G Protein‐Coupled Receptors in Human Lung Fibroblasts: Novel Therapeutic Approaches for Idiopathic Pulmonary Fibrosis?

Abstract

Idiopathic Pulmonary Fibrosis (IPF) is a progressive, often fatal interstitial lung disease and thus in need of new, effective therapies. A feature of IPF is fibroblast‐to‐myofibroblast transition and resultant increased deposition of extracellular matrix (ECM) proteins, which can lead to loss of functional lung tissue. Previous studies have shown that increases in cyclic AMP (cAMP) can decrease the number and function of myofibroblasts. Cellular synthesis of cAMP is mediated by adenylyl cyclase, the activity of which is regulated by G‐protein signaling and G‐protein coupled receptors (GPCRs). We hypothesized that alteration in GPCR expression in lung fibroblasts from IPF patients may identify new therapeutic targets for lung fibrosis. Using RNA‐seq, we have identified and quantified GPCRs of lung fibroblasts isolated from six IPF patients and six controls grown in low passage primary cultures. RNA‐seq analysis revealed the expression of ~120 GPCRs (of ~380 endoGPCRs [regulated by endogenous ligands]). On average ~20 highly expressed GPCR were detected in all samples, with small differences in biological replicates; these may be “housekeeping” GPCRs. We also identified a group of GPCRs with highly variable expression and found that lung fibroblasts from IPF patients selectively expressed a subset of GPCRs. To assess changes in GPCR expression during fibroblast‐to‐myofibroblast transition, we treated fibroblasts with TGFβ1 (10 ng/ml, 48 hrs or 20 ng/ml, 16 hrs). As expected, TGFβ1 treatment increased the expression of pro‐fibrotic markers (e.g., collagens Iα1, Iα2, III; α‐smooth muscle actin; plasminogen activator inhibitor‐1). In addition, TGFβ1 altered (increased or decreased) the expression of numerous GPCRs. TGFβ1 treatment of control fibroblasts did not fully mimic the GPCR expression changes of fibroblasts from IPF patients. We conclude that GPCR expression (GPCRomic) analysis identifies GPCRs that may contribute to the fibrotic state in the lung and thus, may be novel therapeutic targets for lung fibrosis.Support or Funding InformationSupported by NIH T32 HL 098062‐04, Bristol Myers Squibb and CIHR 201403MOP‐RS‐323925.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.