Sialic acid is a critical fetal defense against maternal complement attack

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Abstract

The negatively charged sugar sialic acid (Sia) occupies the outermost position in the bulk of cell surface glycans. Lack of sialylated glycans due to genetic ablation of the Sia activating enzyme CMP-sialic acid synthase (CMAS) resulted in embryonic lethality around day 9.5 post coitum (E9.5) in mice. Developmental failure was caused by complement activation on trophoblasts in Cmas-/- implants accompanied by infiltration of maternal neutrophils at the fetal-maternal interface, intrauterine growth restriction, impaired placental development and a thickened Reichert’s membrane. This phenotype, which shared features with complement-recepter-1 related protein Y (Crry) depletion, was rescued in E8.5 Cmas-/- mice upon injection of cobra venom factor resulting in exhaustion of the maternal complement component C3. Here we show that Sia is dispensable for early development of the embryo proper, but pivotal for fetal-maternal immune homeostasis during pregnancy, i.e. for protecting the allograft implant against attack by the maternal innate immune system. Finally, embryos devoid of cell surface sialylation suffered from malnutrition due to inadequate placentation as secondary effect.

Authors

Markus Abeln, Iris Albers, Ulrike Peters-Bernard, Kerstin Flächsig-Schulz, Elina Kats, Andreas Kispert, Stephen Tomlinson, Rita Gerardy-Schahn, Anja Münster-Kühnel, Birgit Weinhold

Use of contraceptive depot medroxyprogesterone acetate is associated with impaired cervicovaginal mucosal integrity

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Abstract

BACKGROUND. Injectable depot medroxyprogesterone acetate (DMPA) is one of the most popular contraception methods in areas of high HIV seroprevalence. Evidence is accumulating that use of DMPA might be associated with an increased risk of HIV-1 acquisition by women; however, mechanisms of this association are not completely understood. The goal of this study was to gain insight into mechanisms underlying the possible link between use of DMPA and risk of HIV-1 acquisition, exploring transcription profiling of ectocervical tissues. METHODS. Healthy women received either DMPA (n = 31) or combined oral contraceptive (COC), which has not been linked to an increased risk of HIV acquisition (n = 32). We conducted a comparative microarray-based whole-genome transcriptome profiling of human ectocervical tissues before and after 6 weeks of hormonal contraception use. RESULTS. The analysis identified that expression of 235 and 76 genes was significantly altered after DMPA and COC use, respectively. The most striking effect of DMPA, but not COC, was significantly altered expression (mostly downregulation) of many genes strategically involved in the maintenance of mucosal barrier function; the alterations, as indicated by Ingenuity Pathway Analysis (IPA), were most likely due to the DMPA-induced estrogen deficiency. Furthermore, IPA predicted that transcriptome alterations related to ectocervical immune responses were in general compatible with an immunosuppressive effect of DMPA, but, in some women, also with an inflammatory-like response. CONCLUSION. Our results suggest that impairment of cervicovaginal mucosal integrity in response to DMPA administration is an important mechanism contributing to the potential increased risk of HIV-1 acquisition in DMPA users. TRIAL REGISTRATION. ClinicalTrials.gov NCT01421368. FUNDING. This study was supported by the United States Agency for International Development (USAID) under Cooperative Agreement GPO-A-00-08-00005-00.

Authors

Irina A. Zalenskaya, Neelima Chandra, Nazita Yousefieh, Xi Fang, Oluwatosin E. Adedipe, Suzanne S. Jackson, Sharon M. Anderson, Christine K. Mauck, Jill L. Schwartz, Andrea R. Thurman, Gustavo F. Doncel

Loss of placental growth factor ameliorates maternal hypertension and preeclampsia in mice

