Leptin concentrations in endometriosis: A systematic review and meta-analysis

The role of peroxisome proliferator-activated receptors in endometriosis

Endometriosis constitutes the most common cause of chronic pelvic pain in female patients and is associated with infertility. Although there is no known cause for the disease, it is a heritable condition that is determined by numerous genetic, epigenetic, and environmental aspects. Peroxisome proliferator-activated receptors (PPARs) represent nuclear receptor proteins that control gene expression. By using the MEDLINE and LIVIVO databases we conducted a literature review in order to look into the role of PPARs in the endometriosis pathophysiology and succeeded in revealing 36 pertinent publications between 2001 and 2022. In regards to PPAR expression in endometriosis, PPARγ seems to represent the most studied PPAR isoform in endometriosis and to influence various pathways involved in the disease onset and progression. It's interesting to note that diverse treatment agents targeting the PPAR system have been identified as innovative, effective therapeutic alternatives in the context of endometriosis treatment. In conclusion, PPARs appear to contribute an important role in both endometriosis pathophysiology and therapy.

The kisspeptin system in and beyond reproduction: exploring intricate pathways and potential links between endometriosis and polycystic ovary syndrome

Endometriosis and polycystic ovary syndrome (PCOS) are two common female reproductive disorders with a significant impact on the health and quality of life of women affected. A novel hypothesis by evolutionary biologists suggested that these two diseases are inversely related to one another, representing a pair of diametrical diseases in terms of opposite alterations in reproductive physiological processes but also contrasting phenotypic traits. However, to fully explain the phenotypic features observed in women with these conditions, we need to establish a potential nexus system between the reproductive system and general biological functions. The recent discovery of kisspeptin as pivotal mediator of internal and external inputs on the hypothalamic-pituitary-gonadal axis has led to a new understanding of the neuroendocrine upstream regulation of the human reproductive system. In this review, we summarize the current knowledge on the physiological roles of kisspeptin in human reproduction, as well as its involvement in complex biological functions such as metabolism, inflammation and pain sensitivity. Importantly, these functions are known to be dysregulated in both PCOS and endometriosis. Within the evolving scientific field of "kisspeptinology", we critically discuss the clinical relevance of these discoveries and their potential translational applications in endometriosis and PCOS. By exploring the possibilities of manipulating this complex signaling system, we aim to pave the way for novel targeted therapies in these reproductive diseases.

The effect of pentoxifylline and different types of exercise training on coagulation factors in a rat endometriosis model

Objectives

This study evaluated the effects of high-intensity interval training (HIIT), moderate-intensity continuous training (MICT), and pentoxifylline (PTX) on coagulation factors, including the amount and percentage of lymphocytes, PLC, PLR, aPTT, PT, PT.I.N. R in a model of rats with endometriosis.

Methods

Endometriosis was surgically induced in female Sprague-Dawley rats. The rats with confirmed endometrial implants were divided into control, MICT, pentoxifylline (D), HIIT+D, and MICT+D, HIIT groups. D and exercise interventions were performed for eight weeks. Then, the macroscopic size of endometriosis lesions was measured, and inflammatory factors (count and percentage of lymphocytes) and coagulation factors, including PLC, PLR, aPTT, PT, PT.I.N. R, and PLR in blood samples were evaluated.

Results

D significantly decreased the volume of lesions and significantly increased PT and PT.I.N. R in blood. HIIT decreased the volume of lesions and significantly increased PT. MICT did not cause significant effects on the target variables. MICT+D decreased the volume of lesions. HIIT+D significantly decreased the volume of lesions and PLC and increased aPTT as well as the count and percentage of lymphocytes, PT, and PT.I.N. R, and decreased PLR.

Conclusions

All interventions(except for MICT) especially HIIT+D and D by priority, induced a significant effect on reducing some indices of inflammation and coagulation.

How Can Selected Dietary Ingredients Influence the Development and Progression of Endometriosis?

Endometriosis is a chronic, hormone-dependent disease characterized by the presence of endometrial tissue in ectopic locations. Since the treatment options for this disease are still limited, and the cure rate is unsatisfactory, the search for ways to treat symptoms and modify the course of the disease is of key importance in improving the quality of life of patients with endometriosis. So far, the literature has shown that nutrition can influence endometriosis through hormonal modification and altering the inflammatory or oxidative response. Since the importance of nutrition in this disease is still a subject of scientific research, we aimed to summarize the current knowledge on the role of dietary modifications in endometriosis. Our review showed that nutrients with anti-inflammatory and antioxidant properties, including most vitamins and several trace elements, may influence the pathogenesis of endometriosis and can be considered as the nutrients preventing the development of endometriosis. However, despite the many discoveries described in this review, further interdisciplinary research on this topic seems to be extremely important, as in the future, it may result in the development of personalized therapies supporting the treatment of endometriosis.

