Beta-cell Loss Research Articles

Advancing diabetes management: Exploring pancreatic beta-cell restoration’s potential and challenges

Diabetes mellitus, characterized by chronic hyperglycemia due to insulin deficiency or resistance, poses a significant global health burden. Central to its pathogenesis is the dysfunction or loss of pancreatic beta cells, which are res-ponsible for insulin production. Recent advances in beta-cell regeneration research offer promising strategies for diabetes treatment, aiming to restore endogenous insulin production and achieve glycemic control. This review explores the physiological basis of beta-cell function, recent scientific advan-cements, and the challenges in translating these findings into clinical applications. It highlights key developments in stem cell therapy, gene editing technologies, and the identification of novel regenerative molecules. Despite the potential, the field faces hurdles such as ensuring the safety and long-term efficacy of regen-erative therapies, ethical concerns around stem cell use, and the complexity of beta-cell differentiation and integration. The review highlights the importance of interdisciplinary collaboration, increased funding, the need for patient-centered approaches and the integration of new treatments into comprehensive care strategies to overcome these challenges. Through continued research and collaboration, beta-cell regeneration holds the potential to revolutionize diabetes care, turning a chronic condition into a manageable or even curable disease.

MiR-375: it could be a general biomarker of metabolic changes and inflammation in type 1 diabetes patients and their siblings.

Type 1 diabetes (T1D) is a chronic autoimmune illness that results in loss of pancreatic beta cells and insulin insufficiency. MicroRNAs (miRNAs) are linked to immune system functions contributing to the pathophysiology of T1D, miRNA-375 is significantly expressed in the human pancreas and its circulatory levels might correspond to beta cell alterations. Pancreatic islet cell antibodies (ICA) and Glutamic acid decarboxylase antibodies (GADA) have roles in autoimmune pathogenesis and are predictive markers of T1D. The aim of this work was to detect serum level changes of miRNA-375, ICA, and GADA in T1D patients, and their siblings compared to healthy controls and correlate them with T1D biochemical parameters. The study included 66 T1D patients (32 males and 34 females; age range 3-18 years), 22 patients' siblings (13 males and 9 females; age range 4-17 years), and 23 healthy controls (7 males and 16 females; age range 4-17 years). MiRNA-375 levels were measured using quantitative reverse transcription polymerase chain reaction (RT-qPCR), while ICA and GADA levels were measured using enzyme-linked immunosorbent assay (ELISA). Data analysis was done utilizing SPSS-17 software. MiR-375 levels were downregulated in T1D patients and further decreased in their siblings when compared to healthy controls. Furthermore, miR-375 exhibited inverse correlations with HbA1c levels but no correlations with Total Insulin Dose, disease duration, or autoantibodies (GADA & ICA). Our study indicates that miR-375 is significantly downregulated in children with T1D and their siblings, suggesting its potential role as a biomarker for beta-cell function and glycemic control.

