Cytomegalovirus Infection Exacerbates Experimental Colitis by Promoting IL-23 Production

Many studies have demonstrated an association between cytomegalovirus (CMV) infection and inflammatory bowel disease (IBD). Moreover, CMV infection is more common in patients with severe or steroid-refractory IBD. However, it is not clarified whether CMV worsens IBD or if it is merely a surrogate marker for IBD. Here, we used the dextran sodium sulfate (DSS)-induced colitis model to investigate if CMV infection exacerbates colitis. The mice were injected intraperitoneally with 10 MOI of murine CMV (MCMV) and thereafter, chronic colitis was induced by one cycle of DSS exposure. Anti-IL-23R mAb at 20 μg/mice and pyrrolidine dithiocarbamate (PDTC), an effective NF-κB inhibitor, at 50 mg/kg were administrated to the mice. The MCMV-infected mice had a shorter colon length and a higher histopathology score than the mock inoculum-treated mice, while anti-IL-23R mAb administration ameliorated the pathological changes. Expression of IL-23, phospho-NF-κB p65, and phospho-IκBα was upregulated in colon tissues of the MCMV-infected mice compared to mock inoculum-treated mice, while treatment with PDTC attenuated colonic IL-23 production. These data demonstrated that CMV infection could accelerate IBD development. This effect may be due to its activation on NF-κB signaling pathway and subsequently IL-23 production.