Cervico-vaginal secretion cytokine profile: A non-invasive approach to study the endometrial receptivity in IVF cycles

Associations between cytokines and the risk of female and male infertility: A two-sample Mendelian randomization analysis

PURPOSE

Observational studies have linked cytokines to the occurrence of female and male infertility. However, it is not clear how biomarkers of inflammation are causally related to infertility. To explore whether genetic variants in circulating cytokines are associated with the pathogenesis of infertility, we performed two-sample Mendelian randomization (MR) analysis.

METHODS

A total of 31,112 individuals of European ancestry were included in a genome-wide association study (GWAS) of 47 circulating cytokines as instrumental variables (IVs). Outcome data were female infertility, including four different subtypes, and male infertility, from the FinnGen consortium. Five MR methods, including inverse-variance weighted (IVW), MR-Egger, simple mode, weighted median, and weighted mode were employed to examine the genetic association between cytokines and the risk of female infertility and male infertility. The false discovery rate (FDR) was controlled using the Benjamini-Hochberg method.

RESULTS

After FDR correction, cis-protein quantitative trait locus (cis-pQTL) instruments showed that the cytokines GROa and MCSF were positively associated with female infertility. In analyses of subtypes of female infertility, eotaxin and sICAM were inversely associated with ovulation-related infertility; MCP3 alone was positively associated with uterus-related infertility; GROa and MCSF were positively correlated with infertility of cervical, vaginal, and other or unspecified origin; and MIP1a was negatively correlated with tubal origin infertility. The cytokines HGF, IL-2ra, and RANTES were positively correlated with male infertility. Similar findings were obtained in sensitivity analyses. There was no evidence of pleiotropy or heterogeneity in the results.

CONCLUSION

These findings contribute to current understanding of the role of cytokine biomarkers in the etiology of female and male infertility. Furthermore clinical experimental validation is required to evaluate the potential of these cytokines as biomarkers.

DNA Methylation of Window of Implantation Genes in Cervical Secretions Predicts Ongoing Pregnancy in Infertility Treatment

Window of implantation (WOI) genes have been comprehensively identified at the single cell level. DNA methylation changes in cervical secretions are associated with in vitro fertilization embryo transfer (IVF-ET) outcomes. Using a machine learning (ML) approach, we aimed to determine which methylation changes in WOI genes from cervical secretions best predict ongoing pregnancy during embryo transfer. A total of 2708 promoter probes were extracted from mid-secretory phase cervical secretion methylomic profiles for 158 WOI genes, and 152 differentially methylated probes (DMPs) were selected. Fifteen DMPs in 14 genes (BMP2, CTSA, DEFB1, GRN, MTF1, SERPINE1, SERPINE2, SFRP1, STAT3, TAGLN2, TCF4, THBS1, ZBTB20, ZNF292) were identified as the most relevant to ongoing pregnancy status. These 15 DMPs yielded accuracy rates of 83.53%, 85.26%, 85.78%, and 76.44%, and areas under the receiver operating characteristic curves (AUCs) of 0.90, 0.91, 0.89, and 0.86 for prediction by random forest (RF), naïve Bayes (NB), support vector machine (SVM), and k-nearest neighbors (KNN), respectively. SERPINE1, SERPINE2, and TAGLN2 maintained their methylation difference trends in an independent set of cervical secretion samples, resulting in accuracy rates of 71.46%, 80.06%, 80.72%, and 80.68%, and AUCs of 0.79, 0.84, 0.83, and 0.82 for prediction by RF, NB, SVM, and KNN, respectively. Our findings demonstrate that methylation changes in WOI genes detected noninvasively from cervical secretions are potential markers for predicting IVF-ET outcomes. Further studies of cervical secretion of DNA methylation markers may provide a novel approach for precision embryo transfer.

The Bacterial DNA Profiling of Chorionic Villi and Amniotic Fluids Reveals Overlaps with Maternal Oral, Vaginal, and Gut Microbiomes

The in utero microbiome hypothesis has been long debated. This hypothesis will change our comprehension of the pioneer human microbiome if proved correct. In 60 uncomplicated pregnancies, we profiled the microbiome of chorionic villi (CV) and amniotic fluids (AF) in relation to maternal saliva, rectum, and vagina and the soluble cytokines cascade in the vagina, CV and AF. In our series, 12/37 (32%) AF and 10/23 (44%) CV tested positive for bacterial DNA. CV and AF harbored bacterial DNA of Streptococcus and Lactobacillus, overlapping that of the matched oral and vaginal niches, which showed a dysbiotic microbiome. In these pregnant women, the immune profiling revealed an immune hyporesponsiveness in the vagina and a high intraamniotic concentration of inflammatory cytokines. To understand the eventual role of bacterial colonization of the CV and AF and the associated immune response in the pregnancy outcome, further appropriate studies are needed. In this context, further studies should highlight if the hematogenous route could justify the spread of bacterial DNA from the oral microbiome to the placenta and if vaginal dysbiosis could favor the likelihood of identifying CV and AF positive for bacterial DNA.

