Glucagon-like peptide 1 receptor is a T cell-negative costimulatory molecule.

Glucagon-like peptide-1 receptor (GLP-1R) is a key regulator of glucose metabolism known to be expressed by pancreatic ß cells. We herein investigated the role of GLP-1R on T lymphocytes during immune response. Our data showed that a subset of T lymphocytes expresses GLP-1R, which is upregulated during alloimmune response, similarly to PD-1. When mice received islet or cardiac allotransplantation, an expansion of GLP-1Rpos T cells occurred in the spleen and was found to infiltrate the graft. Additional single-cell RNA sequencing (scRNA-seq) analysis conducted on GLP-1Rpos and GLP-1Rneg CD3+ T cells unveiled the existence of molecular and functional dissimilarities between both subpopulations, as the GLP-1Rpos are mainly composed of exhausted CD8 T cells. GLP-1R acts as a T cell-negative costimulatory molecule, and GLP-1R signaling prolongs allograft survival, mitigates alloimmune response, and reduces T lymphocyte graft infiltration. Notably, GLP-1R antagonism triggered anti-tumor immunity when tested in a preclinical mouse model of colorectal cancer.

TMEM219 regulates the transcription factor expression and proliferation of beta cells.

Pancreatic beta cells replenishment is considered the next therapeutic option for type 1 diabetes; while stimulating endogenous beta cells proliferation is the "holy grail" for those patients with exhausted beta cell mass. Here we are demonstrating that the pro-apoptotic receptor TMEM219 is expressed in fetal pancreas, in beta cell precursors and in in vitro embryonic-derived endocrine progenitors. TMEM219 signaling negatively regulates beta cells at early stages and induces Caspase 8-mediated cell death. Pharmacological blockade of TMEM219 further rescued beta cell precursor and proliferation markers, and decreased cell death, both in islets and in in vitro-derived endocrine progenitors, allowing for beta cell preservation. While addressing the upstream controlling TMEM219 expression, we determined the TMEM219 miRNet; indeed, one of those miRNAs, miR-129-2, is highly expressed in human islets, particularly in patients at risk or with established type 1 diabetes. miR-129-2 mimic downregulated TMEM219 expression in islets, in in vitro embryonic-derived endocrine progenitors and in highly proliferating insulinoma-derived cells. Moreover, miR-129-2 inhibitor induced a TMEM219 overexpression in insulinoma-derived cells, which restored cell proliferation and functional markers, thus acting as endogenous regulator of TMEM219 expression. The TMEM219 upstream regulator miR129-2 controls the fate of beta cell precursors and may unleash their regenerative potentials to replenish beta cells in type 1 diabetes.

Type 2 diabetes mellitus pharmacological remission with dapagliflozin plus oral semaglutide.

Dapagliflozin, a sodium-glucose co-transporter-2 inhibitor and semaglutide, a glucagon-like peptide 1 receptor agonist, have both demonstrated efficacy in glycemic control, reducing blood pressure, body weight, risk of renal and heart failure in type 2 diabetes mellitus. In this observational, real-world, study we aimed to investigate the efficacy of the combination therapy with those two agents over glycemic control. We thus obtained the data of 1335 patients with type 2 diabetes followed by 11 Diabetes centers in Lombardia, Italy. A group of 443 patients was treated with dapagliflozin alone, the other group of 892 patients was treated with the combination therapy of dapagliflozin plus oral semaglutide. We analyzed changes in glycated hemoglobin from baseline to 6 months of follow-up, as well as changes in fasting glycemia, body weight, body mass index, systolic and diastolic pressure, heart rate, creatinine, estimated glomerular filtration rate and albuminuria. Both groups of patients showed an improvement of glycometabolic control after 6 months of treatment; indeed, the treatment with dapagliflozin plus oral semaglutide showed a reduction of glycated hemoglobin of 1.2% as compared to the 0.5% reduction observed in the dapagliflozin alone group. Significant changes were observed in body mass index, fasting plasmatic glucose, blood pressure, total cholesterol, LDL and albumin to creatinine ratio, with a high rate (55%) of near-normalization of glycated hemoglobin. Our real world data confirmed the potential of the oral combination therapy dapagliflozin with semaglutide in inducing pharmacological remission of type 2 diabetes mellitus.

eATP and autoimmune diabetes.

