ATOX1-driven ECM degradation and vascular smooth muscle cell apoptosis accelerate aortic dissection progression

The development of aortic dissection (AD) is closely associated with extracellular matrix degradation and the apoptosis of vascular smooth muscle cells (VSMCs). Antioxidant-1 (ATOX1), a copper-binding protein, the precise mechanisms by which it contributes to extracellular matrix (ECM) degradation, VSMC apoptosis, and the onset of AD remain to be further elucidated.

Through high-throughput sequencing, we identified a significant increase in the expression of ATOX1 in patients with AD. Further validation using tissue staining, RT-PCR and Western blot revealed that ATOX1 expression was elevated in AD patients, AD mouse models, and in vitro human aortic vascular smooth muscle cells (HAVSMCs) induced by Angiotensin II (AngII). In vitro experiments showed that silencing ATOX1 or pharmacologically inhibiting ATOX1 with DC_AC50 significantly reduced copper ion expression and the secretion of matrix metalloproteinases (MMPs), while alleviating cell apoptosis in HAVSMCs. Targeted knockdown of ATOX1 in smooth muscle cells using adeno-associated virus vector 9 (AAV9) or pharmacological inhibition of ATOX1 effectively slowed the progression of AD in a β-aminopropionitrile (BAPN)-induced mouse model. Additionally, ATOX1 expression is directly regulated by miR-133b, which was found to be significantly downregulated in the serum and aortic tissues of AD patients, exhibiting an inverse correlation with ATOX1 upregulation in AD. MiR-133b mimic successfully reversed the effects of ATOX1-induced MMPs secretion and apoptosis in HAVSMCs. Lastly, overexpression of miR-133b through AAV9 significantly attenuated the progression of BAPN-induced AD in mice.

Our study suggests that inhibiting ATOX1 may reduce ECM degradation and cell apoptosis, thereby slowing the progression of AD, and highlights ATOX1 inhibition as a potential new strategy for AD treatment.