Human FGF1^ΔHBS Gene Therapy as Treatment for Metabolic Dysfunction-Associated Steatohepatitis in ApoE-KO Mice

The prevalence of metabolic dysfunction-associated steatohepatitis (MASH) is rising worldwide. hFGF1^ΔHBS, a variant of human fibroblast growth factor 1 with three substitutions in its heparin-binding sites, was previously shown by our group to ameliorate fatty liver. However, hFGF1^ΔHBS also significantly modulates systemic metabolism, making it unclear whether its hepatic benefits arise from direct liver-specific actions. Additionally, its poor pharmacokinetic profile underscores the need for alternative delivery strategies. Here, we employed adeno-associated virus serotype 8 under the thyroxine-binding globulin promoter (AAV8-TBG) to achieve sustained, hepatocyte-specific expression of hFGF1^ΔHBS. In high-fat-, high-cholesterol-diet-fed apolipoprotein E knockout mice, liver-directed hFGF1^ΔHBS expression markedly reduced hepatic steatosis, inflammation, and fibrosis, independent of changes in body weight, blood glucose, insulin sensitivity, body composition, or circulating triglyceride and cholesterol levels. Mechanistically, hFGF1^ΔHBS gene transfer normalized fatty acid synthesis and suppressed fatty acid uptake by downregulation of stearoyl-CoA desaturase-1 and cluster of differentiation 36. Importantly, these therapeutic effects were achieved without inducing hepatic hyperproliferation, as evidenced by unchanged expression of proliferating cell nuclear antigen and antigen Kiel 67. Collectively, our findings demonstrate that hFGF1^ΔHBS exerts direct hepatoprotective effects and that AAV8-TBG-mediated liver-directed hFGF1^ΔHBS delivery represents a safe and effective strategy for treating MASH.