Cilia Beat Frequency, Decreased

107-02-8

HGINCPLSRVDWNT-UHFFFAOYSA-N

Acrolein

2-Propenal 2-Propen-1-al 2-Propen-1-one acrilaldehido Acroleina Acrylaldehyd Acrylaldehyde Acrylic aldehyde Allyl aldehyde Aqualin Magnacide B Magnacide H NSC 8819 Prop-2-en-1-al Propenal UN 1092

DTXSID5020023

10028-15-6

CBENFWSGALASAD-UHFFFAOYSA-N

Ozone

Atmospheric ozone Healozone Oxygen, mol. Ozone(16O16O16O) Triatomic oxygen

DTXSID0021098

NOCAS

Cigarette smoke

DTXSID5035038

10102-44-0

JCXJVPUVTGWSNB-UHFFFAOYSA-N

Nitrogen dioxide

Bioxido de Nitrogeno dioxido de nitrogeno Dioxyde d'azote Nitrite radical Nitrito NITROGEN PEROXIDE Stickstoffdioxid UN 1067

DTXSID7020974

NOCAS

Diesel engine exhaust

Diesel Exhaust DE

DTXSID1024043

75-07-0

IKHGUXGNUITLKF-UHFFFAOYSA-N

Acetaldehyde

Ethanal acetaldehido Acetaldehyd Acetic aldehyde Ethyl aldehyde NSC 7594 UN 1089

DTXSID5039224

54-11-5

SNICXCGAKADSCV-JTQLQIEISA-N

Nicotine

Nicotine alkaloid Pyridine, 3-[(2S)-1-methyl-2-pyrrolidinyl]- (-)-(S)-Nicotine (-)-3-(1-Methyl-2-pyrrolidyl)pyridine (-)-Nicotine (-)-β-Pyridyl-α-N-methylpyrrolidine (S)-(-)-Nicotine (S)-3-(1-Methyl-2-pyrrolidinyl)pyridine (S)-Nicotine 3-[(2S)-1-Methyl-2-pyrrolidinyl]pyridine Flux Maag Habitrol l-Nicotine Nicabate Nicoderm Nicolan Niconil Nicopatch Nicorette Nicotell TTS Nicotin nicotina NICOTINE, Nicotinell Nicotrol NSC 5065 Pyridine, 3-(1-methyl-2-pyrrolidinyl)-, (S)- Tabazur UN 1654 XL All Insecticide

DTXSID1020930

7446-09-5

RAHZWNYVWXNFOC-UHFFFAOYSA-N

Sulfur dioxide

SO2 dioxido de azufre Dioxyde de soufre Fermenticide liquid Schwefeldioxid SULFUR DIOXIDE, LIQUID Sulfur superoxide Sulfurous acid anhydride Sulfurous anhydride Sulfurous oxide sulphur dioxide UN 1079

DTXSID6029672

50-00-0

WSFSSNUMVMOOMR-UHFFFAOYSA-N

Formaldehyde

Fannoform Floguard 1015 formaldehido Formaldehyd Formalin LM Formalin Taisei Formalith Formic aldehyde Lysoform Methaldehyde Methanal Methyl aldehyde Methylene oxide Morbicid NSC 298885 Optilyse Oxomethane Oxymethylene Superlysoform UN 1198 UN 2209 Caswell No. 465 EINECS 200-001-8 EPA Pesticide Chemical Code 043001 Formaldehyde, gas Formalin 40 NCI-C02799 RCRA waste number U122 Aldehyd mravenci Aldehyde formique Aldeide formica Formalin-loesungen Oplossingen UNII-1HG84L3525 Formalaz

DTXSID7020637

10102-43-9

MWUXSHHQAYIFBG-UHFFFAOYSA-N

Nitric oxide

Nitric oxide (NO) Amidogen, oxo- monoxido de nitrogeno Monoxyde d'azote Nitric oxide trimer Nitrogen monooxide nitrogen monoxide Nitrogen(II) oxide Nitrosyl radical Oxido nitrico Stickstoffmonoxid UN 1660

DTXSID1020938

60-35-5

DLFVBJFMPXGRIB-UHFFFAOYSA-N

Acetamide

Acetamid acetamida Acetic acid amide Acetimidic acid Ethanamide Ethanimidic acid Methanecarboxamide NSC 25945

DTXSID7020005

103-90-2

RZVAJINKPMORJF-UHFFFAOYSA-N

Acetaminophen

4-Acetamidophenol APAP Paracetamol 4-hydroxyacetanilide Acetamide, N-(4-hydroxyphenyl)- 4-(Acetylamino)phenol 4-(N-Acetylamino)phenol 4-Acetaminophenol 4'-Hydroxyacetanilide Abensanil Acetagesic Acetalgin ACETAMIDE, N-(4-HYDROXYPHENYL) Acetaminofen Acetanilide, 4'-hydroxy- ACETANILIDE, 4-HYDROXY- Algotropyl Alvedon Anaflon Apamide Banesin Ben-u-ron Bickie-mol Biocetamol Cetadol Citramon P Claratal Clixodyne Dafalgan Daphalgan Dial-a-gesic Disprol Doliprane Dolprone Dymadon Efferalgan Endophy Febrilex Febrilix Febro-Gesic Febrolin Fepanil Finimal Gattaphen T Gelocatil Gutte Enteric Homoolan Jin Gang Lestemp Liquagesic Lonarid Lyteca Syrup Minoset Momentum N-(4-Hydroxyphenyl)acetamide N-Acetyl-4-aminophenol N-Acetyl-4-hydroxyaniline N-Acetyl-p-aminophenol Napafen Naprinol Nobedon NSC 109028 NSC 3991 Ortensan p-(Acetylamino)phenol p-Aceaminophenol Pacemol p-Acetamidophenol p-Acetoaminophen P-ACETYLAMINOPHENOL Paldesic panadeine Panadol Panadol Actifast Panadol Extend Panaleve Panasorb Panodil Paracetamol DC Paracetamole Parageniol Paramol Paraspen Parelan Pasolind N Perfalgan Phenaphen Phendon p-Hydroxyacetanilide Prodafalgan Puerxitong Pyrinazine Resfenol Resprin Rhodapop NCR Salzone Tabalgin Tachipirina Tempanal Tralgon Tylenol TylolHot Valadol Valgesic Vermidon Vick Pyrena

DTXSID2020006

968-81-0

VGZSUPCWNCWDAN-UHFFFAOYSA-N

Acetohexamide

Benzenesulfonamide, 4-acetyl-N-[(cyclohexylamino)carbonyl]- 1-(p-Acetylbenzenesulfonyl)-3-cyclohexylurea 1-[(p-Acetylphenyl)sulfonyl]-3-cyclohexylurea Acetohexamid acetohexamida Dimelin Dimelor Dymelor Gamadiabet Hypoglicil Metaglucina Minoral N-(p-Acetylphenylsulfonyl)-N'-cyclohexylurea Ordimel Tsiklamid Urea, 1-[(p-acetylphenyl)sulfonyl]-3-cyclohexyl-

DTXSID7020007

67-66-3

HEDRZPFGACZZDS-UHFFFAOYSA-N

Chloroform

Trichloromethane Methane, trichloro- CARBON TRICHLORIDE Chloroforme cloroformo Formyl trichloride Methane trichloride Methane,trichloro- NSC 77361 Trichloroform UN 1888

DTXSID1020306

110-00-9

YLQBMQCUIZJEEH-UHFFFAOYSA-N

Furan

Divinylene oxide furanne Furfuran Oxacyclopentadiene Tetrole UN 2389

DTXSID6020646

7429-90-5

XAGFODPZIPBFFR-UHFFFAOYSA-N

AZDRQVAHHNSJOQ-UHFFFAOYSA-N

Aluminum

Aisin Metal Fiber Al 050P-H24 ALC Fine Alcan XI 1391 Almi-Paste SSP 303AR Aloxal 3010 Alpaste 00-0506 Alpaste 0100M Alpaste 0100MA Alpaste 0100M-C Alpaste 0200M Alpaste 0200T Alpaste 0230M Alpaste 0230T Alpaste 0241M Alpaste 0300M Alpaste 0500M Alpaste 0539X Alpaste 0620MS Alpaste 0625TS Alpaste 0638-70C Alpaste 0700M Alpaste 0780M Alpaste 0900M Alpaste 100M Alpaste 100MS Alpaste 100MSR Alpaste 1100M Alpaste 1100MA Alpaste 1100N Alpaste 1100NA Alpaste 1109MA Alpaste 1109MC Alpaste 1200M Alpaste 1200T Alpaste 1260MS Alpaste 1500MA Alpaste 1700NL Alpaste 1810YL Alpaste 1830YL Alpaste 1900M Alpaste 1900XS Alpaste 1950M Alpaste 1950N Alpaste 210N Alpaste 2172EA Alpaste 2173 Alpaste 240T Alpaste 241M Alpaste 417 Alpaste 46-046 Alpaste 4-621 Alpaste 4919 Alpaste 50-63 Alpaste 50-635 Alpaste 51-148B Alpaste 51-231 Alpaste 5205N Alpaste 5207N Alpaste 52-509 Alpaste 52-568 Alpaste 5301N Alpaste 5302N Alpaste 53-119 Alpaste 5422NS Alpaste 54-452 Alpaste 54-497 Alpaste 54-542 Alpaste 55-516 Alpaste 55-519 Alpaste 55-574 Alpaste 5620NS Alpaste 5630NS Alpaste 5640NS Alpaste 56-501 Alpaste 5650NS Alpaste 5653NS Alpaste 5654NS Alpaste 5680N Alpaste 5680NS Alpaste 60-600 Alpaste 60-760 Alpaste 60-768 Alpaste 62-356 Alpaste 6340NS Alpaste 6370NS Alpaste 6390NS Alpaste 640NS Alpaste 65-388 Alpaste 66NLB Alpaste 710N Alpaste 7130N Alpaste 7160N Alpaste 7160NS Alpaste 725N Alpaste 740NS Alpaste 7430NS Alpaste 7580NS Alpaste 7620NS Alpaste 7640NS Alpaste 7670M Alpaste 7670NS Alpaste 7675NS Alpaste 7679NS Alpaste 7680N Alpaste 7680NS Alpaste 76840NS Alpaste 7730N Alpaste 7770N Alpaste 7830N Alpaste 8004 Alpaste 8080N Alpaste 8260NAR Alpaste 891K Alpaste 91-0562 Alpaste 92-0592 Alpaste 93-0595 Alpaste 93-0647 Alpaste 94-2315 Alpaste 95-0570 Alpaste 96-0635 Alpaste 96-2104 Alpaste 97-0510 Alpaste 97-0534 Alpaste AW 520B Alpaste AW 612 Alpaste AW 9800 Alpaste F 795 Alpaste FM 7680K Alpaste FX 440 Alpaste FX 910 Alpaste FZ 0534 Alpaste FZU 40C Alpaste G Alpaste HR 8801 Alpaste HS 2 Alpaste J Alpaste K 9800 Alpaste MC 666 Alpaste MC 707 Alpaste MF 20 Alpaste MG 01 Alpaste MG 1000 Alpaste MG 1300 Alpaste MG 500 Alpaste MG 600 Alpaste MH 6601 Alpaste MH 8801 Alpaste MH 9901 Alpaste MR 7000 Alpaste MR 9000 Alpaste MS 630 Alpaste N 1700NL Alpaste NS 7670 Alpaste O 100N Alpaste O 2130 Alpaste O 300M Alpaste P 0100 Alpaste P 1950 Alpaste S Alpaste SAP 110 Alpaste SAP 414P Alpaste SAP 550N Alpaste SCR 5070 Alpaste TCR 2020 Alpaste TCR 2060 Alpaste TCR 2070 Alpaste TCR 3010 Alpaste TCR 3030 Alpaste TCR 3040 Alpaste TCR 3130 Alpaste TD 200T Alpaste UF 500 Alpaste WB 0230 Alpaste WD 500 Alpaste WJP-U 75C Alpaste WX 0630 Alpaste WX 7830 Alpaste WXA 7640 Alpaste WXM 0630 Alpaste WXM 0650 Alpaste WXM 0660 Alpaste WXM 1415 Alpaste WXM 1440 Alpaste WXM 5422 Alpaste WXM 760b Alpaste WXM 7640 Alpaste WXM 7675 Alpaste WXM-T 60B Alpaste WXM-U 75 Alpaste WXM-U 75C Altop X Aluchrome Ultrafin Super Alumat 1600 Alumet H 30 aluminio Aluminium Aluminium Flake Aluminum 27 Aluminum atom Aluminum element Aluminum Flake PCF 7620 Aluminum granules ALUMINUM METAL/GRANULE ALUMINUM PASTE ALUMINUM PIGMENT ALUMINUM TURNINGS Alumi-paste 640NS Alumipaste 91-0562 Alumipaste 98-1822T Alumipaste AW 620 Alumipaste CR 300 Alumipaste GX 180A Alumipaste GX 201A Alumipaste HR 7000 Alumipaste HR 850 Alumipaste MG 11 Alumipaste MH 8801 Aquamet NPW 2900 Aquapaste 205-5 Aquasilver LPW Astroflake 40 Astroflake Black N 020 Astroflake Black N 070 Astroflake LG 40 Astroflake LG 70 Astroflake Silver N 040 Astroshine NJ 1600 Astroshine T 8990 Atomizalumi VA 200 C.I. PIGMENT METAL 1 Chromal IV Chromal X Decomet 1001/10 Decomet 2018/10 Decomet High Gloss Al 1002/10 Ecka AS 081 Eckart 9155 Eterna Brite 301-1 Eterna Brite 601-1 Eterna Brite 651-1 Eterna Brite EBP 251PA Eterna Brite Primier 251PA Ferro FX 53-038 Friend Color F 500GR-W Friend Color F 500WT Friend Color F 700RE-W Friend Color F 701RE-W Hi Print 60T High Print 60T Hisparkle HS 2 Hydro Paste 8726 Hydrolac WHH 2153 Hydrolan 3560 Hydrolux Reflexal 100 Hydroshine WS 1001 JISA 51010P Kryal Z Lansford 243 LE Sheet 800 Leafing Alpaste LG-H Silver 25 Lunar Al-V 95 Metallux 161 Metallux 2154 Metallux 2192 Metalure Metalure 55350 Metalure L 55350 Metalure L 59510 Metalure W 2001 Metapor Metasheen 1800 Metasheen HR 0800 Metasheen KM 100 Metasheen KM 1000 Metasheen Slurry 1807 Metasheen Slurry 1811 Metasheen Slurry KM 100 Metax G Metax S Mirror Glow 1000 Mirror Glow 600 Mirrorsheen Noral Aluminium Noral Ink Grade Aluminium Obron 10890 Offset FM 4500 Puratronic Reflexal 145 Reynolds 400 Reynolds 4-301 Reynolds 4-591 Reynolds 667 SAP 260PW-HS SAP-FM 4010 SBC 516-20Z Scotchcal 7755SE Serumekku Setanium 50MIS-H8 Siberline ET 2025 Siberline ST 21030E1 Silvar A Silver VT 522 Silverline SSP 353 Silvex 793-20C Sparkle Silver 3141ST Sparkle Silver 3500 Sparkle Silver 3641 Sparkle Silver 5000AR Sparkle Silver 516AR Sparkle Silver 5242AR Sparkle Silver 5245AR Sparkle Silver 5271AR Sparkle Silver 5500 Sparkle Silver 5745 Sparkle Silver 7000AR Sparkle Silver 7005AR Sparkle Silver 7500 Sparkle Silver 960-25E1 Sparkle Silver E 1745AR Sparkle Silver L 1526AR Sparkle Silver Premier 751 Sparkle Silver SS 3130 Sparkle Silver SS 5242AR Sparkle Silver SS 5588 Sparkle Silver SSP 132AR Special PCR 507 Splendal 6001BG Spota Mobil 801 SSP 760-20C Stapa Aloxal PM 2010 Stapa Aloxal PM 3010 Stapa Aloxal PM 4010 Stapa Hydrolac BG 8n.1 Stapa Hydrolac BGH Chromal X Stapa Hydrolac PM Chromal VIII Stapa Hydrolac W 60NL Stapa Hydrolac WH 16 Stapa Hydrolac WH 66NL Stapa Hydrolux 2192 Stapa Hydrolux 8154 Stapa IL Hydrolan 2192-55900G Stapa Metallic R 607 Stapa Metallux 1050 Stapa Metallux 211 Stapa Metallux 212 Stapa Metallux 2196 Stapa Metallux 274 Stapa Mobilux 181 Stapa Offset 3000 Stapa PV 10 Stapa VP 46432G Starbrite 2100 Super Fine 18000 Super Fine 22000 Supramex 2022 Toyo Aluminum 02-0005 Toyo Aluminum 93-3040 Transmet K 102HE Tufflake 3645 Tufflake 5843 UN 1396 US Aluminum 809 Valimet H 2 Valimet H 3 White Silver 7080N White Silver 7130N

DTXSID3040273

7440-43-9

BDOSMKKIYDKNTQ-UHFFFAOYSA-N

Cadmium

Cadimium CADMIUM BLUE CADMIUM, IN PLATTEN, STANGEN, BROCKEN,KOERNER

DTXSID1023940

7439-97-6

QSHDDOUJBYECFT-UHFFFAOYSA-N

Mercury

Liquid silver Mercure MERCURIC METAL TRIPLE DISTILLED mercurio Mercury element Quecksilber Quicksilver UN 2024 UN 2809

DTXSID1024172

7440-61-1

JFALSRSLKYAFGM-UHFFFAOYSA-N

Uranium

Uranium, isotope of mass 238 238U Element UN 2979 (DOT) Uranium I

DTXSID1042522

7440-38-2

RQNWIZPPADIBDY-UHFFFAOYSA-N

Arsenic

As Arsenic black ARSENIC METAL arsenico Grey arsenic UN 1558

DTXSID4023886

7440-22-4

BQCADISMDOOEFD-UHFFFAOYSA-N

Silver

Ag Nanopaste NPS-J 90 Ag Sphere 2 Ag-C-GS Algaedyn Arctic Silver 3 Argentum Astroflake 5 Carey Lea silver Colloidal silver Dotite XA 208 Du Pont 4943 ECM 100AF4810 Enlight 600 Enlight silver plate 600 Epinall Finesphere SVND 102 Fordel DC FP 5369-502 Jelcon SH 1 Jungindai Takasago 300 KS (metal) LCP 1-19SFS Metz 3000-1 Nanomelt AGC-A Nanomelt Ag-XA 301 Nanomelt Ag-XF 301 Nanomelt Ag-XF 301H Nanopaste NPS-J 90 Perfect Silver Puff Silver X 1200 RT 1710S-C1 SD (metal) Shell Silver Silbest E 20 Silbest F 20 Silbest J 18 Silbest TC 12 Silbest TC 20E Silbest TC 25A Silbest TCG 1 Silbest TCG 7 Silcoat AgC 103 Silcoat AgC 2011 Silcoat AgC 209 Silcoat AgC 2190 Silcoat AgC 222 Silcoat AgC 2411 Silcoat AgC 74T Silcoat AgC-A Silcoat AgC-AO Silcoat AgC-B Silcoat AgC-BO Silcoat AgC-D Silcoat AgC-G Silcoat AgC-GS Silcoat AgC-L Silcoat AgC-O Silcoat GS Silcoat RF 200 Silflake 135 Silsphere 514 Silver atom Silver element Silver Flake 1 Silver Flake 25 Silver Flake 52 Silver Flake 7A SILVER FLAKES Silver metal Silvest TCG 11N Technic 299 Technic 450 Techno Alpha 175

DTXSID4024305

7439-96-5

PWHULOQIROXLJO-UHFFFAOYSA-N

Manganese

Colloidal manganese Cutaval Manganese element Manganese fulleride Manganese metal alloy Manganese-55 manganeso

