The lung microbiome in moderate and severe chronic obstructive pulmonary diseaseOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study characterized the lung microbiome in chronic obstructive pulmonary disease and compared it with healthy controls. It focused on stable patients without recent exacerbations, steroids, or antibiotics. Bronchoalveolar lavage fluid was analyzed by 454 pyrosequencing of 16S ribosomal DNA. Sequences were processed with mothur, RDP, Fast UniFrac, and Metastats to compare diversity and differential taxa.
Who was studied?
The study analyzed 32 human bronchoalveolar lavage samples. These came from 22 patients with moderate or severe COPD (14 moderate, 8 severe) and 10 healthy controls. COPD patients were ambulatory, non-smokers for at least six months, without systemic steroids for two months. Controls included 4 smokers and 6 non-smokers with normal lung function, recruited in the United States.
What were the most important findings?
Microbial diversity was higher in COPD than controls by Shannon and Simpson indices, but this difference disappeared after controlling for age, which was itself associated with diversity. The main phyla across samples were Actinobacteria, Firmicutes, and Proteobacteria. Principal coordinate analysis separated controls from COPD, but not moderate from severe disease. Several oral-flora bacteria increased in COPD, including Fusobacterium, Leptotrichia, Streptococcus, and Prevotella. Samples also clustered by inhaled corticosteroid and bronchodilator use.
What are the greatest implications of this study?
The findings reinforce that the lung microbiome largely reflects microaspiration of oral flora, linking oral health to COPD. Age and inhaled medications, not disease severity alone, shaped community structure. The small, non-age-matched controls and cross-sectional design limit causal claims. The enrichment of oral bacteria tied to periodontal disease suggests dental care could matter for respiratory outcomes.