Assessment of serum chemerin, vaspin and omentin-1 levels in patients with polycystic ovary syndrome

Serum Chemerin Levels Correlate With Severity of Dysglycemia in Young Adult Women With Polycystic Ovary Syndrome

Context

A subset of polycystic ovary syndrome (PCOS) individuals also have type 2 diabetes (T2D); an unmet need to identify this subgroup exists.

Objective

We looked at the potential role of serum chemerin, a proinflammatory adipokine, in identifying dysglycemic PCOS.

Methods

A total of 93 PCOS and 33 healthy controls were classified, based on fasting and 2-hour plasma glucose levels (2hPGPG) and glycated hemoglobin A1c (HbA1c) (%) into normoglycemic (n = 34), dysglycemic (n = 33), and T2D (n = 26). Serum chemerin were measured by enzyme-linked immunosorbent assay. Homeostatic model 2 assessment of insulin resistance (HOMA-2IR) and homeostatic model 2 assessment of β-cell function (HOMA-2β) were computed using serum C-peptide.

Results

Metabolic syndrome was present in 9.7% (National Cholesterol Education Program) of PCOS. Waist circumference, body fat (%), 2hPGPG, and HbA1c levels were significantly higher in T2D group. Serum triglycerides/high-density lipoprotein cholesterol (TGs/HDL-c) ratio was increased in PCOS individuals with T2D; no significant changes in total cholesterol and LDL-c levels were seen. Serum chemerin levels were significantly higher (P < .001) in the PCOS group. Total body fat (%), 2hPGPG, HbA1c, and TG/HDL-c ratio correlated positively with chemerin levels. Serum chemerin levels correlated positively with HOMA2IR and negatively with HOMA-2β. On receiver operating characteristic curve analysis, a serum chemerin cutoff level of greater than 309.3 ng/mL differentiated PCOS individuals with dysglycemia from those without (sensitivity 85.71%, specificity 89.47%). The Cohen kappa test revealed a substantial agreement (P < .001) between chemerin cutoff and 2hPGPG levels greater than 200 mg/dL. The present study is arguably the first ever to define a serum chemerin cutoff to distinguish PCOS individuals with T2D from those without.

Conclusion

Elevated serum chemerin levels reliably identify PCOS individuals with dysglycemia. Further, longitudinal studies with larger samples are required to confirm this association.

Review of Novel Potential Insulin Resistance Biomarkers in PCOS Patients—The Debate Is Still Open

Research on proteins and peptides that play roles in metabolic regulation, which may be considered potential insulin resistance markers in some medical conditions, such as diabetes mellitus, obesity and polycystic ovarian syndrome (PCOS), has recently gained in interest. PCOS is a common endocrine disorder associated with hyperandrogenemia and failure of ovulation, which is often accompanied by metabolic abnormalities, including obesity, dyslipidemia, hyperinsulinemia, and insulin resistance. In this review, we focus on less commonly known peptides/proteins and investigate their role as potential biomarkers for insulin resistance in females affected by PCOS. We summarize studies comparing the serum fasting concentration of particular agents in PCOS individuals and healthy controls. Based on our analysis, we propose that, in the majority of studies, the levels of nesfastin-1, myonectin, omentin, neudesin were decreased in PCOS patients, while the levels of the other considered agents (e.g., preptin, gremlin-1, neuregulin-4, xenopsin-related peptide, xenin-25, and galectin-3) were increased. However, there also exist studies presenting contrary results; in particular, most data existing for lipocalin-2 are inconsistent. Therefore, further research is required to confirm those hypotheses, as well as to elucidate the involvement of these factors in PCOS-related metabolic complications.

Circulating apelin and chemerin levels in patients with polycystic ovary syndrome: A meta-analysis

BACKGROUND

Polycystic ovary syndrome (PCOS) is one of the most common gynecological endocrine disorders. Apelin and chemerin are newly identified adipokines, which are higher in obesity and diabetes. Studies have found that the serum apelin and chemerin levels in patients with PCOS are significantly increased. However, other studies showed the opposite results. Therefore, the relationship between those two adipokines and PCOS is still controversial.

AIM

This meta-analysis was conducted to statistically evaluate the apelin and chemerin levels of patients with PCOS.

