Microbiota maintain colonic homeostasis by activating TLR2/MyD88/PI3K signaling in IL-10–producing regulatory B cells
Yoshiyuki Mishima, … , Christopher L. Karp, R. Balfour Sartor
Yoshiyuki Mishima, … , Christopher L. Karp, R. Balfour Sartor
Published June 18, 2019
Citation Information: J Clin Invest. 2019;129(9):3702-3716. https://doi.org/10.1172/JCI93820.
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Research Article Gastroenterology Immunology

Microbiota maintain colonic homeostasis by activating TLR2/MyD88/PI3K signaling in IL-10–producing regulatory B cells

Abstract

Resident microbiota activates regulatory cells that modulate intestinal inflammation and promote and maintain intestinal homeostasis. IL-10 is a key mediator of immune regulatory function. Our studies describe the functional importance and mechanisms by which gut microbiota and specific microbial components influence the development of intestinal IL-10–producing B cells. Using fecal transplant into germ-free (GF) Il10+/EGFP reporter and Il10–/– mice, we demonstrated that microbiota from specific pathogen–free mice primarily stimulated IL-10–producing colon-specific B cells and T regulatory 1 cells in ex-GF mice. IL-10 in turn downregulated microbiota-activated mucosal inflammatory cytokines. TLR2 and -9 ligands and enteric bacterial lysates preferentially induced IL-10 production and the regulatory capacity of intestinal B cells. Analysis of Il10+/EGFP mice crossed with additional gene-deficient strains and B cell cotransfer studies demonstrated that microbiota-induced IL-10–producing intestinal B cells ameliorated chronic T cell–mediated colitis in a TLR2-, MyD88-, and PI3K-dependent fashion. In vitro studies implicated downstream signaling of PI3Kp110δ and AKT. These studies demonstrated that resident enteric bacteria activated intestinal IL-10–producing B cells through TLR2, MyD88, and PI3K pathways. These B cells reduced colonic T cell activation and maintained mucosal homeostasis in response to intestinal microbiota.

Authors

Yoshiyuki Mishima, Akihiko Oka, Bo Liu, Jeremy W. Herzog, Chang Soo Eun, Ting-Jia Fan, Emily Bulik-Sullivan, Ian M. Carroll, Jonathan J. Hansen, Liang Chen, Justin E. Wilson, Nancy C. Fisher, Jenny P.Y. Ting, Tomonori Nochi, Angela Wahl, J. Victor Garcia, Christopher L. Karp, R. Balfour Sartor

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Figure 6

Enteric resident bacteria in mice increase the capacity of intestinal B cells to suppress ex vivo bacterial lysate–stimulated inflammatory cytokine production that is mediated by IL-10 signaling.

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Enteric resident bacteria in mice increase the capacity of intestinal B ...
(A) Cytokine secretion by 10 μg/mL CBL-stimulated colonic LP B cells isolated from GF or SPF-raised WT mice in culture for 2 days. Cytokine concentrations were measured by ELISA. Data are presented as median of 6–7 separate cell cultures, with cells in each culture pooled from 3–4 mice. Mann-Whitney U test (GF vs. SPF). *P < 0.05, **P < 0.01, ***P < 0.001. (B) Colonic B cells from GF or SPF-reared WT mice were cultured with anti–IL-10R or isotype control antibodies in the presence or absence of 10 μg/mL CBL for 24 hours. Supernatant levels of IL-12p40 were measured by ELISA. Data are presented as median of 4 separate cell cultures, with cells in each culture pooled from 2–4 mice; *P < 0.05, Kruskal-Wallis test with Dunn’s post hoc test. (C) Cytokine secretion by MLN B cells from GF or SPF-raised WT mice cultured for 2 days with the indicated bacteria lysates or TLR ligands (see Figure 5 legend). IL-10 and IL-12p40 in culture supernatants were measured by ELISA. Data are presented as median of 4 separate cell cultures, with cells in each culture pooled from 3–6 mice. *P < 0.05, **P < 0.01, ***P < 0.001 (vs. no stimulation), Kruskal-Wallis test with Dunn’s post hoc test; #P < 0.05, ##P < 0.01 (GF vs. SPF), Mann-Whitney U test.