PURPOSE OF REVIEW: The purine nucleotide adenosine triphosphate (ATP) is released into extracellular spaces as extracellular ATP (eATP) as a consequence of cell injury or death and activates the purinergic receptors. Once released, eATP may facilitate T-lymphocyte activation and differentiation. The purpose of this review is to elucidate the role of ATP-mediated signaling in the immunological events related to type 1 diabetes (T1D). RECENT FINDINGS: T lymphocytes mediate immune response during the onset of T1D and promote pancreatic islet or whole pancreas rejection in transplantation. Recent data suggest a potential role for eATP in early steps of T1D onset and of allograft rejection. In different preclinical experimental models and clinical trials, several drugs targeting purinergic signaling have been employed to abrogate lymphocyte activation and differentiation, thus representing an achievable treatment to prevent/revert T1D or to induce long-term islet allograft function. SUMMARY: In preclinical and clinical settings, eATP-signaling inhibition induces immune tolerance in autoimmune disease and in allotransplantation. In this view, the purinergic system may represent a novel therapeutic target for auto- and allo-immunity.

Benefits and Hurdles of Pancreatic ß-Cell Replacement.

Insulin represents a life-saving treatment in patients with type 1 diabetes, and technological advancements have improved glucose control in an increasing number of patients. Despite this, adequate control is often still difficult to achieve and insulin remains a therapy and not a cure for the disease. ß-cell replacement strategies can potentially restore pancreas endocrine function and aim to maintain normoglycemia; both pancreas and islet transplantation have greatly progressed over the last decades and, in subjects with extreme glycemic variability and diabetes complications, represent a concrete and effective treatment option. Some issues still limit the adoption of this approach on a larger scale. One is represented by the strict selection criteria for the recipient who can benefit from a transplant and maintain the lifelong immunosuppression necessary to avoid organ rejection. Second, with regard to islet transplantation, up to 40% of islets can be lost during hepatic engraftment. Recent studies showed very preliminarily but promising results to overcome these hurdles: the ability to induce ß-cell maturation from stem cells may represent a solution to the organ shortage, and the creation of semi-permeable membranes that envelope or package cells in either micro- or macro- encapsulation strategies, together with engineering cells to be hypo-immunogenic, pave the way for developing strategies without immunosuppression. The aim of this review is to describe the state of the art in ß-cell replacement with a focus on its efficacy and clinical benefits, on the actual limitations and still unmet needs, and on the latest findings and future directions.

Indirect and Direct Effects of SARS-CoV-2 on Human Pancreatic Islets.

Recent studies have shown that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection may induce metabolic distress, leading to hyperglycemia in patients affected by coronavirus disease 19 (COVID-19). We investigated the potential indirect and direct effects of SARS-CoV-2 on human pancreatic islets in 10 patients who became hyperglycemic after COVID-19. Although there was no evidence of peripheral anti-islet autoimmunity, the serum of these patients displayed toxicity on human pancreatic islets, which could be abrogated by the use of anti-interleukin-1ß (IL-1ß), anti-IL-6, and anti-tumor necrosis factor α, cytokines known to be highly upregulated during COVID-19. Interestingly, the receptors of those aforementioned cytokines were highly expressed on human pancreatic islets. An increase in peripheral unmethylated INS DNA, a marker of cell death, was evident in several patients with COVID-19. Pathology of the pancreas from deceased hyperglycemic patients who had COVID-19 revealed mild lymphocytic infiltration of pancreatic islets and pancreatic lymph nodes. Moreover, SARS-CoV-2-specific viral RNA, along with the presence of several immature insulin granules or proinsulin, was detected in postmortem pancreatic tissues, suggestive of ß-cell-altered proinsulin processing, as well as ß-cell degeneration and hyperstimulation. These data demonstrate that SARS-CoV-2 may negatively affect human pancreatic islet function and survival by creating inflammatory conditions, possibly with a direct tropism, which may in turn lead to metabolic abnormalities observed in patients with COVID-19.

Immunogenicity and Safety of SARS-CoV-2 mRNA Vaccines in a Cohort of Patients With Type 1 Diabetes.

