Enhancement of mitochondrial oxidative stress and up-regulation of antioxidant protein peroxiredoxin III/SP-22 in the mitochondria of human pre-eclamptic placentae

A growing body of evidence indicates that the pathogenesis of pre-eclampsia is closely associated with oxidative stress occurring in mitochondria. In the present study, we evaluated the degree of mitochondrial lipid peroxidation by assessing the accumulation of 4-hydroxy-2-nonenal (HNE)-modified proteins and examined the expression of mitochondrial antioxidant protein peroxiredoxin III/SP-22 in normal and pre-eclamptic human placentae. The accumulation of HNE-modified proteins increased to a greater extent in both the mitochondria and cytosol of pre-eclamptic placentae than in those of normal placentae. Moreover, the accumulation of HNE-modified proteins was much more evident in the mitochondria than in the cytosol, indicating that lipid peroxidation occurred mainly in the mitochondria of pre-eclamptic placentae. The mRNA expression of peroxiredoxin III/SP-22 was increased about 2-fold in pre-eclamptic placentae compared to normal placentae. The protein levels of peroxiredoxin III/SP-22 were approximately 4-fold higher in pre-eclamptic placentae than in normal placentae. Immunohistochemistry of placental tissues showed that the levels of peroxiredoxin III/SP-22 protein were increased in the trophoblasts of floating villi, stromal cells of stem villi, and decidual cells in pre-eclamptic placentae. These results indicate that peroxiredoxin III/SP-22 plays a crucial role in the protection of placental function from oxidative stress occurring in mitochondria of pre-eclamptic placentae.     

Placental nitric oxide synthase (NOS) activity and nitric oxide (NO) production in normal pregnancy, pre-eclampsia and eclampsia.

OBJECTIVES: To measure nitric oxide synthase (NOS) activity and total nitrites levels (as an index of nitric oxide 'NO' production) in placental villous homogenate of normal, pre-eclamptic and eclamptic pregnant women. DESIGN: Two groups were studied cross-sectionally: late pregnant women with pre-eclampsia and eclampsia (n=31) and normal pregnant women (all late) as controls (n=32). Two tissue blocks of whole placenta, each 1 x 1 x 1 cm, were collected at delivery and assayed for NOS activity and total nitrite levels. SETTING: Department of Obstetrics and Gynecology, Assiut University Hospitals, Egypt. METHODS: Placental tissues were homogenized and villous homogenates were assayed for NO production by Griess reaction which measures the combined oxidation products for NO (nitrites and nitrates) after reduction with nitrate reductase. NOS activity was determined by measuring NO synthesis by tissue extracts spectrophotometrically using the oxidation of oxyhemoglobin to methemoglobin by NO. RESULTS: Placental villous homogenates of pregnancies complicated by pre-eclampsia and eclampsia had significantly higher NOS activity and total nitrites levels compared with those of normal pregnancy [for NOS (P<0.0001) and for total nitrites (P<0.001)]. CONCLUSIONS: (1) Placental NOS activity and NO production are significantly increased in pre-eclampsia and eclampsia than those of normal pregnancy; this increase was directly related to the severity of this disorder. (2) Such increase possibly represents a physiologic adaptive response to overcome the increased placental vascular resistance and to minimize platelet and leukocyte adhesion to the surface of placental villi or within the intervillous spaces.     

Increased superoxide generation is associated with decreased superoxide dismutase activity and mRNA expression in placental trophoblast cells in pre-eclampsia

