Identifying species of symbiont bacteria from the human gut that, alone, can induce intestinal Th17 cells in mice

Abstract

Th17 cells accrue in the intestine in response to particular microbes. In rodents, segmented filamentous bacteria (SFB) induce intestinal Th17 cells, but analogously functioning microbes in humans remain undefined. Here, we identified human symbiont bacterial species, in particularBifidobacterium adolescentis, that could, alone, induce Th17 cells in the murine intestine. Similar to SFB,B. adolescentiswas closely associated with the gut epithelium and engendered cognate Th17 cells without attendant inflammation. However,B. adolescentiselicited a transcriptional program clearly distinct from that of SFB, suggesting an alternative mechanism of promoting Th17 cell accumulation. Inoculation of mice withB. adolescentisexacerbated autoimmune arthritis in the K/BxN mouse model. Several off-the-shelf probiotic preparations that includeBifidobacteriumstrains also drove intestinal Th17 cell accumulation.