Lactobacillus crispatus promotes invasion of the HTR-8/SVneo trophoblast cell line

Pharmacological and non-pharmacological interventions for improving endometrial receptivity in infertile patients with polycystic ovary syndrome: a comprehensive review of the available evidence

Direct and indirect evidence suggests that endometrial receptivity may play a crucial role in the reduced fertility rate of women with polycystic ovary syndrome (PCOS). Various pharmacological and non-pharmacological strategies with potential effects on endometrial receptivity in patients with PCOS have been proposed. The aim of this study was to summarize the rationale and the clinical and experimental evidence of interventions tested for improving endometrial receptivity in infertile patients with PCOS. A systematic review was conducted by consulting electronic databases. All interventions with a potential influence on endometrial receptivity in infertile patients with PCOS were evaluated, and their main biological mechanisms were analysed. In total, 24 interventions related to endometrial receptivity were identified. Notwithstanding a strong biological rationale, no intervention aimed at improving endometrial receptivity in women with PCOS is supported by an adequate body of evidence, limiting their use in clinical practice. Further high-quality research is needed in this field to limit potentially ineffective and unsafe add-on treatments in infertile patients with PCOS.

Less is more! Low amount of Fusobacterium nucleatum supports macrophage-mediated trophoblast functions in vitro

F. nucleatum, involved in carcinogenesis of colon carcinomas, has been described as part of the commensal flora of the female upper reproductive tract. Although its contribution to destructive inflammatory processes is well described, its role as commensal uterine bacteria has not been thoroughly investigated. Since carcinogenesis shares similar mechanisms with early pregnancy development (including proliferation, invasion, blood supply and the induction of tolerance), these mechanisms induced by F. nucleatum could play a role in early pregnancy. Additionally, implantation and placentation require a well-balanced immune activation, which might be suitably managed by the presence of a limited amount of bacteria or bacterial residues. We assessed the effect of inactivated F. nucleatum on macrophage-trophoblast interactions. Monocytic cells (THP-1) were polarized into M1, M2a or M2c macrophages by IFN-γ, IL-4 or TGF-β, respectively, and subsequently treated with inactivated fusobacteria (bacteria:macrophage ratio of 0.1 and 1). Direct effects on macrophages were assessed by viability assay, flow cytometry (antigen presentation molecules and cytokines), qPCR (cytokine expression), in-cell Western (HIF and P-NF-κB) and ELISA (VEGF secretion). The function of first trimester extravillous trophoblast cells (HTR-8/SVneo) in response to macrophage-conditioned medium was microscopically assessed by migration (scratch assay), invasion (sprouting assay) and tube formation. Underlying molecular changes were investigated by ELISA (VEGF secretion) and qPCR (matrix-degrading factors and regulators). Inflammation-primed macrophages (M1) as well as high bacterial amounts increased pro-inflammatory NF-κB expression and inflammatory responses. Subsequently, trophoblast functions were impaired. In contrast, low bacterial stimulation caused an increased HIF activation and subsequent VEGF-A secretion in M2c macrophages. Accordingly, there was an increase of trophoblast tube formation. Our results suggest that a low-mass endometrial/decidual microbiome can be tolerated and while it supports implantation and further pregnancy processes.

Unraveling the molecular mechanisms driving enhanced invasion capability of extravillous trophoblast cells: a comprehensive review

Precise extravillous trophoblast (EVT) invasion is crucial for successful placentation and pregnancy. This review focuses on elucidating the mechanisms that promote heightened EVT invasion. We comprehensively summarize the pivotal roles of hormones, angiogenesis, hypoxia, stress, the extracellular matrix microenvironment, epithelial-to-mesenchymal transition (EMT), immunity, inflammation, programmed cell death, epigenetic modifications, and microbiota in facilitating EVT invasion. The molecular mechanisms underlying enhanced EVT invasion may provide valuable insights into potential pathogenic mechanisms associated with diseases characterized by excessive invasion, such as the placenta accreta spectrum (PAS), thereby offering novel perspectives for managing pregnancy complications related to deficient EVT invasion.

