The proportion of follicular fluid CD16+CD56DIM NK cells is increased in IVF patients with idiopathic infertility

Single-cell RNA-seq analysis and cell-cluster deconvolution of the human preovulatory follicular fluid cells provide insights into the pathophysiology of ovarian hyporesponse

Reduction in responsiveness to gonadotropins or hyporesponsiveness may lead to the failure of in vitro fertilization (IVF), due to a low number of retrieved oocytes. The ovarian sensitivity index (OSI) is used to reflect the ovarian responsiveness to gonadotropin stimulation before IVF. Although introduced to clinical practice already years ago, its usefulness to predict clinical outcomes requires further research. Nevertheless, pathophysiological mechanisms of ovarian hyporesponse, along with advanced maternal age and in younger women, have not been fully elucidated. Follicles consist of multiple cell types responsible for a repertoire of biological processes including responding to pituitary gonadotropins necessary for follicle growth and oocyte maturation as well as ovulation. Encouraging evidence suggests that hyporesponse could be influenced by many contributing factors, therefore, investigating the variability of ovarian follicular cell types and their gene expression in hyporesponders is highly informative for increasing their prognosis for IVF live birth. Due to advancements in single-cell analysis technologies, the role of somatic cell populations in the development of infertility of ovarian etiology can be clarified. Here, somatic cells were collected from the fluid of preovulatory ovarian follicles of patients undergoing IVF, and RNA-seq was performed to study the associations between OSI and gene expression. We identified 12 molecular pathways differentially regulated between hypo- and normoresponder patient groups (FDR<0.05) from which extracellular matrix organization, post-translational protein phosphorylation, and regulation of Insulin-like Growth Factor (IGF) transport and uptake by IGF Binding Proteins were regulated age-independently. We then generated single-cell RNA-seq data from matching follicles revealing 14 distinct cell clusters. Using cell cluster-specific deconvolution from the bulk RNA-seq data of 18 IVF patients we integrated the datasets as a novel approach and discovered that the abundance of three cell clusters significantly varied between hypo- and normoresponder groups suggesting their role in contributing to the deviations from normal ovarian response to gonadotropin stimulation. Our work uncovers new information regarding the differences in the follicular gene expression between hypo- and normoresponders. In addition, the current study fills the gap in understanding the inter-patient variability of cell types in human preovulatory follicles, as revealed by single-cell analysis of follicular fluid cells.

Genome-Wide Association Study Demonstrates the Role Played by the CD226 Gene in Rasa Aragonesa Sheep Reproductive Seasonality

Simple Summary

To elucidate the genetic basis of reproductive seasonality in Rasa Aragonesa sheep breed, we performed a genome-wide association study (GWAS) in order to detect single nucleotide polymorphisms (SNPs) or regions associated with traits related to ovarian function and behavioural signs of estrous. The GWAS included 205 ewes with genotypes for 583882 SNPs. Only one SNP overcame the genome-wide significance level. Nine potential SNPs overcame the chromosome-wise significance level (FDR 10%). Gene annotation demonstrated that CD226molecule (CD226) and neuropeptide Y (NPY) genes that could be involved in reproductive seasonality were close to the significant SNPs. To validate the results, we sequenced the entire coding region of the NPY gene and four exons of the CD226 gene to search for polymorphisms that could be involved in the phenotypes studied. Two synonymous and two nonsynonymous SNPs in the NPY and CD226 genes, respectively, were genotyped in the whole population. We demonstrated that the AA genotype of the SNP rs404360094 located in exon 3 of the CD226 gene was associated with higher and lower total days of anoestrus and oestrous cycling months, respectively. Therefore, this SNP could be utilized as a genetic marker for assisted selection marker to reduce seasonality.

Abstract

A genome-wide association study (GWAS) was used to identify genomic regions influencing seasonality reproduction traits in Rasa Aragonesa sheep. Three traits associated with either ovarian function based on blood progesterone levels (total days of anoestrus and progesterone cycling months) or behavioral signs of oestrous (oestrous cycling months) were studied. The GWAS included 205 ewes genotyped using the 50k and 680k Illumina Ovine Beadchips. Only one SNP associated with the progesterone cycling months overcame the genome-wide significance level (rs404991855). Nine SNPs exhibited significant associations at the chromosome level, being the SNPs rs404991855 and rs418191944, that are located in the CD226 molecule (CD226) gene, associated with the three traits. This gene is related to reproductive diseases. Two other SNPs were located close to the neuropeptide Y (NPY) gene, which is involved in circadian rhythms. To validate the GWAS, partial characterization of both genes by Sanger sequencing, and genotyping of two synonymous and two nonsynonymous SNPs in the NPY and CD226 genes, respectively, were performed. SNP association analysis showed that only SNP rs404360094 in the exon 3 of the CD226 gene, which produces an amino acid substitution from asparagine (uncharged polar) to aspartic acid (acidic), was associated with the three seasonality traits. Our results suggest that the CD226 gene may be involved in the reproductive seasonality in Rasa Aragonesa.

