Oxidative stress in midpregnancy as a predictor of gestational hypertension and pre-eclampsia

Oxidative stress biomarkers in pregnancy: a systematic review

BACKGROUND

This systematic review explores the level of oxidative stress (OS) markers during pregnancy and their correlation with complications. Unlike previous studies, it refrains from directly investigating the role of OS but instead synthesises data on the levels of these markers and their implications for various pregnancy-related complications such as preeclampsia, intrauterine growth restrictions, preterm premature rupture of membranes, preterm labour, gestational diabetes mellitus and miscarriages.

METHOD

STUDY DESIGN: Utilizing a systematic review approach, we conducted a comprehensive search across databases, including MEDLINE, CINAHL (EBSCOhost), ScienceDirect, Web of Science, and SCOPUS. Our search encompassed all publication years in English.

RESULTS

After evaluating 54,173 records, 45 studies with a low risk of bias were selected for inclusion. This systematic review has underscored the importance of these markers in both physiological and pathological pregnancy states such as preeclampsia, intrauterine growth restrictions, preterm premature rupture of membranes, preterm labour, gestational diabetes mellitus and miscarriages.

CONCLUSION

This systematic review provides valuable insights into the role of OS in pregnancy and their connection to complications. These selected studies delved deeply into OS markers during pregnancy and their implications for associated complications. The comprehensive findings highlighted the significance of OS markers in both normal and pathological pregnancy conditions, paving the way for further research in this field.

Connecting G protein-coupled estrogen receptor biomolecular mechanisms with the pathophysiology of preeclampsia: a review

BACKGROUND

Throughout the course of pregnancy, small maternal spiral arteries that are in contact with fetal tissue undergo structural remodeling, lose smooth muscle cells, and become less responsive to vasoconstrictors. Additionally, placental extravillous trophoblasts invade the maternal decidua to establish an interaction between the fetal placental villi with the maternal blood supply. When successful, this process enables the transport of oxygen, nutrients, and signaling molecules but an insufficiency leads to placental ischemia. In response, the placenta releases vasoactive factors that enter the maternal circulation and promote maternal cardiorenal dysfunction, a hallmark of preeclampsia (PE), the leading cause of maternal and fetal death. An underexplored mechanism in the development of PE is the impact of membrane-initiated estrogen signaling via the G protein-coupled estrogen receptor (GPER). Recent evidence indicates that GPER activation is associated with normal trophoblast invasion, placental angiogenesis/hypoxia, and regulation of uteroplacental vasodilation, and these mechanisms could explain part of the estrogen-induced control of uterine remodeling and placental development in pregnancy.

CONCLUSION

Although the relevance of GPER in PE remains speculative, this review provides a summary of our current understanding on how GPER stimulation regulates some of the features of normal pregnancy and a potential link between its signaling network and uteroplacental dysfunction in PE. Synthesis of this information will facilitate the development of innovative treatment options.

Energy-Adjusted Dietary Inflammatory Index in pregnancy and maternal cardiometabolic health: findings from the ROLO study

Background

Excessive inflammation during pregnancy has been linked to adverse long-term health outcomes for both mothers and their children. One such outcome is maternal cardiometabolic dysfunction. The Energy-Adjusted Dietary Inflammatory Index is a method of scoring the overall inflammatory potential of the diet. Research on how the inflammatory potential of the maternal diet during pregnancy affects maternal cardiometabolic factors is limited.

Objective

We investigated if the maternal Energy-Adjusted Dietary Inflammatory Index was associated with maternal cardiometabolic factors during pregnancy.

Study design

This is a secondary analysis of 518 individuals who participated in the ROLO (Randomized cOntrol trial of a LOw glycemic index diet in pregnancy) study. Maternal Energy-Adjusted Dietary Inflammatory Index scores were calculated in early (12-14 weeks' gestation) and late pregnancy (34 weeks' gestation) using data collected from 3-day food diaries. Body mass index, blood pressure, fasting lipid profiles, glucose levels, and HOMA1-IR were obtained in early and late pregnancy. Multiple linear regression examined associations between early-pregnancy Energy-Adjusted Dietary Inflammatory Index and early and late maternal cardiometabolic markers. In addition, the relationship between late-pregnancy Energy-Adjusted Dietary Inflammatory Index and late cardiometabolic factors was explored. Regression models were adjusted for maternal ethnicity, maternal age at delivery, education level, smoking status, and original randomized control trial group allocation. In regression models examining late-pregnancy Energy-Adjusted Dietary Inflammatory Index with late lipids, change in lipid level from early to late pregnancy was also adjusted for.

