PDGF/ROCK通路在AcSDKP抑制大鼠矽肺纤维化形成中的作用

目的:探讨血小板源性生长因子/Rho相关卷曲螺旋形成蛋白激酶(PDGF/ROCK)通路在肺纤维化发病机制中的作用以及N-乙酰基-丝氨酰-天门冬酰-赖氨酰-脯氨酸(AcSDKP)能否通过对PDGF/ROCK的调节而发挥抗矽肺纤维化作用。方法:采用非暴露式气管二氧化硅混悬液灌注法制备大鼠矽肺模型。60只SPF级健康成年Wistar 大鼠随机分为模型对照4周组、模型对照 8 周组、矽肺模型 4 周组、矽肺模型 8 周组、AcSDKP 治疗组和AcSDKP预防治疗组,每组10 只。免疫组织化学染色法检测各组大鼠肺组织中phospho-PDGFR-β的表达与分布,Western blotting法检测各组大鼠肺组织中α-平滑肌肌动蛋白(α-SMA)、PDGFR-β、phospho-PDGR-β、ROCK、Ⅰ型胶原和Ⅲ型胶原蛋白的表达。 结果:与相应模型对照组比较,矽肺模型组大鼠肺组织中α-SMA、PDGFR-β、phospho-PDGFR-β、ROCK以及Ⅰ型胶原和Ⅲ型胶原蛋白表达水平均明显升高(P<0.05);形态学检测可见较多的phospho-PDGFR-β阳性表达细胞分布在矽结节与间质纤维化区域。与矽肺模型4周组和模型8周组比较,AcSDKP 治疗组和预防治疗组大鼠肺组织中α-SMA、PDGF-β、phospho-PDGFR-β、ROCK、Ⅰ型胶原和Ⅲ型胶原蛋白表达水平均明显降低(P<0.05);免疫组织化学染色,phospho-PDGFR-β蛋白表达明显减少。 结论:PDGF介导的ROCK信号转导通路可能通过促进大鼠肌成纤维细胞转化而促进矽肺大鼠肺组织中的胶原合成,进而促进矽肺纤维化的形成。AcSDKP 可能通过PDGF/ROCK通路抑制矽肺大鼠肺内肌成纤维细胞的分化,减少其胶原的合成与分泌,进而发挥抗矽肺纤维化的作用。

Effect of PDGF-ROCK pathway in process of N-acetyl-seryl-aspartyl-lysyl-proline inhibiting development of pulmonary fibrosis in rats with silicosis

Objective To investigate whether N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP) can inhibit the development of silicosis through blocking PDGF/ROCK pathway. Methods SiO₂ were douched in bronchial tube of the rats to make the silicotic models.Sixty Wistar rats were randomly divided into model control 4 weeks group, model control 8 weeks group, silicosic model 4 weeks group, silicosic model 8 weeks group, AcSDKP post-treatment group and AcSDKP pre-treatment group (n=10).The expression and distribution of phospho-PDGFR-β in lung tissue of the rats in various groups were observed by immunocytochemistry.The expressions of α-smooth muscle actin (α-SMA), PDGFR-β, phospho-PDGFR-β, ROCK, Ⅰ collagen and Ⅲ collagen in lung tissue of the rats in various groups were detected by Western blotting method. Results Compared with the corresponding control groups, the expression levels of α-SMA, PDGFR-β, phospho-PDGFR-β, ROCK, type Ⅰcollagen and type Ⅲ collagen in lung tissue of the rats in silicosic model groups were increased significantly(P<0.05).In addition, in silicosic model groups, there were more phospho-PDGFR-β positive cells distributed in the silicon nodules and interstitial fibrosis area detected by immunocytochemistry.However, these effects were inhibited in AcSDKP post-treatment group and AcSDKP pre-treatment group (P<0.05).The Results of immunohistochemical staining showed the expression of phospho-PDGFR-β protein was obviously decreased in AcSDKP post-treatment group and AcSDKP pre-treatment group. Conclusion PDGF/ROCK pathway may play an important role in the development of silicosis by promoting myofibroblast differentiation and further secreting more collgen; however, these effects may be inhibited by AcSDKP.