Hepatic stellate cell inhibition by angiotensin II receptor blocker mitigates liver injury and fibrosis via NF-κB-galectin-3 suppression in a rat nonalcoholic steatohepatitis model.

Nonalcoholic steatohepatitis (NASH), associated with metabolic syndromes, causes fibrosis and cirrhosis, leading to hepatocellular carcinoma. Angiotensin II (ANG II) type 1 receptor (AT1R), expressed in hepatic stellate cells (HSCs), promotes cell proliferation and collagen production. Our study aimed to investigate the potential inhibitory effect and mechanism of the AT1R blocker (ARB) on NASH with fibrosis and carcinogenesis using a transgenic rat NASH model, focusing on the direct modulatory effect of ARB on the rat HSC cell line, RI-T. Connexin 32 dominant-negative transgenic rats fed a high-fat diet (HFD) or HFD with ARB (candesartan, 1 or 2 mg/kg/day) in drinking water and injected with dimethylnitrosamine 6 times for 18 weeks. In vivo, ARB improved liver injury, steatohepatitis, and bridging fibrosis by decreasing α-smooth muscle actin (α-SMA) positive activated HSCs, reducing ROS production, and alleviating insulin resistance. ARB decreased inflammatory cytokine mRNA expression (Timp1, Timp2, Ctgf, Tgf-β1), inhibited NF-κB signaling, and notably reduced galectin-3 protein expression, a critical fibrosis mediator regulated by the TGF-β/NF-κB pathway. ARB reduced the Ki-67 labeling index in hepatic preneoplastic glutathione S-transferase placental form positive foci. In vitro, ARB decreased pPKD1 and pPKCδ protein expression, upstream regulators of the NF-κB pathway in HSC activated by TGF-β1 or ANG II. Additionally, galectin-3-stimulated HSC proliferation, activity, and NF-κB signaling were suppressed by ARB. In conclusion, our study demonstrated that ARB alleviates NASH progression and fibrosis by inhibiting HSC activation via suppression of PKC/PKD-NF-κB signaling and galectin-3. Furthermore, we identified a novel mechanistic correlation between ARB and galectin-3, expanding the therapeutic potential of ARBs in NASH.