Deficiency in B7-H1 (PD-L1)/PD-1 coinhibition triggers pancreatic beta-cell destruction by insulin-specific, murine CD8 T-cells

Structure of PD1 and its mechanism in the treatment of autoimmune diseases

PD-1 and CTLA-4 can play an important role in addressing the issue of autoimmune diseases. PD-1 is a transmembrane glycoprotein expressed on T, B, and Dentric cells. This molecule functions as a checkpoint in T cell proliferation. Ligation of PD-1 with its ligands inhibits the production of IL-2, IL-7, IL-10, and IL-12 as well as other cytokines by macrophages, natural killer (NK) cells, and T cells, which can suppress cell proliferation and inflammation. Today, scientists attempt to protect against autoimmune diseases by PD-1 inhibitory signals. In this review, we discuss the structure, expression, and signaling pathway of PD-1. In addition, we discuss the importance of PD-1 in regulating several autoimmune diseases, reflecting how manipulating this molecule can be an effective method in the immunotherapy of some autoimmune diseases.

Umbilical cord mesenchymal stromal cells transplantation delays the onset of hyperglycemia in the RIP-B7.1 mouse model of experimental autoimmune diabetes through multiple immunosuppressive and anti-inflammatory responses

Type 1 diabetes mellitus (T1DM) is an autoimmune disorder specifically targeting pancreatic islet beta cells. Despite many efforts focused on identifying new therapies able to counteract this autoimmune attack and/or stimulate beta cells regeneration, TD1M remains without effective clinical treatments providing no clear advantages over the conventional treatment with insulin. We previously postulated that both the inflammatory and immune responses and beta cell survival/regeneration must be simultaneously targeted to blunt the progression of disease. Umbilical cord-derived mesenchymal stromal cells (UC-MSC) exhibit anti-inflammatory, trophic, immunomodulatory and regenerative properties and have shown some beneficial yet controversial effects in clinical trials for T1DM. In order to clarify conflicting results, we herein dissected the cellular and molecular events derived from UC-MSC intraperitoneal administration (i.p.) in the RIP-B7.1 mouse model of experimental autoimmune diabetes. Intraperitoneal (i.p.) transplantation of heterologous mouse UC-MSC delayed the onset of diabetes in RIP-B7.1 mice. Importantly, UC-MSC i. p. transplantation led to a strong peritoneal recruitment of myeloid-derived suppressor cells (MDSC) followed by multiple T-, B- and myeloid cells immunosuppressive responses in peritoneal fluid cells, spleen, pancreatic lymph nodes and the pancreas, which displayed significantly reduced insulitis and pancreatic infiltration of T and B Cells and pro-inflammatory macrophages. Altogether, these results suggest that UC-MSC i. p. transplantation can block or delay the development of hyperglycemia through suppression of inflammation and the immune attack.

Diabetic ketoacidosis induced by nivolumab in invasive mucinous adenocarcinoma of the lung: a case report and review of the literature

Background

Nivolumab is the first programmed cell death receptor 1 (PD-1) inhibitor approved in China. Compared with chemotherapy, nivolumab has shown advantages of good efficacy and safety in the treatment of a variety of tumors. However, due to its short time of use in China and lack of safety experience, clinical understanding of its adverse reactions has not been sufficiently elucidated. In recent years, cases of diabetic ketoacidosis caused by nivolumab have been reported in the emergency department, which has aroused our concern.

Case Description

Here we present a serious case of diabetic ketoacidosis in a 69-year-old woman with invasive mucinous adenocarcinoma of the lung, which occurred following therapy with the PD-1 inhibitor nivolumab and dendritic cell/cytokine-induced killer cell (DC/CIK) immunotherapy. She presented with diabetic ketoacidosis 5 days after the second cycle of nivolumab administration. The patient presented with dry mouth symptoms, a maximum blood glucose of 511.2 mg/dL, hemoglobin A1c (HbA1c) level of 7.4%, urine ketone body value of 3+, and extracellular fluid residual alkali level of -3.8 mmol/L. Normal saline and insulin was initiated. The patient had no history of obesity or family history of diabetes. She received a single dose of 3.75 mg of dexamethasone treatment during this period of time which resulted in cough improvement, but did not explain the onset of the diabetes. She was treated with insulin, sitagliptin phosphate tablets and acarbose tablets. Diabetic ketoacidosis was considered an immune-related toxicity caused by nivolumab, and consequently, treatment with nivolumab was suspended. Patient was maintained under insulin treatment with a blood glucose levels normalization.

Conclusions

The incubation period of nivolumab-induced diabetic ketoacidosis is dispersive and the clinical risk is high. Patients need life-long insulin therapy. Blood glucose and HbA1c should be monitored routinely before and during nivolumab immunotherapy to avoid the occurrence of diabetic ketoacidosis. After the occurrence of diabetic ketoacidosis, insulin should be used to actively control blood glucose and do a good job in medication education to ensure long-term compliance of patients. Nivolumab should only be initiated if the patient has a clinical benefit under stable glucose control.

Anti-programmed Cell Death Protein-1 Therapy in Intrahepatic Cholangiocarcinoma Induced Type 1 Diabetes: A Case Report and Literature Review

Immune checkpoint inhibitors, widely used in the treatment of malignancies, can improve the prognosis of patients, while it also can induce various immune-related adverse events, and type 1 diabetes induced by anti-programmed cell death protein-1 is a rare but severe complication. Here we reported a case of type 1 diabetes induced by anti-PD-1 which was to treat intrahepatic cholangiocarcinoma. The case was a 61-year-old female who developed diabetes and ketoacidosis symptoms at the 16th week after anti-PD-1 therapy. Her blood glucose was 30.32 mmol/L, HBA1c was 8.10%, and C-peptide was <0.10 ng/ml. The patient was diagnosed as fulminant type 1 diabetes mellitus complicated with ketoacidosis induced by anti-PD-1, and was treated with massive fluid rehydration, intravenous infusion of insulin and correction of acid-base electrolyte disorder. Hepatectomy was performed after stabilization, and the patient was treated with long-term insulin. Through the case report and literature review, this study aims to improve oncologists' understanding of anti-PD-1 induced type 1 diabetes, so as to make early diagnosis and treatment of the complications and ensure medical safety.

