Activated Protein C Induction of MCP-1 in Human Endothelial Cells: A Possible Role for Endothelial Cell Nitric Oxide Synthase

• Published in: Thrombosis research Vol. 103; no. 3; pp. 209 - 219
• Main Authors: Hooper, W.Craig, Phillips, Donald J., Renshaw, Mary A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.08.2001
• Subjects: Activated protein C; Chemokine CCL2 - biosynthesis; Dose-Response Relationship, Drug; Down-Regulation - drug effects; Endothelial cell; Endothelium, Vascular - cytology; Endothelium, Vascular - enzymology; Endothelium, Vascular - metabolism; eNOS; Fibrinolytic Agents - pharmacology; Humans; Immunoassay; Inflammation; Kinetics; Monocyte chemotactic protein-1; Nitric oxide; Nitric Oxide Synthase - genetics; Nitric Oxide Synthase - physiology; Nitric Oxide Synthase Type III; Protein C - metabolism; Protein C - pharmacology; RNA, Messenger - metabolism; Umbilical Veins; Up-Regulation - drug effects; eNOS; Endothelial cell; Inflammation; Activated protein C; Nitric oxide; Monocyte chemotactic protein-1
• ISSN: 0049-3848; 1879-2472
• DOI: 10.1016/S0049-3848(01)00319-X

Classically, activated protein C (APC) of the protein C/protein S anticoagulant pathway has functioned not only to inactivate the procoagulant factors Va and VIIIa but also to inhibit the activity of plasminogen activator inhibitor-1 (PAI-1). More recent data have suggested that the protein C/protein S pathway may serve as a physiological link between coagulation and inflammation. This APC pathway link was proposed because of observations showing that APC could both modulate the effects of cytokines and block neutrophil activation. As a further extension of the effect(s) of APC on cytokines, we found that APC, at the equivalent physiological protein C concentration of 4 μg/ml, significantly upregulated monocyte chemotactic protein-1 (MCP-1) RNA in human umbilical vein endothelial cells (HUVECs), as indicated by a ribonuclease protection assay (RPA) at 3 and 6 h with a return to near basal levels by 24 h. ELISA determinations demonstrated that 4 μg/ml of APC induced a significant ( P=.0001) increase in MCP-1 protein production over basal levels within a 24-h period. At the same concentration, APC downregulated endothelial cell nitric oxide synthase (eNOS) RNA. Downregulation first became apparent at 6 h and continued through 48 h of culture. This downregulation was concentration dependent over a range of 1.3–12 μg/ml, and there was no effect on cell viability within this range. In support of other studies, we also found that exogenously added nitric oxide (NO) inhibited MCP-1 production. These data suggest that APC may induce MCP-1 through the inhibition of eNOS.