Investigation Of Soluble TNF-α Receptor To Silica Induced Pulmonary Fibrosis In Rats

Objective: This study was designed to calculate 5 kind of biological activity medium in the blood serum of rats exposed to silica, and speculate the key profibrotic points. Primarily investigate the preventive and therapeutic effect of soluble TNF-αreceptor and the expression of other cytokinesMethod: Wistar rats were randomly divided into three experimental groups: control group(n=48), silica group(n=48), and intervention group(n=20). silica-instilled groups were received lightly anesthetized with pentobarbital and received a single intratracheal instillation of silicon suspension of 1ml at the concentration of 50mg/ml. The control group was treated in the same way but injection of 1 ml sterilized saline instead. Rats in drug-treated groups were given soluble TNF-αreceptor (500ug) in the 1, 5, 8 day after operation. At 1d, 3d, 7d, 14d, 21d, 28d after establishment of the animal model, eight rats in control and silica-instilled group were sacrificed. At 7d, 14d after establishment of the animal model, five rats in intervention group were sacrificed. The changes of lung histomorphology of rats were observed by HE staining of histological section. Total cell count and differential cell counts in bronchoalveolar lavage fluid (BALF) were estimated by cytometer. Sirius red polarization microscopy detectsⅠandⅢcollagen. The NO activity was also assayed by spectrophotometer, using the kits purchased from Nanjing Jiancheng Bioengineering Institute. The expression of NF-κB, TGF-β1, IL-1β, TNF-αwas assayed by ELISA kit.Result: 1 Histochemistry (HE staining) proved that the rat model of silicosis was successfully established by intratracheal infusion of silica dust suspension.2 Exposure to silica can increased the coefficient of organ to body of rats at each time point, and at 7d, 14d, 21d, 28d this difference was significant(P<0.05). soluble TNF-αreceptor can ameliorated the silica-induced increase in the coefficient of organ to body of rats, this difference was significant at 7d, 14d (P<0.05).3 Effect of soluble TNF-αreceptor on total white cell count in bronchoalveolar lavage fluid(BALF) of silica-treated rats. Compared with that of control group, total white cell count in BALF of silica goup, silica group at every time points increased, this difference was significant at 14d, 21d, 28d (P<0.01). Compared with that of silica group, total white cell count in BALF of Intervention group at 14d decreased significantly (P<0.05).4 Effect of soluble TNF-αreceptor on synthesis ofⅠⅢcollogen of silica-treated rats. In comparison to control group,Ⅰcollagen positive area percent of lung in silica-induced group exhibited a sustained significant increase at 7d, 14d, 21d, 28d (P<0.01) , but the increase ofⅢcollagen positive area percent of lung in silica-induced groups began to be small at 21d, this increase was just significant at 7d, 14d, 21d (P<0.01). ForⅠcollagen, such increases were reduced significantly by TNF-αmonoclonal antibody treatment at 14d (P<0.05), and forⅢcollagen significant at 14d too (P<0.05).5 Effect of soluble TNF-αreceptor on NO content in circumference blood serum of rats exposed to silica. Compared to the control, a relatively increase in the NO content in the serum was observed from silica-exposed rats, this increase was significant at 7d, 14d, 21d, 28d (P<0.05). soluble TNF-αreceptor treatment had obvious effect on the silica-induced increase in this parameter, this reduction was significant at 14d (P<0.05) .6 Effect of soluble TNF-αreceptor on IL-1βprotein expression in circumference blood serum of rats exposed to silica. Compared to the control, a relatively smaller increase in the IL-1βcontent in the serum was observed from silica-exposed rats, this increase was just significant at 3d, 7d (P<0.05) . soluble TNF-αreceptor treatment had marked effect on the silica-induced increase in this parameter, this reduction was significant at 7d (P<0.05) .7 Effect of soluble TNF-αreceptor on TGF-β1 protein expression in circumference blood serum of rats exposed to silica. In comparison to the control, there was a significant increase in TGF-β1 content in the serum from silica-exposed group rats at 14d, 21d, 28d (P<0.01, P<0.05), and the highest level of TGF-β1 was found at 21d. Compared with that of silica group, the level of TGF-β1 was significantly decreased at 14d by treatment of soluble TNF-αreceptor.8 Effect of soluble TNF-αreceptor on NF-κB protein expression in circumference blood serum of rats exposed to silica. Compared to the control, the level of NF-κB increased significantly at at all time points(P<0.01, P<0.05). and it peaked at 3d after rats exposed to silica. such increases were reduced significantly by treatment of soluble TNF-αreceptor at 7d, 14d (P<0.05).9 Effect of soluble TNF-αreceptor on TNF-αprotein expression in Circumference blood serum of rats exposed to silica. No significant differences were found in serum levels of TNF-αbetween rats received different treatment.Conclusion: 1 The bronch of the rat instilled silica dust suspension can cause phlegmonosis and fibrosis pathological change in the lung tissues of the rat and form silicotic nodule. 2 soluble TNF-αreceptor can ameliorated the silica-induced increase in the coefficient of organ to body of rats. 3 The increases of the numbers of total cells in BALF in silica-treated rats were significantly suppressed by soluble TNF-αreceptor. 4 The formation ofⅠandⅢcollagen in lung tissues in silica-treated rats can be suppressed by soluble TNF-αreceptor. 5 soluble TNF-αreceptor may plays roles of anti-fiborosis through intervention the key cytokine such as TNF-α,NF-κB,TGF-β1,IL-1βin cytokine network in silicotic process.