Pre-eclampsia is a multi-system disorder unique to human pregnancy. Although the aetiology of pre-eclampsia is still unknown, increased placental oxidative stress contributes to the pathophysiology of this pregnancy disorder. The goal of this study was to determine if placental trophoblast cells generate superoxide, and if there was a difference in superoxide generation and superoxide dismutase (SOD) activity between trophoblast cells isolated from pre-eclamptic placentae versus normal placentae. Placentae were obtained from nine normal and 10 pre-eclamptic pregnancies immediately after delivery. Trophoblast cells were isolated and purified by Percoll density gradient centrifugation. Superoxide generation and SOD activity were determined by spectrophotometric assays. Localization of CuZn-SOD protein within the placenta was examined by immunohistochemical staining. mRNA expression of CuZn-SOD was determined in trophoblast cells isolated from five normal and five pre-eclamptic pregnancies by Northern blot analysis. 18S ribosomal mRNA expression was used as an internal standard. We found: (1) trophoblast cells from pre-eclamptic placentae generated significantly more superoxide than trophoblast cells from normal placentae: 17.62+/-3.19 versus 4.70+/-0.76 nmol/5x10(6) cells (mean+/-s.e.), P< 0.01; (2) protein and mRNA expression for CuZn-SOD was mainly localized in the trophoblast cells within the placenta; and (3) SOD activity and relative mRNA expression for CuZn-SOD were significantly decreased in trophoblast cells from pre-eclamptic placentae as compared to trophoblast cells from normal placentae, SOD activity: 6.46+/-1.76 versus 13.01+/-1.67 units/mg protein, P< 0.05; relative mRNA expression for CuZn-SOD: 0.25+/-0.09 versus 0.73+/-0.07, P< 0.01. We conclude that increased superoxide generation was associated with decreased SOD activity and mRNA expression for CuZn-SOD in trophoblast cells isolated from pre-eclamptic placentae. These findings support the notion of increased oxidative stress in the pre-eclamptic placenta, which may contribute to the pathophysiology of this pregnancy disorder.     

Localization of indoleamine 2,3-dioxygenase and 4-hydroxynonenal in normal and pre-eclamptic placentae

This study was undertaken to compare placental levels of 2,3-Dioxygenase (IDO), a free radical scavenger, and 4-Hydroxynonenal (4-HNE), a major by-product of lipid peroxidation, in normal and pre-eclamptic pregnancies. Placentae were collected at caesarean section from women with a term, normal singleton pregnancy (37-40 weeks' gestation, n=10) and women with a term singleton pregnancy complicated by pre-eclampsia (n=10). IDO and 4-HNE localization and intensity was studied by semi-quantitative immunohistochemistry and differences between groups were analysed using the Mann-Whitney U test. Immunostaining for IDO was located primarily in endothelial cell nuclei, with a reduced level of staining in the cytoplasm, in most capillaries from all placentae examined. A significantly higher level of IDO immunostaining was observed in normal placentae compared to pre-eclamptic placentae (P=0.008). 4-HNE was located mainly in the cytoplasm of syncytiotrophoblast cells of all placentae examined. There were no significant differences in the pattern or intensity of 4-HNE immunostaining levels between normal and pre-eclamptic pregnancies (P=0.684). Our IDO results support the hypothesis of decreased anti-oxidative capability in the placenta and the possibility of an ineffective compensatory mechanism against increased oxidative stress in the fetus.     

Increased biological oxidation and reduced anti-oxidant enzyme activity in pre-eclamptic placentae

Oxidative stress occurs when cellular levels of reactive oxygen species exceed anti-oxidant capabilities and has been implicated in the pathogenesis of pre-eclampsia. In this study we have examined the tissue levels of endogenous anti-oxidant proteins (superoxide dismutase, glutathione peroxidase, thioredoxin reductase and thioredoxin) and the level of lipid and protein oxidation in placental samples from normal and pre-eclamptic pregnancies. Pre-eclamptic tissue homogenates demonstrated significantly increased levels of lipid peroxidation (20.68 +/- 7.811 microM protein versus 5.33 +/- 4.03 microM/mg protein, P < 0.001) and a trended increase in protein carbonyl concentration (248.1 +/- 97.71 units/mg protein versus 209.7 +/- 82.6 U/mg protein) when compared to controls. The levels and activities of the anti-oxidant proteins superoxide dismutase (2.48 +/- 0.6 U/mg protein versus 2.02 +/- 0.51 U/mg protein, P <0.02), thioredoxin reductase (19.25 +/- 9.81 U/mg protein versus 13.02 +/- 5.66 U/mg protein,P = 0.02), thioredoxin (107.00 +/- 18.11 ng/mg protein versus 91.12 +/- 21.18 ng/mg protein, P = 0.02) and glutathione peroxidase (17.33 +/- 6.63 mmol/min/mg protein versus 11.50 +/- 3.11 mmol/min/mg, P < 0.02) were all found to be significantly reduced when comparing pre-eclamptic placental tissue homogenates to gestational age-matched control placentae from non-pre-eclamptic pregnancies. The results of this study demonstrate a decreased enzymatic anti-oxidant capacity and increased oxidation in placental tissue from pre-eclamptic women, which may contribute to the pathogenesis of this complex disorder.     

