Placental NAD(P)H oxidase mediated superoxide generation in early pregnancy.

Early placental development is characterised by rapid cell differentiation and migration, matrix remodelling and angiogenesis. The enzyme NAD(P)H oxidase is a major source of superoxide anions implicated in signalling pathways regulating these processes in other systems. It is also thought to be involved in oxygen sensing and regulation of the expression of antioxidant genes. We therefore investigated NAD(P)H oxidase activity in placental tissues in early pregnancy and at term, and correlated this with antioxidant capacity. We collected placental tissues from women undergoing termination of pregnancy (n=19; gestational age 11(+6)+/-1(+0) weeks), and those with elective caesarean section at term after uncomplicated pregnancy (n=15; gestational age 38(+6)+/-0(+4) weeks). Tissues were assayed for superoxide production, using lucigenin chemiluminescence, and three independent markers of antioxidant capacity. In human placentas from normal deliveries at term substantial basal NAD(P)H activity was present. Activity was almost threefold higher in early pregnancy (P<0.0001). This was paralleled by higher total antioxidant capacity (P<0.0001), tissue glutathione concentrations (P<0.01) and gluthathione S-transferase enzyme activity (P<0.05) when compared to corresponding term placental values. NAD(P)H oxidase mediated superoxide generation could be an important modulator of the antioxidant defence response in early pregnancy.

Severe preeclampsia is associated with a positive family history of hypertension and hypercholesterolemia.

OBJECTIVE: To investigate an association between a family history of cardiovascular disease and severe preeclampsia and/or HELLP syndrome (Haemolysis, Elevated Liver enzymes, Low Platelets). METHODS: One hundred twenty-eight women with a history of severe preeclampsia and/or HELLP syndrome and 123 women with previous uncomplicated pregnancies only were included in the study. All participants completed questionnaires about diagnoses of cardiovascular diseases, hypertension, and hypercholesterolemia among their first-degree relatives, which were subsequently confirmed by the relatives' general practitioners. The main outcome measures were the prevalence of cardiovascular diseases, hypertension, and hypercholesterolemia among first-degree relatives of both groups. Statistical analysis was done using chi(2)-analysis. RESULTS: The prevalence of familial cardiovascular disease among women with a history of severe preeclampsia and/or HELLP syndrome (23%) compared to controls (19%) was not significantly different (OR 1.3, 95%CI 0.7-2.5). However, women with a history of severe preeclampsia and/or HELLP syndrome more often had one or more first-degree relatives with hypertension and/or hypercholesterolemia before the age of 60 years compared to controls (54% vs. 32%, respectively; OR 2.6, 95%CI 1.5-4.3). The prevalence of hypertension and hypercholesterolemia among first-degree relatives, irrespective of age, also was significantly higher among women with a history of severe preeclampsia and/or HELLP syndrome as compared to controls (60% vs. 42%, respectively; OR 2.0, 95%CI 1.2-3.4). CONCLUSION: Severe preeclampsia is associated with a positive family history of hypertension and/or hypercholesterolemia.

Urinary GSTP1-1 excretion is markedly increased in normotensive pregnancy as well as in preeclampsia.

BACKGROUND: Glutathione S-transferases (GSTs) are present in large amounts in the human kidney, where they demonstrate a specific distribution. The assessment of urinary excretion of GST alpha (proximal tubules) and pi (distal and collecting tubules) could be helpful in determining if, and to what degree renal tubular damage is present in preeclampsia and whether this damage is in the proximal or distal region. METHODS: Urine samples were collected from 22 women with severe preeclampsia and/or HELLP syndrome (PE), from 30 non-pregnant women with a history of severe preeclampsia (HPE), from 18 women with uncomplicated pregnancies (PC) and from 30 non-pregnant women with a history of uncomplicated pregnancies (HPC). GSTA1-1 and GSTP1-1 were assayed by ELISA and were expressed as nanograms per 10 mmol creatinine (Cr). RESULTS: Median urinary GSTP1-1 concentrations were significantly (p<0.001) higher in women with preeclampsia [62.2 (4.3-291.2) ng/10 mmol Cr] compared to non-pregnant women with a history of preeclampsia [22.3 (0-142.6) ng/10 mmol Cr]). In addition, in normotensive pregnant women, urinary GSTP1-1 concentrations were significantly (p<0.01) higher [82.6 (8.3-206.7) ng/10 mmol Cr]) compared to non-pregnant controls [5.1 (0-66.7) ng/10 mmol Cr]. No difference in GSTP1-1 concentrations was found between women with preeclampsia and normotensive pregnant women. GSTA1-1 concentrations were not significantly different between the four groups of women investigated. There were no correlations between the degree of proteinuria and urinary GSTP1-1 or GSTA1-1 concentrations. CONCLUSION: GSTP1-1 metabolism in the distal tubule changes during normotensive as well as preeclamptic pregnancy. Whether this is due to tubular cell damage, disturbed resorption or an increase in cellular levels cannot be determined as yet.

