A synthetic mimetic of CD4 is able to suppress disease in a rodent model of immune colitis

CD4⁺ mucosal T cells mediate the intestinal inflammation in Crohn's disease and may serve as an important target for immune intervention. Here we assessed the therapeutic effect of a synthetic mimetic of CD4 designed to mimic both the sequence and conformation of the complementarity-determining region 3 of murine CD4 V1 domain (rD-mPGPtide) in a mouse colitis model using immunization with 2,4,6-trinitrobenzene sulfonic acid (TNB). i. v. administration of the rD-mPGPtide but not control scrambled peptide could suppress severe inflammation in the chronic colitis mouse model. After treatment with the rD-mPGPtide, a striking improvement of diarrhea and acute wasting disease was observed with decreased mortality. Serum anti-TNB antibody titers, CD45RB^lowCD4⁺ T cells in the lamina propria and IFN-γ mRNA expression in the mucosa were significantly decreased with the rD-mPGPtide treatment. Anti-CD4 antibody also suppressed disease by depletion of CD45RB^highCD4⁺ T cells in the colonic mucosa. The observation that the synthetically engineered analogue of murine CD4 inhibits inflammation in a rodent disease model by different mechanisms than anti-CD4 antibody suggests that a human version of this peptide has potential therapeutic utility in CD4⁺ mucosal T cell-mediated intestinal inflammation in Crohn's disease.