Evaluation of adipokines concentrations in plasma, peritoneal, and endometrioma fluids in women operated on for ovarian endometriosis

Introduction

Some studies indicate the role of selected adipokines in the development of endometriosis. However, a comprehensive assessment of plasma, peritoneal, and endometrioma fluids adipokines concentrations in women with ovarian endometriosis has not yet been performed. Therefore, this study aimed to analyze plasma, peritoneal, and endometrioma fluids selected adipokines concentrations in women operated on for ovarian endometriosis.

Materials and methods

A cross-sectional cohort study involved 56 women operated on for ovarian endometriosis. Body mass, height, and waist circumference were measured, and BMI was calculated. Plasma, peritoneal, and endometrioma fluids adiponectin, leptin, omentin resistin, RBP4, and visfatin/NAMPT were determined by ELISA.

Results

The highest plasma levels of adiponectin, leptin, omentin, and RBP4 than in the endometrioma and peritoneal fluids were found, while levels of resistin and visfatin/NAMPT were significantly higher in endometrioma fluid than in plasma and peritoneal fluid. In addition, levels of visfatin/NAMPT were significantly higher in peritoneal fluid than in plasma. There were also positive correlations between leptin, RBP4, and adiponectin levels in endometrioma and peritoneal fluids (ρ = 0.28; p < 0.05; ρ = 0.31; p < 0.05; ρ= 0.32; p < 0.05, respectively). There were no associations between adipokines levels in plasma, endometrioma, and peritoneal fluids and endometriosis stage.

Conclusion

Our results show that visfatin/NAMPT and resistin may be locally secreted in endometrioma related to inflammation regardless of the stage of endometriosis.

Physiopathological mechanisms related to inflammation in obesity and type 2 diabetes mellitus

Overweight, obesity, and type 2 diabetes mellitus pose global health problems that are ever-increasing. A chronic low-grade inflammatory status and the presence of various pro-inflammatory markers either in circulation or within dysfunctional metabolic tissues are well established. The presence of these factors can, to some extent, predict disease development and progression. A central role is played by the presence of dysfunctional adipose tissue, liver dysfunction, and skeletal muscle dysfunction, which collectively contribute to the increased circulatory levels of proinflammatory factors. Weight loss and classical metabolic interventions achieve a decrease in many of these factors’ circulating levels, implying that a better understanding of the processes or even the modulation of inflammation may alleviate these diseases. This review suggests that inflammation plays a significant role in the development and progression of these conditions and that measuring inflammatory markers may be useful for assessing disease risk and development of future treatment methods.

Implications of obesity and adiposopathy on respiratory infections; focus on emerging challenges

Obesity is characterized by excessive adipose tissue accumulation, which impacts physiological, metabolic, and immune functions. Several respiratory infections, including bacterial pneumonia, influenza, and coronavirus disease 2019, appear to be linked to unfavorable results in individuals with obesity. These may be attributed to the direct mechanical/physiological effects of excess body fat on the lungs’ function. Notably, adipose tissue dysfunction is associated with a low-grade chronic inflammatory status and hyperleptinemia, among other characteristics. These have all been linked to immune system dysfunction and weakened immune responses to these infections. A better understanding and clinical awareness of these risk factors are necessary for better disease outcomes.

Effects of vitamin D supplementation in endometriosis: a systematic review

BACKGROUND

There is a growing body of human, animal and in vitro studies on vitamin D (vit D) substitution in endometriosis. The aim of this systematic review is to critically appraise and qualitatively synthesize the results of the available studies that examine the supplementation of vit D for endometriosis treatment.

METHODS

A systematic search of the literature was conducted in four electronic databases (Medline, Cochrane, Scopus, Embase) and grey literature for original research articles on humans, animals and in vitro models published in any language.

