No abstract

a b s t r a c tEpithelial-mesenchymal transition (EMT) is associated with pulmonary fibrosis, including idiopathic pulmonary fibrosis (IPF). In this study, we investigated EMT of human pulmonary epithelial-derived cells (A549). A549 cells was either cultured by itself or co-cultured with THP-1 macrophages under normoxic (21% O 2 ) and hypoxic (2% O 2 ) conditions. We evaluated the presence of EMT by determining the expression of EMT markers, E-cadherin, vimentin, and fibronectin. To determine the role of TGF-b1 and IL-1b in EMT of the A549 cells, we analyzed the effects of blocking their activity with TGF-b1 inhibitor or IL-1b neutralizing antibody respectively. The A549 cells presented EMT when they were co-cultured with THP-1 macrophages. The EMT of the A549 cells co-cultured with THP-1 macrophages was exacerbated under hypoxia. In addition, the EMT were prevented by the addition of TGF-b1 type I receptor kinase inhibitor. The hypoxic condition increased the mRNA levels of TGF-b1 in A549 cells and THP-1 macrophages and that of IL-1b in THP-1 macrophages when each cells were co-cultured. Anti-IL-1b neutralizing antibody attenuated TGF-b1 secretion in co-culture media under hypoxic conditions. Thus, the IL-1b from THP-1 macrophages up-regulated the TGF-b1 from A549 cells and THP-1 macrophages, and then the TGF-b1 from both cells induced and promoted the EMT of A549 cells when they were co-cultured under hypoxia. Together, these results demonstrate that the interaction between type II pneumocytes and macrophages under hypoxia is necessary for the development of pulmonary fibrosis.

No abstract