Spred2-deficiency enhances the proliferation of lung epithelial cells and alleviates pulmonary fibrosis induced by bleomycin

Sci Rep. 2020 Oct 5;10(1):16490. doi: 10.1038/s41598-020-73752-3.

Abstract

The mitogen-activated protein kinase (MAPK) pathways are involved in many cellular processes, including the development of fibrosis. Here, we examined the role of Sprouty-related EVH-1-domain-containing protein (Spred) 2, a negative regulator of the MAPK-ERK pathway, in the development of bleomycin (BLM)-induced pulmonary fibrosis (PF). Compared to WT mice, Spred2-/- mice developed milder PF with increased proliferation of bronchial epithelial cells. Spred2-/- lung epithelial cells or MLE-12 cells treated with spred2 siRNA proliferated faster than control cells in vitro. Spred2-/- and WT macrophages produced similar levels of TNFα and MCP-1 in response to BLM or lipopolysaccharide and myeloid cell-specific deletion of Spred2 in mice had no effect. Spred2-/- fibroblasts proliferated faster and produced similar levels of MCP-1 compared to WT fibroblasts. Spred2 mRNA was almost exclusively detected in bronchial epithelial cells of naïve WT mice and it accumulated in approximately 50% of cells with a characteristic of Clara cells, 14 days after BLM treatment. These results suggest that Spred2 is involved in the regulation of tissue repair after BLM-induced lung injury and increased proliferation of lung bronchial cells in Spred2-/- mice may contribute to faster tissue repair. Thus, Spred2 may present a new therapeutic target for the treatment of PF.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bleomycin / pharmacology*
  • Cell Proliferation / drug effects
  • Cell Proliferation / physiology*
  • Cells, Cultured
  • Epithelial Cells / drug effects
  • Epithelial Cells / metabolism*
  • Fibroblasts / drug effects
  • Fibroblasts / metabolism
  • Lipopolysaccharides / metabolism
  • Lung / drug effects
  • Lung / metabolism*
  • MAP Kinase Signaling System / drug effects
  • MAP Kinase Signaling System / physiology
  • Macrophages / drug effects
  • Macrophages / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Myeloid Cells / drug effects
  • Myeloid Cells / metabolism
  • Pulmonary Fibrosis / chemically induced*
  • Pulmonary Fibrosis / metabolism*
  • Repressor Proteins / metabolism*
  • Tumor Necrosis Factor-alpha / metabolism

Substances

  • Lipopolysaccharides
  • Repressor Proteins
  • Spred2 protein, mouse
  • Tumor Necrosis Factor-alpha
  • Bleomycin