Patients with type 1 diabetes (T1D) may develop severe outcomes during coronavirus disease 2019 (COVID-19), but their ability to generate an immune response against the SARS-CoV-2 mRNA vaccines remains to be established. We evaluated the safety, immunogenicity, and glycometabolic effects of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccines in patients with T1D. A total of 375 patients (326 with T1D and 49 subjects without diabetes) who received two doses of the SARS-CoV-2 mRNA vaccines (mRNA-1273, BNT162b2) between March and April 2021 at ASST Fatebenefratelli Sacco were included in this monocentric observational study. Local and systemic adverse events were reported in both groups after SARS-CoV-2 mRNA vaccination, without statistical differences between them. While both patients with T1D and subjects without diabetes exhibited a parallel increase in anti-SARS-CoV-2 spike titers after vaccination, the majority of patients with T1D (70% and 78%, respectively) did not show any increase in the SARS-CoV-2-specific cytotoxic response compared with the robust increase observed in all subjects without diabetes. A reduced secretion of the T-cell-related cytokines interleukin-2 and tumor necrosis factor-α in vaccinated patients with T1D was also observed. No glycometabolic alterations were evident in patients with T1D using continuous glucose monitoring during follow-up. Administration of the SARS-CoV-2 mRNA vaccine is associated with an impaired cellular SARS-CoV-2-specific cytotoxic immune response in patients with T1D.

Pharmacologically Enhanced Regulatory Hematopoietic Stem Cells Revert Experimental Autoimmune Diabetes and Mitigate Other Autoimmune Disorders.

Type 1 diabetes (T1D) is characterized by the loss of immune self-tolerance, resulting in an aberrant immune responses against self-tissue. A few therapeutics have been partially successful in reverting or slowing down T1D progression in patients, and the infusion of autologous hematopoietic stem cells (HSCs) is emerging as an option to be explored. In this study, we proposed to pharmacologically enhance by ex vivo modulation with small molecules the immunoregulatory and trafficking properties of HSCs to provide a safer and more efficacious treatment option for patients with T1D and other autoimmune disorders. A high-throughput targeted RNA sequencing screening strategy was used to identify a combination of small molecules (16,16-dimethyl PGE2 and dexamethasone), which significantly upregulate key genes involved in trafficking (e.g., CXCR4) and immunoregulation (e.g., programmed death ligand 1). The pharmacologically enhanced, ex vivo-modulated HSCs (regulatory HSCs [HSC.Regs]) have strong trafficking properties to sites of inflammation in a mouse model of T1D, reverted autoimmune diabetes in NOD mice, and delayed experimental multiple sclerosis and rheumatoid arthritis in preclinical models. Mechanistically, HSC.Regs reduced lymphocytic infiltration of pancreatic ß cells and inhibited the activity of autoreactive T cells. Moreover, when tested in clinically relevant in vitro autoimmune assays, HSC.Regs abrogated the autoimmune response. Ex vivo pharmacological modulation enhances the immunoregulatory and trafficking properties of HSCs, thus generating HSC.Regs, which mitigated autoimmune diabetes and other autoimmune disorders.

Anti-diabetic drugs and weight loss in patients with type 2 diabetes.

INTRODUCTION: Obesity is frequently a comorbidity of type 2 diabetes. Even modest weight loss can significantly improve glucose homeostasis and lessen cardiometabolic risk factors in patients with type 2 diabetes, but lifestyle-based weight loss strategies are not long-term effective. There is an increasing need to consider pharmacological approaches to assist weight loss in the so called diabesity syndrome. Aim of this review is to analyze the weight-loss effect of non-insulin glucose lowering drugs in patients with type 2 diabetes. MATERIAL AND METHODS: A systematic analysis of the literature on the effect of non-insulin glucose lowering drugs on weight loss in patients with type 2 diabetes was performed. For each class of drugs, the following parameters were analyzed: kilograms lost on average, effect on body mass index and body composition. RESULTS: Our results suggested that anti-diabetic drugs can be stratified into 3 groups based on their efficacy in weight loss: metformin, acarbose, empagliflozin and exenatide resulted in a in a mild weight loss (less than 3.2% of initial weight); canagliflozin, ertugliflozin, dapagliflozin and dulaglutide induces a moderate weight loss (between 3.2% and 5%); liraglutide, semaglutide and tirzepatide resulted in a strong weight loss (greater than 5%). CONCLUSIONS: This study shows that new anti-diabetic drugs, particularly GLP1-RA and Tirzepatide, are the most effective in inducing weight loss in patients with type 2 diabetes. Interestingly, exenatide appears to be the only GLP1-RA that induces a mild weight loss.

Hematopoietic Stem Cells in Type 1 Diabetes.

