Insulin Levels In Response Research Articles

Pharmacokinetics and Alterations in Glucose and Insulin Levels After a Single Dose of Canagliflozin in Healthy Icelandic Horses.

Canagliflozin (CFZ) is a sodium-glucose cotransporter-2 inhibitor that has shown promising results as a drug for the treatment of insulin dysregulation in horses. Even though CFZ is used clinically, no pharmacokinetic data has previously been published. In this study, the pharmacokinetics of CFZ after administration of a single oral dose of 1.8 mg/kg in eight healthy Icelandic horses was examined. Additionally, the effect of treatment on glucose and insulin levels in response to a graded glucose infusion was investigated. Plasma samples for CFZ quantification were taken at 0, 0.33, 0.66, 1, 1.33, 1.66, 2, 2.33, 2.66, 3, 3.5, 4, 5, 6, 8, 12, 24, 32, and 48 h post administration. CFZ was quantified using UHPLC coupled to tandem quadrupole mass spectrometry (UHPLC-MS/MS). A non-compartmental analysis revealed key pharmacokinetic parameters, including a median Tmax of 7 h, a Cmax of 2350 ng/mL, and a t1/2Z of 28.5 h. CFZ treatment reduced glucose (AUCGLU, p = 0.001) and insulin (AUCINS, p = 0.04) response to a graded glucose infusion administered 5 h after treatment. This indicates a rapid onset of action following a single dose in healthy Icelandic horses. No obvious adverse effects related to the treatment were observed.

Single-arm, first-in-human feasibility study results for an ultra-low-cost insulin pump

BackgroundUse of Continuous Subcutaneous Insulin Infusion (CSII) has been shown to improve glycemic outcomes in Type 1 Diabetes (T1D), but high costs limit accessibility. To address this issue, an inter-operable, open-source Ultra-Low-Cost Insulin Pump (ULCIP) was developed and previously shown to demonstrate comparable delivery accuracy to commercial models in standardised laboratory tests. This study aims to evaluate the updated ULCIP in-vivo, assessing its viability as an affordable alternative for those who cannot afford commercially available devices.MethodsThis first-in-human feasibility study recruited six participants with T1D. During a nine-hour inpatient stay, participants used the ULCIP under clinical supervision. Venous glucose, insulin, and β-Hydroxybutyrate were monitored to assess device performance.ResultsParticipants displayed expected blood glucose and blood insulin levels in response to programmed basal and bolus insulin dosing. One participant developed mild ketosis, which was treated and did not recur when a new pump reservoir was placed. All other participants maintained β-Hydroxybutyrate < 0.6 mmol/L throughout.ConclusionThe ULCIP safely delivered insulin therapy to users in a supervised inpatient environment. Future work should focus on correcting a pump hardware issue identified in this trial and extending device capabilities for use in closed loop control. Longer-term outpatient studies are warranted.Trial RegistrationThe trial was prospectively registered with the Australian New Zealand Clinical Trials Registry (ACTRN12623001288617) on the 11 December 2023.

Fasting for 48h induced similar glucose intolerance in both sexes despite greater perceived stress and decreased estradiol levels in females.

The purpose of this study was to compare the effects of fasting for 48 h on the evoked insulin and glucose responses in males and females, and to explore factors such as stress and estrogen levels that might influence these responses. Healthy, nonobese male (n = 14) and female (n = 14) subjects underwent 48-h fasting trial. Changes in glucose tolerance and insulin levels in response to the oral glucose tolerance test, subjectively perceived stress and catecholamine concentrations were measured in all participants. Estrogen levels were also measured in the female participants during the 48-h fast. Glucose area under the curve (AUC) values increased similarly in both sexes after 48-h fasting (P < 0.05), but females displayed a greater rise in insulin AUC values than males (P < 0.05). Fasting increased plasma epinephrine concentrations in both sexes (P < 0.05), whereas plasma norepinephrine concentrations and subjective stress increased only in females (P < 0.05). Plasma 17-β-estradiol concentrations in females decreased after fasting (P < 0.05). Fasting for 48h induced a similar glucose intolerance in females and males, despite decreased 17-β-estradiol levels and greater psychological and physiological stress in females. These differences represent a plausible explanation for the gender-based differences observed in insulin responses. Retrospectively registered on ClinicalTrials.gov(NCT05545943) in September 19, 2022.

