Elevated amniotic fluid F₂-isoprostane: a potential predictive marker for preeclampsia

Urinary oxidative stress biomarkers are associated with preterm birth: an Environmental Influences on Child Health Outcomes program study

BACKGROUND

Preterm birth is the leading cause of infant morbidity and mortality worldwide. Elevated levels of oxidative stress have been associated with an increased risk of delivering before term. However, most studies testing this hypothesis have been conducted in racially and demographically homogenous study populations, which do not reflect the diversity within the United States.

OBJECTIVE

We leveraged 4 cohorts participating in the Environmental Influences on Child Health Outcomes Program to conduct the largest study to date examining biomarkers of oxidative stress and preterm birth (N=1916). Furthermore, we hypothesized that elevated oxidative stress would be associated with higher odds of preterm birth, particularly preterm birth of spontaneous origin.

STUDY DESIGN

This study was a pooled analysis and meta-analysis of 4 birth cohorts spanning multiple geographic regions in the mainland United States and Puerto Rico (208 preterm births and 1708 full-term births). Of note, 8-iso-prostaglandin-F2α, 2,3-dinor-5,6-dihydro-8-iso-prostaglandin-F2α (F2-IsoP-M; the major 8-iso-prostaglandin-F2α metabolite), and prostaglandin-F2α were measured in urine samples obtained during the second and third trimesters of pregnancy. Logistic regression was used to calculate adjusted odds ratios and 95% confidence intervals for the associations between averaged biomarker concentrations for each participant and all preterm births, spontaneous preterm births, nonspontaneous preterm births (births of medically indicated or unknown origin), and categories of preterm birth (early, moderate, and late). Individual oxidative stress biomarkers were examined in separate models.

RESULTS

Approximately 11% of our analytical sample was born before term. Relative to full-term births, an interquartile range increase in averaged concentrations of F2-IsoP-M was associated with higher odds of all preterm births (odds ratio, 1.29; 95% confidence interval, 1.11-1.51), with a stronger association observed for spontaneous preterm birth (odds ratio, 1.47; 95% confidence interval, 1.16-1.90). An interquartile range increase in averaged concentrations of 8-iso-prostaglandin-F2α was similarly associated with higher odds of all preterm births (odds ratio, 1.19; 95% confidence interval, 0.94-1.50). The results from our meta-analysis were similar to those from the pooled combined cohort analysis.

CONCLUSION

Here, oxidative stress, as measured by 8-iso-prostaglandin-F2α, F2-IsoP-M, and prostaglandin-F2α in urine, was associated with increased odds of preterm birth, particularly preterm birth of spontaneous origin and delivery before 34 completed weeks of gestation.

Hypertension and renal disease programming: focus on the early postnatal period

The developmental origin of hypertension and renal disease is a concept highly supported by strong evidence coming from both human and animal studies. During development there are periods in which the organs are more vulnerable to stressors. Such periods of susceptibility are also called 'sensitive windows of exposure'. It was shown that as earlier an adverse event occurs; the greater are the consequences for health impairment. However, evidence show that the postnatal period is also quite important for hypertension and renal disease programming, especially in rodents because they complete nephrogenesis postnatally, and it is also important during preterm human birth. Considering that the developing kidney is vulnerable to early-life stressors, renal programming is a key element in the developmental programming of hypertension and renal disease. The purpose of this review is to highlight the great number of studies, most of them performed in animal models, showing the broad range of stressors involved in hypertension and renal disease programming, with a particular focus on the stressors that occur during the early postnatal period. These stressors mainly include undernutrition or specific nutritional deficits, chronic behavioral stress, exposure to environmental chemicals, and pharmacological treatments that affect some important factors involved in renal physiology. We also discuss the common molecular mechanisms that are activated by the mentioned stressors and that promote the appearance of these adult diseases, with a brief description on some reprogramming strategies, which is a relatively new and promising field to treat or to prevent these diseases.

Update on oxidative stress and inflammation in pregnant women, unborn children (nasciturus), and newborns - Nutritional and dietary effects

The scientific background of perinatal pathology, regarding both mother and offspring, from the lipidomic perspective, has highlighted the possibility of identifying new, promising clinical markers of oxidative stress and inflammation, closely related to the normal development of unborn and newborn children, together with their application. In this regard, in recent years, significant advances have been achieved, assisted by both newly developed analytical tools and basic knowledge on the biological implications of oxylipins. Hence, in the light of this recent progress, this review aims to provide an update on the relevance of human oxylipins during pregnancy and in the unborn and newborn child, covering two fundamental aspects. Firstly, the evidence from human clinical studies and dietary intervention trials will be used to shed light on the extent to which dietary supplementation can modulate the lipidomic markers of oxidative stress and inflammation in the perinatal state, emphasizing the role of the placenta and metabolic disturbances in the mother and fetus. The second part of this article comprises a review of existing data on specific pathophysiological aspects of human reproduction, in relation to lipidomic markers in pregnant women, unborn children, and newborn children. The information reviewed here evidences the current opportunity to correct reproductive disturbances, in the framework of lipidomics, by fine-tuning dietary interventions.

