Prevention of pre-eclampsia with low-dose aspirin or vitamins C and E in women at high or low risk: a systematic review with meta-analysis

Emerging pharmacologic interventions for pre-eclampsia treatment

INTRODUCTION

Pre-eclampsia is a serious pregnancy complication and a major global concern for the mortality of both mother and fetus. Existing symptomatic treatments do not delay disease progression; thus, timely delivery of the baby is the most effective measure. However, the risk of various maternal and fetal injuries remains.

AREAS COVERED

In this review, we summarize the potential strategies for pharmacologic interventions in pre-eclamptic therapy. Specifically, we discuss the pathophysiological process of various effective candidate therapeutics that act on potential pathways and molecular targets to inhibit key stages of the disease. We refer to this pathogenesis-focused drug discovery model as a pathogenesis-target-drug (P-T-D) strategy. Finally, we discuss the introduction of nanotechnologies to improve the safety and efficacy of therapeutics via their specific placental targeting ability and placental retention effects.

EXPERT OPINION

Despite the active development of novel pharmacological treatments based on our current knowledge of pre-eclamptic pathogenesis, investigations are still in the early phase. Thus, further exploration of the pathological mechanisms, integrated with the P-T-D strategy and novel nanosystems, could encourage the development of more effective and safer strategies. Such advances could lead to a shift from expectant management to mechanistic-based therapy for pre-eclampsia.

Melatonin treatment during chronic hypoxic gestation improves neonatal cerebrovascular function

BACKGROUND

Fetal chronic hypoxia is associated with blood flow redistribution and oxidative damage in the brain, leading to increased perinatal morbimortality. Melatonin reduces oxidative stress, improves vascular function, and has neuroprotective effects.

OBJECTIVES

This study aimed to determine the effects of an oral melatonin treatment to pregnant ewes at high-altitude, on the cerebrovascular function of their neonates.

STUDY DESIGN

Ten high-altitude pregnant sheep received either vehicle or melatonin (10 mg/d) during the last third of gestation until delivery. Postnatal daily hemodynamic measurements were recorded from lambs until 12 days old. In addition, lambs were submitted to a graded oxygenation protocol to assess cerebrovascular responses. Subsequently, lambs were euthanized, and middle cerebral arteries (MCA) were collected for vascular function, protein levels, and morphostructural analyses.

RESULTS

Antenatal treatment doubled plasma levels of melatonin in pregnant ewes. Melatonin increased carotid flow and decreased carotid vascular resistance in the lambs by the end of the first week. Furthermore, melatonin increased MCA's maximal vasoconstrictor and vasodilator responses, associated with nitric oxide-dependent and independent mechanisms.

CONCLUSIONS

An oral treatment with melatonin during pregnancy promotes postnatal cerebral perfusion in chronically hypoxic neonates. Melatonin is a potential treatment for cerebrovascular dysfunction due to perinatal chronic hypoxia.

Placenta in the Critically Ill Mother

The placenta is a temporary, multifunctional organ composed of both maternal and fetal components. It maintains homeostasis to ensure the growth of the fetus and well-being of the mother. Abnormalities in placental development have been known to be responsible for several disorders of pregnancy. Conditions coincident with pregnancy can upset the homeostasis and result in critical illness, which can greatly impact placental function and in turn affect the fetus. Decreased blood flow, acidemia, hypercarbia, and hypoxia seen in critically ill pregnant mothers can result in fetal death. Understanding the physiological changes and functioning of the maternal-fetal-placental unit will aid in better management of critically ill mothers.

How to cite this article

Taggarsi DA, Krishna B. Placenta in the Critically Ill Mother. Indian J Crit Care Med 2021;25(Suppl 3):S200-S205.

Effects of prenatal micronutrients supplementation timing on pregnancy-induced hypertension: Secondary analysis of a double-blind randomized controlled trial

In this secondary analysis of data from a double‐blind randomized controlled trial (clinicaltrials.gov identifier: NCT00133744) of micronutrient supplementation (multiple micronutrients [MMN], iron–folic acid [IFA] and folic acid [FA] alone), we examined the potential modifying effect of gestational age at enrolment on the association of antenatal supplementation and pregnancy‐induced hypertension (PIH). We included 18,775 nulliparous pregnant women with mild or no anaemia who were enrolled at 20 weeks of gestation or earlier from five counties of northern China. Women were randomly assigned to receive daily FA, IFA or MMN from enrolment until delivery. We used logistic regression to evaluate the association between PIH and timing of micronutrient supplementation. The incidence of PIH was statistically significantly lower among women who began MMN supplementation before 12 gestational weeks compared with women who began MMN supplementation at 12 weeks or later (RR = 0.74, 95% CI: 0.60–0.91). A similar protective effect was observed for both early‐onset (<28 weeks, RR 0.45, 0.21–0.96) and late‐onset of PIH (≥28 weeks, RR 0.77, 0.63–0.96). No statistically significant association was observed between PIH occurrence and timing of supplementation for FA or IFA. Maternal MMN supplementation and antenatal enrolment during the first trimester of pregnancy appeared to be of importance in preventing both early‐ and late‐onset of PIH.

Effects of Maternal Nutritional Supplements and Dietary Interventions on Placental Complications: An Umbrella Review, Meta-Analysis and Evidence Map

The placenta is a vital, multi-functional organ that acts as an interface between maternal and fetal circulation during pregnancy. Nutritional deficiencies during pregnancy alter placental development and function, leading to adverse pregnancy outcomes, such as pre-eclampsia, infants with small for gestational age and low birthweight, preterm birth, stillbirths and maternal mortality. Maternal nutritional supplementation may help to mitigate the risks, but the evidence base is difficult to navigate. The primary purpose of this umbrella review is to map the evidence on the effects of maternal nutritional supplements and dietary interventions on pregnancy outcomes related to placental disorders and maternal mortality. A systematic search was performed on seven electronic databases, the PROSPERO register and references lists of identified papers. The results were screened in a three-stage process based on title, abstract and full-text by two independent reviewers. Randomized controlled trial meta-analyses on the efficacy of maternal nutritional supplements or dietary interventions were included. There were 91 meta-analyses included, covering 23 types of supplements and three types of dietary interventions. We found evidence that supports supplementary vitamin D and/or calcium, omega-3, multiple micronutrients, lipid-based nutrients, and balanced protein energy in reducing the risks of adverse maternal and fetal health outcomes. However, these findings are limited by poor quality of evidence. Nutrient combinations show promise and support a paradigm shift to maternal dietary balance, rather than single micronutrient deficiencies, to improve maternal and fetal health. The review is registered at PROSPERO (CRD42020160887).

