Circulating Maternal Total Cell-Free DNA, Cell-Free Fetal DNA and Soluble Endoglin Levels in Preeclampsia: Predictors of Adverse Fetal Outcome? A Cohort Study

Fetal fraction of cell-free DNA in noninvasive prenatal testing and adverse pregnancy outcomes: a nationwide retrospective cohort study of 56,110 pregnant women

BACKGROUND

Noninvasive prenatal testing by cell-free DNA analysis is offered to pregnant women worldwide to screen for fetal aneuploidies. In noninvasive prenatal testing, the fetal fraction of cell-free DNA in the maternal circulation is measured as a quality control parameter. Given that fetal cell-free DNA originates from the placenta, the fetal fraction might also reflect placental health and maternal pregnancy adaptation.

OBJECTIVE

This study aimed to assess the association between the fetal fraction and adverse pregnancy outcomes.

STUDY DESIGN

We performed a retrospective cohort study of women with singleton pregnancies opting for noninvasive prenatal testing between June 2018 and June 2019 within the Dutch nationwide implementation study (Trial by Dutch Laboratories for Evaluation of Non-Invasive Prenatal Testing [TRIDENT]-2). Multivariable logistic regression analysis was used to assess associations between fetal fraction and adverse pregnancy outcomes. Fetal fraction was assessed as a continuous variable and as <10th percentile, corresponding to a fetal fraction <2.5%.

RESULTS

The cohort comprised 56,110 pregnancies. In the analysis of fetal fraction as a continuous variable, a decrease in fetal fraction was associated with increased risk of hypertensive disorders of pregnancy (adjusted odds ratio, 2.27 [95% confidence interval, 1.89-2.78]), small for gestational age neonates <10th percentile (adjusted odds ratio, 1.37 [1.28-1.45]) and <2.3rd percentile (adjusted odds ratio, 2.63 [1.96-3.57]), and spontaneous preterm birth from 24 to 37 weeks of gestation (adjusted odds ratio, 1.02 [1.01-1.03]). No association was found for fetal congenital anomalies (adjusted odds ratio, 1.02 [1.00-1.04]), stillbirth (adjusted odds ratio, 1.02 [0.96-1.08]), or neonatal death (adjusted odds ratio, 1.02 [0.96-1.08]). Similar associations were found for adverse pregnancy outcomes when fetal fraction was <10th percentile.

CONCLUSION

In early pregnancy, a low fetal fraction is associated with increased risk of adverse pregnancy outcomes. These findings can be used to expand the potential of noninvasive prenatal testing in the future, enabling the prediction of pregnancy complications and facilitating tailored pregnancy management through intensified monitoring or preventive measures.

A Reliable Method for Quantifying Plasma Cell-Free DNA Using an Internal Standard Strategy: Evaluation in a Cohort of Non-Pregnant and Pregnant Women

The use of plasma cell-free DNA (cfDNA) as a useful biomarker in obstetric clinical practice has been delayed due to the lack of reliable quantification protocols. We developed a protocol to quantify plasma cfDNA using an internal standard strategy to overcome difficulties posed by low levels and high fragmentation of cfDNA. cfDNA was isolated from plasma samples of non-pregnant (NP, n = 26) and pregnant (P, n = 26) women using a commercial kit and several elution volumes were evaluated. qPCR parameters were optimized for cfDNA quantification, and several quantities of a recombinant standard were evaluated as internal standard. Absolute quantification was performed using a standard curve and the quality of the complete method was evaluated. cfDNA was eluted in a 50-μl volume, actin-β (ACTB) was selected as the target gene, and qPCR parameters were optimized. The ACTB standard was constructed and 1000 copies were selected as internal standard. The standard curve showed R2 = 0.993 and E = 109.7%, and the linear dynamic range was defined between 102 and 106 ACTB copies/tube. Repeatability and reproducibility in terms of CV were 19% and up to 49.5% for ACTB copies per milliliter of plasma, respectively. The range of cfDNA levels was 428-18,851 copies/mL in NP women and 4031-2,019,363 copies/mL in P women, showing significant differences between the groups. We recommend the application of internal standard strategy for a reliable plasma cfDNA quantification. This methodology holds great potential for a future application in the obstetric field.

