Danahay et al. treated ALI HBECs with IL-13 or IL-4, resulting in changes in permeability, suggesting that these asthma-related cytokines may contribute to a more secretory phenotype [15], whilst Wadsworth and colleagues found that addition of IL-13 and other TH2 cytokines led to increased MMP7 and FasL release, which may lead to epithelial damage and inflammation [16]. This evidence concerns the gene IL13 and asthma.