RNA-seq of islet-specific CD8 T cells in the spleen and pancreatic islets
Ontology highlight
ABSTRACT: T cells infiltrate pancreatic islets during the progression of type 1 diabetes (T1D) but their differentiation states have not been completely defined. We used unbiased single-cell RNA sequencing analyses to gain further insight into the phenotypic complexity of islet-infiltrating T cells in non-obese diabetic (NOD) mice. In the CD4 T cell compartment, we identified naïve, memory, and regulatory T cells, as well as multiple Il21 expressing effector subsets positive for markers indicative of Th1 and Tfh cells. In CD8 T cells, we identified two activated subsets in addition to naïve cells. The two activated islet CD8 T cell subsets respectively resemble the self-renewing progenitor cells and the terminally differentiated/exhausted effectors during chronic lymphocytic choriomeningitis virus infection. We also identified a BATF-driven transcriptional signature promoting the diabetogenic activity of islet-infiltrating β cell autoreactive CD8 T effectors. Our results provide a useful resource for understanding T cell differentiation programs in T1D.
Project description:T cells infiltrate pancreatic islets during the progression of type 1 diabetes (T1D) but their differentiation states have not been completely defined. We used unbiased single-cell RNA sequencing analyses to gain further insight into the phenotypic complexity of islet-infiltrating T cells in non-obese diabetic (NOD) mice. In the CD4 T cell compartment, we identified naïve, memory, and regulatory T cells, as well as multiple Il21 expressing effector subsets positive for markers indicative of Th1 and Tfh cells. In CD8 T cells, we identified two activated subsets in addition to naïve cells. The two activated islet CD8 T cell subsets respectively resemble the self-renewing progenitor cells and the terminally differentiated/exhausted effectors during chronic lymphocytic choriomeningitis virus infection. We also identified a BATF-driven transcriptional signature promoting the diabetogenic activity of islet-infiltrating β cell autoreactive CD8 T effectors. Our results provide a useful resource for understanding T cell differentiation programs in T1D.
Project description:In type 1 diabetes (T1D) autoreactive CD8 T cells infiltrate pancreatic islets and destroy insulin-producing β cells. Progression to T1D onset is a chronic process, which suggests that the effector activity of β-cell autoreactive CD8 T cells needs to be maintained throughout the course of disease development. The mechanism that sustains diabetogenic CD8 T cell effectors during the course of T1D progression has not been completely defined. Here we used single-cell RNA sequencing to gain further insight into the phenotypic complexity of islet-infiltrating CD8 T cells in NOD mice. We identified two functionally distinct subsets of activated CD8 T cells, CD44highTCF1+CXCR6- and CD44highTCF1-CXCR6+, in islets of prediabetic NOD mice. Compared to CD44highTCF1+CXCR6- CD8 T cells, the CD44highTCF1-CXCR6+ subset expressed higher levels of inhibitory and cytotoxic molecules and was more prone to apoptosis. Adoptive cell transfer experiments revealed that CD44highTCF1+CXCR6- CD8 T cells, through continuous generation of the CD44highTCF1-CXCR6+ subset, were more capable than the latter population to promote insulitis and the development of T1D. We further showed that direct interleukin-27 (IL-27) signaling in CD8 T cells promoted the generation of terminal effectors from the CD44highTCF1+CXCR6- population. These results indicate that islet CD44highTCF1+CXCR6- CD8 T cells are a progenitor-like subset with self-renewing capacity and under an IL-27 controlled mechanism they differentiate into the CD44highTCF1-CXCR6+ terminal effector population. Our study provides new insight into the sustainability of the CD8 T cell response in the pathogenesis of T1D.
Project description:Interleukin (IL)-21 is essential for type 1 diabetes (T1D) development in the NOD mouse model. IL-21-expressing CD4 T cells are present in pancreatic islets where they contribute to disease progression. However, little is known about their phenotype and differentiation states. To fill this gap, we generated a novel IL-21 reporter NOD strain to further characterize IL-21+ CD4 T cells in T1D. IL-21+ CD4 T cells accumulate in pancreatic islets and recognize β-cell antigens. Single-cell RNA sequencing revealed that most CD4 T effector cells in islets actively express IL-21 and they are highly diabetogenic despite expressing multiple inhibitory molecules, including PD-1 and LAG3. Islet IL-21+ CD4 T cells segregate into four phenotypically and transcriptionally distinct differentiation states, less differentiated early effectors, Tfh-like cells, and two Th1 subsets. Trajectory analysis predicts that early effectors differentiate into both Tfh-like and terminal Th1 cells. We further demonstrated that intrinsic IL-27 signaling controls the differentiation of islet IL-21+ CD4 T cells, contributing to their helper function. Collectively, our study reveals the heterogeneity of islet-infiltrating IL-21+ CD4 T cells and indicates that both Tfh-like and Th1 subsets continuously produce IL-21 throughout their differentiation process, highlighting the important sources of IL-21 in T1D pathogenesis.
