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From single-cell RNA-sequencing (scRNA-seq) and spatial transcriptomics (ST), one can extract high-dimensional gene expression patterns that can be described by intercellular communication networks or decoupled gene modules. These two descriptions of information flow are often assumed to occur independently. However, intercellular communication drives directed flows of information that are mediated by intracellular gene modules, in turn triggering outflows of other signals. Methodologies to describe such intercellular flows are lacking. We present FlowSig, a method that infers communication-driven intercellular flows from scRNA-seq or ST data using graphical causal modeling and conditional independence. We benchmark FlowSig using newly generated experimental cortical organoid data and synthetic data generated from mathematical modeling. We demonstrate FlowSig's utility by applying it to various studies, showing that FlowSig can capture stimulation-induced changes to paracrine signaling in pancreatic islets, demonstrate shifts in intercellular flows due to increasing COVID-19 severity and reconstruct morphogen-driven activator-inhibitor patterns in mouse embryogenesis.

Evaluating the quality of isolated human islets before transplantation is crucial for predicting the success in treating Type 1 diabetes. The current gold standard involves time-intensive in vivo transplantation into diabetic immunodeficient mice. Given the susceptibility of isolated islets to hypoxia, we hypothesized that hypoxia present in islets before transplantation could indicate compromised islet quality, potentially leading to unfavorable outcomes. To test this hypothesis, we analyzed expression of 39 hypoxia-related genes in human islets from 85 deceased donors. We correlated gene expression profiles with transplantation outcomes in 327 diabetic mice, each receiving 1200 islet equivalents grafted into the kidney capsule. Transplantation outcome was post-transplant glycemic control based on area under the curve of blood glucose over 4 weeks. In linear regression analysis, DDIT4 (R = 0.4971, P

Within the islets of Langerhans, beta cells orchestrate synchronized insulin secretion, a pivotal aspect of metabolic homeostasis. Despite the inherent heterogeneity and multimodal activity of individual cells, intercellular coupling acts as a homogenizing force, enabling coordinated responses through the propagation of intercellular waves. Disruptions in this coordination are implicated in irregular insulin secretion, a hallmark of diabetes. Recently, innovative approaches, such as integrating multicellular calcium imaging with network analysis, have emerged for a quantitative assessment of the cellular activity in islets. However, different groups use distinct experimental preparations, microscopic techniques, apply different methods to process the measured signals and use various methods to derive functional connectivity patterns. This makes comparisons between findings and their integration into a bigger picture difficult and has led to disputes in functional connectivity interpretations. To address these issues, we present here a systematic analysis of how different approaches influence the network representation of islet activity. Our findings show that the choice of methods used to construct networks is not crucial, although care is needed when combining data from different islets. Conversely, the conclusions drawn from network analysis can be heavily affected by the pre-processing of the time series, the type of the oscillatory component in the signals, and by the experimental preparation. Our tutorial-like investigation aims to resolve interpretational issues, reconcile conflicting views, advance functional implications, and encourage researchers to adopt connectivity analysis. As we conclude, we outline challenges for future research, emphasizing the broader applicability of our conclusions to other tissues exhibiting complex multicellular dynamics.

Type 1 diabetes (T1D) is a prototypic T cell-mediated autoimmune disease. Because the islets of Langerhans are insulated from blood vessels by a double basement membrane and lack detectable lymphatic drainage, interactions between endocrine and circulating T cells are not permitted. Thus, we hypothesized that initiation and progression of anti-islet immunity required islet neolymphangiogenesis to allow T cell access to the islet. Combining microscopy and single cell approaches, the timing of this phenomenon in mice was situated between 5 and 8 wk of age when activated anti-insulin CD4 T cells became detectable in peripheral blood while peri-islet pathology developed. This peri-insulitis, dominated by CD4 T cells, respected the islet basement membrane and was limited on the outside by lymphatic endothelial cells that gave it the attributes of a tertiary lymphoid structure. As in most tissues, lymphangiogenesis seemed to be secondary to local segmental endothelial inflammation at the collecting postcapillary venule. In addition to classic markers of inflammation such as CD29, V-CAM, and NOS, MHC class II molecules were expressed by nonhematopoietic cells in the same location both in mouse and human islets. This CD45- MHC class II+ cell population was capable of spontaneously presenting islet Ags to CD4 T cells. Altogether, these observations favor an alternative model for the initiation of T1D, outside of the islet, in which a vascular-associated cell appears to be an important MHC class II-expressing and -presenting cell.

Insulin is an essential regulator of blood glucose homeostasis that is produced exclusively byβcells within the pancreatic islets of healthy individuals. In those affected by diabetes, immune inflammation, damage, and destruction of isletβcells leads to insulin deficiency and hyperglycemia. Current efforts to understand the mechanisms underlyingβcell damage in diabetes rely onin vitro-cultured cadaveric islets. However, isolation of these islets involves removal of crucial matrix and vasculature that supports islets in the intact pancreas. Unsurprisingly, these islets demonstrate reduced functionality over time in standard culture conditions, thereby limiting their value for understanding native islet biology. Leveraging a novel, vascularized micro-organ (VMO) approach, we have recapitulated elements of the native pancreas by incorporating isolated human islets within a three-dimensional matrix nourished by living, perfusable blood vessels. Importantly, these islets show long-term viability and maintain robust glucose-stimulated insulin responses. Furthermore, vessel-mediated delivery of immune cells to these tissues provides a model to assess islet-immune cell interactions and subsequent islet killing-key steps in type 1 diabetes pathogenesis. Together, these results establish the islet-VMO as a novel,ex vivoplatform for studying human islet biology in both health and disease.

Type 2 diabetes (T2D) is a heterogeneous disease that develops through diverse pathophysiological processes1,2 and molecular mechanisms that are often specific to cell type3,4. Here, to characterize the genetic contribution to these processes across ancestry groups, we aggregate genome-wide association study data from 2,535,601 individuals (39.7% not of European ancestry), including 428,452 cases of T2D. We identify 1,289 independent association signals at genome-wide significance (P

Bi-hormonal islet endocrine cells have been proposed to represent an intermediate state of cellular transdifferentiation, enabling an increase in beta-cell mass in response to severe metabolic stress. Beta-cell plasticity and regenerative capacity are thought to decrease with age. We investigated the ontogeny of bi-hormonal islet endocrine cell populations throughout the human lifespan. Immunofluorescence microscopy was performed for insulin, glucagon, and somatostatin presence on paraffin-embedded sections of pancreata from 20 donors without diabetes aged between 11 days and 79 years of age. The mean proportional presence of glucagon-, insulin-, and somatostatin-immunoreactive cells within islets was 27.5%, 62.1%, and 12.1%, respectively. There was no change in the relative presence of alpha- or beta-cells with advancing age, but delta-cell presence showed a decline with age (R2 = 0.59, p < 0.001). The most abundant bi-hormonal cell phenotype observed co-stained for glucagon and insulin, representing 3.1 ± 0.3% of all islet cells. Glucagon/somatostatin and insulin/somatostatin bi-hormonal cells were also observed representing 2–3% abundance relative to islet cell number. Glucagon/insulin bi-hormonal cells increased with age (R2 = 0.30, p < 0.05) whilst insulin/somatostatin (R2 = 0.50, p < 0.01) and glucagon/somatostatin (R2 = 0.35, p < 0.05) cells decreased with age of donor. Findings show that bi-hormonal cells are present within human pancreatic islets throughout life, perhaps reflecting an ongoing potential for endocrine cell plasticity. [ABSTRACT FROM AUTHOR]

