Background This study aimed to investigate the roles and mechanisms of tenofovir alafenamide fumarate (TAF)/tenofovir disoproxil fumarate (TDF) in treating liver fibrosis. Methods The effects of TAF/TDF on carbon tetrachloride (CCl 4 )-induced liver fibrosis in C57BL/6 wild-type or nonstructural protein 5A transactivated protein 9 (NS5ATP9) knockout mice were studied. The differentiation, activation, and proliferation of LX-2 cells after TAF/TDF treatment were tested in vitro. The expression of NS5ATP9 and activities of transforming growth factor-β1 (TGFβ1)/Sekelsky mothers against decapentaplegic homolog 3 (Smad3) and NF-κB/NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome signaling pathways were detected in TAF/TDF-treated mice and LX-2 cells. The genes related to extracellular matrix accumulation were detected in vivo and in vitro after NS5ATP9 silencing or knockout. Results TAF/TDF significantly inhibited CCl 4 -induced liver fibrosis in mice, and regulated the differentiation, activation, and proliferation of hepatic stellate cells (HSCs). Furthermore, TAF/TDF suppressed the activities of TGFβ1/Smad3 and NF-κB/NLRP3 inflammasome signaling pathways in vivo and in vitro. NS5ATP9 inhibited liver fibrosis through TGFβ1/Smad3 and NF-κB signaling pathways. TAF/TDF upregulated the expression of NS5ATP9 in vivo and in vitro. Finally, TAF/TDF could only show marginal therapeutic effects when NS5ATP9 was silenced and knocked out in vivo and in vitro. Conclusions TAF/TDF prevented progression and promoted reversion of liver fibrosis through assembling TGFβ1/Smad3 and NF-κB/NLRP3 inflammasome signaling pathways via upregulating the expression of NS5ATP9. TAF/TDF also regulated the differentiation, activation, and proliferation of HSCs. The findings provided strong evidence for the role of TAF/TDF as a new promising therapeutic strategy in liver fibrosis.
Hepatic stellate cells (HSCs) are the central link of the occurrence and development of hepatic fibrosis, and autophagy promotes HSCs activation. N6-methyladenosine (m6A) RNA modification can also control autophagy by targeting selected autophagy-associated genes. but up to now, little research has been done on the m6A modification autophagy-related genes (ATGs) in hepatic fibrosis. Here, we identify ATG9A as a previously unrecognized m6A modified ATG using m6A-sequencing (m6A-seq). Importantly, ATG9A is upregulated in liver fibrosis mice and primary biliary cirrhosis (PBC) patient liver tissue. Mechanistically, based on the presence of m6A binding sites on ATG9A, ATG9A promotes HSCs autophagy in an m6A dependent manner, thereby enhancing HSCs activation. Noteworthy, FTO is identified as the upstream of ATG9A, and knockdown of ATG9A can prevent FTO-induced HSCs autophagy and activation. In bile duct ligation (BDL) or CCL4-induced liver fibrosis mouse models, lowering ATG9A alleviated liver fibrosis through PI3K/AKT/mTOR pathway and TGFβ1/smad3 pathway. Taken together, our results provided that ATG9A is a potential prognostic biomarker and therapeutic target for patients with liver fibrosis.