Enhanced protein levels of protein thiol/disulphide oxidoreductases in placentae from pre-eclamptic subjects.

Recent studies have indicated that pre-eclampsia is closely associated with oxidative stress both in maternal circulation and in the placenta. Protein thiol/disulphide oxidoreductases, such as thioredoxin, glutaredoxin, and protein disulphide isomerase have recently been found to eliminate reactive oxygen species (ROS) and regenerate oxidatively damaged proteins. Protein thiol/disulphide oxidoreductases may also play a role in combating pre-eclampsia. In this study, we examined the accumulation of 4-hydroxy-2-nonenal (HNE)-modified proteins, which are markers of lipid peroxidation, in human placentae of normal and pre-eclamptic subjects. We also examined the protein levels of thioredoxin, glutaredoxin, and protein disulphide isomerase in placentae. Immunoblotting and immunohistochemistry showed that HNE-modified proteins accumulated to a greater extent in pre-eclamptic placentae than in normal placentae. In both normal and pre-eclamptic placentae, thioredoxin, glutaredoxin, and protein disulphide isomerase were detected in the trophoblasts of the floating villi. The levels of these proteins were increased approximately 2- to 3-fold in the pre-eclamptic placentae compared to the normal placentae. These results indicated that the pre-eclamptic placentae were exposed to oxidative stress and that the protein thiol/disulphide oxidoreductases were adaptively induced in pre-eclamptic placentae, suggesting possible roles for thioredoxin, glutaredoxin, and protein disulphide isomerase in protecting placental functions against oxidative stress caused by pre-eclampsia.     

Monoamine oxidase expression and activity in human placentae from pre-eclamptic and normotensive pregnancies

A feature of pre-eclampsia is that circulating levels of maternal serotonin (5-hydroxytryptamine) are elevated and placental monoamine oxidase-A (MAO-A) activity, the major factor in the regulation of serotonin levels in pregnancy, is reduced. It is not known whether this is due to a reduced MAO-A protein content or a reduced catalytic turnover of the serotonin by MAO-A; this question has been addressed in the present work. Term placentae from normotensive and pre-eclamptic women were analysed for MAO-A specific mRNA expression (by semi-quantitative RT-PCR), MAO-A protein (by immunohistochemistry and quantitative ELISA, using a MAO-A specific monoclonal antibody), together with MAO activity (using [(3)H] labelled 5-hydroxytryptamine as substrate). Immunohistochemical analysis of placentae from both normotensive and pre-eclamptic women demonstrated that MAO-A protein is located in the cytoplasm of the placental syncytiotrophoblast layer, consistent with a mitochondrial location; no MAO-A protein was found in the nucleus. No MAO-B protein was detected in this placental layer, despite the presence of MAO-B mRNA. The results indicate that both total protein/g fresh weight and MAO-A protein/g fresh weight were approximately 40 per cent lower in pre-eclamptic than in normotensive placentae, but that there was no statistical difference in the expression of MAO-A mRNA in relation to GAPDH or actin mRNA or in MAO-A protein/mg total protein. However, MAO-A activity/g fresh weight was significantly reduced in pre-eclamptic placentae, in agreement with previous findings. This was found to be due to a 60 per cent reduction (P< 0.05) in the catalytic turnover (activity/molecule) of the enzyme. This study has therefore clearly shown that the expression of placental MAO-A specific mRNA and MAO-A protein are not specifically affected in pre-eclampsia, but that the catalytic efficiency of the expressed MAO-A enzyme in pre-eclamptic placentae is greatly reduced.     

