ABSTRACT
AIMS: Pancreatic polypeptide (PP) is elevated in people with vascular risk factors such as type 2 diabetes or increased visceral fat. We investigated potential relationships between PP and microvascular and macrovascular complications of diabetes. MATERIALS AND METHODS: Animal study: Subcutaneous PP infusion for 4 weeks in high fat diet mouse model. Retinal mRNA submitted for Ingenuity Pathway Analysis. Human study: fasting PP measured in 1478 participants and vascular complications recorded over median 5.5 (IQR 4.9-5.8) years follow-up. RESULTS: Animal study: The retinal transcriptional response to PP was indicative of cellular stress and damage, and this footprint matched responses described in previously published studies of retinal disease. Of mechanistic importance the transcriptional landscape was consistent with upregulation of folliculin, a recently identified susceptibility gene for diabetic retinopathy. Human study: Adjusting for established risk factors, PP was associated with prevalent and incident clinically significant retinopathy (odds ratio (OR) 1.289 (1.107-1.501) p = 0.001; hazard ratio (HR) 1.259 (1.035-1.531) p = 0.0213), albuminuria (OR 1.277 (1.124-1.454), p = 0.0002; HR 1.608 (1.208-2.141) p = 0.0011), and macrovascular disease (OR 1.021 (1.006-1.037) p = 0.0068; HR 1.324 (1.089-1.61), p = 0.0049), in individuals with type 2 diabetes, and progression to diabetes in non-diabetic individuals (HR 1.402 (1.081-1.818), p = 0.0109). CONCLUSIONS: Elevated fasting PP is independently associated with vascular complications of diabetes and affects retinal pathways potentially influencing retinal neuronal survival. Our results suggest possible new roles for PP-fold peptides in the pathophysiology of diabetes complications and vascular risk stratification.
Subject(s)
Diabetes Mellitus, Type 2 , Diabetic Angiopathies , Diabetic Retinopathy , Fasting , Diabetes Mellitus, Type 2/complications , Diabetes Mellitus, Type 2/pathology , Humans , Male , Female , Middle Aged , Diabetic Angiopathies/etiology , Diabetic Angiopathies/epidemiology , Animals , Mice , Follow-Up Studies , Diabetic Retinopathy/etiology , Diabetic Retinopathy/epidemiology , Diabetic Retinopathy/pathology , Prognosis , Incidence , Biomarkers/analysis , Risk Factors , AgedABSTRACT
AIM: Earlier studies have shown that peptide glucagon-like peptide-1 receptor (GLP-1R) agonists with reduced ß-arrestin recruitment show enhanced anti-hyperglycaemic efficacy through avoidance of GLP-1R desensitization. However, the ligand modifications needed to decrease ß-arrestin recruitment usually also reduces GLP-1R affinity, therefore higher doses are needed. Here we aimed to develop new, long-acting, G protein-biased GLP-1R agonists with acute signalling potency comparable with semaglutide, to provide insights into specific experimental and therapeutic scenarios. MATERIALS AND METHODS: New GLP-1R agonist peptides were assessed using a variety of in vitro and in vivo assays. RESULTS: First, we show that very substantial reductions in ß-arrestin recruitment efficacy are required to realize fully the benefits of GLP-1R agonism on blood glucose lowering in mice, with more moderate reductions being less effective. Secondly, our lead compound (SRB107) performs substantially better than semaglutide for effects on blood glucose and weight loss, which may be jointly attributable to its biased agonist action and protracted pharmacokinetics. Thirdly, we show that biased agonist-specific GLP-1R internalization profiles occur at clinically relevant pharmacological concentrations. Finally, we show that SRB107 cAMP signalling is differentially modulated by single and double GLP1R coding variants seen in human populations, with implications for GLP-1R agonist pharmacogenomics. CONCLUSIONS: Completely abolishing ß-arrestin recruitment improves the anti-hyperglycaemic effects of GLP-1R agonists in mice.
Subject(s)
Blood Glucose , Glucagon-Like Peptide-1 Receptor Agonists , Humans , Animals , Mice , beta-Arrestins/metabolism , Peptides/pharmacology , Glucagon-Like Peptide-1 Receptor/agonists , GTP-Binding Proteins/metabolismABSTRACT
AIMS: To determine whether a continuous infusion of a glucagon-like peptide receptor (GLP-1R)/glucagon receptor (GCGR) co-agonist, G3215 is safe and well tolerated in adults with overweight or obesity. METHODS: A phase 1 randomized, double blind, placebo-controlled trial of G3215 in overweight or obese participants, with or without type 2 diabetes. RESULTS: Twenty-six participants were recruited and randomized with 23 completing a 14-day subcutaneous infusion of G3215 or placebo. The most common adverse events were nausea or vomiting, which were mild in most cases and mitigated by real-time adjustment of drug infusion. There were no cardiovascular concerns with G3215 infusion. The pharmacokinetic characteristics were in keeping with a continuous infusion over 14 days. A least-squares mean body weight loss of 2.39 kg was achieved with a 14-day infusion of G3215, compared with 0.84 kg with placebo infusion (p < .05). A reduction in food consumption was also observed in participants receiving G3215 and there was no deterioration in glycaemia. An improved lipid profile was seen in G3215-treated participants and consistent with GCGR activation, a broad reduction in circulating amino acids was seen during the infusion period. CONCLUSION: An adaptive continuous infusion of the GLP-1/GCGR co-agonist, G3215, is safe and well tolerated offering a unique strategy to control drug exposure. By allowing rapid, response-directed titration, this strategy may allow for mitigation of adverse effects and afford significant weight loss within shorter time horizons than is presently possible with weekly GLP-1R and multi-agonists. These results support ongoing development of G3215 for the treatment of obesity and metabolic disease.
