SAT005 Effect Of OSU-ERβ-12, A Carborane-based ERβ-selective Agonist, On Hepatic Fibrosis And NASH

Abstract Disclosure: P. Kumar: None. T.H. Helms: None. H. Radomska: None. W. Tyler: None. S.K. Kulp: None. C. Bennett: None. C.C. Coss: None. Background: Non-alcoholic fatty liver disease (NAFLD) is a major cause of chronic liver disease worldwide. NAFLD includes a range of conditions from simple steatosis to non-alcoholic steatohepatitis (NASH), advanced fibrosis, and cirrhosis that can ultimately lead to liver failure and/or hepatocellular carcinoma (HCC). Hepatic stellate cells (HSCs) are essential to this pathologic fibrogenesis. In response to liver injury, they deposit collagen, fibronectin, and release the potent pro-fibrotic cytokine transforming growth factor-β (TGFβ). Estrogens have been shown to suppress the TGF-β-induced expression but the molecular mechanism is not completely understood. Estrogens are protective against multiple aspects of NAFLD/NASH pathophysiology. Their therapeutic potential however is limited by undesirable side effects attributed to ERα activation. Selective modulation of ERβ can provide therapeutic benefits of estrogens with reduced ERα-associated toxicities and has shown promising results in several preclinical NASH models. We hypothesize that beneficial estrogen pharmacology in NAFLD-NASH is driven by ERβ activation and ERβ-selective modulators can provide anti-NASH benefit. Our objective was to investigate the role of ERβ signaling and the therapeutic potential of the novel carborane ERβ-selective agonist, OSU-ERβ-12 (ERβ-12), in fibrosis and NASH models. Methods. Efficacy of ERβ-12 was tested in the CCl4 model of hepatic fibrosis by administering CCl4 to mice over 4 weeks at which point intervention with estradiol, LY500307 (LY) and ERβ-12 started. Combined treatment and CCL4 continued for 2 weeks when the CCl4 ceased, and therapy continued for 2 more weeks until sacrifice. We assessed fibrosis via algorithmic quantification of picrosirius red stain. Anti-fibrotic activity of ERβ-12 was assessed in vitro in a human HCC cell (HepG2)/human HSC (LX-2) co-culture system treated with ERβ-12, TGFβ or the combination for 24 h. Expression of pro-fibrotic, TGFβ pathway-related markers was assessed by qRT-PCR and western blotting in liver tissue and cell lysates. Results. ERβ-12 significantly reduced CCl4-induced liver fibrosis in mice at both non-selective (100 mg/kg) and ERβ-selective (10 mg/kg) doses. ERα-related toxicity (reduced urogenital weight) was not observed at the ERβ-selective dose. Reduced fibrosis was associated with decreased mRNA expression of pro-fibrotic and TGFβ pathway genes in livers of ERβ-12 treated mice. ERβ mRNA expression in HepG2/LX-2 co-culture cells was elevated compared to individual cell types. ERβ agonists (ERβ-12, LY) reduced TGFβ-mediated expression of pro-fibrotic genes: MCP-1, TGFβ, COL1A1. This effect was reversed with the pan-ER antagonist fulvestrant. Conclusion. These data suggest that ERβ agonism inhibits TGFβ-mediated liver fibrosis and supports further investigation of ERβ-targeted therapeutic candidates. Presentation: Saturday, June 17, 2023