7936 Type 1 Diabetes Therapeutic Compound MSB-61: Using RNA Sequencing To Identify The Mechanism

Abstract Disclosure: P. Khan: None. K. Corbin: None. N. Ajmal: None. S. Bergmeir: None. G. Gu: None. X. Tong: None. C.S. Nunemaker: None. Abstract Type 1 diabetes (T1D) is a chronic autoimmune disease in which loss of insulin-producing beta-cells leads to hyperglycemia due to which patients eventually require lifelong insulin therapy to maintain normal glycemic control. Insulin remains the gold standard and the only effective treatment for T1D since its discovery 100 years ago. Protecting the pancreatic beta cells from cytokine-induced cell death and restoring insulin secretion are important to treat T1D, two properties that are currently lacking in present therapies. Our lab identified a chemical compound MSB-61 that increases insulin release and protects pancreatic islets against T1D-associated cytokines and endoplasmic reticulum (ER) stress. This study aims to identify the mechanism of action of MSB-61 in protecting pancreatic islets from ER stress-induced cell death. To achieve this aim pancreatic islets obtained from CD-1 strain mice were exposed for one hour to 50uM MSB-61 or vehicle control. After treatment, RNA was collected for RNA sequencing. In addition to RNA extraction for sequencing, MSB-61's ability to secrete insulin was verified by performing ELISA on control,10 and 50uM MSB-61-treated islets, and the activity of protection from cell death was assessed by performing cell death assay on islets treated with ER stressors in the presence and absence of 10 and 50uM MSB-61. Using Genialis, a bioinformatics service, we evaluated 57,010 genes (including non-coding transcripts) in our RNA sequencing data set. The DESeq2 technique of data analysis allowed us to identify 350 differentially expressed genes (DEGs), of which 251 were upregulated and 74 were downregulated. After removing non-coding/undefined transcripts and genes with <5 counts per million, a total of 117 genes remained; 108 up and 9 down. According to the String database (string-db.org), many of the top DEGs formed a common network of genes associated with cell death protection and insulin secretion. A key component of that gene network is a stress-responsive orphan nuclear receptor with known protective effects in beta cells. Testing this orphan nuclear receptor as a possible direct or indirect target of MSB-61 for cell death prevention can aid in identifying the genes and pathways targeted by MSB-61, allowing us to improve our approaches to T1D treatment and develop better medications. Presentation: 6/3/2024

The use of Oral Anti-Diabetic Medications in Diabetes Mellitus type 1: An Educational Article and Expert Opinion

Diabetes mellitus type 1 is lifelong condition resulting from failure of production of insulin because of the loss of pancreatic islet beta-cells because of autoimmune damage. Patients with this type of diabetes need lifelong treatment with insulin to remain alive. Poor diabetic control which predisposes to a variety of complications is not uncommon in patients treated with insulin alone. Therefore, the use of medications that can possibly enhance the therapeutic effect of insulin and reduce the risk of diabetic complications has been considered. Oral anti-diabetics including acarbose, an inhibitor of intestinal α-glucosidase, metformin, a biguanide, sulfonylureas including glipizide, and sitagliptin, an inhibitor of dipeptidyl peptidase 4 (DPP-4) are primarily used for the treatment of non-insulin dependent diabetes (Type 2). The aim of this paper is to provide an overview of the use of oral anti-diabetics in the treatment of insulin dependent diabetes (Type 1). Expert opinion: The current evidence-based expert opinion recommends the judicious use of oral anti-diabetics especially acarbose and metformin in the treatment of unsatisfactorily controlled insulin dependent diabetes type 1. These medications can help in improving diabetic control through reducing glucose levels after meals, and can contribute to lowering the levels of glycosylated hemoglobin (HbA1c). The use of these oral anti-diabetics can also help in reducing insulin requirement.

The islet tissue plasminogen activator/plasmin system is upregulated with human islet amyloid polypeptide aggregation and protects beta cells from aggregation-induced toxicity

