Relationship Between Airway Inflammation, Small Airways Dysfunction, and Frequency of Acute Exacerbations in Patients With Chronic Obstructive Pulmonary Disease

Chronic Obstructive Pulmonary Disease (COPD) is a common, preventable, and treatable disease that is characterized by persistent respiratory symptoms and airflow limitation that is due to airway and/or alveolar abnormalities usually caused by significant exposure to noxious particles or gases Chronic Obstructive Pulmonary Disease (COPD) is a heterogenous disease of the lungs that can comprise of different pathophysiological phenotypes, including emphysema, chronic bronchitis, and Small Airways Disease (SAD). COPD is also associated with chronic inflammation and this ongoing inflammation may result in airway remodeling and excessive mucus plugging within the small airways Small airways disease (SAD) is a cardinal feature of chronic obstructive pulmonary disease (COPD) first recognized in the nineteenth century. The diverse histopathological features associated with SAD underpin the heterogeneous nature of COPD. The small airways have been defined as < 2mm diameter and arise from the 4th - 13th generation of airway branching (taking trachea as 1st generation to alveoli as 23rd), but on average arise by the 8th Small airway disease (SAD) has been recognized for many years as a central feature of chronic obstructive pulmonary disease (COPD). Histopathology studies have shown that the narrowing and destruction of small airways in COPD combined with inflammatory cell infiltration in the submucosa increases the severity of the disease. SAD is present in the early stages of COPD and becomes more widespread over time as the disease progresses to more severe COPD Exacerbations are an acute worsening of symptoms resulting in additional therapy and can be classified as mild, moderate, or severe, Exacerbations are associated with faster lung function decline and hospital admissions During both stable periods and exacerbations, there is increased neutrophilic inflammation in the airways of COPD subjects , Neutrophilic inflammation is a common feature of many airway diseases and is associated with disease progression, often irrespective of the initiating cause or underlying diagnosis The aim of this work is to study the relationship between neutrophilic airway inflammation, small airways dysfunction, and frequency of acute exacerbation in stable COPD patients.