结缔组织生长因子介导转化生长因子-β在石英粉尘致肺纤维化中的作用

The mechanisms of quartz-induced lung fibrosis were explored in many studies; however, 1) few studies learned how lung fibrosis was developed following the innate immune induced by quartz; 2) few biomarkers were found to be used as the therapeutic target for early-stage lung fibrosis; and 3) the reason why fibrosis can be developed at different sites in the lung is unclear. This study is proposed to use western blot, RT-PCR, immunohistochemistry, and ELISA, etc. to learn the dose- and time-effect relationship between quartz exposure and connective tissue growth factor (CTGF) level, and learn the role of transformed growth factor-β (TGF-β)/CTGF in the collagen secretion in fibroblasts. Rats that exposed to quartz with different dose and time will be used to explore the relationship of the exposure mode associated with CTGF level and secretion site, as well as the association between the fibrosis degree and site. Anti-CTGF will be applied to quartz-exposed rats before and after lung fibrosis, in order to evaluate its control and reversal to quartz-induced lung fibrosis. This will provide new clues for study on mechanisms of quartz-induced lung damage, and explore possible therapeutic targets for prevention and treatment of lung fibrosis.

石英粉尘致肺纤维化机制已有较多研究，但仍存在不足：1）对石英刺激引发固有免疫反应后如何形成肺纤维化的研究较少；2）缺少可作为治疗靶点的纤维化早期特征因子；3）纤维化可发生在肺组织的不同部位，但原因尚不清楚。本研究拟采用Western blot、RT-PCR、免疫组化和ELISA等方法分析石英诱导支气管上皮细胞产生结缔组织生长因子（CTGF）的作用条件和剂量、时间-效应关系，以及CTGF介导转化生长因子-β（TGF-β）在成纤维细胞分泌胶原中的作用；进一步对大鼠进行不同暴露模式的石英粉尘染毒，探究CTGF水平和分泌部位与暴露模式的关系，以及与肺组织纤维化程度和发生部位的关联性；通过在肺纤维化形成前后对染毒动物进行CTGF拮抗，与未拮抗的染毒动物对比，评价拮抗CTGF对石英粉尘致肺纤维化的控制与逆转作用，为石英粉尘损伤机体机制研究提供新线索，为防治肺纤维化寻找可能的药物作用靶点。

石英粉尘是我国目前最为严重的职业性有害因素之一，长期接触石英粉尘可导致以肺纤维化改变为主要特征的矽肺病。石英致肺纤维化的机制已有较多研究，但仍存在不足，包括：1）对石英粉尘刺激引发固有免疫反应后如何形成肺纤维化的研究较少；2）缺少可作为治疗靶点的纤维化早期特征因子；3）石英粉尘暴露引发的纤维化可发生在肺组织的不同部位，但原因尚不清楚。基于国内外研究进展和本课题组的前期工作基础，本项目采用Western blot、RT-PCR、ELISA、病理学分析等技术，通过体外染毒实验探讨CTGF在石英粉尘致人支气管上皮细胞损伤中的作用，构建大鼠肺纤维化模型分析不同模式石英粉尘暴露对肺炎性反应和纤维化水平的影响，评价抑制CTGF对控制和逆转石英粉尘致肺纤维化的效果。研究结果显示，石英粉尘染毒总量相同时，单次染毒与多次染毒模式均可导致肺部纤维化，但多次暴露所致纤维化水平更高；TGF-β和CTGF表达水平升高是石英粉尘暴露致纤维化中的重要过程，抑制TGF-β和CTGF均可降低石英粉尘所致纤维化水平；在肺纤维化形成早期抑制CTGF，可在一定程度上控制并减轻后续肺纤维化的程度。以上结果提示，CTGF介导TGF-β在石英致肺纤维化过程中具有重要作用，CTGF有望成为矽肺等肺纤维化相关疾病的干预和治疗靶点，本项目研究结果为石英粉尘的致病机制研究提供了新线索，为石英粉尘所致肺纤维化相关疾病的预防和治疗提供了思路。