AAV8-mediated silencing of Atad3 prevents the progression from simple steatosis to MASH in mice by reduced IL6 secretion

Abstract

ATAD3A deficiency in hepatocytes has been shown to promote simple steatosis (SS). ATAD3 is upregulated in MCD diet-induced MASH. Since the MCD diet is commonly used to induce liver fibrosis, which is related to HSCs activation, we are prompted to investigate the functions of ATAD3 in these two cell types and their mediated transition from SS to MASH. To investigate the role of ATAD3A in HSCs, human LX-2 cells were treated with TGFβ. The results showed that ATAD3A expression was linked to the fibrotic markers ACTA2 and COL1A1. Knockdown of ATAD3A reversed TGFβ-induced HSC activation by downregulating both canonical (SMAD2/3) and non-canonical (ERK1/2 and p38 MAPK) TGFβ signaling pathways. To examine the effect of ATAD3 on the transition from SS to MASH, MASH was induced in mice using the GAN diet for 24 weeks. After 12 weeks, AAV8-conjugated Atad3 shRNA was administered to knock down Atad3 in the liver. This intervention suppressed steatosis and fibrosis while enhancing insulin sensitivity. Further analysis using conditioned medium (CM) from WT and ATAD3A KO Huh7 cells treated with LPS and PA revealed that IL-6 secretion from Huh7 hepatocytes activated HSCs. However, IL-6 secretion was diminished in ATAD3A KO CM. CM from ATAD3A KO cells also suppressed expression of fibrotic markers ACTA2, PP38, and P-SMAD3 compared to WT cells under MASH conditions. These data suggest that AAV8-mediated Atad3 silencing in hepatocytes prevents the transition from SS to MASH, at least in part, by downregulating IL-6 secretion to suppress HSC activation in MASH.

Keywords: AAV8; GAN diet; Lipopolysaccharide; Mitochondria; TGFβ; White adipose tissue.