title: Very late antigen-4 in CD18-independent neutrophil emigration during acute bacterial pneumonia in mice.
abstract: This study tested the hypothesis that very late antigen (VLA)-4 mediates CD18-independent neutrophil emigration into the airspaces induced by either Streptococcus pneumoniae, a stimulus that induces primarily CD18-independent neutrophil emigration, or Escherichia coli, toward which only 20-30% of the total number of neutrophils emigrate through CD18-independent pathways. In wild-type (WT) mice, VLA-4 expression was less on neutrophils that emigrated into the airspaces than on circulating neutrophils. Vascular cell adhesion molecule-1 (VCAM-1) mRNA, the major endothelial cell ligand for VLA-4, increased more in E. coli than in S. pneumoniae pneumonia. VCAM-1 protein expression was not detected in capillaries, the major site of neutrophil emigration. Neutrophil emigration during E. coli or S. pneumoniae pneumonia was similar in mice given antibodies against both CD18 and VLA-4 compared with mice given the anti-CD18 antibody and a control antibody. However, in hematopoietically reconstituted mice with both WT and CD18-deficient neutrophils in their blood, the migration of CD18-deficient neutrophils in response to S. pneumoniae was slightly but significantly less in animals pretreated with the anti-VLA-4 antibody than in those receiving a control antibody. These data suggest that VLA-4 plays a small role in CD18-independent neutrophil emigration, but the majority of CD18-independent neutrophil emigration induced by bacteria in the lungs occurs through VLA-4-independent mechanisms.
authors.affiliation: Division of Integrative Biology, Department of Pediatrics, Rainbow Babies and Children's Hospital and Case Western Reserve University, Cleveland, Ohio 44106, USA.
authors.forename: Sadatomo
authors.initials: S
authors.lastname: Tasaka
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Richer
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Mizgerd
authors.forename: Claire M
authors.initials: CM
authors.lastname: Doerschuk
mesh_terms: D000208:Acute Disease; D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology; D018821:CD18 Antigens; D004927:Escherichia coli Infections / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D007249:Inflammation / Q000276:immunology; D039041:Integrin alpha4beta1; D016023:Integrins / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009504:Neutrophils / Q000276:immunology / Q000378:metabolism*; D018410:Pneumonia, Bacterial / Q000276:immunology*; D011018:Pneumonia, Pneumococcal / Q000276:immunology; D016201:Receptors, Lymphocyte Homing / Q000276:immunology / Q000378:metabolism*; D016029:Receptors, Very Late Antigen / Q000276:immunology / Q000378:metabolism*; D019010:Vascular Cell Adhesion Molecule-1 / Q000276:immunology / Q000378:metabolism
chemical_list: D000888:Antibodies, Anti-Idiotypic; D018821:CD18 Antigens; D007074:Immunoglobulin G; D039041:Integrin alpha4beta1; D016023:Integrins; D016201:Receptors, Lymphocyte Homing; D016029:Receptors, Very Late Antigen; D019010:Vascular Cell Adhesion Molecule-1