Acute alcohol exposure induces tolerance to endotoxin and reduces pro-inflammatory cytokine production: role for hsp70 and hsp90 (44.21)

Abstract

Abstract Alcohol, a commonly abused drug in US, is linked to impaired host defense, increased susceptibility to infections. Acute alcohol exposure in humans and experimental animals attenuates endotoxin/LPS induced pro-inflammatory cell activation. Molecular mechanisms involved in these processes are unclear. Earlier, we showed that acute alcohol induces hsp70, reported to exert anti-inflammatory effects by inhibiting NFκB activity. Here we hypothesize that acute alcohol induces tolerance to a subsequent LPS challenge by regulation of hsp70 and hsp90. To test our hypothesis, RAW 264.7 mouse macrophages were exposed overnight to alcohol (25mM, 50mM) followed by LPS (100ng/ml) challenge. Pro-inflammatory cytokine, NFκB activity and heat shock transcription factor (HSF) 1, hsp70 and hsp90 expression was analyzed. Results show that overnight acute alcohol exposure decreased inflammatory cytokine, TNFα, production to a subsequent LPS challenge. Concomitantly acute alcohol induced HSF1 binding activity and hsp70 but reduced hsp90 levels in RAW macrophages. Hsp70 immunoprecipitation revealed that acute alcohol induces hsp70-NFκB-p50 complexes likely preventing NFκB DNA binding. Treatment of macrophages with hsp70 inhibitor, quercetin, partially blocked acute alcohol mediated down regulation of LPS-induced pro-inflammatory cytokine TNFα. Summarizing, our results indicate that acute alcohol induces endotoxin tolerance and reduced pro-inflammatory cytokines via HSF1 and hsp70 induction.