Alcohol intoxication inhibits pulmonary S100A8 and S100A9 expression in rats challenged with intratracheal lipopolysaccharide

Background: Alcohol is known to inhibit the recruitment of polymorphonuclear leukocytes (PMNs) into tissue sites including the lung. During infection and inflammation, recruited neutrophils (PMNs) release S100 proteins that function to promote the recruitment of additional phagocytes. Methods and Results: This study investigated the effects of alcohol intoxication on S100 protein production in the lung in response to lipopolysaccharide (LPS). Animals were administered alcohol (5.5 g/kg) or saline 30 minutes before intratracheal challenge with LPS (100 mg/rat). Alcohol suppressed PMN recruitment into the lung following intratracheal LPS, which was associated with an inhibition of increase in S100A8 levels in both the bronchoalveolar lavage (BAL) fluid and lysates of cells recovered by BAL at 90 minutes and 4 hours post-LPS challenge. S100A8 and S100A9 mRNA expression in cells recovered by BAL was significantly up-regulated at both 90 minutes and 4 hours after the LPS challenge, and alcohol also suppressed this response. In addition, intratracheal LPS caused a transient increase in S100A8 mRNA expression in circulating leukocytes at 90 minutes after the challenge. Similarly, this LPS-induced up-regulation of S100A8 mRNA expression was inhibited in rats intoxicated with alcohol. Conclusion: These data show that alcohol inhibits the S100 protein response in the lung, which may serve as a mechanism underlying alcohol-induced suppression of PMN recruitment into the terminal airways during pulmonary infection.