Glucagon-like peptide-1 and blood pressure in young and healthy adults from the general population

Hypertension Related to Obesity: Pathogenesis, Characteristics and Factors for Control

The World Health Organization (WHO) refers to obesity as abnormal or excessive fat accumulation that presents a health risk. Obesity was first designated as a disease in 2012 and since then the cost and the burden of the disease have witnessed a worrisome increase. Obesity and hypertension are closely interrelated as abdominal obesity interferes with the endocrine and immune systems and carries a greater risk for insulin resistance, diabetes, hypertension, and cardiovascular disease. Many factors are at the interplay between obesity and hypertension. They include hemodynamic alterations, oxidative stress, renal injury, hyperinsulinemia, and insulin resistance, sleep apnea syndrome and the leptin-melanocortin pathway. Genetics, epigenetics, and mitochondrial factors also play a major role. The measurement of blood pressure in obese patients requires an adapted cuff and the search for other secondary causes is necessary at higher thresholds than the general population. Lifestyle modifications such as diet and exercise are often not enough to control obesity, and so far, bariatric surgery constitutes the most reliable method to achieve weight loss. Nonetheless, the emergence of new agents such as Semaglutide and Tirzepatide offers promising alternatives. Finally, several molecular pathways are actively being explored, and they should significantly extend the treatment options available.

Fasting and stimulated glucagon-like peptide-1 exhibit a compensatory adaptive response in diabetes and pre-diabetes states: A multi-ethnic comparative study

BACKGROUND

Impaired secretion of glucagon-like peptide-1 (GLP-1) among Caucasians contributes to reduced incretin effect in type 2 diabetes mellitus (T2DM) patients. However, studies emanating from East Asia suggested preserved GLP-1 levels in pre-diabetes (pre-DM) and T2DM. We aimed to resolve these conflicting findings by investigating GLP-1 levels during oral glucose tolerance test (OGTT) among Malay, Chinese, and Indian ethnicities with normal glucose tolerance (NGT), pre-DM, and T2DM. The association between total GLP-1 levels, insulin resistance, and insulin sensitivity, and GLP-1 predictors were also analyzed.

METHODS

A total of 174 subjects were divided into NGT (n=58), pre-DM (n=54), and T2DM (n=62). Plasma total GLP-1 concentrations were measured at 0, 30, and 120 min during a 75-g OGTT. Homeostasis model assessment of insulin resistance (HOMA-IR), HOMA of insulin sensitivity (HOMA-IS), and triglyceride-glucose index (TyG) were calculated.

RESULTS

Total GLP-1 levels at fasting and 30 min were significantly higher in T2DM compared with pre-DM and NGT (27.18 ± 11.56 pmol/L vs. 21.99 ± 10.16 pmol/L vs. 16.24 ± 7.79 pmol/L, p=0.001; and 50.22 ± 18.03 pmol/L vs. 41.05 ± 17.68 pmol/L vs. 31.44 ± 22.59 pmol/L, p<0.001; respectively). Ethnicity was a significant determinant of AUC_GLP-1, with the Indians exhibiting higher GLP-1 responses than Chinese and Malays. Indians were the most insulin resistant, whereas Chinese were the most insulin sensitive. The GLP-1 levels were positively correlated with HOMA-IR and TyG but negatively correlated with HOMA-IS. This relationship was evident among Indians who exhibited augmented GLP-1 responses proportionately to their high insulin-resistant states.

CONCLUSION

This is the first study that showed GLP-1 responses are augmented as IR states increase. Fasting and post-OGTT GLP-1 levels are raised in T2DM and pre-DM compared to that in NGT. This raises a possibility of an adaptive compensatory response that has not been reported before. Among the three ethnic groups, the Indians has the highest IR and GLP-1 levels supporting the notion of an adaptive compensatory secretion of GLP-1.

Blood pressure control in type 2 diabetes mellitus with arterial hypertension. The important ancillary role of SGLT2-inhibitors and GLP1-receptor agonists

Type 2 diabetes mellitus and arterial hypertension are major cardiovascular risks factors which shares metabolic and haemodynamic abnormalities as well as pathophysiological mechanisms. The simultaneous presence of diabetes and arterial hypertension increases the risk of left ventricular hypertrophy, congestive heart failure, and stroke, as compared to either condition alone. A number of guidelines recommend lifestyle measures such as salt restriction, weight reduction and ideal body weight mainteinance, regular physical activity and smoking cessation, together with moderation of alcohol consumption and high intake of vegetables and fruits, as the basis for reduction of blood pressure and prevention of CV diseases. Despite the availability of multiple drugs effective for hypertension, BP targets are reached in only 50 % of patients, with even fewer individuals with T2DM-achieving goals. It is established that new emerging classes of type 2 diabetes mellitus treatment, SGLT2 inhibitors and GLP1-receptor agonists, are efficacious on glucose control, and safe in reducing HbA1c significantly, without increasing hypoglycemic episodes. Furthermore, in recent years, many CVOT trials have demonstrated, using GLP1-RA or SGLT2-inihibitors compared to placebo (in combination with the usual diabetes medications) important benefits on reducing MACE (cardio-cerebral vascular events) in the diabetic population. In this hypothesis-driven review, we have examined the anti-hypertensive effects of these novel molecules of the two different classes, in the diabetic population, and suggest that they could have an interesting ancillary role in controlling blood pressure in type 2 diabetic patients.

