title: Role of galectin-3 in leukocyte recruitment in a murine model of lung infection by Streptococcus pneumoniae.
abstract: Pneumonia can be caused by a variety of pathogens, among which Streptococcus pneumoniae causes one of the most common forms of community-acquired pneumonia. Depending on the invading pathogen, the elements of the immune response triggered will vary. For most pathogens, such as Escherichia coli, neutrophil recruitment involves a well-described family of adhesion molecules, beta(2)-integrins. In the case of streptococcal pneumonia, however, neutrophil recruitment occurs mainly through a beta(2)-integrin-independent pathway. Despite decades of research on this issue, the adhesion molecules involved in neutrophil recruitment during lung infection by S. pneumoniae have not been identified. We have previously shown that galectin-3, a soluble mammalian lectin, can be found in lungs infected by S. pneumoniae, but not by E. coli, and can mediate the adhesion of neutrophils on the endothelial cell layer, implying its role in the recruitment of neutrophils to lungs infected with S. pneumoniae. In this study, using galectin-3 null mice, we report further evidence of the involvement of this soluble lectin in the recruitment of neutrophils to S. pneumonia-infected lungs. Indeed, in the absence of galectin-3, lower numbers of leukocytes, mainly neutrophils, were recruited to the infected lungs during infection by S. pneumoniae. In the case of beta(2)-integrin-dependent recruitment induced by lung infection with E. coli, the number of recruited neutrophils was not reduced. Thus, taken together, our data suggest that galectin-3 plays a role as a soluble adhesion molecule in the recruitment of neutrophils to lungs infected by S. pneumoniae, which induces beta(2)-integrin-independent migration.
authors.affiliation: Glycobiology Laboratory, Research Center for Infectious Diseases, Faculty of Medicine, Laval University, 2705 boulevard Laurier, Ste-Foy, Québec, Canada.
authors.forename: Julie
authors.initials: J
authors.lastname: Nieminen
authors.forename: Christian
authors.initials: C
authors.lastname: St-Pierre
authors.forename: Pampa
authors.initials: P
authors.lastname: Bhaumik
authors.forename: Françoise
authors.initials: F
authors.lastname: Poirier
authors.forename: Sachiko
authors.initials: S
authors.lastname: Sato
mesh_terms: D000818:Animals; D018821:CD18 Antigens / Q000502:physiology; D002464:Cell Migration Inhibition / Q000235:genetics / Q000276:immunology; D002634:Chemotaxis, Leukocyte / Q000235:genetics / Q000276:immunology*; D004195:Disease Models, Animal; D037502:Galectin 3 / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D020556:Neutrophil Infiltration / Q000235:genetics / Q000276:immunology; D011018:Pneumonia, Pneumococcal / Q000276:immunology* / Q000378:metabolism* / Q000473:pathology; D011650:Pulmonary Alveoli / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D012995:Solubility; D013296:Streptococcus pneumoniae / Q000276:immunology
chemical_list: D018821:CD18 Antigens; D037502:Galectin 3