Pregnancy, preeclampsia and maternal aging: From epidemiology to functional genomics

Pregnancy-induced metabolic reprogramming and regenerative responses to pro-aging stresses

Pregnancy is associated with physiological adaptations that affect virtually all organs, enabling the mother to support the growing fetus and placenta while withstanding the demands of pregnancy. As a result, mammalian pregnancy is a unique state that exerts paradoxical effects on maternal health. On one hand, the metabolic stress induced by pregnancy can accelerate aging and functional decline in organs. On the other hand, pregnancy activates metabolic programming and tissue regenerative responses that can reverse age-related impairments. In this sense, the oocyte-to-blastocyst transition is not the only physiological reprogramming event in the mammalian body, as pregnancy-induced regeneration could constitute a second physiological reprogramming event. Here, we review findings on how pregnancy dualistically leads to aging and rejuvenation in the maternal body.

LINC01410 accelerates the invasion of trophoblast cells by modulating METTL3/Fas

BACKGROUND

Insufficient trophoblast invasion, culminating in suboptimal uterine spiral artery remodeling, is pinpointed as a pivotal contributor to preeclampsia (PE) development. LINC01410 has been documented to be increased in various neoplasms, and is significantly associated with the invasive capabilities of tumor cells. Nonetheless, its function and the mechanisms in the pathogenesis of PE require further investigation.

METHODS AND RESULTS

LINC01410 and methyltransferase-like 3 (METTL3) were ectopically expressed in HTR-8/Svneo cells via lentiviral transduction. Subsequently, the cells' invasive capabilities and apoptosis rates were evaluated employing Transwell assays and flow cytometry, respectively. The interplay between LINC01410 and METTL3, alongside the m6A methylation of FAS, was probed through RNA immunoprecipitation (RIP). Additionally, the association between FAS and METTL3 was elucidated via Coimmunoprecipitation (Co-IP) assays. The protein level of NF-κB, BAX, and BCL-2 in LINC01410-overexpressing cells was detected by Western blot. Our findings revealed that LINC01410 elevation increased the invasive ability of HTR-8/Svneo cells, directly impacting METTL3 then leading to its reduced expression. Conversely, heightened METTL3 expression mitigated invasiveness while enhancing apoptosis in these cells. Moreover, METTL3's interaction with FAS led to increased FAS expression, subject to m6A methylation. A surge in LINC01410 markedly decreased both mRNA and protein levels of FAS. Furthermore, LINC01410 overexpression significantly reduced NF-κB and BAX protein levels while augmenting BCL-2.

CONCLUSIONS

Upregulation of LINC01410 expression promotes trophoblast cell invasion by inhibiting FAS levels through modified m6A alteration and suppressing the NF-κB pathway. These findings underscore the pivotal role of LINC01410 in regulating trophoblast cell invasion and propose it as a promising therapeutic strategy for preventing or alleviating PE. This offers valuable insights for the clinical treatment of PE, for which definitive targeted therapy methods are currently lacking.

Thrombin in Pregnancy and Preeclampsia: Expression, Localization, and Vasoactivity in Brain and Microvessels From Rats

ABSTRACT

Thrombin is a coagulation factor increased in pregnancy and further increased in preeclampsia (PE), a hypertensive disorder. Thrombin is also expressed in the brain and may have a nonhemostatic role. We characterized thrombin expression and vasoactivity in brain cerebral parenchymal arterioles (PAs) in rat models of pregnancy and PE. PAs were isolated and pressurized from nonpregnant (NP) and late-pregnant (LP) rats and rats with experimental preeclampsia (ePE). Reactivity to thrombin (1-50 U/mL) was measured in the absence and presence of inhibition of cyclooxygenase and nitric oxide synthase. Plasma levels of prothrombin, thrombin-antithrombin (TAT), tissue plasminogen activator, and plasminogen activator inhibitor-1 (PAI-1) and cerebrospinal fluid levels of TAT were compared using enzyme-linked immunosorbent assay. Expression of protease-activated receptor types 1 and 2 in PAs were measured by Western blot and immunohistochemistry. Neuronal thrombin expression was quantified in brains from all groups by immunohistochemistry. Prothrombin and TAT were elevated in ePE plasma compared with NP and LP. TAT was detected in cerebrospinal fluid from all groups and significantly elevated in LP (NP: 0.137 ± 0.014 ng/mL, LP: 0.241 ± 0.015 ng/mL, ePE: 0.192 ± 0.028 ng/mL; P < 0.05). Thrombin caused modest vasoconstriction in PAs from all groups regardless of cyclooxygenase or nitric oxide synthase inhibition. PAR1 and PAR2 were found in PAs from all groups colocalized to smooth muscle. Thrombin expression in central neurons was decreased in both LP and ePE groups compared with NP. These findings suggest a role for thrombin and other hemostatic changes during pregnancy and PE beyond coagulation.

