Showing papers by "Filip K. Knop published in 2018"

Recovery of gut microbiota of healthy adults following antibiotic exposure

Abstract: To minimize the impact of antibiotics, gut microorganisms harbour and exchange antibiotics resistance genes, collectively called their resistome. Using shotgun sequencing-based metagenomics, we analysed the partial eradication and subsequent regrowth of the gut microbiota in 12 healthy men over a 6-month period following a 4-day intervention with a cocktail of 3 last-resort antibiotics: meropenem, gentamicin and vancomycin. Initial changes included blooms of enterobacteria and other pathobionts, such as Enterococcus faecalis and Fusobacterium nucleatum, and the depletion of Bifidobacterium species and butyrate producers. The gut microbiota of the subjects recovered to near-baseline composition within 1.5 months, although 9 common species, which were present in all subjects before the treatment, remained undetectable in most of the subjects after 180 days. Species that harbour β-lactam resistance genes were positively selected for during and after the intervention. Harbouring glycopeptide or aminoglycoside resistance genes increased the odds of de novo colonization, however, the former also decreased the odds of survival. Compositional changes under antibiotic intervention in vivo matched results from in vitro susceptibility tests. Despite a mild yet long-lasting imprint following antibiotics exposure, the gut microbiota of healthy young adults are resilient to a short-term broad-spectrum antibiotics intervention and their antibiotics resistance gene carriage modulates their recovery processes.

Glucagon-like peptide 1 in health and disease.

Abstract: In healthy individuals, the incretin hormone glucagon-like peptide 1 (GLP1) potentiates insulin release and suppresses glucagon secretion in response to the ingestion of nutrients. GLP1 also delays gastric emptying and increases satiety. In patients with type 2 diabetes mellitus (T2DM), supraphysiological doses of GLP1 normalize the endogenous insulin response during a hyperglycaemic clamp. Owing to the short plasma half-life of native GLP1, several GLP1 receptor agonists (GLP1RAs) with longer half-lives have been developed for the treatment of T2DM. These compounds vary in chemical structure, pharmacokinetics and size, which results in different clinical effects on hyperglycaemia and body weight loss; these variations might also explain the difference in cardiovascular effect observed in large-scale cardiovascular outcome trials, in which certain GLP1RAs were shown to have a positive effect on cardiovascular outcomes. Owing to their metabolic effects, GLP1RAs are also considered for the treatment of several other lifestyle-induced conditions, such as obesity, prediabetes and liver disease. This Review provides insights into the physiology of GLP1 and its involvement in the pathophysiology of T2DM and an overview of the currently available and emerging GLP1RAs. Furthermore, we review the results from the currently available large-scale cardiovascular outcome trials and the use of GLP1RAs for other indications.

Metformin-induced glucagon-like peptide-1 secretion contributes to the actions of metformin in type 2 diabetes

Abstract: BACKGROUND. Metformin reduces plasma glucose and has been shown to increase glucagon-like peptide 1 (GLP-1) secretion. Whether this is a direct action of metformin on GLP-1 release, and whether some of the glucose-lowering effect of metformin occurs due to GLP-1 release, is unknown. The current study investigated metformin-induced GLP-1 secretion and its contribution to the overall glucose-lowering effect of metformin and underlying mechanisms in patients with type 2 diabetes. METHODS. Twelve patients with type 2 diabetes were included in this placebo-controlled, double-blinded study. On 4 separate days, the patients received metformin (1,500 mg) or placebo suspended in a liquid meal, with subsequent i.v. infusion of the GLP-1 receptor antagonist exendin9-39 (Ex9-39) or saline. During 240 minutes, blood was sampled. The direct effect of metformin on GLP-1 secretion was tested ex vivo in human ileal and colonic tissue with and without dorsomorphin-induced inhibiting of the AMPK activity. RESULTS. Metformin increased postprandial GLP-1 secretion compared with placebo (P = 0.014), and the postprandial glucose excursions were significantly smaller after metformin + saline compared with metformin + Ex9-39 (P = 0.004). Ex vivo metformin acutely increased GLP-1 secretion (colonic tissue, P < 0.01; ileal tissue, P < 0.05), but the effect was abolished by inhibition of AMPK activity. CONCLUSIONS. Metformin has a direct and AMPK-dependent effect on GLP-1–secreting L cells and increases postprandial GLP-1 secretion, which seems to contribute to metformin’s glucose-lowering effect and mode of action. TRIAL REGISTRATION. {"type":"clinical-trial","attrs":{"text":"NCT02050074","term_id":"NCT02050074"}}NCT02050074 (https://clinicaltrials.gov/ct2/show/{"type":"clinical-trial","attrs":{"text":"NCT02050074","term_id":"NCT02050074"}}NCT02050074). FUNDING. This study received grants from the A.P. Moller Foundation, the Novo Nordisk Foundation, the Danish Medical Association research grant, the Australian Research Council, the National Health and Medical Research Council, and Pfizer Inc.

Enteroendocrine K and L cells in healthy and type 2 diabetic individuals.