Raised prorenin and renin concentrations in pre-eclamptic placentae when measured after acid activation

AIM: The aim of the study was to ascertain if there was any difference in the levels of prorenin and active renin between pre-eclamptic and normotensive feto-placental tissues. METHODS: Supernatants of homogenates from fresh, vaginally delivered placentae from 15 normotensive and 15 pre-eclamptic women were measured for renin concentration (RC), prorenin concentration and renin activity (RA). RA and RC were measured in the absence and presence of nephrectomised sheep plasma, respectively. Prorenin was estimated as the difference between renin concentration in the sample before and after acid activation. All concentrations are expressed as rate of angiotensin generation (ng/ml/h). Angiotensin I was measured by radioimmunoassay. Statistical analysis was performed using Student's 't' test for unpaired samples. All results are presented as mean+/-SEM. RESULTS: The concentrations of renin and prorenin were highest in the chorion laeve when compared to amnion and placenta (p < 0.01) in both the groups. Furthermore, the concentrations of renin and prorenin were significantly higher in all the tissues from women with pre-eclampsia (p < 0.01). CONCLUSION: Renin and prorenin levels are raised in the placental tissues from women with pre-eclampsia. With recent evidence suggesting that both prorenin and renin may have cellular effects independent of angiotensin II generation, there is a need for further study into its role in placentation.     

Endothelin-l in feto-placental tissues from normotensive pregnant women and women with pre-eclampsia

AIMS: The pathogenesis of pre-eclampsia is still unclear. Placental hypoperfusion, which precedes the maternal manifestations of pre-eclampsia, could be due to some vasoconstrictor factor/s like endothelin-1. The aim of the study therefore was to estimate the levels of endothelin-1 in feto-placental tissue homogenates from normotensive pregnant women and women with pre-eclampsia. METHOD AND MATERIAL: Fresh, vaginally delivered placentae from ten normotensive pregnant women and nine women with pre-eclampsia were carefully dissected and 4 gm each of amnion, chorion laeve, placental plate chorion, fetal placenta (fetal surface of the placenta) and maternal placenta (surface of the placenta attached to the uterine wall) were obtained. These tissues were then thoroughly washed in a 0.5 M phosphate buffer, pH 7.5, at room temperature and then individually homogenized for one minute in 4 ml of the same buffer. After centrifugation the supernatant was removed. The pellet was re-suspended in buffer, re-homogenized and then centrifuged. The supernatant was removed and the procedure was repeated once again and the three supernatants of each tissue were pooled. Endothelin-1 was estimated by RIA. All results are presented as mean+/-SEM. Statistical analysis was performed using students 't' test for unpaired samples and a 'p' value of <0.05 was considered significant. RESULTS: In tissues from normotensive pregnant women, no significant differences were evident in endothelin-1 concentrations in the chorion laeve, fetal placenta and maternal placenta but were significantly higher than those in the amnion and placental plate chorion (p<0.01). In tissues from pre-eclamptic women, no significant differences were evident between endothelin-1 concentrations in the chorion laeve, placental plate chorion and fetal placenta. Mean endothelin-1 concentration in the amnion and maternal placenta were significantly lower than those in chorion laeve, placental plate chorion and fetal placenta (p<0.01). Endothelin-1 concentrations were significantly higher in the amnion, chorion laeve, placental plate chorion and fetal placenta from women with pre-eclampsia when compared to tissues from normotensive pregnant women (p<0.01). CONCLUSIONS: Endothelin-1 levels were significantly higher in the placental tissues from women with pre-eclampsia. Endothelin-1, being a powerful vasoconstrictor, could cause significant vasoconstriction in the placental vasculature, and alterations in endothelin-1 levels in placental vasculature may therefore have a role in the pathogenesis of pre-eclampsia.     

Umbilical flow in the normal and pre-eclamptic placenta. A study in vitro

In order to develop a simple in vitro method for assessing adequacy of placental perfusion, umbilical flow was measured in placentae from 10 normal control women and from 10 women with pre-eclampsia, by infusing through the umbilical arteries a heparinized 0.9% saline solution. The average induced umbilical flow in placentae from uneventful pregnancies was 276 +/- 16 SE ml/min compared with 163 +/- 12 ml/min (p less than 0.001) in the pre-eclamptic group. In angiographic studies, 79 +/- 2 SE% of the cotyledons from the normal series, and only 56 +/- 3% (p less than 0.001) from the pre-eclamptic series were functional. Additionally, gross and histological examination revealed three distinct types of cotyledon. Placental areas that blanched following saline infusion showed no blood in the collapsed villi or in the intervillous space; areas distinguished by a ruddy appearance following perfusion showed blood trapped in the villi and in the intervillous space; in a third area, the findings were mixed. When compared with placental zones identified by perfusion with 5% Hypaque solution, these three anatomical regions corresponded to normal, reduced, or absent flow (blanched, intermediate, or ruddy regions, respectively). We conclude that under the conditions of this in vitro study, pre-eclamptic placentae had a greater proportion of umbilical perfusion deficits than had normal placentae.     

