Abstract 463: The Effect of Intrauterine Inflammation on the Early Development of Atherosclerosis

Abstract

Atherosclerosis is a chronic condition that may begin prior to birth, particularly in the presence of factors that act through inflammatory pathways. Inflammation may alter epigenetic marks, and changes in methylation are observed in atherosclerotic lesions. We hypothesised that intrauterine inflammation (chorioamnionitis, which complicates 1-4% of all births in the US) would alter development of early atherosclerosis. We report preliminary findings from a novel mouse model of chorioamnionitis and atherosclerosis. We aim to investigate: 1. the effect of intrauterine inflammation on the development of early atherosclerosis in mice 2. molecular and epigenetic mechanisms Methods: Apolipoprotein E deficient pregnant mice (n=15-19 per group) received LPS (0.1 ng in 5 μl saline) or saline (5 μl) into each amniotic sac on gestational day 15. Offspring were weaned onto a high fat (21% v/v) diet at 4 weeks. Aortae, heart and plasma were collected from 6- and 12-week-old offspring. Aortae were analysed following Haematoxylin and Eosin (H&E) and Oil Red O staining. Heart and aortae cholesterol concentrations were quantified using colorimetric assay. Gene expression (Real-Time PCR) of candidate genes was measured. Results: Intra-amniotic LPS injection induced histological chorioamnionitis. In 6-week-old mice, intrauterine inflammation increased cholesterol concentrations in aorta and cardiac tissue (p<0.05), and increased aortic Dnmt1 mRNA levels (p=0.02; a key regulator of DNA methylation). No differences between LPS- and saline-treated animals were found in H&E stained aortic sinus. In 12-week-old mice, reduced mean intimal area (p=0.02) and mean intimal thickness index (p=0.02) were found in H&E stained brachiocephalic artery sections from LPS-treated offspring. No differences were found between groups in H&E stained aortic sinus or in an en face analysis of Oil Red O-stained aorta. Conclusions: Exposure to intrauterine inflammation has complex effects in this model. Contrary to our hypothesis, 12-week-old LPS-treated mice showed decreased intimal area with no other apparent histological differences, however early cholesterol and molecular biology changes exist. Differential epigenetic regulation may be an early underlying mechanism.