Expression of several pro-inflammatory molecules such as IL-1β, IL-17a, Ccl-2, Cox-2, Cxcl-1, Cxcl-2 and IL-12 that promote colonic inflammation was significantly increased in colons of Ffar2−/− mice than WT mice after AOM/DSS treatment (Supplementary Figure 3). Here, CCL2 is linked to infectious otitis media.