Subject(s)
Diabetes Mellitus, Type 2 , Overweight , Adult , Humans , Overweight/complications , Overweight/drug therapy , Diabetes Mellitus, Type 2/drug therapy , Diabetes Mellitus, Type 2/metabolism , Receptors, Glucagon , Obesity/complications , Obesity/drug therapy , Glucagon-Like Peptide 1/therapeutic use , Glucagon-Like Peptide-1 Receptor/therapeutic useABSTRACT
BACKGROUND & AIMS: Concurrent hepatic steatosis has diverse effects on chronic hepatitis B (CHB), however the combined effects of metabolic dysfunction-associated steatotic liver disease (MASLD) and CHB on liver fibrosis progression remains unclear. The primary aim of this study was to utilize serial fibrosis measurements to compare the dynamic change in fibrosis in CHB patients with/without concurrent MASLD. The secondary aim was to investigate factors associated with steatosis development and regression in CHB patients. METHODS: This was a retrospective cohort study of all non-cirrhotic CHB patients identified from 1/1/2011 to 31/12/2016. Hepatic steatosis was diagnosed by ultrasound. Fibrosis markers included liver stiffness (LSM) by transient elastography, APRI and FIB-4. General linear mixed effects modelling was used to fit polynomial and linear estimates. RESULTS: Of 810 CHB patients (n = 2,373 LSM measurements; median age 44.4y; 48% male; 24% HBeAg positive), 14% had concurrent MASLD. LSM was higher at baseline but decreased in MASLD patients over time, while LSM remained stable in non-MASLD patients, such that all patients had similar LSM beyond 4-5 years. MASLD patients had lower APRI compared to non-MASLD patients, which was predominately due to a higher platelet count and higher ALT over time. There was substantial discordance between LSM, APRI and FIB-4. Baseline BMI was the only factor that predicted steatosis development and regression. CONCLUSIONS: We found no evidence of an association between concurrent MASLD and fibrosis progression amongst CHB patients without baseline advanced liver disease. APRI and FIB-4 may have reduced accuracy in MASLD patients.
Subject(s)
Elasticity Imaging Techniques , Fatty Liver , Hepatitis B, Chronic , Non-alcoholic Fatty Liver Disease , Humans , Male , Adult , Female , Hepatitis B, Chronic/complications , Retrospective Studies , Liver Cirrhosis/diagnosis , Fatty Liver/complications , Non-alcoholic Fatty Liver Disease/complicationsABSTRACT
The peptide hormone glucagon, discovered in late 1922, is secreted from pancreatic alpha cells and is an essential regulator of metabolic homeostasis. This review summarises experiences since the discovery of glucagon regarding basic and clinical aspects of this hormone and speculations on the future directions for glucagon biology and glucagon-based therapies. The review was based on the international glucagon conference, entitled 'A hundred years with glucagon and a hundred more', held in Copenhagen, Denmark, in November 2022. The scientific and therapeutic focus of glucagon biology has mainly been related to its role in diabetes. In type 1 diabetes, the glucose-raising properties of glucagon have been leveraged to therapeutically restore hypoglycaemia. The hyperglucagonaemia evident in type 2 diabetes has been proposed to contribute to hyperglycaemia, raising questions regarding underlying mechanism and the importance of this in the pathogenesis of diabetes. Mimicry experiments of glucagon signalling have fuelled the development of several pharmacological compounds including glucagon receptor (GCGR) antagonists, GCGR agonists and, more recently, dual and triple receptor agonists combining glucagon and incretin hormone receptor agonism. From these studies and from earlier observations in extreme cases of either glucagon deficiency or excess secretion, the physiological role of glucagon has expanded to also involve hepatic protein and lipid metabolism. The interplay between the pancreas and the liver, known as the liver-alpha cell axis, reflects the importance of glucagon for glucose, amino acid and lipid metabolism. In individuals with diabetes and fatty liver diseases, glucagon's hepatic actions may be partly impaired resulting in elevated levels of glucagonotropic amino acids, dyslipidaemia and hyperglucagonaemia, reflecting a new, so far largely unexplored pathophysiological phenomenon termed 'glucagon resistance'. Importantly, the hyperglucagonaemia as part of glucagon resistance may result in increased hepatic glucose production and hyperglycaemia. Emerging glucagon-based therapies show a beneficial impact on weight loss and fatty liver diseases and this has sparked a renewed interest in glucagon biology to enable further pharmacological pursuits.
