Endocannabinoid-related molecules predict the metabolic efficacy of GLP-1 receptor agonism in humans with obesity.

OBJECTIVE: N-acylethanolamines (NAEs) include endocannabinoid (EC) and EC-related molecules that impact the anti-obesity and anti-diabetic efficacy of glucagon-like peptide-1 receptor agonists (GLP-1RA) in animal studies. However, the clinical relevance of these findings remains to be determined. Here, we tested whether GLP-1RA treatment affects circulating NAE levels and whether NAEs may predict the efficacy of GLP-1RA treatment in humans with obesity undergoing weight loss maintenance. MATERIALS AND METHODS: We profiled plasma levels of NAEs in participants with obesity undergoing weight loss maintenance with (n = 23)/or without (n = 20) treatment with the GLP-1RA liraglutide. NAE levels were measured at three different time points: before the start of the study, at the end of the diet-induced weight loss, and after 52-weeks treatment. Linear regression analyses were used to investigate whether pharmacological responses could be predicted by NAEs levels. RESULTS: Liraglutide treatment reduced plasma concentrations of the NAE and oleoyl-ethanolamide (OEA), without altering arachidonoyl-ethanolamide (AEA) levels and palmitoyl-ethanolamide (PEA) levels. High pre-treatment levels of OEA were predictive of superior compound-mediated effects on fasting insulin and triglyceride levels. High pre-treatment PEA and AEA levels were also predictive of superior Liraglutide-mediated effects on triglyceride levels. CONCLUSIONS: Our data suggests that specific NAEs such as OEA and AEA are promising biomarkers of GLP-1RA metabolic efficacy in humans with obesity during weight loss maintenance. Plasma profiling of EC-related molecules may be a promising strategy to tailor GLP-1R-based therapies to individual needs in obesity and diabetes management.

Treatment with liraglutide may improve markers of CVD reflected by reduced levels of apoB.

Background: Dislipidaemia and increased levels of apolipoprotein B (apoB) in individuals with obesity are risk factors for development of cardiovascular disease (CVD). The aim of this study was to investigate the effect of weight loss and weight maintenance with and without liraglutide treatment on plasma lipid profiles and apoB. Methods: Fifty-eight individuals with obesity (body mass index 34.5 ± 3.0 kg/m2 [mean ± SD]) were included in this study. After 8 weeks on a very low-calorie diet (800 kcal/day), participants were randomized to weight maintenance with meal replacements with or without liraglutide (1.2 mg daily) for 1 year. Plasma samples from before and after weight loss and after 1 year of weight maintenance were subjected to nuclear magnetic resonance-based lipidomics analysis. Results: After an 8-week low-calorie diet, study participants lost 12.0 ± 2.9 kg (mean ± SD) of their body weight, which was reflected in their lipid profiles (80 out of 124 lipids changed significantly), including reduced levels of apoB, total cholesterol, free cholesterol, remnant cholesterol, triglycerides, low-density lipoprotein and very low-density lipoprotein subclasses. After 1 year of maintained weight loss, the majority of the lipids had returned to pre-weight loss levels even though weight loss was successfully maintained in both groups. Interestingly, apoB levels remained low in the liraglutide treated group (apoB change: 0.03 ± 0.02 mmol/L, p = 0.4) in contrast to an increase in the control group (apoB change: 0.06 ± 0.07 mmol/L, p = 0.02). Conclusion: An 8-week low-calorie diet, in individuals with obesity, reduced plasma levels of lipids and the atherogenic marker apoB. After 1 year of weight maintenance, only study participants treated with liraglutide maintained reduced levels of apoB, despite similar body weight maintenance. Treatment with liraglutide may therefore reduce apoB levels and thus reflect lower CVD risk. Including apoB measurements in clinical practice when monitoring patients with dislipidemia or CVD might prove to be useful.

Chronic intrahypothalamic rather than subcutaneous liraglutide treatment reduces body weight gain and stimulates the melanocortin receptor system.