Purpose: Type 1 Diabetes (T1D) pathogenesis involves immune cells infiltrating pancreatic Islets of Langerhans, leading to T cell activation, beta cell destruction, and impaired insulin production. However, infiltration has a heterogenic nature that isn't described in detail, as not all islets are infiltrated. The aim of this study was to investigate if the observed heterogeneity is coupled to differences in immune and/or dysfunctional status of islets or exocrine cells, and if specific markers could elucidate mechanistic details of T1D pathogenesis. Procedures: The GeoMx platform was used to spatially quantify protein levels in pancreatic islets and exocrine tissue in Non-Obese Diabetic (NOD) mice. The protein panel included 17 immune activity markers and nine dysfunction markers. Immunohistochemical (IHC) staining and digital image analysis was used to analyze select marker proteins. Results: Use of the GeoMx platform to investigate T1D was shown to be possible, as Granzyme B protein levels were found to be lower in distal islet areas when compared to proximal areas. Smooth Muscle Actin protein levels were higher in exocrine areas proximal to immune-infiltrated islets, when compared to distally located exocrine areas. Findings from GeoMx were however not observed in IHC-stained sections. Conclusions: This study demonstrates that investigating T1D is possible with spatial proteomics, as the assays revealed presence of heterogenic islet areas in NOD mice, which may play a role in T1D progression and escape from immune recognition. This study highlights the potential of spatial technologies for elucidating T1D pathogenesis and future treatment strategies. [ABSTRACT FROM AUTHOR]

BACKGROUND: Type 1 diabetes (T1D) is preceded by a heterogenous pre-clinical phase, islet autoimmunity (IA). We aimed to identify pre vs. post-IA seroconversion (SV) changes in DNAm that differed across three IA progression phenotypes, those who lose autoantibodies (reverters), progress to clinical T1D (progressors), or maintain autoantibody levels (maintainers). METHODS: This epigenome-wide association study (EWAS) included longitudinal DNAm measurements in blood (Illumina 450K and EPIC) from participants in Diabetes Autoimmunity Study in the Young (DAISY) who developed IA, one or more islet autoantibodies on at least two consecutive visits. We compared reverters - individuals who sero-reverted, negative for all autoantibodies on at least two consecutive visits and did not develop T1D (n=41); maintainers - continued to test positive for autoantibodies but did not develop T1D (n=60); progressors - developed clinical T1D (n=42). DNAm data were measured before (pre-SV visit) and after IA (post-SV visit). Linear mixed models were used to test for differences in pre- vs post-SV changes in DNAm across the three groups. Linear mixed models were also used to test for group differences in average DNAm. Cell proportions, age, and sex were adjusted for in all models. Median follow-up across all participants was 15.5 yrs. (interquartile range (IQR): 10.8-18.7). RESULTS: The median age at the pre-SV visit was 2.2 yrs. (IQR: 0.8-5.3) in progressors, compared to 6.0 yrs. (IQR: 1.3-8.4) in reverters, and 5.7 yrs. (IQR: 1.4-9.7) in maintainers. Median time between the visits was similar in reverters 1.4 yrs. (IQR: 1-1.9), maintainers 1.3 yrs. (IQR: 1.0-2.0), and progressors 1.8 yrs. (IQR: 1.0-2.0). Changes in DNAm, pre- vs post-SV, differed across the groups at one site (cg16066195) and 11 regions. Average DNAm (mean of pre- and post-SV) differed across 22 regions. CONCLUSION: Differentially changing DNAm regions were located in genomic areas related to beta cell function, immune cell differentiation, and immune cell function.

While pancreatic β and α cells are considered the main drivers of blood glucose homeostasis through insulin and glucagon secretion, the contribution of δ cells and somatostatin (SST) secretion to glucose homeostasis remains unresolved. Here we provide a quantitative assessment of the physiological contribution of δ cells to the glycaemic set point in mice. Employing three orthogonal mouse models to remove SST signalling within the pancreas or transplanted islets, we demonstrate that ablating δ cells or SST leads to a sustained decrease in the glycaemic set point. This reduction coincides with a decreased glucose threshold for insulin response from β cells, leading to increased insulin secretion to the same glucose challenge. Our data demonstrate that β cells are sufficient to maintain stable glycaemia and reveal that the physiological role of δ cells is to provide tonic feedback inhibition that reduces the β cell glucose threshold and consequently lowers the glycaemic set point in vivo.

Insulin is an essential regulator of blood glucose homeostasis that is produced exclusively byβcells within the pancreatic islets of healthy individuals. In those affected by diabetes, immune inflammation, damage, and destruction of isletβcells leads to insulin deficiency and hyperglycemia. Current efforts to understand the mechanisms underlyingβcell damage in diabetes rely onin vitro-cultured cadaveric islets. However, isolation of these islets involves removal of crucial matrix and vasculature that supports islets in the intact pancreas. Unsurprisingly, these islets demonstrate reduced functionality over time in standard culture conditions, thereby limiting their value for understanding native islet biology. Leveraging a novel, vascularized micro-organ (VMO) approach, we have recapitulated elements of the native pancreas by incorporating isolated human islets within a three-dimensional matrix nourished by living, perfusable blood vessels. Importantly, these islets show long-term viability and maintain robust glucose-stimulated insulin responses. Furthermore, vessel-mediated delivery of immune cells to these tissues provides a model to assess islet-immune cell interactions and subsequent islet killing-key steps in type 1 diabetes pathogenesis. Together, these results establish the islet-VMO as a novel,ex vivoplatform for studying human islet biology in both health and disease.

Background Islet transplantation holds promise for treating selected type 1 diabetes mellitus patients, yet the scarcity of human donor organs impedes widespread adoption. Porcine islets, deemed a viable alternative, recently demonstrated successful longterm survival without zoonotic risks in a clinically relevant pig-to-non-human primate islet transplantation model. This success prompted the development of a clinical trial protocol for porcine islet xenotransplantation in humans. Methods A single-center, open-label clinical trial initiated by the sponsor will assess the safety and efficacy of porcine islet transplantation for diabetes patients at Gachon Hospital. The protocol received approval from the Gachon Hospital Institutional Review Board (IRB) and the Korean Ministry of Food and Drug Safety (MFDS) under the Investigational New Drug (IND) process. Two diabetic patients, experiencing inadequate glycemic control despite intensive insulin treatment and frequent hypoglycemic unawareness, will be enrolled. Participants and their family members will engage in deliberation before xenotransplantation during the screening period. Each patient will receive islets isolated from designated pathogen-free pigs. Immunosuppressants and systemic infection prophylaxis will follow the program schedule. The primary endpoint is to confirm the safety of porcine islets in patients, and the secondary endpoint is to assess whether porcine islets can reduce insulin dose and the frequency of hypoglycemic unawareness. Conclusion A clinical trial protocol adhering to global consensus guidelines for porcine islet xenotransplantation is presented, facilitating streamlined implementation of comparable human trials worldwide.

