Glucagon-like peptide-1 analogues: An overview

β-cell neogenesis: A rising star to rescue diabetes mellitus

BACKGROUND

Diabetes Mellitus (DM), a chronic metabolic disease characterized by elevated blood glucose, is caused by various degrees of insulin resistance and dysfunctional insulin secretion, resulting in hyperglycemia. The loss and failure of functional β-cells are key mechanisms resulting in type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM).

AIM OF REVIEW

Elucidating the underlying mechanisms of β-cell failure, and exploring approaches for β-cell neogenesis to reverse β-cell dysfunction may provide novel strategies for DM therapy.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Emerging studies reveal that genetic susceptibility, endoplasmic reticulum (ER) stress, oxidative stress, islet inflammation, and protein modification linked to multiple signaling pathways contribute to DM pathogenesis. Over the past few years, replenishing functional β-cell by β-cell neogenesis to restore the number and function of pancreatic β-cells has remarkably exhibited a promising therapeutic approach for DM therapy. In this review, we provide a comprehensive overview of the underlying mechanisms of β-cell failure in DM, highlight the effective approaches for β-cell neogenesis, as well as discuss the current clinical and preclinical agents research advances of β-cell neogenesis. Insights into the challenges of translating β-cell neogenesis into clinical application for DM treatment are also offered.

Emerging pharmacological targets for alcohol use disorder

Alcohol Use Disorder (AUD) remains a challenging condition with limited effective treatment options; however new technology in drug delivery and advancements in pharmacology have paved the way for discovery of novel therapeutic targets. This review explores emerging pharmacological targets that offer new options for the management of AUD, focusing on the potential of somatostatin (SST), vasoactive intestinal peptide (VIP), glucagon-like peptide-1 (GLP-1), nociceptin (NOP), and neuropeptide S (NPS). These targets have been selected based on recent advancements in preclinical and clinical research, which suggest their significant roles in modulating alcohol consumption and related behaviors. SST dampens cortical circuits, and targeting both the SST neurons and the SST peptide itself presents promise for treating AUD and various related comorbidities. VIP neurons are modulated by alcohol and targeting the VIP system presents an unexplored avenue for addressing alcohol exposure at various stages of development. GLP-1 interacts with the dopaminergic reward system and reduces alcohol intake. Nociceptin modulates mesolimbic circuitry and agonism and antagonism of nociceptin receptor offers a complex but promising approach to reducing alcohol consumption. NPS stands out for its anxiolytic-like effects, particularly relevant for the anxiety associated with AUD. This review aims to synthesize the current understanding of these targets, highlighting their potential in developing more effective and personalized AUD therapies, and underscores the importance of continued research in identifying and validating novel targets for treatment of AUD and comorbid conditions.

Correlation between type 2 diabetes mellitus remission and intrapancreatic fat deposition

BACKGROUND

Intrapancreatic fat deposition (IPFD) exerts a significant negative impact on patients with type 2 diabetes mellitus (T2DM), accelerates disease deterioration, and may lead to impaired β-cell quality and function.

AIM

To investigate the correlation between T2DM remission and IPFD.

METHODS

We enrolled 80 abdominally obese patients with T2DM admitted to our institution from January 2019 to October 2023, including 40 patients with weight loss-induced T2DM remission (research group) and 40 patients with short-term intensive insulin therapy-induced T2DM remission (control group). We comparatively analyzed improvements in IPFD [differential computed tomography (CT) values of the spleen and pancreas and average CT value of the pancreas]; levels of fasting blood glucose (FBG), 2-h postprandial blood glucose (2hPBG), and insulin; and homeostasis model assessment of insulin resistance (HOMA-IR) scores. Correlation analysis was performed to explore the association between T2DM remission and IPFD.

RESULTS

After treatment, the differential CT values of the spleen and pancreas, FBG, 2hPBG, and HOMA-IR in the research group were significantly lower than those before treatment and in the control group, and the average CT value of the pancreas and insulin levels were significantly higher. Correlation analysis revealed that the greater the T2DM remission, the lower the amount of IPFD.

CONCLUSION

T2DM remission and IPFD are inversely correlated.

From diabetes to diverse domains: the multifaceted roles of GLP-1 receptor agonists

Glucagon-like Peptide-1 (GLP-1) receptor agonists (GLP-1RAs) emerged as a primary treatment for type-2 diabetes mellitus (T2DM), however, their multifaceted effects on various target organs beyond glycemic control opened a new era of treatment. We conducted a comprehensive literature search using databases including Scopus, Google Scholar, PubMed, and the Cochrane Library to identify clinical, in-vivo, and in-vitro studies focusing on the diverse effects of GLP-1 receptor agonists. Eligible studies were selected based on their relevance to the varied roles of GLP-1RAs in T2DM management and their impact on other physiological functions. Numerous studies have reported the efficacy of GLP-1RAs in improving outcomes in T2DM, with demonstrated benefits including glucose-dependent insulinotropic actions, modulation of insulin signaling pathways, and reductions in glycemic excursions. Additionally, GLP-1 receptors are expressed in various tissues and organs, suggesting their widespread physiological functions beyond glycemic control potentially include neuroprotective, anti-inflammatory, cardioprotective, and metabolic benefits. However, further scientific studies are still underway to maximize the benefits of GLP-1RAs and to discover additional roles in improving health benefits. This article sought to review not only the actions of GLP1RAs in the treatment of T2DM but also explore its effects on potential targets in other disorders.

Novel enzyme-resistant pancreatic polypeptide analogs evoke pancreatic beta-cell rest, enhance islet cell turnover, and inhibit food intake in mice

Pancreatic polypeptide (PP) is a postprandial hormone secreted from pancreatic islets that activates neuropeptide Y4 receptors (NPY4Rs). PP is known to induce satiety but effects at the level of the endocrine pancreas are less well characterized. In addition, rapid metabolism of PP by dipeptidyl peptidase-4 (DPP-4) limits the investigation of the effects of the native peptide. Therefore, in the present study, five novel amino acid substituted and/or fatty acid derivatized PP analogs were synthesized, namely [P3]PP, [K13Pal]PP, [P3,K13Pal]PP, [N-Pal]PP, and [N-Pal,P3]PP, and their impact on pancreatic beta-cell function, as well as appetite regulation and glucose homeostasis investigated. All PP analogs displayed increased resistance to DPP-4 degradation. In addition, all peptides inhibited alanine-induced insulin secretion from BRIN-BD11 beta cells. Native PP and related analogs (10-8 and 10-6 M), and especially [P3]PP and [K13Pal]PP, significantly protected against cytokine-induced beta-cell apoptosis and promoted cellular proliferation, with effects dependent on the NPY4R for all peptides barring [N-Pal,P3]PP. In mice, all peptides, except [N-Pal]PP and [N-Pal,P3]PP, evoked a dose-dependent (25, 75, and 200 nmol/kg) suppression of appetite, with native PP and [P3]PP further augmenting glucagon-like peptide-1 (GLP-1) and cholecystokinin (CCK) induced reductions of food intake. The PP peptides had no obvious detrimental effect on glucose tolerance and they did not noticeably impair the glucose-regulatory actions of GLP-1 or CCK. In conclusion, Pro3 amino acid substitution of PP, either alone or together with mid-chain acylation, creates PP analogs with benefits on beta-cell rest, islet cell turnover, and energy regulation that may be applicable to the treatment of diabetes and obesity.

Glucagon like peptide-1 receptor agonists and the risk of skin cancer among patients with type 2 diabetes: Population-based cohort study

AIMS

The objective of this study was to determine whether the use of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) is associated with an increased risk of melanoma and nonmelanoma skin cancer, separately, compared with the use of sulfonylureas among patients with type 2 diabetes.

METHODS

Using the United Kingdom Clinical Practice Research Datalink (2007-2019), we assembled two new-user active comparator cohorts. In the first cohort assessing melanoma as the outcome, 11,786 new users of GLP-1 RAs were compared with 208,519 new users of sulfonylureas. In the second cohort assessing nonmelanoma skin cancer as the outcome, 11,774 new users of GLP-1 RAs were compared with 207,788 new users of sulfonylureas. Cox proportional hazards models weighted using propensity score fine stratification were fit to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of melanoma and nonmelanoma skin cancer, respectively.

RESULTS

Compared with sulfonylureas, GLP-1 RAs were not associated with an increased risk of either melanoma (42.6 vs. 43.9 per 100,000 person-years, respectively; HR 0.96, 95% CI 0.53-1.75) or nonmelanoma skin cancer (243.9 vs. 229.9 per 100,000 person-years, respectively; HR 1.03, 95% CI 0.80-1.33). There was no evidence of an association between cumulative duration of use with either melanoma or nonmelanoma skin cancer. Consistent results were observed in secondary and sensitivity analyses.