Inhibition of autophagy via 3-methyladenine alleviates the progression of preeclampsia

Autophagy is a cellular mechanism for self-renewal that involves the breakdown of cytoplasmic proteins or organelles within lysosomes. Although preeclampsia (PE) exhibits several characteristics that could imply disrupted autophagy, there is limited evidence supporting the notion that impaired placental autophagy directly causes PE, as indicated by differential expression profiling of whole placental tissue. In this study, we aim to explore the significance of autophagy in maintaining pregnancy and its association with PE. First, the RNA-seq results show that 218 genes are differentially expressed in placentas from preeclamptic pregnancies. Notably, KEGG pathway analysis reveals significant enrichment of genes related to autophagy-related signaling pathways, including the PI3K-Akt signaling pathway, the AMPK signaling pathway, and the mTOR signaling pathway. Additionally, our findings indicate an increase in autophagy in placentas from pregnancies complicated by preeclampsia as well as in trophoblasts subjected to hypoxic conditions. Next, we examine the impact of 3-methyladenine (3-MA), a targeted inhibitor of autophagy, on the progression of PE. The administration of 3-MA profoundly alleviates the severity of PE-like symptoms in rats subjected to reduced uterine perfusion pressure (RUPP). The findings from our study suggest that inhibiting autophagy may serve as a promising approach for adjuvant chemotherapy for PE.

Mechanistic study of pre-eclampsia and macrophage-associated molecular networks: bioinformatics insights from multiple datasets

Background

Pre-eclampsia is a pregnancy-related disorder characterized by hypertension and proteinuria, severely affecting the health and quality of life of patients. However, the molecular mechanism of macrophages in pre-eclampsia is not well understood.

Methods

In this study, the key biomarkers during the development of pre-eclampsia were identified using bioinformatics analysis. The GSE75010 and GSE74341 datasets from the GEO database were obtained and merged for differential analysis. A weighted gene co-expression network analysis (WGCNA) was constructed based on macrophage content, and machine learning methods were employed to identify key genes. Immunoinfiltration analysis completed by the CIBERSORT method, R package "ClusterProfiler" to explore functional enrichment of these intersection genes, and potential drug predictions were conducted using the CMap database. Lastly, independent analysis of protein levels, localization, and quantitative analysis was performed on placental tissues collected from both preeclampsia patients and healthy control groups.

Results

We identified 70 differentially expressed NETs genes and found 367 macrophage-related genes through WGCNA analysis. Machine learning identified three key genes: FNBP1L, NMUR1, and PP14571. These three key genes were significantly associated with immune cell content and enriched in multiple signaling pathways. Specifically, these genes were upregulated in PE patients. These findings establish the expression patterns of three key genes associated with M2 macrophage infiltration, providing potential targets for understanding the pathogenesis and treatment of PE. Additionally, CMap results suggested four potential drugs, including Ttnpb, Doxorubicin, Tyrphostin AG 825, and Tanespimycin, which may have the potential to reverse pre-eclampsia.

Conclusion

Studying the expression levels of three key genes in pre-eclampsia provides valuable insights into the prevention and treatment of this condition. We propose that these genes play a crucial role in regulating the maternal-fetal immune microenvironment in PE patients, and the pathways associated with these genes offer potential avenues for exploring the molecular mechanisms underlying preeclampsia and identifying therapeutic targets. Additionally, by utilizing the Connectivity Map database, we identified drug targets like Ttnpb, Doxorubicin, Tyrphostin AG 825, and Tanespimycin as potential clinical treatments for preeclampsia.

