title: Osteopontin alters the functional profile of porcine microglia in vitro.
abstract: OPN (osteopontin) is a secreted glycoprotein predominantly expressed in bone matrix and kidney tissue. More recently, a neuroprotective role has been attributed to this cytokine since it can be up-regulated by microglia in neurodegeneration and inflammation. We demonstrate the expression of OPN within primary cultured microglia. Microglia incubated in vitro with different concentrations (0.1 fM-1 nM) of recombinant OPN showed increased proliferation at 10 fM. Moreover, conditioned medium of LLC-PK1 cells, a pig renal epithelial cell line and a known source of secreted OPN, more than doubled the rate of proliferation of microglia. Addition of an anti-OPN polyclonal antibody completely reversed this effect. Treatment with OPN dose-dependently also inhibited microglial superoxide production. In contrast, phagocytosis of fluorescent-labelled beads was enhanced by OPN. In conclusion, OPN shifts microglia, at least in vitro, to an alternative functional profile more fit to the immune-balanced microenvironment of the CNS (central nervous system).
authors.affiliation: Department of Veterinary Sciences, University of Antwerp, Wilrijk, Antwerp, Belgium. bart.tambuyzer@ua.ac.be
authors.forename: Bart R
authors.initials: BR
authors.lastname: Tambuyzer
authors.forename: Christophe
authors.initials: C
authors.lastname: Casteleyn
authors.forename: Hans
authors.initials: H
authors.lastname: Vergauwen
authors.forename: Steven
authors.initials: S
authors.lastname: Van Cruchten
authors.forename: Chris
authors.initials: C
authors.lastname: Van Ginneken
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000378:metabolism; D018374:LLC-PK1 Cells; D017628:Microglia / Q000166:cytology* / Q000378:metabolism*; D053495:Osteopontin / Q000032:analysis / Q000378:metabolism*; D010587:Phagocytosis; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D013552:Swine / Q000378:metabolism
chemical_list: D017077:Culture Media, Conditioned; D011994:Recombinant Proteins; D053495:Osteopontin; D013481:Superoxides