PDL1 is expressed in the islets of people with type 1 diabetes and is up-regulated by interferons-α and-γ via IRF1 induction

Beta cell extracellular vesicle PD-L1 as a novel regulator of CD8+ T cell activity and biomarker during the evolution of Type 1 Diabetes

Aims/hypothesis

Surviving beta cells in type 1 diabetes respond to inflammation by upregulating programmed death-ligand 1 (PD-L1) to engage immune cell programmed death-1 (PD-1) and limit destruction by self-reactive immune cells. Extracellular vesicles (EVs) and their cargo can serve as biomarkers of beta cell health and contribute to islet intercellular communication. We hypothesized that the inflammatory milieu of type 1 diabetes increases PD-L1 in beta cell EV cargo and that EV PD-L1 may protect beta cells against immune-mediated cell death.

Methods

Beta cell lines and human islets were treated with proinflammatory cytokines to model the proinflammatory type 1 diabetes microenvironment. EVs were isolated using ultracentrifugation or size exclusion chromatography and analysed via immunoblot, flow cytometry, and ELISA. EV PD-L1: PD-1 binding was assessed using a competitive binding assay and in vitro functional assays testing the ability of EV PD-L1 to inhibit NOD CD8 T cells. Plasma EV and soluble PD-L1 were assayed in plasma of individuals with islet autoantibody positivity (Ab+) or recent-onset type 1 diabetes and compared to non-diabetic controls.

Results

PD-L1 protein colocalized with tetraspanin-associated proteins intracellularly and was detected on the surface of beta cell EVs. 24-h IFN-α or IFN-γ treatment induced a two-fold increase in EV PD-L1 cargo without a corresponding increase in number of EVs. IFN exposure predominantly increased PD-L1 expression on the surface of beta cell EVs and beta cell EV PD-L1 showed a dose-dependent capacity to bind PD-1. Functional experiments demonstrated specific effects of beta cell EV PD-L1 to suppress proliferation and cytotoxicity of murine CD8 T cells. Plasma EV PD-L1 levels were increased in islet Ab+ individuals, particularly in those with single Ab+, Additionally, in from individuals with either Ab+ or type 1 diabetes, but not in controls, plasma EV PD-L1 positively correlated with circulating C-peptide, suggesting that higher EV-PD-L1 could be protective for residual beta cell function.

Conclusions/interpretation

IFN exposure increases PD-L1 on the beta cell EV surface. Beta cell EV PD-L1 binds PD1 and inhibits CD8 T cell proliferation and cytotoxicity. Circulating EV PD-L1 is higher in islet autoantibody positive patients compared to controls. Circulating EV PD-L1 levels correlate with residual C-peptide at different stages in type 1 diabetes progression. These findings suggest that EV PD-L1 could contribute to heterogeneity in type 1 diabetes progression and residual beta cell function and raise the possibility that EV PD-L1 could be exploited as a means to inhibit immune-mediated beta cell death.

Regulation of STAT1 Signaling in Human Pancreatic β-Cells by the Lysine Deacetylase HDAC6: A New Therapeutic Opportunity in Type 1 Diabetes?

Type 1 diabetes arises from the selective destruction of pancreatic β-cells by autoimmune mechanisms, and intracellular pathways driven by Janus kinase (JAK)-mediated phosphorylation of STAT isoforms (especially STAT1 and STAT2) are implicated as mediators of β-cell demise. Despite this, the molecular mechanisms that regulate JAK-STAT signaling in β-cells during the autoimmune attack remain only partially disclosed, and the factors acting to antagonize proinflammatory STAT1 signaling are uncertain. We have recently implicated signal regulatory protein α (SIRPα) in promoting β-cell viability in the face of ongoing islet autoimmunity and have now revealed that this protein controls the availability of a cytosolic lysine deacetylase, HDAC6, whose activity regulates the phosphorylation and activation of STAT1. We provide evidence that STAT1 serves as a substrate for HDAC6 in β-cells and that sequestration of HDAC6 by SIRPα in response to anti-inflammatory cytokines (e.g., IL-13) leads to increased STAT1 acetylation. This then impairs the ability of STAT1 to promote gene transcription in response to proinflammatory cytokines, including interferon-γ. We further found that SIRPα is lost from the β-cells of subjects with recent-onset type 1 diabetes under conditions when HDAC6 is retained and STAT1 levels are increased. On this basis, we report a previously unrecognized role for cytokine-induced regulation of STAT1 acetylation in the control of β-cell viability and propose that targeted inhibition of HDAC6 activity may represent a novel therapeutic modality to promote β-cell viability in the face of active islet autoimmunity.

ARTICLE HIGHLIGHTS

Pharmaceutical targeting of the cannabinoid type 1 receptor impacts the crosstalk between immune cells and islets to reduce insulitis in humans

AIMS/HYPOTHESIS

Insulitis, a hallmark of inflammation preceding autoimmune type 1 diabetes, leads to the eventual loss of functional beta cells. However, functional beta cells can persist even in the face of continuous insulitis. Despite advances in immunosuppressive treatments, maintaining functional beta cells to prevent insulitis progression and hyperglycaemia remains a challenge. The cannabinoid type 1 receptor (CB1R), present in immune cells and beta cells, regulates inflammation and beta cell function. Here, we pioneer an ex vivo model mirroring human insulitis to investigate the role of CB1R in this process.

METHODS

CD4+ T lymphocytes were isolated from peripheral blood mononuclear cells (PBMCs) from male and female individuals at the onset of type 1 diabetes and from non-diabetic individuals, RNA was extracted and mRNA expression was analysed by real-time PCR. Single beta cell expression from donors with type 1 diabetes was obtained from data mining. Patient-derived human islets from male and female cadaveric donors were 3D-cultured in solubilised extracellular matrix gel in co-culture with the same donor PBMCs, and incubated with cytokines (IL-1β, TNF-α, IFN-γ) for 24-48 h in the presence of vehicle or increasing concentrations of the CB1R blocker JD-5037. Expression of CNR1 (encoding for CB1R) was ablated using CRISPR/Cas9 technology. Viability, intracellular stress and signalling were assayed by live-cell probing and real-time PCR. The islet function measured as glucose-stimulated insulin secretion was determined in a perifusion system. Infiltration of immune cells into the islets was monitored by microscopy. Non-obese diabetic mice aged 7 weeks were treated for 1 week with JD-5037, then euthanised. Profiling of immune cells infiltrated in the islets was performed by flow cytometry.

RESULTS

CNR1 expression was upregulated in circulating CD4+ T cells from individuals at type 1 diabetes onset (6.9-fold higher vs healthy individuals) and in sorted islet beta cells from donors with type 1 diabetes (3.6-fold higher vs healthy counterparts). The peripherally restricted CB1R inverse agonist JD-5037 arrested the initiation of insulitis in humans and mice. Mechanistically, CB1R blockade prevented islet NO production and ameliorated the ATF6 arm of the unfolded protein response. Consequently, cyto/chemokine expression decreased in human islets, leading to sustained islet cell viability and function.

CONCLUSIONS/INTERPRETATION

These results suggest that CB1R could be an interesting target for type 1 diabetes while highlighting the regulatory mechanisms of insulitis. Moreover, these findings may apply to type 2 diabetes where islet inflammation is also a pathophysiological factor.

DATA AVAILABILITY

Transcriptomic analysis of sorted human beta cells are from Gene Expression Omnibus database, accession no. GSE121863, available at https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSM3448161 .

Untangling the genetics of beta cell dysfunction and death in type 1 diabetes

BACKGROUND

Type 1 diabetes (T1D) is a complex multi-system disease which arises from both environmental and genetic factors, resulting in the destruction of insulin-producing pancreatic beta cells. Over the past two decades, human genetic studies have provided new insight into the etiology of T1D, including an appreciation for the role of beta cells in their own demise.

SCOPE OF REVIEW

Here, we outline models supported by human genetic data for the role of beta cell dysfunction and death in T1D. We highlight the importance of strong evidence linking T1D genetic associations to bona fide candidate genes for mechanistic and therapeutic consideration. To guide rigorous interpretation of genetic associations, we describe molecular profiling approaches, genomic resources, and disease models that may be used to construct variant-to-gene links and to investigate candidate genes and their role in T1D.

MAJOR CONCLUSIONS

We profile advances in understanding the genetic causes of beta cell dysfunction and death at individual T1D risk loci. We discuss how genetic risk prediction models can be used to address disease heterogeneity. Further, we present areas where investment will be critical for the future use of genetics to address open questions in the development of new treatment and prevention strategies for T1D.

