Blood Circulating Levels of Adipokines in Polycystic Ovary Syndrome Patients: A Systematic Review and Meta-analysis

Biomarkers to inform the management of polycystic ovary syndrome: A review of systematic reviews

INTRODUCTION

Polycystic ovarian syndrome (PCOS) is the commonest endocrine condition affecting reproductive age women. Many biomarkers may aid assessment and management, however evidence is limited on their utility in clinical practice. We conducted a review of systematic reviews to identify the most useful biomarkers in the clinical management of PCOS.

METHODS

We searched MEDLINE, EMBASE, CENTRAL and HTA until August 2023 for reviews evaluating biomarkers in PCOS women compared to healthy controls. Methodological quality was assessed using the AMSTAR2 tool. We reported pooled evidence for each biomarker with 95% confidence intervals from the most recent, up-to-date, and best quality review.

RESULTS

From 3360 citations, we included 75 systematic reviews (88 biomarkers, 191,792 women). Most reviews (50/75, 67%) were moderate quality, but reported high heterogeneity (66/75, 88%). We identified 63 abnormal biomarkers in women with PCOS versus healthy controls. Of these, 22 core biomarkers could help evaluate the multisystemic impact of PCOS and inform patient management and surveillance: dehydroepiandrosterone, prolactin, sex hormone-binding globulin, total and free testosterone, anti-Mullerian hormone, systolic and diastolic blood pressure, c-reactive protein, fibrinogen, oral glucose tolerance test, homoeostatic model assessment-insulin resistance index, fasting insulin, total cholesterol, triglycerides, lipoprotein(a), HDL, LDL, non-HDL-cholesterol, ferritin, iron, and 25-hydroxy-vitamin D.

CONCLUSION

We identified 22 core biomarkers assessing the multisystemic impact of PCOS and inform its clinical management. Future research is required to establish validated healthcare pathways.

Effect of Vitamin D3 on Chemerin and Adiponectin Levels in Uterus of Polycystic Ovary Syndrome Rats

BACKGROUND

Polycystic ovary syndrome (PCOS) is an endocrine disorder with disrupted uterus structure and function. A positive effect of vitamin D3 (VD3) in female reproduction was observed. Chemerin (RARRES2) and adiponectin (ADIPOQ) are the main adipokines whose levels are altered in PCOS patients. Therefore, the aim of this study was to investigate the impact of VD3 supplementation on RARRES2 and ADIPOQ levels in the uterus of PCOS rats.

METHODS

We analyzed the plasma levels and uterine transcript and protein expression of RARRES2 and ADIPOQ and their receptors (CCRL2, CMKLR1, GPR1, and ADIPOR1 and ADIPOR2, respectively) in rats with letrozole-induced PCOS.

RESULTS

In control animals, VD3 did not change plasma levels of both adipokines, while in PCOS rats supplemented with VD3, they returned to control levels. The expression of RARRES2 and all investigated receptors increased in the uterus of VD3-treated rats; however, the levels of Rarres2 and Gpr1 genes remained unchanged. VD3 supplementation decreased RARRES2, CMKLR1, and GPR1 but increased CCRL2 level to the control value. In the uterus of VD3-treated rats, the transcript and protein levels of ADIPOQ and both receptors ADIPOR1 increased. At the same time, VD3 supplementation induced an increase in Adipoq, Adipor1, and Adipor2 gene expression and restored protein levels to control level values.

CONCLUSIONS

our findings indicate a new mechanism of VD3 action in the uterine physiology of PCOS rats.

Clinical Diagnostic Values of C1q/TNF-Related Protein-3 for Polycystic Ovary Syndrome Women with Insulin Resistance

Polycystic ovary syndrome (PCOS) is the most common disease caused by complex endocrine and metabolic abnormalities in women. Insulin resistance is considered an important pathophysiological factor in the pathogenesis of PCOS. Here we investigated the clinical values of C1q/TNF-related protein-3 (CTRP3) as predictive factor for insulin resistance. Our study included 200 patients with PCOS, among which 108 had insulin resistance. Serum CTRP3 levels were measured using enzyme-linked immunosorbent assay. Predictive values of CTRP3 for insulin resistance was analyzed using receiver operating characteristic (ROC) analysis. Correlations of CTRP3 to insulin levels, obesity measurements and blood lipid levels were determined using Spearman's correlation analysis. Our data suggested that PCOS patients with insulin resistance had a higher obesity, lower high-density lipoprotein cholesterol, higher total cholesterol, higher insulin levels and lower CTRP3 levels. CTRP3 had a high sensitivity (72.22%) and specificity (72.83%). CTRP3 significantly correlated to insulin levels, body mass index, waist-to-hip ratio, high-density lipoprotein, and total cholesterol levels. The predictive value of CTRP3 in PCOS patients with insulin resistance was supported by our data. Our findings suggest that CTRP3 is involved in the pathogenesis and insulin resistance of PCOS, which indicates its value as an indicator for the PCOS diagnosis.