VAMP4 regulates insulin levels by targeting secretory granules to lysosomes.

Insulin levels are essential for the maintenance of glucose homeostasis, and deviations lead to pathoglycemia or diabetes. However, the metabolic mechanism controlling insulin quantity and quality is poorly understood. In pancreatic β cells, insulin homeostasis and release are tightly governed by insulin secretory granule (ISG) trafficking, but the required regulators and mechanisms are largely unknown. Here, we identified that VAMP4 controlled the insulin levels in response to glucose challenge. VAMP4 deficiency led to increased blood insulin levels and hyperresponsiveness to glucose. In β cells, VAMP4 is packaged into immature ISGs (iISGs) at trans-Golgi networks and subsequently resorted to clathrin-coated vesicles during granule maturation. VAMP4-positive iISGs and resorted vesicles then fuse with lysosomes facilitated by a SNARE complex consisting of VAMP4, STX7, STX8, and VTI1B, which ensures the breakdown of excess (pro)insulin and obsolete materials and thus maintenance of intracellular insulin homeostasis. Thus, VAMP4 is a key factor regulating the insulin levels and a potential target for the treatment of diabetes.

Nanotechnology in Immunotherapy for Type 1 Diabetes: Promising Innovations and Future Advances.

Diabetes is a chronic condition which affects the glucose metabolism in the body. In lieu of any clinical “cure,” the condition is managed through the administration of pharmacological aids, insulin supplements, diet restrictions, exercise, and the like. The conventional clinical prescriptions are limited by their life-long dependency and diminished potency, which in turn hinder the patient’s recovery. This necessitated an alteration in approach and has instigated several investigations into other strategies. As Type 1 diabetes (T1D) is known to be an autoimmune disorder, targeting the immune system in activation and/or suppression has shown promise in reducing beta cell loss and improving insulin levels in response to hyperglycemia. Another strategy currently being explored is the use of nanoparticles in the delivery of immunomodulators, insulin, or engineered vaccines to endogenous immune cells. Nanoparticle-assisted targeting of immune cells holds substantial potential for enhanced patient care within T1D clinical settings. Herein, we summarize the knowledge of etiology, clinical scenarios, and the current state of nanoparticle-based immunotherapeutic approaches for Type 1 diabetes. We also discuss the feasibility of translating this approach to clinical practice.

Loss of function of renal Glut2 reverses hyperglycaemia and normalises body weight in mouse models of diabetes and obesity.

