Preserved Insulin Secretion Research Articles

The Dual Amylin and Calcitonin Receptor Agonist, KBP-066, Induces an Equally Potent Weight Loss Across a Broad Dose Range While Higher Doses May Further Improve Insulin Action.

Pharmacological treatment with dual amylin and calcitonin receptor agonists (DACRAs) cause significant weight loss and improvement of glucose homeostasis. In this study, the maximally efficacious dose of the novel DACRA, KeyBiosciencePeptide (KBP)-066, was investigated. Two different rat models were used: high-fat diet (HFD)-fed male Sprague-Dawley rats and male Zucker diabetic fatty (ZDF, fa/fa) rats to determine the maximum weight loss and glucose homeostatic effect, respectively. One acute study and one chronic study was performed in HFD rats. Two chronic studies were performed in ZDF rats: a preventive and an interventive. All studies covered a dose range of 5, 50, and 500 µg/kg KBP-066 delivered by subcutaneous injection. Treatment with KBP-066 resulted in a significant weight reduction of 13%-16% and improved glucose tolerance in HFD rats, which was independent of dose concentration. Dosing with 50 and 500 µg/kg led to a transient but significant increase in blood glucose, both in the acute and the chronic study in HFD rats. All doses of KBP-066 significantly improved glucose homeostasis in ZDF rats, both in the preventive and interventive study. Moreover, dosing with 50 and 500 µg/kg preserved insulin secretion to a greater extent than 5 µg/kg when compared with ZDF vehicle rats. Taken together, these results show that maximum weight loss is achieved with 5 µg/kg, which is within the range of previously reported DACRA dosing, whereas increasing dosing concentration to 50 and 500 µg/kg may further improve preservation of insulin secretion compared with 5 µg/kg in diabetic ZDF rats. SIGNIFICANCE STATEMENT: Here we show that KeyBiosciencePeptide (KBP)-066 induces an equally potent body weight loss across a broad dose range in obese rats. However, higher dosing of KBP-066 may improve insulin action in diabetic rats both as preventive and interventive treatment.

Metabolic bone markers can be related to preserved insulin secretion in children with newly diagnosed type 1 diabetes.

Type 1 diabetes (T1D) may be associated with numerous complications including bone metabolism disorders. The aim of the study was to evaluate the bone metabolism markers twice in children with a newly diagnosed T1D and after an average of seven months of its duration in relation to parameters of the clinical course of diabetes. In 100 T1D patients and 52 control subjects, the following bone turnover markers were evaluated: osteocalcin - OC, osteoprotegerin - OPG, sRANKL, and deoxypyridoline in urine - DPD and DXA examination was also performed. Lower OC concentration at T1D onset in comparison to controls (p < 0.001) and its increase during follow-up (p < 0.001) was ob-served. The OPG concentration was elevated at T1D onset as compared to the control group (p = 0.024) and decreased thereafter (p < 0.001). The s-RANKL level increased during follow-up (p < 0.001) and was lower than in controls (p < 0.001). Urine DPD con-centration also increased during follow-up in the T1D patient group (p < 0.001) and was higher in comparison to the control group (p = 0.021). BMD-TBLH was higher in the control group as compared to patients both at T1D onset (p = 0.025) and in follow-up ob-servation (p = 0.034). Moreover, OPG correlated positively with glycated haemoglobin (HbA1c) (p = 0.004) and negatively with fasting C-peptide level (p = 0.046) and BMI Z-score (p = 0.003), whereas s-RANKL correlated positively with both fasting (p < 0.001) and stimulated C-peptide levels (p < 0.001). Bone metabolism disorders observed at T1D onset in children and modified after reaching the metabolic control of the disease seem to be most strongly associated with preserved insulin secretion.

2135-P: Genetic Ablation of CB1R Protects against Streptozotocin-Induced ß-Cell Destruction in Mice