CD59 is a cell‐surface inhibitor of the terminal step in the complement cascade. However, in addition to its complement inhibitory function, a non‐canonical role of CD59 in pancreatic beta cells has been identified. Two recently discovered intracellular alternative splice forms of CD59, IRIS‐1 and IRIS‐2, are involved in insulin exocytosis through interactions with SNARE‐complex components. In mice, the CD59 gene has undergone duplication and to further explore the role of CD59 in insulin secretion, blood glucose homeostasis was studied in a CD59 double knockout (CD59abKO) mouse model. However, no phenotypic deviation related to insulin secretion or blood glucose homeostasis was observed for the CD59abKO mice. Instead, a CD59ba hybrid transcript formed as a consequence of the mutation induced to generate the model was identified. This hybrid transcript is expressed in pancreatic islets of the CD59abKO mice and is comprised of the remaining exons of the two CD59 genes spliced together. Similar to canonical CD59, the CD59ba hybrid was found to be glycosylated and present on the cell surface when exogenously expressed in INS‐1 832/13 cells. Furthermore, INS‐1 832/13 cells over‐expressing the mouse CD59ba hybrid retained normal insulin secretion following siRNA‐mediated knockdown of canonical CD59. Hence, although the CD59ba hybrid has lost the complement inhibitory function, the intracellular insulin secretory function remains. These results provide further information concerning the structural requirements of CD59 in its intracellular role relative to its role as a complement inhibitor. It also highlights the importance of carefully assessing plausible consequences of induced mutations in research models. [ABSTRACT FROM AUTHOR]

Producing a tissue-engineered pancreas based on a tissue-specific scaffold from a decellularized pancreas, imitating the natural pancreatic tissue microenvironment and the islets of Langerhans, is one of the approaches to treating patients with type 1 diabetes mellitus (T1DM). The aim of this work was to investigate the ability of a fine-dispersed tissue-specific scaffold (DP scaffold) from decellularized human pancreas fragments to support the islets' survival and insulin-producing function when injected in a streptozotocin-induced diabetic rat model. The developed decellularization protocol allows us to obtain a scaffold with a low DNA content (33 [26; 38] ng/mg of tissue, p < 0.05) and with the preservation of GAGs (0.92 [0.84; 1.16] µg/mg, p < 0.05) and fibrillar collagen (273.7 [241.2; 303.0] µg/mg, p < 0.05). Rat islets of Langerhans were seeded in the obtained scaffolds. The rats with stable T1DM were treated by intraperitoneal injections of rat islets alone and islets seeded on the DP scaffold. The blood glucose level was determined for 10 weeks with a histological examination of experimental animals' pancreas. A more pronounced decrease in the recipient rats' glycemia was detected after comparing the islets seeded on the DP scaffold with the control injection (by 71.4% and 51.2%, respectively). It has been shown that the DP scaffold facilitates a longer survival and the efficient function of pancreatic islets in vivo and can be used to engineer a pancreas. [ABSTRACT FROM AUTHOR]

Islet transplantation represents a promising therapeutic approach for diabetes management, yet the isolation and evaluation of pancreatic islets remain challenging. This study focuses on the isolation of islets from rabbit pancreases, followed by a comprehensive assessment of their viability and functionality. We developed a novel method for isolating islet cells from the pancreas of adult rabbits. We successfully isolated viable islets, which were subsequently evaluated through a combination of viability assays, an insulin enzyme-linked immunosorbent assay (ELISA), and fluorescence lifetime imaging microscopy (FLIM). The viability assays indicated a high percentage of intact islets post-isolation, while the insulin ELISA demonstrated robust insulin secretion in response to glucose stimulation. FLIM provided insights into the metabolic state of the islets, revealing distinct fluorescence lifetime signatures correlating with functional viability. Our findings underscore the potential of rabbit islets as a model for studying islet biology and diabetes therapy, highlighting the efficacy of combining traditional assays with advanced imaging techniques for comprehensive functional assessments. This research contributes to the optimization of islet isolation protocols and enhances our understanding of islet functional activity dynamics in preclinical settings. [ABSTRACT FROM AUTHOR]

Diabetes mellitus is a heterogeneous disease that encompasses a wide range of conditions, from mild cases to severe conditions where survival depends on insulin therapy. The Korean Diabetes Association Task Force Team for Diabetes with β-Cell Failure has established the term to classify severe refractory disease with β-cell failure. Individuals with β-cell failure are at high risk of diabetes-related complications. We propose that diabetes with β-cell failure can be diagnosed when individuals treated with multiple daily insulin injections or insulin pumps meet at least one of the following criteria: fasting C-peptide ≤ 0.6 ng/mL, non-fasting C-peptide ≤ 1.8 ng/mL, 24-hour urine C-peptide < 30 μg/day, or spot urine C-peptide/creatinine ratio ≤ 0.6 nmol/mmol. Among cases of diabetes with β-cell failure, β-cell failure with absolute insulin deficiency can be diagnosed when at least one of the following criteria is met: fasting C-peptide < 0.24 ng/mL, non-fasting C-peptide < 0.6 ng/mL, or spot urine C-peptide/creatinine ratio < 0.2 nmol/mmol. Multiple daily insulin injections with long-acting insulin analogs and rapid-acting insulin analogs or insulin pumps are required for treatment of diabetes with β-cell failure. Continuous glucose monitoring and an automated insulin delivery system, sensor-augmented pump, or smart insulin pen, along with structured education, are necessary. We call for improvements in the relevant systems to ensure that such treatments can be provided. [ABSTRACT FROM AUTHOR]

Pancreatic islets consist of multiple cell types that produce hormones required for glucose homeostasis, and islet dysfunction is a major factor in type 1 and type 2 diabetes. Numerous studies have assessed transcription across individual cell types using single-cell assays; however, there is no canonical reference of gene expression in islet cell types that is also easily accessible for researchers to query and use in bioinformatics pipelines. Here we present an integrated map of islet cell type-specific gene expression from 192,203 cells from single-cell RNA sequencing of 65 donors without diabetes, donors who were type 1 diabetes autoantibody positive, donors with type 1 diabetes, and donors with type 2 diabetes from the Human Pancreas Analysis Program. We identified 10 distinct cell types, annotated subpopulations of several cell types, and defined cell type-specific marker genes. We tested differential expression within each cell type across disease states and identified 1,701 genes with significant changes in expression, with most changes observed in β-cells from donors with type 1 diabetes. To facilitate user interaction, we provide several single-cell visualization and reference mapping tools, as well as the open-access analytical pipelines used to create this reference. The results will serve as a valuable resource to investigators studying islet biology.Article highlights

Type 2 diabetes (T2D) is associated with compromised identity of insulin-producing pancreatic islet β cells, characterized by inappropriate production of other islet cell-enriched hormones. Here, we examined how hormone misexpression was influenced by the MAFA and MAFB transcription factors, closely related proteins that maintain islet cell function. Mice specifically lacking MafA in β cells demonstrated broad, population-wide changes in hormone gene expression with an overall gene signature closely resembling islet gastrin+ (Gast+) cells generated under conditions of chronic hyperglycemia and obesity. A human β cell line deficient in MAFB, but not one lacking MAFA, also produced a GAST+ gene expression pattern. In addition, GAST was detected in human T2D β cells with low levels of MAFB. Moreover, evidence is provided that human MAFB can directly repress GAST gene transcription. These results support a potentially novel, species-specific role for MafA and MAFB in maintaining adult mouse and human β cell identity, respectively. Here, we discuss the possibility that induction of Gast/GAST and other non-β cell hormones, by reduction in the levels of these transcription factors, represents a dysfunctional β cell signature.

