In line with our previous findings, colorectal DCA instillation caused much more severe inflammation and injury than DSS treatment alone (Figures 4(a)–4(f)), whereas inhibition of cathepsin B potently decreased the colonic mature IL-1β level and significantly restrained the aggravating role of DCA in the DSS-induced colitis, as evidenced by much less body weight loss and colon length shortening as well as lower MPO activity and hematochezia score compared to the DCA enema group (Figures 4(a)–4(f)). Here, MPO is linked to colitis.