P047 Enterocytes and dendritic cells both contribute to the intestinal inflammation in paediatric inflammatory bowel diseases
C. Strisciuglio*1, S. Vitale2, L. Pisapia3, E. Miele4, P. Barba3, A. Vitale1, S. Cenni4, G. Del Pozzo3, R. Troncone4, A. Staiano4, C. Gianfrani2
1Second University of Naples, Department of Woman, Child and General and Specialised Surgery, Naples, Italy, 2Institute of Protein Biochemistry, CNR, Naples, Italy, 3Institute of Genetics and Biophysics Adriano Buzzati Traverso, CNR, Naples, Italy, 4University Federico II, Department of Translational Medical Science, Section of Paediatrics, Naples, Italy
The contribution of both adaptive and innate immune response to the development and maintenance of mucosal lesions in inflammatory bowel diseases (IBD) has been extensively dissected. Recent evidence has underlined the role of enterocytes as non-immune inflammatory cells in the pathogenesis of IBD. However, very little is known about the cellular and cytokine inflammatory pathways occurring in very young subjects with IBD.
Through an ex-vivo analysis, we investigated the cytokine production profile and phenotype of enterocytes, dendritic cells, and T lymphocytes in uninflamed colonic biopsies of children with Crohn’s disease (CD), ulcerative colitis (UC), and non-IBD controls (HC). The different cell populations were monitored in freshly isolated intestinal cells by specific surface cell markers, as EpCam, CD11c, and CD3, respectively, for enterocytes, dendritic cells and T lymphocytes, as well as for HLA Class I and II molecule expression. The production of pro-inflammatory cytokines (IL-15, TNF-α, and INF-γ), was evaluated in intestinal colonic mucosa in the steady state condition, or after a brief in-vitro cell stimulation with mitogens, by multicolour flow cytometry and ELISA.
In biopsies from paediatric IBD we observed a higher frequency of IL-15 producing cells. Further, in IBD mucosal explants we found an enhanced densities of EpCam+ enterocytes expressing IL-15, and of CD11c+ dendritic cells producing TNF-α compared with healthy mucosa. Interestingly, increased densities of enterocytes were detected in biopsies from UC patients, whereas no differences were observed in CD11c+ dendritic cell or CD3+ lymphocyte infiltrates amongst IBD and healthy intestinal mucosa. Further, in UC a more prominent infiltration of intestinal cells expressing HLA Class I molecules, and of CD11c+ DCs producing IFN-γ was detected. IFN-γ was found markedly secreted by IBD intestinal cells after a mitogen stimulation.
Our study demonstrates a pro-inflammatory phenotype of both epithelial and dendritic cells in the intestinal mucosa of paediatric subjects with IBD. A pathogenic function of IL-15 in addition to TNF-α is also reported, thus suggesting IL-15 as a potential therapeutic target in paediatric IBD.