Potential for Gut Peptide-Based Therapy in Postprandial Hypotension.

Postprandial hypotension (PPH) is an important and under-recognised disorder resulting from inadequate compensatory cardiovascular responses to meal-induced splanchnic blood pooling. Current approaches to management are suboptimal. Recent studies have established that the cardiovascular response to a meal is modulated profoundly by gastrointestinal factors, including the type and caloric content of ingested meals, rate of gastric emptying, and small intestinal transit and absorption of nutrients. The small intestine represents the major site of nutrient-gut interactions and associated neurohormonal responses, including secretion of glucagon-like peptide-1, glucose-dependent insulinotropic peptide and somatostatin, which exert pleotropic actions relevant to the postprandial haemodynamic profile. This review summarises knowledge relating to the role of these gut peptides in the cardiovascular response to a meal and their potential application to the management of PPH.

A proopiomelanocortin-derived peptide sequence enhances plasma stability of peptide drugs.

Bioactive peptide drugs hold promise for therapeutic application due to their high potency and selectivity but display short plasma half-life. Examination of selected naturally occurring peptide hormones derived from proteolytic cleavage of the proopiomelanocortin (POMC) precursor lead to the identification of significant plasma-stabilizing properties of a 12-amino acid serine-rich orphan sequence NSSSSGSSGAGQ in human γ3-melanocyte-stimulating hormone (MSH) that is homologous to previously discovered NSn GGH (n = 4-24) sequences in owls. Notably, transfer of this sequence to des-acetyl-α-MSH and the therapeutically relevant peptide hormones neurotensin and glucagon-like peptide-1 likewise enhance their plasma stability without affecting receptor signaling. The stabilizing effect of the sequence module is independent of plasma components, suggesting a direct effect in cis. This natural sequence module may provide a possible strategy to enhance plasma stability, complementing existing methods of chemical modification.

Body weight course in the DIAbetes and LifEstyle Cohort Twente (DIALECT-1)-A 20-year observational study.

BACKGROUND: Although weight gain increases risk of type 2 diabetes, real-life data on the weight course in patients with established type 2 diabetes are scarce. We assessed weight course in a real-life diabetes secondary care setting and analyzed its association with patient characteristics, lifestyle habits and initiation of insulin, glucagon like peptide-1 receptor agonists (GLP-1 RA) and sodium-glucose co-transporter-2 inhibitors (SGLT-2i). METHODS: Data on weight, insulin, GLP-1 RA and SGLT-2i use were collected retrospectively (12 years) and prospectively (8 years) from patients included in the DIAbetes and LifEstyle Cohort Twente-1 (DIALECT-1, n = 450, age 63 ± 9 years, 58% men, diabetes duration [7-18] years). Lifestyle habits were assessed using validated questionnaires. The association of clinical parameters with body mass index (BMI) course was determined using linear mixed models. Patients who underwent bariatric surgery (n = 19) had a distinct BMI course and were excluded from the study. RESULTS: Baseline BMI was 31.3 (0.3) and was higher in women, patients aged <60 years and patients with unfavorable lifestyle habits. BMI increased to 32.5 (0.3) after 12 years (P<0.001), and thereafter decreased to 31.5 (0.3) after 20 years, resulting in a similar BMI as the baseline BMI (P = 0.96, compared to baseline). Clinical parameters or initiation of insulin or SGLT-2i were not associated with BMI course. Patients who initiated GLP-1 RA declined in BMI compared to non-users (Pinteraction = 0.003). CONCLUSIONS: High BMI that real-life patients with type 2 diabetes gained earlier in life, remained stable in the following decades. Weight loss interventions should remain a priority, and GLP-1 RA might be considered to support weight loss.

Epicardial adipose tissue GLP-1 receptor is associated with genes involved in fatty acid oxidation and white-to-brown fat differentiation: A target to modulate cardiovascular risk?