BACKGROUND: The GLP-1 receptor agonist liraglutide is marketed for obesity treatment where it induces body weight reduction possibly via the hypothalamus, which regulates energy homeostasis. In animal studies, acute liraglutide treatment triggers satiety, weight loss and activates thermogenesis in adipose tissue. However, the precise mechanisms how liraglutide affects in particular chronic weight loss are still under investigation. OBJECTIVES: We aimed to evaluate whether chronic hypothalamic or chronic subcutaneous administration of liraglutide induces sustained weight loss through altered adipose tissue function and to what extent hypothalamic neuronal appetite regulators are involved in the liraglutide-induced weight loss in healthy lean rats on a normal diet. MATERIALS/METHODS: We continuously administered liraglutide either intrahypothalamically (10 µg per day) or subcutaneously (200 µg kg-1 per day) for 28 days to lean Sprague Dawley rats (n=8 each). We assessed changes in body weight, adipose tissue mass, adipocyte size and adipose tissue volume in the abdominal region by using micro-CT. We analyzed genetic expression patterns of browning, thermogenic and adipocyte differentiation regulators in adipose tissues as well as particular neuronal appetite regulators in the hypothalamus. RESULTS: Intrahypothalamic liraglutide administration induced an 8% body weight reduction at day 9 compared with the control group (P<0.01) and a 7% body weight loss at day 9 compared with subcutaneous liraglutide treatment (P<0.01), supported by a significant reduction in adipose tissue mass and volume with intrahypothalamic liraglutide administration (P<0.05). Our data show that chronic intrahypothalamic liraglutide treatment triggered an 18-fold induction of the hypothalamic mc4r gene (P<0.01) accompanied by a significant increase in circulating thyroxine (T4) levels (P<0.05). CONCLUSIONS: Chronic intrahypothalamic liraglutide administration resulted in a profound reduction in body weight and fat mass loss most likely mediated by the hypothalamic melanocortin system rather than by adipose tissue browning or improved thermogenesis.

Treatment with a GLP-1 receptor agonist diminishes the decrease in free plasma leptin during maintenance of weight loss.

BACKGROUND: Recent studies indicate that glucagon-like peptide (GLP)-1 inhibits appetite in part through regulation of soluble leptin receptors. Thus, during weight loss maintenance, GLP-1 receptor agonist (GLP-1RA) administration may inhibit weight loss-induced increases in soluble leptin receptors thereby preserving free leptin levels and preventing weight regain. METHODS: In a randomized controlled trial, 52 healthy obese individuals were, after a diet-induced 12% body weight loss, randomized to treatment with or without administration of the GLP-1RA liraglutide (1.2 mg per day). In case of weight gain, low-calorie diet products were allowed to replace up to two meals per day to achieve equal weight maintenance. Glucose tolerance and hormone responses were investigated before and after weight loss and after 52 weeks weight maintenance. Primary end points: increase in soluble leptin receptor plasma levels and decrease in free leptin index after 52 weeks weight loss maintenance. RESULTS: Soluble leptin receptor increase was 59% lower; 2.1±0.7 vs 5.1±0.8 ng ml(-1) (-3.0 (95% confidence interval (CI)=-0.5 to -5.5)), P<0.001 and free leptin index decrease was 43% smaller; -62±15 vs -109±20 (-47 (95% CI=-11 to -83)), P<0.05 with administration of GLP-1RA compared with control group. The 12% weight loss was successfully maintained in both the groups with no significant change in weight after 52 weeks follow-up. The GLP-1RA group had greater weight loss during the weight maintenance period (-2.3 kg (95% CI=-0.6 to -4.0)), and had fewer meal replacements per day compared with the control group (minus one meal per day (95% CI=-0.6 to -1)), P<0.001. Fasting glucose was decreased by an additional -0.2±0.1 mmol l(-1) in the GLP-1RA group in contrast to the control group, where glucose increased 0.3±0.1 mmol l(-1) to the level before weight loss (-0.5mmol l(-1) (95% CI=-0.1 to -0.9)), P<0.005. Meal response of peptide PYY3-36 was higher at week 52 in the GLP-1RA group compared with the control group, P<0.05. CONCLUSIONS: The weight maintaining effect of GLP-1RAs may be mediated by smaller decrease in free leptin and higher PYY3-36 response. Low dose GLP-1RA therapy maintained 12% weight loss for 1 year and may prevent pre-diabetes in obesity.