METHODS

We searched the Web of Science, Embase, PubMed, and Google Scholar databases for potential studies. "Polycystic ovary syndrome" or "PCOS" in combination with the terms "apelin" or "chemerin" were used as keywords search titles or abstracts. The publication period examined was between 1990 and 2021. Standardized mean differences (SMD) with corresponding 95% confidence intervals (CIs) were determined as the results of the meta-analysis.

RESULTS

A total of 148 articles were initially retrieved, and 18 qualified articles were finally obtained through preliminary screening and quality evaluation. The publications together contain 1,265 cases and 894 controls. The results of the meta-analysis showed that the circulating chemerin levels in patients with PCOS were significantly higher than those in the controls (SMD: 0.79, 95% CI [0.36, 1.23]), and there was no significant difference in circulating apelin between patients with PCOS and controls (SMD: 0.57, 95% CI [-0.21, 1.35]).

CONCLUSIONS

This meta-analysis is the first to evaluate circulating apelin and chemerin levels in patients with PCOS. Our findings suggest that circulating chemerin levels of patients with PCOS are significantly higher than those of healthy controls.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=218316, identifier CRD42020218316.

Circulating chemerin levels in women with polycystic ovary syndrome: a meta-analysis

OBJECTIVE

The present meta-analysis was conducted to investigate the association between circulating chemerin levels and polycystic ovary syndrome (PCOS) in women.

METHODS

Relevant studies published up to May 2020 were searched from PubMed, Ovid, the Cochrane Library, and Clinical Trial Database. A random effects model was used to measure the strength of association between PCOS and chemerin by using the standardized mean difference (SMD) and 95% confidence interval (CI). All data were analyzed using Stata 12.0 (version 12; Stata-Corp, College Station, TX).

RESULTS

The final meta-analysis included eight studies with 15 results including a total of 897 participants (524 patients with PCOS and 373 controls). The circulating chemerin levels were higher in patients with PCOS (random effects SMD = 1.07; 95% CI: 0.55-1.59; p < .001) than in controls. However, considerable heterogeneity across studies was not eliminated in subgroup analyses. The meta-regression analysis further suggested that region is the main source of heterogeneity (p = .001).

CONCLUSIONS

Our meta-analysis indicated that women with PCOS have significantly higher circulating chemerin levels than in healthy women, indicating that chemerin may be involved in the pathogenesis of PCOS.

Serum and follicular fluid chemerin and chemerin mRNA expression in women with polycystic ovary syndrome: Systematic review and meta-analysis

Introduction

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders among women of reproductive age. Chemerin, a novel adipokine, is involved in inflammation, energy metabolism, adipogenesis, angiogenesis and insulin secretion in the adipose cells and ovary. This systematic review with meta‐analysis aimed to compare serum and follicular fluid (FF) chemerin and ovarian chemerin mRNA expression among women with PCOS and non‐PCOS.

Methods

Electronic databases including Web of Science, PubMed, Google Scholar, Scopus, Cochrane and CINAHL were used for a comprehensive search through April 2021. Of the 174 articles initially identified, 22 studies met the eligibility criteria. A random‐effects model with a weighted mean difference (WMD) and 95% confidence interval (CI) was performed to compare the outcomes between groups. Subgroup and sensitivity analyses were performed to detect the sources of heterogeneity.

Results

Women with PCOS compared to without PCOS showed significantly higher serum chemerin [WMD: 12.02 pg/ml (95% CI: [10.92, 13.13]), p < .001], chemerin mRNA expression [WMD: 0.38% (95% CI [0.25, 0.52]), p = .001] and FF chemerin [(WMD): 41.7 pg/ml (95% CI [17.89, 65.5]) p < .001]. Further, serum chemerin remained high in PCOS women even with subgroup analysis based on body mass index (BMI) or sample size (p < .001). Serum chemerin was higher in women with PCOS and higher BMI [(WMD): 3.29 pg/ml (95% CI: [2.73, 3.384]), p < .001]. The expression of chemerin mRNA was significantly higher in the PCOS group compared to the control group [WMD: 0.38% (95% CI [0.25, 0.52]), p < .001].

Conclusion

Serum and FF chemerin and mRNA expression were higher in the PCOS group compared to the controls. Further, serum chemerin was higher in PCOS women with higher BMI compared to lower BMI. The present findings illustrate that chemerin may be associated with PCOS status and BMI, independently.

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.

