Β-cell Activity Research Articles

Characterization and functional evaluation of goat PDX1 regulatory modules through comparative analysis of conserved interspecies homologs.

PDX1 is a crucial transcription factor in pancreas development and mature β-cell function. However, the regulation of PDX1 expression in larger animals mirroring human pancreas morphogenesis and endocrine maturation remains poorly understood. Therefore, we conducted a comparative analysis to characterize regulatory regions of goat PDX1 gene and assessed their transcriptional activity by transient transfection of several transgenic EGFP constructs in β- and non-β cell lines. We recognized several highly conserved regions encompassing the promoter and cis-regulatory elements (Area I-IV) at 5' flanking sequence of the genes. Within the promoter, we identified that a key E-box and nearby CAAT element synergistically drive transcription, constituting the basal promoter of goat PDX1 gene. Furthermore, each recognized regulatory area separately enhances this basal promoter activity in β-cells compared to non-β cells; however, cooperatively, they exhibit a bifunctional regulatory effect on transcription. Additionally, the intact ~ 3kb upstream region (Area I-III) functions as the most efficient reporter transgene in vitro and shows islet-specific expression in native rat pancreas. Together, our findings suggest that the regulation of goat PDX1 gene is governed by conserved regions similar to other mammals, while both structurally and functionally, these regions exhibit a closer resemblance to those found in humans.

2-Hydroxylation is a chemical switch linking fatty acids to glucose-stimulated insulin secretion

Glucose-stimulated insulin secretion (GSIS) in pancreatic β-cells is metabolically regulated and progressively diminished during the development of type 2 diabetes (T2D). This dynamic process is tightly coupled with fatty acid metabolism, but the underlying mechanisms remain poorly understood. Fatty acid 2-hydroxylase (FA2H) catalyzes the conversion of fatty acids to chiral specific (R)-2-hydroxy fatty acids ((R)-2-OHFAs), which influences cell metabolism. However, little is known about its potential coupling with GSIS in pancreatic β cells. Here, we showed that Fa2h knockout decreases plasma membrane localization and protein level of glucose transporter 2 (GLUT2), which is essential for GSIS, thereby controlling blood glucose homeostasis. Conversely, FA2H overexpression increases GLUT2 on the plasma membrane and enhances GSIS. Mechanistically, FA2H suppresses the internalization and trafficking of GLUT2 to the lysosomes for degradation. Overexpression of wild-type FA2H, but not its mutant with impaired hydroxylase activity in the pancreatic β-cells, improves glucose tolerance by promoting insulin secretion. Levels of 2-OHFAs and Fa2h gene expression are lower in high-fat diet-induced obese mouse islets with impaired GSIS. Moreover, lower gene expression of FA2H is observed in a set of human T2D islets when the insulin secretion index is significantly suppressed, indicating the potential involvement of FA2H in regulating mouse and human GSIS. Collectively, our results identified an FA chemical switch to maintain the proper response of GSIS in pancreatic β cells and provided a new perspective on the β-cell failure that triggers T2D.

Vagal sensory neuron-derived FGF3 controls insulin secretion

Vagal nerve stimulation has emerged as a promising modality for treating a wide range of chronic conditions, including metabolic disorders. However, the cellular and molecular pathways driving these clinical benefits remain largely obscure. Here, we demonstrate that fibroblast growth factor 3 (Fgf3) mRNA is upregulated in the mouse vagal ganglia under acute metabolic stress. Systemic and vagal sensory overexpression of Fgf3 enhanced glucose-stimulated insulin secretion (GSIS), improved glucose excursion, and increased energy expenditure and physical activity. Fgf3-elicited insulinotropic and glucose-lowering responses were recapitulated when overexpression of Fgf3 was restricted to the pancreas-projecting vagal sensory neurons. Genetic ablation of Fgf3 in pancreatic vagal afferents exacerbated high-fat diet-induced glucose intolerance and blunted GSIS. Finally, electrostimulation of the vagal afferents enhanced GSIS and glucose clearance independently of efferent outputs. Collectively, we demonstrate a direct role for the vagal afferent signaling in GSIS and identify Fgf3 as a vagal sensory-derived metabolic factor that controls pancreatic β-cell activity.