DTXSID2024169

7440-02-0

PXHVJJICTQNCMI-UHFFFAOYSA-N

Nickel

Carbonyl 255 Carbonyl Ni 123 Carbonyl Ni 283 Carbonyl Nickel 123 Carbonyl Nickel 283 Carbonyl Nickel 287 Cerac N 2003 CNS 10 Micron Exmet 4 Ni X-4/0 Fibrex P Incofoam Nickel element NICKEL ROUND ANODES Nicrobraz LM:BNi 2 Ni-Flake 95 Novamet 123 Novamet 4SP Novamet 4SP10 Novamet 525 Novamet CNS 400 Novamet HCA 1 Novamet NI 255 Raney nickel Raney nickel 2800 UN 1325 UN 2881

DTXSID2020925

7440-66-6

HCHKCACWOHOZIP-UHFFFAOYSA-N

Zinc

Zn Asarco L 15 C.I. Pigment Black 16 Merrillite NC-Zinc Rheinzink Stapa TE Zinc AT UF (metal) UN 1436 Zinc dust Zinc Dust 3 Zinc Dust 500 mesh Zinc Dust LS 2 Zinc Dust MCS Zinc Flakes GTT ZINC METAL ZINC MOSSY ZINC STRIP ZINC, MOSSY Zincsalt GTT

DTXSID7035012

GO:0031514

GO motile cilium

HP:0012262

HP Abnormal ciliary motility

VT:0001947

VT mucociliary clearance trait

VT:0002327

VT respiratory function trait

MP:0003674

MP oxidative stress

WIKI occurrence

WIKI decreased

WIKI increased

Acrolein

2017-08-15T09:55:59

2021-09-28T08:23:20

Ozone

2021-07-21T10:18:56

2021-09-28T08:26:52

Cigarette smoke

2021-06-24T07:10:58

2021-09-28T09:07:54

Nitrogen dioxide

2021-09-09T07:26:05

2021-09-28T08:54:40

Diesel engine exhaust

2021-08-06T08:41:15

2021-09-28T08:55:47

Acetaldehyde

2021-07-22T07:51:43

Nicotine

2021-07-22T07:53:07

Sex hormone

2021-09-28T07:57:44

Sulfur dioxide

2021-07-22T09:49:34

Formaldehyde

2021-07-22T09:51:10

PM10

2021-07-22T09:54:46

Nitric oxide

2021-07-22T09:57:38

Acetaminophen

2016-11-29T18:42:26

Chloroform

2016-11-29T18:42:27

furan

2020-05-01T14:35:22

Platinum

2022-02-04T14:36:54

Aluminum

2022-02-04T14:42:11

Cadmium

2017-10-25T08:33:12

Mercury

2016-11-29T18:42:19

Uranium

2021-08-05T14:28:50

Arsenic

2021-04-27T00:15:21

Silver

2022-02-03T11:20:11

Manganese

2022-02-04T14:47:23

Nickel

2022-02-04T14:47:59

Zinc

2022-02-04T15:05:00

nanoparticles

2016-12-21T09:40:06

9606

NCBI Homo sapiens

10090

NCBI Mus musculus

10116

NCBI Rattus norvegicus

9986

NCBI Oryctolagus cuniculus

WCS_9913

common ecological species Bos taurus

10141

NCBI Cavia porcellus

8400

NCBI Lithobates catesbeianus

9825

NCBI Sus scrofa domesticus

9940

NCBI Ovis aries

9612

NCBI Canis lupus

WCS_8400

common ecological species Rana catesbeiana

WCS_9606

common toxicological species human

WikiUser_26

ApacheUser rodents

Cilia Beat Frequency, Decreased

CBF, Decreased

Cellular

Cohesive beating of cilia lining the upper and lower respiratory tract is critical for efficient MCC. CBF is influenced by several factors including changes in the physical and chemical properties of the ASL (especially the periciliary fluid), structural modulation in the cilia, concentration of cyclic nucleotides cAMP and cGMP, and intracellular calcium (Ca2+). Formation of cyclic nucleotides such as cGMP is mediated by nitric oxide (NO), which is released by an enzyme family of nitric oxide synthases (NOSs) when the substrate L-arginine (L-Arg) is transformed to L-citrulline. NO activates its receptor protein, soluble guanylate cyclase (sGC), which catalyzes formation of cGMP from guanosine triphosphate (GTP). cGMP then activates protein kinase G (PKG) which has been implicated in the regulation of CBF (Jiao et al., 2011; Li et al., 2000). NO-dependent stimulation of CBF has also been associated with an increase in cAMP-dependent protein kinase A (PKA) (Di Benedetto et al., 1991; Lansley et al., 1992; Salathe et al., 1993; Sanderson and Dirksen, 1989; Schmid et al., 2007; Sisson et al., 1999; Uzlaner and Priel, 1999). An increase in intracellular endogenous cAMP was observed after treatment with isobutyl-1-methylxanthine that also increased CBF (Tamaoki et al., 1989). cAMP accumulation in the airway cilia has been shown to be dependent on Ca2+–calmodulin-dependent PDE1A and indirectly regulates CBF (Kogiso et al., 2018). Increase in CBF after treatment with NO substrate, L-arginine and inhibition of CBF by a NOS inhibitor, N-omega-nitro-L-arginine methyl ester (L-NAME) further provides evidence for the role of NO in increasing CBF (Jiao J. et al., 2011; Sisson J. H., 1995; Uzlaner and Priel, 1999; Yang et al., 1997).  Modulation of CBF is not always accompanied by changes in cAMP levels. PKC activators, phorbol 12-myristate 13-acetate and L-o~-dioctanoylglycerol have been shown to decrease CBF in a concentration- and time-dependent manner in rabbit tracheal epithelial cells (Kobayashi et al., 1989). CBF has been shown to decrease after exposure to inhaled oxidants such as cigarette smoke across different species. A study with 120 subjects showed a significant decrease in nasal CBF following exposure to tobacco smoke (Agius et al., 1998). Exposure to cigarette smoke extract lead to reduction in forskolin-induced CBF in human sinonasal epithelium (Cohen et al., 2009) and  isoproterenol- and methacholine-induced CBF in human adenoid tissues (Wang et al., 2012). This decrease in CBF and unresponsiveness to beta-agonist stimulation occurs in parallel to PKC activation and has been shown to be dependent on the duration of exposure to cigarette smoke in mice (Simet et al., 2010). Normal human bronchial epithelial cells exposed to aerosolized nicotine showed decreased CFTR and BK conductance, impaired CBF, ASL volume, and decreased expression of FOXJ1 and KCNMA1 (Garcia-Arcos et al., 2016).  A concentration-dependent decrease in CBF has been observed after treatment with aldehydes. For example inhibition of cilia ATPase activity was observed after treatment with acetaldehyde, in ciliated bovine bronchial epithelial cells (Sisson et al., 1991). Acrolein, an aldehyde in the gas phase of cigarette smoke, induced ciliostasis at high concentrations (> 1 mM), after 5 min of treatment, and cellular necrosis after 3 hr. However, at lower concentrations (from 0.5‒1 mM), acrolein transiently reduced the CBF to 4 Hz (Romet et al., 1990).

There is no standardized method for measuring CBF. Digital high-speed video imaging with a manual count of CBF in slow motion video play is the most commonly used method for CBF measurement (Kim et al., 2011; Peabody et al., 2018). Photometry and video-microscopy have been used to measure CBF in vitro and ex vivo, including in ciliated bovine bronchial epithelial cells (Allen-Gipson et al., 2011; Sisson et al., 2003; Uzlaner and Priel, 1999), normal human bronchial epithelial cells (Feriani et al., 2017), human nasal epithelial cells (Dimova et al., 2005; Min et al., 1999b), human nasal ciliated epithelium (nasal brushings) (Agius et al., 1998), and mouse tracheal rings (Simet et al., 2010). CBF measurement in vitro generally involves mounting the tissue at the air-liquid interface on a stage followed by microscopic analysis and acquisition of images and/or video recordings of beating cilia. For in vivo and ex vivo measurements, Doppler optical coherence tomography (D-OCT) can also be applied, a mesoscopic non-contact imaging modality that provides high-resolution tomographic images and detects micromotion simultaneously (Jing et al., 2017). D-OCT has been used to quantitatively measure CBF in ex vivo rabbit tracheal cultures (Lemieux et al., 2015).

Age-dependent decreases in CBF have been demonstrated in several species (e.g. guinea pigs, mice, and human) (Bailey et al., 2014; Grubb et al., 2016; Ho et al., 2001; Joki and Saano, 1997; Paul et al., 2013). In a study with 46 healthy subjects with a wide age distribution (mean 42, range 19–81 years), age was found to be negatively associated with airway clearance of inhaled 6-μm Teflon particles (Svartengren et al., 2005). Female hormones, i.e. progesterone and estrogen, have been shown to have direct effect on CBF, i.e., progesterone reduces CBF, 17β-estradiol and progesterone receptor antagonists counteract progesterone effects, but estradiol alone has also been shown to have no effect on CBF. However, the mechanism by which these hormones modulate CBF is yet to be elucidated (Jain et al., 2012; Jia et al., 2011).

UBERON:0000115

UBERON lung epithelium

CL:0005012

CL multi-ciliated epithelial cell

Moderate Mixed

High

All life stages

High High Moderate High High Moderate High

Agius, A. M., L. A. Smallman, and A. L. Pahor (1998). Age, smoking and nasal ciliary beat frequency. Clin. Otolaryngol. Allied Sci. 23, 227-230. Allen-Gipson, D.S., Blackburn, M.R., Schneider, D.J., Zhang, H., Bluitt, D.L., Jarrell, J.C., et al. (2011). Adenosine activation of A(2B) receptor(s) is essential for stimulated epithelial ciliary motility and clearance. Am. J. Physiol. Lung Cell. Mol. Physiol. 301, L171-L180. Bailey, K.L., Bonasera, S.J., Wilderdyke, M., Hanisch, B.W., Pavlik, J.A., Devasure, J., et al. (2014). Aging causes a slowing in ciliary beat frequency, mediated by PKCε. Am. J. Physiol. Lung Cell. Mol. Physiol. 306, L584-L589. Cohen, N.A., Zhang, S., Sharp, D.B., Tamashiro, E., Chen, B., Sorscher, E.J., et al. (2009). Cigarette smoke condensate inhibits transepithelial chloride transport and ciliary beat frequency. Laryngoscope 119, 2269-2274. Di Benedetto, G., Manara-Shediac, F.S. and Mehta, A. (1991). Effect of cyclic AMP on ciliary activity of human respiratory epithelium. Eur. Respir. J. 4, 789-795. Dimova, S., Maes, F., Brewster, M.E., Jorissen, M., Noppe, M. and Augustijns, P. (2005). High-speed digital imaging method for ciliary beat frequency measurement. J. Pharmacy Pharmacol 57, 521-526. Feriani, L., Juenet, M., Fowler, C.J., Bruot, N., Chioccioli, M., Holland, S.M., et al. (2017). Assessing the Collective Dynamics of Motile Cilia in Cultures of Human Airway Cells by Multiscale DDM. Biophys. J. 113, 109-119. Garcia-Arcos, I., Geraghty, P., Baumlin, N., Campos, M., Dabo, A.J., Jundi, B., et al. (2016). Chronic electronic cigarette exposure in mice induces features of COPD in a nicotine-dependent manner. Thorax 71, 1119-1129. Gosepath, J., Schaefer, D., Brommer, C., Klimek, L., Amedee, R.G., and Mann, W.J. (2000). Subacute Effects of Ozone Exposure on Cultivated Human Respiratory Mucosa. Am. J. Rhinol. 14, 411-418.  Grubb, B.R., Livraghi-Butrico, A., Rogers, T.D., Yin, W., Button, B. and Ostrowski, L.E. (2016). Reduced mucociliary clearance in old mice is associated with a decrease in Muc5b mucin. Am. J. Physiol. Lung Cell. Mol. Physiol. 310, L860-L867. Ho, J.C., Chan, K.N., Hu, W.H., Lam, W.K., Zheng, L., Tipoe, G.L., et al. (2001). The Effect of Aging on Nasal Mucociliary Clearance, Beat Frequency, and Ultrastructure of Respiratory Cilia. Am. J. Respir. Crit. Care Med. 163, 983-988. Jain, R., Ray, J.M., Pan, J.-H. and Brody, S.L. (2012). Sex hormone-dependent regulation of cilia beat frequency in airway epithelium. Am. J. Respir. Crit. Care Med. 46, 446-453. Jia, S., Zhang, X., He, D.Z., Segal, M., Berro, A., Gerson, T., et al., 2011. Expression and Function of a Novel Variant of Estrogen Receptor–α36 in Murine Airways. Am. J. Respir. Cell Mol. Biol. 45, 1084-1089. Jiao, J., Wang, H., Lou, W., Jin, S., Fan, E., Li, Y., et al. (2011). Regulation of ciliary beat frequency by the nitric oxide signaling pathway in mouse nasal and tracheal epithelial cells. Exp. Cell Res. 317, 2548-2553. Jing, J.C., Chen, J.J., Chou, L., Wong, B.J.F. and Chen, Z. (2017). Visualization and Detection of Ciliary Beating Pattern and Frequency in the Upper Airway using Phase Resolved Doppler Optical Coherence Tomography. Sci. Rep. 7, 8522-8522. Joki, S. and Saano, V. (1997). Influence of ageing on ciliary beat frequency and on ciliary response to leukotriene D4 in guinea‐pig tracheal epithelium. Clin. Exp. Pharmacol. Physiol. 24, 166-169. Kim, W., Han, T.H., Kim, H.J., Park, M.Y., Kim, K.S. and Park, R.W. (2011). An Automated Measurement of Ciliary Beating Frequency using a Combined Optical Flow and Peak Detection. J. Healthc. Inform. Res. 17, 111-119. Knoll, M., Shaoulian, R., Magers, T. and Talbot, P. (1995). Ciliary beat frequency of hamster oviducts is decreased in vitro by exposure to solutions of mainstream and sidestream cigarette smoke. Biol. Reprod. 53, 29-37. Kobayashi, K., Tamaoki, J., Sakai, N., Chiyotani, A. and Takizawa, T. (1989). Inhibition of ciliary activity by phorbol esters in rabbit tracheal epithelial cells. Lung 167, 277-284. Kogiso, H., Hosogi, S., Ikeuchi, Y., Tanaka, S., Inui, T., Marunaka, Y., et al. (2018). [Ca(2+) ]i modulation of cAMP-stimulated ciliary beat frequency via PDE1 in airway ciliary cells of mice. Exp. Physiol. 103, 381-390. Lansley, A.B., Sanderson, M.J. and Dirksen, E.R. (1992). Control of the beat cycle of respiratory tract cilia by Ca2+ and cAMP. Am. J. Physiol. 263, L232-242. Lemieux, B.T., Chen, J.J., Jing, J., Chen, Z. and Wong, B.J.F. (2015). Measurement of ciliary beat frequency using Doppler optical coherence tomography. Int. Forum Allergy Rhinol. 5, 1048-1054. Li, D., Shirakami, G., Zhan, X. and Johns, R.A. (2000). Regulation of ciliary beat frequency by the nitric oxide-cyclic guanosine monophosphate signaling pathway in rat airway epithelial cells. Am. J. Respir. Cell Mol. Biol. 23, 175-181. Min, Y.-G., Ohyama, M., Lee, K.S., Rhee, C.-S., Oh, S.H., Sung, M.-W., et al. (1999). Effects of free radicals on ciliary movement in the human nasal epithelial cells. Auris Nasus Larynx 26, 159-163. Paul, P., Johnson, P., Ramaswamy, P., Ramadoss, S., Geetha, B. and Subhashini, A.S. (2013). The Effect of Ageing on Nasal Mucociliary Clearance in Women: A Pilot Study. ISRN Pulmonology 2013, 5. Peabody, J.E., Shei, R.-J., Bermingham, B.M., Phillips, S.E., Turner, B., Rowe, S.M., et al. (2018). Seeing cilia: imaging modalities for ciliary motion and clinical connections. Am. J. Physiol. Lung Cell. Mol. Physiol. 314, L909-L921. Romet, S., Dubreuil, A., Baeza, A., Moreau, A., Schoevaert, D. and Marano, F. (1990). Respiratory tract epithelium in primary culture: Effects of. Toxicol. In Vitro 4, 399-402. Salathe, M., Pratt, M.M. and Wanner, A. (1993). Cyclic AMP-dependent phosphorylation of a 26 kD axonemal protein in ovine cilia isolated from small tissue pieces. Am. J. Respir. Cell Mol. Biol. 9, 306-314. Sanderson, M.J. and Dirksen, E.R. (1989). Mechanosensitive and beta-adrenergic control of the ciliary beat frequency of mammalian respiratory tract cells in culture. Am. Rev. Respir. Dis. 139, 432-440. Schmid, A., Sutto, Z., Nlend, M.-C., Horvath, G., Schmid, N., Buck, J., et al. (2007). Soluble Adenylyl Cyclase Is Localized to Cilia and Contributes to Ciliary Beat Frequency Regulation via Production of cAMP. J. Gen. Physiol. 130, 99-109. Schmid, A., Baumlin, N., Ivonnet, P., Dennis, J.S., Campos, M., Krick, S., et al. (2015). Roflumilast partially reverses smoke-induced mucociliary dysfunction. Respir. Res. 16, 135. Simet, S.M., Sisson, J.H., Pavlik, J.A., Devasure, J.M., Boyer, C., Liu, X., et al. (2010). Long-term cigarette smoke exposure in a mouse model of ciliated epithelial cell function. Am. J. Respir. Cell Mol. Biol. 43, 635-640. Sisson, J.H. (1995). Ethanol stimulates apparent nitric oxide-dependent ciliary beat frequency in bovine airway epithelial cells. Am. J. Physiol. 268, L596-600. Sisson, J.H., May, K. and Wyatt, T.A. (1999). Nitric oxide-dependent ethanol stimulation of ciliary motility is linked to cAMP-dependent protein kinase (PKA) activation in bovine bronchial epithelium. Alcohol Clin. Exp. Res. 23, 1528-1533. Sisson, J.H., Stoner, J., Ammons, B. and Wyatt, T. (2003). All‐digital image capture and whole‐field analysis of ciliary beat frequency. J. Microsc. 211, 103-111. Sisson, J.H., Tuma, D.J. and Rennard, S.I. (1991). Acetaldehyde-mediated cilia dysfunction in bovine bronchial epithelial cells. Am. J. Physiol. 260, L29-36. Svartengren, M., Falk, R. and Philipson, K. (2005). Long-term clearance from small airways decreases with age. Eur. Respir. J. 26, 609-615. Tamaoki, J., Kondo, M. and Takizawa, T. (1989). Effect of cAMP on ciliary function in rabbit tracheal epithelial cells. J. Appl. Physiol. 66, 1035-1039. Uzlaner, N. and Priel, Z. (1999). Interplay between the NO pathway and elevated [Ca(2+)](i) enhances ciliary activity in rabbit trachea. J. Physiol. 516, 179-190. Wang, L.F., White, D.R., Andreoli, S.M., Mulligan, R.M., Discolo, C.M. and Schlosser, R.J. (2012). Cigarette smoke inhibits dynamic ciliary beat frequency in pediatric adenoid explants. Otolaryngol. Head Neck Surg. 146, 659-663. Yaghi, A., Zaman, A., Cox, G. and Dolovich, M.B. (2012). Ciliary beating is depressed in nasal cilia from chronic obstructive pulmonary disease subjects. Respir. Med. 106, 1139-1147. Yang, B., Schlosser, R.J. and Mccaffrey, T.V. (1997). Signal transduction pathways in modulation of ciliary beat frequency by methacholine. Ann. Otol. Rhinol. Laryngol. 106, 230-236. AOPWiki 2021-07-19T10:19:36

2021-09-10T01:38:13

Mucociliary Clearance, Decreased

MCC, Decreased

Individual

In healthy adults, tracheal mucus movement varies from 4 to >20 mm/min (Stannard and O'Callaghan, 2006), whereas mucociliary clearance (MCC) in the small airways is slower due to the lower number of ciliated cells (fewer cilia) and their shorter length (Foster et al., 1980; Iravani, 1969; Wanner et al., 1996). Since optimal MCC is dependent in multiple factors, including cilia number and structure as well as ASL and mucus properties, any disturbances of these can lead to impaired MCC. While high humidity or infection can enhance MCC, long-term exposure to noxious substances (e.g. cigarette smoke) lead to decreased mucus clearance from the airways. In most instances this is reflected by decreased mucus transport rates or velocities.