IFN-γ treatment protocol for MHC-Ilo/PD-L1+ pancreatic tumor cells selectively restores their TAP-mediated presentation competence and CD8 T-cell priming potential

Background

Many cancer cells express a major histocompatibility complex class I low/ programmed cell death 1 ligand 1 positive (MHC-I^lo/PD-L1⁺) cell surface profile. For immunotherapy, there is, thus, an urgent need to restore presentation competence of cancer cells with defects in MHC-I processing/presentation combined with immune interventions that tackle the tumor-initiated PD-L1/PD-1 signaling axis. Using pancreatic ductal adenocarcinoma cells (PDACCs) as a model, we here explored if (and how) expression/processing of tumor antigens via transporters associated with antigen processing (TAP) affects priming of CD8 T cells in PD-1/PD-L1-competent/-deficient mice.

Methods

We generated tumor antigen-expressing vectors, immunized TAP-competent/-deficient mice and determined de novo primed CD8 T-cell frequencies by flow cytometry. Similarly, we explored the antigenicity and PD-L1/PD-1 sensitivity of PDACCs versus interferon-γ (IFN-γ)-treated PDACCs in PD-1/PD-L1-competent/deficient mice. The IFN-γ-induced effects on gene and cell surface expression profiles were determined by microarrays and flow cytometry.

Results

We identified two antigens (cripto-1 and an endogenous leukemia virus-derived gp70) that were expressed in the Endoplasmic Reticulum (ER) of PDACCs and induced CD8 T-cell responses either independent (Cripto-1:K^b/Cr_16-24) or dependent (gp70:K^b/p15E) on TAP by DNA immunization. IFN-γ-treatment of PDACCs in vitro upregulated MHC-I- and TAP- but also PD-L1-expression. Mechanistically, PD-L1/PD-1 signaling was superior to the reconstitution of MHC-I presentation competence, as subcutaneously transplanted IFN-γ-treated PDACCs developed tumors in C57BL/6J and PD-L1^-/- but not in PD-1^-/- mice. Using PDACCs, irradiated at day 3 post-IFN-γ-treatment or PD-L1 knockout PDACCs as vaccines, we could selectively bypass upregulation of PD-L1, preferentially induce TAP-dependent gp70:K^b/p15E-specific CD8 T cells associated with a weakened PD-1⁺ exhaustion phenotype and reject consecutively injected tumor transplants in C57BL/6J mice.

Conclusions

The IFN-γ-treatment protocol is attractive for cell-based immunotherapies, because it restores TAP-dependent antigen processing in cancer cells, facilitates priming of TAP-dependent effector CD8 T-cell responses without additional check point inhibitors and could be combined with genetic vaccines that complement priming of TAP-independent CD8 T cells.

Immunotherapy-Associated Pancreatic Adverse Events: Current Understanding of Their Mechanism, Diagnosis, and Management

Immune checkpoint inhibitors (ICIs) such as anti-programmed death-1 (PD-1) and its ligand PD-L1 and anti-cytotoxic T-lymphocyte antigen 4 (CTLA-4) monoclonal antibodies, are involved in T cell-mediated immune response augmentation and promote anti-tumor immunity. Cancer patients treated with combination of immunotherapy, chemotherapy, radiotherapy, and targeted therapy exhibit superior clinical outcomes and tolerance compared with patients treated with monotherapies. However, immutherapy is associated with several concomitant immune-related adverse events (irAEs). For instance, IrAEs interferes with function of gastrointestinal tract, endocrine, dermatological, nervous system and musculoskeletal systems. ICIs-associated pancreatic injury might causes decrease in endocrine and exocrine pancreatic function, resulting in metabolic and nutritional disorders. Clinicians who administer immune checkpoint inhibitors to cancer patients are diagnosed with hyperglycemia, abdominal pain and steatorrhea. Currently, the precise mechanism of ICIs-associated pancreatic injury has not been fully explored. This paper summarizes incidence, diagnosis, clinical characteristics, potential mechanisms, and treatment management patterns of ICIs-associated pancreatic AEs based on previous studies. In addition, possible management approaches of these adverse effects are presented in this paper. in the findings summarized in this paper lay a basis for management of ICIs-associated pancreatic AEs and expanding future immunotherapy applications.

Predictive Biomarkers of Immune Checkpoint Inhibitors-Related Toxicities

The emergence and continuous development of immune checkpoint inhibitors (ICIs) therapy brings a revolution in cancer therapy history, but the major hurdle associated with their usage is the concomitant ICIs-related toxicities that present a challenge for oncologists. The toxicities may involve non-specific symptoms of multiple systems as for the unique mechanism of formation, which are not easily distinguishable from traditional toxicities. A few of these adverse events are self-limiting and readily manageable, but others may limit treatment, cause interruption and need to be treated with methylprednisolone or tumor necrosis factor-α (TNF-α) antibody infliximab, and even directly threaten life. Early accurate recognition and adequate management are critical to the patient's prognosis and overall survival (OS). Several biomarkers such as the expression of programmed cell death ligand 1 (PD-L1), tumor mutation burden (TMB), and microsatellite instability-high (MSI-H)/mismatch repair-deficient (dMMR) have been proved to be the predictors for anti-tumor efficacy of ICIs, but there is a gap in clinical needs for effective biomarkers that predict toxicities and help filter out the patients who may benefit most from these costly therapies while avoiding major risks of toxicities. Here, we summarize several types of risk factors correlated with ICIs-related toxicities to provide a reference for oncologists to predict the occurrence of ICIs-related toxicities resulting in a timely process in clinical practice.