Renal GLUT2 is increased in diabetes, thereby enhancing glucose reabsorption and worsening hyperglycaemia. Here, we determined whether loss of Glut2 (also known as Slc2a2) specifically in the kidneys would reverse hyperglycaemia and normalise body weight in mouse models of diabetes and obesity. We used the tamoxifen-inducible CreERT2-Lox system in mice to knockout Glut2 specifically in the kidneys (Ks-Glut2 KO) to establish the contribution of renal GLUT2 to systemic glucose homeostasis in health and in insulin-dependent as well as non-insulin-dependent diabetes. We measured circulating glucose and insulin levels in response to OGTT or IVGTT under different experimental conditions in the Ks-Glut2 KO and their control mice. Moreover, we quantified urine glucose levels to explain the phenotype of the mice independently of insulin actions. We also used a transcription factor array to identify mechanisms underlying the crosstalk between renal GLUT2 and sodium-glucose cotransporter 2 (SGLT2). The Ks-Glut2 KO mice exhibited improved glucose tolerance and massive glucosuria. Interestingly, this improvement in blood glucose control was eliminated when we knocked out Glut2 in the liver in addition to the kidneys, suggesting that the improvement is attributable to the lack of renal GLUT2. Remarkably, induction of renal Glut2 deficiency reversed hyperglycaemia and normalised body weight in mouse models of diabetes and obesity. Longitudinal monitoring of renal glucose transporters revealed that Sglt2 (also known as Slc5a2) expression was almost abolished 3weeks after inducing renal Glut2 deficiency. To identify a molecular basis for this crosstalk, we screened for renal transcription factors that were downregulated in the Ks-Glut2 KO mice. Hnf1α (also known as Hnf1a) was among the genes most downregulated and its recovery restored Sglt2 expression in primary renal proximal tubular cells isolated from the Ks-Glut2 KO mice. Altogether, these results demonstrate a novel crosstalk between renal GLUT2 and SGLT2 in regulating systemic glucose homeostasis via glucose reabsorption. Our findings also indicate that inhibiting renal GLUT2 is a potential therapy for diabetes and obesity.

Loss-of-function of the long non-coding RNA A830019P07Rik in mice does not affect insulin expression and secretion

Long non-coding RNAs (lncRNAs) contribute to diverse cellular functions and the dysregulation of their expression or function can contribute to diseases, including diabetes. The contributions of lncRNAs to β-cell development, function and survival has been extensively studied in vitro. However, very little is currently known on the in vivo roles of lncRNAs in the regulation of glucose and insulin homeostasis. Here we investigated the impact of loss-of-function in mice of the lncRNA A830019P07Rik, hereafter P07Rik, which was previously reported to be associated with reduced plasma insulin levels. Compared with wild-type littermates, male and female P07Rik mutant mice did not show any defect in glycaemia and plasma insulin levels in both fed and fasted state. Furthermore, P07Rik mutant mice displayed similar glucose and insulin levels in response to an intra-peritoneal glucose tolerance test. Ex vivo, islets from mutant P07Rik released similar amount of insulin in response to increased glucose concentration as wildtype littermates. In contrast with previous reports, our characterization of P07Rik mouse mutants revealed that loss of function of this lncRNA does not affect glucose and insulin homeostasis in mice.

Islet Stellate Cells Regulate Insulin Secretion via Wnt5a in Min6 Cells.

Background Type 2 diabetes mellitus is a serious public health problem worldwide. Accumulating evidence has shown that β-cell dysfunction is an important mechanism underlying diabetes mellitus. The changes in the physiological state of islet stellate cells (ISCs) and the effects of these cells on β-cell dysfunction is an important mechanism underlying diabetes mellitus. The changes in the physiological state of islet stellate cells (ISCs) and the effects of these cells on Methods Glucose-stimulated insulin secretion (GSIS) from Min6 cells was examined by estimating the insulin levels in response to high glucose challenge after culture with ISC supernatant or exogenous Wnt5a. Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR) analyses were used to observe changes in the β-cell dysfunction is an important mechanism underlying diabetes mellitus. The changes in the physiological state of islet stellate cells (ISCs) and the effects of these cells on Results We observed a significant increase in insulin secretion from Min6 cells cocultured in vitro with supernatant from db/m mouse ISCs compared to that from Min6 cells cocultured with supernatant from db/db mouse ISCs; The intracellular Ca2+ concentration in Min6 cells increased in cultured in vitro with supernatant from db/m mouse ISCs and exogenous Wnt5a compared to that from control Min6 cells. Culture of Min6 cells with exogenous Wnt5a caused a significant increase in pCamKII, pFoxO1, PDX-1, and Glut2 levels compared to those in Min6 cells cultured alone; this treatment further decreased Ror2 and Cask expression but did not affect β-cell dysfunction is an important mechanism underlying diabetes mellitus. The changes in the physiological state of islet stellate cells (ISCs) and the effects of these cells on Conclusion ISCs regulate insulin secretion from Min6 cells through the Wnt5a protein-induced Wnt-calcium and FoxO1-PDX1-GLUT2-insulin signalling cascades.

