CD55 and idiopathic pulmonary fibrosis: Similarly, the systemic and local levels of the anaphylatoxins C3a and C5a were higher in patients with IPF than in normal subjects; (2) in normal primary human small airway epithelial cells (SAECs), TGF-β1 downregulated the expression of CD46, CD55, and E-cadherin and upregulated the expression of Snail, which is recognized as a marker of EMT because of its transcriptional repressor activity to CDH1 (E-cadherin gene).