Destruction Of Pancreatic Beta Cells Research Articles

Insulin-degrading enzyme regulates insulin-directed cellular autoimmunity in murine type 1 diabetes

Type 1 diabetes results from the destruction of pancreatic beta cells by autoreactive T cells. As an autoantigen with extremely high expression in beta cells, insulin triggers and sustains the autoimmune CD4+ and CD8+ T cell responses and islet inflammation. We have previously shown that deficiency for insulin-degrading enzyme (IDE), a ubiquitous cytosolic protease with very high affinity for insulin, induces endoplasmic reticulum (ER) stress and proliferation in islet cells and protects non-obese diabetic mice (NOD) from diabetes. Here we wondered whether IDE deficiency affects autoreactive CD8+ T cell responses to insulin and thereby immune pathogenesis in NOD mice. We find that Ide-/- NOD harbor fewer diabetogenic T cells and reduced numbers of CD8+ T cells recognizing the dominant autoantigen insulin and islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP). Using in vitro digestions and cellular antigen presentation assays, we show that generation of the dominant insulin epitope B15-23 involves both the proteasome and IDE. IDE deficiency attenuates MHC-I presentation of the immunodominant insulin epitope by beta cells to cognate CD8+ T cells. Consequently, Ide-/- islets display reduced susceptibility to autoimmune destruction upon grafting, and to killing by insulin-specific CD8+ T cells. Moreover, Ide-/- mice are partly resistant to disease transfer by CD8+ T cells specific for insulin but not for IGRP. Thus, IDE has a dual role in beta cells, regulating ER stress and proliferation while at the same time promoting insulin-directed autoreactive CD8+ T cell responses.

Shifting the paradigm of type 1 diabetes: a narrative review of disease modifying therapies

A new diagnosis of type 1 diabetes (T1D) may be accompanied by numerous lifelong financial, emotional, and physical challenges, thus advancements in therapies that can delay the onset of clinical disease are crucial. T1D is an autoimmune condition involving destruction of pancreatic beta cells leading to insulin deficiency, hyperglycemia, and long-term insulin dependence. The pathogenesis of T1D is classified into stages, with the first signal being the detection of autoantibodies without any glycemic changes. In the second stage, dysglycemia develops without symptoms, and in stage 3, symptoms of hyperglycemia become apparent, and at this time a clinical diagnosis of T1D is made. As a greater understanding of these stages of T1D have evolved, research efforts have been devoted to delaying the onset of clinical disease. To date, only one medication, teplizumab, has been approved by the Food and Drug Administration (FDA) for the treatment of stage 2 T1D. This narrative review present published trials and ongoing research on disease modifying therapies (DMT) in T1D, the mechanisms of action for each therapy, and the stages of T1D that these interventions are being studied.

Challenges in Beta Cell Replacement for Type 1 Diabetes.

Type 1 diabetes (T1D) presents a significant global health challenge, characterized by immune-mediated destruction of pancreatic beta-cells. Achieving therapeutic goals such as prevention of immune destruction, preservation of beta-cell mass, and automated insulin delivery remains complex due to the disease's heterogeneity. This review explores the advancements and challenges in beta-cell replacement therapies, including pancreas and islet cell transplantation, stem cell-derived β-cell generation, and biotechnological innovations. Pancreas transplantation, especially simultaneous pancreas and kidney transplantation (SPK), has evolved significantly, offering insulin independence and improved quality of life despite surgical and immunological complications. Allogeneic islet transplantation, though less invasive, faces challenges such as donor scarcity, immunosuppressive therapy, and variable long-term success. Innovations in stem cell therapy, particularly using human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs), promise an unlimited source of β-cells. However, translating these advances into clinical applications involves overcoming technical, biological, and ethical hurdles. Strategies such as immunomodulation, encapsulation, and genetic engineering are critical to enhancing the viability and integration of transplanted cells. This review provides a comprehensive overview of the scientific intricacies and potential of β-cell replacement therapies, emphasizing the need for continued research to address the remaining challenges and improve diabetes care outcomes.

Type I Diabetes Mellitus impairs cytotoxic immunity through CEACAM5 upregulation in colorectal cancer : Exploring the intersection of autoimmune dysfunction and cancer progression: the role of NF-κB p65 in colorectal cancer.