Coxsackievirus B infection invokes unique cell-type specific responses in primary human pancreatic islets

Coxsackievirus B (CVB) infection has long been considered an environmental factor precipitating Type 1 diabetes (T1D), an autoimmune disease marked by loss of insulin-producing β cells within pancreatic islets. Previous studies have shown CVB infection negatively impacts islet function and viability but do not report on how virus infection individually affects the multiple cell types present in human primary islets. Therefore, we hypothesized that the various islet cell populations have unique transcriptional responses to CVB infection. Here, we performed single-cell RNA sequencing on human cadaveric islets treated with either CVB or poly(I:C), a viral mimic, for 24 and 48 hours. Our global analysis reveals CVB differentially induces dynamic transcriptional changes associated with multiple cell processes and functions over time whereas poly(I:C) promotes an immune response that progressively increases with treatment duration. At the single-cell resolution, we find CVB infects all islet cell types at similar rates yet induces unique cell-type specific transcriptional responses with β, α, and ductal cells having the strongest response. Sequencing and functional data suggest that CVB negatively impacts mitochondrial respiration and morphology in distinct ways in β and α cells, while also promoting the generation of reactive oxygen species. We also observe an increase in the expression of the long-noncoding RNA MIR7-3HG in β cells with high viral titers and reveal its knockdown reduces gene expression of viral proteins as well as apoptosis in stem cell-derived islets. Together, these findings demonstrate a cell-specific transcriptional, temporal, and functional response to CVB infection and provide new insights into the relationship between CVB infection and T1D.

A case of rapidly progressive insulin-dependent diabetes mellitus without islet autoantibodies developed over two years after the first dose of nivolumab

The case was an 80-year-old Japanese man. He was diagnosed with right renal cell carcinoma when he was 74. After laparoscopic radical nephrectomy, the patient received interferon, sorafenib, axitinib, and nivolumab therapy. The patient developed rapid progressive insulin-dependent diabetes mellitus (DM) after 46 courses of nivolumab monotherapy (772 days from the first nivolumab treatment). Glutamic acid decarboxylase antibody, islet cell cytoplasmic antibody, islet cell antigen-2 antibody, insulin antibody, and zinc transporter 8 antibody were all negative. Human leukocyte antigen (HLA) typing showed DRB1*09:01, DRB1 *13:02, DQB1*03:03, and DQB1 *06:04. Multiple daily insulin injections were started. However, controlling his blood glucose by standard multiple daily insulin injection treatments was difficult. The patient survived more than two years after the onset of immune checkpoint inhibitor-associated DM (ICI-DM). This is a valuable report of late-onset ICI-DM with a detailed patient background and clinical course over two years after the first dose of nivolumab.

Inhibition of the eukaryotic initiation factor-2α kinase PERK decreases risk of autoimmune diabetes in mice

Preventing the onset of autoimmune type 1 diabetes (T1D) is feasible through pharmacological interventions that target molecular stress-responsive mechanisms. Cellular stresses, such as nutrient deficiency, viral infection, or unfolded proteins, trigger the integrated stress response (ISR), which curtails protein synthesis by phosphorylating eukaryotic translation initiation factor-2α (eIF2α). In T1D, maladaptive unfolded protein response (UPR) in insulin-producing β cells renders these cells susceptible to autoimmunity. We found that inhibition of the eIF2α kinase PKR-like ER kinase (PERK), a common component of the UPR and ISR, reversed the mRNA translation block in stressed human islets and delayed the onset of diabetes, reduced islet inflammation, and preserved β cell mass in T1D-susceptible mice. Single-cell RNA-Seq of islets from PERK-inhibited mice showed reductions in the UPR and PERK signaling pathways and alterations in antigen-processing and presentation pathways in β cells. Spatial proteomics of islets from these mice showed an increase in the immune checkpoint protein programmed death-ligand 1 (PD-L1) in β cells. Golgi membrane protein 1, whose levels increased following PERK inhibition in human islets and EndoC-βH1 human β cells, interacted with and stabilized PD-L1. Collectively, our studies show that PERK activity enhances β cell immunogenicity and that inhibition of PERK may offer a strategy for preventing or delaying the development of T1D.

Beta cell dedifferentiation in type 1 diabetes: sacrificing function for survival?

The pathogeneses of type 1 and type 2 diabetes involve the progressive loss of functional beta cell mass, primarily attributed to cellular demise and/or dedifferentiation. While the scientific community has devoted significant attention to unraveling beta cell dedifferentiation in type 2 diabetes, its significance in type 1 diabetes remains relatively unexplored. This perspective article critically analyzes the existing evidence for beta cell dedifferentiation in type 1 diabetes, emphasizing its potential to reduce beta cell autoimmunity. Drawing from recent advancements in both human studies and animal models, we present beta cell identity as a promising target for managing type 1 diabetes. We posit that a better understanding of the mechanisms of beta cell dedifferentiation in type 1 diabetes is key to pioneering interventions that balance beta cell function and immunogenicity.

Human inherited PD-L1 deficiency is clinically and immunologically less severe than PD-1 deficiency

We previously reported two siblings with inherited PD-1 deficiency who died from autoimmune pneumonitis at 3 and 11 years of age after developing other autoimmune manifestations, including type 1 diabetes (T1D). We report here two siblings, aged 10 and 11 years, with neonatal-onset T1D (diagnosed at the ages of 1 day and 7 wk), who are homozygous for a splice-site variant of CD274 (encoding PD-L1). This variant results in the exclusive expression of an alternative, loss-of-function PD-L1 protein isoform in overexpression experiments and in the patients' primary leukocytes. Surprisingly, cytometric immunophenotyping and single-cell RNA sequencing analysis on blood leukocytes showed largely normal development and transcriptional profiles across lymphoid and myeloid subsets in the PD-L1-deficient siblings, contrasting with the extensive dysregulation of both lymphoid and myeloid leukocyte compartments in PD-1 deficiency. Our findings suggest that PD-1 and PD-L1 are essential for preventing early-onset T1D but that, unlike PD-1 deficiency, PD-L1 deficiency does not lead to fatal autoimmunity with extensive leukocytic dysregulation.

Inhibition of the Eukaryotic Initiation Factor-2-α Kinase PERK Decreases Risk of Autoimmune Diabetes in Mice

Preventing the onset of autoimmune type 1 diabetes (T1D) is feasible through pharmacological interventions that target molecular stress-responsive mechanisms. Cellular stresses, such as nutrient deficiency, viral infection, or unfolded proteins, trigger the integrated stress response (ISR), which curtails protein synthesis by phosphorylating eIF2α. In T1D, maladaptive unfolded protein response (UPR) in insulin-producing β cells renders these cells susceptible to autoimmunity. We show that inhibition of the eIF2α kinase PERK, a common component of the UPR and ISR, reverses the mRNA translation block in stressed human islets and delays the onset of diabetes, reduces islet inflammation, and preserves β cell mass in T1D-susceptible mice. Single-cell RNA sequencing of islets from PERK-inhibited mice shows reductions in the UPR and PERK signaling pathways and alterations in antigen processing and presentation pathways in β cells. Spatial proteomics of islets from these mice shows an increase in the immune checkpoint protein PD-L1 in β cells. Golgi membrane protein 1, whose levels increase following PERK inhibition in human islets and EndoC-βH1 human β cells, interacts with and stabilizes PD-L1. Collectively, our studies show that PERK activity enhances β cell immunogenicity, and inhibition of PERK may offer a strategy to prevent or delay the development of T1D.

Regulatory mechanisms of PD-1/PD-L1 in cancers

Immune evasion contributes to cancer growth and progression. Cancer cells have the ability to activate different immune checkpoint pathways that harbor immunosuppressive functions. The programmed death protein 1 (PD-1) and programmed cell death ligands (PD-Ls) are considered to be the major immune checkpoint molecules. The interaction of PD-1 and PD-L1 negatively regulates adaptive immune response mainly by inhibiting the activity of effector T cells while enhancing the function of immunosuppressive regulatory T cells (Tregs), largely contributing to the maintenance of immune homeostasis that prevents dysregulated immunity and harmful immune responses. However, cancer cells exploit the PD-1/PD-L1 axis to cause immune escape in cancer development and progression. Blockade of PD-1/PD-L1 by neutralizing antibodies restores T cells activity and enhances anti-tumor immunity, achieving remarkable success in cancer therapy. Therefore, the regulatory mechanisms of PD-1/PD-L1 in cancers have attracted an increasing attention. This article aims to provide a comprehensive review of the roles of the PD-1/PD-L1 signaling in human autoimmune diseases and cancers. We summarize all aspects of regulatory mechanisms underlying the expression and activity of PD-1 and PD-L1 in cancers, including genetic, epigenetic, post-transcriptional and post-translational regulatory mechanisms. In addition, we further summarize the progress in clinical research on the antitumor effects of targeting PD-1/PD-L1 antibodies alone and in combination with other therapeutic approaches, providing new strategies for finding new tumor markers and developing combined therapeutic approaches.

Interferons are key cytokines acting on pancreatic islets in type 1 diabetes

AIMS/HYPOTHESIS

The proinflammatory cytokines IFN-α, IFN-γ, IL-1β and TNF-α may contribute to innate and adaptive immune responses during insulitis in type 1 diabetes and therefore represent attractive therapeutic targets to protect beta cells. However, the specific role of each of these cytokines individually on pancreatic beta cells remains unknown.

METHODS

We used deep RNA-seq analysis, followed by extensive confirmation experiments based on reverse transcription-quantitative PCR (RT-qPCR), western blot, histology and use of siRNAs, to characterise the response of human pancreatic beta cells to each cytokine individually and compared the signatures obtained with those present in islets of individuals affected by type 1 diabetes.

