Anti-inflammatory role of glucagon-like peptide 1 receptor agonists and its clinical implications

Glucagon-like peptide 1 receptor agonists (GLP-1RAs) have emerged as promising therapeutic agents with potent anti-inflammatory properties and diverse clinical implications. This in-depth review article explores the mechanisms behind the anti-inflammatory actions of GLP-1RAs and assesses their prospective applicability in a wide range of disease scenarios. The current review establishes the significance of comprehending the anti-inflammatory role of GLP-1RAs and identifies pertinent research gaps. A concise overview of inflammation and its clinical consequences underscores the critical need for effective anti-inflammatory interventions. Subsequently, the article elucidates the intricate mechanisms through which GLP-1RAs modulate immune cell signaling and regulate the nuclear factor-kappa B (NF-κB) pathway. Detailed discussions encompass their impact on inflammatory responses, cytokine production, and attenuation of oxidative stress. The exposition is substantiated by a collection of pertinent examples and an extensive array of references from both preclinical and clinical investigations. The historical trajectory of GLP-1RA drugs, including exenatide, lixisenatide, liraglutide, and semaglutide, is traced to delineate their development as therapeutic agents. Moreover, the review emphasizes the therapeutic potential of GLP-1RAs in specific disease contexts like type 2 diabetes, a neurodegenerative disorder, and inflammatory bowel disease (IBD), shedding light on their anti-inflammatory effects through rigorous examination of preclinical and clinical studies. The article also provides an outlook on future perspectives for GLP-1RAs, encompassing the domains of diabetes, neurodegenerative diseases, and IBD. In conclusion, GLP-1RAs exhibit substantial anti-inflammatory effects, rendering them promising therapeutic agents with broad clinical implications. They are very useful in a wide variety of diseases because they regulate immunological responses, block NF-κB activation, and decrease production of pro-inflammatory cytokines. Ongoing research endeavors aim to optimize their therapeutic use, delineate patient-specific treatment paradigms, and explore novel therapeutic applications. GLP-1RAs represent a significant breakthrough in anti-inflammatory therapy, offering novel treatment options, and improved patient outcomes.

Glucagon-like peptide-1 receptor agonists and safety in the preconception period

PURPOSE OF REVIEW

Glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) are becoming increasingly popular for the treatment of type II diabetes and obesity. Body mass index (BMI) thresholds at in vitro fertilization (IVF) clinics may further drive the use of these medications before infertility treatment. However, most clinical guidance regarding optimal time to discontinue these medications prior to conception is based on animal data. The purpose of this review was to evaluate the literature for evidence-based guidance regarding the preconception use of GLP-1 RA.

RECENT FINDINGS

16 articles were found in our PubMed search, 10 were excluded as they were reviews or reported on animal data. Included were 3 case reports detailing pregnancy outcomes in individual patients that conceived while on a GLP-1 RA and 2 randomized controlled trials (RCTs) and a follow-up study to one of the RCTs that reported on patients randomized to GLP-1 RA or metformin prior to conception. No adverse pregnancy or neonatal outcomes were reported.

SUMMARY

There are limited data from human studies to guide decision-making regarding timing of discontinuation of GLP-1 RA before conception. Studies focused on pregnancy and neonatal outcomes would provide additional information regarding a safe washout period. Based on the available literature a 4-week washout period prior to attempting conception may be considered for the agents reviewed in this publication.

An Acute Bout of Exercise Suppresses Appetite via Central Lactate Metabolism

Exercise has been reported to elicit a transient suppression of appetite. Plasma lactate, which is produced by exercising muscle, is believed to have a critical effect on exercise-induced appetite suppression. However, the underlying mechanisms and signaling steps of central lactate metabolism remain unexplored. After central oxamate administration, C57BL/6J male mice performed 10 high-intensity interval running at 90% V_max for 4 minutes each, which separated by 2 minutes at 12 m/min. Food intake and the expression of hypothalamic appetite-regulating neuropeptides including proopiomelanocortin (POMC) and neuropeptide Y (NPY) were investigated following exercise training. Janus kinase 2 (Jak2)-signal transducer and activator of transcription 3 (STAT3) signaling pathway was also determined by Western blot. In addition, hypoxia-inducible factor-1α (HIF-1α) was investigated to explore the effect of central lactate metabolism following exercise. We found that central oxamate administration reversed exercise-induced suppression of food intake, and as well as changes in the expression of POMC and NPY. Moreover, acute exercise led to an increase in the phosphorylation of Jak2 and STAT3 in the hypothalamus, while central lactate inhibition significantly blunted this effect. In addition, HIF-1α expression increased obviously after exercise, while it was attenuated by central oxamate administration. Collectively, our data reveal that central lactate metabolism mediates exercise-induced suppression of appetite and changes in neuropeptides, possibly through enhanced Jak2-STAT3 signaling.

