CXCR3A promotes the secretion of the antifibrotic decoy receptor sIL-13Rα2 by pulmonary fibroblasts

Am J Physiol Cell Physiol. 2020 Dec 1;319(6):C1059-C1069. doi: 10.1152/ajpcell.00076.2020. Epub 2020 Oct 7.

Abstract

CXC chemokine receptor 3 (CXCR3) A and its IFN-inducible ligands CXCL9 and CXCL10 regulate vascular remodeling and fibroblast motility. IL-13 is a profibrotic cytokine implicated in the pathogenesis of inflammatory and fibroproliferative conditions. Previous work from our laboratory has shown that CXCR3A is negatively regulated by IL-13 and is necessary for the basal regulation of the IL-13 receptor subunit IL-13Rα2. This study investigates the regulation of fibroblast phenotype, function, and downstream IL-13 signaling by CXCR3A in vitro. CXCR3A was overexpressed via transient transfection. CXCR3A-/- lung fibroblasts were isolated for functional analysis. Additionally, the contribution of CXCR3A to tissue remodeling following acute lung injury was assessed in vivo with wild-type (WT) and CXCR3-/- mice challenged with IL-13. CXCR3 and IL-13Rα2 displayed a reciprocal relationship after stimulation with either IL-13 or CXCR3 ligands. CXCR3A reduced expression of fibroblast activation makers, soluble collagen production, and proliferation. CXCR3A enhanced the basal expression of pERK1/2 while inducing IL-13-mediated downregulation of NF-κB-p65. CXCR3A-/- pulmonary fibroblasts were increasingly proliferative and displayed reduced contractility and α-smooth muscle actin expression. IL-13 challenge regulated expression of the CXCR3 ligands and soluble IL-13Rα2 levels in lungs and bronchoalveolar lavage fluid (BALF) of WT mice; this response was absent in CXCR3-/- mice. Alveolar macrophage accumulation and expression of genes involved in lung remodeling was increased in CXCR3-/- mice. We conclude that CXCR3A is a central antifibrotic factor in pulmonary fibroblasts, limiting fibroblast activation and reducing extracellular matrix (ECM) production. Therefore, targeting of CXCR3A may be a novel approach to regulating fibroblast activity in lung fibrosis and remodeling.

Keywords: CXCR3A; collagen; contractility; fibroblast; fibrosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3 Cells
  • Animals
  • Cell Line
  • Cell Movement / physiology
  • Cell Proliferation / physiology
  • Extracellular Matrix / metabolism*
  • Female
  • Fibroblasts / metabolism*
  • Interleukin-13 / genetics
  • Interleukin-13 / metabolism
  • Interleukin-13 Receptor alpha2 Subunit / genetics
  • Interleukin-13 Receptor alpha2 Subunit / metabolism*
  • Lung / cytology
  • Lung / metabolism
  • Macrophages, Alveolar / immunology
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Pulmonary Fibrosis / pathology*
  • Receptors, CXCR3 / metabolism*
  • Transcription Factor RelA / metabolism

Substances

  • Cxcr3 protein, mouse
  • Interleukin-13
  • Interleukin-13 Receptor alpha2 Subunit
  • Receptors, CXCR3
  • Rela protein, mouse
  • Transcription Factor RelA
  • Mapk1 protein, mouse
  • Mapk3 protein, mouse
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3