Newer GLP-1 receptor agonists and obesity-diabetes

Glucagon-like peptide-1 analogs: Miracle drugs are blooming?

Glucagon-like peptide-1 (GLP-1), secreted by L cells in the small intestine, assumes a central role in managing type 2 diabetes mellitus (T2DM) and obesity. Its influence on insulin secretion and gastric emptying positions it as a therapeutic linchpin. However, the limited applicability of native GLP-1 stems from its short half-life, primarily due to glomerular filtration and the inactivating effect of dipeptidyl peptidase-IV (DPP-IV). To address this, various structural modification strategies have been developed to extend GLP-1's half-life. Despite the commendable efficacy displayed by current GLP-1 receptor agonists, inherent limitations persist. A paradigm shift emerges with the advent of unimolecular multi-agonists, such as the recently introduced tirzepatide, wherein GLP-1 is ingeniously combined with other gastrointestinal hormones. This novel approach has captured the spotlight within the diabetes and obesity research community. This review summarizes the physiological functions of GLP-1, systematically explores diverse structural modifications, delves into the realm of unimolecular multi-agonists, and provides a nuanced portrayal of the developmental prospects that lie ahead for GLP-1 analogs.

Incretin Analogs for Weight Management in Adults Without Diabetes

OBJECTIVE

This is a narrative review of incretin analogs and their effect on weight management in adult without diabetes.

DATA SOURCES

Randomized controlled trials were identified by English language. PubMed/MEDLINE, Scopus, and Embase databases were searched from inception through June 2023 to identify all pertinent trials reporting outcomes on efficacy and safety search using the terms: tirzepatide, semaglutide, liraglutide, and obesity.

STUDY SELECTION AND DATA EXTRACTION

Selected studies were included if the study population was composed of adults without diabetes being treated by glucagon-like peptide 1 (GLP-1) receptor agonists or glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 agonists for weight management, and weight loss was assessed as a primary outcome.

DATA SYNTHESIS

Fifteen studies involving 3 pharmacotherapies (liraglutide, semaglutide, and tirzepatide) were identified. Efficacy data supporting the use of these agents for weight management were promising when compared to placebo and/or other behavioral therapies. Percent weight loss ranged from 5.7% to 11.8%, 14.9% to 17.4%, and 15% to 20.9% for liraglutide, semaglutide, and tirzepatide, respectively. Safety data were relatively similar across all trials and identified gastrointestinal adverse effects as most common.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Glucagon-like peptide 1 agonists are preferred for overweight or obese patients by the American Gastroenterological Association. Future guidelines may address tirzepatides' place in therapy as new evidence comes forth. Providers should consider patient-specific factors such as cost, adverse effects, drug interactions, and comorbidities when prescribing these agents and provide education regarding the need for concurrent diet and exercise modifications.

CONCLUSIONS

All incretin analogs in this review are superior to placebo when used for weight management in adults without diabetes.

Factors influencing the bariatric surgery treatment of bariatric surgery candidates in underdeveloped areas of China

BACKGROUND

From year to year, the proportion of people living with overweight and obesity in China rises, along with the prevalence of diseases linked to obesity. Although bariatric surgery is gaining popularity, there are still several issues with its promotion compared to Western nations. Since less developed places in China are more widespread due to disparities in the development of different regions, there has been little exploration of the factors that might be related to acceptance of bariatric surgery in these regions.

METHODS

Patients who visited the Department of Gastrointestinal Surgery at the North Sichuan Medical College Affiliated Hospital from 2018 to 2022 and had obesity or other relevant metabolic problems were surveyed using a questionnaire. The relationship between demographic factors, socioeconomic status, and acceptance of bariatric surgery was analyzed.

RESULTS

Of 334 patients, 171 had bariatric surgery. BMI, education level, marriage history, medical insurance, family support, and a history of type 2 diabetes were all linked to having bariatric surgery, according to a univariate analysis. In a multivariate analysis, BMI (P = 0.02), education (P = 0.02), family support (P<0.001), medical insurance coverage (P<0.001), and history of type 2 diabetes (P = 0.004) were all positively associated with a willingness to have bariatric surgery. Among 163 non-bariatric patients with obesity, 15.3% were not opposed to surgery but preferred trying medication first, 54.6% leaned towards medical therapy, and 30% were hesitant. Additionally, a majority of patients (48.55%) often lacked adequate knowledge about weight reduction therapy. Age, height, gender, smoking, drinking, family history of type 2 diabetes, education, and marital status did not significantly differ (P > 0.05).

CONCLUSIONS

Many patients are concerned about the safety of surgical treatment and the possibility of regaining weight. Due to the relatively high cost of bariatric surgery, they tend to choose medical treatment. To enhance the acceptance of bariatric surgery in underdeveloped regions of China, it is crucial to focus on disseminating knowledge about bariatric surgery, offer pertinent health education to the community, and foster support from patients' families. The government should pay more attention to obesity and provide support in the form of medical insurance.

Novel GLP-1(28-36) amide-derived hybrid peptide A3 with weight loss and hypoglycemic activities

Glucagon-like peptide-1 (GLP-1) has gained much attention in the last decade for the treatment of type 2 diabetes. Accumulating evidence indicates that some metabolites of GLP-1 have biological activities that might contribute to the pleiotropic effects of GLP-1 independent of the GLP-1 receptor. The hypoglycemic and weight-reducing effects of the reported metabolites and modifications still need to be confirmed. In this study, we started from the C-terminal nonapeptide GLP-1(28-36) amide and developed a series of GLP-1(28-36) amide-derived hybrid peptides. Our findings of biological activity evaluation in INS-1 cells, streptozotocin-induced diabetic and diet-induced obesity mice confirmed a novel hybrid peptide, A3, and provided a new perspective in the development of new drugs from peptide metabolites.

GLP-1RAs and cardiovascular disease: is the endothelium a relevant platform?

Hyperglycemia strongly affects endothelial function and activation, which in turn increases the risk of atherosclerotic cardiovascular disease. Among pharmacotherapies aimed at lowering blood glucose levels, glucagon-like peptide 1 receptor agonists (GLP-1RA) represent a class of drugs involved in the improvement of the endothelium damage and the progression of cardiovascular diseases. They show antihypertensive and antiatherosclerotic actions due at least in part to direct favorable actions on the coronary vascular endothelium, such as oxidative stress reduction and nitric oxide increase. However, cumulative peripheral indirect actions could also contribute to the antiatherosclerotic functions of GLP-1/GLP-1R agonists, including metabolism and gut microbiome regulation. Therefore, further research is necessary to clarify the specific role of this drug class in the management of cardiovascular disease and to identify specific cellular targets involved in the protective signal transduction. In the present review, we provide an overview of the effects of GLP-1RAs treatment on cardiovascular disease with particular attention on potential molecular mechanisms involving endothelium function on formation and progression of atherosclerotic plaque.

Do GLP-1 Analogs Have a Place in the Treatment of PCOS? New Insights and Promising Therapies

Polycystic ovary syndrome (PCOS) is the most prevalent endocrinopathy in women of reproductive age. This condition is characterized by hyperandrogenism and either oligo- or anovulation. PCOS patients often present comorbidities such as obesity, insulin resistance, impaired glucose metabolism, dyslipidemia, hypertension, metabolic syndrome, and an increased risk of diabetes. Given the profound implications of metabolic impairment in PCOS, the accurate diagnosis and management of these facets are imperative. The first-line approach to treatment involves lifestyle modifications, including dietary adjustments and exercise aimed at achieving weight loss, a strategy consistently emphasized across the literature. Supplementation with probiotics, vitamin D, and L-carnitine have also provided additional benefits to patients. In select cases, pharmacological interventions are needed for optimal therapeutic results. The most common medications used in PCOS include metformin, thiazolidinediones, inositols, and two classes of antidiabetic agents: dipeptidyl peptidase-IV (DPP-IV) inhibitors, and sodium-glucose cotransporter-2 (SGLT-2) inhibitors. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are a new addition to the therapeutic arsenal for the metabolic management of PCOS. GLP-1 receptor agonists cause insulin release in a glucose-dependent manner, yielding clinical benefits such as heightened satiety, reduced appetite, and appetite regulation. GLP-1RAs have demonstrated efficacy in reducing glycated hemoglobin levels and promoting weight loss while ameliorating hyperlipidemia. Prior to initiating GLP-1RA therapy, patients should undergo screening for contraindications, including history of pancreatitis, diabetic retinopathy, or thyroid cancer. The effects of treatment should be monitored using laboratory testing and body weight measurements. Effective communication between clinician and patient should be maintained with regular check-in for a period of 6 to 12 months.