RESULTS

IFN-α and IFN-γ had a greater impact on the beta cell transcriptome when compared with IL-1β and TNF-α. The IFN-induced gene signatures have a strong correlation with those observed in beta cells from individuals with type 1 diabetes, and the level of expression of specific IFN-stimulated genes is positively correlated with proteins present in islets of these individuals, regulating beta cell responses to 'danger signals' such as viral infections. Zinc finger NFX1-type containing 1 (ZNFX1), a double-stranded RNA sensor, was identified as highly induced by IFNs and shown to play a key role in the antiviral response in beta cells.

CONCLUSIONS/INTERPRETATION

These data suggest that IFN-α and IFN-γ are key cytokines at the islet level in human type 1 diabetes, contributing to the triggering and amplification of autoimmunity.

Kinetics of IFNγ-Induced Cytokines and Development of Immune-Related Adverse Events in Patients Receiving PD-(L)1 Inhibitors

Immune checkpoint inhibitors (ICI) have the potential to trigger unpredictable immune-related adverse events (irAEs), which can be severe. The underlying mechanisms of these events are not fully understood. As PD-L1 is upregulated by IFN, the heightened immune activation resulting from PD-1/PD-L1 inhibition may enhance the IFN response, triggering the expression of IFN-inducible genes and contributing to irAE development and its severity. In this study, we investigated the interplay between irAEs and the expression of IFN-inducible chemokines and cytokines in 134 consecutive patients with solid tumours treated with PD-(L)1 inhibitors as monotherapy or in combination with chemotherapy or other immunotherapy agents. We compared the plasma levels of IFN-associated cytokines (CXCL9/10/11, IL-18, IL-10, IL-6 and TGFβ) at various time points (at baseline, at the onset of irAE and previous to irAE onset) in three patient groups categorized by irAE development and severity: patients with serious irAEs, mild irAEs and without irAEs after PD-(L)1 inhibitors. No differences were observed between groups at baseline. However, patients with serious irAEs exhibited significant increases in CXCL9/10/11, IL-18 and IL-10 levels at the onset of the irAE compared to baseline. A network analysis and correlation patterns highlighted a robust relationship among these chemokines and cytokines at serious-irAE onset. Combining all of the analysed proteins in a cluster analysis, we identified a subgroup of patients with a higher incidence of serious irAEs affecting different organs or systems. Finally, an ROC analysis and a decision tree model proposed IL-18 levels ≥ 807 pg/mL and TGFβ levels ≤ 114 pg/mL as predictors for serious irAEs in 90% of cases. In conclusion, our study elucidates the dynamic changes in cytokine profiles associated with serious irAE development during treatment with PD-(L)1 inhibitors. The study's findings offer valuable insights into the intricate IFN-induced immune responses associated with irAEs and propose potential predictive markers for their severity.

Chimeric Antigen Receptor (CAR)-Based Cell Therapy for Type 1 Diabetes Mellitus (T1DM); Current Progress and Future Approaches

Type 1 diabetes mellitus (T1DM) is an autoimmune disease that destroys insulin-producing pancreatic β-cells. Insulin replacement therapy is currently the mainstay of treatment for T1DM; however, treatment with insulin does not ameliorate disease progression, as dysregulated immune response and inflammation continue to cause further pancreatic β-cell degradation. Therefore, shifting therapeutic strategies toward immunomodulating approaches could be effective to prevent and reverse disease progression. Different immune-modulatory therapies could be used, e.g., monoclonal-based immunotherapy, mesenchymal stem cell, and immune cell therapy. Since immune-modulatory approaches could have a systemic effect on the immune system and cause toxicity, more specific treatment options should target the immune response against pancreatic β-cells. In this regard, chimeric antigen receptor (CAR)-based immunotherapy could be a promising candidate for modulation of dysregulated immune function in T1DM. CAR-based therapy has previously been approved for a number of hematologic malignancies. Nevertheless, there is renewed interest in CAR T cells' " off-the-shelf " treatment for T1DM. Several pre-clinical studies demonstrated that redirecting antigen-specific CAR T cells, especially regulatory CAR T cells (CAR Tregs), toward the pancreatic β-cells, could prevent diabetes onset and progression in diabetic mice models. Here, we aim to review the current progress of CAR-based immune-cell therapy for T1DM and the corresponding challenges, with a special focus on designing CAR-based immunomodulatory strategies to improve its efficacy in the treatment of T1DM.

Induction of islet autoimmunity to defective ribosomal product of the insulin gene as neoantigen after anti-cancer immunotherapy leading to autoimmune diabetes

Introduction

The autoimmune response in type 1 diabetes (T1D), in which the beta cells expressing aberrant or modified proteins are killed, resembles an effective antitumor response. Defective ribosomal protein products in tumors are targets of the anti-tumor immune response that is unleashed by immune checkpoint inhibitor (ICI) treatment in cancer patients. We recently described a defective ribosomal product of the insulin gene (INS-DRiP) that is expressed in stressed beta cells and targeted by diabetogenic T cells. T1D patient-derived INS-DRiP specific T cells can kill beta cells and are present in the insulitic lesion. T cells reactive to INS-DRiP epitopes are part of the normal T cell repertoire and are believed to be kept in check by immune regulation without causing autoimmunity.

Method

T cell autoreactivity was tested using a combinatorial HLA multimer technology measuring a range of epitopes of islet autoantigens and neoantigen INS-DRiP. INS-DRiP expression in human pancreas and insulinoma sections was tested by immunohistochemistry.

Results

Here we report the induction of islet autoimmunity to INS-DRiP and diabetes after ICI treatment and successful tumor remission. Following ICI treatment, T cells of the cancer patient were primed against INS-DRiP among other diabetogenic antigens, while there was no sign of autoimmunity to this neoantigen before ICI treatment. Next, we demonstrated the expression of INS-DRiP as neoantigen in both pancreatic islets and insulinoma by staining with a monoclonal antibody to INS-DRiP.

Discussion

These results bridge cancer and T1D as two sides of the same coin and point to neoantigen expression in normal islets and insulinoma that may serve as target of both islet autoimmunity and tumor-related autoimmunity.

Insulitis in human type 1 diabetes: lessons from an enigmatic lesion

Type 1 diabetes is caused by a deficiency of insulin secretion which has been considered traditionally as the outcome of a precipitous decline in the viability of β-cells in the islets of Langerhans, brought about by autoimmune-mediated attack. Consistent with this, various classes of lymphocyte, as well as cells of the innate immune system have been found in association with islets during disease progression. However, analysis of human pancreas from subjects with type 1 diabetes has revealed that insulitis is often less intense than in equivalent animal models of the disease and can affect many fewer islets than expected, at disease onset. This is especially true in subjects developing type 1 diabetes in, or beyond, their teenage years. Such studies imply that both the phenotype and the number of immune cells present within insulitic lesions can vary among individuals in an age-dependent manner. Additionally, the influent lymphocytes are often mainly arrayed peripherally around islets rather than gaining direct access to the endocrine cell core. Thus, insulitis remains an enigmatic phenomenon in human pancreas and this review seeks to explore the current understanding of its likely role in the progression of type 1 diabetes.

Relationship between CD274 gene polymorphism and systemic lupus erythematosus risk in a Chinese Han population

OBJECTIVE

Relationship between surface antigen differentiation cluster 274 (CD274) gene polymorphism and systemic lupus erythematosus (SLE) risk is limited. This study aims to discuss whether in a Chinese Han population, CD274 gene polymorphisms may relate to SLE susceptibility.

METHODS

Three hundred and ten SLE patients and 390 healthy controls were included in this case-control study. Using the Kompetitive Allele-Specific PCR (KASP) approach, five single nucleotide polymorphisms (SNPs), including rs2890658, rs4143815, rs822339, rs2282055, and rs2297137, were genotyped for CD274 gene polymorphisms. Correlation between the polymorphisms and clinical, laboratory features in SLE patients were discussed.

RESULTS

Frequency of C allele was substantially lower in SLE patients than in healthy controls (p = .015), and CC genotype was significantly negatively related to developing SLE at locus rs4143815 (p = .013). At locus rs822339, frequency of GA genotype was higher than that of the healthy controls (p = .006). At locus rs2282055, frequency of GG genotype was lower than that of healthy controls (p = .024). According to subgroup analysis, the CD274 gene polymorphisms rs2890658, rs4143815, rs822339, rs2282055, and rs2297137 were partly linked to some clinical symptoms of SLE patients, such as Complement 4 (C4), C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR).

CONCLUSION

CD274 gene polymorphisms may be susceptible to SLE in the Chinese Han people.

Life-Threatening Endocrinological Immune-Related Adverse Events of Immune Checkpoint Inhibitor Therapy

Malignant neoplasms are currently one of the leading causes of morbidity and mortality worldwide, posing a major public health challenge. However, recent advances in research in cancer biology and immunity have led to the development of immunotherapy, which is now used on an everyday basis in cancer treatment in addition to surgical treatment, classical cytostatics, and radiotherapy. The efficacy of immunotherapy has promoted the great popularity of this treatment among patients, as well as significant research interest. The increasing number of patients being treated with immunotherapy not only reassures physicians of the efficacy of this technique but also shows the wide spectrum of side effects of this therapy, which has not been considered before. Immune-related adverse events may affect many systems and organs, such as digestive, cardiovascular, respiratory, skin, or endocrine organs. Most complications have a mild or moderate course, but there are life-threatening manifestations that are essential to be aware of because if they are not properly diagnosed and treated on time, they can have fatal consequences. The purpose of this paper was to present the results of a literature review on the current state of knowledge on life-threatening endocrine side effects (such as adrenal crisis, thyroid storm, myxoedema crisis, diabetic ketoacidosis, and severe hypocalcaemia) of immune checkpoint inhibitors to provide information on symptoms, diagnostics, and management strategies.

