Decreased expression of interleukin 13 in human lung emphysema

Abstract

Background: The overexpression of interferon (IFN)γ or interleukin (IL)-13 in the adult murine lung induces the development of changes that mirror human lung emphysema. Methods: IL-13 and IFNγ expression was determined in lung samples from five groups of patients: severe emphysema without α1-antitrypsin deficiency (SE+, n = 10); severe emphysema with α1-antitrypsin deficiency (SE-, 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 IFNγ mRNA were analysed by RT-PCR. Lung concentrations of IL-13 protein were assessed by ELISA. Results: The expression of IFNγ mRNA was similar in patients with or without emphysema. IL-13 mRNA was markedly decreased in the SE+ group compared with the SE- (p = 0.04), ME (p = 0.02), and non-emphysema 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 non-emphysematous lung, IL-13 protein was below the detection limit of the assay in most emphysemalous lung homogenates. Conclusion: The lung IL-13 content is reduced in patients with severe emphysema without α1-antitrypsin deficiency.