Search

Aims Alterations of the exocrine pancreas have been reported in type 1 diabetes, but their contribution to the pathogenesis of the disease is poorly understood. Here, we investigated markers of exocrine pancreas dysfunction in individuals at-risk of developing type 1 diabetes. Methods Serum P-amylase and lipase levels were assessed in samples obtained from healthy controls, patients with new onset type 1 diabetes, relatives participating to the TrialNet Pathway to Prevention who were, at blood collection, autoantibody negative or positive for a single autoantibody (low-risk individuals), and positive for multiple autoantibodies (high-risk individuals). Linear mixed models were adopted to estimate variation of pancreatic enzymes among the groups and to evaluate the influence of high-risk HLA genotypes and residual beta cell function on exocrine pancreas function. Results In adults, but not children, reduced levels of P-amylase and lipase were shown in at-risk individuals, including (for P-amylase levels only) those at low-risk, and in T1Dnew. Furthermore, while high-risk HLA genotypes negatively affected P-amylase levels in autoantibody negative adult individuals, fasting C-peptide levels did not correlate with pancreatic enzyme levels. Conclusions Exocrine pancreas dysfunction precedes the onset of type 1 diabetes in adult at-risk individuals and may be unrelated to fasting C-peptide levels.

The clinical diagnosis of new-onset type 1 diabetes has, for many years, been considered relatively straightforward. Recently, however, there is increasing awareness that within this single clinical phenotype exists considerable heterogeneity: disease onset spans the complete age range; genetic susceptibility is complex; rates of progression differ markedly, as does insulin secretory capacity; and complication rates, glycemic control, and therapeutic intervention efficacy vary widely. Mechanistic and immunopathological studies typically show considerable patchiness across subjects, undermining conclusions regarding disease pathways. Without better understanding, type 1 diabetes heterogeneity represents a major barrier both to deciphering pathogenesis and to the translational effort of designing, conducting, and interpreting clinical trials of disease-modifying agents. This realization comes during a period of unprecedented change in clinical medicine, with increasing emphasis on greater individualization and precision. For complex disorders such as type 1 diabetes, the option of maintaining the “single disease” approach appears untenable, as does the notion of individualizing each single patient’s care, obliging us to conceptualize type 1 diabetes less in terms of phenotypes (observable characteristics) and more in terms of disease endotypes (underlying biological mechanisms). Here, we provide our view on an approach to dissect heterogeneity in type 1 diabetes. Using lessons from other diseases and the data gathered to date, we aim to delineate a roadmap through which the field can incorporate the endotype concept into laboratory and clinical practice. We predict that such an effort will accelerate the implementation of precision medicine and has the potential for impact on our approach to translational research, trial design, and clinical management.

Alterations of the exocrine pancreas have been reported in type 1 diabetes, but their contribution to the pathogenesis of the disease is poorly understood. Here, we investigated markers of exocrine pancreas dysfunction in individuals at-risk of developing type 1 diabetes.Serum P-amylase and lipase levels were assessed in samples obtained from healthy controls, patients with new onset type 1 diabetes, relatives participating to the TrialNet Pathway to Prevention who were, at blood collection, autoantibody negative or positive for a single autoantibody (low-risk individuals), and positive for multiple autoantibodies (high-risk individuals). Linear mixed models were adopted to estimate variation of pancreatic enzymes among the groups and to evaluate the influence of high-risk HLA genotypes and residual beta cell function on exocrine pancreas function.In adults, but not children, reduced levels of P-amylase and lipase were shown in at-risk individuals, including (for P-amylase levels only) those at low-risk, and in T1Dnew. Furthermore, while high-risk HLA genotypes negatively affected P-amylase levels in autoantibody negative adult individuals, fasting C-peptide levels did not correlate with pancreatic enzyme levels.Exocrine pancreas dysfunction precedes the onset of type 1 diabetes in adult at-risk individuals and may be unrelated to fasting C-peptide levels.

