MPO and colitis: While systemic and topical DPP-4 inhibitors reduce colitis severity and promote healing of colitis (Mimura et al., 2013; Salaga et al., 2017), Dpp4 KO does not protect from colitis (Geier et al., 2005) but increases colonic myeloperoxidase activity and nuclear factor κbp65 subunit and modifies leucocyte trafficking (Detel et al., 2012).