Effect of irisin on endometrial receptivity of rats with polycystic ovary syndrome

Irisin as an emerging target in the regulation of reproductive functions in health and disease

Germ cells are highly conserved in the gonads, nurtured to either develop into a gamete or self-renew into a stem cell reserve. Preserving the germ cell pool and protecting the reproductive organs is essential for maintaining an individual's fertility. Several factors, including a sedentary lifestyle, pollutants, hormonal disruption, drugs, and a disease condition, have been shown to impair normal reproductive function. Irisin has recently been identified as an adipomyokine involved in modulating physiological functions based on the body's metabolic status. It is being studied for its role in various functions, including fertility. Findings show the localization of irisin in various parts of the reproductive axis, with the highest levels observed during puberty and pregnancy. This raises questions about its role and function in reproduction. Studies support irisin's role in protecting against disease-induced reproductive abnormalities and infertility. Therefore, the current review focuses on how irisin influences spermatogenesis and ovarian follicular development and plays a significant role in indirectly preserving the germ cell pool by protecting the gonads against oxidative stress and inflammation.

Altered Molecular Pathways and Biomarkers of Endometrial Receptivity in Infertile Women with Polycystic Ovary Syndrome

Anovulation is the most prominent cause of infertility in polycystic ovary syndrome (PCOS) patients. Although ovulation can be corrected pharmacologically, the number of pregnancies remains low. Even if excellent embryos are transferred by IVF, it does not change the high miscarriage rate of PCOS patients. These facts collectively indicate that there is a disorder of endometrial development and receptivity to the embryo in PCOS patients, including the decrease of receptive ability, inhibition of embryo adhesion, undersupply of energy, poor blood perfusion, and pro-inflammatory status in the endometrium. However, it has never received the same attention as ovulatory dysfunction. Here we list some alternations of endometrial receptivity in women with PCOS, discuss the underlying intricate mechanisms, and try to find out the possible therapeutic targets, which may bring new perspectives to those who are able to provide high-quality embryos.

Exercise-induced modulation of myokine irisin in bone and cartilage tissue—Positive effects on osteoarthritis: A narrative review

Osteoarthritis is a chronic degenerative musculoskeletal disease characterized by pathological changes in joint structures along with the incidence of which increases with age. Exercise is recommended for all clinical treatment guidelines of osteoarthritis, but the exact molecular mechanisms are still unknown. Irisin is a newly discovered myokine released mainly by skeletal muscle in recent years—a biologically active protein capable of being released into the bloodstream as an endocrine factor, the synthesis and secretion of which is specifically induced by exercise-induced muscle contraction. Although the discovery of irisin is relatively recent, its role in affecting bone density and cartilage homeostasis has been reported. Here, we review the production and structural characteristics of irisin and discuss the effects of the different types of exercise involved in the current study on irisin and the role of irisin in anti-aging. In addition, the role of irisin in the regulation of bone mineral density, bone metabolism, and its role in chondrocyte homeostasis and metabolism is reviewed. A series of studies on irisin have provided new insights into the mechanisms of exercise training in improving bone density, resisting cartilage degeneration, and maintaining the overall environmental homeostasis of the joint. These studies further contribute to the understanding of the role of exercise in the fight against osteoarthritis and will provide an important reference and aid in the development of the field of osteoarthritis prevention and treatment.

Hyperandrogenism and Polycystic ovary syndrome: Effects in pregnancy and offspring development

Polycystic ovary syndrome (PCOS) is one of the major endocrine disorders affecting women of reproductive age. Its etiology remains unclear. It is suggested that environmental factors, and particularly the intrauterine environment, play key roles in PCOS development. Besides the role of androgens in PCOS pathogenesis, exposure to endocrine disruptors, as is Bisphenol A, could also contribute to its development. Although PCOS is considered one of the leading causes of ovarian infertility, many PCOS patients can get pregnant. Some of them by natural conception and others by assisted reproductive technique treatments. As hyperandrogenism (one of PCOS main features) affects ovarian and uterine functions, PCOS women, despite reaching pregnancy, could present high-risk pregnancies, including implantation failure, an increased risk of gestational diabetes, preeclampsia, and preterm birth. Moreover, hyperandrogenism may also be maintained in these women during pregnancy. Therefore, as an altered uterine milieu, including hormonal imbalance, could affect the developing organisms, monitoring these patients throughout pregnancy and their offspring development is highly relevant. The present review focuses on the impact of androgenism and PCOS on fertility issues and pregnancy-related outcomes and offspring development. The evidence suggests that the increased risk of pregnancy complications and adverse offspring outcomes of PCOS women would be due to the factors involved in the syndrome pathogenesis and the related co-morbidities. A better understanding of the involved mechanisms is still needed and could contribute to a better management of these women and their offspring. This article is categorized under: Reproductive System Diseases > Molecular and Cellular Physiology Reproductive System Diseases > Environmental Factors.