Glucagon-Like Peptide 1 Receptor Agonists: A Medication for Obesity Management

PURPOSE OF REVIEW

The burden of obesity worldwide is high and projected to rise. Obesity increases the risk of several cardiovascular diseases and cardiometabolic risk factors; hence, utilizing effective long-term therapies for obesity is of utmost importance. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have emerged as effective therapies that achieve substantial weight loss and improve cardiometabolic risk. The purpose of this review is to discuss the role of GLP-1RAs in obesity management.

RECENT FINDINGS

Two subcutaneous GLP-1RAs, liraglutide and semaglutide, have been evaluated in several clinical trials for weight loss. Liraglutide achieves a mean weight loss of 4-7 kg, and more than 50% of treated individuals achieve 5% or more weight loss. Semaglutide has a greater impact on weight loss, with a mean weight loss of 9-16 kg, and more than 50% of treated individuals achieve 10-15% or more weight loss. These results led to regulatory approval of these agents for weight loss in individuals with obesity, regardless of diabetes status. In addition to weight loss, the benefits of GLP-1RAs extend to other risk factors, such as glycemic control and blood pressure. Gastrointestinal symptoms are the most frequently encountered adverse events with incidences between 5 and 30%. Finally, the cost remains one of the most critical challenges that limit GLP-1RAs use. GLP-1RAs have robust weight loss benefits and are expected to have a critical role in the management of obesity in the coming years. Upcoming studies will evaluate the durability of weight loss achieved with GLP-1RAs and the impact on cardiovascular outcomes.

GLP-1 Receptor Agonists: Beyond Their Pancreatic Effects

Glucagon like peptide-1 (GLP-1) is an incretin secretory molecule. GLP-1 receptor agonists (GLP-1RAs) are widely used in the treatment of type 2 diabetes (T2DM) due to their attributes such as body weight loss, protection of islet β cells, promotion of islet β cell proliferation and minimal side effects. Studies have found that GLP-1R is widely distributed on pancreatic and other tissues and has multiple biological effects, such as reducing neuroinflammation, promoting nerve growth, improving heart function, suppressing appetite, delaying gastric emptying, regulating blood lipid metabolism and reducing fat deposition. Moreover, GLP-1RAs have neuroprotective, anti-infectious, cardiovascular protective, and metabolic regulatory effects, exhibiting good application prospects. Growing attention has been paid to the relationship between GLP-1RAs and tumorigenesis, development and prognosis in patient with T2DM. Here, we reviewed the therapeutic effects and possible mechanisms of action of GLP-1RAs in the nervous, cardiovascular, and endocrine systems and their correlation with metabolism, tumours and other diseases.

Obesity, Polycystic Ovary Syndrome, and Infertility: A New Avenue for GLP-1 Receptor Agonists

CONTEXT

Obesity is responsible for an increased risk of sub-fecundity and infertility. Obese women show poorer reproductive outcomes regardless of the mode of conception, and higher body mass index (BMI) is associated with poorer fertility prognosis. Polycystic ovary syndrome (PCOS) is one of the leading causes of infertility, and many women with PCOS are also overweight or obese.

EVIDENCE ACQUISITION

The aim of the present narrative review is to describe the mechanisms responsible for the development of infertility and PCOS in women with obesity/overweight, with a focus on the emerging role of glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1 RAs) as a therapeutic option for obese women with PCOS.