Type 1 diabetes (T1D) is characterized by an autoimmune-mediated destruction of pancreatic beta cells and a chronic inflammatory state, which may influence the progression of colorectal cancer (CRC) through immune system dysregulation and enhanced tumor immune evasion. This study aims to elucidate the role of p65 in modulating the tumor microenvironment in CRC within the context of T1D and to determine how this modulation affects tumor growth, immune cell infiltration, and the expression of immune evasion molecules such as CEACAM5. NOD mice, which model T1D, were inoculated with MC38 colon carcinoma cells engineered to knock down p65. Tumor growth was monitored, and the tumor microenvironment was analyzed using flow cytometry to assess the infiltration of immune cells. The expression of Ki-67 and CEACAM5 in tumor cells was also evaluated. Additionally, in vitro assays were conducted to study the proliferation and activation of T cells co-cultured with tumor cells. Knockdown of p65 in tumor cells significantly inhibited tumor growth in NOD mice. This was accompanied by an increased infiltration of cytotoxic CD8+ T cells and no significant change in CD4+ or Foxp3 + T regulatory cells within the tumor microenvironment. There was a notable reduction in the expression of Ki-67 and CEACAM5, indicating decreased proliferation and potential immune evasion capabilities of the tumor cells. Our findings demonstrate that the NF-κB p65 subunit plays a crucial role in promoting tumor growth and modulating the immune microenvironment in CRC, particularly in the context of T1D. Knocking down p65 not only reduces tumor progression but also enhances the anti-tumor immune response by decreasing immune evasion mechanisms. These results suggest that targeting the NF-κB pathway may be a viable strategy to improve the efficacy of cancer immunotherapy, especially in patients with autoimmune diseases like T1D. Physical activity enhances the effect of immune checkpoint blockade by inhibiting the intratumoral HIF1-α/CEACAM5 axis.

6745 Complete Remission of Type 1 Diabetes and the Honeymoon Phase: A Case Report

Abstract Disclosure: D. Krinsky: None. E. Brutsaert: None. J.A. Mullally: None. Introduction: Type 1 Diabetes (T1D) is a chronic autoimmune disease resulting in insulin deficiency from pancreatic beta-cell destruction. Recent evidence suggests that it can be a partially relapsing and remitting disease, with some patients with T1D being able to briefly discontinue insulin early in the disease course. This phenomenon has been referred to as the “honeymoon phase.” While this period tends to be short, on the order of weeks to months, we describe a unique case of a patient with T1D with a long remission, lasting about five years. Clinical Case A 21-year-old Mexican-American male (BMI 26) with past medical history of T1D presented with polyuria and a 50-pound unintentional weight loss over a 6-month period. He was first diagnosed with T1D at age 14 years when his Hemoglobin A1c (HbA1C) was 13.3% (normal range 4.0-5.6%) in the setting of hospitalization for diabetic ketoacidosis (DKA). All antibody testing done at that time was negative, but islet cell antibodies were later found to be positive. Insulin therapy was started, weaned, and then completely discontinued at age 16 when the patient’s HbA1c was normal at 5%. The patient had no symptoms of diabetes until 6 months prior to presenting, seven years after his original diagnosis. He was found to be in DKA with a HbA1c >14%. Additionally, insulin (< 3.0; normal range 6-27) and c-peptide (0.43; normal range 0.81-3.85) were low with an elevated glucose of 366. Insulin autoantibody, GAD-65 antibody, and islet cell antibody were negative. His DKA resolved and he was discharged on basal and nutritional insulin. Conclusion: The physiology of the honeymoon phase is not well understood and there is not a clear definition, although stimulated C-peptide levels, insulin requirements, and calculating insulin dose adjusted A1c (IDAA1c) have been commonly used. There is variability in reports of the prevalence of partial remission (PR), estimated to occur in 22-60% of patients, with an average duration of 9 months. Our case is unique in that the patient was diagnosed with T1D at the age of 14 years but was able to discontinue all insulin for five years. His presentation is consistent with a complete remission with insulin independence and normal glycemic control (HbA1C <6%) without the use of hypoglycemic agents. Complete remission has a prevalence of only 6.5%. Prior data has shown factors associated with diabetes remission include male sex, postpubescent age of diabetes onset, and fewer than two positive antibodies; factors seen with our patient. Our case highlights a very long remission of T1D, and a better understanding of the immunologic and metabolic factors at play in the honeymoon phase may pave the way for novel T1D prevention and treatment strategies. Presentation: 6/2/2024

8439 Targeting Interferon Gamma-Mediated CXCL16-CXCR6 Chemokine-Receptor Interactions As A Strategy To Prevent Immune Checkpoint Inhibitor Autoimmune Diabetes