CONCLUSIONS

In this population-based cohort study, GLP-1 RAs were not associated with an increased risk of melanoma or nonmelanoma skin cancer, compared with sulfonylureas.

New insights into nanomedicines for oral delivery of glucagon-like peptide-1 analogs

Type 2 diabetes mellitus (T2DM) is a metabolic disorder that arises when the body cannot respond fully to insulin, leading to impaired glucose tolerance. Currently, the treatment embraces non-pharmacological actions (e.g., diet and exercise) co-associated with the administration of antidiabetic drugs. Metformin is the first-line treatment for T2DM; nevertheless, alternative therapeutic strategies involving glucagon-like peptide-1 (GLP-1) analogs have been explored for managing the disease. GLP-1 analogs trigger insulin secretion and suppress glucagon release in a glucose-dependent manner thereby, reducing the risk of hyperglycemia. Additionally, GLP-1 analogs have an extended plasma half-life compared to the endogenous peptide due to their high resistance to degradation by dipeptidyl peptidase-4. However, GLP-1 analogs are mainly administered via subcutaneous route, which can be inconvenient for the patients. Even considering an oral delivery approach, GLP-1 analogs are exposed to the harsh conditions of the gastrointestinal tract (GIT) and the intestinal barriers (mucus and epithelium). Hereupon, there is an unmet need to develop non-invasive oral transmucosal drug delivery strategies, such as the incorporation of GLP-1 analogs into nanoplatforms, to overcome the GIT barriers. Nanotechnology has the potential to shield antidiabetic peptides against the acidic pH and enzymatic activity of the stomach. In addition, the nanoparticles can be coated and/or surface-conjugated with mucodiffusive polymers and target intestinal ligands to improve their transport through the intestinal mucus and epithelium. This review focuses on the main hurdles associated with the oral administration of GLP-1 and GLP-1 analogs, and the nanosystems developed to improve the oral bioavailability of the antidiabetic peptides. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Glucagon-like peptide-1 analogues in monogenic syndromic obesity: Real-world data from a large cohort of Alström syndrome patients

AIM

To examine the real-world efficacy of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) in monogenic obesity in patients with Alström syndrome (ALMS).

METHODS

We screened 72 UK adult patients with ALMS and offered treatment to 34 patients meeting one of the following criteria: body mass index of 25 kg/m2 or higher, insulin resistance, suboptimal glycaemic control on antihyperglycaemic medications or non-alcoholic fatty liver disease.

RESULTS

In total, 30 patients, with a mean age of 31 ± 11 years and a male to-female ratio of 2:1, completed 6 months of treatment with GLP-1 RAs either in the form of semaglutide or exenatide. On average, treatment with GLP-1 RAs reduced body weight by 5.4 ± 1.7 (95% confidence interval [CI] 3.6-7) kg and HbA1c by 12 ± 3.3 (95% CI 8.7-15.3) mmol/mol, equating to 6% weight loss (P < .01) and 1.1% absolute reduction in HbA1c (P < .01). Significant improvements were also observed in serum total cholesterol, triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and alanine aminotransferase. The improvement of metabolic variables in our cohort of monogenic syndromic obesity was comparable with data for polygenic obesity, irrespective of weight loss.

CONCLUSIONS

Data from our centre highlight the non-inferiority of GLP-1 RAs in monogenic syndromic obesity to the available GLP-1 RA-use data in polygenic obesity, therefore, these agents can be considered as a treatment option in patients with ALMS, as well as other forms of monogenic obesity.

Risk of major adverse cardiovascular events and stroke associated with treatment with GLP-1 or the dual GIP/GLP-1 receptor agonist tirzepatide for type 2 diabetes: A systematic review and meta-analysis

INTRODUCTION

Mounting evidence suggests that glucagon-like-peptide-1 receptor-agonists (GLP-1 RAs) attenuate cardiovascular-risk in type-2 diabetes (T2DM). Tirzepatide is the first-in-class, dual glucose-dependent-insulinotropic-polypeptide GIP/GLP-1 RA approved for T2DM.

PATIENTS AND METHODS

A systematic review and meta-analysis of randomized-controlled clinical trials (RCTs) was performed to estimate: (i) the incidence of major adverse cardiovascular events (MACE); and (ii) incidence of stroke, fatal, and nonfatal stroke in T2DM-patients treated with GLP-1 or GIP/GLP-1 RAs (vs placebo).

RESULTS

Thirteen RCTs (9 and 4 on GLP-1 RAs and tirzepatide, respectively) comprising 65,878 T2DM patients were included. Compared to placebo, GLP-1RAs or GIP/GLP-1 RAs reduced MACE (OR: 0.87; 95% CI: 0.81-0.94; p < 0.01; I2 = 37%), all-cause mortality (OR: 0.88; 95% CI: 0.82-0.96; p < 0.01; I2 = 21%) and cardiovascular-mortality (OR: 0.88; 95% CI: 0.80-0.96; p < 0.01; I2 = 14%), without differences between GLP-1 versus GIP/GLP-1 RAs. Additionally, GLP-1 RAs reduced the odds of stroke (OR: 0.84; 95% CI: 0.76-0.93; p < 0.01; I2 = 0%) and nonfatal stroke (OR: 0.85; 95% CI: 0.76-0.94; p < 0.01; I2 = 0%), whereas no association between fatal stroke and GLP-1RAs was uncovered (OR: 0.80; 95% CI: 0.61-1.05; p = 0.105; I2 = 0%). In secondary analyses, GLP-1 RAs prevented ischemic stroke (OR: 0.74; 95% CI: 0.61-0.91; p < 0.01; I2 = 0%) and MACE-recurrence, but not hemorrhagic stroke (OR: 0.92; 95% CI: 0.51-1.66; p = 0.792; I2 = 0%). There was no association between GLP-1RAs or GIP/GLP-1 RAs and fatal or nonfatal myocardial infarction.

DISCUSSION AND CONCLUSION

GLP-1 and GIP/GLP-1 RAs reduce cardiovascular-risk and mortality in T2DM. While there is solid evidence that GLP-1 RAs significantly attenuate the risk of ischemic stroke in T2DM, dedicated RCTs are needed to evaluate the efficacy of novel GIP/GLP-1 RAs for primary and secondary stroke prevention.

Special Issue: "Anti-inflammatory Effects of Glucagon-like Peptide-1"

From the failure of gut extracts in diabetic patients' therapy to the effective action in cardiovascular outcomes [...].

Designing and computational analyzing of chimeric long-lasting GLP-1 receptor agonists for type 2 diabetes

Glucagon-like peptide-1 (GLP-1) is an intestinally derived incretin that plays a vital role in engineering the biological circuit involved in treating type 2 diabetes. Exceedingly short half-life (1-2 min) of GLP-1 limits its therapeutic applicability, and the implication of its new variants is under question. Since albumin-binding DARPin as a mimetic molecule has been reported to increase the serum half-life of therapeutic compounds, the interaction of new variants of GLP-1 in fusion with DARPin needs to be examined against the GLP-1 receptor. This study was aimed to design stable and functional fusion proteins consisting of new protease-resistant GLP-1 mutants (mGLP1) genetically fused to DARPin as a critical step toward developing long-acting GLP-1 receptor agonists. The stability and solubility of the engineered fusion proteins were analyzed, and their secondary and tertiary structures were predicted and satisfactorily validated. Molecular dynamics simulation studies revealed that the predicted structures of engineered fusion proteins remained stable throughout the simulation. The relative binding affinity of the engineered fusion proteins' complex with human serum albumin and the GLP-1 receptor individually was assessed using molecular docking analyses. It revealed a higher affinity compared to the interaction of the individual GLP-1 and HSA-binding DARPin with the GLP-1 receptor and human serum albumin, respectively. The present study suggests that engineered fusion proteins can be used as a potential molecule in the treatment of type 2 diabetes, and this study provides insight into further experimental use of mimetic complexes as alternative molecules to be evaluated as new bio-breaks in the engineering of biological circuits in the treatment of type 2 diabetes.

