Ectopic colonization of oral bacteria in the intestine drives T<sub>H</sub>1 cell induction and inflammation.

Atarashi, Koji; Suda, Wataru; Luo, Chengwei; Kawaguchi, Takaaki; Motoo, Iori; Narushima, Seiko; Kiguchi, Yuya; Yasuma, Keiko et al. · Science · 2017

basic_science · Level V

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Abstract

Intestinal colonization by bacteria of oral origin has been correlated with several negative health outcomes, including inflammatory bowel disease. However, a causal role of oral bacteria ectopically colonizing the intestine remains unclear. Using gnotobiotic techniques, we show that strains of <i>Klebsiella</i> spp. isolated from the salivary microbiota are strong inducers of T helper 1 (T<sub>H</sub>1) cells when they colonize in the gut. These <i>Klebsiella</i> strains are resistant to multiple antibiotics, tend to colonize when the intestinal microbiota is dysbiotic, and elicit a severe gut inflammation in the context of a genetically susceptible host. Our findings suggest that the oral cavity may serve as a reservoir for potential intestinal pathobionts that can exacerbate intestinal disease.

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