Abstract Disclosure: S. Wang: None. N. Huang: None. J.G. Ortega: None. J. Lee: None. K. Kimbrell: None. J. Nguyen: None. J. Olay: None. E. McCarthy: None. E. Peluso: None. H. Chen: None. M.G. Lechner: None. Autoimmune diabetes mellitus is a rare but life-threatening side effect of immune checkpoint inhibitor (ICI) cancer therapy. Checkpoint inhibitors increase immune activation by blocking regulatory molecules on T cells, including programmed death protein (PD1). As a result of this heightened immune activation, patients can develop autoimmunity in healthy tissues, known as immune related adverse events (IRAEs). ICI-associated diabetes mellitus (ICI-T1DM) is an IRAE that results in autoimmune destruction of insulin-producing pancreatic beta-cells. Patients with ICI-T1DM require life-long insulin therapy and more than half present initially with diabetic ketoacidosis. Unfortunately, the mechanism of this IRAE is not fully understood. Anti-PD1 antibody treatment (10mg/kg/dose, twice weekly, i.p.) of male and female non-obese diabetic (NOD) mice leads to autoimmune infiltrates in multiple tissues, including accelerated insulitis and DM. Single cell RNA sequencing of islet infiltrating immune cells from ICI-treated mice previously showed a role for CD8+ T cells and cytokine interferon gamma (IFNγ) in the development of ICI-T1DM. Using CellChat to perform receptor-ligand interaction analysis of these data, we identified both CD8+ and CD4+ T cells as the primary source of IFNγ in immune infiltrates and islet myeloid cells as the primary target. Furthermore, CellChat analysis showed increased receptor-ligand interactions between T cell receptor CXCR6 and its chemokine CXCL16, as well as CXCR3 and chemokines CXCL9 and CXCL10. In vitro IFNγ stimulation of myeloid cells induced strong expression of CXCL16, 9, and 10, suggesting a potential mechanism by which effector T cells are recruited to islets during ICI therapy. Immunophenotyping of islet-infiltrating immune cells indeed showed increased IFNγ+CXCR6+ effector CD8+ cells in anti-PD1 treated mice compared to isotype-treated controls. Moreover, these IFNγ+CXCR6+CD8+ T cells stained positively for the NRP-V7 mimotope tetramer, a known antigen for CD8+ T cells in spontaneous autoimmune diabetes in NOD mice, suggesting this as an antigen-specific population contributing to the immunopathogenesis of ICI-T1DM. Finally, genetic deletion of CXCR6 in NOD mice delayed the onset of autoimmune diabetes during anti-PD1 treatment in female (p=0.0162) but not male mice (p=0.3656). In summary, these data further elucidate the cellular mechanisms by which IFNγ and chemokine signaling pathways drive the development of ICI-T1DM and identify the CXCR6-CXCL16 axis as a potential therapeutic target to prevent this IRAE in checkpoint inhibitor-treated cancer patients. Presentation: 6/2/2024

Etiopatogenia y situación epidemiológica de la diabetes mellitus tipo 1

Type 1 diabetes mellitus (DM1) accounts for 5%-10% of diabetes cases worldwide. In most patients, the pathogenesis is the autoimmune destruction of pancreatic beta cells; in a small percentage, the origin is idiopathic. Although its onset is more common in children, it can also appear in adults, in whom the course is usually slower. Three phases or stages of DM1 have been defined. Virtually all patients with two or more antibodies will develop clinical DM1 (stage 3). In regard to DM1 prevention, there are multiple therapies under study that are aimed at halting the immunologic process or preserving the beta cell. Only teplizumab has been approved by the FDA in stage 2 DM1. The typical clinical symptoms in the diagnosis of DM1 is diabetic ketoacidosis (DKA), which is considered a medical emergency that requires the administration of insulin for its resolution. The determination of autoantibodies in relatives of patients with DM1 has increased the detection of cases of preclinical or asymptomatic DM1 and the need for universal screening for DM1 is being proposed.

