Expression of RXFP1 Is Decreased in Idiopathic Pulmonary Fibrosis. Implications for Relaxin-based Therapies.
Relaxin is a hormone that has been considered as a potential therapy for patients with fibrotic diseases.



To gauge the potential efficacy of relaxin-based therapies in idiopathic pulmonary fibrosis (IPF), we studied gene expression for relaxin/insulin-like family peptide receptor 1 (RXFP1) in IPF lungs and controls.



We analyzed gene expression data obtained from the Lung Tissue Research Consortium and correlated RXFP1 gene expression data with cross-sectional clinical and demographic data. We also employed ex vivo donor and IPF lung fibroblasts to test RXFP1 expression in vitro. We tested CGEN25009, a relaxin-like peptide, in lung fibroblasts and in bleomycin injury.



We found that RXFP1 is significantly decreased in IPF. In patients with IPF, the magnitude of RXFP1 gene expression correlated directly with diffusing capacity of the lung for carbon monoxide (P < 0.0001). Significantly less RXFP1 was detected in vitro in IPF fibroblasts than in donor controls. Transforming growth factor-β decreased RXFP1 in both donor and IPF lung fibroblasts. CGEN25009 was effective at decreasing bleomycin-induced, acid-soluble collagen deposition in vivo. The relaxin-like actions of CGEN25009 were abrogated by RXFP1 silencing in vitro, and, in comparison with donor lung fibroblasts, IPF lung fibroblasts exhibited decreased sensitivity to the relaxin-like effects of CGEN25009.



IPF is characterized by the loss of RXFP1 expression. RXFP1 expression is directly associated with pulmonary function in patients with IPF. The relaxin-like effects of CGEN25009 in vitro are dependent on expression of RXFP1. Our data suggest that patients with IPF with the highest RXFP1 expression would be predicted to be most sensitive to relaxin-based therapies.
1 Dorothy P. and Richard P. Simmons Center for Interstitial Lung Disease.|2 Division of Pulmonary, Allergy, and Critical Care Medicine.
Jiangning
J
Tan
1 Dorothy P. and Richard P. Simmons Center for Interstitial Lung Disease.|2 Division of Pulmonary, Allergy, and Critical Care Medicine.
John R
JR
Tedrow
1 Dorothy P. and Richard P. Simmons Center for Interstitial Lung Disease.|2 Division of Pulmonary, Allergy, and Critical Care Medicine.
Justin A
JA
Dutta
3 Section of Pulmonary, Critical Care, and Sleep Medicine, Yale University, New Haven, Connecticut.
Brenda
B
Juan-Guardela
1 Dorothy P. and Richard P. Simmons Center for Interstitial Lung Disease.|2 Division of Pulmonary, Allergy, and Critical Care Medicine.
Mehdi
M
Nouraie
1 Dorothy P. and Richard P. Simmons Center for Interstitial Lung Disease.|2 Division of Pulmonary, Allergy, and Critical Care Medicine.
Yanxia
Y
Chu
4 Department of Pathology, and.
Humberto
H
Trejo Bittar
5 Division of Rheumatology, University of Pittsburgh, Pittsburgh, Pennsylvania; and.
Kritika
K
Ramani
5 Division of Rheumatology, University of Pittsburgh, Pittsburgh, Pennsylvania; and.
Partha S
PS
Biswas
1 Dorothy P. and Richard P. Simmons Center for Interstitial Lung Disease.|2 Division of Pulmonary, Allergy, and Critical Care Medicine.
Kristen L
KL
Veraldi
3 Section of Pulmonary, Critical Care, and Sleep Medicine, Yale University, New Haven, Connecticut.
Naftali
N
Kaminski
1 Dorothy P. and Richard P. Simmons Center for Interstitial Lung Disease.|2 Division of Pulmonary, Allergy, and Critical Care Medicine.
Yingze
Y
Zhang
1 Dorothy P. and Richard P. Simmons Center for Interstitial Lung Disease.|2 Division of Pulmonary, Allergy, and Critical Care Medicine.
Daniel J
0000-0001-6597-7830
DJ
Kass
D003430:Cross-Sectional Studies; D005260:Female; D015870:Gene Expression / Q000235:genetics; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000235:genetics* / Q000503:physiopathology / Q000628:therapy*; D015151:Immunoblotting; D008168:Lung / Q000503:physiopathology; D008297:Male; D046228:Microarray Analysis; D008875:Middle Aged; D043562:Receptors, G-Protein-Coupled / Q000235:genetics*; D018000:Receptors, Peptide / Q000235:genetics*; D012065:Relaxin / Q000627:therapeutic use*
C417543:RXFP1 protein, human; D043562:Receptors, G-Protein-Coupled; D018000:Receptors, Peptide; D012065:Relaxin
RXFP1; pulmonary fibrosis; relaxin; transforming growth factor-β