目的：研究创伤病人血清游离线粒体DNA（cell-free mitochondrial DNA, cf-mtDNA）含量变化及其与炎症反应的关系,探讨其临床价值。方法：创伤病人37例为创伤组,根据损伤程度分为多发伤组和单发伤组,及休克组和无休克组。10名健康志愿者为对照组。分别比较创伤组和对照组及创伤各亚组创伤后4 h、24 h、72 h和7 d时间点血清cf-mtDNA、 C反应蛋白（C-reactive protein, CRP）、 肿瘤坏死因子α（tumor necrosis factor-α,TNF-α）、白细胞介素6（interleukin-6,IL-6）含量差异,分析血清cf-mtDNA含量与损伤严重程度评分（injury severity score, ISS）、全身炎症反应综合征（systemic inflammatory response syndrome, SIRS）评分和血清CRP、TNF-α、IL-6含量的相关性。应用受试者工作特征（receiver operating characteristic, ROC）曲线评估创伤后血清cf-mtDNA含量诊断炎症反应的价值。结果：创伤病人伤后24 h、72 h血清cf-mtDNA含量明显高于对照组（均P<0.05）。多发伤组病人伤后4 h、24 h、72 h、7 d血清cf-mtDNA含量均明显高于单发伤组（分别P<0.05,P<0.01,P<0.01,P<0.05）。休克组病人伤后24 h血清cf-mtDNA含量明显高于无休克组病人（P<0.01）。创伤并发器官功能损伤组病人伤后4 h、24 h血清cf-mtDNA相对含量明显高于无并发器官功能损伤组（均P<0.05）。死亡病人血清cf-mtDNA含量峰值虽高于生存组,但差异无统计学意义（P>0.05）。随着创伤后血清cf-mtDNA含量升高的同时,血清TNF-α、IL-6、CRP含量也显著升高。创伤后24 h血清cf-mtDNA含量与ISS成正相关（r=0.454,P=0.004）。创伤后4 h~7 d血清cf-mtDNA含量分别与 SIRS评分、血清IL-6含量成正相关（分别r=0.458,P=0.000 1;r=0.252,P=0.005）,但与血清TNF-α含量不相关（r=-0.058,P=0.511）。创伤后4~24 h血清cf-mtDNA含量与血清CRP含量成正相关（r=0.264,P=0.028）。创伤后4 h~7 d血清cf-mtDNA含量诊断炎症反应ROC曲线下面积为0.752（P=0.000 01）,95%CI：0.668~0.836。根据最大约登指数计算结果,最佳临界值为0.075 3,其诊断炎症反应的灵敏度为63.6%,特异度为85.5%。结论：创伤病人创伤后早期血清cf-mtDNA含量升高,高血清cf-mtDNA含量表明创伤和炎症反应程度重。创伤后早期血清cf-mtDNA含量对炎症反应的诊断具有一定价值。

Objective To investigate change in amount of serum cell-free mitochondrial DNA (cf-mtDNA) related with inflammatory response and to explore clinical relevance to trauma patients. Methods Thirty-seven trauma patients as trauma group were divided as multiple trauma subgroup or single trauma subgroup, and as shock subgroup or non-shock subgroup. Ten healthy volunteers were as control group. The amount of cf-mtDNA in serum at 4 h, 24 h, 72 h, 7 d post-injury was compared between trauma group and control group and among subgroups. The association of serum cf-mtDNA with injury severity score (ISS), systemic inflammatory response syndrome (SIRS) score, C-reactive protein (CRP), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were analyzed respectively. The receiver operating characteristic (ROC) curve of serum cf-mtDNA post-injury were constructed to evaluate role in diagnosing SIRS. Results Serum cf-mtDNA in trauma patients at 24 h, 72 h post-injury were significantly higher than those in control group (P<0.05). Serum cf-mtDNA of patients in multiple trauma subgroup were significantly higher than those in single trauma subgroup at 4 h, 24 h, 72 h, 7 d post-injury (P<0.05, P<0.01, P<0.01, P<0.05). The amount of serum cf-mtDNA in shock subgroup were significantly higher than that in non-shock subgroup at 24 h post-injury (P<0.01), and that in group of organ dysfunction higher than in group without organ dysfunction at 4 h, 24 h post-injury (P<0.05). The peak of serum cf-mtDNA in dead patients was hi-gher than survived patients without statistical significance (P>0.05). Amounts of TNF-α, IL-6 and CRP in serum increased with serum cf-mtDNA post-injury. Amount of serum cf-mtDNA correlated positively with ISS at 24 h post-injury (r=0.454, P=0.004), with SIRS score and serum IL-6 at 4 h-7 d post-injury respectively(r=0.458, P=0.000 1; r=0.252, P=0.005), but did not correlate with serum TNF-α (r=-0.058, P=0.511), and with CRP at 4-24 h post-injury positively (r=0.264, P=0.028). The area under ROC curve of serum cf-mtDNA was 0.752 at 4 h-7 d post-injury (P=0.000 01), with 95% confidence interval of 0.668-0.836. According to maximum Youden index, the optimal cutoff value of serum cf-mtDNA was 0.075 2 with the sensitivity 63.6% and specificity 85.5% for diagnosis of SIRS. Conclusions The amount of serum cf-mtDNA increased in trauma patients at early stage, indicating severe trauma and inflammation, and more amount of serum cf-mtDNA would be helpful to diagnose SIRS.