METTL3 inhibition ameliorates liver damage in mouse with hepatitis B virus-associated acute-on-chronic liver failure by regulating miR-146a-5p maturation.

Hepatitis B virus (HBV)-associated acute-on-chronic liver failure (ACLF) is a clinical syndrome of severe liver damage. HBV infection is affected by N6-methyladenosine (mA) RNA modification. Here, we investigated whether methyltransferase-like 3 (METTL3)-mediated mA methylation can affect ACLF. Human hepatic cells (THLE-2) were treated with lipopolysaccharide (LPS) to induce cell damage. Proliferation, apoptosis and mA modification were measured by MTT assay, flow cytometry and Dot blot assay. Our results showed that HBV infection significantly enhanced the levels of mA modification and elevated the expression of METTL3 and mature-miR-146a-5p in THLE-2 cells, which was repressed by cycloleucine (mA inhibitor). METTL3 overexpression enhanced mA modification and promoted mature-miR-146a-5p expression. METTL3 overexpression promoted HBV replication and apoptosis, enhanced the levels of pro-inflammatory cytokines, hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg), and repressed cell proliferation in THLE-2 cells, which attributed to repress miR-146a-5p maturation. Moreover, a severe liver failure mouse model was established by HBV infection to verify the impact of METTL3 knockdown on liver damage in vivo. HBV-infection led to a severe liver damage and increase of apoptosis in hepatic tissues of mice, which was abolished by METTL3 knockdown. METTL3 knockdown reduced METTL3 expression and impeded miR-146a-5p maturation in HBV-infected mice. In conclusion, this work demonstrates that METTL3 inhibition ameliorates liver damage in mouse with HBV-associated ACLF, which contributes to repress miR-146a-5p maturation. Thus, this article suggests a novel therapeutic avenue to prevent and treat HBV-associated ACLF.