Inducible Overexpression of sFlt-1 in Podocytes Ameliorates Glomerulopathy in Diabetic Mice

  1. Ching-Hsin Ku1,
  2. Kathryn E. White2,
  3. Alessandra Dei Cas1,
  4. Anthea Hayward1,
  5. Zoe Webster3,
  6. Rudy Bilous2,
  7. Sally Marshall2,
  8. Giancarlo Viberti1 and
  9. Luigi Gnudi1
  1. 1Cardiovascular Division, King's College London School of Medicine, Guy's Hospital, King's College London, London, U.K
  2. 2Department of Diabetes and Metabolism, School of Clinical Medical Sciences, University of Newcastle, Newcastle, U.K
  3. 3Medical Research Council, Imperial College School of Medicine, Hammersmith Hospital, Imperial College, London, U.K
  1. Corresponding author: Luigi Gnudi, luigi.gnudi{at}kcl.ac.uk

Abstract

OBJECTIVE—Podocyte-specific, doxycycline (DOX)-inducible overexpression of soluble vascular endothelial growth factor (VEGF) receptor-1 (sFlt-1) in adult mice was used to investigate the role of the VEGF-A/VEGF receptor (VEGFR) system in diabetic glomerulopathy.

RESEARCH DESIGN AND METHODS—We studied nondiabetic and diabetic transgenic mice and wild-type controls treated with vehicle (VEH) or DOX for 10 weeks. Glycemia was measured by a glucose-oxidase method and blood pressure by a noninvasive technique. sFlt-1, VEGF-A, VEGFR2, and nephrin protein expression in renal cortex were determined by Western immunoblotting; urine sFlt-1, urine free VEGF-A, and albuminuria by enzyme-linked immunosorbent assay; glomerular ultrastructure by electron microscopy; and VEGFR1 and VEGFR2 cellular localization with Immunogold techniques.

RESULTS—Nondiabetic DOX-treated transgenic mice showed a twofold increase in cortex sFlt-1 expression and a fourfold increase in sFlt-1 urine excretion (P < 0.001). Urine free VEGF-A was decreased by 50%, and cortex VEGF-A expression was upregulated by 30% (P < 0.04). VEGFR2 expression was unchanged, whereas its activation was reduced in DOX-treated transgenic mice (P < 0.02). Albuminuria and glomerular morphology were similar among groups. DOX-treated transgenic diabetic mice showed a 60% increase in 24-h urine sFlt-1 excretion and an ∼70% decrease in urine free VEGF-A compared with VEH-treated diabetic mice (P < 0.04) and had lower urine albumin excretion at 10 weeks than VEH-treated diabetic (d) mice: d-VEH vs. d-DOX, geometric mean (95% CI), 117.5 (69–199) vs. 43 (26.8–69) μg/24 h (P = 0.003). Diabetes-induced mesangial expansion, glomerular basement membrane thickening, podocyte foot-process fusion, and transforming growth factor-β1 expression were ameliorated in DOX-treated diabetic animals (P < 0.05). Diabetes-induced VEGF-A and nephrin expression were not affected in DOX-treated mice.

CONCLUSIONS—Podocyte-specific sFlt-1 overexpression ameliorates diabetic glomerular injury, implicating VEGF-A in the pathogenesis of this complication.

Footnotes

  • Published ahead of print at http://diabetes.diabetesjournals.org on 22 July 2008.

    Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. See http://creativecommons.org/licenses/by-nc-nd/3.0/ for details.

    The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

    • Accepted July 12, 2008.
    • Received May 15, 2008.
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  1. Published online before print July 22, 2008, doi: 10.2337/db08-0647 Diabetes October 2008 vol. 57 no. 10 2824-2833
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