Nod2 in Normal and Abnormal Intestinal Immune Function Maria T. Abreu  Gastroenterology  Volume 129, Issue 4, Pages 1302-1304 (October 2005) DOI: 10.1053/j.gastro.2005.08.028 Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 1 Crohn’s disease patients carrying Nod2 mutations typically have ileal disease. Nod2 is expressed by Paneth cells at the base of the small intestinal crypts. Deficient expression of Nod2 results in decreased Paneth cells expression of cryptdin which may lead to increased bacterial colonization in the crypts. It is also possible that dendritic cells and macrophages in the lamina propria express Nod2. Stimulation of macrophages carrying CD-associated mutations in Nod2 demonstrate increased expression of IL-beta and IL6. Dendritic cells in the lamina propia sample luminal bacteria and express IL-23, a Th1 differentiating cytokine. In the setting of Nod2 mutations, inappropriate sensing of muramyl dipeptide from luminal bacteria may result in elevated expression of IL-23. Together these cytokines may initiate or perpetuate chronic inflammation in the ileum of Crohn’s disease patients. Illustration by Jerry Schoendorf, MAMS. Gastroenterology 2005 129, 1302-1304DOI: (10.1053/j.gastro.2005.08.028) Copyright © 2005 American Gastroenterological Association Terms and Conditions