title: Localization of intercellular adhesion molecule-1 (ICAM-1) in the lungs of silica-exposed mice.
abstract: Intercellular adhesion molecule-1 (ICAM-1) is expressed on a variety of cells including endothelial cells, alveolar epithelial cells, and alveolar macrophages. Endothelial/epithelial cell ICAM-1 participates in the migration of leukocytes out of the blood in response to pulmonary inflammation, whereas alveolar macrophage ICAM-1 may represent cell activation. Our previous studies have shown that there is increased expression of ICAM-1 in lung tissue during acute inflammation following intratracheal injection with silica particles (2 mg/mouse). This increased expression was shown to play a role, in part, in the migration of neutrophils from the circulation into the tissue parenchyma. The aim of the current work is to localize expression of ICAM-1 during acute inflammation in lungs of mice exposed to either silica or the nuisance dust, titanium dioxide. In silica-exposed mice, a significant increase in ICAM-1 was detected on day-1 and localized by immunohistochemistry to aggregates of pulmonary macrophages and to type II epithelial cells. Areas of the lung with increased ICAM-1 expression also showed increased tumor necrosis factor alpha expression. Immunocytochemical staining of bronchoalveolar lavage (BAL) cells demonstrated increased ICAM-1 expression associated with alveolar macrophages 3, 5, and 7 days following silica exposure. Finally, soluble ICAM-1 levels in the BAL fluid were significantly increased in mice exposed to silica on the same days. Titanium dioxide exposure elicited a minimal increase in expression of ICAM-1 in the lungs. These data demonstrate that exposure to the toxic particle silica specifically increases ICAM-1 expression localized to pulmonary macrophages and type II epithelial cells.
authors.affiliation: Department of Pharmaceutical Sciences, School of Pharmacy, University of Connecticut, Storrs 06269, USA.
authors.forename: R C
authors.initials: RC
authors.lastname: Nario
authors.forename: A K
authors.initials: AK
authors.lastname: Hubbard
mesh_terms: D000818:Animals; D001992:Bronchoalveolar Lavage Fluid; D004391:Dust / Q000009:adverse effects; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D007150:Immunohistochemistry; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism*; D008168:Lung / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D014176:Protein Biosynthesis; D012822:Silicon Dioxide / Q000633:toxicity*; D014025:Titanium / Q000009:adverse effects
chemical_list: D004391:Dust; D018799:Intercellular Adhesion Molecule-1; C009495:titanium dioxide; D012822:Silicon Dioxide; D014025:Titanium