Despite the increasing knowledge of pathophysiological mechanisms underlying the onset of type 1 diabetes (T1D), the quest for therapeutic options capable of delaying/reverting the diseases is still ongoing. Among all strategies currently tested in T1D, the use of hematopoietic stem cell (HSC)-based approaches and of teplizumab, showed the most encouraging results. Few clinical trials have already demonstrated the beneficial effects of HSCs in T1D, while the durability of the effect is yet to be established. Investigators are also trying to understand whether the use of selected and better-characterized HSCs subsets may provide more benefits with less risks. Interestingly, ex vivo manipulated HSCs showed promising results in murine models and the recent introduction of the humanized mouse models accelerated the translational potentials of such studies and their final road to clinic. Indeed, immunomodulatory as well as trafficking abilities can be enhanced in genetically modulated HSCs and genetically engineered HSCs may be viewed as a novel "biologic" therapy, to be further tested and explored in T1D and in other autoimmune/immune-related disorders.

miR-21 antagonism reprograms macrophage metabolism and abrogates chronic allograft vasculopathy.

Despite much progress in improving graft outcome during cardiac transplantation, chronic allograft vasculopathy (CAV) remains an impediment to long-term graft survival. MicroRNAs (miRNAs) emerged as regulators of the immune response. Here, we aimed to examine the miRNA network involved in CAV. miRNA profiling of heart samples obtained from a murine model of CAV and from cardiac-transplanted patients with CAV demonstrated that miR-21 was most significantly expressed and was primarily localized to macrophages. Interestingly, macrophage depletion with clodronate did not significantly prolong allograft survival in mice, while conditional deletion of miR-21 in macrophages or the use of a specific miR-21 antagomir resulted in indefinite cardiac allograft survival and abrogated CAV. The immunophenotype, secretome, ability to phagocytose, migration, and antigen presentation of macrophages were unaffected by miR-21 targeting, while macrophage metabolism was reprogrammed, with a shift toward oxidative phosphorylation in naïve macrophages and with an inhibition of glycolysis in pro-inflammatory macrophages. The aforementioned effects resulted in an increase in M2-like macrophages, which could be reverted by the addition of L-arginine. RNA-seq analysis confirmed alterations in arginase-associated pathways associated with miR-21 antagonism. In conclusion, miR-21 is overexpressed in murine and human CAV, and its targeting delays CAV onset by reprogramming macrophages metabolism.

Cell therapy for type 1 diabetes.

INTRODUCTION: Type 1 diabetes (T1D) is a lifelong condition resulting from autoimmune destruction of insulin-producing ß-cells. Islet or whole-pancreas transplantation is limited by the shortage of donors and need for chronic immune suppression. Novel strategies are needed to prevent ß-cell loss and to rescue production of endogenous insulin. AREAS COVERED: This review covers the latest advances in cell-based therapies for the treatment and prevention of T1D. Topics include adoptive transfer of cells with increased immunoregulatory potential for ß-cell protection, and ß-cell replacement strategies such as generation of insulin-producing ß-like cells from unlimited sources. EXPERT OPINION: Cell therapy provides an opportunity to prevent or reverse T1D. Adoptive transfer of autologous cells having enhanced immunomodulatory properties can suppress autoimmunity and preserve ß-cells. Such therapies have been made possible by a combination of genome-editing techniques and transplantation of tolerogenic cells. In-vitro modified autologous hematopoietic stem cells and tolerogenic dendritic cells may protect endogenous and newly generated ß-cells from a patient's autoimmune response without hampering immune surveillance for infectious agents and malignant cellular transformations. However, methods to generate cells that meet quality and safety standards for clinical applications require further refinement.

Sitagliptin favorably modulates immune-relevant pathways in human beta cells.

Type 2 diabetes (T2D) is a condition characterized by hyperglycemia and chronic complications. Antidiabetic drugs and lifestyle interventions are the current gold standard therapy for T2D; current therapies, however, can only delay long-term diabetic complications and can additionally be associated with beta cell failure. While the mechanism of beta cell failure is well-studied, little is known about the immunological and inflammatory events associated with antidiabetic agents. Here we studied the effects of three antidiabetic drugs (Metformin, Sitagliptin, and Liraglutide) on immune-relevant pathways in a human beta cell line. Costimulatory molecule expression, cytokine secretion, and gene expression profiles were evaluated at different time points following challenge with the aforementioned antidiabetic agents. Our results showed that these three antidiabetic agents, particularly Sitagliptin, downregulate HLA Class I and II expression and upregulate the immune-regulatory molecules PD-L1 and CTLA4. Metformin and Liraglutide were shown to elicit significantly greater release of TNFa, IL-6, and GM-CSF, while Sitagliptin had a lesser effect on pro-inflammatory cytokine production. Gene expression analysis confirmed the aforementioned observations and also demonstrated upregulation of NOS2, SIRT1, SITR3, POLRMT, MRPL43 and NFkB with antidiabetic agents. We conclude that Sitagliptin most effectively modulates beneficial immune-relevant pathways in a human beta cell line.