Predictive value of serum and follicular fluid chemerin concentrations during assisted reproductive cycles in women with polycystic ovary syndrome

AIMS

To evaluate the effect of serum and follicular fluid (ff) Chemerin levels on Assisted Reproductive Technology (ART) outcomes in lean patients with PCOS.

MATERIALS AND METHODS

The study included 76 infertile reproductive aged women, between 21-35 years who underwent intracytoplasmic sperm injection (ICSI) procedure. Serum and ff Chemerin levels were evaluated. Fertilization and clinical pregnancy rate were compared between the groups.

RESULTS

Serum (13.32 ng/ml versus 29.82 ng/ml) and ff chemerin (35.90 ng/ml versus 87.60 ng/ml) levels were significantly higher in lean PCOS patients compared to controls (p < .01). Serum (24.5 ng/ml versus 18.4 ng/ml) and ff chemerin (71.7 ng/ml versus 52.8 ng/ml) levels were higher in subjects without clinical pregnancy compared to the subjects with clinical pregnancy (p < .05). A cutoff value of 36.2 ng/ml in the ff chemerin level was found to estimate clinical pregnancy with 83% sensitivity and 52% specificity (Area under the curve 0.66; 95% confidence interval, 0.53-0.79). A cutoff value of 12.7 ng/ml in the serum chemerin level was found to estimate clinical pregnancy with 91% sensitivity and 49% specificity (Area under the curve 0.65; 95% confidence interval, 0.52-0.78). Clinical pregnancy rates were significantly higher in group with lower serum chemerin levels (80.0% versus 30.4%, p < .001). High serum chemerin levels are associated with failure of assisted reproduction [OR:0.1(95% CI, 0.03-0.4, p < .001)].

CONCLUSIONS

PCOS is associated with higher serum and ff chemerin levels and high serum chemerin level is a risk factor for failed ART cycle.

Review: Vaspin (SERPINA12) Expression and Function in Endocrine Cells

Proper functioning of the body depends on hormonal homeostasis. White adipose tissue is now known as an endocrine organ due to the secretion of multiple molecules called adipokines. These proteins exert direct effects on whole body functions, including lipid metabolism, angiogenesis, inflammation, and reproduction, whereas changes in their level are linked with pathological events, such as infertility, diabetes, and increased food intake. Vaspin-visceral adipose tissue-derived serine protease inhibitor, or SERPINA12 according to serpin nomenclature, is an adipokine discovered in 2005 that is connected to the development of insulin resistance, obesity, and inflammation. A significantly higher amount of vaspin was observed in obese patients. The objective of this review was to summarize the latest findings about vaspin expression and action in endocrine tissues, such as the hypothalamus, pituitary gland, adipose tissue, thyroid, ovary, placenta, and testis, as well as discuss the link between vaspin and pathologies connected with hormonal imbalance.

Adipocyte and steroidogenic cell cross-talk in polycystic ovary syndrome

BACKGROUND

Metabolic and endocrine alterations in women with polycystic ovary syndrome (PCOS) affect adipose tissue mass and distribution. PCOS is characterised by hyperandrogenism, obesity and adipocyte dysfunction. Hyperandrogenism in PCOS drives dysfunctional adipocyte secretion of potentially harmful adipocytokines. Glucocorticoids and sex-steroids modulate adipocyte development and function. For their part, adipocyte products interact with adrenal and ovarian steroidogenic cells. Currently, the relationship between adipocyte and steroidogenic cells is not clear, and for these reasons, it is important to elucidate the interrelationship between these cells in women with and without PCOS.

OBJECTIVE AND RATIONALE

This comprehensive review aims to assess current knowledge regarding the interrelationship between adipocytes and adrenal and ovarian steroidogenic cells in animal models and humans with or without PCOS.

SEARCH METHODS

We searched for articles published in English and Portuguese in PubMed. Keywords were as follows: polycystic ovary syndrome, steroidogenesis, adrenal glands, theca cells, granulosa cells, adipocytes, adipocytokines, obesity, enzyme activation, and cytochrome P450 enzymes. We expanded the search into the references from the retrieved articles.

