The whole thorax of C57BL/6 female mice was irradiated to a single absorbed dose of 15 Gy. The formation of radiation-induced pulmonary fibrosis (RIPF) was assessed by lung index, Masson staining, Ashcroft score, and collagen synthesis for 20 weeks after irradiation. TGF-β 1 was measured by enzyme-linked immunosorbnent assay (ELISA), and the major proteins in TGF-β 1/Smad-dependent pathway, including TGF-β, Tβ R, phosphor-Smad 2/3, and Smad 7, were detected by immunohistochemistry staining. The results showed that RIPF formation was significantly reduced when CpG-ODN was administered to mice irradiated. Expression of TGF- β 1, a profibrotic cytokine, remained at a lower level. In TGF-β 1-Smad-dependent pathways, TGF-β 1, Tβ R, and phosphor-Smad 2/3 were downregulated, while Smad 7 was upregulated. This suggested that CpG-ODN prevented RIPF. The mechanism might be associated with a reduction of profibrogenic cytokine TGF-β 1 and inhibition of the fibrosis-related downstream TGF-β 1-Smad- dependent pathway.%使用单次全肺照射至吸收剂量15 Gy的C57BL/6雌性小鼠建立放射性肺纤维化模型,连续20周观察照射小鼠的基本情况和大体肺组织变化,制作肺组织Masson染色切片,并进行Ashcroft纤维化评分和纤维化面积定量,采用酶联免疫吸附测定法(ELISA)测定细胞因子 TGF-β 1的表达水平,免疫组化法检测肺组织内TGF-β 1、Tβ R、磷酸化Smad 2/3和Smad 7蛋白的表达.实验结果显示,照射后给予CpG-ODN处理,能使小鼠肺组织损伤及纤维化程度减轻,Ashcroft 评级降低2分,纤维化面积减少约11%,促纤维化细胞因子TGF-β 1表达水平下降近1/2,肺组织内的TGF-β 1、Tβ R和磷酸化Smad 2/3蛋白的表达皆出现不同程度降低, Smad 7蛋白的表达升高.这些结果提示 CpG-ODN 能通过降低促纤维化细胞因子 TGF-β 1的表达水平抑制TGF-β 1/Smad依赖性纤维化信号通路,从而减轻放射性肺纤维.
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