Role of prostaglandins in pregnancy-induced hypertension

Efficacy of prompt administration of cryoprecipitate in severe postpartum hemorrhage of preeclampsia patients

AIM

Cryoprecipitate (CRYO) is a concentrated preparation of coagulation factors formulated from fresh frozen plasma (FFP), which can replenish coagulation factors rapidly. Preeclampsia (PE) is frequently associated with postpartum hemorrhage (PPH), and the rapid replenishment of coagulation factors is vital in the management. We conducted a retrospective cohort study to determine the efficacy of administering CRYO irrespective of fibrinogen levels in patients with PE who experienced severe PPH.

METHODS

Patients with PPH accompanied by PE and those who required red blood cell (RBC) transfusion were included. Cases were divided into two groups: those treated with CRYO (N = 16) and those not treated with CRYO (N = 10). The total transfusion volume, blood loss before and after transfusion initiation, duration of hospitalization, presence of pulmonary edema, and performance of either interventional radiology or hysterectomy were compared.

RESULTS

The median fibrinogen levels before transfusion were 2.24 and 2.34 g/L in the CRYO group and the not using group, respectively. Although blood loss before transfusion was comparable between the two groups, blood loss after transfusion was significantly less in the CRYO group (median: 520 vs. 2352 mL, p = 0.015), as well as the total blood loss (median: 2285 vs. 3825 mL, p = 0.005) and total transfusion volume (median: RBC 6 vs. 16 U, p = 0.01, FFP 10 vs. 20 U, p = 0.017).

CONCLUSION

Prompt replenishment of coagulation factors using CRYO to patients with PE who experience severe PPH could decrease further bleeding.

Assessment of the value of measuring soluble fms-like tyrosine kinase-1 and placental growth factor levels following administration of tadalafil to treat fetal growth restriction

PURPOSE

The aim of this study was to measure the blood levels of soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF) before and after tadalafil treatment in patients with fetal growth restriction.

MATERIALS AND METHODS

Maternal blood was collected from 13 women before and 2 weeks after tadalafil administration in the TADAFER II trial. The tadalafil treatment was conducted in addition to the conventional FGR treatment. As a control, maternal blood was also collected from 11 women before and 2 weeks after conventional treatment for fetal growth restriction. Blood sFlt-1 and PlGF were measured and the sFlt-1/PlGF ratio was calculated. Student's t-test was used to statistically analyze differences in the sFlt-1 and PlGF levels, and in the sFlt-1/PlGF ratios.

RESULTS

In both treatment groups, the levels of sFlt-1 and PlGF before and after treatment were not significantly different from each other. The sFlt-1/PlGF ratio was 2.0 ± 1.0 before and 17.6 ± 11.3 after treatment in the control group (p=.04). The sFlt-1/PlGF ratio was 2.2 ± 1.1 before and 22.2 ± 10.6 after tadalafil treatment in the tadalafil group (p=.06). The sFlt-1/PlGF ratios before and after tadalafil treatment were significantly increased in the control group. In both treatment groups, the sFlt-1/PlGF ratios before and after treatment were less than 38.

CONCLUSIONS

We conclude that the levels of sFlt-1 and PlGF were not significantly different as a result of tadalafil treatment. Further studies are needed to understand the mechanism of action of tadalafil in the treatment of fetal growth restriction.

Examination of the expression of cyclooxygenase-2 in placenta villi from sufferers of pregnancy induced hypertension

OBJECTIVES

The purpose of this paper is to elucidate the roles of phospholipase A(2) (PLA(2)), cyclooxygenase-2 (COX-2), and prostaglandin I(2) (PGI(2)) synthase in pregnancy induced hypertension (PIH).

METHODS

In placentas from normal pregnant women and pregnant women with severe PIH, the enzyme expression of PLA(2), COX-2, and PGI(2) synthase was measured using real time reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

The expression of each enzyme was compared between normal (n=12) and PIH (n=12) groups. The expression levels of COX-2 and PGI(2) synthase during PIH pregnancy were significantly decreased to about 51% and 68%, respectively, of their values in normal pregnancy. However, the expression of PLA(2) was hardly changed by PIH.

