Gut microbiota-derived indole-3 acetic acid mitigates key hallmarks of metabolic dysfunction-associated steatotic liver disease (MASLD) in an NLRP3-dependent manner in in vitro and diet-induced mouse models

Background Metabolic-dysfunction associated steatotic liver disease(MASLD) is a global epidemic affecting >30 % global population with no approved therapies till date. Recent reports suggest that activation of NLRP3 inflammasome may be involved in the pathogenesis of MASLD. We, therefore, aimed to identify small molecule inhibitor(s) of NLRP3 inflammasome as a potential therapeutic strategy to manage MASLD and validate their efficacy using in vitro and in vivo models of MASLD. Methodology We screened an in-house library of natural products using an in vitro phenotypic assay and identified a gut microbiota derived metabolite of dietary Tryptophan; indole-3 acetic acid (I3A) for its ability to inhibit the levels of IL-1β and IL-18, which are elevated as a result of activation of NLRP3 inflammasome in differentiated THP1 cells. Subsequently, we carried out several in vitro and in vivo studies to confirm the mechanism of action of I3A and its ability to mitigate the key hallmarks of MASLD Results Our in vitro data suggest that I3A is an inhibitor of NLRP3 inflammasome. I3A was also found to improve the blood glucose level, plasma lipid profile, hepatic fat, and liver function in high-fat-high-fructose diet induced model of MASLD using C57BL/6 mice. Conclusion Our results show that I3A, which has been previously reported to be a gut microbiota-derived metabolite of dietary tryptophan, mitigates the key hallmarks of MASLD in an NLRP3 dependent manner. A dedicated structure-activity-relationship (SAR) study around the I3A chemotype may be carried out in future to identify novel NLRP3 inhibitors with desirable pharmacological profile.