Characterization of Diabetogenic CD8+ T Cells

Abstract

Type 1 diabetes (T1D) 2 in humans is an autoimmune disease involving the destruction of insulin-producing ␤ cells in the islets of Langerhans by CD8ϩ T cells (1-6). In humans, the disease develops over a period of years after the first appearance of autoantibodies that identify individuals who are at risk. The kinetics of progression to T1D differs from those of other cellmediated immune responses. In responding to foreign pathogens, there is rapid expansion of antigen-specific effector T cells followed by contraction and the appearance of memory T cells. Immune targets are destroyed within weeks. Primarily based on serologic data from studies of discordant triplets and relatives at risk for the disease, ␤ cell destruction in T1D is thought to occur over a period of years, although we and others have postulated that there was waxing and waning of the process. More recent data has suggested that the progression is not uniform. The time required for metabolic changes in glucose tolerance was thought to reflect the need to destroy a large ␤ cell mass before glucose tolerance deteriorates, but our studies of ␤ cell killing in NOD mice and humans suggests instead that the progression of ␤ cell killing may be rapid in the peridiagnosis period. In NOD mice, which first develop insulitis at 5-6 weeks of age, the rate of ␤ cell killing does not show a significant increase until after11 weeks of age coincident with the appearance of glucose intolerance. In our studies of ␤ cell killing in relatives of patients with T1D, only 25% of the 49 measurements that were obtained approximately every 6 months for up to 4.14 years before diagnosis showed increased levels, indicating that the destruction of ␤ cells is an uncommon event. However, in at-risk subjects who were closer to diagnosis and manifest dysglycemia, 81% of the measurements in 27 subjects showed elevated levels of ␤ cell death. These data showed that ␤ cell killing is significantly greater when glucose intolerance is present.These observations led us to consider whether there were interactions between the pathogenic immune cells and host factors that may affect the progression of disease. To understand these interactions, we focused our studies on CD8ϩ T cells that are reactive to an epitope of glucose-6-phosphatase catalytic subunit related protein (IGRP) and are known to cause ␤ cell killing. These CD8ϩ T cells are the best characterized among pathogenic T cells (2-4, 7-15). In human autopsy studies, CD8ϩ T cells reactive to an epitope of IGRP have been found in pancreata from patients several years after the onset of disease (6). IGRP-reactive CD8ϩ T cells can be found in NOD mice by staining with MHC-I tetramer loaded with NRP-V7 peptide (5,12,16). They can cause diabetes when they receive help from CD4ϩ T cells (13). We analyzed gene expression among these cells to identify mechanisms that might account * This work was supported, in whole or in part, by National Institutes of Health Grants R01 DK057846, U01 AI02011, and UC4 DK104205. The authors declare that th...

Autoreactive CD8+ T cell exhaustion distinguishes subjects with slow type 1 diabetes progression

“…A cutoff of TIGIT, and CD160. All 3 islet-specific clusters were CXCR3 + , consistent with previous reports (29). Thus, islet-specific CD8 + T cells are heterogeneous and dominated by 3 distinct CXCR3 + memory subsets: an exhaustion-like subset that was also dominant for insulin-and chronic virus-specific cells and 2 transitional memory phenotypes unique to islet-specific cells, 1 of which was HELIOS + .…”

Beta cell-specific CD8+ T cells maintain stem cell memory-associated epigenetic programs during type 1 diabetes

“…Given that human beta cell-specific CD8 + T cells isolated from the peripheral blood of individuals with T1D retain stem-associated DNA methylation programs following in vitro expansion, we sought to investigate whether the developmentally plastic state of self-reactive CD8 + T cells was also preserved in cells that traffic to the source of the antigen. To overcome the challenge of examining patient beta cell-specific T cells from various anatomical locations, we utilized an established murine model that allowed us to examine an endogenous immune response in a site-specific manner 30 . Tetramer + beta cell-specific CD8 + T cells were sorted from spleen, pancreatic lymph node, and pancreas of non-obese diabetic (NOD) mice and whole-genome DNA methylation profiling was performed.…”

“…Cells were then washed twice in 10 ml of HBSS + 10% FBS and centrifuged at 600 rcf for 3 minutes and resuspended in complete RPMI. For sorting, cells were washed in PBS twice and stained with the following antibodies: KLRG1 FITC (2F1; eBioscience 11-5893-82), CD62L Percp-cy5.5 (MEL-14; eBioscience 45-0621-82), CD8a PE-cy7 (53–6.7; BioLegend 100722), CD127 BV421 (A7R34; BioLegend 135024),Viability-Zombie Aqua (BioLegend 423101), CD44 APC (IM7; eBioscience 17-0441-82), CD4 BV711 (RM4-5; BioLegend 100550), PD-1 APC-750/Fire (29F.1A12; BioLegend 135240), and mouse NRP-V7 mimotope tetramer PE (KYNKANVFL/H-2K d ; NIH tetramer facility) 30 . Cells were sorted on viability dye-negative, CD4 − CD8 + , and tetramer + CD44 + on a Sony ICyt Synergy (Sony Biotechnology, Inc.).…”

Pharmacological Targeting of GLUT1 to Control Autoreactive T Cell Responses

“…In this model, diabetogenic CD8+ T cells specific for a peptide from the diabetes antigen IGRP (NRPV7- reactive) have features of activated memory T cells, including an increased glycolytic rate and oxidative phosphorylation. Treatment of these mice with 2DG resulted in a reduced frequency of activated T cell, reduced immune infiltration within the islets, and in improved β-cell granularity [36]. Although these findings are still preliminary, preclinical models of autoimmune conditions revealed the presence of an enhanced metabolic activity of autoreactive T cells.…”

“…Homeostatic proliferation is resistant to the inhibitory effect of standard immunosuppressive drugs [65] and was shown to drive the expansion of autoreactive memory T cell clones. Interestingly, T cells exposed to IL-7 up-regulate Glut1 and increase glucose uptake [23] rendering T cells more susceptible to Glut1 blockade [36].…”