MBD2通过影响巨噬细胞活化参与特发性肺纤维化发病机制的研究

Recent studies show that DNA methylation is involved in the pathogenesis of idiopathic pulmonary fibrosis (IPF). Methyl-CpG-binding domain protein 2 (MBD2) plays an important role in DNA methylation, but its role in IPF has not been reported. In the preliminary experiment, we found that the expression of Mbd2 in the lung tissue of pulmonary fibrosis was significantly increased. Furthermore, deficiency of Mbd2 attenuated the activation of macrophages. Moreover, Mbd2 deficiency protected mice against Bleomycin-induced lung injury and fibrosis. Based on above results, firstly, we plan to investigate the effects of MBD2 in the pathogenesis of IPF by observing the relationship between MBD2 expression and the clinical symptoms of IPF patients. Secondly, experiments will be carried out in vivo and in vitro on the Mbd2 knockout mice to clarify the effects of Mbd2 on macrophages activation and its mechanisms. The implementation of this study will further deepen our cognition of the pathogenesis of IPF and may find new potential treatment targets for IPF, which will have important values of science.

目前研究表明，DNA甲基化参与了特发性肺纤维化（IPF）的发病机制。甲基CpG结合域蛋白2（Methyl-CpG-binding domain protein 2，MBD2）是DNA甲基化过程中的重要调控分子，但其在IPF中的作用尚不明确。申请人通过预实验发现，Mbd2在小鼠肺纤维化模型的肺组织中表达明显增加，而Mbd2敲除可降低巨噬细胞的活化；与野生型小鼠相比，Mbd2敲除小鼠肺纤维化模型的肺损伤和纤维化均显著减轻。基于以上实验结果，本项目拟通过研究IPF患者肺组织中MBD2的表达与IPF患者临床指标的相关性，探讨MBD2在IPF发病机制中的作用；并进一步以Mbd2敲除小鼠为研究工具，通过动物模型与细胞干预实验，阐明Mbd2对于巨噬细胞活化的影响及其机制以及由此对肺纤维化产生的影响。本研究的实施将进一步深化对IPF发病机制的认识，并可能为IPF的治疗发现新的干预靶点，具有重要的科学意义。

既往研究发现DNA甲基化参与特发性肺纤维化（IPF）的发病，但其作用方式及机制并不明确。本研究以甲基化CpG结合域(Methyl-CpG-binding domain, MBD)蛋白2为切入点，深入揭示DNA甲基化参与IPF发病的作用方式及机制。研究发现IPF患者的肺组织和支气管肺泡灌洗液中存在替代活化型巨噬细胞增多同时伴随着MBD2的表达增加，在博来霉素诱导肺纤维化模型中亦观察到相似的现象。巨噬细胞中Mbd2缺失可显著降低其替代活化，减少TGF-β1产生，降低成纤维细胞的分化，缓解小鼠肺纤维化。机制研究发现IL-4诱导Ship基因启动子区的甲基化显著升高，Mbd2结合于Ship基因启动子区甲基化区域，抑制Ship的表达，继而增强了PI3K/AKT信号通路的活化，促进巨噬细胞替代活化。基于此我们应用RNAi疗法，将Mbd2 siRNA与纳米材料相结合制备Mbd2 siRNA 脂质体，通过气道注射Mbd2 siRNA 脂质体可治疗博来霉素诱导的小鼠肺纤维化。综上所述，本研究发现了MBD2介导IPF的病理机制，深化了表观遗传调控IPF发病的认知，同时创新了治疗策略，将RNAi疗法引入到肺纤维化的治疗中，不仅明确了其临床转化的可行性，还为后续蛋白靶点的干预研究奠定了基础。