Role of Palm Oil Vitamin E in Preventing Pre-eclampsia: A Secondary Analysis of a Randomized Clinical Trial Following ISSHP Reclassification

Background: Preeclampsia is a significant cause of maternal and perinatal mortality worldwide. Oxidative stress plays a key role in its pathophysiology, hence antioxidants such as tocotrienol may be preventive against preeclampsia. In 2018, the ISSHP revised the definition of preeclampsia. In accordance with the new definition, we report a secondary data analysis from a clinical trial comparing palm oil vitamin E in the form of tocotrienol-rich fraction (TRF) against placebo, in preventing preeclampsia.

Method: A randomized double-blind controlled trial was conducted in 2002–2005 to assess the benefits of TRF in preeclampsia prevention. A total of 299 primigravidae were recruited. The intervention group was supplemented with TRF 100 mg daily in super-olein capsules, whereas the placebo group was prescribed super-olein capsules without TRF, beginning from 12 to 16 gestational weeks until delivery. The primary outcome measure was incidence of preeclampsia.

Results: The total incidence of pregnancy induced hypertension (PIH) was 5%, whereas the incidence of preeclampsia was 2.3%. The odds of developing PIH (adjusted OR 0.254; 95% CI: 0.07–0.93; p–value 0.038) and preeclampsia (adjusted OR 0.030; 95% CI: 0.001–0.65; p-value 0.025) were significantly lower in the TRF arm compared to the placebo arm.

Conclusion: Antenatal supplementation with palm oil vitamin E in the form of TRF is associated with significant reductions in the incidence of preeclampsia and PIH in a single urban tertiary hospital. Palm oil vitamin E deserves further scrutiny as a potential public health preventive measure against preeclampsia and PIH.

Novel Insights into the Regulatory Role of Nuclear Factor (Erythroid-Derived 2)-Like 2 in Oxidative Stress and Inflammation of Human Fetal Membranes

Fetal membrane dysfunction in response to oxidative stress (OS) is associated with adverse pregnancy outcomes. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is one of the regulators of innate OS response. This study evaluated changes in Nrf2 expression and its downstream targets heme oxygenase (HO-1) and peroxisome proliferator-activated receptor gamma (PPARγ) in fetal membranes during OS and infection in vitro. Furthermore, we tested the roles of sulforaphane (SFN; an extract from cruciferous vegetables) and trigonelline (TRN; an aromatic compound in coffee) in regulating Nrf2 and its targets. Fetal membranes (n = 6) collected at term were placed in an organ explant system were treated with water-soluble cigarette smoke extract (CSE), an OS inducer (1:10), and lipopolysaccharide (LPS; 100 ng/mL). Nrf2 expression, expression, its enhancement by sulforaphane (SFN, 10 µM/mL) and down regulation by TRN (10uM/mL) was determined by western blots. Expression of Nrf2 response elements PPARγ (western) heme oxygenase (HO-1), and IL-6 were quantified by ELISA. CSE and LPS treatment of fetal membranes increased nrf2, but reduced HO-1 and PPARγ and increased IL-6. Co-treatment of SFN, but not with TRN, with CSE and LPS increased Nrf2 substantially, as well as increased HO-1 and PPARγ and reduced IL-6 expression. Risk factor-induced Nrf2 increase is insufficient to generate an antioxidant response in fetal membranes. Sulforaphane may enhance innate antioxidant and anti-inflammatory capacity by increasing NRF-2 expression.

Prophylactic aspirin for preventing pre-eclampsia and its complications: An overview of meta-analyses

Benefits of aspirin administration on pre-eclampsia and IUGR depend on the gestational age and dose of aspirin administration. Meta-analyses show that, to prevent preterm labor, aspirin could be administrated even after 16 weeks of gestational age.

Impact of low-dose aspirin on adverse perinatal outcome: meta-analysis and meta-regression

OBJECTIVE

To perform a meta-analysis and meta-regression of randomized controlled trials (RCTs) to evaluate the impact of low-dose aspirin (LDA) on perinatal outcome, independent of its effect on pre-eclampsia (PE), preterm birth and low birth weight.

METHODS

An electronic search of EMBASE, PubMed, CENTRAL, PROSPERO and Google Scholar databases was performed to identify RCTs assessing the impact of LDA in pregnancy, published in English prior to May 2019, which reported perinatal outcomes of interest (placental abruption, delivery mode, low 5-min Apgar score, neonatal acidosis, neonatal intensive care unit admission, periventricular hemorrhage and perinatal death). Risk ratios (RR) and 95% CI were calculated and pooled for analysis. Analysis was stratified according to gestational age at commencement of treatment (≤ 16 weeks vs > 16 weeks) and subgroup analysis was performed to assess the impact of aspirin dose (< 100 mg vs ≥ 100 mg). Meta-regression was used to assess the impact of LDA on perinatal outcome, independent of the reduction in PE, preterm birth and low birth weight.

RESULTS

Forty studies involving 34 807 participants were included. When LDA was commenced ≤ 16 weeks' gestation, it was associated with a significant reduction in the risk of perinatal death (RR, 0.47; 95% CI, 0.25-0.88; P = 0.02; number needed to treat, 92); however, this risk reduction was only seen when a daily dose of ≥ 100 mg was administered. If commenced > 16 weeks' gestation, LDA was associated with a significant reduction in 5-min Apgar score < 7 (RR, 0.75; 95% CI, 0.58-0.96; P = 0.02) and periventricular hemorrhage (RR, 0.68; 95% CI, 0.47-0.99; P = 0.04), but a trend towards an increase in the risk of placental abruption (RR, 1.20; 95% CI, 1.00-1.46; P = 0.06) was also noted. LDA was not associated with any significant increase in adverse events if commenced ≤ 16 weeks gestation. LDA had no effect on delivery mode, irrespective of the gestational age at which it was started. Meta-regression confirmed that the effect of LDA on perinatal death, when treatment was started ≤ 16 weeks' gestation, was independent of any reduction in the rate of PE and preterm birth.

