Exacerbations: etiology and pathophysiologic mechanisms

Abstract

Some patients with COPD are prone to frequent exacerbations, which are an important determinant of health status. Such patients have elevated airway cytokine levels, suggesting the presence of increased inflammation that may increase their susceptibility to exacerbation. The inflammatory response during a COPD exacerbation is variable, but increases in interleukin-6 levels during the exacerbation are related to the presence of a common cold. Rhinovirus infection is the most important etiologic factor in COPD exacerbations and is an important target for preventive therapy. The reduction of COPD exacerbations will have an important impact on the considerable morbidity and mortality associated with COPD.

Figure 1

Top, A: induced sputum levels of IL-6 in patients who are categorized as frequent exacerbators (ie, patients who have experienced three or more exacerbations in the previous year) and in those patients who are categorized as infrequent exacerbators (ie, patients who have experienced two or fewer exacerbations in the previous year). Bottom, B: induced sputum levels of IL-8 in patients with frequent exacerbations and infrequent exacerbations. Data are expressed as medians (interquartile range). Reproduced with permission from Bhowmik et al.

Figure 2

Induced sputum IL-6 levels in the absence and presence of a natural cold. Data are expressed as medians (interquartile range). Reproduced with permission from Bhowmik et al.