Pharmacologic IRE1α kinase inhibition alleviates aortic dissection by decreasing vascular smooth muscle cells apoptosis.

Aortic dissection (AD) is a rare but catastrophic disorder, and associated with significant morbidity among survivors. This study aimed to target IRE1α-XBP1s pathway pharmacologically, and evaluate its therapeutic potential in the occurrence and progression of AD. Western Blot and immunohistochemistry results showed that expression of XBP1s was significantly increased in the human aorta samples of AD group in compared with the control group, and exclusively in aortic vascular smooth muscle cells (VSMCs). Further in vitro study revealed that Angiotensin II (Ang II) could increase the expression of XBP1s and promote its nuclear translocation in cultured VSMCs, which leads to numerous gene transcription, including gp91phox, Chop, Cleaved-caspase 3, Bax, and Bcl-2. These genes contribute to the production of reactive oxygen species (ROS), VMSCs phenotypic switch and apoptosis. Whereas an IRE1α endoribonuclease domain inhibitor MKC-3946 could reverse it. Finally, the efficacy of MKC-3946 was tested in a mouse AD model. As shown in vitro, MKC-3946 could reduce the expression of XBP1s and protect against AD by suppressing XBP1s associated ROS production and apoptosis in VSMCs in vivo. The current study revealed the relevant role of IRE1α-XBP1s signaling pathway in AD occurrence and progression. MKC-3946 could be of great potential in clinical application.