【目的】在北京协和医院单中心抗黑色素瘤分化相关基因 5（melanoma differentiation -associated gene 5，MDA5）抗体相关间质性肺病住院回顾性队列的基础上探讨影响抗 MDA5 抗体相关快速进展型间质性肺病（rapidly progressive interstitial lung disease，R P-ILD）的危险因素。探究托珠单抗治疗对患者生存时间的影响。基础研究方面，通过单细胞转录组测序技术探讨抗MDA抗体相关RP-ILD患者的肺泡灌洗液和外周血单个核细胞的细胞组成以及细胞组成的患者间差异。探讨干扰素刺激基因在患者与健康对照间、在生存患者与死亡患者间的表达差异。通过高通量炎症因子检测，探讨肺泡灌洗液与外周血炎症因子间的差异以及表达这些差异炎症因子和受体的细胞亚群。【方法】临床研究方面，本研究通过单因素和多因素cox风险比例模型探究影响抗M DA5抗体相关间质性肺病患者生存的危险因素。通过倾向性评分匹配平衡托珠单抗治疗组和标准治疗组的组间差异，并绘制Kaplan-Meier生存曲线探究托珠单抗对抗MD A5抗体相关间质性肺病患者生存的影响。基础研究方面，通过单细胞转录组测序获得表达矩阵，经过主成分分析降维、去批次效应及校正聚类后寻找聚类细胞群体间的高异质性基因，并依据高异质性基因进行细胞亚群注释。寻找抗MDA5抗体阳性患者与健康对照间的差异基因，寻找死亡患者与存活患者间的差异基因，利用GO数据库和KEGG数据库进性基因功能富集分析。【结果】预后学研究部分，在杨露伟师兄的研究基础上共纳入了152例抗MDA5抗体相关间质性肺病患者，除外治疗前存在感染40例。单因素cox风险比例模型提示起 病年龄大、γ-谷氨酰转肽酶高、超敏C反应蛋白检测值高、最大激素剂量大以及病程中使用激素冲击治疗与预后差相关，多因素cox风险比例模型提示起病年龄是预后差的危险因素。托珠单抗疗效比较方面，使用倾向性评分匹配平衡两组间年龄，匹配后托珠单抗治疗组和标准治疗组各12人。Kaplan-Meier生存曲线提示托珠单抗治疗有延长生存时间的趋势，但未见统计学显著性。单细胞转录组学部分共注释了13群PBMC细胞和22群BALF细胞，外周血单个核细胞的组成在3名患者间具有较大的异质性，而BALF细胞的组成较为一致。功能富集分析发现，抗MDA5抗体相关RP-ILD患者的外周血单核细胞（CD14+CD16-）相较于健康对照，干扰素-γ相关通路显著上调。死亡患者BALF和PBMC的I型干扰素通路、抗病毒相关通路显著上调。【结论】本研究首次评价了托珠单抗对抗MDA5抗体相关RP-ILD的治疗效果，发现其有潜在延长患者生存的价值，值得扩大样本量进行后续研究，为抗MDA抗体相关RP-ILD的治疗提供了新的药物选择。此外，本研究是国内外首个抗MDA5相关RP-ILD的单细胞转录组学研究，描述了抗MDA5抗体相关RP-ILD患者肺部和外周血的免疫环境，发现了肺部局部炎症在疾病发生进展中的重要性。同时证实了I型干扰素通路在抗MDA5抗体相关RP-ILD中的重要性，且可能与患者的预后相关，在疾病机制的探索和治疗选择方面有重大价值。

【AIMS】To explore risk factors of anti-melanoma differentiation-associated gene 5 (MDA5) antibod y-associated rapidly progressive interstitial lung disease on the basis of the single-center ret rospective cohort from Peking Union Medical College Hospital. To study the efficacy of To cilizumab on the cumulative survival rate of anti-MDA5 antibody-associated RP-ILD patie nts. Through single-cell RNA sequencing (scRNA-seq), our study aims at describing the lan dscape of transcriptomes from immune cells in patients’ blood and lung, studying the differ ences among cell components from different patients, and exploring the differential gene ex pression of patients with different outcomes. We also compare the expression level of interf eron stimulated genes in patients and health controls. Finally, through high through-put ch ips (ProcartaPlex®), the cytokine and chemokine levels of BALF and serum are tested.【METHODS】In this prognostic factor study, univariate and multivariate Cox proportional hazards analy ses were carried out to determine the prognostic factors for anti-MDA5 antibody-associated RP-ILD. Propensity score matching was conducted to balance the baseline characteristics.Consequent survival analysis was completed using Kaplan-Meier analysis. As for scRNA-se q, principal component analysis was used to reduce the dimension of expression matrix. Aft er removing batch effects and standardizing, cell type annotations were carried out accordi ng to pre-calculated specific marker genes. Consequent enrichment analyses were complete d using GO and KEGG analysis. 【RESULTS】A total of 152 patients diagnosed with anti-MDA5 antibody-associated RP-ILD were enroll ed in our study, of which 40 patients were excluded because of infection before treatment. U nivariate cox proportional hazards analysis demonstrated that elder age of disease onset, hi gher level of γ-glutamyl transferase, higher level of hypersensitive C-reaction protein, large r dosage of glucocorticoid and usage of pulse therapy were possible risk factors. Multivariate cox proportional hazards analysis revealed that elder age of disease onset and hypersensit ive C-reaction protein were independent risk factors of poorer prognosis. Kaplan-Meier sur vival analysis after propensity score matching showed a tendency of curve separation but st atistically insignificant. ScRNA-seq showed that cell type composition of PBMC among pat ients varied a lot while cell type composition of BALF demonstrated similar patterns. Subse quent gene functional enrichment revealed a prominent upregulation of genes associated w ith type I interferon. We also found a prominent upregulation of chemokines in BALF, mos t of which were expressed by mono-macrophage systems and T helper cells.【Conclusions】 This was the first retrospective study to evaluate the efficacy of Tocilizumab on prognosis a mong anti-MDA5 antibody associated RP-ILD. Our study demonstrated that Tocilizumab might serve as a rescue therapy for patients who were refractory to standard treatment and might worth subsequent study. Additionally, our team first explored single-cell transcripto me of myositis and anti-MDA5 antibody associated RP-ILD. Local inflammation, instead o f systemic inflammation, might play a key role in pathogenesis of anti-MDA5 antibody asso ciated RP-ILD. Mono-phagocytes and T helper cells expressed chemokines and might contri bute to the local inflammation. Our study also proved from mRNA level that type I interfer on associated signal pathway was up-regulated and might shed light on novel treatment of this virulent disease.