Interventions affecting the nitric oxide pathway versus placebo or no therapy for fetal growth restriction in pregnancy.

BACKGROUND: Fetal growth restriction (FGR) is a condition of poor growth of the fetus in utero. One of the causes of FGR is placental insufficiency. Severe early-onset FGR at < 32 weeks of gestation occurs in an estimated 0.4% of pregnancies. This extreme phenotype is associated with a high risk of fetal death, neonatal mortality, and neonatal morbidity. Currently, there is no causal treatment, and management is focused on indicated preterm birth to prevent fetal death. Interest has risen in interventions that aim to improve placental function by administration of pharmacological agents affecting the nitric oxide pathway causing vasodilatation. OBJECTIVES: The objective of this systematic review and aggregate data meta-analysis is to assess the beneficial and harmful effects of interventions affecting the nitric oxide pathway compared with placebo, no therapy, or different drugs affecting this pathway against each other, in pregnant women with severe early-onset FGR. SEARCH METHODS: We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (16 July 2022), and reference lists of retrieved studies. SELECTION CRITERIA: We considered all randomised controlled comparisons of interventions affecting the nitric oxide pathway compared with placebo, no therapy, or another drug affecting this pathway in pregnant women with severe early-onset FGR of placental origin, for inclusion in this review. DATA COLLECTION AND ANALYSIS: We used standard Cochrane Pregnancy and Childbirth methods for data collection and analysis. MAIN RESULTS: We included a total of eight studies (679 women) in this review, all of which contributed to the data and analysis. The identified studies report on five different comparisons: sildenafil compared with placebo or no therapy, tadalafil compared with placebo or no therapy, L-arginine compared with placebo or no therapy, nitroglycerin compared with placebo or no therapy and sildenafil compared with nitroglycerin. The risk of bias of included studies was judged as low or unclear. In two studies the intervention was not blinded. The certainty of evidence for our primary outcomes was judged as moderate for the intervention sildenafil and low for tadalafil and nitroglycerine (due to low number of participants and low number of events). For the intervention L-arginine, our primary outcomes were not reported. Sildenafil citrate compared to placebo or no therapy (5 studies, 516 women) Five studies (Canada, Australia and New Zealand, the Netherlands, the UK and Brazil) involving 516 pregnant women with FGR were included. We assessed the certainty of the evidence as moderate. Compared with placebo or no therapy, sildenafil probably has little or no effect on all-cause mortality (risk ratio (RR) 1.01, 95% confidence interval (CI) 0.80 to 1.27, 5 studies, 516 women); may reduce fetal mortality (RR 0.82, 95% CI 0.60 to 1.12, 5 studies, 516 women), and increase neonatal mortality (RR 1.45, 95% CI 0.90 to 2.33, 5 studies, 397 women), although the results are uncertain for fetal and neonatal mortality as 95% confidence intervals are wide crossing the line of no effect. Tadalafil compared with placebo or no therapy (1 study, 87 women) One study (Japan) involving 87 pregnant women with FGR was included. We assessed the certainty of the evidence as low. Compared with placebo or no therapy, tadalafil may have little or no effect on all-cause mortality (risk ratio 0.20, 95% CI 0.02 to 1.60, one study, 87 women); fetal mortality (RR 0.11, 95% CI 0.01 to 1.96, one study, 87 women); and neonatal mortality (RR 0.89, 95% CI 0.06 to 13.70, one study, 83 women). L-Arginine compared with placebo or no therapy (1 study, 43 women) One study (France) involving 43 pregnant women with FGR was included. This study did not assess our primary outcomes. Nitroglycerin compared to placebo or no therapy (1 studies, 23 women) One study (Brazil) involving 23 pregnant women with FGR was included. We assessed the certainty of the evidence as low. The effect on the primary outcomes is not estimable due to no events in women participating in both groups. Sildenafil citrate compared to nitroglycerin (1 study, 23 women) One study (Brazil) involving 23 pregnant women with FGR was included. We assessed the certainty of the evidence as low. The effect on the primary outcomes is not estimable due to no events in women participating in both groups. AUTHORS' CONCLUSIONS: Interventions affecting the nitric oxide pathway probably do not seem to influence all-cause (fetal and neonatal) mortality in pregnant women carrying a baby with FGR, although more evidence is needed. The certainty of this evidence is moderate for sildenafil and low for tadalafil and nitroglycerin. For sildenafil a fair amount of data are available from randomised clinical trials, but with low numbers of participants. Therefore, the certainty of evidence is moderate. For the other interventions investigated in this review there are insufficient data, meaning we do not know whether these interventions improve perinatal and maternal outcomes in pregnant women with FGR.