CONCLUSION

LDA improves some important perinatal outcomes, without increasing adverse events such as placental abruption or periventricular hemorrhage, and its utility, if commenced prior to 16 weeks' gestation, may be considered in a wider context beyond the prevention of PE or fetal growth restriction. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Antiplatelet agents for preventing pre-eclampsia and its complications

BACKGROUND

Pre-eclampsia is associated with deficient intravascular production of prostacyclin, a vasodilator, and excessive production of thromboxane, a vasoconstrictor and stimulant of platelet aggregation. These observations led to the hypotheses that antiplatelet agents, low-dose aspirin in particular, might prevent or delay development of pre-eclampsia.

OBJECTIVES

To assess the effectiveness and safety of antiplatelet agents, such as aspirin and dipyridamole, when given to women at risk of developing pre-eclampsia.

SEARCH METHODS

For this update, we searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (30 March 2018), and reference lists of retrieved studies. We updated the search in September 2019 and added the results to the awaiting classification section of the review.

SELECTION CRITERIA

All randomised trials comparing antiplatelet agents with either placebo or no antiplatelet agent were included. Studies only published in abstract format were eligible for inclusion if sufficient information was available. We would have included cluster-randomised trials in the analyses along with individually-randomised trials, if any had been identified in our search strategy. Quasi-random studies were excluded. Participants were pregnant women at risk of developing pre-eclampsia. Interventions were administration of an antiplatelet agent (such as low-dose aspirin or dipyridamole), comparisons were either placebo or no antiplatelet.

DATA COLLECTION AND ANALYSIS

Two review authors assessed trials for inclusion and extracted data independently. For binary outcomes, we calculated risk ratio (RR) and its 95% confidence interval (CI), on an intention-to-treat basis. For this update we incorporated individual participant data (IPD) from trials with this available, alongside aggregate data (AD) from trials where it was not, in order to enable reliable subgroup analyses and inclusion of two key new outcomes. We assessed risk of bias for included studies and created a 'Summary of findings' table using GRADE.

MAIN RESULTS

Seventy-seven trials (40,249 women, and their babies) were included, although three trials (relating to 233 women) did not contribute data to the meta-analysis. Nine of the trials contributing data were large (> 1000 women recruited), accounting for 80% of women recruited. Although the trials took place in a wide range of countries, all of the nine large trials involved only women in high-income and/or upper middle-income countries. IPD were available for 36 trials (34,514 women), including all but one of the large trials. Low-dose aspirin alone was the intervention in all the large trials, and most trials overall. Dose in the large trials was 50 mg (1 trial, 1106 women), 60 mg (5 trials, 22,322 women), 75mg (1 trial, 3697 women) 100 mg (1 trial, 3294 women) and 150 mg (1 trial, 1776 women). Most studies were either low risk of bias or unclear risk of bias; and the large trials were all low risk of bas. Antiplatelet agents versus placebo/no treatment The use of antiplatelet agents reduced the risk of proteinuric pre-eclampsia by 18% (36,716 women, 60 trials, RR 0.82, 95% CI 0.77 to 0.88; high-quality evidence), number needed to treat for one women to benefit (NNTB) 61 (95% CI 45 to 92). There was a small (9%) reduction in the RR for preterm birth <37 weeks (35,212 women, 47 trials; RR 0.91, 95% CI 0.87 to 0.95, high-quality evidence), NNTB 61 (95% CI 42 to 114), and a 14% reduction infetal deaths, neonatal deaths or death before hospital discharge (35,391 babies, 52 trials; RR 0.85, 95% CI 0.76 to 0.95; high-quality evidence), NNTB 197 (95% CI 115 to 681). Antiplatelet agents slightly reduced the risk of small-for-gestational age babies (35,761 babies, 50 trials; RR 0.84, 95% CI 0.76 to 0.92; high-quality evidence), NNTB 146 (95% CI 90 to 386), and pregnancies with serious adverse outcome (a composite outcome including maternal death, baby death, pre-eclampsia, small-for-gestational age, and preterm birth) (RR 0.90, 95% CI 0.85 to 0.96; 17,382 women; 13 trials, high-quality evidence), NNTB 54 (95% CI 34 to 132). Antiplatelet agents probably slightly increase postpartum haemorrhage > 500 mL (23,769 women, 19 trials; RR 1.06, 95% CI 1.00 to 1.12; moderate-quality evidence due to clinical heterogeneity), and they probably marginally increase the risk of placental abruption, although for this outcome the evidence was downgraded due to a wide confidence interval including the possibility of no effect (30,775 women; 29 trials; RR 1.21, 95% CI 0.95 to 1.54; moderate-quality evidence). Data from two large trials which assessed children at aged 18 months (including results from over 5000 children), did not identify clear differences in development between the two groups.

AUTHORS' CONCLUSIONS

Administering low-dose aspirin to pregnant women led to small-to-moderate benefits, including reductions in pre-eclampsia (16 fewer per 1000 women treated), preterm birth (16 fewer per 1000 treated), the baby being born small-for-gestational age (seven fewer per 1000 treated) and fetal or neonatal death (five fewer per 1000 treated). Overall, administering antiplatelet agents to 1000 women led to 20 fewer pregnancies with serious adverse outcomes. The quality of evidence for all these outcomes was high. Aspirin probably slightly increased the risk of postpartum haemorrhage of more than 500 mL, however, the quality of evidence for this outcome was downgraded to moderate, due to concerns of clinical heterogeneity in measurements of blood loss. Antiplatelet agents probably marginally increase placental abruption, but the quality of the evidence was downgraded to moderate due to low event numbers and thus wide 95% CI. Overall, antiplatelet agents improved outcomes, and at these doses appear to be safe. Identifying women who are most likely to respond to low-dose aspirin would improve targeting of treatment. As almost all the women in this review were recruited to the trials after 12 weeks' gestation, it is unclear whether starting treatment before 12 weeks' would have additional benefits without any increase in adverse effects. While there was some indication that higher doses of aspirin would be more effective, further studies would be warranted to examine this.

Oral antioxidant therapy for prevention and treatment of preeclampsia: Meta-analysis of randomized controlled trials

AIMS

To determine whether oral antioxidant therapies, of various types and doses, are able to prevent or treat women with preeclampsia.

