Two wheat decapeptides prevent gliadin-dependent maturation of human dendritic cells

Celiac disease (CD) is a small intestinal enteropathy, triggered in susceptible individuals by the ingestion of dietary gluten. Dendritic cells (DC) are instrumental in the generation and regulation of immune responses and oversee intestinal immune homeostasis promoting and maintaining oral tolerance to food antigens. The aim of this study was to monitor the effect of peptic-tryptic digest of gliadin (PT-gliadin) on the maturation of human monocyte-derived DC and the impact of pDAV and pRPQ decapeptides in the modulation of PT-gliadin-induced phenotypic and functional DC maturation. Immature DC (iDC) were challenged in vitro with PT-gliadin. In some experiments iDC were pre-treated with pDAV or pRPQ and after 2h PT-gliadin was added to the cultures. We found that PT-gliadin up-regulates the expression of the maturation markers HLA-DR, CD83, CD80 and CD86. The functional consequence of PT-gliadin treatment of iDC is a significant increase in IL-12, TNF-alpha production as well as in their T cell stimulatory capacity. On the contrary, the digest of zein had no effect on DC maturation. Interestingly, we found that pre-treatment of iDC with pDAV or pRPQ decapeptides significantly prevents the functional maturation of DC induced by PT-gliadin. On the other hand, pDAV and pRPQ did not revert the PT-gliadin-induced phenotypic maturation of DC. Here we report, for the first time, that naturally occurring peptides are able to prevent the gliadin-dependent DC maturation. This finding could have implication for CD, raising the perspective of a potential therapeutic strategy alternative to a gluten free diet.