Anti PD-1 monoclonal antibody induced autoimmune diabetes mellitus: a case report and brief review

Nowadays, immune checkpoint inhibitor therapy has been used in more and more cancer patients. These agents were associated with immune-related adverse effects, and autoimmune diabetes mellitus is one of them. And it is not common but can be potentially fatal. Anti PD-1 monoclonal antibody is a humanized IgG4 antibody against PD-1, which has been applied in advanced non-small cell lung cancer (NSCLC) treatment. In this paper, we reported the case of autoimmune diabetes mellitus induced by anti PD-1 monoclonal antibody in NSCLC treatment. Here is a 73-year-old male patient with no diabetes history who had anti PD-1 monoclonal antibody 200 mg every 3 weeks for NSCLC treatment. After 10 cycles of the therapy, his blood glucose level elevated and he suffered diabetic ketoacidosis (DKA). And his C-peptide was significantly decreased with negative relative auto-antibodies. Combined with his medical history and the laboratory examination, anti PD-1 monoclonal antibody induced autoimmune diabetes mellitus was diagnosed. After recovering from DKA and controlling his blood glucose, his anti PD-1 therapy was continued and he still got some benefit. This report suggested that glycemic monitoring is imperative during this anti PD-1 monoclonal antibody treatment. Moreover, after controlling the blood glucose level, continuing the immune therapy could still be benefit and safe for the patient.

Stimulatory and Inhibitory Co-signals in Autoimmunity

Co-receptors cooperatively regulate the function of immune cells to optimize anti-infectious immunity while limiting autoimmunity by providing stimulatory and inhibitory co-signals. Among various co-receptors, those in the CD28/CTLA-4 family play fundamental roles in the regulation of lymphocytes by modulating the strength, quality, and/or duration of the antigen receptor signal. The development of the lethal lymphoproliferative disorder and various tissue-specific autoimmune diseases in mice deficient for CTLA-4 and PD-1, respectively, clearly demonstrates their pivotal roles in the development and the maintenance of immune tolerance. The recent success of immunotherapies targeting CTLA-4 and PD-1 in the treatment of various cancers highlights their critical roles in the regulation of cancer immunity in human. In addition, the development of multifarious autoimmune diseases as immune-related adverse events of anti-CTLA-4 and anti-PD-1/PD-L1 therapies and the successful clinical application of the CD28 blocking therapy using CTLA-4-Ig to the treatment of arthritis assure their crucial roles in the regulation of autoimmunity in human. Accumulating evidences in mice and humans indicate that genetic and environmental factors strikingly modify effects of the targeted inhibition and potentiation of co-signals. In this review, we summarize our current understanding of the roles of CD28, CTLA-4, and PD-1 in autoimmunity. Deeper understandings of the context-dependent and context-independent functions of co-signals are essential for the appropriate usage and the future development of innovative immunomodulatory therapies for a diverse array of diseases.

Immunotoxicity from checkpoint inhibitor therapy: clinical features and underlying mechanisms

Immune checkpoint inhibition with monoclonal antibodies is becoming increasingly commonplace in cancer medicine, having contributed to a widening of therapeutic options across oncological indications. Disruption of immune tolerance is the key mechanism of action of checkpoint inhibitors and although immune-related adverse events are a typical class effect of these compounds, the relationship between toxicity and response is not fully understood. Awareness and vigilance are paramount in recognizing potentially life-threatening toxicities and managing them in a timely manner. In this review article, we provide an overview of the clinical features, pathological findings and management principles of common immune-related toxicities, attempting to provide mechanistic insight into an increasingly common complication of cancer therapy.

Rapid onset type-1 diabetes and diabetic ketoacidosis secondary to nivolumab immunotherapy: a review of existing literature

Nivolumab is a programmed cell death receptor (PD-1) inhibitor that is increasingly used for various malignancies, both as a first line agent and as salvage therapy. Being a PD-1/PD-1 ligand checkpoint inhibitor, it is known to cause autoimmune inflammation of various organs and has been associated with thyroiditis, insulitis, colitis, hepatitis and encephalitis to name a few. There are increasing reports of nivolumab leading to acute onset fulminant type 1 diabetes and diabetic ketoacidosis (DKA). We present a case of a 68-year-old man who developed DKA after 2 doses of nivolumab for metastatic melanoma. He was found to have type 1 diabetes, but no diabetes related antibodies were positive. He recovered from diabetes and continues to use insulin 1 year after his diagnosis. This case and associated review illustrates the importance of educating and monitoring patients who start nivolumab therapy regarding this potentially life threatening complication.

Navigating Two Roads to Glucose Normalization in Diabetes: Automated Insulin Delivery Devices and Cell Therapy

Incredible strides have been made since the discovery of insulin almost 100 years ago. Insulin formulations have improved dramatically, glucose levels can be measured continuously, and recently first-generation biomechanical "artificial pancreas" systems have been approved by regulators around the globe. However, still only a small fraction of patients with diabetes achieve glycemic goals. Replacement of insulin-producing cells via transplantation shows significant promise, but is limited in application due to supply constraints (cadaver-based) and the need for chronic immunosuppression. Over the past decade, significant progress has been made to address these barriers to widespread implementation of a cell therapy. Can glucose levels in people with diabetes be normalized with artificial pancreas systems or via cell replacement approaches? Here we review the road ahead, including the challenges and opportunities of both approaches.

Preproinsulin Designer Antigens Excluded from Endoplasmic Reticulum Suppressed Diabetes Development in NOD Mice by DNA Vaccination

DNA vaccines against autoimmune type 1 diabetes (T1D) contain a nonpredictable risk to induce autoreactive T cell responses rather than a protective immunity. Little is known if (and how) antigen expression and processing requirements favor the induction of autoreactive or protective immune responses by DNA immunization. Here, we analyzed whether structural properties of preproinsulin (ppins) variants and/or subcellular targeting of ppins designer antigens influence the priming of effector CD8⁺ T cell responses by DNA immunization. Primarily, we used H-2^b RIP-B7.1 tg mice, expressing the co-stimulator molecule B7.1 in beta cells, to identify antigens that induce or fail to induce autoreactive ppins-specific (K^b/A_12-21 and/or K^b/B_22-29) CD8⁺ T cell responses. Female NOD mice, expressing the diabetes-susceptible H-2^g7 haplotype, were used to test ppins variants for their potential to suppress spontaneous diabetes development. We showed that ppins antigens excluded from expression in the endoplasmic reticulum (ER) did not induce CD8⁺ T cells or autoimmune diabetes in RIP-B7.1 tg mice, but efficiently suppressed spontaneous diabetes development in NOD mice as well as ppins-induced CD8⁺ T cell-mediated autoimmune diabetes in PD-L1^−/− mice. The induction of a ppins-specific therapeutic immunity in mice has practical implications for the design of immune therapies against T1D in individuals expressing different major histocompatibility complex (MHC) I and II molecules.