EVIDENCE SYNTHESIS

Weight reduction represents the most significant factor affecting fertility and pregnancy outcomes. Current experimental and clinical evidence suggests the presence of an underlying pathophysiological link between obesity, GLP-1 kinetic alterations, and PCOS pathogenesis. Based on the positive results in patients affected by obesity, with or without diabetes, the administration of GLP-1 RA (mainly liraglutide) alone or in combination with metformin has been investigated in women with obesity and PCOS. Several studies demonstrated significant weight loss and testosterone reduction, with mixed results relative to improvements in insulin resistance parameters and menstrual patterns.

CONCLUSIONS

The weight loss effects of GLP-1 RA offer a unique opportunity to expand the treatment options available to PCOS patients.

Importance of Postprandial Glucose in Relation to A1C and Cardiovascular Disease

IN BRIEF This article reviews the evidence regarding the impact of postprandial glucose (PPG) on overall A1C and its relation to cardiovascular disease (CVD). To date, four randomized, controlled trials have evaluated the impact of PPG reduction on CVD; however, only one of these successfully demonstrated a positive effect. Despite this, epidemiological evidence does indicate a cardiovascular benefit of PPG reduction, and agents that can be used to manage PPG in people with type 2 diabetes are also discussed.

Dietary Slowly Digestible Starch Triggers the Gut-Brain Axis in Obese Rats with Accompanied Reduced Food Intake

SCOPE

Slowly digestible starch (SDS), as a functional carbohydrate providing a slow and sustained glucose release, may be able to modulate food intake through activation of the gut-brain axis.

METHODS AND RESULTS

Diet-induced obese rats were used to test the effect on feeding behavior of high-fat (HF) diets containing an SDS, fabricated to digest into the ileum, as compared to rapidly digestible starch (RDS). Ingestion of the HF-SDS diet over an 11-week period reduced daily food intake, through smaller meal size, to the same level as a lean body control group, while the group consuming the HF-RDS diet remained at a high food intake. Expression levels (mRNA) of the hypothalamic orexigenic neuropeptide Y (NPY) and Agouti-related peptide (AgRP) were significantly reduced, and the anorexigenic corticotropin-releasing hormone (CRH) was increased, in the HF-SDS fed group compared to the HF-RDS group, and to the level of the lean control group.

CONCLUSION

SDS with digestion into the ileum reduced daily food intake and paralleled suppressed expression of appetite-stimulating neuropeptide genes associated with the gut-brain axis. This novel finding suggests further exploration involving a clinical study and potential development of SDS-based functional foods as an approach to obesity control.

The nutritional property of endosperm starch and its contribution to the health benefits of whole grain foods

Purported health benefits of whole grain foods in lowering risk of obesity, type 2 diabetes, cardiovascular disease, and cancer are supported by epidemiological studies and scientific researches. Bioactive components including dietary fibers, phytochemicals, and various micronutrients present in the bran and germ are commonly considered as the basis for such benefits. Endosperm starch, as the major constituent of whole grains providing glucose to the body, has been less investigated regarding its nutritional property and contribution to the value of whole grain foods. Nutritional quality of starch is associated with its rate of digestion and glucose absorption. In whole grain foods, starch digestion and glucose delivery may vary depending on the form in which the food is delivered, some with starch being rapidly and others slowly digested. Furthermore, there are other inherent factors in whole grain products, such as phenolic compounds and dietary fibers, that may moderate glycemic profiles. A good understanding of the nutritional properties of whole grain starch is important to the development of food processing technologies to maximize their health benefits.

Chili pepper as a body weight-loss food

Chili has culinary as well as medical importance. Studies in humans, using a wide range of doses of chili intake (varying from a single meal to a continuous uptake for up to 12 weeks), concluded that it facilitates weight loss. In regard to this, the main targets of chili are fat metabolism, energy expenditure, and thermogenesis. To induce weight loss, the active substance of chili, capsaicin, activates Transient Receptor Potential Cation Channel sub-family V member 1 (TRPV1) channels) receptors causing an increase in intracellular calcium levels and triggering the sympathetic nervous system. Apart from TRPV1, chili directly reduces energy expenditure by activating Brown Adipose Tissue. Weight loss by chili is also the result of an improved control of insulin, which supports weight management and has positive effects for treatment for diseases like obesity, diabetes and cardiovascular disorders. This review summarizes the major pathways by which chili contributes to ameliorating parameters that help weight management and how the consumption of chili can help in accelerating weight loss through dietary modifications.