The role of magnesium in pancreatic beta-cell function and homeostasis.

Magnesium plays an essential role in glucose utilization and insulin signaling. Recent advances have revealed a greater prevalence of hypomagnesemia in general, and low intracellular magnesium levels in individuals with diabetes contribute to β-cell dysfunction and insulin resistance. This article describes the documented effects of magnesium on various aspects of β-cells and glucose homeostasis. Studies have demonstrated that magnesium deficiency is associated with reduced pancreatic β-cell activity and increased insulin resistance in patients with type 2 diabetes. Additionally, magnesium is involved in many cellular events, including energy homeostasis, protein synthesis, and DNA stability. Furthermore, magnesium is critical for proper glucose utilization and insulin signaling, and magnesium deficiency can lead to the dysregulation of ATP-sensitive potassium (KATP) channels in pancreatic β-cells, impairing insulin secretion. Therefore, maintaining adequate magnesium levels is crucial for maintaining overall health and preventing of metabolic disorders such as type 2 diabetes.

Peroxyredoxin 6 Protects RIN-M5F Pancreatic Beta Cells Against Streptozotocin-Induced Senescence.

There are evidences that a decrease in the functional activity of pancreatic β-cells under type 2 diabetes conditions may be associated with their senescence, therefore, senotherapy may be a prospective strategy for the diabetes treatment. The senotherapeutic potential of peroxiredoxin 6 (PRDX6) was studied in RIN-m5F pancreatic β-cells with streptozotocin-induced senescence by measuring markers, associated with senescence. Exposure to streptozotocin (STZ) resulted in the senescence of the β-cells. The addition of PRDX6 to the culture medium of RIN-m5F β-cells before treatment with STZ decreased the levels of the following senescence markers: the percentage of SA-β-Gal-positive cells, the phosphorylation of histone H2AX and p21 proteins, and the secretion of the proinflammatory cytokine IL-6 but not the anti-inflammatory cytokine IL-10. These effects were accompanied by a decrease in the production of reactive oxygen species (ROS) and the restoration of impaired NF-κB activation. In addition, PRDX6 altered the production of the heat shock protein HSP90: the production of the constitutive form of HSP90-beta decreased, while the level of inducible HSP90-alpha increased. PRDX6 prevented the senescence of RIN-m5F cells in response to the DNA damage-inducing agent streptozotocin, indicating a potential protective role of PRDX6 in type 2 diabetes mellitus.

Glucokinase activity controls subpopulations of β-cells that alternately lead islet Ca2+ oscillations.

Oscillations in insulin secretion, driven by islet Ca2+ waves, are crucial for glycemic control. Prior studies, performed with single-plane imaging, suggest that subpopulations of electrically coupled β-cells have privileged roles in leading and coordinating the propagation of Ca2+ waves. Here, we used 3D light-sheet imaging to analyze the location and Ca2+ activity of single β-cells within the entire islet at >2 Hz. In contrast with single-plane studies, 3D network analysis indicates that the most highly synchronized β-cells are located at the islet center, and remain regionally but not cellularly stable between oscillations. This subpopulation, which includes 'hub cells', is insensitive to changes in fuel metabolism induced by glucokinase and pyruvate kinase activation. β-cells that initiate the Ca2+ wave ('leaders') are located at the islet periphery, and strikingly, change their identity over time via rotations in the wave axis. Glucokinase activation, which increased oscillation period, reinforced leader cells and stabilized the wave axis. Pyruvate kinase activation, despite increasing oscillation frequency, had no effect on leader cells, indicating the wave origin is patterned by fuel input. These findings emphasize the stochastic nature of the β-cell subpopulations that control Ca2+ oscillations and identify a role for glucokinase in spatially patterning 'leader' β-cells.