The role of the endometrial microbiome in embryo implantation and recurrent implantation failure

There is a suggested pathophysiology associated with endometrial microbiota in cases where repeated implantation failure of high-quality embryos is observed. However, there is a suspected association between endometrial microbiota and the pathogenesis of implantation failure. However, there is still a lack of agreement on the fundamental composition of the physiological microbiome within the uterine cavity. This is primarily due to various limitations in the studies conducted, including small sample sizes and variations in experimental designs. As a result, the impact of bacterial communities in the endometrium on human reproduction is still a subject of debate. In this discourse, we undertake a comprehensive examination of the existing body of research pertaining to the uterine microbiota and its intricate interplay with the process of embryo implantation.

Inflammatory responses in early pregnancy: Physiological and pathological perspectives

Background

Several conditions such as infertility, repeated implantation failure, and recurrent pregnancy loss can pose challenges in early pregnancy. These issues can be caused by the abnormal inflammatory response with various factors, including exogenous and endogenous agents, and pathogenic and nonpathogenic agents. In addition, they can be exacerbated by maternal immune response to the abovementioned factors.

Methods

This review aimed to assess the detrimental inflammatory effects of chronic endometritis, endometrial microbiota disturbance, and maternal immune system abnormalities on early pregnancy. Further, essential details such as ovulation, implantation, trophoblast invasion, and placental formation, were examined, thereby highlighting the beneficial roles of inflammation.

Main Findings

Excessive inflammation was associated with various early pregnancy disorders. Meanwhile, a lack of appropriate inflammation could also contribute to the development of different early pregnancy complications.

Conclusion

Excessive inflammation and insufficient inflammation can possibly lead to abnormal conditions in early pregnancy, and appropriate inflammation is required for a successful pregnancy.

Impact of Lactobacillus in the uterine microbiota on in vitro fertilization outcomes

Abundant intrauterine Lactobacillus is associated with good in vitro fertilization (IVF) outcomes; however, whether specific species of Lactobacillus have any benefit remains unclear. So we examine the effect of Lactobacillus on the clinical outcomes of IVF at the species level. Uterine microbiota were classified as either Lactobacillus-dominant (LD) or non-Lactobacillus-dominant. In the LD group, we further investigated the clinical results for each Lactobacillus species and evaluated them in relation to IVF outcomes. In Uterine microbiome analysis, Lactobacillus was the most abundant, with the four species of L. crispatus, L. iners, L. gasseri, and L. jensenii accounting for the great majority. We compared the clinical outcomes of single frozen-thawed embryo transfer conducted by Lactobacillus species and found that the implantation rate was lowest in those in whom L. iners was dominant. This study is the first to conduct a species-level analysis of the uterine microbiota and report on a detailed investigation of Lactobacillus, which was believed to be particularly helpful for pregnancy.

Pregnancy outcomes after vaginal probiotic supplementation before frozen embryo transfer: a randomized controlled study

In women receiving assisted reproductive treatment, intrauterine lactobacilli dominance has been associated with higher rates of pregnancy achievement. This randomized controlled trial conducted in the fertility clinic of the university hospital from 7 August 2019 to May 2021, aimed to compare the clinical outcome of embryo transfer in frozen-thaw cycles with Lactobacillus supplementation prior to embryo transfer and the standard treatment. A total of 340 infertile women underwent randomization. The biochemical and clinical pregnancy rates were comparable between the groups (39.9 and 34.2% in the study group vs. 41.8 and 31.7% in the control group); however, the miscarriage rate was significantly decreased in the study group (9.5 vs. 19.1%, respectively, p = 0.02), [OR = 0.44, 95% CI (0.23, 0.86)]. Among 49 women diagnosed with bacterial vaginosis, the live birth rate in the study group was higher than the control group (42.31 vs. 26.09%, p = 0.23), [OR = 2.08, 95% CI (0.62, 6.99)]. In the blastocyst transfer group (n = 206), the live birth rate was significantly higher in the study group than in the control group (35.71 vs. 22.22%, p = 0.03) [OR = 1.9, 95% CI (1.05, 3.59)]. Therefore, intravaginal lactobacilli supplementation before embryo transfer in the frozen-thaw cycle did not improve the biochemical and clinical pregnancy rate in the general population but significantly reduced the miscarriage rate.Trial Registration: TCTR20190429001 (29/04/2019) @ www.thaiclinicaltrials.org .

