聚合梳蛋白EZH2介导的miR-let-7c表观遗传抑制通过PAK1激酶信号调控巨噬细胞分化的分子机制和功能意义研究

Systemic lupus erythematosus (SLE) is a complex, multiple organs involved, potentially fatal disease and also the prototype of other autoimmune disease. Kidney involvement (mainly glomerulonephritis) occurs in at least one third of patients with lupus and significantly affects survival due to the fact that repetitive bouts of inflammation in kidney lead to glomerular and interstitial fibrosis and tubular atrophy, and eventually to renal insufficiency. Our previous study demonstrated that macrophage inflammatory M2b differentiation and polarization conferred by activated lymphocyte-derived apoptotic (ALD)-DNA immunization could initiate and propagate murine lupus nephritis in the well-known lupus murine model established by immunizing female BALB/c mice with ALD-DNA (J Immunol 2010, J Immunol 2011, J Biol Chem 2013). However, the molecular mechanism and functional significance of macrophage phenotypic switch remains not fully understood. In the present study, our preliminary results showed that ALD-DNA induced p21-activated kinase 1(PAK1) overexpression in inflammatory polarized macrophages, which correlated with the clinical severity of SLE disease. Epigenetic loss of microRNA-let-7c (miR-let-7c) due to enhancer of zeste homolog 2 (EZH2) upregulation determined PAK1 elevation and signaling activation in the inflammatory M2b macrophages in lupus nephritis. Around the key scientific theme of epigenetic modifications influence on immune cell differentiation and its relationship with disease, our present research project will focus on the molecular mechanism and functional significance for the epigenetic control of macrophage differentiation and inflammatory polarization mediated by EZH2/miR-let-7c/PAK1 signaling in lupus nephritis, and will establish a working model of molecular regulation and therapeutic intervention of inflammatory macrophage polarization in lupus nephritis, which paves the way to clinical investigation and drug discovery based on molecular therapy targeting aberrant EZH2/ miR-let-7c/ PAK1 signal activation to alleviate lupus nephritis via blunting macrophage inflammatory polarization.

系统性红斑狼疮（SLE）是一种病因复杂、多器官受累、致死性自身免疫病和自身免疫病研究原型，狼疮性肾炎介导的肾功能衰竭是致死的主要原因。在自身凋亡DNA（ALD-DNA）诱导的常规遗传背景SLE小鼠中，我们发现巨噬细胞M2b型炎性极化在狼疮肾炎中发挥关键作用（J Immunol 2010、2011，J Biol Chem 2013），而其极化状态转换的机制及功能仍不清楚。我们预实验发现聚合梳蛋白EZH2介导的miR-let-7c表观遗传抑制调控狼疮肾炎中巨噬细胞PAK1信号，本项目拟围绕表观遗传修饰对免疫细胞分化的影响及其与疾病的关系这一关键科学问题，通过阐述EZH2/miR-let-7c/PAK1信号介导的巨噬细胞极化在狼疮肾炎中的作用及机制，建立巨噬细胞炎性极化参与狼疮肾炎发病的分子调控和干预治疗模型，为开发针对相应信号活化通过逆转巨噬细胞炎性极化缓解狼疮肾炎的分子靶向治疗药物奠定基础。

在本项目资助下，项目负责人围绕巨噬细胞生物学方向，深入研究在自身免疫病和肿瘤发生过程中异常巨噬细胞功能表型转化的分子机制及其功能意义，并取得一系列研究成果。以第一作者和通讯作者在European Urology、Gut、Annals of Oncology、Cell Death & Differentiation、JAMA Surgery、British Journal of Cancer、Oncoimmunology、Cancer Immunology Immunotherapy、Annals of Surgical Oncology、Cancer Science等免疫学领域国际权威期刊上发表10篇SCI论文，其中第一作者论文1篇，通讯作者论文9篇，影响因子10以上论文3篇。我们发现EZH2信号介导的microRNA let-7c分子表观沉默通过活化巨噬细胞内PAK1及其下游的NIK-IKK-NF-κB信号促进其炎性极化并参与狼疮肾炎发病过程的分子机制及重要作用，阐明肿瘤微环境中浸润IL-23阳性和CXCL8阳性等不同亚群肿瘤相关巨噬细胞以及IL-17阳性细胞在调控肾癌和胃癌患者抗肿瘤免疫反应和免疫逃逸形成过程中的关键作用及其细胞分子机制，这些研究发现为开发靶向异常巨噬细胞功能表型转化的免疫治疗奠定基础。