Adipocyte resistin mRNA levels are down-regulated by laparoscopic ovarian electrocautery in both obese and lean women with polycystic ovary syndrome

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

A body of studies has examined the circulating concentration of adipokines including apelin, vapin, resistin, and chemerin in polycystic ovary syndrome (PCOS) patients. However, their findings have been inconclusive. Therefore, we systematically reviewed available studies to illuminate the overall circulating concentration of adipokines in PCOS subjects. Cochrane's Library, PubMed, Scopus, and ISI Web of Science databases were searched from the earliest available date up to April 2021 for relevant articles. The quality of each study was assessed by the Newcastle-Ottawa Quality Assessment Scale. The pooled effect size was estimated based on the random effects model, and the standard mean differences (SMD) with a 95% confidence interval (CI) were reported. A total of 88 studies met the inclusion criteria and were included in the current systematic review and meta-analysis. The results of the analysis showed that serum levels of vaspin (SMD 0.69; 95% CI, 0.22 to 1.17; P = 0.004; I² = 90.6%), chemerin (SMD 1.87; 95% CI, 1.35 to 2.40; P < 0.001; I² = 94.4%), and resistin (SMD 0.66; 95% CI, 0.41 to 0.91; P < 0.001; I² = 92.6%) were significantly higher in the PCOS group compared to controls. However, there was no significant difference between the PCOS and control groups in relation to apelin levels (SMD - 0.17; 95% CI, - 1.06 to 0.73; P = 0.714; I² = 97.8%). We found that serum levels of vaspin, chemerin, and resistin were significantly higher in PCOS subjects compared with controls. It seems that these adipokines can be measured as a useful marker to predict the development of PCOS.

Recent Update on the Molecular Mechanisms of Gonadal Steroids Action in Adipose Tissue

The gonadal steroids, including androgens, estrogens and progestogens, are involved in the control of body fat distribution in humans. Nevertheless, not only the size and localization of the fat depots depend on the sex steroids levels, but they can also highly affect the functioning of adipose tissue. Namely, the gonadocorticoids can directly influence insulin signaling, lipid metabolism, fatty acid uptake and adipokine production. They may also alter energy balance and glucose homeostasis in adipocytes in an indirect way, e.g., by changing the expression level of aquaglyceroporins. This work presents the recent advances in understanding the molecular mechanism of how the gonadal steroids influence the functioning of adipose tissue leading to a set of detrimental metabolic consequences. Special attention is given here to highlighting the sexual dimorphism of adipocyte functioning in terms of health and disease. Particularly, we discuss the molecular background of metabolic disturbances occurring in consequence of hormonal imbalance which is characteristic of some common endocrinopathies such as the polycystic ovary syndrome. From this perspective, we highlight the potential drug targets and the active substances which can be used in personalized sex-specific management of metabolic diseases, in accord with the patient's hormonal status.