DATA SYNTHESIS

The following databases were searched: MEDLINE, CENTRAL, LILACS, and Web of Science. Inclusion criteria were: a) randomized clinical trials; b) oral antioxidant supplementation; c) study in pregnant women; d) control group, treated or not with placebo. Papers were excluded if they evaluated antioxidant nutrient supplementation associated with other non-antioxidant therapies. Data were extracted and the risk of bias of each study was assessed. Heterogeneity was analyzed using the Cochran Q test, and I2 statistics and pre-specified sensitivity analyses were performed. Meta-analyses were conducted on prevention and treatment studies, separately. The primary outcome was the incidence of preeclampsia in prevention trials, and of perinatal death in treatment trials. Twenty-nine studies were included in the analysis, 19 for prevention and 10 for treatment. The antioxidants used in these studies were vitamins C and E, selenium, l-arginine, allicin, lycopene and coenzyme Q10, none of which showed beneficial effects on the prevention of preeclampsia (RR: 0.89, CI 95%: [0.79-1.02], P = 0.09; I² = 39%, P = 0.04) and other outcomes. The antioxidants used in the treatment studies were vitamins C and E, N-acetylcysteine, l-arginine, and resveratrol. A beneficial effect was found in intrauterine growth restriction.

CONCLUSIONS

Antioxidant therapy had no effects in the prevention of preeclampsia but did show beneficial effects in intrauterine growth restriction, when used in the treatment of this condition.

Antioxidative effects of flavonoids and their metabolites against hypoxia/reoxygenation-induced oxidative stress in a human first trimester trophoblast cell line

This study aimed to investigate the cytoprotective effects of flavonoids, their metabolites alone or in combination against hypoxia/reoxygenation induced oxidative stress in the transformed human first trimester trophoblast cell line (HTR-8/SVneo). Oxidative stress was achieved with hypoxia followed by reoxygenation and the following assays were performed: MTT, CellTox™ Green Cytotoxicity, CellTiter-Glo®, NADP/NADPH-Glo™, ROS-Glo™/H₂O₂, GSH/GSSG-Glo™ and Caspase-Glo® 3/7 assays. HTR-8/SVneo cells, pre-treated for 24 h with flavonoids or their metabolites were protected significantly from oxidative stress. Flavonoids were associated with ROS modulation, reducing the generation of superoxide/hydrogen peroxide. The activities of caspases 3/7 were also significantly reduced significantly in HTR-8/SVneo cells pre-treated with flavonoids. This study has shown for the first time that 24 h pre-treatment with flavonoids, their metabolites alone or in combination, protected against HR-induced oxidative stress in the trophoblast cell line. These data indicate that dietary flavonoids may be beneficial to placental health and invasion during early gestation.

Nitric oxide and the biology of pregnancy

Nitric oxide (NO) is a key regulator of both maternal and fetal homeostasis during pregnancy, facilitating the maternal cardio-vascular changes, fetal development and growth and adaptation to extrauterine life. Dysfunction of the NO system during pregnancy is associated to placental and vascular-related diseases such as hypertensive disorders of pregnancy (HDP) and intrauterine growth restriction (IUGR). Emerging therapeutic strategies involving NO precursors, NO donors, natural derivatives or pharmacological modulators of the NO system seem hold promise for the treatment of such conditions of pregnancy.

Oxidative stress and endothelial function in normal pregnancy versus pre-eclampsia, a combined longitudinal and case control study

Background

Pre-eclampsia (PE) is related to an impaired endothelial function. Endothelial dysfunction accounts for altered vascular reactivity, activation of the coagulation cascade and loss of vascular integrity. Impaired endothelial function originates from production of inflammatory and cytotoxic factors by the ischemic placenta and results in systemic oxidative stress (OS) and an altered bioavailability of nitric oxide (•NO). The free radical •NO, is an endogenous endothelium-derived relaxing factor influencing endothelial function. In placental circulation, endothelial release of •NO dilates the fetal placental vascular bed, ensuring feto-maternal exchange. The Endopreg study was designed to evaluate in vivo endothelial function and to quantify in vitro OS in normal and pre-eclamptic pregnancies.

Methods/design

The study is divided into two arms, a prospective longitudinal study and a matched case control study. In the longitudinal study, pregnant patients ≥18 years old with a singleton pregnancy will be followed throughout pregnancy and until 6 months post-partum. In the case control study, cases with PE will be compared to matched normotensive pregnant women. Maternal blood concentration of superoxide (O₂•) and placental concentration of •NO will be determined using EPR (electron paramagnetic resonance). Endothelial function and arterial stiffness will be evaluated using respectively Peripheral Arterial Tonometry (PAT), Flow-Mediated Dilatation (FMD) and applanation tonometry. Placental expression of eNOS (endothelial NOS) will be determined using immune-histochemical staining. Target recruitment will be 110 patients for the longitudinal study and 90 patients in the case-control study.

Discussion

The results of Endopreg will provide longitudinal information on in vivo endothelial function and in vitro OS during normal pregnancy and PE. Adoption of these vascular tests in clinical practice potentially predicts patients at risk to develop cardiovascular events later in life after PE pregnancies. •NO, O₂•⁻ and eNOS measurements provide further inside in the pathophysiology of PE.

Trial registration

This trial has been registered on clinicaltrials.gov. ClinicalTrials.gov Identifier: NCT02603913. Registered October 2015.

Micronutrient supplementation during pregnancy and the risk of pregnancy-induced hypertension: A randomized clinical trial

BACKGROUND & AIMS

Increasing evidence suggests that iron-containing multiple micronutrient may reduce the risk of pregnancy-induced hypertension including gestational hypertension or preeclampsia. We aimed to examine whether 30 mg iron plus folic acid or multiple micronutrients during pregnancy reduces the risk of pregnancy-induced hypertension.

METHODS

We conducted a secondary data analysis by the dataset from a double-blind randomized controlled trial in China from 2006 to 2009 that was conducted to investigate the effects of multiple micronutrient supplements on adverse pregnancy outcomes when provided to pregnant women with no/mild anemia. We used logistic regression to estimate the adjusted odds ratio and 95% confidence interval and test for effect modification.

