PDF(Pubmed)
Abstract：
BACKGROUND: Extracellular mitochondrial DNA (mtDNA) is released from damaged cells and increases in the serum and bronchoalveolar lavage fluid (BALF) of idiopathic pulmonary fibrosis (IPF) patients. While increased levels of serum mtDNA have been reported to be linked to disease progression and the future development of acute exacerbation (AE) of IPF (AE-IPF), the clinical significance of mtDNA in BALF (BALF-mtDNA) remains unclear. We investigated the relationships between BALF-mtDNA levels and other clinical variables and prognosis in IPF.
METHODS: Extracellular mtDNA levels in BALF samples collected from IPF patients were determined using droplet-digital PCR. Levels of extracellular nucleolar DNA in BALF (BALF-nucDNA) were also determined as a marker for simple cell collapse. Patient characteristics and survival information were retrospectively reviewed.
RESULTS: mtDNA levels in serum and BALF did not correlate with each other. In 27 patients with paired BALF samples obtained in a stable state and at the time of AE diagnosis, BALF-mtDNA levels were significantly increased at the time of AE. Elevated BALF-mtDNA levels were associated with inflammation or disordered pulmonary function in a stable state (n = 90), while being associated with age and BALF-neutrophils at the time of AE (n = 38). BALF-mtDNA ≥ 4234.3 copies/µL in a stable state (median survival time (MST): 42.4 vs. 79.6 months, p < 0.001) and ≥ 11,194.3 copies/µL at the time of AE (MST: 2.6 vs. 20.0 months, p = 0.03) were associated with shorter survival after BALF collection, even after adjusting for other known prognostic factors. On the other hand, BALF-nucDNA showed different trends in correlation with other clinical variables and did not show any significant association with survival time.
CONCLUSIONS: Elevated BALF-mtDNA was associated with a poor prognosis in both IPF and AE-IPF. Of note, at the time of AE, it sharply distinguished survivors from non-survivors. Given the trends shown by analyses for BALF-nucDNA, the elevation of BALF-mtDNA might not simply reflect the impact of cell collapse. Further studies are required to explore the underlying mechanisms and clinical applications of BALF-mtDNA in IPF.
METHODS: Extracellular mtDNA levels in BALF samples collected from IPF patients were determined using droplet-digital PCR. Levels of extracellular nucleolar DNA in BALF (BALF-nucDNA) were also determined as a marker for simple cell collapse. Patient characteristics and survival information were retrospectively reviewed.
RESULTS: mtDNA levels in serum and BALF did not correlate with each other. In 27 patients with paired BALF samples obtained in a stable state and at the time of AE diagnosis, BALF-mtDNA levels were significantly increased at the time of AE. Elevated BALF-mtDNA levels were associated with inflammation or disordered pulmonary function in a stable state (n = 90), while being associated with age and BALF-neutrophils at the time of AE (n = 38). BALF-mtDNA ≥ 4234.3 copies/µL in a stable state (median survival time (MST): 42.4 vs. 79.6 months, p < 0.001) and ≥ 11,194.3 copies/µL at the time of AE (MST: 2.6 vs. 20.0 months, p = 0.03) were associated with shorter survival after BALF collection, even after adjusting for other known prognostic factors. On the other hand, BALF-nucDNA showed different trends in correlation with other clinical variables and did not show any significant association with survival time.
CONCLUSIONS: Elevated BALF-mtDNA was associated with a poor prognosis in both IPF and AE-IPF. Of note, at the time of AE, it sharply distinguished survivors from non-survivors. Given the trends shown by analyses for BALF-nucDNA, the elevation of BALF-mtDNA might not simply reflect the impact of cell collapse. Further studies are required to explore the underlying mechanisms and clinical applications of BALF-mtDNA in IPF.
摘要：
背景：特发性肺纤维化（IPF）患者的细胞外线粒体DNA（mtDNA）从受损细胞中释放并增加血清和支气管肺泡灌洗液（BALF）。虽然据报道血清mtDNA水平升高与疾病进展和IPF急性加重（AE）的未来发展有关，BALF中mtDNA（BALF-mtDNA）的临床意义尚不清楚。我们调查了IPF中BALF-mtDNA水平与其他临床变量和预后之间的关系。
方法：使用液滴数字PCR测定从IPF患者收集的BALF样品中的细胞外mtDNA水平。还测定了BALF中细胞外核仁DNA的水平（BALF-nucDNA）作为简单细胞塌陷的标记。回顾性分析患者特征和生存信息。
结果：血清和BALF中的mtDNA水平不相关。在27例患者中，在稳定状态和AE诊断时获得配对的BALF样本，BALF-mtDNA水平在AE时显著增加。BALF-mtDNA水平升高与稳定状态下的炎症或肺功能紊乱相关（n=90），同时与AE时的年龄和BALF-中性粒细胞有关（n=38）。稳定状态下的BALF-mtDNA≥4234.3拷贝/µL（中位生存时间（MST）：42.4vs.79.6个月，p<0.001）和≥11,194.3拷贝/µL时的AE（MST：2.6vs.20.0个月，p=0.03）与BALF收集后的生存期较短有关，即使在调整了其他已知的预后因素后。另一方面,BALF-nucDNA显示出与其他临床变量相关的不同趋势，并且与生存时间没有任何显着关联。
结论：BALF-mtDNA升高与IPF和AE-IPF的不良预后相关。值得注意的是，在AE的时候，它将幸存者与非幸存者区分开来。鉴于BALF-nucDNA分析显示的趋势，BALF-mtDNA的升高可能不能简单地反映细胞崩溃的影响。需要进一步的研究来探索BALF-mtDNA在IPF中的潜在机制和临床应用。
方法：使用液滴数字PCR测定从IPF患者收集的BALF样品中的细胞外mtDNA水平。还测定了BALF中细胞外核仁DNA的水平（BALF-nucDNA）作为简单细胞塌陷的标记。回顾性分析患者特征和生存信息。
结果：血清和BALF中的mtDNA水平不相关。在27例患者中，在稳定状态和AE诊断时获得配对的BALF样本，BALF-mtDNA水平在AE时显著增加。BALF-mtDNA水平升高与稳定状态下的炎症或肺功能紊乱相关（n=90），同时与AE时的年龄和BALF-中性粒细胞有关（n=38）。稳定状态下的BALF-mtDNA≥4234.3拷贝/µL（中位生存时间（MST）：42.4vs.79.6个月，p<0.001）和≥11,194.3拷贝/µL时的AE（MST：2.6vs.20.0个月，p=0.03）与BALF收集后的生存期较短有关，即使在调整了其他已知的预后因素后。另一方面,BALF-nucDNA显示出与其他临床变量相关的不同趋势，并且与生存时间没有任何显着关联。
结论：BALF-mtDNA升高与IPF和AE-IPF的不良预后相关。值得注意的是，在AE的时候，它将幸存者与非幸存者区分开来。鉴于BALF-nucDNA分析显示的趋势，BALF-mtDNA的升高可能不能简单地反映细胞崩溃的影响。需要进一步的研究来探索BALF-mtDNA在IPF中的潜在机制和临床应用。