Vascular endothelial growth factor expression is unaltered in placentae and myometrial resistance arteries from pre-eclamptic patients

BACKGROUND: The purpose of this study is to determine whether there is any difference for vascular endothelial growth factor expression in placentae and myometrial resistance arteries from control and pre-eclamptic patients to clarify the source of the increased total vascular endothelial growth factor in pre-eclampsia. METHODS: With placentae tissue samples and small pieces of myometrium from the controls (n=10) and pre-eclampsia patients (n=7), vascular endothelial growth factor immunohistochemistry and mRNA in situ hybridization were performed. We also measured the serum vascular endothelial growth factor levels by competitive enzyme immunoassay at the same time. RESULTS: Vascular endothelial growth factor was identified primarily in syncytiotrophoblast in placental tissue, and it was also identified in smooth muscle cells in the myometrium and perivascular smooth muscle in myometrial resistance arteries. However, there were no differences in vascular endothelial growth factor expression between the groups in the presence of elevated serum levels of total vascular endothelial growth factor in pre-eclamptic patients (median 18.2 ng/ml versus 4.9 ng/ml). CONCLUSION: This study suggests that the placenta and perivascular smooth muscle are not the origin of the increased total vascular endothelial growth factor in pre-eclampsia. To clearly understand the role of vascular endothelial growth factor in pre-eclampsia, further studies are required to determine the sites of increased vascular endothelial growth factor synthesis.     

Placental mitochondria as a source of oxidative stress in pre-eclampsia

Pre-eclampsia is a hypertensive disorder of human pregnancy that is a leading cause of premature delivery and fetal growth retardation. It is characterized by hypertension, reduced uteroplacental blood flow, proteinuria and oedema. Pre-eclampsia is associated with increased lipid peroxidation in the maternal circulation and in the placenta. Mitochondria are sources of oxygen radicals and are enriched with polyunsaturated fatty acids that are susceptible to peroxidation. Therefore, the mitochondria could be an important source of oxidative stress and lipid peroxidation. To study this, the level of lipid peroxidation in the mitochondrial fraction of placentae obtained from normally pregnant women (n=8) and women with pre-eclampsia (n=8) was examined. Placental tissues were homogenized and the mitochondrial fraction was isolated by ultracentrifugation. Mitochondrial lipid peroxides were estimated by malondialdehyde (MDA). NADPH and Fe⁺⁺ were used to stimulate lipid peroxidation. Superoxide dismutase (SOD) was used to inhibit superoxide radicals and mannitol to inhibit hydroxyl radicals. The following results were found: (1) MDA levels were significantly greater in the mitochondrial fraction isolated from pre-eclamptic placentae than from normal placentae (27.4 ± 3.0 versus 17.0 ± 1.8 nmol/g tissue, mean ± s.e., P<0.05); (2) the oxidative potential of the pre-eclamptic mitochondrial fraction was also higher than normal as evidenced by the significantly greater stimulation of lipid peroxidation by NADPH and Fe⁺⁺ (248 ± 25 versus 164 ± 35 nmol/g, P<0.05); (3) superoxide dismutase, but not mannitol, attenuated the lipid peroxidation induced by NADPH and Fe⁺⁺ demonstrating that superoxide is the radical responsible for mitochondrial lipid peroxidation in this system; and (4) the amount of mitochondrial protein was 47 per cent greater and the activity of the mitochondrial enzyme, citrate synthase, was 56 per cent greater in the pre-eclamptic placentae indicating an increase in the amount of mitochondria in the pre-eclamptic placentae. It is concluded that: (1) mitochondrial lipid peroxidation is increased in pre-eclampsia; (2) the amount of placental mitochondria is increased in pre-eclampsia; (3) placental mitochondria contribute to the abnormal increase in lipid peroxidation that occurs in pre-eclamptic placentae by both an increase in their amount and an increase in their susceptibility to oxidation; and (4) mitochondrial generation of superoxide could be an important source of oxidative stress in pre-eclampsia.     