A functional amino acid substitution in the glucose-dependent insulinotropic polypeptide receptor (GIPR) gene is associated with lower bone mineral density and increased fracture risk.

CONTEXT: Food ingestion decreases bone resorption, and glucose-dependent insulinotropic polypeptide (GIP) may mediate this effect. Mice overexpressing GIP have increased osteoblast activity and are rescued from age-related bone loss, whereas GIPR knockout mice have decreased cortical bone mass and compromised bone quality. Carriers of the functional variant GIPR Glu354Gln (rs1800437) have higher plasma glucose 2 hours after glucose ingestion, suggesting that the variant encoding GIPR 354Gln decreases the effect of GIP. OBJECTIVE: The objective of the study was to investigate the effect of GIPR Glu354Gln on bone mineral density (BMD) and fracture risk. DESIGN: This was a prospective, comprehensive, cohort study (number NCT00252408). PARTICIPANTS: A total of 1686 perimenopausal women were included. MAIN OUTCOME MEASURES: Dual-energy X-ray absorptiometry was performed at baseline and after 10 years. Incident fractures were recorded during the follow-up and were obtained from the Danish National Patient Registry, giving a total follow-up time of a minimum 16 years. RESULTS: After 10 years, women with the minor frequency C allele of rs1800437 (354Gln) had significantly lower BMD at the femoral neck compared with carriers of the major G-allele (CC: 0.755 ± 0.015 g/cm(2) vs CG: 747 ± 0.005 g/cm(2); GG: 0.766 ± 0.004 g/cm(2), P < .001). Correspondingly, total hip BMD was significantly lower among C allele carriers (CC: 0.881 ± 0.016 g/cm(2); CG: 0.884 ± 0.005 g/cm(2); and GG: 0.906 ± 0.004 g/cm(2), P < .001). Finally, women homozygous for the variant C allele had an increased risk (hazard ratio 1.6, confidence interval 1.0-2.6, P < .05) of nonvertebral fractures. CONCLUSION: This study demonstrates an association between a functional GIPR polymorphism Glu354Gln (rs1800437) and BMD and fracture risk. These findings further establish GIP to be involved in the regulation of bone density.

Dose response of continuous subcutaneous infusion of recombinant glucagon-like peptide-1 in combination with metformin and sulphonylurea over 12 weeks in patients with type 2 diabetes mellitus.

AIMS: Any differences observed between natural glucagon-like peptide-1 (GLP-1) and studies obtained with analogues might call for renewed considerations concerning the use and design of such analogues. Thus, we aimed to evaluate the dose-response relationship of recombinant glucagon-like peptide-1 (7-36) amide (rGLP-1) administered by continuous subcutaneous infusion (CSCI) in subjects with type 2 diabetes. METHODS: We compared the efficacy and safety of three doses of recombinant GLP-1, ranging from 1.25 to 5.0 pmol/kg/min (pkm) and placebo, given by continuous subcutaneous infusion over 3 months in combination with metformin and sulphonylurea (SU), to lower haemoglobin A1c (HbA1c), fasting plasma glucose and weight in 95 type 2 diabetes patients with inadequate glycaemic control. RESULTS: The mean decreases in HbA1c at endpoint (week 12) were significantly greater for all three rGLP-1 dose groups when each was compared with the placebo group, with the greatest decrease occurring in the 5.0 pkm dose group (-1.3%, s.d. ± 0.18, p < 0.001). The mean decreases in fasting plasma glucose from baseline to endpoint were significantly greater for all three rGLP-1 dose groups than for the placebo group, with the greatest decrease occurring in the 5.0 pkm dose group (-26.0 mg/dl, s.d. ± 8.5, p = 0.02). Body weight was significantly reduced by 1.8 kg (s.d. ± 1.3) in the 1.25 pkm dose group only (p = 0.04). CONCLUSIONS: Administration of rGLP-1 by CSCI over a 12-week period in combination with metformin and an SU had a dose dependent effect in lowering HbA1c and fasting plasma glucose. However, administration of rGLP-1 by CSCI may be less effective with respect to lowering of body weight compared with the daily and once weekly analogues.

