Analysis of the Microbiome in the Healthy Smokers and COPD Patients

Brief Summary: This study is to build a microbiome cohort by collecting sputum and fecal samples every few months for three years from healthy smokers and chronic obstructive pulmonary disease (COPD) patients. The aim of this study is to analyze the composition of microbiome of various samples (e.g. sputum, feces) and describe the difference between healthy smokers and COPD patients.

Detailed Description: After the introduction of the gut-lung axis theory, extensive studies revealed the diversity of microbiomes among healthy smokers and COPD patients form the respiratory samples or lung tissues. In the previous study, distinct difference in composition of microbiome in lung tissue between healthy smokers and COPD patients was reported. This study is to build a microbiome cohort by collecting sputum and fecal samples every few months for three years from healthy smokers and chronic obstructive pulmonary disease (COPD) patients who are being followed up by Asan Medical Center. The aim of this study is to analyze the composition of microbiome of various samples (e.g. sputum, feces) and describe the difference between healthy smokers and COPD patients. This study would help establishing gut-lung axis model in humans.

Recruitment & Eligibility

Inclusion Criteria

Patients with smoking history at least 10 pack-year
Patients with persistent airflow limitation that was not fully reversible (e.g. post-bronchodilator forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) <0.7)

Exclusion Criteria

Patients with co-existing illness that would interfere with study results (e.g., malignancy, congestive heart failure, cerebrovascular disorders, chronic renal failure, diabetes with severe complications, or uncontrolled hypertension)
Patients with respiratory disease other than obstructive lung disease (e.g., previous pulmonary resection, tuberculosis-destroyed lung, and bronchiectasis)

Arm && Interventions

Group	Intervention	Description
Healthy smoker	Obtain samples from sputum and feces	Healthy smokers with smoking history at least 10 pack-years and normal spirometry value
COPD patient	Obtain samples from sputum and feces	Patients with smoking history at least 10 pack-years and persistent airflow limitation that was not fully reversible (e.g. post-bronchodilator forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) \<0.7)

Primary Outcome Measures

Name	Time	Method
Microbiome composition by metagenomic analysis	An average of 3 months	The composition of microbiome is presented as bar graph.
Alpha diversity measured by operational taxonomic unit (OTU) quantitative analysis	An average of 3 months	DNA is extracted from each sample from each patient by using a DNA Isolation Kit. The 16S universal primers are used for amplification of 16S ribosomal ribonucleic acid (rRNA) genes with polymerase chain reaction (PCR) system. After amplication, sequencing is performed using the GREENGENES database, after which a metagenomic analysis was performed by the MD Healthcare corporation using MDx-Pro software (Ver.1, Seoul, South Korea). Taxonomic assignment of these sequences is carried out with an operational taxonomic unit (OTU) cutoff of 3%.

Secondary Outcome Measures

Name	Time	Method
Biodiversity described by the Shannon diversity index and the Simpson index	An average of 3 months	The Shannon index and the Simpson index is calculated by using metagenomic data.
Biodiversity described by Principal Component Analysis (PCA)	An average of 3 months	PCA is performed for all 16S rRNA gene reads clustered at a 97% similarity.

Locations (1): Department of Pulmonary and Critical Care Medicine and Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine
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Seoul, Korea, Republic of

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