Irisin: circulating levels in serum and its relation to gonadal axis

Irisin is an exercise-induced myokine/adipokine in mice and humans that plays an important role in 'browning' of white adipose tissue and has shown great potential as a treatment for some metabolic diseases, such as obesity, insulin resistance, and inflammation. The circulating irisin level is reported to be associated with exercise, obesity, diet, diseases, and exposure to different pharmacological agents. Several studies have attempted to characterize the role of irisin in PCOS and other reproductive diseases, but contradictory results have been reported. Our previous study showed that irisin may serve further functions in folliculogenesis and fertility. In this review, we present the current knowledge on the physiology of irisin and its role in gonadal axis. Firstly, we describe irisin circulating levels and speculate on the potential mechanisms involved in irisin secretion and regulation. Then, we focus on the irisin levels in PCOS, and explore the relationships between, BMI, insulin resistance, and hyperandrogenism. Finally, we present the results from animal interventional studies and in vitro experiments to investigate the relationship between irisin and gonadal axis, indicating its novel effects on reproduction and fertility.

Berberine improves ovulation and endometrial receptivity in polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is a clinical syndrome with reproductive and endocrine disorders. Berberine is a monomer from Chinese herbs such as Coptis chinensis, whose effect on improving ovulation and endometrial receptivity of PCOS is uncertain.

PURPOSE

To evaluate the effect of berberine on improving PCOS and explore the mechanism.

METHODS

The rat model of PCOS was induced by intraperitoneal injection of testosterone propionate. Then they was divided into model (Mod) group, low-dose of berberine (BL) group, high-dose of berberine (BH) group and metformin (Met) group as well as a control (Con) group was established. Ovary morphology, hormone level, glucolipid metabolism were measured. UID-mRNA-seq of ovary tissue was conducted to seek the mechanism of berberine on improving ovulation. Three biomarkers of endometrial receptivity were also examined in endometrium by immunohistochemistry.

RESULTS

The number of cystic follicles was increased while the number of corpus luteum was decreased in the rats of Mod group. These changes could be reversed by high-dose of berberine intervention. Berberine could also decrease the levels of serum luteinizing hormone (LH) and total cholesterol (TC) in PCOS rats. Meanwhile, berberine improved the impairment of abnormal oral glucose tolerance without affecting fasting insulin level and Homeostasis model assessment-insulin resistance (HOMA-IR). Luteinizing hormone/ choriogonadotropin receptor (LHCGR) and cytochrome P450 Family 19 Subfamily A Member 1 (CYP19A1) were focused via RNA-seq of ovary. Protein expression in ovary and mRNA expression in granulosa cell of LHCGR and CYP19A1 were decreased in Mod group and rescued by the intervention of berberine. A decrease of endometrial thickness and an increase of integrin αvβ3 and lysophosphatidic acid receptor 3 (LPAR3) protein expression were observed in Mod group, which could be also reversed by berberbine.

CONCLUSIONS

Berberine could improve ovulation in PCOS and the mechanism might be associated with up-regulating LHCGR and CYP19A1. Berberine could also improve endometrial receptivity through down-regualting αvβ3 and LPAR3.

Fibronectin type III domain-containing 5 in cardiovascular and metabolic diseases: a promising biomarker and therapeutic target

Cardiovascular and metabolic diseases are the leading causes of death and disability worldwide and impose a tremendous socioeconomic burden on individuals as well as the healthcare system. Fibronectin type III domain-containing 5 (FNDC5) is a widely distributed transmembrane glycoprotein that can be proteolytically cleaved and secreted as irisin to regulate glycolipid metabolism and cardiovascular homeostasis. In this review, we present the current knowledge on the predictive and therapeutic role of FNDC5 in a variety of cardiovascular and metabolic diseases, such as hypertension, atherosclerosis, ischemic heart disease, arrhythmia, metabolic cardiomyopathy, cardiac remodeling, heart failure, diabetes mellitus, and obesity.