In humans, MCC has been assessed traditionally following inhalation of radio-labeled particles such as 99Tcm-labeled polystyrene particles, resin particles or serum albumin and following their clearance at regular intervals by radioimaging using gamma cameras (Agnew et al., 1986; Kärjä et al., 1982). Taking into account inhalation volumes and flow rates, lung airflow, particle deposition and retention, clearance rates can be calculated and effects of e.g. drugs on MCC can be examined. Alternatively, since MCC occurs at a similar rate in the nose to that in trachea and bronchi (Andersen and Proctor, 1983; Rutland and Cole, 1981) and for ease of use, measurements of MCC can be restricted to that of nasal MCC only. Probably one of the simplest methods is the saccharin transit test (STT). For this test, a small particle of saccharin is placed behind the anterior end of the inferior turbinate. The saccharin will be transported by mucociliary action toward the nasopharynx, where its sweet taste is perceived. When MCC is impaired, saccharin transit times will increase, with a 10- to 20-minute delay being considered a clinical sign of decreased MCC. Using the same principle, the test can also be performed or complemented with dyes such as indigo carmine or methylene blue (Deborah and Prathibha, 2014). In experimental animals, MCC has been evaluated by gamma-scintigraphy (Greiff et al., 1990; Hua et al., 2010; Read et al., 1992), fluorescence videography/fluoroscopy (in explanted tracheas etc.) (Grubb et al., 2016; Rogers  et al., 2018), or by 3D-SPECT (Ortiz Belda et al., 2016). Direct observation of particle movement across airway epithelia to determine mucus velocity or transport rates by using a fiberoptic bronchoscope may be helpful when working in larger animals such as dogs (King, 1998). In vitro, freshly excised frog palate preparations have been used to assess cilia function and mucociliary transport by videomicroscopy (Macchione et al., 1995; Macchione et al., 1999; Trindade et al., 2007). Murine and human nasal, bronchial and small airway epithelial models grown at the air-liquid interface are also suitable in vitro test systems for determining mucus transport by tracing inert particle movement with a set-up similar to that used for assessing CBF (Benam et al., 2018; Fliegauf et al., 2013; Knowles and Boucher, 2002; Sears et al., 2015).

High Mixed

High

All life stages

High Moderate Moderate Moderate Moderate Moderate Moderate

Agnew, J., Sutton, P., Pavia, D. and Clarke, S. (1986). Radioaerosol assessment of mucociliary clearance: towards definition of a normal range. Brit. J. Radiol. 59, 147-151. Allegra, L., Moavero, N., and Rampoldi, C. (1991). Ozone-induced impairment of mucociliary transport and its prevention with N-acetylcysteine. Am. J. Med. 91, S67-S71. Andersen, I. and Proctor, D. (1983). Measurement of nasal mucociliary clearance. Eur. J. Respir. Dis. Suppl. 127, 37-40. Baby, M.K., Muthu, P.K., Johnson, P., and Kannan, S. (2014). Effect of cigarette smoking on nasal mucociliary clearance: A comparative analysis using saccharin test. Lung India 31, 39-42.  Benam, K.H., Vladar, E.K., Janssen, W.J. and Evans, C.M. (2018). Mucociliary defense: emerging cellular, molecular, and animal models. Ann. Am. Thorac. Soc. 15, S210-S215. Deborah, S. and Prathibha, K., 2014. Measurement of nasal mucociliary clearance. Clin. Res. Pulmonol. 2, 1019. Dülger, S., Akdeniz, Ö., Solmaz, F., Şengören Dikiş, Ö., and Yildiz, T. (2018). Evaluation of nasal mucociliary clearance using saccharin test in smokers: A prospective study. Clin. Respir. J. 12, 1706-1710.  Fliegauf, M., Sonnen, A.F.P., Kremer, B. and Henneke, P. (2013). Mucociliary Clearance Defects in a Murine In Vitro Model of Pneumococcal Airway Infection. PloS ONE 8, e59925. Fló-Neyret, C., Lorenzi-Filho, G., Macchione, M., Garcia, M.L.B. and Saldiva, P.H.N. (2001). Effects of formaldehyde on the frog's mucociliary epithelium as a surrogate to evaluate air pollution effects on the respiratory epithelium. Braz. J. Med. Biol. Res. 34, 639-643. Foster, W., Langenback, E. and Bergofsky, E. (1980). Measurement of tracheal and bronchial mucus velocities in man: relation to lung clearance. J. Appl. Physiol. 48, 965-971. Greiff, L., Wollmer, P., Erjefält, I., Pipkorn, U. and Persson, C. (1990). Clearance of 99mTc DTPA from guinea pig nasal, tracheobronchial, and bronchoalveolar airways. Thorax 45, 841-845. Grubb, B.R., Livraghi-Butrico, A., Rogers, T.D., Yin, W., Button, B. and Ostrowski, L.E. (2016). Reduced mucociliary clearance in old mice is associated with a decrease in Muc5b mucin. Am. J. Physiol. Lung Cell. Mol. Physiol. 310, L860-L867. Habesoglu, M., Demir, K., Yumusakhuylu, A.C., Sahin Yilmaz, A., and Oysu, C. (2012). Does passive smoking have an effect on nasal mucociliary clearance? Otolaryngol Head Neck Surg. 147, 152-156. Hua, X., Zeman, K.L., Zhou, B., Hua, Q., Senior, B.A., Tilley, S.L., et al. (2010). Noninvasive real-time measurement of nasal mucociliary clearance in mice by pinhole gamma scintigraphy. J. Appl. Physiol. 108, 189-196. Iravani, J. (1969). Zum Mechanismus der Ortsabhängigkeit der Flimmeraktivität im Bronchialbaum/Location-Dependent Activity of the Ciliary Movement in the Bronchial Tree and its Possible Mechanism. In: Habermann E. et al. (eds) Naunyn Schmiedebergs Archiv für Pharmakologie. Springer, Berlin, Heidelberg. Kakinoki Y, Ohashi Y, Tanaka A, Washio Y, Yamada K, Nakai Y, Morimoto K. (1998). Nitrogen dioxide compromises defence functions of the airway epithelium. Acta Oto-Laryngol. 118, 221-226. Kärjä, J., Nuutinen, J. and Karjalainen, P. (1982). Radioisotopic Method for Measurement of Nasal Mucociliary Activity. Arch. Otolaryngol. 108, 99-101. King, M. (1998). Experimental models for studying mucociliary clearance. Eur. Respir. J. 11, 222-228. Knorst, M.M., Kienast, K., Riechelmann, H., Müller-Quernheim, J. and Ferlinz, R. (1994). Effect of sulfur dioxide on mucociliary activity and ciliary beat frequency in guinea pig trachea. Int. Arch. Occup. Environm. Health 65, 325-328. Knowles, M.R. and Boucher, R.C. (2002). Mucus clearance as a primary innate defense mechanism for mammalian airways. J. Clin. Invest. 109, 571-577. Macchione, M., Guimarães, E., Saldiva, P. and Lorenzi-Filho, G. (1995). Methods for studying respiratory mucus and mucus clearance. Braz. J. Med. Biol Res. 28, 1347. Macchione, M., Oliveira, A.P., Gallafrio, C.T., Muchão, F.P., Obara, M.T., Guimarães, E.T., et al. (1999). Acute effects of inhalable particles on the frog palate mucociliary epithelium. Environm. Health Persp. 107, 829-833. Morgan, K., Patterson, D. and Gross, E. (1986). Responses of the nasal mucociliary apparatus of F-344 rats to formaldehyde gas. Toxicol. Appl. Pharmacol. 82, 1-13. Morgan, K.T., Patterson, D.L. and Gross, E.A. (1984). Frog palate mucociliary apparatus: structure, function, and response to formaldehyde gas. Fund. Appl. Toxicol. 4, 58-68. Ortiz Belda, J.L., Ortiz, A., Milara Payá, J., Armengot Carceller, M., Sanz García, C., Compañ Quilis, D., et al. (2016). Evaluation of Mucociliary Clearance by Three Dimension Micro-CT-SPECT in Guinea Pig: Role of Bitter Taste Agonists. Plos ONE 11, e0164399. Pagliuca, G., Rosato, C., Martellucci, S., De Vincentiis, M., Greco, A., Fusconi, M., et al. (2015). Cytologic and functional alterations of nasal mucosa in smokers: temporary or permanent damage? Otolaryngol Head Neck Surg 152, 740-745. Proença, M., Xavier, R.F., Ramos, D., Cavalheri, V., Pitta, F., and Ramos, E.C. (2011). Immediate and short term effects of smoking on nasal mucociliary clearance in smokers. Revista Portuguesa de Pneumologia (English Edition) 17), 172-176. Read, R.C., Roberts, P., Munro, N., Rutman, A., Hastie, A., Shryock, T., et al. (1992). Effect of Pseudomonas aeruginosa rhamnolipids on mucociliary transport and ciliary beating. J. Appl. Physiol. 72, 2271-2277. Rogers, T.D., Ostrowski, L.E., Livraghi-Butrico, A., Button, B. and Grubb, B.R., 2018. Mucociliary clearance in mice measured by tracking trans-tracheal fluorescence of nasally aerosolized beads. Sci. Rep. 8, 1-12. Rutland, J. and Cole, P.J. (1981). Nasal mucociliary clearance and ciliary beat frequency in cystic fibrosis compared with sinusitis and bronchiectasis. Thorax 36, 654-658. Sears, P.R., Yin, W.-N. and Ostrowski, L.E. (2015). Continuous mucociliary transport by primary human airway epithelial cells in vitro. Am. J. Physiol. Lung Cell. Mol. Physiol. 309, L99-L108. Solak, I., Marakoglu, K., Pekgor, S., Kargin, N.C., Alataş, N., and Eryilmaz, M.A. (2018). Nasal mucociliary activity changes in smokers. Konuralp Med. J. 10, 269-275. Stannard, W. and O'callaghan, C. (2006). Ciliary function and the role of cilia in clearance. J. Aerosol Med. 19, 110-115. Trindade, S.H.K., De Mello Júnior, J.F., De Godoy Mion, O., Lorenzi-Filho, G., Macchione, M., Guimarães, E.T., et al. (2007). Methods for Studying Mucociliary Transport. Braz. J. Otorhinolaryngol. 73, 704-712. Wanner, A., Salathe, M. and O'riordan, T.G. (1996). Mucociliary clearance in the airways. Am. J. Respir. Crit. Care Med. 154, 1868-1902. Xavier, R.F., Ramos, D., Ito, J.T., Rodrigues, F.M., Bertolini, G.N., Macchione, M., et al. (2013). Effects of cigarette smoking intensity on the mucociliary clearance of active smokers. Respiration 86, 479-485.  Yadav, J., and Kaushik, G. (2014). K Ranga R. Passive smoking affects nasal mucociliary clearance. J. Indian Acad. Clin. Med. 15, 96-99. Yeates, D.B., Katwala, S.P., Daugird, J., Daza, A.V. and Wong, L.B. (1997). Excitatory and inhibitory neural regulation of tracheal ciliary beat frequency (CBF) activated by ammonia vapour and SO2. Ann. Occup. Hyg. 41, 736-744. AOPWiki 2021-07-19T10:21:38

2021-09-10T07:19:28

Decrease, Lung function

Decreased lung function

Individual

Lung function is a clinical term referring to the physiological functioning of the lungs, most often in association with the tests used to assess it. Lung function loss can be caused by acute or chronic exposure to airborne toxicants or by an intrinsic disease of the respiratory system.  Although signs of cellular injury are typically exhibited first in the nose and larynx, alveolar-capillary barrier breakdown may ultimately arise and result in local edema (Miller and Chang, 2003). Clinically, bronchoconstriction and hypoxia are seen in the acute phase, with affected subjects exhibiting shortness of breath (dyspnea) and low blood oxygen saturation, and with reduced lung function indices of airflow, lung volume and gas exchange (Hert and Albert, 1994; and How it is Measured or Detected;). When alveolar damage is extensive, the reduced lung function can develop into acute respiratory distress syndrome (ARDS). This severe compromise of lung function is reflected by decreased gas exchange indices (PaO2/FIO2 ≤200 mmHg, due to hypoxemia and impaired excretion of carbon dioxide), increased pulmonary dead space and decreased respiratory compliance (Matthay et al., 2019). Acute inhalation exposures to chemical irritants such as ammonia, hydrogen chloride, nitrogen oxides and ozone typically cause local edema that manifests as dyspnea and hypoxia. In cases where a breakdown of the alveolar capillary function ensues, ARDS develops. ARDS has a particularly high risk of mortality, estimated to be 30-40% (Gorguner and Akgun, 2010; Matthay et al., 2018; Reilly et al., 2019). Lung function decrease due to reduction in lung volume is seen in pulmonary fibrosis, which can be linked to chronic exposures to e.g. silica, asbestos, metals, agricultural and animal dusts (Meltzer and Noble, 2008; Cheresh et al., 2013; Cosgrove, 2015; Trethewey and Walters, 2018). Additionally. decreased lung function occurs in pleural disease, chest wall and neuromuscular disorders, because of obesity and following pneumectomy (Moore, 2012). Decreased lung function can also be a result of narrowing of the airways by inflammation and mucus plugging resulting in airflow limitation. Decreased lung function is a feature of obstructive pulmonary diseases (e.g. asthma, COPD) and linked to a multitude of causes, including chronic exposure to cigarette smoke, dust, metals, organic solvents, asbestos, pathogens or genetic factors.

Pulmonary function tests are a group of tests that evaluate several parameters indicative of lung size, air flow and gas exchange. Decreased lung function can manifest in different ways, and individual circumstances, including potential exposure scenarios, determine which test is used. The section outlines the tests used to evaluate lung function in humans (https://www.nhlbi.nih.gov/health-topics/pulmonary-function-tests, accessed 22 March 2021) and in experimental animals. Lung function tests used to evaluate human lung function The most common (“gold standard”) lung function test in human subjects is spirometry. Spirometry results are primarily used for diagnostic purposes, e.g. to discriminate between obstructive and restrictive lung diseases, and for determining the degree of lung function impairment. Specific criteria for spirometry tests have been outlined in the American Thoracic Society (ATS) and the European Respiratory Society (ERS) Task Force guidelines (Graham et al., 2019). These guidelines consist of detailed recommendations for the preparation and conduct of the test, instruction of the person tested, as well as indications and contraindications, and are complemented by additional guidance documents on how to interpret and report the test results (Pellegrino et al., 2005; Culver et al., 2017). Spirometry measures several different parameters during forceful exhalation, including: <ul> <li style="text-align:justify">Forced expiratory volume in 1 s (FEV1), the maximum volume of air that can forcibly be exhaled during the first second following maximal inhalation</li> <li style="text-align:justify">Forced vital capacity (FVC), the maximum volume of air that can forcibly be exhaled following maximal inhalation </li> <li style="text-align:justify">Vital capacity (VC), the maximum volume of air that can be exhaled when exhaling as fast as possible</li> <li style="text-align:justify">FEV1/FVC ratio</li> <li style="text-align:justify">Peak expiratory flow (PEF), the maximal flow that can be exhaled when exhaling at a steady rate</li> <li style="text-align:justify">Forced expiratory flow, also known as mid-expiratory flow; the rates at 25%, 50% and 75% FVC are given</li> <li style="text-align:justify">Inspiratory vital capacity (IVC), the maximum volume of air that can be inhaled after a full expiration</li> </ul> A reduced FEV1, with normal or reduced VC, normal or reduced FVC, and a reduced FEV1/FVC ratio are indices of airflow limitation, i.e., airway obstruction as seen in COPD (Moore, 2012). In contrast, airway restriction is demonstrated by a reduction in FVC, normal or increased FEV1/FVC ratio, a normal spirometry trace and potentially a high PEF (Moore, 2012). Lung capacity or lung volumes can be measured using one of three basic techniques: 1) plethysmography, 2) nitrogen washout, or 3) helium dilution. Plethysmography consists of a series of sequential measurements in a body plethysmograph, starting with the measurement of functional residual capacity (FRC), the volume of gas present in the lung at end-expiration during tidal breathing. Once the FRC is known, expiratory reserve volume (ERV; the volume of gas that can be maximally exhaled from the end-expiratory level during tidal breathing, i.e., the FRC), vital capacity (VC; the volume change at the mouth between the positions of full inspiration and complete expiration), and inspiratory capacity (IC; the maximum volume of air that can be inhaled from FRC) are determined, and total lung capacity (TLC; the volume of gas in the lungs after maximal inspiration, or the sum of all volume compartments) and residual volume (RV; the volume of gas remaining in the lung after maximal exhalation) are calculated (Weinstock and McCannon, 2017). The other two techniques used to measure lung volumes—helium dilution and nitrogen washout—are based on the principle of conservation of mass: [initial gas concentration] x [initial volume of the system] = [final gas concentration] x [final volume of the system]. The nitrogen washout method is based on the fact that nitrogen is present in the air, at a relatively constant amount. The subject is given 100% oxygen to breathe, and the expired gas, which contains nitrogen in the lung at the beginning of the test, is collected. When no more nitrogen is noted in the expirate, the volume of air expired and the entire amount of nitrogen in that volume are measured, and the initial volume of the system (FRC) can be calculated. In the helium dilution method, a known volume and concentration of helium is inhaled by the subject. Helium, an inert gas that is not absorbed significantly from the lungs, is diluted in proportion to the lung volume to which it is added. The final concentration of helium is then measured and FRC calculated (Weinstock and McCannon, 2017). Measurements of lung volumes in humans are technically more challenging than spirometry. However, they complement spirometry (which cannot determine lung volumes) and may be a preferred means of lung function assessment when subject compliance cannot be reasonably expected (e.g. in pediatric subjects) or where forced expiratory maneuvers are not possible (e.g. in patients with advanced pulmonary fibrosis). There are recommended standards for lung volume measurements and their interpretation in clinical practice, issued by the ATS/ERS Task Force (Wanger et al., 2005; Criée et al., 2011). Finally, indices of gas exchange across the alveolar-capillary barrier are tested by diffusion capacity of carbon monoxide (DLCO) studies (also referred to as transfer capacity of carbon monoxide, TLCO). The principle of the test is the increased affinity of hemoglobin to preferentially bind carbon monoxide over oxygen (Weinstock and McCannon, 2017). Complementary to spirometry and lung volume measurements, DLCO provides information about the lung surface area available for gas diffusion. Therefore, it is sensitive to any structural changes affecting the alveoli, such as those accompanying emphysema, pulmonary fibrosis, pulmonary edema, and ARDS. Recommendations for the standardization of the test and its evaluation have been outlined by the ATS/ERS Task Force (Graham et al., 2017). An isolated reduction in DLCO with normal spirometry and in absence of anemia suggests an injury to the alveolar-capillary barrier, as for example seen in the presence of pulmonary emboli or in patients with pulmonary hypertension (Weinstock and McCannon, 2017; Lettieri et al., 2006; Seeger et al., 2013). Reduced DLCO together with airflow obstruction (i.e., reduced FEV1) indicates lung parenchymal damage and is commonly observed in smokers and in COPD patients (Matheson et al., 2007; Harvey et al., 2016), whereas reduced DLCO with airflow restriction is seen in patients with interstitial lung diseases (Dias et al., 2014; Kandhare et al., 2016). Lung function tests used to evaluate experimental animal lung function Because spirometry requires active participation and compliance of the subject, it is not commonly used in animal studies. However, specialized equipment such as the flexiVent system (SCIREQ®) are available for measuring FEV, FVC and PEF in anesthetized and tracheotomized small laboratory animals. Other techniques such as plethysmography or forced oscillation are increasingly preferred for lung function assessment in small laboratory animals (McGovern et al., 2013; Bates, 2017). In small laboratory animals, plethysmography can be used to determine respiratory physiology parameters (minute volume, respiratory rate, time of pause and time of break), lung volume and airway resistance of conscious animals. Both whole body and head-out plethysmography can be applied, although there is a preference for the latter in the context of inhalation toxicity studies, because of its higher accuracy and reliability (OECD, 2018a; Hoymann, 2012). Gas diffusion tests are not frequently performed in animals, because reproducible samplings of alveolar gas are difficult and technically challenging (Reinhard et al., 2002; Fallica et al., 2011). Modifications to the procedure employed in humans have, however, open possibilities to obtain a human-equivalent DLCO measure or the diffusion factor for carbon monoxide (DFCO)—a variable closely related to DLCO, which can inform on potential structural changes in the lungs that have an effect on gas exchange indices (Takezawa et al., 1980; Dalbey et al., 1987; Fallica et al., 2011; Limjunyawong et al., 2015).

