Adjudin improves beta cell maturation, hepatic glucose uptake and glucose homeostasis.

AIMS/HYPOTHESIS: Recovering functional beta cell mass is a promising approach for future diabetes therapies. The aim of the present study is to investigate the effects of adjudin, a small molecule identified in a beta cell screen using zebrafish, on pancreatic beta cells and diabetes conditions in mice and human spheroids. METHODS: In zebrafish, insulin expression was examined by bioluminescence and quantitative real-time PCR (qPCR), glucose levels were examined by direct measurements and distribution using a fluorescent glucose analogue, and calcium activity in beta cells was analysed by in vivo live imaging. Pancreatic islets of wild-type postnatal day 0 (P0) and 3-month-old (adult) mice, as well as adult db/db mice (i.e. BKS(D)-Leprdb/JOrlRj), were cultured in vitro and analysed by qPCR, glucose stimulated insulin secretion and whole mount staining. RNA-seq was performed for islets of P0 and db/db mice. For in vivo assessment, db/db mice were treated with adjudin and subjected to analysis of metabolic variables and islet cells. Glucose consumption was examined in primary human hepatocyte spheroids. RESULTS: Adjudin treatment increased insulin expression and calcium response to glucose in beta cells and decreased glucose levels after beta cell ablation in zebrafish. Adjudin led to improved beta cell function, decreased beta cell proliferation and glucose responsive insulin secretion by decreasing basal insulin secretion in in vitro cultured newborn mouse islets. RNA-seq of P0 islets indicated that adjudin treatment resulted in increased glucose metabolism and mitochondrial function, as well as downstream signalling pathways involved in insulin secretion. In islets from db/db mice cultured in vitro, adjudin treatment strengthened beta cell identity and insulin secretion. RNA-seq of db/db islets indicated adjudin-upregulated genes associated with insulin secretion, membrane ion channel activity and exocytosis. Moreover, adjudin promoted glucose uptake in the liver of zebrafish in an insulin-independent manner, and similarly promoted glucose consumption in primary human hepatocyte spheroids with insulin resistance. In vivo studies using db/db mice revealed reduced nonfasting blood glucose, improved glucose tolerance and strengthened beta cell identity after adjudin treatment. CONCLUSIONS/INTERPRETATION: Adjudin promoted functional maturation of immature islets, improved function of dysfunctional islets, stimulated glucose uptake in liver and improved glucose homeostasis in db/db mice. Thus, the multifunctional drug adjudin, previously studied in various contexts and conditions, also shows promise in the management of diabetic states. DATA AVAILABILITY: Raw and processed RNA-seq data for this study have been deposited in the Gene Expression Omnibus under accession number GSE235398 ( https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE235398 ).

Characterization of the Secretome, Transcriptome, and Proteome of Human ß Cell Line EndoC-ßH1.

Early diabetes research is hampered by limited availability, variable quality, and instability of human pancreatic islets in culture. Little is known about the human ß cell secretome, and recent studies question translatability of rodent ß cell secretory profiles. Here, we verify representativeness of EndoC-ßH1, one of the most widely used human ß cell lines, as a translational human ß cell model based on omics and characterize the EndoC-ßH1 secretome. We profiled EndoC-ßH1 cells using RNA-seq, data-independent acquisition, and tandem mass tag proteomics of cell lysate. Omics profiles of EndoC-ßH1 cells were compared to human ß cells and insulinomas. Secretome composition was assessed by data-independent acquisition proteomics. Agreement between EndoC-ßH1 cells and primary adult human ß cells was ∼90% for global omics profiles as well as for ß cell markers, transcription factors, and enzymes. Discrepancies in expression were due to elevated proliferation rate of EndoC-ßH1 cells compared to adult ß cells. Consistently, similarity was slightly higher with benign nonmetastatic insulinomas. EndoC-ßH1 secreted 783 proteins in untreated baseline state and 3135 proteins when stressed with nontargeting control siRNA, including known ß cell hormones INS, IAPP, and IGF2. Further, EndoC-ßH1 secreted proteins known to generate bioactive peptides such as granins and enzymes required for production of bioactive peptides. EndoC-ßH1 secretome contained an unexpectedly high proportion of predicted extracellular vesicle proteins. We believe that secretion of extracellular vesicles and bioactive peptides warrant further investigation with specialized proteomics workflows in future studies.