Programmed Cell Death-1 Inhibitor-Induced Type 1 Diabetes Mellitus

CONTEXT

Pembrolizumab (Keytruda; Merck Sharp & Dohme) is a humanized IgG4 monoclonal antibody used in cancer immunotherapy. It targets the programmed cell death-1 (PD-1) receptor, which is important in maintaining self-tolerance. However, immune checkpoint blockade is associated with a risk for immune-related adverse events (irAEs) potentially affecting the endocrine organs. Type 1 diabetes mellitus is a rare irAE of PD-1 inhibitors, occurring in 0.2% of cases.

EVIDENCE ACQUISITION

Systematic search of four databases (MEDLINE, Embase, Web of Science, and Cochrane Library) using the search terms "diabetes" or "ketoacidosis" and "pembrolizumab," "nivolumab," "PD-1 inhibitor," or "immunotherapy." Included were articles published in English between 1 January 2012 and 1 January 2018. The search was supplemented by bibliographic searches of the complete reference lists of all included papers.

EVIDENCE SYNTHESIS

We provide an overview of all published cases (n = 42) of PD-1 inhibitor-induced type 1 diabetes mellitus to date, including a well-characterized case of islet cell antibody and glutamic acid decarboxylase antibody-positive diabetes mellitus, in a patient with a diabetes-prone HLA genotype. She presented with diabetic ketoacidosis during pembrolizumab therapy for a metastatic uveal melanoma. Furthermore, we discuss potential pathogenic mechanisms, clinical presentation, prognostic markers (β-cell antibodies and HLA type), treatment, and a screening protocol.

CONCLUSIONS

Because the use of immunotherapy will increase, it is essential that all clinicians are aware of diabetic ketoacidosis as a rare and life-threatening side effect of immunotherapy. Blood glucose monitoring during anti-PD-1 therapy is necessary.

Occurrence of type 1 and type 2 diabetes in patients treated with immunotherapy (anti-PD-1 and/or anti-CTLA-4) for metastatic melanoma: a retrospective study

Anti-PD-1 and anti-CTLA-4 antibodies cause immune-related side effects such as autoimmune type 1 diabetes (T1D). It has also been suggested that by increasing TNF-α, IL-2 and IFN-γ production, anti-PD-1 and/or anti-CTLA-4 treatment could affect pancreatic beta cell function and insulin sensitivity. This study was based on a retrospective observational analysis from 2 July 2014 to 27 June 2016, which evaluated the occurrence of T1D and changes in glycemia and C-reactive protein (CRP) plasma concentrations in patients undergoing anti-PD-1 and/or anti-CTLA-4 treatment for melanoma at the Saint Louis Hospital. All cases of T1D that developed during immunotherapy registered in the French Pharmacovigilance Database (FPVD) were also considered. Among the 132 patients included, 3 cases of T1D occurred. For the remaining subjects, blood glucose was not significantly affected by anti-PD-1 treatment, but CRP levels (mg/l) significantly increased during anti-PD-1 treatment (p = 0.017). However, 1 case of type 2 diabetes (T2D) occurred (associated with a longer therapy duration). Moreover, glycemia of patients pretreated (n = 44) or concomitantly treated (n = 8) with anti-CTLA-4 tended to increase during anti-PD-1 therapy (p = 0.068). From the FPVD, we obtained 14 cases of T1D that occurred during immunotherapy and were primarily characterized by the rapidity and severity of onset. In conclusion, in addition to inducing this rare immune-related diabetes condition, anti-PD-1 treatment appears to increase CRP levels, a potential inflammatory trigger of insulin resistance, but without any short-term impact on blood glucose level.

Rs2227982 and rs2227981 in PDCD1 gene are functional SNPs associated with T1D risk in East Asian

AIMS

To investigate whether PDCD1 gene polymorphisms are functional, and their associations with T1D risk and related clinical characteristics.

METHODS

A total of 3060 Chinese Han individuals (1019 T1D patients and 2041 healthy controls) were genotyped for 4 tag single nucleotide polymorphisms (SNPs) within the PDCD1 region (rs2227982, rs7421861, rs10204525, and rs6710479) and another most studied synonymous SNP, rs2227981. In addition, 251 healthy individuals underwent an oral glucose tolerance test (OGTT); measures of insulin release and sensitivity were estimated from insulinogenic, BIGTT, Matsuda. Further, we performed in silico bioinformatics analysis to explore potential functional annotation of the investigated SNPs in PDCD1 gene.

RESULTS

Both rs2227982 and rs2227981 polymorphisms were associated with T1D risk in Chinese Han population under additive model (OR = 0.84, 95% CI 0.75-0.93 and OR = 1.23, 95% CI 1.08-1.40, respectively), but not the other three SNPs in PDCD1 gene. Our meta-analysis revealed that rs2227982 and rs2227981 polymorphisms also have significant associations with T1D risk in East Asians (OR = 0.82, 95% CI 0.74-0.90 and OR = 1.23, 95% CI 1.12-1.36, respectively), but not Europeans. And the T allele of rs2227982 polymorphism is associated with increased 30 min post OGTT glucose level (P = 0.023) and 120 min post OGTT insulin level (P = 0.033). Furthermore, the genetic and regulatory architecture suggested all the 5 investigated SNPs in PDCD1 are putatively functional.

CONCLUSIONS

Both rs2227982 and rs2227981 polymorphisms were associated with T1D risk in East Asians, and rs2227982 also had a significant association with glycemic traits, which suggested PDCD1 gene polymorphisms might participate in facilitating T1D risk.

