PRJNA379013: Single cell RNA-seq reveals expansion of IGRP-reactive CD4+ T cells in recent onset type I diabetes (single-cell RNA-seq of T-cell clone)

Summary: Islet-reactive T cells found in peripheral blood of type 1 diabetes (T1D) subjects are thought to be involved in disease pathogenesis, but full understanding of their role is complicated by their presence also in blood of in healthy subjects. To elucidate their role in T1D, we have combined flow cytometry and single cell RNA sequencing (RNA-seq) techniques to link prior antigen exposure, inferred from expanded TCR clonotypes, and functional capacities of islet antigen-reactive CD4+ memory T cells. We find that cells activated by pooled peptides from immunodominant islet antigens showed significantly higher clonotype sharing within recent onset T1D subjects than in healthy individuals, consistent with in vivo T cell expansion during disease progression. There was no clonotype sharing between donors, indicating a predominance of TCRs with distinct or “private” specificities. Expanded clonotypes could be stable, as one was detected at repeat visits by spanning more than a year by one subject. We identified distinct IGRP peptides as the targets of expanded TCR clonotypes from two T1D subjects, thereby implicating this molecule as a trigger for CD4+ T cell expansion during T1D. Transcriptome profiles of cells from T1D and healthy subjects differed, particularly in cells having the most highly expanded TCR clonotypes. As a group, cells with the most highly expanded TCR clonotypes showed Th2-like phenotypes, but at the single cell level there was phenotypic heterogeneity within and between donors. Our findings demonstrate unique specificities and phenotypes of individual islet-reactive CD4+ memory T cells that have expanded during disease progression.

Overall Design: This project contains RNA-seq files from four cell types: 1) T cell clone (N=149 single cell profiles); 2) T cell clone (N=9 bulk cell profiles); 3) CD8+ influenza-reactive T cells (N=45 single cell profiles); and 4) CD4+ pooled islet antigen-reactive T cells (N=246 single cell profiles).