Purpose of this review is to describe the most recent human studies on neutrophils in type 1 diabetes (T1D) and to focus on the key questions that still need to be addressed.Recent evidences demonstrate that neutrophils have marked abnormalities in phenotype and function and play a central role in initiation and perpetuation of aberrant immune responses and organ damage in various systemic autoimmune diseases such as lupus erythematosus and rheumatoid arthritis. In T1D, we have recently demonstrated that reduced circulating neutrophil numbers precede and accompany the disease and that neutrophils infiltrate the pancreas and extrude neutrophil extracellular traps already before the onset of clinical symptoms. However, few other evidences of alterations in neutrophil phenotype and function have been reported in humans, especially in the T1D presymptomatic phases.Dissecting the pathogenic role of these cells in human T1D is crucial for a better understanding of the disease and to open new therapeutic opportunities.

Thirty years ago, one of the first types of CD4+ T regulatory cells was discovered and named T regulatory type 1 (Tr1) cells. Tr1 cells represent a distinct population of T cells, which are induced in the periphery upon antigen exposure under tolerogenic conditions. They produce the immunosuppressive cytokines interleukin-10 (IL-10) and transforming growth factor-beta (TGF-β), do not constitutively express FOXP3, and suppress the function of effector immune cells. In this review, the key studies leading to the identification and biological characterization of Tr1 cells are recapitulated. The fundamental role of Tr1 cells in regulating immune responses to pathogenic and non-pathogenic antigens, as well as their use as cell therapeutics, is summarized.

In 2001, Fondazione Telethon and the Italian muscular dystrophy patient organisation Unione Italiana Lotta alla Distrofia Muscolare joined their efforts to design and launch a call for grant applications specifically dedicated to clinical projects in the field of neuromuscular disorders. This strategic initiative, run regularly over the years and still ongoing, aims at supporting research with impact on the daily life of people with a neuromuscular condition and is centred on macro-priorities identified by the patient organisation. It is investigator-driven, and all proposals are peer-reviewed for quality and feasibility. Over the years, this funding program contributed to strengthening the activities of the Italian neuromuscular clinical network, reaching many achievements in healthcare research. Moreover, it has been an enabling factor for innovative therapy experimentation at international level and prepared the clinical ground to make therapies available to Italian patients. The ultimate scope of healthcare research is to ameliorate the delivery of care. In this paper, the achievements of the funded studies are analysed also from this viewpoint, to ascertain to which extent they have fulfilled the original goals established by the patient organisation. The evidence presented indicates that this has been a highly fruitful program. Factors that contributed to its success, lessons learned, challenges, and issues that remain to be addressed are discussed to provide practical examples of an experience that could inspire also other organizations active in the field of rare disease research.

In the attempt to understand the origin of autoantibody (AAb) production in patients with and at-risk for T1D, multiple studies have analyzed and reported alterations in follicular helper T cells (Tfh) in presymptomatic AAb-positive subjects and patients with T1D. Yet, it is still not clear whether the regulatory counterpart of Tfh cells, represented by follicular regulatory T cells (Tfr), is similarly altered. To address this question, we performed analyses in peripheral blood, spleen and pancreatic lymph nodes (PLN) of organ donor subjects with T1D. Blood analyses were also performed in living AAb-negative and -positive subjects. While negligible differences in the frequency and phenotype of blood Tfr cells were observed between T1D, AAb-negative and AAb-positive adult subjects, the frequency of Tfr cells was significantly reduced in spleen and PLN of T1D as compared to non-diabetic controls. Furthermore, adoptive transfer of Tfr cells delayed disease development in a mouse model of T1D, a finding that could indicate that Tfr cells play an important role in peripheral tolerance and regulation of autoreactive Tfh cells. Together, our findings provide evidence of Tfr cell alterations within disease-relevant tissues in patients with T1D suggesting a role for Tfr cells in defective humoral tolerance and disease pathogenesis.

Transient partial remission, a period of low insulin requirement experienced by most patients soon after diagnosis, has been associated with mechanisms of immune regulation. A better understanding of such natural mechanisms of immune regulation might identify new targets for immunotherapies that reverse type 1 diabetes (T1D). In this study, using Cox model multivariate analysis, we validated our previous findings that patients with the highest frequency of CD4+CD25+CD127hi (127-hi) cells at diagnosis experience the longest partial remission, and we showed that the 127-hi cell population is a mix of Th1- and Th2-type cells, with a significant bias toward antiinflammatory Th2-type cells. In addition, we extended these findings to show that patients with the highest frequency of 127-hi cells at diagnosis were significantly more likely to maintain β cell function. Moreover, in patients treated with alefacept in the T1DAL clinical trial, the probability of responding favorably to the antiinflammatory drug was significantly higher in those with a higher frequency of 127-hi cells at diagnosis than those with a lower 127-hi cell frequency. These data are consistent with the hypothesis that 127-hi cells maintain an antiinflammatory environment that is permissive for partial remission, β cell survival, and response to antiinflammatory immunotherapy.