Advances in Anti-obesity Pharmacotherapy: Current Treatments, Emerging Therapies, and Challenges

Obesity is a major public health concern linked to health risks such as hypertension, hyperlipidemia, type 2 diabetes mellitus (T2DM), stroke, metabolic syndrome, asthma, and cancer. It is among the leading causes of morbidity and mortality worldwide caused by an unhealthy diet and lack of physical activity, but genetic or hormonal factors may also contribute. Over a third of adults in the United States are obese. Pharmacological agents have been designed to reduce weight gain caused by excessive calorie intake and low physical activity. They work by inhibiting the absorption of dietary fat or stimulating the secretion of satiety hormones. These drugs include lipase inhibitors and glucagon-like peptide 1 (GLP-1) receptor agonists. However, the current weight-loss strategies do not effectively treat genetic-related diseases, such as generalized lipodystrophy, Bardet-Biedl syndrome, and proopiomelanocortin (POMC) deficiency. Emerging therapies for these gene mutations have been developed targeting leptin and melanocortin-4 receptors (MC4Rs), restoring the normal function of leptin or melanocortin-4 receptors regulating energy balance and appetite. Leptin analogs and MC4R agonists are novel therapies that target genetic or hormonal causes of obesity. This article provides a comprehensive review of anti-obesity medications (AOMs). In this review, we discuss the clinical trials, efficacy, United States FDA-approved indication, contraindications, and serious side effects of different classes of drugs, including lipase inhibitors, GLP-1 agonists, leptin analogs, and MC4R agonists.

Obesity management for cardiovascular disease prevention

Background

Obesity is a complex disease that leads to higher morbidity and mortality and its rate in the United States is rapidly rising. Targeting obesity management is one of the cornerstones of preventive medicine. Early intervention can significantly reduce the risk of developing cardiovascular disease. While it is well known that lifestyle interventions such as healthful nutrition and routine physical activity are the first and most important step in management, some do not achieve the desired results and require further therapies.

Methods

A literature review was conducted, that included clinical documents, public scientific citations and peer review articles to evaluate anti-obesity medications, endoscopic procedures and bariatric surgeries in the management of obesity. We also included effects of these interventions on weight loss, cardiovascular disease risk reduction and side effects.

Results

This clinical review summarizes recent evidence for the different approaches in obesity management including medications, common endoscopic procedures and bariatric surgeries. For more detailed review on the different management options discussed, we recommend reviewing Obesity Medicine Association Clinical Practice Statement [1].

Conclusion

Management of obesity reduces cardiovascular risk, improves metabolic parameters and other important health outcomes. Different management approaches are available, hence, a high level of awareness of the growing epidemic of obesity is needed to ensure timely referrals to obesity medicine specialists.

The protective role of GLP-1 in neuro-ophthalmology

Despite recent advancements in the field of neuro-ophthalmology, the rising rates of neurological and ophthalmological conditions, mismatches between supply and demand of clinicians, and an aging population underscore the urgent need to explore new therapeutic approaches within the field. Glucagon-like peptide 1 receptor agonists (GLP-1RAs), traditionally used in the treatment of type 2 diabetes, are becoming increasingly appreciated for their diverse applications. Recently, GLP-1RAs have been approved for the treatment of obesity and recognized for their cardioprotective effects. Emerging evidence indicates some GLP-1RAs can cross the blood-brain barrier and may have neuroprotective effects. Therefore, this article aims to review the literature on the neurologic and neuro-ophthalmic role of glucagon-like peptide 1 (GLP-1). This article describes GLP-1 peptide characteristics and the mechanisms mediating its known role in increasing insulin, decreasing glucagon, delaying gastric emptying, and promoting satiety. This article identifies the sources and targets of GLP-1 in the brain and review the mechanisms which mediate its neuroprotective effects, as well as implications for Alzheimer's disease (AD) and Parkinson's disease (PD). Furthermore, the preclinical works which unravel the effects of GLP-1 in ocular dynamics and the preclinical literature regarding GLP-1RA use in the management of several neuro-ophthalmic conditions, including diabetic retinopathy (DR), glaucoma, and idiopathic intracranial hypertension (IIH) are discussed.

Recent advancements in pharmacological strategies to modulate energy balance for combating obesity

The prevalence of obesity along with its related metabolic diseases has increased globally in recent decades. Obesity originates from a heterogeneous physiological state, which is further complicated by the influence of factors such as genetic, behavioural, and environmental. Lifestyle interventions including exercise and diet have limited success, necessitating the development of pharmacological approaches. Mechanistically, strategies target either reducing energy intake or increasing consumption through metabolism boosting. Current drugs lower energy intake via inducing satiety or inhibiting substrate absorption, while targeting mitochondria or cytosolic energy sensors has shown limited success due to toxicity. Nonshivering thermogenesis (NST) has provided hope for activating these processes selectively without significant side effects. The internet-based marketing of plant-based formulations for enhancing metabolism has surged. This review compiles scientific articles, magazines, newspapers, and online resources on anti-obesity drug development. Combination therapy of metabolic boosters and established anti-obesity compounds appears to be a promising future approach that requires further research.

Multifaceted Roles of GLP-1 and Its Analogs: A Review on Molecular Mechanisms with a Cardiotherapeutic Perspective

Diabetes is one of the chronic metabolic disorders which poses a multitude of life-debilitating challenges, including cardiac muscle impairment, which eventually results in heart failure. The incretin hormone glucagon-like peptide-1 (GLP-1) has gained distinct recognition in reinstating glucose homeostasis in diabetes, while it is now largely accepted that it has an array of biological effects in the body. Several lines of evidence have revealed that GLP-1 and its analogs possess cardioprotective effects by various mechanisms related to cardiac contractility, myocardial glucose uptake, cardiac oxidative stress and ischemia/reperfusion injury, and mitochondrial homeostasis. Upon binding to GLP-1 receptor (GLP-1R), GLP-1 and its analogs exert their effects via adenylyl cyclase-mediated cAMP elevation and subsequent activation of cAMP-dependent protein kinase(s) which stimulates the insulin release in conjunction with enhanced Ca²⁺ and ATP levels. Recent findings have suggested additional downstream molecular pathways stirred by long-term exposure of GLP-1 analogs, which pave the way for the development of potential therapeutic molecules with longer lasting beneficial effects against diabetic cardiomyopathies. This review provides a comprehensive overview of the recent advances in the understanding of the GLP-1R-dependent and -independent actions of GLP-1 and its analogs in the protection against cardiomyopathies.

In Vitro Screening for Probiotic Properties of Lactobacillus and Bifidobacterium Strains in Assays Relevant for Non-Alcoholic Fatty Liver Disease Prevention

Non-alcoholic fatty liver disease (NAFLD) is a multifactorial metabolic disorder that poses health challenges worldwide and is expected to continue to rise dramatically. NAFLD is associated with metabolic syndrome, type 2 diabetes mellitus, and impaired gut health. Increased gut permeability, caused by disturbance of tight junction proteins, allows passage of damaging microbial components that, upon reaching the liver, have been proposed to trigger the release of inflammatory cytokines and generate cellular stress. A growing body of research has suggested the utilization of targeted probiotic supplements as a preventive therapy to improve gut barrier function and tight junctions. Furthermore, specific microbial interactions and metabolites induce the secretion of hormones such as GLP-1, resulting in beneficial effects on liver health. To increase the likelihood of finding beneficial probiotic strains, we set up a novel screening platform consisting of multiple in vitro and ex vivo assays for the screening of 42 bacterial strains. Analysis of transepithelial electrical resistance response via co-incubation of the 42 bacterial strains with human colonic cells (Caco-2) revealed improved barrier integrity. Then, strain-individual metabolome profiling was performed revealing species-specific clusters. GLP-1 secretion assay with intestinal secretin tumor cell line (STC-1) found at least seven of the strains tested capable of enhancing GLP-1 secretion in vitro. Gene expression profiling in human biopsy-derived intestinal organoids was performed using next generation sequencing transcriptomics post bacterial co-incubation. Here, different degrees of immunomodulation by the increase in certain cytokine and chemokine transcripts were found. Treatment of mouse primary hepatocytes with selected highly produced bacterial metabolites revealed that indole metabolites robustly inhibited de novo lipogenesis. Collectively, through our comprehensive bacterial screening pipeline, not previously ascribed strains from both Lactobacillus and Bifidobacterium genera were proposed as potential probiotics based on their ability to increase epithelial barrier integrity and immunity, promote GLP-1 secretion, and produce metabolites relevant to liver health.

