Oxidative stress - Related spontaneous preterm delivery challenges in causality determination, prevention and novel strategies in reduction of the sequelae

Analysis of the evolution of placental oxidative stress research from a bibliometric perspective

Background

Research on placental oxidative stress is pivotal for comprehending pregnancy-related physiological changes and disease mechanisms. Despite recent advancements, a comprehensive review of current status, hotspots, and trends remains challenging. This bibliometric study systematically analyzes the evolution of placental oxidative stress research, offering a reference for future studies.

Objective

To conduct a comprehensive bibliometric analysis of the literature on placental oxidative stress to identify research hotspots, trends, and key contributors, thereby providing guidance for future research.

Methods

Relevant data were retrieved from the Web of Science Core Collection database and analyzed using VOSviewer, CiteSpace, and the bibliometrix package. An in-depth analysis of 4,796 publications was conducted, focusing on publication year, country/region, institution, author, journal, references, and keywords. Data collection concluded on 29 April 2024.

Results

A total of 4,796 papers were retrieved from 1,173 journals, authored by 18,835 researchers from 4,257 institutions across 103 countries/regions. From 1991 to 2023, annual publications on placental oxidative stress increased from 7 to 359. The United States (1,222 publications, 64,158 citations), the University of Cambridge (125 publications, 13,562 citations), and Graham J. Burton (73 publications, 11,182 citations) were the most productive country, institution, and author, respectively. The journal Placenta had the highest number of publications (329) and citations (17,152), followed by the International Journal of Molecular Sciences (122 publications). The most frequent keywords were "oxidative stress," "expression," "pregnancy," "preeclampsia," and "lipid peroxidation." Emerging high-frequency keywords included "gestational diabetes mellitus," "health," "autophagy," "pathophysiology," "infection," "preterm birth," "stem cell," and "inflammation."

Conclusion

Over the past 3 decades, research has concentrated on oxidative stress processes, antioxidant mechanisms, pregnancy-related diseases, and gene expression regulation. Current research frontiers involve exploring pathophysiology and mechanisms, assessing emerging risk factors and environmental impacts, advancing cell biology and stem cell research, and understanding the complex interactions of inflammation and immune regulation. These studies elucidate the mechanisms of placental oxidative stress, offering essential scientific evidence for future intervention strategies, therapeutic approaches, and public health policies.

Development of a spontaneous preterm birth predictive model using a panel of serum protein biomarkers for early pregnant women: A nested case-control study

OBJECTIVE

To develop a model based on maternal serum liquid chromatography tandem mass spectrometry (LC-MS/MS) proteins to predict spontaneous preterm birth (sPTB).

METHODS

This nested case-control study used the data from a cohort of 2053 women in China from July 1, 2018, to January 31, 2019. In total, 110 singleton pregnancies at 11-13+6 weeks of pregnancy were used for model development and internal validation. A total of 72 pregnancies at 20-32 weeks from an additional cohort of 2167 women were used to evaluate the scalability of the model. Maternal serum samples were analyzed by LC-MS/MS, and a predictive model was developed using machine learning algorithms.

RESULTS

A novel predictive panel with four proteins, including soluble fms-like tyrosine kinase-1, matrix metalloproteinase 8, ceruloplasmin, and sex-hormone-binding globulin, was developed. The optimal model of logistic regression had an AUC of 0.934, with additional prediction of sPTB in second and third trimester (AUC = 0.868).

CONCLUSION

First-trimester modeling based on maternal serum LC-MS/MS identifies pregnant women at risk of sPTB, which may provide utility in identifying women at risk at an early stage of pregnancy before clinical presentation to allow for earlier intervention.

The protective effects of Ferrostatin-1 against inflammation-induced preterm birth and fetal brain injury

INTRODUCTION

Recent studies have suggested the involvement of ferroptosis in preterm birth. Despite compelling evidence, the underlying mechanism remains unknown. This investigation aimed to determine the therapeutic effects of Ferrostatin-1 (Fer-1), an inhibitor of ferroptosis, in preterm birth and fetal brain injury.

METHODS

Human placenta samples and clinical data of participants were collected to ascertain whether placental ferroptosis was associated with preterm birth. Lipopolysaccharide (LPS)-induced preterm birth mouse model was used to examine the protective effects of Fer-1 on preterm birth. Fetal brain tissues and offspring mice at 5 and 8 weeks were studied to determine the effects of Fer-1 on the cognitive function of offspring.

