ARG1 and colitis: Reactivation of quiescent colitis was associated with a significant increase in an M2 macrophage marker [Arginase 1 (Arg1)], but not Chitinase-like 3 (Ym1) expression (Figures 4C,D), and hCTS treatment (1.5 mg/kg/day, 7 days, i.r).