Aims/hypothesisApart from its fibrinolytic activity, the tissue plasminogen activator (tPA)/plasmin system has been reported to cleave the peptide amyloid beta, attenuating brain amyloid deposition in Alzheimer’s disease. As aggregation of human islet amyloid polypeptide (hIAPP) is toxic to beta cells, we sought to determine whether activation of the fibrinolytic system can also reduce islet amyloid deposition and its cytotoxic effects, which are both observed in type 2 diabetes.MethodsThe expression of Plat (encoding tPA) and plasmin activity were measured in isolated islets from amyloid-prone hIAPP transgenic mice or non-transgenic control islets expressing non-amyloidogenic mouse islet amyloid polypeptide cultured in the absence or presence of the amyloid inhibitor Congo Red. Plat expression was also determined in hIAPP-treated primary islet endothelial cells, bone marrow-derived macrophages (BMDM) and INS-1 cells, in order to determine the islet cell type(s) producing tPA in response to hIAPP aggregation. Cell-free thioflavin-T assays and MS were used to respectively monitor hIAPP aggregation kinetics and investigate plasmin cleavage of hIAPP. Cell viability was assessed in INS-1 beta cells treated with hIAPP with or without plasmin. Finally, to confirm the findings in human samples, PLAT expression was measured in freshly isolated islets from donors with and without type 2 diabetes.ResultsIn isolated islets from transgenic mice, islet Plat expression and plasmin activity increased significantly with the process of amyloid deposition (p≤0.01, n=5); these effects were not observed in islets from non-transgenic mice and were blocked by Congo Red (p≤0.01, n=4). In response to hIAPP exposure, Plat expression increased in BMDM and INS-1 cells vs vehicle-treated cells (p≤0.05, n=4), but not in islet endothelial cells. Plasmin reduced hIAPP fibril formation in a dose-dependent manner in a cell-free system, and restored hIAPP-induced loss of cell viability in INS-1 beta cells (p≤0.01, n=5). Plasmin cleaved monomeric hIAPP, inducing a rapid decrease in the abundance of full-length hIAPP and the appearance of hIAPP 1–11 and 12–37 fragments. hIAPP 12–37, which contains the critical amyloidogenic region, was not toxic to INS-1 cells. Finally, PLAT expression was significantly increased by 2.4-fold in islets from donors with type 2 diabetes (n=4) vs islets from donors without type 2 diabetes (n=7) (p≤0.05).Conclusions/interpretationThe fibrinolytic system is upregulated in islets with hIAPP aggregation. Plasmin rapidly degrades hIAPP, limiting its aggregation into amyloid and thus protecting beta cells from hIAPP-induced toxicity. Thus, increasing islet plasmin activity might be a strategy to limit beta cell loss in type 2 diabetes.Graphical

Revisiting the pattern of loss of β-cell function in preclinical Type 1 Diabetes.

Type 1 diabetes (T1D) results from beta cell destruction due to autoimmunity. It has been proposed that beta cell loss is relatively quiescent in the early years after seroconversion to islet antibody positivity (stage 1) with accelerated beta cell loss only developing around 6-18 months prior to clinical diagnosis. This construct implies that immunointervention in this early stage will be of little benefit since there is little disease activity to modulate. Here we argue that the apparent lack of progression in early stage disease may be an artefact of the modality of assessment used. When substantial β-cell function remains, the standard assessment - the oral glucose tolerance test - represents a submaximal stimulus and underestimates the residual function. By contrast, around the time of diagnosis, glucotoxicity exerts a deleterious effect on insulin secretion giving the impression of disease acceleration. Once glucotoxicity is relieved by insulin therapy, β-cell function partially recovers ("the honeymoon effect"). However, evidence from recent trials suggests that glucose control has little effect on the underlying disease process. We therefore hypothesise that the autoimmune destruction of β-cells actually progresses at a more or less constant rate through all phases of T1D and that early stage immunointervention will be both beneficial and desirable.

Moderate beta-cell ablation triggers synergic compensatory mechanisms even in the absence of overt metabolic disruption

Regeneration, the ability to replace injured tissues and organs, is a phenomenon commonly associated with lower vertebrates but is also observed in mammals, in specific tissues. In this study, we investigated the regenerative potential of pancreatic islets following moderate beta-cell loss in mice. Using a rapid model of moderate ablation, we observed a compensatory response characterized by transient inflammation and proliferation signatures, ultimately leading to the recovery of beta-cell identity and function. Interestingly, this proliferative response occurred independently of inflammation, as demonstrated in ablated immunodeficient mice. Furthermore, exposure to high-fat diet stimulated beta-cell proliferation but negatively impacted beta-cell function. In contrast, an equivalent slower ablation model revealed a delayed but similar proliferative response, suggesting proliferation as a common regenerative response. However, high-fat diet failed to promote proliferation in this model, indicating a differential response to metabolic stressors. Overall, our findings shed light on the complex interplay between beta-cell loss, inflammation, and stress in modulating pancreatic islet regeneration. Understanding these mechanisms could pave the way for novel therapeutic strategies based on beta-cell proliferation.