Poor ovarian response is associated with serum vitamin D levels and pro-inflammatory immune responses in women undergoing in-vitro fertilization

Poor ovarian response (POR¹) limits the success of infertility treatment modality. In this study, we aim to investigate if POR is associated with serum 25(OH) vitamin D (VD²) levels and pro-inflammatory immune responses in infertile women with a history of in-vitro fertilization and embryo transfer failures. A retrospective cross-sectional study included 157 women with IVF failures. Study patients were divided into four groups based on serum 25(OH)VD level and ovarian responses during the most recent IVF cycle; low VD (LVD³) with POR, LVD with normal ovarian response (NOR⁴), normal VD (NVD⁵) with POR, and NVD with NOR. Serum 25(OH)VD level, cellular- and auto-immunity, and metabolic parameters, including homocysteine and plasminogen activator inhibitor-1 were investigated. Peripheral blood CD56⁺ NK cell levels (%) and NK cytotoxicity were significantly higher in POR-LVD when compared to the other groups (P < 0.05, respectively). CD19 + B and CD19+/5+ B-1 cell levels were significantly higher in women with POR-LVD as compared with those of NOR-LVD and POR-NVD (P < 0.05, respectively). TNF-α/IL-10 producing Th1/Th2 cell ratio of POR-LVD was significantly higher than those of POR-NVD and NOR-NVD (P < 0.05 respectively). Peripheral blood homocysteine level of POR-LVD was significantly higher than those of NOR-LVD and POR-NVD (P < 0.05 respectively). We conclude that assessment of cellular and autoimmune abnormalities and metabolic factors, such as homocysteine should be considered in women with POR and LVD. VD and folic acid supplementation may be explored further as a possible therapeutic option for POR with immune and metabolic etiologies.

Ovarian and endometrial immunity during the ovarian cycle

Immune tolerance is crucial for the successful pregnancy, while immune effectors and their products are required to safeguard a fetus from the infectious pathogens. The key immune effectors, such as T, B, and natural killer (NK) cells, monocytes, macrophages, and dendritic cells take part in regulating the immune responses at the maternal-fetal interface. The immune effectors become involved in intraovarian reproductive processes as well, such as ovulation, production of corpus luteum (CL) and its degeneration and determine the quality and evolution of the oocyte during the folliculogenesis. In the cycling endometrium, NK cells are rapidly infiltrated into the endometrium after ovulation and participate in angiogenesis and spiral artery remodeling process. In this study, we reviewed the characteristics and action mechanisms of immune effectors and their products in the peripheral blood, ovary, and endometrium during the ovarian cycle, since a comprehensive understanding of immune responses during the ovarian cycle and the time of implantation can help us to predict the pregnancy outcome and take effective measures for the prevention of potential obstetrical complications.

Gonadotrophin stimulation in IVF alters the immune cell profile in follicular fluid and the cytokine concentrations in follicular fluid and serum

Study question

Are the immune cell profiles and the cytokine concentrations in follicular fluid (FF) and serum at the preovulatory stage different in conventional exogenous gonadotrophin stimulated IVF (c-IVF) compared with natural cycle IVF (NC-IVF)?

Summary answer

The cell counts of CD45+ leucocytes and T cell subpopulations and the cytokine concentrations in FF and serum are different in c-IVF compared to NC-IVF.

What is known already

FF-derived cells are heterogeneous. Immune cells are involved in intra-ovarian processes and cytokines are required for normal follicular development. Gonadotrophins stimulate the regulatory intrafollicular system and influence the local distribution of immune cells and the intrafollicular release of cytokines. Administration of exogenous gonadotrophins may have a significant effect on this local regulatory system, which then in turn could influence oocyte quality.

Study design, size, duration

The study included 105 patients, 69 undergoing c-IVF and 36 undergoing NC-IVF. c-IVF was performed by exogenous ovarian stimulation with hMG and GnRH antagonists.

Participants/materials, setting, methods

FF samples were collected from the first dominant follicle in c-IVF without pooling and from single leading preovulatory follicles in NC-IVF. Three different approaches were used to analyze FF samples: (i) microscopic investigation of CD45+ leucocytes, (ii) fluorescence-activated cell sorting to determine CD19+ B cells and CD3+ T cells including T cell subpopulations (CD4+, CD8+), and (iii) evaluation of tumour necrosis factor-alpha (TNF-α), interferon-gamma (INF-γ), interleukins (IL)-2, -6, -8, -10 and vascular endothelial growth factor (VEGF) levels in matched FF and serum samples using the Bio-Plex® platform.

