The angiopoietin-tie2 system in coronary artery endothelium prevents oxidized low-density lipoprotein-induced apoptosis

Objectives: A healthy, intact coronary artery endothelium is important beca use most common coronary artery diseases result from loss of endothelial in tegrity. In this study, we explored the biological significance of the angi opoietin-Tie2 system in porcine coronary artery. Methods: Cultured porcine coronary artery endothelial cells and explanted coronary arteries were used . Results: Immunohistochemical analyses indicated that Ang1 is selectively expressed in vascular muscular cells, whereas angiopoietin-2 (Ang2) and Tie 2 are selectively expressed in endothelial cells. Accordingly, Ang1 mRNA is mainly expressed in cultured porcine coronary artery vascular smooth muscl e cells, whereas Ang2 and Tie2 mRNAs are mainly expressed in cultured porci ne: coronary artery endothelial cells (PCAECs). Ang1 (200 ng/ml) induced Ti e2 phosphorylation, while Ang2 (200 ng/ml) did not produce Tie2 phosphoryla tion. Ang1 increased the survival of cultured PCAECs during apoptosis induc ed by oxidized low-density Lipoprotein (OxLDL). This survival effect was do es-dependent and PI. Furthermore, Ang1 also protected endothelial cells of explanted coronary artery against OxLDL-induced apoptosis artery. Conclusio n: These results suggest that adult coronary artery contains Ang1-Tie2 comp onents that enhance endothelial cell survival to help maintain the normal i ntegrity of the coronary artery endothelium. (C) 2001 Elsevier Science B.V. All rights reserved.