TNF and Crohn ileitis: In a study by Schaubeck et al. [47], mice lacking tumor necrosis factor (TNF) that binds to adenosine-uridine-rich elements (ARE) (TNFdeltaARE mice), a CD-like ileitis mouse model, were housed under either conventional (CONV), specific pathogen-free (SPF) or germ-free (GF) conditions.