Chronic obstructive pulmonary disease: effects beyond the lungs

Abstract

Peter Barnes discusses the growing epidemic of chronic obstructive pulmonary disease (COPD), especially in developing countries and among nonsmokers.

Figure 1. Patients with COPD have peripheral lung inflammation that may spill over into the systemic circulation, leading to skeletal muscle weakness and cachexia and increasing propensity to cardiovascular, metabolic, and bone diseases, and depression.

There is an increase in circulating cytokines, including IL-1β, IL-6, IL-18, and TNFα, as well as acute-phase proteins, such as CRP and serum amyloid A. Peripheral lung inflammation may also increase the risk of developing lung cancer. There may be genetic predisposition to developing COPD in smokers, which may be shared with genetic susceptibility to comorbid diseases. Airway obstruction reduces physical activity and causes hypoxia, which may contribute to skeletal muscle weakness as well as to comorbid diseases.