Tu1457 POTENTIAL ROLE OF TCR??+ INTRAEPITHELIAL LYMPHOCYTES IN CELIAC DISEASE.

Background and Aim. Although the expansion of TCR?D+ intraepithelial lymphocytes(IELs) is a hallmark of Celiac Disease (CD), to date little is known about the mechanismunderlying their expansion and their role in CD pathogenesis. Different evidence pointstoward an immunoregulatory role for?D+ IEL. We have shown that IL-15, highly expressedin CD intestinal mucosa, impairs the functions of Foxp3+ Treg cells. Different approacheshave been used to study the pattern of cytokines produced by?D+ IELs in CD, which haveled sometimes to contradictory results. It is essential to analyse specific cell types to identifyand define biologically important processes in CD pathogenesis. The development in thelast decade of laser capture microdissection (LCM) has allowed this goal to be achieved.The aim of this study was to investigate the regulatory function of TCR?D+ IELs, isolatedby LCM, and to understand if their role could be impaired by IL-15.Methods.Frozensection of jejunum was obtained from 10 untreated CD patients. Using LCM in combinationwith immunohistochemistry, the?D+ IELs and intestinal epithelial cells were isolated andtotal RNA was extracted. The relative expression of TGF-?, IL-10 and IL-15 was evaluatedby quantitative reverse transcriptase real-time PCR (qRT-PCR).Results were expressed asthe ratio of each cytokine cDNA concentration relative to the concentration of the GAPDHhousekeeping gene cDNA in the same sample. Statistical analyses were performed inGraphPad Prism and data were reported as normalized mean expression ± standard error. Results. An increased gene expression level of TGF-?and IL-10 (p<0.05) was observed in?D+ IELs from untreated CD patients compared to the intestinal epithelial cells which,otherwise, have been characterized by an increased gene expression level of IL-15 (p<0.05).Conclusion.In the epithelium compartment of untreated CD jejunal mucosa we found thatenterocytes and?D+ T cells produce respectively IL-15 and anti-inflammatory cytokinesTGF-?and IL-10. Taken toghether our results suggest that in CD the?D+ IELs have regulatoryfunction, which is not affected by IL-15, produced by enterocytes.