[Study on lung injury induced by rare earth samarium oxide particles in rats]

Objective: To study the effect of samarium trioxide (Sm(2)O(3)) particles on rat lung tissue and compare it with the same dose of silica (SiO(2)) particles, in order to find the reference index for early screening of pneumoconiosis. Methods: In October 2018, 72 SPF healthy male rats were randomly divided into control group, SiO(2) group and Sm(2)O(3) group. The lungs of rats in each group were perfused with 2.0 ml/kg normal saline and 280 mg/kg SiO(2) and Sm(2)O(3) particle suspension by one-time non exposed tracheal perfusion. The lungs of rats were stained with hematoxylin eosin (HE) staining, and the pathological changes of lung tissues were observed. The concentrations of SNAIL homologue 1 (SNAI1) , SNAIL homologue 2 (SNAI2) , and heat shock protein-27 (HSP-27) in rat serum were detected by enzyme-linked immunosorbent assay. 0.5 g of lung tissue from rats in Sm(2)O(3) group and control group exposed to dust for 56 days was screened for long-chain noncoding RNA (lncRNA) and circular RNA (circRNA) . Results: After 7 days of dust exposure, the alveoli in SiO(2) group and Sm(2)O(3) group were disordered, and lymphoid tissue aggregation and proliferation were observed around the bronchial wall. At 14 days, a large number of lymphocytes infiltrated in SiO(2) group, and a small number of macrophages containing Sm(2)O(3) and fibrotic nodules scattered in Sm(2)O(3) group. At 28 days, a small amount of lymphocyte infiltration appeared in SiO(2) group, and fibrotic nodules were seen in some areas of Sm(2)O(3) group. At 56 days, there was a small amount of fibroblast proliferation in SiO(2) group, and a large number of fibrotic nodules containing gray black matter were seen in Sm(2)O(3) group. There was no significant difference in lung organ coefficient among groups at different dust exposure time (P>0.05) . After 14 days of dust exposure, the contents of SNAI1 and SNAI2 in serum of rats in SiO(2) group were lower than those in control group, the content of SNAI2 in serum of Sm(2)O(3) group was lower than that in control group, and the contents of SNAI1 and SNAI2 in serum of Sm(2)O(3) group were higher than those in SiO(2) group (P<0.05) . The content of HSP-27 in SiO(2) group was lower than that in control group (P<0.05) . After 56 days of dust exposure, the content of HSP-27 in Sm(2)O(3) group was lower than that in control group (P<0.05) . At 56 days, lncRNA in Sm(2)O(3) group was up-regulated by 148 and down regulated by 725, circRNA was up-regulated by 16 and down regulated by 153. Conclusion: Sm(2)O(3) can cause lung injury in rats, and the change of SNAI2 content can be detected in the early stage, which can be used as a reference index for early screening of pneumoconiosis. There are differences in the expression of lncRNA and circRNA after 56 days of dust exposure in rats, which may be related to the pathogenesis of pneumoconiosis.