The Effect Of Thalidomide On The Expression Of FIZZ1 In Experimental Sillicosis Of The Rats

Objective To observe the dynamic changes of Found in Inflammatory Zone 1(FIZZ1) expression in the sillicosis of rats , discuss the function of the FIZZ1 to the sillicosis and investigate the effect of thalidomide on the expression of FIZZ1 in experimental sillicosis of the rats .Methods Fifty four Sprague-Dawley rats were randomly divided into three groups (the empty group, the silicosis group and the thalidomide group), each group has 18 rats. The silicosis group and the thalidomide group were injected with silic dust suspension (100mg·kg-1) endotracheally, while the empty group were injected with normal saline instead in the same condition. From the second day the thalidomide group were fed with thalidomide(100mg·kg-1) which was mixed into normal diet, while the other two groups with normal diet instead. We killed 6 rats randomly on day 7, 30, 60 after silic dust suspension or normal saline injection. Then the following tests were undertaken: (1)HE staining of lung section; (2)Determination of lung tissue hydroxyproline(HYP); (3)Immunohistochemical staining of protein of FIZZ1 in the lung; (4)Real-time PCR of FIZZ1 mRNA of the lung tissue. We observed the dynamic changes of FIZZ1 protein and mRNA expression in the lung and the connection of FIZZ1 and sillicosis on different stages.Results (1)Hydroxyproline concentration assay: The hydroxyproline concentration, which had not obviously increased at each time point on the day 7, 30, 60 in the normal lung tissue, was begin to rise from the the 7th day in the silicosis group. The hydroxyproline concentration of silicosis group obviously rised on day 30 and reached the climax on day 60. The change of hydroxyproline concentration in the thalidomide group was consistent with that in the silicosis group, while the hydroxyproline concentration was inferior in thalidomide group compared with that in silicosis group, but still higher than empty group. (2) HE staining: The empty group has not seen obvious pathological change. Each period of silicosis group had the changes of alveolus inflammation, such as infiltration of inflammatory cells in the alveolar space, the edema of the interstitium and the increase of angiogenesis. On day 7, changes described above were the most obvious. On day 30, We could see these changes: inflammation cells such as alveolus macrophages and lymphocytes decreased, fibroblast obviously increased in the interval of alveolus, the ground substance increased widely, the alveolus structure was destroyed and silicotic nodule of gradeⅡcould be seen. On day 60, the alveolus structure was further destroyed. We could see extensive fibrosis of normal structure and isolating or merging silicotic nodule which was gradeⅢappearance. HE staining proved that the rat model of silicosis was successfully established by intratracheal infusion of silic dust suspension. The change of pathology in the thalidomide group was the same with that in the silicosis group, but the extent of alveolus inflammation and pulmonary fibrosis was smaller than that in the silicosis group. (3) Immunohistochemistry: Immunohistochemical staining showed that in the empty group, the expression of FIZZ1 was low in alveolar epithelium cells, bronchiole epithelium, macrophages and endothelial cells of the pulmonary vessels. While the expression of FIZZ1 protein in the lung increased obviously on the day 7 in sillicosis animals. But it was decreased on the day 30 and further decreased on the day 60, which was still higher than the empty group. In the thalidomide group, the expression of FIZZ1 protein was higher than that in the empty group on day 7, 30 and 60, but was lower than that in the silicosis group, especially on day 7 and not obviously on day 60. (4) Real-time PCR: There was expression of FIZZ1 mRNA in each group, but it was weaker in the empty group of lung. The expression of FIZZ1 mRNA in the silicosis group was increased on the day 7, but was slightly decreased on the day 30 and expensively decreased on the day 60, which was higher than the empty group. In the thalidomide group, the expression of FIZZ1 mRNA was higher than that in the empty group on day 7, 30 and 60, but it was lower than that in the silicosis group, especially on day 7, but not obviously changed on day 60. Real-time PCR showed the same result as the immunohistochemistry.Conclusion FIZZ1 protein and mRNA were changed dynamically in the process of sillicosis, especially in the early stage when the FIZZ1 expressed strongly higher. Thalidomide can decrease the collagen level and the abnormal expression of FIZZ1 in the silicosis tissue, and inhibit the process of experimental silicosis.