Differential expression of thioredoxin binding protein-2/Txnip in human placenta: Possible involvement of hypoxia in its suppression during early pregnancy

AIM

Thioredoxin binding protein-2 (TBP-2), which is identical to thioredoxin interacting protein (Txnip), controls cellular proliferation and differentiation. The aim of the present study was to compare TBP-2 protein and mRNA expression in human placenta during the three trimesters of pregnancy and to investigate the role of hypoxia in the change of these expressions in placental tissue. A secondary objective was to determine the gene expression of peroxisome proliferator-activated receptors (PPARs) in TBP-2 deficient placenta using TBP-2 gene disrupted mice (TBP-2^-/- ).

METHODS

Protein and mRNA expression of TBP-2 in human placenta from each trimester were analyzed by immunohistochemistry, Western blots, and by quantitative reverse-transcriptase-polymerase chain reaction. The effect of hypoxia on TBP-2 expression was tested using an explant culture of human placenta. In TBP-2^-/- mouse placenta, we detected PPAR mRNA expression.

RESULTS

TBP-2 was located in syncytiotrophoblasts and cytotrophoblasts, and also in the endothelium in human placenta. Its expression in the placenta was low in the first trimester, and increased in the second and third trimesters. Hypoxia decreased TBP-2 mRNA and protein expression in human placental explant culture. In TBP-2^-/- mice, placental mRNA levels of PPARα and γ were significantly suppressed compared with those in wild-type mice.

CONCLUSION

Hypoxia suppresses TBP-2 gene expression, which may ultimately alter placental development.

Nrf2 Activation Inhibits Effects of Thrombin in Human Amnion Cells and Thrombin-Induced Preterm Birth in Mice

CONTEXT

Nrf2 is a key transcription factor that modulates cell defense mechanisms against endogenous and exogenous stress. Previously, we reported that thrombin increased matrix metalloproteinases and prostaglandin synthesis in human amnion mesenchymal cells.

OBJECTIVE

We sought to determine whether activation of Nrf2 alters the effect of thrombin on prostaglandin synthesis, protease activation, and cytokine release in human amnion. Furthermore, we analyzed the effect of Nrf2 activation on thrombin-induced preterm labor in mice.

DESIGN

Primary human amnion mesenchymal cells and pregnant mice were employed to investigate the effect of Nrf2 on thrombin-induced inflammation and preterm birth.

SETTING

This was a laboratory-based study using cells and mice.

RESULTS

As expected, thrombin increased cyclooxygenase-2, IL-1β, IL-6, IL-8, and matrix metalloproteinase-1 in amnion mesenchymal cells. Preincubation with Nrf2 activators, diethyl maleate or 15-deoxy-Δ12, 14-prostaglandin J2 (15d-PGJ2), profoundly repressed thrombin-induced gene expression. In addition, Nrf2 activation inhibited thrombin-induced cyclooxygenase-2 protein levels and secretion of prostaglandin E2, IL-1β, IL-6, IL-8, TNFα, and granulocyte-macrophage colony-stimulating factor in the media. Whereas vehicle and 15d-PGJ2 did not alter gestational length, all pregnant mice treated with thrombin delivered preterm. 15d-PGJ2 delayed thrombin-induced preterm birth significantly.

CONCLUSIONS

The results indicate that Nrf2 activation represents a key stress response in amnion mesenchyme cells and in pregnant mice to mitigate the adverse proinflammatory effects of thrombin on the fetal membranes. We suggest, therefore, that pharmacological activation of Nrf2 may prevent the increased risk of preterm premature rupture of the membranes associated with thrombin activation that accompanies subchorionic hemorrhage or bleeding during pregnancy.

Magnesium sulphate can prolong pregnancy in patients with severe early-onset preeclampsia

OBJECTIVE

To assess whether long-term use of magnesium sulphate prolongs pregnancy in patients with severe early-onset preeclampsia.

METHODS

Retrospective cohort study included all singleton pregnancies with severe early-onset preeclampsia, expectantly managed in our institution between 2005 and 2013. Obstetric and perinatal outcomes were compared between patients managed using a current protocol that tolerates long-term (over 48 h) use of magnesium sulphate (long-term group, n = 26) and a historical control group (control group, n = 15) that underwent conventional treatment (up to 48 h use of magnesium sulphate).

RESULTS

Long-term group showed significant prolongation of pregnancy compared with the control group (9.2 ± 7.9 versus 16.6 ± 9.3 d, log-rank test, p = 0.021), which was also observed in patients with severe preeclampsia occurring before 28 weeks' gestation (n = 11, 4.5 ± 5.2 versus 13.2 ± 6.8 d, log-rank test, p = 0.035). In contrast to a progressive decrease of platelet count in patients managed without magnesium sulphate, administration of magnesium sulphate for 7 d prevented the decrease of platelet count (p = 0.001). Thirty two percent of patients (13/41) experienced a major complication irrespective of duration of magnesium sulphate use.

CONCLUSIONS

Long-term use of magnesium sulphate prolonged pregnancy in patients with severe early-onset preeclampsia and can help alleviate progression of preeclampsia.

Placental function assessed visually using half-Fourier acquisition single-shot turbo spin-echo (HASTE) magnetic resonance imaging

INTRODUCTION

To investigate a simple visual assessment method of placental function using half-Fourier acquisition single-shot turbo spin-echo (HASTE) magnetic resonance imaging (MRI).

