Recent-onset Type 1 Diabetes Patients Research Articles

Apoptosis of CD4+CD25high T Cells in Type 1 Diabetes May Be Partially Mediated by IL-2 Deprivation

BackgroundType 1 diabetes (T1D) is a T-cell mediated autoimmune disease targeting the insulin-producing pancreatic β cells. Naturally occurring FOXP3+CD4+CD25high regulatory T cells (Tregs) play an important role in dominant tolerance, suppressing autoreactive CD4+ effector T cell activity. Previously, in both recent-onset T1D patients and β cell antibody-positive at-risk individuals, we observed increased apoptosis and decreased function of polyclonal Tregs in the periphery. Our objective here was to elucidate the genes and signaling pathways triggering apoptosis in Tregs from T1D subjects.Principal FindingsGene expression profiles of unstimulated Tregs from recent-onset T1D (n = 12) and healthy control subjects (n = 15) were generated. Statistical analysis was performed using a Bayesian approach that is highly efficient in determining differentially expressed genes with low number of replicate samples in each of the two phenotypic groups. Microarray analysis showed that several cytokine/chemokine receptor genes, HLA genes, GIMAP family genes and cell adhesion genes were downregulated in Tregs from T1D subjects, relative to control subjects. Several downstream target genes of the AKT and p53 pathways were also upregulated in T1D subjects, relative to controls. Further, expression signatures and increased apoptosis in Tregs from T1D subjects partially mirrored the response of healthy Tregs under conditions of IL-2 deprivation. CD4+ effector T-cells from T1D subjects showed a marked reduction in IL-2 secretion. This could indicate that prior to and during the onset of disease, Tregs in T1D may be caught up in a relatively deficient cytokine milieu.ConclusionsIn summary, expression signatures in Tregs from T1D subjects reflect a cellular response that leads to increased sensitivity to apoptosis, partially due to cytokine deprivation. Further characterization of these signaling cascades should enable the detection of genes that can be targeted for restoring Treg function in subjects predisposed to T1D.

Impaired CD4+ and CD8+ T cell phenotype and reduced chemokine secretion in recent-onset type 1 diabetic children

Although the role of the T cell-mediated autoimmune reaction in type 1 diabetes (T1D) is conclusive, studies including data from human circulating CD4(+) and CD8(+) lymphocytes subsets during the disease onset and posterior development are scarce. Further, chemokines and chemokine receptors are key players in the migration of pathogenic T cells into the islets of non-obese diabetic mice developing T1D, but few studies have investigated these markers in human T1D patients. We studied the expression of T helper 1 (Th1)- and Th2-associated chemokine receptors, and the two isoforms of CD45 leucocyte antigen on CD4(+) and CD8(+) lymphocytes from T1D and healthy children, as well as the secretion of chemokines in cell supernatants in peripheral blood mononuclear cells. Our results showed increased expression of CCR7 and CD45RA and reduced CD45RO on CD8(+) cells among recent-onset T1D patients. The percentages of CD4(+) cells expressing CXC chemokine receptor 3 (CXCR3), CXCR6 and CCR5, and the secretion of interferon-gamma-induced protein-10, monocyte chemoattractant protein-1, macrophage inflammatory protein (MIP)-1alpha and MIP-1beta was lower among diabetics. Low expression of Th1-associated receptors and secretion of chemokines, together with an increased amount of CD8(+) cells expressing CD45RA and CCR7 in T1D patients therefore might represent suboptimal Th function in T1D, leading to impaired T cytotoxic responses or alternatively reflect a selective recruitment of Th1 cells into the pancreas.

Identification of novel IGRP epitopes targeted in type 1 diabetes patients

CD8 + T cells play an important role in the development of type 1 diabetes (T1D) in NOD mice and humans. IGRP (islet-specific glucose-6-phosphatase catalytic subunit-related protein) has emerged in recent years as a major antigen in NOD mice. Therefore, we aimed to determine if IGRP is an antigen in T1D patients and to identify the HLA-A2-restricted IGRP epitopes targeted. Using IFN-γ ELISPOT assay, we tested PBMC from recent-onset pediatric T1D patients and healthy controls for reactivity to four IGRP peptides directly ex vivo. Importantly, 65% of patients and 0% of controls were positive for at least one IGRP peptide. Two of these have not been reported previously. These data provide evidence that IGRP is a CD8 + T cell antigen in humans, contributing to the understanding of the underlying disease process as well as to future directions for diagnosis and monitoring disease progression in T1D patients.

IGRP-reactive T cells can be detected directly ex vivo in the blood of type 1 diabetes patients (129.45)

Abstract Both CD4 and CD8 T cells are required for the development of type 1 diabetes (T1D) in NOD mice and several antigens are known to be involved in the development of the disease. Among them is IGRP (islet-specific glucose 6 phosphatase catalytic subunit related protein), which has emerged in recent years as an important antigen in NOD mice. IGRP-reactive CD8 T cells constitute up to 30–40% of islet infiltrating T cells and these cells can be detected directly ex vivo in islet infiltrates and peripheral blood. To determine whether IGRP is a CD8 T cell antigen in humans, we created a panel of 4 HLA-A2 restricted IGRP epitopes (IGRP211-219, IGRP215-223, IGRP222-230, and IGRP265-273) to be screened directly ex vivo by IFN-γ ELISPOT. We performed the study with unfractionated PBMC from 21 recent-onset T1D patients (mean age 9.2 ± 4.3 years old) and 12 healthy controls (29.7 ± 5.7 years old) with the candidate peptides. Our results show that 66% of patients and 8% of healthy controls are positive for at least 1 IGRP peptide and 57% of patients versus 0% of controls are positive for 2 IGRP peptides. These data provide evidence that IGRP is a CD8 T cell antigen in humans, and that IGRP-reactive T cells can be detected ex vivo in the blood of T1D patients. This contributes to the understanding of the underlying disease process in humans as well as to future directions for diagnosis and intervention in T1D patients.