Subject(s)
Diabetes Mellitus, Type 2 , Hyperglycemia , Non-alcoholic Fatty Liver Disease , Humans , Glucagon/metabolism , Diabetes Mellitus, Type 2/metabolism , Glucose/metabolism , Hyperglycemia/metabolism , Amino AcidsABSTRACT
OBJECTIVES: Peptide tyrosine tyrosine (PYY) exists as two species, PYY1-36 and PYY3-36 , with distinct effects on insulin secretion and appetite regulation. The detailed effects of bariatric surgery on PYY1-36 and PYY3-36 secretion are not known as previous studies have used nonspecific immunoassays to measure total PYY. Our objective was to characterize the effect of sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) on fasting and postprandial PYY1-36 and PYY3-36 secretion using a newly developed liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay. DESIGN AND SUBJECTS: Observational study in 10 healthy nonobese volunteers and 30 participants with obesity who underwent RYGB (n = 24) or SG (n = 6) at the Imperial Weight Centre [NCT01945840]. Participants were studied using a standardized mixed meal test (MMT) before and 1 year after surgery. The outcome measures were PYY1-36 and PYY3-36 concentrations. RESULTS: Presurgery, the fasting and postprandial levels of PYY1-36 and PYY3-36 were low, with minimal responses to the MMT, and these did not differ from healthy nonobese volunteers. The postprandial secretion of both PYY1-36 and PYY3-36 at 1 year was amplified after RYGB, but not SG, with the response being significantly higher in RYGB compared with SG. CONCLUSIONS: There appears to be no difference in PYY secretion between nonobese and obese volunteers at baseline. At 1 year after surgery, RYGB, but not SG, is associated with increased postprandial secretion of PYY1-36 and PYY3-36 , which may account for long-term differences in efficacy and adverse effects between the two types of surgery.
Subject(s)
Gastric Bypass , Humans , Gastric Bypass/methods , Peptide YY , Chromatography, Liquid , Blood Glucose , Tandem Mass Spectrometry , Obesity/surgery , Gastrectomy , TyrosineABSTRACT
BACKGROUND AND AIMS: Progressive liver fibrosis related to non-alcoholic fatty liver disease (NAFLD) is associated with all-cause and liver-related mortality. We assessed vibration-controlled transient elastography (VCTE) as a predictor of mortality. METHOD: Data from patients who underwent VCTE for NAFLD at four large health services in Victoria, Australia between the years 2008 and 2019 were linked to state-wide data registries. Cause of death (COD) and predictors of all-cause mortality were subsequently analysed using descriptive statistics and Cox-proportional regression analysis. RESULTS: Of 7079 VCTE records submitted for data linkage, 6341 were matched via data registry linkage. There were 217 deaths over a 22 653 person-year follow-up. COD included malignancies other than hepatocellular carcinoma (HCC) (18.0%, n = 39), sepsis (16.1%, n = 35), decompensated liver disease (15.2%, n = 33), cardiac disease (15.2%, n = 33) and HCC 6.0% (n = 13). Controlled attenuation parameter (CAP) was not associated with mortality in univariable analysis (HR = 1.00, CI 1.0-1.0, p = .488). Increased liver stiffness measurement (LSM) (HR 1.02 per kiloPascal, CI 1.01-1.03, p < .001), Charlson comorbidity index (CCI) (HR 1.32 for each point, CI 1.27-1.38, p < .001) and age (HR 1.05 per annum, CI 1.03-1.07, p < .001) were each associated with higher rates of all-cause mortality in multivariable analysis. LSM ≥10 kPa suggestive of compensated advanced chronic liver disease (cACLD) was associated with mortality in multivariable analysis (HR 2.31, CI 1.73-3.09, p < .001). CONCLUSION: VCTE LSM, in addition to age and CCI, is independently associated with increased all-cause mortality in a large cohort with NAFLD.