Stress-Induced Diabetic Ketoacidosis Due to Transient Beta Cell Stunning in a Youth with Type 2 Diabetes Mellitus: A Case Report

Abstract A 15-year-old boy was admitted to the intensive care unit of our hospital with complaints of increased urination, extreme tiredness, and nausea for the past 15 days. He had also lost 6.5 kg of weight (almost 10% of total body weight) in 1 month. On admission, his plasma glucose was 780 mg/dL, glycated haemoglobin (HbA1c) 11.6%, serum ketones >10.0 mmol/L, osmolality 346 mosm/kg, arterial pH 7.28, and bicarbonate 9 mEq/L. The C-peptide report initially indicated poor pancreatic beta cell reserve (fasting: 0.41 pmol/mL and stimulated: 0.46 pmol/mL). He was diagnosed with diabetic ketoacidosis and responded well to treatment, after which time he was switched to subcutaneous insulin. Ten days later, in the outpatient clinic, his fasting blood glucose was 132 mg/dL, postprandial blood glucose was 183 mg/dL, and C-peptide had improved to fasting: 0.89 pmol/mL and stimulated: 1.42 pmol/mL. Considering the presence of acanthosis nigricans on the neck, a body mass index in the overweight range, a positive family history of diabetes, and negative tests for pancreatic autoantibodies, an early onset diagnosis of type 2 diabetes mellitus was considered. Insulin was gradually withdrawn, and he was switched to metformin. Sustained recovery of C-peptide in this case indicates that lack of insulin at admission was due to beta cell stunning, rather than a total and irreversible loss of beta cells as expected in type 1 diabetes mellitus. Beta cell stunning is often reversible, as shown in this case.

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

Aims/hypothesisInsulitis, a hallmark of inflammation preceding autoimmune type 1 diabetes, leads to the eventual loss of functional beta cells. However, functional beta cells can persist even in the face of continuous insulitis. Despite advances in immunosuppressive treatments, maintaining functional beta cells to prevent insulitis progression and hyperglycaemia remains a challenge. The cannabinoid type 1 receptor (CB1R), present in immune cells and beta cells, regulates inflammation and beta cell function. Here, we pioneer an ex vivo model mirroring human insulitis to investigate the role of CB1R in this process.MethodsCD4+ T lymphocytes were isolated from peripheral blood mononuclear cells (PBMCs) from male and female individuals at the onset of type 1 diabetes and from non-diabetic individuals, RNA was extracted and mRNA expression was analysed by real-time PCR. Single beta cell expression from donors with type 1 diabetes was obtained from data mining. Patient-derived human islets from male and female cadaveric donors were 3D-cultured in solubilised extracellular matrix gel in co-culture with the same donor PBMCs, and incubated with cytokines (IL-1β, TNF-α, IFN-γ) for 24–48 h in the presence of vehicle or increasing concentrations of the CB1R blocker JD-5037. Expression of CNR1 (encoding for CB1R) was ablated using CRISPR/Cas9 technology. Viability, intracellular stress and signalling were assayed by live-cell probing and real-time PCR. The islet function measured as glucose-stimulated insulin secretion was determined in a perifusion system. Infiltration of immune cells into the islets was monitored by microscopy. Non-obese diabetic mice aged 7 weeks were treated for 1 week with JD-5037, then euthanised. Profiling of immune cells infiltrated in the islets was performed by flow cytometry.ResultsCNR1 expression was upregulated in circulating CD4+ T cells from individuals at type 1 diabetes onset (6.9-fold higher vs healthy individuals) and in sorted islet beta cells from donors with type 1 diabetes (3.6-fold higher vs healthy counterparts). The peripherally restricted CB1R inverse agonist JD-5037 arrested the initiation of insulitis in humans and mice. Mechanistically, CB1R blockade prevented islet NO production and ameliorated the ATF6 arm of the unfolded protein response. Consequently, cyto/chemokine expression decreased in human islets, leading to sustained islet cell viability and function.Conclusions/interpretationThese results suggest that CB1R could be an interesting target for type 1 diabetes while highlighting the regulatory mechanisms of insulitis. Moreover, these findings may apply to type 2 diabetes where islet inflammation is also a pathophysiological factor.Data availabilityTranscriptomic analysis of sorted human beta cells are from Gene Expression Omnibus database, accession no. GSE121863, available at https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSM3448161.Graphical