Targeting the autoreactive CD8+ T-cell receptor in type 1 diabetes: Insights from scRNA-seq for immunotherapy

Type 1 Diabetes (T1D) is an autoimmune disease characterized by the attack and destruction of Pancreatic islet beta cells by T cells. Understanding the role of T-cell receptor (TCR) in the development of T1D is of paramount importance. This study employs single-cell RNA sequencing (scRNA-seq) to delve into the mechanistic actions and potential therapeutic applications of autoreactive stem cell-like CD8 TCR in T1D. By retrieving T-cell data from non-obese diabetic (NOD) mice via the GEO database, it was revealed that CD8+ T cells are the predominant T-cell subset in the pancreatic tissue of T1D mice, along with the identification of T-cell marker genes closely associated with T1D. Moreover, the gene TRAJ23 exhibits a preference for T1D, and its knockout alleviates T1D symptoms and adverse reactions in NOD mice. Additionally, engineered TCR-T cells demonstrate significant cytotoxicity towards β cells in T1D.

Long-term TNF-alpha therapy for preserving beta cell function in new onset type 1 diabetes: a case report

BackgroundType 1 diabetes mellitus (T1D) is an autoimmune disease caused by destruction of pancreatic islet beta-cells. There is significant residual beta-cell function, measured through circulating C-peptide, present at the time of T1D diagnosis but this subsequently decreases with time. Higher residual beta-cell function at diagnosis associates with better glycaemic control and less glucose variability, and later in the disease course with less hypoglycaemia, lower glucose variability and fewer microvascular complications. There is therefore value in preserving residual beta cell function in new onset T1D Immunotherapeutic agents can protect residual beta-cell function in type 1 diabetes. However, clinical trials of such agents, whilst demonstrating C-peptide preservation in short term studies, have yet to be taken forward into routine clinical care due to concerns around safety and long-term efficacy. Here we report the case of a gentleman with newly diagnosed T1D whose glycaemic control and insulin requirement improved whilst on a five year infusion programme of infliximab, a monoclonal antibody against TNF-alpha, for colitis.Case presentationA 52-year-old White Caucasian man was diagnosed with T1D in August 2018. Glucose was 25.6 mmol/L, HbA1c was 98mmol/mol and GAD antibodies were strongly positive. HbA1c marginally improved to 91mmol/mol following initiation of insulin detemir 5 units at night and 1:10 g of insulin aspart (November 2018). In June 2019, he developed rectal bleeding and abdominal pain. Following colonoscopy, he was diagnosed with “indeterminate colitis” and commenced on 6-weekly infusions of 400-450 mg infliximab. Thus far, he has received 32 doses and achieved colitis remission. Following infliximab initiation there was increased frequency of mild-moderate hypoglycaemia and he was gradually weaned off and discontinued detemir in June 2020. Since then, HbA1c improved from 57mmol/mol in August 2019 to 52mmol/mol in April 2022, remaining stable at 51mmol/mol. His most recent HbA1c is 54mmol/mol in February 2024. His c-peptide was 550pmol/L in October 2022 and 442pmol/L in February 2024, suggesting well-preserved beta-cell function almost 6 years post-diagnosis.ConclusionsOur patient’s improvement in glycaemic control can be explained by immunomodulation and C peptide preservation from infliximab. With the growing focus on type 1 diabetes disease modulation and working towards an ‘insulin free T1D’, our findings strengthen the evidence base for the repurposing of and long-term treatment with anti-TNF-α agents to preserve beta-cell function in new onset T1D.

The Effect of Vitamin D Deficiency on Immune-Related Hub Genes: A Network Analysis Associated With Type 1 Diabetes.

Background Type 1 diabetes (T1D) is an autoimmune disorder that results in the destruction of pancreatic beta cells, causing a shortage of insulin secretion. The development of T1D is influenced by both genetic predisposition and environmental factors, such as vitamin D. This vitamin is known for its ability to regulate the immune system and has been associated with a decreased risk of T1D. However, the specific ways in which vitamin D affects immune regulation and the preservation of beta cells in T1D are not yet fully understood. Gaining a better understanding of these interactions is essential for identifying potential targets for preventing and treating T1D. Methods The analysis focused on two Gene Expression Omnibus (GEO) datasets, namely, GSE55098 and GSE50012, to detect differentially expressed genes (DEGs). Enrichr (Ma'ayan Laboratory, New York, NY) was used to perform enrichment analysis for the Gene Ontology (GO) biological process and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The Search Tool for the Retrieval of Interacting Genes 12.0 (STRING) database was used to generate a protein-protein interaction (PPI) network. The Cytoscape 3.10.1 (Cytoscape Team, San Diego, CA) was used to analyze the PPI network and discover the hub genes. Results The DEGs in both datasets were identified using the GEO2R tool, with a particular focus on genes exhibiting contrasting regulations. Enrichment analysis unveiled the participation of these oppositely regulated DEGs in processes relevant to the immune system. Cytoscape analysis of the PPI network revealed five hub genes, MNDA, LILRB2, FPR2, HCK, and FCGR2A, suggesting their potential role in the pathogenesis of T1D and the response to vitamin D. Conclusion The study elucidates the complex interaction between vitamin D metabolism and immune regulation in T1D. The identified hub genes provide important knowledge on the molecular pathways that underlie T1D and have the potential to be targeted for therapeutic intervention. This research underscores the importance of vitamin D in the immune system's modulation and its impact on T1D development.