Main results and the role of chance

FF obtained from c-IVF contained proportionally more CD45+ leucocytes (P = 0.0384), but fewer CD8+ cytotoxic T cells than FF from NC-IVF. CD3+ T lymphocytes were the most common type of lymphocytes, and the number thereof was comparable in the two study groups. In c-IVF, serum VEGF levels were higher (P = 0.007) than in NC-IVF while FF contained marginally decreased concentrations of IL-8 in c-IVF in comparison to NC-IVF. The cytokine concentration gradient between FF and serum in c-IVF was 10-fold for IL-8 and 8-fold for VEGF and thereby markedly lower than in NC-IVF, where the differences were 32-fold and 30-fold, respectively. Strong positive correlations were determined between FF- IL-10 and FF- VEGF in c-IVF (r = 0.85, P < 0.0001) and in NC-IVF (r = 0.81, P < 0.0001).

Large scale data

N/A.

Limitations, reasons for caution

The ovulation of NC-IVF follicles was induced by the exogenous administration of hCG, which means that the environment did not fully correspond to the physiological situation.

Wider implications of the findings

The differences in the immune profile and the cytokine concentrations in c-IVF and NC-IVF follicles support the hypothesis that conventional ovarian stimulation affects indirectly and heterogeneously the intrafollicular milieu, and thereby possibly affects the oocyte quality and the IVF outcome. However, further studies are needed to confirm our findings and to refine stimulation protocols in the context of optimizing the intrafollicular environment during oocyte maturation.

Study funding/competing interest(s)

The study was supported by a research grant from IBSA Institut Biochimique SA and MSD Merck Sharp & Dohme GmbH. The authors are clinically involved in low dose mono-follicular stimulation and IVF-therapies, using gonadotrophins from all gonadotrophins distributors on the Swiss market, including Institut Biochimique SA and MSD Merck Sharp & Dohme GmbH.

Detection of dendritic cells and related cytokines in follicular fluid of patients with polycystic ovary syndrome

PROBLEM

The presence of dendritic cells (DCs) and associated cytokines in follicular fluid (FF) from patients with polycystic ovary syndrome (PCOS) remains unknown.

METHODS OF STUDY

FF was collected from PCOS patients and patients with severe male factor infertility (control) at the day of transvaginal oocyte retrieval. Phenotypes of DC were detected by flow cytometry, and TNF-α, IL-6, IL-10, and IL-23 were assessed by ELISA.

RESULTS

A significant decrease in the percentage of DC was found in patients with PCOS (16.22±5.5%) compared with control (21.27±5.5%, P<.01). E₂ on the day of hCG administration was correlated positively with the mean fluorescence intensity of HLA-DR (r=.75, P<.01) and reversely correlated with the concentration of TNF-α in FF (r=-.69, P<.01). The level of TNF-α, IL-6, and IL-10 increased significantly but IL-23 decreased in FF from patients with PCOS.

CONCLUSION

The decrease of DC and disturbance of associated cytokines in FF from PCOS patients indicates a disorder of immunological microenvironment of the ovarian follicle, which might be involved in the dysfunction of folliculogenesis.

Natural killer cells in female infertility and recurrent miscarriage: a systematic review and meta-analysis

INTRODUCTION Embryo implantation is a complex process involving maternal hormonal changes, immune responses and maturational events in the embryo. A pregnancy could fail when these events are not synchronized. It is speculated that in women, an elevation of natural killer (NK) cells may have an effect on reproductive performance, and NK cell levels in blood are currently being used as a diagnostic test to guide the initiation of therapies in patients with infertility. METHODS We conducted a systematic review to evaluate the (i) levels of NK cells in blood and endometrium in infertile versus fertile women, (ii) association between NK cells and IVF outcome, (iii) levels of NK cells in blood and endometrium in women with recurrent miscarriage (RM) versus controls. The following electronic databases were searched: Medline, EMBASE, Cochrane Library, Web of Science and National Research Register. RESULTS A total of 22 studies were included. Meta-analysis of studies that evaluated peripheral and uterine NK (uNK) cell percentages in infertile versus fertile women showed no significant difference between the two groups [standardized mean difference (SMD) -0.33; 95% confidence intervals (CI) -1.06, 0.4; P = 0.37; SMD -1.82; 95% CI -4.80, 1.17; P = 0.23 respectively]. Pooling of studies that reported peripheral NK cells as numbers showed significantly higher NK cell numbers in infertile women compared with fertile controls (SMD 3.16; 95% CI 1.07, 5.24; P = 0.003). Meta-analysis of studies that evaluated the role of NK cells in IVF outcome showed no significant difference in live birth rates in women with elevated NK cells or NK cell activity compared with women without elevated peripheral NK cells or NK cell activity (NK activity assessed using a cytotoxicity assay) (relative risk 0.57; 95% CI 0.06, 5.22; P = 0.62). Meta-analysis of studies that evaluated peripheral NK cell percentages in women with RM versus controls showed significantly higher NK cell percentages in women with RM (SMD 1.36; 95% CI 0.04, 2.69; P = 0.04). Meta-analysis of studies that evaluated peripheral NK cell numbers showed significantly higher NK cell numbers in women with RM compared with controls (SMD 0.81; 95% CI 0.47, 1.16; P < 0.00001). Meta-analysis of studies that evaluated uNK cells showed no significant difference in women with RM compared with controls (SMD 0.40; 95% CI -1.24, 2.04; P = 0.63). CONCLUSIONS Further research is needed before NK cell assessment can be recommended as a diagnostic tool in the context of female infertility or RM. There is no clear explanation as to why the results differ when data for NK cells are expressed as numbers or a percentage. On the basis of current evidence, NK cell analysis and immune therapy should be offered only in the context of clinical research.