Reversal of diabetes by an oral Salmonella-based vaccine in acute and progressive diabetes in NOD mice.

Type 1 diabetes (T1D)-associated hyperglycemia develops, in part, from loss of insulin-secreting beta cells. The degree of glycemic dysregulation and the age at onset of disease can serve as indicators of the aggressiveness of the disease. Tracking blood glucose levels in prediabetic mice may demonstrate the onset of diabetes and, along with animal age, also presage disease severity. In this study, an analysis of blood glucose levels obtained from female NOD mice starting at 4 weeks until diabetes onset was undertaken. New onset diabetic mice were orally vaccinated with a Salmonella-based vaccine towards T1D-associated preproinsulin combined with TGFβ and IL10 along with anti-CD3 antibody. Blood glucose levels were obtained before and after development of disease and vaccination. Animals were classified as acute disease if hyperglycemia was confirmed at a young age, while other animals were classified as progressive disease. The effectiveness of the oral T1D vaccine was greater in mice with progressive disease that had less glucose excursion compared to acute disease mice. Overall, the Salmonella-based vaccine reversed disease in 60% of the diabetic mice due, in part, to lessening of islet inflammation, improving residual beta cell health, and promoting tolerance. In summary, the age of disease onset and severity of glucose dysregulation in NOD mice predicted response to vaccine therapy. This suggests a similar disease categorization in the clinic may predict therapeutic response.

Infection with SARS-CoV-2 can cause pancreatic impairment

Evidence suggests associations between COVID-19 patients or vaccines and glycometabolic dysfunction and an even higher risk of the occurrence of diabetes. Herein, we retrospectively analyzed pancreatic lesions in autopsy tissues from 67 SARS-CoV-2 infected non-human primates (NHPs) models and 121 vaccinated and infected NHPs from 2020 to 2023 and COVID-19 patients. Multi-label immunofluorescence revealed direct infection of both exocrine and endocrine pancreatic cells by the virus in NHPs and humans. Minor and limited phenotypic and histopathological changes were observed in adult models. Systemic proteomics and metabolomics results indicated metabolic disorders, mainly enriched in insulin resistance pathways, in infected adult NHPs, along with elevated fasting C-peptide and C-peptide/glucose ratio levels. Furthermore, in elder COVID-19 NHPs, SARS-CoV-2 infection causes loss of beta (β) cells and lower expressed-insulin in situ characterized by islet amyloidosis and necrosis, activation of α-SMA and aggravated fibrosis consisting of lower collagen in serum, an increase of pancreatic inflammation and stress markers, ICAM-1 and G3BP1, along with more severe glycometabolic dysfunction. In contrast, vaccination maintained glucose homeostasis by activating insulin receptor α and insulin receptor β. Overall, the cumulative risk of diabetes post-COVID-19 is closely tied to age, suggesting more attention should be paid to blood sugar management in elderly COVID-19 patients.

Interleukin-6: An Under-Appreciated Inducer of Thermogenic Adipocyte Differentiation.