RESULTS

We examined the mechanism of spontaneous preterm birth and discovered that placental ferroptosis was associated with preterm birth. Fer-1 inhibited preterm birth by ameliorating placental ferroptosis and maternal inflammation, thus improving LPS-induced intrauterine inflammation to maintain pregnancy. Antenatal administration of Fer-1 prevented LPS-induced fetal brain damage in the acute phase and improved long-term neurodevelopmental impairments by improving placental neuroendocrine signaling and maintaining placental function.

CONCLUSION

Fer-1 inhibited preterm birth and fetal brain injury by inhibiting maternal inflammation and improving placental function. Our findings provide a novel therapeutic strategy for preterm birth.

Association between light rare earth elements in maternal plasma and the risk of spontaneous preterm birth: a nested case-control study from the Beijing birth cohort study

BACKGROUND

Parental exposure to rare earth elements (REEs) could increase the risk of premature rupture of membranes, a major cause of spontaneous preterm birth (SPB). In addition, different subtypes of SPB, such as spontaneous preterm labor (SPL) and preterm premature rupture of membranes (PPROM), may have different susceptibility to environmental exposure. Therefore, we investigated the potential associations between REE exposure in different trimesters and SPB and its subtypes.

METHODS

A nested case-control study was performed. We included 244 women with SPB as cases and 244 women with full-term delivery as controls. The plasma concentrations of light REEs were measured in the first and third trimesters. Logistic regression was used to analyze the associations between single REE levels and SPB, and Bayesian kernel machine regression (BKMR) was used to analyze the mixed-exposure effect.

RESULTS

Exposure to light REEs was associated with SPB and its subtypes only in the third trimester. Specifically, the intermediate- and highest-tertile concentration groups of La and the highest-tertile concentration group of Sm were associated with an increased risk of SPL, with adjusted odds ratios (AORs) of 2.00 (95% CIs: 1.07-3.75), 1.87 (95% CIs: 1.01-3.44), and 1.82 (95% CIs: 1.00-3.30), respectively. The highest-tertile concentration group of Pr was associated with an increased risk of PPROM, with an AOR of 1.69 (95% CIs: 1.00-2.85). Similar results were also found in BKMR models.

CONCLUSIONS

La and Sm levels in plasma may be associated with the risk of SPL, and Pr levels in plasma may be associated with the risk of PPROM.

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.

Effects of selenium levels on placental oxidative stress and inflammation during pregnancy: a prospective cohort study

BACKGROUND

Studies on the impact of Se levels in different pregnancy periods on placental function are limited.

AIM

This cohort study sought to investigate the levels of the trace element Se and to assess their effects on placental oxidative stress (OS) and mRNA expression of inflammatory genes during pregnancy.

METHODS

The study population consisted of 2519 pregnant women from the Ma'anshan birth cohort. Se levels were measured in the first and second trimesters of pregnancy and in cord blood using inductively coupled plasma-mass spectrometry (ICP-MS). Placental stress and mRNA expression of inflammatory genes were assessed using RT-PCR.

RESULTS

A statistically significant negative association was noted between Se levels in the second trimester of pregnancy and mRNA expression of placental HO-1(β = -0.009, p < .01), HIF1α (β = -0.005, p = .010), GRP78 (β = -0.011, p < .001), CRP (β = -.007, p = .033) and CD68 (β = -0.006, p = .019). A negative association was noted between Se levels in cord blood and mRNA expression of placental HO-1 (β = -0.007, p = .004), HIF1α (β = -0.006, p = .005) and GRP78 (β = -0.009, p = .004). We found that prenatal Se status was associated with placental stress and mRNA expression of inflammatory genes.

CONCLUSION

Se deficiency during pregnancy, especially in the second trimester, leads to the production of OS and an increase in inflammatory mediators, affecting the growth and development of the fetus. Monitoring of pregnant women's nutritional status is necessary to prevent nutritional imbalances and deficiencies in important micronutrients in the fetal.

Associations between blood heavy metal(loid)s and serum heme oxygenase-1 in pregnant women: Do their distribution patterns matter?