Approximately 1.25 million Americans have type 1 diabetes mellitus (T1DM), resulting from β-cell destruction. There is no known way to prevent it or to stop destruction of any remaining β-cells. Although the cannabinoid system, specifically cannabinoid 1 receptor (CB1R), is implicated in obesity and T2DM, its role, if any, in T1DM has not been studied. To address this, we induced β-cell destruction in wild type mice (WT: n=8) and mice in which CB1R was genetically nullified in β-cells only (β-CB1R-/-: n=8) in adulthood by five injections of streptozotocin (50 mg/kg intraperitoneally [IP]), a toxin selective for β-cells. We found that β-CB1R-/- mice had random blood glucose (BG) levels in the range of 137-289 mg/dL throughout the study period (28 days) as well as preserved insulin secretion with superior glucose tolerance after IP glucose (2g/kg) at day 8, 15 or 27, relative to their (random BG 500-600 mg/dL) WT littermates. CB1R knockout drove significant increases in pancreatic islet autophagic activity based on increased accumulation of autophagosome hallmarks (LC3B, Beclin-1, ATG5 and ATG7) and reduced p62 expression. Insulin and LC3B were colocalized in CB1R-deficient β-cells. Remarkably, the islets did not show the upregulation of ER unfolded protein response, which was present in β-cells of WT mice, while exerting the induction of protective chaperones. These anti-stress functions were accompanied by increased phosphorylation of AKT (ser) 473 and ERK in β-cells, which reveals a previously unrecognized route for PI3K-AKT pathway to activate the anti-apoptotic NFkB/p65 signaling that coordinately is permissive to β-cell survival. We conclude that CB1R nullification restores autophagy machinery as a novel signaling pathway to counteract ER stress-mediated cell death and confers resistance to β-cell destruction. We propose that CB1R is a potential therapeutic target during the honeymoon phase of T1DM. Disclosure K. Aseer: None. J.M. Egan: None.

59-OR: Liraglutide Preserved Insulin Secretion in Adults with Newly Diagnosed Type 1 Diabetes: The NewLira Trial

Glucagon-like peptide-1 (GLP-1) stimulates insulin secretion in adults with type 1 diabetes and residual beta-cell function. This randomized, double-blind, placebo-controlled, 52-week trial evaluated the efficacy of liraglutide 1.8 mg QD added to insulin treatment in adults diagnosed with type 1 diabetes within 6 weeks prior to screening. At randomization, at end-of-treatment (week 52) and at follow-up (week 58), a 240-min. liquid mixed meal test (237 kcal Nestlé BOOST) was conducted to evaluate the C-peptide response. In total, 65 adults (age 18-40 years) with newly diagnosed type 1 diabetes, stimulated C-peptide ≥200 pmol/L and BMI &amp;gt;20 kg/m2 were randomized (1:1) to liraglutide or placebo added to insulin treatment. Baseline characteristics were similar between groups (mean±SD) age 27±5 years, fasting C-peptide 359±226 pM and diabetes duration 4.4±1.2 weeks. At end-of-treatment, liraglutide sustained stimulated C-peptide secretion and reduced insulin dose compared with placebo (Table). At 6 weeks post-treatment, stimulated C-peptide levels and total insulin dose did not differ between the groups. No difference was found between groups in HbA1c or BMI (Table). No events of severe hypoglycemia or ketoacidosis were reported. In conclusion, liraglutide preserved postprandial insulin secretion one year after diagnosis of type 1 diabetes. The effects had disappeared 6 weeks post-treatment. Disclosure T.F. Dejgaard: Consultant; Self; Novo Nordisk A/S. Research Support; Self; AstraZeneca, Novo Nordisk A/S. Speaker's Bureau; Self; Boehringer Ingelheim International GmbH. C.S. Frandsen: None. U. Kielgast: Advisory Panel; Self; Novo Nordisk A/S. Consultant; Self; Eli Lilly and Company, Sanofi. H.U. Andersen: Advisory Panel; Self; Abbott Laboratories, AstraZeneca, Novo Nordisk A/S. Speaker's Bureau; Self; Nordic Infucare. Stock/Shareholder; Self; Novo Nordisk Inc. B. Thorsteinsson: None. T. Krarup: None. J.J. Holst: Advisory Panel; Self; Novo Nordisk A/S. S. Madsbad: None. Funding Novo Nordisk

2016-P: High Dose DACRA Treatment Improves Glucose Homeostasis, without Additional Weight Loss

