Abstract 699: Mitochondrial Aldehyde Dehydrogenase (aldh-2) Protects Against Lipopolysaccharide-induced Myocardial Contractile Dysfunction by Suppression of ER Stress via Regulation of Autophagy
Lipopolysaccharide (LPS), a constituent of the outer membrane of Gram-negative bacteria, is the principal culprit factor responsible for the development of multi-organ failure including septic heart failure - a major contributor to increased mortality in patients with sepsis. However, there is still no efficacious treatment for septic cardiomyophathy. ALDH2 is well-known for its distinct beneficial role in cardiac pathologies including heart failure, ischemia and reperfusion injury. Little is known with regards to its effect on septic cardiomyopathy and the underlying mechanism. This study was designed to examine whether ALDH2 affects LPS-induced myocardial dysfunction and the underlying mechanism involved with a focus on ER stress and autophagy.
WT and ALDH2 transgenic mice were subjected to LPS (4 mg/kg, 4 h). Myocardial mechanical and intracellular Ca2+ properties were examined in FVB wild-type and ALDH2 transgenic mice using echocardiography and IonOptix SoftEdge techniques. Protein markers for ER stress, autophagy and related signaling molecules were evaluated. LPS compromised cardiac contractile function shown as reduced fractional shortening, peak shortening, maximal velocity of shortening/relengthening, prolonged relengthening duration and impaired intracellular Ca2+ homeostasis, associated with overt ER stress, upregulated autophagy, suppressed phosphorylation of Akt and its downstream signal molecule mTOR, the effects of which were attenuated by ALDH2. In vitro study revealed that the ER stress inducer tunicamycin exacerbated LPS-induced myocardial dysfunction, which was abrogated by the ALDH2 activator Alda-1 and the autophagy inhibitor 3-MA. Interestingly, the beneficial effect of Alda-1 was obliterated by the autophagy inducer rapamycin, Akt inhibitor AktI and mTOR inhibitor RAD001.
We conclude that ALDH2 protects against LPS-induced myocardial dysfunction possibly through suppression of ER stress and inhibition of autophagy.
Author Disclosures: J. Pang: None. X. Xu: None. Y. Zhang: None. Y. Chen: None. J. Ren: None.
- © 2015 by American Heart Association, Inc.