Isoprostanes, neuroprostanes and phytoprostanes: An overview of 25years of research in chemistry and biology

Since the beginning of the 1990's diverse types of metabolites originating from polyunsaturated fatty acids, formed under autooxidative conditions were discovered. Known as prostaglandin isomers (or isoprostanoids) originating from arachidonic acid, neuroprostanes from docosahexaenoic acid, and phytoprostanes from α-linolenic acid proved to be prevalent in biology. The syntheses of these compounds by organic chemists and the development of sophisticated mass spectrometry methods has boosted our understanding of the isoprostanoid biology. In recent years, it has become accepted that these molecules not only serve as markers of oxidative damage but also exhibit a wide range of bioactivities. In addition, isoprostanoids have emerged as indicators of oxidative stress in humans and their environment. This review explores in detail the isoprostanoid chemistry and biology that has been achieved in the past three decades.

Correlation between markers of DNA and lipid oxidative damage in maternal and fetoplacental compartment in the mid-trimester of pregnancy

OBJECTIVE

To determine the levels of 8-isoprostane (8-IP) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in urine and in amniotic fluid (AF) of pregnant women and to assess the correlation between oxidative status in the maternal and fetal compartment in the second trimester of pregnancy.

METHODS

One hundred and forty-six women with singleton pregnancies, undergoing amniocentesis at the Department of Obstetrics and Gynaecology at the University Medical Centre Ljubljana, were prospectively enrolled. AF and maternal urine were collected in the second trimester of pregnancy. Paired urinary and AF 8-IP and 8-OHdG were measured and evaluated cross-sectionally.

RESULTS

8-IP and 8-OHdG concentrations were higher in maternal urine compared to AF and the ratios were 47:1 and 50:1, respectively. AF 8-OHdG was very low and in 74% was below the limit of detection (LOD). We found a positive correlation between 8-IP in maternal and fetal compartment (ρ=0.217, P=0.008), which stayed unchanged also after adjustment for possible confounding factors.

CONCLUSIONS

Oxidative damage to lipids and DNA is also a part of physiologic processes during healthy pregnancy. 8-IP and 8-OHdG are constantly present in urine and AF. A weak positive correlation between maternal and fetal unit suggests a weak reflection of fetal oxidative status in maternal urine in the mid-trimester.

Impact of oxidative stress during pregnancy on fetal epigenetic patterns and early origin of vascular diseases

Epidemiological studies have led scientists to postulate the developmental origins of health and disease hypothesis for noncommunicable diseases such as diabetes, cardiovascular diseases, hypertension, and obesity. However, the cellular and molecular mechanisms involved in the development of these diseases are not well understood. In various animal models, it has been observed that oxidative stress during pregnancy is associated with the early development of endothelial dysfunction in offspring. This phenomenon suggests that endothelial dysfunction may initiate in the uterus and could lead to increased risk of cardiovascular disease later in life. Currently, it is known that many of the fetal adaptive responses to environmental factors are mediated by epigenetic changes in the genome, especially by the degree of methylation in cytosines in the promoter regions of genes. These findings suggest that the establishment of a particular epigenetic pattern in the genome may be generated by oxidative stress.

Plasma F2-isoprostane class VI isomers at 12-18 weeks of pregnancy are associated with later occurrence of preeclampsia

Preeclampsia (PE) has long been associated with early oxidative stress, although the symptoms occur later in pregnancy. We have hypothesized that the oxidative stress in PE, as characterized by the presence of F2-isoprostane (F2-isoP) isomers in late pregnancy, should already be present in plasma at the first regular visit of the obstetrical follow-up. There are 64 possible isomers of F2-isoPs derived from the oxidation of arachidonic acid (AA), but only one of these isomers has been investigated so far in PE, the classical 8-iso-PGF2α. Here, we have investigated two regioisomers of class III (8-iso-15(R)-PGF2α and 8-iso-PGF2α) and a mix of two isomers of class VI ((±)5-iPF2α-VI) in plasma samples collected prospectively at 12-18 weeks from normotensive controls (n = 60) and pregnant mothers who developed PE later in pregnancy (n = 33). The plasma samples were subjected to alkaline hydrolysis followed by liquid-liquid extraction to extract total F2-isoPs for later quantification by HPLC-MS/MS. The F2-isoPs were normalized to either plasma volume or polyunsaturated fatty acid (PUFA) levels measured by GC-FID in plasma phospholipids. Early in pregnancy, only the class VI F2-isoP isomers were found at concentrations significantly higher in women developing PE later in pregnancy (+13%; p = 0.0074). Normalization of F2-isoPs to their substrate, AA, or the omega-3 to omega-6 ratio improved the predictability of PE as determined by receiver operating characteristic (from area under the curve of 0.67 to 0.68 and 0.70 respectively). Interestingly, omega-3 fatty acids were 25% higher in the control group than in the PE group (P = 0.0225). Omega-6 PUFAs correlated with F2-Isop isomers only in cases of PE (r > 0.377; P >0.03, Spearman correlation). In sum, this study indicates that specific isomers of class VI are significant predictors of PE. This work also suggests that F2-isoP isomers are not all generated and eliminated to the same extent and are influenced by the PUFA composition of plasma phospholipids.