The relationship between heavy metal(loid)s exposure and oxidative stress damage is a matter of research interest. Our study aimed to investigate the distribution patterns of the nine heavy metal(loid)s in blood of pregnant women, including four toxic heavy metal(loid)s [arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg)] and five typical heavy metal(loid)s [manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn), and selenium (Se)] in blood. Blood samples of 348 women were collected and their concentrations in the serum (sr) and blood cells (bc) were measured, as well as serum heme oxygenase-1 (HO-1) (an oxidative stress marker). Total blood (tb) concentrations of these metal(loid)s and serum-to-blood cell concentration ratios (sr/bc) were further calculated. We found Cu mainly accumulated in the serum compared to the blood cells with Cu^sr/bc = 2.30, whereas Co, Se, and As evenly distributed between these two fractions. Other metal(loid)s mainly concentrated in the blood cells. Co^sr, Cu^sr, Cu^bc, Mn^bc, Zn^bc, Cd^bc, Co^tb, Cu^tb, Mn^tb, Zn^tb, Cd^tb, and Cu^sr/bc were negatively associated with serum HO-1, whereas As^sr, As^bc, As^tb, Zn^sr/bc, Cd^sr/bc, and Hg^sr/bc were positively, indicating of their potential toxicity. We concluded that the distribution patterns of blood heavy metal(loid)s, in particular for Cd, Hg and Zn, which either increased in serum or decreased in blood cells, might be associated with elevated serum oxidative stress, should be considered in environmental health assessments.

Effect of Endogenic and Exogenic Oxidative Stress Triggers on Adverse Pregnancy Outcomes: Preeclampsia, Fetal Growth Restriction, Gestational Diabetes Mellitus and Preterm Birth

Oxidative stress is caused by an imbalance between the production of reactive oxygen species (ROS) in cells and tissues and the ability of a biological system to detoxify them. During a normal pregnancy, oxidative stress increases the normal systemic inflammatory response and is usually well-controlled by the balanced body mechanism of the detoxification of anti-oxidative products. However, pregnancy is also a condition in which this adaptation and balance can be easily disrupted. Excessive ROS is detrimental and associated with many pregnancy complications, such as preeclampsia (PE), fetal growth restriction (FGR), gestational diabetes mellitus (GDM), and preterm birth (PTB), by damaging placentation. The placenta is a tissue rich in mitochondria that produces the majority of ROS, so it is important to maintain normal placental function and properly develop its vascular network to ensure a safe and healthy pregnancy. Antioxidants may ameliorate these diseases, and related research is progressing. This review aimed to determine the association between oxidative stress and adverse pregnancy outcomes, especially PE, FGR, GDM, and PTB, and explore how to overcome this oxidative stress in these unfavorable conditions.

Praegnatio Perturbatio-Impact of Endocrine-Disrupting Chemicals

The burden of adverse pregnancy outcomes such as preterm birth and low birth weight is considerable across the world. Several risk factors for adverse pregnancy outcomes have been identified. One risk factor for adverse pregnancy outcomes receiving considerable attention in recent years is gestational exposure to endocrine-disrupting chemicals (EDCs). Humans are exposed to a multitude of environmental chemicals with known endocrine-disrupting properties, and evidence suggests exposure to these EDCs have the potential to disrupt the maternal-fetal environment culminating in adverse pregnancy and birth outcomes. This review addresses the impact of maternal and fetal exposure to environmental EDCs of natural and man-made chemicals in disrupting the maternal-fetal milieu in human leading to adverse pregnancy and birth outcomes-a risk factor for adult-onset noncommunicable diseases, the role lifestyle and environmental factors play in mitigating or amplifying the effects of EDCs, the underlying mechanisms and mediators involved, and the research directions on which to focus future investigations to help alleviate the adverse effects of EDC exposure.

Measuring the status of maternal serum thiol/disulfide couples in the diagnosis and/or the determination of the severity of late-onset preeclampsia

OBJECTIVE

Preeclampsia (PrE) is a pregnancy-related disorder. PrE affects the health of the mother and/or the fetus binomial with short and/or long-term consequences. The role of oxidant/antioxidant molecules and aberrant maternal inflammation in PrE has been documented. However, the importance of antioxidant molecules such as thiols has been poorly documented. In this research, a possible link between serum thiols levels and the diagnosis/severity of late-onset PrE (L-PrE) was investigated.

