Preeclampsia: an imbalance in placental prostacyclin and thromboxane production

Preeclampsia is characterized by increased vasoconstriction frequently associated with increased platelet aggregation, reduced uteroplacental blood flow, and premature delivery. Because prostacyclin antagonizes the vasoconstrictor, platelet-aggregating, and uterine-activating actions of thromboxane, we considered the hypothesis that placental production of thromboxane was increased coincident with decreased production of prostacyclin in preeclampsia. Fresh human term placentas were obtained immediately after delivery from 11 normal and 10 preeclamptic pregnancies (blood pressure greater than or equal to 140/90 mm Hg, urinary protein greater than 0.3 gm/24 hr). Tissues (350 mg) were incubated sterilely in 6 ml of Dulbecco's Modified Eagle's Medium for 48 hours at 37 degrees C with 95% oxygen and 5% carbon dioxide in a metabolic shaker. Samples were collected at 8, 20, 32, and 48 hours and analyzed for thromboxane by radioimmunoassay of its stable metabolite, thromboxane B2, and for prostacyclin by radioimmunoassay of its stable metabolite, 6-keto prostaglandin F1 alpha. The production of thromboxane was significantly increased in preeclamptic versus normal placental tissue (22.9 +/- 4.7 versus 6.3 +/- 1.5 pg/mg/hr, mean +/- SE, p less than 0.01), whereas the production of prostacyclin was significantly decreased (3.0 +/- 0.3 versus 6.7 +/- 0.5 pg/mg/hr, p less than 0.001). In both normal and preeclamptic placentas, the production rates of thromboxane and prostacyclin were inhibited by indomethacin (5 mumol/L) and not affected (p greater than 0.50) by arachidonic acid (100 mumol/L). Therefore, during normal pregnancy, the placenta produces equivalent amounts of thromboxane and prostacyclin, so that their biologic actions on vascular tone, platelet aggregation, and uterine activity will be balanced. In preeclamptic pregnancy, however, the placenta produces seven times more thromboxane than prostacyclin.     

Plasma from preeclamptic women stimulates decidual endothelial cell growth and prostacyclin but not nitric oxide production: close correlation of prostacyclin and thromboxane production

OBJECTIVE: To examine the effect of plasma from preeclamptic women on production of the vasoactive substances prostacyclin, thromboxane, nitric oxide, and cyclic guanosine monophosphate (cGMP) by decidual endothelial cells; to determine any effects on cell growth and health; and to examine whether cells from preeclamptic women are activated compared with cells from normal women. METHODS: Decidual endothelial cells from normal and preeclamptic women were incubated for 24 hours in media containing 10% plasma from preeclamptic women or matched normal women. Prostacyclin and thromboxane production was measured, as was nitric oxide and cGMP production after a further 45-minute generation period in 2% test plasma. Cell numbers and lactate dehydrogenase release were also determined. RESULTS: In plasma from preeclamptic women, cells grew significantly faster (P <.05), prostacyclin production was increased (P <.05), and lactate dehydrogenase release was reduced (P <.01). Production of thromboxane, nitric oxide, and cGMP was not significantly affected. Decidual endothelial cells from preeclamptic women had increased growth (P <.0001) and produced more prostacyclin (P <.05) and nitric oxide (P <.001) than normal decidual endothelial cells. There were highly significant correlations between prostacyclin and thromboxane production for incubations in plasmas from preeclamptic women and between background levels of prostacyclin in each plasma from preeclamptic women and the prostacyclin produced in incubations containing that plasma (P <.0001). CONCLUSION: We found that plasma from preeclamptic women contained a factor that stimulated endothelial cell growth and regulated production of related amounts of prostacyclin and thromboxane. The plasma level of this factor appeared to be related to background levels of prostacyclin. The results also indicated that decidual endothelial cells from preeclamptic women were in a relatively activated state.     

