From the Guidelines
Smokers with chronic obstructive pulmonary disease (COPD) typically have elevated levels of neutrophils and macrophages in their airways and airspaces. These cells play a crucial role in the inflammatory process associated with COPD, as they release inflammatory mediators that damage lung tissue and contribute to the development of respiratory diseases like chronic bronchitis and emphysema 1. The inflammatory mechanisms of COPD have been extensively reviewed, and studies have shown that structural changes in the airways of smokers, including mucus gland hyperplasia, bronchiolar edema, smooth muscle hypertrophy, and peribronchiolar fibrosis, result in a narrowing of the small airways 1. Key factors in the pathogenesis of COPD include:
- Increased quantities of proinflammatory cytokines, such as interleukin (IL)-8, IL-1, IL-6, and tumor necrosis factor- 1
- Activation of sensory airway nerves containing tachykinins, which augment airway secretions 1
- Mucous gland enlargement and hyperplasia of goblet cells, leading to excess mucus production 1
- Impaired mucociliary clearance, resulting in the retention of secretions and a vicious cycle of chronic recurrent coughing 1. Overall, the elevation of neutrophils and macrophages in smokers with COPD is a key component of the inflammatory response, contributing to the development and progression of the disease 1.
From the Research
Inflammatory Cells in Smokers with COPD
- Neutrophils are significantly higher in COPD patients with a history of smoking compared to those with anterior tuberculosis 2
- Neutrophils, monocytes, and basophils are increased in smokers with COPD 3
- Total and activated neutrophils predominate in severe COPD, while T lymphocytes, particularly CD8+ cells and macrophages, are prevalent in the lung of healthy smokers and patients with mild COPD 4
- Neutrophils and macrophages have been implicated in the inflammatory response to cigarette smoke in COPD, releasing proteolytic enzymes and generating oxidants that cause tissue damage 5
- CD8+ T cells are increased in the lung tissue of COPD patients and are positively related to the severity of disease, airway obstruction, and degree of alveolar wall damage in emphysema 5
Comparison of Inflammatory Cells in Smokers and Ex-Smokers with COPD
- There are no significant differences between smokers and ex-smokers in the numbers of inflammatory cell types, including CD4+ and CD8+ T-lymphocytes, macrophages, neutrophils, and eosinophils 6
- The bronchial mucosal inflammatory cell infiltrate is similar in ex-smokers and those who continue to smoke 6