FFAR2 and gout: Injection of monosodium urate monohydrate (MSU) crystals caused joint inflammation, hypernociception, and production of IL-1β and CXCL1, which were substantially decreased in germ-free mice, mice treated with antibiotics, and free fatty acid receptor 2 (FFAR2 or GPR43)–deficient mice, suggesting commensal microbiota play a critical role in gout-induced acute inflammation and pain [71].