IFITM1 inhibits trophoblast invasion and is induced in placentas associated with IFN-mediated pregnancy diseases

Interferon-induced transmembrane proteins (IFITMs) are restriction factors that block many viruses from entering cells. High levels of type I interferon (IFN) are associated with adverse pregnancy outcomes, and IFITMs have been shown to impair the formation of syncytiotrophoblast. Here, we examine whether IFITMs affect another critical step of placental development, extravillous cytotrophoblast (EVCT) invasion. We conducted experiments using in vitro/ex vivo models of EVCT, mice treated in vivo with the IFN-inducer poly (I:C), and human pathological placental sections. Cells treated with IFN-β demonstrated upregulation of IFITMs and reduced invasive abilities. Transduction experiments confirmed that IFITM1 contributed to the decreased cell invasion. Similarly, migration of trophoblast giant cells, the mouse equivalent of human EVCTs, was significantly reduced in poly (I:C)-treated mice. Finally, analysis of CMV- and bacterial-infected human placentas revealed upregulated IFITM1 expression. These data demonstrate that high levels of IFITM1 impair trophoblast invasion and could explain the placental dysfunctions associated with IFN-mediated disorders.

Female reproductive tract-organ axes

The female reproductive tract (FRT) and remote/versatile organs in the body share bidirectional communication. In this review, we discuss the framework of the "FRT-organ axes." Each axis, namely, the vagina-gut axis, uterus-gut axis, ovary-gut axis, vagina-bladder axis, vagina-oral axis, uterus-oral axis, vagina-brain axis, uterus-brain axis, and vagina-joint axis, is comprehensively discussed separately. Each axis could be involved in the pathogenesis of not only gynecological diseases but also diseases occurring apart from the FRT. Although the microbiota is clearly a key player in the FRT-organ axes, more quantitative insight into the homeostasis of the microbiota could be provided by host function measurements rather than current microbe-centric approaches. Therefore, investigation of the FRT-organ axes would provide us with a multicentric approach, including immune, neural, endocrine, and metabolic aspects, for understanding the homeostatic mechanism of women's bodies. The framework of the FRT-organ axes could also provide insights into finding new therapeutic approaches to maintain women's health.

Enhancement of Rubella Virus Infection in Immortalized Human First-Trimester Trophoblasts Under Low-Glucose Stress Conditions

Rubella virus (RuV) infections in pregnant women, especially first-trimester infections, can lead to congenital rubella syndrome (CRS). However, the mechanisms of fetal RuV infection are not completely understood, and it is not observed in every pregnant woman infected with RuV. As gestational diabetes mellitus is a risk factor for congenital viral infections, we investigated the possible roles of hypoglycemia-related endoplasmic reticulum (ER) stress as a key factor for vertical RuV infection using immortalized human first-trimester trophoblasts. Low-glucose stress was induced prior to RuV infection by culturing HTR-8/SVneo and Swan.71 cells in low-glucose (LG) medium for 24 h or high-glucose medium for 6 h and then LG medium for an additional 18 h. Clinically isolated RuV was inoculated at a multiplicity of infection of 5 to 10. The intracellular localization of the RuV capsid protein was investigated 24 to 48 h post-infection (pi) with flow cytometry (FCM) analysis and fluorescence microscopy. Viral progeny production was monitored by FCM analysis. Increases in RuV infection in LG-induced ER-stressed trophoblasts were observed. No significant increase in apoptosis of RuV-infected cells was noted at days 2 and 5 pi, and substantial viral progeny production was observed until day 5 pi. An approximate fivefold increase in viral binding was noted for the LG-stressed cells. Although the detailed mechanisms underlying viral entry into LG-stressed cells are not known and require further investigation, these findings suggest that a certain degree of LG stress in early pregnancy may facilitate infection and cause CRS.

