Epithelial calcium-sensing receptor activation by eosinophil granule protein analog stimulates collagen matrix contraction

Pediatr Res. 2013 Apr;73(4 Pt 1):414-9. doi: 10.1038/pr.2012.198. Epub 2012 Dec 26.


Background: Eosinophils reside in normal gastrointestinal tracts and increase during disease states. Receptors for eosinophil-derived granule proteins (EDGPs) have not been identified, but highly cationic molecules, similar to eosinophil proteins, bind extracellular calcium-sensing receptors (CaSRs). We hypothesized that stimulation of CaSRs by eosinophil proteins activates epithelial cells.

Methods: Caco2 intestinal epithelial cells, AML14.3D10 eosinophils, wild-type (WT) human embryonic kidney 293 (HEK293) cells not expressing CaSRs (HEK-WT), and CaSR-transfected HEK293 cells (HEK-CaSR) were stimulated with an eosinophil protein analog poly-L-arginine (PA) and phosphorylated extracellular signal-regulated kinase (pERK)1 and pERK2 were measured. Functional activation was measured with collagen lattice contraction assays.

Results: Coculture of Caco2 cells with AML14.3D10 eosinophils augmented lattice contraction as compared with lattices containing Caco2 cells alone. PA stimulation of Caco2 lattices augmented contraction. HEK-CaSR stimulation with PA or Ca(2+) resulted in greater pERK activation than that of stimulated HEK-WT cells. PA stimulated greater HEK-CaSR lattice contraction than unstimulated lattices. Contraction of PA-stimulated and PA-unstimulated HEK-WT lattices did not differ.

Conclusion: Exposure of intestinal epithelia to the EDGP analog PA stimulates CaSR-dependent ERK phosphorylation and epithelial-mediated collagen lattice contraction. We speculate that EDGP release within the epithelial layers activates the CaSR receptor, leading to matrix contraction and tissue fibrosis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Caco-2 Cells
  • Calcium / metabolism
  • Collagen / metabolism*
  • Dose-Response Relationship, Drug
  • Enzyme Activation
  • Eosinophil Granule Proteins / pharmacology*
  • Epithelial Cells / drug effects*
  • Epithelial Cells / metabolism
  • Epithelial Cells / pathology
  • Fibrosis
  • HEK293 Cells
  • HT29 Cells
  • Humans
  • Intestinal Mucosa / drug effects*
  • Intestinal Mucosa / metabolism
  • Intestinal Mucosa / pathology
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Peptides / pharmacology*
  • Phosphorylation
  • Receptors, Calcium-Sensing / agonists*
  • Receptors, Calcium-Sensing / genetics
  • Receptors, Calcium-Sensing / metabolism
  • Time Factors
  • Transfection


  • CASR protein, human
  • Eosinophil Granule Proteins
  • Peptides
  • Receptors, Calcium-Sensing
  • polyarginine
  • Collagen
  • MAPK1 protein, human
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Calcium