Raised levels of chemerin in women with preeclampsia: A meta-analysis

Chemerin is a multifunctional adipokine associated with systemic inflammation, angiogenesis, and oxidative stress. Emerging evidence suggests a potential link between chemerin and the pathogenesis of preeclampsia (PE). In this systematic review and meta-analysis, we aimed to evaluate the serum chemerin levels in women with PE. A systematic search was conducted across Medline, Web of Science, and Embase databases from inception until April 15, 2023, to identify studies comparing serum chemerin levels in pregnant women with and without PE. A random-effects model was employed to pool the results, accounting for heterogeneity. Thirteen datasets from 10 observational studies, encompassing 832 women with PE and 1298 healthy pregnant women, were analyzed. The pooled findings indicated a statistically significant elevation in serum chemerin levels in women with PE compared to controls (mean difference [MD] = 89.56 ng/mL, 95% confidence interval [CI] 62.14 - 116.98; P < 0.001; I2 = 87%). The subgroup analysis revealed consistent findings across studies that measured chemerin levels before or after the diagnosis of PE, studies that did or did not match the body mass index (BMI), and studies with varying quality scores (P values for subgroup differences were all > 0.05). Compared to controls, women with severe PE exhibited a significantly greater increase in serum chemerin levels than those with mild PE (P value for subgroup difference = 0.007). Additionally, meta-regression analysis results suggested that the mean BMI of the included pregnant women might positively modify the difference in circulating chemerin levels between women with and without PE (coefficient = 8.92; P = 0.045). In conclusion, this meta-analysis suggests a positive correlation between elevated serum chemerin levels and PE diagnosis in comparison to pregnant women without the condition.

SFRP2 suppresses trophoblast cell migration by inhibiting the Wnt/β‑catenin pathway

The present study investigates the role of Secreted Frizzled‑Related Protein 2 (SFRP2) in trophoblast cells, a key factor in preeclampsia (PE) progression. Elevated levels of Secreted Frizzled‑Related Protein 1/3/4/5 (SFRP1/3/4/5) are associated with PE, but the role of SFRP2 is unclear. We analyzed SFRP2 expression in PE placental tissue using the GSE10588 dataset and overexpressed SFRP2 in JEG‑3 cells via lentiviral transfection. The viability, migration, apoptosis, and proliferation of SFRP2‑overexpressing JEG‑3 cells were assessed using Cell Counting Kit‑8, Transwell assays, flow cytometry, and EdU staining. Additionally, we evaluated the impact of SFRP2 overexpression on key proteins in the Wnt/β‑catenin pathway and apoptosis markers (Bax, cleaved‑caspase 3, BCL‑2, MMP9, E‑cadherin, Wnt3a, Axin2, CyclinD1, c‑Myc, p‑β‑catenin, β‑catenin, phosphorylated Glycogen Synthase Kinase 3 beta (p‑GSK3β), and GSK3β) through western blotting. Results showed high SFRP2 mRNA and protein expression in PE placenta and JEG‑3 cells post‑transfection. SFRP2 overexpression significantly reduced JEG‑3 cell viability, proliferation, and migration, while increasing apoptosis. It also altered expression levels of Wnt pathway proteins, suggesting SFRP2's potential as a therapeutic target for PE by inhibiting trophoblast cell migration through the Wnt/β‑catenin signaling cascade.

Exploring the role of exosomal MicroRNAs as potential biomarkers in preeclampsia

The complex pathogenesis of preeclampsia (PE), a significant contributor to maternal and neonatal mortality globally, is poorly understood despite substantial research. This review explores the involvement of exosomal microRNAs (exomiRs) in PE, focusing on their impact on the protein kinase B (AKT)/hypoxia-inducible factor 1-α (HIF1α)/vascular endothelial growth factor (VEGF) signaling pathway as well as endothelial cell proliferation and migration. Specifically, this article amalgamates existing evidence to reveal the pivotal role of exomiRs in regulating mesenchymal stem cell and trophoblast function, placental angiogenesis, the renin-angiotensin system, and nitric oxide production, which may contribute to PE etiology. This review emphasizes the limited knowledge regarding the role of exomiRs in PE while underscoring the potential of exomiRs as non-invasive biomarkers for PE diagnosis, prediction, and treatment. Further, it provides valuable insights into the mechanisms of PE, highlighting exomiRs as key players with clinical implications, warranting further exploration to enhance the current understanding and the development of novel therapeutic interventions.