Subject(s)
Carcinoma, Hepatocellular , Elasticity Imaging Techniques , Liver Neoplasms , Non-alcoholic Fatty Liver Disease , Humans , Non-alcoholic Fatty Liver Disease/complications , Non-alcoholic Fatty Liver Disease/diagnostic imaging , Non-alcoholic Fatty Liver Disease/pathology , Liver Cirrhosis/complications , Carcinoma, Hepatocellular/pathology , Liver Neoplasms/pathology , Liver/pathologyABSTRACT
BACKGROUND AND AIMS: Sleeve gastrectomy (VSG) leads to improvement in hepatic steatosis, associated with weight loss. The aims of this study were to investigate whether VSG leads to weight-loss independent improvements in liver steatosis in mice with diet-induced obesity (DIO); and to metabolically and transcriptomically profile hepatic changes in mice undergoing VSG. METHODS: Mice with DIO were treated with VSG, sham surgery with subsequent food restriction to weight-match to the VSG group (Sham-WM), or sham surgery with return to unrestricted diet (Sham-Ad lib). Hepatic steatosis, glucose tolerance, insulin and glucagon resistance, and hepatic transcriptomics were investigated at the end of the study period and treatment groups were compared with mice undergoing sham surgery only (Sham-Ad lib). RESULTS: VSG led to much greater improvement in liver steatosis than Sham-WM (liver triglyceride mg/mg 2.5 ± 0.1, 2.1 ± 0.2, 1.6 ± 0.1 for Sham-AL, Sham-WM and VSG respectively; p = 0.003). Homeostatic model assessment of insulin resistance was improved following VSG only (51.2 ± 8.8, 36.3 ± 5.3, 22.3 ± 6.1 for Sham-AL, Sham-WM and VSG respectively; p = 0.03). The glucagon-alanine index, a measure of glucagon resistance, fell with VSG but was significantly increased in Sham-WM (9.8 ± 1.7, 25.8 ± 4.6 and 5.2 ± 1.2 in Sham Ad-lib, Sham-WM and VSG respectively; p = 0.0003). Genes downstream of glucagon receptor signalling which govern fatty acid synthesis (Acaca, Acacb, Me1, Acly, Fasn and Elovl6) were downregulated following VSG but upregulated in Sham-WM. CONCLUSIONS: Changes in glucagon sensitivity may contribute to weight-loss independent improvements in hepatic steatosis following VSG.
Subject(s)
Fatty Liver , Glucagon , Mice , Animals , Blood Glucose , Weight Loss , Obesity/complications , Obesity/surgery , Fatty Liver/complications , Gastrectomy/adverse effectsABSTRACT
BACKGROUND: Alanine aminotransferase (ALT) measurement is essential for evaluation of liver disease. We validated a novel rapid point-of-care (POC) test for ALT1 against laboratory ALT. METHODS: Stored plasma samples from adults with chronic liver disease (Test cohort n = 240; Validation cohort n = 491) were analysed using the BioPoint® antigen immunoassay POC ALT1 lateral flow test, which provides quantitative ALT results (Axxin handheld reader) or semi-quantitative results (visual read, cut off 40 IU/ml). The accuracy of POC ALT1 to detect ALT > 40 IU/L was determined by ROC analysis. In patients with chronic hepatitis B, treatment eligibility (EASL criteria) was determined using POC ALT1 and compared to laboratory ALT. RESULTS: POC ALT1 test had good accuracy for laboratory ALT > 40 IU/L: AUROC 0.93 (95% CI: 0.89-0.96) in the Test cohort and AUROC 0.92 (95% CI: 0.88-0.95) in the Validation cohort. POC ALT1 cut off of 0.8 for ALT > 40 IU/L maximised sensitivity (97%) and specificity (71%) in the Test cohort (42% laboratory ALT > 40 IU/L) and yielded PPV 84% and NPV 91% in the Validation cohort (19% laboratory ALT > 40 IU/L). Semi-quantitative POC ALT1 had good accuracy for laboratory ALT in the Validation cohort (AUROC 0.85, 95% CI: 0.81-0.99; sensitivity 77% and specificity 93%). Combined with HBV DNA and transient elastography, both quantitative and semi-quantitative POC ALT1 tests had good accuracy for excluding hepatitis B treatment needs (sensitivity 96%, specificity 78% and NPV 99%). CONCLUSION: The POC ALT1 test had good accuracy for elevated ALT levels and for determining treatment eligibility among people with chronic hepatitis B.
Subject(s)
Hepatitis B, Chronic , Hepatitis B , Adult , Humans , Alanine Transaminase , Hepatitis B, Chronic/diagnosis , Pilot Projects , Cohort Studies , DNA, ViralABSTRACT
AIMS: To investigate whether the elevation in postprandial concentrations of the gut hormones glucagon-like peptide-1 (GLP-1), oxyntomodulin (OXM) and peptide YY (PYY) accounts for the beneficial changes in food preferences, sweet taste function and eating behaviour after Roux-en-Y gastric bypass (RYGB). MATERIALS AND METHODS: This was a secondary analysis of a randomized single-blind study in which we infused GLP-1, OXM, PYY (GOP) or 0.9% saline subcutaneously for 4 weeks in 24 subjects with obesity and prediabetes/diabetes, to replicate their peak postprandial concentrations, as measured at 1 month in a matched RYGB cohort (ClinicalTrials.gov NCT01945840). A 4-day food diary and validated eating behaviour questionnaires were completed. Sweet taste detection was measured using the method of constant stimuli. Correct sucrose identification (corrected hit rates) was recorded, and sweet taste detection thresholds (EC50s: half maximum effective concencration values) were derived from concentration curves. The intensity and consummatory reward value of sweet taste were assessed using the generalized Labelled Magnitude Scale. RESULTS: Mean daily energy intake was reduced by 27% with GOP but no significant changes in food preferences were observed, whereas a reduction in fat and increase in protein intake were seen post-RYGB. There was no change in corrected hit rates or detection thresholds for sucrose detection following GOP infusion. Additionally, GOP did not alter the intensity or consummatory reward value of sweet taste. A significant reduction in restraint eating, comparable to the RYGB group was observed with GOP. CONCLUSION: The elevation in plasma GOP concentrations after RYGB is unlikely to mediate changes in food preferences and sweet taste function after surgery but may promote restraint eating.
