Detection of soluble ST2 in human follicular fluid and luteinized granulosa cells

IL-33 and soluble ST2 in follicular fluid are associated with premature ovarian insufficiency

Background

Premature ovarian insufficiency (POI) is a common reproductive disease that is associated with chronic inflammation in ovaries. Interleukin 33 (IL-33) is a pro-inflammatory IL-1 family cytokine, and functions as an alarmin reflecting inflammatory reaction. Our study aimed to investigate levels of IL-33 and its soluble receptor (sST2) in both follicular fluid (FF) and paired serum during different stages of POI, and evaluate their predictive potentials for POI. Furthermore, we attempted to determine whether IL-33 and sST2 were associated with embryo quality.

Methods

A total of 148 women, including 50 patients with biochemical POI (bPOI) (10 IU/L < follicle-stimulating hormone (FSH) ≤ 25 IU/L), 46 patients with POI (25 IU/L

Results

FF IL-33 levels were significantly increased in bPOI and POI patients compared to controls. They exhibited positive associations with FSH and luteinizing hormone (LH), whereas negative correlations with anti-Müllerian hormone (AMH), estradiol (E2), testosterone (T) and antral follicle count (AFC). Receiver operating characteristic (ROC) curve analysis showed that for POI prediction, FF IL-33 had a better predictive accuracy (AUC 0.901) with high sensitivity (82.61%) and good specificity (84.62%) than those for bPOI prediction. IL-33 levels in paired serum did not differ among three groups. Regarding sST2, its levels in FF declined with POI progression. Contrarily, they showed negative associations with FSH and LH, but positive correlations with AMH, E2, T and AFC. ROC analysis revealed that FF sST2 had comparatively weak potentials for both bPOI and POI prediction compared to those of FF IL-33. Similarly, there was no significant alteration of sST2 in paired serum among three groups. Additionally, Spearman's correlation analysis revealed that FF IL-33 levels were negatively associated with the rates of Day-3 good-quality embryos (r=-0.206, P=0.012), whereas FF sST2 did not.

Conclusion

Our study revealed an increased abundance of FF IL-33, whereas an sST2 deficiency with POI development. This implies that IL-33 and sST2 levels might be associated with the development of POI.

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Key Words

• IL-33
• embryo development
• embryo quality
• inflammation
• ovarian reserve
• predictor
• premature ovarian insufficiency
• soluble ST2

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MESH Headings

• Humans
• Female
• Interleukin-33/blood
• Interleukin-33/metabolism
• Interleukin-1 Receptor-Like 1 Protein/blood
• Interleukin-1 Receptor-Like 1 Protein/metabolism
• Follicular Fluid/metabolism
• Primary Ovarian Insufficiency/blood
• Primary Ovarian Insufficiency/metabolism
• Adult
• Biomarkers/blood
• Biomarkers/metabolism
• Biomarkers/analysis
• Follicle Stimulating Hormone/blood
• Follicle Stimulating Hormone/metabolism
• Case-Control Studies

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Affiliation(s)

Maoxing Tang Department of Reproductive Medicine, Guangdong Provincial People’s Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, China
Xuedong Sun Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, China
Ping Li Department of Reproductive Medicine, Women and Children’s Hospital, School of Medicine, Xiamen University, Xiamen, China
Weifen Deng Reproductive Medicine Centre, Shenzhen Hengsheng Hospital, Shenzhen, China
Xi Zhan Department of Reproductive Medicine, Guangdong Provincial People’s Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, China
Peng Sun Department of Reproductive Medicine, Guangdong Provincial People’s Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, China
Yuhua Shi Department of Obstetrics and Gynecology, Center for Reproductive Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, China

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Infertility, IL-17, IL-33 and Microbiome Cross-Talk: The Extended ARIA-MeDALL Hypothesis