Patterns of postmeal insulin secretion in individuals with sulfonylurea-treated KCNJ11 neonatal diabetes show predominance of non-KATP-channel pathways

ObjectiveInsulin secretion in sulfonylurea-treated KCNJ11 permanent neonatal diabetes mellitus (PNDM) is thought to be mediated predominantly through amplifying non-KATP-channel pathways such as incretins. Affected individuals report symptoms of postprandial hypoglycemia...

Sleeve Gastrectomy and Roux-en-Y Gastric Bypass Attenuate Pro-inflammatory Small Intestinal Cytokine Signatures.

Bariatric surgery rapidly induces improvements in type 2 diabetes (T2D) in concert with reduction in systemic markers of inflammation. The impact of bariatric surgery on local intestinal immunity is not known. We hypothesize that sleeve gastrectomy (SG) and gastric bypass (RYGB) surgeries resolve obesity-induced intestinal inflammation, thereby promotingT2D resolution. SG and RYGB, or control surgery was performed in SD rats (n = 4-6/group). Key cytokines involved in insulin resistance (TNF-α, IFN-γ), inflammasome activation (IL-1β, IL-18), inflammation resolution (IL-10, IL-33), and Th17 cell responses (IL-17, IL-23) were measured by qPCR in mucosal scrapings of jejunum at 4weeks post-surgery. Intestinal cytokine expressions were correlated with weight change, systemic and portal glucose, and insulin levels in response to an enteral glucose load. SG downregulated IL-17 and IL-23 in both proximal and distal jejunum, and IFN-γ was reduced only in distal jejunum (p < 0.05). Jejunal IL-17 and IL-23 expression correlated positively with weight changes after SG (0.93 and 0.98, respectively; p < 0.05). Changes in IFN-γ correlated strongly with insulin levels in portal and systemic circulation (0.99 and 0.95, respectively, p < 0.05). As with SG, IFN-γ, IL-17, and IL-23 were significantly reduced by RYGB. RYGB also reduced TNF-α and IL-18 and increased IL-33 levels (p < 0.05). RYGB and SG reduce expression of pro-inflammatory cytokines IL-17, IL-23, and IFN-γ in the jejunum. RYGB showed attenuation of additional pro-inflammatory cytokines and enhanced expression of IL-33. Post-surgical changes in intestinal IL-17, IL-23, and IFN-γ correlate strongly with changes in weight and glucose-triggered insulin responses.

Targeting Cellular Calcium Homeostasis to Prevent Beta-Cell Death in Type 1 Diabetes

Cytokines are important mediators of beta cell death leading to type 1 diabetes (T1DM). The mechanism of cytokine-mediated beta cell death has been previously shown to involve alterations in beta cell calcium homeostasis and increases in endoplasmic reticulum (ER) stress. Our group has previously established that pharmacologic modulation of cellular calcium levels with dantrolene and sitagliptin can significantly decrease cytokine and ER stress-mediated activation of the calpain and thioredoxin interacting protein pro-apoptotic pathways and suppress cell death in vitro using INS-1E rat insulinoma cells. The current study was designed to determine if dantrolene and sitagliptin can prevent beta cell death and diabetes in the low dose streptozotocin (STZ) model of T1DM. Male C57Bl/6 mice were treated with 5 doses of STZ (50 mg/kg) daily by 10 days of intraperitoneal (IP) injections of placebo, dantrolene, or sitagliptin. Blood sugar was monitored via tail vein blood using a glucometer. Blood glucose and insulin levels in response to 2g/kg IP dextrose injection were obtained on day 10. Unmethylated insulin DNA was also measured from plasma drawn on day 0, 8 and 15 to monitor beta cell death. Sitagliptin treated mice were resistant to low dose STZ induced diabetes as indicated by lower random blood glucose levels and normalization of blood glucose and insulin levels in response to IP dextrose infusion compared to placebo treated animals. In addition, sitagliptin treated animals had significantly lower levels of circulating unmethylated insulin DNA suggesting lower incidence of beta cell death as compared to placebo treated animals. In summary, in the low dose STZ model of diabetes, sitagliptin lowered random blood sugar, normalized blood glucose and insulin response to IP glucose tolerance testing and significantly decreased STZ mediated beta cell death. This study supports further study on the effect of sitagliptin and DPP-4 inhibition on beta cell function and survival in T1DM. Disclosure A.L. Clark: None. D. Abreu: None. C.M. Brown: None. F. Urano: Research Support; Self; Eli Lilly and Company. Stock/Shareholder; Self; CytRx.

