Expression of CCR2 by endothelial cells - Implications for MCP-1 mediated wound injury repair and in vivo inflammatory activation of endothelium

Endothelial cell proliferation and migration may play a central role in ang iogenesis, wound healing, and atherosclerosis, Although CXC chemokines can act on endothelial cells by influencing proliferation, an involvement of CC chemokines and endothelial expression of chemokine receptors remains to be elucidated. Reverse transcription polymerase chain reaction, RNase protect ion, Western blot, and flow cytometric analysis showed that human umbilical vein endothelial cells express mRNA and surface protein of the monocyte ch emotactic protein-1 (MCP-1) receptor CCR2, which was upregulated by inflamm atory cytokines. MCP-1 induced migration of endothelial cells in a transwel l assay, which was inhibited by the 9-76 MCP-1 receptor antagonist. Increas ed secretion of MCP-1 or interleukin-8, but not RANTES, on endothelial inju ry suggested a functional role of CCR2 in wound repair as measured by ELISA . After mechanical injury to endothelial monolayers, which spontaneously cl osed within 24 hours, wound repair was delayed by the 9-76 antagonist and b y a blocking monoclonal antibody to MCP-1, but not to interleukin-8, and wa s improved by exogenous MCP-1. This was confirmed by quantification of cell migration into the wound area, whereas proliferation and viability were un altered by MCP-1 or its analogue. Notably, immunohistochemistry of inflamed tissue revealed CCR2 staining on arterial, venous, and venular endothelium affected by cellular infiltration. This is the first demonstration of endo thelial CCR2 expression ex vivo, inferring its involvement in inflammatory conditions. Thus endothelial cells express functional CCR2 that may have im portant implications for endothelial wound repair and inflammatory reaction s.