Human beta cell mass and function in diabetes: Recent advances in knowledge and technologies to understand disease pathogenesis

Hyperglucagonemia and glucagon hypersecretion in early type 2 diabetes result from multifaceted dysregulation of pancreatic mouse α-cells

Hyperglucagonemia has been implicated in the pathogenesis of type 2 diabetes (T2D). In contrast to β-cells, studies on the function of the pancreatic α-cell in T2D are scarce. Consequently, the processes underlying hyperglucagonemia and α-cell dysfunction are largely unknown, limiting the appropriate design of specific pharmacological and therapeutic strategies. In the current study, we aimed to analyze the alterations of the pancreatic α-cell and its glucagon responses in diabetic db/db mice at early stages of the disease. In this context of glucose intolerance, hyperinsulinemia, and β-cell dysfunction, hyperglucagonemia was only present at fed conditions and was associated with insulin resistance. Yet, we found that the glucagon-to-insulin ratio in db/db mice did not change with fed or fasted states, further supporting that the metabolic regulation of glucagon release was impaired. Pancreatic β-cell dysfunction in db/db mice was manifested by increased basal secretion from isolated islets along with reduced insulin content. In contrast, α-cells from diabetic animals presented upregulated secretion and islet content of glucagon compared with controls. Electrophysiological analysis of dispersed α-cells revealed that altered secretion was not the result of impaired exocytosis. Instead, we found defective regulation of Ca2+ signaling by glucose. Besides these functional alterations, we also observed augmented α-cell mass in diabetic mice, which was accompanied by disrupted islet cytoarchitecture as well as increased α-cell size and number, without pieces of evidence of upregulated proliferation. Overall, these findings indicate that hyperglucagonemia in early T2D results from multifaceted α-cell deregulation in mice.

Promotion of beta cell proliferation through DYRK kinase inhibition using the marine natural product breitfussin C

Pro-inflammatory cytokines, like interleukin-1 beta and interferon gamma, are known to activate signalling pathways causing pancreatic beta cell death and dysfunction, contributing to the onset of diabetes. Targeting cytokine signalling pathways offers a potential strategy to slow or even halt disease progression, reducing reliance on exogenous insulin and improving glucose regulation. This study explores the protective and proliferative effects of breitfussin C (BfC), a natural compound isolated from the Arctic marine hydrozoan Thuiaria breitfussi, on pancreatic beta cells exposed to pro-inflammatory cytokines. Using the beta cell line RIN-M5F, we assessed the protective effects of BfC through a MTS assay for cell viability, caspase 3/7 activity for apoptosis, and EdU incorporation and cell cycle distribution for proliferation. Additionally, we investigated BfC's inhibitory effects on the DYRK family of kinases using kinase activity and binding assays, western blotting, and docking simulations. Our findings reveal that BfC treatment effectively increases beta cell proliferation and counteracts cytokine-induced decrease in proliferation. The proliferative effect is associated with inhibition of DYRK kinases and a subsequent decrease in the cell cycle inhibitor p27KIP. These results suggest that BfC mediates beta cell-protective effect by promoting proliferation through DYRK inhibition, highlighting its potential as a molecular starting point for the development of a therapeutic agent against diabetes.

Effects of Mesenchymal Stem Cell-conditioned Media with Natural Immunomodulatory Agent Resveratrol on Type 1 Diabetes

BACKGROUND

Type 1 diabetes mellitus (T1DM) is a condition marked by elevated blood sugar levels and primarily recognized by the destruction of beta cells caused by an autoimmune attack, which is a significant characteristic of T1DM. Recent studies have demonstrated the regenerative potential of conditioned medium therapy. In light of this, the current research sought to assess the impact of Mesenchymal Stem Cell conditioned media (CM) and CM with resveratrol (CM+ Resveratrol) on the management of T1DM in Swiss albino mice. By leveraging and modifying existing conditioned medium therapy, this study aims to evaluate its effectiveness in treating T1DM.

MATERIALS & METHODS

Diabetes was induced in animals using the diabetes-inducing agent streptozotocin (STZ). The animals were then divided into five groups: Normal control, Disease Control, Resveratrol, Condition Media, and CM + Resveratrol. Treatments were given to the animals accordingly. The study period was 28 days. During this time, the animals were monitored for foodwater intake twice a week, blood glucose levels, and body weight. At the conclusion of the 28-day study period, biochemical estimations were performed for serum insulin levels, C-peptide levels, anti-inflammatory cytokines levels and pro-inflammatory cytokines levels. Additionally, histopathology of the pancreas was performed.

RESULTS

The test groups showed a significant decrease in blood glucose levels, an increase in Cpeptide levels, and a decrease in pro-inflammatory cytokine levels compared to the disease group. However, no statistically significant change within groups was observed in terms of serum insulin and anti-inflammatory cytokine levels. The improvement in diabetic symptoms, such as polyphagia, polydipsia, and weight loss, was observed in the treatment group, along with pancreatic regeneration, which indicated improved insulin secretion.

CONCLUSION

In the current investigation, we concluded that CM and CM+ Resveratrol, as natural immunomodulators, have the capacity to regenerate injured pancreatic beta cells and have antidiabetic action, together with immunomodulating impact. Nonetheless, future studies on this therapy appear to be promising.

Stearic acid metabolism in human health and disease

Named after the Greek term for "hard fat", stearic acid has gradually entered people's field of vision. As an important component of various physiological cellular functions, stearic acid plays a regulatory role in diverse aspects of energy metabolism and signal transduction. Its applications range from serving as a bodily energy source to participating in endogenous biosynthesis. Similar to palmitate, stearic acid serves as a primary substrate for the stearoyl coenzyme A desaturase, which catalyzes the conversion of stearate to oleate and is involved in the synthesis of triglyceride and other complex lipids. Additionally, stearic acid functions as a vital signaling molecule in pathological processes such as cardiovascular diseases, diabetes development, liver injury and even nervous system disorders. Therefore, we conduct a comprehensive review of stearic acid, summarizing its role in various diseases and attempting to provide a systematic overview of its homeostasis, physiological functions, and pathological process. From a medical standpoint, we also explore potential applications and discuss stearic acid as a potential therapeutic target for the treatment of human diseases.

BETA CELL DYSFUNCTION OCCURS INDEPENDENTLY OF INSULITIS IN TYPE 1 DIABETES PATHOGENESIS

During type 1 diabetes (T1D) progression, beta cells become dysfunctional and exhibit reduced first-phase insulin release. While this period of beta cell dysfunction is well established, its cause and underlying mechanism remain unknown. To address this knowledge gap, live human pancreas tissue slices were prepared from autoantibody-negative organ donors without diabetes (ND), donors positive for one or more islet autoantibodies (AAb+), and donors with T1D within 0-4 years of diagnosis (T1D+). Dynamic imaging and physiological secretion studies were conducted to assess the extent and impact of T cell infiltration on beta cell function through immunolabeling, Ca2+ imaging, and perifusion assays for insulin secretion. Beta cells were identified in living slices by ENTPD3 cell surface staining. Beta cells from both ND and AAb+ donors exhibited normal cytosolic Ca2+ mobilization in response to high glucose and KCl. Beta cells from donors with T1D had significantly diminished Ca2+ responses to high glucose but preserved responses to KCl. In T1D, glucose responsiveness was impaired in both T cell-infiltrated and non-infiltrated insulin positive islets, supporting the concept that beta cell dysfunction is independent of close spatial association between beta cells and T cells. Fixed tissue staining and gene expression profiling of laser-capture microdissected islets revealed significant decreases in markers of glucose metabolism to ATP in beta cells from donors with T1D but no changes in endoplasmic reticulum (ER) stress markers. From these data, we posit that functional defects occur in beta cells during T1D pathogenesis independent of local T cell infiltration and beta cell destruction. Additionally, these beta cell metabolic defects contribute to the clinical manifestation of dysglycemia at T1D diagnosis despite a remaining mass of beta cells.

The Emerging Role of p21 in Diabetes and Related Metabolic Disorders

In the context of cell cycle inhibition, anti-proliferation, and the dysregulation observed in certain cancer pathologies, the protein p21 assumes a pivotal role. p21 links DNA damage responses to cellular processes such as apoptosis, senescence, and cell cycle arrest, primarily functioning as a regulator of the cell cycle. However, accumulating empirical evidence suggests that p21 is both directly and indirectly linked to a number of different metabolic processes. Intriguingly, recent investigations indicate that p21 significantly contributes to the pathogenesis of diabetes. In this review, we present a comprehensive evaluation of the scientific literature regarding the involvement of p21 in metabolic processes, diabetes etiology, pancreatic function, glucose homeostasis, and insulin resistance. Furthermore, we provide an encapsulated overview of therapies that target p21 to alleviate metabolic disorders. A deeper understanding of the complex interrelationship between p21 and diabetes holds promise for informing current and future therapeutic strategies to address this rapidly escalating health crisis.

