title: Regulation of polymorphonuclear neutrophil CD16 and CD11b/CD18 expression by matrix proteins during hypoxia is VLA-5, VLA-6 dependent.
abstract: We investigated the effects of hypoxia on matrix protein regulation of polymorphonuclear neutrophil (PMN) CD16 and CD11b/CD18 expression. Adherence of PMN to fibronectin increased CD16 expression during hypoxia over levels seen during normoxia, while adherence of PMN to either fibronectin or laminin increased CD11b/CD18 expression during hypoxia over levels seen during normoxia. Kinetics assays demonstrated a t1/2 approximately 60 min and 30 min of hypoxia for maximal up-regulation of CD16 and CD11b/CD18, respectively. Incubation of fluid-phase PMN with anti-VLA-5 (alpha 5/beta 1) and anti-VLA-6 (alpha 6/beta 1) mAbs blocked the effect of fibronectin and laminin on CD16 and CD11b/CD18 expression. Cross-linking of both fluid-phase and adherent PMN VLA-5 and VLA-6 receptors resulted in a progressive increase in CD16 and CD11b/CD18 expression during hypoxia, but not normoxia. Increases in CD16 and CD11b/CD18 expression resulted in increased E anti-Fc gamma RIII and EC3bi rosetting. Inhibition of GPLC activity and IP3 production with U73122 and cyclopiazonic acid blocked the ability of fibronectin to increase CD16 expression and E anti-Fc gamma RIII rosetting. Inhibition of protein tyrosine kinase with genistein and herbimycin A blocked the ability of laminin to increase CD11b/CD18 expression and EC3bi rosetting. Depletion of intracellular Ca2+ abrogated the effects of fibronectin and laminin on CD16 and CD11b/CD18 expression, while restoration of intracellular Ca2+ restored the ability of fibronectin and laminin to increase CD16 and CD11b/CD18 expression. These results demonstrate that during hypoxia integrin signaling via alpha 5/beta 1 and alpha 6/beta 1 results in the increased expression of CD16 and CD11b/CD18. This increase in receptor expression results in biologically active receptors and is dependent upon intracellular Ca2+, GPLC, and protein tyrosine kinase activity.
authors.affiliation: Department of Surgery, School of Medicine, Rhode Island Hospital/Brown University, Providence 02903, USA.
authors.forename: H
authors.initials: H
authors.lastname: Simms
authors.forename: R
authors.initials: R
authors.lastname: D'Amico
mesh_terms: D018845:CD11 Antigens / Q000096:biosynthesis*; D002118:Calcium / Q000378:metabolism; D015687:Cell Hypoxia; D002478:Cells, Cultured; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D006801:Humans; D039121:Integrin alpha6beta1; D016023:Integrins / Q000378:metabolism*; D009504:Neutrophils / Q000378:metabolism*; D017469:Receptors, Fibronectin / Q000378:metabolism*; D017452:Receptors, IgG / Q000096:biosynthesis*
chemical_list: D018845:CD11 Antigens; D016326:Extracellular Matrix Proteins; D039121:Integrin alpha6beta1; D016023:Integrins; D017469:Receptors, Fibronectin; D017452:Receptors, IgG; D002118:Calcium