Circulating resistin and follistatin levels in obese and non-obese women with polycystic ovary syndrome: A systematic review and meta-analysis

The Concentration of Follistatin and Activin A in Serum and Selected Biochemical Parameters in Women with Polycystic Ovary Syndrome: Stratification by Tobacco Smoke Exposure, Insulin Resistance, and Overweight/Obesity

Background/Objectives: The aim of the study was to investigate the concentrations of follistatin and activin A in the serum of women with polycystic ovary syndrome (PCOS) and to assess their relationship with selected biochemical parameters, specifically stratifying the analysis based on tobacco smoke, insulin resistance, and abnormal weight. Methods: The research was carried out within a cohort of 88 women (60 women with and 28 without PCOS). Results: We observed significant differences (p < 0.05) in follistatin concentrations between women with PCOS stratified by homeostatic model assessment for insulin resistance (HOMA-IR) values. These differences were consistent across both smoking and non-smoking subgroups with PCOS. Similar results were observed when comparing normal-weight women with PCOS to those with overweight or obesity. Additionally, activin A concentrations were significantly increased by higher body mass index (BMI) and HOMA-IR values in non-smoking women with PCOS. Moreover, we identified a negative correlation (r = -0.30; p < 0.023) between cotinine levels and Anti-Müllerian hormone. Among smoking women with PCOS, we noted decreased concentrations of sex hormone-binding globulin and high-density lipoproteins, alongside increased fasting glucose, insulin, HOMA-IR, and free androgen index values. Conclusions: Our findings suggest that activin A and follistatin concentrations are more strongly influenced by disruptions in glucose metabolism and BMI than by tobacco smoke exposure. The observed changes were more pronounced in follistatin than in activin A level.

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.

Androgens Modulate the Immune Profile in a Mouse Model of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is associated with a low-grade inflammation, but it is unknown how hyperandrogenism, the hallmark of PCOS, affects the immune system. Using a PCOS-like mouse model, it is demonstrated that hyperandrogenism affects immune cell populations in reproductive, metabolic, and immunological tissues differently in a site-specific manner. Co-treatment with an androgen receptor antagonist prevents most of these alterations, demonstrating that these effects are mediated through androgen receptor activation. Dihydrotestosterone (DHT)-exposed mice displayed a drastically reduced eosinophil population in the uterus and visceral adipose tissue (VAT). A higher frequency of natural killer (NK) cells and elevated levels of IFN-γ and TNF-α are seen in uteri of androgen-exposed mice, while NK cells in VAT and spleen displayed a higher expression level of CD69, a marker of activation or tissue residency. Distinct alterations of macrophages in the uterus, ovaries, and VAT are also found in DHT-exposed mice and can potentially be linked to PCOS-like traits of the model. Indeed, androgen-exposed mice are insulin-resistant, albeit unaltered fat mass. Collectively, it is demonstrated that hyperandrogenism causes tissue-specific alterations of immune cells in reproductive organs and VAT, which can have considerable implications on tissue function and contribute to the reduced fertility and metabolic comorbidities associated with PCOS.

Polycystic ovary syndrome

Despite affecting ~11-13% of women globally, polycystic ovary syndrome (PCOS) is a substantially understudied condition. PCOS, possibly extending to men's health, imposes a considerable health and economic burden worldwide. Diagnosis in adults follows the International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome, requiring two out of three criteria - clinical or biochemical hyperandrogenism, ovulatory dysfunction, and/or specific ovarian morphological characteristics or elevated anti-Müllerian hormone. However, diagnosing adolescents omits ovarian morphology and anti-Müllerian hormone considerations. PCOS, marked by insulin resistance and hyperandrogenism, strongly contributes to early-onset type 2 diabetes, with increased odds for cardiovascular diseases. Reproduction-related implications include irregular menstrual cycles, anovulatory infertility, heightened risks of pregnancy complications and endometrial cancer. Beyond physiological manifestations, PCOS is associated with anxiety, depression, eating disorders, psychosexual dysfunction and negative body image, collectively contributing to diminished health-related quality of life in patients. Despite its high prevalence persisting into menopause, diagnosing PCOS often involves extended timelines and multiple health-care visits. Treatment remains ad hoc owing to limited understanding of underlying mechanisms, highlighting the need for research delineating the aetiology and pathophysiology of the syndrome. Identifying factors contributing to PCOS will pave the way for personalized medicine approaches. Additionally, exploring novel biomarkers, refining diagnostic criteria and advancing treatment modalities will be crucial in enhancing the precision and efficacy of interventions that will positively impact the lives of patients.

Follistatin and follistatin-like 3 in metabolic disorders

Follistatin (FST) is a glycoprotein which main role is antagonizing activity of transforming growth factor β superfamily members. Folistatin-related proteins such as follistatin-like 3 (FSTL3) also reveal these properties. The exact function of them has still not been established, but it can be bound to the pathogenesis of metabolic disorders. So far, there were performed a few studies about their role in type 2 diabetes, obesity or gestational diabetes and even less in type 1 diabetes. The outcomes are contradictory and do not allow to draw exact conclusions. In this article we summarize the available information about connections between follistatin, as well as follistatin-like 3, and metabolic disorders. We also emphasize the strong need of performing further research to explain their exact role, especially in the pathogenesis of diabetes and obesity.

