Uterine receptivity and implantation: The regulation and action of insulin-like growth factor binding protein-1 (IGFBP-1), HOXA10 and forkhead transcription factor-1 (FOXO-1) in the baboon endometrium

In primates, the phase of the menstrual cycle when the uterus becomes receptive is initially dependent on estrogen and progesterone. Further morphological and biochemical changes are induced as a result of biochemical signals between the embryo and the maternal endometrium. Blastocyst implantation in the baboon usually occurs between 8 and 10 days post ovulation and is similar to that described for the rhesus macaque. In the baboon, when chorionic gonadotropin is infused in a manner that mimics blastocyst transit, this has physiological effects on the three major cell types in the uterine endometrium. The luminal epithelium undergoes endoreplication and distinct epithelial plaques are evident. The glandular epithelium responds by inducing transcriptional and post-translational modifications in the major secretory product, glycodelin. The stromal fibroblasts initiate their differentiation process into a decidual phenotype and are characterized by the expression of actin filaments. Decidualization, is the major change that occurs in the primate endometrium after conception. During this process the fibroblast-like stromal cells change morphologically into polygonal cells and express specific decidual proteins. Studies in the baboon demonstrated that insulin-like growth factor binding protein-1 (IGFBP-1) gene expression is a conceptus-mediated response. Subsequent studies in vitro established that IGFBP-1 is transcriptionally regulated by FOXO1 and HOXA10 which together upregulate the IGFBP-1 promoter activity. A baboon endometriosis model was utilized to determine if the changes observed during uterine receptivity in normally cycling animals were compromised. The data suggests that in animals with disease, markers of uterine receptivity are not appropriately expressed in the eutopic endometrium. It is possible that these differences influence the fertility of the animals with disease and the baboon could be used as a primate model to study the causes of infertility as a result of endometriosis

Frontiers in Reproduction (FIR) : An assessment of success

© Society for the Study of Reproduction, 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biology of Reproduction 95 (2016): 27, doi:10.1095/​biolreprod.116.140384.The Frontiers in Reproduction (FIR) course has been held annually since 1998 at the Marine Biological Laboratories in Woods Hole, MA. The primary purpose of the course is to train young reproductive biologists in cutting-edge techniques that would strengthen their career opportunities. An initial evaluation of the FIR course was conducted by surveying the participants who took the course between 1998 and 2002. The findings of this survey were published in Biology of Reproduction in 2006, which highlighted the overall positive impact the course had on the training and upward career trajectory of the participants during the first 5 yr. The current study was designed to access the continued impact of FIR at the 10-yr mark by evaluating the participants who took the course between 1998 and 2008 using two different survey mechanisms. Based on these evaluations and feedback from the participants, it was evident that 1) FIR continues to have a significant positive impact on the careers of the participants, 2) the majority of the participants continue to be involved in research or administration related to the reproductive sciences, 3) nearly 90% of the attendees have been successful in obtaining funding for their research, and 4) most alumni have published at least five manuscripts in higher impact journals since they took the course. Therefore, it is evident that FIR participants are highly successful and continue to significantly impact the advances in the reproductive sciences worldwide

Chorionic gonadotropin and uterine dialogue in the primate

Implantation is a complex spatio-temporal interaction between the growing embryo and the mother, where both players need to be highly synchronized to be able to establish an effective communication to ensure a successful pregnancy. Using our in vivo baboon model we have shown that Chorionic Gonadotropin (CG), as the major trophoblast derived signal, not only rescues the corpus luteum but also modulates the uterine environment in preparation for implantation. This response is characterized by an alteration in both the morphological and biochemical activity in the three major cell types: luminal and glandular epithelium and stromal fibroblasts. Furthermore, CG and factors from the ovary have a synergistic effect on the receptive endometrium. Novel local effects of CG which influence the immune system to permit the survival of the fetal allograft and prevent endometrial cell death are also discussed in this review. An alternate extracellular signal-regulated kinase (ERK) activation pathway observed in epithelial endometrial cells and the possibility of differential expression of the CG/LH-R isoforms during gestation, open many questions regarding the mechanism of action of CG and its signal transduction pathway within the primate endometrium

Differential regulation of insulin-like growth factor binding protein-1 and -2 by insulin in the baboon (Papio anubis) endometrium