Results

Women's mean (standard deviation) age at delivery was 32.8 (±4.01) years, with median (interquartile range) body mass index of 24.45 (23.34-28.20) kg/m². Mean (standard deviation) Energy-Adjusted Dietary Inflammatory Index was 0.59 (±1.60) in early pregnancy and 0.67 (±1.59) in late pregnancy. In adjusted linear regression analysis, first-trimester maternal Energy-Adjusted Dietary Inflammatory Index was positively associated with maternal body mass index (B=0.007; 95% confidence interval, 0.003-0.011; P=.001), early-pregnancy cardiometabolic markers including total cholesterol (B=0.155; 95% confidence interval, 0.061-0.249; P=.001), triglycerides (B=0.043; 95% confidence interval, 0.005-0.080; P=.03), low-density lipoproteins (B=0.129; 95% confidence interval, 0.049-0.209; P=.002), and diastolic blood pressure (B=0.538; 95% confidence interval, 0.070-1.006; P=.02), and late-pregnancy cardiometabolic markers including total cholesterol (B=0.127; 95% confidence interval, 0.012-0.243; P=.01) and low-density lipoproteins (B=0.110; 95% confidence interval, 0.010-0.209; P=.03). In the third trimester, Energy-Adjusted Dietary Inflammatory Index was associated with late-pregnancy diastolic blood pressure (B=0.624; 95% confidence interval, 0.103-1.145; P=.02), HOMA1-IR (B=0.030; 95% confidence interval, 0.005-0.054; P=.02), and glucose (B=0.003; 95% confidence interval, 0.003-0.034; P=.03). No associations were observed between third-trimester Energy-Adjusted Dietary Inflammatory Index and late-pregnancy lipid profiles.

Conclusion

Maternal diets with a higher Energy-Adjusted Dietary Inflammatory Index, which were low in anti-inflammatory foods and rich in proinflammatory foods, were associated with increased levels of cardiometabolic health risk factors in pregnancy. Promoting dietary intakes that have a lower inflammatory potential may support more favorable maternal cardiometabolic profiles during pregnancy.

Association between the peripartum maternal and fetal telomere lengths and mitochondrial DNA copy numbers and preeclampsia: a prospective case-control study

Purpose

To explore changes in telomere length (TL) and mitochondrial copy number (mtDNA-CN) in preeclampsia (PE) and to evaluate the combined effect of maternal TL and mtDNA-CN on PE risk.

Methods

A case–control study of 471 subjects (130 PE cases and 341 age frequency matched controls with gestational age rank from 24 to 42 weeks) was conducted in Nanjing Drum Tower Hospital, Jiangsu Province of China. Relative telomere length (RTL) and mtDNA-CN were measured using quantitative polymerase chain reaction (qPCR), and PE risk was compared between groups by logistic regression analyses.

Results

PE patients displayed longer RTL (0.48 versus 0.30) and higher mtDNA-CN (3.02 versus 2.00) in maternal blood as well as longer RTL (0.61 versus 0.35) but lower mtDNA-CN (1.69 versus 5.49) in cord blood (all p < 0.001). Exercise during pregnancy exerted an obvious effect of maternal telomere length prolongation. Multiparous women with folic acid intake during early pregnancy and those who delivered vaginally showed longer telomere length, while those factors imposed no or opposite effect on RTL in PE cases. Furthermore, RTL and mtDNA-CN were positively correlated in controls (in maternal blood r = 0.18, p < 0.01; in cord blood r = 0.19, p < 0.001), but this correlation was disrupted in PE patients in both maternal blood and cord blood. Longer maternal RTL and higher mtDNA-CN were associated with a higher risk of PE, and the ROC curve of RTL and mtDNA-CN for predicting PE risk presented an AUC of 0.755 (95% CI: 0.698–0.812).

Conclusions

The interaction of TL and mtDNA-CN may play an important role in the pathogenesis of PE and could be a potential biomarker of PE risk.

Supplementary information

The online version contains supplementary material available at 10.1186/s12884-022-04801-0.

Maternal Dietary Inflammatory Index during Pregnancy Is Associated with Perinatal Outcomes: Results from the IMPACT BCN Trial