Selective Reduction of Ca2+-Independent Phospholipase A2β (iPLA2β)-Derived Lipid Signaling From Macrophages Mitigates Type 1 Diabetes Development

Type 1 diabetes (T1D) is a consequence of autoimmune destruction of β-cells, and macrophages (MΦs) have a central role in initiating processes that lead to β-cell demise. We reported that Ca2+-independent phospholipase A2β (iPLA2β)-derived lipid (iDL) signaling contributes to β-cell death. Because MΦs express iPLA2β, we assessed its role in T1D development. We find that selective reduction of myeloid-iPLA2β in spontaneously diabetes-prone NOD mice 1) decreases proinflammatory eicosanoid production by MΦs, 2) favors the anti-inflammatory (M2-like) MΦ phenotype, and 3) diminishes activated CD4+ and CD8+ T-cells phenotype in the pancreatic infiltrate, prior to T1D onset. These outcomes are associated with a significant reduction in T1D. Further, inhibition of select proinflammatory lipid signaling pathways reduces M1-like MΦ polarization and adoptive transfer of M2-like MΦs reduces NOD T1D incidence, suggesting a mechanism by which iDLs impact T1D development. These findings identify MΦ-iPLA2β as a critical contributor to T1D development and potential target to counter T1D onset.

ARTICLE HIGHLIGHTS

Advanced therapy to cure diabetes: mission impossible is now possible?

Cell and Gene therapy are referred to as advanced therapies that represent overlapping fields of regenerative medicine. They have similar therapeutic goals such as to modify cellular identity, improve cell function, or fight a disease. These two therapeutic avenues, however, possess major differences. While cell therapy involves introduction of new cells, gene therapy entails introduction or modification of genes. Furthermore, the aim of cell therapy is often to replace, or repair damaged tissue, whereas gene therapy is used typically as a preventive approach. Diabetes mellitus severely affects the quality of life of afflicted individuals and has various side effects including cardiovascular, ophthalmic disorders, and neuropathy while putting enormous economic pressure on both the healthcare system and the patient. In recent years, great effort has been made to develop cutting-edge therapeutic interventions for diabetes treatment, among which cell and gene therapies stand out. This review aims to highlight various cell- and gene-based therapeutic approaches leading to the generation of new insulin-producing cells as a topmost "panacea" for treating diabetes, while deliberately avoiding a detailed molecular description of these approaches. By doing so, we aim to target readers who are new to the field and wish to get a broad helicopter overview of the historical and current trends of cell- and gene-based approaches in β-cell regeneration.

Non-linear connection between the triglyceride-glucose index and prediabetes risk among Chinese adults: a secondary retrospective cohort study

BACKGROUND

The triglyceride-glucose (TyG) index has garnered recognition as a surrogate marker for insulin resistance, a pivotal factor in the pathogenesis of various metabolic disorders. Despite its emerging role, the empirical evidence delineating its association with prediabetes mellitus (Pre-DM) remains scant. This research aims to clarify the link between the TyG index and the likelihood of Pre-DM development within a Chinese demographic.

METHODS

This investigation was structured as a retrospective cohort analysis, encompassing a sample of 179,177 Chinese adults. These individuals underwent medical examinations at the Rich Healthcare Group over a period spanning from 2010 to 2016. To ascertain the relationship between the TyG index and the incidence of Pre-DM, this study employed Cox regression analysis complemented by sensitivity and subgroup assessments. Furthermore, Cox proportional hazards regression with cubic spline functions and smooth curve fitting was incorporated to explore the existence of any non-linear connection within this association.

RESULTS

Upon adjusting for a comprehensive array of confounding variables, a statistically significant positive correlation between the TyG index and the risk of Pre-DM was identified (HR: 1.60, 95%CI 1.56-1.65, P < 0.001). The analysis illuminated a non-linear relationship, with an inflection point at a TyG index value of 8.78. For TyG index values below and above this inflection point, the HR was calculated to be 1.94 (95%CI 1.86-2.03) and 1.26 (95%CI 1.20-1.33), respectively. Sensitivity analyses further fortified the reliability of these findings.

CONCLUSIONS

This comprehensive examination delineated a significantly positive, non-linear correlation between the TyG index and the risk of Pre-DM within a Chinese population. Individuals with TyG index values below 8.78 have a significantly increased risk of developing prediabetes. These findings underscore the TyG index's potential efficacy as a predictive tool for assessing Pre-DM risk in clinical practice.

Longitudinal multimodal monitoring of transplanted islet β-cells

PURPOSE

Monitoring β-cell mass and function would provide a better understanding of diabetes, setting the stage for truly individualized therapies. We applied a combined PET/MRI protocol to monitor engrafted islets mass and function without pre-labeling of isolated cells. A PET tracer binding to GLP-1R quantifies β-cell mass, while Mn-CA characterizes β-cell function. Both parameters were assessed in transplanted and native β-cells in vivo and validated with autoradiography and mass spectrometry imaging.

METHODS

Islets were collected and transplanted into the calves of C3H-mice. Accumulation of [64Cu]Ex4 and Mn-CA was examined with a PET/MRI at 1 h post-injection between 1 and 4 weeks after the transplantation. A separate blocking study with diazoxide targeted the functionality of the transplanted islets. As validation, ex vivo autoradiography and LA-ICP-MS imaging were performed after the last imaging session.

RESULTS

PET/MRI monitored the engraftment of transplanted islets and visualized an increasing uptake of the PET tracer and Mn-CA. The Mn-CA accumulated at a higher islet-to-background ratio in the calf of mice than in the pancreas due to the high retention of Mn-CA in the exocrine pancreas. In vivo imaging data correlated well with autoradiography and LA-ICP-MS imaging, validating the in vivo approaches.

CONCLUSION

For the quantification of β-cell function, Mn-based contrast mechanisms between native and transplanted islets differ and require further studies for optimal biological readout. However, non-invasive PET/MRI nonetheless provides the tools to investigate the relationship between β-cell mass and function in pancreatic islets.

Preoperative duration of type 2 diabetes mellitus and remission after Roux-en-Y gastric bypass: a single center long-term cohort study

BACKGROUND

Roux-en-Y gastric bypass (RYGB) has demonstrated excellent glycemic control and type 2 diabetes mellitus (T2DM) remission for patients with obesity and T2DM. Duration of T2DM is a consistent negative predictor of remission after RYGB. However, the exact timing to offer surgical intervention during the course of the disease is not well elucidated.

MATERIAL AND METHODS

The authors performed a retrospective cohort study between 2008 and 2020 to establish the exact association between duration of T2DM and remission after RYGB. The authors divided our cohort into quartiles of preoperative disease duration to quantify the change in remission rates for each year of delay between T2DM diagnosis and RYGB. The authors also compared the average time to remission and changes in glycemic control parameters.

RESULTS

A total of 519 patients (67.2% female; age 53.4±10.7 year; BMI 46.6±8.4 kg/m 2 ) with a follow-up period of 6.6±3.8 years were included. Remission was demonstrated in 51% of patients. Longer duration of T2DM was a significant negative predictor of remission with an estimated decrease in remission rates of 7% for each year of delay [(OR=0.931 (95% CI: 0.892-0.971); P< 0.001)]. Compared to patients with <3 years of T2DM, remission decreased by 37% for patients with 3-6 years, 64% for those with 7-12 years, and 81% for patients with more than 12 years ( P <0.001). Half of the patients reached T2DM remission after 0.5 and 1.1 years, respectively, for the first and second quartiles, while patients in the other quartiles never reached 50% remission. Lastly, The authors noted an overall improvement in all glycemic control parameters for all quartiles at last follow-up.

CONCLUSION

Patients with a recent history of T2DM who undergo early RYGB experience significantly higher and earlier T2DM remission compared to patients with a prolonged history of preoperative T2DM, suggesting potential benefit of early surgical intervention to manage patients with obesity and T2DM.