Amino thiols, detoxification and oxidative stress in pre-eclampsia and other disorders of pregnancy.

New knowledge of placental development and function suggests that several common complications of pregnancy could share a similar origin. It is suggested that impaired placental development in early pregnancy may lead to placental oxidative stress and subsequently to the maternal syndromes such as recurrent early pregnancy loss and pre-eclampsia. Oxidative stress has been most extensively investigated in pre-eclampsia, resulting in hundreds of publications and many reviews. In general the literature points to the presence of placental and maternal oxidative stress. However, conformity amongst the relevant data is not absolute, most probably the result of the diversity of biomarkers investigated and the methods employed to assess oxidative stress, which generally depend on the assessment of end products of oxidative stress. Recently, new techniques have been developed that use different approaches based on the "real-time" measurement of oxidative stress by the redox status of thiols or the assessment of superoxide generation, whereas the role of Phase I/Phase II biotransformation pathways in oxidative stress was recognised. This review focuses on this biotransformation system, the thiol redox status and the involvement of these systems in oxidative stress associated with reproduction and pregnancy disorders, with the emphasis being laid on the syndrome of pre-eclampsia.

High levels of urinary vascular endothelial growth factor in women with severe preeclampsia.

Elevated plasma VEGF concentrations in preeclampsia are associated with local placental ischemia and endothelial dysfunction. We investigated the urinary VEGF excretion in women with severe preeclampsia (n=37) and its relation with proteinuria compared to that in healthy pregnant (n=32) and non-pregnant women (n=30). In women with severe preeclampsia VEGF levels were 54.0 (19.9-192.4) ng/mmol creatinine, significantly (p<0.0001) higher than levels in pregnant controls (28.2 (6.7-63.0) ng/mmol creatinine) and non-pregnant controls (29.5 (10.1-59.1) ng/mmol creatinine). Proteinuria was not significantly correlated with urinary VEGF levels. In conclusion, high urinary VEGF concentrations in severe preeclampsia might reflect increased renal production of VEGF rather than elevated VEGF levels in the systemic circulation.

Trophoblast oxidative stress, antioxidants and pregnancy outcome--a review.

Placental oxidative stress has been implicated in pre-eclampsia and miscarriage. The review briefly summarizes the definition of oxidative stress, methods of estimation and likely sources in the placenta. Experimental evidence favouring a role for trophoblast oxidative stress in pre-eclampsia includes reports of lipid peroxidation and deficiencies in antioxidant defences. The potential sources of free radical generation include enhanced enzymatic synthesis of superoxide by xanthine oxidase and NAD(P)H oxidase. Studies employing immunohistochemical markers of oxidative stress also implicate free radical induced damage in placentae from women with early pregnancy loss. The overwhelming evidence for oxidative stress in the placenta and the maternal circulation in pre-eclampsia has led to the suggestion that antioxidant prophylaxis may prevent oxidant stress and so ameliorate or prevent the disease. Several clinical trials currently underway will not only determine whether antioxidants are of use in pre-eclampsia prevention but also provide an ideal opportunity to investigate the aetiology and consequences of trophoblast oxidative stress.

NAD(P)H oxidase associated superoxide production in human placenta from normotensive and pre-eclamptic women.

Oxidative stress plays an important role in the development of pre-eclampsia. Recently, the superoxide producing enzyme NAD(P)H oxidase was shown to be present in placental trophoblast. In this pilot-study we investigated the NAD(P)H oxidase associated superoxide production as modulator of placental oxidative stress in normotensive pregnancy (n = 19; gestational age 38(+6)+/-0(+1)weeks(+days)) and pre-eclampsia (n = 15; gestational age 34(+3)+/-1(+5)weeks(+days)) using a lucigenin assay. Specificity of superoxide generation by NAD(P)H oxidase was assessed using the inhibitors L-NAME, rotenone, allopurinol, DPI and TIRON. Superoxide production was measurable in all placenta tissues and was inhibited by DPI and TIRON. No significant differences for total superoxide production (O2*total), maximal superoxide production (O2*max), or the rate of superoxide production were found between normotensive and pre-eclamptic women. However, women with early onset of disease had a higher O2*total as compared to those with a late onset disease. We conclude that human placenta contains a functional NAD(P)H oxidase that is highly active, which could be an important source of superoxide during pregnancy and pre-eclampsia. These data justify more detailed investigation of the role of NAD(P)H oxidase and placental oxidative stress in complicated pregnancies.