Background:Use of cell-based medicinal products (CBMPs) represents a state-of-the-art approach for reducing general immunosuppression in organ transplantation. We tested multiple regulatory CBMPs in kidney transplant trials to establish the safety of regulatory CBMPs when combined with reduced immunosuppressive treatment. Methods:The ONE Study consisted of seven investigator-led, single-arm trials done internationally at eight hospitals in France, Germany, Italy, the UK, and the USA (60 week follow-up). Included patients were living-donor kidney transplant recipients aged 18 years and older. The reference group trial (RGT) was a standard-of-care group given basiliximab, tapered steroids, mycophenolate mofetil, and tacrolimus. Six non-randomised phase 1/2A cell therapy group (CTG) trials were pooled and analysed, in which patients received one of six CBMPs containing regulatory T cells, dendritic cells, or macrophages; patient selection and immunosuppression mirrored the RGT, except basiliximab induction was substituted with CBMPs and mycophenolate mofetil tapering was allowed. None of the trials were randomised and none of the individuals involved were masked. The primary endpoint was biopsy-confirmed acute rejection (BCAR) within 60 weeks after transplantation; adverse event coding was centralised. The RTG and CTG trials are registered withClinicalTrials.gov,NCT01656135,NCT02252055,NCT02085629,NCT02244801,NCT02371434,NCT02129881, andNCT02091232. Findings:The seven trials took place between Dec 11, 2012, and Nov 14, 2018. Of 782 patients assessed for eligibility, 130 (17%) patients were enrolled and 104 were treated and included in the analysis. The 66 patients who were treated in the RGT were 73% male and had a median age of 47 years. The 38 patients who were treated across six CTG trials were 71% male and had a median age of 45 years. Standard-of-care immunosuppression in the recipients in the RGT resulted in a 12% BCAR rate (expected range 3·2–18·0). The overall BCAR rate for the six parallel CTG trials was 16%. 15 (40%) patients given CBMPs were successfully weaned from mycophenolate mofetil and maintained on tacrolimus monotherapy. Combined adverse event data and BCAR episodes from all six CTG trials revealed no safety concerns when compared with the RGT. Fewer episodes of infections were registered in CTG trials versus the RGT. Interpretation:Regulatory cell therapy is achievable and safe in living-donor kidney transplant recipients, and is associated with fewer infectious complications, but similar rejection rates in the first year. Therefore, immune cell therapy is a potentially useful therapeutic approach in recipients of kidney transplant to minimise the burden of general immunosuppression.

Summary T regulatory type 1 (Tr1) cells are a class of regulatory T cells (Tregs) participating in peripheral tolerance, hence the rationale behind their testing in clinical trials in different disease settings. One of their applications is tolerance induction to allogeneic islets for long-term diabetes-free survival. Currently the cellular and molecular mechanisms that promote Tr1-cell induction in vivo remain poorly understood. We employed a mouse model of transplant tolerance where treatment with granulocyte colony-stimulating factor (G-CSF)/rapamycin induces permanent engraftment of allogeneic pancreatic islets in C57BL/6 mice via Tr1 cells. The innate composition of graft and spleen cells in tolerant mice was analyzed by flow cytometry. Graft phagocytic cells were co-cultured with CD4+ T cells in vitro to test their ability to induce Tr1-cell induction. Graft phagocytic cells were depleted in vivo at different time-points during G-CSF/rapamycin treatment, to identify their role in Tr1-cell induction and consequently in graft survival. In the spleen, the site of Tr1-cell induction, no differences in the frequencies of macrophages or dendritic cells (DC) were observed. In the graft, the site of antigen uptake, a high proportion of macrophages and not DC was detected in tolerant but not in rejecting mice. Graft-infiltrating macrophages of G-CSF/rapamycin-treated mice had an M2 phenotype, characterized by higher CD206 expression and interleukin (IL)-10 production, whereas splenic macrophages only had an increased CD206 expression. Graft-infiltrating cells from G-CSF/rapamycin-treated mice-induced Tr1-cell expansion in vitro. Furthermore, Tr1-cell induction was perturbed upon in-vivo depletion of phagocytic cells, early and not late during treatment, leading to graft loss suggesting that macrophages play a key role in tolerance induction mediated by Tr1 cells. Taken together, in this mouse model of Tr1-cell induced tolerance to allogeneic islets, M2 macrophages infiltrating the graft upon G-CSF/rapamycin treatment are key for Tr1-cell induction. This work provides mechanistic insight into pharmacologically induced Tr1-cell expansion in vivo in this stringent model of allogeneic transplantation.

