Identification of new therapeutic targets related to endoplasmic reticulum stress and mitochondrial dysfunction to reduce the risk of rupture in degenerative ascending aortic aneurysm.

Background: Ascending Thoracic Aortic Aneurysm (ATAA) is a progressive dilation of the aorta that can be complicated by its dissection leading to death in 80-90% of the patients. When associated with aging and atherosclerosis, the outcome is worse and reconstructive surgery is the only effective therapy. Our objective was to characterize differential expressed genes (DEG) involved in endoplasmic reticulum (ER) and mitochondria dysfunction in patients with degenerative ATAA.

Methods: A transcriptomic analysis was performed by RNA sequencing using RNA isolated from ATAA of patients classified as degenerative (n=13) and multi-organ healthy donors (n=6). DEGs related to ER stress and mitochondrial dysfunction were identified with the DESeq2 package. Enriched pathway (Reactome) and protein interaction (PPI) analysis was performed with the clusterProfiles package. PPI of the selected DEGs was analyzed based on the string database and visualized by Cytoscape software.

Results: Histology revealed a complete disorganization of the extracellular matrix (ECM) and cell loss in the aortic wall of ATAA patients where the upregulation of 15 DEGs and the downregulation of 13 DEGs that encode proteins related to ER stress (ATF4, EIF2AK3, HSPA5, ERN1, SEL1L), mitochondrial dysfunction (DNML1, IMMT, MT-CO3, MT-CYB, MT ND2, TIMM17B, MT-ERF1, TOMM5) and ECM was detected. The results of GO term and enriched pathway analysis indicated that these DEGs are mainly enriched in pathways related to aortic diseases.

Conclusions: Our data show that proteins related to mitochondrial dysfunction and ER stress might be therapeutic targets for the treatment of ATAA.