Fixed-ratio combinations of basal insulin and glucagon-like peptide-1 receptor agonists as a promising strategy for treating diabetes

The maintenance of appropriate glycemic control is important for the prevention of diabetic complications in people with type 2 diabetes (T2D). Numerous oral antidiabetic drugs are now clinically available, but in particular, the introduction of injection regimens using insulin and/or glucagon-like peptide-1 receptor agonist (GLP-1RA)s represents promising step-up options for oral antidiabetic drug treatment. The recently licensed fixed-ratio combination (FRC) products, which comprise basal insulin and a GLP-1RA, have potent anti-hyperglycemic effects and reduce the undesirable side-effects of each component, such as body weight gain, hypoglycemia, and gastrointestinal symptoms. Two FRCs-insulin degludec/Liraglutide and insulin glargine/Lixisenatide-are now clinically available and, to date, several phase II/III trials have been conducted in particular groups of subjects with T2D. However, their utility in real-world clinical settings is of interest for most clinicians. Recently reported real-world clinical trials of these two FRCs in various situations have demonstrated their efficacy regarding glycemic control and the quality of life of people with T2D. Their long-term safety and efficacy require confirmation, but a treatment strategy that includes an FRC may be compatible with the concept of “well-balanced” therapy in certain groups of patients with T2D who have inadequate glycemic control.

Interaction between inorganic phosphate concentration and glucose metabolism in mild refeeding syndrome model

Refeeding syndrome is a major clinical problem that leads to fatal complications in patients suffering from malnutrition. Hypophosphatemia inevitably is observed at the onset of refeeding syndrome and therefore is monitored during refeeding; however, the causes of metabolic changes in phosphate concentration during refeeding remain poorly understood. In a previous study, we established a refeeding syndrome model employing total parenteral nutrition with insulin-induced hypophosphatemia, but the symptoms were severe and the metabolic mechanisms in this model may not have been representative of clinical conditions. Therefore, we established a new animal model of mild refeeding syndrome by using a shorter fasting period followed by a single refeeding. These mild refeeding syndrome-model rats exhibited hypophosphatemia without increases in urinary phosphate excretion. Interestingly, administration of the combination of phosphate and insulin during refeeding promoted insulin secretion during refeeding. This model implies that Pi may directly promote insulin secretion in pancreatic cells. These results clarify the interaction between phosphate and glucose metabolism pancreatic cells during refeeding syndrome in a mild refeeding syndrome model.

Medicines for Obesity: Appraisal of Clinical Studies with Grading of Recommendations, Assessment, Development, and Evaluation Tool

We evaluated the quality of evidence from phase III/IV clinical trials of drugs against obesity using the principles of Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) tool. Our systematic review evaluates the quality of clinical evidence from existing clinical trials and not the pharmacological efficacy of anti-obesity therapies. A literature search using select keywords in separate was performed in PubMed and ClinicalTrials.gov databases for phase III/IV clinical trials during the last ten years. Our findings indicate that the quality of existing clinical evidence from anti-obesity trials generally ranges from low to moderate. Most trials suffered from publication bias. Less frequently, trials suffered from the risk of bias mainly due to lack of blindness in the treatment. Our work indicates that additional higher-quality clinical trials are needed to gain more confidence in the estimate of the effect of currently used anti-obesity medicines, to allow more informed clinical decisions, thus reducing the risk of implementing potentially ineffective or even harmful therapeutic strategies.

Impact of GLP-1 receptor agonist versus omega-3 fatty acids supplement on obesity-induced alterations of mitochondrial respiration

OBJECTIVE

To compare administration of the glucagon-like peptide-1 (GLP-1) analogue, exenatide, versus dietary supplementation with the omega-3 fatty acid-rich Calanus oil on obesity-induced alterations in mitochondrial respiration.

METHODS

Six-week-old female C57BL/6JOlaHSD mice were given high fat diet (HFD, 45% energy from fat) for 12 weeks to induce obesity. Thereafter, they were divided in three groups where one received exenatide (10 μg/kg/day) via subcutaneously implanted mini-osmotic pumps, a second group received 2% Calanus oil as dietary supplement, while the third group received HFD without any treatment. Animals were sacrificed after 8 weeks of treatment and tissues (skeletal muscle, liver, and white adipose tissue) were collected for measurement of mitochondrial respiratory activity by high-resolution respirometry, using an Oroboros Oxygraph-2k (Oroboros instruments, Innsbruck, Austria).

RESULTS

It was found that high-fat feeding led to a marked reduction of mitochondrial respiration in adipose tissue during all three states investigated - LEAK, OXPHOS and ETS. This response was to some extent attenuated by exenatide treatment, but not with Calanus oil treatment. High-fat feeding had no major effect on hepatic mitochondrial respiration, but exenatide treatment resulted in a significant increase in the various respiratory states in liver. Mitochondrial respiration in skeletal muscle was not significantly influenced by high-fat diet or any of the treatments. The precise evaluation of mitochondrial respiration considering absolute oxygen flux and ratios to assess flux control efficiency avoided misinterpretation of the results.

CONCLUSIONS

Exenatide increased hepatic mitochondrial respiration in high-fat fed mice, but no clear beneficial effect was observed in skeletal muscle or fat tissue. Calanus oil did not negatively affect respiratory activity in these tissues, which maintains its potential as a dietary supplement, due to its previously reported benefits on cardiac function.

Frequency of GLP-1 receptor agonists use in diabetic patients diagnosed with delayed gastric emptying and their demographic profile

Advances in the management of diabetes mellitus have come a long way in the 21st century. One of the most important developments in diabetes management has been the discovery of glucagon-like peptide-1 (GLP-1) receptor agonists. The most common side effects of GLP-1 receptor (GLP-1R) agonists are nausea and vomiting which have been attributed to delayed gastric emptying. While the effects of GLP-1R agonists on gastric emptying have prompted further research in this field, there are limited studies evaluating their effects on patients with pre-existing gastroparesis. Additionally, the frequency of GLP-1R agonist use among patients with gastroparesis has not been assessed in the past and this study aims to identify that percentage along with evaluating for possible iatrogenic gastroparesis. A retrospective review of all the gastric emptying studies performed at one academic medical center between January 2019 and January 2021 was performed. We found that although patients on GLP-1R agonists were more likely to have delayed gastric emptying, we could not establish a statistical significance. This could be due to the small sample size in the study. However, GLP-1R agonists use was associated with delayed gastric emptying in patients with diabetes for <10 years. Moreover, a significant proportion (24%) of patients with diabetes with delayed gastric emptying were on a GLP-1R agonist. Recently, semaglutide (GLP-1R agonist) gained Food and Drug Administration approval as a weight loss medication in both patients with and without diabetes. This should prompt further research to evaluate the safety profile of these medications in patients with and without pre-existing gastroparesis.

Network meta-analysis on the effects of finerenone versus SGLT2 inhibitors and GLP-1 receptor agonists on cardiovascular and renal outcomes in patients with type 2 diabetes mellitus and chronic kidney disease

Objective

To evaluate the cardiovascular and renal benefits of finerenone, sodium-glucose cotransporter-2 inhibitors (SGLT2i) and glucagonlike peptide-1 receptor agonists (GLP-1 RA) in patients with Type 2 Diabetes Mellitus (T2DM) and chronic kidney disease (CKD) with network meta-analysis.

Methods

Systematic literature searches were conducted of PubMed, Cochrane Library, Web of Science, Medline and Embase covering January 1, 2000 to December 30, 2021. Randomized control trials (RCTs) comparing finerenone, SGLT-2i and GLP-1 RA in diabetics with CKD were selected. We performed a network meta-analysis to compare the two drugs and finerenone indirectly. Results were reported as risk ratio (RR) with corresponding 95% confidence interval (CI).

Results

18 RCTs involving 51,496 patients were included. Finerenone reduced the risk of major adverse cardiovascular events (MACE), renal outcome and hospitalization for heart failure (HHF) (RR [95% CI]; 0.88 [0.80–0.97], 0.86 [0.79–0.93], 0.79 [0.67,0.92], respectively). SGLT-2i were associated with reduced risks of MACE (RR [95% CI]; 0.84 [0.78–0.90]), renal outcome (RR [95% CI]; 0.67 [0.60–0.74], HHF (RR [95% CI]; 0.60 [0.53–0.68]), all-cause death (ACD) (RR [95% CI]; 0.89 [0.81–0.91]) and cardiovascular death (CVD) (RR [95% CI]; 0.86 [0.77–0.96]) compared to placebo. GLP-1 RA were associated with a lower risk of MACE (RR [95% CI]; 0.86 [0.78–0.94]). SGLT2i had significant effect in comparison to finerenone (finerenone vs SGLT2i: RR [95% CI]; 1.29 [1.13–1.47], 1.31 [1.07–1.61], respectively) and GLP-1 RA (GLP-1 RA vs SGLT2i: RR [95% CI]; 1.36 [1.16–1.59], 1.49 [1.18–1.89], respectively) in renal outcome and HHF.