Low-intensity pulsed ultrasound ameliorates insulin resistance in type 2 diabetes mice via promoting glucagon-like peptide-1 release

Abstract Glucagon-like peptide-1 (GLP-1) is a hormone secreted by intestinal L-cells. It regulates glucose levels by boosting insulin secretion, inhibiting glucagon release, and preventing β-cell death. GLP-1 is increasingly used in managing type 2 diabetes mellitus (T2DM). This study assessed the effectiveness of low-intensity pulsed ultrasound (LIPUS), a non-pharmacological intervention, in enhancing insulin resistance in diabetic mice by stimulating GLP-1 release. T2DM was induced in C57BL/6J mice through a high-fat diet and streptozotocin injection. Mice were divided into Control, T2D-sham and T2D-LIPUS groups. The T2D-LIPUS group received LIPUS treatment with a frequency of 1MHz, intensity of 120mW/cm2, and duty cycle of 20%for 20 minutes/day, 5 days/week for 4 weeks. Glucose tolerance and insulin resistance were measured through tests. Pancreatic histology and GLP-1 expression in serum were evaluated. Results showed that T2DM increased insulin resistance, but LIPUS treatment alleviated it. GLP-1 levels significantly increased in the T2D-LIPUS group compared to the T2D-sham group, approaching the control group’s level. LIPUS also reduced apoptosis of islet β cells. These findings suggest that LIPUS stimulation of the intestine can enhance islet β-cell activity through GLP-1 regulation of the gut-pancreas axis, mitigating insulin resistance in T2DM.

From Gut to Glucose: A Comprehensive Review on Functional Foods and Dietary Interventions for Diabetes Management.

In the realm of diabetes research, considerable attention has been directed toward elucidating the intricate interplay between the gastrointestinal tract and glucose regulation. The gastrointestinal tract, once exclusively considered for its role in digestion and nutrient assimilation, is presently acknowledged as a multifaceted ecosystem with regulatory supremacy over metabolic homeostasis and glucose metabolism. Recent studies indicate that alterations in the composition and functionality of the gut microbiota could potentially influence the regulation of glucose levels and glucose homeostasis in the body. Dysbiosis, characterized by perturbations in the equilibrium of gut microbial constituents, has been irrevocably linked to an augmented risk of diabetes mellitus (DM). Moreover, research has revealed the potential influence of the gut microbiota on important factors, like inflammation and insulin sensitivity, which are key contributors to the onset and progression of diabetes. The key protagonists implicated in the regulation of glucose encompass the gut bacteria, gut barrier integrity, and the gut-brain axis. A viable approach to enhance glycemic control while concurrently mitigating the burden of comorbidities associated with diabetes resides in the strategic manipulation of the gut environment through adapted dietary practices. This review aimed to provide a deep understanding of the complex relationship between gut health, glucose metabolism, and diabetes treatment. This study has presented an exhaustive overview of dietary therapies and functional foods that have undergone extensive research to explore their potential advantages in the management of diabetes. It looks into the role of gut health in glucose regulation, discusses the impact of different dietary elements on the course of diabetes, and evaluates how well functional foods can help with glycemic control. Furthermore, it investigates the mechanistic aspects of these therapies, including their influence on insulin sensitivity, β-cell activity, and inflammation. It deliberates on the limitations and potential prospects associated with integrating functional foods into personalized approaches to diabetes care.

Role of β-cell autophagy in β-cell physiology and the development of diabetes.

Elucidating the molecular mechanism of autophagy was a landmark in understanding not only the physiology of cells and tissues, but also the pathogenesis of diverse diseases, including diabetes and metabolic disorders. Autophagy of pancreatic β-cells plays a pivotal role in the maintenance of the mass, structure and function of β-cells, whose dysregulation can lead to abnormal metabolic profiles or diabetes. Modulators of autophagy are being developed to improve metabolic profile and β-cell function through the removal of harmful materials and rejuvenation of organelles, such as mitochondria and endoplasmic reticulum. Among the known antidiabetic drugs, glucagon-like peptide-1 receptor agonists enhance the autophagic activity of β-cells, which might contribute to the profound effects of glucagon-like peptide-1 receptor agonists on systemic metabolism. In this review, the results from studies on the role of autophagy in β-cells and their implication in the development of diabetes are discussed. In addition to non-selective (macro)autophagy, the role and mechanisms of selective autophagy and other minor forms of autophagy that might occur in β-cells are discussed. As β-cell failure is the ultimate cause of diabetes and unresponsiveness to conventional therapy, modulation of β-cell autophagy might represent a future antidiabetic treatment approach, particularly in patients who are not well managed with current antidiabetic therapy.