Missing links in preeclampsia cell model systems of endothelial dysfunction

Preeclampsia, one of the main hypertensive disorders of pregnancy, is associated with circulating factors released by the ischemic placenta accompanied by systemic endothelial dysfunction. The etiology of preeclampsia remains poorly understood although it is associated with high maternal and fetal mortality and increased cardiovascular disease risk. Most cell model systems used for studying endothelial dysfunction have not taken into account hemodynamic physical factors such as shear-stress forces which may prevent extrapolation of cell data to in vivo settings. We overview the role of hemodynamic forces in modulating endothelial cell function and discuss strategies to reproduce this biological characteristic in vitro to improve our understanding of endothelial dysfunction associated with preeclampsia.

Cell-free fetal DNA impairs trophoblast migration in a TLR9-dependent manner and can be reversed by hydroxychloroquine

Growing evidence suggests a relationship between elevated circulating placental-derived cell-free fetal DNA (cffDNA) and preeclampsia. Hypomethylation of CpG motifs, a hallmark of cffDNA, allows it to activate Toll-like receptor 9 (TLR9). Using an in vitro human first trimester extravillous trophoblast cell model, we sought to determine if trophoblast-derived cffDNA and ODN 2216, a synthetic unmethylated CpG oligodeoxynucleotide, directly impacted spontaneous trophoblast migration. The role of the DNA sensors TLR9, AIM2, and cGAS was assessed using the inhibitor A151. To test whether any effects could be reversed by therapeutic agents, trophoblasts were treated with or without cffDNA or ODN 2216 with or without aspirin (ASA; a known cGAS inhibitor), aspirin-triggered lipoxin (ATL), or hydroxychloroquine (HCQ; a known TLR9 inhibitor). Trophoblast-derived cffDNA and ODN 2216 reduced trophoblast migration without affecting cell viability. Reduced trophoblast migration in response to cffDNA or ODN 2216 was reversed by A151. cffDNA inhibition of trophoblast migration was reversed by HCQ, while ASA or ATL had no effect. In contrast ODN 2216 inhibition of trophoblast migration was reversed by ASA, ATL and HCQ. Our findings suggest that cffDNA can exert a local effect on placental function by impairing trophoblast migration through activation of innate immune DNA sensors. HCQ, a known TLR9 inhibitor, reversed the effects of cffDNA on trophoblast migration. Greater insights into the molecular underpinnings of how cffDNA impacts placentation can aid in our understanding of the pathogenesis of preeclampsia, and in the development of novel therapeutic approaches for preeclampsia therapy.

Liquid Biopsy in Adverse Neurodevelopment of Children: Problems and Prospects

Neurodevelopmental disorders in children have an important impact on the quality of life in the whole life cycle. Severe neurodevelopmental disorders will become a serious social and family burden and an important social and economic problem. The early and middle childhood is the critical period of children's neurodevelopment. Early diagnosis of neurological disorders plays an important role in guiding children's neurological development. Existing monitoring tools lack prenatal and even early assessment of children's neurodevelopment, so reliable biomarkers are conducive to personalized care at an earlier stage. In this review, we will discuss different methods of neurodevelopmental monitoring at different times and the role and evaluation of liquid biopsy in neurodevelopmental monitoring.

Association between low fetal fraction in cell-free DNA testing and adverse pregnancy outcome: A systematic review

Objective

Low fetal fraction (LFF) in prenatal cell‐free DNA (cfDNA) testing is an important cause of test failure and no‐call results. LFF might reflect early abnormal placentation and therefore be associated with adverse pregnancy outcome. Here, we review the available literature on the relationship between LFF in cfDNA testing and adverse pregnancy outcome.

Method

A systematic literature search was conducted in MEDLINE and EMBASE up to November 1, 2020.