Mitochondrial metabolism and dynamics in pancreatic beta cell glucose sensing.

Glucose-regulated insulin secretion becomes defective in all forms of diabetes. The signaling mechanisms through which the sugar acts on the ensemble of beta cells within the islet remain a vigorous area of research after more than 60 years. Here, we focus firstly on the role that the privileged oxidative metabolism of glucose plays in glucose detection, discussing the importance of 'disallowing' in the beta cell the expression of genes including Lactate dehydrogenase (Ldha) and the lactate transporter Mct1/Slc16a1 to restrict other metabolic fates for glucose. We next explore the regulation of mitochondrial metabolism by Ca2+ and its possible role in sustaining glucose signaling towards insulin secretion. Finally, we discuss in depth the importance of mitochondrial structure and dynamics in the beta cell, and their potential for therapeutic targeting by incretin hormones or direct regulators of mitochondrial fusion. This review, and the 2023 Sir Philip Randle Lecture which GAR will give at the Islet Study Group meeting in Vancouver, Canada in June 2023, honor the foundational, and sometimes under-appreciated, contributions made by Professor Randle and his colleagues towards our understanding of the regulation of insulin secretion.

Evaluation of the Effectiveness of In-Hospital Exercise Rehabilitation in Middle-Aged and Elderly Patients with Type 2 Diabetes Mellitus Combined with Sarcopenia Effect of Lifestyle Management on Disease Status in Patients with Type 2 Diabetes Mellitus.

OBJECTIVE: The aim of this study was to explore the effects of in-hospital exercise rehabilitation on glucose and lipid metabolism and healthy physical fitness in middle-aged and elderly patients with type 2 diabetes mellitus (T2DM) combined with sarcopenia, and to provide a reference for the effective implementation of exercise rehabilitation for middle-aged and elderly patients with T2DM combined with sarcopenia in healthcare institutions. METHODS: This study retrospectively included 122 patients with T2DM combined with sarcopenia treated at the General Hospital of Ningxia Medical University from August 2017 to August 2020 and randomly divided into a control group and an experimental group. The control group was given conventional treatment and the experimental group was given exercise rehabilitation in the hospital for 12 weeks to compare the indexes related to glucose and lipid metabolism and healthy fitness in the two groups. RESULTS: After the intervention, the experimental group showed significant decreases in fasting blood glucose (FBG), glycated hemoglobin (HbA1c), insulin resistance index (HOMA-IR), triglycerides (TG), total cholesterol (TC), low-density cholesterol (LDL-C) and body fat percentage (p < 0.05), while high-density cholesterol (HDL-C), grip strength, lower limb extension, lower limb flexion, peak oxygen uptake were significantly higher (p < 0.05) and were more significant at 12 weeks compared to the 6-week intervention (p < 0.05). However, there were no significant changes in any of the glucose metabolism indicators in the control group before and after the intervention. A two-way repeated measures ANOVA showed that at control baseline levels, HbA1c decreased significantly in the experimental group after both 6 and 12 weeks of intervention compared to the control group (p < 0.05). After 6 weeks of intervention, the experimental group showed a significant decrease in body fat percentage and a significant increase in grip strength. After 12 weeks of intervention, the experimental group showed an increase in glycemic control from 33.3% to 73.3%, a significant decrease in body fat percentage and a significant increase in grip strength, lower limb extension and lower limb flexion strength and peak oxygen uptake. CONCLUSION: In-hospital exercise rehabilitation can effectively improve the glycemic and lipid profiles of patients with T2DM combined with sarcopenia and enhance their health fitness, with good clinical rehabilitation effects.

Targeting Protein Kinases to Protect Beta-Cell Function and Survival in Diabetes.

