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The Human and Mouse Islet Peptidome: Effects of Obesity and Type 2 Diabetes, and Assessment of Intraislet Production of Glucagon-like Peptide-1.

ABSTRACT: To characterize the impact of metabolic disease on the peptidome of human and mouse pancreatic islets, LC-MS was used to analyze extracts of human and mouse islets, purified mouse alpha, beta, and delta cells, supernatants from mouse islet incubations, and plasma from patients with type 2 diabetes. Islets were obtained from healthy and type 2 diabetic human donors, and mice on chow or high fat diet. All major islet hormones were detected in lysed islets as well as numerous peptides from vesicular proteins including granins and processing enzymes. Glucose-dependent insulinotropic peptide (GIP) was not detectable. High fat diet modestly increased islet content of proinsulin-derived peptides in mice. Human diabetic islets contained increased content of proglucagon-derived peptides at the expense of insulin, but no evident prohormone processing defects. Diabetic plasma, however, contained increased ratios of proinsulin and des-31,32-proinsulin to insulin. Active GLP-1 was detectable in human and mouse islets but 100-1000-fold less abundant than glucagon. LC-MS offers advantages over antibody-based approaches for identifying exact peptide sequences, and revealed a shift toward islet insulin production in high fat fed mice, and toward proglucagon production in type 2 diabetes, with no evidence of systematic defective prohormone processing.

SUBMITTER: Galvin SG

PROVIDER: S-EPMC8419866 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundGlucagon-like peptide analogues are a new class of drugs used in the treatment of type 2 diabetes that mimic the endogenous hormone glucagon-like peptide 1 (GLP-1). GLP-1 is an incretin, a gastrointestinal hormone that is released into the circulation in response to ingested nutrients. GLP-1 regulates glucose levels by stimulating glucose-dependent insulin secretion and biosynthesis, and by suppressing glucagon secretion, delayed gastric emptying and promoting satiety.ObjectivesTo assess the effects of glucagon-like peptide analogues in patients with type 2 diabetes mellitus.Search strategyStudies were obtained from electronic searches of The Cochrane Library (last search issue 1, 2011), MEDLINE (last search March 2011), EMBASE (last search March 2011), Web of Science (last search March 2011) and databases of ongoing trials.Selection criteriaStudies were included if they were randomised controlled trials of a minimum duration of eight weeks comparing a GLP-1 analogue with placebo, insulin, an oral anti-diabetic agent, or another GLP-1 analogue in people with type 2 diabetes.Data collection and analysisData extraction and quality assessment of studies were done by one reviewer and checked by a second. Data were analysed by type of GLP-1 agonist and comparison treatment. Where appropriate, data were summarised in a meta-analysis (mean differences and risk ratios summarised using a random-effects model).Main resultsSeventeen randomised controlled trials including relevant analyses for 6899 participants were included in the analysis. Studies were mostly of short duration, usually 26 weeks.In comparison with placebo, all GLP-1 agonists reduced glycosylated haemoglobin A1c (HbA1c) levels by about 1%. Exenatide 2 mg once weekly and liraglutide 1.8 mg reduced it by 0.20% and 0.24% respectively more than insulin glargine. Exenatide 2 mg once weekly reduced HbA1c more than exenatide 10 μg twice daily, sitagliptin and pioglitazone. Liraglutide 1.8 mg reduced HbA1c by 0.33% more than exenatide 10 μg twice daily. Liraglutide led to similar improvements in HbA1c compared to sulphonylureas but reduced it more than sitagliptin and rosiglitazone.Both exenatide and liraglutide led to greater weight loss than most active comparators, including in participants not experiencing nausea. Hypoglycaemia occurred more frequently in participants taking concomitant sulphonylurea. GLP-1 agonists caused gastrointestinal adverse effects, mainly nausea. These adverse events were strongest at the beginning and then subsided. Beta-cell function was improved with GLP-1 agonists but the effect did not persist after cessation of treatment.None of the studies was long enough to assess long-term positive or negative effects.Authors' conclusionsGLP-1 agonists are effective in improving glycaemic control.

Project description:BackgroundWith the increasing prevalence of obesity and type 2 diabetes, the availability of different treatment options remains essential. Studies comparing the outcomes of glucagon-like peptide 1 receptor agonists with those of metabolic bariatric surgery in patients with type 2 diabetes and obesity are lacking.MethodsUsing propensity score matching, based on data from several nationwide clinical registries, patients who underwent primary metabolic bariatric surgery (Roux-en-Y gastric bypass or sleeve gastrectomy) were matched with patients who received glucagon-like peptide 1 receptor agonists. Outcome measures included the occurrence of major cardiovascular events, microvascular complications, and potential side effects (alcohol/substance abuse, self-harm, and fractures).ResultsOver a mean follow-up of 7 years, major cardiovascular events occurred in 191 of 2039 patients (cumulative incidence 14.5%) in the surgery group compared with 247 of 2039 patients (19.6%) in the glucagon-like peptide 1 receptor agonist group (HR 0.75 (95% c.i. 0.62 to 0.91), P = 0.003). Patients in the surgery group had lower haemoglobin A1c values 5 years after treatment (mean difference 9.82 (95% c.i. 8.51 to 11.14) mmol/mol, P < 0.001) and fewer microvascular complications (retinopathy HR 0.88 (95% c.i. 0.79 to 0.99), P = 0.039; nephropathy HR 0.72 (95% c.i. 0.66 to 0.80), P < 0.001; and neuropathy or leg ulcers HR 0.82 (95% c.i. 0.74 to 0.92), P < 0.001), but a higher risk of alcohol/substance abuse (HR 2.56 (95% c.i. 1.87 to 3.50), P < 0.001), self-harm (HR 1.41 (95% c.i. 1.17 to 1.71), P < 0.001), and fractures (HR 1.86 (95% c.i. 1.11 to 3.12), P = 0.019).ConclusionCompared with glucagon-like peptide 1 receptor agonist treatment, metabolic bariatric surgery is associated with superior metabolic outcomes and a lower risk of major cardiovascular events in patients with type 2 diabetes and obesity, but a higher risk of alcohol/substance abuse, self-harm, and fractures.

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The Human and Mouse Islet Peptidome: Effects of Obesity and Type 2 Diabetes, and Assessment of Intraislet Production of Glucagon-like Peptide-1.

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