The beta cell-immune cell interface in type 1 diabetes (T1D)

BACKGROUND

T1D is an autoimmune disease in which pancreatic islets of Langerhans are infiltrated by immune cells resulting in the specific destruction of insulin-producing islet beta cells. Our understanding of the factors leading to islet infiltration and the interplay of the immune cells with target beta cells is incomplete, especially in human disease. While murine models of T1D have provided crucial information for both beta cell and autoimmune cell function, the translation of successful therapies in the murine model to human disease has been a challenge.

SCOPE OF REVIEW

Here, we discuss current state of the art and consider knowledge gaps concerning the interface of the islet beta cell with immune infiltrates, with a focus on T cells. We discuss pancreatic and immune cell phenotypes and their impact on cell function in health and disease, which we deem important to investigate further to attain a more comprehensive understanding of human T1D disease etiology.

MAJOR CONCLUSIONS

The last years have seen accelerated development of approaches that allow comprehensive study of human T1D. Critically, recent studies have contributed to our revised understanding that the pancreatic beta cell assumes an active role, rather than a passive position, during autoimmune disease progression. The T cell-beta cell interface is a critical axis that dictates beta cell fate and shapes autoimmune responses. This includes the state of the beta cell after processing internal and external cues (e.g., stress, inflammation, genetic risk) that that contributes to the breaking of tolerance by hyperexpression of human leukocyte antigen (HLA) class I with presentation of native and neoepitopes and secretion of chemotactic factors to attract immune cells. We anticipate that emerging insights about the molecular and cellular aspects of disease initiation and progression processes will catalyze the development of novel and innovative intervention points to provide additional therapies to individuals affected by T1D.

Immune-Checkpoint Inhibitors-Induced Type 1 Diabetes Mellitus: From Its Molecular Mechanisms to Clinical Practice

With the increasing use of immune-checkpoint inhibitors (ICIs), such as anti-cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) and anti-programmed cell death-1 (PD-1), for the treatment of malignancies, cases of ICI-induced type 1 diabetes mellitus (ICI-T1DM) have been reported globally. This review focuses on the features and pathogenesis of this disease. T1DM is an immune-related adverse event that occurs following the administration of anti-PD-1 or anti-programmed death ligand-1 (PDL1) alone or in combination with anti-CTLA-4. More than half of the reported cases presented as abrupt-onset diabetic ketoacidosis. The primary mechanism of ICI-T1DM is T-cell stimulation, which results from the loss of interaction between PD-1 and PD-L1 in pancreatic islet. The similarities and differences between ICI-T1DM and classical T1DM may provide insights into this disease entity. ICI-T1DM is a rare but often life-threatening medical emergency that healthcare professionals and patients need to be aware of. Early detection of and screening for this disease is imperative. At present, the only known treatment for ICI-T1DM is insulin injection. Further research into the mechanisms and risk factors associated with ICI-T1DM development may contribute to a better understanding of this disease entity and the identification of possible preventive strategies.

IFNɣ but not IFNα increases recognition of insulin defective ribosomal product-derived antigen to amplify islet autoimmunity

AIMS/HYPOTHESIS

The inflammatory milieu characteristic of insulitis affects translation fidelity and generates defective ribosomal products (DRiPs) that participate in autoimmune beta cell destruction in type 1 diabetes. Here, we studied the role of early innate cytokines (IFNα) and late immune adaptive events (IFNɣ) in insulin DRiP-derived peptide presentation to diabetogenic CD8+ T cells.

METHODS

Single-cell transcriptomics of human pancreatic islets was used to study the composition of the (immuno)proteasome. Specific inhibition of the immunoproteasome catalytic subunits was achieved using siRNA, and antigenic peptide presentation at the cell surface of the human beta cell line EndoC-βH1 was monitored using peptide-specific CD8 T cells.

RESULTS

We found that IFNγ induces the expression of the PSMB10 transcript encoding the β2i catalytic subunit of the immunoproteasome in endocrine beta cells, revealing a critical role in insulin DRiP-derived peptide presentation to T cells. Moreover, we showed that PSMB10 is upregulated in a beta cell subset that is preferentially destroyed in the pancreases of individuals with type 1 diabetes.

CONCLUSIONS/INTERPRETATION

Our data highlight the role of the degradation machinery in beta cell immunogenicity and emphasise the need for evaluation of targeted immunoproteasome inhibitors to limit beta cell destruction in type 1 diabetes.

DATA AVAILABILITY

The single-cell RNA-seq dataset is available from the Gene Expression Omnibus (GEO) using the accession number GSE218316 ( https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE218316 ).

The role of the interferon/JAK-STAT axis in driving islet HLA-I hyperexpression in type 1 diabetes

The hyperexpression of human leukocyte antigen class I (HLA-I) molecules on pancreatic beta-cells is widely accepted as a hallmark feature of type 1 diabetes pathogenesis. This response is important clinically since it may increase the visibility of beta-cells to autoreactive CD8+ T-cells, thereby accelerating disease progression. In this review, key factors which drive HLA-I hyperexpression will be explored, and their clinical significance examined. It is established that the presence of residual beta-cells is essential for HLA-I hyperexpression by islet cells at all stages of the disease. We suggest that the most likely drivers of this process are interferons released from beta-cells (type I or III interferon; possibly in response to viral infection) or those elaborated from influent, autoreactive immune cells (type II interferon). In both cases, Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STAT) pathways will be activated to induce the downstream expression of interferon stimulated genes. A variety of models have highlighted that HLA-I expression is enhanced in beta-cells in response to interferons, and that STAT1, STAT2 and interferon regulatory factor 9 (IRF9) play key roles in mediating these effects (depending on the species of interferon involved). Importantly, STAT1 expression is elevated in the beta-cells of donors with recent-onset type I diabetes, and this correlates with HLA-I hyperexpression on an islet-by-islet basis. These responses can be replicated in vitro, and we consider that chronically elevated STAT1 may have a role in maintaining HLA-I hyperexpression. However, other data have highlighted that STAT2-IRF9 may also be critical to this process. Thus, a better understanding of how these factors regulate HLA-I under chronically stimulated conditions needs to be gathered. Finally, JAK inhibitors can target interferon signaling pathways to diminish HLA-I expression in mouse models. It seems probable that these agents may also be effective in patients; diminishing HLA-I hyperexpression on islets, reducing the visibility of beta-cells to the immune system and ultimately slowing disease progression. The first clinical trials of selective JAK inhibitors are underway, and the outcomes should have important implications for type 1 diabetes clinical management.

Deucravacitinib, a tyrosine kinase 2 pseudokinase inhibitor, protects human EndoC-βH1 β-cells against proinflammatory insults

Introduction

Type 1 diabetes is characterized by pancreatic islet inflammation and autoimmune-driven pancreatic β-cell destruction. Interferon-α (IFNα) is a key player in early human type 1 diabetes pathogenesis. IFNα activates the tyrosine kinase 2 (TYK2)-signal transducer and activator of transcription (STAT) pathway, leading to inflammation, HLA class I overexpression, endoplasmic reticulum (ER) stress, and β-cell apoptosis (in synergy with IL-1β). As TYK2 inhibition has raised as a potential therapeutic target for the prevention or treatment of type 1 diabetes, we investigated whether the selective TYK2 inhibitor deucravacitinib could protect β-cells from the effects of IFNα and other proinflammatory cytokines (i.e., IFNγ and IL-1β).

Methods

All experiments were performed in the human EndoC-βH1 β-cell line. HLA class I expression, inflammation, and ER stress were evaluated by real-time PCR, immunoblotting, and/or immunofluorescence. Apoptosis was assessed by the DNA-binding dyes Hoechst 33342 and propidium iodide or caspase 3/7 activity. The promoter activity was assessed by luciferase assay.

Results

Deucravacitinib prevented IFNα effects, such as STAT1 and STAT2 activation and MHC class I hyperexpression, in a dose-dependent manner without affecting β-cell survival and function. A comparison between deucravacitinib and two Janus kinase inhibitors, ruxolitinib and baricitinib, showed that deucravacitinib blocked IFNα- but not IFNγ-induced signaling pathway. Deucravacitinib protected β-cells from the effects of two different combinations of cytokines: IFNα + IL-1β and IFNγ + IL-1β. Moreover, this TYK2 inhibitor could partially reduce apoptosis and inflammation in cells pre-treated with IFNα + IL-1β or IFNγ + IL-1β.

Discussion

Our findings suggest that, by protecting β-cells against the deleterious effects of proinflammatory cytokines without affecting β-cell function and survival, deucravacitinib could be repurposed for the prevention or treatment of early type 1 diabetes.