The prevalence of diabetes is increasing worldwide. Massive death of pancreatic beta-cells causes type 1 diabetes. Progressive loss of beta-cell function and mass characterizes type 2 diabetes. To date, none of the available antidiabetic drugs promotes the maintenance of a functional mass of endogenous beta-cells, revealing an unmet medical need. Dysfunction and apoptotic death of beta-cells occur, in particular, through the activation of intracellular protein kinases. In recent years, protein kinases have become highly studied targets of the pharmaceutical industry for drug development. A number of drugs that inhibit protein kinases have been approved for the treatment of cancers. The question of whether safe drugs that inhibit protein kinase activity can be developed and used to protect the function and survival of beta-cells in diabetes is still unresolved. This review presents arguments suggesting that several protein kinases in beta-cells may represent targets of interest for the development of drugs to treat diabetes.

Importance of beta cell mass for glycaemic control in people with type 1 diabetes.

AIMS/HYPOTHESIS: The role of beta cell mass in the balance of glucose control and hypoglycaemic burden in people with type 1 diabetes is unclear. We applied positron emission tomography (PET) imaging with radiolabelled exendin to compare beta cell mass among people with type 1 diabetes and either low glucose variability (LGV) or high glucose variability (HGV). METHODS: All participants with either LGV (n=9) or HGV (n=7) underwent a mixed-meal tolerance test to determine beta cell function and wore a blinded continuous glucose monitor for a week. After an i.v. injection with [68Ga]Ga-NODAGA-exendin-4, PET images were acquired for the quantification of pancreatic uptake of radiolabelled exendin. The mean standardised uptake value (SUVmean) of the pancreas was used to determine the amount of beta cell mass. RESULTS: Participants with LGV had lower HbA1c (46.0 mmol/mol [44.5-52.5] [6.4% (6.3-7)] vs 80 mmol/mol [69.0-110] [9.5% (8.5-12.2)], p=0.001) and higher time in range (TIR) (75.6% [73.5-90.3] vs 38.7% [25.1-48.5], p=0.002) than those with HGV. The SUVmean of the pancreas was higher for the LGV than for the HGV group (5.1 [3.6-5.6] vs 2.9 [2.1-3.4], p=0.008). The AUCC-peptide:AUCglucose ratio was numerically, but not statistically, higher in the LGV compared with the HGV group (2.7×10-2 [6.2×10-4-5.3×10-2] vs 9.3×10-4 [4.7×10-4-5.2×10-3], p=0.21). SUVmean correlated with the AUCC-peptide:AUCglucose ratio (Pearson r=0.64, p=0.01), as well as with the TIR (r=0.64, p=0.01) and the SD of interstitial glucose levels (r=-0.66, p=0.007). CONCLUSION/INTERPRETATION: Our data show higher beta cell mass in people with type 1 diabetes and LGV than in those with HGV, independent of beta cell function.

Proprotein convertase PCSK9 affects expression of key surface proteins in human pancreatic beta cells via intracellular and extracellular regulatory circuits.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is involved in the degradation of the low-density lipoprotein receptor. PCSK9 also targets proteins involved in lipid metabolism (very low-density lipoprotein receptor), immunity (major histocompatibility complex I), and viral infection (cluster of differentiation 81). Recent studies have also indicated that PCSK9 loss-of-function mutations are associated with an increased incidence of diabetes; however, the expression and function of PCSK9 in insulin-producing pancreatic beta cells remain unclear. Here, we studied PCSK9 regulation and function by performing loss- and gain-of-function experiments in the human beta cell line EndoC-ßH1. We demonstrate that PCSK9 is expressed and secreted by EndoC-ßH1 cells. We also found that PCSK9 expression is regulated by cholesterol and sterol regulatory element-binding protein transcription factors, as previously demonstrated in other cell types such as hepatocytes. Importantly, we show that PCSK9 knockdown using siRNA results in deregulation of various elements of the transcriptome, proteome, and secretome, and increases insulin secretion. We also observed that PCSK9 decreases low-density lipoprotein receptor and very low-density lipoprotein receptor levels via an extracellular signaling mechanism involving exogenous PCSK9, as well as levels of cluster of differentiation 36, a fatty acid transporter, through an intracellular signaling mechanism. Finally, we found that PCSK9 regulates the cell surface expression of PDL1 and HLA-ABC, proteins involved in cell-lymphocyte interaction, also via an intracellular mechanism. Collectively, these results highlight PCSK9 as a regulator of multiple cell surface receptors in pancreatic beta cells.

