中文摘要：

目的 探讨低密度粒细胞（LDGs）在DM患者伴发的间质性肺病（ILD）中的意义.方法 纳入了48例DM患者和19名健康对照,其中28例DM患者患有ILD.采用流式细胞术测定PBMCs中LDGs的比例;采用实时定量PCR法测定PBMCs中中性粒细胞相关基因（LL-37、髓过氧化物酶和MMP-8）的mRNA表达水平;采用ELISA法测定PBMCs总蛋白中LL-37的浓度;采用肌炎活动度视觉模拟评分（MYOACT）评估疾病活动度.采用Welch校正的非配对t检验比较伴发ILD的患者和未患ILD的患者LDGs水平的差异,LDGs与临床指标的相关性采用单因素相关分析,PBMCs中中性粒细胞相关基因和蛋白表达水平的比较采用Mann-WhitneyU检验.结果 DM患者PBMCs中LDGs的比例显著升高,是健康对照LDGs均数的7.1倍[（9.1±11.5）％和（1.3±0.7）％,t=4.664,P＜0.01];且伴有ILD的DM患者中LDGs 的比例显著高于不伴ILD的DM患者[（12.3±14.1）％和（4.5±2.6）％,t=2.835,P=0.008 3],是不合并ILD的DM患者LDGs均数的2.7倍;LL-37、髓过氧化物酶和MMP-8的mRNA表达水平和LL-37的蛋白表达水平在DM组显著高于健康对照组;LDGs比例与MYOACT肺疾病活动度评分呈正相关（r=0.439,P=0.010）.结论 DM合并ILD的患者LDGs的比例明显增高,而且与MYOACT肺疾病活动度评分呈正相关,提示异常增多的LDGs是DM合并ILD的可能参与因素.

英文摘要：

Objective This study aims to test the hypothesis that low density granulocytes （LDGs） is involved in the pathogenesis of DM associated-Interstitial lung disease （ILD）.Methods Forty eight DM patients （28 with ILD） and 19 age-and sex-matched healthy Chinese volunteers were recruited to this study.LDGs percentage in peripheral blood mononuclear cells （PBMCs） was tested by flow cytometry.Neutrophilrelated genes （LL-37,MPO and MMP-8） expressions in PBMCs were tested by quantitative RT-PCR.Myositis disease activity assessment visual analogue scales （MYOACT） was used to assess the disease activity.Percentages of LDGs were compared in patients with ILD and without by using unpaired t test with Welch＇s correction,the correlations between LDGs and clinical parameters were further analyzed by linear correlation analysis.The expressions of neutrophil-related mRNA and proteins in PBMCs were compared by using MannWhitney U test.Results LDGs percentage in PBMCs was 7.1-fold higher in DM patients than healthy controls [（9.1±11.5）％ vs （1.3±0.7）％,t=4.664,P＜0.01].LDGs percentage in PBMCs was 2.7-fold higher in DM patients with ILD than DM patients without ILD [（12.3±14.1）％ vs （4.5±2.6）％,t=2.835,P=0.008 3].The mRNA expression level of LL-37,MPO and MMP-8 and LL-37 protein levels in the DM group were significantly higher than those in the control group.LDGs percentage positively correlated with MYOACT lung disease activity scores （r=0.439,P=0.010）.Conclusion Percentage of LDGs in PBMCs is significantly increased in DM patients with ILD and positively correlated with MYOACT lung disease activity scores,suggesting that abnormall increasing of LDGs is a potential contributor to the pathogenesis of DM-associated ILD.