Effect of liraglutide on blood pressure: a meta-analysis of liraglutide randomized controlled trials

BACKGROUND

Several clinical trials have studied the effects of glucagon-like peptide-1 receptor agonists (GLP-1RAs) on glycometabolism and cardiovascular risk factors since they were identified. Because of their cardiovascular benefits and efficacy in lowering glucose, GLP-1RAs are becoming increasingly important in clinical therapy for patients with or without pathoglycaemia. The aim of this study was to assess the effect of the GLP-1RA liraglutide on blood pressure based on randomised controlled trials (RCTs).

METHODS

We searched PubMed for RCTs published from 2009 to 2018 comparing the effect of liraglutide on blood pressure with that of placebo in individuals with or without pathoglycaemia. RCTs in humans that included data describing blood pressure changes from baseline to the end of the trial were selected for inclusion in the meta-analysis.

RESULTS

A total of 18 RCTs that enrolled 7616 individuals in the liraglutide group and 6046 individuals in the control group were included in this meta-analysis. Compared with placebo, liraglutide reduced systolic blood pressure (SBP) by 3.18 mmHg (95% CI -4.32, - 2.05), P < 0.00001, but had no significant effect on diastolic blood pressure (DBP). Subgroup analysis showed that the degree of reduction in SBP was associated with the dose of liraglutide but that significance disappeared when the intervention lasted over 1 year. Liraglutide 3.0 mg/d significantly reduced DBP by 1.46 mmHg (95% CI -2.61, 0.32), P = 0.01, but liraglutide 1.8 mg/d slightly increased DBP by 0.47 mmHg (95% CI 0.11, 0.83), P = 0.01, compared with placebo.

CONCLUSIONS

This meta-analysis demonstrated that liraglutide significantly reduced SBP in individuals with or without pathoglycaemia compared with placebo, but the difference was no longer significant when the intervention lasted over 1 year. Moreover, the effect of liraglutide on blood pressure is associated with the dose. This finding may provide additional evidence for cardiovascular protection.

Different mechanisms involved in liraglutide and glucagon-like peptide-1 vasodilatation in rat mesenteric small arteries

BACKGROUND AND PURPOSE

Glucagon-like peptide-1 (GLP-1) is an incretin hormone that regulates insulin biosynthesis and secretion in a glucose-dependent manner and has been reported to induce vasodilatation. Here, we examined the possible vasorelaxant effect of GLP-1 and its underlying mechanisms.

EXPERIMENTAL APPROACH

Rat mesenteric arteries (diameter ≈ 200-400 μm) and human s.c. arteries were mounted in microvascular myographs for isometric tension recordings. The effect of GLP-1 on vascular responses was examined under normoglycaemic conditions and at high glucose concentrations.

KEY RESULTS

In rat mesenteric arteries and human s.c. arteries without branches, physiological concentrations (1-100 nM) of GLP-1(7-36) and liraglutide failed to cause relaxation or affect contractions evoked by electrical field stimulation. In contrast to GLP-1(7-36), liraglutide induced relaxations antagonized by the GLP-1 receptor antagonist, exendin-(9-39), in branched mesenteric arteries. In contrast to liraglutide, GLP-1 leftward shifted the concentration relaxation curves for bradykinin in s.c. arteries from patients with peripheral arterial disease, an effect resistant to exendin-(9-39). Under normoglycaemic conditions, neither GLP-1 nor liraglutide affected ACh relaxation in rat mesenteric arteries. In arteries exposed to 40 mM glucose, GLP-1, in contrast to liraglutide, potentiated ACh-induced relaxation by a mechanism that was not antagonized by exendin-(9-39). GLP-1 decreased superoxide levels measured with dihydroethidium in rat mesenteric arteries exposed to 40 mM glucose.

CONCLUSIONS AND IMPLICATIONS

GLP-1 receptors are involved in the liraglutide-induced relaxation of branched arteries, under normoglycaemic conditions, while GLP-1 inhibition of vascular superoxide levels contributes to GLP-1 receptor-independent potentiation of endothelium-dependent vasodilatation in hyperglycaemia.

