Does Protease-Antiprotease Imbalance Explain Chronic Obstructive Pulmonary Disease?

Chronic obstructive pulmonary disease (COPD) is defined as airflow limitation that is not fully reversible. The airflow limitation is usually progressive and is associated with the inhalation of noxious gases, typically cigarette smoke. The protease-antiprotease paradigm suggests that the pathogenesis of COPD and emphysema is the result of an imbalance between enzymes that degrade the extracellular matrix within the lung and proteins that oppose this proteolytic activity. This review assesses the genetic evidence in support of protease-antiprotease imbalance in the pathogenesis of COPD. It also articulates why suppression of protease activity in alpha-1 antitrypsin deficiency may be insufficient to prevent the progression of COPD. Rather, alpha-1 antitrypsin deficiency may be better treated by small-molecules so reads molecules, RNA-silencing, and other strategies that target the protein misfolding and polymerization that cause the disease.