title: Pirfenidone exerts a suppressive effect on CCL18 expression in U937-derived macrophages partly by inhibiting STAT6 phosphorylation.
abstract: BACKGROUND
  CC chemokine ligand 18 (CCL18) is suggested to play a role in the development of pulmonary fibrosis. Macrophages are thought to be the main source of CCL18, and the effect of pirfenidone, an anti-fibrotic agent for idiopathic pulmonary fibrosis, on the expression of CCL18 in macrophages warrants investigation.
  
  
  OBJECTIVE
  The purpose of this study was to investigate the effect of pirfenidone on the expression of CCL18 in macrophages.
  
  
  METHODS
  U937 cells were differentiated into macrophages by phorbol myristate acetate and then stimulated with recombinant IL-4 to induce the production of CCL18. The cells were treated with pirfenidone, and the mRNA and protein levels for CCL18 were measured by a reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. The effects of pirfenidone on the IL-4 receptor (IL-4R) expression and STAT6 activation were investigated and on the JAK kinase activity were measured using the Z'-LYTE™ kinase assay.
  
  
  RESULTS
  Pirfenidone significantly suppressed the expression of CCL18 when the cells were treated with concentrations of 50-250 μg/mL. Pirfenidone did not affect the expression of the IL-4R components. The selective STAT6 inhibitor AS1517499 suppressed CCL18 expression. Both AS1517499 and pirfenidone suppressed STAT6 phosphorylation (p < .05), although the effect of pirfenidone was less marked than that of AS1517499. The Z'-LYTE™ kinase assay showed a reduction in the activities of JAK1, JAK3 and TYK2 by pirfenidone.
  
  
  CONCLUSIONS
  Pirfenidone suppresses CCL18 expression in macrophages and this effect is thought to be attributed partly to the inhibition of STAT6 phosphorylation.
authors: a Department of Pulmonary Medicine and Oncology , Graduate School of Medicine, Nippon Medical School , Tokyo , Japan.
authors: Yoshinobu
authors: Y
authors: Saito
authors: a Department of Pulmonary Medicine and Oncology , Graduate School of Medicine, Nippon Medical School , Tokyo , Japan.
authors: Arata
authors: A
authors: Azuma
authors: a Department of Pulmonary Medicine and Oncology , Graduate School of Medicine, Nippon Medical School , Tokyo , Japan.
authors: Kuniko
authors: K
authors: Matsuda
authors: a Department of Pulmonary Medicine and Oncology , Graduate School of Medicine, Nippon Medical School , Tokyo , Japan.
authors: Koichiro
authors: K
authors: Kamio
authors: a Department of Pulmonary Medicine and Oncology , Graduate School of Medicine, Nippon Medical School , Tokyo , Japan.
authors: Shinji
authors: S
authors: Abe
authors: a Department of Pulmonary Medicine and Oncology , Graduate School of Medicine, Nippon Medical School , Tokyo , Japan.
authors: Akihiko
authors: A
authors: Gemma
keywords: CCL18; Pulmonary fibrosis; STAT6; macrophage; pirfenidone