Catalytic ferrous iron in amniotic fluid as a predictive marker of human maternal-fetal disorders

Amniotic fluid contains numerous biomolecules derived from fetus and mother, thus providing precious information on pregnancy. Here, we evaluated oxidative stress of human amniotic fluid and measured the concentration of catalytic Fe(II). Amniotic fluid samples were collected with consent from a total of 89 subjects in Nagoya University Hospital, under necessary medical interventions: normal pregnancy at term, normal pregnancy at the 2nd trimester, preterm delivery with maternal disorders but without fetal disorders, congenital diaphragmatic hernia, fetal growth restriction, pregnancy-induced hypertension, gestational diabetes mellitus, Down syndrome and trisomy 18. Catalytic Fe(II) and oxidative stress markers (8-hydroxy-2'-deoxyguanosine, 8-OHdG; dityrosine) were determined with RhoNox-1 and specific antibodies, respectively, using plate assays. Levels of 8-OHdG and dityrosine were higher in the 3rd trimester compared with the 2nd trimester in normal subjects, and the abnormal groups generally showed lower levels than the controls, thus suggesting that they represent fetal metabolic activities. In contrast, catalytic Fe(II) was higher in the 2nd trimester than the 3rd trimester in the normal subjects, and overall the abnormal groups showed higher levels than the controls, suggesting that high catalytic Fe(II) at late gestation reflects fetal pathologic alterations. Notably, products of H₂O₂ and catalytic Fe(II) remained almost constant in amniotic fluid.

Current development in non-enzymatic lipid peroxidation products, isoprostanoids and isofuranoids, in novel biological samples

Isoprostanoids and isofuranoids are lipid mediators that can be formed from omega-3 and omega-6 polyunsaturated fatty acids (PUFAs). F2-isoprostanes formed from arachidonic acid, especially 15-F2t-isoprostane, are commonly measured in biological tissues for decades as the biomarker for oxidative stress and diseases. Recently, other forms of isoprostanoids derived from adrenic, eicosapentaenoic, and docosahexaenoic acids namely F2-dihomo-isoprostanes, F3-isoprostanes, and F4-neuroprostanes respectively, and isofuranoids including isofurans, dihomo-isofurans, and neurofurans are reported as oxidative damage markers for different metabolisms. The most widely used samples in measuring lipid peroxidation products include but not limited to the blood and urine; other biological fluids, specialized tissues, and cells can also be determined. In this review, measurement of isoprostanoids and isofuranoids in novel biological samples by gas chromatography (GC)-mass spectrometry (MS), GC-MS/MS, liquid chromatography (LC)-MS, and LC-MS/MS will be discussed.

Non-enzymatic lipid oxidation products in biological systems: assessment of the metabolites from polyunsaturated fatty acids

Metabolites of non-enzymatic lipid peroxidation of polyunsaturated fatty acids notably omega-3 and omega-6 fatty acids have become important biomarkers of lipid products. Especially the arachidonic acid-derived F2-isoprostanes are the classic in vivo biomarker for oxidative stress in biological systems. In recent years other isoprostanes from eicosapentaenoic, docosahexaenoic, adrenic and α-linolenic acids have been evaluated, namely F3-isoprostanes, F4-neuroprostanes, F2-dihomo-isoprostanes and F1-phytoprostanes, respectively. These have been gaining interest as complementary specific biomarkers in human diseases. Refined extraction methods, robust analysis and elucidation of chemical structures have improved the sensitivity of detection in biological tissues and fluids. Previously the main reliable instrumentation for measurement was gas chromatography-mass spectrometry (GC-MS), but now the use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) and immunological techniques is gaining much attention. In this review, the types of prostanoids generated from non-enzymatic lipid peroxidation of some important omega-3 and omega-6 fatty acids and biological samples that have been determined by GC-MS and LC-MS/MS are discussed.