RESULTS

Four human studies, four animal studies and four in vitro studies were included. Quantitative synthesis of human studies showed no significant effect of vit D intake for dysmenorrhea (2 studies, 44 vit D vs 44 placebo, mean -0.71, 95% CI -1.94, 0.51) and non-cyclic pelvic pain (2 studies, 42 vit D vs 38 placebo, mean 0.34, 95% CI -0.02, 0.71). Regarding reproductive outcomes in women with endometriosis after in vitro fertilization, the only available study showed no differences between women taking vit D and women taking placebo. Three of the four included animal studies showed regression of endometriotic implants when treated with vit D. The in vitro studies demonstrated that vit D decreases invasion and proliferation of endometriotic lesions without affecting apoptosis.

CONCLUSIONS

Although in vitro and animal studies suggest regression of the endometriotic implants and decrease of invasion and proliferation after vit D supplementation, this was not reflected in the results of the meta-analysis, which showed no benefit of vit D supplementation in patients with endometriosis and dysmenorrhea or non-cyclic pelvic pain as well as on the outcome of IVF treatment. However, given the heterogeneity and the diversity of the available studies, more research is required to shed light on the role of vit D supplementation in women with endometriosis.

The Complex Roles of Adipokines in Polycystic Ovary Syndrome and Endometriosis

Polycystic ovary syndrome (PCOS) and endometriosis are frequent diseases of the female reproductive tract causing high morbidity as they can significantly affect fertility and quality of life. Adipokines are pleiotropic signaling molecules secreted by white or brown adipose tissues with a central role in energy metabolism. More recently, their involvement in PCOS and endometriosis has been demonstrated. In this review article, we provide an update on the role of adipokines in both diseases and summarize previous findings. We also address the results of multi-omics approaches in adipokine research to examine the role of single nucleotide polymorphisms (SNPs) in genes coding for adipokines and their receptors, the secretome of adipocytes and to identify epigenetic alterations of adipokine genes that might be conferred from mother to child. Finally, we address novel data on the role of brown adipose tissue (BAT), which seems to have notable effects on PCOS. For this review, original research articles on adipokine actions in PCOS and endometriosis are considered, which are listed in the PubMed database.

The Levels of Ghrelin, Glucagon, Visfatin and Glp-1 Are Decreased in the Peritoneal Fluid of Women with Endometriosis along with the Increased Expression of the CD10 Protease by the Macrophages

The aim of this study was to evaluate the levels of ten energy metabolism factors: C-peptide, ghrelin, GIP, GLP-1, glucagon, insulin, leptin, PAI-1 (total), resistin, and visfatin, and to determine the expression of GLP1R receptors, CD10, CD26 proteases, and pro-inflammatory marker CD86 by macrophages in the peritoneal fluid (PF) in patients with endometriosis. The study included 54 women with endometriosis and a control group of 30 women with uterine myoma without signs of endometriosis. The levels of factors in PF were assessed by a multiplex method. Expression of GLP1R receptors, CD10, CD26 proteases, and CD86 by macrophages was evaluated using flow cytometry. It was found that in women with endometriosis, the concentrations of ghrelin, GLP-1, glucagon, and visfatin in PF were reduced (p = 0.007, p = 0.009, p = 0.002, p = 0.008, respectively). At the same time, there was a noted increase in the CD10 protease expression by peritoneal macrophages (p = 0.044). Correlation analysis showed a positive correlation of ghrelin and GLP-1 levels with CD86 macrophage expression (p = 0.044, p = 0.022, respectively) in the study group; a positive correlation was also found between the levels of GLP-1, glucagon, and visfatin with CD26 macrophage expression (p = 0.041, p = 0.048, p = 0.015, respectively) in PF. No correlations were found in the control group. These results indicate that a decrease in the levels of ghrelin, GLP-1, glucagon, and visfatin in PF may contribute to endometriosis development through their impact on the expression of pro-inflammatory markers of PF macrophages.

Leptin Stimulates Endometriosis Development in Mouse Models

Endometriosis is a chronic inflammatory condition in women, and obesity leads to an inflammatory condition that is directly involved in the etiology of endometriosis. However, observational studies have shown an inverse correlation between endometriosis and a low body mass index (BMI). Obesity does not protect against endometriosis, and on the contrary, an increased BMI may lead to more severe forms of the disease. To determine the effect of obesity on endometriosis, diet-induced and genetically engineered obese mouse models were integrated with endometriosis mouse models with fluorescence-tagged ectopic lesions. High-fat diet-induced obese mice revealed a significant increase in endometriosis development compared with regular-diet control mice. However, obese recipient mice with leptin deficiency and leptin receptor deficiency showed suppressed endometriosis development compared with control mice. Furthermore, donor uterine tissues with leptin deficiency and leptin receptor deficiency suppressed endometriosis development compared with control donor in control recipient mice. Importantly, we revealed that aberrant high levels of leptin concentration significantly increased endometriosis development compared with vehicle treatment group in control mice with normal body weight. Our results suggest that leptin and its receptor are critical for endometriosis development.