MATERIALS AND METHODS

We examined maternal serum native thiols, disulfide, total thiols levels, and their ratios in pregnant women with (n = 51) and without L-PrE (n = 50). The levels of these three markers were measured using spectrophotometric assays and compared.

RESULTS

There were significant differences in terms of serum native and total thiols levels between patients with L-PrE and healthy pregnant women (p = .001, p = .008, respectively). Disulfide levels were not different in either group (p = 0.729). There was no difference between total thiols, native thiols, disulfide concentrations, and their ratios in patients with mild (23 patients) and severe (27 patients) preeclampsia in L-PrE (p ≥ .05). A significant discriminative role of native and total thiols for the presence of L-PrE, with cutoff values of 175.86 μmol/L and 296.73 μmol/L, respectively, were revealed in ROC curve analysis.

CONCLUSIONS

Lower concentrations of total/native thiols were linked with the development of L-PrE. However, there is still a need for more clinically useful biomarkers/molecules and management strategies in PrE.

Oxidative Stress in Preterm Infants: Overview of Current Evidence and Future Prospects

Preterm birth (PTB), defined as parturition prior to 37 weeks of gestation, is the leading cause of morbidity and mortality in the neonatal population. The incidence and severity of complications of prematurity increase with decreasing gestational age and birthweight. The aim of this review study is to select the most current evidence on the role of oxidative stress in the onset of preterm complication prevention strategies and treatment options with pre-clinical and clinical trials. We also provide a literature review of primary and secondary studies on the role of oxidative stress in preterm infants and its eventual treatment in prematurity diseases. We conducted a systematic literature search of the Medline (Pubmed), Scholar, and ClinicalTrials.gov databases, retroactively, over a 7-year period. From an initial 777 articles identified, 25 articles were identified that met the inclusion and exclusion criteria. Of these, there were 11 literature reviews: one prospective cohort study, one experimental study, three case-control studies, three pre-clinical trials, and six clinical trials. Several biomarkers were identified as particularly promising, such as the products of the peroxidation of polyunsaturated fatty acids, those of the oxidation of phenylalanine, and the hydroxyl radicals that can attack the DNA chain. Among the most promising drugs, there are those for the prevention of neurological damage, such as melatonin, retinoid lactoferrin, and vitamin E. The microbiome also has an important role in oxidative stress. In conclusion, the most recent studies show that a strong relationship between oxidative stress and prematurity exists and that, unfortunately, there is still little therapeutic evidence reported in the literature.

Nanosystems of plant-based pigments and its relationship with oxidative stress

Plant-based pigments are widely present in nature, they are classified depending on their chemical structure as tetrapyrroles, carotenoids, polyphenolic compounds, and alkaloids and are extensively used in medicine, food industry, clothes, and others. Recently they have been investigated due to their role in the areas of food processing, food safety and quality, packaging, and nutrition. Many studies indicate a relationship between bioactive pigments and Non-Communicable Diseases derived from oxidative stress. Their biological applications can help in preventing oxidative injuries in the cell caused by oxygen and nitrogen reactive species. Those pigments are easily degraded by light, oxygen, temperature, pH conditions, among others. Nanotechnology offers the possibility to protect bioactive ingredients and increase its bioavailability after oral administration. Safety to humans (mainly evaluated from toxicity data) is the first concern for these products. In the present work, we present a comprehensive outlook of the most important plant-based pigments used as food colorants, the principal nanotechnology systems prepared with them, and the relationship of these compounds with the oxidative stress and related Non-Communicable Disease.

Extracellular vesicles in normal pregnancy and pregnancy-related diseases

Extracellular vesicles (EVs) are nanosized, membranous vesicles released by almost all types of cells. Extracellular vesicles can be classified into distinct subtypes according to their sizes, origins and functions. Extracellular vesicles play important roles in intercellular communication through the transfer of a wide spectrum of bioactive molecules, contributing to the regulation of diverse physiological and pathological processes. Recently, it has been established that EVs mediate foetal‐maternal communication across gestation. Abnormal changes in EVs have been reported to be critically involved in pregnancy‐related diseases. Moreover, EVs have shown great potential to serve as biomarkers for the diagnosis of pregnancy‐related diseases. In this review, we discussed about the roles of EVs in normal pregnancy and how changes in EVs led to complicated pregnancy with an emphasis on their values in predicting and monitoring of pregnancy‐related diseases.