title: The Aminopeptidase CD13 Induces Homotypic Aggregation in Neutrophils and Impairs Collagen Invasion.
abstract: Aminopeptidase N (CD13) is a widely expressed cell surface metallopeptidase involved in the migration of cancer and endothelial cells. Apart from our demonstration that CD13 modulates the efficacy of tumor necrosis factor-α-induced apoptosis in neutrophils, no other function for CD13 has been ascribed in this cell. We hypothesized that CD13 may be involved in neutrophil migration and/or homotypic aggregation. Using purified human blood neutrophils we confirmed the expression of CD13 on neutrophils and its up-regulation by pro-inflammatory agonists. However, using the anti-CD13 monoclonal antibody WM-15 and the aminopeptidase enzymatic inhibitor bestatin we were unable to demonstrate any direct involvement of CD13 in neutrophil polarisation or chemotaxis. In contrast, IL-8-mediated neutrophil migration in type I collagen gels was significantly impaired by the anti-CD13 monoclonal antibodies WM-15 and MY7. Notably, these antibodies also induced significant homotypic aggregation of neutrophils, which was dependent on CD13 cross-linking and was attenuated by phosphoinositide 3-kinase and extracellular signal-related kinase 1/2 inhibition. Live imaging demonstrated that in WM-15-treated neutrophils, where homotypic aggregation was evident, the number of cells entering IL-8 impregnated collagen I gels was significantly reduced. These data reveal a novel role for CD13 in inducing homotypic aggregation in neutrophils, which results in a transmigration deficiency; this mechanism may be relevant to neutrophil micro-aggregation in vivo.
authors.affiliation: Department of Medicine, University of Cambridge School of Clinical Medicine and Addenbrooke's and Papworth Hospitals, Cambridge, United Kingdom.
authors.forename: Christine A
authors.initials: CA
authors.lastname: Fiddler
authors.affiliation: Department of Medicine, University of Cambridge School of Clinical Medicine and Addenbrooke's and Papworth Hospitals, Cambridge, United Kingdom.|Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge, United Kingdom.
authors.forename: Helen
authors.initials: H
authors.lastname: Parfrey
authors.affiliation: Department of Medicine, University of Cambridge School of Clinical Medicine and Addenbrooke's and Papworth Hospitals, Cambridge, United Kingdom.
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Cowburn
authors.affiliation: Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Ding
authors.initials: D
authors.lastname: Luo
authors.affiliation: Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Gerard B
authors.initials: GB
authors.lastname: Nash
authors.affiliation: Cancer Research UK Cambridge Institute and Department of Oncology, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Gillian
authors.initials: G
authors.lastname: Murphy
authors.affiliation: Department of Medicine, University of Cambridge School of Clinical Medicine and Addenbrooke's and Papworth Hospitals, Cambridge, United Kingdom.
authors.forename: Edwin R
authors.initials: ER
authors.lastname: Chilvers
mesh_terms: D000328:Adult; D000911:Antibodies, Monoclonal / Q000276:immunology; D018826:CD13 Antigens / Q000276:immunology / Q000378:metabolism*; D016764:Cell Polarity; D002478:Cells, Cultured; D002634:Chemotaxis, Leukocyte; D024042:Collagen Type I / Q000378:metabolism*; D006801:Humans; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000166:cytology* / Q000187:drug effects / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D024042:Collagen Type I; D009240:N-Formylmethionine Leucyl-Phenylalanine; D018826:CD13 Antigens