Pulmonary function tests reflect the physiological working of the lungs. Therefore, the AO is applicable to a variety of species, including (but not limited to) rodents, rabbits, pigs, cats, dogs, horses and humans, independent of life stage and gender.

High Mixed

High

Adult

High

<div style="text-align:justify"> Ackermann-Liebrich, U., Leuenberger, P., Schwartz, J., Schindler, C., Monn, C., Bolognini, G., et al. (1997). Lung function and long term exposure to air pollutants in Switzerland. Study on Air Pollution and Lung Diseases in Adults (SAPALDIA) Team. Am. J. Resp. Crit. Care Med. 155, 122-129.  Adam, M., Schikowski, T., Carsin, A.E., Cai, Y., Jacquemin, B., Sanchez, M., et al. (2015). Adult lung function and long-term air pollution exposure. ESCAPE: a multicentre cohort study and meta-analysis. Eur. Resp. J. 45, 38-50. Andersen, M.H.G., Frederiksen, M., Saber, A.T., Wils, R.S., Fonseca, A.S., Koponen, I.K., et al. (2019). Health effects of exposure to diesel exhaust in diesel-powered trains. Part. Fibre Toxicol. 16, 21. Ashley, F., Kannel, W.B., Sorlie, P.D., and Masson, R. (1975). Pulmonary function: relation to aging, cigarette habit, and mortality: the Framingham Study. Ann. Int. Med. 82, 739-745. Bates, J.H.T. (2017). CO Bergstra, A.D., Brunekreef, B., and Burdorf, A. (2018). The effect of industry-related air pollution on lung function and respiratory symptoms in school children. Environm. Health 17, 30.  Baumgartner, K.B., Samet, J.M., Coultas, D.B., Stidley, C.A., Hunt, W.C., Colby, T.V., and J.A. Waldron (2000). Occupational and environmental risk factors for idiopathic pulmonary fibrosis: a multicenter case-control study. Collaborating Centers. Am. J. Epidemiol. 152, 307-315. Broekema, M., ten Hacken, N.H., Volbeda, F., Lodewijk, M.E., Hylkema, M.N., Postma, D.S., et al. (2009). Airway epithelial changes in smokers but not in ex-smokers with asthma. Am. J. Resp. Crit. Care Med. 180, 1170-1178. Celli, B. R. (2010). Predictors of mortality in COPD. Respir. Med. 104, 773-779. Cheresh, P., Kim, S.J., Tulasiram, S., and D.W. Kamp (2013). Oxidative stress and pulmonary fibrosis. Biochim. Biophys. Acta, 1832, 1028–1040. Cosgrove, M.P. (2015). Pulmonary fibrosis and exposure to steel welding fume. Occup. Med. 65, 706-712. Criée, C.P., Sorichter, S., Smith, H.J., Kardos, P., Merget, R., Heise, D., Berdel, D., Köhler, D., Magnussen, H., Marek, W. and H. Mitfessel (2011). Body plethysmography–its principles and clinical use. Respir. Med. 105, 959-971. Dalbey, W., Henry, M., Holmberg, R., Moneyhun, J., Schmoyer, R. and S. Lock (1987). Role of exposure parameters in toxicity of aerosolized diesel fuel in the rat. J. Appl. Toxicol. 7, 265-275. Dias, O.M., Baldi, B.G., Costa, A.N., C.R. Carvalho (2014). Combined pulmonary fibrosis and emphysema: an increasingly recognized condition. J. Bras. Pneumol. 40, 304-312.  Fallica, J., Das, S., Horton, M., and W. Mitzner (2011). Application of carbon monoxide diffusing capacity in the mouse lung. J. Appl. Physiol. 110, 1455–1459. Forbes, L.J., Kapetanakis, V., Rudnicka, A.R., Cook, D.G., Bush, T., Stedman, J.R., et al. (2009). Chronic exposure to outdoor air pollution and lung function in adults. Thorax 64, 657-663. 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The variable effect of smoking on pulmonary function. Chest 63, 655-660.  Lee, H. M., Liu, M. A., Barrett-Connor, E., and N. D. Wong (2014). Association of Lung Function with Coronary Heart Disease and Cardiovascular Disease Outcomes in Elderly: The Rancho Bernardo Study. Respir. Med. 108, 1779–1785. Lettieri, C.J., Nathan, S.D., Barnett, S.D., Ahmad, S. and A.F. Shorr (2006). Prevalence and outcomes of pulmonary arterial hypertension in advanced idiopathic pulmonary fibrosis. Chest 129, 746-752. Limjunyawong, N., Fallica, J., Ramakrishnan, A., Datta, K., Gabrielson, M., Horton, M., and W. Mitzner (2015). Phenotyping mouse pulmonary function in vivo with the lung diffusing capacity. JoVE 95, e52216. Matheson, M.C., Raven, J., Johns, D.P., Abramson, M.J. and E.H. Walters (2007). Associations between reduced diffusing capacity and airflow obstruction in community-based subjects. Respir. Med. 101, 1730-1737. Matthay, M.A., Zemans, R.L., Zimmerman, G.A., Arabi, Y.M., Beitler, J.R., Mercat, A., Herridge, M., Randolph, A.G. and C.S. Calfee (2019). Acute respiratory distress syndrome. Nature Reviews Disease Primers 5, 1-22. McGovern, T.K., Robichaud, A., Fereydoonzad, L., Schuessler, T.F., and J.G. Martin (2013) Evaluation of respiratory system mechanics in mice using the forced oscillation technique. JoVE 75, e50172. Meltzer, E.B., and P.W. Noble (2008). Idiopathic pulmonary fibrosis. Orphanet J. Rare Dis. 3, 8. Miller, K. and A. Chang (2003). Acute inhalation injury. Emerg. Med. Clin. N. Am. 21, 533-557. Miller, M.R., Crapo, R., Hankinson, J., Brusasco, V., Burgos, F., Casaburi, R., Coates, A., Enright, P., van der Grinten, C.M., and P. Gustafsson (2005a). General considerations for lung function testing. Eur. Respir. J. 26, 153-161. Miller, M.R., Hankinson, J., Brusasco, V., Burgos, F., Casaburi, R., Coates, A., Crapo, R., Enright, P., van der Grinten, C., and P. Gustafsson (2005b). Standardisation of spirometry. Eur. Respir. J. 26, 319-338. Moore, V.C. (2012). Spirometry: step by step. Breathe 8, 232-240. OECD (2018a). OECD Guidance Document on Inhalation Toxicity Studies, GD 39. OECD (2018b), Test No. 412: Subacute Inhalation Toxicity: 28-Day Study, OECD Guidelines for the Testing of Chemicals, Section 4, OECD Publishing, Paris, https://doi.org/10.1787/9789264070783-en. OECD (2018), Test No. 413: Subchronic Inhalation Toxicity: 90-day Study, OECD Guidelines for the Testing of Chemicals, Section 4, OECD Publishing, Paris, https://doi.org/10.1787/9789264070806-en. Park, Y., Ahn, C., and T.H. Kim (2021) Occupational and environmental risk factors of idiopathic pulmonary fibrosis: a systematic review and meta-analyses. Sci. Rep. 11, 4318. Prada-Dacasa, P., Urpi, A., Sánchez-Benito, L., Bianchi, P., A. Quintana (2020). Measuring Breathing Patterns in Mice Using Whole-body Plethysmography. Bio. Protoc. 10, e3741. Pelkonen, M., Notkola, I.-L., Nissinen, A., Tukiainen, H., and Koskela, H. (2006). Thirty-year cumulative incidence of chronic bronchitis and COPD in relation to 30-year pulmonary function and 40-year mortality: a follow-up in middle-aged rural men. Chest 130, 1129-1137. Pellegrino, R., Viegi, G., Brusasco, V., Crapo, R., Burgos, F., Casaburi, R., Coates, A., van der Grinten, C., Gustafsson, P., and J. Hankinson (2005). Interpretative strategies for lung function tests. Eur. Respir. J. 26, 948-968. Raghu, G., Remy-Jardin, M., Myers, J.L., Richeldi, L., Ryerson, C.J., Lederer, D.J., Behr, J., Cottin, V., Danoff, S.K., Morell, F., and K.R. Flaherty (2018). Diagnosis of idiopathic pulmonary fibrosis. An official ATS/ERS/JRS/ALAT clinical practice guideline. Am. J. Respir. Crit. Care Med. 198, e44-e68. Reilly, J.P., Zhao, Z., Shashaty, M.G., Koyama, T., Christie, J.D., Lanken, P.N., Wang, C., Balmes, J.R., Matthay, M.A., Calfee, C.S. and L.B. Ware (2019). Low to moderate air pollutant exposure and acute respiratory distress syndrome after severe trauma. Am. J. Respir. Crit. Care Med. 199, 62-70. Reinhard. C., Eder, G., Fuchs, H., Ziesenis, A., Heyder, J. and H. Schulz H (2002). Inbred strain variation in lung function. Mamm. Genome 13, 429-437. RP: Measurement of lung function in small animals. J. Appl. Physiol. 123, 1039-1046. Schikowski, T., Sugiri, D., Ranft, U., Gehring, U., Heinrich, J., Wichmann, H.E., et al. (2005). Long-term air pollution exposure and living close to busy roads are associated with COPD in women. Respir. Res. 6, 152.  Seeger, W., Adir, Y., Barberà, J.A., Champion, H., Coghlan, J.G., Cottin, V., De Marco, T., Galiè, N., Ghio, S., Gibbs, S. and F.J. Martinez (2013). Pulmonary hypertension in chronic lung diseases. J. Am. Coll. Cardiol. 62 Suppl. 25, D109-D116. Sin, D. D., Wu, L., and S. P. Man (2005). The relationship between reduced lung function and cardiovascular mortality: a population-based study and a systematic review of the literature. Chest 127, 1952-1959. Takezawa, J., Miller, F.J. and J.J. O'Neil (1980). Single-breath diffusing capacity and lung volumes in small laboratory mammals. J. Appl. Physiol. 48, 1052-1059. Tantisuwat, A., and Thaveeratitham, P. (2014). Effects of smoking on chest expansion, lung function, and respiratory muscle strength of youths. J. Phys. Ther. Sci. 26, 167-170.  Trethewey, S. P., and G. I. Walters (2018). The Role of Occupational and Environmental Exposures in the Pathogenesis of Idiopathic Pulmonary Fibrosis: A Narrative Literature Review. Medicina (Kaunas, Lithuania) 54, 108. Tsui, H.-C., Chen, C.-H., Wu, Y.-H., Chiang, H.-C., Chen, B.-Y., and Guo, Y.L. (2018). Lifetime exposure to particulate air pollutants is negatively associated with lung function in non-asthmatic children. Environ. 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2021-09-08T04:54:28

Oxidative Stress

Molecular

Oxidative stress is defined as an imbalance in the production of reactive oxygen species (ROS) and antioxidant defenses. High levels of oxidizing free radicals can be very damaging to cells and molecules within the cell.  As a result, the cell has important defense mechanisms to protect itself from ROS. For example, Nrf2 is a transcription factor and master regulator of the oxidative stress response. During periods of oxidative stress, Nrf2-dependent changes in gene expression are important in regaining cellular homeostasis (Nguyen, et al. 2009) and can be used as indicators of the presence of oxidative stress in the cell. In addition to the directly damaging actions of ROS, cellular oxidative stress also changes cellular activities on a molecular level. Redox sensitive proteins have altered physiology in the presence and absence of ROS, which is caused by the oxidation of sulfhydryls to disulfides (2SH àSS) on neighboring amino acids (Antelmann and Helmann 2011). Importantly Keap1, the negative regulator of Nrf2, is regulated in this manner (Itoh, et al. 2010). ROS also undermine the mitochondrial defense system from oxidative damage. The antioxidant systems consist of superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase, as well as antioxidants such as α-tocopherol and ubiquinol, or antioxidant vitamins and minerals including vitamin E, C, carotene, lutein, zeaxanthin, selenium, and zinc (Fletcher, 2010). The enzymes, vitamins and minerals catalyze the conversion of ROS to non-toxic molecules such as water and O2. However, these antioxidant systems are not perfect and endogenous metabolic processes and/or exogenous oxidative influences can trigger cumulative oxidative injuries to the mitochondria, causing a decline in their functionality and efficiency, which further promotes cellular oxidative stress (Balasubramanian, 2000; Ganea & Harding, 2006; Guo et al., 2013; Karimi et al., 2017). However, an emerging viewpoint suggests that ROS-induced modifications may not be as detrimental as previously thought, but rather contribute to signaling processes (Foyer et al., 2017).  Protection against oxidative stress is relevant for all tissues and organs, although some tissues may be more susceptible. For example, the brain possesses several key physiological features, such as high O2 utilization, high polyunsaturated fatty acids content, presence of autooxidable neurotransmitters, and low antioxidant defenses as compared to other organs, that make it highly susceptible to oxidative stress (Halliwell, 2006; Emerit and al., 2004; Frauenberger et al., 2016). Sources of ROS Production Direct Sources: Direct sources involve the deposition of energy onto water molecules, breaking them into active radical species. When ionizing radiation hits water, it breaks it into hydrogen (H*) and hydroxyl (OH*) radicals by destroying its bonds. The hydrogen will create hydroxyperoxyl free radicals (HO2*) if oxygen is available, which can then react with another of itself to form hydrogen peroxide (H2O2) and more O2 (Elgazzar and Kazem, 2015). Antioxidant mechanisms are also affected by radiation, with catalase (CAT) and peroxidase (POD) levels rising as a result of exposure (Seen et al. 2018; Ahmad et al. 2021). Indirect Sources: An indirect source of ROS is the mitochondria, which is one of the primary producers in eukaryotic cells (Powers et al., 2008).  As much as 2% of the electrons that should be going through the electron transport chain in the mitochondria escape, allowing them an opportunity to interact with surrounding structures. Electron-oxygen reactions result in free radical production, including the formation of hydrogen peroxide (H2O2) (Zhao et al., 2019). The electron transport chain, which also creates ROS, is activated by free adenosine diphosphate (ADP), O2, and inorganic phosphate (Pi) (Hargreaves et al. 2020; Raimondi et al. 2020; Vargas-Mendoza et al. 2021). The first and third complexes of the transport chain are the most relevant to mammalian ROS production (Raimondi et al., 2020). The mitochondria have its own set of DNA and it is a prime target of oxidative damage (Guo et al., 2013). ROS are also produced through nicotinamide adenine dinucleotide phosphate oxidase (NOX) stimulation, an event commenced by angiotensin II, a product/effector of the renin-angiotensin system (Nguyen Dinh Cat et al. 2013; Forrester et al. 2018). Other ROS producers include xanthine oxidase, immune cells (macrophage, neutrophils, monocytes, and eosinophils), phospholipase A2 (PLA2), monoamine oxidase (MAO), and carbon-based nanomaterials (Powers et al. 2008; Jacobsen et al. 2008; Vargas-Mendoza et al. 2021).