A Theoretical Basis for the Efficacy of Cancer Immunotherapy and Immunogenic Tumor Dormancy: The Adaptation Model of Immunity

In the past decades, a variety of strategies have been explored to cure cancer by means of immunotherapy, which is less toxic compared with chemotherapy or radiation therapy, and could establish memory for long-lasting protection against tumor recurrence. These endeavors have been successful in offering therapeutic antibodies, vaccines, or cellular immunotherapies, which resulted in prolonging survival of some cancer patients; however, complete cures have not been consistently achieved. The conception, design, and implementation of these promising immunotherapeutic strategies have been influenced by two schools of thought in immunology, which include the "self-nonself" (SNS) model and the "danger" model. Further progress in cancer immunotherapy to achieve consistent cancer cures requires an evolution in our understanding of how the immune system works. The purpose of this review is to revisit premises and limitations of the SNS and danger models based on the outcomes of cancer immunotherapies by suggesting that both models are two sides of the same coin describing how the immune response is induced against cancer. However, neither explains how the immune response succeeds or fails in eliminating the tumor. To this end, the adaptation model has been proposed to explain efficacy of the immune response for achieving cancer cure.

Autoimmune diabetes induced by PD-1 inhibitor-retrospective analysis and pathogenesis: a case report and literature review

Anti-PD-1 antibody treatment is approved in advanced melanoma and provides median overall survival over 24 months. The main treatment-related side effects are immune-related adverse events, which include rash, pruritus, vitiligo, thyroiditis, diarrhoea, hepatitis and pneumonitis. We report a case of autoimmune diabetes related to nivolumab treatment. A 73-year-old man was treated in second line with nivolumab at 3 mg/kg every two weeks for metastatic melanoma. At 6 weeks of treatment, he displayed diabetic ketoacidosis. Nivolumab was withheld 3.5 weeks and insulin therapy was initiated, enabling a normalization of glycaemia and the disappearance of symptoms. Laboratory investigations demonstrated the presence of islet cell autoantibodies, while C-peptide was undetectable. Retrospective explorations on serum banked at week 0 and 3 months before the start of nivolumab, already showed the presence of autoantibodies, but normal insulin, C-peptide secretion and glycaemia. Partial response was obtained at month 3, and nivolumab was then resumed at the same dose. The clinical context and biological investigations before, at and after nivolumab initiation suggest the autoimmune origin of this diabetes, most likely induced by anti-PD-1 antibody in a predisposed patient. The role of PD-1/PD-L1 binding is well known in the pathogenesis of type 1 diabetes. Therefore, this rare side effect can be expected in a context of anti-PD-1 treatment. Glycaemia should be monitored during PD-1/PD-L1 blockade. The presence of autoantibodies before treatment could identify individuals at risk of developing diabetes, but systematic titration may not be relevant considering the rarity of this side effect.

Immune Checkpoint Inhibitor-Associated Type 1 Diabetes Mellitus: Case Series, Review of the Literature, and Optimal Management

With the introduction of immune checkpoint inhibitors into clinical practice, various autoimmune toxicities have been described. Antibodies targeting the receptor:ligand pairing of programmed death receptor-1 (PD-1) and its cognate ligand programmed death-ligand 1 (PD-L1) in rare reports have been associated with autoimmune diabetes mellitus. We report 2 cases of rapid-onset, insulin-dependent, type 1 diabetes mellitus in the setting of administration of nivolumab, a fully human monoclonal antibody to PD-1, and atezolizumab, a humanized monoclonal antibody to PD-L1. This appears to be the first report of autoimmune diabetes mellitus associated with atezolizumab. In addition, we provide a brief review of similar cases reported in the literature and a discussion of potential mechanisms for this phenomenon and propose a diagnostic and treatment algorithm.

Immune checkpoint molecule PD-1 acts as a novel biomarker for the pathological process of gestational diabetes mellitus

AIM

Accumulating evidence suggested that challenge of the maternal-fetal interaction during pregnancy might cause the impairment of immunological hemostasis and lead to gestational diabetes mellitus (GDM) pathological process. Immune checkpoint molecule PD-1 is one of the critical molecule balancing immune response and immunological tolerance.

METHODS

PD-1 expressions on T-cell subsets of GDM patients and control groups were measured via flow cytometric analysis and followed up.

RESULTS

Downregulation of PD-1 acted as an indicator for GDM occurrence in the third trimester of pregnancy. With the recovery of GDM, PD-1 expression restored to normal level.

CONCLUSION

PD-1 expression on T-cell subsets is a novel biomarker for the occurrence and recovery of GDM.

Programmed cell death-1, PD-1, is dysregulated in T cells from children with new onset type 1 diabetes

BACKGROUND

Programmed death cell 1 (PD-1) is an inhibitor of T cell activation and is also functionally linked to glycolysis. We hypothesized that PD-1 expression is defective in activated T cells from children with type 1 diabetes (T1D), resulting in abnormal T cell glucose metabolism.

METHODS

In this pilot study, we enrolled children with new onset T1D within 2 weeks of diagnosis (T1D), unaffected siblings of T1D (SIBS), unaffected, unrelated children (CTRL), children with new onset, and untreated Crohn disease (CD). We repeated the assays 4-6 months post-diagnosis in T1D (T1D follow up). We analyzed anti-CD3/-CD28-stimulated peripheral blood mononuclear cells (PBMC) subsets for PD-1 expression by flow cytometry at baseline and after 24 h in culture. We measured cytokines in the culture medium by multiplex ELISA and glycolytic capacity with a flux analyzer.

RESULTS

We enrolled 37 children. T cells derived from subjects with T1D had decreased PD-1 expression compared to the other study groups. However, in T1D follow-up T cells expressed PD-1 similarly to controls, but had no differences in PBMC cytokine production. Nonetheless, T1D follow up PBMCs had enhanced glycolytic capacity compared to T1D.

CONCLUSIONS

Activated T cells from T1D fail to upregulate PD-1 upon T-cell receptor stimulation, which may contribute to the pathogenesis of T1D. T1D follow up PBMC expression of PD-1 normalizes, together with a significant increase in glycolysis compared to T1D. Thus, insulin therapy in T1D children is associated with normal PD1 expression and heightened glycolytic capacity in PBMC.

The Expression of Programmed Death-1 on CD4+ and CD8+ T Lymphocytes in Patients with Type 2 Diabetes and Severe Sepsis

Objective

To investigate the expression of Programmed death-1 (PD-1) on T lymphocytes in patients with type 2 diabetes mellitus (T2DM) and severe sepsis, we determined PD-1 expression on CD4⁺ and CD8⁺ T lymphocytes of patients with T2DM, severe sepsis, and T2DM combined with severe sepsis.

