Precision Diagnostics by Affinity-Mass Spectrometry: A Novel Approach for Fetal Growth Restriction Screening During Pregnancy

Evolution of Fetal Growth in Symptomatic Sars-Cov-2 Pregnancies

INTRODUCTION

SARS-CoV-2 is a viral disease with potentially devastating effects. Observational studies of pregnant women infected with SARS-CoV-2 report an increased risk for FGR. This study utilizes data from a prospective SARS-CoV-2 registry in pregnancy, investigating the progression of fetuses to fetal growth restriction (FGR) at birth following maternal SARS-CoV-2 and evaluating the hypothesis of whether the percentage of SGA at birth is increased after maternal SARS-CoV-2 taking into account the time interval between infection and birth.

MATERIALS & METHODS

CRONOS is a prospective German registry enrolling pregnant women with confirmed SARS-CoV-2 infection during their pregnancy. SARS-CoV-2 symptoms, pregnancy- and delivery-specific information were recorded. The data evaluated in this study range from March 2020 until August 2021. Women with SARS-CoV-2 were divided into three groups according to the time of infection/symptoms to delivery: Group I<2 weeks, Group II 2-4 weeks, and Group III>4 weeks. FGR was defined as estimated and/or birth weight<10% ile, appropriate for gestational age (AGA) was within 10 and 90%ile, and large for gestational age (LGA) was defined as fetal or neonatal weight>90%ile.

RESULTS

Data for a total of 2,650 SARS-CoV-2-positive pregnant women were available. The analysis was restricted to symptomatic cases that delivered after 24+0 weeks of gestation. Excluding those cases with missing values for estimated fetal weight at time of infection and/or birth weight centile, 900 datasets remained for analyses. Group I consisted of 551 women, Group II of 112 women, and Group III of 237 women. The percentage of changes from AGA to FGR did not differ between groups. However, there was a significantly higher rate of large for gestational age (LGA) newborns at the time of birth compared to the time of SARS-CoV-2 infection in Group III (p=0.0024), respectively.

CONCLUSION

FGR rates did not differ between symptomatic COVID infections occurring within 2 weeks and>4 weeks before birth. On the contrary, it presented a significant increase in LGA pregnancies in Group III. However, in this study population, an increase in the percentage of LGA may be attributed to pandemic measures and a reduction in daily activity.

Epigenetic Modifications at the Center of the Barker Hypothesis and Their Transgenerational Implications

Embryo/fetal nutrition and the environment in the reproductive tract influence the subsequent risk of developing adult diseases and disorders, as formulated in the Barker hypothesis. Metabolic syndrome, obesity, heart disease, and hypertension in adulthood have all been linked to unwanted epigenetic programing in embryos and fetuses. Multiple studies support the conclusion that environmental challenges, such as a maternal low-protein diet, can change one-carbon amino acid metabolism and, thus, alter histone and DNA epigenetic modifications. Since histones influence gene expression and the program of embryo development, these epigenetic changes likely contribute to the risk of adult disease onset not just in the directly affected offspring, but for multiple generations to come. In this paper, we hypothesize that the effects of parental nutritional status on fetal epigenetic programming are transgenerational and warrant further investigation. Numerous studies supporting this hypothesis are reviewed, and potential research techniques to study these transgenerational epigenetic effects are offered.

Profiling of intact blood proteins by matrix-assisted laser desorption/ionization mass spectrometry without the need for freezing - Dried serum spots as future clinical tools for patient screening

RATIONALE

To open up new ways for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS)-based patient screening, blood serum is the most preferred specimen because of its richness in patho-physiological information and due to ease of collection. To overcome deleterious freeze/thaw cycles and to reduce high costs for shipping and storage, we sought to develop a procedure which enables MALDI-MS protein profiling of blood serum proteins without the need for serum freezing.

METHODS

Blood sera from patients/donors were divided into portions which after pre-incubation were fast frozen. Thawed aliquots were deposited on filter paper discs and air-dried at room temperature. Intact serum proteins were eluted with acid-labile detergent-containing solutions and were desalted by employing a reversed-phase bead system. Purified protein solutions were screened by MALDI-MS using standardized instrument settings.

RESULTS

MALDI mass spectra from protein solutions which were eluted from filter paper discs and desalted showed on average 25 strong ion signals (mass range m/z 6000 to 10,000) from intact serum proteins (apolipoproteins, complement proteins, transthyretin and hemoglobin) and from proteolytic processing products. Semi-quantitative analysis of three ion pairs: m/z 6433 and 6631, m/z 8205 and 8916, as well as m/z 9275 and 9422, indicated that the mass spectra from either pre-incubated fast-frozen serum or pre-incubated dried serum spot eluted serum contained the same information on protein composition.

CONCLUSIONS

A workflow that avoids the conventional cold-chain and yet enables the investigation of intact serum proteins and/or serum proteolysis products by MALDI-MS profiling was developed. The presented protocol tremendously broadens the clinical application of MALDI-MS and simultaneously allows a reduction in the costs for storage and shipping of serum samples. This will pave the way for clinical screening of patients also in areas with limited access to health care systems, and/or specialized laboratories.