FFA-Fetuin-A regulates DPP-IV expression in pancreatic beta cells through TLR4-NFkB pathway.

Dipeptidyl peptidase 4 (DPP-IV) is a ubiquitous proteolytic enzyme that cleaves incretin hormones, such as glucagon-like peptide 1 (GLP1) and gastric inhibitory protein (GIP), leading to reduced glucose stimulated insulin secretion from the pancreatic beta cells. The functionally active enzyme is present in a membrane bound form in several cell types as well as in a soluble form in the circulation. The present report deals with DPP-IV expression and its regulation in the pancreatic beta cells in presence of free fatty acids (FFAs) and Fetuin-A, a circulatory glycoprotein associated with insulin resistance in humans and animals. FFA and Fetuin-A individually or in combination trigger DPP-IV expression in MIN6 cells. Islets isolated from high fat diet fed (HFD) mice (16 weeks) showed higher levels of DPP-IV expression than standard diet (SD) fed mice. Fetuin-A increased DPP-IV expression in HFD mice (4 weeks). Inhibition of TLR4 or NFkB prevented palmitate-Fetuin-A mediated DPP-IV expression in MIN6. It has been seen that Fetuin-A alone also could trigger DPP-IV expression in MIN6 cells via NFkB. Additionally, palmitate treatment exhibited reduced level of soluble DPP-IV in the media of MIN6 culture, which corroborated with the expression pattern of its protease, KLK5 that cleaves and releases the membrane bound DPP-IV into the secretion. Our results demonstrate that FFA-Fetuin-A upregulates DPP-IV expression in the pancreatic beta cells through the TLR4-NFkB pathway.

Systematic Bayesian posterior analysis guided by Kullback-Leibler divergence facilitates hypothesis formation.

Bayesian inference produces a posterior distribution for the parameters of a mathematical model that can be used to guide the formation of hypotheses; specifically, the posterior may be searched for evidence of alternative model hypotheses, which serves as a starting point for hypothesis formation and model refinement. Previous approaches to search for this evidence are largely qualitative and unsystematic; further, demonstrations of these approaches typically stop at hypothesis formation, leaving the questions they raise unanswered. Here, we introduce a Kullback-Leibler (KL) divergence-based ranking to expedite Bayesian hypothesis formation and investigate the hypotheses it generates, ultimately generating novel, biologically significant insights. Our approach uses KL divergence to rank parameters by how much information they gain from experimental data. Subsequently, rather than searching all model parameters at random, we use this ranking to prioritize examining the posteriors of the parameters that gained the most information from the data for evidence of alternative model hypotheses. We test our approach with two examples, which showcase the ability of our approach to systematically uncover different types of alternative hypothesis evidence. First, we test our KL divergence ranking on an established example of Bayesian hypothesis formation. Our top-ranked parameter matches the one previously identified to produce alternative hypotheses. In the second example, we apply our ranking in a novel study of a computational model of prolactin-induced JAK2-STAT5 signaling, a pathway that mediates beta cell proliferation. Within the top 3 ranked parameters (out of 33), we find a bimodal posterior revealing two possible ranges for the prolactin receptor degradation rate. We go on to refine the model, incorporating new data and determining which degradation rate is most plausible. Overall, while the effectiveness of our approach depends on having a properly formulated prior and on the form of the posterior distribution, we demonstrate that our approach offers a novel and generalizable quantitative framework for Bayesian hypothesis formation and use it to produce a novel, biologically-significant insight into beta cell signaling.

Dolutegravir use over 48 weeks is not associated with worsening insulin resistance and pancreatic beta cell function in a cohort of HIV-infected Ugandan adults.