Cervical Secretion Methylation Is Associated with the Pregnancy Outcome of Frozen-Thawed Embryo Transfer

The causes of implantation failure remain a black box in reproductive medicine. The exact mechanism behind the regulation of endometrial receptivity is still unknown. Epigenetic modifications influence gene expression patterns and may alter the receptivity of human endometrium. Cervical secretions contain endometrial genetic material, which can be used as an indicator of the endometrial condition. This study evaluates the association between the cervical secretion gene methylation profile and pregnancy outcome in a frozen-thawed embryonic transfer (FET) cycle. Cervical secretions were collected from women who entered the FET cycle with a blastocyst transfer (36 pregnant and 36 non-pregnant women). The DNA methylation profiles of six candidate genes selected from the literature review were measured by quantitative methylation-specific PCR (qMSP). Bioinformatic analysis of six selected candidate genes showed significant differences in DNA methylation between receptive and pre-receptive endometrium. All candidate genes showed different degrees of correlation with the pregnancy outcomes in the logistic regression model. A machine learning approach showed that the combination of candidate genes' DNA methylation profiles could differentiate pregnant from non-pregnant samples with an accuracy as high as 86.67% and an AUC of 0.81. This study demonstrated the association between cervical secretion methylation profiles and pregnancy outcomes in an FET cycle and provides a basis for potential clinical application as a non-invasive method for implantation prediction.

Evaluation of cytokine profile in cervicovaginal lavage specimens of women having asymptomatic reproductive tract infections

Reproductive tract infections (RTIs) such as vaginal candidiasis and bacterial vaginosis (BV) are common among sexually active women and can be both symptomatic or asymptomatic. The microbiota of the reproductive tract triggers immune response at the cervicovaginal interface resulting in secretion of cytokines during the course of these RTIs. The objective of this study was to evaluate the cytokine profile in cervicovaginal lavage of women having asymptomatic vaginal infections. Measurement of vaginal cytokines was done for various interleukins including IL-1β, IL-6, IL-8, IL-10, IL-12/IL23p40, IL-17A, tumour necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ) by ProcartaPlex™ Multiplex Immunoassay. Women having vaginal Candida infection had increased concentration of IL-1β (p=.01), IL-6 (p=.007), IL-8 (p=.327), IL-12/IL23p40 (p=.049) and IFN-γ (p=.125). The results of our study suggest that evaluation of these cytokines could be explored as an additional measure to determine host inflammatory response in women having asymptomatic vaginal candidiasis.Impact StatementWhat is already known on this subject? Studies assessing the vaginal cytokine profile to assess the vaginal milieu in various cohorts such as post-menopausal women, pregnant women, women with history of preterm birth, CIN and scheduled IVF cycle are being undertaken. Variable cytokine response has been reported in literature in women with symptomatic bacterial vaginosis and Candida infection. However, much less is known about vaginal cytokine profile in asymptomatic infection.What do the results of this study add? The results of the study show increased concentration of the pro-inflammatory cytokines IL-1β, IL-6 IL-8, IL-12/IL23p40 and interferon gamma (IFN-γ) in women having asymptomatic Candida, vaginal leucocytosis and raised vaginal pH.What are the implications of these findings for clinical practice and/or further research? Evaluation of vaginal cytokine profile (IL-1β, IL-6 IL-8, IL-1β, IL-12/IL23p40 and IFN-γ) could be explored as an additional measure to determine inflammation in asymptomatic women. Vaginal cytokines (IL-1β, IL-6 IL-8, IL-1β, IL-12/IL23p40 and IFN-γ) could be used further for development of a point of care test.

Genome-wide analysis of cervical secretions obtained during embryo transfer reveals the association between deoxyribonucleic acid methylation and pregnancy outcomes

OBJECTIVE

To study whether the methylation status of cervical secretions can reflect the ability of the endometrium to allow embryo implantation.

DESIGN

Case-control study.

SETTING

In vitro fertilization centers.

PATIENT(S)

Women undergoing embryo transfer cycles, in which at least 1 good-quality embryo was transferred.

INTERVENTION(S)

Collection of cervical secretions during the procedure of embryo transfer.