Interferon-α promotes neo-antigen formation and preferential HLA-B-restricted antigen presentation in pancreatic β-cells

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 we identified islet-infiltrating CD8+ T-cells from T1D donors reactive to 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.

The pathogenic "symphony" in type 1 diabetes: A disorder of the immune system, β cells, and exocrine pancreas

Type 1 diabetes (T1D) is widely considered to result from the autoimmune destruction of insulin-producing β cells. This concept has been a central tenet for decades of attempts seeking to decipher the disorder's pathogenesis and prevent/reverse the disease. Recently, this and many other disease-related notions have come under increasing question, particularly given knowledge gained from analyses of human T1D pancreas. Perhaps most crucial are findings suggesting that a collective of cellular constituents-immune, endocrine, and exocrine in origin-mechanistically coalesce to facilitate T1D. This review considers these emerging concepts, from basic science to clinical research, and identifies several key remaining knowledge voids.

Effects of Lactobacilli acidophilus and/or spiramycin as an adjunct in toxoplasmosis infection challenged with diabetes

The current study assessed the anti-parasitic impact of probiotics on Toxoplasma gondii infection either solely or challenged with diabetes in Swiss albino mice. The study design encompassed group-A (diabetic), group-B (non-diabetic), and healthy controls (C). Each group was divided into infected-untreated (subgroup-1); infected and spiramycin-treated (subgroup-2); infected and probiotic-treated (subgroup-3); infected and spiramycin+ probiotic-treated (subgroup-4). Diabetic-untreated animals exhibited acute toxoplasmosis and higher cerebral parasite load. Overall, various treatments reduced intestinal pathology, improved body weight, and decreased mortalities; nevertheless, probiotic + spiramycin exhibited significant differences. On day 7 post-infection both PD-1 and IL-17A demonstrated higher scores in the intestine of diabetic-untreated mice compared with non-diabetics and healthy control; whereas, claudin-1 revealed worsening expression. Likewise, on day 104 post-infection cerebral PD-1 and IL-17A showed increased expressions in diabetic animals. Overall, treatment modalities revealed lower scores of PD-1 and IL-17A in non-diabetic subgroups compared with diabetics. Intestinal and cerebral expressions of IL-17A and PD-1 demonstrated positive correlations with cerebral parasite load. In conclusion, toxoplasmosis when challenged with diabetes showed massive pathological features and higher parasite load in the cerebral tissues. Probiotics are a promising adjunct to spiramycin by ameliorating IL-17A and PD-1 in the intestinal and cerebral tissues, improving the intestinal expression of claudin-1, and efficiently reducing the cerebral parasite load.

Tryptophan metabolism promotes immune evasion in human pancreatic β cells

BACKGROUND

To resist the autoimmune attack characteristic of type 1 diabetes, insulin producing pancreatic β cells need to evade T-cell recognition. Such escape mechanisms may be conferred by low HLA class I (HLA-I) expression and upregulation of immune inhibitory molecules such as Programmed cell Death Ligand 1 (PD-L1).

METHODS

The expression of PD-L1, HLA-I and CXCL10 was evaluated in the human β cell line, ECN90, and in primary human and mouse pancreatic islets. Most genes were determined by real-time RT-PCR, flow cytometry and Western blot. Activator and inhibitor of the AKT signaling were used to modulate PD-L1 induction. Key results were validated by monitoring activity of CD8+ Jurkat T cells presenting β cell specific T-cell receptor and transduced with reporter genes in contact culture with the human β cell line, ECN90.

FINDINGS

In this study, we identify tryptophan (TRP) as an agonist of PD-L1 induction through the AKT signaling pathway. TRP also synergistically enhanced PD-L1 expression on β cells exposed to interferon-γ. Conversely, interferon-γ-mediated induction of HLA-I and CXCL10 genes was down-regulated upon TRP treatment. Finally, TRP and its derivatives inhibited the activation of islet-reactive CD8+ T cells by β cells.

INTERPRETATION

Collectively, our findings indicate that TRP could induce immune tolerance to β cells by promoting their immune evasion through HLA-I downregulation and PD-L1 upregulation.

FUNDING

Dutch Diabetes Research Foundation, DON Foundation, the Laboratoire d'Excellence consortium Revive (ANR-10-LABX-0073), Agence Nationale de la Recherche (ANR-19-CE15-0014-01), Fondation pour la Recherche Médicale (EQ U201903007793-EQU20193007831), Innovative Medicines InitiativeINNODIA and INNODIA HARVEST, Aides aux Jeunes Diabetiques (AJD) and Juvenile Diabetes Research Foundation Ltd (JDRF).

Single cell transcriptomic analysis of Graves' disease thyroid glands reveals the broad immunoregulatory potential of thyroid follicular and stromal cells and implies a major re-interpretation of the role of aberrant HLA class II expression in autoimmunity

The study of the immune response in thyroid autoimmunity has been mostly focused on the autoantibodies and lymphocytes, but there are indications that intrinsic features of thyroid tissue cells may play a role in disrupting tolerance that needs further investigation. The overexpression of HLA and adhesion molecules by thyroid follicular cells (TFC) and our recent demonstration that PD-L1 is also moderately expressed by TFCs in autoimmune thyroid indicates that TFCs they may activate but also inhibit the autoimmune response. Intriguingly, we have recently found that in vitro cultured TFCs are able to suppress the proliferation of autologous lymphocyte T in a contact-dependent manner which is independent of the PD-1/PD-L1 signaling pathway. To get a more comprehensive picture of TFC activating and inhibitory molecules/pathways driving the autoimmune response in the thyroid glands, preparations of TFCs and stromal cells from five Graves' disease (GD) and four control thyroid glands were compared by scRNA-seq. The results confirmed the previously described interferon type I and type II signatures in GD TFCs and showed unequivocally that they express the full array of genes that intervene in the processing and presentation of endogenous and exogeneous antigens. GD TFCs lack however expression of costimulatory molecules CD80 and CD86 required for priming T cells. A moderate overexpression of CD40 by TFCs was confirmed. GD Fibroblasts showed widespread upregulation of cytokine genes. The results from this first single transcriptomic profiling of TFC and thyroid stromal cells provides a more granular view of the events occurring in GD. The new data point at an important contribution of stromal cells and prompt a major re-interpretation of the role of MHC over-expression by TFC, from deleterious to protective. Most importantly this re-interpretation could also apply to other tissues, like pancreatic beta cells, where MHC over-expression has been detected in diabetic pancreas.

Immune engineered extracellular vesicles to modulate T cell activation in the context of type 1 diabetes

Extracellular vesicles (EVs) can affect immune responses through antigen presentation and costimulation or coinhibition. We generated designer EVs to modulate T cells in the context of type 1 diabetes, a T cell-mediated autoimmune disease, by engineering a lymphoblast cell line, K562, to express HLA-A*02 (HLA-A2) alongside costimulatory CD80 and/or coinhibitory programmed death ligand 1 (PD-L1). EVs presenting HLA-A2 and CD80 activated CD8+ T cells in a dose, antigen, and HLA-specific manner. Adding PD-L1 to these EVs produced an immunoregulatory response, reducing CD8+ T cell activation and cytotoxicity in vitro. EVs alone could not stimulate T cells without antigen-presenting cells. EVs lacking CD80 were ineffective at modulating CD8+ T cell activation, suggesting that both peptide-HLA complex and costimulation are required for EV-mediated immune modulation. These results provide mechanistic insight into the rational design of EVs as a cell-free approach to immunotherapy that can be tailored to promote inflammatory or tolerogenic immune responses.

The extent and magnitude of islet T cell infiltration as powerful tools to define the progression to type 1 diabetes

AIMS/HYPOTHESIS

Insulitis is not present in all islets, and it is elusive in humans. Although earlier studies focused on islets that fulfilled certain criteria (e.g. ≥15 CD45+ cells or ≥6 CD3+ cells), there is a fundamental lack of understanding of the infiltration dynamics in terms of its magnitude (i.e. how much) and extent (i.e. where). Here, we aimed to perform an in-depth characterisation of T cell infiltration by investigating islets with moderate (1-5 CD3+ cells) and high (≥6 CD3+ cells) infiltration in individuals with and without type 1 diabetes.

METHODS

Pancreatic tissue sections from 15 non-diabetic, eight double autoantibody-positive and ten type 1 diabetic (0-2 years of disease duration) organ donors were obtained from the Network for Pancreatic Organ Donors with Diabetes, and stained for insulin, glucagon, CD3 and CD8 by immunofluorescence. T cell infiltration was quantified in a total of 8661 islets using the software QuPath. The percentage of infiltrated islets and islet T cell density were calculated. To help standardise the analysis of T cell infiltration, we used cell density data to develop a new T cell density threshold capable of differentiating non-diabetic and type 1 diabetic donors.

