A Novel Urease-Negative Helicobacter Species Associated with Colitis and Typhlitis in IL-10-Deficient Mice

A spiral-shaped bacterium with bipolar, single-sheathed flagella was isolated from the intestines of IL-10 (interleukin-10)-deficient (IL-10(−/−)) mice with inflammatory bowel disease. The organism was microaerobic, grew at 37 and 42°C, and was oxidase and catalase positive but urease negative. On the basis of 16S rRNA gene sequence analysis and biochemical and phenotypic criteria, the organism is classified as a novel helicobacter. Cesarean section-rederived IL-10(−/−) mice without helicobacter infection did not have histological evidence of intestinal inflammation. However, helicobacter-free IL-10(−/−), SCID/NCr, and A/JNCr mice experimentally inoculated with the novel urease-negative Helicobacter sp. developed variable degrees of inflammation in the lower intestine, and in immunocompetent mice, the experimental infection was accompanied by a corresponding elevated immunoglobulin G antibody response to the novel Helicobacter sp. antigen. These data support other recent studies which demonstrate that multiple Helicobacter spp. in both naturally and experimentally infected mice can induce inflammatory bowel disease. The mouse model of helicobacter-associated intestinal inflammation should prove valuable in understanding how specific microbial antigens influence a complex disease process.