METHODS

The institutional review board approved this retrospective study of fetal MRI in 48 singleton pregnant women for whom placentas had undergone clinical pathological examinations. Two readers independently assessed the placentas using the HASTE scoring system, particularly emphasizing the visualization of the regular two-tone pattern inside and signal intensity (SI) of placental parenchyma referring to SI of the fetal kidney and liver. After categorization using the HASTE scoring system, the associations between the scores and the presence of pathologically proven placental insufficiency or of low birth weight less than the tenth percentile were examined using chi-square tests. The associations between the HASTE scores and the MRI findings previously reported to suggest placental insufficiency, such as placental thickness and placenta to amniotic fluid SI ratio, were also examined using Student t-tests.

RESULTS

The HASTE scores were associated significantly with the presence of pathologically proven placental insufficiency (P = .003 for reader 1; P = .04 reader 2) and birth weight less than the tenth percentile (P = .005 for reader 1; P = .003 for reader 2). The HASTE scores were associated significantly with the placenta thickness (P < .0001 for both readers) and the placenta to the amniotic fluid SI ratio (P < .0001 for both readers).

DISCUSSION

The HASTE scoring system is feasible for use in clinical assessment of placental function and for diagnosing placental insufficiency.

Case of soluble fms-like tyrosine kinase 1 apheresis in severe pre-eclampsia developed at 15 weeks' gestation

Soluble fms-like tyrosine kinase-1 (sFlt1), a circulating vascular endothelial growth factor receptor 1 antagonist, is associated with the pathogenesis of pre-eclampsia. Extracorporeal removal of sFlt1 (sFlt1 apheresis) is emerging as a treatment for pre-eclampsia. We performed sFlt1 apheresis for a patient with very early onset pre-eclampsia, beginning at 15 weeks' gestation. She underwent sFlt1 apheresis 13 times from 19 to 23 weeks' gestation. The series of treatments lowered circulating sFlt1, stabilized blood pressure, reduced urinary protein, and preserved renal function, which contributed to a successful prolongation of pregnancy for 4 weeks and a live birth at 23(+3) weeks' gestation. Further studies are necessary for clinical application of sFlt1 apheresis as sFlt1 might have a protective function for the placenta and fetus in pre-eclampsia.

Visualization of placental hypocirculation with typical patterns using conventional magnetic resonance imaging: Two case reports

We report two cases of clinically suspected placental hypocirculation, as per evidenced by specific half-Fourier acquisition single-shot turbo spin-echo (HASTE) magnetic resonance findings of the whole placenta. Patient 1 was a case of fetal growth restriction caused by pregnancy-induced hypertension, while patient 2 experienced a discordant dichorionic diamniotic twin pregnancy with fetal growth restriction complication with a velamentous insertion of the umbilical cord in the smaller twin. In both cases, HASTE images showed noticeably decreased signal intensity with high-intensity signal spots present in the central region of the placenta. In the twin pregnancy case, the low-intensity signal area in the placenta of the smaller twin was much lower compared to that of the larger twin. Pathological findings failed to support or explain these observations. HASTE images might reflect compensatory alternation of the distribution of maternal blood and villus caused by hypocirculation. In conclusion, our results suggest that HASTE imaging might be a useful approach for the visualization of placental hypocirculation.

Reliable pre-eclampsia pathways based on multiple independent microarray data sets

Pre-eclampsia is a multifactorial disorder characterized by heterogeneous clinical manifestations. Gene expression profiling of preeclamptic placenta have provided different and even opposite results, partly due to data compromised by various experimental artefacts. Here we aimed to identify reliable pre-eclampsia-specific pathways using multiple independent microarray data sets. Gene expression data of control and preeclamptic placentas were obtained from Gene Expression Omnibus. Single-sample gene-set enrichment analysis was performed to generate gene-set activation scores of 9707 pathways obtained from the Molecular Signatures Database. Candidate pathways were identified by t-test-based screening using data sets, GSE10588, GSE14722 and GSE25906. Additionally, recursive feature elimination was applied to arrive at a further reduced set of pathways. To assess the validity of the pre-eclampsia pathways, a statistically-validated protocol was executed using five data sets including two independent other validation data sets, GSE30186, GSE44711. Quantitative real-time PCR was performed for genes in a panel of potential pre-eclampsia pathways using placentas of 20 women with normal or severe preeclamptic singleton pregnancies (n = 10, respectively). A panel of ten pathways were found to discriminate women with pre-eclampsia from controls with high accuracy. Among these were pathways not previously associated with pre-eclampsia, such as the GABA receptor pathway, as well as pathways that have already been linked to pre-eclampsia, such as the glutathione and CDKN1C pathways. mRNA expression of GABRA3 (GABA receptor pathway), GCLC and GCLM (glutathione metabolic pathway), and CDKN1C was significantly reduced in the preeclamptic placentas. In conclusion, ten accurate and reliable pre-eclampsia pathways were identified based on multiple independent microarray data sets. A pathway-based classification may be a worthwhile approach to elucidate the pathogenesis of pre-eclampsia.

Endothelial function progressively deteriorates during normal pregnancy

OBJECTIVE

To elucidate changes in endothelial function throughout the gestational period in normal pregnancy and its relationship with plasma soluble fms-like tyrosine kinase-1 (sFlt-1) levels.

METHODS

Endothelial function was evaluated by reactive hyperemia index (RHI) using Endo-PAT2000 and plasma sFlt-1 levels were measured simultaneously by ELISA.

RESULTS

RHI gradually deteriorated with increasing gestational age. Plasma sFlt-1 levels exhibited a gradual increase at late pregnancy and were inversely correlated with RHI.

CONCLUSION

Maternal endothelial function gradually deteriorates with increasing gestational age and there is an inverse correlation between endothelial function and plasma sFlt-1 levels in normal pregnancy.