BACKGROUND: The Uganda Ministry of Health issued restrictive guidelines on the use of dolutegravir (DTG) in persons stratified to have a heightened risk of diabetes mellitus. This followed multiple reports of persons with HIV (PWH) presenting with accelerated hyperglycemia after a few weeks to months of exposure to DTG. Having demonstrated a low incidence of diabetes mellitus and improving blood glucose trajectories in a cohort of ART naïve Ugandan PWH on DTG, we sought to determine whether the observed improvement in blood glucose did not mask background compensated insulin resistance. METHODS: In this analysis, 63 patients underwent serial oral glucose tolerance tests over 48 weeks. Using fasting serum insulin and glucose, we calculated insulin resistance and pancreatic beta cell function by homeostatic modelling (HOMA IR and HOMA%ß respectively). Absolute mean changes between baseline and post-baseline blood glucose, pancreatic beta cell function and insulin resistance were computed by subtracting each post-baseline value from the baseline value and compared using student t-test. Multiple linear regression models were used to determine the factors associated with changes in pancreatic beta cell function and insulin resistance. RESULTS: Of the 63 participants, 37 (58%) were female. Median age was 31 (IQR: 28-37). Despite a trend towards an initial increase in both HOMA IR and HOMA%ß at 12 weeks followed by a decline through 36 weeks to 48 weeks, the HOMA IR and HOMA%ß at 48 weeks were not significantly different from baseline i.e. (difference in mean HOMA IR from baseline: 0.14, 95%CI: -0.46, 0.733, p = 0.648) and (difference in mean HOMA %ß from baseline: 6.7, 95%CI: -13.4, 26.8, p = 0.506) respectively. CONCLUSION: We demonstrated insignificant changes in both insulin resistance and pancreatic beta cell function in clinically stable young adult Ugandan PWH on dolutegravir for 48 weeks. We add to the body of evidence demonstrating glucose metabolic safety of dolutegravir in ART naïve patients. Ugandan guidelines should reconsider restricting DTG initiation in ART naive adults at high risk for diabetes.

HIV infection in adult Ugandans with new-onset type 2 diabetes: exploring its influence on the anthropometric and metabolic profile.

OBJECTIVE: HIV infection increases the risk of type 2 diabetes and may influence its phenotypic profile. In this study, we aimed to compare the anthropometric and metabolic characteristics of HIV-infected and uninfected adult Ugandans with new-onset type 2 diabetes to evaluate the influence of HIV infection on specific surrogate markers of adiposity, insulin resistance, and pancreatic beta-cell function. METHODS: We consecutively recruited 500 HIV-infected and uninfected adult Ugandans with new-onset type 2 diabetes (diagnosed in < 3 months) from seven tertiary hospitals over a 20-month period and compared their anthropometric and metabolic characteristics to identify any significant differences. RESULTS: Of the 500 participants with new-onset type 2 diabetes, 59 (11.8%) had a self-reported history of HIV infection. Compared with HIV-uninfected participants with type 2 diabetes, participants with HIV infection and type 2 diabetes had a lower median (IQR) hip circumference (97.8 [91.0-106.0] cm vs. 104.0 [96.0-112.0], p = 0.002) and visceral fat level (8 [6-11] vs. 10 [7-12], p < 0.001) assessed using bioimpedance analysis. No statistically significant difference was noted with the markers of pancreatic beta-cell function (fasting, 30-minute, and 120-minute C-peptide concentrations, oral insulinogenic index, and homeostatic model assessment 2-beta cell function) and insulin resistance (homeostatic model assessment 2-insulin resistance) between both groups. CONCLUSION: In our study population, HIV infection was not associated with increased adiposity, pancreatic beta-cell function, and insulin resistance. Large prospective studies are needed to investigate the effect of HIV on the pathogenesis of type 2 diabetes in adult Ugandans.

Mitochondrial Dynamics and Insulin Secretion.

