title: The unique property of the CC chemokine regakine-1 to synergize with other plasma-derived inflammatory mediators in neutrophil chemotaxis does not reside in its NH2-terminal structure.
abstract: The recently discovered CC chemokine, regakine-1, is constitutively present in bovine serum and synergizes with the CXC chemokine interleukin-8 (IL-8) to chemoattract neutrophils. Here we show that regakine-1 cooperates with the CXC chemokine receptor 2 ligand neutrophil activating protein-2 (NAP-2) and the anaphylatoxin C5a, two other mediators of inflammation present in the circulation. Neutrophil chemotaxis was 3-fold enhanced when regakine-1 (100 ng/ml) and C5a (30 ng/ml) were combined at concentrations present in bovine or human plasma, respectively. This synergy was also observed when neutrophils were preincubated with regakine-1. Plasma chemokines such as NAP-2, beta-thromboglobulin, and hemofiltrate CC-chemokine-1 did not affect C5a chemotactic activity. The capability of regakine-1 to synergize with C5a, NAP-2, or N-formyl-methionyl-leucyl-phenylalanine (fMLP) was not observed for monocyte chemotactic protein-3 (MCP-3), another CC chemokine that weakly chemoattracts neutrophils. Regakine-1 also failed to cooperate with MCP-3 and macrophage inflammatory protein-1alpha in neutrophil chemotaxis. The receptor of regakine-1 is not known yet. Competition with labeled fMLP or C5a for binding to neutrophils or receptor transfected cell lines demonstrated that regakine-1 did not alter receptor recognition. The protein kinase inhibitors 2'-amino-3'-methoxyflavone (PD98059), wortmannin and staurosporin had no effect on the synergy between C5a and regakine-1. Although NH2-terminal truncation affects the chemotactic potency of most chemokines, it did not affect the synergistic capacity of regakine-1 with C5a on neutrophils. These findings indicate that the constitutive plasma chemokine regakine-1 is a stable enhancer of the inflammatory response and that its blockade might be beneficial in acute and systemic inflammatory disorders.
authors.affiliation: Laboratory of Molecular Immunology, Rega Institute for Medical Research, University of Leuven, Leuven, Belgium.
authors.forename: Mieke
authors.initials: M
authors.lastname: Gouwy
authors.forename: Sofie
authors.initials: S
authors.lastname: Struyf
authors.forename: Frank
authors.initials: F
authors.lastname: Mahieu
authors.forename: Willy
authors.initials: W
authors.lastname: Put
authors.forename: Paul
authors.initials: P
authors.lastname: Proost
authors.forename: Jo
authors.initials: J
authors.lastname: Van Damme
mesh_terms: D054407:Chemokine CCL4; D054410:Chemokine CCL7; D019742:Chemokines, CC / Q000494:pharmacology*; D002633:Chemotaxis; D015936:Complement C5a / Q000378:metabolism; D016207:Cytokines; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D019402:Macrophage Inflammatory Proteins / Q000378:metabolism; D018945:Monocyte Chemoattractant Proteins / Q000378:metabolism; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000378:metabolism; D009504:Neutrophils / Q000187:drug effects* / Q000502:physiology; D010455:Peptides / Q000378:metabolism*; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D014162:Transfection; D001620:beta-Thromboglobulin
chemical_list: C515450:CCL7 protein, human; D054407:Chemokine CCL4; D054410:Chemokine CCL7; D019742:Chemokines, CC; D016207:Cytokines; D004791:Enzyme Inhibitors; D019402:Macrophage Inflammatory Proteins; D018945:Monocyte Chemoattractant Proteins; C061615:PPBP protein, human; D010455:Peptides; D047428:Protein Kinase Inhibitors; D001620:beta-Thromboglobulin; C426232:regakine 1; D009240:N-Formylmethionine Leucyl-Phenylalanine; D015936:Complement C5a; D011494:Protein Kinases