title: Monosodium urate monohydrate crystals induce the release of the proinflammatory protein S100A8/A9 from neutrophils.
abstract: The neutrophil cytoplasmic protein S100A8/A9 (along with S100A8 and S100A9) is chemotactic and stimulates neutrophil adhesion by activating the beta2-integrin CD11b/CD18. It is also essential to neutrophil migration in vivo in response to monosodium urate monohydrate (MSUM) crystals, the principal etiologic agent of gout. S100A8/A9 is present in the synovial fluid of patients with gout and arthritis and is secreted by activated monocytes; however, its mechanism of release by neutrophils remains unknown. The aim of this study was to identify the mechanism of stimulation of the release of S100A8/A9 by MSUM-activated neutrophils. Here, we show that S100A8/A9 is released by neutrophils stimulated with MSUM crystals and that this release could be enhanced by preincubating neutrophils with granulocyte macrophage-colony stimulating factor. Antibodies directed against CD11b and CD16 blocked the release induced by MSUM crystals, suggesting that Fc receptor for immunoglobulin G (FcgammaR)IIIB (CD16) and CD11b/CD18 were involved in the stimulation by MSUM crystals. Neutrophil preincubation with the Src kinase inhibitor 4-amino-5-(4-chlorophenyl)-7-(t-butyl) pyrazolo[3,4-d]pyrimidine and the Syk tyrosine kinase inhibitor trans-3,3',4,5'-tetrahydrozystilbene significantly reduced the release of S100A8/A9, suggesting that the Src tyrosine kinase family and Syk were involved. In addition, wortmannin reduced neutrophil release of S100A8/A9, indicating a potential involvement of phosphatidylinolitol-3 kinase in this release. Preincubation of neutrophils with the tubulin depolymerization promoters nocodazole and vincristine reduced MSUM-induced release, suggesting a tubulin-associated pathway of release. These results indicate that S100A8/A9 is released by MSUM crystal-stimulated neutrophils following activation of CD11b, CD16, Src kinases, Syk, and tubulin polymerization.
authors.affiliation: Centres de Recherche en Infectiologie, Room RC 709, CRCHUL, Université Laval, 2705, Laurier Blvd., Sainte-Foy, Quebec, Canada G1V 4G2.
authors.forename: Carle
authors.initials: C
authors.lastname: Ryckman
authors.forename: Caroline
authors.initials: C
authors.lastname: Gilbert
authors.forename: Rinaldo
authors.initials: R
authors.lastname: de Médicis
authors.forename: André
authors.initials: A
authors.lastname: Lussier
authors.forename: Karen
authors.initials: K
authors.lastname: Vandal
authors.forename: Philippe A
authors.initials: PA
authors.lastname: Tessier
mesh_terms: D040501:Calgranulin A / Q000378:metabolism*; D040502:Calgranulin B / Q000378:metabolism*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism; D006801:Humans; D009504:Neutrophils / Q000378:metabolism*; D050257:Tubulin Modulators; D014527:Uric Acid / Q000378:metabolism*
chemical_list: D040501:Calgranulin A; D040502:Calgranulin B; D050257:Tubulin Modulators; D014527:Uric Acid; D016178:Granulocyte-Macrophage Colony-Stimulating Factor