title: Pathological study of chronic pulmonary toxicity induced by intratracheally instilled Asian sand dust (Kosa): possible association of fibrosis with the development of granulomatous lesions.
abstract: BACKGROUND
  Exposure to Asian sand dust (ASD) is associated with enhanced pulmonary morbidity and mortality, and the reporting of such cases has rapidly increased in East Asia since 2000. The purpose of the study was to assess chronic lung toxicity induced by ASD.
  
  
  METHODS
  A total of 174 ICR mice were randomly divided into 5 control and 17 exposure groups. Suspensions of low dose (0.2, 0.4 mg) and high dose (3.0 mg) of ASD particles in saline were intratracheally instilled into ICR mice, followed by sacrifice at 24 hours, 1 week, and 1, 2, 3 and 4 months after instillation. Paraffin sections of lung tissues were stained with hematoxylin and eosin and by immunohistochemistry to detect α-smooth muscle actin, collagen III, matrix metalloproteinase-9 (MMP-9), tissue inhibitor of metalloproteinases-1 (TIMP-1), CD3, CD20, immunoglobulin G, interleukin-1β and inducible nitric oxide synthase.
  
  
  RESULTS
  A lung histological examination revealed similar patterns in the lesions of the groups treated with high (3.0 mg) or low dose (0.4 mg) of ASD. Acute inflammation was observed 24 h after treatment and subsided after 1 week; persistent granulomatous changes were observed at 2 months, focal lymphocytic infiltration at 3 months, and granuloma formation at 4 months. An increase in the size of granulomatous lesions was observed over time and was accompanied by collagen deposition in the lesions. The cytoplasm of macrophages in inflammatory lesions showed positive immunolabeling for MMP-9 at 24 h, 1 and 2 months after instillation of 3.0 mg of ASD. Positive immunolabeling for TIMP-1 was demonstrated in the cytoplasm of macrophages at 2 and 4 months after instillation of 3.0 mg of ASD. These findings suggest association between the expression of MMP-9 and TIMP-1 with the development of lung granulomatous lesions.
  
  
  CONCLUSIONS
  These findings suggest that collagen deposition resulting from the altered regulation of extracellular matrix is associated with granuloma formation in the lungs of mice treated with ASD.
authors.affiliation: Laboratory of Pathology, School of Life and Environmental Science, Azabu University, Kanagawa, Japan. a-shimada@azabu-u.ac.jp.
authors.forename: Akinori
authors.initials: A
authors.lastname: Shimada
authors.forename: Yukari
authors.initials: Y
authors.lastname: Kohara
authors.forename: Misaki
authors.initials: M
authors.lastname: Naota
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Takehito
authors.initials: T
authors.lastname: Morita
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Inoue
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Takano
mesh_terms: D000818:Animals; D004391:Dust; D006099:Granuloma / Q000139:chemically induced; D007249:Inflammation / Q000139:chemically induced; D008168:Lung / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D051379:Mice; D008813:Mice, Inbred ICR; D011658:Pulmonary Fibrosis / Q000139:chemically induced* / Q000175:diagnosis / Q000473:pathology*; D012822:Silicon Dioxide / Q000633:toxicity*; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000378:metabolism; D014132:Trachea
chemical_list: D004391:Dust; C576839:TIMP1 protein, rat; D019715:Tissue Inhibitor of Metalloproteinase-1; D012822:Silicon Dioxide; D020780:Matrix Metalloproteinase 9
keywords: Asian sand dust; CD20; CD3; MMP-9; TIMP-1; chronic toxicity; granuloma; lung; macrophages