Tr1 cell therapy is considered an emerging approach to improve transplant tolerance and enhance allogeneic graft survival. However, it remains unclear how Tr1 cells promote transplant tolerance and whether they will be safe and stable in the face of an acute viral infection. By employing a mouse model of pancreatic islet transplantation, we report that Tr1 cell therapy promoted transplant tolerance via de novo induction of Tr1 cells in the recipients. Acute viral infection with lymphocytic choriomeningitis virus (LCMV) had no impact on Tr1 cell number and function, neither on the Tr1 cells infused nor on the ones induced, and that was reflected in the robust maintenance of the graft. Moreover, Tr1 cell immunotherapy had no detrimental effect on CD8 and CD4 anti-LCMV effector T-cell responses and viral control. Together, these data suggest that Tr1 cells did not convert to effector cells during acute infection with LCMV, maintained transplant tolerance and did not inhibit antiviral immunity.

International audience; Type 1 diabetes (T1D) is an autoimmune disease characterized by the selective destruction of pancreatic islet β-cells that produce insulin, in the context of an underlying multigenetic inheritance 1. When most of the β-cells are destroyed or non-functional, the ensuing lack of insulin results in hyperglycemia and requires lifelong insulin-replacement therapy 1. The physiopathology of T1D involves inappropriate activation of both the innate immune system and adaptive immune system, which induces loss of self-tolerance and islet destruction 2-5. T1D is characterized by the presence of anti-islet autoantibodies and auto-reactive T cells. Innate immune cells are involved at various stages of the disease and are particularly important for the initiation of the local immune response in the pancreas and the pancreatic lymph nodes (PLNs) 2,4. Published data have highlighted the role of the intestinal microbiota in T1D by transfer experiments in mice of the non-obese diabetic (NOD) strain 6-8 and gut microbiota differences in children that are associated with the development of T1D 9-11. Several studies have also described alterations to the gut mucosa in NOD mice and patients with T1D 12-16. Mucosal-associated invariant T cells (MAIT cells) are innate-like T cells that recognize bacterial metabolites derived from the synthesis of riboflavin and presented by the monomorphic major histocompatibility complex (MHC) class-I-related protein MR1 (refs. 17-19). These non-conventional T cells express a conserved αβ T cell antigen receptor (TCR) that consists of an invariant TCR α-chain (α-chain variable region 7.2 and α-chain joining regions 33, 20 and12 (V α 7.2-J α 33,20,12) in humans and V α 19-J α 33 in mice) with a restricted set of TCR β-chains. MAIT cells produce various cytokines, such as TNF, IFN-γ, IL-17 and granzyme B (GzB), that participate in tissue inflammation and cell death 17,20-28. The nearly complete absence of MAIT cells in germ-free mice 17,29 and their physiological localization at mucosal sites, including the gut 17,21 , suggest a strong interaction with the microbiota. Here we found alterations in MAIT cells in patients with T1D and, through the use of NOD mice, revealed a protective role for MAIT cells directed against T1D. The localization and function of MAIT cells highlight their key role in the maintenance of gut integrity whereby they control the development of autoimmune responses to pancreatic β-cells. RESULTS Alterations in MAIT cells in children with recent-onset T1D We first began our investigation of MAIT cells in T1D by analyzing the frequency and phenotype of MAIT cells in fresh peripheral Type 1 diabetes (T1D) is an autoimmune disease that results from the destruction of pancreatic b-cells by the immune system that involves innate and adaptive immune cells. Mucosal-associated invariant T cells (MAIT cells) are innate-like T-cells that recognize derivatives of precursors of bacterial riboflavin presented by the major histocompatibility complex (MHC) class I-related molecule MR1. Since T1D is associated with modification of the gut microbiota, we investigated MAIT cells in this pathology. In patients with T1D and mice of the non-obese diabetic (NOD) strain, we detected alterations in MAIT cells, including increased production of granzyme B, which occurred before the onset of diabetes. Analysis of NOD mice that were deficient in MR1, and therefore lacked MAIT cells, revealed a loss of gut integrity and increased anti-islet responses associated with exacerbated diabetes. Together our data highlight the role of MAIT cells in the maintenance of gut integrity and the control of anti-islet autoimmune responses. Monitoring of MAIT cells might represent a new biomarker of T1D, while manipulation of these cells might open new therapeutic strategies.