Maternal and fetal single nucleotide polymorphisms in the epoxide hydrolase and gluthatione S-transferase P1 genes are not associated with pre-eclampsia in the Coloured population of the Western Cape, South Africa.

Oxidative stress is thought to play an important role in the pathophysiology of pre-eclampsia. A defect in certain enzymes responsible for detoxification may cause prolonged exposure to reactive by-products and contribute to maternal endothelial as well as placental damage. Two polymorphisms affecting the function of the biotransformation enzymes epoxide hydrolase and glutathione S-transferase P1 were shown previously to be associated with pre-eclampsia in a Dutch population. The aim of this study was to determine if these two polymorphisms (maternal or fetal) contribute to pre-eclampsia in an anthropologically distinct population (the Western Cape region of South Africa) with a high incidence of the disease. Genomic DNA of mother - infant pairs with severe pre-eclampsia (n = 144), a population control group (n = 156) and control mother - infant pairs with uncomplicated pregnancy outcome (n = 45) were analysed for the EPHX and GSTP1 polymorphisms by polymerase chain reaction amplification and restriction enzyme digestion. Each polymorphism had a similar distribution in case and control subjects (mother and infant). The Val105/Val105 genotype of GSTP1 occurred at a higher frequency than reported for other populations. Neither maternal nor fetal EPHX Tyr113His and GSTP1 Ile105Val polymorphisms appear to contribute significantly to the pathophysiology of pre-eclampsia in the Coloured population of the Western Cape region of South Africa.

Homocysteine, cysteine, and glutathione in human colonic mucosa: elevated levels of homocysteine in patients with inflammatory bowel disease.

The present study was performed to evaluate the levels of the amino thiols cysteine, homocysteine, and glutathione in the colonic mucosa of patients with various intestinal diseases, especially chronic inflammatory bowel disease. Colonic biopsies of macroscopically normal mucosa out of a proximal and distal segment were collected from 187 patients with various intestinal diseases. Protein was assayed in duplicate by the method of Lowry et al (1951), using bovine serum albumin as standard. Total glutathione, cysteine, and homocysteine were quantified by high performance liquid chromatography (HPLC) with fluorescent detection. Only in patients with inflammatory bowel disease were the homocysteine levels in the large bowel mucosa significantly elevated compared with the concentrations in patients with normal mucosa. No significant differences were seen for glutathione and cysteine concentrations in colonic mucosa among the different groups of diseases. No correlation was found between the age of the patients and levels of the amino thiols investigated. GSH content and concentrations of cysteine and homocysteine were similar in male and female subjects. In our study markedly elevated concentrations of homocysteine in the colonic mucosa were observed in patients suffering from ulcerative colitis and Crohn's disease. This finding has been reported already in the literature for plasma homocysteine levels. Increased homocysteine levels in the colonic mucosa and plasma of patients with inflammatory bowel disease may play a role in the pathogenesis of Crohn's disease and ulcerative colitis.

Ethene and other biomarkers of oxidative stress in hypertensive disorders of pregnancy.

OBJECTIVE: An increase in reactive oxygen species (ROS) and lipid peroxides and a comprised antioxidant status has been implicated in the pathophysiology of severe preeclampsia. This study investigates whether oxidative stress and impaired antioxidant systems also contribute to milder forms of hypertensive disorders in pregnancy. Furthermore, ethene in exhaled air, a noninvasive measure for oxidative stress, was evaluated and compared with two other more established biomarkers. METHODS: Ethene in exhaled air, plasma protein carbonyls, and the ratio of free glutathione/oxidized glutathione (GSHfree/GSHox) as markers for oxidative stress as well as the antioxidants vitamins C and E, uric acid, glutathione, and the oxygen radical absorbance capacity (ORAC) in plasma were measured in 30 healthy nonpregnant, 14 normal pregnant, 9 women with pregnancy-induced hypertension (PIH), and 14 preeclamptic women. Pregnant participants were measured during pregnancy and after delivery. RESULTS: Women suffering from PIH and preeclampsia showed higher levels of the antioxidants vitamin E and uric acid, and lower levels of vitamin C compared with normal pregnant and nonpregnant women. All markers for oxidative stress were comparable between groups. Ethene levels showed a positive correlation with protein carbonyls but no correlation could be demonstrated with the free glutathione/oxidised glutathione ratio. CONCLUSIONS: PIH and preeclampsia are associated with minor alterations in antioxidant levels without signs of oxidative stress. Detection of ethene in exhaled air seems a promising noninvasive method to study lipid peroxidation but further research in more severe preeclampsia is needed.