Abstract: Enteroendocrine K and L cells are pivotal in regulating appetite and glucose homeostasis Knowledge of their distribution in humans is sparse and it is unknown whether alterations occur in type 2 diabetes We aimed to evaluate the distribution of enteroendocrine K and L cells and relevant prohormone-processing enzymes (using immunohistochemical staining), and to evaluate the mRNA expression of the corresponding genes along the entire intestinal tract in individuals with type 2 diabetes and healthy participants In this cross-sectional study, 12 individuals with type 2 diabetes and 12 age- and BMI-matched healthy individuals underwent upper and lower double-balloon enteroscopy with mucosal biopsy retrieval from approximately every 30 cm of the small intestine and from seven specific anatomical locations in the large intestine Significantly different densities for cells positive for chromogranin A (CgA), glucagon-like peptide-1, glucose-dependent insulinotropic polypeptide, peptide YY, prohormone convertase (PC) 1/3 and PC2 were observed along the intestinal tract The expression of CHGA did not vary along the intestinal tract, but the mRNA expression of GCG, GIP, PYY, PCSK1 and PCSK2 differed along the intestinal tract Lower counts of CgA-positive and PC1/3-positive cells, respectively, were observed in the small intestine of individuals with type 2 diabetes compared with healthy participants In individuals with type 2 diabetes compared with healthy participants, the expression of GCG and PYY was greater in the colon, while the expression of GIP and PCSK1 was greater in the small intestine and colon, and the expression of PCSK2 was greater in the small intestine Our findings provide a detailed description of the distribution of enteroendocrine K and L cells and the expression of their products in the human intestinal tract and demonstrate significant differences between individuals with type 2 diabetes and healthy participants NCT03044860

The Role of Glucagon in the Pathophysiology and Treatment of Type 2 Diabetes.

Abstract: Type 2 diabetes is a disease involving both inadequate insulin levels and increased glucagon levels. While glucagon and insulin work together to achieve optimal plasma glucose concentrations in healthy individuals, the usual regulatory balance between these 2 critical pancreatic hormones is awry in patients with diabetes. Although clinical discussion often focuses on the role of insulin, glucagon is equally important in understanding type 2 diabetes. Furthermore, an awareness of the role of glucagon is essential to appreciate differences in the mechanisms of action of various classes of glucose-lowering therapies. Newer drug classes such as dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists improve glycemic control, in part, by affecting glucagon levels. This review provides an overview of the effect of glucose-lowering therapies on glucagon on the basis of an extensive PubMed literature search to identify clinical studies of glucose-lowering therapies in type 2 diabetes that included assessment of glucagon. Clinical practice currently benefits from available therapies that impact the glucagon regulatory pathway. As clinicians look to the future, improved treatment strategies are likely to emerge that will either use currently available therapies whose mechanisms of action complement each other or take advantage of new therapies based on an improved understanding of glucagon pathophysiology.

Evidence of a liver–alpha cell axis in humans: hepatic insulin resistance attenuates relationship between fasting plasma glucagon and glucagonotropic amino acids

Abstract: The secretion of glucagon is controlled by blood glucose and inappropriate secretion of glucagon contributes to hyperglycaemia in diabetes. Besides its role in glucose regulation, glucagon regulates amino acid metabolism in hepatocytes by increasing ureagenesis. Disruption of this mechanism causes hyperaminoacidaemia, which in turn increases glucagon secretion. We hypothesised that hepatic insulin resistance (secondary to hepatic steatosis) via defective glucagon signalling/glucagon resistance would lead to impaired ureagenesis and, hence, increased plasma concentrations of glucagonotropic amino acids and, subsequently, glucagon. To examine the association between glucagon and amino acids, and to explore whether this relationship was modified by hepatic insulin resistance, we studied a well-characterised cohort of 1408 individuals with normal and impaired glucose regulation. In this cohort, we have previously reported insulin resistance to be accompanied by increased plasma concentrations of glucagon. We now measure plasma levels of amino acids in the same cohort. HOMA-IR was calculated as a marker of hepatic insulin resistance. Fasting levels of glucagonotropic amino acids and glucagon were significantly and inversely associated in linear regression models (persisting after adjustment for age, sex and BMI). Increasing levels of hepatic, but not peripheral insulin resistance (p > 0.166) attenuated the association between glucagon and circulating levels of alanine, glutamine and tyrosine, and was significantly associated with hyperaminoacidaemia and hyperglucagonaemia. A doubling of the calculated glucagon–alanine index was significantly associated with a 30% increase in hepatic insulin resistance, a 7% increase in plasma alanine aminotransferase levels, and a 14% increase in plasma γ-glutamyltransferase levels. This cross-sectional study supports the existence of a liver–alpha cell axis in humans: glucagon regulates plasma levels of amino acids, which in turn feedback to regulate the secretion of glucagon. With hepatic insulin resistance, reflecting hepatic steatosis, the feedback cycle is disrupted, leading to hyperaminoacidaemia and hyperglucagonaemia. The glucagon–alanine index is suggested as a relevant marker for hepatic glucagon signalling.

GIP(3 - 30)NH 2 is an efficacious GIP receptor antagonist in humans: a randomised, double-blinded, placebo-controlled, crossover study

Abstract: Glucose-dependent insulinotropic polypeptide (GIP) is an incretin hormone secreted postprandially from enteroendocrine K cells, but despite therapeutically interesting effects, GIP physiology in humans remains incompletely understood. Progress in this field could be facilitated by a suitable GIP receptor antagonist. For the first time in humans, we investigated the antagonistic properties of the naturally occurring GIP(3-30)NH2 in in vivo and in in vitro receptor studies. In transiently transfected COS-7 cells, GIP(3-30)NH2 was evaluated with homologous receptor binding and receptor activation (cAMP accumulation) studies at the glucagon-like peptide 1 (GLP-1), glucagon-like peptide-2 (GLP-2), glucagon, secretin and growth hormone-releasing hormone (GHRH) receptors. Ten healthy men (eligibility criteria: age 20–30 years, HbA1c less than 6.5% [48 mmol/mol] and fasting plasma glucose [FPG] less than 7 mmol/l) were included in the clinical study. Data were collected as plasma and serum samples from a cubital vein cannula. As primary outcome, insulin secretion and glucose requirements were evaluated together with in a randomised, four-period, crossover design by infusing GIP(3-30)NH2 (800 pmol kg−1 min−1), GIP (1.5 pmol kg−1 min−1), a combination of these or placebo during hyperglycaemic clamp experiments. The content of the infusions were blinded to the study participants and experimental personnel. No study participants dropped out. GIP(3-30)NH2 neither bound, stimulated nor antagonised a series of related receptors in vitro. The elimination plasma half-life of GIP(3-30)NH2 in humans was 7.6 ± 1.4 min. Markedly larger amounts of glucose were required to maintain the clamp during GIP infusion compared with the other days. GIP-induced insulin secretion was reduced by 82% (p < 0.0001) during co-infusion with GIP(3-30)NH2, and the need for glucose was reduced to placebo levels. There were no effects of GIP(3-30)NH2 alone or of GIP with or without GIP(3-30)NH2 on plasma glucagon, GLP-1, somatostatin, triacylglycerols, cholesterol, glycerol or NEFA. GIP(3-30)NH2 administration was well tolerated and without side effects. We conclude that GIP(3-30)NH2 is an efficacious and specific GIP receptor antagonist in humans suitable for studies of GIP physiology and pathophysiology. ClinicalTrials.gov registration no. NCT02747472. The study was funded by Gangstedfonden, the European Foundation for the Study of Diabetes, and Aase og Ejnar Danielsens fond.

