HLA Class II Antigen Processing and Presentation Pathway Components Demonstrated by Transcriptome and Protein Analyses of Islet β-Cells From Donors With Type 1 Diabetes

Abstract

Type 1 diabetes studies consistently generate data showing islet b-cell dysfunction and T cell-mediated anti-b-cell-specific autoimmunity. To explore the pathogenesis, we interrogated the b-cell transcriptomes from donors with and without type 1 diabetes using both bulk-sorted and single b-cells. Consistent with immunohistological studies, b-cells from donors with type 1 diabetes displayed increased Class I transcripts and associated mRNA species. These b-cells also expressed mRNA for Class II and Class II antigen presentation pathway components, but lacked the macrophage marker CD68. Immunohistological study of three independent cohorts of donors with recent-onset type 1 diabetes showed Class II protein and its transcriptional regulator Class II MHC trans-activator protein expressed by a subset of insulin + CD68 2 b-cells, specifically found in islets with lymphocytic infiltrates. b-Cell surface expression of HLA Class II was detected on a portion of CD45 2 insulin + b-cells from donors with type 1 diabetes by immunofluorescence and flow cytometry. Our data demonstrate that pancreatic b-cells from donors with type 1 diabetes express Class II molecules on selected cells with other key genes in those pathways and inflammation-associated genes. b-Cell expression of Class II molecules suggests that b-cells may interact directly with islet-infiltrating CD4 + T cells and may play an immunopathogenic role. The immune system plays a critical role in human type 1 diabetes pathogenesis. Varying proportions of T-cell subsets (CD8 + and CD4 +) and B cells infiltrate the pancreatic islets (1) and target b-cells by recognizing type 1 diabetes-associated autoantigens (2,3). The immunological mechanisms recruiting these cells to the islets had remained incompletely understood because, until recently, islets from donors with type 1 diabetes were not available for study. Antigen presentation to T cells is mediated by antigen-presenting cells (APCs) via two classes of HLA molecules: HLA Class I, recognized by CD8 +-expressing T cells (Class I is present on nearly all nucleated cells), and

Pancreatic β‐cells express major histocompatibility complex class II: Do diabetic β‐cells have the capacity of antigen‐presenting cells?

“…Immunostaining using pancreatic tissue showed that MHC class II and CIITA were not stained in non‐diabetic pancreatic islets, but were occasionally found in the islets patients with type 1 diabetes. Furthermore, CD68 + cells (macrophages) exist independently of CIITA + β‐cells, and it was shown that in this study, CIITA and insulin double positive cells were not macrophages that phagocytosed β‐cells.…”

“…Russell et al . approached this argument with a novel technique called transcriptome analysis using donor islets as samples.…”

“…Pancreatic β‐cells were sorted by fluorescence‐activated cell sorting from pancreatic islets obtained from 12 non‐diabetic donors and four type 1 diabetes donors. Ribonucleic acid sequencing of bulk‐sorted pancreatic β‐cells showed expression of not only MHC class I gene, but also MHC class II and MHC class II‐related genes, such as CIITA , in pancreatic β‐cells from patients with type 1 diabetes. Furthermore, islet cells from one non‐diabetic donor and one type 1 diabetes donor were separated, and single‐cell ribonucleic acid sequencing was carried out; and islet cells, including α‐cells or β‐cells, were distinguished by two‐dimensional plots using t‐distributed stochastic neighbor embedding.…”

“…Furthermore, islet cells from one non‐diabetic donor and one type 1 diabetes donor were separated, and single‐cell ribonucleic acid sequencing was carried out; and islet cells, including α‐cells or β‐cells, were distinguished by two‐dimensional plots using t‐distributed stochastic neighbor embedding. Furthermore, as a result of examining the gene profile of MHC class II or class II invariant chain CD74 in these pancreatic β‐cells, MHC class II expression was observed in 35.2% of pancreatic β‐cells from type 1 diabetes patients, but 7.8% in non‐diabetic pancreatic β‐cells.…”

Recovery of viable endocrine‐specific cells and transcriptomes from human pancreatic islet‐engrafted mice

“…Following FASTQ file generation in BaseSpace (Illumina), sequence files from bulk cell libraries were processed as described previously, 14 except that expected counts were filtered to include only genes with > 10 counts in at least three samples prior to submission to DESeq2 for differential gene expression analysis. Genes with at least a twofold change in expression and adjusted P values of < .01 were considered differentially expressed between pretransplant and posttransplant groups.…”