Elastolytic activity and alveolar epithelial type-1 cell damage after chronic LPS inhalation: Effects of dexamethasone and rolipram
- Division of Pharmacology, Welsh School of Pharmacy, Cardiff University, King Edward VII Avenue, Cathays Park, Cardiff, CF10 3XF (United Kingdom)
- Physiology Department, School of Biosciences, Cardiff University, King Edward VII Avenue, Cathays Park, Cardiff, CF10 3XF (United Kingdom)
This study investigated whether a correlation between leukocyte-derived elastolytic activity, alveolar epithelial type-1 cell damage, and leukocyte infiltration of the airways existed in guinea-pigs chronically exposed to inhaled lipopolysaccharide (LPS). The airway pathology of this model, notably the neutrophilia, resembles chronic obstructive pulmonary disease (COPD). The effect of the corticosteroid, dexamethasone, or the phosphodiesterase-4 (PDE4)-inhibitor, rolipram, on these features was studied. Conscious guinea-pigs were exposed for 1 h to single or repeated (nine) doses of LPS (30 {mu}g ml{sup -1}). Dexamethasone (20 mg kg{sup -1}, ip) or rolipram (1 mg kg{sup -1}, ip) was administered 24 and 0.5 h before the first exposure and daily thereafter. Bronchoalveolar lavage fluid (BALF) was removed and elastolytic activity determined as the elastase-like release of Congo Red from impregnated elastin. The presence of the specific epithelial cell type-1 protein (40-42 kDa) RT1{sub 40} in BALF was identified by Western blotting using a rat monoclonal antibody and semi-quantified by dot-blot analysis. The antibody was found to identify guinea-pig RT1{sub 40}. BALF inflammatory cells, particularly neutrophils and macrophages, and elastolytic activity were increased in chronic LPS-exposed guinea-pigs, the latter by 90%. Chronic LPS exposure also increased (10.5-fold) RT1{sub 40} levels, indicating significant alveolar epithelial type-1 cell damage. Dexamethasone or rolipram treatment reduced the influx of inflammatory cells, the elastolytic activity (by 40% and 38%, respectively), and RT1{sub 40} levels (by 50% and 57%, respectively). In conclusion, chronic LPS-exposed guinea-pigs, like COPD, exhibit elastolytic lung damage. This was prevented by a PDE4 inhibitor and supports their development for suppressing this leukocyte-mediated pathology.
- OSTI ID:
- 20721998
- Journal Information:
- Toxicology and Applied Pharmacology, Vol. 207, Issue 3; Other Information: DOI: 10.1016/j.taap.2005.01.006; PII: S0041-008X(05)00017-7; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0041-008X
- Country of Publication:
- United States
- Language:
- English
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