Background Here, we isolated, expanded and functionally characterized regulatory T cells (Tregs) from patients with end stage kidney and liver disease, waiting for kidney/liver transplantation (KT/LT), with the aim to establish a suitable method to obtain large numbers of immunomodulatory cells for adoptive immunotherapy post-transplantation. Methods We first established a preclinical protocol for expansion/isolation of Tregs from peripheral blood of LT/KT patients. We then scaled up and optimized such protocol according to good manufacturing practice (GMP) to obtain high numbers of purified Tregs which were phenotypically and functionally characterized in vitro and in vivo in a xenogeneic acute graft-versus-host disease (aGVHD) mouse model. Specifically, immunodepressed mice (NOD-SCID-gamma KO mice) received human effector T cells with or without GMP-produced Tregs to prevent the onset of xenogeneic GVHD. Results Our small scale Treg isolation/expansion protocol generated functional Tregs. Interestingly, cryopreservation/thawing did not impair phenotype/function and DNA methylation pattern of FOXP3 gene of the expanded Tregs. Fully functional Tregs were also isolated/expanded from KT and LT patients according to GMP. In the mouse model, GMP Tregs from LT or KT patient proved to be safe and show a trend toward reduced lethality of acute GVHD. Conclusions These data demonstrate that expanded/thawed GMP-Tregs from patients with end-stage organ disease are fully functional in vitro. Moreover, their infusion is safe and results in a trend toward reduced lethality of acute GVHD in vivo, further supporting Tregs-based adoptive immunotherapy in solid organ transplantation. Electronic supplementary material The online version of this article (10.1186/s12967-019-2004-2) contains supplementary material, which is available to authorized users.

Autoantibodies (AAbs) are a hallmark of Type 1 diabetes (T1D). Alterations in the frequency and phenotype of follicular helper (Tfh) T cells have been previously documented in patients with type 1 diabetes (T1D), but the contribution of follicular regulatory T (Treg) cells, which are responsible for suppressing AAb development, is less clear. Here, we investigated the frequency and activation status of follicular (CXCR5

PTPN22 (protein tyrosine phosphatase non receptor 22) encodes a tyrosine phosphatase that functions as a key regulator of immune homeostasis. In particular, PTPN22 inhibits T-cell receptor signaling and selectively promotes type I interferon responses in myeloid cells. To date, there is little information on the CD8 T-cell-intrinsic role of PTPN22 in response to a viral pathogen. We unexpectedly found that PTPN22-deficient virus-specific CD8 T cells failed to accumulate in wild-type hosts after lymphocytic choriomeningitis virus infection. Lack of PTPN22 expression altered CD8 T-cell activation and antiviral cytokine production, but did not significantly affect the composition of effector and memory cell precursors. Most significantly, in vivo, PTPN22-deficient CD8 T cells showed a profound defect in upregulating STAT-1 after lymphocytic choriomeningitis virus infection and considerably less phosphorylation of STAT-1 in response to IFN-α treatment in vitro compared with their wild-type counterparts. In stark contrast, following transfer into lymphopenic mice, CD8 T-cell expansion and central-like phenotype, was considerably increased in the absence of PTPN22. Collectively, our results suggest that PTPN22 has dual roles in T-cell clonal expansion and effector function; whereas it promotes antigen-driven responses during acute infection by positively regulating interferon signaling in T cells, PTPN22 inhibits homeostatic-driven proliferation.