ADAM17 regulates TNFα production by placental trophoblasts

Increased trophoblast TNFα production is an important component of placental dysfunction in preeclampsia. However, the mechanism of increased TNFα production in the preeclamptic placenta is largely unknown. ADAM17 is a metallopeptidase that functions as a TNFα converting enzyme. In this study, we examined ADAM17 expression in placentas from normal and preeclamptic pregnancies and found increased ADAM17 expression in preeclamptic placentas compared to those from normal placentas, p < 0.05. Since hypoxia/oxidative stress is an underlying pathophysiology in the preeclamptic placenta, we further determined if hypoxia/oxidative stress could modulate ADAM17 expression and subsequently induce TNFα production in placental trophoblasts. Trophoblasts were isolated from normal term placentas and treated with cobalt (II) chloride (CoCl₂), a hypoxia mimetic agent, at different concentrations. Our results showed that CoCl₂ induced a dose-dependent increase in TNFα production that is associated with enhanced ADAM17 expression. Trophoblast expressions of HO-1 (a sensor of cellular oxidative stress) and caspase-3 (an indicator of apoptosis) in response to CoCl₂ stimulation were also examined. We further found that metallopeptidase inhibitor GM6001 and ADAM17 siRNA could block CoCl₂ induced TNFα production, demonstrating the role of ADAM17 in TNFα production in placental trophoblasts. These results suggest that oxidative stress-induced increased ADAM17 expression could contribute to the increased TNFα production in preeclamptic placentas.     

Low-dose aspirin: treatment for the imbalance of increased thromboxane and decreased prostacyclin in preeclampsia

The discovery of the imbalance of increased thromboxane and decreased prostacyclin production in preeclamptic women has explained the cause of the major clinical symptoms of this disorder and has formed the basis and rationale for clinical studies with low-dose aspirin to treat preeclampsia. Low doses of aspirin (60 to 81 mg/day) have a remarkable ability to inhibit thromboxane production selectively without significantly inhibiting prostacyclin production. Therefore the actions of thromboxane to increase vasoconstriction, stimulate platelet aggregation, increase uterine contractility, and decrease uteroplacental blood flow are attenuated, and the ratio of thromboxane to prostacyclin is altered in favor of prostacyclin. Prostacyclin promotes vasodilation, inhibits platelet aggregation, decreases uterine contractility, and increases uteroplacental blood flow. The initial clinical studies with low doses of aspirin are very encouraging with respect to the treatment and prevention of preeclampsia. Substantial evidence already indicates that low-dose aspirin therapy decreases the incidence of preeclampsia; it decreases the maternal systemic arterial pressor response to angiotensin II; and it does not seem to be harmful to the fetus. Treatment of preeclampsia with prostacyclin appears to be contraindicated because prostacyclin is a potent systemic vasodilator and the clinical outcome of preeclamptic women infused with prostacyclin has been poor. The mechanism whereby low-dose aspirin preferentially inhibits thromboxane synthesis is not known.(ABSTRACT TRUNCATED AT 250 WORDS)     

Oxidative stress causes vascular dysfunction in the placenta

Increased production of superoxide and nitric oxide may produce oxidative stress in the placenta by formation of the prooxidant peroxynitrite, which itself causes vascular dysfunction. Nitrotyrosine residues, which are a marker of peroxynitrite formation and action, are found in placental vessels of preeclamptic and diabetic pregnancies, indicating oxidative stress. Treatment of the placental vasculature with authentic peroxynitrite in vitro attenuates responses both to vasoconstrictors such as the thromboxane mimetic U46619 and to vasodilators, including glyceryl trinitrate and prostacyclin, indicating it has caused vascular dysfunction. Further, the responses of the fetal–placental vasculature of diabetic and preeclamptic placentae to these same vasoconstrictor and vasodilator agents are significantly attenuated when compared to responses in normal control placentae. Together these data suggest there may be a cause and effect relationship between formation and action of peroxynitrite and vascular dysfunction in the placenta of both preeclamptic and diabetic pregnancies. The presence of such attenuated vascular responses indicates that perhaps the placenta may not be able to adequately respond to demands for altered blood flow in situations where this is necessary in preeclamptic or diabetic pregnancies, thus leading to further fetal compromise.     

Endocrinologic events in early pregnancy failure

Fourteen women experiencing early pregnancy failure have been studied during the time of conception and at frequent intervals until spontaneous abortion occurred. Serial measurements of serum estradiol, progesterone, 17α-hydroxyprogesterone, prolactin, human placental lactogen (hPL), and human chorionic gonadotropin (hCG) were determined; regular sonar scanning allowed the time of fetal death to be determined to within 7 days in six patients and a diagnosis of blighted ovum to be made in the remainder. In all patients serum progesterone and estradiol concentrations were within the normal range up to 7 weeks but appeared to decrease from about 8 weeks' gestation whether or not a living fetus was present. The placenta continued to produce hCG and hPL but, despite the continuing presence of hCG, the levels of 17α-hydroxyprogesterone declined to concentrations below those associated with normal pregnancy. These data suggest that the placenta may require a particular stimulus to take over production of progesterone and estradiol.     

