Decreased expression of interleukin 13 in human lung emphysema

Background: The overexpression of interferon (IFN) gamma or interleukin (IL)-13 in the adult murine lung induces the development of changes that mirror human lung emphysema. Methods: IL-13 and IFNgamma expression was determined in lung samples from five groups of patients: severe emphysema without alpha(1)-antitrypsin deficiency (SE+, n = 10); severe emphysema with alpha(1)-antitrypsin deficiency (SE2, n = 5); mild localised emphysema ( ME, n = 8); non-emphysema smokers ( NE-S, n = 9), and non-emphysema non-smokers ( NE-NS, n = 11). Lung IL-13 and IFNgamma mRNA were analysed by RTPCR. Lung concentrations of IL-13 protein were assessed by ELISA. Results: The expression of IFNgamma mRNA was similar in patients with or without emphysema. IL-13 mRNA was markedly decreased in the SE+ group compared with the SE2 ( p = 0.04), ME ( p = 0.02), and nonemphysema groups ( p = 0.01). IL-13 mRNA correlated with forced expiratory volume in 1 second ( r = 0.5, p = 0.04) and arterial oxygen tension ( r = 0.45, p = 0.03) in emphysema patients. In contrast to the nonemphysematous lung, IL-13 protein was below the detection limit of the assay in most emphysematous lung homogenates. Conclusion: The lung IL-13 content is reduced in patients with severe emphysema without alpha(1)-antitrypsin deficiency.