Acute alcohol intake impairs lung inflammation by changing pro- and anti-inflammatory mediator balance

Previous studies have shown that alcohol (ethanol [EtOH]) intoxication impairs lung immunity by affecting cytokines pivotal to the inflammatory process. The objective of this study was to test the hypothesis that acute alcohol intoxication impairs lung innate immunity by downregulating the expression of proinflammatory mediators while simultaneously upregulating anti-inflammatory mediators. EtOH was administered to the mice 0.5 h prior to an intratracheal injection of Escherichia coli lipopolysaccharide (LPS). The animals were killed either 4 or 24 h after LPS to recover plasma, lungs, and bronchoalveolar lavage fluid. Lung inflammatory cytokines tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), IL-6, macrophage inhibitory factor (MIF), IL-10, TGF-β, and receptors for TNF-α, IL-1β, IL-6, and TGF-β as well as glycoprotein (gp)130 and corticosterone (CS) levels were evaluated at mRNA and protein level. While the mRNA expression and the soluble TNF-Rp55 levels were significantly upregulated by EtOH, LPS-induced TNF-α activity, TNF-Rp55 mRNA expression, and soluble TNF-Rp55 levels were significantly suppressed. The LPS-induced expression of IL-1β, IL-6, MIF, gp130, and receptors IL-1RI, IL-1RII, and IL-6Rα were also significantly impaired by EtOH. EtOH increased significantly the basal IL-10 activity at 3 h, which continued to remain elevated even at 24 h. The EtOH effect on IL-10 activity persisted even in LPS-challenged mice. EtOH and LPS augmented lung CS levels independently of each other. EtOH suppressed upregulation of TGF-β1 mRNA expression by LPS and blocked completely LPS-induced TGF-β1 secretion. In conclusion, the data suggest that the suppression of acute lung inflammation by EtOH intoxication is largely due to impairment by EtOH of proinflammatory cytokine signaling at the levels of cytokine expression and secretion as well as receptor expression and soluble receptor activity. The augmentation by EtOH of anti-inflammatory mediators' secretion most likely shifts the cytokine balance in the anti-inflammatory direction.