Abstract
Respiratory infections are well-known triggers of chronic respiratory diseases. Recently, culture-independent tools have indicated that lower airway microbiota may contribute to pathophysiologic processes associated with asthma and chronic obstructive pulmonary disease (COPD). However, the relationship between upper airway microbiota and chronic respiratory diseases remains unclear. This study was undertaken to define differences of microbiota in the oropharynx of asthma and COPD patients relative to those in healthy individuals. To account for the qualitative and quantitative diversity of the 16S rRNA gene in the oropharynx, the microbiomes of 18 asthma patients, 17 COPD patients, and 12 normal individuals were assessed using a high-throughput next-generation sequencing analysis. In the 259,572 total sequence reads, α and β diversity measurements and a generalized linear model revealed that the oropharynx microbiota are diverse, but no significant differences were observed between asthma and COPD patients. Pseudomonas spp. of Proteobacteria and Lactobacillus spp. of Firmicutes were highly abundant in asthma and COPD. By contrast, Streptococcus, Veillonella, Prevotella, and Neisseria of Bacteroidetes dominated in the healthy oropharynx. These findings are consistent with previous studies conducted in the lower airways and suggest that oropharyngeal airway microbiota are important for understanding the relationships between the various parts of the respiratory tract with regard to bacterial colonization and comprehensive assessment of asthma and COPD.
Highlights
Asthma and chronic obstructive pulmonary disease (COPD) are common chronic inflammatory diseases of the airways, and their prevalence and mortality rates continue to increase, establishing them as leading causes of disability worldwide [1]
The World Health Organization (WHO) estimates that 235 million people are annually affected by asthma and approximately 250,000 people die per year worldwide [2]
Study subjects All of the samples were collected from individuals with newly diagnosed asthma and COPD in accordance with the ethical guidelines mandated by the commission a protocol that was approved by the University’s Human Subjects Institutional Review Board (IRB) of Chung-Ang University College of Medicine, Seoul, Korea
Summary
Asthma and chronic obstructive pulmonary disease (COPD) are common chronic inflammatory diseases of the airways, and their prevalence and mortality rates continue to increase, establishing them as leading causes of disability worldwide [1]. Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis are clinically relevant contributors to asthma exacerbations, when sinusitis is present [1,2]. Atypical bacteria such as Chlamydophila pneumoniae and Mycoplasma pneumoniae may be associated with asthma [6,7,8]. Pseudomonas aeruginosa, Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae are known to be associated with a significantly increased risk of exacerbation of COPD. The prevalence of bacterial pathogens in the lower airways was found to be the same during acute exacerbations and stable disease; changes in bacterial load are unlikely to be an important mechanism underlying exacerbation of COPD [9,10,11]
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