Oxidative stress causes vascular dysfunction in the placenta

Increased production of superoxide and nitric oxide may produce oxidative stress in the placenta by formation of the prooxidant peroxynitrite, which itself causes vascular dysfunction. Nitrotyrosine residues, which are a marker of peroxynitrite formation and action, are found in placental vessels of preeclamptic and diabetic pregnancies, indicating oxidative stress. Treatment of the placental vasculature with authentic peroxynitrite in vitro attenuates responses both to vasoconstrictors such as the thromboxane mimetic U46619 and to vasodilators, including glyceryl trinitrate and prostacyclin, indicating it has caused vascular dysfunction. Further, the responses of the fetal-placental vasculature of diabetic and preeclamptic placentae to these same vasoconstrictor and vasodilator agents are significantly attenuated when compared to responses in normal control placentae. Together these data suggest there may be a cause and effect relationship between formation and action of peroxynitrite and vascular dysfunction in the placenta of both preeclamptic and diabetic pregnancies. The presence of such attenuated vascular responses indicates that perhaps the placenta may not be able to adequately respond to demands for altered blood flow in situations where this is necessary in preeclamptic or diabetic pregnancies, thus leading to further fetal compromise.     

Estrogens in intrahepatic cholestasis of pregnancy

OBJECTIVE: To determine whether estrogen production and excretion are impaired in gravidas with intrahepatic cholestasis. METHODS: Plasma and urine samples were collected from 13 women from the United States and Chile at 35-38 weeks' gestation with mild (n = 9) or severe (n = 4) intrahepatic cholestasis of pregnancy. Urinary and plasma steroid levels from women with cholestasis were compared with levels from 27 normal pregnant women within the same gestational age range. Urinary concentrations of dehydroepiandrosterone (DHEA), estrone (E1), estradiol (E2), estriol (E3), estetrol, progesterone, and 16-hydroxy-pregnenolone were measured by gas chromatography mass spectrometry, and plasma concentrations of DHEA sulfate, progesterone, unconjugated E1, unconjugated E2, unconjugated E3, sulfated E3 derivatives, glucuronidated E3 derivatives, and total E3 were measured by radioimmunoassay. RESULTS: Compared with normal pregnant women, women with cholestasis had significantly lower plasma levels of estrogens and DHEA sulfate, the precursor to placental estrogen production synthesized by the fetal adrenal gland (Hotelling-Lawley trace = 0.81; F4,19 = 3.9; P = .02). The mean plasma DHEA sulfate, unconjugated E2, unconjugated E3, and total E3 concentrations were 0.271, 10.21, 9.80, and 99.53 ng/mL, respectively, in women with cholestasis compared with 0.802, 18.98, 16.28, and 145.07 ng/mL for controls. CONCLUSION: Fetal adrenal production of DHEA sulfate, and in response, downstream placental production of estrogens, was compromised by intrahepatic cholestasis of pregnancy.     

Progesterone synthesis by the human placenta

One of the essential roles of the human placenta is to produce the steroid hormone progesterone, which is required for the maintenance of pregnancy. The rate-determining step of placental progesterone synthesis is the conversion of cholesterol to pregnenolone by cytochrome P450scc (CYP11A1) in placental mitochondria in a reaction requiring electrons delivered via adrenodoxin reductase and adrenodoxin. Pregnenolone is converted to progesterone by type 1 3beta-hydroxysteroid dehydrogenase located in the mitochondrion. Progesterone synthesis by the human placenta displays notable differences from steroid synthesis in the classical steroid producing tissues such as the adrenal cortex and corpus luteum. One important difference is that the placenta lacks short term modulation of steroid synthesis and does not express the steroidogenic acute regulatory (StAR) protein. The most notable difference between the placenta and other steroidogenic tissues is that electron supply to P450scc limits the rate at which cholesterol is converted to pregnenolone in the placenta. The limiting component for electron delivery to P450scc is the concentration of adrenodoxin reductase in the mitochondrial matrix which is insufficient to maintain the adrenodoxin pool in a fully reduced state. Evidence suggests that placental mitochondria have a near-saturating cholesterol concentration for P450scc, likely provided by the StAR-like protein MLN64, and cholesterol translocation to the P450scc is not a major site of regulation of progesterone synthesis. Cyclic AMP stimulates progesterone synthesis by the human placenta but uncertainty remains regarding the key hormones that control cyclic AMP levels. The mechanism of regulation of adrenodoxin reductase levels in the human placenta remains to be studied.     