Protein Misfolding in Pregnancy: Current Insights, Potential Mechanisms, and Implications for the Pathogenesis of Preeclampsia

Protein misfolding disorders are a group of diseases characterized by supra-physiologic accumulation and aggregation of pathogenic proteoforms resulting from improper protein folding and/or insufficiency in clearance mechanisms. Although these processes have been historically linked to neurodegenerative disorders, such as Alzheimer's disease, evidence linking protein misfolding to other pathologies continues to emerge. Indeed, the deposition of toxic protein aggregates in the form of oligomers or large amyloid fibrils has been linked to type 2 diabetes, various types of cancer, and, in more recent years, to preeclampsia, a life-threatening pregnancy-specific disorder. While extensive physiological mechanisms are in place to maintain proteostasis, processes, such as aging, genetic factors, or environmental stress in the form of hypoxia, nutrient deprivation or xenobiotic exposures can induce failure in these systems. As such, pregnancy, a natural physical state that already places the maternal body under significant physiological stress, creates an environment with a lower threshold for aberrant aggregation. In this review, we set out to discuss current evidence of protein misfolding in pregnancy and potential mechanisms supporting a key role for this process in preeclampsia pathogenesis. Improving our understanding of this emerging pathophysiological process in preeclampsia can lead to vital discoveries that can be harnessed to create better diagnoses and treatment modalities for the disorder.

WD repeat domain 5 promotes the development of late-onset preeclampsia by activating nuclear factor kappa B

PURPOSE

Over-activation of nuclear factor kappa B (NF-κB) was proven to be involved in the pathogenesis of preeclampsia. However, its regulation mechanism is not clear yet. This paper explored the role of WD repeat domain 5 (WDR5) in the development of late-onset preeclampsia and its relationship with NF-κB.

METHODS

WDR5 expression was detected in normal placentas and placentas from late-onset preeclampsia patients. CCK-8 and colony formation assays were conducted to appraise the proliferative ability of trophoblast. Migration and invasion were observed by wound healing and transwell assays. The interaction between WDR5 and NF-κB inhibitor I-kappa-B-alpha (IkBa) was verified by Co-immunoprecipitation analysis. Immunofluorescence was used to analyze the activation of NF-κB. Finally, we tested the role of WDR5 using the mice late-onset preeclampsia model.

RESULTS

WDR5 was highly expressed in the placentas of late-onset preeclampsia patients. WDR5 overexpression suppressed cell proliferation, migration, and invasion in trophoblast. WDR5 could interact with IkBa to activate NF-κB. Knockdown of NF-κB counteracted the anti-proliferative and anti-metastatic effects of WDR5 overexpression in trophoblast. In-vivo studies suggested that targeting WDR5 combated late-onset preeclampsia development.

CONCLUSIONS

Our finding provides new insights into the role of WDR5 in late-onset preeclampsia development.

Parity and Risk of Dementia in Women: The Atherosclerosis Risk in Communities Study

Objective: Reproductive factors, including parity, may contribute to dementia risk, due to hormonal, physiological, social, and demographic factors. We hypothesized that higher parity would be associated with increased dementia risk. Materials and Methods: We utilized data from the Atherosclerosis Risk in Communities (ARIC) community-based cohort study. Participants were recruited in 1987-1989 and followed through 2017. Participants, all born between 1921 and 1945, were from four U.S. communities in Forsyth County, NC; Jackson, MS; Minneapolis, MN; and Washington County, MD. We included all female participants seen at ARIC visit three or five for whom parity and dementia outcomes were available (N = 7,921). The primary exposure was self-reported number of live births. Our primary outcome was dementia, diagnosed via neurocognitive assessments, informant interviews, and expert adjudication. We created Cox proportional hazards models to evaluate the association between parity and incident dementia, adjusting for demographic factors, education level, apolipoprotein E allele status, and vascular risk factors. We tested for interactions by race and birth cohort. Results: The adjusted hazard ratio was 0.82 (95% confidence intervals [CI] 0.69-0.99) for dementia in women with 0-1 births and 0.85 (95% CI 0.72-0.99) for women with 5+ births, compared to women with 2 births (reference group). This association was present in women born from 1924 to 1934, but not in women born in 1935 or later (p-interaction <0.001). Conclusion: We found an inverted U-shaped association of parity with dementia risk. This effect was modified by birth cohort, suggesting that the association may depend on demographic and sociocultural factors.