KBP is a Dual Amylin and Calcitonin Receptor Agonist (DACRA). DACRAs have shown efficacy on weight loss and glucose control in rats. However, it is unclear whether the maximum effect has been reached. High Fat Diet (HFD, 60% fat) fed male Sprague-Dawley rats entered a dose escalation regimen ending at 5 (normal dose), 50 or 500 µg/kg daily KBP (n=10/group). Male ZDF (fa/fa) rats received identical doses without dose escalation in a preventive study setup (n=9-10/group). In HFD rats, KBP treatment resulted in a transient decrease in food intake at each dose escalation step. At study end, KBP treatment resulted in a significant weight loss of 77-94 g (13-16%, P&amp;lt;0.0001) compared to vehicle. Furthermore, KBP reduced the weight of adipose tissues (P&amp;lt;0.05). Surprisingly, there was a trend of 5 µg/kg KBP causing a more pronounced adipose-specific weight loss compared to 500 µg/kg (subcutaneous 1.7 vs. 0.7 g, visceral 4.1 vs. 2.5 g adipose weight loss). During two OGTTs, KBP treatment significantly lowered blood glucose (BG) and insulin levels compared to vehicle indicating improved glucose tolerance. Lastly, 24h fecal energy loss increased by KBP treatment, though this trend was absent when accounting for food intake and total feces output. In ZDF rats, KBP treatment significantly improved fasting BG (endpoint vehicle 29.5, endpoint KBP average 18.3 mmol/L, tAUC P&amp;lt;0.0001) and HbA1c (vehicle 10.2%, KBP average 6.1%, P&amp;lt;0.0001) compared to vehicle, with no significant difference between treatment groups. Importantly, fasting and non-fasting insulin levels of KBP-treated rats were increased compared to vehicle in a dose-dependent manner during an OGTT, resulting in lowered BG levels. Increased insulin levels suggest that KBP protects against the known β-cell degradation in the ZDF model. Taken together, these data suggest that higher doses of KBP than previously investigated may preserve insulin secretion to a greater extent. With respect to weight loss, no additional benefit was observed from the high doses. Disclosure N. Sonne: None. A.T. Larsen: None. K.V. Andreassen: Employee; Self; Nordic Bioscience. M.A. Karsdal: Employee; Self; Nordic Bioscience. K. Henriksen: Employee; Self; Nordic Bioscience. Employee; Spouse/Partner; Novo Nordisk A/S. Stock/Shareholder; Self; Nordic Bioscience. Other Relationship; Self; Nordic Bioscience.

Preserving β-cell function is the major determinant of diabetes remission following laparoscopic sleeve gastrectomy in Japanese obese diabetic patients

Laparoscopic sleeve gastrectomy has been proven effective in treating obesity-associated type 2 diabetes mellitus (T2DM). However, reports of the effect of laparoscopic sleeve gastrectomy on glucose metabolism in Japanese obese patients with T2DM are rare. The aim of this study was to evaluate the effects of laparoscopic sleeve gastrectomy on glucose tolerance in Japanese obese patients with T2DM, and to analyze factors influencing diabetes remission after surgery. This was a retrospective analysis of data for 24 consecutive patients with T2DM who underwent laparoscopic sleeve gastrectomy. We investigated weight loss and its impact on T2DM 1 year postoperatively. We also compared baseline characteristics and postoperative factors between patients who achieved diabetes remission and patients without remission. Mean body weight loss and percent total weight loss were 23.9 kg and 23.3%, respectively. Mean hemoglobin A1c levels dropped from 7.3 ± 0.3% to 6.1 ± 0.2%, and 18 patients (75%) achieved diabetes remission 1 year postoperatively. Patients achieving remission had significantly lower hemoglobin A1c levels (p = 0.026), higher fasting C-peptide values (p < 0.001), shorter diabetes duration (p < 0.001), lower insulin requirement (p = 0.002), and higher area under the insulin response curve (p < 0.001) and insulinogenic index (p < 0.001) during oral glucose tolerance testing. In conclusion, laparoscopic sleeve gastrectomy is an effective treatment for Japanese obese patients with T2DM. Preserving insulin secretion is the major determinant of diabetes remission.

Exendin-4 overcomes cytokine-induced decreases in gap junction coupling via protein kinase A and Epac2 in mouse and human islets.