RESULTS

Our analysis revealed that 17.1% of islets in non-diabetic donors, 33% of islets in autoantibody-positive and 32.5% of islets in type 1 diabetic donors were infiltrated by 1 to 5 CD3+ cells. Islets infiltrated by ≥6 CD3+ cells were rare in non-diabetic donors (0.4%) but could be found in autoantibody-positive (4.5%) and type 1 diabetic donors (8.2%). CD8+ and CD8- populations followed similar patterns. Likewise, T cell density was significantly higher in the islets of autoantibody-positive donors (55.4 CD3+ cells/mm2) and type 1 diabetic donors (74.8 CD3+ cells/mm2) compared with non-diabetic individuals (17.3 CD3+ cells/mm2), which was accompanied by higher exocrine T cell density in type 1 diabetic individuals. Furthermore, we showed that the analysis of a minimum of 30 islets and the use of a reference mean value for T cell density of 30 CD3+ cells/mm2 (the 30-30 rule) can differentiate between non-diabetic and type 1 diabetic donors with high specificity and sensitivity. In addition, it can classify autoantibody-positive individuals as non-diabetic or type 1 diabetic-like.

CONCLUSIONS/INTERPRETATION

Our data indicates that the proportion of infiltrated islets and T cell density change dramatically during the course of type 1 diabetes, and these changes can be already observed in double autoantibody-positive individuals. This suggests that, as disease progresses, T cell infiltration extends throughout the pancreas, reaching the islets and exocrine compartment. While it predominantly targets insulin-containing islets, large accumulations of cells are rare. Our study fulfils the need to further understand T cell infiltration, not only after diagnosis but also in individuals with diabetes-related autoantibodies. Furthermore, the development and application of new analytical tools based on T cell infiltration, like the 30-30 rule, will allow us to correlate islet infiltration with demographic and clinical variables with the aim of identifying individuals at the very early stages of the disease.

Inflammation versus regulation: how interferon-gamma contributes to type 1 diabetes pathogenesis

Type 1 diabetes is an autoimmune disease with onset from early childhood. The insulin-producing pancreatic beta cells are destroyed by CD8⁺ cytotoxic T cells. The disease is challenging to study mechanistically in humans because it is not possible to biopsy the pancreatic islets and the disease is most active prior to the time of clinical diagnosis. The NOD mouse model, with many similarities to, but also some significant differences from human diabetes, provides an opportunity, in a single in-bred genotype, to explore pathogenic mechanisms in molecular detail. The pleiotropic cytokine IFN-γ is believed to contribute to pathogenesis of type 1 diabetes. Evidence of IFN-γ signaling in the islets, including activation of the JAK-STAT pathway and upregulation of MHC class I, are hallmarks of the disease. IFN-γ has a proinflammatory role that is important for homing of autoreactive T cells into islets and direct recognition of beta cells by CD8⁺ T cells. We recently showed that IFN-γ also controls proliferation of autoreactive T cells. Therefore, inhibition of IFN-γ does not prevent type 1 diabetes and is unlikely to be a good therapeutic target. In this manuscript we review the contrasting roles of IFN-γ in driving inflammation and regulating the number of antigen specific CD8⁺ T cells in type 1 diabetes. We also discuss the potential to use JAK inhibitors as therapy for type 1 diabetes, to inhibit both cytokine-mediated inflammation and proliferation of T cells.

A Concerted Vision to Advance the Knowledge of Diabetes Mellitus Related to Immune Checkpoint Inhibitors

The rubric of immune-related (ir) diabetes mellitus (DM) (irDM) encompasses various hyperglycemic disorders related to immune checkpoint inhibitors (ICPis). Beyond sharing similarities with conventional DM, irDM is a distinct, yet important, entity. The present narrative review provides a comprehensive overview of the literature regarding irDM published in major databases from January 2018 until January 2023. Initially considered rare, irDM is increasingly being reported. To advance the knowledge of irDM, the present review suggests a concerted vision comprising two intertwined aspects: a scientific-centered and a patient-centered view. The scientific-centered aspect addresses the pathophysiology of irDM, integrating: (i) ICPi-induced pancreatic islet autoimmunity in genetically predisposed patients; (ii) altered gut microbiome; (iii) involvement of exocrine pancreas; (iv) immune-related acquired generalized lipodystrophy. The patient-centered aspect is both nurtured by and nurturing the four pillars of the scientific-centered aspect: awareness, diagnosis, treatment, and monitoring of irDM. The path forward is a multidisciplinary initiative towards: (i) improved characterization of the epidemiological, clinical, and immunological profile of irDM; (ii) standardization of reporting, management, and surveillance protocols for irDM leveraging global registries; (iii) patient stratification according to personalized risk for irDM; (iv) new treatments for irDM; and (v) uncoupling ICPi efficacy from immunotoxicity.

Autoimmunity and Carcinogenesis: Their Relationship under the Umbrella of Autophagy

The immune system and autophagy share a functional relationship. Both innate and adaptive immune responses involve autophagy and, depending on the disease’s origin and pathophysiology, it may have a detrimental or positive role on autoimmune disorders. As a “double-edged sword” in tumors, autophagy can either facilitate or impede tumor growth. The autophagy regulatory network that influences tumor progression and treatment resistance is dependent on cell and tissue types and tumor stages. The connection between autoimmunity and carcinogenesis has not been sufficiently explored in past studies. As a crucial mechanism between the two phenomena, autophagy may play a substantial role, though the specifics remain unclear. Several autophagy modifiers have demonstrated beneficial effects in models of autoimmune disease, emphasizing their therapeutic potential as treatments for autoimmune disorders. The function of autophagy in the tumor microenvironment and immune cells is the subject of intensive study. The objective of this review is to investigate the role of autophagy in the simultaneous genesis of autoimmunity and malignancy, shedding light on both sides of the issue. We believe our work will assist in the organization of current understanding in the field and promote additional research on this urgent and crucial topic.

Endocrine Dysfunction From Immune Checkpoint Inhibitors: Pearls and Pitfalls in Evaluation and Management

Immune checkpoint inhibitors (ICPis) have proven extremely efficacious in cancer therapy but also lead to a plethora of immune-related adverse events (irAEs). The endocrine irAEs are not only quite common but also may pose a challenge to the clinician while managing a patient with cancer treated with ICPis. The clinical features of endocrine dysfunction are usually nonspecific and may overlap with concurrent illnesses, underlying the importance of accurate hormone testing and efforts toward case-finding. The management of endocrine irAEs is unique in the focus being on hormone replacement rather than curtailing the autoimmune process. Although the management of thyroid irAEs appears straightforward, adrenal insufficiency and insulin-dependent diabetes can be life-threatening if not promptly recognized and treated. This clinical review synthesizes the studies to provide pearls and pitfalls in the evaluation and management of endocrine irAEs with specific reference to guidelines from oncologic societies.

Inflammatory Cell Infiltration Into Islets Without PD-L1 Expression Is Associated With the Development of Immune Checkpoint Inhibitor-Related Type 1 Diabetes in Genetically Susceptible Patients

Immune checkpoint inhibitors (ICIs) could cause type 1 diabetes (T1D). However, the underlying mechanism remains unclear. We immunohistochemically analyzed pancreatic specimens from three individuals with ICI-related T1D, and their histopathological data were compared those from three patients who had received ICI therapy but did not develop T1D (non-T1D) and seven normal glucose-tolerant subjects as control subjects. All ICI-related T1D patients had susceptible HLA haplotypes. In ICI-related T1D, the β-cell area decreased and the α-cell area increased compared with non-T1D and control subjects. The number of CD3-positive cells around islets increased in ICI-related T1D and non-T1D compared with control subjects, while the number of CD68-positive cells around islets increased in ICI-related T1D compared with non-T1D and control subjects. The expression ratios of programmed death-ligand 1 (PD-L1) on islets decreased in non-T1D and almost completely disappeared in ICI-related T1D, while PD-L1 expression was observed in most cells of pancreatic islets in control subjects. This study, therefore, indicates that ICI therapy itself could reduce PD-L1 expression on islets in all subjects, which may be related to β-cell vulnerability. In addition, we showed that absence of PD-L1 expression on β-cells, genetic susceptibility, and infiltration of macrophages as well as T lymphocytes around islets might be responsible for T1D onset.

Interferon-α2a induces CD4+ T cell apoptosis and suppresses Th1/Th17 responses via upregulating IRF1-mediated PDL1 expression in dendritic cells from Behcet's uveitis

Recombinant interferon-α2a (IFNα2a) has been widely used in the treatment of Behcet's uveitis (BU). However, the mechanism underlying its effects remains poorly understood. In this study, we investigated its effect on dendritic cells (DCs) and CD4⁺ T cells, which are essential for the development of BU. Our results showed that the expression of PDL1 and IRF1 was significantly decreased in DCs from active BU patients, and IFNα2a could significantly upregulate PDL1 expression in an IRF1-dependent manner. IFNα2a-treated DCs induced CD4⁺ T cells apoptosis and inhibited the Th1/Th17 immune response in association with reduced secretion of IFN-γ and IL-17. We also found that IFNα2a promoted Th1 cell differentiation and IL-10 secretion by CD4⁺ T cells. Finally, a comparison of patients before and after IFNα2a therapy revealed that the frequencies of Th1/Th17 cells significantly decreased in association with remission of uveitis after IFNα2a therapy. Collectively, these results show that IFNα2a could exert its effects by modulating the function of DCs and CD4⁺ T cells in BU.