Exploring the underlying mechanisms of obesity and diabetes and the potential of Traditional Chinese Medicine: an overview of the literature

Obesity and diabetes are closely related metabolic disorders that have become major public health concerns worldwide. Over the past few decades, numerous studies have explored the underlying mechanisms of these disorders and identified various risk factors, including genetics, lifestyle, and dietary habits. Traditional Chinese Medicine (TCM) has been increasingly recognized for its potential to manage obesity and diabetes. Weight loss is difficult to sustain, and several diabetic therapies, such as sulfonylureas, thiazolidinediones, and insulin, might make it harder to lose weight. While lifestyle changes should be the primary approach for people interested in lowering weight, drugs are also worth investigating. Since some of the newer glucose-lowering medications that cause weight loss, such as glucagon-like peptide-1 receptor agonists (GLP-1 RAs) and sodium-glucose cotransporter 2 inhibitors (SGLT2i), are additionally utilized or are under consideration for use as anti-obesity drugs, the frontier between glucose-lowering medication and weight loss drugs appears to be shifting. This review provides an overview of the literature on the underlying mechanisms of obesity and diabetes and the prospect of TCM in their management. We discuss the various TCM interventions, including acupuncture, herbal medicine, and dietary therapy, and their effects on metabolic health. We also highlight the potential of TCM in regulating gut microbiota, reducing inflammation, and improving insulin sensitivity. The findings suggest that TCM may provide a promising approach to preventing and managing obesity and diabetes. However, further well-designed studies are needed to confirm the efficacy and safety of TCM interventions and to elucidate their underlying mechanisms of action.

State of art on the mechanisms of laparoscopic sleeve gastrectomy in treating type 2 diabetes mellitus

Obesity and type-2 diabetes mellitus (T2DM) are metabolic disorders. Obesity increases the risk of T2DM, and as obesity is becoming increasingly common, more individuals suffer from T2DM, which poses a considerable burden on health systems. Traditionally, pharmaceutical therapy together with lifestyle changes is used to treat obesity and T2DM to decrease the incidence of comorbidities and all-cause mortality and to increase life expectancy. Bariatric surgery is increasingly replacing other forms of treatment of morbid obesity, especially in patients with refractory obesity, owing to its many benefits including good long-term outcomes and almost no weight regain. The bariatric surgery options have markedly changed recently, and laparoscopic sleeve gastrectomy (LSG) is gradually gaining popularity. LSG has become an effective and safe treatment for type-2 diabetes and morbid obesity, with a high cost-benefit ratio. Here, we review the me-chanism associated with LSG treatment of T2DM, and we discuss clinical studies and animal experiments with regard to gastrointestinal hormones, gut microbiota, bile acids, and adipokines to clarify current treatment modalities for patients with obesity and T2DM.

Utilization of glucagon-like peptide-1 receptor agonists in children and adolescents in China: a real-world study

Background

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have been widely used in treating type 2 diabetes mellitus (T2DM) and obesity in adults, but scientific research about the indication in children and adolescents is scarce. The current study aims to explore the prescriptions of GLP-1RAs in children and adolescents in China and to evaluate its rationality.

Methods

GLP-1RA prescriptions of children and adolescents were retrospectively obtained from the Hospital Prescription Analysis Cooperative Project. The study extracted information on patient's demographic characteristics, monotherapy and combination therapy of GLP-1RAs, and trends in GLP-1RA usage from 2016 to 2021. The rationality of GLP-1RA prescriptions was comprehensively assessed based on the indications approved by China National Medical Products Administration (NMPA), the U.S. Food and Drug Administration (FDA), European Medicines Agency (EMA), Pharmaceuticals and Medical Devices Agency (PMDA), and published randomized controlled trials (RCTs).

Results

A total of 234 prescriptions from 46 hospitals were included, with a median age of 17 years old. The majority of patients were diagnosed with overweight/obesity or prediabetes/diabetes, accounting for 43.59% and 46.15%, respectively. There were 88 patients on GLP-1RA monotherapy. GLP-1RAs plus metformin was the most common combination therapy (38.89%). 12.39% of patients were found a co-administration with orlistat. The share of overweight/obesity prescriptions increased from 27% in 2016 to 54% in 2021, whereas prediabetes/diabetes prescriptions declined from 55% to 42%. The prescriptions were divided into appropriate and questionable groups according to the diagnosis, and the potentially questionable prescription was related to age (p = 0.017), department visited (p = 0.002), and any hospitalization (p < 0.001).

Conclusions

This study described the prescribing of GLP-1RAs in children and adolescents. Our findings indicated that the utilization of GLP-1RAs has increased from 2016 to 2021. There was a strong basis for administering GLP-1RAs in overweight/obesity and prediabetes/diabetes, whereas the evidence was insufficient in other conditions. It is crucial to demand robust and sustained efforts to enhance the awareness of the safety of utilization of GLP-1RAs in children and adolescents.

Assessing adverse drug reaction reports for antidiabetic medications approved by the food and drug administration between 2012 and 2017: a pharmacovigilance study

Objective

Between 2012 and 2017, the U.S. Food and Drug Administration (FDA) approved 10 antidiabetic indicated therapies. Due to the limited literature on voluntarily reported safety outcomes for recently approved antidiabetic drugs, this study investigated adverse drug reactions (ADRs) reported in the FDA Adverse Event Reporting System (FAERS).

Research Design and Methods

A disproportionality analysis of spontaneously reported ADRs was conducted. FAERS reports from January 1, 2012 to March 31, 2022 were compiled, allowing a 5-year buffer following drug approval in 2017. Reporting odds ratios were calculated for the top 10 ADRs, comparing new diabetic agents to the other approved drugs in their therapeutic class.

Results

127,525 reports were identified for newly approved antidiabetic medications listed as the primary suspect (PS). For sodium-glucose co-transporter-2 (SGLT-2) inhibitors, the odds of blood glucose increased, nausea, and dizziness being reported was greater for empagliflozin. Dapagliflozin was associated with greater reports of weight decreased. Canagliflozin was found to have a disproportionally higher number of reports for diabetic ketoacidosis, toe amputation, acute kidney injury, fungal infections, and osteomyelitis. Assessing glucagon-like peptide-1 (GLP-1) receptor agonists, dulaglutide and semaglutide were associated with greater reports of gastrointestinal adverse drug reactions. Exenatide was disproportionally associated with injection site reactions and pancreatic carcinoma reports.

Conclusion

Pharmacovigilance studies utilizing a large publicly available dataset allow an essential opportunity to evaluate the safety profile of antidiabetic drugs utilized in clinical practice. Additional research is needed to evaluate these reported safety concerns for recently approved antidiabetic medications to determine causality.

Albumin-binding DARPins as scaffold improve the hypoglycemic and anti-obesity effects of exendin-4 in vivo

Type 2 diabetes mellitus (T2DM) and obesity have been considered epidemics and threats to public health worldwide. Exendin-4 (Ex), a GLP-1R agonist, has potential for treating T2DM and obesity. However, Ex has a half-life of only 2.4 h in humans and needs to be administered twice daily, which hampers its clinical application. In this study, we synthesized four new GLP-1R agonists by genetically fusing Ex to the N-terminus of HSA-binding ankyrin repeat proteins (DARPins) via linkers of different lengths, denoted as Ex-DARPin-GSx fusion proteins (x = 0, 1, 2, and 3). The Ex-DARPin fusion proteins were substantially stable, resulting in incomplete denaturation even at 80 °C. The in vitro bioactivity results demonstrated that Ex-DARPin fusion proteins could bind to HSA and activate GLP-1R. The Ex-DARPin fusion proteins had a comparable half-life (29-32 h), which is much longer than that of native Ex (0.5 h in rats). Subcutaneous injection of 25 nmol/kg Ex-DARPin fusion protein normalized blood glucose (BG) levels for at least 72 h in mice. The Ex-DARPin fusion proteins, injected at 25 nmol/kg every three days, significantly lowered BG, inhibited food consumption, and reduced body weight (BW) for 30 days in STZ-induced diabetic mice. Histological analysis of pancreatic tissues using H&E staining revealed that Ex-DARPin fusion proteins significantly improved the survival of pancreatic islets in diabetic mice. The differences in in vivo bioactivity of fusion proteins with different linker lengths were not significant. According to the findings in this study, long-acting Ex-DARPin fusion proteins designed by us hold promise for further development as antidiabetic and antiobesity therapeutic agents. Our findings also indicate that DARPins are a universal platform for generating long-acting therapeutic proteins via genetic fusion, thus broadening the application scope of DARPins.

