Up-regulation of microRNA-155 in macrophages contributes to increased tumor necrosis factor {alpha} (TNF{alpha}) production via increased mRNA half-life in alcoholic liver disease.
Activation of Kupffer cells (KCs) by gut-derived lipopolysaccharide (LPS) and Toll-Like Receptors 4 (TLR4)-LPS-mediated increase in TNFα production has a central role in the pathogenesis of alcoholic liver disease. Micro-RNA (miR)-125b, miR-146a, and miR-155 can regulate inflammatory responses to LPS. Here we evaluated the involvement of miRs in alcohol-induced macrophage activation. Chronic alcohol treatment in vitro resulted in a time-dependent increase in miR-155 but not miR-125b or miR-146a levels in RAW 264.7 macrophages. Furthermore, alcohol pretreatment augmented LPS-induced miR-155 expression in macrophages. We found a linear correlation between alcohol-induced increase in miR-155 and TNFα induction. In a mouse model of alcoholic liver disease, we found a significant increase in both miR-155 levels and TNFα production in isolated KCs when compared with pair-fed controls. The mechanistic role of miR-155 in TNFα regulation was indicated by decreased TNFα levels in alcohol-treated macrophages after inhibition of miR-155 and by increased TNFα production after miR-155 overexpression, respectively. We found that miR-155 affected TNFα mRNA stability because miR-155 inhibition decreased whereas miR-155 overexpression increased TNFα mRNA half-life. Using the NF-κB inhibitors, MG-132 or Bay11-7082, we demonstrated that NF-κB activation mediated the up-regulation of miR-155 by alcohol in KCs. In conclusion, our novel data demonstrate that chronic alcohol consumption increases miR-155 in macrophages via NF-κB and the increased miR-155 contributes to alcohol-induced elevation in TNFα production via increased mRNA stability.
Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
Shashi
S
Bala
Miguel
M
Marcos
Karen
K
Kodys
Timea
T
Csak
Donna
D
Catalano
Pranoti
P
Mandrekar
Gyongyi
G
Szabo
D000818:Animals; D002460:Cell Line; D002492:Central Nervous System Depressants / Q000494:pharmacology; D002908:Chronic Disease; D004195:Disease Models, Animal; D000431:Ethanol / Q000494:pharmacology; D005260:Female; D007728:Kupffer Cells / Q000187:drug effects / Q000473:pathology / Q000502:physiology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008108:Liver Diseases, Alcoholic / Q000235:genetics* / Q000473:pathology; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D020871:RNA Stability / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics* / Q000502:physiology; D015854:Up-Regulation / Q000502:physiology
D002492:Central Nervous System Depressants; D008070:Lipopolysaccharides; D035683:MicroRNAs; C532623:Mirn155 microRNA, mouse; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D000431:Ethanol