The role and mechanism of VDAC1 in type 2 diabetes: An underestimated target of environmental pollutants

Type 2 diabetes (T2D) is a chronic metabolic disease that accounts for more than 90% of diabetic patients. Its main feature is hyperglycemia due to insulin resistance or insulin deficiency. With changes in diet and lifestyle habits, the incidence of T2D in adolescents has burst in recent decades. The deterioration in the exposure to the environmental pollutants further aggravates the prevalence of T2D, and consequently, it imposes a significant economic burden. Therefore, early prevention and symptomatic treatment are essential to prevent diabetic complications. Mitochondrial number and electron transport chain activity are decreased in the patients with T2D. Voltage-Dependent Anion Channel 1 (VDAC1), as a crucial channel protein on the outer membrane of mitochondria, regulates signal transduction between mitochondria and other cellular components, participating in various biological processes. When VDAC1 exists in oligomeric form, it additionally facilitates the entry and exit of macromolecules into and from mitochondria, modulating insulin secretion. We summarize and highlight the interplay between VDAC1 and T2D, especially in the environmental pollutants-related T2D, shed light on the potential therapeutic implications of targeting VDAC1 monomers and oligomers, providing a new possible target for the treatment of T2D.

Integrated Transcriptomics and Proteomics Identified CMPK1 as a Potential Biomarker for Type 2 Diabetes Mellitus

Aim/Introduction

Type 2 diabetes mellitus (T2DM) is one of the most frequent and widespread disease in the world.Obesity is the most significant predictor of T2DM, but the exact mechanism how obesity promotes T2DM remains unknown. Finding specific biomarkers to assist in diagnosing and treating patients with obese and T2DM is critical.

Materials and Methods

We collected liver tissues from obesity patients with and without T2DM for proteomic sequencing and immunohistochemistry assay. Analysis Gene Ontology(GO) enrichment, Kyoto Encyclopedia of Genes and Genomes(KEGG), and protein interaction network (PPI) were performed on the parameters and data derived from the Tandem Mass Tags(TMT)-based proteomics analysis of liver tissues. Transcriptome data were downloaded from the Gene Expression Omnibus(GEO)website and genes that are deferentially expressed in both transcriptome and proteome were selected.

Results

We identified 140 deferentially expressed proteins from proteomic sequencing. Six biomarkers were deferentially expressed in both proteome and transcriptome with consistent changes in direction. The protein-protein interaction (PPI) analysis suggested CMPK1, the expression with greatest difference, was the core protein among the six biomarkers. Immunohistochemistry validated CMPK1 was upregulated significantly in the liver tissues of T2DM patients. The correlation analysis revealed that the expression of CMPK1 was significantly associated with key molecules in T2DM-related pathways at both protein and transcriptome levels.

Conclusion and Novelty

Our study showed CMPK1 was upregulated in the liver of T2DM patients and provides a possible new target for screening and diagnosing T2DM in patients with obese and a novel theoretical basis for the pathophysiological mechanism of obesity-related metabolic diseases.

β-Cell keratin 8 maintains islet mechanical integrity, mitochondrial ultrastructure, and β-cell glucose transporter 2 plasma membrane targeting

Islet β-cell dysfunction is an underlying factor for type I diabetes (T1D) development. Insulin sensing and secretion are tightly regulated in β-cells at multiple subcellular levels. The epithelial intermediate filament (IF) protein keratin (K) 8 is the main β-cell keratin, constituting the filament network with K18. To identify the cell-autonomous functions of K8 in β-cells, mice with targeted deletion of β-cell K8 (K8flox/flox; Ins-Cre) were analyzed for islet morphology, ultrastructure, and integrity, as well as blood glucose regulation and streptozotocin (STZ)-induced diabetes development. Glucose transporter 2 (GLUT2) localization was studied in β-cells in vivo and in MIN6 cells with intact or disrupted K8/K18 filaments. Loss of β-cell K8 leads to a major reduction in K18. Islets without β-cell K8 are more fragile, and these β-cells display disjointed plasma membrane organization with less membranous E-cadherin and smaller mitochondria with diffuse cristae. Lack of β-cell K8 also leads to a reduced glucose-stimulated insulin secretion (GSIS) response in vivo, despite undisturbed systemic blood glucose regulation. K8flox/flox, Ins-Cre mice have a decreased sensitivity to STZ compared with K8 wild-type mice, which is in line with decreased membranous GLUT2 expression observed in vivo, as GLUT2 is required for STZ uptake in β-cells. In vitro, MIN6 cell plasma membrane GLUT2 is rescued in cells overexpressing K8/K18 filaments but mistargeted in cells with disrupted K8/K18 filaments. β-Cell K8 is required for islet and β-cell structural integrity, normal mitochondrial morphology, and GLUT2 plasma membrane targeting, and has implications on STZ sensitivity as well as systemic insulin responses.NEW & NOTEWORTHY Keratin 8 is the main cytoskeletal protein in the cytoplasmic intermediate filament network in β-cells. Here for the first time, we assessed the β-cell autonomous mechanical and nonmechanical roles of keratin 8 in β-cell function. We demonstrated the importance of keratin 8 in islet and β-cell structural integrity, maintaining mitochondrial morphology and GLUT2 plasma membrane targeting.

Latilactobacillus sakei QC9 alleviates hyperglycaemia in high-fat diet and streptozotocin-induced type 2 diabetes mellitus mice via the microbiota-gut-liver axis

Probiotics have been considered a promising option for mitigating the progression of type 2 diabetes mellitus (T2DM). Here, Latilactobacillus sakei QC9 (L. sakei QC9) with a hypoglycemic effect was screened out from 30 food-derived strains through α-glucosidase and α-amylase activity inhibition tests in vitro and a 4-week in vivo preliminary animal experiment. To further understand its alleviating effect on long-term hyperglycaemia occurring in T2DM, we conducted an experiment that lasted for 8 weeks. The results showed that taking L. sakei QC9 can regulate glucose and lipid metabolism while improving the antioxidant capacity and alleviating chronic inflammation. In addition, our results demonstrated that L. sakei QC9 may mediate the microbiota-gut-liver axis by regulating the composition of intestinal flora (increasing the abundance of butyrate-producing bacteria) and increasing the content of short-chain fatty acids (especially butyrate), affecting the PI3K/Akt signalling pathway in the liver, thereby achieving the purpose of alleviating the development of T2DM. In summary, our work is the first to prove the long-term hypoglycemic effect of L. sakei in high-fat diet (HFD) and streptozotocin (STZ)-induced T2DM mice and supports the possibility of L. sakei QC9 being used as a new treatment for alleviating T2DM.

Comprehensive Characterization of Islet Remodeling in Development and in Diabetes Using Mass Cytometry

The pancreatic islet is the functional and structural unit of the pancreatic endocrine portion. Islet remodeling occurs in both normal development and pathogenesis of type 1 (T1D) and type 2 diabetes (T2D). However, accurately quantifying changes in islet cellular makeup and hormone expressions poses significant challenges due to large intra- and inter-donor heterogeneity and the limited scalability of traditional methods such as immunostaining. The cytometry by time-of-flight (CyTOF) technology enables simultaneous quantification of more than 30 protein markers at single-cell resolution in a high-throughput fashion. Moreover, with distinct DNA and viability markers, single live cells can be explicitly selected in CyTOF. Here, leveraging the CyTOF data generated by the Human Pancreas Analysis Program, we characterized more than 12 million islet cells from 71 donors. Our data revealed continued age-related changes in islet endocrine cell compositions, but the maturity of endocrine cells is reached by 3 years of age. We also observed significant changes in beta cell numbers and key protein expressions, along with a significant increase in bihormonal cells in T1D donors. In contrast, T2D donors exhibited minimal islet remodeling events. Our data shine a light on the islet dynamics during development and diabetes pathogenesis and suggest divergent pathogenesis processes of T1D and T2D. Our comprehensive approach not only elucidates islet plasticity but also establishes a foundation for integrated CyTOF analysis in islet biology and beyond.

Establishing evidence for immune surveillance of β-cell senescence

Cellular senescence is a programmed state of cell cycle arrest that involves a complex immunogenic secretome, eliciting immune surveillance and senescent cell clearance. Recent work has shown that a subpopulation of pancreatic β-cells becomes senescent in the context of diabetes; however, it is not known whether these cells are normally subject to immune surveillance. In this opinion article, we advance the hypothesis that immune surveillance of β-cells undergoing a senescence stress response normally limits their accumulation during aging and that the breakdown of these mechanisms is a driver of senescent β-cell accumulation in diabetes. Elucidation and therapeutic activation of immune surveillance mechanisms in the pancreas holds promise for the improvement of approaches to target stressed senescent β-cells in the treatment of diabetes.

