Transcriptomic regulations in oligodendroglial and microglial cells related to brain damage following fetal growth restriction

Fetal growth restriction (FGR) is a major complication of human pregnancy, frequently resulting from placental vascular diseases and prenatal malnutrition, and is associated with adverse neurocognitive outcomes throughout life. However, the mechanisms linking poor fetal growth and neurocognitive impairment are unclear. Here, we aimed to correlate changes in gene expression induced by FGR in rats and abnormal cerebral white matter maturation, brain microstructure, and cortical connectivity in vivo. We investigated a model of FGR induced by low-protein-diet malnutrition between embryonic day 0 and birth using an interdisciplinary approach combining advanced brain imaging, in vivo connectivity, microarray analysis of sorted oligodendroglial and microglial cells and histology. We show that myelination and brain function are both significantly altered in our model of FGR. These alterations, detected first in the white matter on magnetic resonance imaging significantly reduced cortical connectivity as assessed by ultrafast ultrasound imaging. Fetal growth retardation was found associated with white matter dysmaturation as shown by the immunohistochemical profiles and microarrays analyses. Strikingly, transcriptomic and gene network analyses reveal not only a myelination deficit in growth-restricted pups, but also the extensive deregulation of genes controlling neuroinflammation and the cell cycle in both oligodendrocytes and microglia. Our findings shed new light on the cellular and gene regulatory mechanisms mediating brain structural and functional defects in malnutrition-induced FGR, and suggest, for the first time, a neuroinflammatory basis for the poor neurocognitive outcome observed in growth-restricted human infants. GLIA 2016;64:2306-2320.