Insulin-positive Cells Research Articles

IN EXPERIMENTAL RAT DIABETES TRANSCRIPTION FACTOR MAFA IS SYNTHESIZED IN DIFFERENTIATED PANCREATIC ISLET CELLS AND DOES NOT SERVE AS A MARKER OF PROGENITOR CELLS

Different transcription factors, which are synthesized at different stages of cell differentiation, are often considered markers of p-cell precursors. One of these transcription factors is MafA, the role of which is not fully understood. According to one hypothesis, it activates insulin gene expression in the differentiating p-cells. According to another, this factor is only necessary for the regulation of insulin secretion by already differentiated p-cells. In favor of the latter hypothesis, we showed that MafA is not expressed in the immature p-cells during the prenatal development of the human pancreas. In order to finally determine whether MafA is a marker of differentiating cells or it is synthesized in already mature p-cells the aim of our investigation was the analysis of dynamical changes of MafA-positive cell population and C-kit-positive endocrinocyte precursors in Langerhans islets during experimental diabetes in rats. The study was performed on male Wistar rats (250-300g body weight) which were intraperitoneally injected with alloxan. Animals were sacrificed 1,2, 7, 14, 21 days of the experiment for the morphological analysis of pancreas. Paraffin sections of pancreas were stained immunohistochemically with antibodies against MafA, C-kit, insulin and glucagon. The maximum number of MafA-positive cells in the islets was found during normal prenatal development of pancreas. At all stages of the experimental diabetes the number of MafA-positive cells in the islets decreased, wherein the number of insulin-positive cells in the islets increased by the end of the first and third weeks of the experiment. It was also established that in experimental diabetes, changes in populations of MafA- and C-kit-positive cells occur in different ways. Thus, the results of our research showed that MafA cannot be considered as a marker of progenitor cells and is expressed only in the mature cells of the Langerhans islets, that confirms our previous data obtained during the study of prenatal development of human pancreas.

Comparison of glycemic improvement between intermittent calorie restriction and continuous calorie restriction in diabetic mice

BackgroundCalorie restriction (CR) has been well proved to be a powerful tool to improve metabolic health associated with aging; and many types of CR have been proposed. Intermittent CR has become a trend in recent years due to its better compliance than continuous CR every day. However, there are few studies that directly compare the interventional activity of intermittent CR vs continuous CR in metabolic disorders such as diabetes.MethodsIn this study, we analyzed two protocols of intermittent CR with the calorie-matched continuous CR in two diabetic mouse models including db/db and streptozotocin-treated mice. Intermittent CR was carried out by a fasting-mimicking diet (FMD, with 30% calorie intake of the control per day) for 2 days or 5 days (i.e., 2–5 or 5–9 regimes followed by free eating for 5 or 9 days respectively).ResultsIn the two diabetic mouse models, both intermittent CR and continuous CR significantly reduced fasting blood glucose level and improved insulin sensitivity. However, intermittent CR performed significantly better than continuous CR in improving glycemic control and insulin sensitivity in db/db mice. In addition, intermittent CR improved the glucose homeostasis of the db/db mice without causing loss of body weight. Analyses with the pancreatic islets reveal that intermittent CR profoundly elevated the number of insulin-positive cells in both diabetic mouse models.ConclusionsOur study indicated that both intermittent CR and continuous CR can lower fasting blood glucose level in the diabetic mice, while intermittent CR is better than the latter in improving glucose homeostasis in db/db mice.

Targeted Derivation of Organotypic Glucose- and GLP-1-Responsive β Cells Prior to Transplantation into Diabetic Recipients.

SummaryGeneration of functional β cells from pluripotent sources would accelerate diagnostic and therapeutic applications for diabetes research and therapy. However, it has been challenging to generate competent β cells with dynamic insulin-secretory capacity to glucose and incretin stimulations. We introduced transcription factors, critical for β-cell development and function, in differentiating human induced pluripotent stem cells (PSCs) and assessed the impact on the functionality of derived β-cell (psBC) progeny. A perifusion system revealed stepwise transduction of the PDX1, NEUROG3, and MAFA triad (PNM) enabled in vitro generation of psBCs with glucose and GLP-1 responsiveness within 3 weeks. PNM transduction upregulated genes associated with glucose sensing, insulin secretion, and β-cell maturation. In recipient diabetic mice, PNM-transduced psBCs showed glucose-responsive insulin secretion as early as 1 week post transplantation. Thus, enhanced pre-emptive β-cell specification of PSCs by PNM drives generation of glucose- and incretin-responsive psBCs in vitro, offering a competent tissue-primed biotherapy.

