A Short Time Rat Model of Mucosal Inflammation by in Situ Perfusion of an Intestinal Segment

Abstract

Background: The extent to which numerous strains of genetically engineered mice, including mice lacking toll-like receptor 5 (T5KO), display colitis that is environment-dependent with the gut microbiota underlying much of the variance in phenotype. Accordingly, embryonic rederivation of T5KO mice ameliorated their spontaneous colitis despite only partially correcting elevations in pro-inflammatory gene expression. We postulated that absence of overt inflammation in these mice required activation of endogenous anti-inflammatory pathways. Consequently, we hypothesized that neutralization of the anti-inflammatory cytokine IL-10 might induce uniform colitis in T5KO mice and thus provide a practical means to study mechanisms underlying their inflammation. Methods: Two distinct strains of noncolitic T5KO mice, mice lacking MyD88, TLR4 and IL-1R as well as various double-KO were treated weekly for 4 weeks with 1 mg/mouse of IL-10 receptor neutralizing antibody (IL-10R mAb) and colitis assayed 1 week after the final injection. Results: Anti-IL-10R mAb treatment led to severe uniform intestinal inflammation in both strains of T5KO mice. Such neutralization of IL-10 signaling did not cause colitis in WT littermate mice nor mice lacking TLR4, Myd88 or IL-1R. The susceptibility of T5KO mice to this colitis model was not rescued by absence of TLR4 in that TLR4/T5-DKO mice displayed severe colitis in response to anti-IL-10R mAb treatment. Finally, we observed that ablation of IL-1β signaling was crucial for this colitis model as IL-1R/TLR5-DKO were completely protected from colitis in response to IL-10RmAb treatment. Conclusion: Regardless of whether they harbor a “colitiogenic microbiota,” loss of TLR5 predisposes mice to colitis triggered by immune dysregulation via an IL-1β-dependant pathway.