# Pharmacological Enhancement of Integrated Stress Response Confers Protection in Calcific Aortic Valve Disease

## TL;DR

This study shows that boosting the body's stress response with drugs like Guanabenz and Sephin1 can protect against aortic valve disease by reducing calcification.

## Contribution

The study identifies pharmacological enhancement of the integrated stress response as a novel therapeutic strategy for calcific aortic valve disease.

## Key findings

- ISR activators Guanabenz and Sephin1 reduced aortic valve calcification in animal models.
- Nox4 overexpression suppressed calcification by enhancing the p-eIF2α/ATF4 pathway.
- Pharmacological ISR enhancement mitigated aortic valve stenosis severity in CAVD models.

## Abstract

•The ISR effector ATF4 and the ROS-generating enzyme Nox4 are up-regulated in the aortic valve leaflets of mice, rabbits, and patients with CAVD.•Knockdown of endogenous Nox4 significantly promoted calcification in cultured porcine AVIC and increased aortic valve calcium deposits in mice.•Nox4 overexpression suppressed AVIC calcification by enhancing ISR activation through the p-eIF2α/ATF4 pathway.•Guanabenz and Sephin1, ISR activators that prolong eIF2α phosphorylation, effectively alleviated AVIC osteoblastic-like differentiation and mitigated the severity of aortic valve calcification and stenosis in respective rabbit and mouse CAVD models.•This study suggests that pharmacological enhancement of the adaptive integrated stress response holds therapeutic potential for targeting CAVD.

The ISR effector ATF4 and the ROS-generating enzyme Nox4 are up-regulated in the aortic valve leaflets of mice, rabbits, and patients with CAVD.

Knockdown of endogenous Nox4 significantly promoted calcification in cultured porcine AVIC and increased aortic valve calcium deposits in mice.

Nox4 overexpression suppressed AVIC calcification by enhancing ISR activation through the p-eIF2α/ATF4 pathway.

Guanabenz and Sephin1, ISR activators that prolong eIF2α phosphorylation, effectively alleviated AVIC osteoblastic-like differentiation and mitigated the severity of aortic valve calcification and stenosis in respective rabbit and mouse CAVD models.

This study suggests that pharmacological enhancement of the adaptive integrated stress response holds therapeutic potential for targeting CAVD.

Previous studies have shown that Nox4 activates eIF2α/ATF4 signaling during the integrated stress response (ISR) and protects heart injury. However, their roles in calcific aortic valve disease (CAVD) remain unclear. Here, we show that both ATF4 and Nox4 are up-regulated in porcine aortic valve interstitial cells (AVIC) and in human aortic valves with CAVD. Nox4 knockdown promotes while Nox4 overexpression suppresses CAVD by modulating ISR. Importantly, ISR activators Guanabenz and Sephin1 effectively attenuate AVIC osteoblastic-like differentiation and mitigate CAVD in rabbits and mice, respectively. These findings highlight that pharmacological enhancement of the ISR is a promising therapeutic strategy for CAVD.