Published online Nov 27, 2020. doi: 10.4254/wjh.v12.i11.965
Peer-review started: July 16, 2020
First decision: September 14, 2020
Revised: September 16, 2020
Accepted: October 5, 2020
Article in press: October 5, 2020
Published online: November 27, 2020
Due to frequent association of morbidity and mortality of human immunodeficiency virus (HIV)-infection with liver injury, the inclusion of drugs with anti-fibrotic activity to the treatment of people living with HIV (PLWH) is pathogenically important. Alcohol consumption is known to speed up liver fibrosis development. Previously, we have shown that the exposure of hepatocytes to HIV and ethanol metabolites causes high oxidative stress, impairs proteasomal and lysosomal functions leading to accumulation of HIV in these cells, which end-ups with apoptotic cell death and finally, promotes progression to liver fibrosis.
The combined exposure of hepatocytes to HIV and alcohol induces hepatotoxicity and pro-fibrotic activation of hepatic stellate cells (HSC). Since HIV replication in hepatocytes is abortive, it cannot be fully controlled by antiretroviral therapy (ART) and thus, to prevent liver fibrosis progression in alcohol-abused PLWH, ART should be combined with the drugs suppressing apoptosis without enhancing HIV DNA integration in hepatocytes and decreasing pro-fibrotic activation of liver non-parenchymal cells.
The objective of this study was to investigate whether obeticholic acid (OCA) prevents HIV/ethanol metabolism-induced activation of HSC by HIV+ apoptotic hepatocyte engulfment, thereby diminishing liver fibrosis.
The study was performed on hepatocyte-like Huh7.5-CYP (RLW) cells infected with HIV ADA and exposed to acetaldehyde-generating system (AGS) in the presence or absence of OCA. As an end-point, we have measured expression of HIV-related markers (HIVgagRNA-by real-time polymerase chain reaction (PCR), p24- by western blot, HIV DNA-by semi-nested PCR, integrated HIV DNA-by ddPCR) and non-HIV-related parameters (lysosomal and proteasomal activities, hepatocytes apoptosis). We also characterized pro-fibrotic activation and inflammasome induction in HSC (LX2 cells) by HIV-containing apoptotic hepatocytes internalization.
We found that OCA attenuated HIV-AGS-induced accumulation of HIVgagRNA, HIV DNA and p24. It suppressed ROS production, restored chymotrypsin-like proteasome activity as well as cathepsin B lysosome activity and decreased apoptosis in RLW cells. Exposure of HIV-containing apoptotic hepatocytes to OCA prevented activation of inflammasome and pro-fibrotic activation of HSC.
By suppressing oxidative stress and restoring proteasomal and lysosomal functions impaired by HIV and ethanol metabolism, OCA decreases accumulation of HIV in hepatocytes, leading to down-regulation of apoptosis in these cells. OCA also reverses pro-fibrotic and inflammasome-related activation of HSC triggered by engulfment of HIV-containing apoptotic hepatocytes, potentially contributing to suppression of liver fibrosis development.
Our in vitro studies are in the frame of pre-clinical characterization of anti-fibrotic effects of OCA in alcohol-exposed PLWH with a high risk of liver fibrosis development. At the next step, these in vitro effects will be confirmed by in vivo experiments on humanized mice infected with HIV and fed ethanol diet.