Intestinal NLRP3 Deficiency Exacerbates MASLD in Male Mice via Reduced Butyrate Production

Objectives: Metabolic dysfunction-associated steatotic liver disease (MASLD) represents a major global health burden, yet its underlying mechanisms remain incompletely defined. We aimed to investigate the role of intestinal NOD-, LRR-, and pyrin-domain-containing protein 3 (NLRP3) inflammasome in the gut-liver axis to identify potential therapeutic targets for MASLD.

Methods: Eight-week-old male mice were given a methionine-choline-deficient (MCD) diet for 4 weeks to induce MASLD-associated fibrosis. The functional role of NLRP3 was assessed using Vil1^creNLRP3^f/f mice with intestinal epithelial cell-specific NLRP3 deletion. To evaluate the potential influence of the gut microbiota, Vil1^creNLRP3^f/f-MCD mice were co-housed with NLRP3^f/f-MCD counterparts. The effect of butyrate was also evaluated in Vil1^creNLRP3^f/f-MCD mice via oral gavage for 3 weeks. The role of intestinal NLRP3 was further validated in a carbon tetrachloride (CCl₄)-induced liver fibrosis model.

Results: Intestinal NLRP3 expression was markedly reduced in wild-type mice given MCD diet. Compared with NLRP3^f/f-MCD mice, Vil1^creNLRP3^f/f-MCD mice developed more severe MASLD and exhibited impaired intestinal barrier integrity, whereas the co-housing condition alleviated hepatic pathology. Moreover, butyrate administration significantly improved hepatic steatosis and fibrosis in Vil1^creNLRP3^f/f-MCD mice. Mechanistic analysis revealed attenuated hepatic Peroxisome Proliferator-activated Receptor α (PPARα) activation and enhanced hepatic activator protein (AP)-1 signaling in Vil1^creNLRP3^f/f-MCD mice, both of which improved under co-housing condition or butyrate treatment. Similarly, intestinal NLRP3 deletion aggravated CCl₄-induced liver fibrosis.

Conclusion: Loss of intestinal NLRP3 diminished butyrate production, inhibited PPARα expression, and enhanced AP-1 signaling, collectively intensifying MASLD progression.