Hedgehog Interacting Protein (Hhip) Regulates Insulin Secretion in Mice Fed High Fat Diets

Hedgehog interacting protein (Hhip) is essential for islet formation and beta-cell proliferation during pancreatic development; abnormally elevated Hhip expression has been linked to human pancreatitis. Here, we investigate the role of Hhip in modulating insulin secretion in adult Hhip mice (Hhip +/− vs. Hhip+/+) fed high fat diets (HFD). Both sexes of HFD-Hhip +/+ mice developed impaired glucose intolerance, that was only ameliorated in male HFD-Hhip +/− mice that had high levels of circulating plasma insulin, but not in female HFD-Hhip +/− mice. HFD stimulated Hhip gene expression, mainly in beta cells. Male HFD-Hhip +/+ mice had more large islets in which insulin content was reduced; islet architecture was disordered; and markers of oxidative stress (8-OHdG and Nox 2) were increased. In contrast, male HFD-Hhip +/− mice had more small islets with increased beta cell proliferation, enhanced GSIS, less oxidative stress and preserved islet integrity. In vitro, recombinant Hhip increased Nox2 and NADPH activity and decreased insulin-positive beta cells. siRNA-Hhip increased GSIS and abolished the stimulation of sodium palmitate (PA)-BSA on Nox2 gene expression. We conclude that pancreatic Hhip gene inhibits insulin secretion by altering islet integrity and promoting Nox2 gene expression in beta cells in response to HDF-mediated beta cell dysfunction, a novel finding.

Impaired glucose tolerance, glucagon, and insulin responses in mice lacking the loop diuretic-sensitive Nkcc2a transporter.

The Na+K+2Cl- cotransporter-2 (Nkcc2, Slc12a1) is abundantly expressed in the kidney and its inhibition with the loop-diuretics bumetanide and furosemide has been linked to transient or permanent hyperglycemia in mice and humans. Notably, Slc12a1 is expressed at low levels in hypothalamic neurons and in insulin-secreting β-cells of the endocrine pancreas. The present study was designed to determine if global elimination of one of the Slc12a1 products, i.e., Nkcc2 variant a (Nkcc2a), the main splice version of Nkcc2 found in insulin-secreting β-cells, has an impact on the insulin and glucagon secretory responses and fuel homeostasis in vivo. We have used dynamic tests of glucose homeostasis in wild-type mice and mice lacking both alleles of Nkcc2a (Nkcc2aKO) and assessed their islet secretory responses in vitro. Under basal conditions, Nkcc2aKO mice have impaired glucose homeostasis characterized by increased blood glucose, intolerance to the sugar, delayed/blunted in vivo insulin and glucagon responses to glucose, and increased glycemic responses to the gluconeogenic substrate alanine. Further, we provide evidence of conserved quantitative secretory responses of Nkcc2aKO islets within a context of increased islet size related to hyperplastic/hypertrophic glucagon- and insulin-positive cells (α-cells and β-cells, respectively), normal total islet Cl- content, and reduced β-cell expression of the Cl- extruder Kcc2.

Pathogenesis of fulminant type1 diabetes: Genes, viruses and the immune mechanism, and usefulness of patient-derived induced pluripotent stem cells for future research.

