Bacterial suppression of intestinal fungi via activation of human gut γδ T-cells

Gut symbionts condition mucosal immunity to resist infection by enteropathogens, but the specific microbes and mechanisms involved differ significantly between host species. In higher primates, bacterial metabolite HMB-PP is sensed by a specialized population of Vγ9Vδ2+T-cells, which we now report can potently suppress growth of endogenous fungi in human intestinal organ cultures. In healthy intestine, HMB-PP-stimulated Vδ2+T-cells restricted outgrowth of keystone fungus Candida albicans via a mechanism that required IL-22. In contrast, Crohn’s disease (CD) patients with reduced Vδ2+T-cell numbers displayed outgrowth of C. albicans strains that readily formed toxin-producing filaments, triggered neutrophil extracellular traps, and induced macrophage IL-1β release ex vivo . Genomic and proteomic analysis of the Candida isolates suggested increased tissue adhesion of CD-derived strains, which rapidly invaded the gut barrier in an ‘intestine-on-a-chip’ model. These data reveal that bacterial activation of Vδ2+T-cells suppresses fungal pathobionts in human gut via an IL-22-dependent mechanism that is dysregulated in CD.