Interplay of Transcriptional Factors In Beta Cells Development and Maturation

Diabetes is a group of metabolic disorders resulting from defects in insulin secretion, insulin action, or both. It is characterized by high blood sugar levels over a prolonged period of time with disturbances of carbohydrate, protein, and fat metabolism. It is a global disorder affecting about half a billion or 536.6 million people worldwide, which is said to rise to 783.2 million by 2045. To maintain normoglycemia, pancreatic β-cells release insulin in proportion to the amounts of nutrients in the blood. Through a process of postnatal development, β-cells learn to connect insulin release to food cues. The insulin secretory response in mature β-cells adjusts to alterations in nutritional status. The interaction between transcriptional programs specific to each cell type and external stimuli is necessary for both β-cell maturation and functional adaptation. In this review, we examine the growing data that suggests lineage-determining and signal-dependent transcription factors (LDTFs and SDTFs, respectively) work together to regulate β-cell activity during development and homeostasis. In-depth knowledge of β-cell SDTFs and their corresponding signals would clarify the processes involved in β-cell maturation and functional adaptation, directly affecting diabetes treatments and the production of mature β-cells from stem cells.

Multi-omics Investigations in Endocrine Systems and Their Clinical Implications.

Innovative techniques such as the "omics" can be a powerful tool for the understanding of intracellular pathways involved in homeostasis maintenance and identification of new potential therapeutic targets against endocrine-metabolic disorders. Over the last decades, proteomics has been extensively applied in the study of a wide variety of human diseases, including those involving the endocrine system. Among the most endocrine-related disorders investigated by proteomics in humans are diabetes mellitus and thyroid, pituitary, and reproductive system disorders. In diabetes, proteins implicated in insulin signaling, glucose metabolism, and β-cell activity have been investigated. In thyroid diseases, protein expression alterations were described in thyroid malignancies and autoimmune thyroid illnesses. Additionally, proteomics has been used to investigate the variations in protein expression in adrenal cancers and conditions, including Cushing's syndrome and Addison's disease. Pituitary tumors and disorders including acromegaly and hypopituitarism have been studied using proteomics to examine changes in protein expression. Reproductive problems such as polycystic ovarian syndrome and endometriosis are two examples of conditions where alterations in protein expression have been studied using proteomics. Proteomics has, in general, shed light on the molecular underpinnings of many endocrine-related illnesses and revealed promising biomarkers for both their detection and treatment. The capacity of proteomics to thoroughly and objectively examine complex protein mixtures is one of its main benefits. Mass spectrometry (MS) is a widely used method that identifies and measures proteins based on their mass-to-charge ratio and their fragmentation pattern. MS can perform the separation of proteins according to their physicochemical characteristics, such as hydrophobicity, charge, and size, in combination with liquid chromatography. Other proteomics techniques include protein arrays, which enable the simultaneous identification of several proteins in a single assay, and two-dimensional gel electrophoresis (2D-DIGE), which divides proteins depending on their isoelectric point and molecular weight. This chapter aims to summarize the most relevant proteomics data from targeted tissues, as well as the daily rhythmic variation of relevant biomarkers in both physiological and pathophysiological conditions within the involved endocrine system, especially because the actual modern lifestyle constantly imposes a chronic unentrained condition, which virtually affects all the circadian clock systems within human's body, being also correlated with innumerous endocrine-metabolic diseases.

New-Generation Glucokinase Activators: Potential Game-Changers in Type 2 Diabetes Treatment.

Achieving glycemic control and sustaining functional pancreatic β-cell activity remains an unmet medical need in the treatment of type 2 diabetes mellitus (T2DM). Glucokinase activators (GKAs) constitute a class of anti-diabetic drugs designed to regulate blood sugar levels and enhance β-cell function in patients with diabetes. A significant progression in GKA development is underway to address the limitations of earlier generations. Dorzagliatin, a dual-acting GKA, targets both the liver and pancreas and has successfully completed two phase III trials, demonstrating favorable results in diabetes treatment. The hepato-selective GKA, TTP399, emerges as a strong contender, displaying clinically noteworthy outcomes with minimal adverse effects. This paper seeks to review the current literature, delve into the mechanisms of action of these new-generation GKAs, and assess their efficacy and safety in treating T2DM based on published preclinical studies and recent clinical trials.

