Inhibiting VEGFC - mediated hepatocyte - macrophage regulatory axis contributes to protective effects of naringin against high - fat diet - induced hepatic fibrosis.

BACKGROUND

Naringin (NAR) has shown anti-fibrotic effects. This study found it alleviates non-alcoholic steatohepatitis (NASH)-associated liver fibrosis and downregulates vascular endothelial growth factor C (VEGFC). However, the pathophysiological role of VEGFC in NASH and its contribution to NAR's protection remain unclear.

OBJECTIVE

To determine whether and how the downregulation of VEGFC contributes to the protective effect of NAR against NASH-associated hepatic fibrosis.

METHODS

A mouse model of NASH fibrosis was induced by a 24-week high-fat diet (HFD). Mice were treated concomitantly with NAR-L (25 mg/kg/day), NAR-H (50 mg/kg/day), or SAR131675 (SAR, 30 mg/kg/day) from week 9 to 24 (16 weeks). Clinical serum VEGFC levels were measured in a hospital cohort (n = 165); human hepatic VEGFC expression was analyzed in using data from Gene Expression Omnibus (GEO) datasets (GSE162694, GSE130970). Hepatocyte-specific Vegfc knockout mice (VegfcHep‑cKO) were generated by crossing Vegfcflox/flox with Alb-CreERT2 (Albumin-CreERT2) mice. In vitro, AML12 hepatocytes were pretreated (oleic acid, recombinant VEGFC, or Vegfc genetic modulation); these cells or their conditioned medium were used to stimulate bone marrow-derived macrophages to assess macrophage migration and phenotypic switching.

RESULTS

NAR and SAR131675 ameliorated liver inflammation and fibrosis in mice, downregulated VEGFC and CCL2/CCR2, reduced Ly6Chigh monocyte infiltration, and promoted Ly6Chigh-to-Ly6Clow macrophage phenotypic switch. Clinical data showed elevated VEGFC in NAFLD and NASH patients. VegfcHep‑cKO mice exhibited similar therapeutic effects. In vitro, hepatocyte-derived VEGFC promoted macrophage migration via VEGFR3 and CCL2/CCR2; inhibited phenotypic transition via regulating IL-10 or CX3CR1. NAR disrupted this axis by suppressing VEGFC in hepatocytes.

CONCLUSION

Hepatocyte-derived VEGFC is a key contributor to NASH-related liver fibrosis, functioning by regulating macrophage migration and phenotypic switch. The hepatoprotective effect of NAR is partially mediated through the inhibition of the VEGFC-mediated hepatocyte-macrophage regulatory axis.