Impact of postprandial glycaemia on health and prevention of disease.

Postprandial glucose, together with related hyperinsulinemia and lipidaemia, has been implicated in the development of chronic metabolic diseases like obesity, type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). In this review, available evidence is discussed on postprandial glucose in relation to body weight control, the development of oxidative stress, T2DM, and CVD and in maintaining optimal exercise and cognitive performance. There is mechanistic evidence linking postprandial glycaemia or glycaemic variability to the development of these conditions or in the impairment in cognitive and exercise performance. Nevertheless, postprandial glycaemia is interrelated with many other (risk) factors as well as to fasting glucose. In many studies, meal-related glycaemic response is not sufficiently characterized, or the methodology with respect to the description of food or meal composition, or the duration of the measurement of postprandial glycaemia is limited. It is evident that more randomized controlled dietary intervention trials using effective low vs. high glucose response diets are necessary in order to draw more definite conclusions on the role of postprandial glycaemia in relation to health and disease. Also of importance is the evaluation of the potential role of the time course of postprandial glycaemia.

Homozygous carriers of the G allele of rs4664447 of the glucagon gene (GCG) are characterised by decreased fasting and stimulated levels of insulin, glucagon and glucagon-like peptide (GLP)-1.

AIMS/HYPOTHESIS: The glucagon gene (GCG) encodes several hormones important for energy metabolism: glucagon, oxyntomodulin and glucagon-like peptide (GLP)-1 and -2. Variants in GCG may associate with type 2 diabetes, obesity and/or related metabolic traits. METHODS: GCG was re-sequenced as a candidate gene in 865 European individuals. Twenty-nine variants were identified. Four variants that were considered to have a likelihood for altered functionality: rs4664447, rs7581952, Ile158Val and Trp169Ter, were genotyped in 17,584 Danes. RESULTS: When examined in 5,760 treatment-naive individuals, homozygous carriers of the low frequency (minor allele frequency 2.3%) G allele of rs4664447, predicted to disrupt an essential splice enhancer binding site, had lower levels of fasting plasma glucose (mean ± SD, 4.8 ± 1.2 vs 5.5 ± 0.8 mmol/l, p = 0.004); fasting serum insulin (22 ± 14 vs 42 ± 27 pmol/l, p = 0.04); glucose-stimulated serum insulin (159 ± 83 vs 290 ± 183 pmol/l, p = 0.01) and adult height (165 ± 10 vs 172 ± 9 cm, p = 0.0009) compared with A allele carriers. During oral glucose tolerance and hyperglycaemic arginine stimulation tests, the plasma AUC for GLP-1 (730 ± 69 vs 1,334 ± 288 pmol/l × min, p = 0.0002) and basal and stimulated levels of serum insulin and plasma glucagon were ∼50% decreased (p < 0.001) among three homozygous carriers compared with nine matched wild-type carriers. rs7581952, Ile158Val and Trp169Ter (where 'Ter' indicates 'termination') variants of GCG did not significantly associate or co-segregate with the metabolic traits examined. CONCLUSIONS/INTERPRETATION: Re-sequencing of GCG revealed a low frequency intronic variant, rs4664447, and follow-up physiological studies suggest that this variant in homozygous form may cause decreased fasting and stimulated levels of insulin, glucagon and GLP-1. Overall, our findings suggest that variation in GCG has no major impact on carbohydrate metabolism in the study populations examined.

Dose response of subcutaneous GLP-1 infusion in patients with type 2 diabetes.