Mitochondria are involved in the regulation of cellular energy metabolism, calcium homeostasis, and apoptosis. For mitochondrial quality control, dynamic processes, such as mitochondrial fission and fusion, are necessary to maintain shape and function. Disturbances of mitochondrial dynamics lead to dysfunctional mitochondria, which contribute to the development and progression of numerous diseases, including Type 2 Diabetes (T2D). Compelling evidence has been put forward that mitochondrial dynamics play a significant role in the metabolism-secretion coupling of pancreatic ß cells. The disruption of mitochondrial dynamics is linked to defects in energy production and increased apoptosis, ultimately impairing insulin secretion and ß cell death. This review provides an overview of molecular mechanisms controlling mitochondrial dynamics, their dysfunction in pancreatic ß cells, and pharmaceutical agents targeting mitochondrial dynamic proteins, such as mitochondrial division inhibitor-1 (mdivi-1), dynasore, P110, and 15-oxospiramilactone (S3).

Outbred Mice with Streptozotocin-Induced Diabetes Show Sex Differences in Glucose Metabolism.

Outbred mice (ICR) with different genotypes and phenotypes have been reported to be more suitable for scientific testing than inbred mice because they are more similar to humans. To investigate whether the sex and genetic background of the mice are important factors in the development of hyperglycemia, we used ICR mice and divided them into male, female, and ovariectomized female (FOVX) groups and treated them with streptozotocin (STZ) for five consecutive days to induce diabetes. Our results show that fasting blood glucose and hemoglobin A1c (HbA1c) levels were significantly higher in diabetes-induced males (M-DM) and ovariectomized diabetes-induced females (FOVX-DM) than in diabetes-induced females (F-DM) at 3 and 6 weeks after STZ treatment. Furthermore, the M-DM group showed the most severe glucose tolerance, followed by the FOVX-DM and F-DM groups, suggesting that ovariectomy affects glucose tolerance in female mice. The size of pancreatic islets in the M-DM and FOVX-DM groups was significantly different from that of the F-DM group. The M-DM and FOVX-DM groups had pancreatic beta-cell dysfunction 6 weeks after STZ treatment. Urocortin 3 and somatostatin inhibited insulin secretion in the M-DM and FOVX-DM groups. Overall, our results suggest that glucose metabolism in mice is dependent on sex and/or genetic background.

NGF and Its Role in Immunoendocrine Communication during Metabolic Syndrome.

Nerve growth factor (NGF) was the first neurotrophin described. This neurotrophin contributes to organogenesis by promoting sensory innervation and angiogenesis in the endocrine and immune systems. Neuronal and non-neuronal cells produce and secrete NGF, and several cell types throughout the body express the high-affinity neurotrophin receptor TrkA and the low-affinity receptor p75NTR. NGF is essential for glucose-stimulated insulin secretion and the complete development of pancreatic islets. Plus, this factor is involved in regulating lipolysis and thermogenesis in adipose tissue. Immune cells produce and respond to NGF, modulating their inflammatory phenotype and the secretion of cytokines, contributing to insulin resistance and metabolic homeostasis. This neurotrophin regulates the synthesis of gonadal steroid hormones, which ultimately participate in the metabolic homeostasis of other tissues. Therefore, we propose that this neurotrophin's imbalance in concentrations and signaling during metabolic syndrome contribute to its pathophysiology. In the present work, we describe the multiple roles of NGF in immunoendocrine organs that are important in metabolic homeostasis and related to the pathophysiology of metabolic syndrome.

SUMOylation, a multifaceted regulatory mechanism in the pancreatic beta cells.

SUMOylation is an evolutionarily conserved post-translational modification (PTM) that regulates protein subcellular localization, stability, conformation, transcription and enzymatic activity. Recent studies indicate that SUMOylation plays a key role in insulin gene expression, glucose metabolism and insulin exocytosis under physiological conditions in the pancreatic beta cells. Furthermore, SUMOylation is implicated in beta cell survival and recovery following exposure to oxidative stress, ER stress and inflammatory mediators under pathological situations. SUMOylation is closely regulated by the cellular redox status, and it collaborates with other PTMs such as phosphorylation, ubiquitination, and NEDDylation, to maintain beta cellular homeostasis. We hereby provide an update on recent findings regarding the role of SUMOylation in the regulation of pancreatic beta cell viability and function, and discuss its potential implication in beta cell senescence and RNA processing (e.g., pre-mRNA splicing and mRNA methylation). Through which we intend to provide novel insights into this fundamental biological process regarding both maintenance of beta cell viability and functionality, and beta cell dysfunction in diabetes mellitus.

