Overview of causes of COPD. New understanding of pathogenesis and mechanisms can guide future therapy.

Recent studies have greatly expanded the understanding of pathogenetic mechanisms underlying COPD. Cigarette smoking is the most important cause. Activation of inflammatory mechanisms in the lung leads to tissue damage by a variety of mechanisms. Active proteases and oxidants are believed to play crucial roles. In response to this injury, repair mechanisms are activated. Unfortunately, these repair mechanisms also may be adversely affected by cigarette smoking. Insufficient repair of alveolar structures in response to injury likely leads to emphysema. Repair with scarring likely leads to airflow limitation in chronic bronchitis. Moreover, mediators that drive these processes have systemic effects that contribute to the syndromes characteristic of COPD. Understanding these mechanisms has created novel therapeutic approaches to the management of this disorder.