RESULTS

The incidence of pregnancy-induced hypertension was 7.1% (423/5923), 6.3% (374/5933) and 6.3% (372/5914) among the pregnant women who took folic acid only, iron-folic acid and multiple micronutrient supplements, respectively. The adjusted odds ratios associated with iron-folic acid supplements and multiple micronutrient supplements for pregnancy-induced hypertension were both nearly 0.88 (95% confidence interval, 0.76-1.02), compared with folic acid supplements only. Among pregnant women aged 20-24 years, iron-folic acid (adjusted odds ratios: 0.81, 95% confidence interval: 0.67-0.96) or multiple micronutrient supplementation (adjusted odds ratios: 0.83, 95% confidence interval: 0.70-0.99) can significantly reduce the risk of pregnancy-induced hypertension compared to folic acid supplementation.

CONCLUSIONS

Overall, there were no significant differences in pregnancy-induced hypertension across supplement groups. However, among pregnant women aged 20-24 years, iron-containing multiple micronutrient supplementation was associated with a reduced risk of pregnancy-induced hypertension compared with folic acid supplements only.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00133744.

The Raine study had no evidence of significant perinatal selection bias after two decades of follow up: a longitudinal pregnancy cohort study

BACKGROUND

Cohort studies may increase or decrease their selection bias as they progress through time. The Western Australian Pregnancy Cohort (Raine) Study has followed 2868 children for over two decades; from fetal into adult life. This paper analyses the cohort over time, assessing potential bias that may come and go with recruitment, retention and loss of participants.

METHODS

Linked data from all births in Western Australian over the 3 years the Raine Cohort was recruited were obtained to compare perinatal characteristics and subsequent health outcomes between the Western Australian (WA) contemporaneous birth population and the Raine Cohort at five time points. Perinatal exposure-outcome comparisons were employed to assess bias due to non-participation in Raine Study subsets.

RESULTS

There were demographic differences between the Raine Study cohort and its source population at recruitment with further changes across the period of follow up. Despite these differences, the pregnancy and infant data of those with continuing participation were not significantly different to the WA contemporaneous birth population. None of the exposure-outcome associations were significantly different to those in the WA general population at recruitment or at any cohort reviews suggesting no substantial recruitment or attrition bias.

CONCLUSIONS

The Raine Study is valuable for association studies, even after 20 years of cohort reviews with increasing non-participation of cohort members. Non-participation has resulted in greater attrition of socially disadvantaged participants, however, exposure-outcome association analyses suggest that there is no apparent resulting selection bias.

Effect of a small dose of aspirin on quantitative test of 24-h urinary protein in patients with hypertension in pregnancy

The aim of the present study was to determine the effect of a small dose of aspirin on a quantitative test of 24-h urinary protein in patients with hypertension in pregnancy. In total, 224 patients with hypertension in pregnancy were continuously selected and were randomly divided into the control group (50 cases with conventional therapy), aspirin 50 mg/day group (60 cases), aspirin 75 mg/day group (58 cases), and aspirin 100 mg/day group (56 cases). Clinical effects were compared from 16 gestational weeks to childbirth. According to the comparison in the four groups, there was no statistical difference in the mean arterial pressure, pre-eclampsia rate, gestational weeks, and caesarean section rate (p>0.05). The 24-h urinary protein and endothelin-1 (ET-1) level were significantly decreased following treatment, and were less than the control and 50 mg/day groups. The superoxide dismutase (SOD) level was significantly increased, and higher than the control and 50 mg/day groups. In terms of the 75 and 100 mg/day, control and 50 mg/day groups, there was no statistical difference (p>0.05). A comparison of the complication rate in the four groups of fetuses during the perinatal period, no statistical difference was observed (p>0.05). Thus, the results show that, regarding patients with hypertension in pregnancy, 75 mg/day aspirin can decrease the 24-h urinary protein, SOD, and ET-1 level. However, the results remain to be confirmed to improve maternal and infant outcome in delivery.

Adrenomedullin2 (ADM2)/Intermedin (IMD): A Potential Role in the Pathophysiology of Preeclampsia

CONTEXT

It is not known whether decreases in trophoblast invasion promoting the peptide, adrenomedullin2 (ADM2) system is associated with preeclampsia (PreE).

OBJECTIVE

The objective of the study was to assess the changes in ADM2 levels in plasma, placenta, and amniotic fluid (AF) and its receptor components in placenta from PreE pregnancy compared with the age-matched normal and study the effect of ADM2 on the synthesis of nitric oxide (NO), endothelial nitric oxide synthase (eNOS), and matrix-metalloproteinase (MMP)-2 and MMP-9 in trophoblast cells.

RESULTS

PreE is associated with a decreased expression of ADM2 in plasma and placenta (P < .05); ADM2 interacts with a seven-transmembrane G protein-coupled receptor, calcitonin receptor-like receptor (CRLR) in HTR-8/SVneo cells; placental expression of ADM2/CRLR complex is lower in PreE; mRNA for CRLR and receptor activity-modifying protein-3 are lower, whereas receptor activity-modifying protein-2 is higher in the PreE placenta (P < .05); ADM2 levels in the second trimester are lower in the AF from pregnant women who develop PreE later in gestation (P < .05); ADM2 is localized to the epithelium of the amnion and the ectoderm and mesoderm of the chorion in term fetal membranes; ADM2 increases NO production, eNOS, and MMP2/9-immunoreactivity, whereas ADM2 knockdown inhibits the expression of eNOS and MMP2/9 mRNA and S-nitrosylation in HTR-8/SVneo cells; and ADM2-induced increases in MMP2/9 activity is inhibited by L-nitro-arginine methyl ester in HTR-8SV/neo cells.

CONCLUSION

Decreases in the ADM2 system in PreE at term, in AF from pregnant women during the second trimester who develop PreE later in gestation, and ADM2-induced increases in the NO and MMP-2/9 levels in trophoblast cells suggest a potential role for ADM2 via the NO-MMP system in the pathophysiology of PreE.

Vitamin C: the known and the unknown and Goldilocks

Vitamin C (Ascorbic Acid), the antiscorbutic vitamin, cannot be synthesized by humans and other primates, and has to be obtained from diet. Ascorbic acid is an electron donor and acts as a cofactor for fifteen mammalian enzymes. Two sodium-dependent transporters are specific for ascorbic acid, and its oxidation product dehydroascorbic acid is transported by glucose transporters. Ascorbic acid is differentially accumulated by most tissues and body fluids. Plasma and tissue vitamin C concentrations are dependent on amount consumed, bioavailability, renal excretion, and utilization. To be biologically meaningful or to be clinically relevant, in vitro and in vivo studies of vitamin C actions have to take into account physiologic concentrations of the vitamin. In this paper, we review vitamin C physiology; the many phenomena involving vitamin C where new knowledge has accrued or where understanding remains limited; raise questions about the vitamin that remain to be answered; and explore lines of investigations that are likely to be fruitful.