We reviewed fulminant type 1 diabetes, a recently established subtype of type 1 diabetes, from the aspects of genes, viruses, immune mechanism and usefulness of patient‐derived induced pluripotent stem cells (iPSCs). In an analysis of the pancreas of patients with fulminant type 1 diabetes, viral antigens and viral receptors were expressed in β‐cells, as well as macrophages and T lymphocytes surrounding the β‐cells. These findings suggest that the β‐cells of patients with fulminant type 1 diabetes are destroyed during an immune response against viral infection of the pancreas. Recently, fulminant type 1 diabetes was induced by treatment with anti‐programmed cell death 1 antibodies, suggesting that immune regulatory mechanisms are also involved in the onset of this disease. We generated iPSCs from patients with fulminant type 1 diabetes for the first time. We also successfully differentiated patient‐derived iPSCs into insulin‐producing cells in vitro, and produced a disease model. The proportion of cytokine‐induced apoptotic cells among insulin‐positive cells was higher in the iPSCs from patients with fulminant type 1 diabetes than in iPSCs from healthy control participants. We carried out ribonucleic acid sequencing in insulin‐producing cells differentiated from patient‐derived iPSCs, and are now attempting to identify new biomarkers for the disease.

61-OR: ADA Presidents' Select Abstract: Characterization of Beta-Cell Function with Autoantibodies, Islet Pathology, and Genetics after 50 Years of Insulin Dependence

Characterization of persistent beta-cell function in response to metabolic stimuli with HLA and monogenic genotypes and pancreatic morphology in a large group of people with long duration of type 1 diabetes (T1D) has not been reported. In the Joslin Medalist Study (“Medalists”), which enrolled people with ≥50 years of T1D (n=1019), we determined whether significant associations exist between beta-cell function, autoantibodies (AAb), islet morphology, and genetic risks for T1D and monogenic diabetes. In this cohort, 32% exhibited C-peptide>0.05 ng/mL while 44% had GAD/IA2 AAb. In those with mixed meal tolerance test (MMTT, n=516), 6% responded with doubling of baseline C-peptide, without a related change in AAb status. Longitudinally (n=181, over a median of 4 years), C-peptide levels increased in 12% (n=22) and decreased in 37% (n=67). Among those with repeated MMTT, 5% (3/56) and 16% (9/56) had similar waxing and waning responses, respectively. Postmortem examination of 68 Medalist pancreases showed that all contained scattered insulin-positive cells, with three categories: A) only scattered singlets/doublets (n=9); B) scattered plus few insulin-positive cells in some islets (n=45); and C) scattered plus some lobes with islets having many insulin-positive cells (n=14). 30 Medalists with baseline C-peptide ≥0.1 ng/mL underwent a hyperglycemic/arginine clamp, to which 47% responded. Genetic screen for monogenic diabetes on all Medalists studied with the clamp showed 10 exhibiting monogenic variants, with HLA-/AAb- and HLA+/AAb- Medalists responding most to stimuli. In summary, these results show that all Medalists retained insulin-positive beta-cells, with many responding to metabolic stimuli even after 50 years of T1D. Medalists are heterogeneous with respect to beta-cell function and many with HLA+ diabetes risk alleles also have monogenic variants, indicating the importance of genetic testing for clinically-diagnosed T1D. Disclosure M. Yu: None. M.G. Pezzolesi: None. H.A. Keenan: Employee; Self; Sanofi Genzyme. D.M. Pober: None. Z. He: None. L.J. Tinsley: None. A. Doria: Research Support; Self; Sanofi-Aventis. S. Bonner-Weir: Advisory Panel; Spouse/Partner; Semma Therapeutics, Inc. G.L. King: Research Support; Self; Sanofi. Funding Nunnally Foundation; Beatson Pledge Fund; National Institute of Diabetes and Digestive and Kidney Diseases

273-OR: Intrapancreatic Adipose Tissue of Nondiabetic and Type 2 Diabetic Subjects and Relationships with Islet Morphometry