The information available on the effects of maternal dietary habits on systemic inflammation and adverse maternal outcomes is limited. We aimed to evaluate whether Dietary Inflammatory Index (DII) score during pregnancy is associated with maternal body mass index (BMI), Mediterranean diet (MD) adherence, and perinatal outcomes. At 19−23 weeks’ gestation, 1028 pregnant women were recruited. Dietary information was assessed using a 17-item dietary score to evaluate MD adherence and a validated 151-item food frequency questionnaire. DII score was established according to 33 food and nutritional proinflammatory and anti-inflammatory items. Participants were distributed into tertiles according to the DII score, where a lower DII score (first tertile) represented an anti-inflammatory diet and the third tertile represented the more proinflammatory diet. Maternal characteristics and perinatal outcomes were collected, and newborns’ birthweight percentiles were calculated. Adjusted logistic regression models were used to assess the association of the DII score with maternal and perinatal characteristics, setting the third tertile as the reference group. Women in the third tertile showed lower adherence to MD score compared to the first tertile: median (25th to 75th percentile) 9 (7 to 11) vs. 6 (4.25 to 8), p < 0.001. The proinflammatory diet was significantly associated with a higher maternal pre-pregnancy BMI (adjusted β = 0.88; 95% CI: 0.31 to 1.45) and lower newborn’s birthweight percentile (adjusted β = −9.84th; 95% CI: −19.6 to −0.12). These data show that a proinflammatory diet profile may be associated with maternal overweight and fetal undergrowth.

NFKB1-mediated downregulation of microRNA-106a promotes oxidative stress injury and insulin resistance in mice with gestational hypertension

This study intended to investigate the role of NFKB1 in oxidative stress injury and insulin resistance in gestational hypertension (GH) mice. Following establishment of a GH mouse model by high-fat diet, NFKB1, miR-106a, and FLOT2 expression was detected in liver of mice. After NFKB1, miR-106a, and FLOT2 were altered in GH mice by lentiviral vector, oxidative stress markers in liver tissues were examined by colorimetry, and insulin resistance was assessed by fasting blood glucose and fasting insulin levels. Next, hepatocytes were isolated from GH mice and treated with miR-106a mimic, inhibitor or siRNA, followed by determination of hepatocyte apoptosis and the expression of inflammation- and apoptosis-related factors. Evaluation of the correlations among NFKB1, miR-106a, and FLOT2 were conducted. Liver of GH mice harbored NFKB1 and FLOT2 upregulation and miR-106a downregulation. miR-106a was transcriptionally inhibited by NFKB1, and negatively targeted FLOT2. Oxidative stress injury and insulin resistance in GH mice and apoptosis and inflammation of hepatocytes from GH mice were decreased after silencing NFKB1 or FLOT2 or overexpressing miR-106a. These findings provided evidence demonstrating the inhibitory effect of NFKB1 silencing on oxidative stress injury and insulin resistance in GH mice via miR-106a upregulation and FLOT2 downregulation.

Cross-Talk between Oxidative Stress and Inflammation in Preeclampsia

The occurrence of hypertensive syndromes during pregnancy leads to high rates of maternal-fetal morbidity and mortality. Amongst them, preeclampsia (PE) is one of the most common. This review aims to describe the relationship between oxidative stress and inflammation in PE, aiming to reinforce its importance in the context of the disease and to discuss perspectives on clinical and nutritional treatment, in this line of research. Despite the still incomplete understanding of the pathophysiology of PE, it is well accepted that there are placental changes in pregnancy, associated with an imbalance between the production of reactive oxygen species and the antioxidant defence system, characterizing the placental oxidative stress that leads to an increase in the production of proinflammatory cytokines. Hence, a generalized inflammatory process occurs, besides the presence of progressive vascular endothelial damage, leading to the dysfunction of the placenta. There is no consensus in the literature on the best strategies for prevention and treatment of the disease, especially for the control of oxidative stress and inflammation. In view of the above, it is evident the important connection between oxidative stress and inflammatory process in the pathogenesis of PE, being that this disease is capable of causing serious implications on both maternal and fetal health. Reports on the use of anti-inflammatory and antioxidant compounds are analysed and still considered controversial. As such, the field is open for new basic and clinical research, aiming the development of innovative therapeutic approaches to prevent and to treat PE.

Maternal serum uric acid levels and blood pressure during pregnancy: A community-based cohort study

OBJECTIVE

Studies find both very low and high serum uric acid (UA) levels are related to oxidative stress and to conditions such as cardiovascular diseases and chronic kidney disease in the general population. Pregnancy studies have focused only on high maternal UA. In present study, we tested whether unusually high and low levels of maternal serum UA are associated with increases in blood pressure (BP) during pregnancy.

STUDY DESIGN

The Pregnancy Outcomes and Community Health Study enrolled 3019 pregnant women between their 16th-27th week of pregnancy from 52 clinics in 5 Michigan communities (1998-2004). UA levels were measured in maternal blood collected at enrollment from a sub-cohort of 1223 participants. BP was abstracted from prenatal medical records; these analyses used highest recorded diastolic BP (DBP) and its companion systolic BP (SBP). Mean arterial pressure (MAP) was calculated using the formula of (2 × DBP + SBP)/3. Covariates, including maternal race/ethnicity, age at enrollment, education level, medical insurance status, body mass index before pregnancy, parity, smoking during pregnancy, alcohol use during pregnancy, and gestational week at blood collection, were considered as potential confounding variables. Associations between UA levels and BP were evaluated with linear spline or multiple linear regression models. Models' robustness was examined with bootstrap estimation of variance, sensitivity analysis, and 10-fold cross-validation.

