Transamidated wheat gliadin induces differential antigen recognition in the small intestine of HLA/DQ8 transgenic mice

Abstract

A lifelong gluten-free diet (GFD) is currently the only available therapy for coeliac disease (CD). However, GFD compliance is difficult and alternative strategies are envisaged in the near future. We previously found that wheat gliadin following transamidation by microbial transglutaminase (mTG) does not induce IFN-γ secretion by intestinal T cells from CD patients. Fully transamidated gliadin with lysine ethyl ester can be recovered in a soluble protein fraction (spf) generated by the enzymatic treatment of wheat flour. Herein, we analysed the performance of transamidation by mTG on a pilot-scale (1L) by evaluating the reaction kinetics and its biological effect on the intestinal immune response in HLA/DQ8 transgenic mice, a model of gluten sensitivity. At 1 h, all gliadin fractions showed a faster electrophoretic mobility by acid-polyacrylamide gel electrophoresis (A-PAGE) following transamidation in comparison with their native counterparts. In parallel, the yield of residual native gliadin dropped (30% at 180 min), confirming our previous findings on a lab scale. Mucosal sensitisation of mice with gliadin via the intranasal route induced a Th1 phenotype in mesenteric lymph nodes (MLNs). Importantly, IFN-γ secretion was significantly reduced when gliadin-specific MLN cells were challenged in vitro with spf (P < 0.001). Multiplex analysis revealed that the adaptive immune response evoked by spf involved a distinct cell population characterised by secretion of IL-2, IL-3 and IL-5. Notably, spf stimulated in vitro a reduced or null secretion of all of the examined pro-inflammatory markers mainly associated to innate immunity. In conclusion, our data revealed the ability of transamidated gliadin to modulate both innate and adaptive mechanisms involved in the inflammatory response induced by wheat gliadin in the small intestine of DQ8 mice.