Gut microbiota, hypertension and chronic kidney disease: Recent advances

A large number of different microbial species populates intestine. Extensive research has studied the entire microbial population and their genes (microbiome) by using metagenomics, metatranscriptomics and metabolomic analysis. Studies suggest that the imbalances of the microbial community causes alterations in the intestinal homeostasis, leading to repercussions on other systems: metabolic, nervous, cardiovascular, immune. These studies have also shown that alterations in the structure and function of the gut microbiota play a key role in the pathogenesis and complications of Hypertension (HTN) and Chronic Kidney Disease (CKD). Increased blood pressure (BP) and CKD are two leading risk factors for cardiovascular disease and their treatment represents a challenge for the clinicians. In this Review, we discuss mechanisms whereby gut microbiota (GM) and its metabolites act on downstream cellular targets to contribute to the pathogenesis of HTN and CKD, and potential therapeutic implications.

Bariatric Surgery and Hypertension

Obesity continues to increase in prevalence worldwide. Hypertension has long been associated with obesity, and weight loss continues to be a first-line therapy in the treatment of hypertension. Lifestyle modification and pharmacologic therapy, however, often meet with treatment failure. Bariatric surgery continues to be the most successful approach to sustained weight loss. This review focuses on the underlying physiologic mechanisms of obesity-hypertension, and the impact of bariatric surgery on the treatment of hypertension. Current available literature on the physiologic mechanisms of obesity-hypertension, and the major trials, meta-analyses and systematic reviews of the impact of bariatric surgery procedures on hypertension are reviewed. Evidence suggests significant improvement in obesity-hypertension in patients who undergo surgical weight-reduction procedures. Malabsorptive techniques such as the Roux-en-Y gastric bypass or surgical resection techniques such as laparoscopic sleeve gastrectomy appear to offer superior results in regards to hypertension control over restrictive techniques such as Gastric Banding. Though long-term control of hypertension following surgery remains a concern, available follow-up post-operative data of up to 10 years suggests a sustained, if lessened, effect on hypertension control over time.

Healthy lifestyle and glucagon-like peptide-1 in young and healthy adults: A population-based study

A healthy lifestyle is associated with a lower risk of cardiovascular events and mortality, but underlying mechanisms are not fully understood. The aim of our study was to investigate the relationships between a healthy lifestyle and glucagon-like peptide-1 (GLP-1), an incretin hormone with both glycemic and cardiovascular properties. Healthy participants aged 25-41years without cardiovascular disease, diabetes or a body mass index (BMI) >35kg/m² were enrolled in a population-based study. The following metrics were used to build a lifestyle score ranging from 0 to 7 (a higher score indicating a healthier lifestyle): blood pressure (BP) (<120/80mmHg), plasma levels of glycated hemoglobin (<5.7%), total cholesterol levels (<200mg/dl), BMI (<25kg/m²), not smoking cigarettes, moderate (≥150min/week) or vigorous (≥75min/week) physical activity and a healthy diet. Among 2133 participants median age was 36.7years and 53.3% were female. GLP-1 levels decreased significantly from 39.5 to 30.9ng/l (p<0.0001) across increasing lifestyle score categories. This linear relationship persisted in multivariable adjusted linear regression models (B for GLP-1 per 1-unit increase of the lifestyle score -0.06; 95% confidence intervals -0.07, -0.04; p<0.0001). Individual health metrics that were significantly associated with GLP-1 were a normal BMI (-0.07; -0.12, -0.03; p=0.001), low total cholesterol levels (-0.07; -0.12, -0.03; p=0.001), normal BP (-0.05; -0.10, -0.00; p=0.047) and not smoking (-0.06; -0.10, -0.01; p=0.01). A healthy lifestyle is strongly associated with lower GLP-1 levels in young and healthy adults.

Relationships of iron metabolism with insulin resistance and glucose levels in young and healthy adults

AIMS

Several biomarkers within the iron metabolism pathway have been related to the occurrence of diabetes mellitus, but underlying mechanisms are unknown. The aim of our study was to investigate the differential relationships of iron metabolism with a broad range of diabetes markers in young and healthy adults.

DESIGN

2160 participants aged 25 to 41years were enrolled in a population-based study. Established cardiovascular disease, diabetes or a body mass index >35kg/m(2) were exclusion criteria. Multivariable linear regression models were built to assess the associations of ferritin and transferrin saturation (TSAT) with blood levels of glucagon-like peptide-1 (GLP-1), insulin, homeostatic model assessment-insulin resistance (HOMA-IR), fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c).