Molecular Mechanisms of Laparoscopic Ovarian Drilling and Its Therapeutic Effects in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a common endocrinopathy, characterized by chronic anovulation, hyperandrogenism, and multiple small subcapsular cystic follicles in the ovary during ultrasonography, and affects 5–10% of women of reproductive age. PCOS is frequently associated with insulin resistance (IR) accompanied by compensatory hyperinsulinemia and, therefore, presents an increased risk of type 2 diabetes mellitus (DM). The pathophysiology of PCOS is unclear, and many hypotheses have been proposed. Among these hypotheses, IR and hyperandrogenism may be the two key factors. The first line of treatment in PCOS includes lifestyle changes and body weight reduction. Achieving a 5–15% body weight reduction may improve IR and PCOS-associated hormonal abnormalities. For women who desire pregnancy, clomiphene citrate (CC) is the front-line treatment for ovulation induction. Twenty five percent of women may fail to ovulate spontaneously after three cycles of CC treatment, which is called CC-resistant PCOS. For CC-resistant PCOS women, there are many strategies to improve ovulation rate, including medical treatment and surgical approaches. Among the various surgical approaches, one particular surgical method, called laparoscopic ovarian drilling (LOD), has been proposed as an alternative treatment. LOD results in an overall spontaneous ovulation rate of 30–90% and final pregnancy rates of 13–88%. These benefits are more significant for women with CC-resistant PCOS. Although the intra- and post-operative complications and sequelae are always important, we believe that a better understanding of the pathophysiological changes and/or molecular mechanisms after LOD may provide a rationale for this procedure. LOD, mediated mainly by thermal effects, produces a series of morphological and biochemical changes. These changes include the formation of artificial holes in the very thick cortical wall, loosening of the dense and hard cortical wall, destruction of ovarian follicles with a subsequently decreased amount of theca and/or granulosa cells, destruction of ovarian stromal tissue with the subsequent development of transient but purulent and acute inflammatory reactions to initiate the immune response, and the continuing leakage or drainage of “toxic” follicular fluid in these immature and growth-ceased pre-antral follicles. All these factors contribute to decreasing local and systemic androgen levels, the following apoptosis process with these pre-antral follicles to atresia; the re-starting of normal follicular recruitment, development, and maturation, and finally, the normalization of the “hypothalamus–pituitary–ovary” axis and subsequent spontaneous ovulation. The detailed local and systematic changes in PCOS women after LOD are comprehensively reviewed in the current article.

Involvement of Novel Adipokines, Chemerin, Visfatin, Resistin and Apelin in Reproductive Functions in Normal and Pathological Conditions in Humans and Animal Models

It is well known that adipokines are endocrine factors that are mainly secreted by white adipose tissue. Their central role in energy metabolism is currently accepted. More recently, their involvement in fertility regulation and the development of some reproductive disorders has been suggested. Data concerning the role of leptin and adiponectin, the two most studied adipokines, in the control of the reproductive axis are consistent. In recent years, interest has grown about some novel adipokines, chemerin, visfatin, resistin and apelin, which have been found to be strongly associated with obesity and insulin-resistance. Here, we will review their expression and role in male and female reproduction in humans and animal models. According to accumulating evidence, they could regulate the secretion of GnRH (Gonadotropin-Releasing Hormone), gonadotropins and steroids. Furthermore, their expression and that of their receptors (if known), has been demonstrated in the human and animal hypothalamo-pituitary-gonadal axis. Like leptin and adiponectin, these novel adipokines could thus represent metabolic sensors that are able to regulate reproductive functions according to energy balance changes. Therefore, after investigating their role in normal fertility, we will also discuss their possible involvement in some reproductive troubles known to be associated with features of metabolic syndrome, such as polycystic ovary syndrome, gestational diabetes mellitus, preeclampsia and intra-uterine growth retardation in women, and sperm abnormalities and testicular pathologies in men.

Distinct Response of Fat and Gastrointestinal Tissue to Glucose in Gestational Diabetes Mellitus and Polycystic Ovary Syndrome

Gestational diabetes mellitus (GDM) and polycystic ovary syndrome (PCOS) are distinct pathologies with impaired insulin sensitivity as a common feature. The aim of this study was to evaluate the response of fat tissue adipokines and gastrointestinal incretins to glucose load in patients diagnosed with one of the two disorders and to compare it with healthy controls. Oral glucose tolerance test (oGTT) was performed in 77 lean young women: 22 had positive history of GDM, 19 were PCOS patients, and 36 were healthy controls. Hormones were evaluated in fasting and in 60 min intervals during the 3 h oGTT using Bio-Plex ProHuman Diabetes 10-Plex Assay for C-peptide, ghrelin, GIP, GLP1, glucagon, insulin, leptin, total PAI1, resistin, visfatin and Bio-Plex ProHuman Diabetes Adipsin and Adiponectin Assays (Bio-Rad). Despite lean body composition, both PCOS and GDM women were more insulin resistant than controls. Significant postchallenge differences between the GDM and PCOS groups were observed in secretion of adipsin, leptin, glucagon, visfatin, ghrelin, GIP, and also GLP1 with higher levels in GDM. Conversely, PCOS was associated with the highest resistin, C-peptide, and PAI1 levels. Our data suggest that decreased insulin sensitivity observed in lean women with GDM and PCOS is associated with distinct hormonal response of fat and gastrointestinal tissue to glucose load.

