Human Endothelial Cells Synthesize ENA-78: Relationship to IL-8 and to Signaling of PMN Adhesion

Abstract

The interaction of endothelial cells and polymorphonuclear leukocytes (PMNs, neutrophils) is a critical determinant of the acute inflammatory response, and mirrors cell-cell interactions in other biologic systems. Adhesion molecules that tether the two cells together, and signaling factors that bind to receptors on the leukocytes and mediate their spatially-localized activation, govern PMN responses as they adhere to and traverse stimulated endothelial cells. Here we show that cultured human endothelial cells express two members of the C-X-C family of chemokines, epithelial neutrophil activating peptide-78 (ENA-78) and interleukin (IL)-8, when stimulated by IL-1 or certain other agonists. ENA-78, previously thought to be exclusively a product of epithelium, is expressed by in situ endothelium in inflamed human lung and other tissues as well as by cultured endothelial cells. The regulation of ENA-78 and IL-8 share certain features in common and they have overlapping biologic activities, including the ability to induce PMN adhesiveness. This was demonstrated in experiments in which we found that ENA-78 induces inside-out signaling of beta2 integrins on the PMN surface, as does IL-8. Antibody blocking experiments demonstrated that ENA-78 contributes to the proadhesive activity for neutrophils that is released by endothelial cells stimulated with IL-1 for a prolonged period and that it acts in concert with IL-8, which provides the major component of the signal for adhesion under this condition. We also show, however, that the temporal expression and secretion of ENA-78 and other characteristics of its handling by stimulated endothelial cells vary from the expression of IL-8, indicating that differential regulation of the two signaling chemokines occurs in this cell type.

The CXC Chemokine GCP-2/CXCL6 Is Predominantly Induced in Mesenchymal Cells by Interleukin-1β and Is Down-Regulated by Interferon-γ: Comparison with Interleukin-8/CXCL8

“…Similarly, ENA-78 production by endothelial cells has been shown after stimulation with IL-1␤ and LPS (Imaizumi et al, 1997;Lukacs et al, 1995;Strieter et al, 1992). These induction experiments suggest that GCP-2 is a typical mesenchymal cell-derived chemokine.…”

Differential Ability of Exogenous Chemotactic Agents to Disrupt Transendothelial Migration of Flowing Neutrophils

“…ENA-78 and GRO-␣ can also activate neutrophils through CXCR2 and induce migration, and have higher affinity for CXCR2 than CXCR1 (36 -38). Both ENA-78 and GRO-␣ can be produced by activated endothelial cells (47,48). We found that either could cause up-regulation of CD11b and immobilization of rolling neutrophils as efficiently as IL-8, albeit at a much higher concentration (1 g/ml).…”

Epithelial neutrophil-activating peptide-78 recruits neutrophils into pleural effusion

“…Originally, ENA-78 was characterised from the IL-1b-and tumour necrosis factor (TNF)-a-stimulated alveolar type II epithelial cell line A549 [9]. Now, it is well known that ENA-78 expression is inducible by a variety of inflammation mediators, including lipopolysaccharide, IL-1 and TNF-a, in epithelial cells [9,19], monocytes [20,21], platelets [22], endometrial stromal cells [23], endothelial cells [24] and macrophage [25].…”