The C242T-polymorphism of the NADPH/NADH oxidase gene p22phox subunit is not associated with pre-eclampsia.

Pre-eclampsia is a pregnancy-related multisystem disorder characterised by elevation of blood pressure and proteinuria, in which oxidative stress may play an important role. Blood pressure is partly controlled by O(-)(2) production by NADPH/NADH oxidase and recently it was shown that a C242T substitution in the p22phox gene was associated with coronary artery disease, in which elevated blood pressure and oxidative stress are also important pathophysiologic features. Therefore we studied the prevalence of the C242T polymorphism in the NADPH/NADH oxidase gene in women with pre-eclampsia and/or haemolysis, elevated liver enzymes and low platelets (HELLP) syndrome as compared with women with a normotensive pregnancy. DNA from control women (n = 78), women with pre-eclampsia (n = 40), HELLP syndrome (n = 9) or women with HELLP complicated by pregnancy-induced hypertension or pre-eclampsia (n = 46) were tested for the presence of the C242T polymorphism by polymerase chain reaction followed by restriction fragment-length polymorphism. The prevalence of the homozygous CC-genotype was similar in the patient groups compared with controls. The allele frequency of the T-allele was 31% in both control and patient groups. In conclusion the C242T polymorphism in the p22phox subunit of the NADPH/NADH oxidase gene is not associated with pre-eclampsia. Therefore, oxidative stress generated by NADPH/NADH oxidase probably does not play a role in the development of pre-eclampsia.

Glutathione S-transferases and thiol concentrations in embryonic and early fetal tissues.

BACKGROUND: Glutathione S-transferases (GSTs) are important in intracellular binding and transport of numerous compounds, and play a central role in human detoxification processes. Human GSTs mainly consist of class Pi (GSTP), Mu (GSTM), Alpha (GSTA) and Theta (GSTT) enzymes, each subdivided into one or more isoenzymes. They catalyse the conjugation of glutathione (GSH) to toxic compounds, resulting in more water-soluble and less biologically active products that may be easily excreted. The reactive -SH group in GSH is provided by cysteine, an important amino acid in GSH synthesis. METHODS: GST expression, enzyme activity and concentrations of cysteine and GSH in cytosolic fractions of organs from an embryo and a fetus at 8 and 13 weeks gestational age respectively were investigated. RESULTS: GSTP1 was predominantly present in all tissues of both the embryo and fetus. GSTA (GSTA1 + GSTA2) concentrations were moderate as compared with GSTP1, whereas GSTM1 was present in only low amounts. GSTT1 was not detected in any tissue. GST activity was highest in organs exposed directly to amniotic fluid. In all embryonic and fetal organs, considerable amounts of GSH and cysteine were detected, with higher GSH concentrations in organs where lower cysteine concentrations were demonstrated. CONCLUSIONS: These results suggest that in embryonic and early fetal development cysteine, GSH and GSTs are present in high amounts, and that GSTP1 is the most important GST isoform at these developmental stages.

Gilbert's syndrome is not associated with HELLP syndrome.

The HELLP syndrome has been associated with postpartum unconjugated hyperbilirubinaemia. Several types of disorders cause unconjugated hyperbilirubinaemia, Gilbert's syndrome being the most common. In Caucasians a genetic defect in the TATA box of the promotor region of the gene encoding for bilirubin UDP-glucuronyltransferase is tightly associated with Gilbert's syndrome. This defect was assessed by polymerase chain reaction in 237 women with the HELLP syndrome in their obstetric history and 236 controls. Fifteen percent of the cases and 10% of the controls had a homozygous genetic defect (chi2 = 2.9; P = 0.23). No evidence was found that Gilbert's syndrome is associated with the HELLP syndrome.

Hyperhomocysteinaemia: a risk factor for preeclampsia?

