Ang-1 Inhibited Endoplasmic Reticulum Stress and Apoptosis of VECs in Rats with aSAH-induced CVS Through the Regulated PI3K/Akt Pathway

Abstract

Aims: To explore angiopoietin-1 (Ang-1) involved in cerebral vasospasm (CVS) after aneurysmal subarachnoid hemorrhage (aSAH) through its effect on endoplasmic reticulum stress (ERS) and apoptosis of vascular endothelial cells (VECs).

Background: CVS accounts for high morbidity and mortality of aSAH. Abnormal cellular physiological processes of VECs play a critical role in aSAH-induced CVS. In addition, Ang-1 is involved in regulating vascular structure and function.

Objective: To study the role of Ang-1 played in CVS and the underlying mechanism.

Methods: Blood samples of 130 aSAH patients were collected from 2016 to 2020 at West China Hospital of Sichuan University. A two-hemorrhage rodent model was employed to structure an aSAH-induced CVS rat model. Moreover, oxyHb was used to treat VECs to construct a CVS cell model in vitro. ELISA was used to measure the level of Ang-1 and HE staining to assess the rat's basilar arteries. Subsequently, CCK-8 was used to detect cell viability ability, and flow cytometry was used to test the cell apoptosis rate. Western blotting was used to determine the expression level of ERS marker and apoptosis-related proteins.

Results: There was an abnormally low expression of Ang-1 in CVS patients and CVS rats; besides, oxyHb treatment decreased Ang-1 in VECs in a concentration-dependent manner. Ang-1 treatment led to the thinner basilar artery wall and lumen circumference in CVS rats; moreover, in oxyHbtreated VECs, Ang-1 treatment inhibited ERS and apoptosis. In addition, the expression of p-PI3K and p-Akt in the CVS group decreased, while the expression of p53 in the CVS group increased. The expression of p-PI3K and p-Akt in 8 CVS rats negatively correlates with the expression of Ang- 1, but the correlation between p53 and Ang-1 was positive. Furthermore, the results suggested that Ang-1 suppressed ERS and apoptosis of VECs through the regulated PI3K/Akt/p53 pathway.

Conclusion: Elevated Ang-1 inhibited p53-mediated ERS and apoptosis of VECs through the activated PI3K/Akt pathway; Ang-1 might be an attractive treatment strategy for CVS.

Keywords: Aneurysmal subarachnoid hemorrhage; PI3K/Akt pathway; angiopoietin-1; cerebral vasospasm; endoplasmic reticulum stress; vascular endothelial cells.