抗MDA5抗体介导的NK细胞功能缺陷在肌炎合并急进型间质性肺疾病中的作用及机制研究

抗MDA5抗体肌炎合并急进型间质性肺疾病（RP-ILD）患者的死亡率高达50%。研究证实巨噬细胞活化在抗MDA5抗体肌炎合并RP-ILD中发挥重要作用。申请人的前期表达谱芯片结果提示抗MDA5抗体肌炎合并RP-ILD可能与病毒感染、NK细胞功能缺陷有关。本项目提出如下假说：抗MDA5抗体肌炎患者单核/巨噬细胞通过抗MDA5抗体介导的抗体依赖性细胞毒性（ADCC）和抗体依赖性细胞吞噬作用（ADCP）导致NK细胞功能缺陷，引起巨噬细胞过度活化。本研究拟在体外采用poly（I：C）模拟RNA病毒感染，探讨抗MDA5抗体是否参与单核细胞对NK细胞的ADCC和ADCP作用；进一步表达和纯化MDA5的C末端，皮下注射免疫小鼠，并从气管给予poly（I:C），检测肺组织巨噬细胞的浸润和活化情况以及脾脏NK细胞的功能，有望为阐明肌炎合并RP-ILD的发病机制提供新的研究方向，并为其治疗寻找新的靶点。

The mortality of myositis patients with anti-MDA5 antibody and rapidly progressive interstitial lung disease (RP-ILD) is as high as 50%. Many studies have confirmed that macrophage activation plays an important role in the anti-MDA5 antibody-positive myositis patients with RP-ILD. Our preliminary data suggests that the anti-MDA5 antibody-positive myositis complicated with RP-ILD may be related to viral infection and NK cell function impairment. This present study proposes the following hypothesis: monocytes/macrophages in patients with anti-MDA5 antibody-positive myositis cause NK cell dysfunction through anti-MDA5 antibody-mediated antibody-dependent cytotoxicity (ADCC) and antibody-dependent cell phagocytosis (ADCP), leading to excessive activation of macrophages. This study intends to use poly (I: C) to mimic RNA virus infection in vitro and investigate whether anti-MDA5 antibodies, CD16A and MDA5 are involved in the ADCC and ADCP effects of monocytes/ macrophages on NK cells. Furthermore, the purified MDA5 C-terminus protein was used to immunize mice subcutaneously and the intratracheal administration of poly (I: C) was performed to detect the infiltration and activation of macrophages in the lung and the function of splenic NK cells. Our study is expected to provide new research direction to clarify the pathogenesis of myositis with RP-ILD and find new targets for its treatment.