RESULTS

Both DBP and MAP had a J-shaped relationship with maternal UA; the breakpoints (nadirs) were 0.153 and 0.161 mmol/L UA, respectively. For DBP versus UA, adjusted regression coefficient (β) = -95.67 (standard error (SE) = 37.67 and p = 0.01) for the left and adjusted β = 48.95 (SE = 9.56 and p < 0.01) for the right; for MAP versus UA, adjusted β = -58.48 (SE = 31.42 and p = 0.06) for the left and adjusted β = 52.23 (SE = 11.39 and p < 0.01) for the right. Maternal SBP followed a positive linear trend with UA levels (adjusted β = 37.75, SE = 12.93, and p < 0.01). All results were robust.

CONCLUSION

Extreme high and low maternal serum UA levels may be informative in studying maternal blood pressure during pregnancy.

Dietary Inflammatory Potential during Pregnancy Is Associated with Lower Fetal Growth and Breastfeeding Failure: Results from Project Viva

BACKGROUND

Inflammation during pregnancy has been linked to adverse maternal and infant outcomes. There is limited information available on the contribution of maternal diet to systemic inflammation and pregnancy health.

OBJECTIVE

The objective of this study was to examine associations of maternal prenatal dietary inflammatory index (DII), a composite measure of the inflammatory potential of diet, with markers of maternal systemic inflammation and pregnancy outcomes.

METHODS

We studied 1808 mother-child pairs from Project Viva, a pre-birth cohort study in Massachusetts. We calculated the DII from first- and second-trimester food-frequency questionnaires by standardizing the dietary intakes of participants to global means, which were multiplied by the inflammatory effect score and summed. We examined associations of DII with maternal plasma C-reactive protein and white blood cell count in the second trimester and the following perinatal outcomes: gestational diabetes, preeclampsia, length of gestation, fetal growth, mode of delivery, and duration of breastfeeding. We used multivariable linear and logistic regression models to analyze the strength of these associations.

RESULTS

Maternal age was (mean ± SD) 32.2 ± 5.0 y, prepregnancy body mass index (BMI; in kg/m(2)) was 24.9 ± 5.2, and DII was -2.56 ± 1.42 units with a range of -5.4 to 3.7. DII was positively correlated with prepregnancy BMI (Pearson'sr= 0.13,P< 0.0001). Higher DII scores, reflecting more proinflammatory dietary potential, were associated with higher second-trimester plasma CRP (β: 0.08 mg/L per 1-unit increase in maternal DII; 95% CI: 0.02, 0.14) and lower birth weight for gestational agezscore in infants born to obese mothers (β: -0.10zscore per 1-unit increase in maternal DII; 95% CI: -0.18, -0.02). Higher DII scores were associated with lower odds of breastfeeding for at least 1 mo (OR = 0.85; 95% CI: 0.74, 0.98).

CONCLUSION

A proinflammatory diet during pregnancy is associated with maternal systemic inflammation and may be associated with impaired fetal growth and breastfeeding failure.

Antioxidant status and serum levels of selectins in pre-eclampsia

A cross-sectional study was conducted in a university hospital, enrolling 40 patients with pre-eclampsia (case group) and 40 healthy normotensive pregnant women (control group). Plasma activity of antioxidants and some adhesion molecules involved in oxidative stress were measured and compared between the two groups, according to the patients' age. In patients over the age of 30 years, serum levels of L-selectin and E-selectin were lower in pre-eclamptic patients (p < 0.05); antioxidants, catalase and superoxide dismutase did not significantly differ between the two groups, while glutathione peroxidase was significantly higher in the normotensive group (p < 0.05). In patients under the age of 30 years, E-selectin was significantly higher in the pre-eclampsia group (p < 0.05), while P-selectin, catalase and superoxide dismutase were not significantly different between the two groups (p > 0.05). Total antioxidative activity was similar between pre-eclamptic and normotensive patients (p > 0.05). This study revealed no relationship between total antioxidant activity and pre-eclampsia.

