Effect of glucagon-like peptide-1 receptor agonists on circulating levels of leptin and resistin: A meta-analysis of randomized controlled trials

Leptin and Insulin in COPD: Unveiling the Metabolic-Inflammatory Axis-A Narrative Review

Chronic obstructive pulmonary disease (COPD) is a progressive and debilitating condition characterized by airflow limitations and systemic inflammation. The interaction between the metabolic and inflammatory pathways plays a key role in disease progression, with leptin and insulin emerging as pivotal metabolic regulators. Leptin, an adipokine that regulates energy homeostasis, and insulin, the primary regulator of glucose metabolism, are both altered in COPD patients. This narrative review provides an in-depth examination of the roles of leptin and insulin in COPD pathogenesis, focusing on the molecular mechanisms through which these metabolic regulators interact with inflammatory pathways and how their dysregulation contributes to a spectrum of extrapulmonary manifestations. These disturbances not only exacerbate COPD symptoms but also increase the risk of comorbidities such as metabolic syndrome, diabetes, cardiovascular disease, or muscle wasting. By exploring the underlying mechanisms of leptin and insulin dysregulation in COPD, this review underscores the significance of the metabolic-inflammatory axis, suggesting that restoring metabolic balance through leptin and insulin modulation could offer novel therapeutic strategies for improving clinical outcomes.

Effect of Fibrates on Lipoprotein-associated Phospholipase A2 Mass and Activity: A Systematic Review and Meta-analysis of Controlled Clinical Trials

BACKGROUND

In vascular tissue, macrophages and inflammatory cells produce the enzyme lipoprotein- associated phospholipase A2 (Lp-PLA2). Treatment with fibrates decreases Lp-PLA2 levels in individuals with obesity and metabolic syndrome; however, these findings have not been fully clarified.

OBJECTIVE

The goal of this study was to investigate the possible effects of fibrate therapy on Lp-PLA2 mass and activity through a meta-analysis of clinical trials.

METHODS

Web of Science, PubMed, Scopus, Google Scholar, and ClinicalTrials.gov databases were searched using MeSH terms and keywords. Randomized controlled trials (RCT) evaluating the effect of statins on Lp- PLA2 mass and/or activity were included in the meta-analysis. Quantitative data were analyzed using a random- effects model and the generic inverse variance method.

RESULTS

The meta-analysis of 10 clinical trials indicated that fibrate treatment has no significant effect on Lp- PLA2 mass (fibrate vs. placebo/nothing = WMD: -3.29 ng/ml, 95% CI: -21.35, 14.78, p = 0.72; fibrate vs. active control = WMD: -1.08 ng/ml, 95% CI: -51.38, 49.22, p = 0.97); Lp-PLA2 activity (fibrate vs. active control = WMD: 0.84 nmol/ml/min, 95% CI: -0.17, 1.84, p = 0.10); HDL-LpPLA2 activity (fibrate vs. active control = WMD: 0.77 nmol/ml/min, 95% CI: -0.33, 1.88, p = 0.17); and secretory PLA2 (fibrate vs. active control = WMD: 0.37 ng/ml, 95% CI: -1.22, 1.97, p = 0.65). Also, the results of the sensitivity analysis were robust for all these parameters.

CONCLUSION

In conclusion, fibrate therapy did not reduce the mass and activity of Lp-PLA2.

Comparative Efficacy of Semaglutide Versus Liraglutide or Efinopegdutide on Weight Loss in Obese Patients: A Systematic Review and Meta-Analysis

Glucagon-like peptide-1 agonists (GLP-1 RAs) have produced substantial weight loss effects in type 2 diabetes mellitus (T2DM) cohorts, but these effects have not been thoroughly studied in patients with obesity and without diabetes. This review aimed to analyze direct comparative studies for semaglutide versus other GLP-1 RA (liraglutide and efinopegdutide) in facilitating weight loss and evaluating adverse events in patients with obesity. A systematic search following the guidelines established by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was performed in PubMed, Embase, and Cochrane Library for direct comparative studies comparing semaglutide with other GLP-1 RA on weight loss in patients with obesity. A narrative synthesis and meta-analysis were performed to analyze the differences in weight loss between cohorts. A meta-analysis found that semaglutide produced a greater effect on mean weight loss compared to liraglutide, but did not produce a significant difference compared to efinopegdutide. Semaglutide, liraglutide, and efinopegdutide were well-tolerated and were associated with primarily minimal to moderate severity adverse effects, most of which were gastrointestinal. Future studies should continue to focus on conducting direct comparisons between GLP-1 RAs and emerging multi-receptor GLP-1 RAs, such as efinopegdutide, tirzepatide, and retratrutide, to determine clinical efficacy, long-term safety, and identifying the most effective regimens for clinical practice.

