IL13 and pulmonary fibrosis: A variety of animal models of pulmonary fibrosis have been developed to study IPF human disease by administration of (a) chemical agents, e.g., bleomycin; (b) inorganic particles, e.g., asbestos, silica, and fluorescein isothiocyanate (FITC) directly into the lung; and (c) overexpression of cytokines, including TGF-β (transforming growth factor beta 1), IL-13 (interleukin-13), TNF-α (tumor necrosis factor-alpha), IL-1β (interleukin-1beta), and others, and using gene-transfer or transgenic approaches [3].