Adipose tissue inflammation is a key factor leading to obesity-associated immune disorders, such as insulin resistance, beta cell loss in the pancreatic islets, meta-inflammation, and autoimmunity. Inhibiting adipose tissue inflammation is considered a straightforward approach to abrogate these diseases. However, recent findings show that certain pro-inflammatory cytokines are essential for the proper differentiation and functioning of adipocytes. Lipolysis is stimulated, and the thermogenic competence of adipocytes is unlocked by interleukin-6 (IL-6), a cytokine that was initially recognized as a key trigger of adipose tissue inflammation. Coherently, signal transducer and activator of transcription 3 (STAT3), which is a signal transducer for IL-6, is necessary for thermogenic adipocyte development. Given the impact of thermogenic adipocytes in increasing energy expenditure and reducing body adiposity, functions of IL-6 in the adipose tissue have gained attention recently. In this review, we show that IL-6 signaling may protect from excess fat accumulation by stimulating thermogenesis in adipocytes.

Animal Models for Understanding the Mechanisms of Beta Cell Death during Type 2 Diabetes Pathogenesis.

Type 2 diabetes (T2D) has become a worldwide epidemic, primarily driven by obesity from overnutrition and sedentariness. Recent results reveal there is heterogeneity in both pathology and treatment responses in T2D patients. Therefore, a variety of T2D animal models are necessary to obtain a mechanistic understanding of distinct disease processes. T2D results from insufficient insulin, either due to beta cell loss or inborn deficiency. Although decreases in beta cell mass can occur through loss of identity or cell death, in this review, we will highlight the T2D animal models that display beta cell death, including the Zucker Diabetic Fatty Rat, sand rat, db/db mouse, and a novel diabetic zebrafish model, the Zebrafish Muscle Insulin-Resistant (zMIR) fish. Procuring a mechanistic understanding of different T2D progression trajectories under a variety of contexts is paramount for developing and testing more individualized treatments.

Implications of endoplasmic reticulum stress and beta-cell loss in immunodeficient diabetic NRG-Akita mice for understanding monogenic diabetes.

Immunodeficient mice models have become increasingly important as in vivo models engrafted with human cells or tissues for research. The NOD-Rag1null Ins2Akita Il2rnull (NRG Akita) mice is a model combined with immunodeficient NRG and monogenic diabetes Akita mice that develop spontaneous hyperglycemia with progressive loss of pancreatic insulin-producing beta-cells with age. This model is one of the monogenic diabetic models, which has been providing a powerful platform for transplantation experiments of stem cells-generated human β-cells. This research aimed to provide insights into the mechanisms underlying this monogenic diabetes, which remains incompletely understood. Histological and immunofluorescence analyses were conducted on endocrine pancreatic islets to compare NRG wild-type (Wt) controls with NRG-Akita mice. Our investigation focused on assessing the expression of endocrine hormones, transcription factors, proliferation, ER stress, and apoptosis. Histological analyses on NRG-Akita mice revealed smaller islets at 6-weeks-old, due to fewer β-cells in the islets, compared to NRG-Wt controls, which further progressed with age. The proliferation rate decreased, and apoptosis was abundant in β-cells in NRG Akita mice. Interestingly, our mechanistic analyses revealed that β-cells in NRG-Akita mice progressively accumulated the endoplasmic reticulum (ER) stresses, leading to a decreased expression of pivotal β-cell transcriptional factor PDX1. Altogether, our mechanistic insight into β-cell loss in this model could shed light on essential links between ER stress, proliferation, and cell identity, which might open the door to new therapeutic strategies for various diseases since ER stress is one of the most common features not only in diabetes but also in other degenerative diseases.

Synergistic Effect of a Flavonoid-Rich Cocoa-Carob Blend and Metformin in Preserving Pancreatic Beta Cells in Zucker Diabetic Fatty Rats.

