Expression of tumor necrosis factor-alpha in cultured human endothelial cells stimulated with lipopolysaccharide or interleukin-1alpha.
Tumor-necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine with a wide variety of biological effects. The most important source of this cytokine is monocytes/macrophages. It is a potent agonist in the activation of endothelial cells; however, the precise role of endothelial cells as a source of TNF-alpha is not known. In the present study, we addressed the possibility that TNF-alpha is produced by cultured human umbilical vein endothelial cells (HUVEC) stimulated with factors such as lipopolysaccharide (LPS) or interleukin-1alpha (IL-1alpha). LPS and IL-1alpha induced expression of TNF-alpha mRNA in HUVEC. IL-1alpha induced expression and secretion of TNF-alpha protein, but LPS did not induce production of TNF-alpha protein. Most of the TNF-alpha protein in cell lysate was found in the membrane fraction. The mRNA for TNF-alpha-converting enzyme (TACE) was expressed in unstimulated HUVEC, and its level was not altered by treatment with LPS or IL-1alpha. Transfection of HUVEC with full-length cDNA encoding the precursor TNF-alpha enhanced secretion of TNF-alpha protein by these cells, and treatment of the cells with a TACE inhibitor reduced the secretion. These results suggest that HUVEC produce TNF-alpha and have TACE activity. Secreted TNF-alpha may be involved in autocrine activation of endothelial cells, and TNF-alpha retained in cell membrane may serve as a juxtacrine system to activate target cells on the endothelial surface.
Imaizumi
T
T
Department of Pathological Physiology, Institute of Neurological Diseases, Hirosaki University School of Medicine, Japan. timaizum@cc.hirosaki-u.ac.jp
Itaya
H
H
Fujita
K
K
Kudoh
D
D
Kudoh
S
S
Mori
K
K
Fujimoto
K
K
Matsumiya
T
T
Yoshida
H
H
Satoh
K
K
D051722:ADAM Proteins; D000072198:ADAM17 Protein; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008666:Metalloendopeptidases / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*
D007375:Interleukin-1; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D051722:ADAM Proteins; D008666:Metalloendopeptidases; D000072198:ADAM17 Protein; C000606462:ADAM17 protein, human