Uteroplacental vascular involvement in recurrent spontaneous abortion

Anticontractile Effect of Perivascular Adipose Tissue But Not of Endothelium Is Enhanced by Hydrogen Sulfide Stimulation in Hypertensive Pregnant Rat Aortae

Perivascular adipose tissue (PVAT) modulates the vascular tone. Hydrogen sulfide (H2S) is synthetized by cystathionine gamma-lyase (CSE) in brown PVAT. Modulation of vascular contractility by H2S is, in part, adenosine triphosphate (ATP)-sensitive potassium channels dependent. However, the role of PVAT-derived H2S in hypertensive pregnancy (HTN-Preg) is unclear. Therefore, we aimed to examine the involvement of H2S in the anticontractile effect of PVAT in aortae from normotensive and hypertensive pregnant rats. To this end, phenylephrine-induced contractions in the presence and absence of PVAT and endothelium in aortae from normotensive pregnant (Norm-Preg) and HTN-Preg rats were investigated. Maternal blood pressure, fetal-placental parameters, angiogenesis-related biomarkers, and H2S levels were also assessed. We found that circulating H2S is elevated in hypertensive pregnancy associated with angiogenic imbalance, fetal and placental growth restrictions, which revealed that there is H2S pathway activation. Moreover, under stimulated H2S formation PVAT, but not endothelium, reduced phenylephrine-induced contractions in aortae from HTN-Preg rats. Also, H2S synthesis inhibitor abolished anticontractile effects of PVAT and endothelium. Furthermore, anticontractile effect of PVAT, but not of endothelium, was eliminated by ATP-sensitive potassium channels blocker. In accordance, increases in H2S levels in PVAT and placenta, but not in aortae without PVAT, were also observed. In conclusion, anticontractile effect of PVAT is lost, at least in part, in HTN-Preg aortae and PVAT effect is ATP-sensitive potassium channels dependent in normotensive and hypertensive pregnant rat aortae. PVAT but not endothelium is responsive to the H2S stimulation in hypertensive pregnant rat aortae, implying a key role for PVAT-derived H2S under endothelial dysfunction.

The DSCs-expressed CD82 controls the invasiveness of trophoblast cells via integrinbeta1/MAPK/MAPK3/1 signaling pathway in human first-trimester pregnancy

CD82 is recognized as a wide-spectrum tumor metastasis suppressor that inhibits cancer cell motility and invasiveness. At the human maternal-fetal interface, the decidua is believed to effectively limit the inappropriate invasion of trophoblasts. Here we have found the transcription and translation of CD82 in decidual stromal cells (DSCs), whereas trophoblast cells do not express CD82. The in-cell Western analysis reveals attenuation of CD82 translation in DSCs by human chorionic gonadotropin (hCG), but not by estrogen or progesterone. It is demonstrated that silencing of CD82 by RNA interference increases integrinbeta1, decreases TIMP1 expression in DSCs, and promotes the invasion of the first-trimester human trophoblasts in the coculture. Moreover, U0126, or anti-integrinbeta1 neutralizing antibody, reverses the decreased TIMP1 expression and the increased invasiveness of trophoblast cells, and the antibody also inhibits the MAPK3/1 phosphorylation induced by CD82 silence. After transfection with CD82, the invasive index of BeWo cells decreases significantly with TIMP1 increase. The results above indicate that the DSCs-expressed CD82 up-regulates the expression of TIMP1 in an autocrine manner and inhibits the invasiveness of human first-trimester trophoblast cells partly through the integrinbeta1/MAPK/MAPK3/1 signaling pathway. Furthermore, we have found that the mRNA and protein level of CD82 in decidua of the miscarriage is significantly higher than that of the normal early pregnancy, which implies that the abnormal higher CD82 expression in decidua restricts appropriate invasion of trophoblasts that leads to early pregnancy wastage.

Determinants of Placental Vascularity

PROBLEM

Vascular growth during implantation and placentation is critical for successful gestation and it is thought that vascular insufficiencies during placentation contribute to a number of obstetrical complications. However, relatively little is known regarding the regulation of angiogenesis in the placenta.

METHOD OF STUDY

We review literature concerning the potential significance of inadequate placental vascularity as a contributor to the obstetrical complications of spontaneous abortion, fetal growth restriction and preeclampsia. Gene expression assays were used to compare fluctuations of placenta growth factor (PlGF) and PlGF receptor expression in normal and preeclamptic trophoblast in vitro.