The loss of functional beta-cell mass in diabetes is directly linked to the development of diabetic complications. Although dietary flavonoids have demonstrated antidiabetic properties, their potential effects on pancreatic beta-cell preservation and their synergistic benefits with antidiabetic drugs remain underexplored. We have developed a potential functional food enriched in flavonoids by combining cocoa powder and carob flour (CCB), which has shown antidiabetic effects. Here, we investigated the ability of the CCB, alone or in combination with metformin, to preserve pancreatic beta cells in an established diabetic context and their potential synergistic effect. Zucker diabetic fatty rats (ZDF) were fed a CCB-rich diet or a control diet, with or without metformin, for 12 weeks. Markers of pancreatic oxidative stress and inflammation, as well as relative beta-cell mass and beta-cell apoptosis, were analyzed. Results demonstrated that CCB feeding counteracted pancreatic oxidative stress by enhancing the antioxidant defense and reducing reactive oxygen species. Moreover, the CCB suppressed islet inflammation by preventing macrophage infiltration into islets and overproduction of pro-inflammatory cytokines, along with the inactivation of nuclear factor kappa B (NFκB). As a result, the CCB supplementation prevented beta-cell apoptosis and the loss of beta cells in ZDF diabetic animals. The observed additive effect when combining the CCB with metformin underscores its potential as an adjuvant therapy to delay the progression of type 2 diabetes.

Permanent neonatal diabetes-causing insulin mutations have dominant negative effects on beta cell identity

ObjectiveHeterozygous coding sequence mutations of the INS gene are a cause of permanent neonatal diabetes (PNDM), requiring insulin therapy similar to T1D. While the negative effects on insulin processing and secretion are known, how dominant insulin mutations result in a continued decline of beta cell function after birth is not well understood. MethodsWe explored the causes of beta cell failure in two PNDM patients with two distinct INS mutations using patient-derived iPSCs and mutated hESCs. Resultswe detected accumulation of misfolded proinsulin and impaired proinsulin processing in vitro, and a dominant-negative effect of these mutations on beta-cell mass and function after transplantation into mice. In addition to anticipated ER stress, we found evidence of beta-cell dedifferentiation, characterized by an increase of cells expressing both Nkx6.1 and ALDH1A3, but negative for insulin and glucagon. ConclusionsThese results highlight a novel mechanism, the loss of beta cell identity, contributing to the loss and functional failure of human beta cells with specific insulin gene mutations.

Allo Beta Cell transplantation: specific features, unanswered questions, and immunological challenge.

Type 1 diabetes (T1D) presents a persistent medical challenge, demanding innovative strategies for sustained glycemic control and enhanced patient well-being. Beta cells are specialized cells in the pancreas that produce insulin, a hormone that regulates blood sugar levels. When beta cells are damaged or destroyed, insulin production decreases, which leads to T1D. Allo Beta Cell Transplantation has emerged as a promising therapeutic avenue, with the goal of reinstating glucose regulation and insulin production in T1D patients. However, the path to success in this approach is fraught with complex immunological hurdles that demand rigorous exploration and resolution for enduring therapeutic efficacy. This exploration focuses on the distinct immunological characteristics inherent to Allo Beta Cell Transplantation. An understanding of these unique challenges is pivotal for the development of effective therapeutic interventions. The critical role of glucose regulation and insulin in immune activation is emphasized, with an emphasis on the intricate interplay between beta cells and immune cells. The transplantation site, particularly the liver, is examined in depth, highlighting its relevance in the context of complex immunological issues. Scrutiny extends to recipient and donor matching, including the utilization of multiple islet donors, while also considering the potential risk of autoimmune recurrence. Moreover, unanswered questions and persistent gaps in knowledge within the field are identified. These include the absence of robust evidence supporting immunosuppression treatments, the need for reliable methods to assess rejection and treatment protocols, the lack of validated biomarkers for monitoring beta cell loss, and the imperative need for improved beta cell imaging techniques. In addition, attention is drawn to emerging directions and transformative strategies in the field. This encompasses alternative immunosuppressive regimens and calcineurin-free immunoprotocols, as well as a reevaluation of induction therapy and recipient preconditioning methods. Innovative approaches targeting autoimmune recurrence, such as CAR Tregs and TCR Tregs, are explored, along with the potential of stem stealth cells, tissue engineering, and encapsulation to overcome the risk of graft rejection. In summary, this review provides a comprehensive overview of the inherent immunological obstacles associated with Allo Beta Cell Transplantation. It offers valuable insights into emerging strategies and directions that hold great promise for advancing the field and ultimately improving outcomes for individuals living with diabetes.