Age-based challenges to type 1 diabetes management in the pediatric population.

Type 1 diabetes is rising in the pediatric population, affecting approximately 1.2 million children and adolescents globally. Its complex pathogenesis involves the interaction between genetic predisposition and environmental factors, leading to T cell-mediated destruction of insulin-producing pancreatic beta-cells. This destruction results in insulin insufficiency and hyperglycemia. Hence, managing type 1 diabetes requires a comprehensive approach that includes various aspects such as blood glucose monitoring, insulin therapy, carbohydrate counting, caloric intake monitoring, considering family habits and food preferences, planning daily schedules, and incorporating physical activity. Children with type 1 diabetes encounter age-specific challenges in disease management that may exacerbate the risk of metabolic complications and adverse health outcomes. These risk factors may be neurological, physiological, behavioral, psychological, or social, complicate management and necessitate tailored approaches for effective care. Regardless of the age group, primary caregivers have a high responsibility to maintain optimal glycemic control, including monitoring diet, daily activity, and administering insulin. By reviewing research on the challenges faced by pediatric patients with type 1 diabetes, we summarized key insights aimed at developing targeted interventions and support systems that enhance diabetes management and improve health outcomes in this vulnerable population.

Secreted GDF15 maintains transcriptional responses during DNA damage-mediated senescence in human beta cells.

Type 1 diabetes (T1D) is a chronic metabolic disease resulting from an autoimmune destruction of pancreatic beta cells. Beta cells activate various stress responses during the development of T1D, including senescence, which involves cell cycle arrest, prosurvival signaling, and a proinflammatory secretome termed the senescence-associated secretory phenotype (SASP). We previously identified growth and differentiation factor 15 (GDF15) as a major SASP factor in human islets and human EndoC-βH5 beta cells in a model of DNA damage-mediated senescence that recapitulates features of senescent beta cells in T1D. Soluble GDF15 has been shown to exert protective effects on human and mouse beta cells during various forms of stress relevant to T1D; therefore, we hypothesized that secreted GDF15 may play a prosurvival role during DNA damage-mediated senescence in human beta cells. We found that elevated GDF15 secretion was associated with endogenous senescent beta cells in an islet preparation from a T1D donor, supporting the validity of our DNA damage model. Using antibody-based neutralization, we found that secreted endogenous GDF15 was not required for senescent human islet or EndoC cell viability. Rather, neutralization of GDF15 led to reduced expression of specific senescence-associated genes, including GDF15 itself and the prosurvival gene BCL2-like protein 1 (BCL2L1). Taken together, these data suggest that SASP factor GDF15 is not required to sustain senescent human islet viability, but it is required to maintain senescence-associated transcriptional responses.NEW & NOTEWORTHY Beta cell senescence is an emerging contributor to the pathogenesis of type 1 diabetes, but candidate therapeutic targets have not been identified in human beta cells. In this study, we examined the role of a secreted factor, GDF15, and found that although it is not required to maintain viability during senescence, it is required to fine-tune gene expression programs involved in the senescence response during DNA damage in human beta cells.

The Increased Frequency of Type 1 Regulatory T (Tr1) Cells and the Altered Expression of Aryl Hydrocarbon Receptor (AHR) and Interferon Regulatory Factor-4 (IRF4) Genes in Type 1 Diabetes: A Case-Control Study.