Steroid modulation of pregnenolone to progesterone conversion by human placental cells in vitro

Studies were performed to examine the production of progesterone by human placental cells in vitro. Samples of placentas from 22 women at term after spontaneous onset of labor and vaginal delivery were utilized. The tissue was dispersed into isolated cells with the use of collagenase, and suspensions of these cells were incubated with pregnenolone as substrate in the presence or absence of other compounds which may regulate progesterone production. These cell preparations produced progesterone in a dose-related fashion with exogenous pregnenolone. The conversion of pregnenolone to progesterone occurred rapidly, with most of the conversion completed during the first hour of incubation. The conversion was inhibited by dehydroepiandrosterone, estrone, androstenedione, and testosterone (p less than 0.001 in all cases). The inhibitory effect of androstenedione and testosterone was not dependent on aromatization to estrogen. Dihydrotestosterone and 5 alpha-pregnanedione resulted in a significant increase in the amount of progesterone present (p less than 0.001). In preliminary experiments, gonadotropin-releasing hormone, salbutamol, and propranolol were without significant effect in this system. We conclude that this system is a useful model for studying progesterone production by human placental tissue, and that placental progesterone production may be significantly influenced by the presence of other steroid hormones.     

Serum from women with preeclampsia partially corrects the abnormal in vitro prostacyclin secretion of preeclamptic villous cytotrophoblasts but not that of prostaglandin E2 or endothelin-1

OBJECTIVE: This study was conducted (1) to determine in vitro placental villous cytotrophoblast secretion of prostacyclin, prostaglandin E₂, and endothelin-1, (2) to examine the effect of serum from normal and preeclamptic women on secretion of these vasoactive substances, and (3) to determine whether responses to these sera by cytotrophoblasts from preeclamptic pregnancies are different from those of normal pregnancies. STUDY DESIGN: Cytotrophoblasts isolated from human placentas collected at cesarean section from normal and preeclamptic women were incubated for 20 hours in 20% (vol/vol) sera from preeclamptic or gestational age–matched normal pregnant women. Levels of prostacyclin (measured as 6-keto-prostaglandin F_1α), prostaglandin E₂, and endothelin-1 were measured in cytotrophoblast supernatants. RESULTS: In normal pregnancy sera preeclamptic cytotrophoblasts secreted significantly lower amounts of prostacyclin and prostaglandin E₂ but higher amounts of endothelin-1 than did normal cytotrophoblasts. In preeclamptic sera the abnormality of prostacyclin secretion by preeclamptic cytotrophoblasts was partially corrected, but there was no effect on prostaglandin E₂ or endothelin-1 secretion. Preeclamptic sera had no effect on secretion by normal cytotrophoblasts. CONCLUSIONS: The differences between normal and preeclamptic cytotrophoblasts in prostacyclin, PGE₂, and endothelin-1 secretion and in response to preeclamptic serum suggest altered arachidonic acid metabolism in preeclampsia.(Am J Obstet Gynecol 1997;177:1491-5.)     

Responses of placental steroids, prostacyclin and thromboxane A2 to thermal stress during pregnancy.