Gut feedback mechanisms and food intake: a physiological approach to slow carbohydrate bioavailability

Glycemic carbohydrates in foods are an important macronutrient providing the biological fuel of glucose for a variety of physiological processes. A classification of glycemic carbohydrates into rapidly digestible carbohydrate (RDC) and slowly digestible carbohydrate (SDC) has been used to specify their nutritional quality related to glucose homeostasis that is essential to normal functioning of the brain and critical to life. Although there have been many studies and reviews on slowly digestible starch (SDS) and SDC, the mechanisms of their slow digestion and absorption were mostly investigated from the material side without considering the physiological processes of their in vivo digestion, absorption, and most importantly interactions with other food components and the gastrointestinal tract. In this article, the physiological processes modulating the bioavailability of carbohydrates, specifically the rate and extent of their digestion and absorption as well as the related locations, in a whole food context, will be discussed by focusing on the activities of the gastrointestinal tract including glycolytic enzymes and glucose release, sugar sensing, gut hormones, and neurohormonal negative feedback mechanisms. It is hoped that a deep understanding of these physiological processes will facilitate the development of innovative dietary approaches to achieve desired carbohydrate or glucose bioavailability for improved health.

Incretin-based therapies for obesity treatment

Currently, obesity and its associated complications are considered major public health problems worldwide. Because the causes are multifactorial and complex, different treatment methods are used, which include diet and exercise, as well as the use of drugs, although they can have adverse side effects. A new target for the treatment of obesity may be the incretin system, which consists of hormones that seem to contribute to weight loss. In this sense, some studies have shown a relationship between weight loss and drugs related to incretin system, including glucagon-like peptide-1 (GLP-1) agonists and dipeptidyl peptidase-4 (DPP-4) inhibitors. The objective of this review is to summarize the association between the incretin system and obesity treatment.

Effects of glucagon-like peptide-1 receptor agonists on weight loss in patients with type 2 diabetes: a systematic review and network meta-analysis

To evaluate the effectiveness of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) on weight reduction in patients with Type 2 diabetes mellitus (Type 2 DM), a network meta-analysis was conducted. MEDLINE, EMBASE, Cochrane Library, and ClinicalTrials.gov were searched from 1950 to October 2013. Randomized controlled trials (RCTs) involving GLP-1 RAs were included if they provided information on body weight. A total of 51 RCTs were included and 17521 participants were enrolled. The mean duration of 51 RCTs was 31 weeks. Exenatide 10 μg twice daily (EX10BID) reduced weight compared with exenatide 5 μg twice daily (EX5BID), liraglutide 0.6 mg once daily (LIR0.6QD), liraglutide-1.2 mg once daily (LIR1.2QD), and placebo treatment, with mean differences of -1.07 kg (95% CI: -2.41, -0.02), -2.38 kg (95% CI: -3.71, -1.06), -1.62 kg (95% CI: -2.79, -0.43), and -1.92 kg (95% CI: -2.61, -1.24), respectively. Reductions of weight treated with liraglutide-1.8 mg once daily (LIR1.8QD) reach statistical significance (-1.43 kg (95% CI: -2.73, -0.15)) versus LIR1.2QD and (-0.98 kg (95% CI: -1.94, -0.02)) versus placebo. Network meta-analysis found that EX10BID, LIR1.8QD, and EX2QW obtained a higher proportion of patients with weight loss than other traditional hypoglycemic agents. Our results suggest GLP-1 RAs are promising candidates for weight control in comparison with traditional hypoglycemic drugs, and EX10BID, LIR1.8QD, and EX2QW rank the top three drugs.