Evidence from clinical studies of leptin: current and future clinical applications in humans

Leptin has been established as the prototype adipose tissue secreted hormone and as a major regulator of several human physiology functions. Here, we are primarily reviewing the findings from studies in humans involving leptin administration. We are describing the metabolic, endocrine and immunologic effects of leptin replacement in conditions of leptin deficiency, such as short-term fasting in healthy individuals, relative energy deficiency in sports (REDS), congenital leptin deficiency (CLD), generalized (GL) and partial lipodystrophy (PL), HIV-associated lipodystrophy (HIV-L) and of leptin treatment in conditions of leptin excess (common obesity, type 2 diabetes, steatotic liver disease). We are comparing the results with the findings from preclinical models and present the main conclusions regarding the role of leptin in human physiology, pathophysiology and therapeutics. We conclude that, in conditions of energy deficiency, leptin substitution effectively reduces body weight and fat mass through reduction of appetite, it improves hypertriglyceridemia, insulin resistance and hepatic steatosis (especially in GL and PL), it restores neuroendocrine function (especially the gonadotropic axis), it regulates adaptive immune system cell populations and it improves bone health. On the contrary, leptin treatment in conditions of leptin excess, such as common obesity and type 2 diabetes, does not improve any metabolic abnormalities. Strategies to overcome leptin tolerance/resistance in obesity and type 2 diabetes have provided promising results in animal studies, which should though be tested in humans in randomized clinical trials.

Leptin is a potential biomarker of childhood obesity and an indicator of the effectiveness of weight-loss interventions

Childhood obesity represents a significant public health concern, imposing a substantial burden on the healthcare system. Furthermore, weight-loss programs often exhibit reduced effectiveness in adults who have a history of childhood obesity. Therefore, early intervention against childhood obesity is imperative. Presently, the primary method for diagnosing childhood obesity relies on body mass index (BMI), yet this approach has inherent limitations. Leptin, a satiety hormone produced by adipocytes, holds promise as a superior tool for predicting both childhood and subsequent adulthood obesity. In this review, we elucidate the tools employed for assessing obesity in children, delve into the biological functions of leptin, and examine the factors governing its expression. Additionally, we discuss maternal and infantile leptin levels as predictors of childhood obesity. By exploring the relationship between leptin levels and weight loss, we present leptin as a potential indicator of the effectiveness of obesity interventions.

Effect of Statin Treatment on Lipoprotein-Associated Phospholipase A2 Mass and Activity: A Systematic Review and Meta-analysis of Randomized Placebo-Controlled Trials

PURPOSE

The goal of this meta-analysis was to establish whether statin treatment reduces Lp-PLA2 mass concentration and/or activity.

METHODS

PubMed, Scopus, Web of Science, ClinicalTrials.gov, and Google Scholar databases were searched using MESH terms and keywords. Randomized controlled trials (RCT) with either parallel or cross-over design examining the effect of statins on Lp-PLA2 mass and/or activity were included in meta-analysis.

RESULTS

Out of 256 articles, 10 RCT were selected for meta-analysis. Statin therapy significantly reduced both Lp-PLA2 mass (WMD -44.46 ng/mL; 95%CI -59.01, -29.90; p < 0.001; I2 = 93%) and activity (WMD -39.37 nmol/min/mL; 95%CI -69.99, -8.75; p = 0.01; I2 = 100%). The sensitivity analysis was robust for Lp-PLA2 mass and was also positive for two studies concerning Lp-PLA2 activity.

CONCLUSION

Statin therapy significantly reduced both Lp-PLA2 mass and activity.