Little information is available on adipose tissue features in the human pancreas (AdTP). In the present study we performed morphologic and morphometric studies on AdTP of 9 overweight/obese nondiabetic (ND, age: 65±5 years; 4M/5F; BMI: 31.3±0.4 Kg/m2, mean±SEM) and 13 matched type 2 diabetic (T2D, age: 70±2 years, 8M/5F; BMI: 30.0±0.8 kg/m2) organ donors. Adipocytes were identified and quantified on a fluorescence DM5500 Leica microscope, using the MetaMorph v 1.8.0 software with a tresholded mask applied in exclusive mode. Macrophages were identified by immunohistochemistry using anti-CD68 (Dako) antibody. Assessment of insulin (Abcam Ab) and glucagon (Sigma Ab) positive cells was also performed. The number of adipocytes trended higher (+32.8%) in T2D (8.9±1.4/mm2) compared to ND (6.7±2.1/mm2) and their size was greater in T2D (9,319±1,028 μm2) than ND (5,639±639 μm2, p=0.01). AdTP area in relation to acinar tissue was 90.4% higher (p=0.07) in T2D (7.6±1.3%) than ND (3.9±1.5%). The amount of adipocytes with adjacent ≥ 3 CD68+ cells was higher (p=0.048) in T2D (31/281, 11%) than ND (7/147, 5%). Insulin positive area (T2D: 0.49±0.06%; ND: 0.55±0.09%) as well as glucagon positive area (T2D: 0.24±0.03%; ND: 0.32±0.07%) did not differ significantly between the two groups. Adipocyte size was negatively associated with islet number in ND+T2D (p=0.06) and positively with insulin area in ND (p=0.058); there was a significant, positive relationship between the amount of adipocytes and the number of islets in T2D (p=0.017). In conclusion, we found significant differences in the AdTP of T2D as compared to ND, including increased adypocite size and presence of adipocyte adjacent CD68+ cells; some of these parameters correlated with islet morphometric indices. Disclosure M. Suleiman: None. C. De Luca: None. P. De Simone: None. U. Boggi: None. F. Grano: None. M. Bugliani: None. P. Marchetti: None. L. Marselli: None. Funding Innovative Medicines Initiative 2 Joint Undertaking (115881); European Union; European Federation of Pharmaceutical Industries and Associations; Swiss State Secretariat for Education, Research and Innovation (16.0097-2)

Comparison of Glycemic Improvement Between Intermittent Calorie Restriction and Continuous Calorie Restriction in Diabetic Mice

Calorie restriction (CR) has been well proved to be a powerful tool to improve metabolic health associated with aging; and many types of CR have been proposed. Intermittent CR has become a trend in recent years due to its better compliance than continuous CR every day. However, there are few studies that directly compare the interventional efficacy of intermittent CR to continuous CR in metabolic disorders such as diabetes. In this study, we analyzed two regimes of intermittent CR with the calorie-matched continuous CR in two diabetic mouse models including db/db and streptozotocin-treated mice. Intermittent CR was carried out by a fasting-mimicking diet (FMD, with 30% calorie intake of the control per day) for 2 days or 5 days (i.e., 2-5 or 5-9 regimes followed by free eating for 5 or 9 days respectively). In the two diabetic mouse models, both intermittent CR and continuous CR significantly reduced fasting blood glucose level and improved insulin sensitivity. However, intermittent CR performed significantly better than continuous CR in improving glycemic control and insulin sensitivity in db/db mice. In addition, intermittent CR improved the glucose homeostasis of the db/db mice without causing loss of body weight. Analyses with the pancreatic islets reveal that intermittent CR profoundly elevated the number of insulin-positive cells in both diabetic mouse models. In conclusion, our study indicated that both intermittent CR and continuous CR can lower fasting blood glucose level in the diabetic mice, while intermittent CR is better than the latter in improving insulin sensitivity. Funding Statement: This study was supported by research grants from the National Natural Science Foundation of China (31630036 to Y.C.), the Ministry of Science and Technology of China (2016YFA0500103 to Y.C.), and the Chinese Academy of Sciences (XDA12010102, QYZDJ-SSW-SMC008, ZDRW-ZS-2016-8, and Y817X11141 to Y.C Declaration of Interests: The authors declare no conflict of interest. Ethics Approval Statement: The animal experiments were conducted in accordance with the guidelines of the Institutional Animal Care and Use Committee of the Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS) with an approval number 2010-AN-8.

Characteristic Localization of Neuronatin in Rat Testis, Hair Follicle, Tongue, and Pancreas.

