[The effects of surfactant-TA on bleomycin-induced lung injury and lung fibroblast proliferation].

We investigated whether artificial surfactant modified pulmonary fibrosis following the intratracheal administration of bleomycin (BLM 3.75 mg/kg) in rats. Twenty-four hours after the administration of bleomycin, the lungs were washed twice with surfactant-TA (S-TA, 1 mg/ml, 6 ml x 2 times), and replaced with 0.5 ml of 10 mg/ml S-TA. Fourteen days later the animals were sacrificed and the lungs were assayed for collagen content and pathologic changes. BLM-treated rats showed both increases in wet lung weights and lung collagen content, and a loss in body weights (due to lung injury and fibrosis), but these changes were significantly inhibited by the intratracheal administration of S-TA. In vitro studies demonstrated that S-TA inhibited lung fibroblast proliferation in a dose dependent manner (0.01-0.5 mg/ml). This inhibition was also seen in native rat lung surfactant and its protein and lipid components. However, S-TA, did not change the number of rat type II pneumocutes in culture, and likely protected type II cells from dedifferentiation. S-TA inhibited BLM-induced pulmonary fibrosis, probably by directly inhibiting lung fibroblast proliferation.