Infertility, defined as the inability to obtain pregnancy after 12 months of regular unprotected sexual intercourse, has increased in prevalence over the past decades, similarly to chronic, allergic, autoimmune, or neurodegenerative diseases. A recent ARIA-MeDALL hypothesis has proposed that all these diseases are linked to dysbiosis and to some cytokines such as interleukin 17 (IL-17) and interleukin 33 (IL-33). Our paper suggests that endometriosis, a leading cause of infertility, is linked to endometrial dysbiosis and two key cytokines, IL-17 and IL-33, which interact with intestinal dysbiosis. Intestinal dysbiosis contributes to elevated estrogen levels, a primary factor in endometriosis. Estrogens strongly activate IL-17 and IL-33, supporting the existence of a gut-endometrial axis as a significant contributor to infertility.

Facilitation of Ovarian Response by Mechanical Force-Latest Insight on Fertility Improvement in Women with Poor Ovarian Response or Primary Ovarian Insufficiency

The decline in fertility in aging women, especially those with poor ovarian response (POR) or primary ovarian insufficiency (POI), is a major concern for modern IVF centers. Fertility treatments have traditionally relied on gonadotropin- and steroid-hormone-based IVF practices, but these methods have limitations, especially for women with aging ovaries. Researchers have been motivated to explore alternative approaches. Ovarian aging is a complicated process, and the deterioration of oocytes, follicular cells, the extracellular matrix (ECM), and the stromal compartment can all contribute to declining fertility. Adjunct interventions that involve the use of hormones, steroids, and cofactors and gamete engineering are two major research areas aimed to improve fertility in aging women. Additionally, mechanical procedures including the In Vitro Activation (IVA) procedure, which combines pharmacological activators and fragmentation of ovarian strips, and the Whole Ovary Laparoscopic Incision (WOLI) procedure that solely relies on mechanical manipulation in vivo have shown promising results in improving follicle growth and fertility in women with POR and POI. Advances in the use of mechanical procedures have brought exciting opportunities to improve fertility outcomes in aging women with POR or POI. While the lack of a comprehensive understanding of the molecular mechanisms that lead to fertility decline in aging women remains a major challenge for further improvement of mechanical-manipulation-based approaches, recent progress has provided a better view of how these procedures promote folliculogenesis in the fibrotic and avascular aging ovaries. In this review, we first provide a brief overview of the potential mechanisms that contribute to ovarian aging in POI and POR patients, followed by a discussion of measures that aim to improve ovarian folliculogenesis in aging women. At last, we discuss the likely mechanisms that contribute to the outcomes of IVA and WOLI procedures and potential future directions.

Relationship Between Semen IL-6, IL-33 and Malondialdehyde Generation in Human Seminal Plasma and Spermatozoa

Cytokines are physiological seminal components and their abnormal levels, reported in different pathological conditions, negatively influence the sperm function. We analysed the relationship between interleukin (IL)-6 and IL-33 levels and lipid peroxidation (LPO), measured both in semen and sperm lysate, in 44 human semen samples. The semen analysis was performed following the WHO guidelines. Seminal IL-6 and IL-33 concentrations were assessed by ELISA and LPO was evaluated measuring malondialdehyde (MDA) both in seminal plasma and viable spermatozoa. Two small groups of patients with varicocele and infection were extrapolated from the cases analysed and the variables compared with those of a group of control. IL-33 levels were undetectable in all samples and IL-6 levels were positively correlated with both seminal and sperm MDA concentrations (p < 0.01) and negatively with sperm parameters (p < 0.01). Seminal and sperm MDA levels were both negatively correlated with sperm parameters (p < 0.01). IL-6 and semen MDA showed an exponential positive relationship, whereas MDA values measured in viable spermatozoa were low until IL-6 amount reached a concentration of >30 pg/mL, rising consistently. By comparing the variables in the groups, we confirmed that a high IL-6 concentration in the varicocele and infection groups was concomitant with an increase of seminal MDA levels, but also with MDA measured in viable spermatozoa, which represents the novelty of this study. We identified the IL-6 threshold, beyond which sperm MDA concentration rises concomitantly with the increase of IL-6 concentration. Other studies are needed, considering the increasing number of patients with different pathologies affecting male infertility.