The creation of a cell-engineered pancreatic construct (CEPC) from islets of Langerhans and biocompatible matrix carrier (framework/scaffold), which imitates the native microenvironment of pancreatic tissue, is an approach to the treatment of type I diabetes mellitus (T1D).The objective of this work is to conduct a comparative analysis of the functional efficacy of CEPC and isolated rat islets of Langerhans after intraperitoneal administration into rats with experimental T1D.Materials and method. T1D was induced in rats by injecting low-dose (15 mg/ kg) streptozotocin (STZ) for 5 days. CEPC samples were created using viable and functional allogeneic isolated islets of Langerhans and tissue-specific scaffold obtained by decellularization of human pancreatic fragments. The rats received intraperitoneal injection of allogeneic islets of Langerhans (experimental group 1, n = 4) and CEPC (experimental group 2, n = 4). Control group rats received no treatment (n = 4). Blood glucose levels in the rats were measured, and the pancreas and kidneys of the experimental animals were examined histologically. The follow-up period for all animals continued for 10 weeks. Results. In experimental group 1, on day 7 after injection of Langerhans islets, glycemia decreased significantly from 28.2 ± 4.2 mmol/L to 13.4 ± 2.6 mmol/L. This fall persisted for 7 weeks, following which blood sugar increased to nearly their initial levels (prior to islets administration). In experimental group 2, on day 7 after CEPC administration, there was a more noticeable drop in blood sugar levels from 25.8 ± 5.1 mmol/L to 6.3 ± 2.7 mmol/L compared to experimental group 1. By the 10th week of the experiment, the average glucose level was two times lower than it was at the beginning. Blood glucose levels dropped more sharply in the CEPC group than in the islet group (by 75.6% and 52.5%, respectively).Conclusion. In T1D rats, CEPC has a more potent antidiabetic effect than islets of Langerhans. Thus, it has been shown that a tissue-specific scaffold may be used to create bioartificial pancreas in order to increase the functional efficiency of islets.

Pancreatic islet cells derived from human pluripotent stem cells hold great promise for modeling and treating diabetes. Differences between stem-cell-derived and primary islets remain, but molecular insights to inform improvements are limited. Here, we acquire single-cell transcriptomes and accessible chromatin profiles during in vitro islet differentiation and pancreas from childhood and adult donors for comparison. We delineate major cell types, define their regulomes, and describe spatiotemporal gene regulatory relationships between transcription factors. CDX2 emerged as a regulator of enterochromaffin-like cells, which we show resemble a transient, previously unrecognized, serotonin-producing pre-β cell population in fetal pancreas, arguing against a proposed non-pancreatic origin. Furthermore, we observe insufficient activation of signal-dependent transcriptional programs during in vitro β cell maturation and identify sex hormones as drivers of β cell proliferation in childhood. Altogether, our analysis provides a comprehensive understanding of cell fate acquisition in stem-cell-derived islets and a framework for manipulating cell identities and maturity.

Adaptation of the islet β cell insulin-secretory response to changing insulin demand is critical for blood glucose homeostasis, yet the mechanisms underlying this adaptation are unknown. Here, we have shown that nutrient-stimulated histone acetylation plays a key role in adapting insulin secretion through regulation of genes involved in β cell nutrient sensing and metabolism. Nutrient regulation of the epigenome occurred at sites occupied by the chromatin-modifying enzyme lysine-specific demethylase 1 (Lsd1) in islets. β Cell-specific deletion of Lsd1 led to insulin hypersecretion, aberrant expression of nutrient-response genes, and histone hyperacetylation. Islets from mice adapted to chronically increased insulin demand exhibited shared epigenetic and transcriptional changes. Moreover, we found that genetic variants associated with type 2 diabetes were enriched at LSD1-bound sites in human islets, suggesting that interpretation of nutrient signals is genetically determined and clinically relevant. Overall, these studies revealed that adaptive insulin secretion involves Lsd1-mediated coupling of nutrient state to regulation of the islet epigenome.

The Integrated Physiology of the Exocrine and Endocrine Compartments in Pancreatic Diseases workshop was a 1.5-day scientific conference at the National Institutes of Health (Bethesda, MD) that engaged clinical and basic science investigators interested in diseases of the pancreas. This report provides a summary of the proceedings from the workshop. The goals of the workshop were to forge connections and identify gaps in knowledge that could guide future research directions. Presentations were segregated into six major theme areas, including 1) pancreas anatomy and physiology, 2) diabetes in the setting of exocrine disease, 3) metabolic influences on the exocrine pancreas, 4) genetic drivers of pancreatic diseases, 5) tools for integrated pancreatic analysis, and 6) implications of exocrine-endocrine cross talk. For each theme, multiple presentations were followed by panel discussions on specific topics relevant to each area of research; these are summarized here. Significantly, the discussions resulted in the identification of research gaps and opportunities for the field to address. In general, it was concluded that as a pancreas research community, we must more thoughtfully integrate our current knowledge of normal physiology as well as the disease mechanisms that underlie endocrine and exocrine disorders so that there is a better understanding of the interplay between these compartments.

BackgroundPancreatic islet transplantation via infusion through the portal vein, has become an established clinical treatment for patients with type 1 diabetes. Because the engraftment efficiency is low, new approaches for pancreatic islets implantation are sought. The goal of this study is to explore the possibility that a non-thermal irreversible electroporation (NTIRE) decellularized matrix in the liver could be used as an engraftment site for pancreatic islets.Materials and methodsPancreatic islets or saline controls were injected at sites pre-treated with NTIRE in the livers of 7 rats, 16 hours after NTIRE treatment. Seven days after the NTIRE treatment, islet graft function was assessed by detecting insulin and glucagon in the liver with immunohistochemistry.ResultsPancreatic islets implanted into a NTIRE-treated volume of liver became incorporated into the liver parenchyma and produced insulin and glucagon in 2 of the 7 rat livers. Potential reasons for the failure to observe pancreatic islets in the remaining 5/7 rats may include local inflammatory reaction, graft rejection, low numbers of starting islets, timing of implantation.ConclusionsThis study shows that pancreatic islets can become incorporated and function in an NTIRE-generated extracellular matrix niche, albeit the success rate is low. Advances in the field could be achieved by developing a better understanding of the mechanisms of failure and ways to combat these mechanisms.

Obesity has emerged as public health problems, potentially guiding to many diseases such as diabetes mellitus type 2 and chronic kidney disease (CKD). The aims of the present investigation were to explore possible protective effect of Eurycoma longifolia (EL) extract on the islets of Langerhans and kidneys of high-fat diet (HFD) fed rats. Twenty four healthy adult male Sprague Dawley (SD) rats were randomized into four groups (n=6) and treated for 12 weeks; normal control (ND) group received only normal diet, Group NDEL was received normal diet and EL, Group HFD received HFD only, Group HFDEL received HFD and EL extracts. The animals were scarified at the end of the 12th week; the kidneys and pancreatic tissues were fixed in 10% formal saline and processed for histological studies. [ABSTRACT FROM AUTHOR]

Pancreatic endocrine cells employ a sophisticated system of paracrine and autocrine signals to synchronize their activities, including glutamate, which controls hormone release and b-cell viability by acting on glutamate receptors expressed by endocrine cells. We here investigate whether alteration of the excitatory amino acid transporter 2 (EAAT2), the major glutamate clearance system in the islet, may occur in type 2 diabetes mellitus and contribute to b-cell dysfunction. Increased EAAT2 intracellular localization was evident in islets of Langerhans from T2DM subjects as compared with healthy control subjects, despite similar expression levels. Chronic treatment of islets from healthy donors with high-glucose concentrations led to the transporter internalization in vesicular compartments and reduced [H3 ]-D-glutamate uptake (65 ± 5% inhibition), phenocopying the findings in T2DM pancreatic sections. The transporter relocalization was associated with decreased Akt phosphorylation protein levels, suggesting an involvement of the phosphoinositide 3-kinase (PI3K)/Akt pathway in the process. In line with this, PI3K inhibition by a 100-lM LY294002 treatment in human and clonal b-cells caused the transporter relocalization in intracellular compartments and significantly reduced the glutamate uptake compared to control conditions, suggesting that hyperglycemia changes the trafficking of the transporter to the plasma membrane. Upregulation of the glutamate transporter upon treatment with the antibiotic ceftriaxone rescued hyperglycemia-induced b-cells dysfunction and death. Our data underscore the significance of EAAT2 in regulating islet physiology and provide a rationale for potential therapeutic targeting of this transporter to preserve b-cell survival and function in diabetes. NEW & NOTEWORTHY The glutamate transporter SLC1A2/excitatory amino acid transporter 2 (EAAT2) is expressed on the plasma membrane of pancreatic b-cells and controls islet glutamate clearance and b-cells survival. We found that the EAAT2 membrane expression is lost in the islets of Langerhans from type 2 diabetes mellitus (T2DM) patients due to hyperglycemiainduced downregulation of the phosphoinositide 3-kinase/Akt pathway and modification of its intracellular trafficking. Pharmacological rescue of EAAT2 expression prevents b-cell dysfunction and death, suggesting EAAT2 as a new potential target of intervention in T2DM. [ABSTRACT FROM AUTHOR]

