Background

The sputum microbiome has a potential role in disease phenotyping and risk stratification in chronic obstructive pulmonary disease (COPD), but few large longitudinal cohort studies exist.

Objective

Our aim was to investigate the COPD sputum microbiome and its association with inflammatory phenotypes and mortality.

Methods

16S ribosomal RNA gene sequencing was performed on sputum from 253 clinically stable COPD patients (4-year median follow-up). Samples were classified as Proteobacteria or Firmicutes (phylum level) and Haemophilus or Streptococcus (genus level) dominant. Alpha diversity was measured by using Shannon-Wiener diversity and Berger-Parker dominance indices. Survival was modeled by using Cox proportional hazards regression. A subset of 78 patients had label-free liquid chromatography with tandem mass spectrometry performed, with partial least square discriminant analysis integrating clinical, microbiome, and proteomics data.

Results

Proteobacteria dominance and lower diversity was associated with more severe COPD according to the Global Initiative for Chronic Obstructive Lung Disease classification system (P = .0015), more frequent exacerbations (P = .0042), blood eosinophil level less than or equal to 100 cells/μL (P < .0001), and lower FEV₁ (P = .026). Blood eosinophil counts showed a positive relationship with percent of Firmicutes and Streptococcus and a negative association with percent Proteobacteria and Haemophilus. Proteobacteria dominance was associated with increased mortality compared with Firmicutes-dominated or balanced microbiome profiles (hazard ratio = 2.58; 95% CI = 1.43-4.66; P = .0017 and hazard ratio = 7.47; 95% CI = 1.02-54.86; P = .048, respectively). Integrated omics analysis showed significant associations between Proteobacteria dominance and the neutrophil activation pathway in sputum.

Conclusion

The sputum microbiome is associated with clinical and inflammatory phenotypes in COPD. Reduced microbiome diversity, associated with Proteobacteria (predominantly Haemophilus) dominance, is associated with neutrophil-associated protein profiles and an increased risk of mortality.

中文翻译：

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慢性阻塞性肺疾病的痰液微生物组，气道炎症和死亡率。

背景

在慢性阻塞性肺疾病（COPD）中，痰微生物组在疾病表型和风险分层中具有潜在作用，但目前尚无大型纵向队列研究。

目的

我们的目的是调查COPD痰微生物组及其与炎症表型和死亡率的关系。

方法

对253名临床稳定的COPD患者的痰液进行了16S核糖体RNA基因测序（4年中位随访）。样品被分类为Proteobacteria或Firmicutes（属水平），而以嗜血杆菌属或Streptococcus（属水平）为主。通过使用Shannon-Wiener分集和Berger-Parker优势指数来测量Alpha分集。生存率通过使用Cox比例风险回归建模。78例患者的一部分进行了无标记液相色谱-串联质谱分析，部分最小二乘判别分析整合了临床，微生物组和蛋白质组学数据。

结果

根据《全球慢性阻塞性肺疾病倡议》分类系统（P  = .0015），蛋白细菌优势和较低的多样性与更严重的COPD相关，加重频率更高（P  = .0042），血液嗜酸性粒细胞水平小于或等于100个细胞/μL（P  <.0001）和较低的FEV ₁（P  = .026）。血液嗜酸性粒细胞计数与Firmicutes和链球菌的百分比呈正相关，与Proteobacteria和嗜血杆菌的百分比呈负相关。与Firmicutes为主或平衡的微生物组谱相比，变形杆菌优势与死亡率增加相关（危险比= 2.58; 95％CI = 1.43-4.66; P  = .0017，危险比= 7.47; 95％CI = 1.02-54.86; P  = .048）。综合组学分析显示，细菌的优势度与痰液中性粒细胞活化途径之间存在显着关联。

结论

痰中的微生物组与COPD的临床和炎性表型有关。与变形杆菌（主要是嗜血杆菌）优势相关的微生物组多样性降低，与中性粒细胞相关的蛋白质谱和死亡风险增加相关。