In Utero Origins of Hypertension: Mechanisms and Targets for Therapy

The developmental origins of health and disease theory is based on evidence that a suboptimal environment during fetal and neonatal development can significantly impact the evolution of adult-onset disease. Abundant evidence exists that a compromised prenatal (and early postnatal) environment leads to an increased risk of hypertension later in life. Hypertension is a silent, chronic, and progressive disease defined by elevated blood pressure (>140/90 mmHg) and is strongly correlated with cardiovascular morbidity/mortality. The pathophysiological mechanisms, however, are complex and poorly understood, and hypertension continues to be one of the most resilient health problems in modern society. Research into the programming of hypertension has proposed pharmacological treatment strategies to reverse and/or prevent disease. In addition, modifications to the lifestyle of pregnant women might impart far-reaching benefits to the health of their children. As more information is discovered, more successful management of hypertension can be expected to follow; however, while pregnancy complications such as fetal growth restriction, preeclampsia, preterm birth, etc., continue to occur, their offspring will be at increased risk for hypertension. This article reviews the current knowledge surrounding the developmental origins of hypertension, with a focus on mechanistic pathways and targets for therapeutic and pharmacologic interventions.

Unravelling the theories of pre-eclampsia: are the protective pathways the new paradigm?

Pre-eclampsia is a vascular disorder of pregnancy where anti-angiogenic factors, systemic inflammation and oxidative stress predominate, but none can claim to cause pre-eclampsia. This review provides an alternative to the ‘two-stage model’ of pre-eclampsia in which abnormal spiral arteries modification leads to placental hypoxia, oxidative stress and aberrant maternal systemic inflammation. Very high maternal soluble fms-like tyrosine kinase-1 (sFlt-1 also known as sVEGFR) and very low placenta growth factor (PlGF) are unique to pre-eclampsia; however, abnormal spiral arteries and excessive inflammation are also prevalent in other placental disorders. Metaphorically speaking, pregnancy can be viewed as a car with an accelerator and brakes, where inflammation, oxidative stress and an imbalance in the angiogenic milieu act as the ‘accelerator’. The ‘braking system’ includes the protective pathways of haem oxygenase 1 (also referred as Hmox1 or HO-1) and cystathionine-γ-lyase (also known as CSE or Cth), which generate carbon monoxide (CO) and hydrogen sulphide (H₂S) respectively. The failure in these pathways (brakes) results in the pregnancy going out of control and the system crashing. Put simply, pre-eclampsia is an accelerator–brake defect disorder. CO and H₂S hold great promise because of their unique ability to suppress the anti-angiogenic factors sFlt-1 and soluble endoglin as well as to promote PlGF and endothelial NOS activity. The key to finding a cure lies in the identification of cheap, safe and effective drugs that induce the braking system to keep the pregnancy vehicle on track past the finishing line.

A Dormant Microbial Component in the Development of Preeclampsia

Preeclampsia (PE) is a complex, multisystem disorder that remains a leading cause of morbidity and mortality in pregnancy. Four main classes of dysregulation accompany PE and are widely considered to contribute to its severity. These are abnormal trophoblast invasion of the placenta, anti-angiogenic responses, oxidative stress, and inflammation. What is lacking, however, is an explanation of how these themselves are caused. We here develop the unifying idea, and the considerable evidence for it, that the originating cause of PE (and of the four classes of dysregulation) is, in fact, microbial infection, that most such microbes are dormant and hence resist detection by conventional (replication-dependent) microbiology, and that by occasional resuscitation and growth it is they that are responsible for all the observable sequelae, including the continuing, chronic inflammation. In particular, bacterial products such as lipopolysaccharide (LPS), also known as endotoxin, are well known as highly inflammagenic and stimulate an innate (and possibly trained) immune response that exacerbates the inflammation further. The known need of microbes for free iron can explain the iron dysregulation that accompanies PE. We describe the main routes of infection (gut, oral, and urinary tract infection) and the regularly observed presence of microbes in placental and other tissues in PE. Every known proteomic biomarker of "preeclampsia" that we assessed has, in fact, also been shown to be raised in response to infection. An infectious component to PE fulfills the Bradford Hill criteria for ascribing a disease to an environmental cause and suggests a number of treatments, some of which have, in fact, been shown to be successful. PE was classically referred to as endotoxemia or toxemia of pregnancy, and it is ironic that it seems that LPS and other microbial endotoxins really are involved. Overall, the recognition of an infectious component in the etiology of PE mirrors that for ulcers and other diseases that were previously considered to lack one.

A review of the literature regarding nutritional supplements and their effect on vaginal flora and preterm birth

PURPOSE OF REVIEW

The aim of this review was to evaluate recently published review articles which examine the use of nutritional supplements to prevent preterm birth (PTB) by modifying vaginal bacteria.

RECENT FINDINGS

Probiotics, vitamin D and vitamin C were all identified as nutritional supplements that have the potential to alter bacterial flora and consequently reduce PTB and treat or prevent genital infections. Evidence shows that probiotics may reduce the incidence of PTB as well as being effective at treating bacterial vaginosis, a known cause for PTB. Low vitamin D levels may be associated with bacterial vaginosis, although no evidence was identified which demonstrated that vitamin D supplementation reduced the risk of having bacterial vaginosis or PTB.There is little evidence regarding vitamin C supplementation, although it does suggest a possible benefit with regard to preterm rupture of membranes; however, this did not appear to reduce rates of PTB.

SUMMARY

Although there is evidence that taking probiotics in pregnancy may reduce the incidence of PTB, it is mainly derived from small, poor quality studies. Vitamin D and vitamin C may have potential benefits, but these remain to be proven. Large randomized controlled trials are needed to more accurately evaluate the potential benefits of these low-cost interventions for reducing PTB and its consequences.

Sleep-disordered breathing and future cardiovascular disease risk

Sleep-disordered breathing occurs in 0.6-15% of reproductive age women. This condition is associated with an increased lifetime risk of cardiovascular disease, cardiovascular mortality, and all-cause mortality. A substantial body of evidence demonstrated increased perinatal morbidity among pregnancies affected by SDB including gestational diabetes, gestational hypertension, and preeclampsia. These same conditions are predictive of later cardiovascular disease. Treatment of SDB has been demonstrated to decrease future cardiovascular events and mortality. Screening at-risk individuals in the perinatal period can identify women with SDB, who can benefit from treatment. Continuous positive airway pressure and lifestyle interventions can decrease subsequent adverse cardiovascular health outcomes.