Neuronatin (Nnat) is expressed in the pituitary, pancreas, and other tissues; however, the function of NNAT is still unclear. Recent studies have demonstrated that NNAT is localized in the sex-determining region Y-box 2-positive stem/progenitor cells in the developing rat pituitary primordium and is downregulated during differentiation into mature hormone-producing cells. Moreover, NNAT is widely localized in subcellular organelles, excluding the Golgi. Here, we further evaluated NNAT-positive cells and intracellular localization in embryonic and postnatal rat tissues such as the pancreas, tongue, whisker hair follicle, and testis. Immunohistochemistry revealed that NNAT was localized in undifferentiated cells (i.e., epithelial basal cells and basement cells in the papillae of the tongue and round and elongated spermatids of the testis) as well as in differentiated cells (insulin-positive cells and exocrine cells of the pancreas, taste receptor cells of the fungiform papilla, the inner root sheath of whisker hair follicles, and spermatozoa). In addition, NNAT exhibited novel intracellular localization in acrosomes in the spermatozoa. Because the endoplasmic reticulum (ER) is excluded from spermatozoa and sarco/ER Ca2+-ATPase isoform 2 (SERCA2) is absent from the inner root sheath, these findings suggested that NNAT localization in the ER and its interaction with SERCA2 are cell- or tissue-specific properties.

Interleukin-33 prevents the development of autoimmune diabetes in NOD mice

IL-33/ST2 signal is important for the generation of forkhead box P3 (Foxp3)+ regulatory (Treg) cells, which contribute to immune homeostasis in the context of diseases. The aim of this study was to determine whether targeting IL-33/ST2 signal could establish immunological tolerance and prevent type 1 diabetes (T1D) in nonobese diabetic (NOD) mice. Female NOD mice treated with IL-33 for 4 weeks decreased the incidence and delayed the onset of autoimmune diabetes, whereas IL-33 did not revert blood glucose concentration and disease development in mice with new-onset diabetes. IL-33 reduced immune cell infiltration, increased the number of insulin-positive islet cells, as well as increased antiapoptosis molecule Bcl2 and reduced proapoptosis molecules Caspase3 at mRNA levels in the pancreas. IL-33 increased the expression of phosphorylated-Akt and phosphorylated-PI3K in the pancreas. Systemic administration of IL-33 increased the number of CD4+CD25+Foxp3+Treg cells and induced expression of Treg cell-associated molecules ST2 and GATA3 in splenic lymphocytes, and increased Foxp3, Ctla4, and Gata3 at the -mRNA level in pancreatic lymph nodes of NOD mice. IL-33 signaling stimulated activation of phosphorylation of p44/42 (Erk) and p38 MAPK, as well as CD39 in the spleen. Our results showed that IL-33 prevents disease development in prediabetic NOD mice, and highlight IL-33/ST2 as a potential therapeutic target to prevent T1D.

The functional impact of G protein-coupled receptor 142 (Gpr142) on pancreatic \u03b2-cell in rodent

We have recently shown that the G protein-coupled receptor 142 (GPR142) is expressed in both rodent and human pancreatic β-cells. Herein, we investigated the cellular distribution of GPR142 within islets and the effects of selective agonists of GPR142 on glucose-stimulated insulin secretion (GSIS) in the mouse islets and INS-1832/13 cells. Double-immunostaining revealed that GPR142 immunoreactivity in islets mainly occurs in insulin-positive cells. Potentiation of GSIS by GPR142 activation was accompanied by increased cAMP content in INS-1832/13 cells. PKA/Epac inhibition markedly suppressed the effect of GPR142 activation on insulin release. Gpr142 knockdown (Gpr142-KD) in islets was accompanied by elevated release of MCP-1, IFNγ, and TNFα during culture period and abolished the modulatory effect of GPR142 activation on the GSIS. Gpr142-KD had no effect on Ffar1, Ffar2, or Ffar3 mRNA while reducing Gpr56 and increasing Tlr5 and Tlr7 mRNA expression. Gpr142-KD was associated with an increased expression of Chrebp, Txnip, RhoA, and mitochondrial Vdac1 concomitant with a reduced Pdx1, Pax6, and mitochondrial Vdac2 mRNA levels. Long-term exposure of INS-1832/13 cells to hyperglycemia reduced Gpr142 and Vdac2 while increased Chrebp, Txnip, and Vdac1 mRNA expression. GPR142 agonists or Bt2-cAMP counteracted this effect. Glucotoxicity-induced decrease of cell viability in Gpr142-KD INS-1 cells was not affected by GPR142-agonists while Bt2-cAMP prevented it. The results show the importance of Gpr142 in the maintenance of pancreatic β-cell function in rodents and that GPR142 agonists potentiate GSIS by an action, which most likely is due to increased cellular generation of second messenger molecule cAMP.

