COPD and the microbiome.

Traditional culture techniques confirm that bacteria have an important role in Chronic Obstructive Pulmonary Disease (COPD). In individuals with COPD, acquisition of novel bacterial strains is associated with onset of acute exacerbation of COPD, which leads to further lung dysfunction and enormous health-care costs. Recent study of the human microbiome, the total composite of the bacteria on the human body, posited the microbiome as the last human organ studied, as the microbiome performs a multitude of metabolic functions absent in the human genome. The largest project to study the human microbiome was the National Institutes of Health (NIH) human microbiome project (HMP) started in 2007 to understand the 'normal' microbiome. However due to the presumption that the healthy human lung was sterile, the respiratory tract was not included in that study. The advent of next-generation sequencing technologies has allowed the investigation of the human respiratory microbiome, which revealed that the healthy lung does have a robust microbiome. Subsequent studies in individuals with COPD revealed that the microbiome composition fluctuates with severity of COPD, composition of the individual aero-digestive tract microbiomes, age, during an acute exacerbation of COPD and with the use of steroids and/or antibiotics. Understanding the impact of the microbiome on COPD progression and risk of exacerbation will lead to directed therapies for prevention of COPD progression and exacerbation.