<p>Abstract</p> <p>Background</p> <p>The purpose of this study was to examine the effect of insulin on expression and synthesis of IGFBP-1 and IGFBP-2 in the baboon endometrium in vitro.</p> <p>Methods</p> <p>Baboon endometrial explants collected from cycling, ovariectomized, steroid-treated, simulated-pregnant and pregnant animals were cultured for 48 h in the presence or absence of insulin, with or without estradiol, progesterone and hCG.</p> <p>Results</p> <p>Insulin clearly inhibited IGFBP-1 production and mRNA expression in a time- and dose-dependent manner, whereas IGFBP-2 synthesis was not significantly affected. The inhibitory effects of insulin on IGFBP-1 were more evident in explants of non-pregnant tissue or tissue away from the implantation site. In the absence of insulin, synthesis of IGFBP-1 was induced in explants with low levels of de novo synthesis whereas IGFBP-2 synthesis was inhibited. This effect was potentiated by steroids and hCG in the explant cultures.</p> <p>Conclusion</p> <p>Insulin differentially regulates endometrial IGFBP-1 and IGFBP-2 secretion in the baboon.</p

Protein Inhibitor of Activated STAT3 (PIAS3) Is Down-Regulated in Eutopic Endometrium of Women with Endometriosis

Endometriosis is a major cause of chronic pelvic pain and infertility. Activation of STAT3 appears central to the inflammatory phenotype of eutopic endometrium in women with endometriosis. However, the molecular mechanism by which this occurs remains unknown. Our objective is to determine how STAT3 activity is regulated in endometriosis. Protein inhibitor of activated STAT3 (PIAS3) is a negative regulator of STAT3 activity. We examined the levels of PIAS3 in endometrium from women with and without endometriosis using Western blot analysis and immunohistochemistry. Levels of PIAS3 are significantly lower, in contrast with phosphorylation of STAT3, in women with endometriosis compared to women without endometriosis. Furthermore, induction of endometriosis in the baboon showed a significant reduction of PIAS3 expression during the progression of the disease. Interferon-γ (INFγ) reduces PIAS3 protein levels and increases phospho-STAT3 levels through CXCL10 in endometrial cells, Ishikawa, and 12Z cells. These results suggest that attenuation of PIAS3 causes aberrant activation of STAT3 in endometriosis, leading to inflammatory changes that may impair fertility or cause pain

Characterization of Uterine NK Cells in Women with Infertility or Recurrent Pregnancy Loss and Associated Endometriosis

Uterine natural killer cells (uNK) have been thought to play a key role in endometriosis and infertility. We investigated the expression of CD56, CD16 and NKp46 in endometrial tissues from 61 women with unexplained recurrent pregnancy loss (uRPL) or infertility (UI), and correlated this with the presence or absence of endometriosis. The results from the patients with sub-fertility were compared to those from 10 fertile patients

Interleukin-33 modulates inflammation in endometriosis

Abstract Endometriosis is a debilitating condition that is categorized by the abnormal growth of endometrial tissue outside the uterus. Although the pathogenesis of this disease remains unknown, it is well established that endometriosis patients exhibit immune dysfunction. Interleukin (IL)-33 is a danger signal that is a critical regulator of chronic inflammation. Although plasma and peritoneal fluid levels of IL-33 have been associated with deep infiltrating endometriosis, its contribution to the disease pathophysiology is unknown. We investigated the role of IL-33 in the pathology of endometriosis using patient samples, cell lines and a syngeneic mouse model. We found that endometriotic lesions produce significantly higher levels of IL-33 compared to the endometrium of healthy, fertile controls. In vitro stimulation of endometrial epithelial, endothelial and endometriotic epithelial cells with IL-33 led to the production of pro-inflammatory and angiogenic cytokines. In a syngeneic mouse model of endometriosis, IL-33 injections caused systemic inflammation, which manifested as an increase in plasma pro-inflammatory cytokines compared to control mice. Furthermore, endometriotic lesions from IL-33 treated mice were highly vascularized and exhibited increased proliferation. Collectively, we provide convincing evidence that IL-33 perpetuates inflammation, angiogenesis and lesion proliferation, which are critical events in the lesion survival and progression of endometriosis

Progesterone resistance in endometriosis is modulated by the altered expression of microRNA-29c and FKBP4

