Differential contribution of complement receptor C5aR in myeloid and non-myeloid cells in chronic ethanol-induced liver injury in mice

• Published in: Molecular immunology 2016-07, Vol.75, p.122-132
• Main Authors: McCullough, Rebecca L., McMullen, Megan R., Das, Dola, Roychowdhury, Sanjoy, Strainic, Michael G., Medof, M. Edward, Nagy, Laura E.
• Format: Article
• Language: English
• Subjects: Alcoholic liver disease; Animals; Apoptosis; Blotting, Western; Complement; Disease Models, Animal; Ethanol - toxicity; Female; Hepatocytes; Hepatocytes - immunology; Immunohistochemistry; Inflammation; Liver Diseases, Alcoholic - immunology; Liver Diseases, Alcoholic - pathology; Mice; Mice, Inbred C57BL; Mice, Knockout; Myeloid Cells - immunology; Real-Time Polymerase Chain Reaction; Receptor, Anaphylatoxin C5a - immunology
• ISSN: 0161-5890; 1872-9142
• DOI: 10.1016/j.molimm.2016.05.006

•Chronic ethanol-induced liver injury was studied in C5aR-/-, myeloid specific C5aR-/- and non-myeloid specific C5aR-/- mice.•Global C5aR-/- mice were protected from ethanol-induced pro-inflammatory cytokine production but still had elevated markers of liver injury.•Non-myeloid specific C5aR-/- expressed more pro-inflammatory mediators and hepatocyte apoptosis following chronic ethanol feeding.•C5a increased activation of cell-protective signaling pathways and protected hepatocytes from cytotoxicity induced by ethanol and TNFα. Complement is implicated in the development of alcoholic liver disease. C3 and C5 contribute to ethanol-induced liver injury; however, the role of C5a receptor (C5aR) on myeloid and non-myeloid cells to progression of injury is not known. C57BL/6 (WT), global C5aR-/-, myeloid-specific C5aR-/-, and non-myeloid-specific C5aR-/- mice were fed a Lieber-DeCarli diet (32%kcal EtOH) for 25 days. Cultured hepatocytes were challenged with ethanol, TNFα, and C5a. Chronic ethanol feeding increased expression of pro-inflammatory mediators in livers of WT mice; this response was completely blunted in C5aR-/- mice. However, C5aR-/- mice were not protected from other measures of hepatocellular damage, including ethanol-induced increases in hepatic triglycerides, plasma alanine aminotransferase and hepatocyte apoptosis. CYP2E1 and 4-hydroxynonenal protein adducts were induced in WT and C5aR-/- mice. Myeloid-specific C5aR-/- mice were protected from ethanol-induced increases in hepatic TNFα, whereas non-myeloid-specific C5aR-/- displayed increased hepatocyte apoptosis and inflammation after chronic ethanol feeding. In cultured hepatocytes, cytotoxicity induced by challenge with ethanol and TNFα was completely eliminated by treatment with C5a in cells from WT, but not C5aR-/- mice. Further, treatment with C5a enhanced activation of pro-survival signal AKT in hepatocytes challenged with ethanol and TNFα. Taken together, these data reveal a differential role for C5aR during ethanol-induced liver inflammation and injury, with C5aR on myeloid cells contributing to ethanol-induced inflammatory cytokine expression, while non-myeloid C5aR protects hepatocytes from death after chronic ethanol feeding.