Weight Loss Improved Hypothalamic GH Deficiency but not Hypogonadotropic Hypogonadism in a Man With Down Syndrome

Down syndrome (DS) is associated with several endocrine disorders, including diabetes, obesity, and primary hypogonadism. Here, we present a man with DS who manifested with atypical hypogonadotropic hypogonadism and in whom weight loss resulted in the improvement of hypothalamic GH deficiency. A 27-year-old man with DS and severe obesity was admitted for hypoxia resulting from obesity hypoventilation syndrome. Laboratory tests showed normal levels of LH and FSH despite low testosterone and free testosterone levels. Moreover, thyroid stimulating hormone and prolactin levels were slightly elevated, although a euthyroid function was observed, and GH and IGF-1 levels were low. Endocrinological stimulation tests revealed hypogonadotropic hypogonadism and hypothalamic GH deficiency. Reduction in body weight by 35.3% resulted in the improvement of the IGF-1, thyroid stimulating hormone, and prolactin levels to the reference range, whereas the LH and FSH levels remained low, despite slight elevation. Levels of leptin, which suppresses the hypothalamus-gonadotroph-gonadal axis and upregulates thyrotropin-releasing hormone expression, decreased with weight loss. Furthermore, ghrelin, whose levels increase with weight loss, stimulates GH secretion. Thus, leptin and ghrelin could have contributed to the observed changes in the pituitary hormone profile after weight loss.

GLP-1 receptor agonist as an effective treatment for breast cancer-related lymphedema: a case report

Introduction

Lymphedema is a major public health issue for many women undergoing breast cancer treatment. Although weight loss has been reported to be beneficial in the treatment of lymphedema, no studies to date have examined the use of GLP-1RAs for the treatment of secondary lymphedema. This case report describes a patient who experienced significant resolution of her breast cancer-related lymphedema after initiation of a GLP-1RA for weight loss.

Main symptoms and/or important clinical findings

Nine months postoperatively the patient developed arm swelling and disability. While on adjuvant chemo and hormonal therapy, her weight increased dramatically and peaked 4 years later. Corresponding to her weight gain was significant worsening of her symptoms.

The main diagnoses therapeutic interventions and outcomes

Due to adjuvant cancer-related weight gain and inability to lose weight with diet and exercise, she was referred for evaluation and diagnosed with lymphedema. The patient started treatment with a Glucagon-like peptide 1 receptor agonist and lost 24% of her body weight over the next 13 months. The improvement in her lymphedema mirrored her weight loss. Her limb volume difference dropped from 10.3% down to 3.4% and she no longer required a compression garment. Her imaging demonstrated return of lymphatic pumping and she experienced a significant improvement in quality of life, assessed by a validated lymphedema-specific patient reported outcome (PROM). She remains on hormonal therapy, no longer needs compression and is back to regular exercise without impairment.

Conclusions

GLP-1 RAs provide a potential medical option for many patients struggling with weight gain and lymphedema. We have observed by all objective measures a significant reduction in lymphedema and the elimination of compression in the case presented as a direct result of GLP-1 RA. This may also reduce a patient's BMI to the point where they become a good candidate for lymphovenous bypass or vascularized lymph node transplant when indicated.

Effect of Fibrate Treatment on Circulating Adipokine Levels: A Systematic Review and Meta-analysis of Randomized Clinical Trials

BACKGROUND

Fibrates are widely used in the treatment of dyslipidemia and associated metabolic abnormalities; however, their effects on adipokines are unclear.

AIM OF THE STUDY

This meta-analysis of clinical trials aimed to evaluate the effect of fibrates on circulating adipokine levels.

METHODS

Only randomized controlled trials investigating the impact/effect of fibrate treatment on circulating adipokine levels were included from searches in PubMed-Medline, SCOPUS, ClinicalTrials.gov, Web of Science, and Google Scholar databases. A random effects model and the generic inverse variance method were used for the meta-analysis. Sensitivity analysis was conducted using the leave-one-out method.

RESULTS

This meta-analysis of 22 clinical trials showed a significant reduction on/in leptin (WMD: -1.58 ng/mL, 95% CI: -2.96, -0.20, p = 0.02, I2 = 0%), plasminogen activator inhibitor-1 (PAI-1) (WMD: -13.86 ng/mL, 95% CI: -26.70, -1.03, p = 0.03, I2 = 99%), and visfatin (WMD: -1.52 ng/mL, 95% CI: -2.49, -0.56, p = 0.002, I2 = 0%) after fibrate therapy; no significant effect was observed on adiponectin (WMD: -0.69 µg/ml, 95% CI: -1.40, 0.02, p = 0.06, I2 = 83%) and resistin (WMD: -2.27 ng/mL, 95% CI: -7.11, 2.57, p = 0.36, I2 = 0%). The sensitivity analysis was robust only for visfatin, while the effect size was sensitive to one arm for leptin, four for adiponectin, and two for PAI-1.

