Evaluation of endometrial immune status of polycystic ovary syndrome

The Impacts of Inflammatory and Autoimmune Conditions on the Endometrium and Reproductive Outcomes

Background: A healthy pregnancy begins with an adequate endometrial state, even before the arrival of a blastocyst. Proper endometrial priming and the development of a tolerogenic decidua are key steps in creating the perfect environment for implantation and pregnancy. In these processes, the involvement of the maternal immune system seems to be of great relevance, modulating the different decidual immune populations to prepare the endometrium for a potential pregnancy. However, certain local pathologies of an inflammatory and autoimmune nature appear to have a direct impact on these phenomena, thus altering patients' reproductive outcomes. Methods: This literature review analyzes original articles, reviews, systematic reviews, and meta-analyses published between 1990 and 2024, concerning the impact of different inflammatory and autoimmune conditions on endometrial status and fertility. The included papers were obtained from Medline (Pubmed) and the Cochrane library. Results: There is evidence that endometriosis, adenomyosis, and chronic endometritis, through the promotion of a chronic inflammatory environment, are capable of altering endometrial immune populations, and, thus, processes essential for early pregnancy. Among other effects, these conditions have been linked to impaired decidualization, alterations in progesterone responsiveness, and hindered placentation. Similarly, antiphospholipid syndrome (APS), thyroid dysfunction, diabetes, and other pathologies related to glucose and gluten metabolism, due to their autoimmune nature, also appear to have a local impact on the uterine environment, affecting reproductive success through different mechanisms, including altered hormonal response and, again, impaired decidualization. Conclusions: The management of inflammatory and autoimmune diseases in assisted reproduction patients is gaining importance due to their direct impact on the endometrium. It is necessary to follow current expert recommendations and established therapeutic approaches in order to improve patients' prospects, ranging from antibiotic treatment in chronic endometritis to heparin and aspirin in APS, as well as hormonal treatments for endometriosis/adenomyosis or a gluten-free diet in celiac disease. All of them and the rest of the therapeutic perspectives, both current and under investigation, are presented throughout this work, assessing the possible improvements for reproductive outcomes.

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.

Reducing the Risk of Pre-Eclampsia in Women with Polycystic Ovary Syndrome Using a Combination of Pregnancy Screening, Lifestyle, and Medical Management Strategies

Polycystic ovary syndrome (PCOS) is a multisystem disorder that presents with a variety of phenotypes involving metabolic, endocrine, reproductive, and psychological symptoms and signs. Women with PCOS are at increased risk of pregnancy complications including implantation failure, miscarriage, gestational diabetes, fetal growth restriction, preterm labor, and pre-eclampsia (PE). This may be attributed to the presence of specific susceptibility features associated with PCOS before and during pregnancy, such as chronic systemic inflammation, insulin resistance (IR), and hyperandrogenism, all of which have been associated with an increased risk of pregnancy complications. Many of the features of PCOS are reversible following lifestyle interventions such as diet and exercise, and pregnant women following a healthy lifestyle have been found to have a lower risk of complications, including PE. This narrative synthesis summarizes the evidence investigating the risk of PE and the role of nutritional factors in women with PCOS. The findings suggest that the beneficial aspects of lifestyle management of PCOS, as recommended in the evidence-based international guidelines, extend to improved pregnancy outcomes. Identifying high-risk women with PCOS will allow targeted interventions, early-pregnancy screening, and increased surveillance for PE. Women with PCOS should be included in risk assessment algorithms for PE.

Biomarkers in Polycystic Ovary Syndrome

Polycystic Ovary Syndrome (PCOS) is the most common endocrine disorder in reproductive-age women. PCOS is diagnosed by the presence of two of the following three characteristics: hyperandrogenemia and/or hyperandrogenism, oligo/amenorrhea, and polycystic ovarian morphology. PCOS is associated with reproductive and non-reproductive complications, including obesity, insulin resistance and diabetes, dyslipidemia, and increased blood pressure. There is an urgent need for biomarkers that address both the reproductive and non-reproductive aspects of this complex syndrome. This review focuses on biomarkers, or potential ones, associated with the reproductive and non-reproductive aspects of PCOS, including anthropometric and clinical biomarkers, insulin and the IGF-1 system, lipids, anti-Müllerian hormone and gonadotropins, steroids, inflammatory and renal injury biomarkers, oxidative stress, and non-coding RNAs. We expect that this review will bring some light on the recent updates in the field and encourage researchers to join the exciting and promising field of PCOS biomarkers.