Oxidative Stress. Direct measurement of ROS is difficult because ROS are unstable. The presence of ROS can be assayed indirectly by measurement of cellular antioxidants, or by ROS-dependent cellular damage. Listed below are common methods for detecting the KE, however there may be other comparable methods that are not listed <ul> <li>Detection of ROS by chemiluminescence (https://www.sciencedirect.com/science/article/abs/pii/S0165993606001683)</li> <li>Detection of ROS by chemiluminescence is also described in OECD TG 495 to assess phototoxic potential.</li> <li>Glutathione (GSH) depletion. GSH can be measured by assaying the ratio of reduced to oxidized glutathione (GSH:GSSG) using a commercially available kit (e.g., http://www.abcam.com/gshgssg-ratio-detection-assay-kit-fluorometric-green-ab138881.html). </li> <li>TBARS. Oxidative damage to lipids can be measured by assaying for lipid peroxidation using TBARS (thiobarbituric acid reactive substances) using a commercially available kit. </li> <li>8-oxo-dG. Oxidative damage to nucleic acids can be assayed by measuring 8-oxo-dG adducts (for which there are a number of ELISA based commercially available kits),or  HPLC, described in Chepelev et al. (Chepelev, et al. 2015).</li> </ul> Molecular Biology: Nrf2. Nrf2’s transcriptional activity is controlled post-translationally by oxidation of Keap1. Assay for Nrf2 activity include: <ul> <li>Immunohistochemistry for increases in Nrf2 protein levels and translocation into the nucleus</li> <li>Western blot for increased Nrf2 protein levels</li> <li>Western blot of cytoplasmic and nuclear fractions to observe translocation of Nrf2 protein from the cytoplasm to the nucleus</li> <li>qPCR of Nrf2 target genes (e.g., Nqo1, Hmox-1, Gcl, Gst, Prx, TrxR, Srxn), or by commercially available pathway-based qPCR array (e.g., oxidative stress array from SABiosciences)</li> <li>Whole transcriptome profiling by microarray or RNA-seq followed by pathway analysis (in IPA, DAVID, metacore, etc.) for enrichment of the Nrf2 oxidative stress response pathway (e.g., Jackson et al. 2014)</li> <li>OECD TG422D describes an ARE-Nrf2 Luciferase test method</li> <li>In general, there are a variety of commercially available colorimetric or fluorescent kits for detecting Nrf2 activation</li> </ul>   <table border="1" cellpadding="1" cellspacing="1"> <tbody> <tr> <td>Assay Type & Measured Content</td> <td>Description</td> <td>Dose Range Studied</td> <td> Assay Characteristics (Length / Ease of use/Accuracy) </td> </tr> <tr> <td> ROS Formation in the Mitochondria assay (Shaki et al., 2012) </td> <td>“The mitochondrial ROS measurement was performed flow cytometry using DCFH-DA. Briefly, isolated kidney mitochondria were incubated with UA (0, 50, 100 and 200 μM) in respiration buffer containing (0.32 mM sucrose, 10 mM Tris, 20 mM Mops, 50 μM EGTA, 0.5 mM MgCl2, 0.1 mM KH2PO4 and 5 mM sodium succinate) [32]. In the interval times of 5, 30 and 60 min following the UA addition, a sample was taken and DCFH-DA was added (final concentration, 10 μM) to mitochondria and was then incubated for 10 min. Uranyl acetate-induced ROS generation in isolated kidney mitochondria were determined through the flow cytometry (Partec, Deutschland) equipped with a 488-nm argon ion laser and supplied with the Flomax software and the signals were obtained using a 530-nm bandpass filter (FL-1 channel). Each determination is based on the mean fluorescence intensity of 15,000 counts.”</td> <td>0, 50, 100 and 200 μM of Uranyl Acetate</td> <td> Long/ Easy High accuracy </td> </tr> <tr> <td> Mitochondrial Antioxidant Content Assay Measuring GSH content (Shaki et al., 2012)</td> <td>“GSH content was determined using DTNB as the indicator and spectrophotometer method for the isolated mitochondria. The mitochondrial fractions (0.5 mg protein/ml) were incubated with various concentrations of uranyl acetate for 1 h at 30 °C and then 0.1 ml of mitochondrial fractions was added into 0.1 mol/l of phosphate buffers and 0.04% DTNB in a total volume of 3.0 ml (pH 7.4). The developed yellow color was read at 412 nm on a spectrophotometer (UV-1601 PC, Shimadzu, Japan). GSH content was expressed as μg/mg protein.”</td> <td> 0, 50, 100, or 200 μM Uranyl Acetate </td> <td> </td> </tr> <tr> <td> H2O2 Production Assay Measuring H2O2 Production in isolated mitochondria (Heyno et al., 2008)</td> <td>“Effect of CdCl2 and antimycin A (AA) on H2O2 production in isolated mitochondria from potato. H2O2 production was measured as scopoletin oxidation. Mitochondria were incubated for 30 min in the measuring buffer (see the Materials and Methods) containing 0.5 mM succinate as an electron donor and 0.2 µM mesoxalonitrile 3‐chlorophenylhydrazone (CCCP) as an uncoupler, 10 U horseradish peroxidase and 5 µM scopoletin.” (</td> <td> 0, 10, 30  μM Cd2+ 2  μM antimycin A</td> <td> </td> </tr> <tr> <td> Flow Cytometry ROS & Cell Viability (Kruiderig et al., 1997)</td> <td>“For determination of ROS, samples taken at the indicated time points were directly transferred to FACScan tubes. Dih123 (10 mM, final concentration) was added and cells were incubated at 37°C in a humidified atmosphere (95% air/5% CO2) for 10 min. At t 5 9, propidium iodide (10 mM, final concentration) was added, and cells were analyzed by flow cytometry at 60 ml/min. Nonfluorescent Dih123 is cleaved by ROS to fluorescent R123 and detected by the FL1 detector as described above for Dc (Van de Water 1995)”</td> <td> </td> <td> Strong/easy medium</td> </tr> <tr> <td> DCFH-DA Assay Detection of hydrogen peroxide production (Yuan et al., 2016) </td> <td> Intracellular ROS production was measured using DCFH-DA as a probe. Hydrogen peroxide oxidizes DCFH to DCF. The probe is hydrolyzed intracellularly to DCFH carboxylate anion. No direct reaction with H2O2 to form fluorescent production.    </td> <td>0-400 µM</td> <td> Long/ Easy High accuracy </td> </tr> <tr> <td> H2-DCF-DA Assay Detection of superoxide production (Thiebault et al., 2007) </td> <td>This dye is a stable nonpolar compound which diffuses readily into the cells and yields H2-DCF. Intracellular OH or ONOO- react with H2-DCF when cells contain peroxides, to form the highly fluorescent compound DCF, which effluxes the cell. Fluorescence intensity of DCF is measured using a fluorescence spectrophotometer.</td> <td>0–600 µM</td> <td> Long/ Easy High accuracy </td> </tr> <tr> <td>CM-H2DCFDA Assay</td> <td>**Come back and explain the flow cytometry determination of oxidative stress from Pan et al. (2009)**</td> <td> </td> <td> </td> </tr> </tbody> </table> Direct Methods of Measurement <table cellspacing="0" class="Table" style="border-collapse:collapse; width:623px"> <tbody> <tr> <td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:1px solid black; vertical-align:top; width:141px"> Method of Measurement  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:1px solid black; vertical-align:top; width:151px"> References  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:1px solid black; vertical-align:top; width:255px"> Description  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:1px solid black; vertical-align:top; width:76px"> OECD-Approved Assay </td> </tr> <tr> <td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; vertical-align:top; width:141px"> Chemiluminescence  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:151px"> (Lu, C. et al., 2006;  Griendling, K. K., et al., 2016) </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:255px"> ROS can induce electron transitions in molecules, leading to electronically excited products. When the electrons transition back to ground state, chemiluminescence is emitted and can be measured. Reagents such as uminol and lucigenin are commonly used to amplify the signal.  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:76px"> No   </td> </tr> <tr> <td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; vertical-align:top; width:141px"> Spectrophotometry  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:151px"> (Griendling, K. K., et al., 2016) </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:255px"> NO has a short half-life. However, if it has been reduced to nitrite (NO2-), stable azocompounds can be formed via the Griess Reaction, and further measured by spectrophotometry.  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:76px"> No </td> </tr> <tr> <td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; vertical-align:top; width:141px"> Direct or Spin Trapping-Based Electron Paramagnetic Resonance (EPR) Spectroscopy  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:151px"> (Griendling, K. K., et al., 2016) </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:255px"> The unpaired electrons (free radicals) found in ROS can be detected with EPR, and is known as electron paramagnetic resonance. A variety of spin traps can be used.  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:76px"> No </td> </tr> <tr> <td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; vertical-align:top; width:141px"> Nitroblue Tetrazolium Assay  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:151px"> (Griendling, K. K., et al., 2016) </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:255px"> The Nitroblue Tetrazolium assay is used to measure O2•– levels. O2•– reduces nitroblue tetrazolium (a yellow dye) to formazan (a blue dye), and can be measured at 620 nm.  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:76px"> No </td> </tr> <tr> <td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; vertical-align:top; width:141px"> Fluorescence analysis of dihydroethidium (DHE) or Hydrocyans  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:151px"> (Griendling, K. K., et al., 2016) </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:255px"> Fluorescence analysis of DHE is used to measure O2•– levels. O2•–  is reduced to O2 as DHE is oxidized to 2-hydroxyethidium, and this reaction can be measured by fluorescence. Similarly, hydrocyans can be oxidized by any ROS, and measured via fluorescence.  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:76px"> No </td> </tr> <tr> <td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; vertical-align:top; width:141px"> Amplex Red Assay  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:151px"> (Griendling, K. K., et al., 2016) </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:255px"> Fluorescence analysis to measure extramitochondrial or extracellular H2O2 levels. In the presence of horseradish peroxidase and H2O2, Amplex Red is oxidized to resorufin, a fluorescent molecule measurable by plate reader.  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:76px"> No </td> </tr> <tr> <td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; vertical-align:top; width:141px"> Dichlorodihydrofluorescein Diacetate (DCFH-DA)  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:151px"> (Griendling, K. K., et al., 2016) </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:255px"> An indirect fluorescence analysis to measure intracellular H2O2 levels. H2O2 interacts with peroxidase or heme proteins, which further react with DCFH, oxidizing it to dichlorofluorescein (DCF), a fluorescent product.  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:76px"> No </td> </tr> <tr> <td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; vertical-align:top; width:141px"> HyPer Probe  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:151px"> (Griendling, K. K., et al., 2016) </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:255px"> Fluorescent measurement of intracellular H2O2 levels. HyPer is a genetically encoded fluorescent sensor that can be used for in vivo and in situ imaging.  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:76px"> No </td> </tr> <tr> <td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; vertical-align:top; width:141px"> Cytochrome c Reduction Assay  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:151px"> (Griendling, K. K., et al., 2016) </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:255px"> The cytochrome c reduction assay is used to measure O2•– levels. O2•–  is reduced to O2 as ferricytochrome c is oxidized to ferrocytochrome c, and this reaction can be measured by an absorbance increase at 550 nm.  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:76px"> No </td> </tr> <tr> <td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; vertical-align:top; width:141px"> Proton-electron double-resonance imagine (PEDRI) </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:151px"> (Griendling, K. K., et al., 2016) </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:255px"> The redox state of tissue is detected through nuclear magnetic resonance/magnetic resonance imaging, with the use of a nitroxide spin probe or biradical molecule.  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:76px"> No </td> </tr> <tr> <td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; vertical-align:top; width:141px"> Glutathione (GSH) depletion  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:151px"> (Biesemann, N. et al., 2018)  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:255px"> A downstream target of the Nrf2 pathway is involved in GSH synthesis. As an indication of oxidation status, GSH can be measured by assaying the ratio of reduced to oxidized glutathione (GSH:GSSG) using a commercially available kit (e.g., <a href="http://www.abcam.com/gshgssg-ratio-detection-assay-kit-fluorometric-green-ab138881.html">http://www.abcam.com/gshgssg-ratio-detection-assay-kit-fluorometric-green-ab138881.html</a>).   </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:76px"> No </td> </tr> <tr> <td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; vertical-align:top; width:141px"> Thiobarbituric acid reactive substances (TBARS)  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:151px"> (Griendling, K. K., et al., 2016) </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:255px"> Oxidative damage to lipids can be measured by assaying for lipid peroxidation with TBARS using a commercially available kit.   </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:76px"> No </td> </tr> <tr> <td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; vertical-align:top; width:141px"> Protein oxidation (carbonylation) </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:151px"> (Azimzadeh et al., 2017; Azimzadeh etal., 2015; Ping et al., 2020) </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:255px"> Can be determined with enzyme-linked immunosorbent assay (ELISA) or a commercial assay kit. Protein oxidation can indicate the level of oxidative stress. </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:76px"> No </td> </tr> <tr> <td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; vertical-align:top; width:141px">Seahorse XFp Analyzer   </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:151px">Leung et al. 2018   </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:255px">The Seahorse XFp Analyzer provides information on mitochondrial function, oxidative stress, and metabolic dysfunction of viable cells by measuring respiration (oxygen consumption rate; OCR) and extracellular pH (extracellular acidification rate; ECAR).   </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:76px">No </td> </tr> </tbody> </table> Molecular Biology: Nrf2. Nrf2’s transcriptional activity is controlled post-translationally by oxidation of Keap1. Assays for Nrf2 activity include:  <table cellspacing="0" class="Table" style="border-collapse:collapse; width:623px"> <tbody> <tr> <td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:1px solid black; vertical-align:top; width:154px"> Method of Measurement  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:1px solid black; vertical-align:top; width:139px"> References  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:1px solid black; vertical-align:top; width:256px"> Description  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:1px solid black; vertical-align:top; width:75px"> OECD-Approved Assay </td> </tr> <tr> <td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; vertical-align:top; width:154px"> Immunohistochemistry  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:139px"> (Amsen, D., de Visser, K. E., and Town, T., 2009) </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:256px"> Immunohistochemistry for increases in Nrf2 protein levels and translocation into the nucleus   </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:75px"> No </td> </tr> <tr> <td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; vertical-align:top; width:154px"> Quantitative polymerase chain reaction (qPCR)  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:139px"> (Forlenza et al., 2012) </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:256px"> qPCR of Nrf2 target genes (e.g., Nqo1, Hmox-1, Gcl, Gst, Prx, TrxR, Srxn), or by commercially available pathway-based qPCR array (e.g., oxidative stress array from SABiosciences)  </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:75px"> No </td> </tr> <tr> <td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; height:46px; vertical-align:top; width:154px"> Whole transcriptome profiling via microarray or via RNA-seq followed by a pathway analysis </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; height:46px; vertical-align:top; width:139px"> (Jackson, A. F. et al., 2014) </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; height:46px; vertical-align:top; width:256px"> Whole transcriptome profiling by microarray or RNA-seq followed by pathway analysis (in IPA, DAVID, metacore, etc.) for enrichment of the Nrf2 oxidative stress response pathway </td> <td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; height:46px; vertical-align:top; width:75px"> No </td> </tr> </tbody> </table>

Taxonomic applicability: Occurrence of oxidative stress is not species specific.   Life stage applicability: Occurrence of oxidative stress is not life stage specific.  Sex applicability: Occurrence of oxidative stress is not sex specific.  Evidence for perturbation by prototypic stressor: There is evidence of the increase of oxidative stress following perturbation from a variety of stressors including exposure to ionizing radiation and altered gravity (Bai et al., 2020; Ungvari et al., 2013; Zhang et al., 2009).

High Mixed

High

All life stages

High High

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(2017), “Radioprotective effect of hesperidin on reducing oxidative stress in the lens tissue of rats”, International Journal of Pharmaceutical Investigation, Vol. 7/3, Phcog Net, Bengaluru, <a href="https://doi.org/10.4103/jphi.JPHI_60_17.%E2%80%AF" rel="noreferrer noopener" target="_blank">https://doi.org/10.4103/jphi.JPHI_60_17.</a> Leung, D.T.H., and Chu, S. (2018), “Measurement of Oxidative Stress: Mitochondrial Function Using the Seahorse System” In: Murthi, P., Vaillancourt, C. (eds) Preeclampsia. Methods in Molecular Biology, vol 1710. Humana Press, New York, NY. https://doi.org/10.1007/978-1-4939-7498-6_22  Lu, C., G. Song, and J. Lin (2006), “Reactive oxygen species and their chemiluminescence-detection methods”, TrAC Trends in Analytical Chemistry, Vol. 25/10, Elsevier, Amsterdam, <a href="https://doi.org/10.1016/j.trac.2006.07.007" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1016/j.trac.2006.07.007</a> Nguyen Dinh Cat, A. et al. (2013), “Angiotensin II, NADPH oxidase, and redox signaling in the vasculature”, Antioxidants & redox signaling, Vol. 19/10, Mary Ann Liebert, Larchmont, <a href="https://doi.org/10.1089/ars.2012.4641" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1089/ars.2012.4641</a> Ping, Z. et al. (2020), “Oxidative Stress in Radiation-Induced Cardiotoxicity”, Oxidative Medicine and Cellular Longevity, Vol. 2020, Hindawi, <a href="https://doi.org/10.1155/2020/3579143" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1155/2020/3579143</a> Powers, S.K. and M.J. Jackson. (2008), “Exercise-Induced Oxidative Stress: Cellular Mechanisms and Impact on Muscle Force Production”, Physiological Reviews, Vol. 88/4, American Physiological Society, Rockville, <a href="https://doi.org/10.1152/physrev.00031.2007" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1152/physrev.00031.2007</a> Raimondi, V., F. Ciccarese and V. Ciminale. (2020), “Oncogenic pathways and the electron transport chain: a dangeROS liason”, British Journal of Cancer, Vol. 122/2, Nature Portfolio, London, <a href="https://doi.org/10.1038/s41416-019-0651-y" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1038/s41416-019-0651-y</a> Seen, S. and L. Tong. (2018), “Dry eye disease and oxidative stress”, Acta Ophthalmologica, Vol. 96/4, John Wiley & Sons, Inc., Hoboken, <a href="https://doi.org/10.1111/aos.13526" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1111/aos.13526</a> Ungvari, Z. et al. (2013), “Ionizing Radiation Promotes the Acquisition of a Senescence-Associated Secretory Phenotype and Impairs Angiogenic Capacity in Cerebromicrovascular Endothelial Cells: Role of Increased DNA Damage and Decreased DNA Repair Capacity in Microvascular Radiosensitivity”, The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, Vol. 68/12, Oxford University Press, Oxford, <a href="https://doi.org/10.1093/gerona/glt057." style="color:#0563c1; text-decoration:underline">https://doi.org/10.1093/gerona/glt057.</a>   Vargas-Mendoza, N. et al. (2021), “Oxidative Stress, Mitochondrial Function and Adaptation to Exercise: New Perspectives in Nutrition”, Life, Vol. 11/11, Multidisciplinary Digital Publishing Institute, Basel, <a href="https://doi.org/10.3390/life11111269" style="color:#0563c1; text-decoration:underline">https://doi.org/10.3390/life11111269</a> Wang, H. et al. (2019), “Radiation-induced heart disease: a review of classification, mechanism and prevention”, International Journal of Biological Sciences, Vol. 15/10, Ivyspring International Publisher, Sydney, <a href="https://doi.org/10.7150/ijbs.35460" style="color:#0563c1; text-decoration:underline">https://doi.org/10.7150/ijbs.35460</a> Zhang, R. et al. (2009), “Blockade of AT1 receptor partially restores vasoreactivity, NOS expression, and superoxide levels in cerebral and carotid arteries of hindlimb unweighting rats”, Journal of applied physiology, Vol. 106/1, American Physiological Society, Rockville, <a href="https://doi.org/10.1152/japplphysiol.01278.2007" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1152/japplphysiol.01278.2007</a>. Zhao, R. Z. et al. (2019), “Mitochondrial electron transport chain, ROS generation and uncoupling”, International journal of molecular medicine, Vol. 44/1, Spandidos Publishing Ltd., Athens, <a href="https://doi.org/10.3892/ijmm.2019.4188" style="color:#0563c1; text-decoration:underline">https://doi.org/10.3892/ijmm.2019.4188</a> AOPWiki 2017-05-30T13:58:17

2023-03-21T15:16:10

<upstream-id>004d50c1-7dc2-4d2f-8a21-55fc4853ab74</upstream-id> <downstream-id>a67512e2-5fb7-4d79-8c5f-5ce55f464beb</downstream-id> Because the lung interfaces with the external environment, it is frequently exposed to airborne oxidant gases and particulates, and thus prone to oxidant-mediated cellular damage (Ciencewicki et al., 2008). Oxidant stress—through the action of exogenous and endogenous free radicals, such as super oxides, hydroxyl radicals, and hydrogen peroxides—is a common factor in lung inflammation and various respiratory diseases. The presence of redox-sensitive proteins in motile cilia suggests that oxidant stresses may impact ciliary function negatively (Price and Sisson, 2019). Indeed, exposure of human or rodent ciliated airway epithelial cells to hydrogen peroxide, acetaldehyde, ozone or cigarette smoke—all of which are known to cause oxidative stress—decreases CBF in a dose- and time-dependent manner (Bayram et al., 1998; Burman and Martin, 1986; Gosepath et al., 2000; Hastie et al., 1990; Helleday et al., 1995; Kienast et al., 1994; Knorst et al., 1994a; Min et al., 1999; Simet et al., 2010).

Experimental studies in vitro have shown that exposure of ciliated respiratory cells directly or indirectly to sources of oxidative stress leads to decreased CBF (Burman and Martin, 1986; Wilson et al., 1987; Feldman et al., 1994; Yoshitsugu et al., 1995; Min et al., 1999), which can be reversed by treatment with antioxidants (Schmid et al., 2015). Cigarette smoke condensate, a known inducer of oxidative stress, also causes a decrease in CBF in vitro (Cohen et al., 2009), while, in human subjects exposed to different oxygen levels, oxygen stress causes a decrease in nasal CBF (Stanek et al., 1998).

One mode of antimicrobial defense in the airway epithelium is generation of free radicals by neutrophils and monocytes/macrophages. Some microbes have also been shown to produce oxidants in significant amounts, e.g. H2O2 production by pneumococcus. Several studies have shown that oxidants, irrespective of the source (microbial or host-derived) inhibit ciliary function. Additionally, there is a large body of experimental evidence demonstrating that exposures to environmental oxidants, including volatile aldehydes, peroxides, sulfur dioxide, nitric dioxide and Diesel exhaust particles have a detrimental impact on ciliary function. Therefore, this KER is highly plausible.