CONCLUSION

This meta-analysis showed that fibrate treatment significantly improves adipokine levels with a decrease in leptin, PAI-1, and visfatin, suggesting potential additional clinical therapeutic benefits through/of fibrate treatment on adipose tissue.

Effects of Coffee Supplementation on Homocysteine and Leptin Levels: A Systematic Review and Meta-analysis of Clinical Trials

BACKGROUND

It has been reported that the consumption of antioxidant foods and beverages may benefit the development of cardiovascular risk factors. However, the impact of coffee consumption on some of these factors, such as homocysteine and leptin is controversial. Some clinical trials have suggested that coffee administration increases plasma total homocysteine levels, while others have found no significant changes in leptin concentrations.

OBJECTIVE

This study aimed to assess the effects of coffee supplementation on homocysteine and leptin concentrations in a meta-analysis of clinical trials.

METHODS

PubMed, Web of Science, Scopus, ClinicalTrials.gov, and Google Scholar databases were searched from inception to September 29, 2021. A fixed-effects model and the generic inverse variance weighting method were used for meta-analysis.

RESULTS

The meta-analysis demonstrated that coffee administration significantly increases homocysteine levels (WMD: 0.55 μmol/L, 95% CI: 0.17, 0.93, p = 0.005, I2 = 0%) but has no significant changes in leptin concentrations (WMD: 1.34 ng/mL, 95% CI: -0.78, 3.45, p = 0.21, I2 = 0%). Additionally, the sensitivity analysis was robust for both homocysteine and leptin levels.

CONCLUSION

The results of the present meta-analysis revealed that coffee supplementation raises serum homocysteine concentrations but has no effect on circulating leptin levels.

Liraglutide Lowers Palmitoleate Levels in Type 2 Diabetes. A Post Hoc Analysis of the LIRAFLAME Randomized Placebo-Controlled Trial

Background

Liraglutide is a glucose-lowering medication used to treat type 2 diabetes and obesity. It is a GLP-1 receptor agonist with downstream metabolic changes beyond the incretin system, such as reducing the risk of cardiovascular complications. The understanding of these changes is critical for improving treatment outcomes. Herein, we present a post hoc experimental analysis using metabolomic phenotyping to discover molecular mecphanisms in response to liraglutide.

Method

Plasma samples were obtained from The LiraFlame Study (ClinicalTrials.gov identifier: NCT03449654), a randomized double-blinded placebo-controlled clinical trial, including 102 participants with type 2 diabetes randomized to either liraglutide or placebo treatment for 26 weeks. Mass spectrometry-based metabolomics analyses were carried out on samples from baseline and the end of the trial. Metabolites (n=114) were categorized into pathways and linear mixed models were constructed to evaluate the association between changes in metabolites and liraglutide treatment.

Results

We found the free fatty acid palmitoleate was significantly reduced in the liraglutide group compared to placebo (adjusted for multiple testing p-value = 0.04). The activity of stearoyl-CoA desaturase-1 (SCD1), the rate limiting enzyme for converting palmitate into palmitoleate, was found significantly downregulated by liraglutide treatment compared to placebo (p-value = 0.01). These metabolic changes have demonstrated to be linked to insulin sensitivity and cardiovascular health.

Impact of Incretin-Based Therapies on Adipokines and Adiponectin

Adipokines are a family of hormones and cytokines with both pro- and anti-inflammatory effects released into the circulation to exert their hormonal effects. Adipokines are closely involved in most metabolic pathways and play an important modulatory role in lipid and carbohydrate homeostasis as they are involved in the pathophysiology of most metabolic disorders. Incretin-based therapy is a newly introduced class of antidiabetic drugs that restores euglycemia through several cellular processes; however, its effect on adipokines expression/secretion is not fully understood. In this review, we propose that incretin-based therapy may function through adipokine modulation that may result in pharmacologic properties beyond their direct antidiabetic effects, resulting in better management of diabetes and diabetes-related complications.