Treatment With Naringenin Elevates the Activity of Transcription Factor Nrf2 to Protect Pancreatic β-Cells From Streptozotocin-Induced Diabetes in vitro and in vivo.

Chronic hyperglycemia and unusually high oxidative stress are the key contributors for diabetes in humans. Since nuclear factor E2-related factor 2 (Nrf2) controls the expression of antioxidant- and detoxification genes, it is hypothesized that targeted activation of Nrf2 using phytochemicals is likely to protect pancreatic β-cells, from oxidative damage, thereby mitigates the complications of diabetes. Naringenin is one such activator of Nrf2. However, it is currently not known whether the protective effect of naringenin against streptozotocin (STZ) induced damage is mediated by Nrf2 activation. Hence, the potential of naringenin to activate Nrf2 and protect pancreatic β-cells from STZ-induced damage in MIN6 cells is studied. In MIN6 cells, naringenin could activate Nrf2 and its target genes GST and NQO1, thereby inhibit cellular apoptosis. In animals, administration of 50 mg/kg body weight naringenin, for 45 days, significantly decreased STZ-induced blood glucose levels, normalized the lipid profile, and augmented the levels of antioxidants in pancreatic tissues. Immunohistochemical analysis measuring the number of insulin-positive cells in pancreas showed restoration of insulin expression similar to control animals. Furthermore, naringenin promoted glycolysis while inhibiting gluconeogenesis. In conclusion, naringenin could be a good anti-diabetic agent, which works by promoting Nrf2 levels and by decreasing cellular oxidative stress.

Chemically defined conditions for long-term maintenance of pancreatic progenitors derived from human induced pluripotent stem cells

Large numbers of hormone-releasing cells, approximately 109 endocrine cells, are required to treat type I diabetes patients by cell transplantation. The SOX9-positive pancreatic epithelium proliferates extensively during the early stages of pancreatic development. SOX9-positive pancreatic epithelium is thought to be an expandable cell source of β cells for transplantation therapy. In this study, we attempted to expand pancreatic progenitors (PPs: PDX1+/SOX9+) derived from four human iPSC lines in three-dimensional (3D) culture using a chemically defined medium and examined the potential of the derived PPs to differentiate into β-like cells. PPs from four human iPSC lines were maintained and effectively proliferated in a chemically defined medium containing epidermal growth factor and R-spondin-1, CHIR99021, fibroblast growth factor-7, and SB431542. PPs derived from one iPSC line can be expanded by more than 104-fold in chemically defined medium containing two of the fives, epidermal growth factor and R-spondin-1. The expanded PPs were also stable following cryopreservation. After freezing and thawing, the PPs proliferated without a decrease in the rate. PPs obtained after 50 days of culture successfully differentiated into insulin-positive β-like cells, glucagon-positive α-like cells, and somatostatin-positive δ-like cells. The differentiation efficiency of expanded PPs was similar to that of PPs without expansion culture.

Therapeutic effects of ethanolic extract from the green cocoon shell of silkworm Bombyx mori on type 2 diabetic mice and its hypoglycaemic mechanism.