OUTCOMES

Glucocorticoids and sex-steroids modulate adipocyte differentiation and function. Dysfunctional adipocyte products play important roles in the metabolic and endocrine pathways in animals and women with PCOS. Most adipokines participate in the regulation of the hypothalamic-pituitary-adrenal and ovarian axes. In animal models of PCOS, hyperinsulinemia and poor fertility are common; various adipokines modulate ovarian steroidogenesis, depending on the species. Women with PCOS secrete unbalanced levels of adipocyte products, characterised by higher levels of leptin and lower levels of adiponectin. Leptin expression positively correlates with body mass index, waist/hip ratio and levels of total cholesterol, triglyceride, luteinising hormone, oestradiol and androgens. Leptin inhibits the production of oestradiol and, in granulosa cells, may modulate 17-hydroxylase and aromatase enzyme activities. Adiponectin levels negatively correlate with fat mass, body mass index, waist-hip ratio, glucose, insulin and triglycerides, and decrease androgen production by altering expression of luteinising hormone receptor, steroidogenic acute regulatory protein, cholesterol-side-chain cleavage enzyme and 17-hydroxylase. Resistin expression positively correlates with body mass index and testosterone, and promotes the expression of 17-hydroxylase enzyme in theca cells. The potential benefits of adipokines in the treatment of women with PCOS require more investigation.

WIDER IMPLICATIONS

The current data regarding the relationship between adipocyte products and steroidogenic cells are conflicting in animals and humans. Polycystic ovary syndrome is an excellent model to investigate the interrelationship among adipocyte and steroidogenic cells. Women with PCOS manifest some pathological conditions associated with hyperandrogenism and adipocyte products. In animals, cross-talk between cells may vary according to species, and the current review suggests opportunities to test new medications to prevent or even reverse several harmful sequelae of PCOS in humans. Further studies are required to investigate the possible therapeutic application of adipokines in women with obese and non-obese PCOS. Meanwhile, when appropriate, metformin use alone, or associated with flutamide, may be considered for therapeutic purposes.

Increased chemerin serum levels in hyperandrogenic and normoandrogenic women from Argentina with polycystic ovary syndrome

AIM

To assess serum chemerin levels and investigate the association of chemerin with the hyperandrogenic and normoandrogenic phenotypes of Polycystic Ovary Syndrome (PCOS) and with the metabolic status of the analyzed population.

MATERIAL AND METHODS

A cross-sectional study was conducted on 106 women with PCOS and 60 healthy controls from Argentina. Patients were classified as showing a hyperandrogenic or normoandrogenic phenotype. Participants underwent anthropometric and clinical evaluation and markers of cardiovascular risk, insulin resistance, metabolic syndrome (MS), and serum chemerin levels were assessed.

RESULTS

PCOS patients showed increased levels of chemerin. In adjusted models for age and body mass index (BMI), chemerin was associated with markers of metabolic status. The analysis of chemerin levels considering the cutoff values of BMI, homeostatic model of insulin sensitivity (HOMA-IR) and TG/HDL marker showed that PCOS patients always presented higher levels of chemerin than controls. PCOS group showed increased chemerin levels independently of the presence of MS.

CONCLUSION

PCOS patients always showed increased levels of chemerin independently of their phenotype and presence of overweight, as well as higher levels of chemerin than controls when considering the cutoff values of HOMA-IR and TG/HDL. Therefore, argentine women with PCOS display increased chemerin levels independently of their metabolic or androgenic status.

Pathophysiological roles of chronic low-grade inflammation mediators in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common hormonal imbalance disease in reproductive-aged women. Its basic characteristics are ovulatory dysfunction and ovarian overproduction of androgens that lead to severe symptoms such as insulin resistance, hirsutism, infertility, and acne. Notwithstanding the disease burden, its underlying mechanisms remain unknown, and no causal therapeutic exists. In recent years, further studies showed that inflammation processes are involved in ovulation and play a key role in ovarian follicular dynamics. Visceral adipose tissue can cause inflammatory response and maintenance of the inflammation state in adipocytes by augmented production of inflammatory cytokines, monocyte chemoattractant proteins, and recruitment of the immune cell. Therefore, the PCOS can be related to a low-grade inflammation state and inflammatory markers. Investigating the inflammatory processes and mediators that contribute to the commencement and development of PCOS can be a critical step for better understanding the pathophysiology of the disease and its treatment through inhibition or control of related pathways. In the present review, we discuss the pathophysiological roles of chronic low-grade inflammation mediators including inflammasome-related cytokines, interleukin-1β (IL-1β), and IL-18 in PCOS development.