AIM: To evaluate the dose-response relationship of the recombinant glucagon-like peptide-1 (7-36) amide (rGLP-1) administered by continuous subcutaneous infusion (CSCI) in subjects with type 2 diabetes, with respect to reductions in fasting, postprandial and 11-h serum glucose profiles. METHODS: In a double-blind, parallel, placebo-controlled trial, 47 patients were randomized to placebo or rGLP-1 (1.25, 2.5, 5.0 or 8.5 pmol/kg/min) by CSCI for 7 days. On day 1 (pretreatment) and on day 8, patients underwent monitoring of fasting, postprandial, and 11-h profiles of glucose and hormones. RESULTS: Fasting serum glucose decreased by 76.2, 53.9, 37.0 and 22.7 mg/dl for the 8.5, 5.0, 2.5 and 1.25 pmol/kg/min rGLP-1 groups, respectively, compared to a decrease of 1.1 mg/dl for placebo (p = 0.0002, 0.005, 0.064 and 0.27, respectively). Mean 11-h serum glucose area under the curve decreased by 36.3, 23.3, 16.9 and 10.0% for 8.5, 5.0, 2.5 and 1.25 pmol/kg/min rGLP-1, respectively, compared to no change for placebo (p = 0.0001, 0.0019, 0.012 and 0.14, respectively). Mean fasting C-peptide increased dose dependently with rGLP-1 (p = 0.0023 for the highest dose) and decreased with placebo. There were no serious safety concerns and no instances of hypoglycaemia. CONCLUSIONS: rGLP-1 produced continuous improvements in glycaemic control across a broad dose range of up to 8.5 pmol/kg/min.

Obesity - an indication for GLP-1 treatment? Obesity pathophysiology and GLP-1 treatment potential.

Obesity is common and associated with a high rate of morbidity and mortality; therefore, treatment is of great interest. At present, bariatric surgery is the only truly successful treatment of severe obesity. Mimicking one of the effects of bariatric surgery, namely the increased secretion of glucagon-like peptide (GLP)-1, by artificially increasing the levels of GLP-1 might prove successful as obesity treatment. Recent studies have shown that GLP-1 is a physiological regulator of appetite and food intake. The effect on food intake and satiety is preserved in obese subjects and GLP-1 may therefore have a therapeutic potential. The GLP-1 analogues result in a moderate average weight loss, which is clinically relevant in relation to reducing the risk of type 2 diabetes and cardiovascular disease. Inspired by the hormone profile after gastric bypass, a future strategy in obesity drug development could be to combine several hormones, and thereby produce a superior appetite suppressing hormone profile that may result in a weight loss exceeding that seen in single-agent trials. In conclusion, with the GLP-1 analogues combining a moderate weight loss with beneficial effects on metabolic and cardiovascular risk factors, it seems that we are on the right track for future treatment of obesity.

An overview of once-weekly glucagon-like peptide-1 receptor agonists--available efficacy and safety data and perspectives for the future.

Incretin-based therapies, such as the injectable glucagon-like peptide-1 (GLP-1) receptor agonists and orally administered dipeptidyl peptidase-4 (DPP-4) inhibitors, have recently been introduced into clinical practice. At present, the GLP-1 receptor agonists need to be administered once or twice daily. Several once-weekly GLP-1 receptor agonists are in phase 3 development. This review examines the efficacy, safety and perspective for the future of the once-weekly GLP-1 receptor agonists: exenatide once weekly, taspoglutide, albiglutide, LY2189265 and CJC-1134-PC, and compared them to the currently available agonists, exenatide BID and liraglutide QD. A greater reduction in haemoglobin A1c (HbA1c) and fasting plasma glucose was found with the once-weekly GLP-1 receptor agonists compared with exenatide BID, while the effect on postprandial hyperglycaemia was modest with the once-weekly GLP-1 receptor agonist. The reduction in HbA1c was in most studies greater compared to oral antidiabetic drugs and insulin glargine. The reduction in weight did not differ between the short- and long-acting agonists. The gastrointestinal side effects were less with the once-weekly agonists compared with exenatide BID, except for taspoglutide. Antibodies seem to be most frequent with exenatide once weekly, while hypersensitivity has been described in few patients treated with taspoglutide. Injection site reactions differ among the long-acting GLP-1 receptor agonists and are observed more frequently than with exenatide BID and liraglutide. In humans, no signal has been found indicating an association between the once-weekly agonists and C-cell cancer. The cardiovascular safety, durability of glucose control and effect on weight will emerge from several ongoing major long-term trials. The once-weekly GLP-1 receptor analogues are promising candidates for the treatment of type 2 diabetes, although their efficacy may not be superior to once-daily analogue liraglutide.