Redox Regulation of m 6 A Methyltransferase METTL3 in Human β-cells Controls the Innate Immune Response in Type 1 Diabetes

Type 1 Diabetes (T1D) is characterized by autoimmune-mediated destruction of insulin-producing β-cells. Several observations have renewed interest in the innate immune system as an initiator of the disease process against β-cells. Here, we show that N 6 -Methyladenosine (m 6 A) is an adaptive β-cell safeguard mechanism that accelerates mRNA decay of the 2'-5'-oligoadenylate synthetase (OAS) genes to control the antiviral innate immune response at T1D onset. m 6 A writer methyltransferase 3 (METTL3) levels increase drastically in human and mouse β-cells at T1D onset but rapidly decline with disease progression. Treatment of human islets and EndoC-βH1 cells with pro-inflammatory cytokines interleukin-1 β and interferon α mimicked the METTL3 upregulation seen at T1D onset. Furthermore, m 6 A-sequencing revealed the m 6 A hypermethylation of several key innate immune mediators including OAS1, OAS2, and OAS3 in human islets and EndoC-βH1 cells challenged with cytokines. METTL3 silencing in human pseudoislets or EndoC-βH1 cells enhanced OAS levels by increasing its mRNA stability upon cytokine challenge. Consistently, in vivo gene therapy, to prolong Mettl3 overexpression specifically in β-cells, delayed diabetes progression in the non-obese diabetic (NOD) mouse model of T1D by limiting the upregulation of Oas pointing to potential therapeutic relevance. Mechanistically, the accumulation of reactive oxygen species blocked METTL3 upregulation in response to cytokines, while physiological levels of nitric oxide promoted its expression in human islets. Furthermore, for the first time to our knowledge, we show that the cysteines in position C276 and C326 in the zinc finger domain of the METTL3 protein are sensitive to S-nitrosylation (SNO) and are significant for the METTL3 mediated regulation of OAS mRNA stability in human β-cells in response to cytokines. Collectively, we report that m 6 A regulates human and mouse β-cells to control the innate immune response during the onset of T1D and propose targeting METTL3 to prevent β-cell death in T1D.

An Early Islet Transcriptional Signature Is Associated With Local Inflammation in Autoimmune Diabetes

Identifying the early islet cellular processes of autoimmune type 1 diabetes (T1D) in humans is challenging given the absence of symptoms during this period and the inaccessibility of the pancreas for sampling. In this article, we study temporal events in pancreatic islets in LEW.1WR1 rats, in which autoimmune diabetes can be induced with virus infection, by performing transcriptional analysis of islets harvested during the prediabetic period. Single-cell RNA-sequencing and differential expression analyses of islets from prediabetic rats reveal subsets of β- and α-cells under stress as evidenced by heightened expression, over time, of a transcriptional signature characterized by interferon-stimulated genes, chemokines including Cxcl10, major histocompatibility class I, and genes for the ubiquitin-proteasome system. Mononuclear phagocytes show increased expression of inflammatory markers. RNA-in situ hybridization of rat pancreatic tissue defines the spatial distribution of Cxcl10+ β- and α-cells and their association with CD8+ T cell infiltration, a hallmark of insulitis and islet destruction. Our studies define early islet transcriptional events during immune cell recruitment to islets and reveal spatial associations between stressed β- and α-cells and immune cells. Insights into such early processes can assist in the development of therapeutic and prevention strategies for T1D.

Pancreatic Islet Cells Response to IFNγ Relies on Their Spatial Location within an Islet

Type 1 diabetes (T1D) is an auto-immune disease characterized by the progressive destruction of insulin-producing pancreatic beta cells. While beta cells are the target of the immune attack, the other islet endocrine cells, namely the alpha and delta cells, can also be affected by the inflammatory milieu. Here, using a flow cytometry-based strategy, we compared the impact of IFNγ, one of the main cytokines involved in T1D, on the three endocrine cell subsets isolated from C57BL/6 mouse islets. RNA-seq analyses revealed that alpha and delta cells exposed in vitro to IFNγ display a transcriptomic profile very similar to that of beta cells, with an increased expression of inflammation key genes such as MHC class I molecules, the CXCL10 chemokine and the programmed death-ligand 1 (PD-L1), three hallmarks of IFNγ signaling. Interestingly, at low IFNγ concentration, we observed two beta cell populations (responders and non-responders) based on PD-L1 protein expression. Our data indicate that this differential sensitivity relies on the location of the cells within the islet rather than on the existence of two different beta cells subsets. The same findings were corroborated by the in vivo analysis of pancreatic islets from the non-obese diabetic mouse model of T1D, showing more intense PD-L1 staining on endocrine cells close to immune infiltrate. Collectively, our work demonstrates that alpha and delta cells are as sensitive as beta cells to IFNγ, and suggests a gradual diffusion of the cytokine into an islet. These observations provide novel insights into the in situ inflammatory processes occurring in T1D progression.

Genetic Engineering of Immune Evasive Stem Cell-Derived Islets

Genome editing has the potential to revolutionize many investigative and therapeutic strategies in biology and medicine. In the field of regenerative medicine, one of the leading applications of genome engineering technology is the generation of immune evasive pluripotent stem cell-derived somatic cells for transplantation. In particular, as more functional and therapeutically relevant human pluripotent stem cell-derived islets (SCDI) are produced in many labs and studied in clinical trials, there is keen interest in studying the immunogenicity of these cells and modulating allogeneic and autoimmune immune responses for therapeutic benefit. Significant experimental work has already suggested that elimination of Human Leukocytes Antigen (HLA) expression and overexpression of immunomodulatory genes can impact survival of a variety of pluripotent stem cell-derived somatic cell types. Limited work published to date focuses on stem cell-derived islets and work in a number of labs is ongoing. Rapid progress is occurring in the genome editing of human pluripotent stem cells and their progeny focused on evading destruction by the immune system in transplantation models, and while much research is still needed, there is no doubt the combined technologies of genome editing and stem cell therapy will profoundly impact transplantation medicine in the future.

Leverage biomaterials to modulate immunity for type 1 diabetes

The pathogeny of type 1 diabetes (T1D) is mainly provoked by the β-cell loss due to the autoimmune attack. Critically, autoreactive T cells firsthand attack β-cell in islet, that results in the deficiency of insulin in bloodstream and ultimately leads to hyperglycemia. Hence, modulating immunity to conserve residual β-cell is a desirable way to treat new-onset T1D. However, systemic immunosuppression makes patients at risk of organ damage, infection, even cancers. Biomaterials can be leveraged to achieve targeted immunomodulation, which can reduce the toxic side effects of immunosuppressants. In this review, we discuss the recent advances in harness of biomaterials to immunomodulate immunity for T1D. We investigate nanotechnology in targeting delivery of immunosuppressant, biological macromolecule for β-cell specific autoreactive T cell regulation. We also explore the biomaterials for developing vaccines and facilitate immunosuppressive cells to restore immune tolerance in pancreas.

Islet allografts expressing a PD-L1 and IDO fusion protein evade immune rejection and reverse preexisting diabetes in immunocompetent mice without systemic immunosuppression

Allogeneic islet transplantation is a promising experimental therapy for poorly controlled diabetes. Despite pharmacological immunosuppression, long-term islet engraftment remains elusive. Here, we designed a synthetic fusion transgene coupling PD-L1 and indoleamine dioxygenase [hereafter PIDO] whose constitutive expression prevents immune destruction of genetically engineered islet allograft transplanted in immunocompetent mice. PIDO expressing murine islets maintain robust dynamic insulin secretion in vitro and when transplanted in allogeneic hyperglycemic murine recipients reverse pre-existing streptozotocin-induced and autoimmune diabetes in the absence of pharmacological immunosuppression for more than 50 and 8 weeks, respectively, and is dependent on host CD4 competence. Additionally, PIDO expression in allografts preserves endocrine functional viability of islets and promotes a localized tolerogenic milieu characterized by the suppression of host CD8 T cell and phagocyte recruitment and accumulation of FOXP3⁺ Tregs. Furthermore, in the canine model of xenogeneic islet transplantation, muscle implanted PIDO-expressing porcine islets displayed physiological glucose-responsive insulin secretion competency in euglycemic recipient for up to 20 weeks. In conclusion, the PIDO transgenic technology enables host CD4⁺ T cell-modulated immune evasiveness and long-term functional viability of islet allo- and xenografts in immune-competent recipients without the need for pharmacological immune suppression and would allow for improved outcomes for tissue transplantation.

Mining the transcriptome of target tissues of autoimmune and degenerative pancreatic β-cell and brain diseases to discover therapies

Target tissues of autoimmune and degenerative diseases show signals of inflammation. We used publicly available RNA-seq data to study whether pancreatic β-cells in type 1 and type 2 diabetes and neuronal tissue in multiple sclerosis and Alzheimer’s disease share inflammatory gene signatures. We observed concordantly upregulated genes in pairwise diseases, many of them related to signaling by interleukins and interferons. We next mined these signatures to identify therapies that could be re-purposed/shared among the diseases and identified the bromodomain inhibitors as potential perturbagens to revert the transcriptional signatures. We experimentally confirmed in human β-cells that bromodomain inhibitors I-BET151 and GSK046 prevent the deleterious effects of the pro-inflammatory cytokines interleukin-1β and interferon-γ and at least some of the effects of the metabolic stressor palmitate. These results demonstrate that key inflammation-induced molecular mechanisms are shared between β-cells and brain in autoimmune and degenerative diseases and that these signatures can be mined for drug discovery.