Analysis of serum chemerin concentrations in psoriatic patients in relation to metabolic abnormalities

Introduction

Recent data depict psoriasis as a systemic disease with many comorbidities, especially metabolic syndrome and cardiovascular diseases. Chemerin, an adipokine secreted by adipose tissue cells, may prove to be an important link between psoriasis and its comorbidities.

Aim

Assessment of serum concentrations of chemerin in patients with psoriasis and the healthy control group as well as evaluation of a possible correlation between adipokine concentrations and selected psoriasis severity indices and metabolic syndrome components.

Material and methods

One hundred and two patients with diagnosed psoriasis and 40 healthy volunteers were enrolled in the study. In all subjects, serum chemerin concentrations and selected metabolic syndrome components including lipid and glucose levels were determined. Psoriasis severity was assessed using the PASI and BSA indices.

Results

A higher concentration of chemerin was demonstrated in the group of psoriasis patients compared to the control group (p < 0.05). A positive correlation between chemerin concentration and C-reactive protein concentration (p = 0.001), body mass index (p = 0.031) and triglyceride concentration (p = 0.043) was found. An inverse correlation with high-density lipoprotein cholesterol concentrations (p = 0.015) was also noted. Significantly higher concentrations of chemerin were observed in psoriatic patients with elevated low-density lipoptotein (LDL) cholesterol levels in comparison with patients with normal LDL values (p = 0.032). Chemerin concentrations were also significantly higher in patients with both psoriasis and elevated glucose levels compared to patients with normal blood glucose values (p = 0.043).

Conclusions

The results obtained suggest a possible role of chemerin as an adipokine linking psoriasis with metabolic syndrome.

Metabolic Cytokines at Fasting and During Macronutrient Challenges: Influence of Obesity, Female Androgen Excess and Sex

Scope: Cytokines have pleiotropic functions within the organism and their levels may be influenced by obesity, visceral adiposity and sex hormones. Diet composition may also affect their systemic concentrations during fasting and in the postprandial period. Hence, we studied the influence of sex steroids and obesity on the circulating levels of a panel of metabolic cytokines in the fasting state and after single macronutrient challenges. Methods: On alternate days we submitted 17 women with polycystic ovary syndrome (PCOS) (9 non-obese, 8 obese), 17 non-hyperandrogenic control women (9 non-obese, 8 obese) and 19 control men (10 non-obese, 9 obese) to isocaloric oral glucose, lipid and protein loads. Serum levels of omentin-1, vaspin, lipocalin-2, adipsin, PAI-1, chemerin, FGF-21 and FGF-23 were determined by Luminex multiplex technology. Results: During fasting, obese patients presented higher levels of PAI-1, chemerin and adipsin but decreased FGF-23 and omentin-1 compared with non-obese subjects. Vaspin showed sexual dimorphism with lower levels in men than women with PCOS and female controls. Following macronutrient ingestion, most metabolic cytokines presented a similar physiological response consisting of a decrease in circulating concentrations, which was inversely associated with the fasting levels of these molecules. Protein intake caused the major postprandial decrease whereas glucose did not significantly reduce PAI-1, FGF-23 and vaspin, and even increased FGF-21. Regardless of the macronutrient administered, vaspin levels showed a larger reduction in non-obese individuals while the decrease in PAI-1 was particularly noticeable in the obese subgroup. The postprandial reductions of omentin-1 and FGF-23 after glucose and protein loads were influenced by obesity. No major differences were found between patients with PCOS and male and female controls. Conclusions: Obesity, but not PCOS or sex, markedly influences metabolic cytokine levels at fasting and after macronutrient ingestion. The observed postprandial decrease in their circulating concentrations might represent a physiological compensatory mechanism against food-induced inflammation and oxidative stress. This mechanism is altered by obesity and is differently modulated by macronutrients, suggesting a larger contribution of glucose to stressful postprandial responses.