The effect of heat stress on plasma prostacyclin and thromboxane A2 and serum estradiol, estriol and progesterone responses was studied in pregnant and non-pregnant women. Group I consisted of 15 healthy non-pregnant women, group II of 23 women 13-14 weeks pregnant, and group III of 23 women 36-37 weeks pregnant. Blood samples were taken before the heat stress, at the end of the stress (70 degrees C for 20 min) and 20 min and/or 45 min after the end of stress. The rectal temperature increased 0.3-0.4 degrees C. The concentration of progesterone did not change during the experiment but that of estradiol increased by 11% (P less than 0.005) in group II and by 10% (P less than 0.01) in group III after the end of the stress. Estriol increased only in group III (by 12%, P less than 0.005) after the end of the stress and the increase was higher as compared to group II (P less than 0.005). The metabolite of prostacyclin increased only in group III by 15% (P less than 0.05) during the heat stress. The metabolite of thromboxane A2 decreased in group II by 20% (P less than 0.005) at the end of the stress while there was no change in group III. The fetal heart rate reactivity remained unchanged and only few uterine contractions were recorded. The small changes found in the levels of prostanoids and placental steroids in response to heat stress do not seem to have any deleterious effects on fetal well-being. The slightly increased concentration of placental steroids may rather reflect changes in metabolism than an increase in uteroplacental blood flow.     

Hormones and cervical ripening: dehydroepiandrosterone sulfate, estradiol, estriol, and progesterone

Fetal adrenal steroids have been shown to be important in the timing of parturition. Since dehydroepiandrosterone sulfate is converted to estrogen, which is important in cervical softening, levels of dehydroepiandrosterone sulfate together with those of estradiol, estriol, and progesterone were measured and compared in pregnant women undergoing induction of labor with ripe and unripe uterine cervices. While there were no differences between the levels of estradiol, estriol and progesterone in the two groups of women, dehydroepiandrosterone sulfate was significantly elevated in the group of women with ripe cervices. These findings suggest that cervical changes preceding the onset of labor are associated with a significant elevation of maternal dehydroepiandrosterone sulfate levels. Changes in maternal plasma estradiol, estriol, and progesterone levels do not appear to be clinically related to cervical ripeness.     

MiR 20a,-20b and -200c are involved in hydrogen sulfide stimulation of VEGF production in human placental trophoblasts

Hydrogen sulfide (H₂S) has been implicated to angiogenesis in various tissues. We sought to investigate the role of hydrogen sulfide (H₂S) in regulating production of vascular endothelial growth factor (VEGF) proteins, the key factors of angiogenesis and vasculogenesis, in placenta.MethodsPlacental tissues were obtained from pregnant women with preeclampsia and healthy pregnant women who underwent elective cesarean section. Explants and trophoblasts were isolated from healthy placentas and treated with H₂S donor and precursor. Western blotting was used to determine the levels of cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE). The levels of VEGF mRNA, miR miR-200c,-20a and -20b were determined by quantitative real time PCR.ResultsNaHS and l-cysteine increased VEGF but not placenta growth factor (PlGF) production in cultured explants and trophoblasts. Transfection of CBS and CSE siRNA reversed the stimulatory effect of l-cysteine on VEGF production in placental cells. H₂S prolonged the half-life of VEGF mRNA and decreased the expression of miR-200c,-20a and -20b in placental cells. MiR-200c mimic and inhibitor affected VEGF mRNA and protein level, whereas miR-20a or -20b mimic and inhibitor affect VEGF protein release but not mRNA expression. The expression level of miR-200c,-20a and -20b as well as the level of CBS, CSE and VEGF were downregulated in preeclamptic placentas.ConclusionH₂S produced via CSE and CBS plays a critical role in VEGF production in human placenta. Reduced expression of CSE and CBS may contribute to the abnormal production of angiogenic factors in preeclamptic placenta.     

Garlic increases IL-10 and inhibits TNFalpha and IL-6 production in endotoxin-stimulated human placental explants

Preeclampsia is a multisystem disorder manifest by hypertension after 20 weeks' gestation associated with end organ damage, usually proteinuria. The placenta is thought to be pivotal in the pathogenesis of the disease. Both the placenta and the maternal systemic response are characterised by heightened inflammation. Garlic has been shown to have anti-inflammatory and pro-apoptotic properties amongst others. It was hypothesised that treating placental explants with garlic may inhibit the production of inflammatory cytokines (interleukin-6 (IL-6) and tumour necrosis factor (TNFalpha)) and stimulate the production of anti-inflammatory cytokines (interleukin-10 (IL-10)) by the placental explants. Garlic, we hypothesised, would also stimulate apoptosis in the explants as measured by soluble TNF-related apoptosis-inducing ligand/Apo-2L (sTRAIL) production. Normal placental explants (n=5) and explants from women who had preeclampsia (n=4) were cultured in the presence of various garlic concentrations (10-1000 microg/mL). The lowest garlic concentration (10 microg/mL) increased the normal explant production of IL-10 by 29.2% (12.2, 57.5%; p<0.01) while inhibiting the production of IL-6 by 23.5% (8.9, 32.5%; p<0.01) (normal explants) and TNFalpha by 19.4% (4.5, 35.3%; p<0.05) (preeclamptic explants). Garlic resulted in an increase in IL-10 production at lower doses (normal explants only) and inhibition of the production of IL-10 at higher doses (normal and preeclamptic explants). Garlic also resulted in a dose-dependent reduction of IL-6 and TNFalpha. Initially there was no change in sTRAIL production; however, at the highest garlic concentrations there was a significant increase in production. We thus conclude that garlic may have an immunomodulatory effect on normal and preeclamptic placentas.     