Research progress of endometrial receptivity in patients with polycystic ovary syndrome: a systematic review

Polycystic ovary syndrome (PCOS) is a neuroendocrine heterogeneous disease that frequently occurs in women of reproductive age, causing serious damage to the fertility, quality of life, and physical and mental health of patients. The current studies have proved that satisfactory endometrial receptivity is one of the conditions that must be met during the process of spermatovum position, adhesion and invasion, as well as the subsequent blastocyst division and embryo development. Women with PCOS may suffer a series of pathological processes such as changes in the expression levels of hormones and related receptors, imbalances in the proportion of miscellaneous cytokines, insulin resistance, low-grade chronic inflammation and endometrial morphological changes, which will damage endometrial receptivity from various aspects and obstruct fertilized egg nidation and embryonic development, thus causing adverse reproductive health events including infertility and abortion. This article reviews the research progress about characteristics and related influencing factors of endometrial receptivity in PCOS patients.

Role of pomegranate extract in restoring endometrial androgen receptor expression, proliferation, and pinopodes in a rat model of polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is a multifactorial hormonal disorder accompanied by impairment of endometrial function and structure. Pomegranate is recognized for its role in normalizing the female sex hormones in PCOS with little known about its effect on the accompanying endometrial histological alterations.

AIM OF THE WORK

To assess the possible ameliorative role of pomegranate juice extract (PJE) on endometrial injury in a rat model of PCOS.

MATERIAL AND METHODS

Forty adult albino rats were equally divided into 4 groups; control, PJE-treated (400mg/kg/day for 3 weeks), letrozole-treated (PCOS) (1mg/kg/day for 3 weeks), and PJE & PCOS groups. Serum Follicle-stimulating hormone (FSH), Luteinizing hormone (LH), testosterone, estradiol, and tissue malondialdehyde (MDA) were assayed. Uterine samples were processed for histological staining with hematoxylin & eosin and Masson's trichrome stains, Ki67 and androgen receptor immunohistochemical staining, and scanning electron microscopy.

RESULTS

PCOS group revealed a significant increase in serum FSH, LH, testosterone, estradiol, and tissue MDA. Uterine sections depicted various histological alterations in the endometrium with signs of inflammation. A significant increase in the endometrial collagen fiber content, as well as a significant upregulation in Ki67 and androgen receptor immunohistochemical expression were detected. Scanning electron microscopy showed a significant decrease in the mean number of pinopodes. Concomitant administration of PJE efficiently restored the studied biochemical, histological, and immunohistochemical parameters.

CONCLUSION

PJE ameliorated PCOS accompanying endometrial histological alterations through its antioxidant, anti-inflammatory, anti-fibrotic, anti-proliferative, and anti-androgenic effects most probably due to its polyphenols content.

Endometrial function in women with polycystic ovary syndrome: a comprehensive review

BACKGROUND

Polycystic ovary syndrome (PCOS) is the most common cause of anovulatory infertility. An endometrial component has been suggested to contribute to subfertility and poor reproductive outcomes in affected women.

OBJECTIVE AND RATIONALE

The aim of this review was to determine whether there is sufficient evidence to support that endometrial function is altered in women with PCOS, whether clinical features of PCOS affect the endometrium, and whether there are evidence-based interventions to improve endometrial dysfunction in PCOS women.

SEARCH METHODS

An extensive literature search was performed from 1970 up to July 2020 using PubMed and Web of Science without language restriction. The search included all titles and abstracts assessing a relationship between PCOS and endometrial function, the role played by clinical and biochemical/hormonal factors related to PCOS and endometrial function, and the potential interventions aimed to improve endometrial function in women with PCOS. All published papers were included if considered relevant. Studies having a specific topic/hypothesis regarding endometrial cancer/hyperplasia in women with PCOS were excluded from the analysis.