Polycystic ovary syndrome: possible involvement of androgen-induced, chemerin-mediated ovarian recruitment of monocytes/macrophages

Polycystic ovary syndrome (PCOS) is a continuum of endocrine and reproductive disorders characterized by hyperandrogenism, antral follicle growth arrest, and chronic inflammation. Macrophages play key role in inflammation, and the balance between M1 (inflammatory) and M2 (anti-inflammatory) macrophages determines physiological/pathological outcomes. Here, we investigated if hyperandrogenism increases ovarian chemerin altering the balance of M1 and M2 macrophages and the granulosa cell death. Ovarian chemerin was upregulated by 5α-dihydrotestosterone (DHT) in lean and overweight rats; while increased serum chemerin levels were only evident in overweight rats, suggesting that the serum chemerin may be reflective of a systemic response and associated with obesity, whereas increased ovarian chemerin expression is a localized response independent of the metabolic status. DHT altered follicle dynamics while increased the M1: M2 macrophages ratio in antral and pre-ovulatory follicles. While ovarian M1 macrophages expressing chemokine-like receptor 1 (CMKLR1) were increased, CMKLR1+ monocytes, which migrated toward chemerin-rich environment, were markedly decreased after 15 days of DHT. Androgen-induced granulosa cell apoptosis was dependent on the presence of macrophages. In humans, chemerin levels in follicular fluid, but not in serum, were higher in lean PCOS patients compared to BMI-matched controls and were associated with increased M1: M2 ratio. Our results support the concept that in PCOS, hyperandrogenemia increases chemerin expression while promotes CMKLR1+ monocytes recruitment and deregulates the immunological niche of ovaries. This study established a new immunological perspective in PCOS at the ovarian level. Hyperandrogenism is associated with upregulation of chemerin and macrophage unbalance in the ovaries.

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.

Ovarian Expression of Adipokines in Polycystic Ovary Syndrome: A Role for Chemerin, Omentin, and Apelin in Follicular Growth Arrest and Ovulatory Dysfunction?

Adipokines are a potential link between reproduction and energy metabolism and could partly explain some infertilities related to some pathophysiology, such as polycystic ovary syndrome (PCOS). However, adipokines were predominantly assessed in blood samples, while very little is known concerning their variations in follicular fluid (FF) and ovarian granulosa cells (GCs) of PCOS women. Thus, the objectives of our study were to investigate adiponectin, chemerin, resistin, visfatin, omentin, and apelin ovarian expression in PCOS women in comparison with controls and women with only a polycystic ovary morphology. In total, 78 women undergoing an in vitro fertilization procedure were divided into three groups: 23 PCOS women, 28 women presenting only ≥12 follicles per ovary (ECHO group), and 27 control women. Each group almost equally included normal weight and obese women. Follicular fluid (FF) concentration and granulosa cells (GCs) mRNA expression of adipokines and their receptors were assessed by ELISA and RT-qPCR, respectively. Omentin levels in FF and GC were higher in PCOS than in ECHO and control women, while apelin expression was increased in both PCOS and ECHO groups. FF chemerin concentration was predominant in normal-weight PCOS women compared to BMI (Body Mass Index)-matched ECHO and control women, while GC mRNA levels were higher in the obese PCOS group than in the ECHO one. Compared to PCOS, ECHO women had increased FF adiponectin concentrations and lower plasma AMH levels. The FF concentration of all adipokines was higher in obese subjects except for adiponectin, predominant in normal-weight women. In conclusion, women with PCOS expressed higher GC chemerin and omentin, whereas the ECHO group presented higher levels of FF adiponectin and apelin and lower plasma AMH and LH concentrations. Chemerin, omentin, and apelin expression was differently regulated in women with PCOS, suggesting their possible role in follicular growth arrest and ovulatory dysfunction characterizing PCOS pathogenesis.

The Association Between Serum Vaspin and Omentin-1 Levels in Obese Children with Metabolic Syndrome

BACKGROUND AND AIM

Excess visceral fat accumulation results in altered release of adipokines. The aim of this study was to examine the relationship between new adipokines (omentin-1 and vaspin), insulin resistance, and serum inflammatory markers in obese subjects with metabolic syndrome (MS).

PATIENTS AND METHODS

The study included a total of 121 obese children (79 females and 42 males, aged 12-17 years old). The obese subjects were divided into two groups based on the presence or absence of MS criteria (MS group and non-MS group). Serum omentin-1, vaspin, and high-sensitivity C-reactive protein (CRP) were measured in addition to the other glucose metabolism parameters.

RESULTS

MS was diagnosed in 45 obese children and 76 children did not meet the MS criteria. Serum omentin-1 (289.5 ± 51.9 ng/mL vs. 268.2 ± 60 ng/mL, P = 0.03) levels were significantly lower in the MS group compared to the non-MS group. Serum vaspin levels (1058.3 ± 118 pg/mL vs. 1178.6 ± 158 pg/mL, P = 0.02) were higher in the MS group than the non-MS group. CRP levels correlated well with both the adipokines (r = -0.236, P = 0.04 for omentin-1 and r = 0.296, P = 0.008 for vaspin), although these adipokines did not show statistically significant correlations with fasting glucose-insulin levels, homeostasis model assessment of insulin resistance, and 2 hr postload glucose level.