Future Perspectives on GLP-1 Receptor Agonists and GLP-1/glucagon Receptor Co-agonists in the Treatment of NAFLD

Abstract: Along the obesity pandemic, the prevalence of non-alcoholic fatty liver disease (NAFLD), often regarded as the hepatic manifestation of the metabolic syndrome, increases worldwide representing now the prevalent liver disease in western countries. No pharmacotherapy is approved for the treatment of NAFLD and, currently, the cornerstone treatment is lifestyle modifications focusing on bodyweight loss, notoriously difficult to obtain and even more difficult to maintain. Thus, novel therapeutic approaches are highly demanded. Glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1RAs) are approved for the treatment of type 2 diabetes and obesity. They exert their body weight-lowering effect by reducing satiety and food intake. GLP-1RAs have also been shown to reduce liver inflammation and fibrosis. Furthermore, glucagon receptor agonism is being investigated for the treatment of NAFLD due to its appetite and food intake-reducing effects, as well as its ability to increase lipid oxidation and thermogenesis. Recent studies suggest that glucagon receptor signaling is disrupted in NAFLD, indicating that supra-physiological glucagon receptor agonism might represent a new NAFLD treatment target. The present review provides (1) an overview in the pathophysiology of NAFLD, including the potential involvement of GLP-1 and glucagon, (2) an introduction to the currently available GLP-1RAs and (3) outlines the potential of emerging GLP-1RAs and GLP-1/glucagon receptor co-agonists in the treatment of NAFLD.

FGF21, a liver hormone that inhibits alcohol intake in mice, increases in human circulation after acute alcohol ingestion and sustained binge drinking at Oktoberfest.

Abstract: Objective Excessive alcohol consumption is a leading cause of global morbidity and mortality. However, knowledge of the biological factors that influence ad libitum alcohol intake may be incomplete. Two large studies recently linked variants in the KLB locus with levels of alcohol intake in humans. KLB encodes β-klotho, co-receptor for the liver-derived hormone fibroblast growth factor 21 (FGF21). In mice, FGF21 reduces alcohol intake, and human Fgf21 variants are enriched among heavy drinkers. Thus, the liver may limit alcohol consumption by secreting FGF21. However, whether full-length, active plasma FGF21 (FGF21 (1–181)) levels in humans increase acutely or sub-chronically in response to alcohol ingestion is uncertain. Methods We recruited 10 healthy, fasted male subjects to receive an oral water or alcohol bolus with concurrent blood sampling for FGF21 (1–181) measurement in plasma. In addition, we measured circulating FGF21 (1–181) levels, liver stiffness, triglyceride, and other metabolic parameters in three healthy Danish men before and after consuming an average of 22.6 beers/person/day (4.4 g/kg/day of ethanol) for three days during Oktoberfest 2017 in Munich, Germany. We further correlated fasting FGF21 (1–181) levels in 49 healthy, non-alcoholic subjects of mixed sex with self-reports of alcohol-related behaviors, emotional responses, and problems. Finally, we characterized the effect of recombinant human FGF21 injection on ad libitum alcohol intake in mice. Results We show that alcohol ingestion (25.3 g or ∼2.5 standard drinks) acutely increases plasma levels of FGF21 (1–181) 3.4-fold in fasting humans. We also find that binge drinking for three days at Oktoberfest is associated with a 2.1-fold increase in baseline FGF21 (1–181) levels, in contrast to minor deteriorations in metabolic and hepatic biomarkers. However, basal FGF21 (1–181) levels were not correlated with differences in alcohol-related behaviors, emotional responses, or problems in our non-alcoholic subjects. Finally, we show that once-daily injection of recombinant human FGF21 reduces ad libitum alcohol intake by 21% in mice. Conclusions FGF21 (1–181) is markedly increased in circulation by both acute and sub-chronic alcohol intake in humans, and reduces alcohol intake in mice. These observations are consistent with a role for FGF21 as an endocrine inhibitor of alcohol appetite in humans.

