Puerarin from Pueraria montana var. lobata (Willd.) alleviates hepatic steatosis and inflammation in MAFLD through suppressing STING-IRF3/NF-κB signaling in macrophages

Ethnopharmacological relevance: Metabolic-associated fatty liver disease (MAFLD) has emerged as the most prevalent chronic liver disease globally. Accumulating evidence indicates that aberrant activation of the stimulator of interferon genes (STING) signaling pathway in hepatic macrophages plays a pivotal role in driving hepatic inflammation and steatosis. Puerarin, a bioactive isoflavone derived from Pueraria montana var. lobata (Willd.), has been reported to exert anti-inflammatory and lipid-lowering effects. However, the detailed mechanism of its actions in treating MAFLD remains to be fully explored.

Aim of the study: To investigate whether puerarin ameliorates MAFLD by suppressing the STING-IRF3/NF-κB signaling in hepatic macrophages.

Materials and methods: We explored the effects and underlying mechanisms of puerarin using three models: a high-fat diet (HFD)-induced MAFLD mouse model, an in vitro lipotoxicity model employing bone marrow-derived macrophages (BMDMs) stimulated with palmitic acid (PA) and oleic acid (OA), and a hepatocyte co-culture model using AML12 and HepG2 cells incubated with BMDM-conditioned media. Histological and biochemical assessments included hematoxylin and eosin (H&E) staining, Oil Red O staining, immunohistochemistry and immunofluorescence. Gene and protein expression levels were evaluated by real-time quantitative PCR (RT-PCR) and Western blotting. STING-specific agonists were applied to confirm the involvement of the STING-IRF3/NF-κB signaling pathway.

Results: Puerarin markedly attenuated liver fat accumulation, oxidative stress, and inflammation induced by a high-fat diet in mice. These effects were associated with a marked reduction in STING-positive hepatic macrophages, accompanied by significant downregulation of STING mRNA expression and suppression of the STING-IRF3/NF-κB signaling. Consistently, puerarin suppressed the expression of STING mRNA and protein in BMDMs stimulated with palmitic acid and oleic acid, thereby directly attenuating STING pathway activation and dose-dependently decreasing the release of pro-inflammatory cytokines TNF-α and IFN-β. Furthermore, conditioned media from puerarin-treated BMDMs significantly alleviated lipid accumulation and the expression of genes related to fat production in AML12 and HepG2 cells. Moreover, puerarin effectively antagonized STING activation induced by the specific agonist DMXAA.

Conclusion: Puerarin alleviates hepatic inflammation and lipid accumulation in MAFLD by targeting the STING-IRF3/NF-κB signaling pathway in macrophages. This study elucidates the immunometabolic mechanism of puerarin across multiple cellular contexts and provides preclinical support for its potential role as a therapy for MAFLD.

Inflammation; MAFLD; Macrophages; Puerarin; STING.