BACKGROUND: Epicardial adipose tissue (EAT) is a risk factor for cardiovascular diseases. Glucagon-like peptide 1 analogs (GLP-1A) may have beneficial cardiovascular effects and reduce EAT, possibly throughout targeting GLP-1 receptor (GLP-1R). Nevertheless, the role of EAT GLP-1R, GLP-2R and their interplay with EAT genes involved in adipogenesis and fatty acid (FA) metabolism are unknown. We analyzed whether EAT transcriptome is related to GLP-1R/GLP-2R gene expression, and GLP-1/GLP-2 plasma levels in coronary artery disease patients (CAD). METHODS: EAT was collected from 17 CAD patients undergoing CABG for microarray analysis of GLP-1R, GLP-2R and genes involved in FA metabolism and adipogenesis. EAT thickness was measured by echocardiography. GLP-1 and GLP-2 levels were quantified by ELISA in CAD and healthy subjects (CTR). RESULTS: EAT GLP-1R was directly correlated with genes promoting beta-oxidation and white-to-brown adipocyte differentiation, and inversely with pro-adipogenic genes. GLP-2R was positively correlated with genes involved in adipogenesis and lipid synthesis, and inversely with genes promoting beta-oxidation. GLP-1 and GLP-2 levels were higher in CAD than CTR and in patients with greater EAT thickness. CONCLUSIONS: GLP-1 analogs may target EAT GLP-1R and therefore reduce local adipogenesis, improve fat utilization and induce brown fat differentiation. As EAT lies in direct contiguity to myocardium and coronary arteries, the beneficial effects of GLP-1 activation may extent to the heart. The increased levels of circulating GLP-1 and GLP-2 and EAT GLP-2R may be compensatory mechanisms related to CAD and also EAT expansion, but the meaning of these observations needs to be further investigated.

Introduction.

DISCLOSURES: This supplement was funded by Novo Nordisk. McGill has received grants and personal fees from Novo Nordisk; grants from AstraZeneca, Novartis, Lexicon, and Pfizer; and personal fees from Intarcia, Boehringer-Ingelheim, Janssen, Mannkind, Bayer, and Merck.

Health-Related Quality of Life Assessments with Once-Weekly Glucagon-Like Peptide-1 Receptor Agonists in Type 2 Diabetes Mellitus.

Type 2 diabetes (T2DM) is associated with significant impairment in health-related quality of life (HRQoL). A patient-centered collaborative approach is recommended to optimize clinical outcomes, including HRQoL, in this patient population. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) provide effective glycemic control and have demonstrated beneficial effects on HRQoL and treatment satisfaction. Available once-weekly GLP-1 RAs may offer enhanced convenience compared with daily GLP-1 RAs and include exenatide extended-release (ER), dulaglutide, and semaglutide. This article reviews the impact of once-weekly GLP-1 RAs on HRQoL and treatment satisfaction in patients with T2DM. Compared with oral antihyperglycemic drugs, insulin, and daily GLP-1 RAs, once-weekly GLP-1 RAs offer benefits with regard to HRQoL and treatment satisfaction. These benefits appear to be largely mediated by relative drug effects on glycemic control, weight, and hypoglycemia. While there was not an overall class benefit of once-weekly GLP-1 RAs compared with daily GLP-1 RAs on HRQoL and treatment satisfaction, results suggested that once-weekly GLP-1 RAs may enhance certain elements of treatment satisfaction and increase willingness to continue treatment. In 2 studies comparing once-weekly GLP-1 RAs with each other, semaglutide produced significantly greater improvement in overall treatment satisfaction compared with exenatide ER but not dulaglutide. Once-weekly GLP-1 RAs represent an effective and convenient treatment option that may potentially increase treatment satisfaction and enhance adherence, contributing to improved health outcomes. DISCLOSURES: This supplement was funded by Novo Nordisk. Billings reports personal fees from Dexcom, Novo Nordisk, and Sanofi. Handelsman reports research grants from Amgen, AstraZeneca, Bristol-Myers Squibb, Boehringer Ingelheim, Grifols, Janssen, Lexicon, Merck, Novo Nordisk, Regeneron, and Sanofi; speaker fees from Amarin, Amgen, AstraZeneca, Boehringer Ingelheim-Lilly, Janssen, Merck, Novo Nordisk, Regeneron, and Sanofi; and has served in advisory capacity to Amarin, Amgen, AstraZeneca, Boehringer Ingelheim, Eisai, Intarcia, Janssen, Lilly, Merck, Merck-Pfizer, Novo Nordisk, Regeneron, and Sanofi. Heile reports speaker fees from and has served as advisor to Novo Nordisk. Schneider reports advisory board fees from Intarcia, Lilly, and Novo Nordisk. Wyne has nothing to disclose.