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Abstract

Preeclampsia remains a clinical challenge due to its poorly understood pathogenesis. A prevailing notion is that increased placental production of soluble fms-like tyrosine kinase-1 (sFlt-1) causes the maternal syndrome by inhibiting proangiogenic placental growth factor (PlGF) and VEGF. However, the significance of PlGF suppression in preeclampsia is uncertain. To test whether preeclampsia results from the imbalance of angiogenic factors reflected by an abnormal sFlt-1:PlGF ratio, we studied PlGF knockout (KO; Pgf–/–) mice and noted that while sFlt-1 was significantly elevated in pregnancy, the mice did not develop signs or sequelae of preeclampsia. Notably, PlGF KO mice had morphologically distinct placentas, showing an accumulation of junctional zone glycogen. We next considered the role of placental PlGF in an established model of preeclampsia (pregnant catechol-O-methyltransferase (COMT)-deficient mice) by generating mice with deletions in both the Pgf and Comt genes. Deletion of placental PlGF in the context of COMT loss resulted in a reduction in maternal blood pressure and increased placental glycogen, indicating that loss of PlGF might be protective against the development of preeclampsia. These results identify a role for PlGF in placental development and support a complex model for the pathogenesis of preeclampsia beyond an angiogenic factor imbalance.

Authors

Jacqueline G. Parchem, Keizo Kanasaki, Megumi Kanasaki, Hikaru Sugimoto, Liang Xie, Yuki Hamano, Soo Bong Lee, Vincent H. Gattone, Samuel Parry, Jerome F. Strauss, Vesna D. Garovic, Thomas F. McElrath, Karen H. Lu, Baha M. Sibai, Valerie S. LeBleu, Peter Carmeliet, Raghu Kalluri

HIF2α in the uterine stroma permits embryo invasion and luminal epithelium detachment

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Abstract

Although it has been reported that hypoxia inducible factor 2 α (Hif2a), a major transcriptional factor inducible by low oxygen tension, is expressed in the mouse uterus during embryo implantation, its role in pregnancy outcomes remains unclear. This study aimed to clarify functions of uterine HIF using transgenic mouse models. Mice with deletion of Hif2a in the whole uterus (Hif2a-uKO mice) showed infertility due to implantation failure. Supplementation with progesterone (P4) and leukemia inhibitory factor (LIF) restored decidual growth arrest and aberrant position of implantation sites in Hif2a-uKO mice, respectively, but did not rescue pregnancy failure. Histological analyses in Hif2a-uKO mice revealed persistence of the intact luminal epithelium, which blocked direct contact between stroma and embryo, inactivation of PI3K-AKT pathway (embryonic survival signal), and failed embryo invasion. Mice with stromal deletion of Hif2a (Hif2a-sKO mice) showed infertility with impaired embryo invasion and those with epithelial deletion of Hif2a (Hif2a-eKO mice) showed normal fertility, suggesting the importance of stromal HIF2α in embryo invasion. This was reflected in reduced expression of membrane type 2 metalloproteinase (MT2-MMP), lysyl oxidase (LOX), VEGF, and adrenomedullin (ADM) in Hif2a-uKO stroma at the attachment site, suggesting that stromal HIF2α regulates these mediators to support blastocyst invasion. These findings provide new insight that stromal HIF2α allows trophoblast invasion through detachment of the luminal epithelium and activation of an embryonic survival signal.

Authors

Leona Matsumoto, Yasushi Hirota, Tomoko Saito-Fujita, Norihiko Takeda, Tomoki Tanaka, Takehiro Hiraoka, Shun Akaeda, Hidetoshi Fujita, Ryoko Shimizu-Hirota, Shota Igaue, Mitsunori Matsuo, Hirofumi Haraguchi, Mayuko Saito-Kanatani, Tomoyuki Fujii, Yutaka Osuga

Group B streptococcus exploits vaginal epithelial exfoliation for ascending infection

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Abstract

Thirteen percent of pregnancies result in preterm birth or stillbirth, accounting for fifteen million preterm births and three and a half million deaths annually. A significant cause of these adverse pregnancy outcomes is in utero infection by vaginal microorganisms. To establish an in utero infection, vaginal microbes enter the uterus by ascending infection; however, the mechanisms by which this occurs are unknown. Using both in vitro and murine models of vaginal colonization and ascending infection, we demonstrate how a vaginal microbe, group B streptococcus (GBS), which is frequently associated with adverse pregnancy outcomes, uses vaginal exfoliation for ascending infection. GBS induces vaginal epithelial exfoliation by activation of integrin and β-catenin signaling. However, exfoliation did not diminish GBS vaginal colonization as reported for other vaginal microbes. Rather, vaginal exfoliation increased bacterial dissemination and ascending GBS infection, and abrogation of exfoliation reduced ascending infection and improved pregnancy outcomes. Thus, for some vaginal bacteria, exfoliation promotes ascending infection rather than preventing colonization. Our study provides insight into mechanisms of ascending infection by vaginal microbes.