Research Design and Methods

This prospective and observational study included 50 healthy controls, 80 cases of T2DM without infection (T2DM group), 88 cases of severe sepsis without T2DM (SS group), and 77 cases of severe sepsis combined with T2DM (SS+T2DM group). Expression of peripheral blood PD-1⁺ CD4⁺ T cells and PD-1⁺ CD8⁺ T cells were compared between these 4 groups. Then, 28-day survival of the SS and SS+T2DM patients was assessed, and the expression of PD-1 on T cells was also compared between survivors and non-survivors.

Results

Percentages of PD-1⁺ CD4⁺ T cells and PD-1⁺ CD8⁺ T cells were higher in the T2DM group than in the healthy control group, and were highest in the SS and SS+T2DM groups. However, the expression of PD-1 on T cells and the mortality showed no significant difference between the SS and SS+T2DM groups. The expression of PD-1 on T cells was higher in non-survivors than survivors, but within the survivor group or non-survivor group, no difference can be detected between those with T2DM and those without T2DM.

Conclusion

The expression of PD-1 on T cells was increased in both T2DM and severe septic patients, but combining T2DM did not cause a further increase on the PD-1 expression in patients with severe sepsis.

Exploring the induction of preproinsulin-specific Foxp3(+) CD4(+) Treg cells that inhibit CD8(+) T cell-mediated autoimmune diabetes by DNA vaccination

DNA vaccination is a promising strategy to induce effector T cells but also regulatory Foxp3⁺ CD25⁺ CD4⁺ Treg cells and inhibit autoimmune disorders such as type 1 diabetes. Little is known about the antigen requirements that facilitate priming of Treg cells but not autoreactive effector CD8⁺ T cells. We have shown that the injection of preproinsulin (ppins)-expressing pCI/ppins vector into PD-1- or PD-L1-deficient mice induced K^b/A12-21-monospecific CD8⁺ T cells and autoimmune diabetes. A pCI/ppinsΔA12-21 vector (lacking the critical K^b/A12-21 epitope) did not induce autoimmune diabetes but elicited a systemic Foxp3⁺ CD25⁺ Treg cell immunity that suppressed diabetes induction by a subsequent injection of the diabetogenic pCI/ppins. TGF-β expression was significantly enhanced in the Foxp3⁺ CD25⁺ Treg cell population of vaccinated/ppins-primed mice. Ablation of Treg cells in vaccinated/ppins-primed mice by anti-CD25 antibody treatment abolished the protective effect of the vaccine and enabled diabetes induction by pCI/ppins. Adoptive transfer of Treg cells from vaccinated/ppins-primed mice into PD-L1^−/− hosts efficiently suppressed diabetes induction by pCI/ppins. We narrowed down the Treg-stimulating domain to a 15-residue ppins76–90 peptide. Vaccine-induced Treg cells thus play a crucial role in the control of de novo primed autoreactive effector CD8⁺ T cells in this diabetes model.

PD-L1-driven tolerance protects neurogenin3-induced islet neogenesis to reverse established type 1 diabetes in NOD mice

A breakdown in self-tolerance underlies autoimmune destruction of β-cells and type 1 diabetes. A cure by restoring β-cell mass is limited by the availability of transplantable β-cells and the need for chronic immunosuppression. Evidence indicates that inhibiting costimulation through the PD-1/PD-L1 pathway is central to immune tolerance. We therefore tested whether induction of islet neogenesis in the liver, protected by PD-L1-driven tolerance, reverses diabetes in NOD mice. We demonstrated a robust induction of neo-islets in the liver of diabetic NOD mice by gene transfer of Neurogenin3, the islet-defining factor, along with betacellulin, an islet growth factor. These neo-islets expressed all the major pancreatic hormones and transcription factors. However, an enduring restoration of glucose-stimulated insulin secretion and euglycemia occurs only when tolerance is also induced by the targeted overexpression of PD-L1 in the neo-islets, which results in inhibition of proliferation and increased apoptosis of infiltrating CD4(+) T cells. Further analysis revealed an inhibition of cytokine production from lymphocytes isolated from the liver but not from the spleen of treated mice, indicating that treatment did not result in generalized immunosuppression. This treatment strategy leads to persistence of functional neo-islets that resist autoimmune destruction and consequently an enduring reversal of diabetes in NOD mice.

The adaptation model of immunity

Although 'self-nonself' and 'danger' theories have improved our understanding of the immune system, successful immunotherapy of cancer and many autoimmune diseases still remain far from reach. This indicates that our knowledge of how the immune system decides to respond effectively or ineffectively is limited. Emerging evidence suggest that decision-making during the immune response is not solely determined by 'nonself' entity of the antigen or damage-associated 'danger' signals. This article provides an overview of the 'self-nonself' and 'danger' models, and suggests that 'adaptation' signals are needed to guarantee immunological tolerance that has been observed during the immune response toward 'self', 'nonself' or even 'danger'. This should be facilitated by dynamic expression of adapting receptors (ARs) and adapting ligands on cells of the immune system and other somatic cells. Any alterations in the expression of ARs on certain tissues would result in tissue-specific autoimmune diseases or spontaneous regression of cancer. Identification of such ARs and their nominal adapting ligands could lead to the discovery of currently unknown receptors and their implications in the treatment of cancer, solid organ transplantation and autoimmune diseases.

Immunological in vivo effects of B7-H1 deficiency

B7-H1 regulatory protein, a member of the B7-H family, plays a crucial role in the modulation of immune response in healthy steady-state conditions as well as in different pathologies. B7-H1 knockout mice represent an important model to elucidate further molecular and cellular mechanisms involved, among others, in autoimmunity development and cancer progression. However, a deep immunologic characterization of this model is not complete yet. This study examined the role of B7-H1 in vivo further by direct comparison of specifically phenotyped spleen immune-cell subpopulations and their activation and naïve/memory state as well as cytokine profile in wild-type and B7-H1 knockout mice. Our results demonstrated that B7-H1 deficiency in vivo modulates several immunological parameters, including the amount and composition of Gr1(+)CD11b(+) myeloid population, the composition and activation state of the DC compartment, the frequency and status of NK and NKT cells, B-cells, naïve/memory state of CD8 T-cells and production of IL-2 and IL-10 cytokines. Moreover, we observed an increase in the PD-1 expression in the immune cells in B7-H1 knockout mice compared to the wild-type animals. Valuing the importance of B7-H1 knockout mice for their use in disease models, these data underline the role of B7-H1 in vivo also in healthy state and should be taken into account in future studies on this immunosuppressive molecule.