Islet-Derived eATP Fuels Autoreactive CD8+ T Cells and Facilitates the Onset of Type 1 Diabetes.

Extracellular ATP (eATP) activates T cells by engaging the P2X7R receptor. We identified two loss-of-function P2X7R mutations that are protective against type 1 diabetes (T1D) and thus hypothesized that eATP/P2X7R signaling may represent an early step in T1D onset. Specifically, we observed that in patients with newly diagnosed T1D, P2X7R is upregulated on CD8+ effector T cells in comparison with healthy control subjects. eATP is released at high levels by human/murine islets in vitro in high-glucose/inflammatory conditions, thus upregulating P2X7R on CD8+ T cells in vitro. P2X7R blockade with oxidized ATP reduces the CD8+ T cell-mediated autoimmune response in vitro and delays diabetes onset in NOD mice. Autoreactive CD8+ T-cell activation is highly dependent upon eATP/P2X7R-mediated priming, while a novel sP2X7R recombinant protein abrogates changes in metabolism and the autoimmune response associated with CD8+ T cells. eATP/P2X7R signaling facilitates the onset of autoimmune T1D by fueling autoreactive CD8+ cells and therefore represents a novel targeted therapeutic for the disorder.

Prostaglandin E2 Stimulates the Expansion of Regulatory Hematopoietic Stem and Progenitor Cells in Type 1 Diabetes.

Hematopoietic stem and progenitor cells (HSPCs) are multipotent stem cells that have been harnessed as a curative therapy for patients with hematological malignancies. Notably, the discovery that HSPCs are endowed with immunoregulatory properties suggests that HSPC-based therapeutic approaches may be used to treat autoimmune diseases. Indeed, infusion with HSPCs has shown promising results in the treatment of type 1 diabetes (T1D) and remains the only "experimental therapy" that has achieved a satisfactory rate of remission (nearly 60%) in T1D. Patients with newly diagnosed T1D have been successfully reverted to normoglycemia by administration of autologous HSPCs in association with a non-myeloablative immunosuppressive regimen. However, this approach is hampered by a high incidence of adverse effects linked to immunosuppression. Herein, we report that while the use of autologous HSPCs is capable of improving C-peptide production in patients with T1D, ex vivo modulation of HSPCs with prostaglandins (PGs) increases their immunoregulatory properties by upregulating expression of the immune checkpoint-signaling molecule PD-L1. Surprisingly, CXCR4 was upregulated as well, which could enhance HSPC trafficking toward the inflamed pancreatic zone. When tested in murine and human in vitro autoimmune assays, PG-modulated HSPCs were shown to abrogate the autoreactive T cell response. The use of PG-modulated HSPCs may thus provide an attractive and novel treatment of autoimmune diabetes.

PD-L1 genetic overexpression or pharmacological restoration in hematopoietic stem and progenitor cells reverses autoimmune diabetes.

Immunologically based clinical trials performed thus far have failed to cure type 1 diabetes (T1D), in part because these approaches were nonspecific. Because the disease is driven by autoreactive CD4 T cells, which destroy ß cells, transplantation of hematopoietic stem and progenitor cells (HSPCs) has been recently offered as a therapy for T1D. Our transcriptomic profiling of HSPCs revealed that these cells are deficient in programmed death ligand 1 (PD-L1), an important immune checkpoint, in the T1D nonobese diabetic (NOD) mouse model. Notably, the immunoregulatory molecule PD-L1 plays a determinant role in controlling/inhibiting activated T cells and thus maintains immune tolerance. Furthermore, our genome-wide and bioinformatic analysis revealed the existence of a network of microRNAs (miRNAs) controlling PD-L1 expression, and silencing one of key altered miRNAs restored PD-L1 expression in HSPCs. We therefore sought to determine whether restoration of this defect would cure T1D as an alternative to immunosuppression. Genetically engineered or pharmacologically modulated HSPCs overexpressing PD-L1 inhibited the autoimmune response in vitro, reverted diabetes in newly hyperglycemic NOD mice in vivo, and homed to the pancreas of hyperglycemic NOD mice. The PD-L1 expression defect was confirmed in human HSPCs in T1D patients as well, and pharmacologically modulated human HSPCs also inhibited the autoimmune response in vitro. Targeting a specific immune checkpoint defect in HSPCs thus may contribute to establishing a cure for T1D.