Conclusions

In patients with T2DM and CKD, SGLT2i, GLP-1 RA and finerenone were comparable in MACE, ACD and CVD. SGLT2i significantly decreased the risk of renal events and HHF compared with finerenone and GLP-1 RA. Among GLP-1 RA, GLP-1 analogues showed significant effect in reducing cardiovascular events compared with exendin-4 analogues.

DPP-4 inhibitors and GLP-1RAs: cardiovascular safety and benefits

Glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors are commonly used treatments for patients with type 2 diabetes mellitus (T2DM). Both anti-diabetic treatments function by playing key modulatory roles in the incretin system. Though these drugs have been deemed effective in treating T2DM, the Food and Drug Administration (FDA) and some members of the scientific community have questioned the safety of these therapeutics relative to important cardiovascular endpoints. As a result, since 2008, the FDA has required all new drugs for glycemic control in T2DM patients to demonstrate cardiovascular safety. The present review article strives to assess the safety and benefits of incretin-based therapy, a new class of antidiabetic drug, on the health of patient cardiovascular systems. In the process, this review will also provide a physiological overview of the incretin system and how key components function in T2DM.

Role of Dipeptidyl Peptidase-4 (DPP4) on COVID-19 Physiopathology

DPP4/CD26 is a single-pass transmembrane protein with multiple functions on glycemic control, cell migration and proliferation, and the immune system, among others. It has recently acquired an especial relevance due to the possibility to act as a receptor or co-receptor for SARS-CoV-2, as it has been already demonstrated for other coronaviruses. In this review, we analyze the evidence for the role of DPP4 on COVID-19 risk and clinical outcome, and its contribution to COVID-19 physiopathology. Due to the pathogenetic links between COVID-19 and diabetes mellitus and the hyperinflammatory response, with the hallmark cytokine storm developed very often during the disease, we dive deep into the functions of DPP4 on carbohydrate metabolism and immune system regulation. We show that the broad spectrum of functions regulated by DPP4 is performed both as a protease enzyme, as well as an interacting partner of other molecules on the cell surface. In addition, we provide an update of the DPP4 inhibitors approved by the EMA and/or the FDA, together with the newfangled approval of generic drugs (in 2021 and 2022). This review will also cover the effects of DPP4 inhibitors (i.e., gliptins) on the progression of SARS-CoV-2 infection, showing the role of DPP4 in this disturbing disease.

Therapeutic potential of dopamine agonists in the treatment of type 2 diabetes mellitus

Diabetes is a global health concern that has affected almost 415 million people globally. Bromocriptine is a dopamine D2 agonist, which is a Food and Drug Administration (FDA)-approved drug to treat type 2 diabetes mellitus (T2DM) patients. However, it is considered that a novel treatment therapy is required which can be used in the treatment of diabetes with or without other antidiabetic agents. Dopamine agonists are usually used in neurological disorders like Parkinson's disease (PD), restless leg syndrome, and hyperprolactinemia. However, dopamine agonists including bromocriptine and cabergoline are also effective in reducing the glycemic level in T2DM patients. Bromocriptine was formerly used for the treatment of PD, hyperprolactinemia, and restless leg syndrome, but now it is used for improving glycemic levels as well as reducing free fatty acids and triglycerides. In addition, cabergoline has been found to be effective in glycemic control, but this drug is yet to be approved by the FDA due to its limitations and lack of study. Findings of the clinical trials of bromocriptine have suggested that it reduces almost 0.4-0.8% glycated hemoglobin and cardiovascular risk by 40% in insulin-resistant patients. Moreover, the safe use of bromocriptine in obese T2DM patients makes it a more attractive option as it causes weight loss. Indeed, bromocriptine is a novel therapy for T2DM patients, as its mechanism of action is unique in T2DM patients with minimal adverse effects. This review summarizes the potential of dopamine agonists in the treatment of T2DM.

Meta-analysis of cardiovascular outcome trials assessing the impact of glucagon-like peptide-1 receptor agonists on major cardiac arrhythmias

OBJECTIVE

Glucagon-like peptide-1 receptor agonists (GLP-1RAs), a group of novel antidiabetic agents, demonstrated beneficial cardiovascular effects in recent large, placebo-controlled randomised clinical trials (RCTs); their clear antiarrhythmic benefit has not been yet underlined. The purpose of the present meta-analysis is to clarify the impact of GLP-1RAs on different types of cardiac arrhythmias.

METHODS

We searched PubMed from its inception up to 8 October 2020 for all available cardiovascular and renal outcome, placebo-controlled RCTs utilising GLP-1RAs versus placebo. The present meta-analysis is reported according to the Preferred Reporting Items for Systematic reviews and Meta-analyses (PRISMA) statement.

RESULTS

We included data from 7 RCTs with GLP-1RAs in a total of 55,943 participants. Treatment with GLP-1RAs did not provide significant benefit in the risk for atrial fibrillation (RR = 0.81, 95%CI; 0.78-1.15, I² = 51%), atrial flutter (RR = 0.79, 95%CI; 0.53-1.16, I² = 0%), ventricular fibrillation (RR = 0.99, 95%CI; 0.48-2.04, I² = 0%), ventricular tachycardia (RR = 1.41, 95%CI; 0.87-2.28, I² = 10%), atrial tachycardia (RR = 0.63, 95%CI; 0.10-3.90, I² = 24%), sinus node dysfunction (RR = 0.70, 95%CI; 0.40-1.23, I² = 0%), ventricular extrasystoles (RR = 1.37, 95%CI; 0.56-3.30, I² = 0%), second-degree atrioventricular block (RR = 0.96, 95%CI; 0.52-1.74, I² = 0%) or complete atrioventricular block (RR = 0.78, 95%CI; 0.39-1.54, I² = 38%).

CONCLUSIONS

In patients with type 2 diabetes mellitus, treatment with GLP-1RAs does not significantly affect the risk for major cardiac arrhythmias.

A novel strategy for production of liraglutide precursor peptide and development of a new long-acting incretin mimic

Nowadays, a small number of incretin mimics are used to treat type 2 diabetes mellitus (T2DM) due to their longer half-life. The present study aimed to introduce a novel method for producing the liraglutide precursor peptide (LPP) and developing a potentially new incretin mimic. Here, human αB-crystallin (αB-Cry) was ligated to the LPP at the gene level, and the gene construct was expressed in Escherichia coli with a relatively good efficiency. The hybrid protein (αB-lir) was then purified by a precipitation method followed by anion exchange chromatography. After that, the peptide was released from the carrier protein by a chemical cleavage method yielding about 70%. The LPP was then purified by gel filtration chromatography, and HPLC estimated its purity to be about 98%. Also, the molecular mass of the purified peptide was finally confirmed by mass spectroscopy analysis. Assessment of the secondary structures suggested a dominant α-helical structure for the LPP and a β-sheet rich structure for the hybrid protein. The subcutaneous injection of the LPP and the αB-lir hybrid protein significantly reduced the blood sugar levels in healthy and diabetic mice and stimulated insulin secretion. Also, the hybrid protein exerts its bioactivities more effectively than the LPP over a relatively longer period of time. The results of this study suggested a novel method for the easy and cost-effective production of the LPP and introduced a new long-acting incretin mimic that can be potentially used for the treatment of T2DM patients.

Effects of Glucagon-like peptide 1 (GLP-1) analogs in the hippocampus

The glucagon-like peptide-1 (GLP-1) is a pleiotropic hormone very well known for its incretin effect in the glucose-dependent stimulation of insulin secretion. However, GLP-1 is also produced in the brain, and it displays critical roles in neuroprotection by activating the GLP-1 receptor signaling pathways. GLP-1 enhances learning and memory in the hippocampus, promotes neurogenesis, decreases inflammation and apoptosis, modulates reward behavior, and reduces food intake. Its pharmacokinetics have been improved to enhance the peptide's half-life, enhancing exposure and time of action. The GLP-1 agonists are successfully in clinical use for the treatment of type-2 diabetes, obesity, and clinical evaluation for the treatment of neurodegenerative diseases.

