Journal
RESPIRATORY PHYSIOLOGY & NEUROBIOLOGY
Volume 172, Issue 1-2, Pages 63-71Publisher
ELSEVIER
DOI: 10.1016/j.resp.2010.05.006
Keywords
Gram-negative bacterial sepsis; Lung hypoxia/reoxygenation; Hypoxic threshold; Rat alveolar macrophages; Systems biology
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Funding
- NIH [GM-43153]
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Reductions in alveolar oxygenation during lung hypoxia/reoxygenation (H/R) injury are common after gram-negative endotoxemia. However, the effects of H/R on endotoxin-stimulated cytokine production by alveolar macrophages are unclear and may depend upon thresholds for hypoxic oxyradical generation in situ. Here INF-alpha. and IL-1 beta production were determined in rat alveolar macrophages stimulated with Escherichia coli lipopolysaccharide (LPS, serotype O55:B5) while exposed to either normoxia for up to 24 h, to brief normocarbic hypoxia (1.5 h at an atmospheric PO2 = 10 +/- 2 mm Hg), or to combined H/R. LPS-induced TNE-alpha and IL-1 beta were reduced at the peak of hypoxia and by reoxygenation in LPS + H/R cells (P < 0.01) compared with normoxic controls despite no changes in reduced glutathione (GSH) or in PGE2 production. Both TNF-alpha mRNA and NF-kappa B activation were reduced by hypoxia that suppressed superoxide anion generation. Thus, dynamic reductions in the ambient PO2 of alveolar macrophages that do not deplete GSH suppress LPS-induced TNF-alpha expression, IL-1 beta production, and NF-kappa B activation even as oxyradical production is decreased. (C) 2010 Elsevier B.V. All rights reserved.
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