Monocyte Chemoattractant protein-1 Has Prosclerotic Effects Both in a Mouse Model of Experimental Diabetes and in Vitro in Human Mesangial Cells

Diabetologia. 2008 Jan;51(1):198-207. doi: 10.1007/s00125-007-0837-3. Epub 2007 Oct 30.

Abstract

Aims/hypothesis: Diabetic nephropathy is characterised by mesangial extracellular matrix accumulation. Monocyte chemoattractant protein-1 (MCP-1), a chemokine promoting monocyte infiltration, is upregulated in the diabetic glomerulus. We performed in vitro and in vivo studies to examine whether MCP-1 may have prosclerotic actions in the setting of diabetes, presumably via its receptor, chemokine (C-C motif) receptor 2 (CCR2), which has been described in mesangial cells.

Methods: Human mesangial cells were exposed to recombinant human (rh)-MCP-1 (100 ng/ml) for 12, 24 and 48 h and to rh-MCP-1 (10, 100 and 200 ng/ml) for 24 h. Fibronectin, collagen IV and transforming growth factor, beta 1 (TGF-beta1) protein levels were measured by ELISA and pericellular polymeric fibronectin levels by western blotting. The intracellular mechanisms were investigated using specific inhibitors for CCR2, nuclear factor kappa B (NF-kappaB), p38 mitogen-activated protein kinase and protein kinase C, and an anti-TGF-beta1 blocking antibody. In both non-diabetic and streptozotocin-induced diabetic mice that were deficient or not in MCP-1, glomerular fibronectin accumulation was examined by immunohistochemistry, while cortical Tgf-beta1 (also known as Tgfb1) and fibronectin mRNA and protein levels were examined by real-time PCR and western blotting.

Results: In mesangial cells, MCP-1 binding to CCR2 induced a 2.5-fold increase in fibronectin protein levels at 24 h followed by a rise in pericellular fibronectin, whereas no changes were seen in collagen IV production. MCP-1-induced fibronectin production was TGF-beta1- and NF-kappaB-dependent. In diabetic mice, loss of MCP-1 diminished glomerular fibronectin protein production and both renal cortical Tgf-beta1 and fibronectin mRNA and protein levels.

Conclusions/interpretation: Our in vitro and in vivo findings indicate a role for the MCP-1/CCR2 system in fibronectin deposition in the diabetic glomerulus, providing a new therapeutic target for diabetic nephropathy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chemokine CCL2 / genetics*
  • Chemokine CCL2 / physiology*
  • Collagen Type IV / metabolism
  • Diabetes Mellitus, Experimental / metabolism*
  • Diabetic Nephropathies
  • Enzyme-Linked Immunosorbent Assay
  • Fibronectins / metabolism
  • Humans
  • Mesangial Cells / metabolism*
  • Mice
  • Models, Biological
  • NF-kappa B / metabolism
  • Time Factors
  • Transforming Growth Factor beta1 / metabolism
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • Chemokine CCL2
  • Collagen Type IV
  • Fibronectins
  • NF-kappa B
  • Transforming Growth Factor beta1
  • p38 Mitogen-Activated Protein Kinases