Reproductive aging: biological pathways and potential interventive strategies

Reproductive aging is a natural process conserved across species and is well-known in females. It shows age-related follicle depletion and reduction of oocyte quality, eventually causing reproductive senescence and menopause. Although reproductive aging in males is not well noticed as in females, it also causes infertility and has deleterious consequences on the offspring. Various factors have been suggested to contribute to reproductive aging, including oxidative stress, mitochondrial defects, telomere shortening, meiotic chromosome segregation errors and genetic alterations. With the increasing trend of pregnancy age, it is particularly crucial to find interventions to preserve or extend human fertility. Studies in humans and model organisms have provided insights into the biological pathways associated with reproductive aging, and a series of potential interventive strategies have been tested. Here, we review factors affecting reproductive aging in females and males and summarize interventive strategies that may help delay or rescue the aging phenotypes of reproduction.

Circulating Growth Differentiation Factor 15 and Preeclampsia: A Meta-Analysis

Growth differentiation factor 15 (GDF-15) has been suggested as a potential biomarker of preeclampsia. However, previous studies evaluating circulating GDF-15 in women with preeclampsia showed inconsistent results. A meta-analysis was performed accordingly in this study. Observational studies comparing circulating GDF-15 between women with preeclampsia normal pregnancy were identified by search of electronic databases including PubMed, Embase, Web of Science, Wanfang, and CNKI. The Newcastle-Ottawa Scale (NOS) was used for assessing the quality of the studies. A randomized-effect model incorporating the possible between-study heterogeneity was used to pool the results. Eleven observational studies including 498 women with preeclampsia and 2349 women with normal pregnancy contributed to the meta-analysis. Results showed that compared to controls of women with normal pregnancy at least matched for gestational ages, women with preeclampsia had significantly higher circulating GDF-15 at the diagnosis [standard mean difference (SMD): 0.66, 95% confidence interval (CI): 0.16 to 1.17, p=0.01, I2=93%]. Subgroup analysis showed consistent results in women with preterm and term preeclampsia in Asian and non-Asian women and in studies with different quality scores, which were not statistically significant between subgroups (p for subgroup difference>0.05). Moreover, a higher level of GDF-15 was also found before the diagnosis in women who subsequently developed preeclampsia than those who did not (SMD: 1.32, 95% CI: 0.45 to 2.18, p=0.003, I2=89%). In conclusion, a higher circulating GDF-15 is observed in women with preeclampsia even before the diagnosis of the disease.

Hypertensive disorders of pregnancy share common cfDNA methylation profiles

Hypertensive disorders of pregnancy (HDP) contribute substantially to perinatal morbidity and mortality. Epigenetic changes point towards cardio-metabolic dysregulation for these vascular disorders. In early pregnancy, epigenetic changes using cell free DNA (cfDNA) are largely unexplored. We aimed to investigate these in HDP between 11 and 14 weeks of gestation by analysis of cfDNA methylation profiles in patients with hypertensive disorders. We identified patients without chronic hypertension but with subsequent development of preeclampsia (PE) (n = 11), with chronic hypertension (HT) but without PE development (n = 14), and lacking both PE and HT (n = 422). We matched patients according to PE risk factors into three groups (n = 5 each group): (1) PE: no HT but PE development, (2) HT: chronic hypertension but no PE and (3) Control: no PE or HT. We successfully optimized our cfDNA isolation process prior to whole genome bisulfite sequencing. Analysis of cfDNA methylation changes indicate a common predisposition in PE and HT groups, chiefly of maternal origin. Assessment of significant differentially methylated regions and annotated genes point towards a common cardiovascular predisposition in preeclampsia and hypertension groups in the first trimester. We postulate the pivotal role of the maternal cardiovascular system in HDP, which is already evident in the first trimester.