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Similar gene transcription signatures in diabetes, multiple sclerosis, and Alzheimer’s

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Inflammatory mechanisms are present in the target tissues of the four diseases

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Common gene expression signatures were mined for the identification of drug targets

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Bromodomain inhibitors decrease islet inflammation in models of types 1 and 2 diabetes

The type 1 diabetes gene TYK2 regulates β-cell development and its responses to interferon-α

Type 1 diabetes (T1D) is an autoimmune disease that results in the destruction of insulin producing pancreatic β-cells. One of the genes associated with T1D is TYK2, which encodes a Janus kinase with critical roles in type-Ι interferon (IFN-Ι) mediated intracellular signalling. To study the role of TYK2 in β-cell development and response to IFNα, we generated TYK2 knockout human iPSCs and directed them into the pancreatic endocrine lineage. Here we show that loss of TYK2 compromises the emergence of endocrine precursors by regulating KRAS expression, while mature stem cell-islets (SC-islets) function is not affected. In the SC-islets, the loss or inhibition of TYK2 prevents IFNα-induced antigen processing and presentation, including MHC Class Ι and Class ΙΙ expression, enhancing their survival against CD8⁺ T-cell cytotoxicity. These results identify an unsuspected role for TYK2 in β-cell development and support TYK2 inhibition in adult β-cells as a potent therapeutic target to halt T1D progression.

An inflammatory Signature of Glucose Impairment in Cystic Fibrosis

Objective and Design

Cystic fibrosis-related diabetes (CFRD) is a severe complication associated with increased morbidity and mortality in cystic fibrosis (CF) patients. Extensive inflammatory state in CF leads to pancreas damage and insulin resistance with consequent altered glucose tolerance and CFRD development. The aim of the present study was to identify circulating levels of inflammatory markers specifically associated with impaired glucose tolerance (IGT) and overt CFRD in a sample of young adults with CF.

Materials and Methods

Sixty-four CF outpatients, without evident active pulmonary exacerbation, infectious and autoimmune diseases, were enrolled in the study and the levels of 45 inflammatory serum mediators were measured through x magnetic bead panel multiplex technology.

Results

Serum levels of PDGF-AA, CCL20/MIP3α, IFNα, CCL11/eotaxin, CXCL1/GROα, GMCSF, B7H1/PDL1, IL13, IL7, VEGF, and TGFα were all significantly (p<0.05) elevated in patients according to glycemic status and directly correlated with glycated hemoglobin and C-reactive protein levels.

Conclusion

Our findings suggest that increased levels of specific circulating inflammatory mediators are directly associated with impaired glucose tolerance in CF patients, thus, potentially implicating them in CFRD pathogenesis and warranting larger longitudinal studies to validate their monitoring as predictor of CFRD onset.

Restoring tolerance to β-cells in Type 1 diabetes: Current and emerging strategies

Type 1 diabetes (T1D) results from insulin insufficiency due to islet death and dysfunction following T cell-mediated autoimmune attack. The technical feasibility of durable, functional autologous islet restoration is progressing such that it presents the most likely long-term cure for T1D but cannot succeed without the necessary counterpart of clinically effective therapeutic strategies that prevent grafted islets' destruction by pre-existing anti-islet T cells. While advances have been made in broad immunosuppression to lower off-target effects, the risk of opportunistic infections and cancers remains a concern, especially for well-managed T1D patients. Current immunomodulatory strategies in development focus on autologous Treg expansion, treatments to decrease antigen presentation and T effector (Teff) activation, and broad depletion of T cells with or without hematopoietic stem cell transplants. Emerging strategies harnessing the intensified DNA damage response present in expanding T cells, exacerbating their already high sensitivity to apoptosis to abate autoreactive Teff cells.

Transcription and splicing regulation by NLRC5 shape the interferon response in human pancreatic β cells

IFNα is a key regulator of the dialogue between pancreatic β cells and the immune system in early type 1 diabetes (T1D). IFNα up-regulates HLA class I expression in human β cells, fostering autoantigen presentation to the immune system. We observed by bulk and single-cell RNA sequencing that exposure of human induced pluripotent-derived islet-like cells to IFNα induces expression of HLA class I and of other genes involved in antigen presentation, including the transcriptional activator NLRC5. We next evaluated the global role of NLRC5 in human insulin-producing EndoC-βH1 and human islet cells by RNA sequencing and targeted gene/protein determination. NLRC5 regulates expression of HLA class I, antigen presentation-related genes, and chemokines. NLRC5 also mediates the effects of IFNα on alternative splicing, a generator of β cell neoantigens, suggesting that it is a central player of the effects of IFNα on β cells that contribute to trigger and amplify autoimmunity in T1D.

Immune cells and their inflammatory mediators modify β cells and cause checkpoint inhibitor-induced diabetes

Checkpoint inhibitors (CPIs) targeting programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) and cytotoxic T lymphocyte antigen 4 (CTLA-4) have revolutionized cancer treatment but can trigger autoimmune complications, including CPI-induced diabetes mellitus (CPI-DM), which occurs preferentially with PD-1 blockade. We found evidence of pancreatic inflammation in patients with CPI-DM with shrinkage of pancreases, increased pancreatic enzymes, and in a case from a patient who died with CPI-DM, peri-islet lymphocytic infiltration. In the NOD mouse model, anti-PD-L1 but not anti-CTLA-4 induced diabetes rapidly. RNA sequencing revealed that cytolytic IFN-γ+CD8+ T cells infiltrated islets with anti-PD-L1. Changes in β cells were predominantly driven by IFN-γ and TNF-α and included induction of a potentially novel β cell population with transcriptional changes suggesting dedifferentiation. IFN-γ increased checkpoint ligand expression and activated apoptosis pathways in human β cells in vitro. Treatment with anti-IFN-γ and anti-TNF-α prevented CPI-DM in anti-PD-L1-treated NOD mice. CPIs targeting the PD-1/PD-L1 pathway resulted in transcriptional changes in β cells and immune infiltrates that may lead to the development of diabetes. Inhibition of inflammatory cytokines can prevent CPI-DM, suggesting a strategy for clinical application to prevent this complication.

New-onset type 1 diabetes mellitus as a delayed immune-related event after discontinuation of nivolumab: A case report

RATIONALE

Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment. However, they may cause immune-related adverse events. Although there have been a few reports of new-onset type 1 diabetes mellitus (T1DM) during ICI treatment, T1DM as a delayed immune-related event after discontinuing immunotherapy is extremely rare. Herein, we report the case of an elderly veteran who presented with diabetic ketoacidosis 4 months after the discontinuation of treatment with nivolumab.

PATIENT CONCERNS

A 74-year-old veteran was treated with second-line nivolumab for advanced non-small cell lung cancer. After 9 treatment cycles, the administration was discontinued due to fatigue. Four months later, he was admitted to the emergency department in a stuporous mental state and hyperglycemia, with high glycosylated hemoglobin levels (10.6%). C-peptide levels were significantly decreased, with negative islet autoantibodies.

DIAGNOSES

We diagnosed nivolumab-induced T1DM. There were no laboratory results indicating a new thyroid dysfunction or adrenal insufficiency, which are typical endocrine adverse reactions.

INTERVENTIONS

Since the hypothalamic and pituitary functions were preserved and only the pancreatic endocrine capacity was impaired, we administered continuous intravenous insulin injections, with fluid and electrolyte replacement.

OUTCOMES

His serum glucose levels decreased, and symptoms improved; hence, on the 8 day of hospitalization, we switched to multiple daily insulin injections.

LESSONS

The present case indicates that regular glucose monitoring and patient education are needed for diabetic ketoacidosis after the discontinuation of ICI therapy.

The interferon regulatory factors, a double-edged sword, in the pathogenesis of type 1 diabetes

Type 1 diabetes (T1D) is an autoimmune disease resulted from the unrestrained inflammatory attack towards the insulin-producing islet β cells. Although the exact etiology underlying T1D remains elusive, viral infections, especially those specific strains of enterovirus, are acknowledged as a critical environmental cue involved in the early phase of disease initiation. Viral infections could either directly impede β cell function, or elicit pathological autoinflammatory reactions for β cell killing. Autoimmune responses are bolstered by a massive body of virus-derived exogenous pathogen-associated molecular patterns (PAMPs) and the presence of β cell-derived damage-associated molecular patterns (DAMPs). In particular, the nucleic acid components and the downstream nucleic acid sensing pathways serve as the major effector mechanism. The endogenous retroviral RNA, mitochondrial DNA (mtDNA) and genomic fragments generated by stressed or dying β cells induce host responses reminiscent of viral infection, a phenomenon termed as viral mimicry during the early stage of T1D development. Given that the interferon regulatory factors (IRFs) are considered as hub transcription factors to modulate immune responses relevant to viral infection, we thus sought to summarize the critical role of IRFs in T1D pathogenesis. We discuss with focus for the impact of IRFs on the sensitivity of β cells to cytokine stimulation, the vulnerability of β cells to viral infection/mimicry, and the intensity of immune response. Together, targeting certain IRF members, alone or together with other therapeutics, could be a promising strategy against T1D.