Vascular reactivity to angiotensin II and eicosanoid production in the human placenta from term and preterm pregnancy

Isolated human placental cotyledons from normal term (37-40 weeks of gestation) and preterm (26-36 weeks of gestation) labor were perfused in vitro, and the effect of angiotensin II (ANG II) and its interaction with prostanoids was measured. In the preterm group, ANG II caused greater maximal increases in perfusion pressure than in normal term pregnancies without affecting sensitivity. Also, preparations from normal term pregnancies showed a marked development of tachyphylaxis compared to placentae from preterm pregnancies. Indomethacin (10(-6) M) increased the maximum pressor response to ANG II by 33.6% in normal term, however, in preterm placentas a 39.2% reduction was observed. Infused ANG II 10(-6) M) decreased the concentrations of thromboxane B(2) and 6-keto-PGF(1alpha) in both pregnancy groups, but this effect was not statistically different from the baseline values. In the current study, we show that the placenta of preterm pregnancies in basal conditions produce 7.6 times as much thromboxane as the normal term placenta (2,800+/-470 vs. 366.5+/-62 pg/min, respectively), without significant change in prostacyclin levels (preterm 88.6+/-11.0 vs. Term 100.6+/-30.7 pg/min). These observations provide evidence that the contribution of basally released thromboxane from placental tissue appears to contribute to abnormalities in the regulation of fetoplacental hemodynamics in premature pregnancies.     

Garlic increases IL-10 and inhibits TNFα and IL-6 production in endotoxin-stimulated human placental explants

Preeclampsia is a multisystem disorder manifest by hypertension after 20 weeks' gestation associated with end organ damage, usually proteinuria. The placenta is thought to be pivotal in the pathogenesis of the disease. Both the placenta and the maternal systemic response are characterised by heightened inflammation. Garlic has been shown to have anti-inflammatory and pro-apoptotic properties amongst others. It was hypothesised that treating placental explants with garlic may inhibit the production of inflammatory cytokines (interleukin-6 (IL-6) and tumour necrosis factor (TNFalpha)) and stimulate the production of anti-inflammatory cytokines (interleukin-10 (IL-10)) by the placental explants. Garlic, we hypothesised, would also stimulate apoptosis in the explants as measured by soluble TNF-related apoptosis-inducing ligand/Apo-2L (sTRAIL) production. Normal placental explants (n=5) and explants from women who had preeclampsia (n=4) were cultured in the presence of various garlic concentrations (10-1000 microg/mL). The lowest garlic concentration (10 microg/mL) increased the normal explant production of IL-10 by 29.2% (12.2, 57.5%; p<0.01) while inhibiting the production of IL-6 by 23.5% (8.9, 32.5%; p<0.01) (normal explants) and TNFalpha by 19.4% (4.5, 35.3%; p<0.05) (preeclamptic explants). Garlic resulted in an increase in IL-10 production at lower doses (normal explants only) and inhibition of the production of IL-10 at higher doses (normal and preeclamptic explants). Garlic also resulted in a dose-dependent reduction of IL-6 and TNFalpha. Initially there was no change in sTRAIL production; however, at the highest garlic concentrations there was a significant increase in production. We thus conclude that garlic may have an immunomodulatory effect on normal and preeclamptic placentas.     

Anti-hypertensive drugs alter cytokine production from preeclamptic placentas and peripheral blood mononuclear cells.