Incretin therapies in the management of patients with type 2 diabetes mellitus and renal impairment

Renal impairment (RI) is common among patients with type 2 diabetes mellitus (T2DM), and these patients also experience an age-related decline in renal function. At the same time, treatment options are more limited and treatment is more complex, particularly in patients with moderate or severe RI due to contraindications, need for dose adjustment and/or regular monitoring, and side effects, such as fluid retention and hypoglycemia, which are a more serious concern in this patient population. Incretin therapies, consisting of the injectable glucagon-like peptide-1 (GLP-1) receptor agonists and the oral dipeptidyl peptidase-4 (DPP-4) inhibitors, are a promising new class of antihyperglycemic drugs. In the overall population, they improve glycemic control in a glucose-dependent manner and are not likely to cause hypoglycemia, representing a clear advantage in at-risk populations. Data regarding use of these agents in renally impaired patients have started to emerge, and the objective of this article is to provide an overview of the currently available data and the potential role of these novel agents in the management of patients with T2DM and RI. Data for the GLP-1 receptor agonists in patients with moderate or severe RI are still limited, with no trials dedicated to these populations currently published. In addition, their potential to cause gastrointestinal side effects may limit use in patients with RI due to the risk of dehydration and hypovolemia. The use of GLP-1 receptor agonists in patients with moderate or severe RI is therefore, at present, underlying caution and/or restrictions. On the other hand, data from specific trials in patients with moderate or severe RI are now becoming available for most of the DPP-4 inhibitors. These studies demonstrate good efficacy and tolerability of the DPP-4 inhibitors in patients with moderate or severe RI, thus opening a place for these therapies in the treatment of populations with T2DM and RI. Several of the DPP-4 inhibitors are already approved for use in patients with moderate or severe RI, including for those with end-stage renal disease. While discussing the advantages related to their common mechanism of action, this article also describes differences among the DPP-4 inhibitors (eg, related to their pharmacokinetic properties and the available clinical data). In conclusion, while initial data for these new therapies are promising, further experience is needed to fully assess the risk-benefit balance and clinical positioning of these agents in RI populations.

Recent progress and future options in the development of GLP-1 receptor agonists for the treatment of diabesity

The dramatic rise of the twin epidemics, type 2 diabetes and obesity is associated with increased mortality and morbidity worldwide. Based on this global development there is clinical need for anti-diabetic therapies with accompanied weight reduction. From the approved therapies, the injectable glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are the only class of agents which are associated with a modest weight reduction. Physiological effects of the gastro-intestinal hormone GLP-1 are improvement of glycemic control as well as a reduction in appetite and food intake. Different approaches are currently under clinical evaluation to optimize the therapeutic potential of GLP-1 RAs directed to once-weekly up to once-monthly administration. The next generation of peptidic co-agonists comprises the activity of GLP-1 plus additional gastro-intestinal hormones with the potential for increased therapeutic benefits compared to GLP-1 RAs.

Energy loss via urine and faeces--a combustive analysis in diabetic rats and the impact of antidiabetic treatment on body weight

AIMS

Intensive glycaemic control in type 2 diabetes achieved by insulin is generally accompanied by body weight gain. This study was performed to emphasize the meaning of caloric analysis of urine and faeces for energy balance.

METHODS

We measured energetic loss via urine and faeces during antihyperglycaemic treatment in male obese Zucker diabetic fatty (ZDF) rats. Rats were treated for 10 days with the sodium-glucose-linked transporter-2 (SGLT2) inhibitor AVE2268, with insulin glargine, with the GLP-1 receptor agonist lixisenatide and with the combination of insulin glargine and lixisenatide. Each study was accompanied by one lean (Fa/?) and one obese (fa/fa) untreated non-diabetic and diabetic control group, respectively. Blood glucose, body weight alterations and food assimilation efficiency were monitored.

RESULTS

In control ZDF rats, more than 12 g/day of pure glucose was urinarily excreted. In total, the energetic loss via urine exceeded 30% from total energy uptake. Insulin glargine treatment decreased urinary energetic loss, leading to a body weight gain of approximately 3 g/day. An almost body weight-neutral antihyperglycaemic treatment could be achieved with AVE2268 and lixisenatide. While lixisenatide reduced body weight gain via reduction of energy uptake, the SGLT2 inhibitor even increased urinary glucose and thus energy excretion. Combining insulin glargine with lixisenatide attenuated the anabolic effect of insulin resulting in weight neutrality.

CONCLUSIONS

Our data clearly show renal contribution to the body's energy control by urinary glucose excretion (UGE) during antidiabetic treatment. The undesired retained energy could be reduced via additional UGE or via simultaneous reduction of energy uptake and/or energy retention.