Effects of GLP-1 on ovarian dysfunction in polycystic ovary syndrome: A protocol for systematic review and meta-analysis

BACKGROUND

Polycystic ovary syndrome (PCOS) is a frequent endocrine disorder in women, it is the principal cause of infertility and amenorrhea. Due to its high recurrence rate, poor prognosis and serious complications, more works on the research of PCOS are needed. Therefore, we performed a protocol for systematic review and meta-analysis to investigate the efficacy and safety of glucagon-like peptide-1 receptor agonists on ovarian dysfunction in PCOS.

METHODS

This study protocol has been registered in the PROSPERO and the registration number is CRD42020188247. The procedure of this protocol will be conducted according to the Preferred Reporting Item for Systematic Review and Meta-analysis Protocols guidance. A comprehensive search of several databases from 1966 to November 2022 will be conducted. The databases includes Ovid Medline In-Process & Other Non-Indexed Citations, Ovid MEDLINE, Ovid EMBASE, Ovid Cochrane Central Register of Controlled Trials, Ovid Cochrane Database of Systematic Reviews, and PubMed. The risk of bias of the included studies will be assessed using the Cochrane tool of risk of bias. All statistical analyses will be conducted using the software program Review Manager version 5.3.

RESULTS

The results of this systematic review will be published in a peer-reviewed journal.

CONCLUSION

This systematic review will provide evidence to judge whether glucagon-like peptide-1 receptor agonist is superior to metformin in patients with PCOS.

GLP-1 receptor agonist as a modulator of innate immunity

Glucagon-like peptide-1 (GLP-1) is a 30-amino acid hormone secreted by L cells in the distal ileum, colon, and pancreatic α cells, which participates in blood sugar regulation by promoting insulin release, reducing glucagon levels, delaying gastric emptying, increasing satiety, and reducing appetite. GLP-1 specifically binds to the glucagon-like peptide-1 receptor (GLP-1R) in the body, directly stimulating the secretion of insulin by pancreatic β-cells, promoting proliferation and differentiation, and inhibiting cell apoptosis, thereby exerting a glycemic lowering effect. The glycemic regulating effect of GLP-1 and its analogues has been well studied in human and murine models in the circumstance of many diseases. Recent studies found that GLP-1 is able to modulate innate immune response in a number of inflammatory diseases. In the present review, we summarize the research progression of GLP-1 and its analogues in immunomodulation and related signal pathways.

Regimen comprising GLP-1 receptor agonist and basal insulin can decrease the effect of food on glycemic variability compared to a pre-mixed insulin regimen

BACKGROUND

Increasing evidence suggests that glucagon-like peptide 1 (GLP-1) receptor agonists (RA) can stabilize glycemic variability (GV) and interfere with eating behavior. This study compared the impact of insulin, GLP-1 RA, and dietary components on GV using professional continuous glucose monitoring (CGM).

METHODS

Patients with type 2 diabetes underwent CGM before and after switching from a twice-daily pre-mixed insulin treatment regimen to a GLP-1 RA (liraglutide) plus basal insulin regimen. The dietary components were recorded and analyzed by a certified dietitian. The interactions between the medical regimen, GV indices, and nutrient components were analyzed.

RESULTS

Sixteen patients with type 2 diabetes were enrolled in this study. No significant differences in the diet components and total calorie intake between the two regimens were found. Under the pre-mixed insulin regimen, for increase in carbohydrate intake ratio, mean amplitude of glucose excursion (MAGE) and standard deviation (SD) increased; in contrast, under the new regimen, for increase in fat intake ratio, MAGE and SD decreased, while when the protein intake ratio increased, the coefficient of variation (CV) decreased. The impact of the food intake ratio on GV indices disappeared under the GLP-1 RA regimen. After switching to the GLP-1 RA regimen, the median MAGE, SD, and CV values decreased significantly. However, the significant difference in GV between the two regimens decreased during the daytime.

CONCLUSION

A GLP-1 RA plus basal insulin regimen can stabilize GV better than a regimen of twice-daily pre-mixed insulin, especially in the daytime, and can diminish the effect of food components on GV.

Liraglutide Effectiveness in Type 2 Diabetes: Insights from a Real-World Cohort of Portuguese Patients

Liraglutide is a long-acting glucagon-like peptide-1 receptor agonist prescribed to diabetic patients for glycaemic control. To understand the impact of liraglutide in the real-world setting, this study analysed its effects in a Portuguese cohort of Type 2 diabetes patients. This was an observational, multicentric, and retrospective study that included 191 liraglutide-treated patients with at least 12 months of treatment. Patients’ data were collected and analysed during a 24-month follow-up period. Overall, liraglutide treatment effectively reduced HbA1c levels from 8.3% to around 7.5%, after 6, 12, and 24 months (p < 0.001). In fact, 38.2%, 37.2%, and 44.8% of patients at 6, 12, and 24 months, respectively, experienced an HbA1c reduction of at least 1%. Moreover, a persistent reduction in anthropometric features was also observed, with 44.0%, 47.6%, and 54.4% of patients achieving a weight reduction of at least 3% at 6, 12, and 24 months, respectively. Finally, significant improvements were observed in the HDL-c and LDL-c levels. Our results demonstrate that liraglutide effectively promoted the reduction of HbA1c values during routine clinical practice, which was sustained throughout the study. In addition, there were significant improvements in anthropometric parameters and other cardiovascular risk factors.

Signaling pathways in obesity: mechanisms and therapeutic interventions

Obesity is a complex, chronic disease and global public health challenge. Characterized by excessive fat accumulation in the body, obesity sharply increases the risk of several diseases, such as type 2 diabetes, cardiovascular disease, and nonalcoholic fatty liver disease, and is linked to lower life expectancy. Although lifestyle intervention (diet and exercise) has remarkable effects on weight management, achieving long-term success at weight loss is extremely challenging, and the prevalence of obesity continues to rise worldwide. Over the past decades, the pathophysiology of obesity has been extensively investigated, and an increasing number of signal transduction pathways have been implicated in obesity, making it possible to fight obesity in a more effective and precise way. In this review, we summarize recent advances in the pathogenesis of obesity from both experimental and clinical studies, focusing on signaling pathways and their roles in the regulation of food intake, glucose homeostasis, adipogenesis, thermogenesis, and chronic inflammation. We also discuss the current anti-obesity drugs, as well as weight loss compounds in clinical trials, that target these signals. The evolving knowledge of signaling transduction may shed light on the future direction of obesity research, as we move into a new era of precision medicine.

Mesenchymal Stem Cells (MSCs): A Novel Therapy for Type 2 Diabetes

Although plenty of drugs are currently available for type 2 diabetes mellitus (T2DM), a subset of patients still failed to restore normoglycemia. Recent studies proved that symptoms of T2DM patients who are unresponsive to conventional medications could be relieved with mesenchymal stem/stromal cell (MSC) therapy. However, the lack of systematic summary and analysis for animal and clinical studies of T2DM has limited the establishment of standard guidelines in anti-T2DM MSC therapy. Besides, the therapeutic mechanisms of MSCs to combat T2DM have not been thoroughly understood. In this review, we present an overview of the current status of MSC therapy in treating T2DM for both animal studies and clinical studies. Potential mechanisms of MSC-based intervention on multiple pathological processes of T2DM, such as β-cell exhaustion, hepatic dysfunction, insulin resistance, and systemic inflammation, are also delineated. Moreover, we highlight the importance of understanding the pharmacokinetics (PK) of transplanted cells and discuss the hurdles in MSC-based T2DM therapy toward future clinical applications.

