Furthermore the rising stiffness of lung parenchyma increases the expression of TGF-β and HIF-1α in ECs which are necessary for the formation of PF (Kato et al. 2018; Bryant et al. 2016).The mechanical stress poses on endothelial cells exists not only in the early stages but also persist with disease progression. This evidence concerns the gene TGFB1 and pemphigus foliaceus.