RESULTS

Studies have shown that common obstetrical complications manifest altered placental vascularity. Both intrinsic defects (gene knockouts) and extrinsic factors (O(2) tension, cytokines, etc) may be responsible for the defects. Some of these factors have been shown to influence trophoblast vascular endothelial growth factor (VEGF)/PlGF expression suggesting this particular family of angiogenic proteins play an important role in placental angiogenesis.

CONCLUSION

Placental vascularization reflects a complex interaction of regulatory factors. Understanding the regulation of vascular growth in the placenta will provide much needed insight into placenta-related vascular insufficiencies.

Recurrent pregnancy loss: an update

This review highlights recent studies that investigate causes and treatments for recurrent pregnancy loss. Generally the causes of recurrent pregnancy loss are classified as genetic, endocrinologic, anatomic, immunologic, microbiologic, and environmental. The majority of recent work has focused on potential autoimmune and alloimmune causes; however, controversy still exists over appropriate testing and treatment. Reports have investigated the potential associations between autoimmune factors (antithyroid antibodies and antiphospholipid antibodies) and alloimmune factors (natural killer cells, cytotoxic T cells, and embryotoxic factors) and recurrent pregnancy loss. Increasingly, clinical reports are suggesting intravenous immunoglobulin as a potential treatment for these immunologic problems. Several lines of investigation have suggested certain hypercoagulable states as causative of recurrent pregnancy loss. New studies relating recurrent pregnancy loss to endocrinologic aberrations (hyperprolactinemia and hyperandrogenism) as well as social/environmental factors (stress, caffeine use, tobacco use, human immunodeficiency virus, and history of induced abortion) have been made. A summary of proposed evaluation and treatment options is presented.

Polymorphism for mutation of cytosine to thymine at location 677 in the methylenetetrahydrofolate reductase gene is associated with recurrent early fetal loss

OBJECTIVE

This study was undertaken to determine whether a cytosine to thymine mutation at nucleotide 677 in the gene encoding for methylenetetrahydrofolate reductase is associated with particular subtypes of recurrent unexplained spontaneous abortion.

STUDY DESIGN

The prevalences of cytosine to thymine mutation at nucleotide 677 in the gene encoding for methylenetetrahydrofolate reductase among 41 patients with recurrent unexplained spontaneous abortions and among 18 healthy control subjects were determined with polymerase chain reaction.

RESULTS

Homozygosity and heterozygosity for the cytosine to thymine mutation at nucleotide 677 in the gene encoding for methylenetetrahydrofolate reductase were observed at nonsignificantly different rates among patients and control subjects (9% and 48% versus 22% and 38%, respectively, P <.95). Among patients with recurrent unexplained spontaneous abortions both homozygosity and heterozygosity were associated with significantly increased prevalence of recurrent early fetal loss rather than with repeated anembryonic gestations (P <.0001).

CONCLUSION

The observation that polymorphism for the cytosine to thymine mutation at nucleotide 677 in the gene encoding for methylenetetrahydrofolate reductase is associated with repeated early fetal losses rather than with anembryonic gestations strengthens the argument for the role of hypercoagulability and abnormal uteroplacental vasculature in recurrent spontaneous abortion.

Placenta growth factor: potential role in pregnancy

PROBLEM

In spite of the known requirement for adequate vascularity during placentation, little is known regarding the regulation of angiogenic growth factor production by trophoblast. Placenta growth factor (PIGF) is a recently discovered angiogenic growth factor whose expression is relatively limited to trophoblast.

METHOD OF STUDY

Current literature of PIGF was reviewed, with emphasis on its expression, regulation, role in angiogenesis, and potential function(s) at the maternal-fetal interface.

RESULTS

PIGF is abundantly expressed by trophoblast, which implies that it could act in a paracrine manner to modulate vascular development, stability, and/or function within the decidua and placental villi. In addition, expression of the PIGF receptor, fms-like tyrosine kinase (flt-1) receptor, on trophoblast raises the potential for an autocrine role of PIGF in regulating trophoblast growth and/or function.

CONCLUSIONS

The potential for PIGF to influence both vascular endothelial cells and trophoblast suggests that aberrant trophoblast production of PIGF could compromise cellular function during gestation and contribute to the vascular and placental pathologies noted in many obstetric complications.