Inflammatory Cytokine-Induced HIF-1 Activation Promotes Epithelial-Mesenchymal Transition in Endometrial Epithelial Cells.

The endometrium undergoes repeated proliferation and shedding during the menstrual cycle. Significant changes to this environment include fluctuations in the partial pressure of oxygen, exposure to a high-cytokine environment associated with intrauterine infection, and inflammation. Chronic endometritis is a condition wherein mild inflammation persists in the endometrium and is one of the causes of implantation failure and miscarriage in early pregnancy. It is thought that the invasion of embryos into the endometrium requires epithelial-mesenchymal transition (EMT)-associated changes in the endometrial epithelium. However, the effects of inflammation on the endometrium remain poorly understood. In this study, we investigated the effects of the intrauterine oxygen environment, hypoxia-inducible factor (HIF), and inflammation on the differentiation and function of endometrial epithelial cells. We elucidated the ways in which inflammatory cytokines affect HIF activity and EMT in an immortalized cell line (EM-E6/E7/TERT) derived from endometrial epithelium. Pro-inflammatory cytokines caused significant accumulation of HIF-1α protein, increased HIF-1α mRNA levels, and enhanced hypoxia-induced accumulation of HIF-1α protein. The combined effect of inflammatory cytokines and hypoxia increased the expression of EMT-inducing factors and upregulated cell migration. Our findings indicate that pro-inflammatory factors, including cytokines and LPS, work synergistically with hypoxia to activate HIF-1 and promote EMT in endometrial epithelial cells.

Significance of placental CD200 expression in patients with preeclampsia: Comparison between early­ and late­onset patients.

Preeclampsia, characterized by high blood pressure and proteinuria during pregnancy, causes serious complications in both the mother and the fetus. Although there have been several studies on the causes of preeclampsia, the detailed mechanism of this disease remains unclear. Moreover, a few reports have focused on the causes of preeclampsia in number of weeks at onset. The present study aimed to elucidate the differences between early­ and late­onset preeclampsia. This study enrolled patients with preeclampsia from January 2014 to December 2020. They were classified into early­ (<34 weeks) and late­onset (≥34 weeks) preeclampsia groups. The expression profiles of 770 immune­related genes were studied in the placental tissue from five patients each in the early­ and late­onset groups. The expression of CD200 in the trophoblasts of the placenta of 26 and 27 patients in early­ and late­onset groups, respectively, was also analyzed using immunostaining. Analysis of extracted RNA indicated that CD200 was significantly upregulated in the early­onset group compared with late­onset group and normal control. Immunostaining for CD200 demonstrated a significantly increased expression in the early­onset group compared with the late­onset group. The present study demonstrated that upregulation of CD200, which belongs to the immunoglobulin superfamily and is recognized as a molecule that acts in immune tolerance via inhibition of classical macrophage activation, may be associated with early­onset preeclampsia, although it remains unknown whether upregulation of CD200 expression is a cause or effect of the development of early­onset preeclampsia. Early­onset preeclampsia might have a different mechanism from that of late­onset; thus, further studies are needed to clarify the mechanism of these conditions for adequate treatment.

The novel oral gonadotropin-releasing hormone receptor antagonist relugolix is a new option for controlled ovarian stimulation cycles.

Purpose: Relugolix is an oral gonadotropin-releasing hormone antagonist (GnRHant), which was first introduced in 2019. This study investigated the effects of the conventional injectable GnRHant formulation and this new oral GnRHant formulation on controlled ovarian stimulation (COS) cycles. Methods: Relugolix was administered in 126 cycles and conventional GnRHant injection was administered in 658 cycles (controls). The follicle stimulation was performed by an antagonist method, and for final oocyte maturation, recombinant human chorionic gonadotropin (rHCG), or gonadotropin-releasing hormone agonist (GnRHa), or both (dual trigger) were selected. The number of retrieved oocytes was counted and then they were evaluated for subsequent development up to cleavage stage. Results: The number of retrieved oocytes which was the primary outcome of this research was affected by the combination of GnRHant type and the final oocyte maturation agent. The combination of relugolix and a GnRHa trigger showed a significantly lower number of retrieved oocytes (p < 0.001) than the other combinations. Conclusions: Relugolix is a new option for COS cycles, but should be carefully combined with the final maturation agent. Clinical trial approval: This study was conducted after approval by the Medical Corporation Sankeikai Institutional Ethics Committee (approval number: 2019-34).

NDRG1 is expressed in human granulosa cells: An implicative role of NDRG1 in the ovary.