Leptin levels in women with unexplained infertility: A systematic review and meta-analysis

BACKGROUND

Unexplained infertility (UI) is usually used for any heterosexual couple who failed to have a successful clinical pregnancy without identifying clear causes after they undergo all standard fertility tests. Evidence shows that leptin is one of the most accurate biomarkers for UI. Nevertheless, conflicting results regarding leptin levels in women with UI have been reported.

AIM

To find the serum leptin levels in women with UI.

METHODS

All studies written in English and conducted before April 30, 2021 from PubMed/MEDLINE, Embase, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, Google Scholar, OpenGrey, OATD, and the infertility conference abstract were included. Studies were found eligible if they provided the mean and standard deviation of leptin for the case group and control group. The quality assessment of individual studies was evaluated using the Joanna Briggs Institute Quality Assessment Tool. Data synthesis and statistical analysis were done using STATA software version 16.

RESULTS

A total of 378 studies were reviewed, and just six studies that fulfilled the eligibility criteria were included in this meta-analysis. The pooled result showed that leptin levels were significantly higher in women with UI compared to fertile women, with a standardized mean difference of 0.97 (95% confidence interval: -0.49-2.43). However, heterogeneity across studies was highly significant (P < 0.00001; I² = 98.8%).

CONCLUSION

The results of this study suggest that leptin levels are elevated in women with UI compared with fertile women; hence, leptin could be a potential biomarker for UI in women, and it may be useful for identifying women with a high risk of infertility.

What is the link between endometriosis and adiposity?

Endometriosis is defined by the presence of extrauterine endometrial tissue and presents with symptoms of dysmenorrhea, chronic pelvic pain, and impaired fertility. This condition often follows a chronic progressive course with favorable recurrence, even after surgical or medical treatment. The etiology or exact pathophysiology of endometriosis remains to be clarified, although it is thought to be a complex and multifactorial disease. Prior epidemiological or population-based studies have reported several risk factors related to endometriosis, such as environmental, menstrual, habitual, and lifestyle factors. Moreover, anthropometry has been found to be significantly associated with the diagnosis of endometriosis, as a lower body mass index is associated with an elevated risk of endometriosis. Here, we review studies that have examined the association between body size and the risk of endometriosis and discuss the clinical and biological significance of the relationship between adiposity and endometriosis.

Leptin as a Biomarker of Stress: A Systematic Review and Meta-Analysis

BACKGROUND

Leptin is a satiety hormone mainly produced by white adipose tissue. Decreasing levels have been described following acute stress.

OBJECTIVE

To conduct a systematic review and meta-analysis to determine if leptin can be a biomarker of stress, with levels decreasing following acute stress.

METHODS

PubMed, Cochrane Library, Embase, and ScienceDirect were searched to obtain all articles studying leptin levels after acute stress on 15 February 2021. We included articles reporting leptin levels before and after acute stress (physical or psychological) and conducted random effects meta-analysis (DerSimonian and Laird approach). We conducted Meta-regressions and sensitivity analyses after exclusion of groups outside the metafunnel.

RESULTS

We included seven articles-four cohort and three case-control studies-(28 groups) from 27,983 putative articles. Leptin levels decreased after the stress intervention (effect size = -0.34, 95%CI -0.66 to -0.02) compared with baseline levels, with a greater decrease after 60 min compared to mean decrease (-0.45, -0.89 to -0.01) and in normal weight compared to overweight individuals (-0.79, -1.38 to -0.21). There was no difference in the overweight population. Sensitivity analyses demonstrated similar results. Levels of leptin after stress decreased with sex ratio-i.e., number of men/women-(-0.924, 95%CI -1.58 to -0.27) and increased with the baseline levels of leptin (0.039, 0.01 to 0.07).

CONCLUSIONS

Leptin is a biomarker of stress, with a decrease following acute stress. Normal-weight individuals and women also have a higher variation of leptin levels after stress, suggesting that leptin may have implications in obesity development in response to stress in a sex-dependent manner.