The comparison of the antidiabetic effects of exenatide, empagliflozin, quercetin, and combination of the drugs in type 2 diabetic rats.

Type 2 diabetes, a metabolic disease that involves extended treatment, is rapidly increasing in humans and animals worldwide. This study aimed to compare monotherapy and combined therapy of exenatide, empagliflozin, and quercetin in 67 Wistar Albino male rats. The animals were divided into the following seven groups: healthy control, diabetes control, diabetes + sham, diabetes + exenatide (10μg/kg), diabetes + empagliflozin (50 mg/kg), diabetes + quercetin (50 mg/kg), and diabetes + combination treatment. The treatments were continued for 8 weeks. At the end of the experiment, glucose and HbA1c levels decreased with all monotherapy treatments and the combination treatments, while insulin levels increased with exenatide and combined treatments. Adiponectin levels increased with empagliflozin, quercetin, and combined treatments, while leptin levels decreased only with combined treatments. All monotherapies caused an increase in total antioxidant levels. Exenatide and quercetin treatments reduced low-density lipoprotein (LDL) levels; therewithal, exenatide and combined treatments increased high-density lipoprotein (HDL) levels. Triglyceride levels decreased in all treatment groups. The homeostatic model assessment for insulin resistance (HOMA-IR) level decreased with the combined treatment; on the contrary, the homeostatic model assessment for β-cell activity (HOMA-β) level increased with empagliflozin, exenatide, and combined treatments. In conclusion, the antidiabetic effects of exenatide were more pronounced than empagliflozin and quercetin, however, the combined treatment had better antidiabetic and antihyperlipidemic effects than monotherapies. Quercetin could be a supportive or food supplement antidiabetic agent. The exenatide treatment can be recommended for monotherapy in type 2 patients, and the combination of empagliflozin, exenatide, and quercetin may be effective in diabetic patients who need combined therapy.

A composite capsule strategy to support longevity of microencapsulated pancreatic β cells

Pancreatic islet microencapsulation allows transplantation of insulin producing cells in absence of systemic immunosuppression, but graft survival is still limited. In vivo studies have demonstrated that many islet-cells die in the immediate period after transplantation. Here we test whether intracapsular inclusion of ECM components (collagen IV and RGD) with necrostatin-1 (Nec-1), as well as amino acids (AA) have protective effects on islet survival. Also, the inclusion of pectin was tested as it enhances the mitochondrial health of β-cells. To enhance the longevity of encapsulated islets, we studied the impact of the incorporation of the mentioned components into the alginate-based microcapsules in vitro. The efficacy of the different composite microcapsules on MIN6 β-cell or human islet-cell survival and function, as well as suppression of DAMP-induced immune activation, were determined. Finally, we examined the mitochondrial dynamic genes. This was done in the absence and presence of a cytokine cocktail. Here, we found that composite microcapsules of APENAA improved insulin secretion and enhanced the mitochondrial activity of β-cells. Under cytokine exposure, they prevented the cytokine-induced decrease of mitochondrial activity as well as viability till day 5. The rescuing effects of the composite capsules were accompanied by alleviated mitochondrial dynamic gene expression. The composite capsule strategy of APENAA might support the longevity of microencapsulated β-cells by lowering susceptibility to inflammatory stress. Our data demonstrate that combining strategies to support β-cells by changing the intracapsular microenvironment might be an effective way to preserve islet graft longevity in the immediate period after transplantation.

XBP1 splicing contributes to endoplasmic reticulum stress-induced human islet amyloid polypeptide up-regulation

As a pathological hallmark of type 2 diabetes mellitus (T2DM), islet amyloid is formed by the aggregation of islet amyloid polypeptide (IAPP). Endoplasmic reticulum (ER) stress interacts with IAPP aggregates and has been implicated in the pathogenesis of T2DM. To examine the role of ER stress in T2DM, we cloned the hIAPP promoter and analyzed its promoter activity in human β-cells. We found that ER stress significantly enhanced hIAPP promoter activity and expression in human β-cells via triggering X-box binding protein 1 (XBP1) splicing. We identified a binding site of XBP1 in the hIAPP promoter. Disruption of this binding site by substitution or deletion mutagenesis significantly diminished the effects of ER stress on hIAPP promoter activity. Blockade of XBP splicing by MKC3946 treatment inhibited ER stress-induced hIAPP up-regulation and improved human β-cell survival and function. Our study uncovers a link between ER stress and IAPP at the transcriptional level and may provide novel insights into the role of ER stress in IAPP cytotoxicity and the pathogenesis of T2DM.

