Disruption of Pten speeds onset and increases severity of spontaneous colitis in Il10-/- mice

Abstract

Background & Aims Early-onset ulcerative colitis, which is considered severe colonic inflammation that develops in infants and young children, can be caused by alterations in interleukin (IL)-10 signaling, although other factors are involved in its pathogenesis. We investigated whether loss of phosphatase and tensin homologue (PTEN), which regulates many important cell functions such as cell proliferation, cell survival, and Toll-like receptor (TLR) signaling pathways, contributes to the development of colitis in Il10-/- mice. Methods We generated Il10-/- mice (in C57BL/6 and C3H/HeJBir background strains) with disruption of Pten in the intestinal epithelium (IntsΔPten/ΔPten;Il10-/- mice) and Ints ΔCont;Il10-/- (control) mice. Colon tissues were collected and histological, transmission electron microscopy, and gene expression analysis were performed. Fecal microbiota samples were analyzed by sequencing of 16S ribosomal RNA genes. We disrupted Tlr4 in Ints ΔPten/ΔPten;Il10-/- mice. Lipopolysaccharide signaling via TLR4 was blocked by treating mice with polymyxin B. Results Il10-/- mice developed colitis when they were 6 to 7 months old, whereas IntsΔPten/ΔPten;Il10-/- mice developed severe colitis and colon tumors by the time they were 36 days old. Within 3 months of birth, 80% of IntsΔPten/ΔPten;Il10 -/- mice developed severe colitis and colonic malignancy, whereas none of the IntsΔCont;Il10-/- mice had these phenotypes. IntsΔPten/ΔPten;Il10-/- mice had alterations in fecal microbiota compared with controls, such as increased proportions of Bacteroides species, which are gram negative. Disruption of Tlr4 or treating IntsΔPten/ΔPten;Il10-/- mice with polymyxin B delayed the development of colitis and reduced disease severity. Conclusions Disruption of Pten in the intestinal epithelium of Il10 -/- mice speeds the onset and increases the severity of colitis. Fecal microbiota from IntsΔPten/ΔPten;Il10-/- mice have increased proportions of Bacteroides species. Development of colitis is delayed and reduced by blocking TLR4 signaling. Ints ΔPten/ΔPten;Il10-/- mice may be studied as a model for early-onset ulcerative colitis and used to identify new therapeutic targets. © 2014 by the AGA Institute.