SP stimulates the synthesis of TNF-α, IL-1β, and IL-6 in the human colonic mucosa [64], increases the production of IL-1β and IL-6 mRNA in human glial cells, and co-operates with mast cells in the wall of ileum and ascending colon of irritable bowel syndrome (IBS) patients [65,66]. This evidence concerns the gene IL1B and irritable bowel syndrome.