Aims: Evidence is accumulating of the therapeutic benefits of mesenchymal stromal cells (MSCs) in diabetes‐related conditions. We have identified a novel population of stromal cells within islets of Langerhans – islet stellate cells (ISCs) – which have a similar morphology to MSCs. In this study we characterize mouse ISCs and compare their morphology and function to MSCs to determine whether ISCs may also have therapeutic potential in diabetes. Methods: ISCs isolated from mouse islets were compared to mouse bone marrow MSCs by analysis of cell morphology; expression of cell‐surface markers and extracellular matrix (ECM) components; proliferation; apoptosis; paracrine activity; and differentiation into adipocytes, chondrocytes and osteocytes. We also assessed the effects of co‐culture with ISCs or MSCs on the insulin secretory capacity of islet beta cells. Results: Although morphological similar, ISCs were functionally distinct from MSCs. Thus, ISCs were less proliferative and more apoptotic; they had different expression levels of important paracrine factors; and they were less efficient at differentiation down multiple lineages. Co‐culture of mouse islets with ISCs enhanced glucose induced insulin secretion more effectively than co‐culture with MSCs. Conclusions: ISCs are a specific sub‐type of islet‐derived stromal cells that possess biological behaviors distinct from MSCs. The enhanced beneficial effects of ISCs on islet beta cell function suggests that they may offer a therapeutic target for enhancing beta cell functional survival in diabetes. [ABSTRACT FROM AUTHOR]

Background Bisphenol A (BPA) is an endocrine disrupter affecting glucose homeostasis. Objectives This study aimed to investigate BPA's relationship with Type 1 Diabetes Mellitus (T1DM) in Dakahlia Governorate's children, in Egypt. Subjects, materials and methods The study had two parts: clinical and experimental. Clinical Study was conducted on 200 children, equally divided into control and T1DM groups. They underwent: demographic data, height, weight, body mass index, glycosylated HbA1C, random blood glucose, and urinary BPA measurements. Experimental Study was conducted on 60 adult albino rats. Rats were randomly divided into three equal groups: control group: received 0.5 mL of pure olive oil, group 1: received 20 mg/kg/day BPA, and group 2: received 100 mg/kg/day BPA orally for 6 weeks. Fasting and two hours postprandial glucose levels were measured at the beginning and end of the study. Histopathological examination and imaging study of the pancreas were done. Results In clinical study: HbA1C and random blood glucose levels in diabetic children showed a significant increase compared to control. Children in control group showed controlled HbA1C, while the T1DM group showed 86% with poor diabetic control. There was a significant increase in BPA level in the T1DM group compared to the control. Rats that received BPA showed a marked increase in fasting and two hours postprandial glucose levels, histopathological changes in the pancreas with more changes determined in the high dose group, and a significant decrease in the islets of Langerhans diameters with group 2 more affected. Conclusion So, BPA exposure could be considered a risk factor for T1DM in children. [ABSTRACT FROM AUTHOR]

The need for maintaining cell-spheroid viability and function within high-density cultures is unmet for various clinical and experimental applications, including cell therapies. One immediate application is for transplantation of pancreatic islets, a clinically recognized treatment option to cure type 1 diabetes; islets are isolated from a donor for subsequent culture prior to transplantation. However, high seeding conditions cause unsolicited fusion of multiple spheroids, thereby limiting oxygen diffusion to induce hypoxic cell death. Here we introduce a culture dish incorporating a micropyramid-patterned surface to prevent the unsolicited fusion and oxygen-permeable bottom for optimal oxygen environment. A 400µm-thick, oxygen-permeable polydimethylsiloxane sheet topped with micropyramid pattern of 400µm-base and 200µm-height was fabricated to apply to the 24-well plate format. The micropyramid pattern separated the individual pancreatic islets to prevent the fusion of multiple islets. This platform supported the high oxygen demand of islets at high seeding density at 260 islet equivalents cm-2, a 2-3-fold higher seeding density compared to the conventional islet culture used in a preparation for the clinical islet transplantations, demonstrating improved islet morphology, metabolism and function in a 4 d-culture. Transplantation of these islets into immunodeficient diabetic mice exhibited significantly improved engraftment to achieve euglycemia compared to islets cultured in the conventional culture wells. Collectively, this simple design modification allows for high-density cultures of three-dimensional cell spheroids to improve the viability and function for an array of investigational and clinical replacement tissues.

BackgroundHigh throughput sequencing has enabled the interrogation of the transcriptomic landscape of glucagon-secreting alpha cells, insulin-secreting beta cells, and somatostatin-secreting delta cells. These approaches have furthered our understanding of expression patterns that define healthy or diseased islet cell types and helped explicate some of the intricacies between major islet cell crosstalk and glucose regulation. All three endocrine cell types derive from a common pancreatic progenitor, yet alpha and beta cells have partially opposing functions, and delta cells modulate and control insulin and glucagon release. While gene expression signatures that define and maintain cellular identity have been widely explored, the underlying epigenetic components are incompletely characterized and understood. However, chromatin accessibility and remodeling is a dynamic attribute that plays a critical role to determine and maintain cellular identity.ResultsHere, we compare and contrast the chromatin landscape between mouse alpha, beta, and delta cells using ATAC-Seq to evaluate the significant differences in chromatin accessibility. The similarities and differences in chromatin accessibility between these related islet endocrine cells help define their fate in support of their distinct functional roles. We identify patterns that suggest that both alpha and delta cells are poised, but repressed, from becoming beta-like. We also identify patterns in differentially enriched chromatin that have transcription factor motifs preferentially associated with different regions of the genome. Finally, we not only confirm and visualize previously discovered common endocrine- and cell specific- enhancer regions across differentially enriched chromatin, but identify novel regions as well. We compiled our chromatin accessibility data in a freely accessible database of common endocrine- and cell specific-enhancer regions that can be navigated with minimal bioinformatics expertise.ConclusionsBoth alpha and delta cells appear poised, but repressed, from becoming beta cells in murine pancreatic islets. These data broadly support earlier findings on the plasticity in identity of non-beta cells under certain circumstances. Furthermore, differential chromatin accessibility shows preferentially enriched distal-intergenic regions in beta cells, when compared to either alpha or delta cells.