Glucose-Dependent Insulinotropic Polypeptide (GIP) Inhibits Bone Resorption Independently of Insulin and Glycemia

Abstract: Context The gut hormone glucose-dependent insulinotropic polypeptide (GIP) causes postprandial insulin release and inhibits bone resorption assessed by carboxy-terminal collagen crosslinks (CTX). Objective To study if GIP affects bone homeostasis biomarkers independently of insulin release and glycemic level. Design Randomized, double-blinded, crossover study with 5 study days. Patients Ten male C-peptide-negative patients with type 1 diabetes. Interventions On 3 matched days with "low glycemia" (plasma glucose in the interval 3 to 7 mmol/L for 120 minutes), we administered intravenous (IV) GIP (4 pmol × kg-1 × min-1), glucagon-like peptide 1 (1 pmol × kg-1 × min-1), or placebo (saline), and on 2 matched days with "high glycemia" (plasma glucose 12 mmol/L for 90 minutes), we administered either GIP or saline. Main Outcome Measures CTX, procollagen type 1 N-terminal propeptide (P1NP), and parathyroid hormone (PTH). Results During low glycemia: GIP progressively suppressed CTX from baseline by up to 59 ± 18% compared with 24 ± 10% during saline infusion (P < 0.0001). Absolute values of P1NP and PTH did not differ between days. During high glycemia: GIP suppressed CTX from baseline by up to 59 ± 19% compared with 7 ± 9% during saline infusion (P < 0.0001). P1NP did not differ between days. GIP suppressed PTH after 60 minutes compared with saline (P < 0.01), but this difference disappeared after 90 minutes. Conclusions Short-term GIP infusions robustly reduce bone resorption independently of endogenous insulin secretion and during both elevated and low plasma glucose, but have no effect on P1NP or PTH after 90 minutes.

Hyperglucagonemia correlates with plasma levels of non-branched-chain amino acids in patients with liver disease independent of type 2 diabetes.

Abstract: Hypersecretion of glucagon (hyperglucagonemia) has been suggested to be linked to type 2 diabetes. Here, we show that levels of amino acids correlate with levels of glucagon. Hyperglucagonemia may ...

Hemodynamic Effects of Glucagon: A Literature Review.

Abstract: Context Glucagon's effects on hemodynamic parameters, most notably heart rate and cardiac contractility, are often overlooked. The glucagon receptor is a central target in novel and anticipated type 2 diabetes therapies, and hemodynamic consequences of glucagon signaling have therefore become increasingly important. In this review, we summarize and evaluate published studies on glucagon pharmacology with a focus on clinical hemodynamic effects in humans. Evidence Acquisition PubMed, Embase, and the Cochrane Library were searched for clinical studies concerning hemodynamic effects of glucagon (no year restriction). Papers reporting effects of a defined glucagon dose on any hemodynamic parameter were included. Reference searches were conducted in retrieved articles. Evidence Synthesis Hemodynamic effects of glucagon have been investigated mainly in cohort studies of patients suffering from heart failure receiving large glucagon bolus injections. The identified studies had shortcomings related to restricted patient groups, lack of a control group, randomization, or blinding. We identified no properly conducted randomized clinical trials. The majority of human studies report stimulating effects of pharmacological glucagon doses on heart rate, cardiac contractility, and blood pressure. The effects were characterized by short duration, interindividual variation, and rapid desensitization. Some studies reported no measurable effects of glucagon. Conclusions The level of evidence regarding hemodynamic effects of glucagon is low, and observations in published studies are inconsistent. Actual effects, interindividual variation, dose-response relationships, and possible long-term effects of supraphysiological glucagon levels warrant further investigation.

EJE PRIZE 2018: A gut feeling about glucagon

Abstract: Hyperglucagonaemia (in the fasting as well as in the postprandial state) is considered a core pathophysiological component of diabetes and is found to contribute substantially to the hyperglycaemic state of diabetes. Hyperglucagonaemia is usually viewed upon as a consequence of pancreatic alpha cell insensitivity to the glucagon-suppressive effects of glucose and insulin. Since we observed that the well-known hyperglucagonaemic response to oral glucose in patients with type 2 diabetes is exchanged by normal suppression of plasma glucagon levels following isoglycaemic intravenous glucose administration in these patients, we have been focusing on the gut and gut-derived factors as potential mediators of diabetic hyperglucagonaemia. In a series of clinical experiments, we have elucidated the role of gut-derived factors in diabetic hyperglucagonaemia and shown that glucose-dependent insulinotropic polypeptide promotes hyperglucagonaemia and that glucagon, hitherto considered a pancreas-specific hormone, may also be secreted from extrapancreatic tissues - most likely from proglucagon-producing enteroendocrine cells. Furthermore, our observation that fasting hyperglucagonaemia is unrelated to the diabetic state, but strongly correlates with obesity, liver fat content and circulating amino acids, has made us question the common 'pancreacentric' and 'glucocentric' understanding of hyperglucagonaemia and led to the hypothesis that steatosis-induced hepatic glucagon resistance (and reduced amino acid turnover) and compensatory glucagon secretion mediated by increased circulating amino acids constitute a complete endocrine feedback system: the liver-alpha cell axis. This article summarises the physiological regulation of glucagon secretion in humans and considers new findings suggesting that the liver and the gut play key roles in determining fasting and postabsorptive circulating glucagon levels.

Effects of glucagon-like peptide-1 receptor agonists on cardiovascular risk factors: A narrative review of head-to-head comparisons.

Abstract: Cardiovascular (CV) disease is the leading cause of death and morbidity in patients with type 2 diabetes. Five CV risk factors (blood pressure, resting heart rate, body weight, cholesterol levels and blood glucose) are monitored routinely as safety and efficacy endpoints in randomized clinical trials for diabetes therapies. To determine if different glucagon-like peptide-1 receptor agonists (GLP-1RAs) had varying effects on these CV risk factors, we reviewed 16 head-to-head trials directly comparing GLP-1RAs that included at least one of the five factors. Few trials reported statistical differences between GLP-1RAs in terms of systolic blood pressure (SBP), body weight and total cholesterol. Liraglutide increased heart rate vs its comparators in three separate trials. All GLP-1RAs reduced glycated haemoglobin (HbA1c), but exenatide twice daily and lixisenatide had statistically smaller effects compared with other GLP-1RAs. These descriptive data indicate that individual GLP-1RAs affect CV risk factors differently, potentially because of their individual pharmacokinetics and/or size. Short-acting GLP-1RAs appeared to result in smaller changes in SBP and total cholesterol compared with continuous-acting treatments, while large GLP-1RAs had a reduced effect on body weight compared with small GLP-1RAs. For glycaemic control, short-acting GLP-1RAs had a greater impact on postprandial glucose levels vs continuous-acting GLP-1RAs, but for fasting plasma glucose levels and HbA1c, continuous-acting treatments had the greater effect. No differentiating trends were obvious in heart rate data. These diverse actions of GLP-1RAs on CV risk factors should aid individualized patient treatment.