Subject(s)
Gastric Bypass , Gastrointestinal Hormones , Prediabetic State , Humans , Taste , Food Preferences , Single-Blind Method , Prediabetic State/complications , Obesity/complications , Obesity/surgery , Gastric Bypass/adverse effects , Gastric Bypass/methods , Peptide YY/metabolism , Glucagon-Like Peptide 1/metabolism , Sucrose , VolunteersABSTRACT
Receptors for the peptide hormones glucagon-like peptide-1 (GLP-1R), glucose-dependent insulinotropic polypeptide (GIPR), and glucagon (GCGR) are important regulators of insulin secretion and energy metabolism. GLP-1R agonists have been successfully deployed for the treatment of type 2 diabetes, but it has been suggested that their efficacy is limited by target receptor desensitization and downregulation due to recruitment of ß-arrestins. Indeed, recently described GLP-1R agonists with reduced ß-arrestin-2 recruitment have delivered promising results in preclinical and clinical studies. We therefore aimed to determine if the same phenomenon could apply to the closely related GIPR and GCGR. In HEK293 cells depleted of both ß-arrestin isoforms the duration of G protein-dependent cAMP/PKA signaling was increased in response to the endogenous ligand for each receptor. Moreover, in wildtype cells, "biased" GLP-1, GCG, and GIP analogs with selective reductions in ß-arrestin-2 recruitment led to reduced receptor endocytosis and increased insulin secretion over a prolonged stimulation period, although the latter effect was only seen at high agonist concentrations. Biased GCG analogs increased the duration of cAMP signaling, but this did not lead to increased glucose output from hepatocytes. Our study provides a rationale for the development of GLP-1R, GIPR, and GCGR agonists with reduced ß-arrestin recruitment, but further work is needed to maximally exploit this strategy for therapeutic purposes.
Subject(s)
Cyclic AMP/metabolism , Gastric Inhibitory Polypeptide/metabolism , Glucagon-Like Peptide 1/metabolism , Glucagon-Like Peptide-1 Receptor/metabolism , Incretins/pharmacology , Receptors, Gastrointestinal Hormone/metabolism , beta-Arrestins/metabolism , Animals , Gastric Inhibitory Polypeptide/genetics , Glucagon/metabolism , Glucagon-Like Peptide 1/genetics , Glucagon-Like Peptide-1 Receptor/genetics , HEK293 Cells , Humans , Insulin Secretion , Ligands , Mice , Mice, Inbred C57BL , Receptors, Gastrointestinal Hormone/genetics , Signal Transduction , beta-Arrestins/geneticsABSTRACT
The glucagon-like peptide-1 receptor (GLP-1R), a key pharmacological target in type 2 diabetes (T2D) and obesity, undergoes rapid endocytosis after stimulation by endogenous and therapeutic agonists. We have previously highlighted the relevance of this process in fine-tuning GLP-1R responses in pancreatic beta cells to control insulin secretion. In the present study, we demonstrate an important role for the translocation of active GLP-1Rs into liquid-ordered plasma membrane nanodomains, which act as hotspots for optimal coordination of intracellular signaling and clathrin-mediated endocytosis. This process is dynamically regulated by agonist binding through palmitoylation of the GLP-1R at its carboxyl-terminal tail. Biased GLP-1R agonists and small molecule allosteric modulation both influence GLP-1R palmitoylation, clustering, nanodomain signaling, and internalization. Downstream effects on insulin secretion from pancreatic beta cells indicate that these processes are relevant to GLP-1R physiological actions and might be therapeutically targetable.