Transcriptome Profiles and Gene Expression of Min6 Cells Are Altered by Pancreatic Stellate Cells

Aim: To identify the influence of pancreatic stellate cell (PSCs) secretions on gene expression profiles of Min6 cells by whole transcriptome sequencing. Methods: Pancreatic stellate cells (PSCs) were isolated from C57BL6J mice and propagated in vitro to acquire the activated phenotype. Total RNA was isolated from monocultured (MC) and PSC cocultured (CC) Min6 cells to prepare cDNA libraries, which were subjected to whole transcriptome sequencing for identifying differential expression of β-cell transcription factors (Pdx-1, Rfx6 and NeuroD1) related to insulin gene transcription and GSIS related genes such as Glut2, Gck, Abcc8, Kcnj11 and L-type Ca2+ channels (Cacnb2, Cacna1c). qRT-PCR was used to validate the gene expression. GSIS of Min6 cells was examined by estimating insulin levels in response to high glucose challenge. Results: Transcriptome analysis of discovery set revealed that coculture of Min6 cells with PSCs caused increased expression of β-cell specific genes (Ins1, Rfx6 and NeuroD1) concomitant with decreased expression of Pdx-1, MafA and Nkx2-2. Expression of GSIS associated genes (Glut2, Gck, Abcc8, Kcnj11 and Cacnb2) was decreased in such conditions. Validation by qRT-PCR in Min6 cells cocultured with PSCs revealed increased significant expression of Ins1 (2.1 ± 0.22 folds; p ≤ 0.001), Rfx6 (1.68 ± 0.23 folds; p ≤ 0.002) and NeuroD1 (0.96 ± 0.11 folds; p ≤ 0.01), accompanied by downregulation of Cacnb2 (-0.93 ± 0.57 folds; p ≤ 0.05). PSC secretions did not restore the GSIS from glucose unresponsive higher passage Min6 cells (MC: 1.33 ± 0.42; CC: 1.55 ± 0.72 pmol/mg protein; p = ns) upon high glucose stimulation. However, glucose responsive higher passage Min6 cells cocultured with PSCs presented increased insulin secretion (MC: 7.025 ± 0.64; CC: 14.84 ± 1.01 pmol/mg protein; p ≤ 0.04) concomitant with marginal increase of insulin contents. Conclusion: PSC secretions increase Ins1, Rfx6 and NeuroD1 gene expression, GSIS from glucose responsive Min6 cells, but do not restore the GSIS from glucose unresponsive Min6 cells.