RESULTS

Median (interquartile range) age was 37 (31, 40) years. In multivariable linear regression analyses, β-coefficients (95% confidence intervals) per 1-SD increase in ferritin were 0.04 (0.02; 0.07, p=0.0008) for GLP-1, 0.06 (0.04; 0.08, p<0.0001) for insulin, 0.07 (0.04; 0.09, p<0.0001) for HOMA-IR, 0.004 (-0.00; 0.01, p=0.07) for FPG and -0.003 (-0.01; -0.00, p=0.07) for HbA1c. β-coefficients (95% CI) per 1-SD increase in TSAT were -0.07 (-0.09; -0.05, p<0.0001) for GLP-1, -0.06 (-0.08; -0.04, p<0.0001) for insulin, -0.07(-0.09; -0.05, p<0.0001) for HOMA-IR, -0.01 (-0.01; -0.00, p<0.0001) for FPG and -0.01 (-0.01; -0.00, p=0.0004) for HbA1c.

CONCLUSIONS

Markers of insulin resistance are strongly related with markers of iron metabolism in healthy subjects. These relationships were inconsistent and weaker for short-term and long-term glucose levels. These results may provide insights in the relationships between iron metabolism and diabetes occurrence.

Plasma levels of glucagon-like peptide 1 and markers of obesity among young and healthy adults

OBJECTIVE

Glucagon-like peptide 1 (GLP-1)-related pathways may partially explain the strong relationship between obesity and type 2 diabetes. We therefore aimed to evaluate the relationships between fasting GLP-1 levels, body fat mass and other obesity markers in a large sample of young and healthy adults.

DESIGN AND PATIENTS

Our population-based study included 2096 individuals aged 24-44. Exclusion criteria were prevalent cardiovascular disease, diabetes or a body mass index (BMI) >35 kg/m(2) . Body fat mass was obtained by bioelectrical impedance analysis. Multivariable linear regression models were constructed to assess the relationships of GLP-1 with various measures of body composition.

RESULTS

Median age of our population was 37 years, median BMI 24·1 kg/m(2) and median body fat 25·1%. A strong positive correlation was observed in age-adjusted models between GLP-1 and fat mass in men (β (95% confidence interval) 1·38 (0·69; 2·07), P < 0·001) and women (1·27 (0·65; 1·89), P < 0·001) as well as fully adjusted models including BMI in men [0·87 (0·27; 1·46), P < 0·01] but not women [0·29 (-0·07; 0·64), P = 0·11]. The relationships of GLP-1 with BMI for men and women [0·00 (-0·34; 0·34), P = 0·99] [-0·02 (-0·28; 0·25), P = 0·91] and waist circumference [0·43 (-0·45; 1·30), P = 0·34] [0·37 (-0·44; 1·18), P = 0·37], respectively, were not significant after multivariable adjustment including fat mass.

CONCLUSION

Among young and healthy adults, GLP-1 levels are strongly and independently related to body fat mass especially in men but not BMI or waist circumference. These results raise the hypothesis that GLP-1 may be implicated in body fat mass regulation.

A Novel GLP1 Receptor Interacting Protein ATP6ap2 Regulates Insulin Secretion in Pancreatic Beta Cells

GLP1 activates its receptor, GLP1R, to enhance insulin secretion. The activation and transduction of GLP1R requires complex interactions with a host of accessory proteins, most of which remain largely unknown. In this study, we used membrane-based split ubiquitin yeast two-hybrid assays to identify novel GLP1R interactors in both mouse and human islets. Among these, ATP6ap2 (ATPase H(+)-transporting lysosomal accessory protein 2) was identified in both mouse and human islet screens. ATP6ap2 was shown to be abundant in islets including both alpha and beta cells. When GLP1R and ATP6ap2 were co-expressed in beta cells, GLP1R was shown to directly interact with ATP6ap2, as assessed by co-immunoprecipitation. In INS-1 cells, overexpression of ATP6ap2 did not affect insulin secretion; however, siRNA knockdown decreased both glucose-stimulated and GLP1-induced insulin secretion. Decreases in GLP1-induced insulin secretion were accompanied by attenuated GLP1 stimulated cAMP accumulation. Because ATP6ap2 is a subunit required for V-ATPase assembly of insulin granules, it has been reported to be involved in granule acidification. In accordance with this, we observed impaired insulin granule acidification upon ATP6ap2 knockdown but paradoxically increased proinsulin secretion. Importantly, as a GLP1R interactor, ATP6ap2 was required for GLP1-induced Ca(2+) influx, in part explaining decreased insulin secretion in ATP6ap2 knockdown cells. Taken together, our findings identify a group of proteins that interact with the GLP1R. We further show that one interactor, ATP6ap2, plays a novel dual role in beta cells, modulating both GLP1R signaling and insulin processing to affect insulin secretion.