Validity of adiponectin-to-leptin and adiponectin-to-resistin ratios as predictors of polycystic ovary syndrome

OBJECTIVE

To evaluate the association of changes in adipokine ratios with polycystic ovary syndrome (PCOS) and related features as altered levels of the adipokines adiponectin, leptin, and resistin were linked with the pathogenesis of PCOS.

DESIGN

Case-control retrospective study.

SETTING

Outpatient obstetrics/gynecology and adult endocrinology clinics.

PATIENT(S)

Unrelated women with PCOS (n = 211) and age-matched control women (n = 215).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Utility of adiponectin/leptin and adiponectin/resistin ratios as potential biomarkers of PCOS and associated features.

RESULT(S)

Significant differences in adiponectin but not leptin or resistin serum levels were seen between women with PCOS and control women. Ratios of adiponectin/leptin and adiponectin/resistin, but not leptin/resistin ratios, were statistically significantly different between PCOS cases and control women. Receiver operated characteristics area under the curve demonstrated sensitivity and specificity for adiponectin/leptin and adiponectin/resistin but not leptin/resistin ratios or individual adipokines as predictors of PCOS. Adiponectin/leptin and adiponectin/resistin ratios negatively correlated with body mass index, homeostatic model assessment, insulin resistance, and free insulin, testosterone, and sex hormone-binding globulin. In addition, adiponectin/resistin ratio negatively correlated with menarche.

CONCLUSION(S)

Ratios of adiponectin/leptin and adiponectin/resistin constitute novel predictor factors to explain PCOS and associated features and thus may present target for novel therapeutics in PCOS.

Visfatin and resistin serum levels in normal-weight and obese women with polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy among women of reproductive age that is linked to insulin resistance and obesity. While studies have shown that plasma levels of resistin and visfatin increase with obesity, the association between PCOS and these markers has not been described well.

OBJECTIVES

This case-control study aimed to compare the serum levels of visfatin and resistin in women with PCOS in comparison with the healthy controls matched for age and body mass index (BMI).

PATIENTS AND METHODS

A total of 80 women consisted of 40 women with PCOS and 40 matched eumenorrheic women without hyperandrogenism enrolled in the study. They were subcategorized into obese and normal-weight women according to their BMI. Serum visfatin and resistin levels were assessed using sandwich enzyme-linked Immunosorbent assay (ELISA).

RESULTS

Serum levels of resistin were higher among both obese and normal-weight women with PCOS in comparison with the controls (2.36 and 1.58 ng/mL in normal-weight women with PCOS and controls, respectively; and 2.10 and 1.91 ng/mL in obese women with PCOS and controls, respectively). Serum visfatin levels was higher in both obese women with PCOS and controls (3.46 and 3.49 ng/mL PCOS and control groups, respectively) in comparison with normal-weight women in both groups (3.16 and 3.15 in PCOS and control groups, respectively); however; there were no statistically significant differences in serum resistin and visfatin levels between PCOS and control groups (P > 0.05).

CONCLUSIONS

While the expression of visfatin and resistin may be upregulated in women with PCOS, it is not translated at serum level.

Adipokines in reproductive function: a link between obesity and polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy associated with infertility and metabolic disorder in women of reproductive age. Dysfunction of adipose tissue has been implicated in the pathophysiology of PCOS. Increasing evidence shows that the dysregulated expression of adipokines, the secreted products of adipose tissue, plays an important role in the pathology of PCOS. Here, we review the role of several identified adipokines that may act as a link between obesity and PCOS. PCOS also reciprocally influences the profile of adipokines. Insight into the underlying mechanisms will help better understand the pathology of PCOS and identify new therapeutic targets of this syndrome.