Weight change with liraglutide and comparator therapies: an analysis of seven phase 3 trials from the liraglutide diabetes development programme

AIM

We investigated the relationship between weight change and related factors in subjects with type 2 diabetes mellitus (T2DM) treated with liraglutide versus comparator diabetes therapies.

METHODS

Twenty-six-week data from seven phase 3, randomized trials in the liraglutide T2DM development programme were analysed by trial and treatment group: liraglutide (1.2 and 1.8 mg), active comparator and placebo. Outcome measures included proportions of subjects in various weight change categories and their percentage weight change from baseline; impact of body mass index (BMI) and gastrointestinal (GI) adverse events (AEs) on weight change and correlation of weight change with change in glycosylated haemoglobin (HbA1c).

RESULTS

A number of subjects experienced >5% weight loss during the trials (24.4% liraglutide 1.8 mg and 17.7% liraglutide 1.2 mg; 17.7% exenatide, 10.0% sitagliptin, 3.6-7.0% sulphonylurea, 2.6% thiazolidinedione and 2.6% glargine; 9.9% placebo). More weight loss was seen with liraglutide 1.2 and 1.8 mg than with active comparators except exenatide. Across trials, higher initial BMI was associated with slightly greater weight loss with liraglutide. Mean weight loss increased slightly the longer GI AEs persisted. Although HbA1c reduction was slightly larger in higher weight loss categories across treatments (including placebo), sample sizes were small and no clear correlation could be determined. Liraglutide-treated subjects experienced additional HbA1c reduction beyond that which appeared weight induced; thus, not all HbA1c-lowering effect appears weight mediated.

CONCLUSIONS

The majority of liraglutide-treated T2DM subjects experienced weight loss in this analysis. Weight loss was greater and occurred more in glucagon-like peptide-1 receptor agonist-treated subjects than in active comparator-treated subjects.

Plasma dipeptidyl peptidase 4 activity correlates with body mass index and the plasma adiponectin concentration in healthy young people

We previously found that plasma dipeptidyl peptidase 4 (DPP4) activity was associated with the development of obesity, type 2 diabetes, and type 1 diabetes using animal models. In this study, we investigated whether DPP4 activity is correlated with the clinical parameters of obesity and/or diabetes in healthy young subjects. Body mass index (BMI), plasma DPP4 activity, total cholesterol, high density lipoprotein (HDL) cholesterol, triglycerides, fasting blood glucose, adiponectin concentration, and body fat were measured in 165 subjects (110 males and 55 females, age 23.2 ± 2.4 years). In correlation analyses, DPP4 activity displayed strong positive correlations with BMI (p = 5.5 × 10(-5)) and total cholesterol (p = 0.0014), and a negative correlation with the plasma adiponectin concentration (p = 0.013), but not fasting blood glucose. Our findings suggest that plasma DPP4 activity is correlated with the clinical parameters of obesity rather than diabetes in young people.

Discovery of orally active carboxylic acid derivatives of 2-phenyl-5-trifluoromethyloxazole-4-carboxamide as potent diacylglycerol acyltransferase-1 inhibitors for the potential treatment of obesity and diabetes

Diacylglycerol acyltransferase-1 (DGAT-1) is the enzyme that catalyzes the final and committed step of triglyceride formation, namely, the acylation of diacylglycerol with acyl coenzyme A. DGAT-1 deficient mice demonstrate resistance to weight gain on high fat diet, improved insulin sensitivity, and reduced liver triglyceride content. Inhibition of DGAT-1 thus represents a potential novel approach for the treatment of obesity, dyslipidemia, and metabolic syndrome. In this communication, we report the identification of the lead structure 6 and our lead optimization efforts culminating in the discovery of potent, selective, and orally efficacious carboxylic acid derivatives of 2-phenyl-5-trifluoromethyloxazole-4-carboxamides. In particular, compound 29 (DGAT-1 enzyme assay, IC(50) = 57 nM; CHO-K1 cell triglyceride formation assay, EC(50) = 0.5 μM) demonstrated dose dependent inhibition of weight gain in diet induced obese (DIO) rats (0.3, 1, and 3 mg/kg, p.o., qd) during a 21-day efficacy study. Furthermore, compound 29 demonstrated improved glucose tolerance determined by an oral glucose tolerance test (OGTT).