Context: Endometriosis results in aberrant gene expression in the eutopic endometrium (EuE) and subsequent progesterone resistance. MicroRNA (miR) microarray data in a baboon model of endometriosis showed an increased expression of miR-29c. Objectives: To explore the role of miR-29c in progesterone resistance in a subset of women with endometriosis. Design: MiR-29c expression was analyzed in the endometrium of baboons and women with or without endometriosis. The role in progesterone resistance and decidualization was analyzed by transfecting human uterine fibroblast cells with miR-29c. Patients: Subjects diagnosed with deep infiltrative endometriosis (DIE) by transvaginal ultrasound with bowel preparation underwent surgical excision of endometriosis. Eutopic secretory endometrium was collected pre- and postoperatively. Women with normal EuE and without DIE served as controls. Results: Quantitative reverse transcription polymerase chain reaction demonstrated that miR-29c expression increased, while the transcript levels of its target, FK506-binding protein 4 (FKBP4), decreased in the EuE of baboons following the induction of endometriosis. FKBP4 messenger RNA and decidual markers were statistically significantly decreased in decidualized human uterine fibroblast cells transfected with a miR-29c mimic compared with controls. Human data corroborated our baboon data and demonstrated higher expression of miR-29c in endometriosis EuE compared with normal EuE. MiR-29c was significantly decreased in endometriosis EuE postoperatively compared with preoperative tissues, and FKBP4 showed an inverse trend following radical laparoscopic resection surgery. Conclusions: We demonstrate that miR-29c expression is increased in EuE of baboons and women with endometriosis, which might contribute to a compromised progesterone response by diminishing the levels of FKBP4. Resection of DIE is likely to reverse the progesterone resistance associated with endometriosis in women

A balancing act: RNA binding protein HuR/TTP axis in endometriosis patients

Endometriosis, a major reproductive pathology affecting 8-10% of women is characterized by chronic inflammation and immune dysfunction. Human antigen R (HuR) and Tristetraprolin (TTP) are RNA binding proteins that competitively bind to cytokines involved in inflammation including: tumor necrosis factor alpha (TNF-α), granulocyte macrophage colony stimulating factor (GM-CSF), interleukin 6 (IL-6) among others, and stabilize and destabilize them, respectively. The aim of this study was to examine RNA binding protein (RNABP) HuR/TTP axis in endometriosis patients compared to menstrual stage matched healthy fertile controls in hopes of better understanding their contribution to the pathogenesis of endometriosis. Additionally, using a targeted in vitro siRNA approach, we examined whether knock-down of TTP can play a functional role on other RNABPs that competitively bind to inflammatory targets of TTP in both endometriotic and endometrial epithelial cell lines. Our results suggest that RNABPs TTP and HuR are dysregulated in endometriotic lesions compared to matched eutopic patient samples as well endometrium from healthy controls. Silencing of TTP in endometriotic and endometrial epithelial cells revealed differential response to inflammatory cytokines and other RNABPs. Our results suggest potential involvement of HuR/TTP RNA binding protein axis in regulation of inflammation in endometriosis

KRAS Activation and over-expression of SIRT1/BCL6 Contributes to the Pathogenesis of Endometriosis and Progesterone Resistance

Endometriosis is an inflammatory condition that is associated with progesterone resistance and cell proliferation, resulting in pain, infertility and pregnancy loss. We previously demonstrated phosphorylation of STAT3 in eutopic endometrium of infertile women with this disorder leading to over-expression of the oncogene BCL6 and stabilization of hypoxia-induced factor 1 alpha (HIF-1α). Here we report coordinated activation of KRAS and over-expression of Sirtuin 1 (SIRT1), a histone deacetylase and gene silencer, in the eutopic endometrium from women with endometriosis throughout the menstrual cycle. The mice with conditional activation of KRAS in the PGR positive cells reveal an increase of SIRT1 expression in the endometrium compared to control mice. The expression of progesterone receptor target genes including the Indian Hedgehog pathway genes are significantly down-regulated in the mutant mice. SIRT1 co-localizes with BCL6 in the nuclei of affected individuals and both proteins bind to and suppress the promoter of GLI1, a critical mediator of progesterone action in the Indian Hedgehog pathway, by ChIP analysis. In eutopic endometrium, GLI1 expression is reduced in women with endometriosis. Together, these data suggest that KRAS, SIRT1 and BCL6 are coordinately over-expressed in eutopic endometrium of women with endometriosis and likely participate in the pathogenesis of endometriosis