Placental transcriptional signatures associated with cerebral white matter damage in the neonate

Epigenetic Responses to Nonchemical Stressors: Potential Molecular Links to Perinatal Health Outcomes

PURPOSE OF REVIEW

We summarize the recent literature investigating exposure to four nonchemical stressors (financial stress, racism, psychosocial stress, and trauma) and DNA methylation, miRNA expression, and mRNA expression. We also highlight the relationships between these epigenetic changes and six critical perinatal outcomes (preterm birth, low birth weight, preeclampsia, gestational diabetes, childhood allergic disease, and childhood neurocognition).

RECENT FINDINGS

Multiple studies have found financial stress, psychosocial stress, and trauma to be associated with DNA methylation and/or miRNA and mRNA expression. Fewer studies have investigated the effects of racism. The majority of studies assessed epigenetic or genomic changes in maternal blood, cord blood, or placenta. Several studies included multi-OMIC assessments in which DNA methylation and/or miRNA expression were associated with gene expression. There is strong evidence for the role of epigenetics in driving the health outcomes considered. A total of 22 biomarkers, including numerous HPA axis genes, were identified to be epigenetically altered by both stressors and outcomes. Epigenetic changes related to inflammation, the immune and endocrine systems, and cell growth and survival were highlighted across numerous studies. Maternal exposure to nonchemical stressors is associated with epigenetic and/or genomic changes in a tissue-specific manner among inflammatory, immune, endocrine, and cell growth-related pathways, which may act as mediating pathways to perinatal health outcomes. Future research can test the mediating role of the specific biomarkers identified as linked with both stressors and outcomes. Understanding underlying epigenetic mechanisms altered by nonchemical stressors can provide a better understanding of how chemical and nonchemical exposures interact.

Accelerated Aging and the Life Course of Individuals Born Preterm

Individuals born preterm have shorter lifespans and elevated rates of chronic illness that contribute to mortality risk when compared to individuals born at term. Emerging evidence suggests that individuals born preterm or of low birthweight also exhibit physiologic and cellular biomarkers of accelerated aging. It is unclear whether, and to what extent, accelerated aging contributes to a higher risk of chronic illness and mortality among individuals born preterm. Here, we review accelerated aging phenotypes in adults born preterm and biological pathways that appear to contribute to accelerated aging. We highlight biomarkers of accelerated aging and various resiliency factors, including both pharmacologic and non-pharmacologic factors, that might buffer the propensity for accelerated aging among individuals born preterm.

Prenatal Alcohol Exposure Impairs the Placenta-Cortex Transcriptomic Signature, Leading to Dysregulation of Angiogenic Pathways

Although alcohol consumption during pregnancy is a major cause of behavioral and learning disabilities, most FASD infants are late- or even misdiagnosed due to clinician's difficulties achieving early detection of alcohol-induced neurodevelopmental impairments. Neuroplacentology has emerged as a new field of research focusing on the role of the placenta in fetal brain development. Several studies have reported that prenatal alcohol exposure (PAE) dysregulates a functional placenta-cortex axis, which is involved in the control of angiogenesis and leads to neurovascular-related defects. However, these studies were focused on PlGF, a pro-angiogenic factor. The aim of the present study is to provide the first transcriptomic "placenta-cortex" signature of the effects of PAE on fetal angiogenesis. Whole mouse genome microarrays of paired placentas and cortices were performed to establish the transcriptomic inter-organ "placenta-cortex" signature in control and PAE groups at gestational day 20. Genespring comparison of the control and PAE signatures revealed that 895 and 1501 genes were only detected in one of two placenta-cortex expression profiles, respectively. Gene ontology analysis indicated that 107 of these genes were associated with vascular development, and String protein-protein interaction analysis showed that they were associated with three functional clusters. PANTHER functional classification analysis indicated that "intercellular communication" was a significantly enriched biological process, and 27 genes were encoded for neuroactive ligand/receptors interactors. Protein validation experiments involving Western blot for one ligand-receptor couple (Agt/AGTR1/2) confirmed the transcriptomic data, and Pearson statistical analysis of paired placentas and fetal cortices revealed a negative correlation between placental Atg and cortical AGTR1, which was significantly impacted by PAE. In humans, a comparison of a 38WG control placenta with a 36WG alcohol-exposed placenta revealed low Agt immunolabeling in the syncytiotrophoblast layer of the alcohol case. In conclusion, this study establishes the first transcriptomic placenta-cortex signature of a developing mouse. The data show that PAE markedly unbalances this inter-organ signature; in particular, several ligands and/or receptors involved in the control of angiogenesis. These data support that PAE modifies the existing communication between the two organs and opens new research avenues regarding the impact of placental dysfunction on the neurovascular development of fetuses. Such a signature would present a clinical value for early diagnosis of brain defects in FASD.

A multi-omic approach identifies an autism spectrum disorder (ASD) regulatory complex of functional epimutations in placentas from children born preterm

Children born preterm are at heightened risk of neurodevelopmental impairments, including Autism Spectrum Disorder (ASD). The placenta is a key regulator of neurodevelopmental processes, though the precise underlying molecular mechanisms remain unclear. Here, we employed a multi-omic approach to identify placental transcriptomic and epigenetic modifications related to ASD diagnosis at age 10, among children born preterm. Working with the extremely low gestational age (ELGAN) cohort, we hypothesized that a pro-inflammatory placental environment would be predictive of ASD diagnosis at age 10. Placental messenger RNA (mRNA) expression, CpG methylation, and microRNA (miRNA) expression were compared among 368 ELGANs (28 children diagnosed with ASD and 340 children without ASD). A total of 111 genes displayed expression levels in the placenta that were associated with ASD. Within these ASD-associated genes is an ASD regulatory complex comprising key genes that predicted ASD case status. Genes with expression that predicted ASD case status included Ewing Sarcoma Breakpoint Region 1 (EWSR1) (OR: 6.57 (95% CI: 2.34, 23.58)) and Bromodomain Adjacent To Zinc Finger Domain 2A (BAZ2A) (OR: 0.12 (95% CI: 0.03, 0.35)). Moreover, of the 111 ASD-associated genes, nine (8.1%) displayed associations with CpG methylation levels, while 14 (12.6%) displayed associations with miRNA expression levels. Among these, LRR Binding FLII Interacting Protein 1 (LRRFIP1) was identified as being under the control of both CpG methylation and miRNAs, displaying an OR of 0.42 (95% CI: 0.17, 0.95). This gene, as well as others identified as having functional epimutations, plays a critical role in immune system regulation and inflammatory response. In summary, a multi-omic approach was used to identify functional epimutations in the placenta that are associated with the development of ASD in children born preterm, highlighting future avenues for intervention.