Abstract 9081: Fatal Occlusive Pulmonary Vasculopathy in Rats Late After Perinatal Hypoxia: Hyperproliferative and Pro-Inflammatory Phenotypes and Related Differential Dna Methylation in Cultured Pulmonary Arterial Smooth Muscle Cells as the Potential Substrate

Abstract

Background: Perinatal insults increase the risk of developing various adult-onset vascular diseases. Although we recently established a fatal SU5416/hypoxia-induced model with worsening pulmonary vascular disease (PVD) in rats late after exposure to perinatal hypoxia, the mechanisms are elusive. Hypothesis: In rats with fatal occlusive PVD late after perinatal hypoxia, cultured pulmonary arterial smooth muscle cells (PASMCs) from rats before SU5416/hypoxia treatment exhibit phenotypic and epigenetic changes. Methods: PVD was induced in 7-week-old rats exposed to perinatal hypoxia or ambient air by injecting SU5416 followed by exposure to hypoxia for 3 weeks (SU5416/hypoxia). Rats were assessed at the baseline (7 weeks of age) and 8 weeks after SU5416 injection (15 weeks of age). Proliferation, cytokine production and genome-wide DNA methylation profile were evaluated in PASMC isolated from the baseline rats with/without perinatal hypoxia. Results: In SU5416/hypoxia rats, perinatal hypoxia reduced body weight gain and survival, and increased right ventricular systolic pressure, Fulton index and occlusive PVD (p<.05), which were associated with an increase in perivascular macrophages, expression of prepro-endothelin-1 mRNA and eNOS protein in the lung (p<.05) but not with impaired alveolarization or worsening right ventricular fibrosis. In PASMCs isolated from the baseline rats, perinatal hypoxia enhanced PDGF-BB-induced cell proliferation and phosphorylation of extracellular signal-regulated kinase as well as TNFα-induced expression of IL-6, monocyte chemotactic protein 1 and phosphorylation of p38 (p<.05). DNA methylation profiling identified 35 differentially methylated regions (DMRs). Methylation in the region encoding phosducin like protein (Pdcl) was associated with decreased PDGF-BB-induced expression of Pdcl mRNA in PASMCs with perinatal hypoxia. Functional enrichment analysis of DMRs revealed the relation to cell proliferation and inflammatory process (ie, Wnt5A and ROR1). Conclusions: In SU5416/hypoxia rats late after perinatal hypoxia, hyperproliferative and pro-inflammatory phenotypes and functionally related differential DNA methylation in PASMCs may be the substrate for the fatal occlusive PVD.