Gut
dysbiosis, host genetics, and environmental triggers are implicated as causative factors in
inflammatory bowel disease (IBD), yet mechanistic insights are lacking. Longitudinal analysis of
ulcerative colitis (UC) patients following total
colectomy with ileal anal anastomosis (IPAA) where >50% develop
pouchitis offers a unique setting to examine cause vs. effect. To recapitulate human IPAA, we employed a mouse model of surgically created blind self-filling (SFL) and self-emptying (SEL) ileal loops using wild-type (WT),
IL-10 knockout (KO) (IL-10), TLR4 KO (T4), and IL-10/T4 double KO mice. After 5 wk, loop histology, host gene/
protein expression, and bacterial
16s rRNA profiles were examined. SFL exhibit fecal stasis due to directional motility oriented toward the loop end, whereas SEL remain empty. In WT mice, SFL, but not SEL, develop pouchlike microbial communities without accompanying active
inflammation. However, in genetically susceptible IL-10-deficient mice, SFL, but not SEL, exhibit severe
inflammation and mucosal transcriptomes resembling human
pouchitis. The
inflammation associated with
IL-10 required TLR4, as animals lacking both pathways displayed
little disease. Furthermore, germ-free
IL-10 mice conventionalized with SFL, but not SEL, microbiota populations develop severe
colitis. These data support essential roles of stasis-induced, colon-like microbiota, TLR4-mediated colonic
metaplasia, and
genetic susceptibility in the development of
pouchitis and possibly UC. However, these factors by themselves are not sufficient. Similarities between this model and human UC/
pouchitis provide opportunities for gaining insights into the mechanistic basis of IBD and for identification of targets for novel preventative and therapeutic interventions.