Oxidative stress markers in hypertensive states of pregnancy: preterm and term disease

Discussion continues as to whether de novo hypertension in pregnancy with significant proteinuria (pre-eclampsia; PE) and non-proteinuric new hypertension (gestational hypertension; GH) are parts of the same disease spectrum or represent different conditions. Non-pregnant hypertension, pregnancy and PE are all associated with oxidative stress. We have established a 6 weeks postpartum clinic for women who experienced a hypertensive pregnancy. We hypothesized that PE and GH could be distinguished by markers of oxidative stress; thiobarbituric acid reactive substances (TBARS) and antioxidants (ferric ion reducing ability of plasma; FRAP). Since the severity of PE and GH is greater pre-term, we also compared pre-term and term disease. Fifty-eight women had term PE, 23 pre-term PE, 60 had term GH and 6 pre-term GH, 11 pre-existing (essential) hypertension (EH) without PE. Limited data were available from normotensive pregnancies (n = 7) and non-pregnant controls (n = 14). There were no differences in postpartum TBARS or FRAP between hypertensive states; TBARS (P = 0.001) and FRAP (P = 0.009) were lower in plasma of non-pregnant controls compared to recently-pregnant women. Interestingly FRAP was higher in preterm than term GH (P = 0.013). In PE and GH, TBARS correlated with low density lipoprotein (LDL)-cholesterol (P = 0.036); this association strengthened with inclusion of EH (P = 0.011). The 10 year Framingham index for cardiovascular risk was positively associated with TBARS (P = 0.003). Oxidative stress profiles do not differ between hypertensive states but appear to distinguish between recently-pregnant and non-pregnant states. This suggests that pregnancy may alter vascular integrity with changes remaining 6 weeks postpartum. LDL-cholesterol is a known determinant of oxidative stress in cardiovascular disease and we have shown this association to be present in hypertensive pregnancy further emphasizing that such a pregnancy may be revealing a pre-existing cardiovascular risk.

Oxidative status shifts in uterine cervical incompetence patients

Uterine cervical incompetence (UCI) is a pregnancy complication affecting about 10% of the pregnancies in the western world. Studying the etiology of the UCI requires a specific approach adequate for this highly heterogenous syndrome. Oxidative status disorders are associated with various pathologies, including pregnancy complications. As such, general oxidative status profiling is a promising methodology to treat UCI. We aimed at assaying the closely interrelated oxidative status markers in the uterine cervical incompetence patients by means of the systems biology-oriented approach. Chemiluminescent assay, circulating thioredoxin 1 protein, uric acid, and homocysteine level measurements were used to assess the character of the oxidative status regulation in the UCI patients. We found UCI to be associated with the atypical plasma oxidative status deregulation; UCI plasma samples demonstrated lowered proneness to the pro-oxidative processes, and this was not due to the excessive antioxidant activity. There were neither signs of oxidative stress nor destructive pro-oxidant feedforward circuit locking in the UCI group. We also report increased circulating levels of uric acid in the UCI patients.

Thioredoxin-1 and oxidative stress status in pregnant women at early third trimester of pregnancy: relation to maternal and neonatal characteristics

This study examined the clinical and biological importance of thioredoxin-1, a redox-active defensive protein that controls multiple biological functions, in pregnant women. We measured serum concentrations of thioredoxin-1, total hydroperoxides, and redox potential in 60 pregnant women at the early third trimester: gestational age of 27-29 weeks. The thioredoxin-1 concentration (mean ± SD) was 90 ± 42 ng/ml. Total hydroperoxides was 471 ± 105 U.CARR (1 U.CARR = 0.08 mg/dl H(2)O(2)). Redox potential was 2142 ± 273 µmol/l. The total hydroperoxides: redox potential ratio (oxidative stress index) was 0.23 ± 0.08. Thioredoxin-1, total hydroperoxides, and oxidative stress index were higher and redox potential was lower than in blood of healthy adults. Total hydroperoxides and redox potential were mutually correlated significantly and negatively. Thioredoxin-1 correlated significantly and negatively and redox potential correlated significantly and positively with body weight and body mass index. Thioredoxin-1 and redox potential correlated significantly and positively with uric acid and albumin, respectively. Thioredoxin-1 and oxidative stress index correlated significantly and negatively and redox potential significantly and positively with neonatal birth weight. These results suggest that high concentrations of thioredoxin-1 are linked to high oxidative stress status in pregnant women and that neonatal birth weight is affected by the maternal oxidative condition during later pregnancy.