Hypoxia within subcutaneously implanted macroencapsulation devices limits the viability and functionality of densely loaded islets.

Subcutaneous macroencapsulation devices circumvent disadvantages of intraportal islet therapy. However, a curative dose of islets within reasonably sized devices requires dense cell packing. We measured internal PO2 of implanted devices, mathematically modeled oxygen availability within devices and tested the predictions with implanted devices containing densely packed human islets. Partial pressure of oxygen (PO2) within implanted empty devices was measured by noninvasive 19F-MRS. A mathematical model was constructed, predicting internal PO2, viability and functionality of densely packed islets as a function of external PO2. Finally, viability was measured by oxygen consumption rate (OCR) in day 7 explants loaded at various islet densities. In empty devices, PO2 was 12 mmHg or lower, despite successful external vascularization. Devices loaded with human islets implanted for 7 days, then explanted and assessed by OCR confirmed trends proffered by the model but viability was substantially lower than predicted. Co-localization of insulin and caspase-3 immunostaining suggested that apoptosis contributed to loss of beta cells. Measured PO2 within empty devices declined during the first few days post-transplant then modestly increased with neovascularization around the device. Viability of islets is inversely related to islet density within devices.

Paired box 6 gene delivery preserves beta cells and improves islet transplantation efficacy

Loss of pancreatic beta cells is the central feature of all forms of diabetes. Current therapies fail to halt the declined beta cell mass. Thus, strategies to preserve beta cells are imperatively needed. In this study, we identified paired box 6 (PAX6) as a critical regulator of beta cell survival. Under diabetic conditions, the human beta cell line EndoC‐βH1, db/db mouse and human islets displayed dampened insulin and incretin signalings and reduced beta cell survival, which were alleviated by PAX6 overexpression. Adeno‐associated virus (AAV)‐mediated PAX6 overexpression in beta cells of streptozotocin‐induced diabetic mice and db/db mice led to a sustained maintenance of glucose homeostasis. AAV‐PAX6 transduction in human islets reduced islet graft loss and improved glycemic control after transplantation into immunodeficient diabetic mice. Our study highlights a previously unappreciated role for PAX6 in beta cell survival and raises the possibility that ex vivo PAX6 gene transfer into islets prior to transplantation might enhance islet graft function and transplantation outcome.

Thioredoxin Interacting Protein Inhibitors in Diabetes Mellitus: A Critical Review.

Diabetes Mellitus (DM) is one of the highest contributors to global mortality, exceeding numbers of even the three major infectious diseases in the world, namely Tuberculosis, HIV AIDS, and Malaria. DM is characterised by increased serum levels of glucose caused by a loss of beta cells of the pancreatic islets, responsible for the secretion of insulin. Upon accumulation of data via a wide array of literature surveys, it has been found that Thioredoxin Interacting Protein (TXNIP) presents itself as a vital factor in controlling the production and loss of beta islet cells. TXNIP inhibits the action of the Thioredoxin (TRX) protein found in the beta cells thereby rendering it ineffective in maintaining the cellular redox balance causing oxidative stress and subsequent consequences ultimately leading to aggravation of the disease. TRX exists in the form of two isoforms - TRX1, which is located in the cytosol and at times translocates to the nucleus, and TRX2, which is located in the nucleus. TRX is responsible for the maintenance of the normal cellular redox balance by reducing the oxidised proteins formed by the Reactive Oxygen Species (ROS) with the help of NADPH dependent TRX Reductase enzyme. This proves to be essential in the pathogenesis of Diabetes Mellitus as the beta cells of the pancreatic islets lack a sufficient amount of antioxidant systems. Thus, inhibition of TXNIP has become essential in the survival of beta cells, not only enhancing insulin secretion and sensitivity but also alleviating the diseases associated with Diabetes. Hence, TXNIP is discovered to be a unique therapeutic target in the management of DM.