Optogenetic stimulation of vagal nerves for enhanced glucose-stimulated insulin secretion and β cell proliferation

The enhancement of insulin secretion and of the proliferation of pancreatic β cells are promising therapeutic options for diabetes. Signals from the vagal nerve regulate both processes, yet the effectiveness of stimulating the nerve is unclear, owing to a lack of techniques for doing it so selectively and prolongedly. Here we report two optogenetic methods for vagal-nerve stimulation that led to enhanced glucose-stimulated insulin secretion and to β cell proliferation in mice expressing choline acetyltransferase-channelrhodopsin 2. One method involves subdiaphragmatic implantation of an optical fibre for the photostimulation of cholinergic neurons expressing a blue-light-sensitive opsin. The other method, which suppressed streptozotocin-induced hyperglycaemia in the mice, involves the selective activation of vagal fibres by placing blue-light-emitting lanthanide microparticles in the pancreatic ducts of opsin-expressing mice, followed by near-infrared illumination. The two methods show that signals from the vagal nerve, especially from nerve fibres innervating the pancreas, are sufficient to regulate insulin secretion and β cell proliferation.

Inhibition of the eukaryotic initiation factor-2α kinase PERK decreases risk of autoimmune diabetes in mice

Preventing the onset of autoimmune type 1 diabetes (T1D) is feasible through pharmacological interventions that target molecular stress-responsive mechanisms. Cellular stresses, such as nutrient deficiency, viral infection, or unfolded proteins, trigger the integrated stress response (ISR), which curtails protein synthesis by phosphorylating eukaryotic translation initiation factor-2α (eIF2α). In T1D, maladaptive unfolded protein response (UPR) in insulin-producing β cells renders these cells susceptible to autoimmunity. We found that inhibition of the eIF2α kinase PKR-like ER kinase (PERK), a common component of the UPR and ISR, reversed the mRNA translation block in stressed human islets and delayed the onset of diabetes, reduced islet inflammation, and preserved β cell mass in T1D-susceptible mice. Single-cell RNA-Seq of islets from PERK-inhibited mice showed reductions in the UPR and PERK signaling pathways and alterations in antigen-processing and presentation pathways in β cells. Spatial proteomics of islets from these mice showed an increase in the immune checkpoint protein programmed death-ligand 1 (PD-L1) in β cells. Golgi membrane protein 1, whose levels increased following PERK inhibition in human islets and EndoC-βH1 human β cells, interacted with and stabilized PD-L1. Collectively, our studies show that PERK activity enhances β cell immunogenicity and that inhibition of PERK may offer a strategy for preventing or delaying the development of T1D.

Inhibition of the Eukaryotic Initiation Factor-2-α Kinase PERK Decreases Risk of Autoimmune Diabetes in Mice

Preventing the onset of autoimmune type 1 diabetes (T1D) is feasible through pharmacological interventions that target molecular stress-responsive mechanisms. Cellular stresses, such as nutrient deficiency, viral infection, or unfolded proteins, trigger the integrated stress response (ISR), which curtails protein synthesis by phosphorylating eIF2α. In T1D, maladaptive unfolded protein response (UPR) in insulin-producing β cells renders these cells susceptible to autoimmunity. We show that inhibition of the eIF2α kinase PERK, a common component of the UPR and ISR, reverses the mRNA translation block in stressed human islets and delays the onset of diabetes, reduces islet inflammation, and preserves β cell mass in T1D-susceptible mice. Single-cell RNA sequencing of islets from PERK-inhibited mice shows reductions in the UPR and PERK signaling pathways and alterations in antigen processing and presentation pathways in β cells. Spatial proteomics of islets from these mice shows an increase in the immune checkpoint protein PD-L1 in β cells. Golgi membrane protein 1, whose levels increase following PERK inhibition in human islets and EndoC-βH1 human β cells, interacts with and stabilizes PD-L1. Collectively, our studies show that PERK activity enhances β cell immunogenicity, and inhibition of PERK may offer a strategy to prevent or delay the development of T1D.

Crosstalk between protein misfolding and endoplasmic reticulum stress during ageing and their role in age-related disorders

Maintaining the proteome is crucial to retaining cell functionality and response to multiple intrinsic and extrinsic stressors. Protein misfolding increased the endoplasmic reticulum (ER) stress and activated the adaptive unfolded protein response (UPR) to restore cell homeostasis. Apoptosis occurs when ER stress is prolonged or the adaptive response fails. In healthy young cells, the ratio of protein folding machinery to quantities of misfolded proteins is balanced under normal circumstances. However, the age-related deterioration of the complex systems for handling protein misfolding is accompanied by ageing-related disruption of protein homeostasis, which results in the build-up of misfolded and aggregated proteins. This ultimately results in decreased cell viability and forms the basis of common age-related diseases called protein misfolding diseases. Proteins or protein fragments convert from their ordinarily soluble forms to insoluble fibrils or plaques in many of these disorders, which build up in various organs such as the liver, brain, or spleen. Alzheimer's, Parkinson's, type II diabetes, and cancer are diseases in this group commonly manifest in later life. Thus, protein misfolding and its prevention by chaperones and different degradation paths are becoming understood from molecular perspectives. Proteodynamics information will likely affect future interventional techniques to combat cellular stress and support healthy ageing by avoiding and treating protein conformational disorders. This review provides an overview of the diverse proteostasis machinery, protein misfolding, and ER stress involvement, which activates the UPR sensors. Here, we will discuss the crosstalk between protein misfolding and ER stress and their role in developing age-related diseases.

Autologous intraarterial pancreatic bone-marrow mononuclear cells infusion in T2D patients: Changes on beta-cells function, insulin resistance, and inflammatory marker

BACKGROUND

Type 2 diabetes (T2D) is a progressive disease. Many drugs currently being used for the management of T2D have minimal effect on pancreatic beta cells regeneration. Cell-based therapies might provide potential benefits in this aspect.

METHODS

A pilot study in five T2D patients with 12 months follow-up was performed to evaluate the effect of autologous bone marrow mononuclear stem cells (BM-MNCs) infusion into pancreatic arteries on the insulin requirement, beta-cell function, insulin resistance, and systemic inflammatory marker (CRP).

RESULTS

The primary endpoint, a 50 % reduction of total insulin doses from baseline, was not achieved in this study. However, a trend of increasing fasting C-peptide (p = 0.07) and C-peptide 60' (p = 0.07) and 90' (p = 0.07) after a mixed-meal tolerance test was observed 12 months post-infusion compared to baseline levels. A similar result was observed for the homeostatic model assessment of beta cell function (HOMA1-B), an index for beta cell function. No improvement was observed for insulin resistance measured by homeostasis model assessment of insulin resistance (HOMA1-IR) and systemic inflammatory parameter.

CONCLUSION

Intraarterial pancreatic autologous BM-MNCs infusion might potentially improve beta cell function in T2D patients, although further study is needed to confirm this finding.

Multiple nanotechnological approaches using natural compounds for diabetes management

Objectives

Diabetes mellitus (DM) is a long-standing and non-transmissible endocrine disease that generates significant clinical issues and currently affects approximately 400 million people worldwide. The aim of the present review was to analyze the most relevant and recent studies that focused on the potential application of plant extracts and phytocompounds in nanotechnology for the treatment of T2DM.

Methods

Various databases were examined, including Springer Link, Google Scholar, PubMed, Wiley Online Library, and Science Direct. The search focused on discovering the potential application of nanoparticulate technologies in enhancing drug delivery of phytocompounds for the mentioned condition.

Results

Several drug delivery systems have been considered, that aimed to reduce adverse effects, while enhancing the efficiency of oral antidiabetic medications. Plant-based nanoformulations have been highlighted as an innovative approach for DM treatment due to their eco-friendly and cost-effective synthesis methods. Their benefits include targeted action, enhanced availability, stability, and reduced dosage frequency.

Conclusions

Nanomedicine has opened new opportunities for the diagnosis, treatment, and prevention of DM. The use of nanomaterials has demonstrated improved outcomes for both T1DM and T2DM. Notably, flavonoids, including substances such as quercetin, naringenin and myricitrin, have been recognized for their enhanced efficacy when delivered through novel nanotechnologies in preventing T2DM onset and associated complications. The perspectives on the addressed subject point to the development of more nanostructured phytocompounds with improved bioavailability and therapeutic efficacy.

