Background: The incidence of Inflammatory bowel disease (IBD) is increasing worldwide and the current therapeutic strategies are limited by reduced effectiveness, high costs, and/or presence of toxic/side effects. We have previously demonstrated that UC patients display a deficiency in the levels of glycosylation of mucosal T cells that was associated with disease severity .
However, it remains unknown whether this mechanism can be therapeutically targeted in IBD.
Methods: We conducted ex vivo and in vivo studies in order to evaluate the impact of glycans supplementation in the regulation of T cell-mediated immune response. Purified mucosal T cells were obtained from fresh colonic biopsies of 68 Ulcerative Colitis (UC) patients with active disease and the effects of the supplementation with specific glycans in the adaptive immune response were studied by analysing T cell proliferation (by CFSE assay); T cell differentiation and cytokines production (by flow cytometry) and TCR signaling (by western blot). Additionally, we used in vivo mouse models of colitis (DSS-induced) as well as transgenic mice with different glycosylation profiles to assess the impact of glycans in the control of disease severity and disease progression.
Results: The results on ex vivo T cells cultures revealed that the supplementation with specific glycans is able to enhance the glycosylation of T cells, repairing the previously described deficiency on branched glycans in T lymphocytes .
We observed that increasing doses of specific glycans resulted in a significant reduction of T cell proliferation, suppression of Th1 and Th17 response through decreasing the expression of the transcription factors, T-bet and RORγt and the respective cytokines production, TNF-α, INF-γ and IL17A. Downstream TCR signaling was also suppressed as observed by the reduction in phosphorylation levels of ZAP70 and LAT. Interestingly, our in vivo data reveal that mice with colitis treated with specific glycans exhibited a suppression of disease severity and a delay in disease progression as demonstrated by low disease activity index (DAI) and suppression of Th1 immune response in the gut.
Conclusions: Our data suggest that enhancing the glycosylation of T cells resulted in a significant suppression of T cell mediated-immune response associated with the control of intestinal inflammation and suppression of disease severity and progression. Glycans are thus a novel and promising target-specific immunomodulatory therapy in IBD.
 Dias, AM et al., (2014), Dysregulation of T cell receptor N-glycosylation: a molecular mechanism involved in ulcerative colitis, Human Molecular Genetics