Department of Nephrology, Clinical Medical College and The First Affiliated Hospital of Chengdu Medical College, Chengdu, China.
Department of Neurology, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China.
J Clin Lab Anal. 2022 Jul;36(7):e24558. doi: 10.1002/jcla.24558. Epub 2022 Jun 16.
Mitochondrial DNA (MtDNA) exposed to the extracellular space due to cell death and stress has immunostimulatory properties. However, the clinical significance of circulating MtDNA in maintenance hemodialysis (MHD) patients and the precise mechanism of its emergence have yet to be investigated.
This cross-sectional study consisted of 52 MHD patients and 32 age- and sex-matched healthy controls. MHD patients were further categorized into high and low circulating cell-free MtDNA (ccf-MtDNA) groups based on the median value. Copy number of MtDNA was quantified using TaqMan-based qPCR. Plasma cytokines were measured using ELISA kits. Reactive oxygen species (ROS) and mitochondrial membrane potential (Δψm) in peripheral blood mononuclear cells (PBMCs) were detected using DCFH-DA or JC-1 staining.
The copy numbers of ccf-MtDNA in patients with MHD were higher than those in healthy controls, and these alterations were correlated with changes of cytokines TNF-α and IL-6. Adjusted model in multivariate analysis showed that the presence of anuria and longer dialysis vintage were independently associated with higher levels of ccf-MtDNA. Meanwhile, although not statistically significant, an inverse correlative trend between urinary MtDNA and ccf-MtDNA was observed in patients with residual urine. Afterward, using PBMCs as surrogates for mitochondria-rich cells, we found that patients in the high ccf-MtDNA group exhibited a significantly higher ROS production and lower Δψm in cells.
Our data suggested that changes in ccf-MtDNA correlate with the degree of inflammatory status in MHD patients, and that the excessive MtDNA may be caused by mitochondrial dysfunction and reduced urinary MtDNA excretion.
由于细胞死亡和应激，线粒体 DNA（MtDNA）暴露于细胞外空间，具有免疫刺激性。然而，循环 MtDNA 在维持性血液透析（MHD）患者中的临床意义及其确切的产生机制尚未得到研究。
这项横断面研究包括 52 名 MHD 患者和 32 名年龄和性别匹配的健康对照者。根据中位数，MHD 患者进一步分为高和低循环无细胞 MtDNA（ccf-MtDNA）组。使用 TaqMan 基于 qPCR 定量 MtDNA 拷贝数。使用 ELISA 试剂盒测量血浆细胞因子。使用 DCFH-DA 或 JC-1 染色检测外周血单核细胞（PBMCs）中的活性氧（ROS）和线粒体膜电位（Δψm）。
MHD 患者的 ccf-MtDNA 拷贝数高于健康对照组，这些改变与细胞因子 TNF-α和 IL-6 的变化相关。多元分析调整模型显示，无尿和透析时间较长与 ccf-MtDNA 水平升高独立相关。同时，尽管没有统计学意义，但在有残余尿的患者中观察到尿 MtDNA 和 ccf-MtDNA 之间呈负相关趋势。随后，使用 PBMCs 作为富含线粒体细胞的替代物，我们发现 ccf-MtDNA 水平较高的患者细胞中 ROS 产生显著增加，Δψm 降低。
我们的数据表明，ccf-MtDNA 的变化与 MHD 患者炎症状态的严重程度相关，并且过多的 MtDNA可能是由线粒体功能障碍和尿 MtDNA 排泄减少引起的。
