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Inducible overexpression of sFlt-1 in podocytes ameliorates glomerulopathy in diabetic mice.

Ku CH, White KE, Dei Cas A, Hayward A, Webster Z, Bilous R, Marshall S, Viberti G, Gnudi L - Diabetes (2008)

Bottom Line: Urine free VEGF-A was decreased by 50%, and cortex VEGF-A expression was upregulated by 30% (P < 0.04).Diabetes-induced mesangial expansion, glomerular basement membrane thickening, podocyte foot-process fusion, and transforming growth factor-beta1 expression were ameliorated in DOX-treated diabetic animals (P < 0.05).Podocyte-specific sFlt-1 overexpression ameliorates diabetic glomerular injury, implicating VEGF-A in the pathogenesis of this complication.

View Article: PubMed Central - PubMed

Affiliation: Cardiovascular Division, King's College London School of Medicine, Guy's Hospital, King's College London, London, 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 approximately 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) mug/24 h (P = 0.003). Diabetes-induced mesangial expansion, glomerular basement membrane thickening, podocyte foot-process fusion, and transforming growth factor-beta1 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.

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Related in: MedlinePlus

Expression of VEGFR1 and VEGFR2 in mouse glomerular cells. Representative transmission electron microscopy images of VEGFR2 (A), VEGFR1 (B), and negative control (C). Immunogold staining (arrows on black dots) in mouse glomerular capillaries. Positive Immunogold staining is seen, as expected, in endothelial cells (EC) (A and B) and, for the first time, for VEGFR2 in podocyte cell body (P) and foot processes (Pfp) (A). Scale bars represent 0.5 μm.
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f3: Expression of VEGFR1 and VEGFR2 in mouse glomerular cells. Representative transmission electron microscopy images of VEGFR2 (A), VEGFR1 (B), and negative control (C). Immunogold staining (arrows on black dots) in mouse glomerular capillaries. Positive Immunogold staining is seen, as expected, in endothelial cells (EC) (A and B) and, for the first time, for VEGFR2 in podocyte cell body (P) and foot processes (Pfp) (A). Scale bars represent 0.5 μm.

Mentions: Immunogold staining showed localization of VEGFR1 and VEGFR2 in endothelial cells as previously reported. We detected expression of VEGFR2, but not VEGFR1, in podocyte cell body and foot processes in vivo (Fig. 3).


Inducible overexpression of sFlt-1 in podocytes ameliorates glomerulopathy in diabetic mice.

Ku CH, White KE, Dei Cas A, Hayward A, Webster Z, Bilous R, Marshall S, Viberti G, Gnudi L - Diabetes (2008)

Expression of VEGFR1 and VEGFR2 in mouse glomerular cells. Representative transmission electron microscopy images of VEGFR2 (A), VEGFR1 (B), and negative control (C). Immunogold staining (arrows on black dots) in mouse glomerular capillaries. Positive Immunogold staining is seen, as expected, in endothelial cells (EC) (A and B) and, for the first time, for VEGFR2 in podocyte cell body (P) and foot processes (Pfp) (A). Scale bars represent 0.5 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2551695&req=5

f3: Expression of VEGFR1 and VEGFR2 in mouse glomerular cells. Representative transmission electron microscopy images of VEGFR2 (A), VEGFR1 (B), and negative control (C). Immunogold staining (arrows on black dots) in mouse glomerular capillaries. Positive Immunogold staining is seen, as expected, in endothelial cells (EC) (A and B) and, for the first time, for VEGFR2 in podocyte cell body (P) and foot processes (Pfp) (A). Scale bars represent 0.5 μm.
Mentions: Immunogold staining showed localization of VEGFR1 and VEGFR2 in endothelial cells as previously reported. We detected expression of VEGFR2, but not VEGFR1, in podocyte cell body and foot processes in vivo (Fig. 3).

Bottom Line: Urine free VEGF-A was decreased by 50%, and cortex VEGF-A expression was upregulated by 30% (P < 0.04).Diabetes-induced mesangial expansion, glomerular basement membrane thickening, podocyte foot-process fusion, and transforming growth factor-beta1 expression were ameliorated in DOX-treated diabetic animals (P < 0.05).Podocyte-specific sFlt-1 overexpression ameliorates diabetic glomerular injury, implicating VEGF-A in the pathogenesis of this complication.

View Article: PubMed Central - PubMed

Affiliation: Cardiovascular Division, King's College London School of Medicine, Guy's Hospital, King's College London, London, 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 approximately 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) mug/24 h (P = 0.003). Diabetes-induced mesangial expansion, glomerular basement membrane thickening, podocyte foot-process fusion, and transforming growth factor-beta1 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.

Show MeSH
Related in: MedlinePlus