Linking preeclampsia and cardiovascular disease later in life

Preeclampsia (PE), which is defined as new onset hypertension after 20 weeks of pregnancy accompanied by proteinuria, is characterized by inadequate placentation, oxidative stress, inflammation and widespread endothelial dysfunction. A link between PE and long-term risk of cardiovascular disease (CVD) was suggested by retrospective studies, which found that PE was associated with a 2–3-fold risk of CVD later in life, with a 5–7-fold risk in the case of severe and/or early-onset PE. Recently, meta-analyses and prospective studies have confirmed the association between PE and the emergence of an unfavorable CVD risk profile, in particular a 3–5-fold increased prevalence of the metabolic syndrome only 8 years after the index pregnancy. PE and CVD share many risk factors, including obesity, hypertension, dyslipidemia, hypercoagulability, insulin resistance and both entities are characterized by endothelial dysfunction. PE and CVD are complex traits sharing common risk factors and pathophysiological processes, but the genetic link between both remains to be elucidated. However, recent evidence suggests that genetic determinants associated with the metabolic syndrome, inflammation and subsequent endothelial dysfunction are involved. As the evidence now supports that PE represents a risk factor for the emergence of the metabolic syndrome and CVD later in life, the importance of long-term follow-up assessment of CVD risk beginning early in women with a history of PE must be considered and translated into new preventive measures.

Effect of Ramadan fasting on maternal oxidative stress during the second trimester: a preliminary study

AIM

To evaluate whether fasting during Ramadan has any significant effects on maternal oxidative stress or fetal health in healthy, pregnant women with an uncomplicated, second-trimester, singleton pregnancy.

METHODS

During the month of Ramadan, 1-29 September 2008, 42 fasting and 30 non-fasting pregnant women were enrolled in this prospective controlled study. Total antioxidant status (TAS), total oxidant status (TOS) and the oxidative stress index (OSI) were measured from maternal serum samples taken on a fasting day during Ramadan. The two groups underwent routine follow-up examinations. At the end of the pregnancy, maternal complications, birth weight and maternal weight gain during the entire pregnancy were noted. To evaluate whether the duration of fasting days (≥10 or ≥15 days) had any significant effects on maternal oxidative stress, pregnant women who observed Ramadan for more than nine days or those who fasted for more than 14 days were compared with the control group in terms of TAS, TOS and OSI.

RESULTS

No significant differences were observed between the groups studied in terms of TAS, TOS, OSI, maternal age, gestational age, parity, birth weight or weight gain during the pregnancy. The TAS level was evaluated as significantly higher (P = 0.027) in the ≥10 fasting days group compared to the non-fasting control group, while there were no significant differences between the groups with respect to TOS and OSI.

CONCLUSION

Maternal fasting during Ramadan during the second trimester does not have a significant effect on maternal oxidative stress, fetal development or fetal birth weight.

Using isoprostanes as biomarkers of oxidative stress: some rarely considered issues

The measurement of F2-isoprostanes by methods utilizing mass spectrometry is widely regarded as the best currently available biomarker of lipid peroxidation. F2-isoprostanes and their metabolites can be measured accurately in plasma, urine, and other body fluids using mass spectrometric techniques, and detailed protocols have been published in several papers. However, many clinical studies and intervention studies with diets or supplements, have employed single "spot" measurements of F2-isoprostanes on either plasma/serum or urine to estimate "oxidative stress." This review examines the validity of the common assumption that plasma and urinary F2-isoprostane measurements are equivalent. It identifies scenarios where they may not be and where "spot" measurements can be misleading, with examples from the literature. We also discuss the controversial issue of whether and how F2-isoprostane levels in plasma should be standardized against lipids, and, if so, which lipids to use.

Periodontal disease, oxidative stress, and risk for preeclampsia

BACKGROUND

Maternal periodontal infection is associated with an increased risk for preeclampsia. Periodontal infection is also associated with increased oxidative stress. Our objective was to determine the relationship among maternal periodontal disease, maternal oxidative stress, and the development of preeclampsia.

METHODS

A secondary analysis of prospectively collected data from the Oral Conditions and Pregnancy Study was performed. A cohort of healthy women enrolled at <26 weeks of gestation underwent an oral examination, serum sampling, and delivery follow-up. A periodontal infection was categorized by clinical parameters as healthy or mild or moderate/severe periodontal infection. Preeclampsia was defined by the American Congress of Obstetricians and Gynecologists criteria as blood pressure >140/90 mmHg and >or=1+ proteinuria on a catheterized specimen. Maternal blood was assayed for 8-isoprostane concentrations using an enzyme-linked immunosorbent assay and stratified as elevated (>or=75th percentile) or not elevated (<75th percentile). Odds ratios (ORs) for preeclampsia were calculated and stratified by periodontal disease and the level of 8-isoprostane concentration.

RESULTS

A total of 34 (4.3%) of 791 women developed preeclampsia. Women with an 8-isoprostane concentration >or=75th percentile at enrollment were more likely to develop preeclampsia compared to women with an 8-isoprostane concentration <75th percentile (38.2% versus 24.4%, respectively; P = 0.07; OR: 1.91; 95% confidence interval [CI]: 0.94 to 3.90). Among women with moderate/severe periodontal disease, an elevated 8-isoprostane concentration (>or=75th percentile) did not significantly increase the likelihood for preeclampsia (adjusted OR: 2.08; 95% CI: 0.65 to 6.60).

