Meta-analysis on prevalence of vaginal group B streptococcus colonization and preterm births in India.

OBJECTIVE: Preterm birth is a major cause of neonatal morbidity and mortality. Vaginal colonization of Group B Streptococci (GBS) is associated with increased risk of preterm birth. However, the association of GBS colonization and preterm births in the Indian context remains an unrecognized problem. DATA SOURCES: Data was collected using various online search tools from 36 (1981-2019) Indian studies comprising 9778 cases. METHOD OF STUDY SELECTION: Studies reporting the prevalence of GBS colonization in the Indian population were included. TABULATION, INTEGRATION, AND RESULTS: The prevalence of GBS colonization in pregnant Indian women was estimated to be 7.8% (763/9778) with wide heterogeneity across studies. The prevalence of GBS was 7.4% when culture methods were used and 11.6% with use of immunological methods. The detection rate of GBS almost doubled when enrichment was used in the culture method (8.1 vs. 5%). The risk of preterm delivery was higher (OR 7.9) among women with GBS colonization as compared to those without GBS. CONCLUSIONS: As compared to the western population, there is low prevalence of GBS colonization among Indian pregnant women; however, the risk of preterm births with GBS colonization is higher. There is a need to implement a universal GBS screening program prior to intrapartum antibiotic prophylaxis in women experiencing preterm births.

Modulation of E-Cadherin and N-Cadherin by ovarian steroids and embryonic stimuli.

Endometrium is a dynamic tissue that undergoes extensive remodelling to attain a receptive state which is further modulated in presence of an embryo for successful initiation of pregnancy. Cadherins are the proteins of the junctional complex of which E-cadherin (E-Cad) is crucial for maintaining epithelial cell state and integrity of the epithelial barrier; gain of N-cadherin (N-Cad) in epithelial cells leads to epithelial to mesenchymal transition (EMT). In the present study, we investigated the expression of E-Cad and N-Cad in the mouse endometrial luminal epithelium and its modulation by estrogen, progesterone, and embryonic stimuli. We observed that E-Cad is diffusely expressed in the luminal epithelium of mouse endometrium during the estrus stage and upon estrogen treatment. It is apico-laterally and basolaterally sorted at the diestrus stage and in response to the combined treatment of estrogen and progesterone. In 3D spheroids of human endometrial epithelial cells, combined treatment with estrogen and progesterone led to lateral sorting of E-Cad without any effects on its mRNA levels. at the time of embryo implantation, there is loss of E-Cad along with the gain of N-Cad and SNAIL expression suggestive of EMT in the luminal epithelium. This EMT is possibly driven by embryonic stimuli as treatment with estrogen and progesterone did not lead to the gain of N-Cad expression in the mouse endometrium in vivo or in human endometrial epithelial cells in vitro. In conclusion, the present study demonstrates that steroid hormones directly affect E-Cad sorting in the endometrial epithelium which undergo EMT in response to embryonic stimuli.

Extracellular vesicles in embryo implantation and disorders of the endometrium.

Implantation of the embryo is a rate-limiting step for a successful pregnancy, and it requires an intricate crosstalk between the embryo and the endometrium. Extracellular vesicles (EVs) are membrane-enclosed, nano-sized structures produced by cells to mediate cell to cell communication and modulate a diverse set of biological processes. Herein, we review the involvement of EVs in the process of embryo implantation and endometrial diseases. EVs have been isolated from uterine fluid, cultured endometrial epithelial/stromal cells and trophectodermal cells. The endometrial epithelial and stromal/decidual cell-derived EVs and its cargo are internalized bythe trophoblast cells, and they regulate a diverse set of genes involved in adhesion, invasion and migration. Conversely, the embryo-derived EVs and its cargo are internalized by epithelial and immune cells of the endometrium for biosensing and immunomodulation required for successful implantation. EVs have also been shown to play a role in infertility, recurrent implantation failure, endometriosis, endometritis and endometrial cancer. Further research should set a stage for EVs as non-invasive "liquid biopsy" tools for assessment of endometrial health.

Single-Cell RNA-seq Identifies Cell Subsets in Human Placenta That Highly Expresses Factors Driving Pathogenesis of SARS-CoV-2.