BACKGROUND Bone marrow stem cells have been shown to be a promising therapeutic strategy for autoimmune diseases. This study aimed to assess the safety and efficacy of autologous hematopoietic stem cell (ABMSC) transplantation without immunoablation used to suppress the autoimmune reaction in 6 children with newly diagnosed autoimmune diabetes mellitus. We monitored the levels of islet cell antibodies (ICA), antibodies against islet antigen-related tyrosine phosphatase 2 (IA2), glutamic acid-decarboxylase (GAD) antibodies, and anti-insulin antibodies (AIA). MATERIAL AND METHODS Between 2018 and 2022, 6 children (age 6-10 years, average 8 years) recently diagnosed with type 1 diabetes mellitus with the presence of ICA, IA2, GAD, AIA and ketoacidosis, were treated with an ABMSC stimulated with Filgrastim, granulocyte colony-stimulating factor (G-CSF), 10 ug/kg/day for 4 days. Bone marrow was harvested on day 5, collected by puncture and identified as mononuclear cells >180×10⁶/kg, CD34+ >0.22%, and transplanted by intravenous (i.v.) infusion. Patients were monitored with ICA, IA2, GAD, AIA, C-peptide, blood glucose, and glycosylated hemoglobin A1c (HbA1C) 6 months after the procedure. RESULTS At 6-month follow-up, we observed a negative value of the ICA, which was previously positive (P

Oxylipins, pro-inflammatory and pro-resolving lipid mediators, are associated with the risk of type 1 diabetes (T1D) and may be influenced by diet. This study aimed to develop a nutrient pattern related to oxylipin profiles and test their associations with the risk of T1D among youth. The nutrient patterns were developed with a reduced rank regression in a nested case-control study (n = 335) within the Diabetes Autoimmunity Study in the Young (DAISY), a longitudinal cohort of children at risk of T1D. The oxylipin profiles (adjusted for genetic predictors) were the response variables. The nutrient patterns were tested in the case-control study (n = 69 T1D cases, 69 controls), then validated in the DAISY cohort using a joint Cox proportional hazards model (n = 1933, including 81 T1D cases). The first nutrient pattern (NP1) was characterized by low beta cryptoxanthin, flavanone, vitamin C, total sugars and iron, and high lycopene, anthocyanidins, linoleic acid and sodium. After adjusting for T1D family history, the HLA genotype, sex and race/ethnicity, NP1 was associated with a lower risk of T1D in the nested case-control study (OR: 0.44, p = 0.0126). NP1 was not associated with the risk of T1D (HR: 0.54, p-value = 0.1829) in the full DAISY cohort. Future studies are needed to confirm the nested case-control findings and investigate the modifiable factors for oxylipins.

Background Administration of pancreatic endoplasmic reticulum kinase inhibitor (PERKi) improved insulin secretion and hyperglycemia in obese diabetic mice. In this study, autophagic balance was studied whether to mediate it. Methods Human islets were isolated from living patients without diabetes. PERKi GSK2606414 effects were evaluated in the islets under glucolipotoxicity by palmitate. Islet insulin contents and secretion were measured. Autophagic flux was assessed by microtubule associated protein 1 light chain 3 (LC3) conversion, a red fluorescent protein (RFP)-green fluorescent protein (GFP)- LC3 tandem assay, and P62 levels. For mechanical analyses, autophagy was suppressed using 3-methyladenine in mouse islets. Small interfering RNA for an autophagy-related gene autophagy related 7 (Atg7) was transfected to interfere autophagy. Results PERKi administration to mice decreased diabetes-induced P62 levels in the islets. Glucolipotoxicity significantly increased PERK phosphorylation by 70% and decreased insulin contents by 50% in human islets, and addition of PERKi (40 to 80 nM) recovered both. PERKi also enhanced glucose-stimulated insulin secretion (6-fold). PERKi up-regulated LC3 conversion suppressed by glucolipotoxicity, and down-regulated P62 contents without changes in P62 transcription, indicating enhanced autophagic flux. Increased autophagosome-lysosome fusion by PERKi was visualized in mouse islets, where PERKi enhanced Atg7 bound to LC3. Suppression of Atg7 eliminated PERKi-induced insulin contents and secretion. Conclusion This study provided functional changes of human islets with regard to autophagy under glucolipotoxicity, and suggested modulation of autophagy as an anti-diabetic mechanism of PERKi.

Over a period of almost 30 years, Gomori was one of the most prolific and productive investigators in the emerging field of enzyme histochemistry and was recognized by his peers as a pioneer in developing methods for the histochemical demonstration of hydrolytic enzyme activity, most notably phosphatases, esterases, and lipases. Gomori also made important contributions to diabetes research by developing histological techniques that reliably stained the insulin-secreting B cell of the pancreatic islets of Langerhans. Gomori's aldehyde fuchsin staining method was standard for pathological and physiological studies on islet B cells in relation to diabetes and obesity until insulin antibodies became widely available for immunohistochemical identification of B cells. Gomori was a founding member of The Histochemical Society in 1950. When the HCS established the Journal of Histochemistry and Cytochemistry in 1953, Gomori served as one of the first Associate Editors. He also served as President of The Histochemical Society. [ABSTRACT FROM AUTHOR]

AbstractThe "Integrated Physiology of the Exocrine and Endocrine Compartments in Pancreatic Diseases" Workshop was a 1.5-day scientific conference at the National Institutes of Health (Bethesda, MD) that engaged clinical and basic science investigators interested in diseases of the pancreas. This report summarizes the workshop proceedings. The goal of the workshop was to forge connections and identify gaps in knowledge that could guide future research directions. Presentations were segregated into 6 major themes, including (a) Pancreas Anatomy and Physiology; (b) Diabetes in the Setting of Exocrine Disease; (c) Metabolic Influences on the Exocrine Pancreas; (d) Genetic Drivers of Pancreatic Diseases; (e) Tools for Integrated Pancreatic Analysis; and (f) Implications of Exocrine-Endocrine Crosstalk. For each theme, there were multiple presentations followed by panel discussions on specific topics relevant to each area of research; these are summarized herein. Significantly, the discussions resulted in the identification of research gaps and opportunities for the field to address. In general, it was concluded that as a pancreas research community, we must more thoughtfully integrate our current knowledge of the normal physiology as well as the disease mechanisms that underlie endocrine and exocrine disorders so that there is a better understanding of the interplay between these compartments.

Inflammation and oxidative stress in pancreatic islets amplify the appearance of various posttranslational modifications to self-proteins. In this study, we identified a select group of carbonylated islet proteins arising before the onset of hyperglycemia in NOD mice. Of interest, we identified carbonyl modification of the prolyl-4-hydroxylase β subunit (P4Hb) that is responsible for proinsulin folding and trafficking as an autoantigen in both human and murine type 1 diabetes. We found that carbonylated P4Hb is amplified in stressed islets coincident with decreased glucose-stimulated insulin secretion and altered proinsulin-to-insulin ratios. Autoantibodies against P4Hb were detected in prediabetic NOD mice and in early human type 1 diabetes prior to the onset of anti-insulin autoimmunity. Moreover, we identify autoreactive CD4+ T-cell responses toward carbonyl-P4Hb epitopes in the circulation of patients with type 1 diabetes. Our studies provide mechanistic insight into the pathways of proinsulin metabolism and in creating autoantigenic forms of insulin in type 1 diabetes.