Membranes under the Magnetic Lens: A Dive into the Diverse World of Membrane Protein Structures Using Cryo-EM

Membrane proteins are highly diverse in both structure and function and can, therefore, present different challenges for structure determination. They are biologically important for cells and organisms as gatekeepers for information and molecule transfer across membranes, but each class of membrane proteins can present unique obstacles to structure determination. Historically, many membrane protein structures have been investigated using highly engineered constructs or using larger fusion proteins to improve solubility and/or increase particle size. Other strategies included the deconstruction of the full-length protein to target smaller soluble domains. These manipulations were often required for crystal formation to support X-ray crystallography or to circumvent lower resolution due to high noise and dynamic motions of protein subdomains. However, recent revolutions in membrane protein biochemistry and cryo-electron microscopy now provide an opportunity to solve high resolution structures of both large, >1 megadalton (MDa), and small, <100 kDa (kDa), drug targets in near-native conditions, routinely reaching resolutions around or below 3 Å. This review provides insights into how the recent advances in membrane biology and biochemistry, as well as technical advances in cryo-electron microscopy, help us to solve structures of a large variety of membrane protein groups, from small receptors to large transporters and more complex machineries.

Efficacy of subcutaneous semaglutide compared to placebo for weight loss in obese, non-diabetic adults: a systematic review & meta-analysis

BACKGROUND

Research on semaglutide's effect on weight loss has been largely focused on Type 2 Diabetics. No meta-analyses of semaglutide's efficacy in non-diabetic individuals have been conducted to date. Expanding the knowledge of semaglutide's outcome in non-diabetics may provide impactful changes at the clinical level.

AIM

This systematic review and meta-analysis quantified the efficacy of subcutaneous semaglutide in treating obesity in non-diabetic adult patients compared to placebo.

METHOD

Academic Search Premier, Cumulative Index to Nursing and Allied Health Literature (CINAHL) complete, MEDLINE with Full Text, Cochrane Central Register of Controlled Trials, medrxiv.org, and clinicaltrials.gov were systematically investigated using a predetermined search strategy from inception to August 21, 2021. Covidence.org was used to screen, select, and extract data by two independent reviewers. Individual study bias was assessed using the Cochrane Risk of Bias 2 tool. Data were exported to RevMan v5.4, where meta-analysis was conducted using a DerSimonian and Laird random-effects model.

RESULTS

The initial search identified 332 relevant articles and ultimately retained four randomized controlled trials encompassing 2,882 participants with a BMI ≥ 27 kg/m². Patients treated with semaglutide experienced a clinically significant reduction in mean body weight - 11.62 kg (95% CI: -13.03 to -10.21; P < 0.00001).

CONCLUSION

This systematic review and meta-analysis validates the clinical efficacy of semaglutide for the treatment of obesity in the adult, non-diabetic population.

Liraglutide Alleviates Diabetic Atherosclerosis through Regulating Calcification of Vascular Smooth Muscle Cells

Background

Diabetes mellitus (DM) is a group of metabolic diseases characterized by hyperglycemia, which can induce the development of atherosclerosis (AS). Calcification of vascular smooth muscle cells (VSMCs) exerts an important role in the process of AS. In this study, the effects of liraglutide (LIRA) on VSMC under high-glucose condition and its mechanism were explored.

Method

After VSMC was treated by high glucose with or without LIRA in vitro, the alkaline phosphatase (ALP) activity was measured by the detection kit, osteogenic marker protein expression was detected by Western blotting, and calcification was determined by alizarin red staining. Subsequently, the DM rat model was established and the ALP activity, calcification, and osteogenic marker proteins were determined in vivo. Immunohistochemical (IHC) staining and hematoxylin-eosin staining were performed on the thoracic aorta of DM rats.

Result

The positive rate of SMα-actin expression in the DM + AS group was significantly lower than that in control rats, but LIRA administration increased the positive rate in the model. The expression of Cbfα-1 and OPN in the DM + AS group was significantly higher than that in the control group, while it was decreased after treatment of LIRA. The ALP activity and calcium content were increased in DM + AS rats, and the treatment of LIRA decreased the phenotypes in the rats, so as to delay the progression of AS in DM rats. Meanwhile, LIRA inhibited the ALP activity, upregulated SM-α expression, and downregulated expression of OPN and Cbfα-1 in VSMC under high-glucose (HG) conditions. Mechanically, HG-enhanced ALP activity, AKT, and ERK phosphorylation were inhibited by LIRA, PI3K antagonist LY294002, or ERK1/2 antagonist PD98059, in which cotreatment of LIRA with LY294002 and PD98059 could further enhance the effect of LIRA on VSMC, and GLP-1R antagonists reversed the phenotypes in the model. LIRA blocked the osteogenic transformation of VSMC through PI3K and ERK1/2 signaling pathways, which can be reversed by GLP-1R antagonists.

Conclusion

LIRA inhibited the abnormalities in VSMC calcification mediated by the GLP-1R, which was related to PI3K/Akt and ERK1/2 MAPK pathways. Therefore, the prospect and significance of LIRA in the treatment of DM complicated with AS were clarified.

The role of the lateral septum in neuropsychiatric disease

The lateral septum (LS) is a structure in the midline of the brain that is interconnected with areas associated with stress and feeding. This review highlights the role of the LS in anxiety, depression, and eating disorders and their comorbidity. There is a prevailing view that the LS is anxiolytic. This review finds that the LS is both anxiolytic and anxiogenic. Furthermore, the LS can promote and inhibit feeding. Given these shared roles, the LS represents a common site for the comorbidity of neuropsychiatric disorders, and therefore a potential pharmacological target. This is crucial since currently available treatments are not always effective. Corticotrophin-releasing factor 2 antagonists are potential drugs for the treatment of anxiety and anorexia and require further research. Furthermore, other drugs currently in trials for binge eating, such as alpha-adrenergic agonists, may in fact promote food intake. It is hoped that the advancements in chemo- and optogenetic techniques will allow future studies to profile the specific neural connections of the LS and their function. This information could facilitate our understanding of the underlying mechanisms, and therefore pharmacological targets, of these psychiatric conditions.

Meta-analysis of seven heterogeneous studies on liraglutide add-on therapy in patients with type 2 diabetes mellitus treated with insulin

BACKGROUND AND AIMS

Clinical trials indicate the efficacy of add-on therapy using incretin-related drugs to treat type 2 diabetes mellitus (DM) inadequately controlled by insulin. However, heterogeneity exists among these studies. Baseline body mass index (BMI) accounts for the heterogeneity of add-on therapy with dipeptidyl peptidase-4 (DPP-4) inhibitors and the associated higher BMI with a lower efficacy. The efficacy of add-on therapy with glucagon-like peptide-1 (GLP-1) receptor agonists remains unclear.

METHODS

We performed a meta-analysis of randomized controlled trials of ≥12 weeks reporting the endpoint of adjusted mean change in hemoglobin A1c levels (AMΔHbA1c) or hypoglycemia incidence. Patients with type 2 DM treated with insulin alone or with metformin for at least 8 weeks before the study treatment were included. The intervention group received liraglutide co-administered with insulin or a fixed-dose combination. The control group received a placebo or insulin. Covariates included five baseline parameters (HbA1c, fasting plasma glucose, BMI, type 2 DM duration, and treatment duration).

RESULTS

Seven studies (2067 patients) were selected. AMΔHbA1c was -1.00% (95% confidence interval [CI]: -1.21 to -0.78, I² = 74.7%). The odds ratio for hypoglycemia incidence was 0.97 (95% CI: 0.50-1.87, I² = 81.9%). Covariates did not account for the heterogeneity in AMΔHbA1c or hypoglycemia incidence.

CONCLUSIONS

Liraglutide add-on therapy reduced HbA1c levels without increasing hypoglycemia incidence, independent of BMI, in insulin non-responders with type 2 DM. GLP-1 receptor agonists may be more suitable than DPP-4 inhibitors for add-on therapy in patients with high BMI.

REGISTRATION NUMBER

PROSPERO #CRD42021178888.