Total peroxyl radical-trapping ability and anti-oxidant vitamins of the umbilical venous plasma and the placenta in pre-eclampsia

AIM: Our purpose was to investigate lipid peroxide levels, total peroxyl radical-trapping anti-oxidative parameter (TRAP) values, and anti-oxidant vitamin levels in umbilical venous plasma and placental tissues, and to evaluate their roles in the pathophysiology of pre-eclampsia. METHODS: Samples of umbilical venous plasma and placental tissue homogenates were obtained from 23 normal and 18 pre-eclamptic women at between 33 and 40 weeks' gestation. The enzyme-linked immunosorbent assay method was used to assay alpha-tumor necrosis factor (TNF-alpha), and lipid peroxide levels were measured by thiobarbituric acid reaction. The TRAP values were measured using the modified Wayner's method. Ascorbic acid, retinol alpha-tocopherol and gamma-tocopherol were measured by high performance liquid chromatography. RESULTS: Levels of TNF-alpha in placental tissue homogenates of women with pre-eclampsia were significantly higher than those of women with normal pregnancy (21.4 +/- 3.39 v. 10.3 +/- 1.06 pg/mL, P < 0.05). Lipid peroxide levels in umbilical venous plasma and placental tissue homogenates of women with pre-eclampsia were significantly higher than those of women with normal pregnancy (10.3 +/- 1.1 v. 5.85 +/- 0.53, P < 0.01, 5.14 +/- 0.40 v. 3.99 +/- 0.33 nmol/mg protein, P < 0.05, respectively). The TRAP values in umbilical venous plasma and placental tissue homogenates of women with pre-eclampsia were significantly lower than those of women with normal pregnancy (0.39 +/- 0.02 v. 0.45 +/- 0.02, P < 0.05, 0.27 +/- 0.02 v. 0.34 +/- 0.03 mM, P < 0.05, respectively). Ascorbic acid levels in umbilical venous plasma and placental tissue homogenates of women with pre-eclampsia were significantly lower than those of women with normal pregnancy (325.4 +/- 50.4 v. 543 +/- 73.8, P < 0.05, 219.0 +/- 21.0 v. 333.3 +/- 32.6 nmol/mL, P < 0.05, respectively). CONCLUSIONS: The above results suggest that increased oxidative stress in the placenta is involved in the pathophysiology of pre-eclampsia, and ascorbic acid may act as an important preventative factor in the development of pre-eclampsia.     

Plasma antithrombin III levels in pre-eclampsia and chronic hypertension

Plasma levels of antithrombin III were tested during pregnancy in a control group of normal patients and in a study group that included patients with moderate and severe pre-eclampsia and chronic hypertension. The control group showed mean antithrombin III activity of 97.9 +/- 20.9%, the severe pre-eclamptic patients 22.33 +/- 18.22%, the moderate pre-eclamptic patients 56.0 +/- 7.56%, and the chronic hypertensive patients 77.5 +/- 6.69%. The difference between normal pregnancy and moderate pre-eclampsia was significant at P less than 0.002, normal pregnancy and severe pre-eclampsia P less than 0.002, moderate and severe pre-eclampsia P less than 0.002, chronic hypertension and normal pregnancy P less than 0.1, and chronic hypertension and severe pre-eclampsia P less than 0.002. All the severe pre-eclamptic patients and 2 out of 6 of the moderate pre-eclamptic women were below 55.7% (mean - 2S.D.) of normal antithrombin III activity. Patients with heavy proteinuria had depressed antithrombin III activity. However, chronic hypertensive pregnancies, although rather a small group, had almost normal values of plasma antithrombin III activity. The plasma antithrombin III value may thus help to distinguish between chronic hypertension and severe pre-eclamptic disease.     