CONCLUSIONS

The decreases in COX-2 and PGI(2) synthase expression in severe PIH placentas may be causal factors in the disruption of the PGI(2)-thromboxane A(2) (TXA(2)) balance in favor of TXA(2). The decrease in COX-2 was more marked than that of PGI(2) synthase.

Effect of endothelin-1 on intracellular glutathione and lipid peroxide availability and on the secretion of vasoactive substances by human umbilical vein endothelial cells

BACKGROUND

The major pathophysiologic changes observed in preeclampsia suggest that endothelial cell dysfunction plays an important role in this disorder. The pathway mediating endothelial cell layer dysfunction is unknown. The concentration of endothelin-1 (ET-1), a potent mammalian vasoconstrictor peptide produced by the vascular endothelium, has been observed to be significantly increased in preeclampsia. In this study, we determined the in vitro effect of endothelin-1 on glutathione and lipid peroxide levels and on the secretion of vasoactive substances by human umbilical vein endothelial cells (HUVECs).

METHODS

Human umbilical vein endothelial cells were incubated for 24 h in the presence of different concentrations of ET-1 (0-1000 pmol L(-1)), which were shown in an earlier experiment to have no effects on vitality and proliferation rate of HUVECs. The levels of glutathione (GSH) and lipid peroxides (LPO) were measured in endothelial cell lysates. For the measurement of vasoactive substances, levels of nitric oxide (NO), prostacyclin (PGI2) and thromboxane A2 (TXA2) were measured in endothelial cell supernatants.

RESULTS

At lower concentrations (5-50 pmol L(-1)), ET-1 increases the intracellular content of LPO, stimulates the secretion of TXA2, but inhibits the secretion of PGI2 in endothelial cells compared with control cells. At higher concentrations (100-1000 pmol L(-1)), ET-1 increases the intracellular content of GSH, but results in a decrease of LPO, and increase of PGI2, back to control levels. ET-1 has no effect on NO secretion.

CONCLUSION

These findings demonstrate that at concentrations corresponding to values in plasma from preeclamptic women, ET-1 induces oxidative stress and results in altered secretion of vasoactive substances in human endothelial cells. We conclude that ET-1 may participate in the pathway leading to endothelial cell dysfunction seen in preeclampsia.

Prostaglandin H synthase and vascular function

Prostaglandin H synthase (PGHS) is a rate-limiting enzyme in the production of prostaglandins and thromboxane, which are important regulators of vascular function. Under normal physiological conditions, PGHS-dependent vasodilators (such as prostacyclin) modulate vascular tone. However, PGHS-dependent vasoconstriction (mediated by thromboxane and/or its immediate precursor, PGH(2)) predominates in some vascular pathologies (eg, systemic hypertension, diabetes, cerebral ischemia, and aging). This review will discuss the role of PGHS-dependent modulation of vascular function in a number of vascular beds (systemic, pulmonary, cerebral, and uterine) with an emphasis on vascular pathophysiology. Moreover, the specific contributions of the different isoforms (PGHS-1 and PGHS-2) are discussed. Understanding the role of PGHS in vascular function is of particular importance because they are the targets of the commonly used nonsteroidal antiinflammatory drugs (NSAIDs), which include aspirin and ibuprofen. Importantly, with the advent of specific PGHS-2 inhibitors for treatment of conditions such as chronic inflammatory disease, it is an opportune time to review the data regarding PGHS-dependent modulation of vascular function.

Trial of prophylactic administration of TXA2 synthetase inhibitor, ozagrel hydrochloride, for preeclampsia

OBJECTIVE

In an attempt to investigate the prophylactic effect of a thromboxane A2 (TXA2) synthetase inhibitor on pregnant women with a high risk of preeclampsia, the following clinical study was undertaken.

METHODS

Forty pregnant women were randomly allocated to control or treatment groups. Ozagrel Hydrochloride (400 mg/day, orally) and placebo were started at 20 weeks of gestation and continued until delivery.