Silencing of forkhead box protein O-1 (FOXO-1) enhances insulin-producing cell generation from adipose mesenchymal stem cells for diabetes therapy

AIMS

Generation of mature β-cells from MSCs has been a challenge in the field of stem cell therapy of diabetes. Adipose tissue-derived mesenchymal stem cells (Ad-MSCs) have made their mark in regenerative medicine, and provide several advantages compared to other MSCs sources. Forkhead box protein O-1 (FOXO-1) is an important transcription factor for normal development of β-cells, yet its over expression in β-cells may cause glucose intolerance. In this study, we isolated, characterized Ad-MSCs from rat epididymal fat pads, differentiated these MSCs into insulin producing cells (IPCs) and studied the role of FOXO-1 in such differentiation.

MATERIALS AND METHODS

We examined the expression of FOXO-1 and its nuclear cytoplasmic localization in the generated IPCs. Afterwards we knocked down FOXO-1 using siRNA targeting FOXO-1 (siFOXO-1). The differentiated siFOXO-1 IPCs were compared to non-targeting siRNA (siNT) IPCs regarding expression of β-cell markers by qRT-PCR and western blotting, dithizone (DTZ) staining and glucose stimulated insulin secretion (GSIS).

KEY FINDINGS

Isolated Ad-MSCs exhibited all characteristics of MSCs and can generate IPCs. FOXO-1 was initially elevated during differentiation followed by a decline towards end of differentiation. FOXO-1 was dephosphorylated and localized to the nucleus upon differentiation into IPCs. Knock down of FOXO-1 improved the expression of β-cell markers in final differentiated IPCs, improved DTZ uptake and showed increased insulin secretion upon challenging with increased glucose concentration.

SIGNIFICANCE

These results portray FOXO-1 as a hindering factor of generation of IPCs whose down-regulation can generate more mature IPCs for MSCs therapy of diabetes mellitus.

New opportunities and perspectives on biosynthesis and bioactivities of secondary metabolites from Aloe vera

Historically, the genus Aloe has been an indispensable part of both traditional and modern medicine. Decades of intensive research have unveiled the major bioactive secondary metabolites of this plant. Recent pandemic outbreaks have revitalized curiosity in aloe metabolites, as they have proven pharmacokinetic profiles and repurposable chemical space. However, the structural complexity of these metabolites has hindered scientific advances in the chemical synthesis of these compounds. Multi-omics research interventions have transformed aloe research by providing insights into the biosynthesis of many of these compounds, for example, aloesone, aloenin, noreugenin, aloin, saponins, and carotenoids. Here, we summarize the biological activities of major aloe secondary metabolites with a focus on their mechanism of action. We also highlight the recent advances in decoding the aloe metabolite biosynthetic pathways and enzymatic machinery linked with these pathways. Proof-of-concept studies on in vitro, whole-cell, and microbial synthesis of aloe compounds have also been briefed. Research initiatives on the structural modification of various aloe metabolites to expand their chemical space and activity are detailed. Further, the technological limitations, patent status, and prospects of aloe secondary metabolites in biomedicine have been discussed.

Association between Diet Quality and Risk of Type 2 Diabetes Mellitus in Patients with Coronary Heart Disease: Findings from the CORDIOPREV Study

The incidence of type 2 diabetes mellitus (T2DM) is growing in Western countries. Nutritional interventions that promote high-quality dietary patterns could help reverse this trend. We aimed to evaluate whether changes in Nutrient-Rich Food Index 9.3 (NRF9.3) were related to the risk of developing T2DM in patients with coronary heart disease (CHD). The study was carried out in the context of two healthy dietary interventions (a Mediterranean and a low-fat diet). For this purpose, we evaluated all the patients in the CORDIOPREV study without T2DM at baseline. Data were obtained during the first 5 years of dietary intervention. The score was calculated using the Food Frequency Questionnaires at baseline and after 1 year of intervention. After 5 years of follow-up, 106 patients developed T2DM (incident-T2DM), while 316 subjects did not (non-T2DM). Total NRF9.3 score and changes during the first year of intervention were compared between incident-T2DM and non-T2DM. Incident-T2DM showed less improvement in NRF9.3 than non-T2DM (p = 0.010). In the multi-adjusted Cox proportional hazard study, patients with greater improvement in NRF9.3 had over 50% less risk of developing T2DM compared with the lowest tertile (HR 2.10, 95%, CI = 1.12-3.56). In conclusion, improved diet quality in terms of nutrient density after the dietary intervention was associated with a lower risk of T2DM in patients with CHD.

Vanillin improves glucose homeostasis and modulates metabolic activities linked to type 2 diabetes in fructose-streptozotocin induced diabetic rats

OBJECTIVE

This study investigated the antidiabetic effect of vanillin using in vitro, in silico, and in vivo experimental models.

METHODOLOGY

Type 2 diabetes (T2D) was induced in male Sprague-Dawley (SD) rats using fructose-streptozotocin (STZ), then orally administered low (150 mg/kg bodyweight) or high (300 mg/kg bodyweight) dose of vanillin for 5 weeks intervention period.

RESULTS

Vanillin suppressed the levels of blood glucose, serum cholesterol, triglyceride, low-density lipoprotein cholesterol (LDL-c), alanine transaminase (ALT), aspartate transaminase (AST), creatinine, urea, uric acid, when elevated serum insulin, HDL-cholesterol, and concomitantly improved pancreatic β-cell function, glucose tolerance, and pancreatic morphology. It also elevated both serum and pancreatic tissue GSH level, SOD and catalase activities, and hepatic glycogen level, while depleting malondialdehyde level, α-amylase, lipase, acetylcholinesterase, ATPase, ENTPDase and 5'-nucleotidase, glucose-6-phosphatase, fructose-1,6-bisphosphatase, and glycogen phosphorylase activities.

CONCLUSIONS

The results indicate the potent antidiabetic effect of vanillin against T2D and its associated complications.

Comparing the effects of developmental exposure to alpha lipoic acid (ALA) and perfluorooctanesulfonic acid (PFOS) in zebrafish (Danio rerio)

Alpha lipoic acid (ALA) is a dietary supplement that has been used to treat a wide range of diseases, including obesity and diabetes, and have lipid-lowering effects, making it a potential candidate for mitigating dyslipidemia resulting from exposures to the per- and polyfluoroalkyl substance (PFAS) family member perfluorooctanesulfonic acid (PFOS). ALA can be considered a non-fluorinated structural analog to PFOS due to their similar 8-carbon chain and amphipathic structure, but, unlike PFOS, is rapidly metabolized. PFOS has been shown to reduce pancreatic islet area and induce β-cell lipotoxicity, indicating that changes in β-cell lipid microenvironment is a mechanism contributing to hypomorphic islets. Due to structural similarities, we hypothesized that ALA may compete with PFOS for binding to proteins and distribution throughout the body to mitigate the effects of PFOS exposure. However, ALA alone reduced islet area and fish length, with several morphological endpoints indicating additive toxicity in the co-exposures. Individually, ALA and PFOS increased fatty acid uptake from the yolk. ALA alone increased liver lipid accumulation, altered fatty acid profiling and modulated PPARɣ pathway signaling. Together, this work demonstrates that ALA and PFOS have similar effects on lipid uptake and metabolism during embryonic development in zebrafish.

Advances in extracellular vesicles as mediators of cell-to-cell communication in pregnancy

Cell-to-cell communication mediated by Extracellular Vesicles (EVs) is a novel and emerging area of research, especially during pregnancy, in which placenta derived EVs can facilitate the feto-maternal communication. EVs comprise a heterogeneous group of vesicle sub-populations with diverse physical and biochemical characteristics and originate by specific biogenesis mechanisms. EVs transfer molecular cargo (including proteins, nucleic acids, and lipids) between cells and are critical mediators of cell communication. There is growing interest among researchers to explore into the molecular cargo of EVs and their functions in a physiological and pathological context. For example, inflammatory mediators such as cytokines are shown to be released in EVs and EVs derived from immune cells play key roles in mediating the immune response as well as immunoregulatory pathways. Pregnancy complications such as gestational diabetes mellitus, preeclampsia, intrauterine growth restriction and preterm birth are associated with altered levels of circulating EVs, with differential EV cargo and bioactivity in target cells. This implicates the intriguing roles of EVs in reprogramming the maternal physiology during pregnancy. Moreover, the capacity of EVs to carry bioactive molecules makes them a promising tool for biomarker development and targeted therapies in pregnancy complications. This review summarizes the physiological and pathological roles played by EVs in pregnancy and pregnancy-related disorders and describes the potential of EVs to be translated into clinical applications in the diagnosis and treatment of pregnancy complications.

