SUMOylation inhibitors synergize with FXR agonists in combating liver fibrosis

Area of Science:

• Hepatology
• Molecular Biology
• Pharmacology

Background:

• Farnesoid X receptor (FXR) is a therapeutic target for nonalcoholic steatohepatitis (NASH) and liver fibrosis.
• Clinical efficacy of FXR agonists has been limited, necessitating novel therapeutic strategies.

Purpose of the Study:

• To investigate the efficacy of obeticholic acid (OCA) in preventing and treating liver fibrosis.
• To explore the role of FXR SUMOylation in regulating HSC activation and response to FXR agonists.
• To evaluate the potential of combining OCA with SUMOylation inhibitors for liver fibrosis treatment.

Main Methods:

• Administration of OCA prophylactically and therapeutically in preclinical models.
• Assessment of hepatic stellate cell (HSC) activation and fibrogenesis.
• Investigation of FXR SUMOylation status and its impact on FXR signaling.
• Co-administration of OCA with SUMOylation inhibitors in various liver injury models (CCl4, bile duct ligation, NASH).

Main Results:

• Prophylactic OCA administration prevented HSC activation and fibrogenesis, but therapeutic use was less effective.
• Activated HSCs exhibited resistance to OCA due to enhanced FXR SUMOylation.
• SUMOylation inhibitors restored FXR signaling, enhancing OCA's efficacy against HSC activation and fibrosis.
• Combined OCA and SUMOylation inhibitor therapy significantly reduced liver fibrosis in multiple models, including NASH.

Conclusions:

• FXR SUMOylation limits the therapeutic efficacy of FXR agonists in liver fibrosis.
• Combining SUMOylation inhibitors with FXR agonists like OCA represents a promising therapeutic strategy for liver fibrosis and NASH.