Submitted on July 12, 2007
Accepted on February 8, 2008
ANGIOPOIETIN 1 AND 2 GENE AND PROTEIN EXPRESSION IS DIFFERENTIALLY REGULATED IN ACUTE ANTI-THY 1.1 GLOMERULONEPHRITIS
Valentina Campean1, Britta Karpe2, Christian Haas3, Akram Atalla4, Harm Peters5, Harald Rupprecht6, Stefan Liebner7, Till Acker8, Karl Heinz Plate9, and Kerstin Amann1*
1 Pathology, University of Erlangen-Nurnberg, Germany
2 Pathology, University of Erlangen-Nurnberg, Erlangen, Germany
3 Cardiology, University of Tubingen, Tubingen, Germany
4 Pathologie, University of Erlangen-Nurnberg, Erlangen, Germany
5 Nephrologie, Charite, Humboldt University Berlin, Berlin, Germany
6 Internal Medicine, Klinikum Bayreuth, Bayreuth, Germany
7 Edinger Institute, University Frankfurt/Main, Germany
8 Edinger Institute, University Frankfurt/Main, Frankfurt, Germany
9 Neuropathologie, Edinger Institut, Frankfurt, Germany
* To whom correspondence should be addressed. E-mail: kerstin.amann{at}uk-erlangen.de.
Capillary neoformation is important in repair of glomerular injury of various origins. Vascular endothelial growth factor(VEGF) was shown to be crucial for glomerular capillary repair in glomerulonephritis(GN). We reasoned that other angiogenic factors are likewise involved in glomerular capillary remodeling and found angiopoietin(ANG)1 and 2 mRNA to be up-regulated in cDNA microarrays of microdissected glomeruli of anti-Thy 1.1 GN of the rat. We then studied glomerular gene and protein expression of ANG1, 2 and their receptor Tie-2 in the course of anti-Thy 1.1 GN induced by injection of OX-7 antibody. Animals were perfusion-fixed at days 6 and 12 after GN induction and compared with controls. Capillary damage and repair was quantitatively analyzed using stereological techniques. Gene and protein expression of ANG1, ANG2, their receptor Tie-2 were analyzed using real-time PCR from microdissected glomeruli, in-situ hybridization, immunofluorescence and Western Blot analysis.
Glomerular capillarisation assessed as length density was significantly lower at day6 of GN than in controls; it was back to normal values at day 12. ANG1 and ANG2 gene expression was markedly up-regulated at day 6 of the disease compared to controls. Protein expression of ANG1 and ANG2 was confined to podocytes and Tie-2 to endothelial cells. At day 12 of GN when capillary restoration was nearly completed ANG1 and 2 gene expressions returned to basal levels, whereas Tie-2 was still up.
The results indicate that likewise VEGF glomerular expression of ANG1, 2 and Tie-2 are differentially regulated and may contribute to healing and endothelial cell stabilization in experimental GN.