The pancreatic islets of Langerhans maintain glucose homeostasis through insulin secretion, where insulin secretion dynamics are regulated by intracellular Ca2+ signalling and electrical coupling of the insulin producing β-cells in the islet. We have previously shown that cytokines decrease β-cell coupling and that compounds which increase cAMP can increase coupling. In both mouse and human islets exendin-4, which increases cAMP, protected against cytokine-induced decreases in coupling and in mouse islets preserved glucose-stimulated calcium signalling by increasing connexin36 gap junction levels on the plasma membrane. Our data indicate that protein kinase A regulates β-cell coupling through a fast mechanism, such as channel gating or membrane organization, while Epac2 regulates slower mechanisms of regulation, such as gap junction turnover. Increases in β-cell coupling with exendin-4 may protect against cytokine-mediated β-cell death as well as preserve insulin secretion dynamics during the development of diabetes. The pancreatic islets of Langerhans maintain glucose homeostasis. Insulin secretion from islet β-cells is driven by glucose metabolism, depolarization of the cell membrane and an influx of calcium, which initiates the release of insulin. Gap junctions composed of connexin36 (Cx36) electrically couple β-cells, regulating calcium signalling and insulin secretion dynamics. Cx36 coupling is decreased in pre-diabetic mice, suggesting a role for altered coupling in diabetes. Our previous work has shown that pro-inflammatory cytokines decrease Cx36 coupling and that compounds which increase cAMP can increase Cx36 coupling. The goal of this study was to determine if exendin-4, which increases cAMP, can protect against cytokine-induced decreases in Cx36 coupling and altered islet function. In both mouse and human islets, exendin-4 protected against cytokine-induced decreases in coupling and preserved glucose-stimulated calcium signalling. Exendin-4 also protected against protein kinase Cδ-mediated decreases in Cx36 coupling. Exendin-4 preserved coupling in mouse islets by preserving Cx36 levels on the plasma membrane. Exendin-4 regulated Cx36 coupling via both protein kinase A (PKA)- and Epac2-mediated mechanisms in cytokine-treated islets. In mouse islets, modulating Epac2 had a greater impact in mediating Cx36 coupling, while in human islets modulating PKA had a greater impact on Cx36 coupling. Our data indicate that PKA regulates Cx36 coupling through a fast mechanism, such as channel gating, while Epac2 regulates slower mechanisms of regulation, such as Cx36 turnover in the membrane. Increases in Cx36 coupling with exendin-4 may protect against cytokine-mediated β-cell dysfunction to insulin secretion dynamics during the development of diabetes.

Is Absence of Carbohydrate Metabolism Disorders in Patients with Prolonged History of Obesity due to Low Insulin Resistance or Preserved Insulin Secretion?

Background: At present a lot of attention is paid to the so-called “metabolically healthy obesity”. More than a half of patients with prolonged history of obesity lack any carbohydrate metabolism disorders. Unfortunately, physiological factors forming the foundation of a favorable metabolic profile in such patients are not sufficiently defined. Aims: Evaluation of insulin resistance (IR) degree, the level of insulin secretion by pancreatic β-cells, and the contribution of both these mechanisms to the maintenance of normal carbohydrate metabolism in patients with prolonged history of obesity. Methods: An observational cross-sectional non-blinded selective comparative case-control study was performed. Patients with prolonged history of obesity without carbohydrate metabolism disorders and with type 2 diabetes mellitus (DM2) were included into the study. The following parameters were analyzed: IR parameters (М-index, HOMA-IR); insulin secretion parameters (НОМА-%β and insulinogenic index, glucose disposition index, GDI); body composition indices (total body fat and visceral fat area). Results: 68 patients participated in the study: 34 patients with obesity and normal carbohydrate metabolism («Obesity and NCM» group), and 34 patients with obesity and DM2 («Obesity and DM2» group); both groups were matched by body mass index, known obesity duration, and sex ratio (males/females) in each group. «Obesity and NCM» groups significantly differed from «Obesity and DM2» group by the following parameters: lower IR level (М-index median 4.13 vs 1.52 mg/kg/min, p0.001; HOMA-IR median 4.84 vs 9.94, p0.001); better insulin secretion (insulinogenic index median 28.15 vs 15.24, p0.002; HOMA-%β median 115.63 vs 25.94, p0.001); higher GDI (median 115.63 vs 25.94, p0.001); lower visceral fat area (median 170.00 vs 230.00 cm2, p0.001). Differences in total body fat (%) were not statistically significant. Conclusions: Patients with obesity and NCM compared to patients with DM2 have a less significant IR and a more preserved basal stimulated insulin secretion, which allows to maintain normal carbohydrate metabolism. Low visceral fat grade also contributes to this. Most likely, the most important factor contributing to the “maintenance” of normal carbohydrate metabolism in patients with obesity is preserved insulin secretion, which is confirmed by the high glucose disposal index (almost 4.5-fold higher than that in patients with DM2) characterizing the ability of β-cells to secrete the amount of insulin required to overcome IR.

