Innate immune responses are crucial for host defense against pathogens, but need to be tightly regulated to prevent chronic inflammation. Initial characterization of mice with a targeted inactivating mutation in the p110d subunit of phosphoinositide 3-kinase (PI3K p110δD910A/D910A) reveal defects in B- and T-cell signaling and chronic colitis. Here, we further characterize features of inflammatory bowel diseases (IBD) in these mice and investigate underlying innate immune defects

Kobayashi, Taku

Li, Fengling

Matsuoka, Katsuyoshi

Plevy, Scott E.

Rao, Kavitha N.

Sartor, R. Balfour

Sepulveda, Antonia R.

Sheikh, Shehzad Z.

Steinbach, Erin C.

Uno, Jennifer K.

Vanhaesebroeck, Bart

PubMed

Carolina Digital Repository

Altered Macrophage Function Contributes to Colitis in Mice Defective in the Phosphoinositide-3 Kinase Subunit p110δ

Background & Aims: Innate immune responses are crucial for host defense against pathogens but need to be tightly regulated to prevent chronic inflammation. Initial characterization of mice with a targeted inactivating mutation in the p110δ subunit of phosphoinositide 3-kinase (PI3K p110δD910A/D910A) revealed defects in B- and T-cell signaling and chronic colitis. Here, we further characterize features of inflammatory bowel diseases in these mice and investigate underlying innate immune defects. Methods Colons and macrophages from PI3K p110δD910A/D910A mice were evaluated for colonic inflammation and innate immune dysfunction. Colonic p110δ messenger RNA expression was examined in interleukin (IL)-10 -/- and wild-type germ-free mice during transition to a conventional microbiota. To assess polygenic impact on development of colitis, p110δD910A/D910A mice were backcrossed to IL-10-/- mice. Results A mild spontaneous colitis was shown in PI3K p110δ D910A/D910A mice at 8 weeks, with inflammation increasing with age. An inflammatory mucosal and systemic cytokine profile was characterized by expression of IL-12/23. In PI3K p110δD910A/D910A macrophages, augmented toll-like receptor signaling and defective bactericidal activity were observed. Consistent with an important homeostatic role for PI3K p110δ, wild-type mice raised in a germ-free environment markedly up-regulated colonic PI3K p110δ expression with the introduction of the enteric microbiota; however, colitis-prone IL-10-/- mice did not. Moreover, PI3K p110δD910A/D910A mice crossed to IL-10-/- mice developed severe colitis at an early age. Conclusions This study describes a novel model of experimental colitis that highlights the importance of PI3K p110δ in maintaining mucosal homeostasis and could provide insight into the pathogenesis of human inflammatory bowel disease. © 2010 by the AGA Institute

George Washington University: Health Sciences Research Commons (HSRC)

Altered macrophage function contributes to colitis in mice defective in the phosphoinositide-3 kinase subunit p110δ

https://cdr.lib.unc.edu/downloads/h415ph39b

Altered Macrophage Function Contributes to Colitis in Mice Defective in the Phosphoinositide-3 Kinase Subunit p110δ

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George Washington University: Health Sciences Research Commons (HSRC)