Dynamic Expression of Interleukin-33 and ST2 in the Mouse Reproductive Tract Is Influenced by Superovulation

Interleukin-33 (IL-33) is an IL-1 family cytokine with pleiotropic effects on diverse cell types. Dysregulated IL-33 signaling has been implicated in pregnancy-related disorders, including preeclampsia and recurrent pregnancy loss, and in ovarian function in women undergoing controlled ovarian stimulation for in vitro fertilization. To date, expression of IL-33 and its receptor subunit, ST2, in the female reproductive tract remains poorly characterized. We identify IL-33-expressing oocytes surrounded by ST2-expressing granulosa cells at all stages of follicular development, in addition to IL-33⁺ and ST2⁺ non-endothelial cells in the ovarian stroma and theca layer in ovaries from adult mice. These expression patterns are similar in estrus- and diestrus-stage adults and in pubescent mice, suggesting a role for IL-33 signaling in ovarian function throughout development and in the estrous cycle. In the uterus, we find expression of IL-33 and ST2 in glandular and luminal epithelia during estrus and at the initiation of pregnancy. Uterine IL-33 expression was modulated by the estrous cycle and was reduced in pubescent females. Last, superovulation increases transcripts for IL-33 and the soluble form of ST2 (sST2) in ovaries, and for IL-33 in uteri. Collectively, our findings lay the foundation for studies identifying cell type-specific requirements for IL-33/ST2 signaling in the establishment and maintenance of mouse pregnancy.

IL-33-Responsive Group 2 Innate Lymphoid Cells Are Regulated by Female Sex Hormones in the Uterus

Group 2 innate lymphoid cells (ILC2s) reside in multiple organs in the body, where they play roles in immunity, tissue homeostasis, and metabolic regulation. However, little is known about the regulatory mechanisms of ILC2s in different organs. Here, we identified ILC2s in the mouse uterus and found that they express cell surface molecules, including the IL-33 receptor, ST2, that are roughly comparable to those expressed by lung ILC2s. Both in vivo and in vitro treatment with IL-33 induced type 2 cytokine production in uterine ILC2s, suggesting that they respond to IL-33 in a manner similar to ILC2s in other organs. Importantly, uterine ILC2s were nearly absent in ovariectomized mice and were increased in wild-type mice by estrogen administration, whereas lung ILC2s were unaffected by both ovariectomy and estrogen administration. Likewise, a marked reduction in uterine ILC2s was observed in mice deficient in estrogen receptor α or estrogen receptor β. Furthermore, uterine ILC2s highly expressed estrogen receptor α, and in vitro culture of isolated uterine ILC2s with 17β-estradiol modified expression of a number of genes. Finally, an increased prevalence in neonatal mortality was observed in litters from dams lacking the IL-33 receptor, ST2. Taken together, our findings indicate that unlike lung IL2Cs, uterine ILC2s are regulated by female sex hormones, which may specialize them for specific physiological functions.

Soluble ST2--analytical considerations

Suppression of tumorigenicity 2 (ST2, also known as interleukin [IL]-1 receptor-like-1) is an IL-1 receptor family member with transmembrane (ST2L) and soluble isoforms (sST2). ST2L is a membrane-bound receptor, and IL-33 is the functional ligand for ST2L. sST2, a soluble truncated form of ST2L, is secreted into the circulation and functions as a "decoy" receptor for IL-33, inhibiting IL-33/ST2L signaling. Blood concentrations of sST2 are increased in inflammatory diseases and heart disease and are considered a valuable prognostic marker in both conditions. In multiple clinical trials, sST2 has emerged as a clinically useful prognostic biomarker in patients with cardiac diseases. Interestingly, sST2 even provides prognostic information in low-risk community-based populations. In this review, we will discuss analytical considerations of measuring circulating sST2 including pre-analytical issues, such as in vitro stability of sST2, biological variation of sST2, and postanalytical issues, such as reference ranges and comparisons to diseased cohorts.

