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.

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.

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.