In vivo treatment with NO-prednisolone (NCX-1015) potently stimulates IL-10 production, suggesting that the NO steroid induces a regulatory subset of T cells that negatively modulates intestinal inflammation. The two doses of NO-prednisolone tested, 0.5 and 5 mg/kg/day (equivalent to 0.33 and 3.3 mg/kg/day prednisone, respectively) effectively attenuates the severity of the wasting syndrome, ameliorates the colitis score, and reduces the colonic myeloperoxidase (MPO) activity. NO-prednisolone administration also reduces the colonic mRNA and protein content of tumor necrosis factor-α, IL-12, and IFN-γ. NO-prednisolone also reduces the expression of inducible NO synthase and cyclooxygenase-2 but in contrast does not inhibit colonic expression of IL-10 mRNA or protein. In fact, IL-10 expression is enhanced in mice treated with NO-prednisolone.