Effects of tumor necrosis factor and epidermal growth factor on cell morphology, cell surface receptors, and the production of tissue inhibitor of metalloproteinases and IL-6 in human microvascular endothelial cells.

The effect of human TNF on cultured human microvascular endothelial (HME) cells was examined. Incubation with TNF alone transformed the morphology of HME cells from a cobblestone-like appearance into a disordered array of criss-crossed, elongated, spindle-shaped cells. Coadministration of epidermal growth factor (EGF) and TNF caused even more dramatic morphologic changes than TNF alone. Addition of basic fibroblast growth factor or insulin-like growth factor-I showed rather weak effects on cell morphology than EGF. Cell growth of HME cells was stimulated up to two-fold by TNF whereas addition of EGF additively enhanced the growth rate. Treatment of HME cells with 10 ng/ml EGF increased the binding of 125I-TNF, and Scatchard analysis showed increased TNF-R number by EGF treatment. Cellular response to TNF in the absence or presence of EGF was assessed by analyzing SDS-PAGE patterns of secreted proteins from HME cells. TNF enhanced the secretion of a protein of molecular weight 25,000 Da (25 kDa) which was found to be IL-6. In contrast, secretion of a polypeptide of 29 kDa was significantly increased when HME cells were treated with EGF, but not with TNF. Coadministration of TNF and EGF synergistically increased the secretion of the 29-kDa protein. This 29-kDa protein was found to be tissue inhibitor of metalloproteinases when assayed with antitissue inhibitor of metalloproteinases antibody. TNF and EGF also enhanced secretion of collagenase with Mr of approximately 55 kDa. Increased steady state levels of the inhibitor mRNA were observed when HME cells were treated with EGF, and coadministration of TNF further increased the levels. The morphologic transformation of HME cells by TNF and/or EGF is discussed in relation to their expression of the secreted proteins.