Epithelial–mesenchymal transition of A549 cells is enhanced by co-cultured with THP-1 macrophages under hypoxic conditions

• Published in: Biochemical and biophysical research communications 2014-10, Vol.453 (4), p.804-809
• Main Authors: Sueki, Akane, Matsuda, Kazuyuki, Iwashita, Chinami, Taira, Chiaki, Ishimine, Nau, Shigeto, Shohei, Kawasaki, Kenji, Sugano, Mitsutoshi, Yamamoto, Hiroshi, Honda, Takayuki
• Format: Article
• Language: English
• Subjects: Cell Hypoxia - immunology; Cell Line; Coculture Techniques - methods; Cytokines - immunology; Epithelial-Mesenchymal Transition - immunology; Epithelial–mesenchymal transition; Humans; Hypoxia; Idiopathic pulmonary fibrosis; Macrophages; Macrophages - cytology; Macrophages - immunology; Respiratory Mucosa - cytology; Respiratory Mucosa - immunology; Type II pneumocytes
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2014.10.022

•Hypoxia promoted EMT of A549 cells co-cultured with THP-1 macrophages.•TGF-β1 was required to induce EMT of A549 cells under hypoxia.•Hypoxia increased the expression of IL-1β in THP-1 macrophages.•IL-1β increased TGF-β1 from THP-1 macrophages and A549 cells.•TGF-β1 from THP-1 macrophages and A549 cells promoted the EMT of A549 cells. Epithelial–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% O2) and hypoxic (2% O2) 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-β1 and IL-1β in EMT of the A549 cells, we analyzed the effects of blocking their activity with TGF-β1 inhibitor or IL-1β 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-β1 type I receptor kinase inhibitor. The hypoxic condition increased the mRNA levels of TGF-β1 in A549 cells and THP-1 macrophages and that of IL-1β in THP-1 macrophages when each cells were co-cultured. Anti-IL-1β neutralizing antibody attenuated TGF-β1 secretion in co-culture media under hypoxic conditions. Thus, the IL-1β from THP-1 macrophages up-regulated the TGF-β1 from A549 cells and THP-1 macrophages, and then the TGF-β1 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.