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P092. Detection of apoptosis in intestinal mucosa and mesenteric fat tissue of Crohn's disease

C.B. Dias1, L.R. Meirelles2, M. Milanski3, M.L.S. Ayrizono4, A. Coope3, M. Portovedo3, N. Planell5, C.S.R. Coy4, L.A. Velloso3, R.F. Leal1, 1University of Campinas, Colorectal Surgery Unit, Surgery Department. Cell Signalization Laboratory, Internal Medicine Department, Campinas, Brazil, 2University of Campinas, Pathology Department, Campinas, Brazil, 3University of Campinas, Cell Signalization Laboratory, Internal Medicine Department, Campinas, Brazil, 4University of Campinas, Colorectal Surgery Unit, Surgery Department, Campinas, Brazil, 5CIBER-EHD, Department of Gastroenterology and Bioinformatics Platform, Barcelona, Spain

Background

CD is associated with the expression of many genes and with complex pathways involving defect in apoptosis mechanisms. Recently, the role of mesenteric fat has been associated with CD etiopathology, since fat hypertrophy is detected near the affected intestinal area.

Methods

Evaluate apoptosis in intestinal mucosa and mesenteric fat in CD. Ten patients with ileocecal CD (CD Group), eight with non-inflammatory diseases (mesenteric fat tissue control group) selected for surgery, and eight with normal ileocolonoscopy (intestinal mucosa control group) were studied. The expression of Bax (pro-apoptotic protein) and Bcl-2 (anti-apoptotic protein) was determined by immunoblot, RT-PCR and immunochemistry. Intestinal mucosa and mesenteric fat tissue were compared with the respective controls, using non-parametric tests (p < 0.05). The local ethical committee approved the study.

Results

Transcriptional expression of Bax was significantly decreased in intestinal mucosa of CD compared to controls; although the protein expression was similar among the groups. Immunochemistry of intestinal tissue showed low number of positive cells for Bax, in both epithelium and immune cells of the lamina propria, in CD group, which was in agreement to gene expression. Protein, gene expression and immunochemistry for Bax were similar when comparing the mesenteric fat groups. The intestinal mucosa of the CD group had significantly higher protein levels and low gene expression of Bcl-2 compared to controls. Immunochemistry also showed more positive immune cells for Bcl-2 in the lamina propria of CD group. The mesenteric fat of CD had lower Bcl-2 gene expression than the control and the protein levels were similar. However, immunochemistry showed significantly higher expression of Bcl-2 in mesenteric fat of CD group when compared to control.

Conclusion

Patients with CD had significantly higher expression of Bcl-2 in intestinal tissue (immune cells of the lamina propria) and in mesenteric fat tissue, detected by immunochemistry. Conversely, Bax protein and gene expression was significantly lower in intestinal tissue of CD, seen by immunochemistry and RT-PCR. Our results strongly suggest that, immune cells and epithelium present a defective apoptosis in intestinal mucosa and also in the hypertrophied mesenteric fat of CD, thus potentially allowing longer time for them to produce pro-inflammatory cytokines. These findings may explain the maintenance of intestinal inflammation in CD patients.

Financial Support: FAPESP.