The third path of tubulointerstitial fibrosis: aberrant endothelial secretome

Kidney Int. 2017 Sep;92(3):558-568. doi: 10.1016/j.kint.2017.02.033. Epub 2017 May 3.

Abstract

The secretome, defined as a portion of proteins secreted by specific cells to the extracellular space, secures a proper microenvironmental niche not only for the donor cells, but also for the neighboring cells, thus maintaining tissue homeostasis. Communication via secretory products exists between endothelial cells and fibroblasts, and this local mechanism maintains the viability and density of each compartment. Endothelial dysfunction, apart from obvious cell-autonomous defects, leads to the aberrant secretome, which predisposes fibroblasts to acquire a myofibroblastic fibrogenic phenotype. In our recent profiling of the secretome of such dysfunctional profibrogenic renal microvascular endothelial cells, we identified unique profibrogenic signatures, among which we detected ligands of Notch and Wnt-β-catenin pathways. Here, we stress the role of reprogramming cues in the immediate microenvironment of (myo)fibroblasts and the contribution of the endothelial secretome to the panoply of instructive signals in the vicinity of fibroblasts. We hope that this brief overview of endothelial-fibroblast communication in health and disease will lead to eventual unbiased proteomic mapping of individual secretomes of glomerular and tubular epithelial cells, pericytes, and podocytes through reductionist approaches to allow for the synthetic creation of a complex network of secretomic signals acting as reprogramming factors on individual cell types in the kidney. Knowledge of profibrogenic and antifibrogenic signatures in the secretome may garner future therapeutic efforts.

Keywords: endothelial cell; fibroblast; microenvironment; proteomics; reprogramming; secretome.

Publication types

  • Review

MeSH terms

  • Animals
  • Cellular Senescence
  • Endothelial Cells / metabolism
  • Endothelial Cells / pathology*
  • Epithelial-Mesenchymal Transition
  • Extracellular Space / metabolism
  • Fibrosis
  • Humans
  • Kidney Tubules / blood supply
  • Kidney Tubules / metabolism
  • Kidney Tubules / pathology*
  • Mice
  • Microvessels / cytology
  • Microvessels / metabolism
  • Microvessels / pathology*
  • Myofibroblasts / metabolism
  • Myofibroblasts / pathology*
  • Proteome / metabolism*
  • Proteomics
  • Receptors, Notch / metabolism
  • Renal Insufficiency, Chronic / metabolism
  • Renal Insufficiency, Chronic / pathology*
  • Wnt Proteins / metabolism
  • Wnt Signaling Pathway
  • beta Catenin / metabolism

Substances

  • CTNNB1 protein, human
  • Proteome
  • Receptors, Notch
  • Wnt Proteins
  • beta Catenin