Animal models for type 1 and type 2 diabetes: advantages and limitations

Diabetes mellitus, commonly referred to as diabetes, is a group of metabolic disorders characterized by chronic elevation in blood glucose levels, resulting from inadequate insulin production, defective cellular response to extracellular insulin, and/or impaired glucose metabolism. The two main types that account for most diabetics are type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM), each with their own pathophysiological features. T1D is an autoimmune condition where the body's immune system attacks and destroys the insulin-producing beta cells in the pancreas. This leads to lack of insulin, a vital hormone for regulating blood sugar levels and cellular glucose uptake. As a result, those with T1D depend on lifelong insulin therapy to control their blood glucose level. In contrast, T2DM is characterized by insulin resistance, where the body's cells do not respond effectively to insulin, coupled with a relative insulin deficiency. This form of diabetes is often associated with obesity, sedentary lifestyle, and/or genetic factors, and it is managed with lifestyle changes and oral medications. Animal models play a crucial role in diabetes research. However, given the distinct differences between T1DM and T2DM, it is imperative for researchers to employ specific animal models tailored to each condition for a better understanding of the impaired mechanisms underlying each condition, and for assessing the efficacy of new therapeutics. In this review, we discuss the distinct animal models used in type 1 and type 2 diabetes mellitus research and discuss their strengths and limitations.

Development of an ostrich-derived single-chain variable fragment (scFv) against PTPRN extracellular domain

In type 1 diabetes, the immune system destroys pancreatic beta cells in an autoimmune condition. To overcome this disease, a specific monoclonal antibody that binds to pancreatic beta cells could be used for targeted immunotherapy. Protein tyrosine phosphatase receptor N (PTPRN) is one of the important surface antigen candidates. Due to its high sequence homology among mammals, so far, no single-chain monoclonal antibody has been produced against this receptor. In this study, we developed a novel single-chain variable fragment (scFv) against the PTPRN extracellular domain. To this aim, ostrich species was used as a host is far phylogenetically birds from mammals to construct a phage display library for the first time. An ostrich-derived scfv phage display library was prepared and biopanning steps were done to enrich and screen for isolating the best anti-PTPRN binders. An scFv with appropriate affinity and specificity to the PTPRN extracellular domain was selected and characterized by ELISA, western blotting, and flow cytometry. The anti-PTPRN scFv developed in this study could be introduced as an effective tool that can pave the way for the creation of antibody-based targeting systems in cooperation with the detection and therapy of type I diabetes.

Extracellular vesicles as tools and targets in therapy for diseases

Extracellular vesicles (EVs) are nano-sized, membranous structures secreted into the extracellular space. They exhibit diverse sizes, contents, and surface markers and are ubiquitously released from cells under normal and pathological conditions. Human serum is a rich source of these EVs, though their isolation from serum proteins and non-EV lipid particles poses challenges. These vesicles transport various cellular components such as proteins, mRNAs, miRNAs, DNA, and lipids across distances, influencing numerous physiological and pathological events, including those within the tumor microenvironment (TME). Their pivotal roles in cellular communication make EVs promising candidates for therapeutic agents, drug delivery systems, and disease biomarkers. Especially in cancer diagnostics, EV detection can pave the way for early identification and offers potential as diagnostic biomarkers. Moreover, various EV subtypes are emerging as targeted drug delivery tools, highlighting their potential clinical significance. The need for non-invasive biomarkers to monitor biological processes for diagnostic and therapeutic purposes remains unfulfilled. Tapping into the unique composition of EVs could unlock advanced diagnostic and therapeutic avenues in the future. In this review, we discuss in detail the roles of EVs across various conditions, including cancers (encompassing head and neck, lung, gastric, breast, and hepatocellular carcinoma), neurodegenerative disorders, diabetes, viral infections, autoimmune and renal diseases, emphasizing the potential advancements in molecular diagnostics and drug delivery.

Role of cytosolic and endoplasmic reticulum Ca2+ in pancreatic beta-cells: pros and cons

Pancreatic beta cells utilize Ca2+ to secrete insulin in response to glucose. The glucose-dependent increase in cytosolic Ca2+ concentration ([Ca2+]C) activates a series of insulin secretory machinery in pancreatic beta cells. Therefore, the amount of insulin secreted in response to glucose is determined in a [Ca2+]C-dependent manner, at least within a moderate range. However, the demand for insulin secretion may surpass the capability of beta cells. Abnormal elevation of [Ca2+]C levels beyond the beta-cell endurance capacity can damage them by inducing endoplasmic reticulum (ER) stress and cell death programs such as apoptosis. Therefore, while Ca2+ is essential for the insulin secretory functions of beta cells, it could affect their survival at pathologically higher levels. Because an increase in beta-cell [Ca2+]C is inevitable under certain hazardous conditions, understanding the regulatory mechanism for [Ca2+]C is important. Therefore, this review discusses beta-cell function, survival, ER stress, and apoptosis associated with intracellular and ER Ca2+ homeostasis.

Rational Engineering of Islet Tolerance via Biomaterial-Mediated Immune Modulation

Type 1 diabetes (T1D) onset is characterized by an autoimmune attack on β islet cells within the pancreas, preventing the insulin secretion required to maintain glucose homeostasis. Targeted modulation of key immunoregulatory cell populations is a promising strategy to restore tolerance to β cells. This strategy can be used to prevent T1D onset or reverse T1D with transplanted islets. To this end, drug delivery systems can be employed to transport immunomodulatory cargo to specific cell populations that inhibit autoreactive T cell-mediated destruction of the β cell mass. The rational engineering of biomaterials into nanoscale and microscale drug carriers can facilitate targeted interactions with immune cells. The physicochemical properties of the biomaterial, the delivered immunomodulatory agent, and the target cell populations are critical variables in the design of these delivery systems. In this review, we discuss recent biomaterials-based drug delivery approaches to induce islet tolerance and the need to consider both immune and metabolic markers of disease progression.

A role and mechanism for redox sensing by SENP1 in β-cell responses to high fat feeding

Pancreatic β-cells respond to metabolic stress by upregulating insulin secretion, however the underlying mechanisms remain unclear. Here we show, in β-cells from overweight humans without diabetes and mice fed a high-fat diet for 2 days, insulin exocytosis and secretion are enhanced without increased Ca2+ influx. RNA-seq of sorted β-cells suggests altered metabolic pathways early following high fat diet, where we find increased basal oxygen consumption and proton leak, but a more reduced cytosolic redox state. Increased β-cell exocytosis after 2-day high fat diet is dependent on this reduced intracellular redox state and requires the sentrin-specific SUMO-protease-1. Mice with either pancreas- or β-cell-specific deletion of this fail to up-regulate exocytosis and become rapidly glucose intolerant after 2-day high fat diet. Mechanistically, redox-sensing by the SUMO-protease requires a thiol group at C535 which together with Zn+-binding suppresses basal protease activity and unrestrained β-cell exocytosis, and increases enzyme sensitivity to regulation by redox signals.

The Role of Selenium Nanoparticles in Addressing Diabetic Complications: A Comprehensive Study

Diabetes, as an emerging epidemic, has put forward a significant spotlight on the evolving population worldwide grounded upon the remarkable affliction of healthcare along with economical conflict. Various studies suggested that, in modern society, lack of maintenance of a healthy life style leads to the occurrence of diabetes as insulin resistant, later having a damaging effect on the pancreatic β-cells, suggesting various complications. Furthermore, diabetes management is controversial owing to different opinions based on the prevention of complications. For this purpose, nanostructured materials (NSM) like selenium nanoparticles (SeNPs) have proved their efficiency in the therapeutic management of such serious diseases. This review offers an in- -depth idea regarding the pathophysiology, diagnosis and various conventional therapeutics of type 1 and type 2 diabetes, shedding light on Diabetic Nephropathy (DN), a case study of type 1 diabetes. Moreover, this review provides an exhaustive study by highlighting the economic and healthcare burdens associated with diabetes along with the controversies associated with conventional therapeutic management and the promising role of NSM like selenium nanoparticles (SeNPs), as a novel weapon for encountering such fatal diseases.