Halting the Canadian STRIDER randomised controlled trial of sildenafil for severe, early-onset fetal growth restriction: ethical, methodological, and pragmatic considerations.

OBJECTIVES: To determine the efficacy and safety of sildenafil citrate to improve outcomes in pregnancies complicated by early-onset, dismal prognosis, fetal growth restriction (FGR). Eligibility: women ≥ 18 years, singleton, 18 + 0-27 + 6 weeks' gestation, estimated fetal weight < 700 g, low PLFG, and ≥ 1 of (i) abdominal circumference < 10th percentile for gestational age (GA); or (ii) reduced growth velocity and either abnormal uterine artery Doppler or prior early-onset FGR with adverse outcome. Ineligibility criteria included: planned termination or reversed umbilical artery end-diastolic flow. Eligibility confirmed by placental growth factor (PLGF) < 5 th percentile for GA measured post randomization. Women randomly received (1:1) either sildenafil 25 mg three times daily or matched placebo until either delivery or 31 + 6 weeks. PRIMARY OUTCOME: delivery GA. The trial stopped early when Dutch STRIDER signalled potential harm; despite distinct eligibility criteria and IRB and DSMB support to continue, because of futility. NCT02442492 [registered 13/05/2015]. RESULTS: Between May 2017 and June 2018, 21 (90 planned) women were randomised [10 sildenafil; 11 placebo (1 withdrawal)]. Baseline characteristics, PLGF levels, maternal and perinatal outcomes, and adverse events did not differ. Delivery GA: 26 + 6 weeks (sildenafil) vs 29 + 2 weeks (placebo); p = 0.200. Data will contribute to an individual participant data meta-analysis.

Short-term outcomes of phosphodiesterase type 5 inhibitors for fetal growth restriction: a study protocol for a systematic review with individual participant data meta-analysis, aggregate meta-analysis, and trial sequential analysis.

BACKGROUND: Early onset fetal growth restriction secondary to placental insufficiency can lead to severe maternal and neonatal morbidity and mortality. Pre-clinical studies and a few small randomised clinical trials have suggested that phosphodiesterase type 5 (PDE-5) inhibitors may have protective effects against placental insufficiency in this context; however, robust evidence is lacking. The STRIDER Consortium conducted four randomised trials to investigate the use of a PDE-5 inhibitor, sildenafil, for the treatment of early onset fetal growth restriction. We present a protocol for the pre-planned systematic review with individual participant data meta-analysis, aggregate meta-analysis, and trial sequential analysis of these and other eligible trials. The main objective of this study will be to evaluate the effects of PDE-5 inhibitors on neonatal morbidity compared with placebo or no intervention among pregnancies with fetal growth restriction. METHODS: We will search the following electronic databases with no language or date restrictions: OVID MEDLINE, OVID EMBASE, the Cochrane Controlled Register of Trials (CENTRAL), and the clinical trial registers Clinicaltrials.gov and World Health Organisation International Clinical Trials Registry Platform (ICTRP). We will identify randomised trials of PDE-5 inhibitors in singleton pregnancies with growth restriction. Two reviewers will independently screen all citations, full-text articles, and abstract data. Our primary outcome will be infant survival without evidence of serious adverse neonatal outcome. Secondary outcomes will include gestational age at birth and birth weight z-scores. We will assess bias using the Cochrane Risk of Bias 2 tool. We will conduct aggregate meta-analysis using fixed and random effects models, Trial Sequential Analysis, and individual participant data meta-analysis using one- and two-stage approaches. The certainty of evidence will be assessed with GRADE. DISCUSSION: This pre-defined protocol will minimise bias during analysis and interpretation of results, toward the goal of providing robust evidence regarding the use of PDE-5 inhibitors for the treatment of early onset fetal growth restriction. SYSTEMATIC REVIEW REGISTRATION: PROSPERO (CRD42017069688).

The feasibility of task-sharing the identification, emergency treatment, and referral for women with pre-eclampsia by community health workers in India.