Preserving Insulin Secretion in Diabetes by Inhibiting VDAC1 Overexpression and Surface Translocation in β Cells

SummaryType 2 diabetes (T2D) develops after years of prediabetes during which high glucose (glucotoxicity) impairs insulin secretion. We report that the ATP-conducting mitochondrial outer membrane voltage-dependent anion channel-1 (VDAC1) is upregulated in islets from T2D and non-diabetic organ donors under glucotoxic conditions. This is caused by a glucotoxicity-induced transcriptional program, triggered during years of prediabetes with suboptimal blood glucose control. Metformin counteracts VDAC1 induction. VDAC1 overexpression causes its mistargeting to the plasma membrane of the insulin-secreting β cells with loss of the crucial metabolic coupling factor ATP. VDAC1 antibodies and inhibitors prevent ATP loss. Through direct inhibition of VDAC1 conductance, metformin, like specific VDAC1 inhibitors and antibodies, restores the impaired generation of ATP and glucose-stimulated insulin secretion in T2D islets. Treatment of db/db mice with VDAC1 inhibitor prevents hyperglycemia, and maintains normal glucose tolerance and physiological regulation of insulin secretion. Thus, β cell function is preserved by targeting the novel diabetes executer protein VDAC1.

Preserved insulin secretion and kidney function in recipients with functional pancreas grafts 1 year after transplantation: a single-center prospective observational study

Successful simultaneous pancreas and kidney transplantation (SPK) or pancreas transplantation alone (PTA) restores glycemic control. Diabetes and impaired kidney function are common side effects of immunosuppressive therapy. This study addresses glucometabolic parameters and kidney function during the first year. We examined 67 patients with functioning grafts (SPK n = 30, PTA n = 37) transplanted between September 2011 and November 2016 who underwent repeated oral glucose tolerance tests (OGTTs) 8 and 52 weeks after transplantation. Another 19 patients lost their graft the first year post-transplant and 28 patients did not undergo repeated OGTTs and could not be studied. All patients received ATG induction therapy plus tacrolimus, mycophenolate and prednisolone. Glomerular filtration rate was measured before and 8 and 52 weeks after transplantation by serum clearance methods. From week 8 to 52 after transplantation, mean fasting glucose decreased (SPK: 5.4 ± 0.7 to 5.1 ± 0.8 mmol/L, PTA: 5.4 ± 0.6 to 5.2 ± 0.7 mmol/L; both P < 0.05), and also 120-min post-OGTT glucose (SPK: 6.9 ± 2.9 to 5.7 ± 2.2 mmol/L; P = 0.07, PTA: 6.5 ± 1.7 to 5.7 ± 1.2 mmol/L; P < 0.05). Fasting C-peptide levels also decreased (SPK: 1500 ± 573 to 1078 ± 357 pmol/L, PTA: 1210 ± 487 to 1021 ± 434 pmol/L, both P < 0.005). Measured GFR decreased from enlistment to 8 weeks post transplant in PTA patients (94 ± 22 to 78 ± 19 mL/min/1.73 m2; P < 0.005), but did not deteriorate from week 8 to week 52 (SPK: 55.0 ± 15.1 vs 59.7 ± 11.3 ml/min/1.73 m²; P = 0.19, PTA: 76 ± 19 vs 77 ± 19 mL/min/1.73 m²; P = 0.74). Glycemic control and kidney function remain preserved in recipients with functioning SPK and PTA grafts 1 year after transplantation.

Delivery of shRNA via lentivirus in human pseudoislets provides a model to test dynamic regulation of insulin secretion and gene function in human islets.

sRodent islets are widely used to study the pathophysiology of beta cells and islet function, however, structural and functional differences exist between human and rodent islets, highlighting the need for human islet studies. Human islets are highly variable, deteriorate during culture, and are difficult to genetically modify, making mechanistic studies difficult to conduct and reproduce. To overcome these limitations, we tested whether pseudoislets, created by dissociation and reaggregation of islet cell suspensions, allow for assessment of dynamic islet function after genetic modulation. Characterization of pseudoislets cultured for 1 week revealed better preservation of first‐phase glucose‐stimulated insulin secretion (GSIS) compared with cultured‐intact islets and insulin secretion profiles similar to fresh islets when challenged by glibenclamide and KCl. qPCR indicated that pseudoislets are similar to the original islets for the expression of markers for cell types, beta cell function, and cellular stress with the exception of reduced proinflammatory cytokine genes (IL1B, CCL2, CXCL8). The expression of extracellular matrix markers (ASPN, COL1A1, COL4A1) was also altered in pseudoislets compared with intact islets. Compared with intact islets transduced by adenovirus, pseudoislets transduced by lentivirus showed uniform transduction and better first‐phase GSIS. Lastly, the lentiviral‐mediated delivery of short hairpin RNA targeting glucokinase (GCK) achieved significant reduction of GCK expression in pseudoislets as well as marked reduction of both first and second phase GSIS without affecting the insulin secretion in response to KCl. Thus, pseudoislets are a tool that enables efficient genetic modulation of human islet cells while preserving insulin secretion.

