Innate PI3K p110? regulates Th1/Th17 development and microbiota-dependent colitis.

ABSTRACT: The p110? subunit of class IA PI3K modulates signaling in innate immune cells. We previously demonstrated that mice harboring a kinase-dead p110? subunit (p110?(KD)) develop spontaneous colitis. Macrophages contributed to the Th1/Th17 cytokine bias in p110?(KD) mice through increased IL-12 and IL-23 expression. In this study, we show that the enteric microbiota is required for colitis development in germfree p110?(KD) mice. Colonic tissue and macrophages from p110?(KD) mice produce significantly less IL-10 compared with wild-type mice. p110?(KD) APCs cocultured with naive CD4+ Ag-specific T cells also produce significantly less IL-10 and induce more IFN-?- and IL-17A-producing CD4+ T cells compared with wild-type APCs. Illustrating the importance of APC-T cell interactions in colitis pathogenesis in vivo, Rag1(-/-)/p110?(KD) mice develop mild colonic inflammation and produced more colonic IL-12p40 compared with Rag1(-/-) mice. However, CD4+ CD45RB(high/low) T cell Rag1(-/-)/p110?(KD) recipient mice develop severe colitis with increased percentages of IFN-?- and IL-17A-producing lamina propria CD3+D4+ T cells compared with Rag1(-/-) recipient mice. Intestinal tissue samples from patients with Crohn's disease reveal significantly lower expression of PIK3CD compared with intestinal samples from non-inflammatory bowel disease control subjects (p < 0.05). PIK3CD expression inversely correlates with the ratio of IL12B:IL10 expression. In conclusion, the PI3K subunit p110? controls homeostatic APC-T cell interactions by altering the balance between IL-10 and IL-12/23. Defects in p110? expression and/or function may underlie the pathogenesis of human inflammatory bowel disease and lead to new therapeutic strategies.

SUBMITTER: Steinbach EC 

PROVIDER: S-EPMC3992276 | biostudies-literature | 2014 Apr

REPOSITORIES: biostudies-literature