Nuclear factor erythroid 2-related factor 2 ameliorates disordered glucose and lipid metabolism in liver: Involvement of gasdermin D in regulating pyroptosis.

BACKGROUND: The epidemic of metabolic dysfunction-associated fatty liver disease linked to excessive high-fat diet (HFD) consumption has sparked widespread public concern. Nuclear factor erythroid 2-related factor 2 (NRF2) has been reported to improve glucose/lipid metabolism, liver lipid degeneration and alleviate HFD-induced inflammation. However, its pathways and mechanisms of action are not fully understood. METHODS: To confirm the effect of NRF2 on glucose/lipid metabolism in the liver, Nrf2-/- mice as well as liver-specific Nrf2 knockout mice, and AAV-TBG-Nrf2 were employed. The hyperinsulinemic-euglycemic clamp was utilized to determine the effect of NRF2 on glucose metabolism. To elucidate the effect of NRF2 on pyroptosis, we performed western blots, immunofluorescence, quantitative real-time PCR, and Flow cytometry experiments. Finally, chromatin immunoprecipitation-seq and dual-luciferase reporter assay was used to underscore the transcriptional regulatory effect of NRF2 on Gsdmd. RESULTS: We found that overexpression of Nrf2 inhibited the expression of inflammatory cytokines and pyroptosis markers, including cle-Caspase1, NLRP3 and the N-terminus of gasdermin D (N-GSDMD) both in vivo and in vitro, while Nrf2 deficiency was the opposite. Specifically, with NRF2 expression up-regulated, GSDMD expression decreased and Gsdmd overexpression partially reversed the effect of Nrf2 overexpression on pro-inflammatory phenotype. Mechanistically, we demonstrate that NRF2 binds to the Gsdmd promoter at the -2110 - 1130 bp site, inhibiting the GSDMD expression and thereby improving glucose/lipid metabolism and liver steatosis. CONCLUSION: Our data indicate that NRF2 is an effective inhibitor of pyroptosis and has a multi-target effect in the treatment of obesity-related metabolic diseases. KEY POINTS: MAFLD is associated with increased hepatocytes NRF2 expression. NRF2 alleviates MAFLD by suppressing pyroptosis. NRF2 directly inhibits GSDMD expression to regulate pyroptosis. Targeting the NRF2-pyroptosis (GSDMD) axis offers a potential therapeutic strategy for MAFLD.