CONCLUSIONS

Women with oxidative stress early in pregnancy, as measured by an 8-isoprostane concentration >or=75th percentile, were at an increased risk for developing preeclampsia. The presence of periodontal disease did not appear to modify this risk.

Adherence to walking or stretching, and risk of preeclampsia in sedentary pregnant women

Pregnant women at risk for preeclampsia may benefit from the positive effects of exercise, but they may be unlikely to adhere to an exercise program. A randomized trial was conducted with 124 sedentary pregnant women to compare the effects of walking exercise to a stretching exercise on adherence and on the preeclampsia risk factors of heart rate (HR), blood pressure, and weight gain. Walkers exercised less than stretchers both overall and as pregnancy advanced. HR and blood pressure were lower among stretchers than walkers, but weight gain did not differ between the groups. For sedentary pregnant women, a stretching exercise may be more effective than walking in mitigating the risk of preeclampsia due to higher adherence and possible cardiac-physiologic effects.

Oxidative stress and inflammatory markers in normal pregnancy and preeclampsia

AIM

Although previous investigators have demonstrated the presence of oxidative stress and inflammation in preeclampsia, none directly correlate both to preeclampsia.

METHODS

We determined in 35 preeclamptic and 35 normotensive pregnant women plasma levels of thiobarbituric acid reactive species, protein carbonyl, tumour necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), IL-6 and IL-10.

RESULTS

Plasma thiobarbituric acid reactive species and protein carbonyls were higher in preeclamptic patients. TNF-alpha and IL-6 (but not IL-1beta or IL-10) were higher in preeclamptic patients. We found significant correlation between plasma IL-6 and carbonyls, and these correlated to blood pressure.

CONCLUSIONS

We demonstrated that some oxidative and inflammatory mediators were altered in preeclampsia, and some correlated to blood pressure.

Iron behaving badly: inappropriate iron chelation as a major contributor to the aetiology of vascular and other progressive inflammatory and degenerative diseases

BACKGROUND

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular 'reactive oxygen species' (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation.

REVIEW

We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation).The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible.This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, since in some circumstances (especially the presence of poorly liganded iron) molecules that are nominally antioxidants can actually act as pro-oxidants. The reduction of redox stress thus requires suitable levels of both antioxidants and effective iron chelators. Some polyphenolic antioxidants may serve both roles.Understanding the exact speciation and liganding of iron in all its states is thus crucial to separating its various pro- and anti-inflammatory activities. Redox stress, innate immunity and pro- (and some anti-)inflammatory cytokines are linked in particular via signalling pathways involving NF-kappaB and p38, with the oxidative roles of iron here seemingly involved upstream of the IkappaB kinase (IKK) reaction. In a number of cases it is possible to identify mechanisms by which ROSs and poorly liganded iron act synergistically and autocatalytically, leading to 'runaway' reactions that are hard to control unless one tackles multiple sites of action simultaneously. Some molecules such as statins and erythropoietin, not traditionally associated with anti-inflammatory activity, do indeed have 'pleiotropic' anti-inflammatory effects that may be of benefit here.

CONCLUSION

Overall we argue, by synthesising a widely dispersed literature, that the role of poorly liganded iron has been rather underappreciated in the past, and that in combination with peroxide and superoxide its activity underpins the behaviour of a great many physiological processes that degrade over time. Understanding these requires an integrative, systems-level approach that may lead to novel therapeutic targets.

Does leisure time physical activity in early pregnancy protect against pre-eclampsia? Prospective cohort in Danish women

OBJECTIVE

To examine the association between physical activity in early pregnancy and risk of pre-eclampsia.

DESIGN

Prospective cohort.

SETTING

Denmark.

POPULATION

A total of 85,139 pregnant Danish women, recruited between 1996 and 2002.

METHODS

The authors assessed leisure time physical activity in first trimester by a telephone interview and categorised women a priori into seven groups: 0 (reference), 1-44, 45-74, 75-149, 150-269, 270-419 and 420+ minutes/week. Pre-eclampsia diagnoses were extracted from the Danish National Patient Registry. A number of potential confounders were adjusted for by logistic regression.

MAIN OUTCOME MEASURES

Pre-eclampsia and severe pre-eclampsia.

RESULTS

The two highest physical activity levels were associated with increased risk of severe pre-eclampsia compared with the nonexercising group, with adjusted odds ratios of 1.65 (95% CI: 1.11-2.43) and 1.78 (95% CI: 1.07-2.95), whereas more moderate levels of physical activity (1-270 minutes/week) had no statistically significant association with risk of pre-eclampsia (total n = 85,139).