Dysregulation of β-Cell Proliferation in Diabetes: Possibilities of Combination Therapy in the Development of a Comprehensive Treatment

Diabetes mellitus (DM) is a metabolic disorder characterized by chronic hyperglycemia as a result of insufficient insulin levels and/or impaired function as a result of autoimmune destruction or insulin resistance. While Type 1 DM (T1DM) and Type 2 DM (T2DM) occur through different pathological processes, both result in β-cell destruction and/or dysfunction, which ultimately lead to insufficient β-cell mass to maintain normoglycemia. Therefore, therapeutic agents capable of inducing β-cell proliferation is crucial in treating and reversing diabetes; unfortunately, adult human β-cell proliferation has been shown to be very limited (~0.2% of β-cells/24 h) and poorly responsive to many mitogens. Furthermore, diabetogenic insults result in damage to β cells, making it ever more difficult to induce proliferation. In this review, we discuss β-cell mass/proliferation pathways dysregulated in diabetes and current therapeutic agents studied to induce β-cell proliferation. Furthermore, we discuss possible combination therapies of proliferation agents with immunosuppressants and antioxidative therapy to improve overall long-term outcomes of diabetes.

Spinal cord-wide structural disruption in type 2 diabetes rescued by exenatide "a glucagon-like peptide-1 analogue" via down-regulating inflammatory, oxidative stress and apoptotic signaling pathways

The mechanisms of spinal cord-wide structural and functional disruption in diabetic patients remain elusive. This study evaluated histopathological alterations of the spinal cord cytoarchitecture in T2DM model of rats and assessed the potential ameliorating effect of exenatide "a potent GLP-1 analogue". Thirty male rats were allocated into three groups; I (control), II (Diabetic): T2DM was induced by high fat diet for 8 weeks followed by a single I.P injection of STZ (25 mg/kg BW) and III (Diabetic/Exenatide): T2DM rats injected with exenatide (10 μg/Kg, S.C. twice daily for 2 weeks). Neurobehavioral sensory and motor tests were carried out and glycemic control biomarkers and indices of insulin resistance and sensitivity were measured. In addition, the spinal cord was processed for histological and immunohistochemical studies besides assessing its tissue homogenate levels of pro-inflammatory/anti-inflamatory cytokines and oxidant/antioxidant biomarkers. Moreover, RT-qPCR was performed to measure the expression of proapoptotic/antiapoptotic and neurotrophic genes. The diabetic rats exhibited thermal hyperalgesia, mechanical allodynia and decreased locomotor activity along with increased serum glucose, insulin, HbA1c, HOMA-IR while, quantitative insulin sensitivity check index (QUICKI) was decreased. Also, IL-1β NF-kB, MDA increased while IL-10, SOD activity and β-endorphin decreased in the spinal tissue. Up regulation of caspase-3 and down regulation of Bcl-2, nerve growth factor (NGF) and glial cell-derived neurotrophic (GDNF) in diabetic rats. Also, they exhibited histopathological changes and increased CD68 positive microglia and Bax immunoreactivity in the spinal cord. Subsequent to exenatide treatment, most biomolecular, structural and functional impairments of the spinal cord were restored in the diabetic rats. In conclusion, the neuro-modulating effect of exenatide against diabetic-induced spinal cord affection warrants the concern about its therapeutic relevance in confronting the devastating diabetic neuropathic complications.

The potential role of lactulose pharmacotherapy in the treatment and prevention of diabetes

The non-absorbable disaccharide lactulose is mostly used in the treatment of various gastrointestinal disorders such as chronic constipation and hepatic encephalopathy. The mechanism of action of lactulose remains unclear, but it elicits more than osmotic laxative effects. As a prebiotic, lactulose may act as a bifidogenic factor with positive effects in preventing and controlling diabetes. In this review, we summarized the current evidence for the effect of lactulose on gut metabolism and type 2 diabetes (T2D) prevention. Similar to acarbose, lactulose can also increase the abundance of the short-chain fatty acid (SCFA)-producing bacteria Lactobacillus and Bifidobacterium as well as suppress the potentially pathogenic bacteria Escherichia coli. These bacterial activities have anti-inflammatory effects, nourishing the gut epithelial cells and providing a protective barrier from microorganism infection. Activation of peptide tyrosine tyrosine (PYY) and glucagon-like peptide 1 (GLP1) can influence secondary bile acids and reduce lipopolysaccharide (LPS) endotoxins. A low dose of lactulose with food delayed gastric emptying and increased the whole gut transit times, attenuating the hyperglycemic response without adverse gastrointestinal events. These findings suggest that lactulose may have a role as a pharmacotherapeutic agent in the management and prevention of type 2 diabetes via actions on the gut microbiota.

Association between different GLP-1 receptor agonists and gastrointestinal adverse reactions: A real-world disproportionality study based on FDA adverse event reporting system database

OBJECTIVE

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have significantly improved clinical effects on glycemic control. However, real-world data concerning the difference in gastrointestinal adverse events (AEs) among different GLP-1 RAs are still lacking. Our study aimed to characterize and compare gastrointestinal AEs among different marketed GLP-1 RAs (exenatide, liraglutide, dulaglutide, lixisenatide, and semaglutide) based on real-world data.

METHODS

Disproportionality analysis was used to evaluate the association between GLP-1 RAs and gastrointestinal adverse events. Data were extracted from the US FDA Adverse Event Reporting System (FAERS) database between January 2018 and September 2022. Clinical characteristics, the time-to-onset, and the severe proportion of GLP-1 RAs-associated gastrointestinal AEs were further analyzed.

RESULTS

A total of 21,281 reports of gastrointestinal toxicity were analyzed out of 81,752 adverse event reports, and the median age of the included patients was 62 (interquartile range [IQR] 54-70) years old. Overall GLP-1 RAs were associated with increased risk of gastrointestinal system disorders (ROR, 1.46; 95% CI, 1.44-1.49), which were further attributed to liraglutide (ROR, 2.39; 95% CI, 2.28-2.51), dulaglutide (ROR, 1.39; 95% CI, 1.36-1.42), and semaglutide (ROR, 3.00; 95% CI, 2.89-3.11). Adverse events uncovered in the labels included gastroesophageal reflux disease, gastritis, bezoar, breath odor, intra-abdominal hematoma, etc. Furthermore, it was observed that semaglutide had the greatest risk of nausea (ROR, 7.41; 95% CI, 7.10-7.74), diarrhea (ROR, 3.55; 95% CI, 3.35-3.77), vomiting (ROR, 6.67; 95% CI, 6.32-7.05), and constipation (ROR, 6.17; 95% CI, 5.72-6.66); liraglutide had the greatest risk of abdominal pain upper (ROR, 4.63; 95% CI, 4.12-5.21) and pancreatitis (ROR, 32.67; 95% CI, 29.44-36.25). Most gastrointestinal AEs tended to occur within one month. Liraglutide had the highest severe rate of gastrointestinal AEs (23.31%), while dulaglutide had the lowest, with a severe rate of 12.29%.

CONCLUSION

GLP-1 RA were significantly associated with gastrointestinal AEs, and the association was further attributed to liraglutide, dulaglutide, and semaglutide. In addition, semaglutide had the greatest risk of nausea, diarrhea, vomiting, constipation, and pancreatitis, while liraglutide had the greatest risk of upper abdominal pain. Our study provided valuable evidence for selecting appropriate GLP-1 RAs to avoid the occurrence of GLP-1 RA-induced gastrointestinal AEs.

The Effects of the New Therapeutic Treatments for Diabetes Mellitus on the Male Reproductive Axis

One of the complications of chronic hyperglycemia and insulin resistance due to type 2 diabetes mellitus (T2DM) on the hypothalamic-pituitary-gonadal axis in men, is the high prevalence of hypogonadotropic hypogonadism, which has been recently defined as functional hypogonadism, characterized by low testosterone associated with inappropriately normal gonadotropin levels. Although the pathophysiology of this hormonal imbalance may be related to several factors, including glycemic control, concomitant sleep apnea, insulin resistance, the main role is determined by the degree of central or visceral obesity and the consequent inflammatory state. Several drugs have been developed to treat T2DM such as glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase 4 inhibitors, and sodium-glucose co-transporter 2 inhibitors. All appear to be effective in ameliorating blood glucose control, by lowering inflammation and body weight, and most seem to reduce the risk of micro- and macrovascular damage as a consequence of uncontrolled diabetes. A few studies have evaluated the impact of these drugs on gonadal function in T2DM patients with hypogonadism, with promising results. This review summarizes the main current knowledge of the effects of these new antidiabetic drugs on the hypothalamus-pituitary-gonadal axis, showing their potential future application in addition to glucose control in dysmetabolic male patients.