Adult muscle-derived stem cells engraft and differentiate into insulin-expressing cells in pancreatic islets of diabetic mice

BackgroundPancreatic beta cells are unique effectors in the control of glucose homeostasis and their deficiency results in impaired insulin production leading to severe diabetic diseases. Here, we investigated the potential of a population of nonadherent muscle-derived stem cells (MDSC) from adult mouse muscle to differentiate in vitro into beta cells when transplanted as undifferentiated stem cells in vivo to compensate for beta-cell deficiency.ResultsIn vitro, cultured MDSC spontaneously differentiated into insulin-expressing islet-like cell clusters as revealed using MDSC from transgenic mice expressing GFP or mCherry under the control of an insulin promoter. Differentiated clusters of beta-like cells co-expressed insulin with the transcription factors Pdx1, Nkx2.2, Nkx6.1, and MafA, and secreted significant levels of insulin in response to glucose challenges. In vivo, undifferentiated MDSC injected into streptozotocin (STZ)-treated mice engrafted within 48 h specifically to damaged pancreatic islets and were shown to differentiate and express insulin 10–12 days after injection. In addition, injection of MDSC into hyperglycemic diabetic mice reduced their blood glucose levels for 2–4 weeks.ConclusionThese data show that MDSC are capable of differentiating into mature pancreatic beta islet-like cells, not only upon culture in vitro, but also in vivo after systemic injection in STZ-induced diabetic mouse models. Being nonteratogenic, MDSC can be used directly by systemic injection, and this potential reveals a promising alternative avenue in stem cell-based treatment of beta-cell deficiencies.

High-fat diet effects on metabolic responses to chronic stress

Context: High-fat diets and chronic stress are prevalent risk factors for various chronic diseases in modern societies.Objective: This study investigated the effect of high-fat diet on glucose-related metabolic responses to chronic foot-shock stress.Materials and methods: Male rats were divided into high-fat diet (containing 54.21% saturated and 44.89% unsaturated fatty acids) and normal diet groups and then into stress and non-stress subgroups. The diets were applied for 5 weeks, and stress was induced during the last week of the diet course. Plasma levels of metabolic parameters, HOMA-IR index, intra-abdominal fat weight, and islets’ insulin secretion were assessed.Results: High-fat diet increased abdominal fat weight and plasma leptin, and insulin levels in response to stress without affecting HOMA-IR index and islets’ insulin secretion.Conclusions: High proportion of unsaturated fat may not lead to deleterious metabolic responses; however combined with chronic stress has a synergistic and adverse effect on visceral adiposity and results in elevated plasma leptin.

Polymorphism rs16147 of the Neuropeptide Y Gene Modifies the Response of Cardiovascular Risk Biomarkers and Adipokines to Two Hypocaloric Diets

Aims: Our aim was to evaluate the relationship of weight loss and changes in adipokine levels after two hypocaloric diets in obese subjects with polymorphism rs16147 of the neuropeptide Y gene. Subjects and Methods: A population of 283 obese patients was analyzed. At the basal visit, patients were randomly allocated to one of two diets for a period of 3 months (diet I, low in carbohydrates; diet II, low in fat). Results: With diet I and in both genotype groups (major versus minor allele), body mass index (BMI), weight, fat mass, waist circumference, and leptin decreased. With diet II and in all genotypes, BMI, weight, fat mass, waist circumference, and leptin decreased. With both diets and in subjects with the minor allele, insulin levels (diet I: major allele -1.7 ± 7.8 IU/L versus minor allele -4.2 ± 6.1 IU/L, p = 0.01; diet II: major allele -2.3 ± 6.1 IU/L versus minor allele -4.0 ± 5.2 IU/L, p = 0.02) and insulin resistance (diet I: major allele -0.2 ± 3.1 units versus minor allele -1.7 ± 3.0 units, p = 0.03; diet II: major allele -0.9 ± 2.0 units versus minor allele -1.7 ± 1.3 units, p = 0.01) decreased. Conclusion: The rs16147 genotype affected the reduction in insulin resistance and insulin levels in response to two different hypocaloric diets in obese subjects, with a lack of response in subjects with the major allele.

Drosophila insulin release is triggered by adipose Stunted ligand to brain Methuselah receptor.

