Aflatoxin B1-exposed hepatocyte-derived extracellular vesicles: Initiating hepatic stellate cell-mediated liver fibrosis through a p53-Parkin-dependent mitophagy pathway

Abstract

Environmental aflatoxin B₁ (AFB₁) exposure has been proposed to contribute to hepatocellular carcinoma by promoting liver fibrosis, but the potential mechanisms remain to be further elucidated. Extracellular vesicles (EVs) were recognized as crucial traffickers for hepatic intercellular communication and play a vital role in the pathological process of liver fibrosis. The AFB₁-exposed hepatocyte-derived EVs (AFB₁-EVs) were extracted, and the functional effects of AFB₁-EVs on the activation of hepatic stellate cells (HSCs) were explored to investigate the molecular mechanism of AFB₁ exposure-induced liver fibrogenesis. Our results revealed that an environment-level AFB₁ exposure induced liver fibrosis via HSCs activation in mice, while the AFB₁-EVs mediated hepatotoxicity and liver fibrogenesis in vitro and in vivo. AFB₁ exposure in vitro increased PINK1/Parkin-dependent mitophagy in hepatocytes, where upregulated transcription of the PARK2 gene via p53 nuclear translocation and mitochondrial recruitment of Parkin, and promoted AFB₁-EVs-mediated mitochondria-trafficking communication between hepatocytes and HSCs. The knockdown of Parkin in HepaRG cells reversed HSCs activation by blocking the mitophagy-related AFB₁-EVs trafficking. This study further revealed that the hepatic fibrogenesis of AFB₁ exposure was rescued by genetic intervention with siPARK2 or p53's Pifithrin-α (PFTα) inhibitors. Furthermore, AFB₁-EVs-induced HSCs activation was relieved by GW4869 pharmaceutic inhibition of EVs secretion. These results revealed a novel mechanism that AFB₁ exposure-induced p53-Parkin signal axis regulated mitophagy-dependent hepatocyte-derived EVs to mediate the mitochondria-trafficking intercellular communication between hepatocytes and HSCs in the local hepatotoxic microenvironment to promote the activated HSCs-associated liver fibrogenesis. Our study provided insight into p53-Parkin-dependent pathway regulation and promised an advanced strategy targeting intervention to EVs-mediated mitochondria trafficking for preventing xenobiotics-induced liver fibrosis.

Keywords: Aflatoxin B(1); Extracellular vesicles; Intercellular communications; Liver fibrogenesis; Mitochondria trafficking; p53-Parkin-dependent mitophagy.