Biomedical subjects

Rebecca L Jones

Publications and source records attributed to Rebecca L Jones.

13 recordsLinked to original sources

PubMed2006

The chemokines, CX3CL1, CCL14, and CCL4, promote human trophoblast migration at the feto-maternal interface.

Human embryo implantation is a complex process involving blastocyst attachment to the endometrial epithelium and subsequent trophoblast invasion of the decidua. Chemokines, critical regulators of leukocyte migration, are abundant in endometrial epithelial and decidual cells at this time. We hypothesized that endometrial chemokines stimulate trophoblast invasion. Chemokine receptors CX3CR1 and CCR1 were immunolocalized in human first-trimester implantation sites, specifically to endovascular extravillous trophoblasts, but not to the invading interstitial EVTs (iEVTs), with weak staining also on syncytium. CCR3 was localized to invading iEVTs and to microvilli on the syncytial surface. Expression of CX3CL1 (fractalkine), CCL7 (MCP-3), and their receptors (CX3CR1, CCR1, CCR2, CCR3, and CCR5) mRNA was examined in cellular components of the maternal-embryonic interface by RT-PCR. Both chemokines were abundant in entire endometrium and placenta, endometrial cells (primary cultures and HES, a human endometrial epithelial cell line) and trophoblast cell lines (JEG-3, ACIM-88, and ACIM-32). Chemokine receptor mRNA was expressed by placenta and trophoblast cell lines: CCR1 by all trophoblast cell types, whereas CCR2, CCR3, and CX3CR1 were more variable. CX3CR1, CCR1, CCR2, and CCR5 were also expressed by endometrial cells. Migration assays used the trophoblast cell line most closely resembling extravillous cytotrophoblast (AC1M-88). Trophoblast migration occurred in response to CX3CL1, CCL14, and CCL4, but not CCL7. Endometrial cell-conditioned media also stimulated trophoblast migration; this was attenuated by neutralizing antibodies to CX3CL1 and CCL4. Thus, chemokines are expressed by maternal and embryonic cells during implantation, whereas corresponding receptors are on trophoblast cells. Promotion of trophoblast migration by chemokines and endometrial cell conditioned medium indicates an important involvement of chemokines in maternal-fetal communication.

Cell Line↗

PubMed2006

Activin-A secretion is increased in the eutopic endometrium from women with endometriosis.

BACKGROUND: Activin is a well-characterised growth and differentiation factor and an important inflammatory mediator. Activin is secreted by normal endometrial glands and stroma and is expressed by endometrial leucocytes. It is also known that the eutopic endometrium from women with endometriosis is functionally different to that from women without endometriosis. In this study, we hypothesise that the endometrial secretion of activin is altered in women with endometriosis. AIMS: To determine whether the expression of inhibin/activin subunits and the secretion of activin-A is different in eutopic endometrium from women with and without endometriosis. METHODS: Endometrial biopsies were obtained from premenopausal, regularly menstruating women with and without endometriosis. Staining intensity for the different inhibin/activin subunits was compared in endometrial and endometriotic biopsies. Activin-A secretion was studied using endometrial explants and endometrial glandular and stromal monolayer cell cultures. RESULTS: The alpha- and betaA-subunits of inhibin/activin were more abundant in eutopic glandular cells from patients with minimal to mild endometriosis compared to women without endometriosis. In patients with endometriosis, the betaB-subunit was more abundant in eutopic stromal cells and endometrial leucocytes. Comparison of paired endometrial and endometriotic biopsies from the same patient did not reveal significant differences for any of the inhibin/activin subunits or activin receptors. Activin-A secretion by glandular and stromal endometrial cells was sevenfold and threefold higher, respectively, in women with endometriosis compared to women without endometriosis. CONCLUSIONS: The expression of inhibin/activin subunits in eutopic endometrium is altered in women with endometriosis, leading to higher levels of activin-A secretion by both glandular cells and stromal cells.

Activins↗

PubMed2006

The role of activins during decidualisation of human endometrium.

