抗dsDNA IgG致病新机制—通过抑制SOCS1信号而诱导肾脏纤维化病变

Systemic lupus erythematosus is characterized by excessive production of pathogenic autoantibodies including anti-dsDNA antibodies, which induce specific injuries in kideneys. However, the precise mechanim underlying lupus nephritis remains unclear. Recently, we found that anti-dsDNA IgG exhibits high affinity to kinase inhibitory region (KIR) of suppressor of cytokine signaling 1 (SOCS1), a negative regulator of tissue fibrosis. The binding of anti-dsDNA IgG to KIR leads to the production of profibrotic cytokines in cells. Moreover, we identified a peptide (abbreviated as ALW), which blocks the antigenic recognition of anti-dsDNA IgG with an efficiency of >80%. Therefore, we speculate that anti-dsDNA IgG penetrates renal resident cells, modulates gene expression or interferes signal transduction of SOCS1-KIR to JAK2, and then triggers myofibroblast phenotype of normal cells. Also, ALW peptide may effectively inhibit such pathogenic effect of anti-dsDNA IgG. In this study, our aim will be focused on revealing the role of anti-dsDNA IgG in aberrant signal transduction of SOCS1-KIR to JAK2. The main techniques include cell culture, chemical peptide modification, mass spectrometry, etc. Finally, modified ALW peptide will be administrated to MRL/lpr lupus-prone mice, followed by monitoring both therapeutic and side effect. The results from this study will not only elucidate a novel intrinsic mechanism underlying renal fibrotic progresses induced by anti-dsDNA IgG, but also contribute to the development of small-molecule peptide therapies for patients with SLE-related end-organ damage.

抗dsDNA抗体是系统性红斑狼疮主要致病抗体之一，与肾损害密切相关，但致病机制不清楚。我们最近发现抗dsDNA IgG特异性识别SOCS1（一种纤维化负向调控因子）的功能区域KIR结构，继而促进纤维化炎症因子合成；还发现一种ALW多肽能高效封闭（>80%）抗dsDNA IgG与抗原结合。因此提出假说：抗dsDNA抗体穿透进入肾脏固有细胞，直接调控基因表达或干扰SOCS1-KIR与JAK2结合，诱导肌成纤维细胞表型；利用ALW多肽可能阻断抗dsDNA IgG的致病效应。本课题拟借助细胞培养、多肽化学修饰、质谱分析等技术，阐明抗dsDNA IgG干扰胞内SOCS1-JAK2信号链的分子机制，并借助MRL/lpr狼疮小鼠模型探讨ALW多肽靶向性阻断抗dsDNA IgG的初步疗效。本研究将揭示抗dsDNA抗体诱导肾组织纤维化的一种致病新机制，还将奠定小分子多肽药物治疗红斑狼疮靶器官损害的理论基础。

项目背景：狼疮性肾炎是系统性红斑狼疮（SLE）患者最常见内脏并发症，高达30%狼疮性肾炎患者会出现肾功能障碍，最终形成以肾脏纤维化为特征的肾小球硬化改变，构成SLE患者的主要死亡原因之一。抗dsDNA IgG是SLE患者肾脏损害的重要致病抗体之一，参与肾脏纤维化过程；SOCS1是组织纤维化与细胞表型转化的重要信号途径，在狼疮性肾炎纤维化机制发挥重要介导作用。因此，阐明抗dsDNA IgG致病机制，将为治疗红斑狼疮特异性器官损害奠定基础。.主要研究内容：阐明抗dsDNA IgG穿透活细胞并与SOCS1结合作用，其与SOCS1-KIR结合对纤维化因子的影响；证实抗dsDNA IgG调控T细胞分化、巨噬细胞浸润的作用；采用化学修饰ALW多肽，分析其缓解抗dsDNA IgG的酶切效应；在SLE小鼠模型验证ALW多肽（药物前体）直接阻断抗dsDNA IgG致病作用。.重要结果：发现抗dsDNA IgG穿透肾脏固有细胞的分子机制，抗dsDNA IgG可以调控基因表达及激活HMGB1信号；阐明抗dsDNA IgG调控T细胞分化与巨噬细胞浸润的作用，揭示抗dsDNA IgG调控SOCS1功能的分子机制；对ALW多肽进行化学修饰，基本不改变ALW多肽的抗原性和水溶性特征，验证ALW多肽阻断体内抗dsDNA IgG致病作用的较好效果。.关键数据：迄今发表SCI论文6篇（标注资助）；在国际学术会议发言1次，在国内中文会议发言6次；授权中国发明专利1项；获得陕西高校科技成果奖一等奖1项；培养博士生3人、硕士生4人（毕业）、陕西省高层次人才特殊支持计划-科技创新领军人才1人。.科学意义：本项目从抗dsDNA IgG“调控纤维化相关基因表达（包括HMGB1信号途径）”和“交叉结合SOCS1-KIR多肽链”两个角度，阐明其诱导肾脏纤维化的分子机制。通过化学修饰ALW多肽，可以维持其抗原结构特征和高水溶性特征，同时规避被自身抗体酶切的缺陷，证实该多肽高效阻断抗dsDNA IgG的致病效应，为SLE的靶向治疗奠定理论基础。