Activated protein C utilizes the angiopoietin/Tie2 axis to promote endothelial barrier function.
Activated protein C (APC) is an anticoagulant, approved as a treatment for severe sepsis, that can prevent apoptosis, inflammation, and vascular leakage. The aim of this study was to investigate whether APC protects endothelial barrier function through the angiopoietin (Ang)/Tie2 axis. APC significantly up-regulated gene and protein expression of Tie2 and Ang1 in a dose (0.01-10 microg/ml)- and time (0.5-24 h)-dependent manner in human umbilical vein endothelial cells (HUVECs). Interestingly, it markedly inhibited Ang2 with an IC(50) of approximately 0.1 microg/ml. HUVEC permeability, measured using Evans blue dye transfer, was significantly reduced in the presence of APC, and, in concordance, the tight junction associated protein zona occludens (ZO)-1 was up-regulated and localized peripherally around cells, compared with controls. Smooth muscle cell migration toward APC-stimulated HUVECs was elevated compared with unstimulated cells. Blocking antibodies and small interfering (si) RNA treatment, compared with isotype (IgG) or scrambled siRNA controls, showed that APC requires 3 receptors, the endothelial protein C receptor, protease-activated receptor 1, and Tie2 to perform all these barrier stabilization functions. In summary, this study demonstrates that APC has novel effects on the Ang/Tie2 axis, which enhance endothelial barrier function and are likely to contribute to its therapeutic effect in sepsis and other diseases associated with vascular leakage.-Minhas, N., Xue, M., Fukudome, K., Jackson, C. J. Activated protein C utilizes the angiopoietin/Tie2 axis to promote endothelial barrier function.
Sutton Arthritis Research Laboratories, Level 10, Kolling Bldg., University of Sydney at Royal North Shore Hospital, St. Leonards 2065 NSW, Australia.
Nikita
N
Minhas
Meilang
M
Xue
Kenji
K
Fukudome
Christopher J
CJ
Jackson
D042682:Angiopoietins / Q000378:metabolism*; D000925:Anticoagulants / Q000494:pharmacology*; D015703:Antigens, CD / Q000502:physiology; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D000074283:Endothelial Protein C Receptor; D004797:Enzyme-Linked Immunosorbent Assay; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D015151:Immunoblotting; D008565:Membrane Proteins / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism*; D011486:Protein C / Q000494:pharmacology*; D034741:RNA, Small Interfering; D044463:Receptor, PAR-1 / Q000502:physiology; D042787:Receptor, TIE-2 / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000037:antagonists & inhibitors / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014471:Umbilical Veins / Q000166:cytology; D062826:Zonula Occludens-1 Protein; D010975:Platelet Aggregation Inhibitors
D042682:Angiopoietins; D000925:Anticoagulants; D015703:Antigens, CD; D000074283:Endothelial Protein C Receptor; D008565:Membrane Proteins; C478370:PROCR protein, human; D010750:Phosphoproteins; D011486:Protein C; D034741:RNA, Small Interfering; D044463:Receptor, PAR-1; D011956:Receptors, Cell Surface; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein; D042787:Receptor, TIE-2; D010975:Platelet Aggregation Inhibitors