Background: In contrast to the deleterious effects of chronic excessive alcohol consumption on the liver and cardiovascular system, modest alcohol intake, such as 1 to 2 drinks per day, has benefits on cardiovascular mortality. Little is known about the length of time or the amounts of alcohol consumed that may cause alterations in inflammatory cells such as monocytes that are crucial to atherosclerotic vascular disease. Here, we determine in vivo effects of acute alcohol consumption on inflammatory cytokine production and nuclear regulatory factor kappaB (NF-kappaB) binding in human monocytes.
Methods: Human blood monocytes were isolated by plastic adherence before and after acute alcohol consumption (2 ml vodka/kg body weight). Lipopolysaccharide (LPS)- and superantigen-induced tumor necrosis factor alpha (TNF alpha), interleukin (IL)-1beta, and IL-10 production were then determined in monocytes by ELISA. Nuclear regulatory factor-kappaB activity of monocytes before and after alcohol consumption was estimated by electromobility shift assay and promoter-driven reporter activity. IkappaBalpha was determined by Western blotting in the cytoplasmic extracts.
Results: Eighteen hours after moderate alcohol consumption, we found a significant reduction in monocyte production of inflammatory mediators, TNF-alpha and IL-1beta, in response to LPS or staphylococcal enterotoxin B stimulation. Acute alcohol consumption inhibited LPS-induced DNA binding of the p65/p50 NF-kappaB in monocytes that regulates the expression of both the TNF-alpha and the IL-1beta genes. Consistent with this, acute alcohol treatment (25 mM) significantly reduced LPS-induced activation of an NF-kappaB-driven reporter gene suggesting inhibition of this proinflammatory signaling pathway. Further, LPS-induced IkappaBalpha degradation was not affected by acute alcohol consumption indicating an IkappaBalpha-independent mechanism, as observed earlier in the in vitro acute alcohol studies. In contrast, monocyte production of the anti-inflammatory cytokine, IL-10, was augmented by acute alcohol intake.
Conclusions: Our findings suggest that acute alcohol consumption has dual anti-inflammatory effects that involve augmentation of IL-10 and attenuation of monocyte inflammatory responses involving inhibition of NF-kappaB. These mechanisms may contribute to the beneficial effects of moderate alcohol use on atherosclerosis.