Case Report: Off-Label Liraglutide Use in Children With Wolfram Syndrome Type 1: Extensive Characterization of Four Patients

Aims: Wolfram syndrome type 1 is a rare recessive monogenic form of insulin-dependent diabetes mellitus with progressive neurodegeneration, poor prognosis, and no cure. Based on preclinical evidence we hypothesized that liraglutide, a glucagon-like peptide-1 receptor agonist, may be repurposed for the off-label treatment of Wolfram Syndrome type 1. We initiated an off-label treatment to investigate the safety, tolerability, and efficacy of liraglutide in pediatric patients with Wolfram Syndrome type 1. Methods: Pediatric patients with genetically confirmed Wolfram Syndrome type 1 were offered off-label treatment approved by The Regional Network Coordination Center for Rare Diseases, Pharmacological Research IRCCS Mario Negri, and the internal ethics committee. Four patients were enrolled; none refused nor were excluded or lost during follow-up. Liraglutide was administered as a daily subcutaneous injection. Starting dose was 0.3 mg/day. The dose was progressively increased as tolerated, up to the maximum dose of 1.8 mg/day. The primary outcome was evaluating the safety, tolerability, and efficacy of liraglutide in Wolfram Syndrome type 1 patients. Secondary endpoints were stabilization or improvement of C-peptide secretion as assessed by the mixed meal tolerance test. Exploratory endpoints were stabilization of neurological and neuro-ophthalmological degeneration, assessed by optical coherence tomography, electroretinogram, visual evoked potentials, and magnetic resonance imaging. Results: Four patients aged between 10 and 14 years at baseline were treated with liraglutide for 8-27 months. Liraglutide was well-tolerated: all patients reached and maintained the maximum dose, and none withdrew from the study. Only minor transient gastrointestinal symptoms were reported. No alterations in pancreatic enzymes, calcitonin, or thyroid hormones were observed. At the latest follow-up, the C-peptide area under the curve ranged from 81 to 171% of baseline. Time in range improved in two patients. Neuro-ophthalmological and neurophysiological disease parameters remained stable at the latest follow-up. Conclusions: We report preliminary data on the safety, tolerability, and efficacy of liraglutide in four pediatric patients with Wolfram Syndrome type 1. The apparent benefits both in terms of residual C-peptide secretion and neuro-ophthalmological disease progression warrant further studies on the repurposing of glucagon-like peptide-1 receptor agonists as disease-modifying agents for Wolfram Syndrome type 1.

Targeted oral peptide delivery using multi-unit particulates: Drug and permeation enhancer layering approach

Oral delivery of peptides is a challenge due to their instability and their limited transport and absorption characteristics within the gastrointestinal tract. In this work, we used layering techniques in a fluidized bed dryer to create a configuration in which the active peptide, permeation enhancers, and polymers are coated to control the release of the peptide. Formulations were developed to disintegrate at pH values of 5.5 and 7.0. In addition, sustained-release or mucoadhesive polymers were coated to trigger release at a desired site in the gastrointestinal tract. Dissolution studies with a USP Type I (basket) apparatus confirmed the duration of release. Pharmacokinetic studies were performed in beagle dogs to evaluate bioavailability. A high-disintegration pH was found to be advantageous in enhancing bioavailability.

Oral semaglutide in the management of type 2 DM: Clinical status and comparative analysis

BACKGROUND

In the incretin system, Glucagon-like peptide-1 (GLP-1) is a hormone that inhibits the release of glucagon and regulates glucose-dependent insulin secretion. In type 2 diabetes, correcting the impaired incretin system using GLP-1 agonist is a well-defined therapeutic strategy.

OBJECTIVES

This review article aims to discuss the mechanism of action, key regulatory events, clinical trials for glycaemic control and comparative analysis of semaglutide with the second-line antidiabetic drugs.

DESCRIPTION

Semaglutide is a glucagon-like peptide 1 (GLP 1) receptor agonist with enhanced glycaemic control in diabetes patients. In 2019, USFDA approved the first oral GLP-1 receptor agonist, semaglutide to be administered as a once-daily tablet. Further, recent studies highlight the ability of semaglutide to improve the glycaemic control in obese patients with a reduction in body weight. Still, in clinical practice, in type 2 DM treatment paradigm the impact of oral semaglutide remains unidentified. This review article discusses the mechanism of action, pharmacodynamics, key regulatory events, and clinical trials regarding glycaemic control.

CONCLUSION

The review highlights the comparative analysis of semaglutide with the existing second-line drugs for the management of type 2 diabetes mellitus by stressing on its benefits and adverse events.

The therapeutic potential of GLP-1 analogues for stress-related eating and role of GLP-1 in stress, emotion and mood: a review

Stress and low mood are powerful triggers for compulsive overeating, a maladaptive form of eating leading to negative physical and mental health consequences. Stress-vulnerable individuals, such as people with obesity, are particularly prone to overconsumption of high energy foods and may use it as a coping mechanism for general life stressors. Recent advances in the treatment of obesity and related co-morbidities have focused on the therapeutic potential of anorexigenic gut hormones, such as glucagon-like peptide 1 (GLP-1), which acts both peripherally and centrally to reduce energy intake. Besides its appetite suppressing effect, GLP-1 acts on areas of the brain involved in stress response and emotion regulation. However, the role of GLP-1 in emotion and stress regulation, and whether it is a viable treatment for stress-induced compulsive overeating, has yet to be established. A thorough review of the pre-clinical literature measuring markers of stress, anxiety and mood after GLP-1 exposure points to potential divergent effects based on temporality. Specifically, acute GLP-1 injection consistently stimulates the physiological stress response in rodents whereas long-term exposure indicates anxiolytic and anti-depressive benefits. However, the limited clinical evidence is not as clear cut. While prolonged GLP-1 analogue treatment in people with type 2 diabetes improved measures of mood and general psychological wellbeing, the mechanisms underlying this may be confounded by associated weight loss and improved blood glucose control. There is a paucity of longitudinal clinical literature on mechanistic pathways by which stress influences eating behavior and how centrally-acting gut hormones such as GLP-1, can modify these. (250).

Dipeptidyl Peptidase (DPP)-IV Inhibitors with Antioxidant Potential Isolated from Natural Sources: A Novel Approach for the Management of Diabetes

Type 2 diabetes mellitus (T2DM) is characterized by hyperglycemia that is predominantly caused by insulin resistance or impaired insulin secretion, along with disturbances in carbohydrate, fat and protein metabolism. Various therapeutic approaches have been used to treat diabetes, including improvement of insulin sensitivity, inhibition of gluconeogenesis, and decreasing glucose absorption from the intestines. Recently, a novel approach has emerged using dipeptidyl peptidase-IV (DPP-IV) inhibitors as a possible agent for the treatment of T2DM without producing any side effects, such as hypoglycemia and exhaustion of pancreatic β-cells. DPP-IV inhibitors improve hyperglycemic conditions by stabilizing the postprandial level of gut hormones such as glucagon-like peptide-1, and glucose-dependent insulinotropic polypeptides, which function as incretins to help upregulate insulin secretion and β-cell mass. In this review, we summarized DPP-IV inhibitors and their mechanism of inhibition, activities of those isolated from various natural sources, and their capacity to overcome oxidative stress in disease conditions.

Novel Approaches to Restore Pancreatic Beta-Cell Mass and Function

Beta-cell dysfunction and beta-cell death are critical events in the development of type 2 diabetes mellitus (T2DM). Therefore, the goals of modern T2DM management have shifted from merely restoring normoglycemia to maintaining or regenerating beta-cell mass and function. In this review we summarize current and novel approaches to achieve these goals, ranging from lifestyle interventions to N-methyl-D-aspartate receptor (NMDAR) antagonism, and discuss the mechanisms underlying their effects on beta-cell physiology and glycemic control. Notably, timely intervention seems critical, but not always strictly required, to maximize the effect of any approach on beta-cell recovery and disease progression. Conventional antidiabetic medications are not disease-modifying in the sense that the disease does not progress or reoccur while on treatment or thereafter. More invasive approaches, such as bariatric surgery, are highly effective in restoring normoglycemia, but are reserved for a rather small proportion of obese individuals and sometimes associated with serious adverse events. Finally, we recapitulate the broad range of effects mediated by peripheral NMDARs and discuss recent evidence on the potential of NMDAR antagonists to be developed as a novel class of antidiabetic drugs. In the future, a more refined assessment of disease risk or disease subtype might enable more targeted therapies to prevent or treat diabetes.