Dysregulation of immune response in PCOS organ system

Polycystic ovary syndrome (PCOS) is the most common reproductive endocrine disorder affecting women, which can lead to infertility. Infertility, obesity, hirsutism, acne, and irregular menstruation are just a few of the issues that PCOS can be linked to. PCOS has a complicated pathophysiology and a range of clinical symptoms. Chronic low-grade inflammation is one of the features of PCOS. The inflammatory environment involves immune and metabolic disturbances. Numerous organ systems across the body, in addition to the female reproductive system, have been affected by the pathogenic role of immunological dysregulation in PCOS in recent years. Insulin resistance and hyperandrogenism are associated with immune cell dysfunction and cytokine imbalance. More importantly, obesity is also involved in immune dysfunction in PCOS, leading to an inflammatory environment in women with PCOS. Hormone, obesity, and metabolic interactions contribute to the pathogenesis of PCOS. Hormone imbalance may also contribute to the development of autoimmune diseases. The aim of this review is to summarize the pathophysiological role of immune dysregulation in various organ systems of PCOS patients and provide new ideas for systemic treatment of PCOS in the future.

Immune Dysfunction in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in reproductive-aged individuals with ovaries. It is associated with anovulation and increased risk to fertility and metabolic, cardiovascular, and psychological health. The pathophysiology of PCOS is still inadequately understood, although there is evidence of persistent low-grade inflammation, which correlates with associated visceral obesity. Elevated proinflammatory cytokine markers and altered immune cells have been reported in PCOS and raise the possibility that immune factors contribute to ovulatory dysfunction. Because normal ovulation is modulated by immune cells and cytokines in the ovarian microenvironment, the endocrine and metabolic abnormalities associated with PCOS orchestrate the accompanying adverse effects on ovulation and implantation. This review evaluates the current literature on the relationship between PCOS and immune abnormalities, with a focus on emerging research in the field.

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.

How do pre-pregnancy endometrial macrophages contribute to pregnancy?

Macrophages are professional phagocytes with a wide distribution in all tissues throughout the body. Macrophages play a crucial role in homeostasis and numerous physiological processes beyond innate and adaptive immunity, including cellular debris removal, metabolic regulation, tissue repair, and tissue remodeling. Uterine macrophages are a heterogeneous and highly plastic subset of immune cells regulated by the local microenvironment and, in addition to their anti-inflammatory and anti-infective functions, support the establishment and maintenance of pregnancy. Comprehensive reviews have summarized the role of decidual macrophages during pregnancy. However, the distribution of macrophages in the endometrium prior to pregnancy, their functional remodeling, and the knock-on effects on subsequent pregnancies have not been elucidated. In this review, we focus on 1) how the phenotypes of endometrial macrophages and their interactions with other endometrial cells indicate or contribute to the subsequent pregnancy, 2) the adaptive switching of endometrial macrophages during the initial establishment of pregnancy, 3) and the pregnancy complications and pregnancy-related disorders associated with endometrial macrophages.

Tumor Necrosis Factor Alpha Level in the Uterine Fluid of Patients with Polycystic Ovary Syndrome and Its Correlation with Clinical Parameters

OBJECTIVE

This study aimed to analyze tumor necrosis factor alpha (TNF-α) level in the uterine fluid of patients with polycystic ovary syndrome (PCOS) and its correlation with the clinical parameters of PCOS.

METHODS

A total of 162 patients treated in the Reproductive Medicine Center of the General Hospital of Ningxia Medical University between December 2019 and November 2021 were enrolled as research subjects, including 80 patients with PCOS and 82 patients with other gynecological disease, who were used as the controls. The patients' general data, along with blood glucose, blood lipid, insulin, and sex hormone levels and other data, were collected. The TNF-α levels in the patients' serum and uterine fluid were detected using enzyme-linked immunosorbent assay.

RESULTS

Compared with the patients in the control group, the body mass index (BMI), anti-Müllerian hormone, luteinizing hormone, testosterone (T), fasting insulin (FINS), homeostasis model assessment insulin resistance (HOMA-IR), triglyceride (TG), and low-density lipoprotein (LDL) of patients with PCOS were higher, and high-density lipoprotein was lower (P < 0.05). The TNF-α levels in the serum and uterine fluid of patients with PCOS were higher than those in the control group (P < 0.01), and the TNF-α levels in the uterine fluid of these patients was significantly correlated with BMI, T, FINS, HOMA-IR, serum TNF-α, TG, and LDL (P < 0.05).