Less common forms of diabetes in young population

Types diabetes other than type 1 are generally considered rare in children and adolescents. The incidence of type 2 diabetes has increased dramatically over the past decade in some ethnic groups. The increased incidence of this type of diabetes mellitus has corresponded tem-porally to unprecedented increases in body weight and obesity prevalence in adolescents in various ethnic populations. Early treatment of insulin resistance is important to prevent the development of diabetes. In therapy, lifestyle modification is essential for weight loss, and if this is not enough, pharmacotherapy is required. Maturity-onset diabetes of the young (MODY), another type of insulin-dependent diabetes, is characterised by early onset and autosomal dominant inheritance. MODY is mainly caused by β-cell defects, resulting in insufficient insulin secretion for a given blood glucose level. Unlike non-insulin-dependent diabetes in youth (NIDDM-Y), there is no significant increase in insulin resistance. The purpose of this article is to characterise and present types of diabetes other than type 1 found in the young population.

Inter-organ communication involved in metabolic regulation at the whole-body level

Metabolism in each organ of multi-organ organisms, including humans, is regulated in a coordinated manner to dynamically maintain whole-body homeostasis. Metabolic information exchange among organs/tissues, i.e., inter-organ communication, which is necessary for this purpose, has been a subject of ongoing research. In particular, it has become clear that metabolism of energy, glucose, lipids, and amino acids is dynamically regulated at the whole-body level mediated by the nervous system, including afferent, central, and efferent nerves. These findings imply that the central nervous system obtains metabolic information from peripheral organs at all times and sends signals selectively to peripheral organs/tissues to maintain metabolic homeostasis, and that the liver plays an important role in sensing and transmitting information on the metabolic status of the body. Furthermore, the utilization of these endogenous mechanisms is expected to lead to the development of novel preventive/curative therapies for metabolic diseases such as diabetes and obesity.(This is a summarized version of the subject matter presented at Symposium 7 presented at the 43rd Annual Meeting of the Japanese Society of Inflammation and Regeneration.).

Obesity under the moonlight of c-MYC

The moonlighting protein c-Myc is a master regulator of multiple biological processes including cell proliferation, differentiation, angiogenesis, apoptosis and metabolism. It is constitutively and aberrantly expressed in more than 70% of human cancers. Overwhelming evidence suggests that c-Myc dysregulation is involved in several inflammatory, autoimmune, metabolic and other non-cancerous diseases. In this review, we addressed the role of c-Myc in obesity. Obesity is a systemic disease, accompanied by multi-organ dysfunction apart from white adipose tissue (WAT), such as the liver, the pancreas, and the intestine. c-Myc plays a big diversity of functions regulating cellular proliferation, the maturation of progenitor cells, fatty acids (FAs) metabolism, and extracellular matrix (ECM) remodeling. Moreover, c-Myc drives the expression of a wide range of metabolic genes, modulates the inflammatory response, induces insulin resistance (IR), and contributes to the regulation of intestinal dysbiosis. Altogether, c-Myc is an interesting diagnostic tool and/or therapeutic target in order to mitigate obesity and its consequences.

Pancreatic Beta-cell Dysfunction in Type 2 Diabetes

Pancreatic β-cells produce and secrete insulin to maintain blood glucose levels within a narrow range. Defects in the function and mass of β-cells play a significant role in the development and progression of diabetes. Increased β-cell deficiency and β-cell apoptosis are observed in the pancreatic islets of patients with type 2 diabetes. At an early stage, β-cells adapt to insulin resistance, and their insulin secretion increases, but they eventually become exhausted, and the β-cell mass decreases. Various causal factors, such as high glucose, free fatty acids, inflammatory cytokines, and islet amyloid polypeptides, contribute to the impairment of β-cell function. Therefore, the maintenance of β-cell function is a logical approach for the treatment and prevention of diabetes. In this review, we provide an overview of the role of these risk factors in pancreatic β-cell loss and the associated mechanisms. A better understanding of the molecular mechanisms underlying pancreatic β-cell loss will provide an opportunity to identify novel therapeutic targets for type 2 diabetes.

Human Pseudoislet System for Synchronous Assessment of Fluorescent Biosensor Dynamics and Hormone Secretory Profiles

The pancreatic islets of Langerhans, which are small 3D collections of specialized endocrine and supporting cells interspersed throughout the pancreas, have a central role in the control of glucose homeostasis through the secretion of insulin by beta cells, which lowers blood glucose, and glucagon by alpha cells, which raises blood glucose. Intracellular signaling pathways, including those mediated by cAMP, are key for regulated alpha and beta cell hormone secretion. The 3D islet structure, while essential for coordinated islet function, presents experimental challenges for mechanistic studies of the intracellular signaling pathways in primary human islet cells. To overcome these challenges and limitations, this protocol describes an integrated live-cell imaging and microfluidic platform using primary human pseudoislets generated from donors without diabetes that resemble native islets in their morphology, composition, and function. These pseudoislets are size-controlled through the dispersion and reaggregation process of primary human islet cells. In the dispersed state, islet cell gene expression can be manipulated; for example, biosensors such as the genetically encoded cAMP biosensor, cADDis, can be introduced. Once formed, pseudoislets expressing a genetically encoded biosensor, in combination with confocal microscopy and a microperifusion platform, allow for the synchronous assessment of fluorescent biosensor dynamics and alpha and beta cell hormone secretory profiles to provide more insight into cellular processes and function.

The association between type 1 diabetes and exercise/physical activity and prolongation of the honeymoon phase in patients

In type 1 diabetes (T1D), pancreatic beta cells are destroyed by the immune system, causing chronic hyperglycemia and micro and macrovascular complications. However, some people experience a 'honeymoon' phase (or partial remission) after being diagnosed with type 1 diabetes. During this phase, a substantial amount of insulin is still produced by the pancreas, helping to reduce blood sugar levels and the requirement for external insulin. The clinical significance of this phase lies in the potential for pharmacological and non-pharmacological interventions during this time frame to either slow down or arrest beta-cell destruction. Clearly, we need to continue researching novel therapies like immunomodulatory agents, but we also need to look at potentially effective therapies with acceptable side effects that can serve as a complement to the medicines currently being studied. Physical activity and exercise, regardless of its type, is one of the factors its impact on the control of diabetes is being investigated and promising results have been achieved. Although there are still limited reports in this regard, there is some evidence to suggest that regular physical exercise could prolong the honeymoon period in both adults and children. In this review, having described the immune base of type 1 diabetes, we outline the benefits of exercise on the general health of individuals with T1D. Moreover, we centered on the honeymoon and current evidence suggesting the effects of physical activity and exercise on this phase duration.

Human Beta Cell Functional Adaptation and Dysfunction in Insulin Resistance and Its Reversibility

BACKGROUND

Beta cells play a key role in the pathophysiology of diabetes since their functional adaptation is able to maintain euglycemia in the face of insulin resistance, and beta cell decompensation or dysfunction is a necessary condition for full-blown type 2 diabetes (T2D). The mechanisms behind compensation and decompensation are incompletely understood, especially for human beta cells, and even less is known about influences of chronic kidney disease (CKD) or immunosupressive therapy after transplantation on these processes and the development of posttransplant diabetes.

SUMMARY

During compensation, beta cell sensitivity to glucose becomes left-shifted, i.e., their sensitivity to stimulation increases, and this is accompanied by enhanced signals along the stimulus-secretion coupling cascade from membrane depolarization to intracellular calcium and the most distal insulin secretion dynamics. There is currently no clear evidence regarding changes in intercellular coupling during this stage of disease progression. During decompensation, intracellular stimulus-secretion coupling remains enhanced to some extent at low or basal glucose concentrations but seems to become unable to generate effective signals to stimulate insulin secretion at high or otherwise stimulatory glucose concentrations. Additionally, intercellular coupling becomes disrupted, lowering the number of cells that contribute to secretion. During progression of CKD, beta cells also seem to drift from a compensatory left-shift to failure, and immunosupressants can further impair beta cell function following kidney transplantation.

KEY MESSAGES

Beta cell stimulus-secretion coupling is enhanced in compensated insulin resistance. With worsening insulin resistance, both intra- and intercellular coupling become disrupted. CKD can progressively disrupt beta cell function, but further studies are needed, especially regarding changes in intercellular coupling.