Animals adapt their growth rate and body size to available nutrients by a general modulation of insulin-insulin-like growth factor signaling. In Drosophila, dietary amino acids promote the release in the hemolymph of brain insulin-like peptides (Dilps), which in turn activate systemic organ growth. Dilp secretion by insulin-producing cells involves a relay through unknown cytokines produced by fat cells. Here, we identify Methuselah (Mth) as a secretin-incretin receptor subfamily member required in the insulin-producing cells for proper nutrient coupling. We further show, using genetic and ex vivo organ culture experiments, that the Mth ligand Stunted (Sun) is a circulating insulinotropic peptide produced by fat cells. Therefore, Sun and Mth define a new cross-organ circuitry that modulates physiological insulin levels in response to nutrients.

Abstract 127: Effects of miR-33 Antagonism on Glucose and Triglyceride Metabolism in Nonhuman Primates.

Elevated plasma low-density lipoprotein (LDL) and decreased high-density lipoprotein (HDL) cholesterol levels increase the risk of cardiovascular disease (CVD). While strategies to lower LDL cholesterol have been successful in reducing CVD-related mortality, there is still an unmet need for developing therapies to reduce the residual risk of atherosclerotic CVD. Plasma HDL cholesterol levels are inversely correlated with CVD risk and thus novel therapies to increase plasma HDL cholesterol levels have garnered much attention in recent years. MicroRNA-33a and b (miR-33a/b) are intronically-encoded microRNAs residing in the sterol response element binding protein genes SREBF2 and SREBF1 and suppress the expression of the genes involved in cholesterol efflux and fatty acid oxidation. Recent studies show that antagonism of miR-33 results in increased ABCA1expression and elevated plasma HDL levels in both mice and nonhuman primates. However, findings in mice suggest that long term miR-33 antagonism may lead to hepatic steatosis and increased production of very low-density lipoprotein (VLDL), the precursor to proatherogenic LDL. In the current study, cynomolgus monkeys were fed a high carbohydrate diet plus Kool Aid prior to administration of antisense oligonucleotides (ASOs) specific for miR-33a/b. As expected, miR-33 antagonism resulted in elevated plasma total cholesterol levels, predominantly due to increased HDL. No differences in plasma LDL or triglycerides were observed between treatment groups. MiR-33a/b antagonism had no effect on VLDL triglyceride secretion rates. Anti-miR-33 treatment did not promote hepatic lipid accumulation or adversely affect liver transaminase levels. Glucose tolerance tests revealed no differences in either plasma glucose or insulin levels in response to miR-33a/b antagonism. These findings suggest that anti-miR-33 therapy raises HDL cholesterol without negatively impacting either triglyceride or glucose homeostasis in nonhuman primates.

In vitro generation of pancreatic β-cells for diabetes treatment. I. β-like cells derived from human pluripotent stem cells.

Diabetes mellitus is a chronic disease that affects hundreds of millions of people worldwide. Type 1 diabetes (T1D) is characterized by the lack of pancreatic β-cells that had been destroyed as a result of an autoimmune response. Therefore, in patients with T1D, the replacement therapy with functional β-cells derived from extrinsic sources could be a preferable option as compared to insulin treatment. Unfortunately, successful transplantation of whole pancreata or pancreatic islets into patients with diabetes is available only to a fraction of them due to the scarcity of donors. The rapid development of cell reprogramming methods made it possible to generate large numbers of human β-like cells derived from human embryonic stem cells (hESCs) or human induced pluripotent stem cells (hiPSCs). This review describes the basis of in vitro differentiaton protocols of β-like cells that mimic changes of the main signaling pathways during the key stages of human and murine pancreas development, which are described first. During the last 15 years it was found that there are no important differences between hESCs and hiPSCs in their differentiation capacities into β-like cells and the expression profiles of the key transcription factors. The in vitro produced β-like cells are immature as demonstrated by functional tests in rodents and single-cell transcriptomic and proteomic analyses. After the transplantation of the β cell progenitors into immunocompromised diabetic mice, a few weeks have to pass before the increased insulin levels in response to glucose load appear. There is a continuous progress in the development of open-type encapsulation devices which allow the vascularization of the transplanted cells and protect them against host's immune cells. The results of the first clinical trial of human partially differentiated endocrine progenitors of β cells transplanted into patients with T1D will be published in the year 2019. It is hoped that further improvements in the techniques of large-scale generation of the β-like cells derived from human pluripotent stem cells will bring us closer to their clinical application as a form of cause-directed therapy for people with diabetes.

