摘要INTRODUCTION Chronic obstructive pulmonary disease (COPD) is a worldwide respiratory disease which always co-exists with multiple extrapulmonary comorbidities such as cardiovascular diseases and osteoporosis.The World Health Organization pointed out that till 2030,COPD would be the third leading reason of mortality.[1] In spite of the advanced medical research and health-care efforts,COPD still shows continuously increasing quantity of death.Tobacco smoking,indoor and outdoor air pollution (for example,biomass fuel),virus,and pulmonary dysplasia are the main risk factors for COPD.All these factors eventually destroy lung parenchymal tissue and disturb repair and defense system,which eventually lead to emphysema and small airway fibrosis [Figure 1].