Death versus dedifferentiation: The molecular bases of beta cell mass reduction in type 2 diabetes.

Diabetes Mellitus is currently affecting more than 425 million people worldwide, among which over 90 % of the cases belong to type 2 diabetes. The number is growing quickly every year. Together with its many complications, the disease is causing tremendous social and economic burden and is classified as one of the leading causes of high morbidity and mortality rate. Residing in the islets of Langerhans, pancreatic beta cell serves as a central mediator in glucose homeostasis through secreting insulin, the only hormone that could reduce glucose level in the body, into the blood. Abnormality in pancreatic beta cell is generally considered as the fundamental reason which is responsible for the development of diabetes. Evidence shows that beta cell mass is greatly reduced in the biopsy of type 2 diabetic patients. Since then, large amount of research was conducted in order to decipher the molecular mechanisms behind the phenotype above and enormous progression has been made. The aim of this review is to summarize and provide a rudimentary molecular road map for beta cell mass reduction from the aspects of apoptosis and dedifferentiation based on recent research advances. Hopefully, this review could give the community some enlightenment for the next-step research and, more importantly, could provide avenues for developing novel and effective therapies to restrain or reverse beta cell loss in type 2 diabetes in the clinic.

Spatial and transcriptional heterogeneity of pancreatic beta cell neogenesis revealed by a time-resolved reporter system.

AIMS/HYPOTHESIS: While pancreatic beta cells have been shown to originate from endocrine progenitors in ductal regions, it remains unclear precisely where beta cells emerge from and which transcripts define newborn beta cells. We therefore investigated characteristics of newborn beta cells extracted by a time-resolved reporter system. METHODS: We established a mouse model, 'Ins1-GFP; Timer', which provides spatial information during beta cell neogenesis with high temporal resolution. Single-cell RNA-sequencing (scRNA-seq) was performed on mouse beta cells sorted by fluorescent reporter to uncover transcriptomic profiles of newborn beta cells. scRNA-seq of human embryonic stem cell (hESC)-derived beta-like cells was also performed to compare newborn beta cell features between mouse and human. RESULTS: Fluorescence imaging of Ins1-GFP; Timer mouse pancreas successfully dissected newly generated beta cells as green fluorescence-dominant cells. This reporter system revealed that, as expected, some newborn beta cells arise close to the ducts (ßduct); unexpectedly, the others arise away from the ducts and adjacent to blood vessels (ßvessel). Single-cell transcriptomic analyses demonstrated five distinct populations among newborn beta cells, confirming spatial heterogeneity of beta cell neogenesis such as high probability of glucagon-positive ßduct, musculoaponeurotic fibrosarcoma oncogene family B (MafB)-positive ßduct and musculoaponeurotic fibrosarcoma oncogene family A (MafA)-positive ßvessel cells. Comparative analysis with scRNA-seq data of mouse newborn beta cells and hESC-derived beta-like cells uncovered transcriptional similarity between mouse and human beta cell neogenesis including microsomal glutathione S-transferase 1 (MGST1)- and synaptotagmin 13 (SYT13)-highly-expressing state. CONCLUSIONS/INTERPRETATION: The combination of time-resolved histological imaging with single-cell transcriptional mapping demonstrated novel features of spatial and transcriptional heterogeneity in beta cell neogenesis, which will lead to a better understanding of beta cell differentiation for future cell therapy. DATA AVAILABILITY: Raw and processed single-cell RNA-sequencing data for this study has been deposited in the Gene Expression Omnibus under accession number GSE155742.

Liraglutide protects ß-cells in novel human islet spheroid models of type 1 diabetes.

