Background & aims: Conflicting results have been reported regarding the impact of hepatitis B virus X protein (HBx) expression on liver regeneration triggered by partial hepatectomy (PH). In the present report we investigated the mechanisms by which HBx protein alters hepatocyte proliferation after PH.
Methods: PH was performed on a transgenic mouse model in which HBx expression is under the control of viral regulatory elements and liver regeneration was monitored. LPS, IL-6 neutralizing antibody, and SB203580 were injected after PH to evaluate IL-6 participation during liver regeneration.
Results: Cell cycle progression of hepatocytes was delayed in HBx transgenic mice compared to WT animals. Moreover, HBx induced higher secretion of IL-6 soon after PH. Upregulation of IL-6 was associated with an elevation of STAT3 phosphorylation, SOCS3 transcript accumulation and a decrease in ERK1/2 phosphorylation in the livers of HBx transgenic mice. The involvement of IL-6 overexpression in cell cycle deregulation was confirmed by the inhibition of liver regeneration in control mice after the upregulation of IL-6 expression using LPS. In addition, IL-6 neutralization with antibodies was able to restore liver regeneration in HBx mice. Finally, the direct role of p38 in IL-6 secretion after PH was demonstrated using SB203580, a pharmacological inhibitor.
Conclusions: HBx is able to induce delayed hepatocyte proliferation after PH, and HBx-induced IL-6 overexpression is involved in delayed liver regeneration. By modulating IL-6 expression during liver proliferation induced by stimulation of the cellular microenvironment, HBx may participate in cell cycle deregulation and progression of liver disease.
Keywords: HBV; HBx; HCC; PH; hepatitis B virus; hepatitis B virus X protein; hepatocellular carcinoma; partial hepatectomy.
Copyright © 2013 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.