TNF and irritable bowel syndrome: Several clinical studies have found elevated levels of pro-inflammatory cytokines (such as IL-1α, IL-1β, IL-6, IL-8, IL-17, TNF-α, CXCL-11 and CXCR-3)and reduced levels of the anti-inflammatory cytokine IL-10 in patients with IBS (22, 24, 29–31, 59–62).