Purpose: N-myc downstream-regulated gene 1 (NDRG1) is expressed in various human tissues and plays a role in regulating cellular proliferation, angiogenesis, and hypoxia sensing. However, the role of NDRG1 in the ovary remains poorly understood. Therefore, we investigated NDRG1 expression and the role of NDRG1 in the human ovary. Methods: Follicular fluid (FF) and luteinized granulosa cells were collected from follicles during oocyte retrieval. KGN cells were cultured with cobalt chloride (CoCl2, a hypoxia-mimicking agent) and/or echinomycin. mRNA, protein levels and secretion, and localization were assessed by real-time PCR, Western blotting, ELISA, and immunohistochemical analysis, respectively. KGN cells were also transfected with NDRG1 siRNA for 72 h. Results: NDRG1 protein was expressed in luteinized granulosa cells. NDRG1 concentration was positively correlated with vascular endothelial growth factor (VEGF) and progesterone concentrations in FF. CoCl2-induced hypoxic stress significantly increased NDRG1 and VEGF mRNA and protein and hypoxia-inducible factor-1α expression compared with those in the controls. The CoCl2-induced overexpression of NDRG1 and VEGF was suppressed by echinomycin. Transfection with NDRG1 siRNA significantly suppressed the release of progesterone in the culture medium. Conclusions: These results indicate that ovarian NDRG1 may play important roles in follicular development, especially in the early luteinization of pre-ovulatory follicles.

Hypoxia: Role of SIRT1 and the protective effect of resveratrol in ovarian function.

BACKGROUND: Ovarian function is closely related to the degree of vascular network development surrounding the ovary. Maternal aging-related construction defects in this vascular network can cause ovarian hypoxia, which impedes oocyte nutrient supply, leading to physiological changes in the ovaries and oocytes. The anti-aging gene Sirtuin 1 (SIRT1) senses and adapts to ambient stress and is associated with hypoxic environments and mitochondrial biogenesis. METHODS: The present study is a literature review focusing on investigations involving the changes in SIRT1 and mitochondrial expression during hypoxia and the cytoprotective effects of the SIRT1 activator, resveratrol. MAIN FINDINGS: Hypoxia suppresses SIRT1 and mitochondrial expression. Resveratrol can reverse the hypoxia-induced decrease in mitochondrial and SIRT1 activity. Resveratrol suppresses the production of hypoxia-inducible factor-1α and vascular endothelial growth factor proteins. CONCLUSION: Resveratrol exhibits protective activity against hypoxic stress and may prevent hypoxia- or aging-related mitochondrial dysfunction. Resveratrol treatment may be a potential option for infertility therapy.

Cigarette Smoke Extract Activates Hypoxia-Inducible Factors in a Reactive Oxygen Species-Dependent Manner in Stroma Cells from Human Endometrium.

Cigarette smoking (CS) is a major contributing factor in the development of a large number of fatal and debilitating disorders, including degenerative diseases and cancers. Smoking and passive smoking also affect the establishment and maintenance of pregnancy. However, to the best of our knowledge, the effects of smoking on the human endometrium remain poorly understood. In this study, we investigated the regulatory mechanism underlying CS-induced hypoxia-inducible factor (HIF)-1α activation using primary human endometrial stromal cells and an immortalized cell line (KC02-44D). We found that the CS extract (CSE) increased reactive oxygen species levels and stimulated HIF-1α protein stabilization in endometrial stromal cells, and that CS-induced HIF-1α-dependent gene expression under non-hypoxic conditions in a concentration- and time-dependent manner. Additionally, we revealed the upregulated expression of a hypoxia-induced gene set following the CSE treatment, even under normoxic conditions. These results indicated that HIF-1α might play an important role in CS-exposure-induced cellular stress, inflammation, and endometrial remodeling.

Exposure to cigarette smoke affects endometrial maturation including angiogenesis and decidualization.

PURPOSE: To elucidate the effects of cigarette smoking on human endometrial maturation for reproductive function, the authors examined the in vitro effects of cigarette smoke extract (CSE) on angiogenesis and decidualization in primary human endometrial stromal cells (ESCs). METHODS: Endometrial stromal cells were cultured with CSE and/or estradiol-17ß (E2) and medroxyprogesterone acetate (MPA). The mRNA, protein levels, and protein secretion of the angiogenic factors and decidual specific factors were assessed using real-time polymerase chain reaction, Western blot analysis, and enzyme-linked immunosorbent assay, respectively. Decidualization was also monitored by the changes in cellular morphology. RESULTS: Endometrial stromal cell proliferation substantially decreased after dose-dependent treatments with CSE at concentrations above 1%, whereas cell death was induced at treatment concentrations above 1% CSE. Treatments above 0.025% CSE led to increased vascular endothelial growth factor mRNA through hypoxia-inducible factor-1α accumulation. CSE concentrations at 0.01% and 0.025% increased the prolactin expression levels after treatment with E2 and MPA, whereas 0.1% and 0.25% CSE concentrations suppressed prolactin. Similar tendencies were observed in cellular morphology and other decidual specific factors. CONCLUSION: These results suggest that exposure to cigarette smoke affects endometrial appropriate maturation including the processes of angiogenesis and decidualization in the reproductive system.