Project description:Human Naïve-like CD8 T cells induced by the Yellow Fever Vaccine 17D were compared to the conventional subsets in total CD8 T cells Samples originate from peripheral blood mononuclear cells (PBMC) from 8 different donors vaccinated with the YF-17D vaccine 1'000 cells from various CD8 T cells subsets were purified by flow cytometry, from 8 vaccinees (donors d1 to d8); the subsets (cell types) include: A2/NS4b tetramer positive CCR7+ CD45RA+ CD8 T cells (A2_NS4b Naïve-like), Total Naive (CCR7+ CD45RA+), Total Tscm (CCR7+ CD45RA+ CD58+ CD95+), Total CM (CCR7+ CD45RA-) and Total Effectors (CCR7 negative).
Project description:Interferon (IFN)-α is the earliest cytokine signature observed in individuals at risk for type 1 diabetes (T1D), but its effect on the repertoire of HLA Class I (HLA-I)-bound peptides presented by pancreatic β-cells is unknown. Using immunopeptidomics, we characterized the peptide/HLA-I presentation in in-vitro resting and IFN-α-exposed β-cells. IFN-α increased HLA-I expression and peptide presentation, including neo-sequences derived from alternative mRNA splicing, post-translational modifications - notably glutathionylation - and protein cis-splicing. This antigenic landscape relied on processing by both the constitutive and immune proteasome. The resting β-cell immunopeptidome was dominated by HLA-A-restricted ligands. However, IFN-α only marginally upregulated HLA-A and largely favored HLA-B, translating into a major increase in HLA-B-restricted peptides and into an increased activation of HLA-B-restricted vs. HLA-A-restricted CD8+ T-cells. A preferential HLA-B hyper-expression was also observed in the islets of T1D vs. non-diabetic donors, and islet-infiltrating CD8+ T-cells from T1D donors were reactive to some HLA-B-restricted granule peptides. Thus, the inflammatory milieu of insulitis may skew the autoimmune response toward epitopes presented by HLA-B, hence recruiting a distinct T-cell repertoire that may be relevant to T1D pathogenesis.
Project description:Interferon (IFN)-α is the earliest cytokine signature observed in individuals at risk for type 1 diabetes (T1D), but its effect on the repertoire of HLA Class I (HLA-I)-bound peptides presented by pancreatic β-cells is unknown. Using immunopeptidomics, we characterized the peptide/HLA-I presentation in in-vitro resting and IFN-α-exposed β-cells. IFN-α increased HLA-I expression and peptide presentation, including neo-sequences derived from alternative mRNA splicing, post-translational modifications - notably glutathionylation - and protein cis-splicing. This antigenic landscape relied on processing by both the constitutive and immune proteasome. The resting β-cell immunopeptidome was dominated by HLA-A-restricted ligands. However, IFN-α only marginally upregulated HLA-A and largely favored HLA-B, translating into a major increase in HLA-B-restricted peptides and into an increased activation of HLA-B-restricted vs. HLA-A-restricted CD8+ T-cells. A preferential HLA-B hyper-expression was also observed in the islets of T1D vs. non-diabetic donors, and islet-infiltrating CD8+ T-cells from T1D donors were reactive to some HLA-B-restricted granule peptides. Thus, the inflammatory milieu of insulitis may skew the autoimmune response toward epitopes presented by HLA-B, hence recruiting a distinct T-cell repertoire that may be relevant to T1D pathogenesis.
