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IDENTIFICATION OF SPONTANEOUS FELINE IDIOPATHIC PULMONARY FIBROSIS: MORPHOLOGY AND ULTRASTRUCTURAL EVIDENCE FOR A TYPE II PNEUMOCYTE DEFECT
Citation:
Williams, K. J., D. Malarkey, L. A. Cohn, D. J. Patrick, J A. Dye, AND G. B. Toews. IDENTIFICATION OF SPONTANEOUS FELINE IDIOPATHIC PULMONARY FIBROSIS: MORPHOLOGY AND ULTRASTRUCTURAL EVIDENCE FOR A TYPE II PNEUMOCYTE DEFECT. CHEST 125:2278-2288, (2004).
Description:
Abstract
Idiopathic pulmonary fibrosis currently lacks an animal model that develops the persistent, progressive lung fibrosis characteristic of the disease. Sixteen domestic cats developed dyspnea that was not responsive to therapy and which rapidly progressed until death/euthanasia. The pathology findings were consistent with usual interstitial pneumonia. Gross findings consisted of discrete, often subpleural, regions of fibrosis, and rare honeycombing. Histopathogically, the remodeling was heterogeneous, with 3 features present in all cats: 1) interstitial fibrosis with fibroblast/myofibroblast foci, 2) honeycombing with alveolar epithelial metaplasia, and 3) alveolar interstitial smooth muscle metaplasia. Interstitial inflammation was not a prominent feature of the disease; the infiltrates were primarily in areas of mature fibrosis and honeycombing. The -smooth muscle actin positive myofibroblasts were prominent in myofibroblast foci, beneath the honeycomb epithelium, and in alveolar septa away from the chronic remodeling where their presence coincides with increased extracellular matrix deposition. Other findings similar to the human disease were increases in mast cells in the fibrotic lung, and coincident primary lung neoplasia. This study shows that the domestic cat develops chronic respiratory disease that is clinically and pathologically similar to IPF in humans and that this may be a valuable model to study the disease in people.