Islets of Langerhans are anatomically dispersed within the pancreas and exhibit regulatory coordination between islets in response to nutritional and inflammatory stimuli. However, within individual islets, there is also multi-faceted coordination of function between individual beta-cells, and between beta-cells and other endocrine and vascular cell types. This is mediated partly through circulatory feedback of the major secreted hormones, insulin and glucagon, but also by autocrine and paracrine actions within the islet by a range of other secreted products, including somatostatin, urocortin 3, serotonin, glucagon-like peptide-1, acetylcholine, and ghrelin. Their availability can be modulated within the islet by pericyte-mediated regulation of microvascular blood flow. Within the islet, both endocrine progenitor cells and the ability of endocrine cells to trans-differentiate between phenotypes can alter endocrine cell mass to adapt to changed metabolic circumstances, regulated by the within-islet trophic environment. Optimal islet function is precariously balanced due to the high metabolic rate required by beta-cells to synthesize and secrete insulin, and they are susceptible to oxidative and endoplasmic reticular stress in the face of high metabolic demand. Resulting changes in paracrine dynamics within the islets can contribute to the emergence of Types 1, 2 and gestational diabetes. [ABSTRACT FROM AUTHOR]

Islet transplantation is a curative treatment for patients suffering from type 1 diabetes and has the potential to replace current treatment strategies involving the exogenous administration of insulin. Despite this potential, there are many hurdles in achieving successful long‐term graft survival due to autoimmune and foreign body reactions leading to graft rejection coupled with donor shortage and potential adverse effects from the need for long‐term administration of immunosuppressive drugs. As a result, various approaches have been proposed to increase the viability and function of islet grafts during isolation and ex vivo culture with the use of growth factors, hormones, and other therapeutic agents. In addition, other strategies have addressed how to enhance or maintain islet graft performance after implantation with improvements on immunosuppressive drug regimens and the use of biomaterials to encapsulate and protect the cells from graft rejection. This review focuses on the recent advances in strategies to improve islet viability and function with the addition of exogenous compounds and the implementation of conformal coating as a promising tool for immunoprotection of islet transplants. [ABSTRACT FROM AUTHOR]

Detailed characterization of human pancreatic islets is key to elucidating the pathophysiology of all forms of diabetes, especially type 2 diabetes. However, access to human pancreatic islets is limited. Pancreatic tissue for islet retrieval can be obtained from brain-dead organ donors or from individuals undergoing pancreatectomy, often referred to as living donors. Different protocols for human islet procurement can substantially impact islet function. This variability, coupled with heterogeneity between individuals and islets, results in analytical challenges to separate genuine disease pathology or differences between human donors from experimental noise. There are currently no international guidelines for human donor phenotyping, islet procurement and functional characterization. This lack of standardization means that substantial investments from multiple international efforts towards improved understanding of diabetes pathology cannot be fully leveraged. In this Perspective, we overview the status of the field of human islet research, highlight the challenges and propose actions that could accelerate research progress and increase understanding of type 2 diabetes to slow its pandemic spreading.

Dietary fructose, especially in the context of a high-fat western diet, has been linked to type 2 diabetes. Although the effect of fructose on liver metabolism has been extensively studied, a significant portion of the fructose is first metabolized in the small intestine. Here, we report that dietary fat enhances intestinal fructose metabolism, which releases glycerate into the blood. Chronic high systemic glycerate levels induce glucose intolerance by slowly damaging pancreatic islet cells and reducing islet sizes. Our findings provide a link between dietary fructose and diabetes that is modulated by dietary fat.

Delineating gene regulatory networks that orchestrate cell-type specification is a continuing challenge for developmental biologists. Single-cell analyses offer opportunities to address these challenges and accelerate discovery of rare cell lineage relationships and mechanisms underlying hierarchical lineage decisions. Here, we describe the molecular analysis of mouse pancreatic endocrine cell differentiation using single-cell transcriptomics, chromatin accessibility assays coupled to genetic labeling, and cytometry-based cell purification. We uncover transcription factor networks that delineate β-, α-, and δ-cell lineages. Through genomic footprint analysis, we identify transcription factor-regulatory DNA interactions governing pancreatic cell development at unprecedented resolution. Our analysis suggests that the transcription factor Neurog3 may act as a pioneer transcription factor to specify the pancreatic endocrine lineage. These findings could improve protocols to generate replacement endocrine cells from renewable sources, like stem cells, for diabetes therapy.

Urocortin 3 (UCN3) is a peptide hormone expressed in pancreatic islets of Langerhans of both human alpha and human beta cells and solely in murine beta cells. UCN3 signaling acts locally within the islet to activate its cognate receptor, corticotropin releasing hormone receptor 2 (CRHR2), which is expressed by delta cells, to potentiate somatostatin (SST) negative feedback to reduce islet cell hormone output. The functional importance of UCN3 signaling in the islet is to modulate the amount of SST tone allowing for finely tuned regulation of insulin and glucagon secretion. UCN3 signaling is a hallmark of functional beta cell maturation, increasing the beta cell glucose threshold for insulin secretion. In doing so, UCN3 plays a relevant functional role in accurately maintaining blood glucose homeostasis. Additionally, UCN3 acts as an indicator of beta cell maturation and health, as UCN3 is not expressed in immature beta cells and is downregulated in dedifferentiated and dysfunctional beta cell states. Here, we review the mechanistic underpinnings of UCN3 signaling, its net effect on islet cell hormone output, as well as its value as a marker for beta cell maturation and functional status.

Pancreatic α-cells are important in maintaining metabolic homeostasis, but their role in regulating maternal metabolic adaptations to pregnancy has not been studied. The objective of this study was to determine whether pancreatic α-cells respond to pregnancy and their contribution to maternal metabolic adaptation. With use of C57BL/6 mice, the findings of our study showed that pregnancy induced a significant increase of α-cell mass by promoting α-cell proliferation that was associated with a transitory increase of maternal serum glucagon concentration in early pregnancy. Maternal pancreatic GLP-1 content also was significantly increased during pregnancy. Using the inducible Cre/loxp technique, we ablated the α-cells (α-null) before and during pregnancy while maintaining enteroendocrine L-cells and serum GLP-1 in the normal range. In contrast to an improved glucose tolerance test (GTT) before pregnancy, significantly impaired GTT and remarkably higher serum glucose concentrations in the fed state were observed in α-null dams. Glucagon receptor antagonism treatment, however, did not affect measures of maternal glucose metabolism, indicating a dispensable role of glucagon receptor signaling in maternal glucose homeostasis. However, the GLP-1 receptor agonist improved insulin production and glucose metabolism of α-null dams. Furthermore, GLP-1 receptor antagonist Exendin (9-39) attenuated pregnancy-enhanced insulin secretion and GLP-1 restored glucose-induced insulin secretion of cultured islets from α-null dams. Together, these results demonstrate that α-cells play an essential role in controlling maternal metabolic adaptation to pregnancy by enhancing insulin secretion.

Cell replacement therapy using β cells derived from stem cells is a promising alternative to conventional diabetes treatment options. Although current differentiation methods produce glucose-responsive β cells, they can also yield populations of undesired endocrine progenitors and other proliferating cell types that might interfere with long-term islet function and safety of transplanted cells. Here, we describe the generation of an array of monoclonal antibodies against cell surface markers that selectively label stem cell-derived islet cells. A high-throughput screen identified promising candidates, including three clones that mark a high proportion of endocrine cells in differentiated cultures. A scalable magnetic sorting method was developed to enrich for human pluripotent stem cell (hPSC)-derived islet cells using these three antibodies, leading to the formation of islet-like clusters with improved glucose-stimulated insulin secretion and reduced growth upon transplantation. This strategy should facilitate large-scale production of functional islet clusters from stem cells for disease modeling and cell replacement therapy.