Relation of resistin gene variants to resistin plasma levels and altered susceptibility to polycystic ovary syndrome: A case control study

BACKGROUND

A role for resistin in the pathogenesis of polycystic ovarian syndrome (PCOS) and related features were described for various ethnicities. As its expression is partly inherited, a role for RETN polymorphisms in regulating resistin levels and PCOS risk was shown, but with varied results.

AIM

To investigate the association of rs34124816 (-537A>C), rs1862513 (-420C>G), rs3219175 (-358G>A), rs3745367 (+299G>A), rs3745369 (+1263G>C), and rs1423096 (+4965C>T) RETN SNPs with PCOS.

METHODS

Study subjects included 583 women with PCOS, and 713 eumenorrheic women serving as controls. Genotyping was done by real-time PCR.

RESULTS

Higher minor allele frequency (MAF) of rs34124816, rs3219175, and rs3745369, and lower MAF of rs1862513 and rs1423096 were seen in PCOS cases. Reduced PCOS risk was found with rs3745367 minor-allele homozygotes and rs1423096 minor-allele homozygotes, while increased risk was linked with rs3745367 heterozygotes, and with rs3745369 heterozygotes and minor-allele homozygotes. While it did not reach statistical significance, serum resistin levels were elevated in PCOS cases than in control women and major-allele homozygotes of rs34124816 and rs1862513, and in rs1423096 minor-allele-containing carriers. Carriage of rs34124816 correlated positively with age and LH, whereas rs1862513 positively and rs3745367 negatively correlated with fasting glucose. Six-locus (rs34124816-rs1862513-rs3219175-rs3745367-rs3745369-rs1423096) haplotype analysis demonstrated a significant reduction in AGGGGG and a marked increase in AGGGCG haplotypes between cases and controls, thus assigning PCOS protective and susceptible nature to these haplotypes, respectively.

CONCLUSIONS

This study is the first to document the contribution of rs34124816 and rs1423096 RETN variants to the risk of PCOS. The varied association of RETN gene variants with PCOS suggests an ethnic contribution of RETN association with PCOS.

LncRNA NEAT1 and MALAT1 are involved in polycystic ovary syndrome pathogenesis by functioning as competing endogenous RNAs to control the expression of PCOS-related target genes

Accumulating evidence has shown an abnormal expression of several non-coding RNAs in ovarian tissues which might be closely linked with the pathogenesis of PCOS. The aim of this study was to identify competing endogenous (ce) RNA network: long non-coding RNA (lncRNA), microRNA (miRNA) and their target genes: androgen receptor (AR), follistatin (FST) and insulin receptor substrate-2 (IRS-2), which are relevant to PCOS, to underline the molecular pathogenesis of PCOS and assist in early diagnosis and treatment. Bioinformatic analysis was performed to retrieve a ceRNA network: [lncRNA (NEAT1 and MALAT1) - miRNA (miR-30a-5p and miR-30d-5p) - mRNA (AR, FST and IRS-2)] linked to PCOS. Expression of the selected RNAs was examined by qPCR in peripheral blood leukocytes obtained from 73 PCOS patients (41 obese and 32 non-obese) and 31 healthy controls. PCOS patients showed significantly higher expression levels of NEAT1, miR-30a-5p, AR, FST and IRS-2, with significantly lower expression levels of MALAT1 and miR-30d-5p relative to controls especially in obese versus non-obese patients. Receiver operating characteristic (ROC) curve analysis indicated that most of the selected RNAs could serve as potential early diagnostic markers for PCOS with the highest efficiency obtained upon combining NEAT1 and miR-30d-5p or MALAT1 and miR-30a-5p with either of PCOS target genes. Moreover, all addressed RNAs had been proved as potential predictors of PCOS. The obtained data of ceRNA network raised the possibility that NEAT1 overexpression may increase the expression levels of AR, FST and IRS-2 by sponging miR-30d-5p, while low expression of MALAT1 may allow higher expression of the above genes via increasing miR-30a-5p, suggesting their involvement in PCOS pathogenesis and promising role for future diagnosis and targeted therapy.

Disentangling the aetiological pathways between body mass index and site-specific cancer risk using tissue-partitioned Mendelian randomisation

BACKGROUND

Body mass index (BMI) is known to influence the risk of various site-specific cancers, however, dissecting which subcomponents of this heterogenous risk factor are predominantly responsible for driving disease effects has proven difficult to establish. We have leveraged tissue-specific gene expression to separate the effects of distinct phenotypes underlying BMI on the risk of seven site-specific cancers.

METHODS

SNP-exposure estimates were weighted in a multivariable Mendelian randomisation analysis by their evidence for colocalization with subcutaneous adipose- and brain-tissue-derived gene expression using a recently developed methodology.