Diabetes mellitus is a clinically complex disease characterized by hyperglycaemia with disturbances in carbohydrate, fat and protein metabolism. The aim of this study was to determine the therapeutic effect of ethanolic extract (EE) from the green cocoon sericin layer of silkworm Bombyx mori on mice with type 2 diabetes mellitus (T2DM) and its hypoglycaemic mechanisms. The results showed that oral EE for 7 weeks had significant ameliorative effects on all the biochemical parameters studied in vivo. The levels of oral glucose tolerance and insulin tolerance were significantly improved. The hypoglycaemic rate in the 350 mg kg-1 high dosage group was 39.38%. The levels of nuclear factor kappa B (NFκB), interleukin 6 (IL-6) and tumour necrosis factor alpha (TNF-α) in the high dosage EE-treated group were significantly reduced, while activities of antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were obviously increased. The islet area and the number of insulin-positive beta cells increased significantly in the high dose group. Furthermore, expression levels of insulin receptor (IR), insulin receptor substrate (IRS), phosphatidylinositide 3-kinase (PI3K), p-Akt and phospho-glycogen synthase kinase-3β (p-GSK3β) involved in insulin signalling were increased. Adenosine 5'-monophosphate-activated protein kinase (AMPK) and glucose transporter 4 (GLUT4) also were activated to regulate glucose metabolism in EE-treated groups. The levels of glucose 6-phosphatase (G6pase) and phosphoenolpyruvate carboxykinase (PEPCK) decreased, while the glucokinase (GK) level increased to promote glycolysis. The results clearly indicated that oral EE, especially at a high dose, could improve the glucose metabolism of T2DM by reducing inflammatory reactions, enhancing the antioxidant capacity and insulin sensitivity, and regulating the balance between glycolysis and gluconeogenesis, which means that EE has potential ameliorative effects on T2DM mice.

Alpha-cells: Its Role as the Islet Harmonizer

It has long been thought that the alpha cells and its secretory products play an important role solely in maintaining euglycemia and preventing hypoglycemia through a contradictory action to the B cell’s insulin. The α-cell function is tightly regulated by various physiological inputs including systemic energy status, central and autonomic nervous systems, and the endocrine system. It is also an important amino acid sensor, glucagon blockade suppresses hepatic amino acid catabolism and increases the serum amino acid level. In addition to those controllers, the intra-islet microenvironment, where α-cells are located, has been recently revealed to be important in the regulation of the various cellular secretory functions including the overlapping of glucagon and insulin secretion through a precise cell-cell crosstalk. Paracrine interactions between pancreatic islet cells have been proposed as a mechanism to regulate hormone secretion and glucose homeostasis, alpha and B cells are closely positioned on the sides of their blood supply where acetylcholine acts as the paracrine communicator of signals inside the islets. Recently, it has been demonstrated that blocking acetylcholine esterase increases insulin secretion. Moreover, it has also been suggested that glucagon is not exclusively a counter-regulatory hormone that elevates blood glucose levels, in contrast it can cause hypoglycemia conditioned by the presence of intact B cells and a functional GLP-1R (glucagon-like peptide 1 receptor). These data argue for glucagon agonism in modern management of T2DM. Alpha-cells also, have been shown to be able to trans-differentiate into β-cells only in the presence of insulin-positive cells with α-cell origin in the lineage tracing analyses, confirming the role of α-cells as a source of β-cell regeneration. The article reviews the updated knowledge about the functions of the alpha-cells and its role in the paracrine control of islet cell secretions and the future therapeutic potentials.

Repercussions of low fructose-drinking water in male rats.

Fructose consumption has increased worldwide, and it has been associated with the development of metabolic diseases such as insulin resistance (IR) and steatosis. The aim was to evaluate if lower fructose concentrations may cause pancreatic structural abnormalities, leading to a glucose intolerance without steatosis in male rats. Young male rats orally received 7% fructose solution for 12 weeks. Body weight, food, water, and energy intake were measured. An oral glucose tolerance test (OGTT) was performed. After final experimental period, all rats were anaesthetized and killed. Blood samples were collected for biochemical analyses and organs (liver and pancreas) were processed for morphological analyses. Fructose consumption was not associated with lipid accumulation in liver. However, fructose administration was associated with an increased area under curve from OGTT and an increased percentage of insulin-positive cells, high beta cell mass and reduced pancreatic islet area. Fructose supplementation (7%) did not cause steatosis, but it led to abnormal morphology and function of pancreatic islet cells, contributing for glucose intolerance development. Our findings demonstrate that even low fructose concentrations may cause deleterious effects in animals.

