ABSTRACT
Certain inflammatory stimuli render cultured human vascular endothelial cells hyperadhesive for neutrophils. This state is transient and reversible, in part because activated endothelial cells secrete a leukocyte adhesion inhibitor (LAI). LAI was identified as endothelial interleukin-8 (IL-8), the predominant species of which is an extended amino-terminal IL-8 variant. At nanomolar concentrations, purified endothelial IL-8 and recombinant human IL-8 inhibit neutrophil adhesion to cytokine-activated endothelial monolayers and protect these monolayers from neutrophil-mediated damage. These findings suggest that endothelial-derived IL-8 may function to attenuate inflammatory events at the interface between vessel wall and blood.
Subject(s)
Chemotactic Factors/isolation & purification , Endothelium, Vascular/physiology , Interleukin-1/pharmacology , Interleukins/isolation & purification , Neutrophils/physiology , Amino Acid Sequence , Biological Factors/pharmacology , Cell Adhesion/drug effects , Cells, Cultured , Chemotactic Factors/pharmacology , Culture Media/analysis , Cytokines , Endothelium, Vascular/cytology , Endothelium, Vascular/drug effects , Humans , Interleukin-8 , Interleukins/pharmacology , Molecular Sequence Data , Neutrophils/cytology , Neutrophils/drug effects , Recombinant Proteins/pharmacologyABSTRACT
We have examined the contributions of endothelial-leukocyte adhesion molecule-1 (ELAM-1) and the complex of leukocyte surface adhesion molecules designated CD11/CD18 to the adhesion of human polymorphonuclear leukocytes (PMN) to cultured human endothelial cells (HEC), activated by rIL-1 beta for 4 or 24 h. Inhibition of PMN attachment to IL-1-activated HEC was measured in a quantitative in vitro monolayer adhesion assay, after treatment with mAb directed to ELAM-1 (mAb H18/17), and to CD11a (mAb L11), CD11b (mAb 44), CD11c (mAb L29), and CD18 (mAb 10F12), alone or in combination. Pretreatment of activated HEC with mAb H18/7 inhibited PMN adhesion by 47 +/- 8% whereas control mAb had no effect. CD11/CD18-directed mAb significantly blocked PMN adhesion to activated HEC (anti-CD11a, 40 +/- 3%; anti-CD11b, 34 +/- 4%; anti-CD18, 78+/- 6% inhibition). The combination of mAb H18/7 and each of the various anti-CD11/CD18 mAb resulted in greater inhibition of PMN adhesion than any Mab alone. After 24 h of rIL-1 beta treatment, when ELAM-1 was markedly decreased but elevated PMN adhesion was still observed, mAb H18/7 had no effect on PMN adhesion. At this time, CD11/CD18-dependent adhesive mechanisms predominated and a CD11c-dependent mechanism became apparent (anti-CD11a, 67 +/- 4% inhibition; anti-CD11b, 45 +/- 9%; anti-CD11c, 26 +/- 6%; anti-CD18, 97 +/- 1%). In summary, PMN adhesion to IL-1-activated HEC involves both CD11/CD18-dependent mechanisms and an ELAM-1-dependent mechanism, and the relative contribution of these varies at different times of IL-1-induced HEC activation. The additive blocking observed at 4 h with mAb H18/7 in combination with CD11/CD18-directed Mab implies that members of the CD11/CD18 complex do not function as an obligate ligand(s) for ELAM-1.
Subject(s)
Antigens, Differentiation/physiology , Antigens, Surface/physiology , Endothelium, Vascular/physiology , Interleukin-1 , Membrane Glycoproteins/physiology , Neutrophils/physiology , Antibodies, Monoclonal/physiology , Antigens, Differentiation/immunology , Antigens, Surface/immunology , Antigens, Surface/metabolism , CD11 Antigens , CD18 Antigens , Cell Adhesion Molecules , Endothelium, Vascular/immunology , Flow Cytometry , Fluorescent Antibody Technique , Humans , Membrane Glycoproteins/immunology , Neutrophils/immunology , Recombinant ProteinsABSTRACT
Adhesion of polymorphonuclear leukocytes (PMN) to the endothelial lining of blood vessels is an essential component of the inflammatory response. We have examined the effects of various lipoxygenase metabolites of arachidonic acid on PMN adhesion to cultured vascular endothelial cells, using a quantitative monolayer adhesion assay. Our results indicated that leukotriene B4 (LTB4) could effectively stimulate PMN adhesion to endothelial cell surfaces, in contrast to the sulfidopeptide leukotrienes C4, D4, and E4, and the monohydroxyacid lipoxygenase products of leukocytes and platelets, 5S-hydroxy-6-trans-8,11,14-cis-eicosatetraenoic acid and 12S-hydroxy-5,8-cis,10-trans,14-cis-eicosatetraenoic acid, respectively. LTB4-stimulation of PMN-endothelial adhesion did not appear to be dependent upon the generation of cyclooxygenase metabolites, nor was it inhibited by exogenous prostacyclin. Enhanced PMN adhesion was observed with endothelial cells that were cultured from different types of large vessels (arteries and veins) in several species. These findings suggest an important pathophysiologic role for LTB4 in regulating leukocyte-vessel wall interactions.