Decidualisation of the endometrial stroma is critical to create a specialised environment for embryo implantation and trophoblast invasion; however, the mechanisms involved are poorly understood. We have established that activin A is an important regulator of decidualisation of endometrial stromal cells in vitro. Here we describe studies that verify the physiological significance of these findings. We demonstrate that high concentrations of activin A are produced by decidualising cells in excess of the antagonists, inhibin and follistatin, thus confirming its bioavailability within the decidual environment. Furthermore, we demonstrate that all components of the activin signalling pathway (activin receptors and Smads) are expressed in decidualised cells, and identify a downstream mechanism for activin in the endometrium, through the regulation of matrix metalloproteinases (MMPs). This new knowledge is important for understanding the roles for activins and inhibins in regulating fertility.

Activins↗

PubMed2006

Complex expression patterns support potential roles for maternally derived activins in the establishment of pregnancy in mouse.

Maternal-fetal communications are critical for the establishment of pregnancy. Embryonic growth and differentiation factors produced by the oviduct and uterus play essential roles during the pre- and early post-implantation phases. Although several studies indicate roles for activin in embryonic development, gene-knockout studies have failed to identify a critical role in mammalian embryogenesis. We hypothesized that activin is produced by maternal tissues during the establishment of pregnancy, and thus maternally derived activin could compensate for the absence of embryonic activin in null homozygotes during critical developmental stages. We investigated the expression of inhibin alpha, activin betaA, and betaB subunits in the mouse oviduct and uterus during the estrous cycle and early pregnancy, and in the early conceptus. Inhibin alpha subunit was weakly expressed, while activin betaA and betaB subunits were strongly expressed in oviduct and uterus at estrous, and dramatically upregulated in the uterus on each day of pregnancy between days 3.5 and 8.5 post coitum. Prior to implantation, activin betaA and betaB subunits were immunolocalized to oviductal and uterine epithelial cells; following implantation they were expressed in the stroma, in a wave preceding decidualization. Later in pregnancy, activin betaA and betaB subunits were present in decidua basalis, trophoblast giant cells, and labyrinth zone of the developing placenta. Expression of activin betaA subunit was also detected in blastocysts and early post-implantation embryos. These data are consistent with a role for maternally derived activins in the support of the pre-implantation embryo, and during gastrulation and embryogenesis.

Activins↗

PubMed2006

TGF-beta superfamily expression and actions in the endometrium and placenta.

Transforming growth factor beta (TGFbeta) superfamily members are closely associated with tissue remodelling events and reproductive processes. This review summarises the current state of knowledge regarding the expression and actions of TGFbeta superfamily members in the uterus, during the menstrual cycle and establishment of pregnancy. TGFbetas and activin beta subunits are abundantly expressed in the endometrium, where roles in preparation events for implantation have been delineated, particularly in promoting decidualisation of endometrial stroma. These growth factors are also expressed by epithelial glands and secreted into uterine fluid, where interactions with preimplantation embryos are anticipated. Knockout models and embryo culture experiments implicate activins, TGFbetas, nodal and bone morphogenetic proteins (BMPs) in promoting pre- and post-implantation embryo development. TGFbeta superfamily members may therefore be important in the maternal support of embryo development. Following implantation, invasion of the decidua by fetal trophoblasts is tightly modulated. Activin promotes, whilst TGFbeta and macrophage inhibitory cytokine-1 (MIC-1) inhibit, trophoblast migration in vitro, suggesting the relative balance of TGFbeta superfamily members participate in modulating the extent of decidual invasion. Activins and TGFbetas have similar opposing actions in regulating placental hormone production. Inhibins and activins are produced by the placenta throughout pregnancy, and have explored as a potential markers in maternal serum for pregnancy and placental pathologies, including miscarriage, Down's syndrome and pre-eclampsia. Finally, additional roles in immunomodulation at the materno-fetal interface, and in endometrial inflammatory events associated with menstruation and repair, are discussed.

Activins↗

PubMed2005

Activin A and inhibin A differentially regulate human uterine matrix metalloproteinases: potential interactions during decidualization and trophoblast invasion.

