Effect of nerve growth factor on endothelial cell biology: proliferation and adherence molecule expression on human dermal microvascular endothelial cells

In addition to its effect on the central nervous system, nerve growth factor (NGF) appears to play a key role in the initiation and maintenance of inflammation in many organs. NGF degranulates mast cells, recruits inflammatory cellular infiltrates and activates T cells. Extravascular migration of leukocytes is initially controlled by the interaction of cell surface adhesion molecules of leukocytes and endothelial cells. A marked upregulation of NGF in keratinocytes is also observed in conditions characterized by angiogenesis such as psoriasis and wound healing. In this study we investigated the role of NGF in inflammation by studying its effects on endothelial cell proliferation and intracellular adhesion molecule expression by endothelial cells. The effect of NGF on human dermal microvascular endothelial cell (HDMEC) proliferation was measured using the hexosaminidase assay. ICAM-1 expression on HDMEC was measured by ELISA. The function of ICAM-1 was assessed by adherence of peripheral blood mononuclear cells (PBMC) to HDMEC using Cr-51-labeled PBMC. There was a significant int crease in proliferation of HDMEC stimulated with NGF as compared to unstimulated HDMEC (P < 0.001). NGF neutralizing antibody decreased the mitogenic effect of NGF significantly (P < 0.05). NGF also increased ICAM expression on HDMEC as compared to unstimulated HDMEC (P < 0.05). NGF-neutralizing antibody decreased ICAM expression on NGF-stimulated HDMEC: (P < 0.05). The percentage of PBMC adherence was higher in NGF-stimulated HDMEC (P < 0.001). Anti-ICAM antibody decreased PBMC adherence. In the study reported here, the role of NGF in two important aspects of inflammation, i.e. angiogenesis and inflammatory cell recruitment at the site of inflammation, was investigated.