However, although these observations support the important role of TNF in enabling skin-specific interventions to exacerbate colitis, this inflammatory response was dependent on the presence of bacteria in the gut as skin wounds did not increase TNF in the colon of germ-free mice (Fig. 5c) and mortality rate, body weight loss, tissue histology, and infiltration of neutrophils and macrophages was rescued after treatment with vancomycin (Fig. 5d–h and Supplementary Fig. 9c–h). This evidence concerns the gene TNF and colitis.