Embryo implantation and trophoblast invasion are tightly regulated processes, involving sophisticated communication between maternal decidual and fetal trophoblast cells. Decidualization is a prerequisite for successful implantation and is promoted by a number of paracrine agents, including activin A. To understand the downstream mechanisms of activin-promoted decidualization, the effects of activin on matrix metalloproteinases (MMPs) (important mediators of decidualization) were investigated. Activin A stimulated endometrial production of proMMPs-2, -3, -7, -9, and active MMP-2. In contrast, inhibin A was a potent inhibitor of proMMP-2, and antagonized the effect of activin on MMPs. Activin is up-regulated with decidualization, and MMPs-2, -3, and -9 increase in parallel. Furthermore, proMMP-2 production is stimulated when decidualization is accelerated with activin, and suppressed when activin is neutralized, attenuating decidualization. These data support that activin A promotes decidualization through up-regulating MMPs. Previous in vitro evidence proposes further roles for activin and MMPs in promoting trophoblast invasion; therefore, we examined their interrelationships in early human implantation sites. MMPs-7 and -9 were produced by static cytotrophoblast subpopulations, whereas MMP-2 was strikingly up-regulated in invasive extravillous cytotrophoblasts (EVT). Maternal decidua is the primary source of activin, where a role in stimulating MMP-2 in iEVTs can be envisaged. Inhibin was absent from cytotrophoblast populations, except for a dramatic up-regulation in endovascular EVT plugs, coinciding with a down-regulation of MMP-2. This suggests that inhibin may have a role in the cessation of vascular invasion. These data support that activin, via effects on MMPs, is an important factor in the maternal-fetal dialog regulating implantation.

Activins↗

PubMed2005

Chemokine expression is dysregulated in the endometrium of women using progestin-only contraceptives and correlates to elevated recruitment of distinct leukocyte populations.

BACKGROUND: Breakthrough bleeding (BTB) is the most common reason for discontinuation of progestin-only (p-only) contraceptives, yet the causes are unknown. Use of p-only contraceptives is associated with elevated influx of endometrial leukocytes, similar to that observed perimenstrually or within decidualized endometrium. We hypothesized that chemokine expression is altered in women using p-only contraceptives, leading to abnormal leukocyte recruitment and BTB. METHODS: Expression of eight highly abundant endometrial chemokines was examined using immunohistochemistry and real-time PCR, in endometria from women using subdermal and intrauterine levonorgestrel and correlated to leukocyte subpopulations. RESULTS: Macrophage-derived chemokine (MDC), hemofiltrate CC chemokine-1 (HCC-1), monocyte chemoattractant protein-3 (MCP-3), interleukin-8 (IL-8) and eotaxin were strongly produced by epithelial glands, comparable to levels in premenstrual phase endometrium. Stromal cells were negative for chemokines in atrophic/shedding endometria, but intensely positive in highly decidualized tissues for MDC, MCP-3, HCC-1 and 6Ckine. Macrophage inflammatory protein-1beta (MIP-1b) and HCC-4 were suppressed in all p-exposed endometria. CONCLUSIONS: These data demonstrate that chemokine expression is dysregulated in p-exposed endometria, consistent with the morphological appearance of the endometrium and the leukocyte subsets present. This reinforces a potential role for chemokines in the elevated leukocyte recruitment that contributes to endometrial fragility and BTB.

Cell Proliferation↗

PubMed2005

Expression patterns of hyaluronan, hyaluronan synthases and hyaluronidases indicate a role for hyaluronan in the progression of endometrial cancer.