OUTCOMES

Experimental and clinical data suggest that the endometrium differs in women with PCOS when compared to healthy controls. Clinical characteristics related to the syndrome, alone and/or in combination, may contribute to dysregulation of endometrial expression of sex hormone receptors and co-receptors, increase endometrial insulin-resistance with impaired glucose transport and utilization, and result in chronic low-grade inflammation, immune dysfunction, altered uterine vascularity, abnormal endometrial gene expression and cellular abnormalities in women with PCOS. Among several interventions to improve endometrial function in women with PCOS, to date, only lifestyle modification, metformin and bariatric surgery have the highest scientific evidence for clinical benefit.

WIDER IMPLICATIONS

Endometrial dysfunction and abnormal trophoblast invasion and placentation in PCOS women can predispose to miscarriage and pregnancy complications. Thus, patients and their health care providers should advise about these risks. Although currently no intervention can be universally recommended to reverse endometrial dysfunction in PCOS women, lifestyle modifications and metformin may improve underlying endometrial dysfunction and pregnancy outcomes in obese and/or insulin resistant patients. Bariatric surgery has shown its efficacy in severely obese PCOS patients, but a careful evaluation of the benefit/risk ratio is warranted. Large scale randomized controlled clinical trials should address these possibilities.

Integrin-Ligand Interactions in Inflammation, Cancer, and Metabolic Disease: Insights Into the Multifaceted Roles of an Emerging Ligand Irisin

Integrins are transmembrane proteins that mediate cellular adhesion and migration to neighboring cells or the extracellular matrix, which is essential for cells to undertake diverse physiological and pathological pathways. For integrin activation and ligand binding, bidirectional signaling across the cell membrane is needed. Integrins aberrantly activated under pathologic conditions facilitate cellular infiltration into tissues, thereby causing inflammatory or tumorigenic progressions. Thus, integrins have emerged to the forefront as promising targets for developing therapeutics to treat autoimmune and cancer diseases. In contrast, it remains a fact that integrin-ligand interactions are beneficial for improving the health status of different tissues. Among these ligands, irisin, a myokine produced mainly by skeletal muscles in an exercise-dependent manner, has been shown to bind to integrin αVβ5, alleviating symptoms under unfavorable conditions. These findings may provide insights into some of the underlying mechanisms by which exercise improves quality of life. This review will discuss the current understanding of integrin-ligand interactions in both health and disease. Likewise, we not only explain how diverse ligands play different roles in mediating cellular functions under both conditions via their interactions with integrins, but also specifically highlight the potential roles of the emerging ligand irisin in inflammation, cancer, and metabolic disease.

Irisin induces trophoblast differentiation via AMPK activation in the human placenta

Irisin, an adipokine, regulates differentiation and phenotype in various cell types including myocytes, adipocytes, and osteoblasts. Circulating irisin concentration increases throughout human pregnancy. In pregnancy disorders such as preeclampsia and gestational diabetes mellitus, circulating irisin levels are reduced compared to healthy controls. To date, there are no data on the role and molecular function of irisin in the human placenta or its contribution to pathophysiology. Aberrant trophoblast differentiation is involved in the pathophysiology of preeclampsia. The current study aimed to assess the molecular effects of irisin on trophoblast differentiation and function. First-trimester placental explants were cultured and treated with low (10 nM) and high (50 nM) physiological doses of irisin. Treatment with irisin dose-dependently increased both in vitro placental outgrowth (on Matrigel™) and trophoblast cell-cell fusion. Adenosine monophosphate-activated protein kinase (AMPK) signaling, an important regulator of cellular energy homeostasis that is involved in trophoblast differentiation and pathology, was subsequently investigated. Here, irisin exposure induced placental AMPK activation. To determine the effects of irisin on trophoblast differentiation, two trophoblast-like cell lines, HTR-8/SVneo and BeWo, were treated with irisin and/or a specific AMPK inhibitor (Compound C). Irisin-induced AMPK phosphorylation in HTR-8/SVneo cells. Additionally, as part of the differentiation process, integrin switching from α6 to α1 occurred as well as increased invasiveness. Overall, irisin promoted differentiation in villous and extravillous cell-based models via AMPK pathway activation. These findings provide evidence that exposure to irisin promotes differentiation and improves trophoblast functions in the human placenta that are affected in abnormal placentation.