Genetic analysis of the estrogen-related receptor alpha and studies of association with obesity and type 2 diabetes.

BACKGROUND: The estrogen-related receptor alpha (ERRalpha or NR3B1) is a transcription factor from the nuclear receptor super-family, group III. The gene encoding ERRalpha (ESRRA) is located on chromosome 11q13, a region showing genetic linkage to body mass index and fat percentage. Through interaction with the peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha), ERRalpha regulates key enzymes involved in the beta-oxidation of fatty acids. RESULTS: By screening 48 overweight or obese subjects for variants in the exons, exon-intron boundaries and 1000 base pairs (bp) of the promoter region of ESRRA using bi-directional nucleotide sequencing, we identified seven variants. Four rare variants had minor allele frequencies (MAF) below 1%: Pro369Pro, Gly406Asp, 3'UTR+418G>A, 3'UTR+505C>A. Two single-nucleotide polymorphisms, Pro116Pro and IVS6+65C>T (MAF 15%), were in complete linkage disequilibrium (LD) (r (2)=1). We also confirmed the presence of a reported 23 bp microsatellite repeat (ESRRA23). The Pro116Pro and ESRRA23 variants were not associated with obesity, type 2 diabetes or related phenotypes in a large population-based study of 6365 Danish whites. The two variants were examined for interactions with variants in the peroxisome proliferator-activated receptor-gamma coactivator-1alpha and -beta; however, no evidence of epistatic effects between the variants was demonstrated. CONCLUSION: The ESRRA23 and Pro116Pro variants of the gene encoding ERRalpha are not associated with obesity, type 2 diabetes or related quantitative traits in the examined Danish whites.

Variants in the 5' region of the neuropeptide Y receptor Y2 gene (NPY2R) are associated with obesity in 5,971 white subjects.

AIMS/HYPOTHESIS: The gene encoding neuropeptide Y receptor Y2 (NPY2R) is widely expressed in the central nervous system, with particularly high abundance in the hypothalamus, which is known to be important for appetite regulation. We tested whether variations in NPY2R are associated with obesity. METHODS: The coding region of NPY2R was analysed for mutations in 48 obese Danish white subjects and two silent substitutions were identified: SNPs 1 and 2 (rs1047214 and rs2880415). SNP1 and additional reported variants (SNPs 3-6 [rs11099992, rs12649641, rs2342676 and rs6857530]) located in the 5' region were examined in 5,971 Danish white subjects. Since SNPs 1-2 and 4-6, respectively, were in tight linkage disequilibrium large-scale analyses of genetic epidemiology were restricted to SNPs 1, 3 and 4. RESULTS: Homozygous carriers of the minor A allele of SNP4 were more common among obese subjects; the AA frequency was 15.9 (95% CI 15.2-16.6) among 4,837 non-obese subjects (BMI <30 kg/m(2)) vs 19.0 (95% CI 17.2-20.8) among 960 obese subjects (BMI > or =30 kg/m(2)), odds ratio 1.24 (95% CI 1.04-1.48), p=0.02. SNPs 1-3 were not associated with obesity. CONCLUSIONS/INTERPRETATION: Common variants rs12649641, rs2342676 and rs6857530 in the 5' region of NPY2R are associated with obesity in Danish white subjects.