Androgens and polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a mainly hyperandrogenic disorder and is possibly the most frequent endocrinopathy in premenopausal women. Androgen excess is the primary defect in PCOS, because ovarian theca cells secrete increased amounts of androgens even after several passes in primary culture. Excessive androgen amounts might favor the visceral deposition of body fat in affected women, resulting in insulin resistance, compensatory hyperinsulinism and further androgen excess. This vicious circle starts early during life in women with PCOS, even during fetal development, manifests clinically during puberty and does not end after menopause. All the steps in the vicious circle contribute to the association of PCOS with metabolic dysfunction and cardiovascular risk factors. Fortunately, most, if not all, of the therapeutic strategies currently in use for the management of PCOS, including lifestyle modification and diet, oral contraceptives, antiandrogens and insulin sensitizers, may ameliorate androgen excess and its long-term consequences.

The plasma level and gene expression of resistin in polycystic ovary syndrome

OBJECTIVES

To investigate the relationship between plasma resistin, polycystic ovary syndrome (PCOS), and insulin resistance (IR). To compare the mRNA level of resistin in mononuclear cells and monocyte-derived macrophages in women with PCOS and controls.

MATERIALS AND METHODS

Patients with PCOS and controls were enrolled and IR was considered as the stratified factor for subgroups. Fasting blood was collected to determine the levels of sex hormones, insulin, glucose, blood lipid, and resistin. Resistin gene expression was evaluated by quantitative real-time RT-PCR in mononuclear cells and monocyte-derived macrophages cultured with or without rosiglitazone for 96 h.

RESULTS

No significant difference of plasma resistin levels was found among PCOS-IR, PCOS-non-IR, control-IR, and control-non-IR groups. There were no significant differences in resistin mRNA expression between participants with and without PCOS and with and without IR. Resistin mRNA expression in monocyte-derived macrophages was higher than that in mononuclear cells (p = 0.04), and could be reduced by rosiglitazone (p < 0.001).

CONCLUSIONS

Plasma resistin does not correlate with normal weight PCOS or IR. Resistin gene expression in mononuclear cells and monocyte-derived macrophages in PCOS and IR is the same as controls. Further researches on the role of resistin in the pathogenesis of PCOS or IR should concentrate on the tissue level.

Adipokines: new emerging roles in fertility and reproduction

Adipose tissue is a specialized endocrine and paracrine organ producing specific factors called adipokines. It is well known that adipokines balance is fundamental to prevent obesity, metabolic syndrome, and cardiovascular diseases. During the last years, new roles of adipokines have been emerging in the field of fertility and reproduction. Although the literature is still quite controversial, this review serves to resume current knowledge on this topic. Alterations in adipokine levels or in their mechanism of action are associated with fertility impairment and pregnancy diseases, as well as with obesity, metabolic syndrome, and cardiovascular diseases. Normal levels of adipokines are fundamental to maintain integrity of hypothalamus-pituitary-gonadal axis, regular ovulatory processes, successful embryo implantation, and physiologic pregnancy. More efforts are needed to understand the mechanisms and to the extent to which adipokine changes are involved in the impairment of fertility and pregnancy outcome, to find possible medical treatments.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians Learning Objectives: After completion of this educational activity, the obstetrician/gynecologist should be better able to demonstrate current knowledge in the research field of adipokines in fertility and reproduction; evaluate the central role of metabolism balance in good pregnancy outcome; and apply new perspectives of studies.