Subject(s)
Glucagon-Like Peptide-1 Receptor/metabolism , Insulin-Secreting Cells/metabolism , Animals , CHO Cells , Cell Membrane/metabolism , Cluster Analysis , Cricetulus , Cyclic AMP/metabolism , Diabetes Mellitus, Type 2 , Endocytosis/drug effects , Glucagon-Like Peptide 1/agonists , Glucagon-Like Peptide 1/metabolism , Glucagon-Like Peptide-1 Receptor/physiology , HEK293 Cells , Humans , Insulin/metabolism , Insulin Secretion/physiology , Insulin-Secreting Cells/physiology , Lipoylation , Signal Transduction/drug effectsABSTRACT
The glucagon-like peptide-1 receptor (GLP-1R) is a class B G protein-coupled receptor and mainstay therapeutic target for the treatment of type 2 diabetes and obesity. Recent reports have highlighted how biased agonism at the GLP-1R affects sustained glucose-stimulated insulin secretion through avoidance of desensitization and downregulation. A number of GLP-1R agonists (GLP-1RAs) feature a fatty acid moiety to prolong their pharmacokinetics via increased albumin binding, but the potential for these chemical changes to influence GLP-1R function has rarely been investigated beyond potency assessments for cAMP. Here, we directly compare the prototypical GLP-1RA exendin-4 with its C-terminally acylated analog, exendin-4-C16. We examine relative propensities of each ligand to recruit and activate G proteins and ß-arrestins, endocytic and postendocytic trafficking profiles, and interactions with model and cellular membranes in HEK293 and HEK293T cells. Both ligands had similar cAMP potency, but exendin-4-C16 showed â¼2.5-fold bias toward G protein recruitment and a â¼60% reduction in ß-arrestin-2 recruitment efficacy compared with exendin-4, as well as reduced GLP-1R endocytosis and preferential targeting toward recycling pathways. These effects were associated with reduced movement of the GLP-1R extracellular domain measured using a conformational biosensor approach and a â¼70% increase in insulin secretion in INS-1 832/3 cells. Interactions with plasma membrane lipids were enhanced by the acyl chain. Exendin-4-C16 showed extensive albumin binding and was highly effective for lowering of blood glucose in mice over at least 72 hours. Our study highlights the importance of a broad approach to the evaluation of GLP-1RA pharmacology. SIGNIFICANCE STATEMENT: Acylation is a common strategy to enhance the pharmacokinetics of peptide-based drugs. This work shows how acylation can also affect various other pharmacological parameters, including biased agonism, receptor trafficking, and interactions with the plasma membrane, which may be therapeutically important.
Subject(s)
Exenatide/metabolism , Glucagon-Like Peptide-1 Receptor/metabolism , Incretins/metabolism , Signal Transduction/physiology , Acylation/drug effects , Acylation/physiology , Animals , Exenatide/pharmacology , HEK293 Cells , Humans , Incretins/pharmacology , Insulin Secretion/drug effects , Insulin Secretion/physiology , Male , Mice , Mice, Inbred C57BL , Protein Transport/drug effects , Protein Transport/physiology , Signal Transduction/drug effectsABSTRACT
Bile acids (BA) regulate postprandial metabolism directly and indirectly by affecting the secretion of gut hormones like glucagon-like peptide-1 (GLP-1). The postprandial effects of BA on the secretion of other metabolically active hormones are not well understood. The objective of this study was to investigate the effects of oral ursodeoxycholic acid (UDCA) and chenodeoxycholic acid (CDCA) on postprandial secretion of GLP-1, oxyntomodulin (OXM), peptide YY (PYY), glucose-dependent insulinotropic peptide (GIP), glucagon, and ghrelin. Twelve healthy volunteers underwent a mixed meal test 60 min after ingestion of UDCA (12-16 mg/kg), CDCA (13-16 mg/kg), or no BA in a randomized crossover study. Glucose, insulin, GLP-1, OXM, PYY, GIP, glucagon, ghrelin, and fibroblast growth factor 19 were measured prior to BA administration at -60 and 0 min (just prior to mixed meal) and 15, 30, 60, 120, 180, and 240 min after the meal. UDCA and CDCA provoked differential gut hormone responses; UDCA did not have any significant effects, but CDCA provoked significant increases in GLP-1 and OXM and a profound reduction in GIP. CDCA increased fasting GLP-1 and OXM secretion in parallel with an increase in insulin. On the other hand, CDCA reduced postprandial secretion of GIP, with an associated reduction in postprandial insulin secretion. Exogenous CDCA can exert multiple salutary effects on the secretion of gut hormones; if these effects are confirmed in obesity and type 2 diabetes, CDCA may be a potential therapy for these conditions.NEW & NOTEWORTHY Oral CDCA and UDCA have different effects on gut and pancreatic hormone secretion. A single dose of CDCA increased fasting secretion of the hormones GLP-1 and OXM with an accompanying increase in insulin secretion. CDCA also reduced postprandial GIP secretion, which was associated with reduced insulin. In contrast, UDCA did not change gut hormone secretion fasting or postprandially. Oral CDCA could be beneficial to patients with obesity and diabetes.
