Dual Modulation of Senescence and Immune Checkpoints by Metformin and Dapagliflozin Attenuates Liver Fibrosis in a Thioacetamide-Induced Rat Model

Abstract

Purpose Liver fibrosis, characterized by excessive extracellular matrix accumulation, reflects a maladaptive repair response to persistent hepatic injury. Recent studies implicate cellular senescence and immune checkpoint dysregulation as pivotal drivers of fibrogenesis, yet these pathways remain underutilized in therapeutic development. This study evaluates the anti-fibrotic efficacy of metformin and dapagliflozin, two metabolic modulators, in a thioacetamide (TAA)-induced rat model, emphasizing their impact on senescence and immune regulation. Methods Male albino rats (N=6/group) were assigned to five groups: control, TAA (200 mg/kg, i.p., thrice weekly for 4 weeks), TAA + metformin (300 mg/kg/day), TAA + dapagliflozin (1 mg/kg/day), and TAA + combination therapy. Liver tissues underwent histopathological examination and SMAD-3 mRNA quantification via qRT-PCR. Protein levels of TGF-β1, PD-1, p16, NF-κB, α-SMA, fibronectin, collagen-I, and sirtuin-1 were assessed, alongside serum oxidative stress markers (MDA, SOD) and liver enzymes (ALT, AST). Results All treatments significantly reduced fibrosis, collagen deposition and improved liver architecture. Mechanistically, both drugs suppressed fibrotic and senescence markers, downregulated PD-1, enhanced sirtuin-1, and mitigated oxidative stress. Notably, combination therapy yielded synergistic anti-fibrotic effects. Conclusions These findings highlight a dual-pathway therapeutic strategy targeting senescence and immune imbalance, with relevance to metabolic liver disease.

Keywords: Liver fibrosis, metformin, dapagliflozin, senescence, PD-L1