Authors

Jay Vornhagen, Blair Armistead, Verónica Santana-Ufret, Claire Gendrin, Sean Merillat, Michelle Coleman, Phoenicia Quach, Erica Boldenow, Varchita Alishetti, Christina Leonhard-Melief, Lisa Y. Ngo, Christopher Whidbey, Kelly S. Doran, Chad Curtis, Kristina M. Adams Waldorf, Elizabeth Nance, Lakshmi Rajagopal

Constitutively active follicle-stimulating hormone receptor enables androgen-independent spermatogenesis

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Abstract

Spermatogenesis is regulated by the 2 pituitary gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH). This process is considered impossible without the absolute requirement of LH-stimulated testicular testosterone (T) production. The role of FSH remains unclear because men and mice with inactivating FSH receptor (FSHR) mutations are fertile. We revisited the role of FSH in spermatogenesis using transgenic mice expressing a constitutively strongly active FSHR mutant in a LH receptor–null (LHR-null) background. The mutant FSHR reversed the azoospermia and partially restored fertility of Lhr–/– mice. The finding was initially ascribed to the residual Leydig cell T production. However, when T action was completely blocked with the potent antiandrogen flutamide, spermatogenesis persisted. Hence, completely T-independent spermatogenesis is possible through strong FSHR activation, and the dogma of T being a sine qua non for spermatogenesis may need modification. The mechanism for the finding appeared to be that FSHR activation maintained the expression of Sertoli cell genes considered androgen dependent. The translational message of our findings is the possibility of developing a new strategy of high-dose FSH treatment for spermatogenic failure. Our findings also provide an explanation of molecular pathogenesis for Pasqualini syndrome (fertile eunuchs; LH/T deficiency with persistent spermatogenesis) and explain how the hormonal regulation of spermatogenesis has shifted from FSH to T dominance during evolution.

Authors

Olayiwola O. Oduwole, Hellevi Peltoketo, Ariel Poliandri, Laura Vengadabady, Marcin Chrusciel, Milena Doroszko, Luna Samanta, Laura Owen, Brian Keevil, Nafis A. Rahman, Ilpo T. Huhtaniemi

H3K27me3 dynamics dictate evolving uterine states in pregnancy and parturition

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Abstract

Uncovering the causes of pregnancy complications such as preterm labor requires greater insight into how the uterus remains in a noncontractile state until term and then surmounts this state to enter labor. Here, we show that dynamic generation and erasure of the repressive histone modification tri-methyl histone H3 lysine 27 (H3K27me3) in decidual stromal cells dictate both elements of pregnancy success in mice. In early gestation, H3K27me3-induced transcriptional silencing of select gene targets ensured uterine quiescence by preventing the decidua from expressing parturition-inducing hormone receptors, manifesting type 1 immunity, and most unexpectedly, generating myofibroblasts and associated wound-healing responses. In late gestation, genome-wide H3K27 demethylation allowed for target gene upregulation, decidual activation, and labor entry. Pharmacological inhibition of H3K27 demethylation in late gestation not only prevented term parturition, but also inhibited delivery while maintaining pup viability in a noninflammatory model of preterm parturition. Immunofluorescence analysis of human specimens suggested that similar regulatory events might occur in the human decidua. Together, these results reveal the centrality of regulated gene silencing in the uterine adaptation to pregnancy and suggest new areas in the study and treatment of pregnancy disorders.