OBJECTIVE: Antihypertensive drugs are administered to women with preeclampsia to control blood pressure and fluid overload. Whether they modulate placental or circulating cytokine production in women with preeclampsia is unknown. This study examines the effect of pharmacological doses of antihypertensive drugs on the production of IL-10, tumor necrosis factor alpha (TNF-alpha), and IL-6 in placental tissue and peripheral blood mononuclear cells (PBMCs) from women with preeclampsia. METHODS: Term placenta samples (n = 6) and PBMCs from whole blood (n = 6) were obtained from women with preeclampsia. Both villous explants and PBMCs were cultured with increasing concentrations of antihypertensive drugs (clonidine, diazoxide, hydralazine, and furosemide). The dose effect of drugs on the production of placental and circulating cytokines IL-10, TNF-alpha, and IL-6 was examined by enzyme-linked immunosorbent assay (ELISA). RESULTS: Our data suggest that clonidine can stimulate anti-inflammatory IL-10 production from PBMC while decreasing pro-inflammatory TNF-alpha, whereas low doses of hydralazine increased the production of IL-10, TNF-alpha, and IL-6 from preeclamptic PBMCs. There was a reduction in IL-10, TNF-alpha, and IL-6 production with increasing doses of clonidine and hydralazine by placentas in preeclampsia. IL-10, TNF-alpha, and IL-6 production from preeclamptic placenta and PBMCs were inhibited by diazoxide and furosemide. CONCLUSIONS: Antihypertensive drugs may alter Th1/Th2 cytokine balance in preeclamptic tissues in vitro.     

Serum and placental interleukin-18 are elevated in preeclampsia

OBJECTIVES: Interleukin-18 (IL-18) is a proinflammatory cytokine with pleiotrophic qualities and its roles in pregnancy, labor onset and pregnant complications have been proposed. However, the alterations of serum and placental IL-18 have been less investigated. The objective of the current investigation was to detect IL-18 concentrations in serum and placentas from patients with preeclampsia and women with normal pregnancy. METHODS: 27 patients with preeclampsia and 28 women with normal pregnancy were recruited. Blood and placental samples were taken and IL-18 concentrations in serum and placental homogenate were analyzed by enzyme-linked immunosorbent assay (ELISA). The levels of IL-18 in serum and placenta were compared between preeclampsia and control. RESULTS: Both serum and placental levels of IL-18 were significantly increased in preeclampsia as compared with control (P=0.014 and 0.003, respectively). Serum and placental levels of IL-18 were not significantly different in preeclamptic women who received dexomethasone and those who did not (P=0.223 and 0.330, respectively). Serum and placental IL-18 levels were not significantly different between preeclamptic women who delivered before 36 complete gestational weeks and those who delivered after 36 complete weeks (P=0.616 and 0.869, respectively). There were no significant differences in serum and placental IL-18 between women with mild preeclampsia and those with severe preeclampsia (P=0.056 and 0.357, respectively). CONCLUSIONS: Increased serum and placental levels of IL-18 were observed in preeclampsia. Those associations may offer insight into the pathogenesis of the disease.     

Expression levels of cyclooxygenase-2, tumor necrosis factor-α and inducible NO synthase in placental tissue of normal and preeclamptic pregnancies

Objective: Although preeclampsia (PE) is one of the most important problems affecting pregnant women, etiologic factors in its development are still unclear. We aimed to investigate the expression levels of cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α) and inducible NO synthase (iNOS) in preeclamptic and healthy control placentas. Patients and methods: Placental tissue samples were obtained after delivery from patients diagnosed with PE and from normal-term pregnants and analyzed for COX-2, TNF-α and iNOS expression by immunohistochemistry. Results: A strong expression of COX-2 was observed in syncytiotrophoblast cells of preeclamptic placentas, which was significantly higher than that of normal placentas (p?=?0.005). A mild expression of TNF-α in both normal and preeclamptic syncytiotrophoblasts was seen (p?=?0.435). In addition, a strong expression of iNOS in normal syncytiotrophoblasts was found, but the intensity of the iNOS expression was highly reduced in preeclamptic placentas (p?=?0.001). No correlation was detected between COX-2, TNF-α and iNOS expression levels. Conclusion: The findings of a decrease of iNOS expression and an increase of COX-2 expression in placenta suggest the existence of functional roles of iNOS and COX-2 in the pathophysiology of PE, probably by contributing to the reduced placental blood flow and increased resistance to flow in the fetomaternal circulation.