BACKGROUND: Hypertensive disorders are the second highest direct obstetric cause of maternal death after haemorrhage, accounting for 14% of maternal deaths globally. Pregnancy hypertension contributes to maternal deaths, particularly in low- and middle-income countries, due to a scarcity of doctors providing evidence-based emergency obstetric care. Task-sharing some obstetric responsibilities may help to reduce the mortality rates. This study was conducted to assess acceptability by the community and other healthcare providers, for task-sharing by community health workers (CHW) in the identification and initial care in hypertensive disorders in pregnancy. METHODS: This study was conducted in two districts of Karnataka state in south India. A total of 14 focus group discussions were convened with various community representatives: women of reproductive age (N = 6), male decision-makers (N = 2), female decision-makers (N = 3), and community leaders (N = 3). One-to-one interviews were held with medical officers (N = 2), private healthcare OBGYN specialists (N = 2), senior health administrators (N = 2), Taluka (county) health officers (N = 2), and obstetricians (N = 4). All data collection was facilitated by local researchers familiar with the setting and language. Data were subsequently transcribed, translated and analysed thematically using NVivo 10 software. RESULTS: There was strong community support for home visits by CHW to measure the blood pressure of pregnant women; however, respondents were concerned about their knowledge, training and effectiveness. The treatment with oral antihypertensive agents and magnesium sulphate in emergencies was accepted by community representatives but medical practitioners and health administrators had reservations, and insisted on emergency transport to a higher facility. The most important barriers for task-sharing were concerns regarding insufficient training, limited availability of medications, the questionable validity of blood pressure devices, and the ability of CHW to correctly diagnose and intervene in cases of hypertensive disorders of pregnancy. CONCLUSION: Task-sharing to community-based health workers has potential to facilitate early diagnosis of the hypertensive disorders of pregnancy and assist in the provision of emergency care. We identified some facilitators and barriers for successful task-sharing of emergency obstetric care aimed at reducing mortality and morbidity due to hypertensive disorders of pregnancy.

Hypertonic saline increases lung epithelial lining fluid glutathione and thiocyanate: two protective CFTR-dependent thiols against oxidative injury.

BACKGROUND: Cystic fibrosis is a debilitating lung disease due to mutations in the cystic fibrosis transmembrane conductance regulator protein (CFTR) and is associated with chronic infections resulting in elevated myeloperoxidase activity and generation of hypochlorous acid (HOCl). CFTR mutations lead to decreased levels of glutathione (GSH) and thiocyanate (SCN) in the epithelial lining fluid (ELF). Hypertonic saline is used to improve lung function however the mechanism is uncertain. METHODS: In the present study, the effect of GSH and SCN on HOCl-mediated cell injury and their changes in the ELF after hypertonic saline nebulization in wild type (WT) and CFTR KO mice was examined. CFTR sufficient and deficient lung cells were assessed for GSH, SCN and corresponding sensitivity towards HOCl-mediated injury, in vitro. RESULTS: CFTR (-) cells had lower extracellular levels of both GSH and SCN and were more sensitive to HOCl-mediated injury. In vivo, hypertonic saline increased ELF GSH in the WT and to a lesser extent in the CFTR KO mice but only SCN in the WT ELF. Finally, potential protective effects of GSH and SCN at concentrations found in the ELF against HOCl toxicity were examined in vitro. CONCLUSIONS: While the concentrations of GSH and SCN associated with the WT ELF protect against HOCl toxicity, those found in the CFTR KO mice were less sufficient to inhibit cell injury. These data suggests that CFTR has important roles in exporting GSH and SCN which are protective against oxidants and that hypertonic saline treatment may have beneficial effects by increasing their levels in the lung.

Select cyclopentenone prostaglandins trigger glutathione efflux and the role of ABCG2 transport.

Electrophilic cyclopentenone prostaglandins (cyPGs), such as 15-deoxy-Delta(12,14)-prostaglandin J(2) (15dPGJ(2)), initiate redox-based cell signaling responses including increased intracellular glutathione (GSH) synthesis. We investigated whether cyPGs facilitated GSH efflux and if members of the ATP-binding cassette (ABC) protein family mediated the efflux. Four human cell lines were treated with 1-6 microM cyPGs for 48 h. Media and cells were harvested for GSH measurements using HPLC-EC. CyPG treatment increased extracellular GSH levels two- to threefold over controls in HN4 and C38 cells and five- to sixfold in SAEC and MDA 1586 cells and was dependent on increased GSH synthesis. Our studies show that prostaglandin D(2) and its metabolites, prostaglandin J(2) and 15dPGJ(2), specifically induce GSH efflux compared to other eicosanoids. These higher extracellular GSH levels were associated with protection from tert-butylhydroperoxide. Superarray analysis of ABC transporters suggested only ABCG2 expression had a positive relationship in the four cell types compared with extracellular GSH increases after cyPG treatment. The ABCG2 substrate Hoechst 33342 inhibited extracellular GSH increase after 15dPGJ(2) treatment. We report for the first time that ABCG2 may play a role in GSH efflux in response to cyPG treatment and may link inflammatory signaling with antioxidant adaptive responses.