Microglia Activation Regulates Systemic Glucose Tolerance

Obesity and high fat diet (HFD) consumption in rodents is associated with hypothalamic inflammation and activation of microglia, the resident CNS immune cells. Recently, we provided evidence that microglia are critical intermediary cells that transmit the inflammatory signal induced by HFD exposure. Mice with a conditional knockout of IKKb specifically in microglia (CX3CR1CreERT2 x IKKbeta fl/fl, MGKO) have reduced susceptibility to HFD-associated hyperphagia and DIO compared with IKKb fl/fl littermate controls (Ctl). Surprisingly, despite their reduced fat mass, HFD-fed MGKO mice have equal glucose intolerance to Ctls as well as no improvement in white adipose tissue inflammation or hepatic triglyceride content. Together these data suggest dissociation between microglial regulation of energy and glucose homeostasis. To address this possibility, we pair-fed MGKO mice to Ctl mice, resulting in matched body weights during HFD feeding. Pair-fed MGKO mice showed a greater degree of impairment in glucose tolerance and insulin sensitivity with preserved insulin secretion compared to controls. Similarly, chemical inactivation of microglia using centrally-administered minocycline worsens insulin sensitivity in HFD-fed rats. Finally, using several distinct genetic models, we show that microglial activation acutely improves glucose tolerance and insulin sensitivity. Together, these data reveal a novel aspect of CNS regulation of metabolism in which microglial inflammatory activation promotes HFD overconsumption and weight gain but offsets obesity-associated dysregulation of glucose homeostasis. These results indicate the need for pathway-specific targeting to develop glial-based therapeutics for obesity and diabetes. Disclosure J. Douglass: None. M. Valdearcos: None. S.K. Koliwad: None. J. Thaler: Research Support; Self; Novo Nordisk A/S.

Melatonin attenuates smoking-induced hyperglycemia via preserving insulin secretion and hepatic glycogen synthesis in rats.

Epidemiology survey indicated that cigarette smoking is a risk factor of diabetes. However, the precise mechanisms remain to be clarified. In this study, we found that smoking caused metabolic malfunctions on pancreas and liver in experimental animal model. These were indicated by hyperglycemia, increased serum hemoglobin A1c level and decreased insulin secretion, inhibition of liver glycogen synthase (LGS), and hepatic glycogen synthesis. Mechanistic studies revealed that all these alterations were caused by the inflammatory reaction and reactive oxygen species (ROS) induced by the smoking. Melatonin treatment significantly preserved the functions of both pancreas and liver by reducing β cell apoptosis, CD68‐cell infiltration, ROS production, and caspase‐3 expression. The siRNA‐knockdown model identified that the protective effects of melatonin were mediated by melatonin receptor‐2 (MT2). This study uncovered potentially underlying mechanisms related to the association between smoking and diabetes. In addition, it is, for first time, to report that melatonin effectively protects against smoking‐induced glucose metabolic alterations and the signal transduction pathway of melatonin is mainly mediated by its MT2 receptor. These observations provide solid evidence for the clinically use of melatonin to reduce smoking‐related diabetes, and the therapeutic regimens are absent currently.

Estrogen receptor α protects pancreatic β-cells from apoptosis by preserving mitochondrial function and suppressing endoplasmic reticulum stress

Estrogen receptor α (ERα) action plays an important role in pancreatic β-cell function and survival; thus, it is considered a potential therapeutic target for the treatment of type 2 diabetes in women. However, the mechanisms underlying the protective effects of ERα remain unclear. Because ERα regulates mitochondrial metabolism in other cell types, we hypothesized that ERα may act to preserve insulin secretion and promote β-cell survival by regulating mitochondrial-endoplasmic reticulum (EndoRetic) function. We tested this hypothesis using pancreatic islet-specific ERα knockout (PERαKO) mice and Min6 β-cells in culture with Esr1 knockdown (KD). We found that Esr1-KD promoted reactive oxygen species production that associated with reduced fission/fusion dynamics and impaired mitophagy. Electron microscopy showed mitochondrial enlargement and a pro-fusion phenotype. Mitochondrial cristae and endoplasmic reticulum were dilated in Esr1-KD compared with ERα replete Min6 β-cells. Increased expression of Oma1 and Chop was paralleled by increased oxygen consumption and apoptosis susceptibility in ERα-KD cells. In contrast, ERα overexpression and ligand activation reduced both Chop and Oma1 expression, likely by ERα binding to consensus estrogen-response element sites in the Oma1 and Chop promoters. Together, our findings suggest that ERα promotes β-cell survival and insulin secretion through maintenance of mitochondrial fission/fusion-mitophagy dynamics and EndoRetic function, in part by Oma1 and Chop repression.

