Sex Hormone-Binding Globulin Prevents Carbon Tetrachloride-Induced Liver Fibrosis Development

Circulating sex hormone-binding globulin (SHBG) concentrations are lower in individuals with metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH), reflecting its potential role in metabolic liver dysfunction. Our prior studies demonstrated that SHBG can attenuate MASLD by limiting hepatic lipid deposition, partly through suppression of lipogenic pathways, in both cellular and animal models. In the present work, we have examined whether SHBG could protect against development of liver fibrosis. For this purpose, in vitro and in vivo studies were performed. In vitro, we used co-cultures of human hepatocellular carcinoma cell line (HepG2) and human hepatic stellate cell line (LX-2) cells transfected using an SHBG expression vector vs. vehicle and treated with transforming growth factor beta 1 (TGF-β1). For in vivo studies we used wild-type and human SHBG transgenic mice developing liver fibrosis induced by carbon tetrachloride (CCl₄). Our results clearly showed that SHBG overexpression reduced the TGF-β1-induced expression in collagen in LX-2 cells. Moreover, SHBG overexpression reduced the CCl₄ induced liver fibrosis in both male and female mice. Histological examination revealed that SHBG transgenic mice had reduced NAS score and decreased collagen accumulation, assessed by Sirious Red staining. In addition, human SHBG transgenic mice treated with CCl₄ exhibited lower collagen 1A1 (Col1A1) protein levels when compared with wild-type CCl₄ treated mice. Mechanistically, SHBG attenuated fibrosis primarily through modulation of the TGF-β1/matrix metalloproteinases (MMPs)/tissue inhibitor metalloproteinases 1 (TIMP1) axis, characterized by reduced TGF-β1 levels, increased metalloprotease activity, and decreased TIMP1 levels compared with wild-type CCl₄ treated mice. Notably, female SHBG transgenic mice exhibited greater protection against fibrosis than males, indicating a sex-dependent effect likely mediated by differences in sex steroid signaling. Taken together, we demonstrate for the first time that SHBG protects against liver fibrosis by promoting collagen degradation via the TGF-β1/MMPs/TIMP1 pathway. Further research is needed to elucidate the role of sex steroids in the regulation of MMPs and the observed sexual dimorphism.