Mechanisms in COPD compared with asthma

Educational aims To discuss the similarities and differences in inflammation between chronic obstructive pulmonary disease (COPD) and asthma. To consider the clinical relevance of these differences. To speculate about the therapeutic implications of this basic research. Summary Both asthma and COPD are characterised by airway obstruction, which is variable and reversible in asthma but is progressive and largely irreversible in COPD. In both diseases, there is chronic inflammation of the respiratory tract, mediated by increased expression of multiple inflammatory proteins, including cytokines, chemokines, adhesion molecules, inflammatory enzymes and receptors. In both diseases, there are acute episodes or exacerbations, when the intensity of this inflammation increases. The similarity between these airway diseases prompted the suggestion in the 1960s that asthma and COPD are part of a spectrum of a common disease (chronic obstructive lung disease) and this came to be known as the “Dutch hypothesis”. This was countered by the “British hypothesis”, which maintained that these diseases were separate entities; the debate continues today, with evidence both for and against these two views [1, 2].