1. Academic Validation
  2. AMP-activated protein kinase mediates the effects of lipoprotein-associated phospholipase A2 on endothelial dysfunction in atherosclerosis

AMP-activated protein kinase mediates the effects of lipoprotein-associated phospholipase A2 on endothelial dysfunction in atherosclerosis

  • Exp Ther Med. 2017 Apr;13(4):1622-1629. doi: 10.3892/etm.2017.4142.
Li Yang 1 2 Hong-Liang Cong 2 Shu-Feng Wang 2 Ting Liu 3
Affiliations

Affiliations

  • 1 Department of Cardiology, Thoracic Clinical College, Tianjin Medical University, Tianjin 300222, P.R. China.
  • 2 Department of Cardiology, Tianjin Chest Hospital, Tianjin 300222, P.R. China.
  • 3 Tianjin Cardiovascular Institute, Tianjin 300222, P.R. China.
Abstract

The present study aimed to investigate the effects of lipoprotein-associated Phospholipase A2 (Lp-PLA2) on endothelial dysfunction in an in vitro cell model of atherosclerosis, and to determine whether AMP-activated protein kinase (AMPK) mediates the effects of Lp-PLA2 on endothelial dysfunction. A total of 392 patients with coronary artery disease (CAD), including various sub-conditions, were recruited, and the plasma concentrations of Lp-PLA2 were evaluated. In addition, an in vitro model of atherosclerosis was established by exposing human umbilical vein endothelial cells (HUVECs) to oxidized low-density lipoprotein (oxLDL). SB-435495 was used to inhibit Lp-PLA2, and compound C was used to suppress AMPK expression. Lp-PLA2, AMPKα and phosphorylated-AMPKα (T172) expression in HUVECs were evaluated using western blot analysis. The concentrations of nitric oxide (NO), endothelin 1 (ET-1), intercellular adhesion molecule 1 (ICAM-1) and platelet/endothelial cell adhesion molecule 1 (PECAM-1) in Cell Culture supernatant were determined using commercially available ELISA kits. MTT assays were employed to indicate changes in cell viability. The current study found the plasma Lp-PLA2 levels were elevated in the CAD patients with stable angina pectoris, unstable angina pectoris, acute coronary syndromes and acute myocardial infarction, compared with a healthy control population. In addition, the in vitro results showed that Lp-PLA2 expression levels were elevated in oxLDL-exposed HUVECs. Lp-PLA2 suppression could increase cell viability, induce the production of NO and decrease the secretion of ET-1, in addition to suppressing the expression of cell adhesion molecules, including ICAM-1 and PECAM-1 in oxLDL-exposed HUVECs. The expression of AMPKα and phosphorylated-AMPKα (T172) was regulated by Lp-PLA2, and AMPK suppression was able to reverse the effects of Lp-PLA2 with regard to cell viability, endothelial vasorelaxation capacity and the secretion of adhesion molecules in oxLDL-exposed HUVECs. In conclusion, the present study provides initial evidence that Lp-PLA2 is able to cause endothelial dysfunction in an in vitro model of atherosclerosis, and the effects of Lp-PLA2 on endothelial dysfunction was at least partially a result of the downregulation of AMPKα, thus contributing to the progression of atherosclerosis.

Keywords

AMP-activated protein kinase; atherosclerosis; endothelial dysfunction; lipoprotein-associated phospholipase A2.

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