MAIN OUTCOME MEASURE(S)

Methylation profiles of cervical secretions in relation to pregnancy outcomes.

RESULT(S)

Genome-wide methylation profiles differ between cervical secretions from pregnancy and nonpregnancy cycles. Clustering analysis on the basis of the top 2,000 differentially methylated probes of cervical secretions from 28 pregnancy and 29 nonpregnancy cycles correctly categorized 86.0% of the samples in terms of conceptional status, which was verified in selected genes by quantitative methylation-specific polymerase chain reaction and validated in another independent sample set. The combination of selected genes was estimated to predict pregnancy outcomes with a maximal area under the receiver operating characteristic curve of 0.83.

CONCLUSION(S)

The methylation profiles of cervical secretions were associated with pregnancy outcomes in embryo transfer cycles. Although not clinically useful at present, deoxyribonucleic acid methylation in cervical secretions may shed new light on the less invasive assessment of endometrial receptivity.

Mucosal biomarkers for endometrial receptivity: A promising yet underexplored aspect of reproductive medicine

Annually, approximately 2 million assisted reproductive technology (ART) procedures are performed worldwide, of which, only ~25% lead to successful delivery. There are two major factors contributing to successful implantation: embryo quality and endometrial receptivity (ER). Although embryo quality might be assessed through morphological and genetic testing, no clinically approved techniques are available to evaluate ER. Mucus in different parts of the female reproductive tract contains many cytokines, chemokines, growth factors, and nucleic acids, which influence and reflect various implantation-related processes. Therefore, the aim of the present review was to summarize available data regarding noninvasively obtained mucosal biomarkers for ER and to investigate their ability to predict the outcome of ART procedures. A broad literature search was performed to define studies related to noninvasive ER assessments. More than 50 biomarkers detectable in endometrial fluid, embryo transfer cannula leftover cells and mucus, menstrual blood, cervicovaginal washings are discussed herein. The remarkable methodological heterogeneity of the reviewed studies complicates the comparison of their results. Nevertheless, certain promising analytical targets may already be identified, such as urocortin, activin A, IL-1β, TNF-α, IP-10, MCP-1, and several oxidative stress biomarkers. The present review contains a collection of currently available mucosal biomarker-related data, which may provide insights for future studies.Abbreviations: ART: assisted reproductive technology; ER: endometrial receptivity; IVF: in vitro fertilization; ICSI: intracytoplasmic sperm injection; IUI: intrauterine insemination; MeSH: Medical Subject Headings; hDP 200: human decidua-associated protein 200; ET: embryo transfer; IL-18: Interleukin-18; LRG: leucine-rich α2-glycoprotein; ROC: receiver operating characteristic; AUC: area under the ROC-curve; LH: luteinizing hormone; LIF: leukemia inhibitory factor; TNF-α: tumor necrosis factor alpha; IFN-γ: interferon γ; MCP-1: monocyte chemoattractant protein-1; VEGF: vascular endothelial growth factor; SOD: superoxide dismutase; CAT: catalase; LPO: lipid peroxidation; TTG: total thiol groups; TAP: total antioxidant power; CE: chronic endometritis.

Interleukin-9 produced by helper T cells stimulates interleukin-8 expression in endometriosis

PROBLEM

Inflammation and immune responses play crucial roles in the development of endometriosis. Although interleukin-9 (IL-9) has a pro-inflammatory function in chronic inflammatory diseases, its function in endometriosis remains unknown. Here, we aimed to investigate the significance of IL-9 and IL-9-producing lymphocytes in endometriosis.

METHOD OF STUDY

Specimens were obtained from patients with and without endometriosis. Peritoneal fluid (PF), peripheral blood (PB), and ovarian endometrioma (OE) tissues were analyzed for the proportion of CD4⁺ IL-9⁺ lymphocytes and IL-9 concentration using flow cytometry and enzyme-linked immunosorbent assay. OE, endometrium with endometriosis (EE), and normal endometrium (NE) were analyzed for IL-9 receptor (IL-9R) expression using immunohistochemical staining. IL-9-dependent changes in Interleukin-8 (IL-8) expression in endometrial stromal cells from OE (OESCs) were evaluated using real-time PCR.

RESULTS

The proportion of CD4⁺ IL-9⁺ lymphocytes was higher in the PF, but not the PB, of patients with endometriosis than individuals without endometriosis (p < .05). However, IL-9 levels in the PF did not differ between those with and without endometriosis. We detected CD4+ IL-9+ lymphocytes in OE tissues and IL-9R in OE tissues and OESCs. In OESC culture, IL-9 significantly elevated IL-8 expression in a dose-dependent manner (p < .05), which was nullified by the addition of the anti-IL-9 receptor antibody. Furthermore, IL-9 additively stimulated IL-8 expression in the presence of TNF-α (p < .05).

