The Inhibitory Innate Immune Sensor NLRP12 Maintains a Threshold against Obesity by Regulating Gut Microbiota Homeostasis

In addition to high-fat diet (HFD) and inactivity, inflammation and microbiota composition contribute to obesity. Inhibitory immune receptors, such as NLRP12, dampen inflammation and are important for resolving inflammation, but their role in obesity is unknown. We show that obesity in humans correlates with reduced expression of adipose tissue NLRP12. Similarly, Nlrp12 ^−/− mice show increased weight gain, adipose deposition, blood glucose, NF-κB/MAPK activation, and M1-macrophage polarization. Additionally, NLRP12 is required to mitigate HFD-induced inflammasome activation. Co-housing with wild-type animals, antibiotic treatment, or germ-free condition was sufficient to restrain inflammation, obesity, and insulin tolerance in Nlrp12 ^−/− mice, implicating the microbiota. HFD-fed Nlrp12 ^−/− mice display dysbiosis marked by increased obesity-associated Erysipelotrichaceae, but reduced Lachnospiraceae family and the associated enzymes required for short-chain fatty acid (SCFA) synthesis. Lachnospiraceae or SCFA administration attenuates obesity, inflammation, and dysbiosis. These findings reveal that Nlrp12 reduces HFD-induced obesity by maintaining beneficial microbiota. Truax et al. show that myeloid-expressed NLRP12 restrains high-fat-diet-induced obesity and type 2 diabetes by attenuating TNF, IL-6, NF-kB, MAPK, M1-macrophage polarization, and inflammasome activation in adipose tissue. This protective function of NLRP12 is microbiota dependent, and is associated with Lachnospiraceae and their metabolites, which mitigate obesity.