Treatment with H2O2 causes a dose-dependent decline in ciliary beat frequency (CBF) in tracheal rings from male Sprague-Dawley rats (Burman and Martin, 1986). Exposure of nasal ciliated epithelial cells to enzymatically generated oxidants (xanthine/xanthine oxidase) was accompanied by ciliary slowing, which was maximal at the end of the experiment (4 h). After 4 h, the reduction in CBF was 37.4%. Catalase alone, or in combination with superoxide dismutase (SOD), completely protected the epithelial strips from oxidant-mediated ciliary dyskinesia. Exposure of respiratory epithelium to glucose/glucose oxidase resulted in similar effects to those obtained with the xanthine/xanthine oxidase system, with 38% and 57% CBF reduction after 4 h in systems containing 25 and 100 mU of glucose oxidase, respectively. Treatments with H2O2 and HOCl at concentrations of ≥100 µM caused dose-dependent ciliary dyskinesia after 4 h (Feldman et al., 1994). Marked ciliary slowing was observed after exposure of human nasal epithelial cells to free radicals within the first 5 min. There was a significant difference in CBF between experimental and control groups. Pretreatment with 300 U/mL SOD or with 5 mM 3-ABA prevented CBF changes. (Min et al., 1999). Pyocyanin dissolved in PBS produced gradual slowing of CBF in strips of normal human nasal ciliated epithelium without recovery. Ciliary dyskinesia was observed only late in the experiments when ciliostasis and epithelial disruption were also noted. In contrast, 1-hydroxyphenazine produced rapid onset of ciliary slowing, dyskinesia, and immediate ciliostasis but also some recovery of ciliary beating during the experiment (Wilson et al., 1987). Baseline CBF was analyzed in human sinonasal epithelial cells for 4 min (time 0) followed by administration of either cigarette smoke condensate (CSC; not further specified) or DMSO for 3 min. Forskolin was then administered to the apical surface and stimulated CBF measured. Following addition of forskolin, stimulated CBF was significantly decreased in the CSC-exposed group compared to DMSO controls (Cohen et al., 2009). Treatment of fully differentiated normal human bronchial epithelial cells with 100 nM roflumilast raised the CBF at 1 h after exposure. Subsequent air or cigarette smoke exposure increased CBF significantly in roflumilast-treated cultures (Schmid et al., 2015). In superficial mucosae of the inferior nasal turbinates from non-smoking healthy volunteers exposed to three different oxygen concentrations—21%, 60% and 95%—for 2 h, CBF dose-dependently increased. Extending exposure to extreme oxygen concentrations to 4 h, however, decreased CBF, which is indicative of “oxygen stress” (Stanek et al., 1998). Within 2 min of exposure of human respiratory epithelial cell monolayers to 10 µM H2O2, a decrease in CBF was observed. All cilia stopped moving within 10 min without obvious surface structural change in the ciliated cells. Catalase significantly reduced the ciliotoxic effect of H2O2 (Yoshitsugu et al., 1995).

Several studies show that oxidants decrease CBF which can be reversed by addition of antioxidants, suggesting a direct effect. However, there is evidence suggesting that oxidant-mediated decreases in CBF cannot be prevented by addition of antioxidants. For example, a polycyanin-induced decrease in CBF in human nasal epithelium could be reversed by treatment with isobutylmethylxanthine and forskolin, both of which increase intracellular cAMP, and also by the cAMP analog dibutyryl cAMP, while antioxidants did not seem to have any effect on CBF (Kanthakumar et al., 1993). Like polycyanin, two other P. aeruginosa toxins, 1-hydroxyphenazine (1-HP) and rhamnolipid reduced CBF which was associated with a decrease in intracellular adenosine nucleotides (Kanthakumar et al., 1996).  Inconsistent with several studies, there are studies that suggest that exposure to cigarette smoke does not inhibit CBF. A study involving 56 human subjects (27 non-smokers and 29 smokers) showed no differences in CBF between the 2 groups. However, a decrease in nasal mucociliary clearance was observed in smokers who exhaled smoke through their noses (Stanley et al., 1986).  While several studies have shown age dependence of CBF, there is evidence that suggests otherwise  (Agius et al., 1998).

<table class="table table-bordered table-fullwidth"> <thead> <tr> <th>Modulating Factor (MF)</th> <th>MF Specification</th> <th>Effect(s) on the KER</th> <th>Reference(s)</th> </tr> </thead> <tbody> <tr> <td>CFTR genetic dysfunction / cystic fibrosis</td> <td>Mutations in CFTR gene and decreased CFTR levels lead in reduced Cl–channel activity and to compromised fluid and electrolyte transport, consequently to reduced airway surface liquid levels, thus hindering coordinated ciliary beating.</td> <td>Decrease in CFTR protein activity decreases CBF (see also KERs 2440 and 2441).</td> <td>Van Goor et al., 2009</td> </tr> </tbody> </table>

Several studies in various species, including humans and rodents, provide evidence in support of this KER. The empirical evidence confirms both a dose- and time-dependence between the upstream KE/MIE and the downstream KE. Our quantitative understanding of this KER is therefore strong.

Treatment of human nasal ciliated epithelial cells with 0.4 mM xanthine + 100 mU/mL xanthine oxidase—producing 159 ± 4.0 µM/h H2O2—decreased CBF by ca. 1 Hz at 1 h and ca. 2.5 Hz (37.4%) at 4 h. Catalase alone (500 U/mL), or in combination with SOD (300 U/mL ) completely protected the cells from oxidant-mediated ciliary dyskinesia (Feldman et al., 1994). Treatment of human nasal ciliated epithelial cells with 5 mM glucose + 25 mU/mL glucose oxidase— producing 114 ± 7.7 µM/h H2O2—decreased CBF by ca. 2 Hz at 1 h and ca. 4 Hz (38%) at 4 h. The decline in CBF was even larger with 57% (approx. 6 Hz) at 4 h when 100 mU/mL glucose oxidase was used (producing 322 ± 11.5 µM/h H2O2). Catalase alone (500 U/mL) completely protected the cells from oxidant-mediated ciliary dyskinesia (Feldman et al., 1994). Treatment of human nasal ciliated epithelial cells with H2O2 at concentrations ≥100 µM dose-dependently decreased CBF in human nasal ciliated epithelial cells, with 100 µM causing a 22.4% reduction and the maximal decrease (51.6%) seen with 500 µM H2O2 at 4 h. Adding 100 mU/mL MPO to 150 µM H2O2 enhanced the H2O2-mediated decrease in CBF (control:11.7 ±0.6 Hz; H2O2: 8.2 ± 1.1 Hz, 30% decrease; H2O2 + MPO: 5.4±0.2 Hz, 53.8% decrease). (Feldman et al., 1994). Treatment of human nasal ciliated epithelial cells with HOCl at concentrations ≥100 µM dose-dependently decreased CBF in human nasal ciliated epithelial cells, with 100 µM causing a 26.1% reduction and 500 µM causing the maximal decrease (100%) at 4 h (Feldman et al., 1994). Treatment of human nasal epithelial cells with 0.4 mM xanthine + 100 mU/mL xanthine oxidase decreased CBF by ca. 50% within 2 min. Addition of 300 U/mL SOD abolished this effect (Min et al., 1999). Treatment of human nasal epithelial cells with 10 mM H2O2 decreased CBF to 36.5 ±4.4% of baseline within 5 min, with a maximal decrease in CBF of 100% seen after 10 min, whereas 1 mM H2O2 had no effect on CBF. Treatment of human nasal ciliated epithelial cells with 0.8 mM xanthine + 100 mU/mL xanthine oxidase transiently increased CBF by 12.1±1.0% from baseline. When xanthine concentration was increased to 4 and 8 mM, CBF decreased by 26.8±1.7 and 25.6±1.5%, respectively (Yoshitsugu et al., 1995). Treatment of bovine ciliated bronchial epithelial cells with acetaldehyde, an oxidative stressor, decreased CBF in a dose-dependent manner. Significant slowing of ciliary beating by ca. 50% was observed with concentrations as low as 15-30 µM, and ciliary beating was completely abrogated at concentrations > 250 µM. Ciliary beating also decreased following treatment with 15-30 µM propionaldehyde (40-50% of control), butyraldehyde (35-65% of control), isobutyraldehyde (20-40% of control), and benzaldehyde (80-90% of control) (Sisson et al., 1991). Exposure of rabbit tracheal explants to formaldehyde dose-dependently decreased CBF. At 66 µg formaldehyde/cm3, CBF decreased from 12.6 to 11.8 Hz; at 33 µg formaldehyde/cm3, CBF decreased from 13.0 to 10.9 Hz (Hastie et al., 1990). Exposure of guinea pig trachea to SO2 at concentrations of 2.5-12.5 ppm for 30 min dose-dependently decreased CBF. Exposure to 2.5 ppm SO2 caused a small, non-significant decrease in mean CBF, and exposure to 5 ppm SO2 caused a 45% decrease. The greatest decrease (72 %) in mean CBF was recorded after exposure to 12.5 ppm SO2 (Knorst et al., 1994a). Exposure of human nasal epithelial cells (cultured in Ringer’s solution) to SO2 at concentrations of 2.5-12.5 ppm for 30 min dose-dependently decreased CBF. Exposure to 2.5 ppm yielded a 42.8% decrease, whereas exposure to 12.5 ppm yielded a 96.5% decrease in CBF (Kienast et al., 1994). A 20-min exposure to NO2, a known air pollutant, at concentrations of 1.5 or 3.5 ppm did not affect CBF in healthy human subjects at 45 min post-exposure (Helleday et al., 1995). Exposure of human bronchial epithelial cells from healthy volunteers to 10, 50, and 100 µg/mL Diesel exhaust particles (DEP) significantly decreased CBF by 15.9%, 31.0%, and 55.5%, respectively, from baseline after 24 h (Bayram et al., 1998). A 4-week exposure of human nasal epithelial cells to 100 µg/m3 ozone had no effect on CBF, whereas 5- and 10-times that concentration significantly decreased CBF (-11.1% at 500 µg/m3; -33.3% at 1000 µg/m3) (Gosepath et al., 2000). Baseline CBF in tracheal rings from C57Bl/6 mice exposed to cigarette smoke (whole body exposure to mainstream and sidestream cigarette smoke via inhalation from 1R1 reference cigarettes, at 150 mg/m3 total particulate matter for 2 h/day, 5 days/week, for up to 1 year) for 1.5 to 3 months was slightly, but not significantly, increased (&sim;1 Hz). After 6 months of smoke exposure, however, baseline CBF significantly decreased (&sim;2–3 Hz) (Simet et al., 2010).

Treatment of human nasal ciliated epithelial cells with 0.4 mM xanthine + 100 mU/mL xanthine oxidase decreased CBF over time, with a noticeable decrease by ca. 1 Hz at 1 h and a maximal decrease of 37.4% reached at 4 h (Feldman et al., 1994). Treatment of human nasal ciliated epithelial cells with 5 mM glucose + 25 mU/mL glucose oxidase decreased CBF by ca. 2 Hz at 1 h and a maximal decrease of ca. 4 Hz (38%) at 2 h, that did not change until the end of the experiment at 4 h. When 100 mU/mL glucose oxidase was used, CBF decreased by ca. 2 Hz at 1 h, 4 Hz at 2 h, 5.5 Hz at 3 h, reaching a maximum of 57% (approx. 6 Hz) at 4 h (Feldman et al., 1994). Treatment of human nasal epithelial cells with 0.4 mM xanthine + 100 mU/mL xanthine oxidase decreased CBF maximally by ca. 50% within 2 min, after which it began to increase again, reaching approx. 80% of the baseline value after 30 min (Min et al., 1999). Treatment of human nasal ciliated epithelial cells with 0.8 mM xanthine + 100 mU/mL xanthine oxidase transiently increased CBF by 12.1±1.0% from baseline within 15 s, after which it rapidly returned to baseline levels (within 30 min). When xanthine concentrations were increased to 4 and 8 mM, CBF decreased by 26.8±1.7 and 25.6±1.5%, respectively (Yoshitsugu et al., 1995). Treatment of bovine ciliated bronchial epithelial cells with acetaldehyde reduced CBF rapidly, with a significant drop in CBF occurring within 30 s and a maximal decrease by 3 min (Sisson et al., 1991). Exposure of rabbit tracheal explants to formaldehyde time-dependently decreased CBF: At 66 µg/cm3, CBF decreased from 12.6 to 11.8 Hz immediately upon addition of HCHO to complete cessation of beating by 10 min. At 33 µg/cm3, CBF decreased from 13.0 to 10.9 Hz by 30 min (Hastie et al., 1990). At 24 h following a 4-h exposure of healthy human subjects to 3.5 ppm NO2, there was a significant elevation in CBF from 12.4±0.9 Hz (at baseline, pre-exposure) to 13.8±0.8 Hz (Helleday et al., 1995). Exposure of human bronchial epithelial cells to DEP significantly decreased CBF from 2 h onward after incubation with 50 to 100 µg/mL DEP and from 6 hours onward after incubation with 10 µg/mL DEP (Bayram et al., 1998). A 4-week exposure of human nasal epithelial cells to ozone significantly reduced CBF, with effects becoming noticeable at the higher concentrations (-7.1% at 500 µg/m3;  -10.3% at 1000 µg/m3) after 2 weeks of exposure and a maximal decrease after 4 weeks (-11.1% at 500 µg/m3; -33.3% at 1000 µg/m3) (Gosepath et al., 2000).

Unknown

Not Specified Mixed

Not Specified

All life stages

High Not Specified Not Specified Not Specified

Age-dependent decreases in CBF have been demonstrated in several species (e.g. guinea pigs, mice, and human) (Bailey et al., 2014; Grubb et al., 2016; Ho et al., 2001; Joki and Saano, 1997; Paul et al., 2013).  Female hormones, i.e. progesterone and estrogen, have been shown to have direct effect on CBF, i.e., progesterone reduces CBF, 17β-estradiol and progesterone receptor antagonists counteract progesterone effects, but estradiol alone has also been shown to have no effect on CBF. However, the mechanism by which these hormones modulate CBF is yet to be elucidated (Jain et al., 2012; Jia et al., 2011).

#<Reference::ActiveRecord_Associations_CollectionProxy:0x00007b430b0c7f28> AOPWiki 2021-08-02T03:05:24

2023-03-24T06:04:15

<upstream-id>a67512e2-5fb7-4d79-8c5f-5ce55f464beb</upstream-id> <downstream-id>76d10b3b-ae16-47bc-a711-4ffef74ad4d6</downstream-id> Synchronized ciliary action transports mucus from the distal lung to the mouth, where it is swallowed or expectorated (Munkholm and Mortensen, 2014). In addition to ASL and mucus properties, the speed of ciliary movement, and hence the effectiveness of mucociliary clearance (MCC), is dependent on ciliary amplitude and beat frequency (Rubin, 2002). CBF itself is influenced by several factors, including changes in the physical and chemical properties of the ASL (especially the periciliary fluid), structural modulation in the cilia, concentration of cyclic nucleotides cAMP and cGMP, and intracellular calcium (Ca2+). Aside from genetic defects leading to ciliopathies, there is ample evidence for prolonged exposure to noxious agents, such as cigarette smoke, nitrogen oxide and sulfur dioxide, playing a major role in decreasing CBF and hampering efficient MCC.

A decrease in CBF resulting from sulfur dioxide exposure reduced mucociliary clearance in dogs (Yeates et al., 1997) and mucociliary activity in guinea pig tracheas (Knorst et al., 1994). In rats, formaldehyde inhalation exposure resulted in lower numbers of ciliated cells, while ciliary activity and mucus flow rates were decreased in a dose and time-dependent manner (Morgan et al., 1986). In humans, CBF positively correlates with nasal mucociliary clearance time (Ho et al., 2001), and bronchiectasis patients have lower nasal CBF and slower mucociliary transport (MCT) (Rutland and Cole, 1981). Administration of nebulized CBF inhibitors and enhancers quantifiably decreased or increased mucociliary clearance, respectively (Boek et al., 1999; Boek et al., 2002). Increased CBF and MCT was also noted in human sinonasal epithelial cell cultures treated with Myrtol®, an essential oil distillate (Lai et al., 2014) and in sheep tracheas and human airway epithelial cultures subjected to temperature changes (Kilgour et al., 2004; Sears et al., 2015). Exposures of frog palate epithelia to formaldehyde and PM10 reduced MCC and mucociliary transport, but only formaldehyde-treated epithelia showed decreases in CBF (Morgan et al., 1984; Macchione et al., 1999; Fló-Neyret et al., 2001). Ex vivo treatment of sheep trachea with acetylcholine and epinephrine increased CBF, but only acetylcholine increased surface liquid velocity, while both parameters were decreased upon incubation with platelet-activating factor (Seybold et al., 1990).

Ciliary function and mucus transport are invariably linked to effective mucus transport along the mucociliary escalator (Bustamante-Marin and Ostrowski, 2017; Mall, 2008). Therefore, this KER is biologically plausible.

Studies in animal models of ciliopathies and in individuals with genetic disorders causing cilia defects demonstrate that absent or asynchronous cilia beating results in defective mucus clearance from the lungs, consequently leading to respiratory infections that may be chronic recurrent in nature and ultimately lead to declining lung function (Knowles et al., 2013; Munkholm and Mortensen, 2014; Tilley et al., 2015). Similarly, indirect effects of airway inflammation, caused for example by respiratory infections or allergies, are known to be responsible for changes in cilia beating and hence mucus clearance (Almeida-Reis et al., 2010; Hisamatsu and Nakajima, 2000; Maurer et al., 1982). Finally, airway epithelial injury following exposure to inhalation toxicants can also damage cilia and inhibit cilia function and thereby impair MCC (Iravani and Van As, 1972; Wanner et al., 1996). A decrease in CBF resulting from sulfur dioxide exposure reduced mucociliary clearance in dogs (Yeates et al., 1997) and mucociliary activity in guinea pig tracheas (Knorst et al., 1994). In rats, formaldehyde inhalation exposure resulted in lower numbers of ciliated cells, while ciliary activity and mucus flow rates were decreased in a dose and time-dependent manner (Morgan et al., 1986). In humans, CBF positively correlates with nasal mucociliary clearance time (Ho et al., 2001), and bronchiectasis patients have lower nasal CBF and slower mucociliary transport (MCT) (Rutland and Cole, 1981). Administration of nebulized CBF inhibitors and enhancers quantifiably decreased or increased mucociliary clearance, respectively (Boek et al., 1999; Boek et al., 2002). Increased CBF and MCT was also noted in human sinonasal epithelial cell cultures treated with Myrtol®, an essential oil distillate (Lai et al., 2014) and in sheep tracheas and human airway epithelial cultures subjected to temperature changes (Kilgour et al., 2004; Sears et al., 2015). Exposures of frog palate epithelia to formaldehyde and PM10 reduced MCC and mucociliary transport, but only formaldehyde-treated epithelia showed decreases in CBF (Morgan et al., 1984; Macchione et al., 1999; Fló-Neyret et al., 2001). The available evidence does not interrogate the direct relationship between CBF and MCC, but rather evaluates both outcomes in parallel. However, because of the intrinsic linkage of cilia function and MCC, we find the empirical evidence in support of this KER to be moderate. Ex vivo treatment of sheep trachea with acetylcholine and epinephrine increased CBF, but only acetylcholine increased surface liquid velocity, while both parameters were decreased upon incubation with platelet-activating factor (Seybold et al., 1990).

Although ciliary function is considered a primary determinant for effective MCC (Duchateau et al., 1985; Gizurarson, 2015), there is evidence that suggests that MCC can be impeded by other factors that do not affect CBF. For example, nasal CBF in cigarette smokers regularly exhaling through the nose was not significantly different from that of nonsmokers, although they exhibited significantly longer nasomuciliary clearance times compared to nonsmokers. Possible explanations offered for this discrepancy were a potential loss of cilia in the nasal epithelium or increased mucus viscoelasticity (Stanley et al., 1986). Similarly, formaldehyde exposure of rats resulted in decreased cilia numbers and slower mucus flow rates (Morgan KT et al., 1986). On the other hand, there are a number of pharmacological compounds that improve mucociliary clearance through reductions in mucus viscosity, but have no effect on CBF (Jiao and Zhang, 2019), or through increases in CBF, but have no effect on mucociliary clearance (Phillips et al., 1990).

Physiological factors such as age, sex, posture, sleep, and exercise were shown to affect MCC, although study findings are not always concordant (Houtmeyers et al., 1999). MCC and CBF, for example, were observed to decrease with age in several species in numerous studies (e.g. guinea pigs, mice, and human) (Bailey et al., 2014; Grubb et al., 2016; Ho et al., 2001; Joki and Saano, 1997; Paul et al., 2013; Yager et al., 1978), but evidence by (Agius et al., 1998) suggests that age does not have a major effect on CBF.

