title: Promotion of neutrophil adherence to human osteoblasts by microcrystals and f-Met-Leu-Phe.
abstract: Human osteoblast-like cells (hOB) stimulated by monosodium urate monohydrate (MSUM) or calcium pyrophosphate dihydrate (CPPD) microcrystals produce the neutrophil chemoattractant IL-8. We investigated whether human neutrophils can adhere to hOB and respond to hOB preactivated by MSUM, CPPD, or by f-Met-Leu-Phe (fMLP). Confluent hOB were coincubated with human blood neutrophils in the presence of MSUM, CPPD or fMLP. MSUM, CPPD, and fMLP stimulated a significant adherence of neutrophils to hOB after a 1h incubation. This effect was not abrogated by pretreating the cells with an anti-CD18 mAb. MSUM stimulated more efficiently the adherence of neutrophils to non-preactivated hOB while CPPD were more efficient when hOB were preactivated. Crystal-free conditioned media from MSUM- or CPPD-stimulated hOB mobilized intracellular free calcium in human neutrophils. Thus, microcrystals were powerful promoters of neutrophil adherence to hOB via a CD18-independent mechanism. The bacterial peptide fMLP also stimulated the adherence of neutrophils to hOB. Functional neutrophil-hOB interactions could be important in bone pathophysiology of crystal- or infection-associated arthritis.
authors.affiliation: Department of Medicine, Centre de Recherche en Rhumatologie et Immunologie (CRRI), Université Laval, Quebec, Canada.
authors.forename: Line
authors.initials: L
authors.lastname: Bouchard
authors.forename: Paul H
authors.initials: PH
authors.lastname: Naccache
authors.forename: Patrice E
authors.initials: PE
authors.lastname: Poubelle
mesh_terms: D002118:Calcium / Q000378:metabolism; D002131:Calcium Pyrophosphate / Q000737:chemistry / Q000494:pharmacology; D002448:Cell Adhesion; D002478:Cells, Cultured; D003460:Crystallization; D017077:Culture Media, Conditioned / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects / Q000276:immunology*; D010006:Osteoblasts / Q000166:cytology / Q000502:physiology*; D014527:Uric Acid / Q000737:chemistry / Q000494:pharmacology
chemical_list: D017077:Culture Media, Conditioned; D014527:Uric Acid; D009240:N-Formylmethionine Leucyl-Phenylalanine; D002118:Calcium; D002131:Calcium Pyrophosphate