The transcription factor HAND2 up-regulates transcription of the IL15 gene in human endometrial stromal cells.

Cyclic changes of the human endometrium, such as proliferation, secretion, and decidualization, occur during regular menstrual cycles. Heart- and neural crest derivatives-expressed transcript 2 (HAND2) is a key transcription factor in progestin-induced decidualization of human endometrial stromal cells (ESCs). It has been suggested that HAND2 regulates interleukin 15 (IL15), a key immune factor required for the activation and survival of uterine natural killer (uNK) cells. Activated uNK cells can promote spiral artery remodeling and secrete cytokines to induce immunotolerance. To date, no studies have evaluated the transcription factors that regulate IL15 expression in human ESCs. In the present study, we examined whether HAND2 controls IL15 transcriptional regulation in human ESCs. Quantitative RT-PCR and histological analyses revealed that HAND2 and IL15 levels increase considerably in the secretory phase of human endometrium tissues. Results from ChIP-quantitative PCR suggested that HAND2 binds to a putative HAND2 motif, which we identified in the upstream region of the human IL15 gene through in silico analysis. Using a luciferase reporter assay, we found that the upstream region of the human IL15 gene up-regulates reporter gene activities in response to estradiol and a progestin representative (medroxyprogesterone) in ESCs. The upstream region of the human IL15 gene also exhibited increasing responsiveness to transfection with a HAND2 expression vector. Of note, deletion and substitution variants of the putative HAND2 motif in the upstream region of IL15 did not respond to HAND2 transfection. These findings confirm that HAND2 directly up-regulates human IL15 transcription in ESCs.

Thyroid Hormone Facilitates in vitro Decidualization of Human Endometrial Stromal Cells via Thyroid Hormone Receptors.

Endometrial stromal cells differentiate into decidual cells through the process of decidualization. This differentiation is critical for embryo implantation and the successful establishment of pregnancy. Recent epidemiological studies have suggested that thyroid hormone is important in the endometrium during implantation, and it is commonly believed that thyroid hormone is essential for proper development, differentiation, growth, and metabolism. This study aimed to investigate the impact of thyroid hormone on decidualization in human endometrial stromal cells (hESCs) and define its physiological roles in vitro by gene targeting. To identify the expression patterns of thyroid hormone, we performed gene expression profiling of hESCs during decidualization after treating them with the thyroid hormone levothyroxine (LT4). A major increase in decidual response was observed after combined treatment with ovarian steroid hormones and thyroid hormone. Moreover, LT4 treatment also affected the regulation of many transcription factors important for decidualization. We found that type 3 deiodinase, which is particularly important in fetal and placental tissues, was upregulated during decidualization in the presence of thyroid hormone. Further, it was observed that progesterone receptor, an ovarian steroid hormone receptor, was involved in thyroid hormone-induced decidualization. In the absence of thyroid hormone receptor (TR), due to the simultaneous silencing of TRα and TRß, thyroid hormone expression was unchanged during decidualization. In summary, we demonstrated that thyroid hormone is essential for decidualization in the endometrium. This is the first in vitro study to find impaired decidualization as a possible cause of infertility in subclinical hypothyroidism (SCH) patients.

Concentration of stromal cell-derived factor-1 (SDF-1/CXCL12) in the follicular fluid is associated with blastocyst development.

PURPOSE: To study the association between stromal cell-derived factor-1 (SDF-1/CXCL12) and vascular endothelial growth factor (VEGF) concentrations in individual human ovarian follicles and IVF outcomes. METHODS: Concentrations of SDF-1 and VEGF in 261 follicular fluid samples were measured with enzyme-linked immunosorbent assay. IVF outcome parameters were included in fertilization rate, cleavage rate, embryo morphology on day 3, and blastocyst morphology on day 5. RESULTS: The follicular concentration of SDF-1 and VEGF was not significantly associated with fertilization and cleavage outcome, and embryo morphology. The rates of full blastocysts and good-quality blastocysts were significantly higher in follicles with an SDF-1 concentration of 275-350 pg/mL than in the follicles with SDF-1 concentrations of <200 and ≥350 pg/mL (P < 0.05). The follicular concentration of VEGF was not associated with the blastocyst morphology. CONCLUSION: Our findings showed that follicular concentration of SDF-1, and not VEGF, may be a valuable biochemical marker of blastocyst development.