RESULTS

Seventeen of 20 (85%) women in the control group developed preeclampsia, whereas 9 of 20 (45%) in the treatment group developed preeclampsia. Ozagrel Hydrochloride significantly (p < 0.01) reduced the occurrence of preeclampsia, and the incidence of both hypertension (p < 0.05) and proteinuria (p < 0.01) was significantly less in the treatment group compared with the control group. One month after administration, the mean plasma concentration of TXB2, a metabolite of TXA2, was significantly decreased (p < 0.01) to 62.4 +/- 13.6%, whereas that of 6-keto prostaglandin F1 alpha, a metabolite of PGI2, was significantly increased (p < 0.01) to 206.7 +/- 52.8%. There were no maternal or fetal side effects observed.

CONCLUSIONS

It seems likely that Ozagrel Hydrochloride could be used for the prevention of preeclampsia in high-risk pregnant women.

The possibility of clinical application of the thromboxane A2 synthase inhibitor, ozagrel, for the treatment and prevention of preeclampsia: a preliminary report

OBJECTIVES

This study was performed to investigate whether the TXA2 synthase inhibitor, ozagrel, was effective in the treatment and prevention of pre-eclampsia.

STUDY DESIGN

Ozagrel was administrated therapeutically to 4 severely pre-eclamptic women, and prophylactically to 5 pregnant women with histories of severe preeclampsia and complications.

RESULTS

The therapeutic administration (TA) of ozagrel improved hypertension and proteinuria. Two patients delivered appropriate-for-date (AFD) infants, whereas the other 2 patients delivered light-for-date (LFD) infants. Mean plasma concentrations of TXB2 (plasma TXB2) decreased, whereas plasma 6-keto PGF1 alpha were almost unchanged. The prophylactic administration (PA) of ozagrel prevented the occurrence of preeclampsia in 3 of the 5 patients. All delivered AFD infants. The duration of pregnancy was prolonged more than that of previous pregnancies in all patients. Plasma TXB2 decreased, whereas plasma 6-keto PGF1 alpha increased.

CONCLUSIONS

PA prevented preeclampsia and intrauterine growth retardation, whereas TA improved only maternal symptoms. These results might justify a large prospective study to determine whether ozagrel is an effective prophylactic.

Pre-eclampsia: excessive activation of a G protein-associated receptor?

Although the systemic physiological alterations present in pre-eclampsia appear disparate and unrelated, four of them (endothelial cell hyperplasia and alterations in uric acid, calcium, and prostaglandin homeostasis) are demonstrated here to mimic closely the pattern of intracellular alterations caused by the activation of a G protein-associated receptor. The implication of this is that the excessive activation of a particular G protein-associated receptor may play a central role in the pathogenesis of pre-eclampsia.

Production of prostacyclin and thromboxane A2 in mononuclear cells from preeclamptic women

OBJECTIVE

Although the changes in prostacyclin and thromboxane A2 levels in preeclampsia have been well studied, little work has previously been done on mononuclear cells, and the cause of the changes in unclear. We determined the prostacyclin and thromboxane A2 production in mononuclear cells and investigated the effect of preeclamptic serum on this production.

STUDY DESIGN

The production of prostacyclin and thromboxane A2 was measured by enzyme immunoassay in 16 normal pregnant women, nine preeclamptic women with proteinuria, and six preeclamptic women without proteinuria. Sera from these three groups of women were investigated to see whether the sera have any effect on prostaglandin production.

RESULTS

The levels of thromboxane A2 in preeclamptic patients were found to be much higher than those of normal pregnancy, whereas the levels of prostacyclin tended to be lower. Such changes lead to a markedly increased ratio of thromboxane A2 to prostacyclin in preeclamptic patients. There was no difference in the levels of prostacyclin and thromboxane A2 between the preeclamptic patients with and without proteinuria. Serum from preeclamptic patients with proteinuria slightly reduced prostacyclin synthesis in normal pregnancy but significantly increased increased thromboxane A2 production, resulting in a ratio of thromboxane A2 to prostacyclin similar to that of preeclampsia. However, serum from preeclamptic patients without proteinuria failed to exert such effects.

CONCLUSION

The imbalance between prostacyclin and thromboxane A2 occurs in mononuclear cells from preeclamptic women, and there is a factor(s) in proteinuric-preeclamptic serum to contribute, in part, to these changes. Our findings also suggested that the cause of abnormal prostaglandin production in preeclampsia was complicated and multifactorial.