The bile acid-sequestering resin sevelamer eliminates the acute GLP-1 stimulatory effect of endogenously released bile acids in patients with type 2 diabetes

Abstract: Aims Discovery of the specific bile acid receptors farnesoid X receptor (FXR) and Takeda G protein-coupled receptor 5 (TGR5) in enteroendocrine L cells has prompted research focusing on the impact of bile acids on glucagon-like peptide-1 (GLP-1) secretion and glucose metabolism. The aim of the present study was to assess the GLP-1 secretory and gluco-metabolic effects of endogenously released bile, with and without concomitant administration of the bile acid-sequestering resin, sevelamer, in patients with type 2 diabetes. Materials and Methods We performed a randomized, placebo-controlled, double-blinded cross-over study including 15 metformin-treated patients with type 2 diabetes. During 4 experimental study days, either sevelamer 3200 mg or placebo in combination with intravenous infusion of cholecystokinin (CCK) (0.4 pmol sulfated CCK-8/kg/min) or saline was administered in randomized order. The primary endpoint was plasma GLP-1 excursions as measured by incremental area under the curve. Secondary endpoints included plasma responses of glucose, triglycerides, insulin, CCK, fibroblast growth factor-19 and 7α-hydroxy-4-cholesten-3-one (C4). In addition, gallbladder dynamics, gastric emptying, resting energy expenditure, appetite and ad libitum food intake were assessed. Results CCK-mediated gallbladder emptying was demonstrated to elicit a significant induction of GLP-1 secretion compared to saline, whereas concomitant single-dose administration of the bile acid sequestrant sevelamer was shown to eliminate the acute bile acid-induced increase in plasma GLP-1 excursions. Conclusions Single-dose administration of sevelamer eliminated bile acid-mediated GLP-1 secretion in patients with type 2 diabetes, which could be explained by reduced bile acid stimulation of the basolaterally localized TGR5 on enteroendocrine L cells.

Adaptive changes in pancreas post Roux-en-Y gastric bypass induced weight loss.

Abstract: Background Obesity has been shown to trigger adaptive increases in pancreas parenchymal and fat volume. Consecutively, pancreatic steatosis may lead to beta-cell dysfunction. However, it is not known whether the pancreatic tissue components decrease with weight loss and pancreatic steatosis is reversible following Roux-en-Y gastric bypass (RYGB). Therefore, the objective of the study was to investigate the effects of RYGB-induced weight loss on pancreatic volume and glucose homeostasis. Methods Eleven patients were recruited in the Obesity Centre of the University Medical Centre Hamburg-Eppendorf. Before and 6 months after RYGB, total GLP-1 levels were measured during oral glucose tolerance test. To assess changes in visceral adipose tissue and pancreatic volume, MRI was performed. Measures of glucose homeostasis and insulin indices were assessed. Fractional beta-cell area was estimated by correlation with the C-peptide-to-glucose ratio; beta-cell mass was calculated by the product of beta-cell area and pancreas parenchymal weight. Results Pancreas volume decreased from 83.8 (75.7-92.0) to 70.5 (58.8-82.3) cm3 (mean [95% CI], P = .001). The decrease in total volume was associated with a significant decrease in fat volume. Fasting insulin and C-peptide were lower post RYGB. HOMA-IR levels decreased, whereas insulin sensitivity increased (P = .03). This was consistent with a reduction in the estimated beta-cell area and mass. Conclusions Following RYGB, pancreatic volume and steatosis adaptively decreased to "normal" levels with accompanying improvement in glucose homeostasis. Moreover, obesity-driven beta-cell expansion seems to be reversible; however, future studies must define a method to more accurately estimate functional beta-cell mass to increase our understanding of glucose homeostasis after RYGB.

FGF21, a liver hormone that inhibits alcohol intake in mice, increases in human circulation after acute alcohol ingestion and sustained binge drinking at Oktoberfest

Abstract: Objective: Excessive alcohol consumption is a leading cause of global morbidity and mortality. However, knowledge of the biological factors that influence ad libitum alcohol intake may be incomplete. Two large studies recently linked variants in the KLB locus with levels of alcohol intake in humans. KLB encodes β-klotho, co-receptor for the liver-derived hormone fibroblast growth factor 21 (FGF21). In mice, FGF21 reduces alcohol intake, and human Fgf21 variants are enriched among heavy drinkers. Thus, the liver may limit alcohol consumption by secreting FGF21. However, whether full-length, active plasma FGF21 (FGF21 (1-181)) levels in humans increase acutely or sub-chronically in response to alcohol ingestion is uncertain. Methods: We recruited 10 healthy, fasted male subjects to receive an oral water or alcohol bolus with concurrent blood sampling for FGF21 (1-181) measurement in plasma. In addition, we measured circulating FGF21 (1-181) levels, liver stiffness, triglyceride, and other metabolic parameters in three healthy Danish men before and after consuming an average of 22.6 beers/person/day (4.4 g/kg/day of ethanol) for three days during Oktoberfest 2017 in Munich, Germany. We further correlated fasting FGF21 (1-181) levels in 49 healthy, non-alcoholic subjects of mixed sex with self-reports of alcohol-related behaviors, emotional responses, and problems. Finally, we characterized the effect of recombinant human FGF21 injection on ad libitum alcohol intake in mice. Results: We show that alcohol ingestion (25.3 grams or ~2.5 standard drinks) acutely increases plasma levels of FGF21 (1-181) 3.4-fold in fasting humans. We also find that binge drinking for three days at Oktoberfest is associated with a 2.1-fold increase in baseline FGF21 (1-181) levels, in contrast to minor deteriorations in metabolic and hepatic biomarkers. However, basal FGF21 (1-181) levels were not correlated with differences in alcohol-related behaviors, emotional responses, or problems in our non-alcoholic subjects. Finally, we show that once-daily injection of recombinant human FGF21 reduces ad libitum alcohol intake by 21% in mice. Conclusions: FGF21 (1-181) is markedly increased in circulation by both acute and sub-chronic alcohol intake in humans, and reduces alcohol intake in mice. These observations are consistent with a role for FGF21 as an endocrine inhibitor of alcohol appetite in humans.

