Indeed, stimulation of unfractioned lamina propria mononuclear cells (LPMC) isolated from normal colonic samples with TNF, a cytokine over-produced in both CD and UC (4), increased IL-34 production while blockade of TNF with a neutralizing TNF antibody in IBD LPMC cultures and ex vivo mucosal explants taken from IBD patients reduced IL-34 synthesis. This evidence concerns the gene TNF and inflammatory bowel disease.