Interference with mitochondrial function as part of the antifibrogenic effect of Rilpivirine: A step towards novel targets in hepatic stellate cell activation

Abstract

Activated hepatic stellate cells (aHSCs), the main perpetrators of liver fibrosis, are a promising therapeutic target in the treatment of chronic liver disease. During liver injury, HSCs transcend from a quiescent to a fibrotic phenotype, a process which involves major metabolic reprogramming with altered mitochondrial function. The antiretroviral drug Rilpivirine (RPV) has demonstrated a hepatoprotective and specifically antifibrotic effect in several animal models of chronic liver injury, as well as in vitro. Herein, we use HSCs activated with the profibrogenic cytokine TGF-β to explore whether mitochondrial function is implicated in this effect. The mitochondrial bioenergetic profile, morphology and dynamics of TGF-β-treated cells (48 h) were altered and these effects were prevented by co-treatment with clinically relevant concentrations of RPV. A MitoStress Test (Seahorse Analyzer) revealed that TGF-β increased both oxygen consumption rate (basal respiration, maximal respiration and spare respiratory capacity) and extracellular acidification rate (indicative of increased glycolysis). Cells exposed to TGF-β also displayed diminished mitochondrial membrane potential and enhanced mitochondrial fission. All of these effects were rescued with RPV. RNA sequencing analysis of cells exposed to TGF-β revealed the presence of 338 differentially expressed genes that encode mitochondrial proteins (mito-DEGs), of which 139 and 199 were significantly up- and down-regulated (adjusted p<0.05). This alteration in 15 (10.79 %) and 31 (22.03 %) of the up-regulated and 16 (8.04 %) and 49 (24.62 %) of the down-regulated mitoDEGs was prevented with co-exposure to RPV 4μM or 8μM, respectively. In conclusion, alterations in mitochondrial function are implicated in the antifibrogenic action of RPV, pointing to potential novel antifibrotic targets.