Elevated Postoperative Endogenous GLP-1 Levels Mediate Effects of Roux-en-Y Gastric Bypass on Neural Responsivity to Food Cues.

OBJECTIVE: It has been suggested that weight reduction and improvements in satiety after Roux-en-Y gastric bypass (RYGB) are partly mediated via postoperative neuroendocrine changes. Glucagon-like peptide-1 (GLP-1) is a gut hormone secreted after food ingestion and is associated with appetite and weight reduction, mediated via effects on the central nervous system (CNS). Secretion of GLP-1 is greatly enhanced after RYGB. We hypothesized that postoperative elevated GLP-1 levels contribute to the improved satiety regulation after RYGB via effects on the CNS. RESEARCH DESIGN AND METHODS: Effects of the GLP-1 receptor antagonist exendin 9-39 (Ex9-39) and placebo were assessed in 10 women before and after RYGB. We used functional MRI to investigate CNS activation in response to visual food cues (pictures) and gustatory food cues (consumption of chocolate milk), comparing results with Ex9-39 versus placebo before and after RYGB. RESULTS: After RYGB, CNS activation was reduced in the rolandic operculum and caudate nucleus in response to viewing food pictures (P = 0.03) and in the insula in response to consumption of palatable food (P = 0.003). GLP-1 levels were significantly elevated postoperatively (P < 0.001). After RYGB, GLP-1 receptor blockade resulted in a larger increase in activation in the caudate nucleus in response to food pictures (P = 0.02) and in the insula in response to palatable food consumption (P = 0.002). CONCLUSIONS: We conclude that the effects of RYGB on CNS activation in response to visual and gustatory food cues may be mediated by central effects of GLP-1. Our findings provide further insights into the mechanisms underlying the weight-lowering effects of RYGB.

Antidiabetic Drug Alogliptin Protects the Heart Against Ischemia-reperfusion Injury Through GLP-1 Receptor-dependent and Receptor-independent Pathways Involving Nitric Oxide Production in Rabbits.

GLP-1 has been reported to be cardioprotective against ischemia-reperfusion injury. We aimed to examine the effect of alogliptin, which may produce GLP-1, on ischemia-reperfusion injury and its mechanisms. Rabbits were fed a normal chow (control group) and a chow containing alogliptin (2 mg·kg·d: alogliptin-L group and 20 mg·kg·d: alogliptin-H group) for 7 days. The rabbits underwent 30 minutes of coronary occlusion and 48 hours of reperfusion. Exendin (9-39) [5 or 50 µg/kg, i.v., alogliptin-H+exendin (9-39)-L group and alogliptin-H+exendin (9-39)-H group] or L-NAME (10 mg/kg, i.v., alogliptin-H+L-NAME group) was administered to the alogliptin-H group. Alogliptin dose-dependently reduced the infarct size, which was partially blocked by exendin (9-39), but completely blocked by L-NAME. Exendin (9-39) or L-NAME alone did not affect the infarct size for themselves. The left ventricular ejection fraction and ±dP/dt were higher in the alogliptin-L group and alogliptin-H group than in the control group. Alogliptin increased the serum NOx and plasma GLP-1 levels, and those levels inversely correlated with the infarct size. Alogliptin upregulated the expressions of phosphorylated (p)-Akt and p-eNOS, which were inhibited by exendin (9-39) and L-NAME, respectively. In conclusion, alogliptin protects the heart against ischemia-reperfusion injury through GLP-1 receptor-dependent and receptor-independent pathways which involve nitric oxide production in rabbits.