Mycoplasma pneumoniae infection and environmental tobacco smoke inhibit lung glutathione adaptive responses and increase oxidative stress.

Chronic cigarette smoking evokes a lung glutathione (GSH) adaptive response that results in elevated GSH levels in the lung epithelial lining fluid (ELF). Currently, little is known about how the lung regulates or maintains steady-state levels of ELF GSH. Pathogens such as Mycoplasma pneumoniae can exacerbate airway inflammation and oxidative stress. The present study examined whether M. pneumoniae infections synergize with environmental tobacco smoke (ETS) to disrupt lung GSH adaptive responses. Mice were exposed separately and in combination to ETS and M. pneumoniae for 16 weeks. ETS exposure resulted in a doubling of ELF GSH levels, which was blocked in the M. pneumoniae-exposed mice. In addition, the ETS-plus-M. pneumoniae-exposed mice had elevated levels of oxidized glutathione (GSSG), resulting in a dramatic change in the ELF redox state that corresponded with an increase in lung tissue DNA oxidation. Similar findings were observed in human lung epithelial cells in vitro. Cells exposed separately or in combination to cigarette smoke extract and M. pneumoniae for 48 h had elevated apical levels of GSH compared to control cells, and these increases were blocked by M. pneumoniae and were also associated with increased cellular DNA oxidation. Further studies showed that M. pneumoniae exposure blocked ETS-induced increases in GSH reductase, an enzyme that recycles GSSG back to GSH, both in vitro and in vivo. These studies suggest that M. pneumoniae infection synergizes with ETS and suppresses the lung's ability to respond appropriately to environmental challenges leading to enhanced oxidative stress.

A role for CFTR in the elevation of glutathione levels in the lung by oral glutathione administration.

The cystic fibrosis transmembrane conductance regulator (CFTR) protein is the only known apical glutathione (GSH) transporter in the lung. The purpose of these studies was to determine whether oral GSH or glutathione disulfide (GSSG) treatment could increase lung epithelial lining fluid (ELF) GSH levels and whether CFTR plays a role in this process. The pharmacokinetic profile of an oral bolus dose of GSH (300 mg/kg) was determined in mice. Plasma, ELF, bronchoalveolar lavage (BAL) cells, and lung tissue were analyzed for GSH content. There was a rapid elevation in the GSH levels that peaked at 30 min in the plasma and 60 min in the lung, ELF, and BAL cells after oral GSH dosing. Oral GSH treatment produced a selective increase in the reduced and active form of GSH in all lung compartments examined. Oral GSSG treatment (300 mg/kg) resulted in a smaller increase of GSH levels. To evaluate the role of CFTR in this process, Cftr knockout (KO) mice and gut-corrected Cftr KO-transgenic (Tg) mice were given an oral bolus dose of GSH (300 mg/kg) and compared with wild-type mice for changes in GSH levels in plasma, lung, ELF, and BAL cells. There was a twofold increase in plasma, a twofold increase in lung, a fivefold increase in ELF, and a threefold increase in BAL cell GSH levels at 60 min in wild-type mice; however, GSH levels only increased by 40% in the plasma, 60% in the lung, 50% in the ELF, and twofold in the BAL cells within the gut-corrected Cftr KO-Tg mice. No change in GSH levels was observed in the uncorrected Cftr KO mice. These studies suggest that CFTR plays an important role in GSH uptake from the diet and transport processes in the lung.

Mitochondrial oxidative stress in the lungs of cystic fibrosis transmembrane conductance regulator protein mutant mice.