Dual-agonist incretin peptides from fish with potential for obesity-related Type 2 diabetes therapy - A review

The long-acting glucagon-like peptide-1 receptor (GLP1R) agonist, semaglutide and the unimolecular glucose-dependent insulinotropic polypeptide receptor (GIPR)/GLP1R dual-agonist, tirzepatide have been successfully introduced as therapeutic options for patients with Type-2 diabetes (T2DM) and obesity. Proglucagon-derived peptides from phylogenetically ancient fish act as naturally occurring dual agonists at the GLP1R and the glucagon receptor (GCGR) with lamprey GLP-1 and paddlefish glucagon being the most potent and effective in stimulating insulin release from BRIN-BD11 clonal β-cells. These peptides were also the most effective in lowering blood glucose and elevating plasma insulin concentrations when administered intraperitoneally to overnight-fasted mice together with a glucose load. Zebrafish GIP acts as a dual agonist at the GIPR and GLP1R receptors. Studies with the high fat-fed mouse, an animal model with obesity, impaired glucose-tolerance and insulin-resistance, have shown that twice-daily administration of the long-acting analogs [D-Ala²]palmitoyl-lamprey GLP-1 and [D-Ser²]palmitoyl-paddlefish glucagon over 21 days improves glucose tolerance and insulin sensitivity. This was associated with β-cell proliferation, protection of β-cells against apoptosis, decreased pancreatic glucagon content, improved lipid profile, reduced food intake and selective alteration in the expression of genes involved in β-cell stimulus-secretion coupling. In insulin-deficient Glu^CreERT2;ROSA26-eYFP transgenic mice, the peptides promoted an increase in β-cell mass with positive effects on transdifferentiation of glucagon-producing to insulin-producing cells. Naturally occurring fish dual agonist peptides, particularly lamprey GLP-1 and paddlefish glucagon, provide templates for development into therapeutic agents for obesity-related T2DM.

PEX-168 improves insulin resistance, inflammatory response and adipokines in simple obese mice: a mechanistic exploration

BACKGROUND

Polyethylene glycol loxenatide (PEX-168) is a new antidiabetic drug; as such, there are not yet any reports on its weight loss effect. Therefore, this trial was designed to investigate the effect of PEX-168 on simple obese mice.

METHODS

Thirty healthy male C57BL/6 mice were randomly selected and divided into a control group (NC) and an obesity model group. The high-fat diet-induced simple obesity mice were divided into a model control group (HF) and three intervention groups. The intervention groups were injected with different doses of PEX-168 intraperitoneally once a week for 12 weeks (low (LD), medium (MD) and high (HD)). Fasting blood glucose (FBG), body weight and food intake were measured from 1 to 12 weeks after PEX-168 injection. The serum insulin (INS), C-reactive protein (CRP), chemerin and omentin levels were measured after 12 weeks.

RESULTS

Compared with the HF group, the low dose of PEX-168 reduced the body weight of the mice in a short period of time (8 weeks), and the mice in the MD and HD groups showed a significant decrease in body weight (P < 0.05). The low dose of PEX-168 could effectively improve the blood glucose and homeostasis model assessment of insulin resistance (Homa-IR) of the mice (FBG P < 0.05 INS, Homa-IR P < 0.001), but there was no significant difference between different doses (P > 0.05). CRP levels in the MD and HD groups were significantly improved (P < 0.05). The levels of serum chemerin and omentin in the intervention groups were also significantly improved (P < 0.01), but there was no significant difference between the different doses (P > 0.05).

CONCLUSIONS

PEX-168 significantly reduced the body weight of simple obese mice and improved the insulin resistance. PEX-168 may regulate the expression of chemerin and omentin through its hypoglycaemic effect, and the weight-reducing effect of PEX-168 is unlikely to be the reason for the changes in both.

Pancreatic Safety of Once-Weekly Dulaglutide in Chinese Patients with Type 2 Diabetes Mellitus: Subgroup Analysis by Potential Influencing Factors

INTRODUCTION

In the randomized, open-label, parallel-arm, active-controlled phase III AWARD-CHN2 trial, once-weekly dulaglutide plus concomitant oral antihyperglycemic medications (OAMs) improved HbA1c over 26 weeks compared with once-daily insulin glargine in patients with type 2 diabetes mellitus (T2DM). This post-hoc subgroup analysis of AWARD-CHN2 investigated the pancreatic safety of dulaglutide in Chinese patients with T2DM, stratified by potential influencing factors.

METHODS

Changes in pancreatic enzyme (pancreatic amylase, total amylase, and lipase) levels over 26 weeks were assessed and stratified by patient age (< 60, ≥ 60 years), sex (female, male), duration of diabetes (< 10, ≥ 10 years), baseline weight (< 70, ≥ 70 kg), BMI (< 25, ≥ 25 kg/m²), HbA1c (< 8.5, ≥ 8.5%), triglycerides (< 2.3, ≥ 2.3 mmol/L), and concomitant OAMs (metformin, sulfonylurea, metformin plus sulfonylurea).

RESULTS

A total of 203 Chinese patients with T2DM were included in this post-hoc analysis. Pancreatic enzyme levels increased within the normal range from baseline to Week 26, and no pancreatitis events were confirmed by independent adjudication. Least-squares mean increase in pancreatic amylase (U/L) from baseline to Week 26 was comparable across all subgroups with no statistically (all P-values > 0.05) or clinically significant between-group differences for age (< 60 years: 5.34; ≥ 60 years: 6.71), sex (female: 5.85; male: 5.66), duration of diabetes (< 10 years: 6.15; ≥ 10 years: 4.85), weight (< 70 kg: 6.19; ≥ 70 kg: 5.39), BMI (< 25 kg/m²: 5.92; ≥ 25 kg/m²: 5.61), HbA1c (< 8.5%: 6.82; ≥ 8.5%: 4.08), triglycerides (< 2.3 mmol/L: 4.94; ≥ 2.3 mmol/L: 8.04), and concomitant OAMs (metformin: 5.68; sulfonylurea: 5.44; metformin plus sulfonylurea: 5.87). Similar results were observed for total amylase and lipase.

CONCLUSION

In Chinese patients with T2DM receiving dulaglutide 1.5 mg in AWARD-CHN2, elevations of pancreatic enzymes over 26 weeks were within the normal range and were neither associated with pancreatitis nor baseline factors, which suggests the clinical use of dulaglutide in Chinese patients with T2DM is not associated with pancreatic safety issues.

CLINICAL TRIAL REGISTRATION

NCT01648582.

Long-term functional alterations following prenatal GLP-1R activation

Evidence supporting the use of glucagon-like peptide-1 (GLP-1) analogues to pharmacologically treat disorders beyond type 2 diabetes and obesity is increasing. However, little is known about how activation of the GLP-1 receptor (GLP-1R) during pregnancy affects maternal and offspring outcomes. We treated female C57Bl/6 J mice prior to conception and throughout gestation with a long-lasting GLP-1R agonist, Exendin-4. While GLP-1R activation has significant effects on food and drug reward, depression, locomotor activity, and cognition in adults, we found few changes in these domains in exendin-4-exposed offspring. Repeated injections of Exendin-4 had minimal effects on the dams and may have enhanced maternal care. Offspring exposed to the drug weighed significantly more than their control counterparts during the preweaning period and demonstrated alterations in anxiety-like outcomes, which indicate a developmental role for GLP-1R modulation in the stress response that may be sex-specific.

A 2021 Update on the Use of Liraglutide in the Modern Treatment of 'Diabesity': A Narrative Review

Obesity and type 2 diabetes mellitus have become a significant public health problem in the past decades. Their prevalence is increasing worldwide each year, greatly impacting the economic and personal aspects, mainly because they frequently coexist, where the term “diabesity” may be used. The drug class of glucagon-like peptide 1 receptor agonists (GLP-1 RAs) is one of the most modern therapy options in managing these metabolic disorders. This review focuses on the effects of liraglutide, a long-acting GLP-1 RA, in diabesity and non-diabetic excess weight. This drug class improves glycemic control by enhancing insulin secretion from the beta-pancreatic cells and inhibiting glucagon release. Furthermore, other effects include slowing gastric emptying, increasing postprandial satiety, and reducing the appetite and food consumption by influencing the central nervous system, with weight reduction effects. It also reduces cardiovascular events and has positive effects on blood pressure and lipid profile. A lower-dose liraglutide (1.2 or 1.8 mg/day) is used in patients with diabetes, while the higher dose (3.0 mg/day) is approved as an anti-obesity drug. In this review, we have summarized the role of liraglutide in clinical practice, highlighting its safety and efficacy as a glucose-lowering agent and a weight-reduction drug in patients with and without diabetes.

