TGFB1 and idiopathic pulmonary fibrosis: IL-13 levels were shown to be significantly increased in the bronchial epithelium and macrophages of patients with IPF [26], and the cytokines can activate the activator protein 1 (AP-1) transcription factor by interacting with the IL-13α2 receptor, thereby inducing the production of TGF-β in the alveolar macrophages [27].