Activation of AMPK prevents monocrotaline-induced pulmonary arterial hypertension by suppression of NF-κB-mediated autophagy activation.

AIMS: It has been shown that activation of autophagy is involved in the development of pulmonary arterial hypertension (PAH). Meanwhile, activation of nuclear factor-kappaB (NF-κB) has been found to induce autophagy in several types of human diseases including cancer and cardiac diseases. However, it is still unknown whether NF-κB mediates autophagy activation in PAH, and whether activation of adenosine monophosphate-activated protein kinase (AMPK) benefits PAH by modulation of NF-κB and autophagy. MAIN
METHODS: Rat models of PAH were established by intraperitoneally injection of monocrotaline (MCT). The right ventricle systolic pressure (RVSP), right ventricular hypertrophy index (RVHI), and percentage of medial wall thickness (%MT) were performed to evaluate the development of PAH. The translocation of NF-κB p65 from cytosol to nucleus, the protein levels of LC3A, LC3B, and RND3 were determined by immunoblotting. Metformin was used to activate AMPK. KEY
FINDINGS: NF-κB and autophagy were significantly activated in MCT-induced PAH rats, this was accompanied with the reduction of RND3. Pharmacological inhibition of NF-κB suppressed MCT-induced activation of autophagy and down-regulation of RND3 expression and reduced RVSP, RVHI, and %MT in MCT-induced PAH rats. In addition, activation of AMPK by metformin suppressed NF-κB-mediated autophagy activation and down-regulation of RND3 and therefore reduced RVSP, RVHI, and %MT in MCT-induced PAH. SIGNIFICANCE: NF-κB-induced autophagy activation and consequent down-regulation of RND3 contributes to the development of PAH in MCT-treated rats. Activation of AMPK prevents the development of PAH by targeting on NF-κB to suppress autophagy and vascular remodeling.