Influence of colchicine on pulmonary silicotic fibrogenesis in rats

With an aim to evaluate the antifibrotic action of colchicine in experimental model of pulmonary silicosis, the effect of colchicine on developing and developed pulmonary silicosis induced by quartz was studied in rats in vivo and on alveolar macrophages exposed to quartz particulates in vitro. A progressive increase in wet and dry weight of lungs exposed to quartz dust alone, and quartz dust and colchicine injected orally was investigated. An increase in collagen contents, with lapse in time, in animals exposed intratracheally to quartz dust, or exposed similarly to quartz dust but receiving colchicine simultaneously through oral route was observed. A blindfold evaluation of histological sections of lungs of silicotic animals with or without colchicine administration during development of lesions did not reveal any difference between two groups of silicotic rats. Administration of colchicine for 4 weeks after the lesions were developed neither inhibited nor retarded the laying down of collagen. The studies were extended to investigate the effect of colchicine on quartz-induced alveolar macrophage cytotoxicity. The presence of varying concentrations of colchicine in the culture medium did not significantly alter cytotoxic potential of quartz. The results reveal that colchicine administration during the development of and on developed silicosis does not significantly alter pathogenesis of silicotic lesions. At the cellular level colchicine does not modulate quartz-induced alveolar macrophage cytotoxicity, believed to be a significant event for the onset of pulmonary silicotic fibrogenesis.