Association of the leukemia inhibitory factor gene mutation and the antiphospholipid antibodies in the peripheral blood of infertile women

To characterize the impact of the potentially functional mutation--the G to A transition at the position 3400 of the leukemia inhibitory factor (LIF; a pluripotent cytokine that plays a central role in the control of the embryo implantation) gene that leads to the exchange of valine with methionine at codon 64 we evaluated the association of the LIF gene mutation and the levels of antiphospolipid antibodies (aPLs) in the peripheral blood of infertile women (the aPLs examination was part of our routine immunological test during the infertility check-up). Eight infertile mutation-positive women were diagnosed with idiopathic infertility (n=5) and endometriosis (n=3) and their levels of aPLs in serum were compared with 115 infertile women without any LIF gene mutation. Enzyme-linked immunosorbent assay was used for the detection of seven antiphospholipid antibodies; the results were statistically assessed by the Fisher's 2 by 2 exact test to evaluate the association of the LIF gene mutations and aPLs in serum of infertile patients. The presence of aPLs was significantly higher in our study group (100%) than in 30% of aPLs-positives in control infertile patients (p = 0.0035) which indicates that the aPLs are elevated in women with LIF gene mutations.

Characterization and depletion of leukocytes from cells isolated from the pre-ovulatory ovarian follicle

BACKGROUND

Cells isolated from the periovulatory ovarian follicle are often used as a model of ovarian steroidogenesis and corpus luteum formation. The follicular fluid-derived cell (FFDC) population is, however, heterogeneous and in addition to granulosa-lutein cells, non-steroidogenic cells are also present. These non-steroidogenic cells, especially the immune cells, may have important biological functions in this model. Here, we describe a method to isolate FFDC, characterize the phenotype of the immune cells and deplete immune cells from FFDC.

METHODS AND RESULTS

Follicular fluid aspirated transvaginally during IVF was clarified by centrifugation and enzymatic dispersion, labelled for leukocyte-specific markers and analysed by flow cytometry. Leukocytes constituted 22% of FFDC and expressed macrophage/dendritic cell, monocyte and lymphocyte markers. Leukocytes were depleted with anti-CD45-conjugated immunobeads, resulting in an FFDC population with <1.9% leukocytes. Leukocyte-containing FFDC secreted more interleukin-8 in culture than leukocyte-depleted FFDC.

CONCLUSION

Leukocyte-depleted FFDC may serve as a useful model to study the interaction of immune cells and luteinizing cells during corpus luteum formation.

Natural killer cells and reproductive failure

PURPOSE OF REVIEW

The purpose of this review is to provide an update of what is known about the role of natural killer cells in reproduction.

RECENT FINDINGS

In humans, natural killer cells are present in abundance in the uterus and appear to play an important role in early pregnancy. Women with reproductive failure have been shown to have higher levels of natural killer cell numbers and activity in peripheral blood. The evidence relating to uterine natural killer cells, however, is contradictory. While earlier studies suggested an increase of uterine natural killer cells in women with recurrent pregnancy loss, more recent investigations have not confirmed this trend. Uterine natural killer cell number or activity appear to be higher in spontaneous abortions with normal chromosomes compared with chromosomally abnormal pregnancies. Furthermore, a rise of the cytotoxic CD56(dim)CD16+ natural killer cell subset is seen in the follicular fluid of patients with idiopathic infertility and it is postulated that this increase may decrease fertilization rates in this group.

SUMMARY

Natural killer cell number and activity appear to be altered in women with reproductive failure although it is unclear if the difference is a cause or effect of reproductive failure. Whether natural killer cells are increased or decreased depends on whether peripheral blood, endometrium or first-trimester decidua is analyzed. Until more is known about the role of natural killer cells in normal pregnancy, there does not appear to be any benefit in offering natural killer cell testing to women with reproductive failure outside of research protocols.