Deciphering the Neuroprotective Role of Glucagon-like Peptide-1 Agonists in Diabetic Neuropathy: Current Perspective and Future Directions

Diabetic neuropathy is referred to as a subsequential and debilitating complication belonging to type 1 and type 2 diabetes mellitus. It is a heterogeneous group of disorders with a particularly complex pathophysiology and also includes multiple forms, ranging from normal discomfort to death. The evaluation of diabetic neuropathy is associated with hyperglycemic responses, resulting in an alteration in various metabolic pathways, including protein kinase C pathway, polyol pathway and hexosamine pathway in Schwann and glial cells of neurons. The essential source of neuronal destruction is analogous to these respective metabolic pathways, thus identified as potential therapeutic targets. These pathways regulating therapeutic medications may be used for diabetic neuropathy, however, only target specific drugs could have partial therapeutic activity. Various antidiabetic medications have been approved and marketed, which possess the therapeutic ability to control hyperglycemia and ameliorate the prevalence of diabetic neuropathy. Among all antidiabetic medications, incretin therapy, including Glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors, are the most favorable medications for the management of diabetes mellitus and associated peripheral neuropathic complications. Besides enhancing glucose-evoked insulin release from pancreatic β-cells, these therapeutic agents also play a vital role to facilitate neurite outgrowth and nerve conduction velocity in dorsal root ganglion. Furthermore, incretin therapy also activates cAMP and ERK signalling pathways, resulting in nerve regeneration and repairing. These effects are evidently supported by a series of preclinical data and investigations associated with these medications. However, the literature lacks adequate clinical trial outcomes related to these novel antidiabetic medications. The manuscript emphasizes the pathogenesis, current pharmacological approaches and vivid description of preclinical and clinical data for the effective management of diabetic neuropathy.

DBPR108, a novel dipeptidyl peptidase-4 inhibitor with antihyperglycemic activity

AIMS

Dipeptidyl peptidase 4 (DPP-4) is a valid molecular drug target from which its inhibitors have been developed as medicines for treating diabetes. The present study evaluated a new synthetic DPP-4-specific inhibitor of small molecule DBPR108 for pharmacology and pharmacokinetic profiles.

MAIN METHODS

DBPR108 of various doses was orally administered to rats, diabetic mice, and dogs and the systemic circulating DPP-4 activities in the animals were measured to demonstrate the pharmacological mechanisms of action via DPP-4 inhibition. Upon an oral administration of DBPR108, the serum active GLP-1 and insulin levels of the rats challenged with an oral glucose ingestion were measured. Oral glucose tolerance test in diet-induced obese mice was performed to examine if DBPR108 increases the glucose tolerability in animals.

KEY FINDINGS

Orally administered DBPR108 inhibited the systemic plasma DPP-4 activities in rats, dogs and diabetic mice in a dose-dependent manner. DBPR108 caused elevated serum levels of active GLP-1 and insulin in the rats. DBPR108 dose-dependently increased the glucose tolerability in diet-induced obese (DIO) mice and, furthermore, DIO mice treated with DBPR108 (0.1 mg/kg) in combination with metformin (50 or 100 mg/kg) showed a prominently strong increase in the glucose tolerability.

SIGNIFICANCE

DBPR108 is a novel DPP-4-selective inhibitor of small molecule that demonstrated potent in vivo pharmacological effects and good safety profiles in animals. DBPR108 is now a drug candidate being further developed in the clinical studies as therapeutics for treating diabetes.

Akkermansia muciniphila secretes a glucagon-like peptide-1-inducing protein that improves glucose homeostasis and ameliorates metabolic disease in mice

The gut microbiota, which includes Akkermansia muciniphila, is known to modulate energy metabolism, glucose tolerance, immune system maturation and function in humans^1-4. Although A. muciniphila is correlated with metabolic diseases and its beneficial causal effects were reported on host metabolism^5-8, the molecular mechanisms involved have not been identified. Here, we report that A. muciniphila increases thermogenesis and glucagon-like peptide-1 (GLP-1) secretion in high-fat-diet (HFD)-induced C57BL/6J mice by induction of uncoupling protein 1 in brown adipose tissue and systemic GLP-1 secretion. We apply fast protein liquid chromatography and liquid chromatography coupled to mass spectrophotometry analysis to identify an 84 kDa protein, named P9, that is secreted by A. muciniphila. Using L cells and mice fed on an HFD, we show that purified P9 alone is sufficient to induce GLP-1 secretion and brown adipose tissue thermogenesis. Using ligand-receptor capture analysis, we find that P9 interacts with intercellular adhesion molecule 2 (ICAM-2). Interleukin-6 deficiency abrogates the effects of P9 in glucose homeostasis and downregulates ICAM-2 expression. Our results show that the interactions between P9 and ICAM-2 could be targeted by therapeutics for metabolic diseases.

Polymeric microparticle systems for modified release of glucagon-like-peptide-1 receptor agonists

Type 2 diabetes is a fast-growing worldwide epidemic. Despite the multiple therapies available to treat type 2 diabetes, the disease is not correctly managed in over half of patients, mainly due to non-compliance with prescribed treatment regimes. The development of analogues to the glucagon-like peptide 1 (GLP-1) has resulted in the extension of its half-life and associated benefits. Further benefits in the use of peptide-based GLP-1 receptor agonists have been achieved by the use of controlled-release systems based on polymeric microparticles. In this review, we focus on commercially available formulations and others that remain in development, discussing the preparation methods and the relationship between in vitro and in vivo kinetic release behaviours.

Discovery through Machine Learning and Preclinical Validation of Novel Anti-Diabetic Peptides

While there have been significant advances in drug discovery for diabetes mellitus over the past couple of decades, there is an opportunity and need for improved therapies. While type 2 diabetic patients better manage their illness, many of the therapeutics in this area are peptide hormones with lengthy sequences and a molecular structure that makes them challenging and expensive to produce. Using machine learning, we present novel anti-diabetic peptides which are less than 16 amino acids in length, distinct from human signalling peptides. We validate the capacity of these peptides to stimulate glucose uptake and Glucose transporter type 4 (GLUT4) translocation in vitro. In obese insulin-resistant mice, predicted peptides significantly lower plasma glucose, reduce glycated haemoglobin and even improve hepatic steatosis when compared to treatments currently in use in a clinical setting. These unoptimised, linear peptides represent promising candidates for blood glucose regulation which require further evaluation. Further, this indicates that perhaps we have overlooked the class of natural short linear peptides, which usually come with an excellent safety profile, as therapeutic modalities.

Liraglutide Protects Nucleus Pulposus Cells Against High-Glucose Induced Apoptosis by Activating PI3K/Akt/ mTOR/Caspase-3 and PI3K/Akt/GSK3β/Caspase-3 Signaling Pathways

Background and Objective: Diabetes mellitus (DM) is reportedly a significant risk factor for intervertebral disc degeneration (IDD). Incretin system and particularly glucagon-like peptide 1 (GLP-1) because of its glucose-lowering effects has become an important target in therapeutic strategies of type 2 diabetes (T2D). Liraglutide is a GLP-1 receptor (GLP-1R) agonist with glucoregulatory and insulinotropic functions as well as regulatory functions on cell proliferation, differentiation, and apoptosis. However, little is known on the roles and signaling pathways of apoptosis protecting effects of liraglutide in IDD. This study aimed to investigate the potential protective effects of liraglutide against high glucose-induced apoptosis of nucleus pulposus cells (NPCs) and the possible involved signaling pathways.

Methods: The human NPCs were incubated with 100 nM liraglutide alone or in combination with LY294002 (PI3K inhibitor), rapamycin (mTOR inhibitor), and SB216763 (GSK3β inhibitor) in a high glucose culture for 48 h. The four groups were assessed further for apoptosis and genes expressions. The apoptotic effect was evaluated by flow cytometry and further confirmed by cell death detection enzyme-linked immunoassay plus (ELISAPLUS). The gene and protein expression levels were assessed by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting techniques. The results were comparatively assessed between the four groups.

Results: The results confirmed the presence of GLP-1R in the NPCs indicating that liraglutide inhibited the high glucose-induced apoptosis, which was blocked by silencing GLP-1R with siRNA. Moreover, liraglutide stimulated the phosphorylation of Akt, mTOR and GSK3β. Treatment with LY294002 significantly increased the apoptosis of NPCs and reduced the levels of their downstream substrates (p-AKT, p-mTOR, and p-GSK3β). Further assessments revealed that activation of mTOR and GSK3β was almost completely inhibited by rapamycin and SB216763, respectively, which significantly increased the caspase-3 levels.

Conclusion: Liraglutide could protect NPCs against high glucose-induced apoptosis by activating the PI3K/AKT/mTOR/caspase-3 and PI3K/AKT/GSK3β/caspase-3 signaling pathways.