IL13 and colitis: Owing to Oxa-induced colitis being mediated by type 2 immunity, the effect of melatonin on the secretion of type 2 inflammatory cytokines was assessed, and melatonin treatment markedly suppressed the production of IL-5 and IL-13 in the colon of the MT50 group (Figures 3A, B and Supplementary Figure 2A).