Preventive Effect of Molecular Iodine in Pancreatic Disorders from Hypothyroid Rabbits

Pancreatic alterations such as inflammation and insulin resistance accompany hypothyroidism. Molecular iodine (I2) exerts antioxidant and differentiation actions in several tissues, and the pancreas is an iodine-uptake tissue. We analyzed the effect of two oral I2 doses on pancreatic disorders in a model of hypothyroidism for 30 days. Adult female rabbits were divided into the following groups: control, moderate oral dose of I2 (0.2 mg/kg, M-I2), high oral dose of I2 (2.0 mg/kg, H-I2), oral dose of methimazole (MMI; 10 mg/kg), MMI + M-I2,, and MMI + H-I2. Moderate or high I2 supplementation did not modify circulating metabolites or pancreatic morphology. The MMI group showed reductions of circulating thyroxine (T4) and triiodothyronine (T3), moderate glucose increments, and significant increases in cholesterol and low-density lipoproteins. Acinar fibrosis, high insulin content, lipoperoxidation, and overexpression of GLUT4 were observed in the pancreas of this group. M-I2 supplementation normalized the T4 and cholesterol, but T3 remained low. Pancreatic alterations were prevented, and nuclear factor erythroid-2-related factor-2 (Nrf2), antioxidant enzymes, and peroxisome proliferator-activated receptor gamma (PPARG) maintained their basal values. In MMI + H-I2, hypothyroidism was avoided, but pancreatic alterations and low PPARG expression remained. In conclusion, M-I2 supplementation reestablishes thyronine synthesis and diminishes pancreatic alterations, possibly related to Nrf2 and PPARG activation.

Insulin Preferentially Regulates the Activity of Parasympathetic Preganglionic Neurons over Sympathetic Preganglionic Neurons

BACKGRUOUND

Insulin is a peptide hormone that regulates post-prandial physiology, and it is well known that insulin controls homeostasis at least in part via the central nervous system. In particular, insulin alters the activity of neurons within the autonomic nervous system. However, currently available data are mostly from unidentified brainstem neurons of the dorsal motor nucleus of the vagus nerve (DMV).

METHODS

In this study, we used several genetically engineered mouse models to label distinct populations of neurons within the brainstem and the spinal cord for whole-cell patch clamp recordings and to assess several in vivo metabolic functions.

RESULTS

We first confirmed that insulin directly inhibited cholinergic (parasympathetic preganglionic) neurons in the DMV. We also found inhibitory effects of insulin on both the excitatory and inhibitory postsynaptic currents recorded in DMV cholinergic neurons. In addition, GABAergic neurons of the DMV and nucleus tractus solitarius were inhibited by insulin. However, insulin had no effects on the cholinergic sympathetic preganglionic neurons of the spinal cord. Finally, we obtained results suggesting that the insulininduced inhibition of parasympathetic preganglionic neurons may not play a critical role in the regulation of glucose homeostasis and gastrointestinal motility.

CONCLUSION

Our results demonstrate that insulin inhibits parasympathetic neuronal circuitry in the brainstem, while not affecting sympathetic neuronal activity in the spinal cord.

The Interplay of Adipokines and Pancreatic Beta Cells in Metabolic Regulation and Diabetes

The interplay between adipokines and pancreatic beta cells, often referred to as the adipo-insular axis, plays a crucial role in regulating metabolic homeostasis. Adipokines are signaling molecules secreted by adipocytes that have profound effects on several physiological processes. Adipokines such as adiponectin, leptin, resistin, and visfatin influence the function of pancreatic beta cells. The reciprocal communication between adipocytes and beta cells is remarkable. Insulin secreted by beta cells affects adipose tissue metabolism, influencing lipid storage and lipolysis. Conversely, adipokines released from adipocytes can influence beta cell function and survival. Chronic obesity and insulin resistance can lead to the release of excess fatty acids and inflammatory molecules from the adipose tissue, contributing to beta cell dysfunction and apoptosis, which are key factors in developing type 2 diabetes. Understanding the complex interplay of the adipo-insular axis provides insights into the mechanisms underlying metabolic regulation and pathogenesis of metabolic disorders. By elucidating the molecular mediators involved in this interaction, new therapeutic targets and strategies may emerge to reduce the risk and progression of diseases, such as type 2 diabetes and its associated complications. This review summarizes the interactions between adipokines and pancreatic beta cells, and their roles in the pathogenesis of diabetes and metabolic diseases.

Exosome-based drug delivery systems for the treatment of diabetes and its complications: current opinion

Diabetes medication is based on controlling blood glucose and delaying the onset of related complications and is not a complete cure for diabetes. Conventional drug therapy fails to stop progressive islet β cell failure in diabetic patients. Recent studies have shown that "exosome-based therapy" holds great promise in treating diabetes and its complications. Exosomes are small vesicles that are stable in the bloodstream and can effectively deliver therapeutic drugs to specific tissues or organs through intercellular communication. Using exosomes as carriers for drug delivery offers several advantages. This review summarizes the benefits of exosomal drug delivery systems, drug loading methods, and their applications in treating diabetes and its complications. However, there are still challenges to overcome in using exosomal drug delivery systems, such as large-scale production, assessing the contents of exosomes, and monitoring the safety and effectiveness of the treatment in vivo. In conclusion, this review proposes the therapeutical potential of exosomes as drug carriers for developing novel drugs to provide new strategies for treating diabetes and its complications.

Saliva insulin tracks plasma insulin across the day following high-carbohydrate and low-carbohydrate meals

Non-invasive monitoring of insulin could hold promise to identify those with, or at risk for developing, insulin resistance. We aimed to examine saliva insulin responses across the day following high- and low-carbohydrate meals and evaluate whether changes in saliva insulin might accurately reflect changes in plasma insulin. In two randomized crossover studies, young normal weight men (NW; n = 8; Study 1) and adults with overweight/obesity (OO; n = 8; Study 2) completed two 9-h experimental trials in which the participants consumed isocaloric mixed high-carbohydrate (HC) or low-carbohydrate (LC) meals at 0, 3, and 6 h. Plasma and saliva samples were collected at fasted baseline and every 30 min for a total of 19 samples across 9 h. Overall, findings revealed a similar trend for postprandial saliva and plasma insulin responses regardless of the time of the day with a ∼30-45 min lag between saliva and plasma insulin responses. In both NW and OO groups, saliva and plasma insulin area under the curve (AUC) and incremental AUC were significantly higher in HC condition as compared to LC condition (all P ≤ 0.002). Nine-hour plasma and saliva insulin total AUCs were strongly and very strongly correlated in both HC (r = 0.68; P = 0.007) and LC (r = 0.84, P < 0.001) conditions, respectively. Saliva insulin is proportionate to and appears to reasonably track plasma insulin across the day with a ∼30-45 min delay. Saliva insulin shows promise as a non-invasive method to discern between low and high plasma insulin and may have utility in predicting the degree of insulin resistance (NCT03374436).

Islet cells in human type 1 diabetes: from recent advances to novel therapies - a symposium-based roadmap for future research

There is a growing understanding that the early phases of type 1 diabetes (T1D) are characterised by a deleterious dialogue between the pancreatic beta cells and the immune system. This, combined with the urgent need to better translate this growing knowledge into novel therapies, provided the background for the JDRF-DiabetesUK-INNODIA-nPOD symposium entitled 'Islet cells in human T1D: from recent advances to novel therapies', which took place in Stockholm, Sweden, in September 2022. We provide in this article an overview of the main themes addressed in the symposium, pointing to both promising conclusions and key unmet needs that remain to be addressed in order to achieve better approaches to prevent or reverse T1D.

Sex Differences in Pancreatic β-Cell Physiology and Glucose Homeostasis in C57BL/6J Mice

The importance of sexual dimorphism has been highlighted in recent years since the National Institutes of Health's mandate on considering sex as a biological variable. Although recent studies have taken strides to study both sexes side by side, investigations into the normal physiological differences between males and females are limited. In this study, we aimed to characterized sex-dependent differences in glucose metabolism and pancreatic β-cell physiology in normal conditions using C57BL/6J mice, the most common mouse strain used in metabolic studies. Here, we report that female mice have improved glucose and insulin tolerance associated with lower nonfasted blood glucose and insulin levels compared with male mice at 3 and 6 months of age. Both male and female animals show β-cell mass expansion from embryonic day 17.5 to adulthood, and no sex differences were observed at embryonic day 17.5, newborn, 1 month, or 3 months of age. However, 6-month-old males displayed increased β-cell mass in response to insulin resistance compared with littermate females. Molecularly, we uncovered sexual dimorphic alterations in the protein levels of nutrient sensing proteins O-GlcNAc transferase and mTOR, as well as differences in glucose-stimulus coupling mechanisms that may underlie the differences in sexually dimorphic β-cell physiology observed in C57BL/6J mice.