Background and aim Type 1 diabetes is an autoimmune disorder characterized by the destruction of pancreatic beta cells, leading to insulin deficiency and hyperglycemia. Regulatory T cells (Tregs), particularly type 1 regulatory T (Tr1) cells, play a crucial role in modulating autoimmune responses. Therefore, this study aimed to evaluate the frequency of Tr1 cells and their association with aryl hydrocarbon receptor (AHR) and interferon regulatory factor-4 (IRF4) gene expression levels in type 1 diabetes mellitus (T1DM) compared to the healthy controls. Method A case-control study design was used. The case group included patients diagnosed with T1DM, while the control group consisted of healthy individuals, matched for age and sex. Blood samples were collected, and peripheral blood mononuclear cells (PBMCs) were isolated. Serum interleukin 10 (IL-10) and interleukin 21 (IL-21) levels were measured using enzyme-linked immunosorbent assay (ELISA). The gene expression of AHR and IRF4 was analyzed using quantitative real-time polymerase chain reaction (qPCR), and Tr1 cell populations were determined using flow cytometry. Data were summarized with mean and standard error of the mean (SEM) for quantitative variables. Independent sample t-test, chi-square test, and the Mann-Whitney U test were used to compare groups. Statistical analyses were performed using SPSS version 25 (IBM SPSS Statistics, Armonk, NY), with significance levels set at p < 0.05. Figures were created using GraphPad Prism (GraphPad Software, San Diego, CA). Results A total of 45 cases were enrolled in the study, with 30 T1DM patients and 15 healthy controls. The mean IL-10 concentration was significantly higher in the patients (10.4 ± 1.1 pg/mL) compared to the healthy controls (5.1 ± 0.7 pg/mL), with a p-value of 0.001. There was no significant difference in IL-21 levels between the patients (76.1 ± 9.0 pg/mL) and healthy controls (88.2 ± 17.5 pg/mL), indicated by a p-value of 0.480. AHR gene expression was significantly lower in patients, with a p-value of 0.037. Although IRF4 gene expression was higher in patients, the difference was not statistically significant (p= 0.449). Tr1 cell frequency was significantly higher in T1DM patients (1.45% of cluster of differentiation 4+ {CD4+} T cells) compared to the healthy controls (0.40% of CD4+ T cells), with a p-value of 0.045. Conclusions The study demonstrated that T1DM is associated with higher IL-10 levels, decreased AHR gene expression, and a higher frequency of Tr1 cells. Policymakers should focus on developing targeted immunomodulatory therapies to address these immunological abnormalities. Healthcare providers should prioritize monitoring cytokine levels and gene expression in T1DM patients to tailor treatment plans effectively. Further research is needed to explore the therapeutic potential of modulating Tr1 cells and their related pathways in T1DM management.

Beta cells deficient for Renalase counteract autoimmunity by shaping natural killer cell activity.

Type 1 diabetes (T1D) arises from autoimmune-mediated destruction of insulin-producing pancreatic beta cells. Recent advancements in the technology of generating pancreatic beta cells from human pluripotent stem cells (SC-beta cells) have facilitated the exploration of cell replacement therapies for treating T1D. However, the persistent threat of autoimmunity poses a significant challenge to the survival of transplanted SC-beta cells. Genetic engineering is a promising approach to enhance immune resistance of beta cells as we previously showed by inactivating the Renalase (Rnls) gene. Here, we demonstrate that Rnls loss of function in beta cells shapes autoimmunity by mediating a regulatory natural killer (NK) cell phenotype important for the induction of tolerogenic antigen-presenting cells. Rnls-deficient beta cells mediate cell-cell contact-independent induction of hallmark anti-inflammatory cytokine Tgfβ1 in NK cells. In addition, surface expression of regulatory NK immune checkpoints CD47 and Ceacam1 is markedly elevated on beta cells deficient for Rnls. Altered glucose metabolism in Rnls mutant beta cells is involved in the upregulation of CD47 surface expression. These findings are crucial to better understand how genetically engineered beta cells shape autoimmunity, giving valuable insights for future therapeutic advancements to treat and cure T1D.

Enrichment of Bioactive Lipids in Urinary Extracellular Vesicles and Evidence of Apoptosis in Kidneys of Hypertensive Diabetic Cathepsin B Knockout Mice after Streptozotocin Treatment.

