In fact, exogenous CO suppresses TNBS-induced colitis through inhibition of TNF-α production.(24) Similarly, the beneficial effects of CO and HO-1 induction were also demonstrated in the models of chronic Th1-mediated colitis in IL-10-deficient mice(25) and Th2-mediated colitis in TCRα-deficient mice.(26). Here, IL10 is linked to colitis.