Damaged AECs produces many kinds of profibrotic mediators, such as transforming growth factor beta 1 (TGF-β1), connective tissue growth factor (CTGF), platelet-derived growth factor (PDFG), etc., that promote a profibrotic microenvironment in the lungs of IPF patients. This evidence concerns the gene TGFB1 and idiopathic interstitial pneumonia.