Human mammary fibroblasts stimulate invasion of breast cancer cells in a three-dimensional culture and increase stroma development in mouse xenografts

INTRODUCTION

Tumour phenotype is regulated in a complex fashion as a result of interactions between malignant cells and the tumour stroma. Fibroblasts are the most abundant and perhaps most active part of the tumour stroma. A better understanding of the changes that occur in fibroblasts in response to the presence of malignant cells may lead to the development of new strategies for cancer treatment. We explored the effects of fibroblasts on the growth and invasion of mammary carcinoma tumour cells in vitro and in vivo.

METHODS

In order to analyse secreted factors that affect invasive abilities of breast cancer cells we co-cultured human mammary fibroblasts (HMF3s) and cancer cells (MCF7S1) in three-dimensional (3D) growth conditions devoid of heterogeneous cell-cell contact. To study the possible influence of fibroblasts on MCF7S1 cancer cell growth in vivo we co-injected HMF3s and MCF7S1 cells in Balb/c nu/nu mice.

RESULTS

In 3D co-culture both HMF3s and MCF7S1 cells demonstrated enhanced invasion into a Matrigel matrix. This was correlated with enhanced expression of the metastasis promoting S100A4 protein in fibroblasts, stimulation of the matrix metalloproteinase (MMP)-2 activity, and enhanced secretion of a range of different cytokines. Orthotopic injection of oestrogen-dependent MCF7S1 cancer cells together with fibroblasts showed stimulation of tumour growth in mice without an external oestrogen supply. The resulting tumours were characterized by increased development of extracellular matrix, as well as an increase of murine S100A4 concentration and activity of MMP-2 in the tumour interstitial fluid.

CONCLUSION

Stimulation of the invasive phenotype of tumour cells in 3D co-cultures with fibroblasts could be correlated with increased production of S100A4 and MMP-2. We propose that enhanced development of mouse host-derived tumour stroma in a MCF7S1 co-injection xenograft model leads to oestrogen independency and is triggered by the initial presence of human fibroblasts.

The expression of resistin in adipose tissues of patients with polycystic ovary syndrome and insulin resistance

The relationship between the expression of resistin in polycystic ovary syndrome (PCOS) and insulin resistance was investigated. The plasma resistin concentrations in 35 patients with PCOS and 40 controls were measured by ELISA. Luteinizing hormone (LH), follicle-stimulating hormone (FSH), and fasting insulin (FIN) were tested by radioimmunoassay. Insulin resistance index (HOMA-IR) was calculated. Fasting plasma glucose (FPG) was determined by oxidase test. Western blot and reverse transcriptase PCR (RT-PCR) methods were used to detect the expression of resistin in adipose tissues. The levels of plasma resistin, LH, LH/FSH and FIN and HOMA-IR in patients with PCOS were significantly higher than those in control group (all P<0.05). Plasma resistin was correlated positively with FPG, FIN, HOMA-IR, LH and LH/FSH (r=0.56, 0.60, 0.65, 0.48, and 0.42 respectively). Resistin protein and mRNA expression levels in patients with PCOS were significantly higher than those in normal tissues (all P<0.01). It was concluded that resistin might be involved in the pathogenesis of insulin resistance of PCOS.

Polycystic ovarian syndrome: pathophysiology, molecular aspects and clinical implications

Polycystic ovarian syndrome (PCOS) is universally recognised as the commonest endocrinopathy of women. The definition and the aetiological hypotheses of PCOS are continuously evolving to accommodate expanding knowledge on the syndrome, which is now known to be more complex than purely a reproductive disorder. Increased androgen synthesis, disrupted folliculogenesis and insulin resistance lie at the pathophysiological core of PCOS. An intriguing concept involves the perpetuation of a vicious circle with endocrine/reproductive and metabolic components. An unfavourable metabolic environment may unmask genetic traits of ovarian dysfunction, and the unfolding endocrine derangement could further aggravate the metabolic disarray. This article reviews the molecular mechanisms known to underlie the ovarian and metabolic abnormalities characterising PCOS. The putative interdependence between reproductive and metabolic aspects of PCOS, and therapeutic implications for the management of PCOS, are also discussed.