[The roles of TSP-1 and its receptor CD47 in pathogenesis of paraquat-induced pulmonary fibrosis in rats].

To establish a rat model of paraquat (PQ) -induced pulmonary fibrosis and observe the changes in thrombospondin-1 (TSP-1) and its receptor CD47 in lung tissue, and to investigate their roles in the pathogenesis of PQ-induced pulmonary fibrosis. Fifty-four clean adult male Sprague-Dawley rats were randomly divided into normal control group (=6) and 2 h, 12 h, 1 d, 3 d, 7 d, and 14 d PQ poisoning groups (=8 per group). A rat model of PQ poisoning was established by a single gavage of 20 wt.% PQ solution (50 mg/kg). Flow cytometry was used to determine the concentration of reactive oxygen species (ROS) in blood and lung tissue. Enzyme-linked immunosorbent assay was used to determine the concentrations of hydroxyl radicals, malondialdehyde, and hydroxyproline in lung tissue. HE staining and Masson staining were used to observe the pathological damage of lung tissue after PQ poisoning. The expression of TSP-1 and CD47 in lung tissue was measured by Immunohistochemistry. Compared with the normal control group, the 2 h to 7 d PQ poisoning groups showed significant increases in ROS fluorescence intensity in red blood cells and lung tissues and the concentrations of malondialdehyde and hydroxyl radicals in lung tissue (<0.05) , and the 14 d PQ poisoning group had a significant increase in the concentration of hydroxyproline in lung tissue (<0.05). HE staining showed that the 2 h to 7 d PQ poisoning groups had significantly higher semiquantitative pathological scores of pulmonary alveolitis than the normal control group (<0.05). The Masson staining showed that the 7 d and 14 d PQ poisoning groups had significantly higher semiquantitative pathological scores of pulmonary fibrosis than the normal control group (<0.05). Compared with the normal control group, all PQ poisoning groups (except the 12 h group) had significantly increased expression of TSP-1 in lung tissue (<0.05) , and all PQ poisoning groups (except the 1 d group) had significantly increased expression of CD47 in lung tissue (<0.05). Within 2 h after PQ poisoning, the expression of TSP-1 and CD47 was positively correlated with the concentrations of ROS, hydroxyl radicals, and malondialdehyde and the degree of pulmonary alveolitis (<0.01) ; at 1 d after PQ poisoning, the expression of TSP-1 and CD47 was positively correlated with the concentration of hydroxyproline in lung tissue (<0.01) . The expression of TSP-1 and CD47 is closely related to oxidative stress and subsequent pulmonary fibrosis, and they may be involved in the development and progression of pulmonary alveolitis and subsequent pulmonary fibrosis in rats with PQ poisoning.