CONCLUSIONS

Higher vaspin and lower omentin-1 levels were determined in obese MS children compared to non-MS children and these adipokines were significantly correlated with high CRP values. These data support the view that adipokines in MS children contribute to increased inflammation markers before abnormal glucose metabolism.

Molecular Mechanisms of Vaspin Action - From Adipose Tissue to Skin and Bone, from Blood Vessels to the Brain

Visceral adipose tissue-derived serine protease inhibitor (vaspin) or SERPINA12 according to the serpin nomenclature was identified together with other genes and gene products that were specifically expressed or overexpressed in the intra-abdominal or visceral adipose tissue (AT) of the Otsuka Long-Evans Tokushima fatty rat. These rats spontaneously develop visceral obesity, insulin resistance, hyperinsulinemia and -glycemia, as well as hypertension and thus represent a well suited animal model of obesity and related metabolic disorders such as type 2 diabetes.The follow-up study reporting the cloning, expression and functional characterization of vaspin suggested the great and promising potential of this molecule to counteract obesity induced insulin resistance and inflammation and has since initiated over 300 publications, clinical and experimental, that have contributed to uncover the multifaceted functions and molecular mechanisms of vaspin action not only in the adipose, but in many different cells, tissues and organs. This review will give an update on mechanistic and structural aspects of vaspin with a focus on its serpin function, the physiology and regulation of vaspin expression, and will summarize the latest on vaspin function in various tissues such as the different adipose tissue depots as well as the vasculature, skin, bone and the brain.

The association between polycystic ovary syndrome, obesity, and the serum concentration of adipokines

PURPOSE

This study aimed to investigate the interactive effect of polycystic ovary syndrome (PCOS) status and obesity status on the serum levels of adipokines.

METHODS

In this comparative case-control cross-sectional study, 58 women with PCOS and 104 eumenorrheic non-hirsute women as the control group were recruited. They were further divided into two subgroups of overweight/obese and normal weight. The interactive effect of the PCOS status and obesity status on the circulating levels of adipokines was assessed using general linear model with the adjustment of age.

RESULTS

A statistically significant negative interaction was reported between obesity status and PCOS status in the determination of serum adiponectin and resistin concentrations (effect size = -0.14, interaction P = 0.001, effect size = -0.15, P = 0.016). It indicated that adiponectin and resistin were significantly decreased in overweight/obese patients with PCOS compared with other subgroups. Statistically significant positive interactive effects were found between PCOS status obesity status and leptin (effect size = 0.321, interaction P = 0.036), indicating that the overweight/obese women with PCOS had the higher levels of leptin compared with the control group. Also, no interaction was reported between PCOS status and obesity status with regard to the serum levels of other adipokines.

CONCLUSIONS

While no sufficient evidence is available with regard to the causal association between adipokines and PCOS, they may contribute to the development of PCOS and regarded as the novel biomarkers of PCOS.

Circulating omentin-1 levels in women with polycystic ovary syndrome: a meta-analysis

To investigate the association between circulating omentin-1 levels and polycystic ovary syndrome (PCOS) in women, a meta-analysis was performed. A systematic literature search using PubMed, Embase and Web of Science was carried out. Ten articles with 13 studies were included in this meta-analysis, which included a total of 1264 subjects (733 patients with PCOS and 531 controls). The pooled standard mean difference (SMD) and 95% confidence interval (CI) were used to estimate the association between omentin-1 levels and PCOS. Circulating omentin-1 levels were lower in PCOS with an SMD (95% CI) of -0.67 (-0.91, -0.43) and p = 0.000 (random-effects). However, significant heterogeneity was detected across studies (I²=73.6% and p = 0.000). The subgroup analysis suggested that omentin-1 levels in PCOS patients were associated with HOMA-IR ratio. Meta-regression analysis indicated region was the main source of heterogeneity (p = 0.048). The results of this meta-analysis suggested that circulating omentin-1 levels are significantly lower in women with PCOS compared with controls, which indicated that omentin-1 may play a role in the pathologic processes of PCOS.