4th Annual BMRP Investigator Meeting - Abstract
NOD2/CARD15 Mutations and Apoptosis in Crohn's Disease
Helga-Paula Török1,a, Vanessa Beynon1, Jürgen Glas2, Kerstin Maier1, Andreas Koch1 and Christian Folwaczny1,b
1Chirurgische Klinik und Poliklinik – Innenstadt and 2Poliklinik fuer Zahnerhaltung und Parodontologie, Ludwig-Maximilians University (Munich, Germany)
The underlying pathogenetic mechanisms linking Crohn’s disease to mutations in NOD2 has not yet been entirely elucidated. Herein we studied the influence of NOD2 variants on the release of factors implied in inflammation and apoptosis like TNF-a, IL-10, IL-12 and IL-1b. To delineate a role of NOD2 in apoptosis, we investigated the effect of muramyl dipeptide (MDP) on apoptosis in peripheral blood mononuclear cells (PBMC), lamina propria mononuclear cells and primary epithelial cells. We further generated Flp-In T-REx HEK 293 cell lines stably transfected with wt-NOD2 and NOD2 variants. Our results are compatible with an impaired mRNA induction and protein release in monocytes with double-dose mutations in NOD2. Incubation of peripheral blood mononuclear cells in the presence of MDP resulted in significant increase of the cell percentage undergoing apoptosis. A similar effect was observed in isolated peripheral blood monocytes and in primary epithelial cells from intestinal biopsies short term cultured in presence of MDP. In contrast, L1007fs homozygote PBMCs did not show an increase of apoptosis. This effect also was not observed in isolated peripheral blood lymphocytes and lamina propria mononuclear cells, irrespective of the NOD2 genotype. Preliminary data in HEK 293 cells transfected with NOD2-variants also show an increase of apoptotic cells after NOD2 over-expression and stimulation with MDP. These observations are compatible with an implication of NOD2 in apoptosis. The detailed analysis of the respective apoptotic pathway and the influence of disease associated variants on these processes are under investigation. An impairment of apoptosis caused by NOD2 variants could represent an important pathogenetic link to the uncontrolled inflammation that characterise inflammatory bowel disease.
aCo-Investigator and Presenter; bPrincipal Investigator