Proglucagon-Derived Peptides as Therapeutics

Initially discovered as an impurity in insulin preparations, our understanding of the hyperglycaemic hormone glucagon has evolved markedly over subsequent decades. With description of the precursor proglucagon, we now appreciate that glucagon was just the first proglucagon-derived peptide (PGDP) to be characterised. Other bioactive members of the PGDP family include glucagon-like peptides -1 and -2 (GLP-1 and GLP-2), oxyntomodulin (OXM), glicentin and glicentin-related pancreatic peptide (GRPP), with these being produced via tissue-specific processing of proglucagon by the prohormone convertase (PC) enzymes, PC1/3 and PC2. PGDP peptides exert unique physiological effects that influence metabolism and energy regulation, which has witnessed several of them exploited in the form of long-acting, enzymatically resistant analogues for treatment of various pathologies. As such, intramuscular glucagon is well established in rescue of hypoglycaemia, while GLP-2 analogues are indicated in the management of short bowel syndrome. Furthermore, since approval of the first GLP-1 mimetic for the management of Type 2 diabetes mellitus (T2DM) in 2005, GLP-1 therapeutics have become a mainstay of T2DM management due to multifaceted and sustainable improvements in glycaemia, appetite control and weight loss. More recently, longer-acting PGDP therapeutics have been developed, while newfound benefits on cardioprotection, bone health, renal and liver function and cognition have been uncovered. In the present article, we discuss the physiology of PGDP peptides and their therapeutic applications, with a focus on successful design of analogues including dual and triple PGDP receptor agonists currently in clinical development.

Protein Isolates from Raw and Cooked Foxtail Millet Attenuate Development of Type 2 Diabetes in Streptozotocin-Induced Diabetic Mice

SCOPE

Millet protein has received much attention due to its beneficial role in alleviating metabolic disease symptoms. This study aims to investigate the role and molecular mechanism of foxtail millet protein isolates, including protein isolates from raw and cooked foxtail millet in alleviating diabetes, including gut microbiota and intracellular signal pathways.

METHODS AND RESULTS

Protein isolates from raw and cooked foxtail millet are orally administered to streptozotocin (STZ)-induced diabetic mice for 5 weeks before hypoglycemic effect evaluation. The results show that foxtail millet protein isolates improve glucose intolerance and insulin resistance in diabetic mice. However, only the protein isolate from cooked foxtail millet reverse the weight loss trend and alleviate lipid disorders in diabetic mice. Besides, 16S rRNA sequencing show that both raw and cooked foxtail millet protein isolates altered diabetes-induced gut dysbiosis. In addition, western blotting analysis indicated that the protein isolate from cooked foxtail millet increases the expression levels of glucagon-like peptide-1 receptor (GLP-1R), phosphoinositide 3-kinase (PI3K), and phosphoinositide-protein kinase B (p-AKT)/AKT while the protein isolate from raw foxtail millet downregulates stearoyl-coenzyme A desaturase 1 (SCD1) level.

CONCLUSION

Both raw and cooked foxtail millet protein isolates can exert hypoglycemic effects in diabetic mice through rewiring glucose homeostasis, mitigating diabetes-induced gut dysbiosis, and affecting the GLP-1R/PI3K/AKT pathway.

Irisin and Incretin Hormones: Similarities, Differences, and Implications in Type 2 Diabetes and Obesity

Incretins are gut hormones that potentiate glucose-stimulated insulin secretion (GSIS) after meals. Glucagon-like peptide-1 (GLP-1) is the most investigated incretin hormone, synthesized mainly by L cells in the lower gut tract. GLP-1 promotes β-cell function and survival and exerts beneficial effects in different organs and tissues. Irisin, a myokine released in response to a high-fat diet and exercise, enhances GSIS. Similar to GLP-1, irisin augments insulin biosynthesis and promotes accrual of β-cell functional mass. In addition, irisin and GLP-1 share comparable pleiotropic effects and activate similar intracellular pathways. The insulinotropic and extra-pancreatic effects of GLP-1 are reduced in type 2 diabetes (T2D) patients but preserved at pharmacological doses. GLP-1 receptor agonists (GLP-1RAs) are therefore among the most widely used antidiabetes drugs, also considered for their cardiovascular benefits and ability to promote weight loss. Irisin levels are lower in T2D patients, and in diabetic and/or obese animal models irisin administration improves glycemic control and promotes weight loss. Interestingly, recent evidence suggests that both GLP-1 and irisin are also synthesized within the pancreatic islets, in α- and β-cells, respectively. This review aims to describe the similarities between GLP-1 and irisin and to propose a new potential axis-involving the gut, muscle, and endocrine pancreas that controls energy homeostasis.

Incretin Hormones in Obesity and Related Cardiometabolic Disorders: The Clinical Perspective

The prevalence of obesity continues to grow rapidly worldwide, posing many public health challenges of the 21st century. Obese subjects are at major risk for serious diet-related noncommunicable diseases, including type 2 diabetes mellitus, cardiovascular disease, and non-alcoholic fatty liver disease. Understanding the mechanisms underlying obesity pathogenesis is needed for the development of effective treatment strategies. Dysregulation of incretin secretion and actions has been observed in obesity and related metabolic disorders; therefore, incretin-based therapies have been developed to provide new therapeutic options. Incretin mimetics present glucose-lowering properties, together with a reduction of appetite and food intake, resulting in weight loss. In this review, we describe the physiology of two known incretins—glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), and their role in obesity and related cardiometabolic disorders. We also focus on the available and incoming incretin-based medications that can be used in the treatment of the above-mentioned conditions.

Oral GLP1 Analog: Where Does the Tide Go?

T2D is a potentially preventable disease that has been ranked the seventh leading cause of mortality in the United States. There is strong evidence demonstrating that preventing type 2 diabetes is, in many cases, attainable through lifestyle intervention. Unfortunately, prediabetes is mostly overlooked and awareness with diabetes prevention tools is lacking among primary care physicians. Nationally, efforts were not successful in reversing this epidemic even with an array of diabetes medications. Among the most effective medications for T2D are glucagon-like peptide-1 receptor agonists (GLP-1 RAs), which have been shown to reduce both A1C and body weight. Dulaglutide, liraglutide and injectable semaglutide also reduced cardiovascular events and cardiovascular mortality in patients with established cardiovascular disease or multiple cardiovascular risk factors. In this review, we will examine the first FDA approved oral GLP-1 RA; semaglutide. Moreover, this review will discuss the potential impact oral semaglutide may have on glycemic control, weight loss and cardiovascular comorbidities. It also examines the factors that may impact patient compliance, including cost, side effects and clinical issues. Finally, it deliberates the optimism surrounding the development of oral semaglutide in the treatment of diabetes as well as related conditions, such as obesity and non-alcoholic fatty liver disease (NAFLD).

Bile Acids as Key Modulators of the Brain-Gut-Microbiota Axis in Alzheimer's Disease

Recently, the concept of the brain-gut-microbiota (BGM) axis disturbances in the pathogenesis of Alzheimer's disease (AD) has been receiving growing attention. At the same time, accumulating data revealing complex interplay between bile acids (BAs), gut microbiota, and host metabolism have shed new light on a potential impact of BAs on the BGM axis. The crosstalk between BAs and gut microbiota is based on reciprocal interactions since microbiota determines BA metabolism, while BAs affect gut microbiota composition. Secondary BAs as microbe-derived neuroactive molecules may affect each of three main routes through which interactions within the BGM axis occur including neural, immune, and neuroendocrine pathways. BAs participate in the regulation of multiple gut-derived molecule release since their receptors are expressed on various cells. The presence of BAs and their receptors in the brain implies a direct effect of BAs on the regulation of neurological functions. Experimental and clinical data confirm that disturbances in BA signaling are present in the course of AD. Disturbed ratio of primary to secondary BAs as well as alterations in BA concertation in serum and brain samples have been reported. An age-related shift in the gut microbiota composition associated with its decreased diversity and stability observed in AD patients may significantly affect BA metabolism and signaling. Given recent evidence on BA neuroprotective and anti-inflammatory effects, new therapeutic targets have been explored including gut microbiota modulation by probiotics and dietary interventions, ursodeoxycholic acid supplementation, and use of BA receptor agonists.

GLP-1R activation alters performance in cognitive tasks in a sex-dependent manner

RATIONALE

The activation of the glucagon-like peptide-1 receptor (GLP-1R) has been purported to have antidepressant-like and cognitive-enhancing effects. Many people suffering from major depressive disorder (MDD) also experience deficits in cognition. While currently approved antidepressant pharmacotherapies can alleviate the mood symptoms in some patients, they do not treat the cognitive ones.

