[A rat model of chronic bronchiolitis due to Pseudomonas aeruginosa--a histopathological study of bronchus-associated lymphoid tissue (BALT)].
To investigate the role of BALT in chronic respiratory infection, we established a rat model of chronic bronchiolitis caused by Pseudomonas aeruginosa, and the light microscopic findings of the BALT were studied. Experimental pneumonia was produced in SD rats by intratracheal inoculation of 10(6) colony forming units (cfu) of mucoid P. aeruginosa enmeshed in agar beads. The mean cfu recoverable from the lung increased up to 10(8) cfu at day 1. The number of bacteria remained fairly constant at 10(4) cfu until day 28. Histologically, infiltration of neutrophils could be seen around the agar beads containing P. aeruginosa in the lung from day 1 to day 7. From day 14 to day 28. the histological changes in the lungs were characterized by accumulation of foamy cells accompanied with lymphocyte infiltrations and granulation tissues around the respiratory bronchioles, but without involved alveoli. These chronic inflammatory histologic changes were similar to those of diffuse panbronchiolitis (DPB). At the same time, there were massive accumulation of lymphocytes in lymphatics and in high endothelial venules of the BALT at day 7. The development of germinal centers in the follicular area was found from day 7 to day 28. The airway was narrowed as a result of BALT hyperplasia protruding to the bronchial lumen. These results suggest that histological changes represent the model of chronic bronchiolitis and BALT may have a specific role in developing the local immune responses against chronic respiratory infection due to P. aeruginosa.
Iwata
M
M
Second Department of Internal Medicine, Hamamatsu University School of Medicine.
Sato
A
A
D000818:Animals; D001980:Bronchi / Q000473:pathology*; D001988:Bronchiolitis / Q000209:etiology / Q000276:immunology / Q000473:pathology*; D002908:Chronic Disease; D004195:Disease Models, Animal; D008221:Lymphoid Tissue / Q000276:immunology / Q000473:pathology*; D008297:Male; D011552:Pseudomonas Infections; D011550:Pseudomonas aeruginosa; D051381:Rats; D011919:Rats, Inbred Strains