The regional expression of insulin-like growth factor II (IGF-II) and insulin-like growth factor binding protein-1 (IGFBP-1) in the placentae of women with pre-eclampsia

Insulin-like growth factors and their binding proteins regulate cellular proliferation, differentiation and function, and play an important role in placental development. IGF-II and IGFBP-1 are abundantly expressed by cells at the maternal-fetal interface and mediate cell-to-cell communication between trophoblasts and decidua. Placentae of pre-eclamptic pregnancies show villous cytotrophoblast proliferation, increased syncytial sprout formation and impaired trophoblast invasion. We hypothesized that the expression of IGF-II and IGFBP-1 by cells at the maternal-fetal interface is altered in pre-eclampsia. We determined the regional abundance and cellular localization of IGF-II mRNA and IGFBP-1 mRNA and protein in placentae from normotensive control and pre-eclamptic pregnancies. IGF-II mRNA was expressed in both the chorionic villi and basal plate decidua regions. Increased IGF-II mRNA abundance was observed in the intermediate trophoblasts of peri-infarct regions. IGFBP-1 expression was present only in the decidua of the basal plate and membranes, and this expression was decreased significantly in pre-eclamptic placentae. The increased IGF-II expression in the intermediate trophoblast surrounding placental infarcts suggests a role for IGF-II in placental repair or remodelling. Decreased IGFBP-1 mRNA expression in the basal plate decidua suggests that the increased concentrations of IGFBP-1 the circulation of pre-eclamptic women is not of decidual origin. The altered IGF-II and IGFBP-1 expression at the fetomaternal interface may be important in the pathophysiology of pre-eclampsia.     

Vasoactive effects of 8-epi-prostaglandin F(2alpha)in isolated human placental conduit and resistance blood vessels in vitro.

The effects of 8-epi-prostaglandin F(2alpha)(8-epi-PGF(2alpha)) and the thromboxane A(2)-mimetic U46619 were examined on isolated human fetal placental arteries obtained from normal pregnancies and from those complicated by pre-eclampsia. The effects of these agents were examined on both conduit and resistance arteries. 8-epi-PGF(2alpha)was found to be markedly less potent than U46619 in constricting both size vessels. Vasoconstrictor EC(50)s for 8-epi PGF(2alpha)were 4.10x10(-7) m (2.02-8.35x10(-7) m) (mean, 95 per cent CI and 2.05x10(-6) m (0.43-9.89 x10(-6) m) in conduit and resistance arteries, respectively. The maximum vasoconstriction produced by 8-epi-PGF(2alpha)(112+/-17 per cent), (relative to maximum KCl induced vasoconstriction) in conduit vessels was significantly less than that caused by U46619 (152+/-20 per cent). In resistance vessels the maximum vasoconstrictor effects to 8-epi-PGF(2alpha)(208+/-10 per cent) and U46619 (201+/-19 per cent) were similar, and in both cases significantly greater than the maximal effects seen in conduit vessels. U46619 displayed a similar vasoconstrictor potency in both conduit (EC(50)=1.21x10(-9) m, 0.58-2.51x10(-9) m) and resistance arteries [EC(50)=5.95x10(-9) m, (0.81-43.60x10(-9) m] as was found for 8-epi PGF(2alpha). 8-epi-PGF(2alpha)was equipotent in resistance arteries obtained from women with severely pre-eclamptic pregnancies (EC(50)=1.25x10(-6) m, 0.25-6.17x10(-6) m) compared with normotensive controls. However, the maximum vasoconstrictor effect induced by 8-epi-PGF(2alpha)in placental resistance arteries was significantly reduced (99+/-20 per cent) in vessels obtained from severely pre-eclamptic compared with normal pregnancies. These results indicate that 8-epi-PGF(2alpha)displays differential vasoconstrictor activity in the fetal-placental vasculature. Furthermore the vasoconstrictor effects of 8-epi-PGF(2alpha)are reduced in pre-eclampsia, the effect being selective to placental resistance vessels. This reduction may occur as a result of more serious disturbances in the placental microcirculation with the disease process in pre-eclampsia.     