To enable accurate, high-throughput and longer-term studies of the immunopathogenesis of type 1 diabetes (T1D), we established three in-vitro islet-immune injury models by culturing spheroids derived from primary human islets with proinflammatory cytokines, activated peripheral blood mononuclear cells or HLA-A2-restricted preproinsulin-specific cytotoxic T lymphocytes. In all models, ß-cell function declined as manifested by increased basal and decreased glucose-stimulated insulin release (GSIS), and decreased intracellular insulin content. Additional hallmarks of T1D progression such as loss of the first-phase insulin response (FFIR), increased proinsulin-to-insulin ratios, HLA-class I expression, and inflammatory cytokine release were also observed. Using these models, we show that liraglutide, a glucagon-like peptide 1 receptor agonist, prevented loss of GSIS under T1D-relevant stress, by preserving the FFIR and decreasing immune cell infiltration and cytokine secretion. Our results corroborate that liraglutide mediates an anti-inflammatory effect that aids in protecting ß-cells from the immune-mediated attack that leads to T1D.

Time-dependent effects on circulating cytokines in patients with LADA: A decrease in IL1-ra and IL-1 beta is associated with progressive disease.

BACKGROUND: Cytokines and chemokines participate in autoimmune processes at cellular targets which include insulin-producing beta cells. To which extent such participation is reflected in the circulation has not been conclusively resolved. AIM: We compared the time course of cytokines/chemokines in Latent Autoimmune Diabetes in Adults (LADA) patients heterogeneous for high or low autoimmune activity as determined by levels of antibodies against glutamic acid decarboxylase (GADA). METHODS: Serum samples to be measured were from a two-armed randomized controlled trial (RCT) in 68 LADA patients. The study encompassed 21 months with C-peptide as primary endpoint. We measured 27 immune mediators at baseline, at 9 and at 21 months (end of study). Results of measurements were analyzed by multiple linear regression. RESULTS: At baseline, a high body mass index (BMI) (>26 kg/m2) was associated with elevated levels of the interleukins (IL) IL-1 beta, IL-1ra, IL-2, IL-5, IL-6 and IL-13. Treatment during RCT (sitagliptin vs. insulin) did not affect the time course (21 months) of levels of cytokines/chemokines (by univariate analyses). However, levels of the cytokines IL-1ra and IL-1 beta decreased significantly (p < 0.04 or less) in patients with high vs. low GADA when adjusted for BMI, age, gender (male/female), treatment (insulin/sitagliptin) and study site (Norwegian/Swedish). CONCLUSIONS: In LADA, high levels of GADA, a proxy for high autoimmune activity and linked to a decline in C-peptide, was associated with a decrease of selected cytokines over time. This implies that the decline of IL-1ra and IL-1 beta in the circulation reflects autoimmune activity and beta cell demise in LADA.

A novel technique using chronic infusion of small extracellular vesicles from gestational diabetes mellitus causes glucose intolerance in pregnant mice.

Small extracellular vesicles (sEVs) play a central role in cell-to-cell communication in normal physiology and in disease, including gestational diabetes mellitus (GDM). The goal of the present study was to test the hypothesis that chronic administration of sEVs isolated from GDM causes glucose intolerance in healthy pregnant mice. Small EVs were isolated from plasma between 24 and 28 weeks gestation from healthy pregnant women (controls) and GDM, and infused intravenously for 4 days in late pregnant mice using a mini-osmotic pump. Subsequently in vivo glucose tolerance was assessed, and muscle and adipose tissue insulin sensitivity and islet glucose stimulated insulin secretion (GSIS) were determined in vitro. Mice infused with sEVs from GDM developed glucose intolerance. Administration of sEVs from controls, but not sEVs from GDM women, stimulated islet GSIS and increased fasting insulin levels in pregnant mice. Neither infusion of sEVs from controls nor from GDM women affected muscle insulin sensitivity, placental insulin or mTOR signaling, placental and fetal weight. Moreover, these results were not associated with immunomodulatory effects as human sEVs did not activate mouse T cells in vitro. We suggest that circulating sEVs regulate maternal glucose homeostasis in pregnancy and may contribute to the attenuated islet insulin secretion and more pronounced glucose intolerance in GDM as compared with healthy pregnancy.