CONCLUSIONS

We were unable to document a protective effect of leisure time physical activity against pre-eclampsia. Our data even suggest that leisure time physical activity exceeding 270 minutes/week in first trimester may increase risk of severe pre-eclampsia.

Placental anti-oxidant gene polymorphisms, enzyme activity, and oxidative stress in preeclampsia

The etiology and pathophysiology of preeclampsia are not fully understood. However, oxidative stress has been strongly linked to the occurrence of this multi-system disease. This has led to many theories of the pathogenesis of preeclampsia involving placental oxidative stress. In this study, we hypothesized that polymorphisms of anti-oxidant genes in the placental tissue contributed to susceptibility to preeclampsia. Polymorphisms in copper/zinc superoxide dismutase (CuZn-SOD), manganese superoxide dismutase (MnSOD), glutathione-S-transferase M1 (GSTM1), and glutathione-S-transferase T1 (GSTT1) in the umbilical cord tissue were assayed by polymerase chain reaction (PCR) in 23 nulliparous preeclampsia cases and 32 nulliparous normotensive controls. Corresponding enzyme activity levels and an oxidative stress biomarker (8-isoprostane) of the placental tissue were also measured. In addition, maternal plasma 8-isoprostane levels were also determined. Our results showed that no significant differences in polymorphism frequency of the tested genes, enzyme activity levels or 8-isoprostane levels in the placental tissue were detected between the cases and controls. However, maternal plasma 8-isoprostane level was significantly higher in the cases than in the controls (105.8 vs. 27.9 pg/ml, p=0.03). In conclusion, our study showed that polymorphisms of CuZn-SOD, MnSOD, GSTM1 and GSTT1 in the placental tissue were not associated with preeclampsia.

Low maternal concentrations of soluble vascular endothelial growth factor receptor-2 in preeclampsia and small for gestational age

OBJECTIVES

Preeclampsia is considered an anti-angiogenic state. A role for the anti-angiogenic factors soluble vascular endothelial growth factor receptor-1 (sVEGFR-1) and soluble endoglin in preeclampsia has been proposed. Soluble vascular endothelial growth factor receptor-2 (sVEGFR-2) has been detected in human plasma, and the recombinant form of this protein has anti-angiogenic activity. There is a paucity of information about maternal plasma sVEGFR-2 concentrations in patients with preeclampsia and those without preeclampsia with small for gestational age (SGA) fetuses. This study was conducted to determine whether: (1) plasma sVEGFR-2 concentration changes throughout pregnancy; and (2) preeclampsia and SGA are associated with abnormalities in the maternal plasma concentration of sVEGFR-2.

STUDY DESIGN

This cross-sectional study included non-pregnant women (n = 40), women with normal pregnancies (n = 135), women with an SGA fetus (n = 53), and women with preeclampsia (n = 112). SGA was defined as an ultrasound-estimated fetal weight below the 10(th) percentile for gestational age that was confirmed by neonatal birth weight. Plasma concentrations of sVEGFR-2 were determined by ELISA.

RESULTS

(1) There was no significant difference in the mean plasma concentration of sVEGFR-2 between non-pregnant women and those with normal pregnancies (p = 0.8); (2) patients with preeclampsia and those without preeclampsia with SGA fetuses had a lower mean plasma concentration of sVEGFR-2 than that of women with normal pregnancies (p < 0.001 for both); and (3) there was no significant difference in the mean plasma concentration of sVEGFR-2 between patients with preeclampsia and those without preeclampsia with SGA (p = 0.9).

CONCLUSIONS

Preeclampsia and SGA are associated with low plasma concentrations of sVEGFR-2. One interpretation of the findings is that plasma sVEGFR-2 concentration could reflect endothelial cell function.

Prediction of pre-eclampsia in early pregnancy

Pre-eclampsia is a multisystem disorder of pregnancy, usually characterized by the appearance of high blood pressure and the excretion of protein in the urine of a previously healthy woman. Symptoms and signs vary in intensity from woman to woman; from a borderline rise in blood pressure, to convulsions (eclampsia), stroke and death. The disease remits following removal of the placenta and so the mainstay of current treatment is timely delivery. A pathophysiological framework of the disease has been established, beginning with failures in placental development, inducing oxidative stress and release of compounds that lead to endothelial activation, vasoconstriction and glomerular endotheliosis. A combination of epidemiological, biophysical and biochemical tests now allow most patients at-risk to be identified by midpregnancy, whilst minimizing false-positive prediction. It is hoped that earlier classification of patients at-risk of the disease, on the basis of pathophysiological changes, will enable specific therapies to be developed targeting these changes.