CONCLUSION

There is local inflammation in the uterine cavity of patients with PCOS, and the detection of cytokines in uterine secretions may be a simple and feasible method of understanding the uterine microenvironment of patients with PCOS.

Transcriptomic Analysis Reveals Endometrial Dynamics in Normoweight and Overweight/Obese Polycystic Ovary Syndrome Women

The aim of this work was to identify the transcriptomic characteristics of the endometrium in normoweight and overweight/obese polycystic ovary syndrome (PCOS) potentially underlying the pathogenesis. This study included 38 patients undergoing in vitro fertilization: 22 women with PCOS and 16 matched controls. Each of the groups was subdivided into normoweight (body mass index (BMI) < 25 kg/m²) and overweight/obese (BMI ≥25 kg/m²) subgroups. Endometrium samples were collected in the secretory phase from controls or in a modeled secretory phase using daily administration of progesterone from women with PCOS before in vitro fertilization treatment. Transcriptome profiles were assessed by high-throughput RNA sequencing to investigate distinct endometrial gene expression patterns in PCOS. Bioinformatics analyses revealed that the endometrium from PCOS expresses significantly different transcripts encoding endometrial receptivity, inflammatory response, angiogenesis, and energy metabolism. Additionally, our study demonstrated that the differentially expressed genes between normoweight and overweight/obese PCOS are involved in fatty acid metabolism, endometrial decidualization, and immune response. For the first time, we have described the transcriptome characteristics of normoweight and overweight/obese PCOS endometria. Our results indicate different endometrial gene expressions between different subtypes of PCOS and non-PCOS women, which might affect endometrial functions in PCOS patients.

Artificial intelligence deep learning model assessment of leukocyte counts and proliferation in endometrium from women with and without polycystic ovary syndrome

OBJECTIVE

To study whether artificial intelligence (AI) technology can be used to discern quantitative differences in endometrial immune cells between cycle phases and between samples from women with polycystic ovary syndrome (PCOS) and non-PCOS controls. Only a few studies have analyzed endometrial histology using AI technology, and especially, studies of the PCOS endometrium are lacking, partly because of the technically challenging analysis and unavailability of well-phenotyped samples. Novel AI technologies can overcome this problem.

DESIGN

Case-control study.

SETTING

University hospital-based research laboratory.

PATIENT(S)

Forty-eight women with PCOS and 43 controls. Proliferative phase samples (26 control and 23 PCOS) and luteinizing hormone (LH) surge timed LH+ 7-9 (10 control and 16 PCOS) and LH+ 10-12 (7 control and 9 PCOS) secretory endometrial samples were collected during 2014-2019.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Endometrial samples were stained with antibodies for CD8+ T cells, CD56+ uterine natural killer cells, CD68+ macrophages, and proliferation marker Ki67. Scanned whole slide images were analyzed with an AI deep learning model. Cycle phase differences in leukocyte counts, proliferation rate, and endometrial thickness were measured within the study populations and between the PCOS and control samples. A subanalysis of anovulatory PCOS samples (n = 11) vs. proliferative phase controls (n = 18) was also performed.

RESULT(S)

Automated cell counting with a deep learning model performs well for the human endometrium. The leukocyte numbers and proliferation in the endometrium fluctuate with the menstrual cycle. Differences in leukocyte counts were not observed between the whole PCOS population and controls. However, anovulatory women with PCOS presented with a higher number of CD68+ cells in the epithelium (controls vs. PCOS, median [interquartile range], 0.92 [0.75-1.51] vs. 1.97 [1.12-2.68]) and fewer leukocytes in the stroma (CD8%, 3.72 [2.18-4.20] vs. 1.44 [0.77-3.03]; CD56%, 6.36 [4.43-7.43] vs. 2.07 [0.65-4.99]; CD68%, 4.57 [3.92-5.70] vs. 3.07 [1.73-4.59], respectively) compared with the controls. The endometrial thickness and proliferation rate were comparable between the PCOS and control groups in all cycle phases.

CONCLUSION(S)

Artificial intelligence technology provides a powerful tool for endometrial research because it is objective and can efficiently analyze endometrial compartments separately. Ovulatory endometrium from women with PCOS did not differ remarkably from the controls, which may indicate that gaining ovulatory cycles normalizes the PCOS endometrium and enables normalization of leukocyte environment before implantation. Deviant endometrial leukocyte populations observed in anovulatory women with PCOS could be interrelated with the altered endometrial function observed in these women.