Association of Insulin-Like Growth Factor-1 With Polycystic Ovarian Syndrome: A Systematic Review and Meta-analysis

OBJECTIVE

Circulating concentration of insulin-like growth factor (IGF)-1 in patients with polycystic ovary syndrome (PCOS) is still unclear. Therefore, we aimed to investigate the association of IGF-1 with PCOS through this meta-analysis.

METHODS

Literature search was conducted through PubMed, Embase, Web of Science, Cochrane Library, and China National Knowledge Infrastructure (up to July 2022). A manual search was performed on the references of related original research. Then, we applied the random-effects model to evaluate the overall effect size by calculating the standard mean difference and its 95% CI. Subgroup analyses were used to explore the sources of heterogeneity. In addition, a sensitivity analysis was performed and publication bias was assessed.

RESULTS

Twenty studies were included in this meta-analysis involving 657 individuals: 362 patients with PCOS and 295 normal controls. The results of meta-analysis showed that serum IGF-1 levels were significantly higher in patients with PCOS than in controls (standard mean difference, 0.89; 95% CI, 0.34-1.45; P = .002). The final pooled data were determined by the random-effects model because a significant high heterogeneity (I² = 89%) was found. A subgroup analysis based on body mass index showed that elevated IGF-1 level was associated with normal-weight and overweight patients in the PCOS group, but there was no significant association with obesity. The sensitivity analysis indicated that no individual study significantly affected the overall pooled result and no publishing bias was observed.

CONCLUSION

These data suggest that elevated serum IGF-1 levels may not be a major cause of PCOS pathogenesis. Body mass index may be a major determinant of serum IGF-1.

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.

Chemerin: A Functional Adipokine in Reproductive Health and Diseases

As a multifaceted adipokine, chemerin has been found to perform functions vital for immunity, adiposity, and metabolism through its three known receptors (chemokine-like receptor 1, CMKLR1; G-protein-coupled receptor 1, GPR1; C-C motif chemokine receptor-like 2, CCRL2). Chemerin and the cognate receptors are also expressed in the hypothalamus, pituitary gland, testis, ovary, and placenta. Accumulating studies suggest that chemerin participates in normal reproduction and underlies the pathological mechanisms of certain reproductive system diseases, including polycystic ovary syndrome (PCOS), preeclampsia, and breast cancer. Herein, we present a comprehensive review of the roles of the chemerin system in multiple reproductive processes and human reproductive diseases, with a brief discussion and perspectives on future clinical applications.

Association of circulating vaspin levels and patients with metabolic-associated fatty liver disease: a systematic review and meta-analysis

Background

The incidence rate of metabolic-associated fatty liver disease (MAFLD) is increasing annually; however, there are still no effective methods for establishing an early diagnosis and conducting real-time tracing. Vaspin can affect the metabolic processes in the body, and it is closely associated with many metabolic diseases. Many previous studies have speculated on the association between vaspin and MAFLD, but the results of these studies have not been conclusive. This meta-analysis examined the differences in circulating vaspin levels between patients with MAFLD and healthy individuals.

Methods

Six databases and other sources were searched with free terms and Medical Subject Headings terms, and a total of 13 articles were included (900 cases and 669 controls). RevMan 5.3 and Stata 16 were used for analysis. The standardised mean difference (SMD) and 95% confidence interval (CI) were used to assess the overall outcomes. Cohen’s kappa coefficient was applied to examine the differences between the two authors in the selection of studies and in the evaluation of the quality of evidence for the studies.

Results

The results demonstrated that there was no significant difference in the circulating vaspin levels between the MAFLD group and healthy group (SMD = 0.46, 95% CI: [− 0.12, 1.04]). The subgroup analysis suggested that area and body mass index (BMI) may be the sources of heterogeneity, and the results of univariate meta-regression analysis were consistent with those of the subgroup analysis (P = 0.005 and P < 0.001, respectively). Furthermore, BMI may better explain the source of heterogeneity (P = 0.032) in the multivariate meta-regression analysis.

Conclusion

In summary, no significant correlation was observed between the circulating vaspin levels and MAFLD. BMI may be an important factor affecting this correlation, which may provide a reference for further studies on mechanism and diagnosis of MAFLD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-022-01658-2.