Subject(s)
Bile Acids and Salts/pharmacology , Gastrointestinal Hormones/metabolism , Postprandial Period/drug effects , Administration, Oral , Adult , Bile Acids and Salts/administration & dosage , Bile Acids and Salts/blood , Chenodeoxycholic Acid/administration & dosage , Chenodeoxycholic Acid/pharmacology , Cross-Over Studies , Eating/physiology , Female , Healthy Volunteers , Humans , Male , Middle Aged , Secretory Pathway/drug effects , United Kingdom , Ursodeoxycholic Acid/administration & dosage , Ursodeoxycholic Acid/pharmacology , Young AdultABSTRACT
'Imperial Satiety Protocol' (I-SatPro) is a new multifaceted approach to weight loss for people with obesity (PwO), encompassing dietary advice, time-restricted eating, physical activity and coaching to support behaviour change. Participants (n = 84) attended fortnightly I-SatPro group sessions for 30 weeks, with 70% of participants completing. On completion at 30 weeks, the mean weight loss was 15.2 ± 1.1 kg (13.2 ± 0.8% from baseline, P < .0001), which was maintained to 52 weeks (16.6 ± 1.5 kg, 14.1 ± 1.2%, P < .0001). Weight loss was not associated with reduced energy expenditure. In participants with type 2 diabetes and pre-diabetes (n = 16), glycated haemoglobin fell from 50 to 43 mmol/mol (P < .01). Systolic blood pressure fell by 12 mmHg (P < .0001). Triglycerides fell by 0.37 mmol/L (P < .01) and high-density lipoprotein rose by 0.08 mmol/L (P < .01). Short Form-36 (SF-36) functioning and wellbeing scores increased in all domains post I-SatPro intervention. For selected PwO, I-SatPro delivers clinically meaningful weight loss, and the potential for long-term health and wellbeing improvements.
Subject(s)
Diabetes Mellitus, Type 2 , Weight Reduction Programs , Delivery of Health Care , Diabetes Mellitus, Type 2/therapy , Humans , Obesity/therapy , Weight LossABSTRACT
AIM: To report the results from a Phase 1 trial of an extended-release peptide YY analogue, Y14, developed for the treatment of obesity. METHODS: Y14 was evaluated in overweight/obese volunteers in a Phase 1 randomized placebo-controlled trial, conducted in a clinical trial unit in the United Kingdom. Part A was a blinded single-ascending-dose study evaluating doses up to 36 mg. Part B was double-blinded and tested multiple ascending doses between 9 and 36 mg, given at 7- to 14-day intervals, over the course of 28 days, with up to five doses given per participant. The primary outcome was safety and tolerability; the secondary outcome was assessment of pharmacokinetic (PK) characteristics. Exploratory outcomes included food intake, body weight change and glucose tolerance after multiple doses. RESULTS: Between April 11, 2017 and December 24, 2018, 53 participants were enrolled into Part A and 24 into Part B of the trial. The PK characteristics were compatible with administration every 7 to 14 days. The most common adverse events (AEs) were nausea, vomiting or administration site reactions, which were mild in most cases and settled with time. No serious AE occurred. Participants given multiple doses of Y14 lost between -2.87 and -3.58 kg body weight compared with placebo (P <0.0001) at 31 days from the first dose, with profound reductions in food intake of 38% to 55% (P <0.0001, compared to placebo) and there was no evidence of tachyphylaxis. CONCLUSIONS: Our results support the continued development of Y14 as a novel treatment for obesity.
Subject(s)
Obesity , Peptide YY , Double-Blind Method , Humans , Obesity/drug therapy , Overweight , United KingdomABSTRACT
BACKGROUND: A unique model of care was adopted in Australia following introduction of universal subsidised direct-acting antiviral (DAA) access in 2016 in order to encourage rapid scale-up of treatment. Community-based medical practitioners and integrated hepatitis nurses initiated DAA treatment with remote hepatitis specialist approval of the planned treatment without physical review. AIMS: To evaluate outcomes of community-based treatment of hepatitis C virus (HCV) through this remote consultation process in the first 12 months of this model of care. METHODS: A retrospective chart review of patients undergoing community-based HCV treatment from general practitioners and integrated hepatitis nurse consultants through the remote consultation model in three state jurisdictions in Australia from 1 March 2016 to 28 February 2017. RESULTS: Sustained virological response at 12 weeks (SVR12) was confirmed in 383 (65.1%) of 588 subjects intended for treatment with a median follow-up time of 12 months (interquartile range 9-14 months). The SVR12 test was not performed in 159 (27.0%) of 588 and 307 (52.2%) of 588 did not have liver biochemistry rechecked following treatment. Subjects who completed follow up exhibited high SVR12 rates (383/392; 97.7%). Nurse-led treatment was associated with higher confirmation of SVR12 (73.7% vs 62.4%; P = 0.01) and liver biochemistry testing post treatment (57.5% vs 45.0%; P = 0.01). CONCLUSIONS: Community-based management of HCV through remote specialist consultation may be an effective model of care. Failure to check SVR12, recheck liver biochemistry and appropriate surveillance in patients with cirrhosis may emerge as significant issues requiring further support, education and refinement of the model to maximise effectiveness of future elimination efforts.
