Naringin affects VEGFC/TGF-β1 to mediate intercellular communication in MASH through coordinated Src and p38 MAPK pathways

Metabolic dysfunction-associated steatohepatitis (MASH) fibrosis is driven by dysregulated intercellular communication. While our prior work identified hepatocyte-derived vascular endothelial growth factor C (VEGFC) as the key driver recruiting pro-fibrotic Ly6C^high monocytes (defining the "Who") and by dictating their functional positioning (defining the "Where") in fibrotic foci, the intracellular signaling mechanism ("How") translating this recruitment into fibrogenic output remained unknown. This study elucidates this mechanism and its therapeutic targeting by naringin (NAR). In HFD-induced MASH mice and Vegfc^△hep genetic models, both NAR and the vascular endothelial growth factor receptor-3 (VEGFR3) inhibitor SAR131675 attenuated hepatic steatosis, inflammation, and fibrosis, concomitant with reduced hepatic VEGFC expression and improved liver-to-body weight ratios. Mechanistically, VEGFC activation of macrophage VEGFR3 triggers Src/p38 MAPK signaling pathway, driving transforming growth factor-β (TGF-β1) production and inducing a pathological hybrid polarization-distinct from classical M1-type macrophages (M1)/ M2-type macrophages (M2) classification-characterized by concurrent nitric oxide synthase 2 (Nos2) and TGF-β1 upregulation, Arginase 1 (Arg1) suppression, and unchanged macrophage Mannose Receptor 1 (Cd206) in both RAW264.7 cells and primary bone marrow-derived macrophages. This macrophage-derived TGF-β1 critically mediates hepatic stellate cells (HSCs) activation. These findings define the complete "Who/Where/How" pathogenic relay in MASH fibrosis and establish the VEGFC-VEGFR3-Src/p38 MAPK-TGF-β1 axis as the pharmacological target of NAR.