OBJECTIVES

We tested whether systemic administration of a GLP-1R agonist would alter location discrimination, a cognitive task that is diminished in humans with MDD.

METHODS

Male and female laboratory mice (6-8 weeks old, N = 6-14/sex) were trained in a touchscreen operant task of location discrimination. Upon reaching baseline criterion, mice were administered vehicle or a GLP-1R agonist, Exendin-4, systemically prior to testing in probe trials of varying difficulty.

RESULTS

Following GLP-1R activation, males showed modest yet non-significant performance in the location discrimination task. Females, however, showed enhanced performance during the most difficult probe tests following Exendin-4 administration.

CONCLUSIONS

GLP-1R activation appears to enhance overall performance in the location discrimination task and does so in a sex- and difficulty-dependent manner. These preliminary yet impactful data indicate that GLP-1R agonists may be useful as an adjunctive pharmacotherapy to treat cognitive deficits associated with MDD and/or multiple neurological disorders.

Obesity and Related Type 2 Diabetes: A Failure of the Autonomic Nervous System Controlling Gastrointestinal Function?

The pandemic spread of obesity and type 2 diabetes is a serious health problem that cannot be contained with common therapies. At present, the most effective therapeutic tool is metabolic surgery, which substantially modifies the gastrointestinal anatomical structure. This review reflects the state of the art research in obesity and type 2 diabetes, describing the probable reason for their spread, how the various brain sectors are involved (with particular emphasis on the role of the vagal system controlling different digestive functions), and the possible mechanisms for the effectiveness of bariatric surgery. According to the writer’s interpretation, the identification of drugs that can modulate the activity of some receptor subunits of the vagal neurons and energy-controlling structures of the central nervous system (CNS), and/or specific physical treatment of cortical areas, could reproduce, non-surgically, the positive effects of metabolic surgery.

Differential GLP-1R Binding and Activation by Peptide and Non-peptide Agonists

Peptide drugs targeting class B1 G-protein-coupled receptors (GPCRs) can treat multiple diseases; however, there remains substantial interest in the development of orally delivered non-peptide drugs. Here, we reveal unexpected overlap between signaling and regulation of the glucagon-like peptide-1 (GLP-1) receptor by the non-peptide agonist PF 06882961 and GLP-1 that was not observed for another compound, CHU-128. Compounds from these patent series, including PF 06882961, are currently in clinical trials for treatment of type 2 diabetes. High-resolution cryoelectron microscopy (cryo-EM) structures reveal that the binding sites for PF 06882961 and GLP-1 substantially overlap, whereas CHU-128 adopts a unique binding mode with a more open receptor conformation at the extracellular face. Structural differences involving extensive water-mediated hydrogen bond networks could be correlated to functional data to understand how PF 06882961, but not CHU-128, can closely mimic the pharmacological properties of GLP-1. These findings will facilitate rational structure-based discovery of non-peptide agonists targeting class B GPCRs.

Liraglutide and Insulin Have Contrary Effects on Adipogenesis of Human Adipose-Derived Stem Cells via Wnt Pathway

BACKGROUND

Glucagon-like peptide-1 (GLP-1) has been reported to have beneficial impacts on improving human's metabolism and ameliorating insulin resistance. While insulin is another important and conventional drug in diabetes treatment, but it has an adverse effect on weight gain.

PURPOSE

To make sure whether GLP-1 and insulin play different roles in human adipose-derived stem cells (hADSCs).

METHODS

We examined the in vitro roles and molecular mechanisms of liraglutide, a GLP-1 analogue, and human insulin on hADSCs isolated from subcutaneous adipose tissue. Different concentrations (0, 0.1, 1, 10, 100nM) of liraglutide and insulin were added to proliferation and differentiation medium of hADSCs, respectively.

RESULTS

Liraglutide inhibits while insulin promotes the proliferation and differentiation at the concentration of 100nM. Moreover, the levels of GSK-3 increase during differentiation and liraglutide could down-regulate it when compared with insulin. We also find that the activation of phosphorylated GSK-3α and GSK-3β is involved in the differentiation roles. And classical and non-classical Wnt pathways all play roles in the differentiation, which are characterized with the up/down-regulation of the expression of adipogenesis genes such as PPAR-γ and CEBP-α.

CONCLUSION

Liraglutide and insulin have contrary effects on the proliferation and adipogenesis via Wnt pathway in primary cultured ADSCs. Those effects could partly explain the different roles of GLP-1 and insulin on weight gain and insulin resistance.

A glycosylated Fc-fused glucagon-like peptide-1 receptor agonist exhibits equivalent glucose lowering to but fewer gastrointestinal side effects than dulaglutide

AIM

To evaluate the pharmacokinetic and pharmacodynamic properties of a novel glycosylated Fc-fused glucagon-like peptide-1(GLP-1-gFc) receptor agonist with distinctive receptor binding affinity, designed to improve in vivo stability and safety relative to the commercial GLP-1 analogue dulaglutide, and assess its safety profile and pharmacokinetics in healthy humans.

MATERIALS AND METHODS

We constructed GLP-1-gFc and determined its binding affinity and potency using in vitro instrumental and cell-based analyses followed by in vivo comparison of the glucose-lowering and gastrointestinal side effects between GLP-1-gFc and dulaglutide. A phase 1 clinical trial was conducted to confirm the efficacy and safety profile of GLP-1-gFc.

RESULTS

GLP-1-gFc showed 10-fold less binding affinity and 4-fold less potency than dulaglutide in in vitro. A potency-adjusted dose delayed HbA1c increase comparable with that of dulaglutide (Change for 6 weeks: 2.4 mg/kg GLP-1-gFc, 4.34 ± 0.40 vs. 0.6 mg/kg dulaglutide, 4.26 ± 0.22; n.s.). However, the equivalent efficacy dose and higher dose did not induce malaise-related responses (blueberry bar consumption, g/mouse: 2.4 mg/kg GLP-1-gFc, 0.15% ± 0.03% vs. 0.6 mg/kg dulaglutide, 0.04% ± 0.01%; P < .01) or QT interval changes (mean at 14-20 hours, mSc: 0.28 mg/kg GLP-1-gFc, 0.0-8.0 vs. 0.07 mg/kg dulaglutide, 8.0-27.7; n.s.), observed as safety variables in rats and monkeys, compared with those of dulaglutide. Glucose reductions in an oral glucose tolerance test were significant at day 3 postdose without severe gastrointestinal adverse events and pulse rate changes in healthy subjects.

CONCLUSIONS

These results suggest that GLP-1-gFc could be used as a novel GLP-1 receptor agonist with better safety than dulaglutide to maximize therapeutic benefits in subjects with type 2 diabetes.

The influence of Glucose-dependent Insulinotropic Polypeptide (GIP) on human adipose tissue and fat metabolism: Implications for obesity, type 2 diabetes and Non-Alcoholic Fatty Liver Disease (NAFLD)

Glucose-dependent insulinotropic polypeptide (GIP) and glucagon like peptide (GLP-1) are the two incretin hormones secreted by the enteroendocrine system in response to nutrient ingestion. Compared with GLP-1, GIP is less well studied as a hormone or as a potential pharmacological treatment. Beyond its insulinotropic effects in the pancreas, GIP has important biological actions in many other tissues but its role in dietary fat metabolism and lipid storage in adipose tissue has been most studied. It is still unclear if such effects of GIP on adipose tissue/fat metabolism are protective or deleterious in the long term. Antagonising GIP actions through genetic and chemical disruption in mice models prevented diet induced obesity and improved insulin sensitivity. Whilst such effects of GIP antagonism are yet to be evaluated in humans, recent studies using combined GIP and GLP-1 agonists have shown weight reduction and improved glycaemic control in people with type 2 diabetes (T2D). Therapeutic manipulation of GIP physiology is intriguing in that both agonists and antagonists of GIP are being investigated to explore their potential weight-reducing and other metabolic benefits in people with obesity, T2D and non-alcoholic fatty liver disease (NAFLD). This review will discuss the physiological effects of GIP on fat metabolism in human adipose and other non-adipose tissues such as liver, pancreas, skeletal muscle and heart, describe where the actions of GIP may contribute to the pathophysiology of obesity, T2D and NAFLD and finally describe the therapeutic implications of GIP antagonism and agonism in these conditions.