Project description:Autoreactive CD8+ T cell plays a key role in the pathogenesis of Type 1 diabetes (T1D), but the antigen spectrum that activate autoreactive CD8+ T cells is still not completely clear. Endoplasmic reticulum stress(ERS)has been implicated in the generation of β cell autoantigens and the enhanced immune visibility of β cells to autoreactive T cells. Here, we in-depth analyzed the major histocompatibility complex class I (MHC-I) associated immunopeptidome (MIP) of islets β cell under steady-state and ERS-state, and found couples of peptides exclusively present in the MIP of β cell line under ERS state. Among them, peptide OTUB258-66 derived from ubiquitin thioesterase OTUB2 showed immunodominance in NOD mice, and autoreactive CD8+ T cells targeting OTUB258-66 were diabetogenic in NOD mice. High glucose intake upregulated the expression of OTUB2 in the pancreas and amplified the OTUB258-66-specific CD8+ T cell response in NOD mice. Repeated administration with OTUB258-66 significantly reduced the incidence of T1D in NOD mice. This study not only provides an explanation for the role of ERS induced by environmental factors such as high glucose intake in promoting β cell autoimmune injury, but also provides a novel ERS-associated β cell autoantigens for developing specific immune intervention in prevention and treatment of T1D.
Project description:A major hypothesis for the etiology of type 1 diabetes (T1D) postulates initiation by viral infection, leading to double-stranded RNA (dsRNA)-mediated interferon response and inflammation; however, a causal virus has not been identified. Here we use a mouse model, corroborated with human islet data, to demonstrate that endogenous dsRNA in beta cells can lead to a diabetogenic immune response, thus identifying a virus-independent mechanism for T1D initiation. We found that disruption of the RNA editing enzyme ADAR in beta cells triggers a massive interferon response, islet inflammation and beta cell failure and destruction, with features bearing striking similarity to early-stage human T1D. Glycolysis via calcium enhances the interferon response, suggesting an actionable vicious cycle of inflammation and increased beta cell workload.
Project description:Type 1 diabetes (T1D) is characterized by pancreatic islet infiltration by autoreactive immune cells and a near-total loss of β-cells. Restoration of insulin-producing β-cells coupled with immunomodulation to suppress the autoimmune attack has emerged as a potential approach to counter T1D. Here we report that enhancing β-cell mass in female NOD mice early in life (prior to weaning) results in immunomodulation of T-cells, reduced islet infiltration and lower β-cell apoptosis, that together protect them from developing T1D. We observed that a model exhibiting β-cell hyperplasia on the NOD background (NOD-LIRKO) displayed altered β-cell antigens, and islet transplantation studies showed prolonged graft survival of NOD-LIRKO islets even upon exposure to diabetogenic splenocytes in vivo. Adoptive transfer of splenocytes from the NOD-LIRKOs prevented diabetes development in pre-diabetic NOD mice, while conversely, similar protective outcomes were obtained when NOD-LIRKO splenocytes were adoptively transferred after mixing them with diabetogenic NOD splenocytes in a dose-dependent manner. A significant increase in the splenic CD4+CD25+FoxP3+ regulatory T-cell (Treg) population in the NOD-LIRKO mice was observed to drive the protected phenotype since Treg depletion rendered NOD-LIRKO mice diabetic. The increase in Tregs coupled with a downregulation of key mediators of cellular function, upregulation of apoptosis and activation of TGF-β/SMAD3 signaling pathway in pathogenic T-cells favored reduced ability to kill β-cells. These data provide novel evidence that initiating β-cell proliferation, alone, prior to islet infiltration by immune cells alters the identity of β-cells, decreases pathologic self-reactivity of effector cells and increases Tregs to prevent progression of T1D.
Project description:Autoreactive CD8+ T-cells recognizing autoantigens expressed by pancreatic islets lead to the destruction of insulin-producing β-cells in type 1 diabetes, but these T-cell also occur in healthy subjects. We tested the hypothesis that uncontrolled expansion of diabetogenic T-cells in patients occurs, resulting from failure to activate apoptosis. We compared function, transcriptome and epigenetic regulation thereof in relation with fate upon repeated exposure to islet-autoantigen of islet autoreactive T-cells from healthy and type 1 diabetic donors with identical islet epitope specificity and HLA-A2 restriction. Patient's T-cells proliferated exponentially, whereas those of non-diabetic origin succumbed to cell death. Transcriptome analysis revealed reduced expression of TRAIL, TRAIL-R2, FAS and FASLG (members of the extrinsic apoptosis pathway) in patient-derived compared to healthy-donor-derived T cells. This was mirrored by increased expression of microRNAs predicted to regulate these particular genes, namely miR-98, miR-23b and miR-590-5p. Gene specific targeting by these microRNAs was confirmed using dual-luciferase reporter assays. Finally, transfection of these microRNAs into primary T-cells reduced FAS and TRAIL mRNA underscoring their functional relevance. We propose that repression of pro-apoptotic pathways by microRNAs contributes to unrestricted expansion of diabetogenic cytotoxic T-cells, implicating microRNA-mediated gene silencing in islet autoimmunity in T1D.