The evolution of Type 1 diabetes (T1D) therapy has been marked by consecutive shifts, from insulin replacement to immunosuppressive drugs and targeted biologics (following the understanding that T1D is an autoimmune disease), and to more disease-specific or patient-oriented approaches such as antigen-specific and cell-based therapies, with a goal to provide efficacy, safety, and long-term protection. At the same time, another important paradigm shift from treatment of new onset T1D patients to prevention in high-risk individuals has taken place, based on the hypothesis that therapeutic approaches deemed sufficiently safe may show better efficacy if applied early enough to maintain endogenous β cell function, a concept supported by many preclinical studies. This new strategy has been made possible by capitalizing on a variety of biomarkers that can more reliably estimate the risk and rate of progression of the disease. More advanced (“omic”-based) biomarkers that also shed light on the underlying contributors of disease for each individual will be helpful to guide the choice of the most appropriate therapies, or combinations thereof. In this review, we present current efforts to stratify patients according to biomarkers and current alternatives to conventional drug-based therapies for T1D, with a special emphasis on cell-based therapies, their status in the clinic and potential for treatment and/or prevention.

Translational medicine works through the definition of unmet medical needs, their understanding and final resolution. In this complex and multi-disciplinary process patients have always been regarded as "end-users" or no more than "data provider." Considering that the translational practice is nowadays highly inefficient (i.e., large intellectual and economical resources are wasted with limited impact on people health) here we propose to reverse the process: start from patients, engage them, and keep them at the center. A new partnership needs to be formed between the patients and the health care professionals, as well as the treating physicians, to make the most out of the current "health resources." New patient-centric approaches are emerging but they remain isolated phenomena often difficult to implement. Here-with this perspective-we aim at thinking differently and learning from new experiences. We will provide some successful examples of change, and we will discuss new approaches to create a radical change in the way translational medicine is managed and how this would significantly impact people health and health care systems.

Stage 1, defined as having ≥2 (i.e., multiple) autoantibodies (MA+) with normoglycemia, is currently identified as the earliest pathogenetic phase of type 1 diabetes. There is limited information of a possible β-cell function decline during the preceding phase, defined as single autoantibody positivity (SA+). Therefore, we evaluated metabolic measures at time of SA+ determination and assessed their predictive value for progression to MA+. Relatives participating in the TrialNet prospective Pathway to Prevention with SA+ (GADA, IAA, or IA-2A) were studied. Time from SA+ to MA+ was analyzed to assess risk of conversion. Measures evaluated during OGTT included: mean AUC for C-peptide, glucose, and insulin; fasting glucose and C-peptide; early insulin and C-peptide responses (30-0 min); peak C-peptide; glucose and C-peptide sums (30 to 120 min) and Index60 (incorporating fasting C-peptide, 1-hour glucose, and 1-hour C-peptide). Clinical factors included age, sex, ethnicity and autoantibody type. Of the 2,265 subjects identified as SA+, 57% were female, 83% white, 14% hispanic, with a median age of 14.8 years (range: 1.0 to 48.7 years). Most (71%) had GADA, 25% IAA and 4% IA-2A; 68% were tested also for ZnT8A. Overall, 407 (18%) SA+ progressed to MA+ during a median follow-up of 1.8 years. Adjusting for age, sex, and ethnicity we found that higher levels of mean AUC glucose (HR=2.4, p=0.004) significantly increased risk of progression to MA+. Index60 was significant both continuous (HR=1.17, p=0.004) and dichotomized (≥1 vs. Disclosure E. Bosi: Consultant; Self; Abbott, AstraZeneca, Lexicon Pharmaceuticals, Inc., LifeScan, Inc.. Employee; Spouse/Partner; LifeScan, Inc.. Consultant; Self; Medtronic, Merck Sharp & Dohme Corp., Novartis AG, Roche Diabetes Care Health and Digital Solutions, Sanofi. S. Geyer: None. J. Sosenko: None. D.J. Becker: None. M. Battaglia: None. H.M. Ismail: None. M.A. Atkinson: Other Relationship; Self; Patent Issued. L.H. Philipson: Research Support; Self; Novo Nordisk Inc.. Speaker's Bureau; Self; Merck & Co., Inc.. Research Support; Self; JAEB Center For Health Research, JDRF, Janssen Pharmaceuticals, Inc., Medtronic MiniMed, Inc.. J.P. Palmer: None. C. Evans-Molina: None.