Polygenic Risk Score and Risk Factors for Preeclampsia and Gestational Hypertension

Preeclampsia and gestational hypertensive disorders (GHD) are common complications of pregnancy that adversely affect maternal and offspring health, often with long-term consequences. High BMI, advanced age, and pre-existing conditions are known risk factors for GHD. Yet, assessing a woman's risk of GHD based on only these characteristics needs to be reevaluated in order to identify at-risk women, facilitate early diagnosis, and implement lifestyle recommendations. This study demonstrates that a risk score developed with machine learning from the case-control genetics dataset can be used as an early screening test for GHD. We further confirm BMI as a risk factor for GHD and investigate a relationship between GHD and genetically constructed anthropometric measures and biomarkers. Our results show that polygenic risk score can be used as an early screening tool that, together with other known risk factors and medical history, would assist in identifying women at higher risk of GHD before its onset to enable stratification of patients into low-risk and high-risk groups for monitoring and preventative programs to mitigate the risks.

Diagnostic signature and immune characteristic of aging-related genes from placentas in Preeclampsia

INTRODUCTION

Preeclampsia (PE) is a serious pregnancy syndrome. Advanced maternal age (≥ 35 years old) is one of the major risk factors of PE and placental aging is considered to be related to this disease. However, the mechanisms underlying these phenomena remain obscured.

METHODS

Gene expression profiles of PE and non-PE placental samples were curated from the GSE75010 dataset. A diagnostic model was constructed and immune characteristics of PE subtypes were estimated.

RESULTS

A total of 58 aging-related genes, which may be associated with PE, were identified. Among them, LEP and FLT1 may be key aging-related genes. Based on 5 top genes (PIK3CB, FLT1, LEP, PIK3R1, CSNK1E), a diagnostic nomogram for PE was built (AUC = 0.872 in the GSE75010 dataset). Three molecular subtypes were clustered, which had different immune and angiogenesis characteristics.

CONCLUSION

The present study suggests the potential implications of aging-related genes in diagnosing PE. Diverse immune characteristics may be involved in the placental aging of PE.

Human placenta-based genome-wide mRNA sequencing to identify TEK/IGF1/CSF1/ANGPT2 as crucial segments in the pathogenesis of pre-eclampsia

Pre-eclampsia is a pregnancy-specific disease commonly occurring in late pregnancy and has always been threatening maternal and fetal lives, yet the etiology and pathogenesis of pre-eclampsia are still uncertain. To depict the overall changes of genes at the genome-wide level and identify potential biomarkers for early diagnosis of pre-eclampsia, we conducted this study by collecting placenta samples donated by six pregnancy women, among whom three healthy women were included as controls and three women were diagnosed with pre-eclampsia. The placental sample tissues were then subjected to high-throughput sequencing. Furthermore, we proceeded with bioinformatics analysis and formulated the hypothesis of pre-eclampsia development and verified the potential targets of pre-eclampsia by immunohistochemistry. Demographically, we found that the baseline characteristics of study subjects were highly homogeneous except for gestational weeks and blood pressure, where the blood pressure was higher and gestational weeks were shorter in the pre-eclampsia group (systolic blood pressure 123.33 ± 4.62 vs. 148.67 ± 3.79 mmHg, p = 0.046; diastolic blood pressure 79.00 ± 5.20 vs. 88.33 ± 2.89 mmHg, p = 0.068; gestational weeks 39.33 ± 1.03 vs. 35.76 ± 2.41, p = 0.050). Specific pathological changes were identified, shown as syncytial knots, fibrinoid necrosis, perivillous fibrin deposition, and vasculitis. For high-throughput sequencing, a total of 1,891 dysregulated genes were determined, of which 960 genes were downregulated and 931 genes were upregulated. The bioinformatics analysis indicated that these genes, with different molecular functions in different parts of cells, were primarily responsible for endothelium development and vascular process in the circulatory system, and more than 10 signaling pathways were involved. By focusing on the PI3K-Akt signaling pathway, Rap1 signaling pathway, and disease enrichment analysis item pre-eclampsia, TEK, CSF1, IGF1, and ANGPT2 were identified to promote the development of pre-eclampsia. After confirming the placental expression of these genes at the protein level, we proposed the pathogenesis of pre-eclampsia as follows: the downregulation of TEK, CSF1, IGF1, and ANGPT2 may inhibit trophoblast proliferation and affect the remodeling of spiral arteries, causing maternal and fetal malperfusion and impeding nutrient exchange, thereby leading to clinical manifestations of pre-eclampsia.