There are several studies providing insights into the negative effect of inhalation exposures on CBF and MCC, that are in line with the current thinking on how these two KEs connect. Additionally, pharmacological studies demonstrated that stimulation of CBF typically results in stimulation of MCC. However, since most studies usually evaluated the KEs in parallel, and even though some results support both dose response and temporal sequence of the KEs, none of the available data affirms causal linkage between CBF and MCC. Our understanding of the evidence is therefore moderate.

CBF decreased sequentially with increasing SO2 doses in dogs. CBF decreased from 6.3 ± 0.2 (SE) Hz at baseline to 5.7 ± 0.2 Hz at 5.5 ppm SO2. Five ppm SO2 delivered to both the trachea and tracheobronchial airways for 20 min also caused a marked decrease in mean bronchial mucociliary clearance from 53.7 ± 5.7% to 32.8 ± 7.7% after 90 min (Yeates et al., 1997). The effects of 30-min exposure to SO2 on mucociliary activity (MCA) and ciliary beat frequency (CBF) were studied in 31 guinea pig tracheas. A 63% reduction in mean MCA and statistically insignificant changes in CBF were recorded at concentrations of 2.5 ppm SO2. Higher SO2 concentrations caused further impairment of MCA as well as a dose-dependent decrease in CBF: At 5 ppm SO2, CBF decreased by 45%, at 12.5 ppm by 72%. The maximum decrease in MCA (81%) was observed with 7.5 ppm SO2; the highest SO2 concentration did not decrease MCA further. The decrease in MCA was associated with an impairment of CBF only at SO2 concentrations ≥5.0 ppm (Knorst et al., 1994b). Administration of a nebulized CBF inhibitor (0.9% NaCl) to 15 healthy volunteers significantly decreased mucociliary transport (MCT) from 7.9±1.5 mm/min (SEM) to 4.5±1.6 mm/min. Salbutamol, a CBF enhancer, significantly increased MCT from 8.0±1.4 to 12.5±1.1 mm/min (Boek et al., 2002; Boek et al., 1999). Cooling human airway epithelial cultures grown at the air-liquid interface from 37°C to 25°C over the course of approx. 20 min decreased CBF from 12 to 6 Hz and mucociliary transport (MCT) from 140 to 90 µm/s. Extending the range of temperature tested, CBF was found to increase by 0.49±0.06 Hz for every temperature increase by 1°C, and this was mirrored by an increase in MCT. MCT increased on average between 5 and 11 µm/s for every Hz increase in CBF. This study also showed that CBF decreased with increasing mucin concentration, dropping from 12.4 Hz at 2% bovine submaxillary mucin (BSM) to 10.1 Hz at 8% BSM, concurrent with a ca. 70% reduction in MCT. In addition, treatment with 10 µM basolateral forskolin reproducibly increased CBF by 19.3±2.1% and MCT by 24.4±3.1% over baseline (Sears et al., 2015). In sheep trachea CBF and mucus transport velocity (MTV) were 9.8±2.7 beats/s and 5.7±2.6 mm/min, respectively, at baseline. Temperature reductions from 37°C to 34°C caused a progressive decline in CBF (ca. –20% at 2 h and –90% at 4 h) and MTV (ca. –50% at 2 h and –90% at 4 h), which was further exacerbated by additional temperature decreases (30°C; CBF: ca. –75% at 2 h; MTV: –80% at 2 h) (Kilgour et al., 2004). Frog palate preparations were incubated with 1.25, 2.5 and 5.0 ppm formaldehyde. At formaldehyde doses of 2.5 and 5 ppm, CBF decreased by ca. 25% compared to baseline within 30 min and by 35-50% within 60 min (Fló-Neyret et al., 2001). Incubation of frog palates with PM10 from Sao Paolo, Brazil, for up to 120 min did not affect CBF but decreased MCT at concentrations ≥1000 pg/m3 (Macchione et al., 1999) In freshly excised sheep tracheas, a 60-min incubation with 10 µM platelet-activating factor caused a 6% decrease in CBF and a dose-dependent decrease in surface liquid velocity, reaching a maximum of 63% (Seybold et al., 1990). In patients with bronchiectasis, nasal CBF was 12.8±1.3 Hz and nasal clearance time was 31.8± 18.4 min. In comparison, in healthy controls, nasal CBF was 14.0±1.3 Hz and nasal clearance time was 17.6± 8.3 min (Rutland and Cole, 1981). Following basolateral treatment of human sinonasal epithelial cell cultures grown at the air-liquid interface with  Myrtol®, a phytopharmaceutical mixture of distillates of rectified essential oils of eucalyptus, sweet orange, myrtle, and lemon as the active ingredients, increased CBF in a dose-dependent manner, with a maximum stimulation with 0.1% of 48±7% after 30 min. The same concentration caused a 46±16% increase in MCT at 40 min (Lai et al., 2014). In New Zealand white rabbits exposed to 3 ppm NO2 for 24 h, the average CBF decreased from 764 beats/min to 692 beats/min, and the transport velocity decreased from 5.23 mm/min to 3.03 mm/min (Kakinoki, 1998).

A 20-minute exposure of dogs to SO2 caused a decrease in mean bronchial MCC after 90 min (Yeates et al., 1997). Frog palate epithelia were incubated with 1.25, 2.5 and 5.0 ppm formaldehyde. At formaldehyde doses of 2.5 and 5 ppm, CBF decreased by ca. 25% compared to baseline within 30 min and by 35-50% within 60 min (Fló-Neyret et al., 2001). Incubation of freshly excised sheep tracheas with 10 µM platelet-activating factor caused a maximal decrease in CBF of 6% after 60 min and decrease in surface liquid velocity of ca. 30% at 20 min, ca. 50% at 40 min and 63% after 60 min (Seybold et al., 1990). Following basolateral treatment of human sinonasal epithelial cell cultures grown at the air-liquid interface with different concentrations of Myrtol®, CBF increased rapidly within the first 30 min and then declined thereafter. The maximum response for MCT was seen after 40 min (Lai et al., 2014).

Unknown

High Mixed

High

All life stages

High Not Specified Not Specified Not Specified Not Specified Not Specified

Evidences for this KER are derived from studies carried out in dog, gunea pig, rat, frog, sheep, rabbit model systems as well as in human epithelial cell cultures. MCC and CBF were observed to decrease with age in several species (e.g. guinea pigs, mice, and human) (Bailey et al., 2014; Grubb et al., 2016; Ho et al., 2001; Joki and Saano, 1997; Paul et al., 2013; Yager et al., 1978), but evidence by (Agius et al., 1998) suggests that age does not have a major effect on CBF.

#<Reference::ActiveRecord_Associations_CollectionProxy:0x00007b430b10ac88> AOPWiki 2021-07-19T10:24:02

2023-03-24T08:17:45

<upstream-id>76d10b3b-ae16-47bc-a711-4ffef74ad4d6</upstream-id> <downstream-id>97c1443c-ec6b-4f69-aa33-6ed51112a7df</downstream-id> It is very well known that patients suffering from motile ciliopathies, such as primary ciliary dyskinesia, have impaired or absent MCC and lower lung function (reduced FEV1 and FVC) compared to their healthy counterparts (Halbeisen et al., 2018; Marthin et al., 2010; Wallmeier et al., 2020). In cystic fibrosis patients, decreased MCC (due to reduced airway hydration and changes in mucus chemical and viscoelastic properties) causes mucus build-up leading to mucus plugging in the airways and consequently to decreased lung function over time (Kerem et al., 2014; Mossberg et al., 1978; Regnis et al., 1994; Robinson and Bye, 2002; Szczesniak et al., 2017; Wanner et al., 1996). Mucus plugging due to decreased MCC is also considered a major cause of airway obstruction and airflow limitation in COPD patients (Dunican et al., 2021; Okajima et al., 2020) and asthmatics (Kuyper et al., 2003; Maxwell, 1985).

Changes in MCC rate are typically paralleled by effects on lung function in several studies where both endpoints have been assessed. In patients with primary ciliary dyskinesia, absence of cilia motion prevents normal MCC and consequently, lung function is reduced (Denizoglu Kulli et al., 2020). In cystic fibrosis patients, the ASL is depleted resulting in impaired MCC (Boucher, 2004). Although the known CFTR genotypes can result in a variety of phenotypes (Derichs, 2013), clinical data indicate that some specific gene defects, such as the p.Phe508del variant, are more frequently associated with decreased lung function indices (e.g. FEV1 % predicted, FVC % predicted, FEF25-75) (Kerem et al., 1990; Johansen et al., 1991; Schaedel et al., 2002). Both cigarette smoking and occupational exposure to biomass fumes led to slower MCC and reduced FEV1 % predicted and FEV1/FVC (Ferreira et al., 2018). Nasomucociliary clearance was slower in COPD smokers compared to former smokers with COPD or to nonsmokers (Ito et al., 2015). Allergen challenge in asthma patients resulted in both reduced MCC and FEV1, which could be reversed by inhalation of hypertonic saline solution (Alexis et al., 2017). In cystic fibrosis patients, treatment with mucolytic agents (Laube et al., 1996; McCoy et al., 1996; Quan et al., 2001; Elkins et al., 2006; Amin et al., 2011; Donaldson et al., 2018) or a CFTR potentiator (Rowe et al., 2014) improved both MCC and lung function (FEV1, FVC and FEF25-75).

Lung function is known to decrease with age, and several studies showed that mucus transport rates also decrease in older compared to younger individuals (Goodman et al., 1978; Uzeloto et al., 2021). Impaired MCC is also seen in chronic smokers, even prior to a clinically significant drop in lung function and the detection of small airway disease (Clunes et al., 2012a; Goodman et al., 1978; Lourenço et al., 1971; Uzeloto et al., 2021; Vastag et al., 1986), and in patients with obstructive lung disease and hence, poor lung function (Cruz et al., 1974; Vastag et al., 1986). Adult asthmatics also displayed decreased mucus transport rates/velocities in addition to decreased lung function (Ahmed et al., 1981; Bateman et al., 1983; Foster et al., 1982; Mezey et al., 1978). In patients with primary ciliary dyskinesia, absence of cilia motion prevents normal MCC and consequently, lung function is reduced (Denizoglu Kulli et al., 2020). In cystic fibrosis patients, the ASL is depleted resulting in impaired MCC (Boucher, 2004a). Although the known CFTR genotypes can result in a variety of phenotypes (Derichs, 2013), clinical data indicate that some specific gene defects, such as the p.Phe508del variant, are more frequently associated with decreased lung function indices (e.g. FEV1 % predicted, FVC % predicted, FEF25-75) (Johansen et al., 1991; Kerem et al., 1990; Schaedel et al., 2002). Unsurprisingly, results from studies with pharmacological agents aimed at restoring CFTR function do not only indicate enhanced MCC but also support improvements in lung function (Bennett et al., 2018; Donaldson et al., 2018; Rowe S. M. et al., 2014a). While the available data link these two KEs, causal evidence is not always available, and some inference is present. Therefore, we judge the biological plausibility of this KER as moderate.

Occupational exposure to biomass combustion products resulted in slower MCC and reduced FEV1 % predicted and FEV1/FVC (Ferreira et al., 2018). Compared to healthy controls, current smokers without airway obstruction and current smokers with COPD exhibited longer saccharin transit times, indicative of impaired MCC, and lower FEV1 % predicted and FEV1/FVC (Uzeloto et al., 2021). Similarly, nasomucociliary clearance was slower in COPD smokers compared to former smokers with COPD or to nonsmokers (Ito et al., 2015). Additionally, mucus plug density—assessed by CT imaging—and mucoid (rather than watery) consistency were inversely related to FEF25–75% and associated with increased RV/TLV (Kesimer et al., 2018). Asthma patients responded to allergen challenge with a reduction in both MCC and FEV1 (Bennett et al., 2011; Mezey et al., 1978), which could be rescued by inhalation with hypertonic saline solution (Alexis et al., 2017). Multiple studies interrogating the effect of mucolytic agents such as hypertonic saline solution or recombinant DNase on mucus transport rates or mucus clearance in patients with cystic fibrosis report improvements in both, mucus transport velocities or rates and lung function indices, including FEV1, FVC and FEF25-75 (Amin et al., 2011; Donaldson et al., 2018; Elkins et al., 2006; Laube et al., 1996; McCoy et al., 1996; Quan et al., 2001). Both MCC and lung function (FEV1, FVC and FEF25-75) improved in cystic fibrosis patients treated with ivacaftor, a CFTR potentiator that increases the channel open probability (Rowe et al., 2014b). Some studies with mucolytics such as N-acetylcysteine, bromhexine, theophylline/ambroxol or sorebrol demonstrated improved MCC was connected with small improvements in lung function (FEV1, FVC and FEV1/FVC) in patients with chronic bronchitis (Aylward et al., 1980; Castigiioni and Gramolini, 1986; Thomson et al., 1974; Würtemberger et al., 1988).

Genetic defects leading to motile ciliopathies or defects in CFTR function are linked to impaired MCC. However, because of the genetic variety, not every defect, for example in the CFTR gene, also expresses an overt pulmonary phenotype. Other factors, such as low-level chronic inflammation may drive lung pathology by pathways independent of MCC. This might also explain the absence of differences in MCC between healthy smokers and smokers with COPD (Fleming et al., 2019). Not all studies looking to elucidate the effect of mucolytics on MCC report an improvement of lung function, even though mucus transport rates or tracheobronchial clearance significantly improve. These studies include, for example, some on the effects of hypertonic saline solution, NAC, ambroxol and 2-mercapto-ethane sulphonate (Clarke et al., 1979; Ericsson et al., 1987; Millar et al., 1985; Robinson et al., 1997; Würtemberger et al., 1988). This could be, at least in part, related to the fact that a sudden drop in lung function served as an indicator of patient distress in these studies, and interventions were halted when they occurred to ensure patient safety (Robinson et al., 1996). Another reason could be related to the mechanisms underlying mucus solubilization that may be completely independent of lung function. MCC is only one means by which mucus can be cleared from the lungs. Another one is cough clearance, and it is highly dependent on the properties of the ASL, in particular the ASL height (Knowles and Boucher, 2002).

Invariably, if mucus viscosity increases (independent of whether that results from increased mucus production (hypersecretion), depletion of the ASL or another cause) and MCC decreases, another mechanism comes into action to clear excess mucus: cough clearance. Cough constitutes a “backup” host defense by which acutely or chronically accumulated mucus is expelled through forceful, high-velocity airflow (Button et al., 2018; King, 2006). Our current understanding of the mechanical principles and biology of cough suggest that failure of cough clearance may also be a contributor to decreased lung function.

The available data, though not causally linking decreases in MCC with decreased lung function, provide a good insight into the importance of the physiological role of MCC in maintaining normal lung function. In at least some studies, impairment of MCC correlated with the drop in FEV1 or FEF25-75. Although clinically valuable benefits can be seen in studies with pharmacological agents such as mucolytics and CFTR modifying drugs, they do not cover a wide range of dose responses nor are they supportive of the KER causality. Therefore, we judge our quantitative understanding as moderate.

Sixteen Brazilian sugarcane workers aged 25±4 years, with a BMI of 24±3 kg/m2, with exhaled CO of 2.1±1.5 ppm, were examined during the non-harvest season and during the sugarcane burning harvest season. There was a non-significant decrease in saccharin transit time (from 8±1 min to 3±1 min) and a significant decrease  FEV1/FVC ratio (from 88.62±5.68 to 84.90±6.47) and %FEV1 (from 92.19±13.24 to 90.44±12.76) during harvest compared with the non-harvest season (Ferreira et al., 2018). 12 (6M/6F) mild allergic, non-smoking asthmatics ages 20–39 with skin sensitivity to house dust mites (HDM) and normal baseline lung function (FEV1 %pred > 80, FEV1/FVC ratio >0.70) inhaled sequential doses of inhaled HDM extract (D. farinae, Greer®, Lenoir, NC) delivered as 5 inhalations from a Devilbiss 646 nebulizer (mass median aerodynamic diameter of 5 um, GSD = 2.0). Five of the 12 patients responded to the allergen challenge with >10% reductions in FEV1 % predicted and reduction in whole lung MCC as evidenced by increased retention rates (mean Central TB Ave120Ret increased from 0.69 to 0.79 for baseline vs. allergen challenge respectively). This reduction in MCC significantly correlated with the post challenge 24 hour FEV1 (Bennett et al., 2011). Treatment of patients with chronic bronchitis with bromhexine (3 x 16 mg/day) for 14 days resulted in mean changes in FEV1, FVC and FEV1/FVC of + 0.047 L + 0.033 L and +0.6%, respectively, with MCC at 6 h being 6.8% greater after treatment compared to baseline (Thomson et al., 1974). Treatment of patients with chronic bronchitis with ambroxol alone (2 x 30 mg/day) or with theophyllin (2 x 400 mg/day) and ambroxol (2 x 30 mg/day) for 7 days MCC/h improved from 18.3 ± 11.1% to 23.3 ± 13% and 29.6 ± 15.7%, respectively whereas lung function remained nearly unchanged with FEV1 predicted of 86.0 ± 9.78 at baseline vs 83.7 ± 9.27 (ambroxol only) and 83.1 ± 11.07 (combination) (Würtemberger et al., 1988). Treatment of chronic bronchitics with N-acetylcysteine (4 mg/day by metered dose inhaler) for 16 weeks significantly improved sputum viscosity (-0.53 vs -0.67; differences between medians to placebo: 0-14 (-0.77 0.64)) and minimally improved FVC (3.0±0.21 vs 2.9± 0.18 L/s) and PEF (356.7 ±29.64 L/min vs 354.6±25.07) but not FEV1 (1.9±0.18 vs 2.0± 0.13 L/s) (Dueholm et al., 1992). Treatment of asthmatics with salmeterol improved tracheobronchial clearance rates (AUC: 333±24%h vs 347±30%h in placebo) as well as FEV1 (76 ± 8), FVC (100 ± 5) and PEF % predicted (100 ± 7) compared to placebo (73 ± 8; 95 ± 5; 94 ± 7) (Hasani et al., 2003). Treatment of mild-to-moderate bronchitics with 42 µg salmeterol slightly enhanced whole lung clearance in 2 hr (not significant; C10–2= 25±11% vs 22±10% in placebo), significantly increased mean  peripheral lung clearance (C10–2= 22±9% vs 17±10% in placebo) and significantly increased FEV1 %pred and FEF25–75 at 2 h compared to baseline (93±18%predicted, 2.45 ± 1.08 L/s vs 88±19%predicted, 2.27 ± 0.98 L/s in placebo) (Bennett et al., 2006). Sputum induction by inhalation of hypertonic saline solution (5%) in asthmatics at 6 hr following challenge with LPS significantly improved FEV % predicted by approx. 20% and was accompanied by a ca. 6-fold increase in whole lung clearance (from 0.1 %/min to 0.6%/min) (Alexis et al., 2017). 133 cystic fibrosis patients (age (mean [SD]) was 21.1 (11.4) years and 46.4% were female. All participants had one copy of the G551D mutation, and 72.2% were compound heterozygous with F508del on the other allele.) completed a 6-month course of ivacaftor. Lung function improved from baseline FEV1% predicted of 82.6 (25.6) to 90.1 (25.0) (mean change, 6.7; 95% CI, 4.9–8.5). In a subgroup of 22 patients, particle clearance from the whole right lung was markedly increased. Average clearance through 60 minutes at 1 month post-treatment was more than twice the baseline value, reflecting substantially improved MCC (Rowe et al., 2014b). Inhalation of hypertonic saline solution (7%, 4 mL twice daily for 48 weeks) by cystic fibrosis patients improved FVC (by 82 mL; 95 percent confidence interval, 12 to 153) and FEV1 (by 68 mL; 95 percent confidence interval, 3 to 132) values, but not FEF25–75 (Elkins et al., 2006). In cystic fibrosis patients that inhaled hypertonic saline solution without amiloride twice a day over a period of 14 days one-hour mucus clearance rates improved from baseline (9.3±1.6%) to 14.0±2.0% and increased FEV1 by 6.2%. FVC and FEF25-75 also improved by 1.8% and 13.1%, respectively (Donaldson et al., 2006). Dornase alfa (recombinant human DNase) is currently used as a mucolytic to treat pulmonary disease in cystic fibrosis. It reduces mucus viscosity in the lungs, promoting improved clearance of secretions (Yang and Montgomery, 2021). In children with cystic fibrosis (mean: 8.4 yrs of age with FEV1 ≥95% predicted) treated with dornase alfa for 96 weeks, FEV1 % predicted improved by 3.2 ± 1.2, FVC % predicted improved by 0.7 ± 1.0, and FEF25-75 % predicted improved by 7.9 ± 2.3 compared to placebo (Quan et al., 2001). In young patients with cystic fibrosis (6-18 yrs of age with FEV1 ≥80% predicted) treated with dornase alfa for 96 weeks, FEF25-75 % predicted improved by 6.1±10.34 compared to placebo (Amin et al., 2011). In 10 adult cystic fibrosis patients receiving 2.5 mg rhDNase twice a day for 6 days, FEV1 and FVC increased by an average of 9.4 ± 3.5% and 12.7 ± 2.6%, respectively, as compared with a decrease of 1.8 ± 1.7% and an increase of 0.4±1.1% in the placebo group, respectively, although there were no significant changes in MCC (Laube et al., 1996). In 320 cystic fibrosis patients (7 to 57 yrs of age), dornase alfa treatment at 2.5 mg/day for 12 weeks (McCoy et al., 1996). Saccharin transit times (a marker of nasal MCC) were higher in healthy current smokers and COPD smokers than in healthy controls (10.87 [7.29–17] min and 16.47 [8.25–20.15] min, respectively, vs 8.52 [5.54–13.91] min). These groups also differed in their lung function indices: FEV1 % predicted was 101.4 ± 12.37 in healthy controls, 96.41 ± 12.3 in healthy current smokers, and 67.96 ± 24.02 in COPD smokers. FVC % predicted was 103.1 ± 13.45 in healthy controls, 97.51 ± 12.88 in healthy current smokers, and 90.33 ± 29.27 in COPD smokers. FEV1/FVC % predicted was 82.15 [78.5–85] in healthy controls, 82.20 [79.2–84.1] in healthy current smokers, and 61.1 [55.3–67.2] in COPD smokers (Uzeloto et al., 2021). Saccharin transit time of smokers with COPD (16.5 [11–28] min, median [interquartile range 25–75%]) was slightly longer than that of current smokers (15.9 [10 –27] min), and both were longer compared with exsmokers with COPD (10.2 [6 –12] min) and nonsmokers (8 [6 –16] min). Lung function parameters for the groups were as follows: nonsmokers, FEV1/FVC 0.84 ± 0.09, FEV1 % predicted  103.2 ± 11.5, FVC % predicted 102.2 ± 13.3; current smokers, FEV1/FVC 0.76 ± 0.05, FEV1 % predicted  90.7 ± 7.4, FVC % predicted 96.3 ± 13.9; former smokers with COPD, FEV1/FVC 0.49 ± 0.08, FEV1 % predicted  46.8 ± 12.6, FVC % predicted 76.8 ± 18.5; current smokers with COPD, FEV1/FVC 0.66 ± 0.16, FEV1 % predicted  48.7 ± 16.8, FVC % predicted 71.7 ± 13.0 (Ito et al., 2015).