International audience; The human leukocyte antigen-A2 (HLA-A2)-restricted zinc transporter 8186-194 (ZnT8186-194) and other islet epitopes elicit interferon-γ secretion by CD8+ T cells preferentially in type 1 diabetes (T1D) patients compared with controls. We show that clonal ZnT8186-194-reactive CD8+ T cells express private T cell receptors and display equivalent functional properties in T1D and healthy individuals. Ex vivo analyses further revealed that CD8+ T cells reactive to ZnT8186-194 and other islet epitopes circulate at similar frequencies and exhibit a predominantly naïve phenotype in age-matched T1D and healthy donors. Higher frequencies of ZnT8186-194-reactive CD8+ T cells with a more antigen-experienced phenotype were detected in children versus adults, irrespective of disease status. Moreover, some ZnT8186-194-reactive CD8+ T cell clonotypes were found to cross-recognize a Bacteroides stercoris mimotope. Whereas ZnT8 was poorly expressed in thymic medullary epithelial cells, variable thymic expression levels of islet antigens did not modulate the peripheral frequency of their cognate CD8+ T cells. In contrast, ZnT8186-194-reactive cells were enriched in the pancreata of T1D patients versus nondiabetic and type 2 diabetic individuals. Thus, islet-reactive CD8+ T cells circulate in most individuals but home to the pancreas preferentially in T1D patients. We conclude that the activation of this common islet-reactive T cell repertoire and progression to T1D likely require defective peripheral immunoregulation and/or a proinflammatory islet microenvironment.

Tr1 cell therapy is considered an emerging approach to improve transplant tolerance and enhance allogeneic graft survival. However, it remains unclear how Tr1 cells promote transplant tolerance and whether they will be safe and stable in the face of an acute viral infection. By employing a mouse model of pancreatic islet transplantation, we report that Tr1 cell therapy promoted transplant tolerance via de novo induction of Tr1 cells in the recipients. Acute viral infection with lymphocytic choriomeningitis virus (LCMV) had no impact on Tr1 cell number and function, neither on the Tr1 cells infused nor on the ones induced, and that was reflected in the robust maintenance of the graft. Moreover, Tr1 cell immunotherapy had no detrimental effect on CD8 and CD4 anti-LCMV effector T-cell responses and viral control. Together, these data suggest that Tr1 cells did not convert to effector cells during acute infection with LCMV, maintained transplant tolerance and did not inhibit antiviral immunity.

BACKGROUND. Neutrophils and their inflammatory mediators are key pathogenic components in multiple autoimmune diseases, while their role in human type 1 diabetes (T1D), a disease that progresses sequentially through identifiable stages prior to the clinical onset, is not well understood. We previously reported that the number of circulating neutrophils is reduced in patients with T1D and in presymptomatic at-risk subjects. The aim of the present work was to identify possible changes in circulating and pancreas-residing neutrophils throughout the disease course to better elucidate neutrophil involvement in human T1D. METHODS. Data collected from 389 subjects at risk of developing T1D, and enrolled in 4 distinct studies performed by TrialNet, were analyzed with comprehensive statistical approaches to determine whether the number of circulating neutrophils correlates with pancreas function. To obtain a broad analysis of pancreas-infiltrating neutrophils throughout all disease stages, pancreas sections collected worldwide from 4 different cohorts (i.e., nPOD, DiViD, Siena, and Exeter) were analyzed by immunohistochemistry and immunofluorescence. Finally, circulating neutrophils were purified from unrelated nondiabetic subjects and donors at various T1D stages and their transcriptomic signature was determined by RNA sequencing. RESULTS. Here, we show that the decline in β cell function is greatest in individuals with the lowest peripheral neutrophil numbers. Neutrophils infiltrate the pancreas prior to the onset of symptoms and they continue to do so as the disease progresses. Of interest, a fraction of these pancreas-infiltrating neutrophils also extrudes neutrophil extracellular traps (NETs), suggesting a tissue-specific pathogenic role. Whole-transcriptome analysis of purified blood neutrophils revealed a unique molecular signature that is distinguished by an overabundance of IFN-associated genes; despite being healthy, said signature is already present in T1D-autoantibody-negative at-risk subjects. CONCLUSIONS. These results reveal an unexpected abnormality in neutrophil disposition both in the circulation and in the pancreas of presymptomatic and symptomatic T1D subjects, implying that targeting neutrophils might represent a previously unrecognized therapeutic modality. FUNDING. Juvenile Diabetes Research Foundation (JDRF), NIH, Diabetes UK.