Astilbe thunbergii reduces postprandial hyperglycemia in a type 2 diabetes rat model via pancreatic alpha-amylase inhibition by highly condensed procyanidins.

Type 2 diabetes mellitus (T2DM) is a common global health problem. Prevention of this disease is an important task, and functional food supplements are considered an effective method. We found potent pancreatic α-amylase inhibition in Astilbe thunbergii root extract (AT) and confirmed that AT treatment in a T2DM rat model reduces post-starch administration blood glucose levels. Activity-guided isolation revealed procyanidin (AT-P) as the α-amylase inhibitory component with IC50 = 1.7 µg/mL against porcine pancreatic α-amylase. Structure analysis of AT-P revealed it is a B-type procyanidin comprised of four types of flavan-3-ols, some with a galloyl group, and catechin attached as the terminal unit. The abundant AT-P content and its comparable α-amylase inhibition to acarbose, the anti-diabetic medicine, suggest that AT is a promising food supplement for diabetes prevention.

A Human Glucagon-Like Peptide-1-albumin Recombinant Protein with Prolonged Hypoglycemic Effect Provides Efficient and Beneficial Control of Glucose Metabolism in Diabetic Mice.

GW002 is a recombinant protein engineered by fusing the C-terminal region of human glucagon-like peptide-1 (GLP-1) to the N-terminal region of human serum albumin (HSA) with a peptide linker. This study aims to evaluate its anti-diabetic effects both in vitro and in vivo. The GLP-1 receptor-dependent luciferase reporter plasmid was transiently transfected in NIT-1 cells to calculate the half-maximal concentration (EC50) for GLP-1 receptor activation, and normal ICR mice and diabetic KKAy mice were acutely injected with GW002 (1, 3, 9 mg/kg) subcutaneously to evaluate the hypoglycemic action, while the diabetic KKAy and db/db mice were treated with GW002 once daily for 7 weeks to evaluate the effects on glucose metabolism. The results showed that GW002 activated GLP-1 receptor in NIT-1 cells with higher EC50 versus exendin-4 (46.7 vs. 7.89 nM), and single subcutaneous injection of GW002 at doses of 1, 3 and 9 mg/kg efficiently restrained the glycemia variation after oral glucose loading in ICR mice for at least 4 d, as well as reducing the non-fasting blood glucose in KKAy mice for about 2 d, while repeated injections of GW002 significantly improved abnormal glycaemia, hemoglobin (Hb)A1c levels, oral glucose intolerance and ß-cell function in diabetic db/db mice. These results suggested that GW002 showed prolonged hypoglycemic action by activating its cognate receptor and provided efficient control of glucose metabolism. Thus GW002 may be a potential treatment for the management of type 2 diabetes.

Quantitative Impact of Plasma Clearance and Down-regulation on GLP-1 Receptor Molecular Imaging.

PURPOSE: Quantitative molecular imaging of beta cell mass (BCM) would enable early detection and treatment monitoring of type 1 diabetes. The glucagon-like peptide-1 (GLP-1) receptor is an attractive target due to its beta cell specificity and cell surface location. We quantitatively investigated the impact of plasma clearance and receptor internalization on targeting efficiency in healthy B6 mice. PROCEDURES: Four exenatide-based probes were synthesized that varied in molecular weight, binding affinity, and plasma clearance. The GLP-1 receptor internalization rate and in vivo receptor expression were quantified. RESULTS: Receptor internalization (54,000 receptors/cell in vivo) decreased significantly within minutes, reducing the benefit of a slower-clearing agent. The multimers and albumin binding probes had higher kidney and liver uptake, respectively. CONCLUSIONS: Slow plasma clearance is beneficial for GLP-1 receptor peptide therapeutics. However, for exendin-based imaging of islets, down-regulation of the GLP-1 receptor and non-specific background uptake result in a higher target-to-background ratio for fast-clearing agents.