Transcriptome and secretome profiling of sensory neurons reveals sex differences in pathways relevant to insulin sensing and insulin secretion.

Sensory neurons in the dorsal root ganglia (DRG) convey somatosensory and metabolic cues to the central nervous system and release substances from stimulated terminal endings in peripheral organs. Sex-biased variations driven by the sex chromosome complement (XX and XY) have been implicated in the sensory-islet crosstalk. However, the molecular underpinnings of these male-female differences are not known. Here, we aim to characterize the molecular repertoire and the secretome profile of the lower thoracic spinal sensory neurons and to identify molecules with sex-biased insulin sensing- and/or insulin secretion-modulating activity that are encoded independently of circulating gonadal sex hormones. We used transcriptomics and proteomics to uncover differentially expressed genes and secreted molecules in lower thoracic T5-12 DRG sensory neurons derived from sexually immature 3-week-old male and female C57BL/6J mice. Comparative transcriptome and proteome analyses revealed differential gene expression and protein secretion in DRG neurons in males and females. The transcriptome analysis identified, among others, higher insulin signaling/sensing capabilities in female DRG neurons; secretome screening uncovered several sex-specific candidate molecules with potential regulatory functions in pancreatic β cells. Together, these data suggest a putative role of sensory interoception of insulin in the DRG-islet crosstalk with implications in sensory feedback loops in the regulation of β-cell activity in a sex-biased manner. Finally, we provide a valuable resource of molecular and secretory targets that can be leveraged for understanding insulin interoception and insulin secretion and inform the development of novel studies/approaches to fathom the role of the sensory-islet axis in the regulation of energy balance in males and females.

Single cell multiomic analysis reveals diabetes-associated β-cell heterogeneity driven by HNF1A

Broad heterogeneity in pancreatic β-cell function and morphology has been widely reported. However, determining which components of this cellular heterogeneity serve a diabetes-relevant function remains challenging. Here, we integrate single-cell transcriptome, single-nuclei chromatin accessibility, and cell-type specific 3D genome profiles from human islets and identify Type II Diabetes (T2D)-associated β-cell heterogeneity at both transcriptomic and epigenomic levels. We develop a computational method to explicitly dissect the intra-donor and inter-donor heterogeneity between single β-cells, which reflect distinct mechanisms of T2D pathogenesis. Integrative transcriptomic and epigenomic analysis identifies HNF1A as a principal driver of intra-donor heterogeneity between β-cells from the same donors; HNF1A expression is also reduced in β-cells from T2D donors. Interestingly, HNF1A activity in single β-cells is significantly associated with lower Na+ currents and we nominate a HNF1A target, FXYD2, as the primary mitigator. Our study demonstrates the value of investigating disease-associated single-cell heterogeneity and provides new insights into the pathogenesis of T2D.

Lower serum zinc level is associated with higher fasting insulin in type 2 diabetes mellitus (T2DM) and relates with disturbed glucagon suppression response in male patients