The Novel Peptide AEDPPE Alleviates Trophoblast Cell Dysfunction Associated With Preeclampsia by Regulating the NF-κB Signaling Pathway

Background: Preeclampsia (PE) is a serious risk to the health of pregnant women and fetuses during pregnancy, and there is no effective treatment for this condition. Although many reports have confirmed the therapeutic effects of peptides in diseases, the role of peptides in PE remains poorly understood.

Methods: A differentially expressed peptide in PE (AEDPPE) is derived from heat-shock protein beta-1 (HSPB1), amino acids 100 to 109 (DVNHFAPDEL), which we identified in a previous study. We synthesized AEDPPE and investigated its effect on HTR-8/SVneo cell function using a Cell Counting Kit-8, flow cytometric assay, and Transwell and wound-healing assays. Quantitative reverse transcription-PCR and ELISA were used to determine cytokine expression. Pull-down assay, mass spectrometry, Western blot analysis, and immunofluorescence were used to explore the potential targets and signaling pathways regulated by AEDPPE. Finally, we assessed the effect of AEDPPE in the lipopolysaccharide (LPS)-induced PE-like rat model.

Results: AEDPPE significantly promoted the migration and invasion of HTR-8/SVneo cells, and it decreased the expression of interleukins 1 beta (IL-1β), interleukin 6 (IL-6), and interleukin 8 (IL-8). These functions performed by AEDPPE remained evident after injury to HTR-8/SVneo cells with tumor necrosis factor-alpha (TNF-α), and AEDPPE reversed the elevated sFlt-1/PlGF ratio induced by TNF-α. AEDPPE may exert these biological effects by binding to heat-shock protein 90β (HSP 90β) and, thus, affect the NF-κB signaling pathway. In an LPS-induced PE-like rat model, AEDPPE significantly improved PE symptoms and fetal rat outcomes.

Conclusion: Our study showed that AEDPPE enhanced trophoblast migration and invasion and reduced inflammatory cytokine expression, and we hypothesized that these actions involved the NF-κB signaling pathway. The use of AEDPPE may thus develop into a novel modality in the treatment of PE.

Low Abundance Fusobacterium Nucleatum Supports Early Pregnancy Development - An In Vitro Study

Pregnancy success depends greatly on a balanced immune homeostasis. The detection of bacterial components in the upper reproductive tract in non-pregnant and pregnant women raised questions on its possible beneficial role in reproductive health. The local conditions that allow the presence of bacteria to harmonize with the establishment of pregnancy are still unknown. Among the described bacterial species in endometrial and placental samples, Fusobacterium nucleatum was found. It has been observed that F. nucleatum can induce tumorigenesis in colon carcinoma, a process that shares several features with embryo implantation. We propose that low concentrations of F. nucleatum may improve trophoblast function without exerting destructive responses. Inactivated F. nucleatum and E. coli were incubated with the trophoblastic cell lines HTR8/SVneo, BeWo, and JEG-3. Viability, proliferation, migratory capacity, invasiveness and the secretion of chemokines, other cytokines and matrix metalloproteinases were assessed. The presence of F. nucleatum significantly induced HTR8/SVneo invasion, accompanied by the secretion of soluble mediators (CXCL1, IL-6 and IL-8) and metalloproteinases (MMP-2 and MMP-9). However, as concentrations of F. nucleatum increased, these did not improve invasiveness, hindered migration, reduced cell viability and induced alterations in the cell cycle. Part of the F. nucleatum effects on cytokine release were reverted with the addition of a TLR4 blocking antibody. Other effects correlated with the level of expression of E-cadherin on the different cell lines tested. Low amounts of F. nucleatum promote invasion of HTR8/SVneo cells and induce the secretion of important mediators for pregnancy establishment. Some effects were independent of LPS and correlated with the expression of E-cadherin on trophoblasts.