TNF and inflammatory bowel disease: With IBD, the impaired ability of Pattern Recognition Receptors (PRRs), such as Toll-like receptors (TLRs), on epithelial and immune cells in the intestine to differentiate between pathogenic and commensal bacteria leads to prolonged activation of nuclear factor-κB, a pro-inflammatory transcription factor which triggers overproduction of inflammatory cytokines, such as tumor necrosis factor (TNF) and IL-1β [21].