NOD2 and ulcerative colitis: Inflammatory bowel diseases (IBDs), comprising Crohn's Disease (CD) and Ulcerative Colitis (UC), are characterized by chronic idiopathic intestinal inflammation, resulting from predisposing genetic (genes encoding proteins relevant to both innate and adaptive immunity: NOD2, STAT3, and IL-23 receptor, etc.)and environmental factors (specific Toll-like receptors (TLRs) ligands and antigens derived from commensal bacteria) acting on immunoregulatory system.