Preeclampsia represents one of the most frequent complications of pregnancy, however, little is known about its aetiology. Damage of the endothelial layer lining the blood vessel wall is thought to play an important role in the pathophysiology of preeclampsia, accordingly, mild hyperhomocysteinaemia has been reported to be more prevalent among preeclamptic women. Therefore, we investigated the role of hyperhomocysteinaemia in preeclampsia by measuring plasma levels of homocysteine and studying the prevalence of the 677(C-->T) polymorphism in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene, which may lead to reduced MTHFR enzyme activity and subsequently to higher plasma homocysteine levels. Plasma samples of 10 healthy non-pregnant women, 10 normotensive pregnant women, and 20 women with preeclampsia were analysed for total homocysteine levels by high performance liquid chromatography. Furthermore, 167 Dutch non-pregnant women previously hospitalised for preeclampsia and 403 population-based controls were analysed for the 677(C-->T) polymorphism by polymerase chain reaction followed by restriction fragment length polymorphism analysis (PCR/RFLP). In normotensive pregnancy homocysteine levels were lower compared with levels in healthy non-pregnant controls (8.4 versus 13.7micromol/l, P<0.001). Women with preeclampsia showed higher concentrations than women during normotensive pregnancy (13.3 versus 8.4micromol/l, P<0.02). However, levels of homocysteine in preeclampsia were comparable to those found in healthy non-pregnant women. PCR/RFLP showed no significant difference in the incidence of the 677(C-->T) polymorphism in the MTHFR gene between preeclamptic women with or without HELLP syndrome and controls (13 and 9% homozygous for the less common T-allele, respectively; OR 1.5, 95% CI 0.8-2.6, P=0.17). In contrast with previous reports, we cannot confirm that mild hyperhomocysteinaemia is a risk factor for preeclampsia. Pregnancy induced hyperhomocysteinaemia found in preeclampsia might better be explained by fluctuations in plasma volume than by the presence of the 677(C-->T) polymorphism in the MTHFR gene.

Oxidized and free whole blood thiols in preeclampsia.

OBJECTIVE: To measure levels of oxidized and free thiols in whole blood of normotensive pregnant and preeclamptic women and evaluate the role of oxidative stress. METHODS: We measured whole blood oxidized and free levels of cysteine, homocysteine, cysteinylglycine, and glutathione by high performance liquid chromatography in women with normotensive pregnancies (n = 50), preeclampsia (n = 29), and preeclampsia complicated by the hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome (n = 16). RESULTS: Oxidized and free levels (median [range], micromol/L) of cysteine and homocysteine were higher in women with preeclampsia than normotensive pregnancies (45 [27-81] versus 29 [9-91], P <.001, and 98 [57-193] versus 69 [33-215], P <.001; 0.8 [0.2-4.4] versus 0.4 [0.01-1.6], P <.001, and 2.1 [0.7-9.4] versus 1.2 [0.2-21.2], P <.01; respectively). The ratios of free to oxidized cysteine, homocysteine, and cysteinylglycine were lower in preeclampsia than normotensive pregnancy (2.2 [1.3-3.0] versus 2.4 [1.7-4.3], P <.001; 2.3 [0.5-5.4] versus 2.9 [1.1-24], P <.001; 4.1 [2.3-11.6] versus 5.4 [2.6-24.3], P <.02, respectively), indicating a shift in favor of the oxidized form of those thiols. In HELLP syndrome, levels of oxidized and free cysteine and levels of oxidized homocysteine were higher than normal (44 [33-63] versus 29 [9-91], P <.001, and 102 [82-133] versus 69 [33-215], P <.001; 1.0 [0.3-2.9] versus 0.4 [0.01-1.6], P <.001, respectively). No significant differences were found in oxidized glutathione levels in women with preeclampsia (22 [5-49] versus 17 [2- 60], P =.06) or free levels in preeclamptic women with HELLP syndrome (757 [624-993] versus 842 [539-1516], P =.09) as compared with normotensive pregnant women. The ratios of free to oxidized cysteinylglycine and glutathione were higher in women with HELLP syndrome than in those with preeclampsia (5.4 [3.3-12.7] versus 4.1 [2.3-11.6], P =.02, and 56 [28-124] versus 45 [16-166], P =.02, respectively). CONCLUSION: Significantly lower ratios of free to oxidized cysteine, homocysteine, and cysteinylglycine in preeclampsia might indicate oxidative stress.