Results

Five studies met the criteria for inclusion; all were retrospective observational cohort studies. The cohort sizes ranged from 370 to 6375 pregnancies, with all tests performed in the first trimester or early second trimester. A 4% cutoff for LFF was used in two studies, two studies used the 5th and 25th percentiles, respectively, and one study used a variety of cutoff values for LFF. LFF in prenatal cfDNA testing was observed to be associated with hypertensive disease of pregnancy, small for gestational age neonates, and preterm birth. Conflicting results were found regarding the association between LFF and gestational diabetes mellitus.

Conclusions

LFF in cfDNA testing is associated with adverse pregnancy outcome,specifically pregnancy‐related hypertensive disorders, preterm birth, and impaired fetal growth related to placental dysfunction. Since the available evidence is limited, a large prospective cohort study on the relationship between fetal fraction and pregnancy outcomes is needed.

What's already known about this topic?

Low fetal fraction (LFF) in prenatal cell‐free DNA (cfDNA) testing is an important cause of test failure and no‐call results and has been associated with aneuploidy

LFF might also reflect early abnormal placentation and therefore be associated with adverse pregnancy outcome

What does this review add?

This review summarizes the available data on LFF in prenatal cfDNA testing and its relation to adverse pregnancy outcomes

LFF was found to be associated with pregnancy‐related hypertensive disorders, preterm birth, and impaired fetal growth related to placental dysfunction

Since the available evidence is limited, a large prospective cohort study on the relationship between fetal fraction and pregnancy outcomes is needed

Circulating Nucleic Acids in Maternal Plasma and Serum in Pregnancy Complications: Are They Really Useful in Clinical Practice? A Systematic Review

OBJECTIVE

A systematic review was carried out to summarize the available evidence to assess whether circulating nucleic acids in maternal plasma and serum (CNAPS) have the potential to serve as extra and independent markers for the prediction and/or progression monitoring of the most common and severe complications of pregnancy, including preeclampsia, intrauterine growth restriction, preterm delivery, morbidly adherent placenta, gestational diabetes, antiphospholipid syndrome, threatened abortion, intrahepatic cholestasis of pregnancy, and hyperemesis gravidarum.

METHOD

A comprehensive literature search of the MEDLINE (PubMed), EMBASE, and ISI Web of Knowledge databases was conducted to identify relevant studies that included amounts of CNAPS in the abovementioned pregnancy complications.

RESULTS

Eighty-three studies met the eligibility criteria. The vast majority of studies were conducted on the quantity of total circulating cell free DNA (cfDNA) and cell free fetal DNA (cffDNA), and some were conducted on messenger RNA (mRNA) species. A few studies have instead evaluated the cell free DNA fetal fraction (cfDNAff), but only in a limited number of pregnancy complications. Despite the growing interest and the abundance of the papers available, little information is available for other new CNAPS, including microRNA (miRNA), long noncoding RNA (lncRNA), mitochondrial DNA (mtDNA), and circular RNA.

CONCLUSION

Due to the heterogeneity of the populations enrolled, the scarcity of the studies that adjusted the CNAPS values for possible confounding factors, and the difficulty in interpreting the published data, no conclusion regarding the statistical robustness and clinical relevance of the data can be made at present. If assayed at the third trimester, the CNAPS have, however, shown better performance, and could be used in populations already at risk of developing complications as suggested by the presence of other clinical features. Other CNAPS, including miRNA, are under investigation, especially for the screening of gestational diabetes mellitus, but no data about their clinical utility are available. Circulating DNA (cfDNA, cffDNA, and cfDNAff) and mRNA have not been properly evaluated yet, especially in patients asymptomatic early in pregnancy but who developed complications later, perhaps because of the high cost of these techniques and the availability of other predictors of pregnancy complications (biochemical, biophysical, and ultrasound markers). Therefore, from the analysis of the data, the positive predictive value is not available. As regards the new CNAPS, including miRNA, there are still no sufficient data to understand if they can be promising markers for pregnancy complications monitoring and screening, since CNAPS are statistically weak and expensive. It is reasonable to currently conclude that the use of the CNAPS in clinical practice is not recommended.