Duodenal Exclusion but Not Sleeve Gastrectomy Preserves Insulin Secretion, Making It the More Effective Metabolic Procedure

There is an ongoing debate on which procedure provides the best treatment for type 2 diabetes. Furthermore, the pathomechanisms of diabetes improvement of partly anatomically differing operations is not fully understood. A loop duodenojejunostomy (DJOS) with exclusion of one third of intestinal length, a sleeve gastrectomy (SG), or a combination of DJOS + SG was performed in 8-week-old male ZDF rats. One, three, and six months after surgery, an oral glucose tolerance test and measurements of GLP-1, GIP, insulin, and bile acids were conducted. After an initial (4weeks) equal glucose control, DJOS and DJOS + SG showed significantly lower glucose levels than SG 3 and 6months after surgery. There was sharp decline of insulin levels in SG animals over time, whereas insulin levels in DJOS and DJOS + SG were preserved. GIP levels were significantly larger in both groups containing a sleeve at all three time points, whereas GLP-1 was equal in all groups at all time. Bile acid levels were significantly higher in the DJOS compared to the SG group at all time points. Interestingly, the additional SG in the DJOS + SG group led to lower bile acid levels 1 and 6months postoperatively. The effect of SG on glucose control was transient, whereas a duodenal exclusion was the more effective procedure in this model due to a sustained pancreatic function with a preserved insulin secretion.

Decline in the acute insulin response in relationship to plasma glucose concentrations.

To investigate (1) whether the decline in acute insulin response (AIR) precedes or coincides with defined glucose regulation categories and whether acute insulin response decline varies by race and adiposity, (2) linearity of the relationship between acute insulin response and increasing plasma glucose concentrations, (3) longitudinal changes in acute insulin response accounting for changes in insulin action across categories of glucose tolerance. Clinical cross-sectional and longitudinal study of nondiabetic subjects. Inpatient assessment of oral glucose tolerance (2-h PG, fasting PG), and acute insulin response (intravenous glucose tolerance test) in 326 and 84 Native Americans of full and ≤6/8th Southwestern heritage, respectively, and 115 Whites. Linearity of acute insulin response vs plasma glucose concentrations investigated using spline analyses. Follow-up (average=2.07years) glucose tolerance, acute insulin response, and insulin action (hyperinsulinemic-euglycemic clamp) assessed in 230 full Native Americans. In certain groups, the relationship between acute insulin response and increasing plasma glucose levels was non-linear. In all groups, acute insulin response decline preceded the cut-offs for traditional glucose regulation categories, although the timing with respect to increasing plasma glucose varied by race and adiposity. Longitudinal data indicated that improvement in insulin action is the key factor to preserve insulin secretion, underlying the reversion of glucose tolerance in prediabetic individuals. With worsening insulin action, the decline in insulin secretion occurred prior to current diagnostic guidelines for impaired glucose regulation. However, the relationship between acute insulin response and increasing plasma glucose varies and was not always non-linear. Understanding the dynamics of this relationship may determine when to initiate preventive pharmacotherapy directed at the preservation of β-cell failure.

Combination Immunotherapy for Type 1 Diabetes.

Type 1 diabetes (T1D) is an autoimmune disease marked by β-cell destruction. Immunotherapies for T1D have been investigated since the 1980s and have focused on restoration of tolerance, T cell or B cell inhibition, regulatory T cell (Treg) induction, suppression of innate immunity and inflammation, immune system reset, and islet transplantation. The purpose of this review is to provide an overview and lessons learned from single immunotherapy trials, describe recent and ongoing combination immunotherapy trials, and provide perspectives on strategies for future combination clinical interventions aimed at preserving insulin secretion in T1D. Combination immunotherapies have had mixed results in improving short-term glycemic control and insulin secretion in recent-onset T1D. A handful of studies have successfully reached their primary end-point of improved insulin secretion in recent-onset T1D. However, long-term improvements glycemic control and the restoration of insulin independence remain elusive. Future interventions should focus on strategies that combine immunomodulation with efforts to alleviate β-cell stress and address the formation of antigens that activate autoimmunity.

