Reducing Effect of Angiotensin-1 Converting Enzyme Inhibitor (Captopril) in Fibrosis of Radiation Induced Lung Injury

ABSTRACT

BACKGROUND: The captopril reduces radiation induced lung injury and fibrosis. We designed a study to evaluate the antifibrogenic effect of Captopril in radiation induced lung injury. METHODS: Fifty Sprague-Dawley rats were divided into radiation group (I) (n=30) and radiation plus captopril group (II) (n=15). The rats were sacrificed at 12 hours and 11 weeks after radiation. We examined light microscopic, immunohistochemical and electron microscopic features in each groups. RESULTS: In Group I, the lungs showed acute lung injury at 12 h. The lungs showed patchy fibrosis with collagen deposits at 11 weeks. The severity of the alveolar injury and fibrosis was correlated with radiation doses. The Group II showed less severe lung fibrosis than Group I. The mean numbers of mast cells and myofibroblasts of Group II were lower than Group I (p< 0.05). The TNF-alpha and TGF-beta were higher expressed according to radiation doses in Group I, and less prominent in Group II. Ultrastructurally, the alveolar cell injury and fibrosis were less severe in Group II. The TUNEL stains showed higher expressions according to radiation doses in Group I, and expressed in Group II. CONCLUSIONS: The captopril decreases the number of mast cells and myofibroblasts, reduces collagen deposition and apoptosis of alveolar cells in rat lungs after radiation, and so reduces the degree of pulmonary injury and fibrosis.