Metformin is not only the first-line medication for the treatment of type 2 diabetes, but it is also effective as an anti-inflammatory, anti-oxidative and anti-tumor agent. However, the effect of metformin during viral hepatitis remains elusive. Using an adenovirus (Ad)-induced viral hepatitis mouse model, we found that metformin treatment significantly attenuated liver injury, with reduced serum aspartate transaminase (AST) and alanine transaminase (ALT) levels and liver histological changes, presumably via decreased effector T cell responses. We then demonstrated that metformin reduced mTORC1 activity in T cells from infected mice, as evidenced by decreased phosphorylation of ribosome protein S6 (p-S6). The inhibitory effects on the mTORC1 signaling by metformin was dependent on the tuberous sclerosis complex 1 (TSC1). Mechanistically, metformin treatment modulated the phosphorylation of dynamin-related protein 1 (Drp-1) and mitochondrial fission 1 protein (FIS1), resulting in increased mass in effector T cells. Moreover, metformin treatment promoted mitochondrial superoxide production, which can inhibit excessive T cell activation in viral hepatitis. Together, our results revealed a protective role and therapeutic potential of metformin against liver injury in acute viral hepatitis via modulating effector T cell activation via regulating the mTORC1 pathway and mitochondrial functions.

Background: Whether metformin is related to nonalcoholic fatty liver disease (NAFLD) is controversial. Our aim was to investigate the relationship between metformin and NAFLD that may predict the metformin potential of these lesions and new prevention strategies in NAFLD patients.Methods: The meta-analysis was analyzed by Revman 5.3 softwares systematically searched for works published through July 29, 2022. Network pharmacology research based on databases, Cytoscape 3.7.1 software and R software respectively. Results:The following variables were associated with metformin in NAFLD patients: decreased of alanine aminotransferase (ALT) level (mean difference [MD] = −10.84, 95% confidence interval [CI] = −21.85 to 0.16, P = .05); decreased of aspartate amino transferase (AST) level (MD = −4.82, 95% CI = −9.33 to −0.30, P = .04); decreased of triglyceride (TG) level (MD = −0.17, 95% CI = −0.26 to −0.08, P = .0002); decreased of total cholesterol (TC) level (MD = −0.29, 95% CI = −0.47 to −0.10, P = .003); decreased of insulin resistance (IR) level (MD = −0.42, 95% CI = −0.82 to −0.02, P = .04). In addition, body mass index (BMI) (MD = −0.65, 95% CI = −1.46 to 0.16, P = .12) had no association with metformin in NAFLD patients. 181 metformin targets and 868 NAFLD disease targets were interaction analyzed, 15 core targets of metformin for the treatment of NAFLD were obtained. The effect of metformin on NAFLD mainly related to cytoplasm and protein binding, NAFLD, hepatitis B, pathway in cancer, toll like receptor signaling pathway and type 2 diabetes mellitus (T2DM). The proteins of hypoxia inducible factor-1 (HIF1A), nuclear factor erythroid 2-related factor (NFE2L2), nitric oxide synthase 3 (NOS3), nuclear receptor subfamily 3 group C member 1 (NR3C1), PI3K catalytic subunit alpha (PIK3CA), and silencing information regulator 2 related enzyme 1 (SIRT1) may the core targets of metformin for the treatment of NAFLD. Conclusion:Metformin might be a candidate drug for the treatment of NAFLD which exhibits therapeutic effect on NAFLD patients associated with ALT, AST, TG, TC and IR while was not correlated with BMI. HIF1A, NFE2L2, NOS3, NR3C1, PIK3CA, and SIRT1 might be core targets of metformin for the treatment of NAFLD.Abbreviations: ALT = alanine aminotransferase, AST = aspartate amino transferase, BMI = body mass index, CI = confidence interval, HCC = hepatocellular carcinoma, HIF1A = hypoxia inducible factor-1, HOMA-IR = insulin resistance index, IR = insulin resistance, MCC = maximal clique centrality, MD = mean difference, NAFLD = nonalcoholic fatty liver disease, NAFL = nonalcoholic fatty liver, NASH = nonalcoholic steatohepatitis, NFE2L2 = nuclear factor erythroid 2-related factor, NOS = Newcastle-Ottawa quality assessment scale, NOS3 = nitric oxide synthase 3, NR3C1 = nuclear receptor subfamily 3 group C member 1, OR = odds ratio, PIK3CA = PI3K catalytic subunit alpha, PPI = protein protein interaction, SIRT1 = silencing information regulator 2 related enzyme 1, T2DM = type 2 diabetes mellitus, TC = total choleste...