Cathepsin B (CtsB) is a ubiquitously expressed cysteine protease that plays important roles in health and disease. Urinary extracellular vesicles (uEVs) are released from cells associated with urinary organs. The antibiotic streptozotocin (STZ) is known to induce pancreatic islet beta cell destruction, diabetic nephropathy, and hypertension. We hypothesized that streptozotocin-induced diabetic kidney disease and hypertension result in the release of bioactive lipids from kidney cells that induce oxidative stress and renal cell death. Lipidomics was performed on uEVs isolated from CtsB knockout mice treated with or without STZ, and their kidneys were used to investigate changes in proteins associated with cell death. Lysophosphatidylethanolamine (LPE) (18:1), lysophosphatidylserine (LPS) (22:6), and lysophosphatidylglycerol (LPG) (22:5) were among the bioactive lipids enriched in uEVs from CtsB knockout mice treated with STZ compared to untreated CtsB mice (n = 3 uEV preparations per group). Anti-oxidant programming was activated in the kidneys of the CtsB knockout mice treated with STZ, as indicated by increased expression of glutathione peroxidase 4 (GPX4) and the cystine/glutamate antiporter SLC7A11 (XCT) (n = 4 mice per group), which was supported by a higher reactivity to 4-hydroxy-2-nonenal (4-HNE), a marker for oxidative stress (n = 3 mice per group). Apoptosis but not ferroptosis was the ongoing form of cell death in these kidneys as cleaved caspase-3 levels were significantly elevated in the STZ-treated CtsB knockout mice (n = 4 mice per group). There were no appreciable differences in the pro-ferroptosis enzyme acyl-CoA synthetase long-chain family member 4 (ACSL4) or the inflammatory marker CD93 in the kidneys (n = 3 mice per group), which further supports apoptosis as the prevalent mechanism of pathology. These data suggest that STZ treatment leads to oxidative stress, inducing apoptotic injury in the kidneys during the development of diabetic kidney disease and hypertension.

Insulin-Dendrimer Nanocomplex for Multi-Day Glucose-Responsive Insulin Therapy in Ossabaw Miniature Swine with Type 1 Diabetes

Background: Therapy for type 1 diabetes resulting from immunogenic destruction of the insulin-producing pancreatic beta cells has been a challenge for over 100 years. Delivering exogenous insulin to maintain euglycemia is a delicate balance between plasma glucose transport to insulin-responsive tissues, glucose absorption in the gut, and the pharmacodynamics of insulin. The synthesis of short- and long-acting insulins and use of insulin pumps have made great strides in the standard of diabetes care. Despite advances, hypoglycemia is a major limitation. There is no approved therapy that offers glucose-responsive insulin function. Toward this end we engineered a nanoscale complex combining both electrostatic and dynamic-covalent interactions between a synthetic dendrimer carrier and an insulin analogue modified with a high-affnity glucose-binding motif. Hypothesis: This insulin nanocomplex will yield an injectable insulin depot providing both glucose-sensitive and long-lasting insulin availability in a translation preclinical model. Methods: Ossabaw minature swine (41-59 kg; N=6) were made diabetic with alloxan, which was confirmed by stable hyperglycemia (228±43 mg/dL). Oral glucose tolerance tests (OGTT) were conducted at the diabetic baseline and each of the following 6 days after one subcutaneous injection of the insulin nanocomplex. Results: The basline OGTT elicted blood glucose of 350-450 mg/dL for 90 min of the 150 min OGTT, while serum insulin remained at ~5 μU/mL, nearly the detection limit. In contrast, 3 h after injection of insulin nanocomplex (~0.8-0.9 mg/kg) blood glucose decreased to 71±12 mg/dL. Subsequent OGTTs on days 1-6 increased blood glucose from normoglycemia to ~200 mg/dL and serum insulin increased to ~60-220 μU/mL, followed by return to nearly normolgycemia hours after the OGTT. Hypoglycemia was avoided in all pigs. Conclusions: The subcutaneous nanocomplex of a modified insulin and a synthetic dendrimer carrier produced a glucose-responsive insulin depot for week-long glycemic control following a single routine injection. These findings offer great promise for overcoming the hypoglycemia risk of intensive glucose control. Future studies should include additional physiological challenges of exercise and nutritional states. Support: Juvenile Diabetes Research Foundation 5-CDA-2020-947-A-N, Helmsley Charitable Trust 2019PG-T1D016 and 2102-04994, American Diabetes Association Pathway 1-19-ACE-31, National Science Foundation BMAT1944875, European Union-Next Generation EU LX22NPO5104, Czech Academy of Sciences RVO 6138963. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Nutritional Management of Athletes with Type 1 Diabetes: A Narrative Review.

