Different gene co-expression patterns of aortic intima-media and adventitia in thoracic aortic aneurysm

Due to permanent aortic dilation, thoracic aortic aneurysm (TAA) is a life-threatening disease. Once ruptured, TAA has a high lethality and disability rate. Although studies have focused on transcriptomic alterations in TAA, more detailed analysis is still lacking, especially the different aortic intima-media and adventitia roles. This study aimed to identify the different co-expression patterns between the aortic intima-media and the adventitia underlying the aortic dilation.

We analyzed the gene expression profiles obtained from Gene Expression Omnibus (GEO, GSE26155) database. With a false discovery rate (FDR) < 0.05 and |log2FC| ≥ 1, 56 and 33 differential genes in the intima-media and adventitia, respectively, between the non-dilated and dilated status. Gene ontology (GO) and gene set enrichment analysis revealed that degranulation and activation of neutrophils play an essential role in the intima-media of dilated aortas. Through weighted gene co-expression network analysis (WGCNA), we identified essential co-expressed modules and hub genes to explore the biological functions of the dysregulated genes.

Functional pathway analysis suggested that lipid metabolism, C-C motif chemokine pathways were significantly enriched in the adventitia, whereas ribosome proteins and related mRNA translation pathways were closely related to intima and media. Furthermore, the ssGSEA analysis indicated that macrophages, helper T cells, and neutrophils were higher in the intima-media of the dilated thoracic aorta. Finally, we validated the critical findings of the study with the murine model of TAA.

This study identified and verified hub genes and pathways in aortic intima-media and adventitia prominently associated with aortic dilation, providing practical understanding in the perspective of searching for new molecular targets.