补体H因子在抗中性粒细胞胞浆抗体相关小血管炎发病机制中的研究

Antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) is a multisystem immune-mediated disorder, and kidney involvement is one of the most serious complications of AAV. The pathogenesis of AAV has not been fully understood. Increasing evidences have demonstrated that activation of alternative complement pathway plays an important role in the pathogenesis of AAV. Complement factor H is a key regulator of the alternative complement pathway. In our previous studies we found that biofunction of complement factor H was impaired in AAV patients, which might contribute to disease development. However, the pathogenesis of complement factor H dysfunction was not clear. We presume that there is post-translation modification of complement factor H in AAV, resulting in complement factor H dysfunction which could promote AAV progression by contributing to alternative complement pathway activation and ANCA mediated neutrophils activation. Since activation of neutrophils also leads to alternative pathway complement activation by the releasing of properdin, then complement factor H dysfunction might result in alternative complement pathway activation by affecting the process of ANCA mediated neutrophils activation. Thus, in our current project, we plan to purify complement factor H of AAV patients, and try to detect post-translation modification in purified complement factor H. Then we will test the biofunction of modified complement factor H. The role of complement factor H in alternative complement pathway activation and ANCA mediated neutrophil activation will be explored through both the in vivo assay and animal models. The data will provide scientific clues for further elucidation of disease pathogenesis and targeted therapy.

抗中性粒细胞胞浆抗体（ANCA）相关小血管炎（AAV）是常见的自身免疫病，发病机制不清，补体旁路途径异常激活是其中的重要环节。H因子是补体旁路途径的关键负性调节蛋白，我们前期研究发现AAV中存在H因子功能缺陷，但其原因及在发病机制中的作用尚不明确。我们推测：AAV中H因子存在蛋白异常修饰导致其功能缺陷；H因子功能缺陷除导致补体旁路异常活化外，还可能通过影响ANCA介导的中性粒细胞活化继而导致补体旁路异常激活，从而参与疾病发生。本项目拟在前期工作的基础上：①研究AAV疾病状态下H因子异常修饰，及其对H因子生物学功能的影响。②通过细胞实验研究AAV患者H因子对ANCA介导中性粒细胞活化及其继发的补体旁路异常激活的影响。③在动物实验中应用H因子或其抗体进行干预，研究对疾病严重程度、补体活化水平、中性粒细胞活化水平等的影响。本项目将有助于阐明H因子异常在AAV发病机制中的作用，并探索潜在治疗靶点。

抗中性粒细胞胞浆抗体（ANCA）相关小血管炎（AAV）是常见的自身免疫病，发病机制不清，补体旁路途径异常激活是其中的重要环节。H因子是补体旁路途径的关键负性调节蛋白，我们前期研究发现AAV中存在H因子功能缺陷，但其原因及在发病机制中的作用尚不明确。我们推测：AAV中H因子存在蛋白异常修饰导致其功能缺陷；H因子功能缺陷除导致补体旁路异常活化外，还可能通过影响ANCA介导的中性粒细胞活化参与疾病发生。本在本研究中，我们证实了AAV疾病状态下存在H因子的异常修饰，在AAV患者来源的CFH中，我们检测到其功能区硝基化或卤化的酪氨酸残基。而健康对照组没有发现这种改变。另外一个导致H因子水平或功能异常的原因可能是其降解增多。我们应用AAV患者及健康对照血清进行了Western Blot，结果显示AAV患者中存在CFH异常降解片段，提示AAV中存在可与CFH结合并降解CFH的蛋白水解酶。而在H因子异常的下游效应方面，我们发现H因子缺陷影响ANCA介导的中性粒细胞活化及中性粒细胞和内皮细胞间的相互作用。在AAV动物模型造模稳定的基础上，疾病建立后药物干预的实验方式显示了潜在治疗药物的作用。以上结果进一步扩展了目前对AAV发病机制的理解，有望为该病未来的临床治疗提供新的方向。