In Vitro Generation of Glucose-Responsive Insulin-Secreting Cells from PDX1-Overexpressing Human-Induced Pluripotent Stem Cell Derived from Diabetic Patient.

Pancreatic and duodenal homeobox 1 (PDX1), a member of the homeodomain-containing transcription factor family, is a key transcription factor for pancreas development and mature β-cell function. In this study, induced overexpression of PDX1 resulted in producing susceptible cells for pancreatic differentiation and was well beneficial to enhance β-cell production, maturation, function, and survival. Induced PDX1 overexpression in harmony with a set of signaling molecules involves in guiding the signaling pathways toward pancreas development, leaded to high-efficient in vitro generation of ectopic insulin-producing cells (IPCs) with the effectively reduced number of polyhormonal cells and increased number of insulin (INS) single-positive cells. This strategy yielded 85.61% glucose-responsive insulin-positive cells in vitro, which was seven times higher than the basal level, and electron microscopy images revealed the presence of mature β-cell secretory granules. The generation of glucose-responsive insulin-secreting β-like cells from human-induced pluripotent stem cells (hiPSCs) in vitro would provide a promising approach to produce an unprecedented cell source for cell transplantation therapy in diabetes without the ethical obstacle of embryonic stem cells and would bypass immune rejection. These cells are an invaluable source for disease modeling, drug discovery, and pharmacogenomics studies as well.

Generation of functional human pancreatic organoids by transplants of embryonic stem cell derivatives in a 3D-printed tissue trapper.

Organoids can be regarded as a beneficial tool for discovery of new therapeutics for diabetes and/or maturation of pancreatic progenitors (PP) towards β cells. Here, we devised a strategy to enhance maturation of PP by assembly of three-dimensional (3D) pancreatic organoids (PO) containing human embryonic stem (ES) cell derivatives including ES-derived pancreatic duodenal homeobox 1 (PDX1) + early PP, mesenchymal stem cells, and endothelial cells at an optimized cell ratio, on Matrigel. The PO was placed in a 3D-printed tissue trapper and heterotopically implanted into the peritoneal cavity of immunodeficient mice where it remained for 90 days. Our results indicated that, in contrast to corresponding early PP transplants, 3D PO developed more vascularization as indicated by greater area and number of vessels, a higher number of insulin-positive cells and improvement of human C-peptide secretions. Based on our findings, PO-derived β cells could be considered a novel strategy to study human β-cell development, novel therapeutics, and regenerative medicine for diabetes.

PDL1 is expressed in the islets of people with type 1 diabetes and is up-regulated by interferons-α and-γ via IRF1 induction.

BackgroundAntibodies targeting PD-1 and its ligand PDL1 are used in cancer immunotherapy but may lead to autoimmune diseases, including type 1 diabetes (T1D). It remains unclear whether PDL1 is expressed in pancreatic islets of people with T1D and how is it regulated.MethodsThe expression of PDL1, IRF1, insulin and glucagon was evaluated in samples of T1D donors by immunofluorescence. Cytokine-induced PDL1 expression in the human beta cell line, EndoC-βH1, and in primary human pancreatic islets was determined by real-time RT-PCR, flow cytometry and Western blot. Specific and previously validated small interference RNAs were used to inhibit STAT1, STAT2, IRF1 and JAK1 signaling. Key results were validated using the JAK inhibitor Ruxolitinib.FindingsPDL1 was present in insulin-positive cells from twelve T1D individuals (6 living and 6 deceased donors) but absent from insulin-deficient islets or from the islets of six non-diabetic controls. Interferons-α and -γ, but not interleukin-1β, induced PDL1 expression in vitro in human islet cells and EndoC-βH1 cells. Silencing of STAT1 or STAT2 individually did not prevent interferon-α-induced PDL1, while blocking of JAKs – a proposed therapeutic strategy for T1D – or IRF1 prevented PDL1 induction.InterpretationThese findings indicate that PDL1 is expressed in beta cells from people with T1D, possibly to attenuate the autoimmune assault, and that it is induced by both type I and II interferons via IRF1.