Circulating Total Cell-Free DNA Levels Are Increased in Hypertensive Disorders of Pregnancy and Associated with Prohypertensive Factors and Adverse Clinical Outcomes

Previous studies have described increased circulating cell-free DNA (cfDNA) in hypertensive disorders of pregnancy (HDP). Here, we aimed first to confirm this information using a simple, but sensible fluorescent assay, and second to investigate whether total cfDNA is associated with circulating factors known to be linked to the pathophysiology of HDP as well as with poor maternal-fetal outcomes. We studied 98 women with healthy pregnancies (HP), 88 with gestational hypertension (GH), and 91 with preeclampsia (PE). Total DNA was extracted from plasma using the QIAamp DNA blood mini kit and quantified using Quant-iT™ PicoGreen® dsDNA fluorescent detection kit. We found higher total cfDNA levels in GH and PE (197.0 and 174.2 ng/mL, respectively) than in HP (140.5 ng/mL; both p < 0.0001). Interestingly, total cfDNA levels were elevated in both male and female-bearing pregnancies diagnosed with either HDP, and in more severe versus less severe HDP cases, as classified according to responsiveness to antihypertensive therapy. In addition, total cfDNA was independently associated with HDP, and a cutoff concentration of 160 ng/mL provided appropriate sensitivity and specificity values for diagnosing GH and PE compared to HP (70-85%, both p < 0.0001). Moreover, high total cfDNA was associated with adverse clinical outcomes (high blood pressure, low platelet count, preterm delivery, fetal growth restriction) and high prohypertensive factors (sFLT-1, sEndoglin, MMP-2). These findings represent a step towards to the establishment of cfDNA as a diagnostic tool and the need to understand its role in HDP.

Preeclampsia – Prediction and Monitoring Factors

Preeclampsia is one of the leading causes of maternal and perinatal morbidity and mortality, usually characterized by hypertension and proteinuria. Despite high incidence of preeclampsia the pathophysiological basis of preeclampsia is still not clear and there are a number of mechanisms and signaling pathways that intertwine. It is very important to develop specific and reliable predictive algorithms in order to enable early initiation of therapy due to facts that incidence of preeclampsia has upward trend and that cause adverse maternal and fetal outcome. Some of the most commonly used methods for prediction of preeclampsia include uterine artery Doppler velocimetry, determination of some microRNA, such as miR-210, and assessment of various pro-angiogenic and anti-angiogenic factors from blood. Angiogenic factors that possibly have most important role in pathogenesis of preeclampsia are vascular endothelial growth factor (VEGF) and placental growth factor (PlGF), which promote angiogenesis, and soluble fms-like tyrosine kinase-1 (sFlt1) and soluble form of endoglin (s-Eng), which exhibit anti-angiogenic properties. Aggravating circumstance is that preeclampsia has heterogeneous origin, and due to this fact, the value of individual markers can vary significantly. There is a constant tendency for creating comprehensive algorithm for prediction of preeclampsia which would be sufficiently specific and sensitive, and in the same time cheap and available. In that sense, new clinical studies are needed to show the most effective combination of parameters in the predeclampsia prediction.

DNA damage, metabolism and aging in pro-inflammatory T cells: Rheumatoid arthritis as a model system

The aging process is the major driver of morbidity and mortality, steeply increasing the risk to succumb to cancer, cardiovascular disease, infection and neurodegeneration. Inflammation is a common denominator in age-related pathologies, identifying the immune system as a gatekeeper in aging overall. Among immune cells, T cells are long-lived and exposed to intense replication pressure, making them sensitive to aging-related abnormalities. In successful T cell aging, numbers of naïve cells, repertoire diversity and activation thresholds are preserved as long as possible; in maladaptive T cell aging, protective T cell functions decline and pro-inflammatory effector cells are enriched. Here, we review in the model system of rheumatoid arthritis (RA) how maladaptive T cell aging renders the host susceptible to chronic, tissue-damaging inflammation. In T cells from RA patients, known to be about 20years pre-aged, three interconnected functional domains are altered: DNA damage repair, metabolic activity generating energy and biosynthetic precursor molecules, and shaping of plasma membranes to promote T cell motility. In each of these domains, key molecules and pathways have now been identified, including the glycolytic enzymes PFKFB3 and G6PD; the DNA repair molecules ATM, DNA-PKcs and MRE11A; and the podosome marker protein TKS5. Some of these molecules may help in defining targetable pathways to slow the T cell aging process.