Large chloride channel from pre-eclamptic human placenta

Chloride transport involving conductive pathways participates in numerous epithelial functions, such as membrane voltage maintenance, solute transport and cell volume regulation. Evidence points to involvement of transepithelial chloride transport in such functions in placental syncytiotrophoblast. A molecular candidate for physiologic conductive chloride transport in apical syncytiotrophoblast membrane is a Maxi-chloride channel with distinct biophysical properties: conductance over 200 pS, multiple substates, voltage dependent open probability, and permeation to anionic amino acids. Pre-eclampsia, a high incidence pathology of pregnancy, exerts great impact on fetal morbi-mortality. This relies, among others, on intrauterine growth restriction (IUGR), thought to be mediated by diminished blood flow to the placenta, with growing knowledge regarding contribution of other factors. The Maxi-chloride channel's properties suggest it could be altered in this pathology. We have characterized the apical chloride channels from pre-eclamptic placentae, reconstituted in giant liposomes suitable for patch-clamp electrophysiological studies. In n=33 experiments from n=6 pre-eclamptic placentae we observed a chloride-permeable channel with similar biophysical properties to the channel from normal tissue (n=29 experiments from n=15 placentae). However, the main conductance state showed diminished magnitude (<150 pS), and the open probability versus voltage relationship exhibited a flattened curve instead of the bell-shaped curve of normal placentae. These results are the first evidence of a functionally altered ionic channel from placental syncytiotrophoblast in pre-eclampsia. Considering the abundance of chloride-conducting channel activity in human apical membrane and their relevance in epithelial function in general, these alterations could greatly disturb numerous placental functions that rely on syncytiotrophoblast integrity.     

Intrauterine expression of parathyroid hormone-related protein in normal and pre-eclamptic pregnancies

Maternal hypertension, vasoconstriction and placental insufficiency are features of pre-eclampsia. Alterations in calcium homeostasis and in the production of calciotropic hormones and vasoactive agents have also been described in association with pre-eclampsia. Parathyroid hormone-related protein (PTHrP) is abundantly expressed in intrauterine tissues during normal pregnancy and has roles in fetal growth and calcium homeostasis, placental calcium transport and vascular tone regulation. Intrauterine PTHrP mRNA expression and tissue PTHrP content were determined by Northern blot analysis and radioimmunoassay, respectively, in preterm and term pre-eclamptic women. PTHrP mRNA expression and PTHrP content in placenta, amnion over placenta, reflected amnion and choriodecidua from preterm pre-eclamptic women (n=8−10) were not different from preterm controls (n=10−12). PTHrP rnRNA expression and content in amnion over placenta and reflected amnion were significantly greater in term compared to preterm pre-eclamptics (P<0.05). PTHrP mRNA expression was significantly lower in choriodecidua from term pre-eclamptic women (n=8) compared to term controls (n=28, P<0.05), but was not different in placenta or amnion. PTHrP content was not altered in term pre-eclamptic women (n=8) compared to controls (n=25) for any tissue. In summary, PTHrP expression in placenta and amnion was not increased in pre-eclamptic women in association with maternal hypertension, placental insufficiency and vasoconstriction. PTHrP rnRNA expression was decreased in choriodecidua in association with term but not preterm pre-eclampsia, however, levels of the protein were not decreased. The data suggest that PTHrP is not involved in the placental pathophysiology of pre-eclampsia in late gestation.     

Placental stem cell markers in pre-eclampsia

OBJECTIVE: To investigate the placental CD34, CD44, and leukemia inhibitory factor (LIF) levels in normotensive and pre-eclamptic women. METHOD: The study population consisted of 21 women with pre-eclampsia. Twenty normotensive pregnant women served as controls and were matched to pre-eclamptic patients by gestational age at delivery. Decidual samples obtained from the central part of the placenta were stored at -70 degrees C until analysis. CD44 and LIF were quantified in homogenates by enzyme-linked immunosorbent assay (ELISA), while CD34 was quantified by flow cytometry. RESULTS: The pre-eclamptic and normotensive groups were well matched. There were no significant differences in age, parity, weight, and gestational age at birth between the groups (P>0.05). The mean placental levels of CD34 (6.55+/-2.48 vs 3.16+/-1.23), CD44 (385.24+/-178.85 vs 157.75+/-31.73, and LIF (140+/-51.11 vs 96.25+/-31.62) were significantly higher in pre-eclamptic compared with normotensive women, respectively (P<0.05). CONCLUSION: Higher levels of CD34, CD44, and LIF were found in the placentas of pre-eclamptic compared with normotensive women.