OBJECTIVE: The extracellular glycosaminoglycan hyaluronan (HA) and its degradative enzymes, hyaluronidases (Hyal), play important roles in tumor metastasis and angiogenesis. HA promotes tumor cell adhesion and migration, while its cleaved fragments stimulate angiogenesis. The aims of this study were to assess the levels of HA and how it might be regulated in endometrial cancer. METHODS: Endometrial carcinomas were grouped according to histologic grade (Grade 1-3). HA histochemistry utilized a biotinylated HA binding peptide (n = 15), while HA synthase (HAS) immunohistochemistry utilized an antibody recognizing HAS1, HAS2 HAS3 (n = 24). Real-time RT-PCR was used to determine the mRNA expression of Hyal 1, Hyal 2 (n = 13) and Hyal 3 (n = 11) in endometrial carcinomas. RESULTS: HA, its synthases and degradative enzymes were identified in endometrial carcinomas of all histologic grades. HA was predominantly localized to tumor-associated stroma. Semiquantitative analysis revealed increased HA levels with tumor grade, however, this increase only attained significance in Grade 2 carcinomas (P < 0.05). HA staining intensity scores were significantly associated with the presence of myometrial invasion (P < 0.05). Alternatively, HAS was predominantly localized in tumor epithelial cells, and its levels did not vary with tumor grade. Expression of Hyal 3 and Hyal 2 mRNA were >1000-fold and >30-fold greater respectively than that of Hyal 1 mRNA, the major Hyal expressed in other cancers. No Hyal type varied with tumor grade. CONCLUSION: This is the first study to demonstrate the cellular localization of HA and its synthases and that Hyal 3 mRNA is predominant in endometrial cancer. The results suggest a role for elevated HA in endometrial cancer progression.

Aged↗

PubMed2004

Coexpression of fractalkine and its receptor in normal human endometrium and in endometrium from users of progestin-only contraception supports a role for fractalkine in leukocyte recruitment and endometrial remodeling.

Leukocytes are critical mediators of endometrial remodeling, but the mechanisms by which leukocyte subpopulations enter the uterus are currently unknown. Endometrial leukocytes have no genomic progesterone receptors; thus, we hypothesized that leukocyte migration is induced indirectly by progesterone-regulated chemokines. Fractalkine (CX3CL1), a chemotactic membrane-bound adhesion factor, and its receptor (CX3CR1) were assessed by immunohistochemistry in endometrial samples across the menstrual cycle, in early pregnancy, and in women using progestin-only contraceptives. Fractalkine was localized predominantly to glandular epithelial and decidualized stromal cells, with the highest staining intensity in the secretory phase and early pregnancy. It was also detected in subpopulations of endometrial leukocytes (macrophages and uterine NK cells), with maximal numbers during the proliferative phase and early pregnancy. CX3CR1 was similarly colocalized to the glandular epithelium and decidualized stromal cells, with the highest expression in the secretory phase. CX3CR1-positive leukocytes (macrophages and neutrophils) were in greatest abundance during the menstrual phase. In the endometrium of women using progestin-only contraceptives, immunoreactive fractalkine was markedly reduced in the glandular epithelium, but was increased in decidualized stroma and infiltrating leukocytes. These findings support a number of roles for fractalkine in the endometrium, in the secretory phase, in early pregnancy, and when influenced by progestin-only contraceptives.

CX3C Chemokine Receptor 1↗

PubMed2004

Identification of chemokines important for leukocyte recruitment to the human endometrium at the times of embryo implantation and menstruation.

Human endometrium possesses a unique immunological environment enabling implantation of the semiallogeneic embryo. Large populations of macrophages and uterine-specific natural killer cells infiltrate the implantation site, believed to be important modulators of trophoblast invasion and decidualization. In the absence of pregnancy, there is a dramatic influx of neutrophils, eosinophils, and macrophages, likely to be critical for focal inflammatory endometrial destruction. However, little is known regarding selective recruitment of leukocyte subtypes. We employed a gene array approach to analyze the expression of 21 chemokines in endometrium. Real-time RT-PCR and immunohistochemistry was conducted to verify expression patterns and determine cellular source. Nine chemokines were highly abundant in human endometrium: monocyte chemotactic protein-3, eotaxin, fractalkine, macrophage inflammatory protein-1beta, 6Ckine, IL-8, hemofiltrate CC chemokine-1 and -4, and macrophage-derived chemokine. Chemokine mRNA was generally up-regulated during endometrial receptivity and early pregnancy, particularly of macrophage and natural killer chemoattractants. Chemokine protein was predominantly localized to epithelial glands, whereas differentiated stromal cells were a major source of chemokines after decidualization. This is the first study to use an unbiased approach to screen for endometrial chemokines, and we report the selective regulation of chemokines, corresponding to the recruitment of distinct leukocyte subpopulations required for pregnancy and menstruation.

Cell Movement↗

PubMed2002

Expression of activin receptors, follistatin and betaglycan by human endometrial stromal cells; consistent with a role for activins during decidualization.

Decidualization of the human endometrium is critical for implantation, but the mechanisms involved are largely unknown. Activin subunits are expressed in endometrium during decidualization. From its known actions in cell differentiation and tissue remodelling, we hypothesized that activin A is involved in the paracrine regulation of decidualization. We examined the expression of activin receptors (ActRs) by semi-quantitative and real-time RT-PCR. mRNA for all ActR subtypes (Ia, Ib, IIa and IIb) was detected in endometrium, with maximal expression in the early secretory phase and in early pregnancy. ActR protein was localized exclusively to stromal and endothelial cells. This expression pattern was confirmed by in-situ hybridization. Activin bioavailability is locally regulated by its binding protein, follistatin, and also by the antagonist, inhibin. Inhibin competition for ActRII binding is enhanced by the binding protein, betaglycan. Follistatin and betaglycan were also detected in the endometrium, localized to stromal and epithelial cells. This co-expression of activin subunits, receptors and binding proteins indicates that stromal cells are capable of responding to activin, and that there is tight local regulation of activin action within the endometrium. As activin production is up-regulated in decidual cells, this provides further evidence for an involvement of activins during stromal cell decidualization.

Activin Receptors↗

PubMed2002

Activin A promotes human endometrial stromal cell decidualization in vitro.

Decidualization of the endometrium is critical for implantation and placental development. Stromal cells differentiate causing widespread tissue remodeling. The mechanisms involved are unknown, although a number of known paracrine factors play contributory roles. From its known actions on cell differentiation and remodeling, we hypothesized that activin A regulates decidualization. Stromal cells produce activin beta A subunits with the onset of decidualization, and these cells coexpress activin receptors. Utilizing an in vitro model of stromal cell decidualization, we demonstrate that high concentrations of dimeric activin A are produced by decidual cells. Addition of activin A to cells undergoing decidualization resulted in a dose-dependent increase in PRL production, an established marker of decidualization. This response was inhibited by co-treatment with follistatin. Neutralization of endogenous activins significantly reduced the decidual response. This is the first report of dimeric activin A production by decidualized cells, and is evidence for a autocrine/paracrine action of activin A within the endometrium. The demonstration that activin A enhances the decidual reaction in vitro suggests that it plays a key role in promoting stromal cell decidualization. This data provides insights into the processes underlying decidualization, which is important for understanding implantation and placentation and has potential clinical applications for the regulation of fertility.

Activins↗

PubMedDate not supplied

Potential roles for endometrial inhibins, activins and follistatin during human embryo implantation and early pregnancy.

The human endometrium is a remarkably dynamic tissue, undergoing cycles of proliferation, differentiation and breakdown every 28 days. In preparation for embryo implantation, the endometrium differentiates or decidualizes, involving widespread morphological and functional differentiation of endometrial stromal cells. If pregnancy occurs, the decidua regulates trophoblast invasion and forms the maternal component of the placenta. Uterine remodeling has long been known to be regulated by the ovarian steroid hormones 17beta-estradiol and progesterone; however, only recently has the importance of paracrine factors in mediating the cellular and biochemical changes been recognized. Many growth factors and cytokines, such as inhibins and activins, whose expression is generally limited to developmental and pathological states, are produced by actively remodeling endometrial cells, and play crucial roles in regulating endometrial cell function. Here, we present evidence for integral roles for the inhibin and activin family in the paracrine regulation of endometrial receptivity, decidualization and implantation.

Activin Receptors↗