Epigenetic signature in human development of vascular lesions: effects of maternal hypercolesterolemia

Background and purpose: It is well established that human vascular lesions begin very early stage in life with the development of fatty streak lesions in the arteries of fetuses. Although several studies have demonstrated that maternal cholesterol may exert detrimental effects on the number and degree of vascular lesions in fetuses, however, how cholesterol affects in utero programming is still unclear. Epigenetics migh promote pathogenic mechanisms by which gene-environment interactions could occurr. The aim of this study was to verify whether maternal hypercholesterolemia during pregnancy affects epigenetic signature in fetal aortic tissues. Methods: Human fetal aortas (n=42) were analyzed by immunohistochemistry and dichotomized in their respective high and low maternal cholesterol during pregnancy. Immunohistochemistry in fetal arteries was performed with the following antibodies: Anti-trimethyl-Histone H3, (Lys4, Lys9, Lys27), and Anti-CD68 antibody. Methyl DNA immunoprecipitation was performed by MeDIP kit (DIAGENODE). Results: The data indicated a strong signal >75% of positive cells with histone trimethyl lys 27 antibody present in 27% of the biggest fetal aortic lesion area (>120mm2/section) (p>0.039). Molecular analysis of specific cholesterol regulatory circuit gene expression revealed hypermethylation in promoter and 3' UTR of SREBP2 and LDL receptor gene in aortas from hypercholesterolemic mothers compared to normocholesterolemic group (p<0.004). Conclusions: Our data indicate that epigenetic mechanisms may contribute to the development of vascular lesions in humans. Maternal hypercholesterolemia during pregnancy may exacerbate the triggering of in promoter and 3' UTR of SREBP2 and LDL receptor gene. The understanding of epigenetic mechanisms during fetal programming by this approach could lead to potential applications in clinical practice through the development of epigenetic biomarkers for early diagnosis of vascular disease and/or novel drugs adversing such epigentic mechanisms.