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.
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。