Oxidative stress damage as a detrimental factor in preterm birth pathology

Normal term and spontaneous preterm births (PTB) are documented to be associated with oxidative stress (OS), and imbalances in the redox system (balance between pro- and antioxidant) have been reported in the maternal-fetal intrauterine compartments. The exact mechanism of labor initiation either at term or preterm by OS is still unclear, and this lack of understanding can partially be blamed for failure of antioxidant supplementation trials in PTB prevention. Based on recent findings from our laboratory, we postulate heterogeneity in host OS response. The physiologic (at term) and pathophysiologic (preterm) pathways of labor are not mediated by OS alone but by OS-induced damage to intrauterine tissues, especially fetal membranes of the placenta. OS damage affects all major cellular elements in the fetal cells, and this damage promotes fetal cell senescence (aging). The aging of the fetal cells is predominated by p38 mitogen activated kinase (p38MAPK) pathways. Senescing cells generate biomolecular signals that are uterotonic, triggering labor process. The aging of fetal cells is normal at term. However, aging is premature in PTB, especially in those PTBs complicated by preterm premature rupture of the membranes, where elements of redox imbalances and OS damage are more dominant. We postulate that fetal cell senescence signals generated by OS damage are likely triggers for labor. This review highlights the mechanisms involved in senescence development at term and preterm by OS damage and provides insight into novel fetal signals of labor initiation pathways.

[Hypertension and pregnancy in Lome (sub-Saharan Africa): epidemiology, diagnosis and risk factors]

AIM

Describe the epidemiology, diagnosis and risk factors of hypertension in pregnant women in Lome.

METHODS

It was a prospective, descriptive and comparative study during 12 months (October 1st, 2011 to September 31st, 2012) on 200 cases of hypertension among 1620 pregnant women, in the department of gynecology and obstetrics at the Tokoin teaching hospital of Lome.

RESULTS

We had 200 cases of hypertension on 1620 pregnant women. The prevalence of hypertension in pregnant women in Lome was 12.3%. The average age of pregnant women was 30±7 years, with extremes of 15 and 44 years. Hypertension was more common (50%) in ages of 30-39 years. The society the most represented were housewives (33.33%), civil servants (16.67%) and traders (16.66%). Hypertension was found incidentally or during a complication especially during the third trimester of pregnancy. Preeclampsia (44%) and pregnancy-induced hypertension (33%) were the most represented. The main risk factors where primiparity (especially older primipars >30ans), nulliparity, familial history of hypertension, low economic level, history of pregnancy-induced hypertension, age >30 years, twinning, obesity and stress.

CONCLUSION

Hypertension in pregnancy is frequent in Lome. A regular follow-up before and after delivery is important according to fetal and maternal complications, and the risk of heart and kidney disease at mild and long outcome.

Does vitamin C deficiency increase lifestyle-associated vascular disease progression? Evidence based on experimental and clinical studies

SIGNIFICANCE

Despite continuous advances in the prevention of cardiovascular disease (CVD), critical issues associated with an unhealthy lifestyle remain an increasing cause of morbidity and mortality in industrialized countries.

RECENT ADVANCES

A growing body of literature supports a specific role for vitamin C in a number of reactions that are associated with vascular function and control including, for example, nitric oxide bioavailability, lipid metabolism, and vascular integrity.

CRITICAL ISSUES

A large body of epidemiological evidence supports a relationship between poor vitamin C status and increased risk of developing CVD, and the prevalence of deficiency continues to be around 10%-20% of the general Western population although this problem could easily and cheaply be solved by supplementation. However, large intervention studies using vitamin C have not found a beneficial effect of supplementation. This review outlines the proposed mechanism by which vitamin C deficiency worsens CVD progression. In addition, it discusses problems with the currently available literature, including the discrepancies between the large intervention studies and the experimental and epidemiological literature.

FUTURE DIRECTIONS

Increased insights into vitamin C deficiency-mediated CVD progression will enable the design of future randomized controlled trials that are better suited to test the efficacy of vitamin C in disease prevention as well as the identification of high-risk individuals which could possibly benefit from supplementation.

Biomarkers of oxidative stress in women with pre-eclampsia

AIM

The potential role of oxidative stress in the pathophysiology of pre-eclampsia has been reported in the literature. There are only a few studies that have investigated changes in malondialdehyde (MDA), vitamin E and total blood glutathione together in pre-eclampsia. Therefore, the aim of this study was to measure the levels of MDA, vitamin E and total glutathione as putative circulatory markers of oxidative stress for the early detection of pre-eclampsia.

PATIENTS & METHODS

In this case-control study, blood samples were collected from 40 pre-eclamptic and 80 normal pregnant females at the department of obstetrics and gynecology at King Abdulaziz Medical City (Riyadh, Saudi Arabia) between February 2009 and January 2010. Circulating markers of oxidative stress were evaluated, including MDA, total glutathione and vitamin E, by high-performance liquid chromatography.

RESULTS

Markers of oxidative stress including serum MDA, total glutathione and vitamin E were found to be significantly different in both groups.

CONCLUSION

MDA, vitamin E and blood total glutathione are possible candidate markers to predict pre-eclampsia.

miR-210 inhibits trophoblast invasion and is a serum biomarker for preeclampsia

Preeclampsia is characterized by hypertension and proteinuria in pregnant women. Its exact cause is unknown. Preeclampsia increases the risk of maternal and fetal morbidity and mortality. Although delivery, often premature, is the only known cure, early targeted interventions may improve maternal and fetal outcomes. Successful intervention requires a better understanding of the molecular etiology of preeclampsia and the development of accurate methods to predict women at risk. To this end, we tested the role of miR-210, a miRNA up-regulated in preeclamptic placentas, in first-trimester extravillous trophoblasts. miR-210 overexpression reduced trophoblast invasion, a process necessary for uteroplacental perfusion, in an extracellular signal-regulated kinase/mitogen-activated protein kinase-dependent manner. Conversely, miR-210 inhibition promoted invasion. Furthermore, given that the placenta secretes miRNAs into the maternal circulation, we tested if serum expression of miR-210 was associated with the disease. We measured miR-210 expression in two clinical studies: a case-control study and a prospective cohort study. Serum miR-210 expression was significantly associated with a diagnosis of preeclampsia (P = 0.007, area under the receiver operator curves = 0.81) and was predictive of the disease, even months before clinical diagnosis (P < 0.0001, area under the receiver operator curve = 0.89). Hence, we conclude that aberrant expression of miR-210 may contribute to trophoblast function and that miR-210 is a novel predictive serum biomarker for preeclampsia that can help in identifying at-risk women for monitoring and treatment.