CONCLUSION

Our findings show that IL-9 produced by helper T cells induces IL-8 expression, suggesting that IL-9 plays an important role in the development of endometriosis by stimulating IL-8 expression.

Macrophage migration inhibitory factor in human early pregnancy events and association with placental pathologies

Macrophage migration inhibitory factor (MIF) is a versatile cytokine acting as an important regulator of innate and adaptive immunity and implicated in many physiological and pathological processes. It is abundantly expressed at the feto-maternal interface and proposed to have a role in establishing and maintaining a healthy pregnancy. This review presents the current literature data regarding the MIF role in early pregnancy events and its association with some of the placental pathological conditions, including infection, preeclampsia, gestational diabetes mellitus and choriocarcinoma. General information regarding MIF structure and function is followed by an overview of its expression in reproductive tissues and in pregnancy. Futher, we discuss MIF's involvement in the survival of decidual stromal cells, placenta of the first trimester of pregnancy, and in trophoblast cell functions studied in vitro. Current findings associating this cytokine to placental infection, preeclampsia, gestational diabetes mellitus and choriocarcinoma are presented in the final part.

Does bacterial colonization during embryo transfer have an impact on pregnancy rate in ICSI? : Tunisian preliminary results

INTRODUCTION

Embryos' transfer into the uterine cavity remains a limiting factor in the success of intracytoplasmic sperm injection (ICSI). This study aimed to evaluate the impact of cervico-vaginal colonization on ICSI outcomes.

MATERIEL AND METHODS

Longitudinal, prospective and analytical study, conducted from February 1 st to October 31 st, 2017. On the day of embryos' transfer, patients with the following criteria were included: Age ≤ 40, normal uterine ultrasound and hysteroscopy, first or second attempt of ICSI, use of fresh semen and transfer of at least one good quality embryo. Three samples were done for microbiological analysis: vaginal secretions, cervical mucus and the tip of the transfer catheter.

RESULTS

The study included 40 patients. Pregnancy rate was 52.5 %. Catheter contamination occurred in nine cases (22.5 %). The most frequently isolated bacteria were Streptococcus anginosus (37 % of cases), Gardnerella vaginalis (27 % of cases) and Streptococcus agalactiae (18 % of cases). In all cases of contamination, the same bacteria were found also in the vagina and cervical mucus. In cases of contamination with Gardnerella vaginalis, the study of vaginal flora showed bacterial vaginosis. No pregnancy was obtained when contamination of the transfer catheter occurred. In the absence of contamination, pregnancy rate was 61.2 % (ρ = 0.003). Both populations (patients with catheter contamination and patients without catheter contamination) were comparable regarding epidemiological characteristics and ICSI attempt data.

CONCLUSION

Contamination of the transfer catheter by cervical-vaginal bacteria appears to affect IVF results. Systematic antibiotic prophylaxis could be proposed to reduce this negative impact.

The Vaginal Community State Types Microbiome-Immune Network as Key Factor for Bacterial Vaginosis and Aerobic Vaginitis

Regarding bacterial vaginosis (BV), the relevance of the vaginal microbiota to the women’s health fulfills a key role, but knowledge gaps regarding aerobic vaginitis (AV) exist. This study aims to characterize vaginal microbiome and its relationship with the local immune mediators, providing an opportunity to define the link between vaginal commensal microorganisms and opportunistic pathogens in the relation of a given vaginal community state type (CST). A total of 90 vaginal samples from Caucasian asymptomatic women of reproductive age (18–40 years) attending the yearly examination and not reporting any vaginal complaints were retrospectively evaluated for microbiome assessment and immune factor dosage. The samples were tested by the Ion Torrent PGM and the Luminex Bio-Plex technologies for the analysis of microbiome and immune factors, respectively. In our study, the CST classification together with the local immune response profiling represented a good predictive indicator of the vaginal health, suggesting that the predominance of a specific Lactobacillus and its relative abundance are pivotal elements to maintain a physiologic status. A vaginal colonization from Bifidobacterium may absolve a protective role similar to that of Lactobacillus, corresponding to a newly identified CST, although studies are needed to better clarify its clinical significance. Moreover, within each CST, a different pattern of inflammation is activated and orchestrated both by the dominant Lactobacillus spp. and by specific non-Lactobacillus bacteria and can give insights into the pathogenic mechanisms. In conclusion, this study contributes to the characterization of vaginal dysbiosis, reshaping this concept by taking into consideration the CST profiling, local immune marker, and immune–microbial network.