Programmed cell death 1 (PD-1) regulates the effector function of CD8 T cells via PD-L1 expressed on target keratinocytes

Programmed cell death 1 (PD-1) is an inhibitory molecule expressed by activated T cells. Its ligands (PD-L1 and -L2; PD-Ls) are expressed not only by a variety of leukocytes but also by stromal cells. To assess the role of PD-1 in CD8 T cell-mediated diseases, we used PD-1-knockout (KO) OVA-specific T cell-receptor transgenic (Tg) CD8 T cells (OT-I cells) in a murine model of mucocutaneous graft-versus-host disease (GVHD). We found that mice expressing OVA on epidermal keratinocytes (K14-mOVA mice) developed markedly enhanced GVHD-like disease after transfer of PD-1-KO OT-I cells as compared to those mice transferred with wild-type OT-I cells. In addition, K14-mOVA × OT-I double Tg (DTg) mice do not develop GVHD-like disease after adoptive transfer of OT-I cells, while transfer of PD-1-KO OT-I cells caused GVHD-like disease in a Fas/Fas-L independent manner. These results suggest that PD-1/PD-Ls-interactions have stronger inhibitory effects on pathogenic CD8 T cells than does Fas/Fas-L-interactions. Keratinocytes from K14-mOVA mice with GVHD-like skin lesions express PD-L1, while those from mice without the disease do not. These findings reflect the fact that primary keratinocytes express PD-L1 when stimulated by interferon-γ in vitro. When co-cultured with K14-mOVA keratinocytes for 2 days, PD-1-KO OT-I cells exhibited enhanced proliferation and activation compared to wild-type OT-I cells. In addition, knockdown of 50% PD-L1 expression on the keratinocytes with transfection of PD-L1-siRNA enhanced OT-I cell proliferation. In aggregate, our data strongly suggest that PD-L1, expressed on activated target keratinocytes presenting autoantigens, regulates autoaggressive CD8 T cells, and inhibits the development of mucocutaneous autoimmune diseases.

IGRP and insulin vaccination induce CD8+ T cell-mediated autoimmune diabetes in the RIP-CD80GP mouse

Autoimmune diabetes is characterized by autoantigen-specific T cell-mediated destruction of pancreatic islet beta cells, and CD8(+) T cells are key players during this process. We assessed whether the bitransgenic RIP-CD80 x RIP-LCMV-GP (RIP-CD80GP) mice may be a versatile antigen-specific model of inducible CD8(+) T cell-mediated autoimmune diabetes. Antigen-encoding DNA, peptide-loaded dendritic cells and antigen plus incomplete Freund's adjuvant were used for vaccination. Of 14 pancreatic proteins tested by DNA vaccination, murine pre-proinsulin 2 (100% of mice; median time after vaccination, 60 days) and islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP) (77%, 58 days) could induce diabetes. Vaccination with DNA encoding for zinc transporter 8, Ia-2, Ia-2β, glutamic acid decarboxylase 67 (Gad67), chromogranin A, insulinoma amyloid polypeptide and homeobox protein Nkx-2.2 induced diabetes development in 25-33% of mice. Vaccination with DNA encoding for Gad65, secretogranin 5, pancreas/duodenum homeobox protein 1 (Pdx1), carboxyl ester lipase, glucagon and control hepatitis B surface antigen (HBsAg) induced diabetes in <20% of mice. Diabetes induction efficiency could be increased by DNA vaccination with a vector encoding a ubiquitin-antigen fusion construct. Diabetic mice had florid T cell islet infiltration. CD8(+) T cell targets of IGRP were identified with a peptide library-based enzyme-linked immunospot assay, and diabetes could also be induced by vaccination with major histocompatibility complex (MHC) class I-restricted IGRP peptides loaded on mature dendritic cells. Vaccination with antigen plus incomplete Freund's adjuvant, which can prevent diabetes in other models, led to rapid diabetes development in the RIP-CD80GP mouse. We conclude that RIP-CD80GP mice are a versatile model of antigen specific autoimmune diabetes and may complement existing mouse models of autoimmune diabetes for evaluating CD8(+) T cell-targeted prevention strategies.

Long-term IKK2/NF-κB signaling in pancreatic β-cells induces immune-mediated diabetes

Type 1 diabetes is a multifactorial inflammatory disease in genetically susceptible individuals characterized by progressive autoimmune destruction of pancreatic β-cells initiated by yet unknown factors. Although animal models of type 1 diabetes have substantially increased our understanding of disease pathogenesis, heterogeneity seen in human patients cannot be reflected by a single model and calls for additional models covering different aspects of human pathophysiology. Inhibitor of κB kinase (IKK)/nuclear factor-κB (NF-κB) signaling is a master regulator of inflammation; however, its role in diabetes pathogenesis is controversially discussed by studies using different inhibition approaches. To investigate the potential diabetogenic effects of NF-κB in β-cells, we generated a gain-of-function model allowing conditional IKK2/NF-κB activation in β-cells. A transgenic mouse model that expresses a constitutively active mutant of human IKK2 dependent on Pdx-1 promoter activity (IKK2-CA(Pdx-1)) spontaneously develops full-blown immune-mediated diabetes with insulitis, hyperglycemia, and hypoinsulinemia. Disease development involves a gene expression program mimicking virus-induced diabetes and allergic inflammatory responses as well as increased major histocompatibility complex class I/II expression by β-cells that could collectively promote diabetes development. Potential novel diabetes candidate genes were also identified. Interestingly, animals successfully recovered from diabetes upon transgene inactivation. Our data give the first direct evidence that β-cell-specific IKK2/NF-κB activation is a potential trigger of immune-mediated diabetes. Moreover, IKK2-CA(Pdx-1) mice provide a novel tool for studying critical checkpoints in diabetes pathogenesis and mechanisms governing β-cell degeneration/regeneration.