Endothelial microparticles released by activated protein C protect beta cells through EPCR/PAR1 and annexin A1/FPR2 pathways in islets.

Islet transplantation is associated with early ischaemia/reperfusion, localized coagulation and redox‐sensitive endothelial dysfunction. In animal models, islet cytoprotection by activated protein C (aPC) restores islet vascularization and protects graft function, suggesting that aPC triggers various lineages. aPC also prompts the release of endothelial MP that bear EPCR, its specific receptor. Microparticles (MP) are plasma membrane procoagulant vesicles, surrogate markers of stress and cellular effectors. We measured the cytoprotective effects of aPC on endothelial and insulin‐secreting Rin‐m5f β‐cells and its role in autocrine and paracrine MP‐mediated cell crosstalk under conditions of oxidative stress. MP from aPC‐treated primary endothelial (EC) or β‐cells were applied to H2O2‐treated Rin‐m5f. aPC activity was measured by enzymatic assay and ROS species by dihydroethidium. The capture of PKH26‐stained MP and the expression of EPCR were probed by fluorescence microscopy and apoptosis by flow cytometry. aPC treatment enhanced both annexin A1 (ANXA1) and PAR‐1 expression in EC and to a lesser extent in β‐cells. MP from aPC‐treated EC (eMaPC) exhibited high EPCR and annexin A1 content, protected β‐cells, restored insulin secretion and were captured by 80% of β cells in a phosphatidylserine and ANXA1‐dependent mechanism. eMP activated EPCR/PAR‐1 and ANXA1/FPR2‐dependent pathways and up‐regulated the expression of EPCR, and of FPR2/ALX, the ANXA1 receptor. Cytoprotection was confirmed in H2O2‐treated rat islets with increased viability (62% versus 48% H2O2), reduced apoptosis and preserved insulin secretion in response to glucose elevation (16 versus 5 ng/ml insulin per 10 islets). MP may prove a promising therapeutic tool in the protection of transplanted islets.

GDF11 Attenuates Development of Type 2 Diabetes via Improvement of Islet β-Cell Function and Survival.

Growth differentiation factor 11 (GDF11) has been implicated in the regulation of islet development and a variety of aging conditions, but little is known about the physiological functions of GDF11 in adult pancreatic islets. Here, we showed that systematic replenishment of GDF11 not only preserved insulin secretion but also improved the survival and morphology of β-cells and improved glucose metabolism in both nongenetic and genetic mouse models of type 2 diabetes (T2D). Conversely, anti-GDF11 monoclonal antibody treatment caused β-cell failure and lethal T2D. In vitro treatment of isolated murine islets and MIN6 cells with recombinant GDF11 attenuated glucotoxicity-induced β-cell dysfunction and apoptosis. Mechanistically, the GDF11-mediated protective effects could be attributed to the activation of transforming growth factor-β/Smad2 and phosphatidylinositol-4,5-bisphosphate 3-kinase-AKT-FoxO1 signaling. These findings suggest that GDF11 repletion may improve β-cell function and mass and thus may lead to a new therapeutic approach for T2D.

GAD-specific T cells are induced by GAD-alum treatment in Type-1 diabetes patients

Administration of Glutamic Acid Decarboxylase (GAD)65 formulated in aluminium hydroxide preserved insulin secretion in a phase II trial in recent onset Type 1 Diabetes. A subsequent European phase III trial was closed at 15months after failing to reach primary endpoint, but the majority of the Swedish patients completed the 21months follow-up. We studied the frequencies and phenotype of T cells, suppressive capacity of Tregs, GAD65-induced proliferation, and frequencies of T cells with a GAD65-specific TCR in Swedes participating in the trial. Stimulation with GAD65 induced activated T cells and also cells with a suppressive phenotype. Activated GAD65-specific effector T cells were detected by tetramer staining while the frequency of GAD65-specific Treg was not affected by the treatment. Additional doses of GAD-alum increased frequencies of CD25+CD127+, but had no effect on CD25hiCD127lo. Our findings indicate that GAD-alum treatment primarily induced activated T cells. GAD65-specific cells were mainly of activated phenotype.