TNF and colitis: In melanoma patients who developed colitis there was an overexpression of mucosal IL1β and IL-17, but not TNF. These fascinating results were corroborated by results in experimental models in which mice, gavaged with different strains of B. intestinalis following gut sterilization with antibiotics, showed overexpression of Il1b. Moreover, fecal microbiota transplant (FMT) in antibiotic-treated animals using fecal material from human donors harboring high endogenous levels of B. intestinalis induced ileal overexpression of Il1b after administration of CICB.