High androgen concentrations in follicular fluid of polycystic ovary syndrome women

BACKGROUND

According to current definitions of Polycystic Ovary Syndrome (PCOS), hyperandrogenism is considered as a key element in the pathogenesis of this common endocrinopathy. However, until now, studies about ovarian androgen profile in women are very rare. Our aim was then to characterise the expression profile of the androgens in follicular fluid of 30 PCOS patients, and compare it to those of 47 Control women and 29 women with only polycystic ovary morphology on ultrasounds (ECHO group).

METHODS

A retrospective, single-centre cohort study was performed. The intrafollicular concentrations of the key androgens were assessed and correlated with the intrafollicular levels of some adipokines of interest. Androgens were quantified by mass spectrophotometry combined with ultra-high-performance liquid chromatography, while adipokine concentrations were measured by ELISA assays.

RESULTS

In PCOS patients, the intrafollicular concentrations of the androgens synthesised by ovarian theca cells, i.e., 17OH-pregnenolone, dehydroepiandrosterone, Δ4-androstenedione and testosterone, were significantly higher than those of the androgens of adrenal origin, and positively correlated with the main PCOS clinical and biological features, as well as with the adipokines mostly expressed in the follicular fluid of PCOS patients, i.e. resistin, omentin, chemerin and apelin. Conversely, Control women showed the highest levels of 17OH-progesterone, deoxycorticosterone and 11-deoxycortisol. Confirming these results, apelin levels were negatively associated with pregnenolone and deoxycorticosterone concentrations, while visfatin levels, which were higher in the Control group, negatively correlated with the Δ4-androstenedione and testosterone ones.

CONCLUSIONS

PCOS is characterised by a selective increase in the intrafollicular levels of the androgens synthesised by theca cells, strengthening the hypothesis that ovarian hyperandrogenism plays a central role in its pathogenesis. Further, the significant correlation between the intrafollicular concentrations of the androgens and most of the adipokines of interest, including apelin, chemerin, resistin and omentin, confirms the existence of a close relationship between these two hormonal systems, which appear deeply involved in ovarian physiology and PCOS physiopathology.

Progress of Adipokines in the Female Reproductive System: A Focus on Polycystic Ovary Syndrome

Adipose tissue, one type of loose connective tissue in the human body, maintains the primary task of energy storage. Adipose tissue is not only an energy reservoir but also plays a vital role as the largest endocrine organ of the whole body via releasing a variety of adipokines, which participate in many pathophysiological processes, such as energy metabolism regulation, glucose and lipid metabolism, and inflammation. Polycystic ovary syndrome (PCOS) is a disorder that mainly involves the female reproductive system, affecting women of childbearing age particularly. Insulin resistance (IR) and hyperandrogenemia (HA) have been implicated as a critical link involving the etiology and outcome of PCOS. A great deal of studies has bridged the gap between adipokines (such as Adiponectin, Chemerin, Metrnl, Apelin, Resistin, Visfatin, Leptin, Vaspin, Lipocalin 2, and Omentin) and reproductive fitness. In this review, we will focus on the adipokines' functions on PCOS and come up with some points of view on the basis of current research.

The Role of Glp-1 Receptor Agonists in Insulin Resistance with Concomitant Obesity Treatment in Polycystic Ovary Syndrome

Insulin resistance is documented in clamp studies in 75% of women with polycystic ovary syndrome (PCOS). Although it is not included in the diagnostic criteria of PCOS, there is a crucial role of this metabolic impairment, which along with hormonal abnormalities, increase each other in a vicious circle of PCOS pathogenesis. Insulin resistance in this group of patients results from defects at the molecular level, including impaired insulin receptor-related signaling pathways enhanced by obesity and its features: Excess visceral fat, chronic inflammation, and reactive oxygen species. While lifestyle intervention has a first-line role in the prevention and management of excess weight in PCOS, the role of anti-obesity pharmacological agents in achieving and maintaining weight loss is being increasingly recognized. Glucagon-like peptide-1 receptor agonists (GLP1-RAs) not only act by reducing body weight but also can affect the mechanisms involved in insulin resistance, like an increasing expression of glucose transporters in insulin-dependent tissues, decreasing inflammation, reducing oxidative stress, and modulating lipid metabolism. They also tend to improve fertility either by increasing LH surge in hypothalamus-pituitary inhibition due to estrogen excess connected with obesity or decreasing too high LH levels accompanying hyperinsulinemia. GLP1-RAs seem promising for effective treatment of obese PCOS patients, acting on one of the primary causes of PCOS at the molecular level.