Subject(s)
General Practitioners , Hepatitis C, Chronic , Hepatitis C , Remote Consultation , Antiviral Agents/therapeutic use , Australia/epidemiology , Hepacivirus , Hepatitis C/diagnosis , Hepatitis C/drug therapy , Hepatitis C/epidemiology , Hepatitis C, Chronic/drug therapy , Humans , Retrospective Studies , Treatment OutcomeABSTRACT
Malnutrition among patients with chronic liver disease (CLD) is a common complication with significant prognostic implications for patients with liver cirrhosis. Micronutrient deficiency has been associated with an increased risk of hepatic decompensation and is an independent risk factor for mortality among cirrhotic patients. Micronutrient deficiencies in patients with CLD include zinc, vitamin A, vitamin D and selenium. This review article aims to evaluate the literature to date on the complications of zinc deficiency in patients with CLD. A management algorithm for zinc replacement has also been proposed.
Subject(s)
Dietary Supplements , Liver Diseases/therapy , Trace Elements/therapeutic use , Zinc/therapeutic use , Chronic Disease , Humans , Liver Diseases/diagnosis , Liver Diseases/etiologyABSTRACT
The glucagon-like peptide-1 receptor (GLP-1R) is an important regulator of blood glucose homeostasis. Ligand-specific differences in membrane trafficking of the GLP-1R influence its signalling properties and therapeutic potential in type 2 diabetes. Here, we have evaluated how different factors combine to control the post-endocytic trafficking of GLP-1R to recycling versus degradative pathways. Experiments were performed in primary islet cells, INS-1 832/3 clonal beta cells and HEK293 cells, using biorthogonal labelling of GLP-1R to determine its localisation and degradation after treatment with GLP-1, exendin-4 and several further GLP-1R agonist peptides. We also characterised the effect of a rare GLP1R coding variant, T149M, and the role of endosomal peptidase endothelin-converting enzyme-1 (ECE-1), in GLP1R trafficking. Our data reveal how treatment with GLP-1 versus exendin-4 is associated with preferential GLP-1R targeting towards a recycling pathway. GLP-1, but not exendin-4, is a substrate for ECE-1, and the resultant propensity to intra-endosomal degradation, in conjunction with differences in binding affinity, contributes to alterations in GLP-1R trafficking behaviours and degradation. The T149M GLP-1R variant shows reduced signalling and internalisation responses, which is likely to be due to disruption of the cytoplasmic region that couples to intracellular effectors. These observations provide insights into how ligand- and genotype-specific factors can influence GLP-1R trafficking.
Subject(s)
Endocytosis/physiology , Glucagon-Like Peptide-1 Receptor/metabolism , Insulin-Secreting Cells/metabolism , Insulin-Secreting Cells/physiology , Protein Transport/physiology , Animals , Cell Line , Cytoplasm/metabolism , Endosomes/metabolism , Endosomes/physiology , Endothelin-Converting Enzymes/metabolism , HEK293 Cells , Humans , Ligands , MiceABSTRACT
BACKGROUND & AIMS: As many as 70% of individuals with chronic hepatitis C (CHC) are managed solely in primary care. The aims of this study were to determine the prevalence of elevated liver stiffness measurement (LSM) in a cohort of community managed patients with CHC and to evaluate predictors of advanced liver disease and liver-related events. METHODS: A prospective cohort of adult patients with CHC were recruited from 21 primary care practices throughout Victoria, Australia. Inclusion criteria included the presence of CHC for >6â¯months, no recent (<18â¯months) specialist input and no history of hepatocellular carcinoma. Clinical assessment, LSM and phlebotomy were carried out in primary care. A hospital cohort was recruited for comparison. Participants were followed longitudinally and monitored for liver-related events. RESULTS: Over 26â¯months, 780 community patients were recruited and included in the analysis. The median LSM was 6.9â¯kPa in the community, with 16.5% of patients at risk of advanced fibrosis (LSM ≥12.5â¯kPa); of these 8.5% had no laboratory features of advanced liver disease. The proportion at risk of cirrhosis was no different between the community and hospital cohorts (pâ¯=â¯0.169). At-risk alcohol consumption, advancing age, elevated body mass index and alanine aminotransferase were independent predictors of elevated LSM. Over a median follow-up of 15.2â¯months, liver-related events occurred in 9.3% of those with an LSM ≥12.5â¯kPa. An LSM of 24â¯kPa had the highest predictive power for liver-related events (hazard ratio152; pâ¯<0.001). CONCLUSION: The prevalence of advanced fibrosis, as determined by LSM, in primary care managed CHC is significant and comparable to a hospital cohort. Furthermore, this study supports the use of LSM as a community screening tool in a CHC population and indicates a possible role in predicting liver-related events. LAY SUMMARY: The prevalence of advanced liver disease in primary care managed hepatitis C is unknown. Our data suggests that rates of advanced fibrosis in the community are significant (16.5%), often underdiagnosed and comparable to rates seen in specialist referral centres. Liver stiffness measurement is a feasible community screening tool prior to hepatitis C therapy and can predict liver-related adverse events.