CBLB502 administration protects gut mucosal tissue in ulcerative colitis by inhibiting inflammation

Background: Ulcerative colitis (UC) is a nonspecific inflammatory disease for which medications and therapeutic strategies have only been moderately successful. CBLB502, a toll-like receptor 5 (TLR5) agonist derived from Salmonella flagellin, exhibits anticancer and radioprotective activities via modulation of TLRs and the nuclear factor kappa B (NF-kappa B) signaling pathway and can protect against acute renal ischemic failure. In this study, we intend to examine the effects of CBLB502 on both TLR responses and the interleukin (IL) and NF-kappa B signaling pathways in UC treatment. Methods: The UC mouse model was prepared in BALB/c mice by administering 2,4,6-trinitrobenzene sulfonic acid (TNBS). CBLB502 was used as the therapeutic drug. After CBLB502 therapy, the IL and tumor necrosis factor-alpha (TNF-alpha) levels were measured by ELISA. Total RNA and protein of colon samples was extracted. Results: We found that CBLB502 had a distinctive therapeutic effect in the UC model. In control group animals, IL-10 expression in serum was 91.48 +/- 24.38 ng/mL; this was higher than in the model group (59.36 +/- 14.46 ng/mL, P<0.05) or the treatment group (54.29 +/- 5.83 ng/mL, P<0.05). In model group animals, the concentration of TNF-alpha in serum was 140.11 +/- 12.70 ng/mL, which was lower than protein levels in the control group (173.86 +/- 29.26 ng/mL, P<0.05). The mRNA levels of TLR1, 2, 3, 4, 6, 7, 8, and 9 in the CBLB502 treatment group were significantly lower than in the model group (P<0.05). Western blot revealed that CBLB502 also reduced NF-kappa B expression in the mouse colon, but that NF-kappa B expression was not significantly lower than the model group. Conclusions: CBLB502 can reduce mucosal damage induced by TNBS and inhibit inflammation and TLR expression. The inhibition of UC by CBLB502 is strictly TLR-IL-dependent and is dose-dependent within the efficacious dose range. Therefore, our results suggested that CBLB502 might be a candidate drug for the treatment of UC.