Effects of liraglutide on gallbladder emptying: A randomized, placebo-controlled trial in adults with overweight or obesity

Abstract: Aims Treatment with liraglutide 3.0 mg has been associated with gallbladder-related adverse events. To conduct a single-centre, double-blind, 12-week trial comparing the effect of 0.6 mg liraglutide and steady-state liraglutide 3.0 mg with placebo on gallbladder emptying in adults with body mass index (BMI) ≥27 kg/m2 and without diabetes. Methods Participants were randomized 1:1 to once-daily subcutaneous liraglutide (n = 26) or placebo (n = 26), starting at 0.6 mg with 0.6-mg weekly increments to 3.0 mg, with nutritional and physical activity counselling. A 600-kcal (23.7 g fat) liquid meal test was performed at baseline, after the first dose and after 12 weeks. The primary endpoint was the 12-week maximum postprandial gallbladder ejection fraction (GBEFmax ), measured over 240 minutes after starting the meal. Results Baseline characteristics were similar between groups (mean ± SD overall age 47.6 ± 10.0 years, BMI 32.6 ±3.4 kg/m2 , 50% women). Mean 12-week GBEFmax (treatment difference -3.7%, 95% confidence interval [CI] -13.1, 5.7) and area under the GBEF curve in the first 60 minutes (-390% × min, 95% CI -919, 140) did not differ for liraglutide 3.0 mg (n = 23) vs placebo (n = 24). The median (range) time to GBEFmax was 151 (11-240) minutes with liraglutide 3.0 mg and 77 (22-212) minutes with placebo. Similar findings were noted after the first 0.6-mg liraglutide dose. Gastrointestinal disorders, notably nausea and constipation, were the most frequently reported adverse events. Conclusions Treatment with liraglutide did not affect the GBEFmax but appeared to prolong the time to GBEFmax .

Determinants of Fasting Hyperglucagonemia in Patients with Type 2 Diabetes and Nondiabetic Control Subjects

Abstract: Background: Fasting hyperglucagonemia can be detrimental to glucose metabolism in patients with type 2 diabetes (T2D) and may contribute to metabolic disturbances in obese and/or prediabet...

Glucose‐lowering effects and mechanisms of the bile acid‐sequestering resin sevelamer

Abstract: Aims Sevelamer, a non-absorbable amine-based resin used for treatment of hyperphosphataemia, has been demonstrated to have a marked bile acid-binding potential alongside beneficial effects on lipid and glucose metabolism. The aim of this study was to investigate the glucose-lowering effect and mechanism(s) of sevelamer in patients with type 2 diabetes. Materials and methods In this double-blinded randomized controlled trial, we randomized 30 patients with type 2 diabetes to sevelamer (n = 20) or placebo (n = 10). Participants were subjected to standardized 4-hour liquid meal tests at baseline and after 7 days of treatment. The main outcome measure was plasma glucagon-like peptide-1 excursions as measured by area under the curve. In addition, blood was sampled for measurements of glucose, lipids, glucose-dependent insulinotropic polypeptide, C-peptide, glucagon, fibroblast growth factor-19, cholecystokinin and bile acids. Assessments of gastric emptying, resting energy expenditure and gut microbiota composition were performed. Results Sevelamer elicited a significant placebo-corrected reduction in plasma glucose with concomitant reduced fibroblast growth factor-19 concentrations, increased de novo synthesis of bile acids, a shift towards a more hydrophilic bile acid pool and increased lipogenesis. No glucagon-like peptide-1-mediated effects on insulin, glucagon or gastric emptying were evident, which points to a limited contribution of this incretin hormone to the glucose-lowering effect of sevelamer. Furthermore, no sevelamer-mediated effects on gut microbiota composition or resting energy expenditure were observed. Conclusions Sevelamer reduced plasma glucose concentrations in patients with type 2 diabetes by mechanisms that seemed to involve decreased intestinal and hepatic bile acid-mediated farnesoid X receptor activation.

