DNA methylation analysis of aortic wall tissue in ascending aortic dilatation/aneurysm and dissection

Ascending aortic dilatation/aneurysm and dissection are life-threatening cardiovascular conditions. However, the epigenetic regulatory mechanisms within aortic cells underlying these pathologies remain poorly understood. This study aimed to identify differentially methylated genes (DMGs) in aortic tissues from patients with ascending aortic dilatation/aneurysm and dissection by performing a re-analysis of publicly available DNA methylation datasets. A re-analysis was conducted on three DNA methylation datasets (GSE50192, GSE202047, GSE84274) from the Illumina Infinium HumanMethylation450 BeadChip. To account for tissue heterogeneity, cellular deconvolution was performed using the HEpiDISH algorithm and a custom reference panel of cell-type-specific CpG sites for key vascular cell types (endothelial cells, fibroblasts, smooth muscle cells, immune cells). Our re-analysis revealed that aortic dissection and bicuspid aortic valve patients with aortic dilatation/aneurysm exhibit distinct DNA methylation profiles compared to intact aorta. These pathologies differ from each other in the number and the spectrum of DMGs. The adjustment for cellular heterogeneity eliminated the majority of the initially identified DMGs. However, this correction helped to make an assessment of vascular inflammation, characterize its impact on aortic wall stability, and identify genes with differential DNA methylation associated with the disease phenotypes, rather than with inter-group heterogeneity. The genes NFIX, PCDH7, MED13L, LMO4, DIP2C, PLEKHF1, NKD1, C10orf41 (ZNF503-AS2), ARAP2, TBX3, and TBX5, which remained in the DMG status after adjustment for cellular composition and are expressed in individual cells/whole aortic tissue, can be considered as new candidate genes for the development of aortic dilatation/aneurysm in patients with bicuspid aortic valve. NFIX, LMO4, DIP2C, C10orf41 (ZNF503- AS2), MED13L, TBX3, TBX5 are transcriptional regulators or modulators; NKD1 is a recognized inhibitor of the Wnt pathway. Our findings highlight the necessity of a rigorous approach to cohort design, which includes comprehensive phenotyping (encompassing aortic valve morphology) and underscore the importance of future single-cell investigations.