Sphingosine-1-phosphate is increased in patients with idiopathic pulmonary fibrosis and mediates epithelial to mesenchymal transition
- Javier Milara1,2,3,
- Rafael Navarro4,
- Gustavo Juan5,
- Teresa Peiró6,
- Adela Serrano1,
- Mercedes Ramón4,
- Esteban Morcillo3,5,
- Julio Cortijo1,3,5
- 1Research foundation, University General Hospital Consortium, Valencia, Spain
- 2Department of Biotechnology, Universidad Politécnica de Valencia, Valencia, Spain
- 3CIBERES, Health Institute Carlos III, Valencia, Spain
- 4Respiratory Unit, University General Hospital Consortium, Valencia, Spain
- 5Department of Medicine, Faculty of Medicine, University of Valencia, Valencia, Spain
- 6Department of Pharmacology, Faculty of Medicine, University of Valencia, Valencia, Spain
- Correspondence to Dr Javier Milara, Unidad de Investigación, Consorcio, Hospital General Universitario, Avenida tres cruces s/n, E-46014 Valencia, Spain; xmilara{at}hotmail.com
-
Contributors Javier Milara: contributed to immunohistochemistry analysis and drafting the original manuscript, and contributed to and approved the final manuscript. Rafa Navarro: contributed to supervising clinical characterisation, coordinating the bronchoalveolar lavage sampling and analysis, and contributed to and approved the final manuscript. Gustavo Juan: contributed to supervising clinical characterization, coordinating the bronchoalveolar lavage sampling and analysis, and contributed to and approved the final manuscript. Teresa Peiró: contributed to undertaking laboratory characterization of patients, protein array and ELISAs, and contributed to and approved the final manuscript. Adela Serrano: contributed to undertaking laboratory characterization of patients, western blot real-time PCR and ELISAs, and contributed to and approved the final manuscript. Mercedes Ramon: contributed to supervising clinical characterization, coordinating the bronchoalveolar lavage sampling and analysis, and contributed to and approved the final manuscript. Esteban Morcillo: contributed to conception of the project design and contributed to and approved the final manuscript. Julio Cortijo: contributed to conception of the project design and contributed to and approved the final manuscript.
- Received 15 February 2011
- Accepted 20 October 2011
- Published Online First 21 November 2011
Abstract
Background Idiopathic pulmonary fibrosis (IPF) is characterised by the aberrant epithelial to mesenchymal transition (EMT) and myofibroblast accumulation. Sphingosine-1-phosphate (S1P) and sphingosine kinase 1 (SPHK1) have been implicated in lung myofibroblast transition, but their role in EMT and their expression in patients with IPF is unknown.
Methods and results S1P levels were measured in serum (n=27) and bronchoalveolar lavage (BAL; n=15) from patients with IPF and controls (n=30 for serum and n=15 for BAL studies). SPHK1 expression was measured in lung tissue from patients with IPF (n=12) and controls (n=15). Alveolar type II transformation into mesenchymal cells was studied in response to S1P (10−9–10−5 M). The median (IQR) of S1P serum levels was increased in patients with IPF (1.4 (0.4) μM) versus controls (1 (0.26) μM; p<0.0001). BAL S1P levels were increased in patients with IPF (1.12 (0.53) μM) versus controls (0.2 (0.5); p<0.0001) and correlated with diffusion capacity of the lung for carbon monoxide, forced expiratory volume in 1 s and forced vital capacity (Spearman's r=−0.87, −0.72 and −0.68, respectively) in patients with IPF. SPHK1 was upregulated in lung tissue from patients with IPF and correlated with α-smooth muscle actin, vimentin and collagen type I (Spearman's r=0.82, 0.85 and 0.72, respectively). S1P induced EMT in alveolar type II cells by interacting with S1P2 and S1P3, as well as by the activation of p-Smad3, RhoA-GTP, oxidative stress and transforming growth factor-β1 (TGF-β1) release. Furthermore, TGF-β1-induced EMT was partially conducted by the S1P/SPHK1 activation, suggesting crosstalk between TGF-β1 and the S1P/SPHK1 axis.
Conclusions S1P is elevated in patients with IPF, correlates with the lung function and mediates EMT.
- Sphingosine-1-phosphate
- sphingosine kinase 1
- epithelial to mesenchymal transition
- idiopathic pulmonary fibrosis
- airway epithelium
- interstitial fibrosis
- oxidative stress
Footnotes
-
Funding This work was supported by grants SAF2008-03113 (JC), SAF2009-08913 (EJM), CIBERES (CB06/06/0027) from the Ministry of Science and Innovation and the Health Institute ‘Carlos III’ of the Spanish government, and research grants (Prometeo/2008/045 and Emerging Groups GE-029/10) from the regional government (‘Generalitat Valenciana’) and the Valencian Society of Pneumology.
-
Competing interests None.
-
Patient consent Obtained.
-
Ethics approval This study has been approved by the ethics committee of the University General Hospital of Valencia, Spain.
-
Provenance and peer review Not commissioned; externally peer-reviewed.