Hyperuricemia Causes Pancreatic β-Cell Death and Dysfunction through NF-κB Signaling Pathway

Accumulating clinical evidence suggests that hyperuricemia is associated with an increased risk of type 2 diabetes. However, it is still unclear whether elevated levels of uric acid can cause direct injury of pancreatic β-cells. In this study, we examined the effects of uric acid on β-cell viability and function. Uric acid solution or normal saline was administered intraperitoneally to mice daily for 4 weeks. Uric acid-treated mice exhibited significantly impaired glucose tolerance and lower insulin levels in response to glucose challenge than did control mice. However, there were no significant differences in insulin sensitivity between the two groups. In comparison to the islets in control mice, the islets in the uric acid–treated mice were markedly smaller in size and contained less insulin. Treatment of β-cells in vitro with uric acid activated the NF-κB signaling pathway through IκBα phosphorylation, resulting in upregulated inducible nitric oxide synthase (iNOS) expression and excessive nitric oxide (NO) production. Uric acid treatment also increased apoptosis and downregulated Bcl-2 expression in Min6 cells. In addition, a reduction in insulin secretion under glucose challenge was observed in the uric acid–treated mouse islets. These deleterious effects of uric acid on pancreatic β-cells were attenuated by benzbromarone, an inhibitor of uric acid transporters, NOS inhibitor L-NMMA, and Bay 11–7082, an NF-κB inhibitor. Further investigation indicated that uric acid suppressed levels of MafA protein through enhancing its degradation. Collectively, our data suggested that an elevated level of uric acid causes β-cell injury via the NF-κB-iNOS-NO signaling axis.

Role of Adipose Triglyceride Lipase and Lipolysis in the Regulation of Insulin Secretion: Study in β-Cell-Specific ATGL-Deficient Mice

Previous studies have suggested that lipolysis-derived lipid signalling molecules play a role in the regulation of glucose-stimulated insulin secretion. To directly assess the role of lipolysis of β-cell endogenous lipid stores in glucose signalling for insulin secretion, β-cell-specific adipose triglyceride lipase (ATGL)-deficient mice (KO) were generated. β-cell-specific tamoxifen-inducible ATGL deletion in MIP-Cre-ER/ATGL-LoxP mice (KO) was compared to tamoxifen-injected-MIP-Cre-ER and -ATGL-LoxP mice (controls). Two weeks after tamoxifen treatment in 8-week-old mice, ATGL protein level was dramatically decreased in KO islets from both sexes. KO male mice showed a decrease in body weight gain compared to the controls, which became significant 6 weeks after tamoxifen injection. Fasting plasma levels of free fatty acids and triglycerides were unchanged in KO mice of both sexes. Male KO mice showed a 60% decrease in insulinemia without altered glycemia in fed and fasted states. They also showed a 70% reduction in plasma insulin levels in response to a glucose challenge and a trend toward glucose intolerance. However, despite similar ATGL deletion in female KO mice, none of these changes in glucose homeostasis and insulin secretory response were observed. These results demonstrate that lipolysis via ATGL is involved in glucose-stimulated insulin secretion, at least in male mice. Female mice are often protected from diabetes in various animal models due to estrogens and a number of compensatory processes. We are currently studying the compensatory mechanisms that occur in KO female mice as they may reveal signalling and compensatory pathways involved in insulin secretion.