TNF and irritable bowel syndrome: Some patients with IBS had been found with low-grade inflammation, more likely those to suffer diarrhea-predominant IBS (IBS-D) or post-infectious IBS (PI-IBS), than other IBS subtypes24 as observed by increased lamina propria immune cells in the colonic mucosa25,26, as well as increased levels of pro-inflammatory cytokines including IL-1β, TNF-α, IL-6 and IL-8, and reduced levels of anti-inflammatory cytokines such as IL-1027.