高迁移率族蛋白1在ANCA相关小血管炎发病机制中的作用

Antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) is characterized by pauci-immune necrotizing in?ammation of the small blood vessels. The pathogenesis of ANCA-associated vasculitides has not been fully understood. ANCA and neutrophil have been demonstrated to play a central role in the process of AAV. High mobility group box-1 (HMGB1) is an ancient nuclear protein. Later studies have demonstrated a novel role of HMGB1 as a kind of pro-inflammatory mediator when placed extracellularly.Our study has reported circulating HMGB1 levels were elevated in patients with active AAV.According to the previous results, we propose that this scientific hypothesis: HMGB1 played an important role in the pathogenesis of ANCA associated vasculitis, the role may be through the activation of neutrophils. The process may be completed by advanced glycation endproducts receptor (RAGE) and Toll-like receptor family (TLRs) and the intracellular signal transduction pathway may include MyD88, TIRAP and IRAK1.

抗中性粒细胞胞浆抗体（ANCA）相关小血管炎（AAV）的发病机制目前未明，ANCA和中性粒细胞起了重要作用。高迁移率族蛋白1（HMGB1）是一种重要的炎症介质和致炎细胞因子，许多研究提示HMGB1在AAV的发病中可能起重要作用。申请者前期研究发现AAV患者血清中HMGB1的浓度与疾病活动性密切相关，且中性粒细胞经HMGB1共孵育后，细胞膜表达ANCA靶抗原的水平增加，因此提出如下假设：HMGB1在ANCA相关小血管炎的发病过程发挥了重要作用，该作用可能是通过活化中性粒细胞、使中性粒细胞表面表达ANCA靶抗原增加、进而与ANCA反应、使中性粒细胞发生呼吸爆发和脱颗粒而实现的，该过程中可能是通过晚期糖基化终产物受体(RAGE)和Toll样受体家族(TLRs)部分成员完成，所经历的细胞内信号传导途径可能包括MyD88、TIRAP和IRAK1等。

本课题组通过检测 ANCA 相关小血管炎患者肾组织中和尿液中HMGB1 的水平，证实疾病活动患者的尿液中HMGB1的水平与疾病活动度相关，同时我们发现在病情活动患者的肾脏组织中，HMGB1主要在细胞浆和细胞间隙表达，而细胞核的HMGB1表达较健康对照者明显下降。我们将疾病活动患者血清中的ANCA-IgG分别刺激经HMGB1处理的中性粒细胞及未经处理的中性粒细胞，结果证实HMGB1能预激活中性粒细胞，使其表达更多ANCA的靶抗原，继而用ANCA刺激，中性粒细胞可发生呼吸爆发和脱颗粒的改变。应用相关受体阻滞剂及动物模型研究HMGB1使中性粒细胞发生上述反应的受体，应用信号转导因子阻滞剂探索 HMGB1 使中性粒细胞发生上述反应的细胞内信号转导途径证实TLR4/MyD88/NF-κB和RAGE/MyD88/NF-κB途径是HMGB1使中性粒细胞发生活化的细胞内信号转导途径。实验证实经HMGB1刺激中性粒细胞及肾小球内皮细胞后，可以观察到血浆HMGB1的水平与可溶性细胞间黏附分子-1和血管内皮生长因子呈现明显相关性。HMGB1增加了中性粒细胞向肾小球内皮细胞的迁移，同时在ANCA的介导下，也促进了中性粒细胞脱颗粒和呼吸爆发。