Journal Article
Interleukin-1 induces interleukin-8 secretion from endothelial cells by a juxtacrine mechanism
Kaplanski, G; Farnarier, C; Kaplanski, S; Porat, R; Shapiro, L; Bongrand, P; Dinarello, CA
Blood
ISSN: 0006-4971
EISSN: 1528-0020
Inflammation is characterized by migration of neutrophils through the endothelium, and the chemokine interleukin-8 (IL-8) appears to be involved. We asked whether adherence of cells bearing a membrane-form of interleukin 1 (IL-1) induces IL-8 secretion from human umbilical vein endothelial cells (HUVEC) and fibroblasts. Human peripheral blood mononuclear cells (PBMC) were stimulated with endotoxin for 12 hours and then fixed for 4 hours with paraformaldehyde. When these cells were added to HUVEC or fibroblasts, IL-8 production was induced. This stimulation by fixed PBMC was attributed to IL-1, because pretreatment of HUVEC or fibroblasts with IL-1 receptor antagonist (IL-1Ra) reduced the induction by 95% and 80%, respectively, P < .005. Using anti-IL-1 alpha monoclonal antibodies, reduction was complete, whereas anti-IL-1 beta had no effect. IL-1 alpha was shown on the surface of monocytes by fluorescence-activated cell sorter (FACS) analysis. Blockade of IL-1 receptors on PBMC did not affect the activity of membrane-associated IL-1 alpha, indicating that IL-1 is not anchored to the membrane through its receptors. However, PBMC treated with D-mannose before fixation resulted in a loss of activity; this loss of activity was associated with release of IL-1 alpha, not IL-1 beta, into the supernatant. Thus, anchoring of IL-1 alpha to the membrane may be via a lectin or mannose receptor-like interaction. Blockade of membrane IL-1 alpha required a 30-fold and fivefold excess of IL-1Ra compared with the amount required to block soluble IL-1 beta and IL-1 alpha, respectively. We conclude that the fixed PBMC IL-8 inducing activity is almost entirely caused by IL-1, that this represents IL-1 alpha bound to a surface lectin or mannose receptor on the monocyte, and that it functions in inflammation via juxtacrine interactions.
Cell Membrane/metabolism; Cell Separation; Cells, Cultured; Culture Media, Conditioned/chemistry; Dose-Response Relationship, Drug; Endothelium, Vascular/ drug effects/secretion; Fixatives/pharmacology; Flow Cytometry; Infant, Newborn; Interleukin 1 Receptor Antagonist Protein; Interleukin-1/ pharmacology; Interleukin-8/ secretion; Leukocytes, Mononuclear/drug effects/immunology; Lipopolysaccharides/pharmacology; Lymphocyte Activation; Mannose/pharmacology; Recombinant Proteins/pharmacology; Sialoglycoproteins/pharmacology; Solubility; Umbilical Veins