Selection and progression of unimolecular agonists at the GIP, GLP-1, and glucagon receptors as drug candidates

The continued global growth in the prevalence of obesity coupled with the limited number of efficacious and safe treatment options elevates the importance of innovative pharmaceutical approaches. Combinatorial strategies that harness the metabolic benefits of multiple hormonal mechanisms have emerged at the preclinical and more recently clinical stages of drug development. A priority has been anti-obesity unimolecular peptides that function as balanced, high potency poly-agonists at two or all the cellular receptors for the endocrine hormones glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and glucagon. This report reviews recent progress in this area, with emphasis on what the initial clinical results demonstrate and what remains to be addressed.

A long-acting, dual-agonist analogue of lamprey GLP-1 shows potent insulinotropic, β-cell protective, and anorexic activities and improves glucose homeostasis in high fat-fed mice

Peptidase-resistant analogues of GLP-1 peptides from sea lamprey and paddlefish ([D-Ala²]palmitoyl-lamprey GLP-1 and [D-Ala²]palmitoyl-paddlefish GLP-1) produced significant (P ≤ 0.05) and concentration-dependent increases in insulin release from BRIN-BD11 clonal β-cells and from isolated mouse islets. Both analogues retained the ability of the native peptides to activate both the GLP-1 receptor (GLP1R) and the glucagon receptor (GCGR). [D-Ala²]palmitoyl-lamprey GLP-1 significantly (P < 0.001) stimulated proliferation of BRIN-BD11 cells and protected against cytokine-induced apoptosis. Administration of the lamprey analogue (25 nmol/kg body weight) to lean mice up to 4 h before a glucose load improved glucose tolerance and increased plasma insulin concentrations. Twice daily administration of the lamprey GLP-1 analogue to high fat-fed mice for 21 days decreased body weight, food intake, and circulating glucose and insulin concentrations. The analogue significantly improved glucose tolerance and insulin sensitivity with beneficial effects on islet β-cell area and insulin secretory responsiveness. Islet gene expression of Glp1r, Gcgr and Gipr significantly increased. The lamprey GLP-1 analogue shows therapeutic promise for treatment of patients with obesity-related Type 2 diabetes.

GLP-1 Receptor Agonists in Type 2 Diabetes Mellitus

The rising epidemic of type 2 diabetes mellitus & associated complications is a serious cause of concern for humanity. Glucagon-like peptide-1 receptor agonists commonly abbreviated as GLP-1 RAs, emerged as a promising therapeutic class based on incretin therapy that regulates glucose metabolism through multiple mechanisms. In the present study, various investigational & clinically used GLP-1 RAs have been reviewed with emphasis on their efficacy, structural modifications, adverse effects and toxicities. Various clinical trials justifying their efficacy have also been included, which highlighted the potential of GLP-1 RAs over conventional anti hyperglycaemic agents through a study of pooled effect on glycemic efficacy and weight-loss. The significant potency and appreciable safety of GLP-1 RAs manifested their potential as a logical approach for the management of type 2 diabetes.

Recent Developments in Therapeutic Peptides for the Glucagon-like Peptide 1 and 2 Receptors

Glucagon-like peptide 1 (GLP-1) and glucagon-like peptide 2 (GLP-2) are proglucagon derived peptides that are released from gut endocrine cells in response to nutrient intake. These molecules are rapidly inactivated by the action of dipeptidyl peptidase IV (DPP-4) which limits their use as therapeutic agents. The recent emergence of three-dimensional structures of GPCRs such as GLP-1R and glucagon receptor has helped to drive the rational design of innovative peptide molecules that hold promise as novel peptide therapeutics. One emerging area is the discovery of multifunctional molecules that act at two or more pharmacological systems to enhance therapeutic efficacy. In addition, drug discovery efforts are also focusing on strategies to improve patient convenience through alternative routes of peptide delivery. These novel strategies highlight the broad utility of peptide-based therapeutics in human disease settings where unmet needs still exist.

Controlling Obesity and Metabolic Diseases by Hydrodynamic Delivery of a Fusion Gene of Exendin-4 and α1 Antitrypsin

Obesity and associated metabolic comorbidities represent a growing public health problem. In this study, we demonstrate the use of a newly created fusion gene of exendin-4 and α1-antitrypsin to control obesity and obesity-associated metabolic disorders including insulin resistance, fatty liver and hyperglycemia. The fusion gene encodes a protein with exendin-4 peptide placed at the N-terminus of human α-1 antitrypsin, and is named EAT. Hydrodynamic transfer of the EAT gene to mice prevents high-fat diet-induced obesity, insulin resistance and fatty liver development. In diet-induced obese mice, expression of EAT gene induces weight loss, improves glucose homeostasis, and attenuates hepatic steatosis. In ob/ob mice, EAT gene transfer suppresses body weight gain, maintains metabolic homeostasis, and completely blocks fatty liver development. Six-month overexpression of the EAT fusion gene in healthy mice does not lead to any detectable toxicity. Mechanistic study reveals that the resulting metabolic benefits are achieved by a reduced food take and down-regulation of transcription of pivotal genes responsible for lipogenesis and lipid droplet formation in the liver and chronic inflammation in visceral fat. These results validate the feasibility of gene therapy in preventing and restoring metabolic homeostasis under diverse pathologic conditions, and provide evidence in support of a new strategy to control obesity and related metabolic diseases.

Is there a relationship between PTSD and complicated obesity? A review of the literature

Recent research strongly supports the hypothesis that posttraumatic stress disorder (PTSD) can be accompanied by obesity and related metabolic disturbances. The mechanisms of these associations are however still not well defined, although disturbed functions in the sympathetic-adrenergic nervous system together with the disturbed release of hormones via the endocrine HPA (hypothalamic-pituitary-adrenal) axis apparently play a role. Leptin resistance and ghrelin excesses might contribute to a disturbed hypothalamic function, and also disturb other cerebral functions, leading to dysfunctional reward signaling and uncontrolled appetite combined with a tendency to alcohol abuse. Secondarily, cortisol stimulation will contribute to the development of central obesity which is known to facilitate the development of metabolic syndrome, including slightly increased levels of inflammatory biomarkers such as C-reactive protein and fibrinogen. While previous therapeutic strategies have focused on early psychotherapeutic interventions in PTSD, the present review emphasizes the importance of better therapeutic approaches regarding the somatic correlates of the syndrome. Strict regulation of dietary meals and food composition with minimal intake of sweets and saturated fat, as well as alcohol avoidance, can provide a basic therapeutic framework. A cognitive psychotherapeutic approach with graduated desensitization toward trigging factors, combined with pharmacotherapy, is discussed in the present review.

Glucagon-like peptides-1 from phylogenetically ancient fish show potent anti-diabetic activities by acting as dual GLP1R and GCGR agonists

Glucagon-like peptides-1 (GLP-1)from phylogenetically ancient fish (lamprey, dogfish, ratfish, paddlefish and bowfin) and from a teleost, the rainbow trout produced concentration-dependent stimulations of insulin release from clonal β-cells and isolated mouse islets. Lamprey and paddlefish GLP-1 were the most potent and effective. Incubation of BRIN-BD11 cells with GLP-1 receptor (GLP1R) antagonist, exendin-4 (9-39) attenuated insulinotropic activity of all peptides whereas glucagon receptor (GCGR) antagonist [des-His¹,Pro⁴,Glu⁹] glucagon amide significantly decreased the activities of lamprey and paddlefish GLP-1 only. The GIP receptor antagonist GIP (6-30) Cex-K⁴⁰ [Pal] attenuated the activity of bowfin GLP-1. All peptides (1 μM) produced significant increases in cAMP concentration in CHL cells transfected with GLP1R but only lamprey and paddlefish GLP-1 stimulated cAMP production in HEK293 cells transfected with GCGR. Intraperitoneal administration of lamprey and paddlefish GLP-1 (25 nmol/kg body weight) in mice produced significant decreases in blood glucose and increased insulin concentrations comparable to the effects of human GLP-1. Lamprey and paddlefish GLP-1 display potent insulinotropic activity in vitro and glucose-lowering activity in vivo that is mediated through GLP1R and GCGR so that these peptides may constitute templates for design of new antidiabetic drugs.