Comparing Olive Oil and C4-dietary Oil, a Prodrug for the GPR119 Agonist, 2-oleoyl Glycerol, Less Energy Intake of the Latter Is Needed to Stimulate Incretin Hormone Secretion in Overweight Subjects With Type 2 Diabetes

Abstract: After digestion, dietary triacylglycerol stimulates incretin release in humans, mainly through generation of 2-monoacylglycerol, an agonist for the intestinal G protein-coupled receptor 119 (GPR119). Enhanced incretin release may have beneficial metabolic effects. However, dietary fat may promote weight gain and should therefore be restricted in obesity. We designed C4-dietary oil (1,3-di-butyryl-2-oleoyl glycerol) as a 2-oleoyl glycerol (2-OG)-generating fat type, which would stimulate incretin release to the same extent while providing less calories than equimolar amounts of common triglycerides, e.g., olive oil. We studied the effect over 180 min of (a) 19 g olive oil plus 200 g carrot, (b) 10.7 g C4 dietary oil plus 200 g carrot and (c) 200 g carrot, respectively, on plasma responses of gut and pancreatic hormones in 13 overweight patients with type 2 diabetes (T2D). Theoretically, both oil meals result in formation of 7.7 g 2-OG during digestion. Both olive oil and C4-dietary oil resulted in greater postprandial (P ≤ 0.01) glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) responses (incremental area under curve (iAUC)): iAUCGLP−1: 645 ± 194 and 702 ± 97 pM × min; iAUCGIP: 4,338 ± 764 and 2,894 ± 601 pM × min) compared to the carrot meal (iAUCGLP−1: 7 ± 103 pM × min; iAUCGIP: 266 ± 234 pM × min). iAUC for GLP-1 and GIP were similar for C4-dietary oil and olive oil, although olive oil resulted in a higher peak value for GIP than C4-dietary oil. C4-dietary oil enhanced secretion of GLP-1 and GIP to almost the same extent as olive oil, in spite of liberation of both 2-OG and oleic acid, which also may stimulate incretin secretion, from olive oil. Thus, C4-dietary oil is more effective as incretin releaser than olive oil per unit of energy and may be useful for dietary intervention.

Cholecystokinin secretion is suppressed by glucagon-like peptide-1: clue to the mechanism of the adverse gallbladder events of GLP-1-derived drugs

Abstract: Objective: Recent randomized and controlled trials of drugs derived from the gut hormone glucagon-like peptide-1 (GLP-1) show that the most frequent adverse symptoms are gastrointestinal, including...

Cardiovascular biomarkers in clinical studies of type 2 diabetes.

Abstract: When planning cardiovascular (CV) studies in type 2 diabetes (T2D), selection of CV biomarkers is a complex issue. Because the pathophysiology of CV disease (CVD) in T2D is multifactorial, ideally, the selected CV biomarkers should cover all aspects of the known pathophysiology of the disease. This will allow the researcher to distinguish between effects on different aspects of the pathophysiology. To this end, we discuss a host of biomarkers grouped according to their role in the pathogenesis of CVD, namely: (1) cardiac damage biomarkers; (2) inflammatory biomarkers; and (3) novel biomarkers (oxidative stress and endothelial dysfunction biomarkers). Within each category we present the best currently validated biomarkers, with special focus on the population of interest (people with T2D). For each individual biomarker, we discuss the physiological role, validation in the general population and in people with T2D, analytical methodology, modifying factors, effects of glucose-lowering drugs, and interpretation. This approach will provide clinical researchers with the information necessary for planning, conducting and interpreting results from clinical trials. Furthermore, a systematic approach to selection of CV biomarkers in T2D research will improve the quality of future research.

A gut feeling about glucagon

Abstract: Hyperglucagonaemia (in the fasting as well as in the postprandial state) is considered a core pathophysiological component of diabetes and is found to contribute substantially to the hyperglycaemic state of diabetes. Hyperglucagonaemia is usually viewed upon as a consequence of pancreatic alpha cell insensitivity to the glucagonsuppressive effects of glucose and insulin. Since we observed that the well-known hyperglucagonaemic response to oral glucose in patients with type 2 diabetes is exchanged by normal suppression of plasma glucagon levels following isoglycaemic intravenous glucose administration in these patients, we have been focusing on the gut and gut-derived factors as potential mediators of diabetic hyperglucagonaemia. In a series of clinical experiments, we have elucidated the role of gut-derived factors in diabetic hyperglucagonaemia and shown that glucose-dependent insulinotropic polypeptide promotes hyperglucagonaemia and that glucagon, hitherto considered a pancreas-specific hormone, may also be secreted from extrapancreatic tissues – most likely from proglucagon-producing enteroendocrine cells. Furthermore, our observation that fasting hyperglucagonaemia is unrelated to the diabetic state, but strongly correlates with obesity, liver fat content and circulating amino acids, has made us question the common ‘pancreacentric’ and ‘glucocentric’ understanding of hyperglucagonaemia and led to the hypothesis that steatosisinduced hepatic glucagon resistance (and reduced amino acid turnover) and compensatory glucagon secretion mediated by increased circulating amino acids constitute a complete endocrine feedback system: the liver–alpha cell axis. This article summarises the physiological regulation of glucagon secretion in humans and considers new findings suggesting that the liver and the gut play key roles in determining fasting and postabsorptive circulating glucagon levels. Correspondence should be addressed to F K Knop Email filip.knop@regionh.dk European Journal of Endocrinology (2018) 178, R267–R280

Bone Turnover Markers in Patients With Nonalcoholic Fatty Liver Disease and/or Type 2 Diabetes During Oral Glucose and Isoglycemic Intravenous Glucose.

Abstract: Context Nonalcoholic fatty liver disease (NAFLD) is associated with type 2 diabetes (T2D) and vice versa, and both conditions are associated with an increased risk of fractures and altered bone turnover. Although patients with NAFLD typically suffer from decreased bone mineral density (BMD), T2D is associated with normal to high BMD. The pathophysiology is uncertain but may involve the gut-bone axis. Objective We investigated the influence of the gut on glucose-induced changes in plasma bone turnover markers in healthy controls and patients with T2D and/or biopsy-verified NAFLD. Design Cross-sectional cohort study. Patients Patients with NAFLD with normal glucose tolerance, patients with NAFLD and T2D, patients with T2D without liver disease, and healthy controls. Interventions Four-hour 50-g oral glucose tolerance test (OGTT) and an isoglycemic intravenous glucose infusion (IIGI). Main Outcome Measures Collagen type 1 C-telopeptide (CTX), osteocalcin, procollagen type 1 N-terminal propeptide (P1NP), and parathyroid hormone. Results Plasma glucose levels achieved during OGTTs were successfully matched on corresponding IIGI days. Patients with NAFLD and T2D exhibited similar CTX suppression during the two glucose challenges (P = 0.46) and pronounced suppression of P1NP during IIGI compared with OGTT. Conversely, remaining groups showed greater (P < 0.05) CTX suppression during OGTT and similar suppression of bone formation markers during IIGI and OGTT. Conclusions OGTT-induced CTX suppression seems to be impaired in patients with NAFLD and T2D, but preserved in patients with either NAFLD or T2D, suggesting that coexistence of T2D and NAFLD may affect gut-bone axis.

