Toll-like receptor 4 mediates ozone-induced murine lung hyperpermeability via inducible nitric oxide synthase.
We tested the hypotheses that 1) inducible nitric oxide synthase (iNOS) mediates ozone (O3)-induced lung hyperpermeability and 2) mRNA levels of the gene for iNOS (Nos2) are modulated by Toll-like receptor 4 (Tlr4) during O3 exposure. Pretreatment of O3-susceptible C57BL/6J mice with a specific inhibitor of total NOS (N(G)-monomethyl-L-arginine) significantly decreased the mean lavageable protein concentration (a marker of lung permeability) induced by O3 (0.3 parts/million for 72 h) compared with vehicle control mice. Furthermore, lavageable protein in C57BL/B6 mice with targeted disruption of Nos2 [Nos2(-/-)] was 50% less than the protein in wild-type [Nos2(+/+)] mice after O3. To determine whether Tlr4 modulates Nos2 mRNA levels, we studied C3H/HeJ (HeJ) and C3H/HeOuJ mice that differ only at a missense mutation in Tlr4 that confers resistance to O3-induced lung hyperpermeability in the HeJ strain. Nos2 and Tlr4 mRNA levels were significantly reduced and correlated in resistant HeJ mice after O3 relative to those in susceptible C3H/HeOuJ mice. Together, the results are consistent with an important role for iNOS in O3-induced lung hyperpermeability and suggest that Nos2 mRNA levels are mediated through Tlr4.
Kleeberger
S R
SR
Department of Environmental Health Sciences, The Johns Hopkins University School of Public Health, Baltimore, Maryland 21205, USA. skleeber@jhsph.edu
Reddy
S P
SP
Zhang
L Y
LY
Cho
H Y
HY
Jedlicka
A E
AE
D000280:Administration, Inhalation; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry / Q000166:cytology; D002199:Capillary Permeability / Q000187:drug effects*; D002452:Cell Count; D029721:Drosophila Proteins; D004791:Enzyme Inhibitors / Q000008:administration & dosage; D004847:Epithelial Cells / Q000166:cytology; D007274:Injections, Intraperitoneal; D008168:Lung / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism*; D016676:Macrophages, Alveolar / Q000166:cytology; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D009504:Neutrophils / Q000166:cytology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D010126:Ozone / Q000008:administration & dosage / Q000633:toxicity*; D011506:Proteins / Q000032:analysis; D012333:RNA, Messenger / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D019323:omega-N-Methylarginine / Q000008:administration & dosage
D029721:Drosophila Proteins; D004791:Enzyme Inhibitors; D008562:Membrane Glycoproteins; D011506:Proteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D019323:omega-N-Methylarginine; D010126:Ozone; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse