Matrix metalloproteinase expression during mouse peri-implantation development

Potential role of intermedin/adrenomedullin 2 in early embryonic development in rats

Adrenomedullin2 (ADM2), also referred to as Intermedin (IMD) is expressed in trophoblast cells in human placenta and enhances the invasion and migration of first trimester HTR-8/SV-neo cells. Recently we demonstrated that infusion of IMD antagonist in pregnant rats causes feto-placental growth restriction suggesting a role for IMD in maintaining a successful pregnancy. Therefore, this study was undertaken to assess if IMD has a functional role in embryo implantation in a rat model. We show that IMD mRNA is expressed in rat implantation sites and its expression is significantly higher on day 15 in placenta compared to days 18-22. Infusion of IMD antagonist IMD₁₇₋₄₇ from day 3 of pregnancy causes a significant decrease in the weights of day 9 implantation sites as well as serum levels of 17β-estradiol, progesterone, nitric oxide and serum MMP2 and MMP9 gelatinase activity. Further, expression of MMP2, MMP9, VEGF and PLGF protein levels are significantly downregulated in the implantation sites of IMD antagonist treated rats. This study suggests a potential involvement of IMD in regulating the factors that are critical for implantation and growth of the embryo and thus in establishment of normal rat pregnancy.

Dynamic in vivo changes in the activities of gelatinases, matrix metalloproteinases (MMPs), and tissue inhibitor of metalloproteinases (TIMPs) in buffalo (Bubalus bubalis) uterine luminal fluid during estrous cycle and early pregnancy

In ruminants, the phenomenon of endometrial tissue remodeling during the estrous cycle and early pregnancy is not fully understood. In this report, the occurrence of tissue remodeling, if any, in buffalo endometrium was studied by detecting gelatinases, matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs); the key regulators of tissue remodeling, in uterine luminal fluids (ULF) of cycling and early pregnant (approx. 43-65 days) buffaloes. Each stage of the estrous cycle and pregnant ULF demonstrated a unique profile of gelatinase activities compared to serum/follicular fluid, with a major gelatinase band of 60 kDa with highest activity in early-luteal stage. In addition to a 32 kDa uterus-specific gelatinase band detected in both non-pregnant and pregnant ULFs, the pregnant ULF displayed three new gelatinase bands of 86, 78, and 57 kDa. Western blot technique confirmed the presence of MMP-2 (54 kDa), MMP-9 (76/73 kDa), TIMP-1 (32 kDa), TIMP-2(20 kDa), and two molecular weight forms (31 and 22 kDa) of TIMP-3 in buffalo ULF with varying band intensities. Highest MMP-2 and MMP-9 activities were observed in follicular and early-luteal stage ULFs, respectively. Highest TIMP-1 activity was observed in early-luteal ULF. Interestingly, TIMP-2 activity was only detected in mid-luteal, late-luteal, and follicular stage ULFs with significantly increasing intensities. Highest activities of 31 and 22 kDa TIMP-3 were associated with late-luteal and early-luteal stage ULFs, respectively. The varied activities of MMPs and TIMPs in buffalo ULF during the estrous cycle and early pregnancy might be a reflection of dynamic structural remodeling of the endometrium and/or developing conceptus.

Brain-derived neurotrophic factor promotes implantation and subsequent placental development by stimulating trophoblast cell growth and survival

Successful implantation of the blastocyst and subsequent placental development is essential for reproduction. Expression of brain-derived neurotrophic factor (BDNF) and neurotrophin-4/5, together with their receptor, tyrosine kinase B (TrkB), in trophectoderm cells of blastocyst suggests their potential roles in implantation and placental development. Here we demonstrated that treatment with BDNF promoted blastocyst outgrowth, but not adhesion, in vitro and increased levels of the cell invasion marker matrix metalloproteinase-9 in cultured blastocysts through the phosphatidylinositol 3-kinase pathway. After implantation, BDNF and neurotrophin-4/5 proteins as well as TrkB were expressed in trophoblast cells and placentas during different stages of pregnancy. Both TrkB and its ligands were also expressed in decidual cells. Treatment of cultured trophoblast cells with the TrkB ectodomain, or a Trk receptor inhibitor K252a, suppressed cell growth as reflected by decreased proliferation and increased apoptosis, whereas an inactive plasma membrane nonpermeable K252b was ineffective. Studies using the specific inhibitors also indicated the importance of the phosphatidylinositol 3-kinase/Akt pathway in mediating the action of TrkB ligands. In vivo studies in pregnant mice further demonstrated that treatment with K252a, but not K252b, suppressed placental development accompanied by increases in trophoblast cell apoptosis and decreases in placental labyrinth zone at midgestation. In vivo K252a treatment also decreased fetal weight at late gestational stages. Our findings suggested important autocrine/paracrine roles of the BDNF/TrkB signaling system during implantation, subsequent placental development, and fetal growth by increasing trophoblast cell growth and survival.

Expression of extracellular matrix metalloproteinase inducer and matrix metalloproteinases during mouse embryonic development

Mouse embryo implantation is a highly invasive and controlled process that involves remodeling and degradation of the extracellular matrix of the uterus. Matrix metalloproteinases (MMPs) are the main proteinases facilitating this process. Extracellular matrix metalloproteinase inducer (EMMPRIN) can stimulate the production of MMPs and is required for successful implantation in the mouse. The aims of the present study were to examine the expression profiles of mRNA and proteins for EMMPRIN and MMPs in the developing mouse embryoin vitro, and to study whether EMMPRIN protein induces the production of MMPs by mouse blastocysts. EMMPRIN mRNA, detected by RT-PCR, was present at all stages of embryo development from the one-cell to the blastocyst outgrowth. EMMPRIN protein, observed by confocal microscopy, was present on the cell surface at the same stages of development as was the mRNA. Of seven MMPs studied, murine collagenase-like A (Mcol-A), murine collagenase-like B (Mcol-B) and gelatinase A (MMP-2) mRNAs were detected only in blastocyst outgrowths by RT-PCR. Gelatinase B (MMP-9) mRNA was detected both in expanded blastocysts and blastocyst outgrowths. MMP-2 and -9 proteins were detected in the cytoplasm of outgrowing trophoblast cells. Collagenase-2 (MMP-8), collagenase-3 (MMP-13), or stromelysin-1 (MMP-3) mRNAs were not present at any stage of pre- or peri-implantation mouse embryo development. Quantitative RT-PCR analyses showed that recombinant EMMPRIN protein did not stimulate MMP-2 or -9 expression by mouse blastocyst outgrowths. These data suggest that EMMPRIN may regulate physiological functions other than MMP production by mouse embryos during implantation.

Role of Neutrophils in Matrix Metalloproteinase Activity in the Preimplantation Mouse Uterus1

Matrix metalloproteinases (MMPs) have been implicated in embryonal implantation processes such as trophoblast invasion and decidualization. The temporal and spatial distributions of MMP bioactivities were analyzed by in situ zymography, which indicated these activities to be markedly increased in the postcoital mouse uterus compared with those in the later implantation stage. Activity was ascribed to proMMP9, which moved from the uterine serosa to the endometrium but was not associated with mRNA up-regulation. The activity was colocalized with infiltrating neutrophils, and neutropenic mice did not exhibit MMP9 expression. Removing the seminal vesicles from male mice abolished the postcoital increase in MMP9 in the female. These results indicate the major MMP activity in the preimplantation uterus to originate in proMMP9-bearing neutrophils attracted by seminal plasma. Considering our results together with those of previous reports of reduced fertility in Mmp9-deficient female mice, we speculate that neutrophil infiltration participates in the extracellular matrix degradation needed to support pregnancy.

A ‘minimum dose’ of lipopolysaccharide required for implantation failure: assessment of its effect on the maternal reproductive organs and interleukin-1α expression in the mouse

Genital tract infections caused by gram-negative bacteria induce abortion and are one of the most common complications of human pregnancy. This study was carried out to decipher the mechanism of gram-negative bacterial lipopolysaccharide (LPS)-induced pregnancy loss, using a mouse (Park strain) model. Since many of the biological effects of LPS are mediated by interleukin (IL)-1α, the role of IL-1α in LPS-induced pregnancy loss was studied. Pregnant female animals were injected intra-peritoneally (i.p.) with different doses (1 to 50 μg) of LPS from Salmonella minnesota Re-595, on day 0.5 of pregnancy. We found that 250 μg/kg body weight (i.e. 5 μg/female mouse) of LPS when given on day 0.5 of pregnancy was the ‘minimum dose’ (MD) required to completely inhibit the implantation of the blastocyst in the mouse. The effect of this dose on the pathophysiology of the various reproductive organs (i.e. uterus, ectoplacental cones, developing fetus, ovaries etc.) was assessed on day 14 of pregnancy. The effects of this dose on the level and pattern of expression of the proinflammatory cytokine IL-1α in the maternal uterine horns and preimplantation stage embryos were studied by RT-PCR. A single dose (100 ng/mouse) of recombinant mouse IL-1α was given i.p. to pregnant females on day 1 of pregnancy to study its effect on implantation. Our results show that treatment of the pregnant animals with LPS may alter cell proliferation and induce leukocyte infiltration, degeneration of luminal glandular epithelium, and hyperplasia in the various reproductive organs, and may also alter both embryonic and uterine IL-1α expression. IL-1α administration also caused implantation failure similar to that of LPS. The observations suggest that the determined MD of LPS may alter the expression of developmentally important proinflammatory cytokines such as IL-1α, which could, in turn, inhibit the normal processes of blastocyst implantation. Therefore, it is proposed that the LPS-induced histopathological alterations in the various reproductive organs of pregnant animals could be mediated by IL-1α and this may be one of the causes of failure of blastocyst implantation in the mouse.

Comprehending the role of LPS in Gram-negative bacterial vaginosis: ogling into the causes of unfulfilled child-wish

INTRODUCTION

Intrauterine infection is frequently associated with pregnancy loss in pregnant women.

DISCUSSION

This article reviews the role of Gram-negative bacterial infection in various complications related to early pregnancy and subsequent pregnancy loss. Here we discuss the pathways of ascending intrauterine infection, microbiology and the pathophysiology of such infections. The clinical impact, therapy, consequences, prevention and implications of Gram-negative bacterial infections in women during their reproductive life span is also discussed. This article also makes an attempt to discuss our studies and findings, related to the effect of the LPS component of the Gram-negative bacterial endotoxin on preimplantation stage embryonic development and implantation. This early phase of pregnancy remains mostly unnoticed by the mother as well as the health care provider, and therefore holds more threat to the life of the fetus and the mother. The molecular mechanisms of LPS-induced pregnancy losses through abnormal embryonic development, implantation failure, and preterm labor and birth with specific references to the role of proinflammatory cytokines like IL-1 and TNF are discussed.

CONCLUSION

Once these inflammatory mediators have increased in the feto-maternal tissues, it may be too late or harmful to try and prevent the adverse outcomes of pregnancy.

Gram-Negative Bacterial Endotoxin- Induced Infertility: A Birds Eye View

Alleviation of infertility on the one hand and development of improved methods of contraception on the other are global concerns to woman's health. The molecular signals that regulate implantation are of clinical relevance since understanding the nature of these signals may lead to strategies to correct implantation failure and to develop novel contraceptive approaches. The other pressing concern is the poor pregnancy rate resulting from in vitro fertilization (IVF). The pregnancy rate in IVF programs remains about 20-30% in spite of the high rate of successful fertilization. This has led to the proposition that additional uterine factors, critical for the implantation process, must be limiting. Identification of such parameters could help in determining the appropriate physiological state of the uterus for embryo transfer. Several factors are known to have a direct or indirect impact on the ability of the uterus to develop to a functionally receptive state. This would disrupt the normal coordination between embryonic and uterine development even though all molecular players may seem otherwise normal.

Synergistic effects of antiprogestins and iNOS or aromatase inhibitors on establishment and maintenance of pregnancy

Progesterone is known to be involved in many steps in female reproduction including control of implantation and uterine-cervical function during pregnancy. Our studies in rats and guinea pigs indicate that progesterone inhibits uterine contractility and cervical softening during pregnancy. Progesterone levels or actions decline near the end of pregnancy leading to the onset of labor. Treatment with progestin agonists prolongs pregnancy and inhibits cervical softening, whereas treatment with antiprogestins (mifepristone or onapristone) stimulates uterine contractility, cervical softening and premature delivery. Thus the effect of progesterone receptor modulators in the uterus and cervix depend up on the degree of intrinsic agonistic/antagonistic activities. Our recent studies show that progesterone interacts with nitric oxide (NO) to maintain pregnancy and that administration of progesterone antagonists with NO synthase inhibitors act synergistically to stimulate labor. In addition our studies show that combinations of progesterone antagonists with aromatase inhibitors act synergistically to induce labor. Similarly antiprogestins interact with NO synthase or aromatase inhibitors to block implantation through action on the endometrium. These studies suggest new applications for combined therapies of progestin receptor modulators with aromatase inhibitors or agents that modify NO production for contraception, stimulation of labor, estrogen-dependent diseases and improved outcomes in pregnancy.

Differential regulation of the expression of matrix metalloproteinases and tissue inhibitors of metalloproteinases by cytokines and growth factors in bovine endometrial stromal cells and trophoblast cell line BT-1 in vitro

Degradation and reconstitution of extracellular matrix in uterine endometrium is a crucial event for embryonic implantation and is regulated by matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). In the present study, we investigated the regulation of MMP and TIMP expression in cultured bovine endometrial stromal cells (BESCs) and a bovine trophoblast cell line BT-1 (BT-1 cells). The production of proMMP-9 was induced by transforming growth factor beta (TGFbeta) and 12-O-tetradecanoylphorbol 13-acetate in the stromal cells. The treatment of BESCs with TGFbeta, insulin-like growth factor-I, and hepatocyte growth factor (HGF) resulted in a significant increase in the level of TIMP-1 in the culture medium. In addition, a significant increase of TIMP-2 production was observed in interleukin (IL)-1alpha and HGF-treated BESCs. However, the expression of TIMP-1 and TIMP-2 mRNA was not augmented by these factors. The treatment of BESCs with 12-O-tetradecanoylphorbol 13-acetate resulted in a significant increase in the level of TIMP-1 but a significant decrease in the level of TIMP-2 in the stromal cells. Membrane type-1 MMP mRNA expression in the stromal cells was augmented by tumor necrosis factor alpha (TNFalpha), IL-6, HGF, and 12-O-tetradecanoylphorbol 13-acetate. On the other hand, BT-1 cells constitutively produced proMMP-9 and proMMP-2, and the treatment of BT-1 cells with TNFalpha, HGF, and 12-O-tetradecanoylphorbol 13-acetate resulted in a significant increase in the level of proMMP-9 but not in the level of proMMP-2. The production of TIMP-1 in BT-1 cells was also augmented by IL-1alpha, TNFalpha, and HGF at the level of translation and was transcriptionally increased by 12-O-tetradecanoylphorbol 13-acetate. However, the level of TIMP-2 mRNA in BT-1 cells was not affected by any of the treatments. These results suggest that the expression of MMPs and TIMPs is differentially regulated by cytokines and growth factors and that the production of TIMP-1 and TIMP-2 may not be accompanied by changes in their mRNA expression in bovine endometrium and trophoblasts. Furthermore, as in humans and rodents, MMPs and TIMPs may contribute to the control of degradation and reconstitution of extracellular matrix in bovine endometrium during embryonic implantation and early placentation.

Nitric oxide induces gelatinase A (matrix metalloproteinase 2) during rat embryo implantation

OBJECTIVE

To evaluate a reciprocal signaling interaction initiated by embryo-derived nitric oxide (NO) to facilitate implantation by increased production of gelatinase A (matrix metalloproteinase 2, MMP2) in uterine stroma.

DESIGN

Experimental animal studies.

SETTING

Reproductive-physiology research laboratory.

ANIMAL(S)

Female syngeneic Wistar rats aged 14 weeks.

INTERVENTION(S)

Vaginal smears to confirm pregnancy. Oviductal ligature to avoid the descent of blastocysts to the uterine lumen. Plasma exudation assays to locate uterine blastocyst implantation sites. Organ cultures treated with NO donors and nitric oxide synthase (NOS) inhibitors.

MAIN OUTCOME MEASURE(S)

Expression of MMP2 and NO was assessed by Western blot and zymography of tissue extracts and by immunofluorescence of tissue sections.

RESULT(S)

An increase in MMP2 activity was found in uterine extracts in early pregnant rats and was concentrated at implantation sites. Immunolocalization experiments showed that inducible NOS was expressed on the surface of the implanting blastocyst adjacent to the uterine epithelium at the sites of increased MMP2 expression. In organ culture experiments, NO donors were found to increase, whereas NOS inhibitors were found to decrease MMP2 activity in uterine tissue sections.

CONCLUSION(S)

Blastocyst-derived NO contributes to the production of uterine-derived MMP2, an essential component of implantation and initiation of placentation.

Serglycin proteoglycan synthesis in the murine uterine decidua and early embryo

This study has explored the localization and synthesis of the serglycin proteoglycan in the murine embryo and uterine decidua during midgestation. Embryos in deciduae were subjected to in situ hybridization with cRNA probes and to immunohistochemical detection with a specific antibody against murine serglycin. Adherent decidual cell cultures were prepared from freshly isolated deciduae. Proteoglycan biosynthesis was investigated by labeling intact deciduae and decidual cultures with (35)S-sulfate. Serglycin mRNA was detected by in situ hybridization throughout the mesometrial portion and at the periphery of the antimesometrial portion of the decidua at Embryonic Day (E) 8.5, and in the parietal endoderm surrounding the embryo. Serglycin mRNA was detected in fetal liver at E11.5-E14.5. Serglycin was detected by immunohistochemistry in decidua and parietal endoderm at E8.5 and in liver at E13.5. Most of the proteoglycans synthesized by cultured intact deciduae (78%) and adherent decidual cultures (91%) were secreted into the medium. Serglycin proteoglycan may play an important role in uterine decidual function during early postimplantation development.

Trophoblast giant-cell differentiation involves changes in cytoskeleton and cell motility

Trophoblast giant-cell differentiation is well-characterized at the molecular level, yet very little is known about how molecular changes affect the cellular functions of trophoblast in embryo implantation. We have found, using both explanted E7.5 mouse embryo ectoplacental cone and the rat choriocarcinoma (Rcho-1) cell line, that trophoblast differentiation is distinguished by dramatic changes in cytoarchitecture and cell behavior. Undifferentiated trophoblast cells contain little organized actin and few small, peripheral focal complexes and exhibit high membrane protrusive activity, while differentiated trophoblast giant cells contain prominent stress fibers, large internal as well as peripheral focal adhesions, and become immotile. The dramatic changes in cell behavior and cytoskeletal organization of giant cells correlate with changes in the activities of the Rho family of small GTPases and a decrease in tyrosine phosphorylation of focal adhesion kinase. Together, these data provide detailed insight into the cellular properties of trophoblast giant cells and suggest that giant-cell differentiation is characterized by a transition from a motile to a specialized epithelial phenotype. Furthermore, our data support a phagocytic erosion, rather than a migratory infiltration, mechanism for trophoblast giant-cell invasion of the uterine stroma.

Progesterone exposure prevents matrix metalloproteinase-3 (MMP-3) stimulation by interleukin-1alpha in human endometrial stromal cells

Suppression of endometrial matrix metalloproteinases (MMPs) is necessary to maintain tissue stability during the invasive events of implantation and placental development. Several laboratories have shown that inflammatory cytokines, including interleukin-lalpha (IL-1alpha), can oppose progesterone suppression of MMPs in the human endometrium. Furthermore, we have recently demonstrated colocalization of epithelial cell IL-1alpha and MMP-7 expression at sites of ectopic pregnancy. The current study extends these findings, revealing a previously unrecognized interrelationship between progesterone and IL-1alpha in regulation of MMP-3. Although IL-1alpha is a potent stimulator of MMP-3 in proliferative phase endometrium in organ culture, we demonstrate that progesterone exposure in vivo reduces IL-1alpha stimulation of MMP-3 in secretory phase tissue. This loss of sensitivity to IL-1alpha was duplicated in isolated stromal cells treated with progesterone in vitro, and IL-1alpha stimulation of MMP-3 returned in a dose-dependent manner with progesterone withdrawal. The antiprogestin, onapristone, partially blocked the ability of progesterone to prevent stimulation of MMP-3 by IL-1alpha. These data suggest a novel mechanism by which progesterone may preserve tissue integrity during the establishment and maintenance of pregnancy by limiting stimulation of MMPs by inflammatory cytokines such as IL-1a.

Resistance of young gelatinase B-deficient mice to experimental autoimmune encephalomyelitis and necrotizing tail lesions

Regulated expression of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) plays a role in various physiological processes. To determine in vivo how unbalanced expression of these factors can promote or affect the course of pathologies, we knocked out the mouse gelatinase B gene by replacing the catalytic and zinc-binding domains with an antisense-oriented neomycin resistance gene. Adult gelatinase B-deficient mice and wild-type controls could be induced to develop experimental autoimmune encephalomyelitis (EAE) with similar scores for neurologic disease, blood-brain barrier permeability, and central nervous system histopathology. However, whereas diseased control animals showed necrotizing tail lesions with hyperplasia of osteocartilaginous tissue, adult gelatinase B-deficient mice were resistant to this tail pathology. Gelatinase B-deficient mice younger than 4 weeks of age were significantly less susceptible to the development of EAE than were age matched controls and, even as they aged, they remained resistant to tail lesions. These data illustrate that gelatinase B expression plays a role in the development of the immune system and that, in ontogenesis, the propensity to develop autoimmunity is altered by the absence of this MMP.

Cytokines in implantation

Implantation is a complex process which involves the 'invasion' of the maternal endometrium by the trophoblast surrounding the developing blastocyst. In response to this interaction there is a cellular reaction within the endometrium which has some features analogous to invasion by a tumour and some which are more characteristic of an inflammatory response. In addition, and also in common with cancer and inflammation, there is a release of biologically active molecules, including cytokines, at and around the implantation site. The information on cytokines is complex and often contradictory but it is recognised that they play an important role in the successful establishment of pregnancy. The evidence for this role is examined in this review.