Differences Between Randomized Clinical Trial Patients and Real-World Initiators of the Glucagon-Like Peptide 1 Receptor Agonist Liraglutide

Abstract: Randomized controlled trials (RCTs) are considered the gold standard for determining efficacy and safety of new drugs. Successful randomization addresses known and unknown confounding when assessing a drug’s effect among trial patients selected on strict inclusion and exclusion criteria (1). However, treatment results have been shown on occasion to be much less favorable than expected outside trial populations, often related to differences in age, comorbidity, disease severity, drug compliance, and/or comedication among patients treated in everyday clinical practice (1). The risk of adverse drug effects may also be higher among patients treated in routine clinical care. Liraglutide, a glucagon-like peptide 1 receptor agonist, was quickly adopted by clinicians following its approval by the European Medicines Agency in 2009 and by the U.S. Food and Drug Administration in 2010. Approval was based on a number of phase III RCTs called the Liraglutide Effect and Action in Diabetes (LEAD) 1–5 trials (2). We used data from Danish population-based medical databases to examine whether routine clinical care liraglutide initiators would have been eligible for participation in …

Ghrelin secretion in humans - a role for the vagus nerve?

Abstract: BACKGROUND Ghrelin, an orexigenic peptide, is secreted from endocrine cells in the gastric mucosa. Circulating levels rise in the preprandial phase, suggesting an anticipatory or cephalic phase of release, and decline in the postprandial phase, suggesting either the loss of a stimulatory factor or inhibition by factors released when nutrients enter the intestine. We hypothesized that vagal signals are not required for the (i) preprandial increase or (ii) postprandial suppression of ghrelin levels. Further, we wanted to investigate the hypothesis that (iii) glucagon-like peptide-1 might be implicated in the postprandial decline in ghrelin levels. METHODS We measured ghrelin levels in plasma from sham-feeding and meal studies carried out in vagotomized individuals and controls, and from a GLP-1 infusion study carried out in fasting healthy young individuals. KEY RESULTS We find that (i) ghrelin secretion is unchanged during indirect vagal stimulation as elicited by modified sham-feeding in vagotomized individuals and matched controls, (ii) ghrelin secretion is similarly suppressed after meal ingestion in vagotomized individuals and controls, and (iii) infusion of GLP-1 does not lower ghrelin levels. CONCLUSIONS & INFERENCES We conclude that for postprandial suppression of circulating ghrelin levels, a circulating factor (but not GLP-1) or short (duodeno-gastric) reflexes seem to be implicated.

Model-Based Prediction of Plasma Concentration and Enterohepatic Circulation of Total Bile Acids in Humans

Abstract: Bile acids released postprandially can modify the rate and extent of lipophilic compounds' absorption. This study aimed to predict the enterohepatic circulation (EHC) of total bile acids (TBAs) in response to caloric intake from their spillover in plasma. A model for TBA EHC was combined with a previously developed gastric emptying (GE) model. Longitudinal gallbladder volumes and TBA plasma concentration data from 30 subjects studied after ingestion of four different test drinks were supplemented with literature data. Postprandial gallbladder refilling periods were implemented to improve model predictions. The TBA hepatic extraction was reduced with the high-fat drink. Basal and nutrient-induced gallbladder emptying rates were altered by type 2 diabetes (T2D). The model was predictive of the central trend and the variability of gallbladder volume and TBA plasma concentration for all test drinks. Integration of this model within physiological pharmacokinetic modeling frameworks could improve the predictions for lipophilic compounds' absorption considerably.

Effects of Smoking Versus Nonsmoking on Postprandial Glucose Metabolism in Heavy Smokers Compared With Nonsmokers

Abstract: OBJECTIVE Epidemiological studies suggest that smoking increases the risk of type 2 diabetes. We hypothesized that smoking-derived nicotine and ensuing activation of nicotinic cholinergic receptors in the gastrointestinal tract and the autonomic nervous system would have a detrimental effect on postprandial glucose metabolism and, thus, potentially constitute a link between smoking and the development of type 2 diabetes. RESEARCH DESIGN AND METHODS We subjected 11 male heavy smokers to two identical 4-h liquid mixed-meal tests: one with concomitant cigarette smoking (immediately before and after meal intake) and one without smoking. Twelve age-, sex-, and BMI-matched nonsmokers underwent an identical meal test without smoking. RESULTS The smokers were characterized by higher fasting plasma concentrations of glucagon compared with the nonsmokers. Among smokers, cigarette smoking before and after the meal significantly reduced postprandial plasma glucose excursions. There were no differences in gut or pancreatic hormone concentrations between the test days in the smoking group, and the responses were similar to those in the control group. CONCLUSIONS Our results suggest that smoking in association with meal intake decreases the postprandial plasma glucose concentrations, possibly through decreased gastric emptying, and that elevated fasting glucagon concentrations rather than smoking-induced alterations in postprandial glucose and hormone responses may be associated with the elevated risk of type 2 diabetes in chronic smokers.