Identification of an anergic BND cell-derived activated B cell population (BND2) in young-onset type 1 diabetes
Ontology highlight
ABSTRACT: Recent evidence suggests a role for B cells in the pathogenesis of type 1 diabetes (T1D), particularly in individuals who develop T1D at a younger age and demonstrate rapid progression and beta cell loss. However, little is known regarding the specificity, phenotype, and function of B cells in young-onset T1D. We performed a cross-sectional analysis comparing insulin-reactive to tetanus-reactive B cells in the blood of T1D and controls using mass cytometry. Unsupervised clustering revealed the existence of a highly activated B cell subset, we term BND2, that falls within the previously defined anergic BND subset. We found a specific increase in the frequency of insulin-reactive BND2 cells in the blood of young-onset T1D donors, which was further enriched in the pancreatic lymph nodes of T1D donors. The frequency of insulin-binding BND2 cells correlated with anti-insulin autoantibody levels in T1D subjects. We demonstrate BND2 cells phenotypically and functionally are pre-plasma cells and can likely act as antigen-presenting cells to T cells. These findings suggest that activation of insulin-reactive anergic B cells may play a role in the rapid progression of young-onset T1D and warrants further investigation in other autoimmune conditions.
Project description:Beta-cells produce hybrid insulin peptides (HIPs) by linking insulin fragments to other peptides through peptide bonds. HIPs have unique amino acid sequences and are targeted by autoreactive T cells in type 1 diabetes (T1D). Individuals with recent-onset T1D have significantly higher levels of HIP-reactive T cells in their blood compared to non-diabetic control subjects. HIP-reactive T cells have also been found in the residual pancreatic islets of deceased T1D organ donors. In non-obese diabetic (NOD) mice, a major T1D animal model, several CD4 T cell clones that trigger diabetes have been shown to target HIPs. Through mass spectrometry, a subgroup of HIPs containing N-terminal amine groups of various peptides linked to aspartic acid residues of insulin C-peptide has been detected in NOD islets. Our research reveals that these HIPs form spontaneously in beta-cells via an aspartic anhydride intermediate mechanism. This process leads to the creation of a regular HIP with a standard peptide bond and a HIP-isomer (isoHIP) with an isopeptide bond linked to the carboxylic acid side-chain of the aspartic acid residue. Our mass spectrometric analyses confirmed the presence of both HIP isomers in murine islets, thereby validating the occurrence of this new reaction mechanism in beta-cells. The spontaneous formation of neoepitopes through the development of new peptide bonds within cells may contribute to the pathogenesis of T1D and other autoimmune diseases.
Project description:Autoreactive B cells play an important but ill-defined role in autoimmune type 1 diabetes (T1D). To better understand their contribution to disease, we performed single cell gene expression and BCR-seq on pancreatic islet antigen-reactive (IAR) B cells from the peripheral blood of nondiabetic (ND), autoantibody positive prediabetic (AAB), and recent-onset T1D individuals. We found that the frequency of IAR B cells was increased particularly in AAB, but also in T1D compared to ND donors. Additionally, IAR B cells from AAB and T1D donors exhibited differential gene expression in B cell signaling, pro-inflammatory, infection, and antigen processing and presentation pathways compared to ND donors. Strikingly, both AAB and T1D donors demonstrated a significant increase in particular heavy and light chain V gene usages compared to ND, and these B cells were enriched in islet-reactivity. Shared public clones of IAR B cells were found almost entirely among the AAB and T1D donors. IAR B cells were clonally expanded in the autoimmune donors, particularly the AAB group. Notably, a substantial fraction of IAR B cells in AAB and T1D donors appeared to be polyreactive and was confirmed by production of recombinant monoclonal antibodies. Altogether, these results expand our current understanding of B cells during development of T1D, how autoreactive B cells may become activated, and identify unique BCR repertoire differences that may serve as biomarkers for increased disease risk. These findings could be applied to future therapeutic approaches to prevent or treat T1D, as well as assess response to therapy.
Project description:Type 1 diabetes (T1D) is caused by the autoimmune destruction of insulin-producing pancreatic beta cells, leading to life-long dependence on exogenous insulin. Profiling immune cells that infiltrate islets would be invaluable to understanding how beta cell destruction occurs. However, human pancreatic samples demonstrating active infiltration and beta cell destruction are rare. Alternatively, peri-pancreatic lymph nodes (pLNs) or other secondary lymphoid organs may harbor immune cells which participate in memory responses that drive T1D autoimmunity. To study the immune response throughout T1D onset and disease, lymphocytes from pLNs, mesenteric lymph nodes (mesLNs), and the spleen were collected from human T1D, auto-antibody positive (AAb+), and normal donors (NDs) enrolled in the Human Pancreas Analysis Program (HPAP). Tissue immune cell identity, phenotype, and transcriptional status was analyzed using Cellular Indexing of Transcriptomes and Epitopes by Sequencing (CITEseq). Lymphocytes from 17 pLN, 9 mesLN, and 15 spleen samples spanning 7 ND, 5 AAb+, and 7 T1D donors were thawed and processed through the CITEseq pipeline. 5 donors per disease group had a paired pLN and spleen sample, with 3 of the 5 donors having a paired mesLN sample, allowing for cross-tissue immune status comparison spanning multiple stages of disease onset. The dataset provides one of the first and largest CITEseq datasets on human AAb+ and T1D samples publicly available.
Project description:compare gene expression profiles between normal and anergic T cells and identify upregulated genes in anergic T cells Experiment Overall Design: RNA from normal Th1 T cell clone and anergic Th1 T cell clone made anergic by plate-bound anti-CD3 antibody were isolated and amplified for microarray analysis
Project description:How human islet antigen reactive CD4+ memory T cells (IAR T cells) from peripheral blood affect Type 1 Diabetes (T1D) progression in the pancreas is poorly understood. We identified paired alpha/beta (TRA/TRB) T cell receptors (TCRs) in IAR T cells from the blood of healthy, at-risk, new onset, and established T1D donors, and measured sequence overlap with TCRs in pancreata from organ donors. We detected extensive TRA junction sharing between IAR T cells and pancreatic infiltrating T cells (PIT), with perfect or single mismatched TRA junction amino acid sequences comprising ~34% of unique IAR TRA junctions. PIT-matched TRA junctions were largely public, and showed significant nucleotide sequence convergence, increased use of germline-encoded residues in epitope engagement, and a potential for cross-reactivity. The link with T cells in the pancreas implicates autoreactive IAR T cells with shared TRA junctions in the prediabetic and new onset phases of T1D progression.
Project description:How human islet antigen reactive CD4+ memory T cells (IAR T cells) from peripheral blood affect Type 1 Diabetes (T1D) progression in the pancreas is poorly understood. We identified paired alpha/beta (TRA/TRB) T cell receptors (TCRs) in IAR T cells from the blood of healthy, at-risk, new onset, and established T1D donors, and measured sequence overlap with TCRs in pancreata from organ donors. We detected extensive TRA junction sharing between IAR T cells and pancreatic infiltrating T cells (PIT), with perfect or single mismatched TRA junction amino acid sequences comprising ~34% of unique IAR TRA junctions. PIT-matched TRA junctions were largely public, and showed significant nucleotide sequence convergence, increased use of germline-encoded residues in epitope engagement, and a potential for cross-reactivity. The link with T cells in the pancreas implicates autoreactive IAR T cells with shared TRA junctions in the prediabetic and new onset phases of T1D progression.
Project description: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.
Project description: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.
Project description: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.
Project description: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.