Cystic fibrosis is a fatal genetic disorder involving dysfunction of the cystic fibrosis transmembrane regulator protein (CFTR) resulting in progressive respiratory failure. Previous studies indicate that CFTR regulates cellular glutathione (GSH) transport and that dysfunctional CFTR is associated with chronic pulmonary oxidative stress. The cause and the source of this oxidative stress remain unknown. The current study examines the role of the mitochondria in CFTR-mediated pulmonary oxidative stress. Mitochondrial GSH levels and markers of DNA and protein oxidation were assessed in the lung mitochondria from CFTR-knockout mice. In addition, in vitro models using human CFTR-sufficient and -deficient lung epithelial cells were also employed. Mitochondrial GSH levels were found to be decreased up to 85% in CFTR-knockout mice, and 43% in human lung epithelial cells deficient in CFTR. A concomitant 29% increase in the oxidation of mitochondrial DNA, and a 30% loss of aconitase activity confirmed the existence of a mitochondrial oxidative stress. Flow cytometry revealed significantly elevated levels of cellular reactive oxygen species (ROS) in CFTR-deficient human lung cells. These studies suggest that dysfunctional CFTR leads to an increase in the level of ROS and mitochondrial oxidative stress. This oxidative stress, however, appears to be a consequence of lower mitochondrial GSH levels and not increased oxidation of GSH. Further studies are needed to determine how CFTR deficiency contributes to mitochondrial oxidative stress and the role this plays in CFTR-mediated lung pathophysiology.

Dichloroacetate-induced developmental toxicity and production of reactive oxygen species in zebrafish embryos.

Dichloroacetate (DCA) is one of the toxic by products that are formed during the chlorine disinfection process of drinking water. In this study, the developmental toxicity of DCA has been determined in zebrafish (Danio rerio) embryos. Embryos were exposed to different concentrations (4, 8, 16, and 32 mM) of the compound at the 4 h postfertilization (hpf) stage of development, and were observed for different developmental toxic effects at 8, 24, 32, 55, 80, and 144 hpf. Exposure of embryos to 8-32 mM of DCA resulted in significant increases in the heart rate and blood flow of the 55 and 80 hpf embryos that turned into significant decreases at the 144 hpf time point. At 144 hpf, malformations of mouth structure, notochord bending, yolk sac edema and behavioral effects including perturbed swimming and feeding behaviors were also observed. DCA was also found to produce time- and concentration-dependent increases in embryonic levels of superoxide anion (O2*-) and nitric oxide (NO), at various stages of development. The results of the study suggest that DCA-induced developmental toxic effects in zebrafish embryos are associated with production of reactive oxygen species in those embryos.

A novel class of cytochrome P450 reductase redox cyclers: cationic manganoporphyrins.

Manganese porphyrins are a potent class of catalytic antioxidants whose activity was recently shown to be partially dependent upon flavin-containing enzymes (R. Kachadourian et al., 2004, Biochem. Pharmacol. 67, 77-85). We tested whether manganese porphyrins could redox cycle with the flavin-containing enzyme, cytochrome P450 reductase, and whether this results in the inhibition of xenobiotic metabolism. The effect of manganese porphyrins on xenobiotic metabolism in rat and human liver microsomes was assessed spectrofluorometrically by following the O-dealkylation of benzyloxy- (BROD) and methoxyresorufin (MROD). Redox cycling of manganese porphyrins with human cytochrome P450 reductase was assessed both spectrophotometrically and polarographically by following the consumption of NADPH and oxygen, respectively. The tetrakis(N-pyridinium-2-yl) meso-substituted manganoporphyrin, MnTEPyP5+, and the tetrakis(1,3-dimethyl imidazolium-2-yl) meso-substituted manganoporphyrin, MnTDMIP5+, were 40 to 100 times more potent inhibitors of rat and human liver microsomal BROD metabolism than the tetrakis(1,3-diethyl imidazolium-2-yl) meso-substituted manganoporphyrin, MnTDEIP5+, or the tetrakis(4-benzoic acid) meso-substituted manganoporphyrin, MnTBAP. A similar pattern of inhibition was also seen in beta-naphthoflavone-induced rat liver microsomal MROD metabolism. This pattern of xenobiotic metabolism inhibition correlated with the compound's ability to redox cycle with cytochrome P450 reductase where MnTEPyP5+ was more potent than MnTDEIP5+. Furthermore, redox cycling of MnTEPyP5+ with cytochrome P450 reductase was inhibited by the flavin domain inhibitor diphenyleneiodonium. Small changes to the carbon chain length on the imidazolium side groups had a large effect on this activity. It is possible that interactions between manganoporphyrins and flavin-dependent oxidoreductases can account for both adverse and beneficial effects of the compounds.