Amniotic fluid transcriptomics reflects novel disease mechanisms in fetuses with myelomeningocele

Abstract

Background Cell-free (cf) RNA in amniotic fluid supernatant (AFS) reflects developmental changes in gene expression in the living fetus, including genes specific to the central nervous system (CNS). Although it has been previously shown that CNS-specific transcripts are present in AFS, it is not known whether changes in the AFS transcriptome reflect the specific pathophysiology of fetal CNS disorders. In myelomeningocele, there is open communication between the CNS and amniotic fluid. Objectives To identify molecular pathophysiologic changes and novel disease mechanisms specific to myelomeningocele by analyzing AFS cfRNA in fetuses with open myelomeningocele. Study Design AFS was collected from 10 pregnant women at the time of the open myelomeningocele repair in the second trimester (24.5+/−1.0 wks) and 10 archived AFS from sex and gestational age-matched euploid fetuses without myelomeningocele were used as controls (20.9+/−0.9 wks). Differentially regulated gene expression patterns were analyzed using Human Genome U133 Plus 2.0 arrays. Results Fetuses with myelomeningocele had 284 differentially-regulated genes (176 up- & 108 down-regulated) in AFS. Known genes associated with myelomeningocele (PRICKLE2, GLI3, RAB23, HES1, FOLR1) and novel dysregulated genes were identified in association with neurodevelopment and neuronal regeneration (up-regulated, GAP43 and ZEB1) or axonal growth and guidance (down-regulated, ACAP1). Pathway analysis demonstrated a significant contribution of inflammation to pathology and a broad influence of Wnt signaling pathways (Wnt1, Wnt5A, ITPR1). Conclusion(s) Transcriptomic analyses of living fetuses with myelomeningocele using AFS cfRNA demonstrated differential regulation of specific genes and molecular pathways relevant to this CNS disorder, resulting in a new understanding of pathophysiological changes. The data also suggested the importance of pathways involving secondary pathology, such as inflammation, in myelomeningocele. These newly identified pathways may lead to hypotheses that can test novel therapeutic targets as adjuncts to fetal surgical repair.

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Amniotic fluid cell-free transcriptome: a glimpse into fetal development and placental cellular dynamics during normal pregnancy

“…For decades, AF sampled through transabdominal amniocentesis has been used to assess the fetal karyotype [7][8][9][10][11], lung maturity [12][13][14][15], and presence of inflammatory conditions, such as intra-amniotic infection and sterile intra-amniotic inflammation . Although the ultimate goal is to develop fetal testing via non-invasive sampling, such as urine or maternal blood, the advantages of AF for biomarker discovery have often been recognized [83][84][85][86][87].…”