RESULTS

Our results provide evidence that brain-tissue-derived BMI variants are predominantly responsible for driving the genetically predicted effect of BMI on lung cancer (OR: 1.17; 95% CI: 1.01-1.36; P = 0.03). Similar findings were identified when analysing cigarettes per day as an outcome (Beta = 0.44; 95% CI: 0.26-0.61; P = 1.62 × 10-6), highlighting a possible shared aetiology or mediator effect between brain-tissue BMI, smoking and lung cancer. Our results additionally suggest that adipose-tissue-derived BMI variants may predominantly drive the effect of BMI and increased risk for endometrial cancer (OR: 1.71; 95% CI: 1.07-2.74; P = 0.02), highlighting a putatively important role in the aetiology of endometrial cancer.

CONCLUSIONS

The study provides valuable insight into the divergent underlying pathways between BMI and the risk of site-specific cancers.

Circulating follistatin concentrations in adolescent PCOS: Divergent effects of randomized treatments

PURPOSE

Follistatin is a glycoprotein that represses members of the transforming growth factor-β superfamily including activin. Higher follistatin levels have been associated with an increased risk for type 2 diabetes and with polycystic ovary syndrome (PCOS). In non-obese adolescent girls with PCOS, insulin sensitization results in a healthier endocrine-metabolic outcome than oral contraception (OC); we assessed whether those differences are underscored by changes in serum follistatin concentrations.

METHODS

Circulating follistatin, endocrine-metabolic markers and hepato-visceral fat were measured longitudinally in 72 girls with PCOS [age, 16 years; body mass index (BMI), 23 Kg/m²] randomized to receive PioFluMet [pioglitazone (7.5 mg/d), metformin (850 mg/d) and flutamide (62.5 mg/d), n=17]; EE-CA [an OC containing 35 µg ethinylestradiol (EE) and 2 mg cyproterone acetate (CA), n=17]; SPIOMET [Spironolactone (50 mg/d), pioglitazone (7.5 mg/d) and metformin (850 mg/d), n=18], or EE-LNG [an OC containing 20 µg EE and 100 mg levonorgestrel (LNG), n=20]. Twenty-eight age- and BMI-matched healthy girls served as controls.

RESULTS

Pre-treatment follistatin levels were similar in PCOS and controls. OCs raised serum follistatin after 6 months (6.8-fold vs 2.5-fold for EE-CA and EE-LNG, respectively). Neither SPIOMET nor PioFluMet changed follistatin levels. Follistatin correlated negatively with high-molecular weight adiponectin and positively with mean serum insulin concentrations during an oral glucose tolerance test at baseline, and with liver fat after 6 months.

CONCLUSION

In girls with PCOS, follistatin levels rise significantly after 6 months on OCs and this increase associates to a worsening of markers of insulin resistance and to changes in liver fat.

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 immune system's role in PCOS

Polycystic ovary syndrome (PCOS) is a common disorder of the endocrine system. Its main manifestations include oligo-ovulation, hyperandrogenism, and polycystic ovary morphology (PCOM), affecting women of childbearing age. Although the exact pathogenesis of this disease is still unknown, many factors, including genetic, endocrine, and metabolism disorders, play critical roles in its development. The immunopathogenesis of PCOS has not yet been studied in-depth, but it is hypothesized that immune system abnormalities may play a key role in it. Recent research has shown inflammation's effect on ovulation and ovarian follicular dynamics. Thus, it is suggested that there is a close association between PCOS and low-grade chronic systemic inflammation. As a result, chronic low-grade inflammation is identified as a significant factor in the pathogenesis and development of PCOS, which in turn leads to infertility. As a result, this article reviews PCOS immunopathology, evaluates long-standing hypotheses about the immune system's role in PCOS, and assesses the association between inflammatory factors and PCOS.

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.

Cardiometabolic biomarkers in women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age. Apart from the reproductive problems, PCOS is also associated with metabolic disturbances, and therefore, it also affects adolescents and postmenopausal women with PCOS as well as their offspring and other first-degree relatives. Adolescents with PCOS show unfavorable cardiometabolic biomarkers more often than controls, such as overweight/obesity and hyperandrogenism, and studies also suggest an unfavorable lipid profile. During reproductive age, women with PCOS develop additional cardiometabolic biomarkers, such as hypertension, insulin resistance, and metabolic syndrome. Growing evidence also supports the important role of inflammatory cytokines in cardiovascular health in these women. During menopausal transition, some PCOS characteristics ameliorate, whereas other biomarkers increase, such as body mass index, insulin resistance, type 2 diabetes, and hypertension. Offspring of women with PCOS have a lower birth weight and a higher body mass index later in life than controls. In addition, fathers, mothers, and siblings of women with PCOS show unfavorable cardiometabolic biomarkers. Therefore, cardiovascular screening and follow-up of women with PCOS and their offspring and siblings are of utmost importance.