Why hypertension is good new and preeclampsia bad news-demonstrating the failure of prevention

Hypertensive disorders in pregnancy continue to be an intriguing and potentially lethal complication in humans and some other primates. In a simplistic way the current hypothesis is that the genesis of preeclampsia starts at 12 to 14 wk gestation with failure of trophoblast invasion in the spiral arteries, resulting in some degree of hypoxemia in the placenta. The hypoperfused placental tissue starts to secrete variable amounts of angiogenic and antiangiogenic factors which eventually cause endothelial damage all over the pregnant women’s body with one of the many signs of preeclampsia as the clinical endpoint. For some incomprehensible reason a major interest has existed for decades concerning the early prediction of preeclampsia, most commonly tested using uterine artery Doppler (the earlier the better) and various serum markers, alone or in combination. Any new model for detection has been welcomed enthusiastically, although nothing has changed in the outcome of women presenting with preeclampsia.

Preeclampsia 2012

Preeclampsia is a common complication of pregnancy associated with high maternal morbidity and mortality and intrauterine fetal growth restriction. There is extensive evidence that the reduction of uteroplacental blood flow in this syndrome results from the toxic combination of hypoxia, imbalance of angiogenic and antiangiogenic factors, inflammation, and deranged immunity. Women treated for preeclampsia also have an increased risk for cardiovascular and renal disease. At present it is unclear if the increased cardiovascular and renal disease risks are due to residual and or progressive effects of endothelial damage from the preeclampsia or from shared risk factors between preeclampsia and cardiac disease. Moreover, it appears that endothelin-1 signaling may play a central role in the hypertension associated with preeclampsia. In this paper, we discuss emerging data on the pathogenesis of preeclampsia and review therapeutic options.

Preeclampsia: multiple approaches for a multifactorial disease

Preeclampsia is a pregnancy-specific disorder characterized by hypertension and excess protein excretion in the urine. It is an important cause of maternal and fetal morbidity and mortality worldwide. The disease is almost exclusive to humans and delivery of the pregnancy continues to be the only effective treatment. The disorder is probably multifactorial, although most cases of preeclampsia are characterized by abnormal maternal uterine vascular remodeling by fetally derived placental trophoblast cells. Numerous in vitro and animal models have been used to study aspects of preeclampsia, the most common being models of placental oxygen dysregulation, abnormal trophoblast invasion, inappropriate maternal vascular damage and anomalous maternal-fetal immune interactions. Investigations into the pathophysiology and treatment of preeclampsia continue to move the field forward, albeit at a frustratingly slow pace. There remains a pressing need for novel approaches, new disease models and innovative investigators to effectively tackle this complex and devastating disorder.

Antioxidants for preventing preeclampsia: a systematic review

OBJECTIVE

To investigate the efficacy of antioxidants for preventing preeclampsia and other maternal and fetal complications among pregnant women with low, moderate, or high risk of preeclampsia.

METHODS

We searched MEDLINE, Embase, CENTRAL, mRCT, and other databases, with no language or publication restrictions. Two independent reviewers selected randomized controlled trials that evaluated the use of antioxidants versus placebo and extracted the relevant data. Relative risks (RRs) and 95% confidence intervals (95% CIs) were calculated. The data were compiled through the random effects model.

MAIN RESULTS

Fifteen studies were included (21,012 women and 21,647 fetuses). No statistically significant difference was found between women who received antioxidant treatment and women who received placebo for preeclampsia (RR = 0.92; 95% CI: 0.82-1.04), severe preeclampsia (RR = 1.03; 95% CI: 0.87-1.22), preterm birth (RR = 1.03; 95% CI: 0.94-1.14), and small for gestational age <10th centile (RR = 0.92; 95% CI: 0.80-1.05). Side effects were numerically more frequent in the antioxidants group compared to placebo, but without significant statistical difference (RR = 1.24; 95% CI: 0.85-1.80).

CONCLUSIONS

The available evidence reviewed does not support the use of antioxidants during pregnancy for the prevention of preeclampsia and other outcomes.

Molecular mechanisms of hypertension--reactive oxygen species and antioxidants: a basic science update for the clinician

Many factors have been implicated in the pathophysiology of hypertension such as upregulation of the renin-angiotensin-aldosterone system, activation of the sympathetic nervous system, perturbed G protein-coupled receptor signalling, inflammation, and altered T-cell function. Common to these processes is increased bioavailability of reactive oxygen species (ROS) (termed oxidative stress) due to excess ROS generation, decreased nitric oxide (NO) levels, and reduced antioxidant capacity in the cardiovascular, renal, and nervous systems. Although oxidative stress may not be the sole etiology of hypertension, it amplifies blood pressure elevation in the presence of other prohypertensive factors. In the cardiovascular system ROS play a physiological role in controlling endothelial function, vascular tone, and cardiac function, and a pathophysiological role in inflammation, hypertrophy, proliferation, apoptosis, migration, fibrosis, angiogenesis, and rarefaction, all of which are important processes contributing to endothelial dysfunction and cardiovascular remodelling in hypertension. A major source for cardiovascular ROS is a family of nonphagocytic nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (Nox1, Nox2, Nox4, and Nox5). Other sources include mitochondrial enzymes, xanthine oxidase, and uncoupled NO synthase (NOS). Although convincing data from animal studies support a causative role for oxidative stress in the pathogenesis of hypertension, there is still no solid evidence that oxidative stress causes hypertension in humans. However, biomarkers of excess ROS are increased in patients with hypertension and oxidative damage is important in the molecular mechanisms associated with cardiovascular and renal injury in hypertension. Although clinical trials failed to show beneficial antihypertensive effects of antioxidants, strategies that combat oxidative stress by targeting Noxs in an isoform-specific manner may have therapeutic potential.