title: Moderate alcohol induces stress proteins HSF1 and hsp70 and inhibits proinflammatory cytokines resulting in endotoxin tolerance.
abstract: Binge or moderate alcohol exposure impairs host defense and increases susceptibility to infection because of compromised innate immune responses. However, there is a lack of consensus on the molecular mechanism by which alcohol mediates this immunosuppression. In this study, we show that cellular stress proteins HSF1 and hsp70 play a mechanistic role in alcohol-mediated inhibition of the TLR4/MyD88 pathway. Alcohol exposure induced transcription factor HSF1 mRNA expression and DNA binding activity in primary human monocytes and murine macrophages. Furthermore, HSF1 target gene hsp70 mRNA and protein are upregulated by alcohol in monocytes. In vitro pre-exposure to moderate alcohol reduced subsequent LPS-induced NF-κB promoter activity and downstream TNF-α, IL-6 and IL-1β production in monocytes and macrophages, exhibiting endotoxin tolerance. Mechanistic analysis demonstrates that alcohol-induced HSF1 binds to the TNF-α promoter in macrophages at early time points, exerting transrepression and decreased TNF-α expression. Furthermore, association of hsp70 with NF-κB subunit p50 in alcohol-treated macrophages correlates with reduced NF-κB activation at later time points. Hsp70 overexpression in macrophages was sufficient to block LPS-induced NF-κB promoter activity, suggesting alcohol-mediated immunosuppression by hsp70. The direct crosstalk of hsp70 and HSF1 was further confirmed by the loss of alcohol-mediated endotoxin tolerance in hsp70- and HSF1-silenced macrophages. Our data suggest that alcohol-mediated activation of HSF1 and induction of hsp70 inhibit TLR4-MyD88 signaling and are required for alcohol-induced endotoxin tolerance. Using stress proteins as direct drug targets would be clinically relevant in alcohol abuse treatment and may serve to provide a better understanding of alcohol-mediated immunosuppression.
authors.affiliation: Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605.
authors.forename: Sujatha
authors.initials: S
authors.lastname: Muralidharan
authors.affiliation: Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605.
authors.forename: Aditya
authors.initials: A
authors.lastname: Ambade
authors.affiliation: Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605.
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Fulham
authors.affiliation: Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605.
authors.forename: Janhavee
authors.initials: J
authors.lastname: Deshpande
authors.affiliation: Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605.
authors.forename: Donna
authors.initials: D
authors.lastname: Catalano
authors.affiliation: Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605 pranoti.mandrekar@umassmed.edu.
authors.forename: Pranoti
authors.initials: P
authors.lastname: Mandrekar
mesh_terms: D000293:Adolescent; D000328:Adult; D000428:Alcohol Drinking / Q000009:adverse effects; D000818:Animals; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D004731:Endotoxins / Q000276:immunology; D000431:Ethanol / Q000494:pharmacology*; D005260:Female; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D000076249:Heat Shock Transcription Factors; D006801:Humans; D007108:Immune Tolerance / Q000187:drug effects*; D007249:Inflammation / Q000276:immunology*; D053583:Interleukin-1beta / Q000096:biosynthesis; D015850:Interleukin-6 / Q000096:biosynthesis; D008264:Macrophages / Q000276:immunology; D008297:Male; D051379:Mice; D008875:Middle Aged; D009000:Monocytes / Q000276:immunology; D053594:Myeloid Differentiation Factor 88 / Q000037:antagonists & inhibitors; D052002:NF-kappa B p50 Subunit / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000187:drug effects; D034622:RNA Interference; D012333:RNA, Messenger / Q000096:biosynthesis; D051197:Toll-Like Receptor 4 / Q000037:antagonists & inhibitors*; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis; D055815:Young Adult
chemical_list: D004268:DNA-Binding Proteins; D004731:Endotoxins; C000619706:HSF1 protein, human; D018840:HSP70 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; C508585:IL1B protein, human; C508600:IL6 protein, human; D053583:Interleukin-1beta; D015850:Interleukin-6; C507779:MYD88 protein, human; D053594:Myeloid Differentiation Factor 88; D052002:NF-kappa B p50 Subunit; D012333:RNA, Messenger; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D000431:Ethanol