Type 1 diabetes mellitus (T1DM) represents a complex clinical challenge for health systems. The autoimmune destruction of pancreatic beta cells leads to a complete lack of insulin production, exposing people to a lifelong risk of acute (DKA, coma) and chronic complications (macro and microvascular). Physical activity (PA) has widely demonstrated its efficacy in helping diabetes treatment. Nutritional management of people living with T1DM is particularly difficult. Balancing macronutrients, their effects on glycemic control, and insulin treatment represents a complex clinical challenge for the diabetologist. The effects of PA on glycemic control are largely unpredictable depending on many individual factors, such as intensity, nutrient co-ingestion, and many others. Due to this clinical complexity, we have reviewed the actual scientific literature in depth to help diabetologists, sport medicine doctors, nutritionists, and all the health figures involved in diabetes care to ameliorate both glycemic control and the nutritional status of T1DM people engaging in PA. Two electronic databases (PubMed and Scopus) were searched from their inception to January 2024. The main recommendations for carbohydrate and protein ingestion before, during, and immediately after PA are explained. Glycemic management during such activity is widely reviewed. Micronutrient needs and nutritional supplement effects are also highlighted in this paper.

An updated review on diabetes mellitus: Exploring its etiology, pathophysiology, complications and treatment approach

Diabetes mellitus, a prevalent chronic metabolic disorder, encompasses types like Type 1 (T1DM), Type 2 (T2DM), and gestational diabetes, marked by elevated blood sugar levels. T1DM, an autoimmune disease, entails genetic susceptibility triggering pancreatic beta cell destruction, necessitating insulin replacement. T2DM, linked to metabolic syndrome and insulin resistance, is influenced by genetics, obesity, inactivity, and ethnicity. Gestational Diabetes Mellitus (GDM) in pregnancy elevates offspring obesity and T2DM risk. Diagnosis involves fasting glucose, oral glucose tolerance, HbA1c tests, and specific antibody assessments. Chronic complications include atherosclerosis, retinopathy, neuropathy, nephropathy, and osmotic cell death, emphasizing glycaemic control. Treatment strategies differ, with T1DM requiring insulin therapy and T2DM involving lifestyle changes, medication, and potential insulin use, underscoring the need to understand diabetes for effective management and improved quality of life.

Exploring Transcriptional Regulation of Beta Cell SASP by Brd4-Associated Proteins and Cell Cycle Control Protein p21.

Type 1 diabetes (T1D) is a metabolic disease resulting from progressive autoimmune destruction of insulin-producing pancreatic beta cells. Although the majority of beta cells are lost in T1D, a small subset undergoes senescence, a stress response involving growth arrest, DNA damage response, and activation of a senescence-associated secretory phenotype (SASP). SASP in beta cells of the nonobese diabetic (NOD) mouse model of T1D and primary human islets is regulated at the level of transcription by bromodomain extra-terminal (BET) proteins, but the mechanisms remain unclear. To explore how SASP is transcriptionally regulated in beta cells, we used the NOD beta cell line NIT-1 to model beta cell SASP and identified binding partners of BET protein Brd4 and explored the role of the cyclin-dependent kinase inhibitor p21. Brd4 interacted with a variety of proteins in senescent NIT-1 cells including subunits of the Ino80 chromatin remodeling complex, which was expressed in beta cells during T1D progression in NOD mice and in human beta cells of control, autoantibody-positive, and T1D donors as determined from single-cell RNA-seq data. RNAi knockdown of p21 during senescence in NIT-1 cells did not significantly impact viability or SASP. Taken together, these results suggest that Brd4 interacts with several protein partners during senescence in NIT-1 cells, some of which may play roles in SASP gene activation and that p21 is dispensable for the SASP in this beta cell model.

Evidence for C-Peptide as a Validated Surrogate to Predict Clinical Benefits in Trials of Disease-Modifying Therapies for Type 1 Diabetes.

Type 1 diabetes is a chronic autoimmune disease in which destruction of pancreatic beta cells causes life-threatening metabolic dysregulation. Numerous approaches are envisioned for new therapies, but limitations of current clinical outcome measures are significant disincentives to development efforts. C-peptide, a direct byproduct of proinsulin processing, is a quantitative biomarker of beta cell function that is not cleared by the liver and can be measured in the peripheral blood. Studies of quantitative measures of beta cell function have established a predictive relationship between stimulated C-peptide as a measure of beta cell function and clinical benefits. C-peptide levels at diagnosis are often high enough to afford glycemic control benefits associated with protection from end-organ complications of diabetes, and even lower levels offer protection from severe hypoglycemia in type 1 diabetes, as observed in large prospective cohort studies and interventional trials of islet transplantation. These observations support consideration of C-peptide not just as a biomarker of beta cell function, but also as a specific, sensitive, feasible, and clinically meaningful outcome defining beta cell preservation or restoration for clinical trials of disease-modifying therapies. Regulatory acceptance of C-peptide as a validated surrogate for demonstration of efficacy would greatly facilitate development of disease-modifying therapies for type 1 diabetes.