Six asymptomatic patients with bronchial asthma and a history of allergic pollenosis and episodic bronchospasm consistent with ragweed hypersensitivity wer challenged by inhalation of an aqueous, short ragweed antigen extract (Greer Laboratories, Lenoir, N.C.), diluted with a phosphate-buffered saline solution. Mean tracheal mucus velocity (TMV) decreased to 72% of baseline immediately after challenge when specific airway conductance (SGaw), and FEV1 showed a maximal decrease, with a further decrease to 47% of baseline after 1 h, when SGaw and FEV1 had returned to baseline values (Mezey et al., 1978). Treatment of chronic bronchitics with N-acetylcysteine (3 x 200 mg/day) for 4 weeks significantly decreased sputum thickness, increased sputum pourability from 650% glycerol time (at baseline) to 320% glycerol time on day 21 and PEFR on days 28 (+5%), 35 (+6%) and 42 (+7%) and FEV1 on days 21 (+2%), 28(+3%), 35 (+4%) and 42 (+5%) compared to baseline (ca. 33% predicted and 28% predicted, respectively) (Aylward et al., 1980). Treatment of mild-to-moderate bronchitics with 42 µg salmeterol slightly enhanced whole lung clearance in 2 hr (not significant; C10–2= 25±11% vs 22±10% in placebo), significantly increased mean  peripheral lung clearance (C10–2= 22±9% vs 17±10% in placebo) and significantly increased FEV1 %pred and FEF25–75 at 2 h compared to baseline (93±18%predicted, 2.45 ± 1.08 L/s vs 88±19%predicted, 2.27 ± 0.98 L/s in placebo) , and significantly increased FEV1 %pred and FEF25–75 at both 1 (92±19%predicted, 2.44 ± 1.14 L/s) and 2 h (93±18%predicted, 2.45 ± 1.08 L/s) compared to baseline (pre-dose; 90 ± 20%predicted, 2.16 ± 0.92 L/s) (Bennett et al., 2006). In cystic fibrosis patients on a 6-month ivacaftor regimen, FEV1% improvement was detectable as soon as the 1-month follow-up visit (mean change, 6.7; 95% CI, 5.2–8.3) (Rowe et al., 2014b). MCC remained at elevated level at the month 3 visit (Donaldson et al., 2018). One-hour mucus-clearance rates in cystic fibrosis patients receiving hypertonic saline with placebo were significantly faster than in the group receiving hypertonic saline with amiloride (14.0±2.0 vs. 7.0±1.5 %), and the durability of response following the inhalation of hypertonic saline with placebo was ≥8 hours (Donaldson et al., 2006).

Unknown

High Mixed

High

All life stages

High

The evidences for this KER come from and therefore apply to humans.

#<Reference::ActiveRecord_Associations_CollectionProxy:0x00007b430b13c6c0> AOPWiki 2021-07-19T10:24:31

2023-03-24T08:27:51

Oxidative stress Leading to Decreased Lung Function

Brendan Ferreri-Hanberry

Karsta Luettich, Philip Morris Products S.A., Philip Morris International R&D, Neuchatel, Switzerland Hasmik Yepiskoposyan, Philip Morris Products S.A., Philip Morris International R&D, Neuchatel, Switzerland Monita Sharma, PETA Science Consortium International e.V., Stuttgart, Germany Frazer Lowe, Broughton Nicotine Services, Earby, Lancashire, United Kingdom Damien Breheny, British American Tobacco (Investments) Ltd., Group Research and Development, Southampton, United Kingdom

BY-SA

2.0

We propose here an AOP that attempts to delineate how exposure to oxidative insults lead to decreased lung function (Luettich et al., 2021). This AOP evaluates one of the major processes known to be involved in regulating efficient mucociliary clearance (MCC)—ciliary function. MCC is a key aspect of the innate immune defense against airborne pathogens and inhaled chemicals and is governed by the concerted action of its functional components, the cilia and the airway surface liquid (ASL), which is composed of mucus and periciliary layers (Bustamante-Marin and Ostrowski, 2017). Disturbances in any of the processes regulating ciliary function can cause MCC dysfunction. Impaired MCC is linked to airway diseases such as chronic obstructive pulmonary disease (COPD) or asthma, both of which are characterized by decreased lung function and bear a significant risk of increased morbidity and mortality. Given the individual and public health burden of the consequences of lung function impairment, gaining a greater understanding of the underlying mechanisms is extremely important in the risk assessment of respiratory toxicants. The KE proposed here are moderately to highly essential, and we judge the overall biological plausibility of this AOP as strong. The KER Oxidative stress leading to decreased CBF is supported by multiple studies across different species with ample empirical evidence reflecting both dose-response and time concordance. The KER Decreased CBF leading to decreased MCC lacks this expanse of empirical evidence, or the evidence does not fully support the causality between the KE even though the relationship is logical and plausible. Overall, our quantitative understanding of the AOP is moderate. With a surface area of ~100 m2 and ventilated by 10,000 to 20,000 liters of air per day (National Research Council, 1988; Frohlich et al., 2016), the lungs are a major barrier that protect the body from a host of external factors that enter the respiratory system and may cause lung pathologies. Mucociliary clearance (MCC) is a key aspect of the innate immune defense against airborne pathogens and inhaled particles and is governed by the concerted action of its functional components, the cilia and the airway surface liquid (ASL), which comprises mucus and the periciliary layer (Bustamante-Marin and Ostrowski, 2017). In healthy subjects, ≥10 mL airway secretions are continuously produced and transported daily by the mucociliary escalator. Disturbances in any of the processes regulating ASL volume, mucus production, mucus viscoelastic properties, or ciliary function can cause MCC dysfunction and are linked to airway diseases such as chronic obstructive pulmonary disease (COPD) or asthma, both of which bear a significant risk of increased morbidity and mortality. The mechanism by which exposure to inhaled toxicants might lead to mucus hypersecretion and thereby impact pulmonary function has already been mapped in AOP148 on decreased lung function. However, whether an exposure-related decline in lung function is solely related to excessive production of mucus is debatable, particularly in light of the close relationship between mucus, ciliary function, and efficient MCC. To date, no single event has been attributed to MCC impairment, and it is likely that events described in this AOP as well as in AOP148, AOP424, and AOP425 have to culminate to lead to decreased lung function.

Established regulatory guideline studies for inhalation toxicity focus on evident clinical signs of systemic toxicity, including death, or organ-specific toxicity following acute and (sub)chronic exposure respectively. In toxicological and safety pharmacological studies with airborne test items targeting the airways or the lungs as a whole, lung function is a relevant endpoint for the characterization of potential adverse events (OECD, 2018a; Hoymann, 2012). Hence, the AO “decreased lung function” is relevant for regulatory decision-making in the context of (sub)chronic exposure (OECD, 2018b; OECD, 2018c). Regulatory relevance of the AO “decreased lung function” is evident when looking at the increased risk of diseases in humans following inhalation exposure, and because of its links to other comorbidities and mortality. To aid diagnosis and monitoring of fibrosis, current recommendations include both the recording of potential environmental and occupational exposures as well as an assessment of lung function (Baumgartner et al., 2000). The latter typically confirms decreased lung function as demonstrated by a loss of lung volume. As the disease progresses, dyspnea and lung function worsen, and the prognosis is directly linked to the decline in FVC (Meltzer and Noble, 2008). Chronic exposure to cigarette smoke and other combustion-derived particles results in the development of COPD. COPD is diagnosed on the basis of spirometry results as laid out in the ATS/ERS Task Force documents on the standardization of lung function tests and their interpretation (Pellegrino et al., 2005; Culver et al., 2017, Graham et al., 2019). Rapid rates of decline in the lung function parameter FEV1 are linked to higher risk of exacerbations, increased hospitalization and early death (Wise et al., 2006; Celli, 2010). Reduced FEV1 also poses a risk for serious cardiovascular events and mortality associated with cardiovascular disease (Sin et al., 2005; Lee et al., 2015).

adjacent

High

High adjacent

Moderate

High adjacent

Moderate

Not Specified Mixed

Not Specified

All life stages

High

The experimental evidence to support the biological plausibility of the KERs from MIE to AO is moderate to strong overall for the AOP presented here, while there is a moderate concordance of dose-response relationships. In terms of essentiality, we have rated all of the KEs as either moderate or high. AOPs such as this one can play a central role in risk assessment strategies for a wide variety of regulatory purposes by providing mechanistic support to an integrated approach to testing and assessment (IATA; (Clippinger et al., 2018)). IATAs are flexible frameworks that can be adapted to best address the regulatory question or purpose at hand. More specifically, this AOP can be applied to the risk assessment of inhaled toxicants, by enabling the development of testing strategies through the assembly of existing information and the generation of new data where they are currently lacking. Targeted approaches to fill data gaps can be developed using new approach methodologies (NAMs) informed by this AOP. All KE proposed in this AOP occur and are measurable in several species, including frogs, mice, rats, guinea pigs, ferrets, cats, dogs, cows, monkeys, and humans. The majority of the supporting empirical evidence derives from studies in rodent and human systems, and experimental findings in animals appear to be highly translatable to humans. Data regarding the applicability of KE to all life-stages from birth to adulthood are available for the MIE (Oxidative Stress), KE1908 (Cilia Beat Frequency, Decreased), KE1909 (Mucociliary Clearance, Decreased), and AO (Decreased Lung Function), and indicate that they apply to all life stages. It is also worth noting here that age-dependent decreases in CBF, MCC, and lung function have been demonstrated in several species (e.g., guinea pigs, mice, and humans) and reflect normal physiological aging processes (Bailey et al., 2014; Grubb et al., 2016; Ho et al., 2001; Joki and Saano, 1997; Paul et al., 2013; Sharma and Goodwin, 2006). Gender-specific data relevant to the AOP network are not as widely available as species-specific data, and to our knowledge, the role of gender has not been systematically evaluated for all KE described here. Informative evidence on gender differences stems from patients with chronic pulmonary diseases, such as cystic fibrosis, asthma, COPD, and bronchiectasis, that are characterized by decreased lung function. Considering the importance of efficient MCC—brought about by the interactions of ciliary function, ASL homeostasis and mucus properties—for normal physiological function, we consider this AOP applicable to both genders.

The definition of essentiality implies that the modulation of upstream KEs impacts the downstream KEs in an expected fashion. If blocked or failing to occur, the KEs in the current AOP will not necessarily stop the progression to subsequent KEs. Due to the complex biology of motile cilia formation and function, ASL homeostasis, mucus properties and their concerted impact on MCC, the KEs and AO may be triggered because of alternative pathways or biological redundancies. However, when exacerbated, the KEs promote the occurrence of downstream events eventually leading to the AO. The causal pathway starting from the exposure to oxidants and leading to decreased lung function involves parallel routes with KEs, each of which is sufficient to cause the downstream KE to occur. Based on the evidence we judge the MIE (Oxidative Stress), KE1908 (Cilia Beat Frequency, Decreased), and KE1909 (Mucociliary Clearance, Decreased) as highly essential.

We judge the overall biological plausibility of this AOP as strong. The KER Oxidative stress leading to decreased CBF is supported by multiple studies across different species with ample empirical evidence reflecting both dose-response and time concordance. The KER Decreased CBF leading to decreased MCC lacks this expanse of empirical evidence, or the evidence does not fully support the causality between the KE even though the relationship is logical and plausible.

Overall, our quantitative understanding of the AOP network is moderate. There is robust evidence that provides an insight into the KER Oxidative stress leading to decreased cilia beat frequency and Decreased cilia beat frequency leading to decreased MCC, and the dose response and temporal relationship between the two KE in question are well described and quantified for different stressors across different test systems. In some instances, we are less confident in our quantitative understanding. For example, dose response data as well as data supportive of the KE causality are limited for the KER Decreased MCC leading to decreased lung function.

Given the individual and public health burden of the consequences of lung function impairment, gaining a greater understanding of the underlying mechanisms is extremely important in the risk assessment of respiratory toxicants. An integrated assessment of substances with the potential to be inhaled, either intentionally or unintentionally, could incorporate inhalation exposure and dosimetry modelling to inform an in vitro approach with appropriate exposure techniques and cell systems to assess KEs in this AOP (EPA’s Office of Chemical Safety and Pollution Prevention, 2019). Standardization and robustness testing of assays against explicit performance criteria using suitable reference materials can greatly increase the level of confidence in their use for KE assessment (Petersen et al., 2021). Much of the empirical evidence that supports the KERs in the qualitative AOP described here was obtained from in vitro studies using well-established methodologies for biological endpoint assessment. Being chemical agnostic, this AOP can be applied to a variety of substances that share the AO. For example, impaired MCC and decreased lung function have a long-known relationship with smoking, but little is known about the consequences of long-term use of alternative inhaled nicotine delivery products such as electronic cigarettes and heated tobacco products. This AOP can form the basis of an assessment strategy to evaluate the effects of exposure to aerosol from these products based on the KEs identified here.

Moderate

High

Low

Bailey, K.L., Bonasera, S.J., Wilderdyke, M., Hanisch, B.W., Pavlik, J.A., DeVasure, J., et al. (2014). Aging causes a slowing in ciliary beat frequency, mediated by PKCε. Am. J. Physiol. Lung Cell. Mol. Physiol. 306, L584-L589. Bustamante-Marin, X.M., and Ostrowski, L.E. (2017a). Cilia and Mucociliary Clearance. Cold Spring Harb. Persp. Biol. 9, a028241.  Clippinger, A.J., Allen, D., Behrsing, H., BéruBé, K.A., Bolger, M.B., Casey, W., et al. (2018). Pathway-based predictive approaches for non-animal assessment of acute inhalation toxicity. Toxicol. In Vitro 52, 131-145. EPA’s Office of Chemical Safety and Pollution Prevention (2019). "FIFRA Scientific Advisory Panel Meeting Minutes and Final Report No. 2019-01 Peer Review on Evaluation of a Proposed Approach to Refine the Inhalation Risk Assessment for Point of Contact Toxicity: A Case Study Using a New Approach Methodology (NAM) December 4 and 6, 2018 FIFRA Scientific Advisory Panel Meeting". U.S. Environmental Protection Agency). Frohlich, E., Mercuri, A., Wu, S., and Salar-Behzadi, S. (2016). Measurements of Deposition, Lung Surface Area and Lung Fluid for Simulation of Inhaled Compounds. Front. Pharmacol. 7, 181.  Grubb, B.R., Livraghi-Butrico, A., Rogers, T.D., Yin, W., Button, B., and Ostrowski, L.E. (2016). Reduced mucociliary clearance in old mice is associated with a decrease in Muc5b mucin. Am. J. Physiol. Lung Cell. Mol. Physiol. 310, L860-L867. Ho, J.C., Chan, K.N., Hu, W.H., Lam, W.K., Zheng, L., Tipoe, G.L., et al. (2001). The effect of aging on nasal mucociliary clearance, beat frequency, and ultrastructure of respiratory cilia. Am. J. Respir. Crit. Care Med. 163, 983-988. Joki, S., and Saano, V. (1997). Influence of ageing on ciliary beat frequency and on ciliary response to leukotriene D4 in guinea-pig tracheal epithelium. Clin. Exp. Pharmacol. Physiol. 24, 166-169. Luettich, K., Sharma, M., Yepiskoposyan, H., Breheny, D., and Lowe, F. J. (2021). An Adverse Outcome Pathway for Decreased Lung Function Focusing on Mechanisms of Impaired Mucociliary Clearance Following Inhalation Exposure. Frontiers in Toxicology, 55. National Research Council (1988). Air Pollution, the Automobile, and Public Health. Washington, DC: The National Academies Press. Paul, P., Johnson, P., Ramaswamy, P., Ramadoss, S., Geetha, B., and Subhashini, A. (2013). The effect of ageing on nasal mucociliary clearance in women: a pilot study. ISRN 2013, 598589. Petersen, E.J., Sharma, M., Clippinger, A.J., Gordon, J., Katz, A., Laux, P., et al. (2021). Use of Cause-and-Effect Analysis to Optimize the Reliability of In Vitro Inhalation Toxicity Measurements Using an Air–Liquid Interface. Chem. Res. Toxicol. 34, 1370–1385. Sharma, G., and Goodwin, J. (2006). Effect of aging on respiratory system physiology and immunology. Clin. Interv. Aging 1, 253-260.  AOPWiki 2021-07-19T09:29:14

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