Authors

Patrice Nancy, Johan Siewiera, Gabrielle Rizzuto, Elisa Tagliani, Ivan Osokine, Priyanka Manandhar, Igor Dolgalev, Caterina Clementi, Aristotelis Tsirigos, Adrian Erlebacher

Polycomb subunit BMI1 determines uterine progesterone responsiveness essential for normal embryo implantation

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Abstract

Natural and synthetic progestogens have been commonly used to prevent recurrent pregnancy loss in women with inadequate progesterone secretion or reduced progesterone sensitivity. However, the clinical efficacy of progesterone and its analogs for maintaining pregnancy is variable. Additionally, the underlying cause of impaired endometrial progesterone responsiveness during early pregnancy remains unknown. Here, we demonstrated that uterine-selective depletion of BMI1, a key component of the polycomb repressive complex-1 (PRC1), hampers uterine progesterone responsiveness and derails normal uterine receptivity, resulting in implantation failure in mice. We further uncovered genetic and biochemical evidence that BMI1 interacts with the progesterone receptor (PR) and the E3 ligase E6AP in a polycomb complex–independent manner and regulates the PR ubiquitination that is essential for normal progesterone responsiveness. A close association of aberrantly low endometrial BMI1 expression with restrained PR responsiveness in women who had previously had a miscarriage indicated that the role of BMI1 in endometrial PR function is conserved in mice and in humans. In addition to uncovering a potential regulatory mechanism of BMI1 that ensures normal endometrial progesterone responsiveness during early pregnancy, our findings have the potential to help clarify the underlying causes of spontaneous pregnancy loss in women.

Authors

Qiliang Xin, Shuangbo Kong, Junhao Yan, Jingtao Qiu, Bo He, Chan Zhou, Zhangli Ni, Haili Bao, Lin Huang, Jinhua Lu, Guoliang Xia, Xicheng Liu, Zi-Jiang Chen, Chao Wang, Haibin Wang

The SO(H)L(H) “O” drivers of oocyte growth and survival but not meiosis I

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Abstract

The spermatogenesis/oogenesis helix-loop-helix (SOHLH) proteins SOHLH1 and SOHLH2 play important roles in male and female reproduction. Although previous studies indicate that these transcriptional regulators are expressed in and have in vivo roles in postnatal ovaries, their expression and function in the embryonic ovary remain largely unknown. Because oocyte differentiation is tightly coupled with the onset of meiosis, it is of significant interest to determine how early oocyte transcription factors regulate these two processes. In this issue of the JCI, Shin and colleagues report that SOHLH1 and SOHLH2 demonstrate distinct expression patterns in the embryonic ovary and interact with each other and other oocyte-specific transcription factors to regulate oocyte differentiation. Interestingly, even though there is a rapid loss of oocytes postnatally in ovaries with combined loss of Sohlh1 and Sohlh2, meiosis is not affected and proceeds normally.

Authors

T. Rajendra Kumar

Transcription factors SOHLH1 and SOHLH2 coordinate oocyte differentiation without affecting meiosis I

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Abstract

Following migration of primordial germ cells to the genital ridge, oogonia undergo several rounds of mitotic division and enter meiosis at approximately E13.5. Most oocytes arrest in the dictyate (diplotene) stage of meiosis circa E18.5. The genes necessary to drive oocyte differentiation in parallel with meiosis are unknown. Here, we have investigated whether expression of spermatogenesis and oogenesis bHLH transcription factor 1 (Sohlh1) and Sohlh2 coordinates oocyte differentiation within the embryonic ovary. We found that SOHLH2 protein was expressed in the mouse germline as early as E12.5 and preceded SOHLH1 protein expression, which occurred circa E15.5. SOHLH1 protein appearance at E15.5 correlated with SOHLH2 translocation from the cytoplasm into the nucleus and was dependent on SOHLH1 expression. NOBOX oogenesis homeobox (NOBOX) and LIM homeobox protein 8 (LHX8), two important regulators of postnatal oogenesis, were coexpressed with SOHLH1. Single deficiency of Sohlh1 or Sohlh2 disrupted the expression of LHX8 and NOBOX in the embryonic gonad without affecting meiosis. Sohlh1-KO infertility was rescued by conditional expression of the Sohlh1 transgene after the onset of meiosis. However, Sohlh1 or Sohlh2 transgene expression could not rescue Sohlh2-KO infertility due to a lack of Sohlh1 or Sohlh2 expression in rescued mice. Our results indicate that Sohlh1 and Sohlh2 are essential regulators of oocyte differentiation but do not affect meiosis I.

Authors

Yong-Hyun Shin, Yu Ren, Hitomi Suzuki, Kayla J. Golnoski, Hyo won Ahn, Vasil Mico, Aleksandar Rajkovic