Quantitative Proteomics Reveals That a Prognostic Signature of the Endometrium of the Polycystic Ovary Syndrome Women Based on Ferroptosis Proteins

OBJECTIVE

We aimed to study the relationship between ferroptosis proteins and reproductive outcomes of infertile patients with PCOS and construct the related prognostic model.

METHODS

These endometrium samples of the study were collected from 33 women with PCOS and 7 control women with successful pregnancies at the Reproductive Center of Lanzhou University Second Hospital, September 2019 to September 2020. The 40 patients' endometrium was identified the differentially expressed proteins (DEPs) using liquid chromatography tandem mass spectrometry. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and Gene Ontology (GO) showed that the DEPs related pathways and functions between PCOS and controls. Subsequently, univariate Cox regression analysis and Lasso regression were used to identifying independent prognostic ferroptosis proteins, which were utilized to establish a prognostic model. Then the performance of the prognostic model was evaluated by receiver operating characteristic curve (ROC) and decision curve analysis (DCA). Then clinical data and prognostic model were used to predict the reproductive outcomes of PCOS patients by constructing the nomograms. Finally, we performed the single sample gene set enrichment analysis (ssGSEA) to explore the correlation between risk scores and immune status.

RESULTS

A total of 5331 proteins were identified, 391 proteins were differentially expressed in the PCOS and controls. The KEGG analysis revealed that the ferroptosis pathway was significantly different between PCOS and controls. 5 ferroptosis proteins (GPX4, DPP4, G6PD, PCBP1, and PCBP2) prognostic model (FerSig) was constructed via Cox regression and Lasso regression. Patients were separated into high and low-risk groups according to the FerSig. Kaplan-Meier curve showed that patients in the low-risk group had much better reproductive outcomes than those in the high-risk group. The DCA showed that the risk score was an independent predictive factor for reproductive outcomes. Compared with clinical data, ROC curve analysis indicated the FerSig proteins as a potential diagnostic and prognostic factor in PCOS patients. Functional analysis revealed that the FerSig proteins and immune microenvironment were correlated to the prognosis of PCOS.

CONCLUSION

The prognostic model focused on the FerSig proteins could predict the reproductive outcomes of PCOS patients with decreased endometrial receptivity, and provided theoretical basis for individualized treatment.

Associations Between Asthma and Polycystic Ovary Syndrome: Current Perspectives

A potential correlation between polycystic ovary syndrome (PCOS) and asthma, used to be identified as diseases originating from two independent systems, has been supported by increasing evidence. From an epidemiological perspective, mounting studies have confirmed that women suffering from PCOS exhibit increased susceptibility to asthma. Meanwhile, PCOS and asthma seem to share several mutual pathological conditions, such as metabolic disorders, hormonal fluctuation, proinflammatory state, etc. Here, we further elucidate the correlation between asthma and PCOS by focusing on the internal common pathophysiology and adverse influences on women's health. Understanding the internal connection between PCOS and asthma may shed light on developing new prevention and control strategies to fight against these conditions.

A review of the pathophysiology of recurrent implantation failure

Implantation is a critical step in human reproduction. The success of this step is dependent on a competent blastocyst, receptive endometrium, and successful cross talk between the embryonic and maternal interfaces. Recurrent implantation failure is the lack of implantation after the transfer of several embryo transfers. As the success of in vitro fertilization has increased and failures have become more unacceptable for patients and providers, the literature on recurrent implantation failure has increased. While this clinical phenomenon is often encountered, there is not a universally agreed-on definition-something addressed in an earlier portion of this Views and Reviews. Implantation failure can result from several different factors. In this review, we discuss factors including the maternal immune system, genetics of the embryo and parents, anatomic factors, hematologic factors, reproductive tract microbiome, and endocrine milieu, which factors into embryo and endometrial synchrony. These potential causes are at various stages of research and not all have clear implications or immediately apparent treatment.

Is fertility reduced in ovulatory women with polycystic ovary syndrome? An opinion paper

Polycystic ovary syndrome (PCOS) is the most common cause of anovulatory infertility; however, whether women with PCOS and spontaneous or drug-induced ovulatory cycles have the same reproductive potential as non-PCOS controls is a matter of debate. In the present opinion paper, the author takes the opportunity to summarize the collective evidence supporting the hypothesis of reduced fertility potential in women with PCOS, regardless of ovulatory status, and speculate that reduced reproductive potential may be caused by altered oocytes, embryo and endometrial competence, and infertility-related co-morbidities as well as an increased risk of pregnancy complications.

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.