A missing PD-L1/PD-1 coinhibition regulates diabetes induction by preproinsulin-specific CD8 T-cells in an epitope-specific manner

Coinhibitory PD-1/PD-L1 (B7-H1) interactions provide critical signals for the regulation of autoreactive T-cell responses. We established mouse models, expressing the costimulator molecule B7.1 (CD80) on pancreatic beta cells (RIP-B7.1 tg mice) or are deficient in coinhibitory PD-L1 or PD-1 molecules (PD-L1^−/− and PD-1^−/− mice), to study induction of preproinsulin (ppins)-specific CD8 T-cell responses and experimental autoimmune diabetes (EAD) by DNA-based immunization. RIP-B7.1 tg mice allowed us to identify two CD8 T-cell specificities: pCI/ppins DNA exclusively induced K^b/A_12–21-specific CD8 T-cells and EAD, whereas pCI/ppinsΔA_12–21 DNA (encoding ppins without the COOH-terminal A_12–21 epitope) elicited K^b/B_22–29-specific CD8 T-cells and EAD. Specific expression/processing of mutant ppinsΔA_12–21 (but not ppins) in non-beta cells, targeted by intramuscular DNA-injection, thus facilitated induction of K^b/B_22–29-specific CD8 T-cells. The A_12–21 epitope binds K^b molecules with a very low avidity as compared with B_22–29. Interestingly, immunization of coinhibition-deficient PD-L1^−/− or PD-1^−/− mice with pCI/ppins induced K^b/A_12–21-monospecific CD8 T-cells and EAD but injections with pCI/ppinsΔA_12–21 did neither recruit K^b/B_22–29-specific CD8 T-cells into the pancreatic target tissue nor induce EAD. PpinsΔA_12–21/(K^b/B_22–29)-mediated EAD was efficiently restored in RIP-B7.1⁺/PD-L1^−/− mice, differing from PD-L1^−/− mice only in the tg B7.1 expression in beta cells. Alternatively, an ongoing beta cell destruction and tissue inflammation, initiated by ppins/(K^b/A_12–21)-specific CD8 T-cells in pCI/ppins+pCI/ppinsΔA_12–21 co-immunized PD-L1^−/− mice, facilitated the expansion of ppinsΔA_12–21/(K^b/B_22–29)-specific CD8 T-cells. CD8 T-cells specific for the high-affinity K^b/B_22–29- (but not the low-affinity K^b/A_12–21)-epitope thus require stimulatory ´help from beta cells or inflamed islets to expand in PD-L1-deficient mice. The new PD-1/PD-L1 diabetes models may be valuable tools to study under well controlled experimental conditions distinct hierarchies of autoreactive CD8 T-cell responses, which trigger the initial steps of beta cell destruction or emerge during the pathogenic progression of EAD.

PD-L1 blockade overrides Salmonella typhimurium-mediated diabetes prevention in NOD mice: no role for Tregs

Increasingly, evidence suggests that there is a strong environmental component to the development of the autoimmune disease type 1 diabetes. Our previous data showed that NOD mice are protected from developing diabetes after infection with Salmonella typhimurium and there is some evidence that changes within the DC compartment play a crucial role in this protective effect. This paper further characterises this Salmonella-modulated protective phenotype. We find that, contrary to other infection-mediated models of type 1 diabetes protection, there was no expansion of Foxp3(+) Tregs. Furthermore, transcriptome analysis of DCs identified a distinct Salmonella-induced signature in which the inhibitory receptor PD-L1 was up-regulated. This was confirmed by flow cytometry. In vivo blockade of the PD1/PD-L1 interaction was found to ablate the protective function of Salmonella infection. These data provide evidence for a novel regulatory DC phenotype proficient at controlling autoreactive T cells for an extended duration in the NOD mouse model of diabetes.

Critical co-stimulatory pathways in the stability of Foxp3+ Treg cell homeostasis in Type I diabetes

Mechanisms of peripheral tolerance maintain a controlled balance between self-tolerance, protective immunity against a spectrum of non-self antigens, and suppressing pathology in various disorders. CD4(+) regulatory T cells (T(reg)) expressing the Foxp3 transcription factor dominantly control the activity and pathological consequences of a variety of effector T cell lineages in various inflammatory settings. This review will focus on recent advances on the roles of B7 family members in regulating Treg cell development, function and homeostasis during tolerance induction and organ-specific autoimmunity.

The role of co-inhibitory signals in spontaneous tolerance of weakly mismatched transplants

The immune system of female H-2(b) (C57BL/6) mice is a strong responder against the male minor-H antigen. However rejection or acceptance of such weakly mismatched grafts depends on the type of tissue transplanted. The mechanism responsible for such spontaneous graft acceptance, and its relationship to the natural mechanisms of tolerance of self antigens is unknown. Co-inhibitory molecules negatively regulate immune responses, and are important for self tolerance. We examined whether co-inhibitory molecules play a critical role in "spontaneous" allograft tolerance. Naïve or donor sensitized diabetic female C57BL/6 (B6) wild type (WT), PD-1(-/-), and BTLA(-/-) mice were transplanted with freshly isolated syngeneic male islet grafts. The role of co-inhibitors during priming of anti-donor responses and graft challenge was also assessed using monoclonal antibodies targeting co-inhibitory receptors. Among the co-inhibitor (CTLA-4, PD-1) specific antibodies tested, only anti-PD-1 showed some potential to prevent spontaneous acceptance of male islet grafts. All BTLA(-/-) and almost all PD-1(-/-) recipients maintained the ability to spontaneously accept male islet grafts. While spontaneous graft acceptance in naïve recipients was only weakly PD-1 dependent, tolerance induced by the accepted islets was found to be highly PD-1 dependent. Furthermore, spontaneous graft acceptance in pre-sensitized recipients showed an absolute requirement for recipient PD-1 but not BTLA. Thus, the PD-1 pathway, involved in self tolerance, plays a critical role in spontaneous tolerance induced by weakly mismatched grafts in naïve recipients and spontaneous graft acceptance in pre-sensitized recipients.