Infection by the Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) results in the novel coronavirus disease COVID-19, which has posed a serious threat globally. Infection of SARS-CoV-2 during pregnancy is associated with complications such as preterm labor and premature rupture of membranes, and a proportion of neonates born to infected mothers are also positive for the virus. During pregnancy, the placental barrier protects the fetus from pathogens and ensures healthy development. To predict if the placenta is permissive to SARS-CoV-2, we utilized publicly available single-cell RNA-seq data to identify if the placental cells express the necessary factors required for infection. SARS-CoV-2 binding receptor ACE2 and the S protein priming protease TMPRSS2 are co-expressed by a subset of syncytiotrophoblasts (STB) in the first trimester and extravillous trophoblasts (EVT) in the second trimester human placenta. In addition, the non-canonical receptor BSG/CD147 and other proteases (CTSL, CTSB, and FURIN) are detected in most of the placental cells. Other coronavirus family receptors (ANPEP and DPP4) were also expressed in the first and second trimester placental cells. Additionally, the term placenta of multiple species including humans expressed ACE2, DPP4, and ANPEP along with the viral S protein proteases. The ACE2- and TMPRSS2-positive (ACE2 + TMPRSS2 +) placental subsets expressed mRNA for proteins involved in viral budding and replication. These cells also had the mRNA for proteins that physically interact with SARS-CoV-2 in host cells. Further, we discovered unique signatures of genes in ACE2 + TMPRSS2 + STBs and EVTs. The ACE2 + TMPRSS2 + STBs are highly differentiated cells and express genes involving mitochondrial metabolism and glucose transport. The second trimester ACE2 + TMPRSS2 + EVTs are enriched for markers of endovascular trophoblasts. Both these subtypes abundantly expressed genes in the Toll-like receptor pathway. The second trimester EVTs are also enriched for components of the JAK-STAT pathway that drives inflammation. We carried out a systematic review and identified that in 12% of pregnant women with COVID-19, the placenta was infected with SARS-CoV-2, and the virus was detected in STBs. To conclude, herein we have uncovered the cellular targets for SARS-CoV-2 entry and have shown that these cells can potentially drive viremia in the developing human placenta. Our results provide a basic framework toward understanding the paraphernalia involved in SARS-CoV-2 infections in pregnancy.

Homeobox genes in endometrium: from development to decidualization.

The eutherian species evolved an elaborate uterus to allow viviparity. For successful pregnancy, the uterus must not only be differentiated, but must also function optimally and any defects in uterus differentiation and/or function can lead to infertility. The homoebox gene HOXA10 has emerged to be a key player in both uterine development and its optimal functioning in adulthood. Within the Abd-B family, the posterior Hoxa genes play a dominant role in anterio-posterior segmentation of the Müllerian ducts in mammals, with Hoxa10 having a central role in uterine segmentation. In the adult endometrium, HOXA10 is expressed by endometrial cells and is regulated in a cyclic manner under the influence of ovarian steroids. During embryo implantation, expression of HOXA10 is increased in endometrial stromal cells by signals from the embryo to govern stromal cell transformation to decidual cells. Once decidualization is initiated, HOXA10 is rapidly downregulated to activate expression of pro-invasive factors to promote trophoblast invasion. We propose that HOXA10 governs embryo implantation in a three-step process: 1) acquisition of endometrial receptivity, 2) responding to signals from the blastocyst to modify receptive endometrium for decidualization 3) making the decidua conductive for trophoblast invasion and placentation. There is currently ample evidence that expression of HOXA10 is deregulated in a variety of "endometriopathies" such as endometriosis and endometrial cancers. Overall, HOXA10 appears to be the master regulator of endometrial health and a central determinant of fertility in mammals.

Oviductal glycoprotein 1 (OVGP1) is expressed by endometrial epithelium that regulates receptivity and trophoblast adhesion.

PURPOSE: To study the regulation and functions of oviductal glycoprotein 1 (OVGP1) in endometrial epithelial cells. METHODS: Expression of OVGP1 in mouse endometrium during pregnancy and in the endometrial epithelial cell line (Ishikawa) was studied by immunofluorescence, Western blotting, and RT-PCR. Regulation of OVGP1 in response to ovarian steroids and human chorionic gonadotropin (hCG) was studied by real-time RT-PCR. OVGP1 expression was knockdown in Ishikawa cells by shRNA, and expression of receptivity associated genes was studied by real-time RT-PCR. Adhesion of trophoblast cell line (JAr) was studied by in vitro adhesion assays. RESULTS: OVGP1 was localized exclusively in the luminal epithelial cells of mouse endometrium at the time of embryo implantation. Along with estrogen and progesterone, hCG induced the expression of OVGP1 in Ishikawa cells. Knockdown of OVGP1 in Ishikawa cells reduced mRNA expression of ITGAV, ITGB3, ITGA5, HOXA10, LIF, and IL15; it increased the expression of HOXA11, MMP9, TIMP1, and TIMP3. Supernatants derived from OVGP1 knockdown Ishikawa cells reduced the adhesiveness of JAr cells in vitro. Expression of OVGP1 mRNA was found to be significantly lowered in the endometrium of women with recurrent implantation failure. CONCLUSION: OVGP1 is specifically induced in the luminal epithelium at the time of embryo implantation where it regulates receptivity-related genes and aids in trophoblast adhesion.

Embryo Implantation: War in Times of Love.

Contrary to widespread belief, the implantation of an embryo for the initiation of pregnancy is like a battle, in that the embryo uses a variety of coercive tactics to force its acceptance by the endometrium. We propose that embryo implantation involves a three-step process: (1) identification of a receptive endometrium; (2) superimposition of a blastocyst-derived signature onto the receptive endometrium before implantation; and finally (3) breaching by the embryo and trophoblast invasion, culminating in decidualization and placentation. We review here the story that is beginning to emerge, focusing primarily on the cells that are in "combat" during this process.