Characterization of microRNA profile in human cumulus granulosa cells: Identification of microRNAs that regulate Notch signaling and are associated with PCOS

CONTEXT

Polycystic ovary syndrome (PCOS), a complex and heterogeneous endocrine condition, is characterized by polycystic ovaries, hyperandrogenism, insulin resistance and chronic anovulation. Cumulus granulosa cells surrounding the oocyte are involved in different aspects of PCOS pathology. Several studies suggested that miRNAs play an important regulatory role at the post-transcriptional level in cumulus granulosa cells.

OBJECTIVE

Our objective was to describe the altered miRNA expression profiles and miRNA targeted signaling pathways in PCOS.

DESIGN

Case-control study that involved 21 women with PCOS and 20 women without the disease (controls). The miRNA expression profiles of human cumulus granulosa cells were determined using next generation sequencing by Illumina Hiseq 2000. The differentially expressed miRNAs and novel miRNAs were validated by quantitative real-time PCR. The Notch3 and MAPK3 were demonstrated to be targeted by miR-483-5p based on quantitative real-time PCR, western blot and luciferase activity assay.

RESULTS

Compared with controls, a total of 59 known miRNA were identified that differentially expressed in PCOS cumulus granulosa cells, including 21 miRNAs increase and 38 miRNAs decrease. Moreover, the novel miRNAs were predicted in PCOS and control cumulus granulosa cells. The potential regulating roles of miRNA in pathophysiology of PCOS were analyzed by GO and KEGG pathway annotation, and several important processes were identified to be targeted by the differentially expressed miRNAs, such as Notch signaling, regulation of hormone, and energy metabolism. Furthermore, Notch3 and MAPK3, the members of Notch signaling and ERK-MAPK pathway, were demonstrated to be regulated by miR-483-5p based on negative expression correlation validation and detection of Notch3/MAPK3 expression after miR-483-5p mimics transfection. Dual luciferase activity assay suggested that Notch3 and MAPK3 were directly targeted by miR-483-5p.

CONCLUSION

Our data suggested that miRNAs and their targeted pathways (e.g. Notch signaling pathway) play important roles in the etiology and pathophysiology of PCOS, and provides novel candidates for molecular biomarkers or treatment targets in the research of female infertility associated with PCOS.

Soluble ST2 in heart failure

In addition to routine clinical laboratory tests (including natriuretic peptides and cardiac troponins), other biomarkers are gaining attention for their utility in heart failure (HF) management. Among them, soluble ST2 (sST2) a novel biomarker integrating inflammation, fibrosis, and cardiac stress has been included in the 2013 ACCF/AHA guideline for additive risk stratification of patients with acute and chronic HF. sST2 is an interleukin-1 (IL-1) receptor family member, is secreted into the circulation and functions as a "decoy" receptor for IL-33, inhibiting IL-33/ST2 signaling. Blood concentrations of sST2 are increased in various diseases such as inflammatory diseases and heart diseases and are considered a valuable prognostic marker in both conditions. sST2 lacks disease specificity and, therefore, is not a valuable marker for the diagnosis of HF. In acute and chronic HF, however, sST2 is strongly associated with measures of HF severity and poor outcome. Several studies in patients with HF indicate that serial measurement of sST2 has prognostic value and could have a potential role in future biomarker-directed therapy. In this review, the role of sST2 as a HF biomarker will be discussed, specifically addressing analytical considerations of measuring sST2 as well as the clinical applications of measurement of sST2 for the diagnosis, prognosis and monitoring of acute and chronic HF.