Predictive, Preventive and Personalized Medicine & Molecular Diagnostics

Biography

Biography: Constantin Polychronakos

Abstract

Background: Type 1 diabetes (T1D) is due to the autoimmune destruction of the pancreatic -cells. Autoantigen specificity is determined by the T-cell receptors (TCRs) of autoreactive lymphocytes but their characteristics are poorly understood. Next-generation sequencing now offers methodological possibilities for exploring the vast diversity of the somatically rearranged TCRs for possibilities of personalized diagnosis and intervention. Objective: To define the TCRs reactive to whole proinsulin, the most important T1D autoantigen. Methods: We examined T-cells from the peripheral blood of nine children with T1D and two normal controls, by proliferated in vitro after 12 days of activation with proinsulin and isolated by CFSE dye-dilution flow-sorting. TCRs were amplified from whole RNA by 5’RACE and amplicons sequenced on the Illumina miSeq with a 250x2 protocol. Beta-chain reads were analysed by a paired-end modification of the standard algorithm. Results: Response to proinsulin was highly polyclonal in the T1D patients but much fewer clones were seen in the two controls, where 29% and 80% of all proliferating clones had the same TCR (p=0.018, rank test). Interestingly, 562 out of the 5,446 clones that showed at least 20-fold expansion were “public”, i.e. exactly the same in different subjects. These clones tended to have a higher ratio of expansion (mean 123 vs. 103, p=0.04 Conclusion: TCR clonality of proinsulin specificities appears to distinguish cases from controls and, if confirmed, may be an important predictor of diabetes, and immune-progress biomarker. Definition of the main TCR clones in early pre-diabetes may provide opportunities for antigen-specific immunosuppression.