AimsZinc ion can play critical role in glycemic control in diabetes mellitus (DM), contributing to both insulin synthesis and secretion. In this study, we aimed to investigate the level of zinc in diabetic patients and its association with glycemic parameters, insulin, and glucagon level. Methods: 112 individuals (59 cases of type 2DM and 53 non-diabetic controls) were included in this study. Biochemical parameters (FBG, 2hpp, HbA1C), and zinc level in the serum were measured using colorimetric assays. Insulin and glucagon were measured by ELISA method. HOMA-IR, HOMA-B, reciprocal HOMA-B, and Quicki indices were calculated using appropriate formula. For further analysis, patients were divided into two groups: high (>135.5 μg/dl) and low (<135.5 μg/dl) zinc. Glucagon suppression was considered yes if 2hpp glucagon < fasting glucagon. Results: Our results showed that serum Zn level in type 2 DM patients was lower than control (P value=0.02). Patients with lower Zn had higher fasting insulin (P value=0.006) and higher β-cell activity index (HOMA-B, p value=0.02), however fasting glucagon and parameters of hyperglycemia (FBG, 2hpp, Hba1C) were not different. Moreover, insulin sensitivity and resistance indices (Quicki, HOMA-IR,1/HOMA-IR) showed non-significantly improved status in high Zn group. We found non-significant association between glucagon suppression and Zn level in both genders (N = 39, p value = 0.07), however, it was significant in males (N = 14, p value = 0.02). Conclusion: Altogether, our results indicated reduced serum Zn in type 2DM can exacerbate hyperinsulinemia and glucagon suppression (only significant in the male), highlighting its importance in type 2DM control.

230-LB: A Composite Capsule Strategy Support Longevity of Microencapsulated Pancreatic ß Cells

Microencapsulation of islets in immunoprotective membranes offers an alternative treatment for type 1 diabetes in absence of systemic immunosuppression. However, periods of survival of transplanted islets are still limited. A factor that might be involved in a limited duration of survival is permanent damage to the extracellular matrix (ECM) during enzymatic islet-isolation which enhances susceptibility of islets for inflammatory stress. Here we investigated whether a combination of inclusion of ECM components (collagen IV and RGD), necroptosis inhibitor necrostatin-1 (Nec-1), amino acids (AA), and inclusion of the immunomodulatory polymer pectin in microcapsules can enhance the functionality of β-cells. The impact of these factors individually or combined was tested on MIN6 β-cells and human islet-cells. Viability, function, and immune activation via danger-associated molecular patterns (DAMPs) release and NF-κB activation in THP1-reporter cells were determined. Also, impact on mitochondrial dynamics was tested. Our data show that composite capsules of pectin/ECM/Nec-1/AA improve insulin secretion and enhance the mitochondrial activity of β-cells in vitro till day 7 after encapsulation. The alginate-pectin based microcapsules also showed immunomodulatory effects with decreased DAMPs release and lower NF-κB activation. After cytokine exposure, pectin/ECM/Nec-1/AA prevented the cytokine-induced decrease of mitochondrial activity and prevented viability loss until day 5. The rescuing effects were accompanied by modulation of mitochondrial fusion and fission gene expression, similar to that of untreated controls. Our data suggest that this composite capsule strategy using pectin/ECM/Nec-1/AA supports survival of microencapsulated β-cells and lowers susceptibility of β-cells for inflammatory stress. This strategy to create a better intracapsular microenvironment is a potentially promising way to preserve islet function and enhance graft survival time. Disclosure T. Qin: None. A. M. Smink: None. P. De vos: None. Funding JDRF (2-SRA-2018-523-S-B); China Scholarship Council (201906230339)

Beta Cell Dysfunction in Youth- and Adult-Onset Type 2 Diabetes: An Extensive Narrative Review with a Special Focus on the Role of Nutrients.

Traditionally a disease of adults, type 2 diabetes (T2D) has been increasingly diagnosed in youth, particularly among adolescents and young adults of minority ethnic groups. Especially, during the recent COVID-19 pandemic, obesity and prediabetes have surged not only in minority ethnic groups but also in the general population, further raising T2D risk. Regarding its pathogenesis, a gradually increasing insulin resistance due to central adiposity combined with a progressively defective β-cell function are the main culprits. Especially in youth-onset T2D, a rapid β-cell activity decline has been observed, leading to higher treatment failure rates, and early complications. In addition, it is well established that both the quantity and quality of food ingested by individuals play a key role in T2D pathogenesis. A chronic imbalance between caloric intake and expenditure together with impaired micronutrient intake can lead to obesity and insulin resistance on one hand, and β-cell failure and defective insulin production on the other. This review summarizes our evolving understanding of the pathophysiological mechanisms involved in defective insulin secretion by the pancreatic islets in youth- and adult-onset T2D and, further, of the role various micronutrients play in these pathomechanisms. This knowledge is essential if we are to curtail the serious long-term complications of T2D both in pediatric and adult populations.