脓毒症患儿血浆线粒体DNA的变化及临床意义

The clinical significance of changes in plasma mitochondrial DNA in children with sepsis

目的本研究采用前瞻性研究方法观察脓毒症患儿血浆线粒体DNA（mtDNA）动态变化，探索血浆mtDNA对评估脓毒症患儿病情的临床价值。方法将2016年6月至2017年1月收住湖南省儿童医院重症监护病房的37例脓毒症患儿作为人选对象，分别于住院第1、3、7天3个时间点抽取股静脉血采用实时荧光定量PCR检测血浆mtDNA水平，另随机选取同时期年龄、性别相仿的健康体检儿童27例为对照组；同时检测CRP、PCT等实验室指标。脓毒症及脓毒性休克的临床诊断依据按照Sepsis3的标准，排除本身有遗传代谢性疾病、肝肾疾病、肿瘤终末期患儿。两样本间比较采用Mann-Whitney U检验。采用受试者工作曲线（ROC）评估其灵敏度和特异度。结果脓毒症与正常组对比，脓毒症组血浆mtDNA水平3384．4（1368．5，6857．5）pg／mL，高于健康对照组1904．8（1267．9，2395．5）pg／mL，差异有统计学意义（P〈0．05）。脓毒症多器官障碍组血浆mtDNA水平在入院第1、3、7天均高于单器官障碍组，差异有统计学意义（P〈0．05）。脓毒症休克组血浆mtDNA水平在人院第1、3、7天均显著高于非休克组，差异有统计学意义（P〈0．05）。脓毒症死亡组血浆mtDNA水平在入院第1、3、7天均高于存活组，第1、3天差异有统计学意义（P〈0．05），第7天差异无统计学意义（P〉0．05）。血浆mtDNA与PCT、CRP预测脓毒症MODS诊断效能：血浆mtDNA第1天曲线下面积最大为0．848，临界值为2176．2pg／mL，其灵敏度和特异度为89％、72％，差异有统计学意义（P〈0．05）。当CRP临界值为71．3mg／L时其灵敏度和特异度为58％、67％。当PCT临界值7．24ng／L时其灵敏度和特异度为84％、61％。动态观察发现，各组血浆mtDNA峰值出现在入院第1天，随后呈动态下降趋势。结论脓毒症患儿血浆mtDNA水平升高，与器官功能损伤有关，表明其可用作儿童脓毒症MODS诊断的生物标志物之一。脓毒症患儿血浆mtDNA水平在入院后第1、3天升高明显，与病情严重性呈正相关，对脓毒症病情严重程度的判断及预后评估有一定价值。

Objective To observe the dynamic changes of plasma mitochondrial DNA （mtDNA） in children with sepsis in order to explore the clinical value of it in evaluation of these cases. Methods A total of 37 sepsis children admitted from June 2016 to January 2017 in the intensive care unit of Hunan Children＇s Hospital were enrolled for this prospectively study. And another 27 healthy children with similar age and gender were randomly selected as the control group. The venous blood samples were taken on the 1 st, 3rd and 7th day after admission. Fluorescence quantitative PCR was used to detect the plasma mtDNA level. Meanwhile, the laboratory examinations such as detections of CRP and PCT were carried out. The diagnosis of sepsis and septic shock was based on Sepsis Criteria 3. Patients with genetic metabolic disease, liver and kidney disease, end-stage of tumors were excluded. Data of two groups were analyzed with Mann-Whitney U test. The sensitivity and specificity were assessed by receiver operating curve （ROC）. Results The plasma mtDNA level in the sepsis group 3 384.4（1 368.5, 6 857.5） pg/mL was higher than that in the healthy control group 1 904.8（1 267.9, 2 395.5） pg/mL with statistical significance （P〈0.05）. The levels of plasma mtDNA in the sepsis multi-organ dysfunction group were higher than those in the single organ disorder group at day 1,3,7, with statistically significant in three intervals （P 〈0.05）. The level of plasma mtDNA in sepsis group were significantly higher than those in non-shock group at day 1,3,7, with statistical difference （P 〈0.05）. The plasma mtDNA levels in the non-survival group were higher than those in survival group 13 515.1（4 832.7, 152 348.5） vs. 2 780.0（1 226.8, 5 261.2） on day 1; 5 842.4（3 402.8, 101 937.5） vs. 1 450.5（710.6, 2 481.6）on day 3 with statistical difference （P 〈0.05）.there was no significant difference in mtDNA on day 7 was 1 045.1 vs. 741.8（334.0, 1 254.6） between survival group and non-survival group （P 〉0.05）. In respect of diagnostic efficacy of plasma mtDNA, PCT and CRP in predicting sepsis MODS, the largest area under the ROC curve of plasma mtDNA was 0.848 oceurring on the 1st day, when the critical value was 2 176.2 pg/mL, the sensitivity and specificity was 89% and 72%, respectively, and the difference was statistically significant（P〈0.01）. When the critical value of CRP was 71.3 mg/L, the sensitivity and specificity was 58% and 67% respectively. When the critical value of PCT was 7.24 ng/L, the sensitivity and specificity were 84% and 61%, respectively. The plasma mtDNA peaked on day 1 followed by a downward changes. Conclusions The elevated level of plasma mtDNA in sepsis children was associated with organ dysfunction, indicating that it can be used as one of biomarkers for the diagnosis of sepsis MODS in children. The level of plasma mtDNA in children with sepsis was significantly high on the first and third day after admission, which was positively correlated with the severity of sepsis and it has certain value in assessment of the disease.