Circulating fetal and total cell-free DNA, and sHLA-G in black South African women with gestational hypertension and pre-eclampsia

OBJECTIVE

Quantification of circulating fetal and total cell-free DNA (cfDNA) and soluble human leucocyte antigen (HLAG) in gestational hypertension and pre-eclampsia.

METHODS

Serum cfDNA were quantified in controls, pre-eclamptics, and gestational hypertensive patients using real-time qPCR. Soluble HLAG was measured by enzyme-linked immune-sorbent assay.

RESULTS

Serum fetal and total cfDNA levels were higher in pre-eclampsia compared with the controls and gestational hypertensives (p < 0.001), more so in severe compared with mild-to-moderate pre-eclampsia (p < 0.05). Soluble HLAG levels were lower in pre-eclamptics than controls and gestational hypertension (p < 0.05).

CONCLUSION

Circulating fetal and total cfDNA were increased, while soluble HLAG was decreased in pre-eclampsia.

Differential miR-346 and miR-582-3p Expression in Association with Selected Maternal and Fetal Complications

Several miRNAs are expressed in human gestational tissue, and some have been shown to be associated with placental dysfunction and complicated pregnancy outcomes. To investigate the roles of miR-346 and miR-582-3p in adverse obstetric events, we analyzed these 2 miRNAs in three samples (maternal blood, umbilical cord blood and placenta) obtained from pregnant women in four groups, including healthy control (n = 60), preeclampsia (n = 31), preterm delivery (n = 29) and small for gestational age (n = 19) patients. The expression levels of miR-346 and miR-582-3p in all included adverse obstetric outcome groups were significantly higher in the maternal plasma samples but lower in the placenta samples (all p value < 0.05). In addition, the miR-346 expression levels in fetal cord blood were also significantly lower in all of the included adverse obstetric outcome groups (all p < 0.05). Multivariate analysis of the three specimens after adjusting for maternal age and gestational age at delivery gave the same results. In conclusion, aberrant miR-346 and miR-582-3p expression level in pregnancy was associated with multiple maternal and fetal complications. Their differential expression in maternal blood, umbilical cord blood and placenta could be potential biomarkers or therapeutic targets for adverse obstetric outcomes

Total and Fetal Circulating Cell-Free DNA, Angiogenic, and Antiangiogenic Factors in Preeclampsia and HELLP Syndrome

BACKGROUND

Preeclampsia (PE) is a hypertensive disorder of pregnancy characterized by hypertension and proteinuria. The HELLP syndrome is the most severe form of PE. The aim of the present study was to determine different potential biomarkers that may help us perform an early diagnosis of the disease, assess on the severity of the disease, and/or predict maternal or fetal adverse outcomes.

METHODS

We measured serum levels of total and fetal circulating cell-free DNA (cfDNA), soluble endoglin, soluble form of vascular endothelial growth factor receptor, and placental growth factor in a healthy control group of pregnant women (n = 26), patients with mild (n = 37) and severe PE (n = 25), and patients with HELLP syndrome (n = 16).

RESULTS

We observed a gradual and strong relationship between all the biomarkers mentioned and the range of severity of PE, with the highest levels in patients with HELLP syndrome. Nevertheless, only the values of total cfDNA were able to significantly differentiate severe PE and HELLP syndrome (20957 ± 2784 vs. 43184 ± 8647 GE/ml, P = 0.01). Receiver operating characteristic (ROC) curves were constructed (i) for the healthy group with respect to the groups with PE and (ii) for patients with PE with respect to the group with HELLP syndrome; sensitivity and specificity values at different cutoff levels were calculated in each case. The maximum ROC area under the curve value for PE and HELLP syndrome (with respect to controls) was 0.91 (P < 0.001).

CONCLUSIONS

The measured biomarkers of cell damage, angiogenesis, and antiangiogenesis may reflect the severity of PE, with higher levels in patients who develop HELLP syndrome. In addition, these biomarkers may also help predict adverse fetal and maternal outcomes.