Dietary fiber is a critical determinant of pathologic ILC2 responses and intestinal inflammation - Bulk RNA-Seq
Innate lymphoid cells (ILCs) can promote host defense, chronic inflammation or tissue protection and are regulated by cytokines and neuropeptides. However, their regulation by diet and microbiota-derived signals remains unclear. We show that an inulin fiber diet promotes Tph1-expressing inflammatory ILC2s (ILC2INFLAM) in the colon which produce IL-5 but not tissue-protective amphiregulin (AREG), resulting in accumulation of eosinophils. This exacerbates inflammation in a murine model of intestinal damage and inflammation in an ILC2- and eosinophil-dependent manner. Mechanistically, inulin fiber diet elevated microbiota-derived bile acids, including cholic acid (CA) that induced expression of ILC2-activating IL-33. In IBD patients, bile acids, their receptor farnesoid X receptor (FXR), IL-33, and eosinophils were all upregulated compared to controls, suggesting relevance of this diet-ILC2 axis in human IBD pathogenesis. Together, these data reveal that dietary fiber-induced changes in microbial metabolites operate as a rheostat that governs protective versus pathologic ILC2 responses with relevance to precision nutrition for inflammatory diseases. Overall design: Colonic biopsies from five non-IBD healthy controls and five pan-colitic IBD patients were digested into single cell suspensions and used to construct RNA-Seq libraries.