IL10 and colitis: In addition, the implication of the microbiota on the pathogenesis of colitis in IL-10 deficient mice is supported by solid evidences such as the fact that inflammation is more severe in mice kept under conventional housing conditions, in comparison to animals maintained under specific pathogen-free and germ-free conditions (Berg et al., 1996; Sellon et al., 1998; Spencer et al., 2002).