ROCK insufficiency attenuates ozone-induced airway hyperresponsiveness in mice.
Ozone causes airway hyperresponsiveness (AHR) and pulmonary inflammation. Rho kinase (ROCK) is a key regulator of smooth muscle cell contraction and inflammatory cell migration. To determine the contribution of the two ROCK isoforms ROCK1 and ROCK2 to ozone-induced AHR, we exposed wild-type, ROCK1(+/-), and ROCK2(+/-) mice to air or ozone (2 ppm for 3 h) and evaluated mice 24 h later. ROCK1 or ROCK2 haploinsufficiency did not affect airway responsiveness in air-exposed mice but significantly reduced ozone-induced AHR, with a greater reduction in ROCK2(+/-) mice despite increased bronchoalveolar lavage (BAL) inflammatory cells in ROCK2(+/-) mice. Compared with wild-type mice, ozone-induced increases in BAL hyaluronan, a matrix protein implicated in ozone-induced AHR, were lower in ROCK1(+/-) but not ROCK2(+/-) mice. Ozone-induced increases in other inflammatory moieties reported to contribute to ozone-induced AHR (IL-17A, osteopontin, TNFα) were not different in wild-type vs. ROCK1(+/-) or ROCK2(+/-) mice. We also observed a dose-dependent reduction in ozone-induced AHR after treatment with the ROCK1/ROCK2 inhibitor fasudil, even though fasudil was administered after induction of inflammation. Ozone increased pulmonary expression of ROCK2 but not ROCK1 or RhoA. A ROCK2 inhibitor, SR3677, reduced contractile forces in primary human airway smooth muscle cells, confirming a role for ROCK2 in airway smooth muscle contraction. Our results demonstrate that ozone-induced AHR requires ROCK. Whereas ROCK1-dependent changes in hyaluronan may contribute to ROCK1's role in O3-induced AHR, the role of ROCK2 is downstream of inflammation, likely at the level of airway smooth muscle contraction.
Molecular and Integrative Physiological Sciences Program, Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts; and dkasahar@hsph.harvard.edu.
David I
DI
Kasahara
Molecular and Integrative Physiological Sciences Program, Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts; and.
Joel A
JA
Mathews
Molecular and Integrative Physiological Sciences Program, Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts; and.
Chan Y
CY
Park
Molecular and Integrative Physiological Sciences Program, Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts; and.
Youngji
Y
Cho
Molecular and Integrative Physiological Sciences Program, Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts; and.
Gabrielle
G
Hunt
Molecular and Integrative Physiological Sciences Program, Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts; and.
Allison P
AP
Wurmbrand
Department of Medicine, University of Chicago, Chicago, Illinois.
James K
JK
Liao
Molecular and Integrative Physiological Sciences Program, Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts; and.
Stephanie A
SA
Shore
D000818:Animals; D016535:Bronchial Hyperreactivity / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D020381:Interleukin-17 / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008817:Mice, Mutant Strains; D009119:Muscle Contraction / Q000187:drug effects / Q000235:genetics; D009130:Muscle, Smooth / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D053495:Osteopontin / Q000235:genetics / Q000378:metabolism; D010083:Oxidants, Photochemical / Q000009:adverse effects* / Q000494:pharmacology; D010126:Ozone / Q000009:adverse effects* / Q000494:pharmacology; D011014:Pneumonia / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism; D054460:rho-Associated Kinases / Q000096:biosynthesis* / Q000235:genetics
C098680:Il17a protein, mouse; D020381:Interleukin-17; D010083:Oxidants, Photochemical; C506896:Spp1 protein, mouse; D014409:Tumor Necrosis Factor-alpha; D053495:Osteopontin; D010126:Ozone; C515854:Rock1 protein, mouse; C515855:Rock2 protein, mouse; D054460:rho-Associated Kinases
bronchoalveolar lavage; fasudil; hyaluronan; inflammation; osteopontin