Review: maternal and placental antioxidant response to preeclampsia - impact on vasoactive eicosanoids

The abnormally developed placenta is believed to be the pathophysiological cause of preeclampsia (PE). The resulting malperfusion of the placenta in PE can be associated with fluctuations in oxygen levels, leading to oxidative stress. How then do the placenta and the circulatory system of the mother adapt and respond to the increased oxidative challenge associated with PE? Many antioxidant systems have been shown to be upregulated or downregulated in the placenta and/or the maternal circulation during PE. Such altered antioxidant response can lead to increased lipid peroxidation. Oxidation of arachidonoyl residues in phospholipids generates bioactive lipids such as F2-isoprostanes, which are known vasoconstrictors. The consequences of changes in antioxidant status can also affect signal transduction and enzymatic pathways related to eicosanoid synthesis.

Mitochondrial activation in the growth-restricted fetus of monochorionic twins

OBJECTIVE

To study the regulatory mechanisms of selective intrauterine growth restriction (sIUGR) independent of confounding genetic factors, monochorionic (MC) twins are the ideal model, because they have identical genomic DNA. We hypothesize that the intrauterine growth restriction fetus has mitochondrial activation compared with its larger counterpart, and sought to demonstrate this using the MC twin model.

DESIGN

Fetal cord blood and amniotic fluid of MC twins were prospectively collected during delivery. Mitochondrial DNA of cord blood was measured using real-time quantitative polymerase chain reaction (PCR), and mitochondria in amniotic fluid mesenchymal stem cells (AFMSCs) were analyzed with MitoTracker staining.

SETTING

Tertiary referring center.

PATIENT(S)

Forty-three pairs of MC twins, including 24 pairs with sIUGR and 19 pairs without.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Mitochondrial DNA contents were measured and presented as fold difference between the small and large fetuses. After staining with MitoTracker, mitochondrial intensity in AFMSCs was analyzed with the Image J program.

RESULT(S)

The fold differences of the cord blood mitochondrial DNA content between the small and large twins were significantly higher in the MC twins with sIGUR (2.5 ± 1.2, n = 24 pairs) than in those without sIUGR (1.2 ± 0.3, n = 19 pairs). In addition, mitochondrial staining intensities were significantly higher in the AFMSCs derived from growth-restricted fetuses than from control fetuses.

CONCLUSION(S)

Mitochondrial activation in the sIUGR fetus of MC twins was likely regulated by locally adverse placental and blood flow conditions, instead of genetic factors.

Amniotic fluid oxidative and nitrosative stress biomarkers correlate with fetal chronic hypoxia in diabetic pregnancies

BACKGROUND

In spite of improvement in obstetrical care, pregnancy in women with type 1 diabetes mellitus is associated with increased perinatal morbidity and mortality. Hyperglycemia during pregnancy causes excessive fetal growth and chronic fetal hypoxia as reflected in increased erythropoietin (EPO) levels in amniotic fluid (AF).

OBJECTIVES

We hypothesized that the degree of fetal hypoxia would correlate with fetal oxidative and nitrosative stress as evidenced ty the concentration of specific biomarkers in AF.

MATERIAL AND METHODS

19 pregnant women with type 1 or insulin-treated gestational diabetes mellitus were studied. AF samples were collected and processed for EPO, meta-tyrosine, nitro-tyrosine and 8-hydroxy-2-deoxiguanosine by chemiluminescent immunoassay and high-performance liquid chromatography coupled to tandem mass spectrometry methods, respectively.

RESULTS

The mean (SD) of the last HbA1c concentration before delivery was 7.7% (1.1). Median gestational age was 258 days (range 231-268). Birth weight was 3,868 ± 695 g with a z-score >2 SD in 47% of the cases. A significant correlation was found between the concentrations of AF EPO and meta-tyrosine/phenylalanine ratio (p < 0.001), nitro-tyrosine (p < 0.01) and 8-oxo-dG/2dG ratio (p < 0.001).

CONCLUSIONS

We confirmed that fetuses of type 1 diabetes or insulin-treated gestational diabetes pregnancies experience chronic hypoxia as reflected by increased EPO concentrations in AF near term. Moreover, EPO levels significantly correlated with the concentration of oxidative and nitrosative stress biomarkers in AF. This pro-oxidant status may predispose newborn infants to poor postnatal adaptation and early neonatal complications.

Application of proteomics for the identification of biomarkers in amniotic fluid: are we ready to provide a reliable prediction?

Proteomics-based identification of biomarkers for fetal abnormalities and pregnancy complications in amniotic fluid (AF) has made significant progress in the past 5 years. This is attributed mainly to advances in mass spectrometry-based proteomic technologies that enable new strategies for discovering biomarkers from complex biological fluids in a high-throughput and sensitive manner. These markers, although they still need to be verified, are diagnostic and may in the future provide targets for therapeutic intervention. In the current review we focus on the emergence of proteomics as a major platform technology in studying AF and developing biomarkers for fetal aneuploidies and pregnancy-related disorders.