ObjectiveThe contribution of beta-cell dysfunction to type 2 diabetes (T2D) is not restricted to insulinopenia in the late stages of the disease. Elevated fasting insulinemia in normoglycemic humans is a major factor predicting the onset of insulin resistance and T2D, demonstrating an early alteration of beta-cell function in T2D. Moreover, an early and chronic increase in fasting insulinemia contributes to insulin resistance in high-fat diet (HFD)-fed mice. However, whether there are genetic factors that promote beta-cell-initiated insulin resistance remains undefined. Human variants of the mitochondrial transporter ABCB10, which regulates redox by increasing bilirubin synthesis, have been associated with an elevated risk of T2D. The effects of T2D ABCB10 variants on ABCB10 expression and the actions of ABCB10 in beta-cells are unknown.MethodsThe expression of beta-cell ABCB10 was analyzed in published transcriptome datasets from human beta-cells carrying the T2D-risk ABCB10 variant. Insulin sensitivity, beta-cell proliferation, and secretory function were measured in beta-cell-specific ABCB10 KO mice (Ins1Cre-Abcb10flox/flox). The short-term role of beta-cell ABCB10 activity on glucose-stimulated insulin secretion (GSIS) was determined in isolated islets.ResultsCarrying the T2Drisk allele G of ABCB10 rs348330 variant was associated with increased ABCB10 expression in human beta-cells. Constitutive deletion of Abcb10 in beta-cells protected mice from hyperinsulinemia and insulin resistance by limiting HFD-induced beta-cell expansion. An early limitation in GSIS and H2O2-mediated signaling caused by elevated ABCB10 activity can initiate an over-compensatory expansion of beta-cell mass in response to HFD. Accordingly, increasing ABCB10 expression was sufficient to limit GSIS capacity. In health, ABCB10 protein was decreased during islet maturation, with maturation restricting beta-cell proliferation and elevating GSIS. Finally, ex-vivo and short-term deletion of ABCB10 in islets isolated from HFD-fed mice increased H2O2 and GSIS, which was reversed by bilirubin treatments.ConclusionsBeta-cell ABCB10 is required for HFD to induce insulin resistance in mice by amplifying beta-cell mass expansion to maladaptive levels that cause fasting hyperinsulinemia.

Aims/hypothesisType 2 diabetes is characterised by islet amyloid and toxic oligomers of islet amyloid polypeptide (IAPP). We posed the questions, (1) does IAPP toxicity induce an islet response comparable to that in humans with type 2 diabetes, and if so, (2) what are the key transcriptional drivers of this response?MethodsThe islet transcriptome was evaluated in five groups of mice: beta cell specific transgenic for (1) human IAPP, (2) rodent IAPP, (3) human calpastatin, (4) human calpastatin and human IAPP, and (5) wild-type mice. RNA sequencing data was analysed by differential expression analysis and gene co-expression network analysis to establish the islet response to adaptation to an increased beta cell workload of soluble rodent IAPP, the islet response to increased expression of oligomeric human IAPP, and the extent to which the latter was rescued by suppression of calpain hyperactivation by calpastatin. Rank-rank hypergeometric overlap analysis was used to compare the transcriptome of islets from human or rodent IAPP transgenic mice vs humans with prediabetes or type 2 diabetes.ResultsThe islet transcriptomes in humans with prediabetes and type 2 diabetes are remarkably similar. Beta cell overexpression of soluble rodent or oligomer-prone human IAPP induced changes in islet transcriptome present in prediabetes and type 2 diabetes, including decreased expression of genes that confer beta cell identity. Increased expression of human IAPP, but not rodent IAPP, induced islet inflammation present in prediabetes and type 2 diabetes in humans. Key mediators of the injury responses in islets transgenic for human IAPP or those from individuals with type 2 diabetes include STAT3, NF-κB, ESR1 and CTNNB1 by transcription factor analysis and COL3A1, NID1 and ZNF800 by gene regulatory network analysis.Conclusions/interpretationBeta cell injury mediated by IAPP is a plausible mechanism to contribute to islet inflammation and dedifferentiation in type 2 diabetes. Inhibition of IAPP toxicity is a potential therapeutic target in type 2 diabetes.

Various microbial products leaked from gut lumen exacerbate tissue inflammation and metabolic disorders in obesity. Vsig4+ macrophages are key players preventing infiltration of bacteria and their products into host tissues. However, roles of islet Vsig4+ macrophages in the communication between microbiota and β cells in pathogenesis of obesity-associated islet abnormalities are unknown. Here, we find that bacterial DNAs are enriched in β cells of individuals with obesity. Intestinal microbial DNA-containing extracellular vesicles (mEVs) readily pass through obese gut barrier and deliver microbial DNAs into β cells, resulting in elevated inflammation and impaired insulin secretion by triggering cGAS/STING activation. Vsig4+ macrophages prevent mEV infiltration into β cells through a C3-dependent opsonization, whereas loss of Vsig4 leads to microbial DNA enrichment in β cells after mEV treatment. Removal of microbial DNAs blunts mEV effects. Loss of Vsig4+ macrophages leads to microbial DNA accumulation in β cells and subsequently obesity-associated islet abnormalities.

Leonid Vasilyevich Sobolev is an outstanding pathologist, whose name definitely should occupy an honorable place in the galaxy of great scientists of Russia. However, his name was undeservedly forgotten, and the role of his work was underestimated. This Russian scientist made the most important discovery: he proved in an experiment that it is the islets of Langerhans in the pancreas that secrete a humoral regulator, "factor X", the deficiency of which leads to diabetes mellitus. This mysterious islet factor will be isolated from the pancreas of dogs in 1921 by the future Nobel laureate Frederick G. Banting and will become part of the medicine as insulin. However, there is every reason to believe that the discovery of F. G. Banting, who repeated a series of experiments by Leonid Vasilyevich Sobolev, is, in fact, secondary, which is the research subject in this paper.

Aims: Pancreatic islet allotransplantation is an effective therapy for type 1 diabetes mellitus, restoring glycaemic control and hypoglycaemic awareness in patients with recurrent severe hypoglycaemia. Insulin independence following transplant is being increasingly reported; however, this is not a primary endpoint in the UK. Having surpassed 10 years of islet transplantation in Scotland, we aimed to evaluate the impact of insulin independence following transplant on metabolic outcomes and graft survival. Methods: We conducted a retrospective analysis on data collected prospectively between 2011 and 2022. Patients who underwent islet transplantation in Scotland up to the 31st January 2020 were included. Primary endpoint was graft survival (stimulated C‐peptide >50 pmol/L). Secondary endpoints included GOLD score, HbA1c, C‐peptide and insulin requirement. Outcomes were compared between patients who achieved insulin independence at any point following transplant versus those who did not. Results: 60 patients were included. 74.5% experienced >50 severe hypoglycaemic episodes in the year preceding transplant. There was a 55.0% decrease in insulin requirement following transplant and 30.0% achieved insulin independence. Mean graft survival time was 9.0 years (95% CI 7.2–10.9) in patients who achieved insulin independence versus 4.4 years (95% CI 3.4–5.3) in patients who did not. Insulin independence was associated with significantly improved graft function, glycaemic control and hypoglycaemic awareness at 1 year. Conclusions: This is the largest UK single‐centre study on islet transplant to date. Our findings demonstrate significantly improved outcomes in patients who achieved insulin independence following islet transplantation. [ABSTRACT FROM AUTHOR]

Type 1 diabetes is caused by a deficiency of insulin secretion which has been considered traditionally as the outcome of a precipitous decline in the viability of β-cells in the islets of Langerhans, brought about by autoimmune-mediated attack. Consistent with this, various classes of lymphocyte, as well as cells of the innate immune system have been found in association with islets during disease progression. However, analysis of human pancreas from subjects with type 1 diabetes has revealed that insulitis is often less intense than in equivalent animal models of the disease and can affect many fewer islets than expected, at disease onset. This is especially true in subjects developing type 1 diabetes in, or beyond, their teenage years. Such studies imply that both the phenotype and the number of immune cells present within insulitic lesions can vary among individuals in an age-dependent manner. Additionally, the influent lymphocytes are often mainly arrayed peripherally around islets rather than gaining direct access to the endocrine cell core. Thus, insulitis remains an enigmatic phenomenon in human pancreas and this review seeks to explore the current understanding of its likely role in the progression of type 1 diabetes. [ABSTRACT FROM AUTHOR]