gms | German Medical Science

24. Jahrestagung der Deutschen Gesellschaft für Arterioskleroseforschung

Deutsche Gesellschaft für Arterioskleroseforschung

18.03. - 20.03.2010, Blaubeuren

The VEGF/VEGF receptor system in atherosclerosis and in a vascular organ culture model

Meeting Contribution

  • L. Mey - Department of Laboratory Medicine and Pathobiochemistry, Molecular Diagnostics, Philipps-University, Marburg, Germany
  • C. Löwer - Department of Laboratory Medicine and Pathobiochemistry, Molecular Diagnostics, Philipps-University, Marburg, Germany
  • Z. Kharip - Department of Laboratory Medicine and Pathobiochemistry, Molecular Diagnostics, Philipps-University, Marburg, Germany
  • A. Hildenberg - Department of Laboratory Medicine and Pathobiochemistry, Molecular Diagnostics, Philipps-University, Marburg, Germany
  • K. Nemeth - Department of Laboratory Medicine and Pathobiochemistry, Molecular Diagnostics, Philipps-University, Marburg, Germany
  • H. Renz - Department of Laboratory Medicine and Pathobiochemistry, Molecular Diagnostics, Philipps-University, Marburg, Germany
  • corresponding author N. Al-Fakhri - Department of Laboratory Medicine and Pathobiochemistry, Molecular Diagnostics, Philipps-University, Marburg, Germany

Deutsche Gesellschaft für Arterioskleroseforschung e.V.. 24. Jahrestagung der Deutschen Gesellschaft für Arterioskleroseforschung. Blaubeuren, 18.-20.03.2010. Düsseldorf: German Medical Science GMS Publishing House; 2011. Doc10dgaf14

DOI: 10.3205/10dgaf14, URN: urn:nbn:de:0183-10dgaf142

Veröffentlicht: 23. März 2011

© 2011 Mey et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielfältigt, verbreitet und öffentlich zugänglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Abstract

Vascular Endothelial Growth Factor (VEGF) regulates the expression of the caspase-dependent mediator poly(ADP-ribose)-polymerase (PARP), as demonstrated in our previous work. In the present study, we aimed at investigating the receptors involved in the anti-apoptotic signaling of VEGF in endothelial cells.VEGFR-1, VEGFR-2 and neuropilin-1 (NP-1) were analyzed by fluorescence microscopy. The in vivo effects of VEGF were analyzed in an arterial and venous organ culture model. VEGFR-2 was demonstrated to be expressed on the cell surface of endothelial cells together with NP-1. NP-1 acted as a co-receptor. VEGF exerts its anti-apoptotic effect via VEGFR-2 and NP-1 and regulates the anti-apoptotic protein PARP. In atherosclerosis, VEGF acts as an anti-apoptotic factor protecting the integrity of the endothelium and inhibiting neointima development and progression.


Introduction

In a previous work we have shown that VEGF has an anti-apoptotic effect via Akt and JNK-dependent signaling pathways and the regulation of poly(ADP-ribose) Polymerase-1 [1]. But the role of VEGF receptors in the endothelium has been poorly defined. The aim of this study was to investigate the expression and distribution of the receptors VEGF-R1, VEGF-R2 and the coreceptor neuropilin-1 (NP-1) in atherosclerosis and in a vascular organ culture model.


Material and methods

Human artery specimens: 25 specimens of atherosclerotic carotid, and femoral arteries, 10 normal vessels, and preparations in organ culture models of internal thoracic artery and the saphenous vein were studied. After surgical removal of about 2 cm long vessels, segments with 2–3 mm in diameter were prepared, incubated for 10 days with 10% serum and cultured with or without VEGF (10 ng/ml). Cryosections of 6µm thickness were prepared. By immunohistochemical and immunofluorescence microscopy (data not shown) VEGF-R1, VEGF-R2, NP-1 and von Willebrand factor (vWF) were demonstrated. Human endothelial cells (EC) derived from the cell line EA.hy926 were cultured on vitronectin coated coverslips (2 µg/ml) and incubated with 10 ng/ml VEGF. Subsequently the VEGF receptors VEGFR-1, VEGFR-2 and NP-1 were detected by immunofluorescence microscopy.


Results

In the organ culture model no change of intimal hyperplasia resulted from VEGF supplementation compared to sole incubation with medium and 10% serum (Figure 1 [Fig. 1]). A change in expression of VEGF-R2 and NP-1 by VEGF was determined by immunohistochemistry in the internal thoracic artery model. VEGF-R1 was not detectable (Figure 2 [Fig. 2]). In the culture model of the great saphenous vein (Figure 2 [Fig. 2]) a higher expression of VEGF-R2 was demonstrated. Neither NP-1 nor VEGF-R1 could be verified by immunohistochemistry or immuno-fluorescence microscopy (data not shown) in the organ culture model of the saphenous vein [2].

By immunohistochemistry of atherosclerotic specimens, an increased expression of VEGF-R2 and NP-1 is established as compared to normal vessels (data not shown). VEGFR-2 and NP-1 showed an increased density by VEGF stimulation, also a VEGF induced receptor clustering and endocytosis could be demonstrated by immunofluorescence (Figure 3 [Fig. 3]). The VEGF-R1, however, only showed low expression on EC [3].


Discussion

The growth factor VEGF is the strongest stimulator of proliferation and a natural apoptosis inhibitor for EC [4]. In atherosclerosis increased VEGF plasma levels and an increased local production were demonstrated [5]. The endothelial VEGF receptors VEGF-R2 and NP-1 could be detected in the organ culture models and in EC, increased in number and density by VEGF supplementation. In EC cultures, the two VEGF receptors are colocalized. Atherosclerotic arteries also showed an increase in expression of VEGFR-2 and NP-1. VEGFR-1 was not detected, as expected. The results suggest the involvement of the VEGF-receptor system in the anti-apoptotic effect of VEGF on the human endothelium.


References

1.
Hörmann, et al. Vascular endothelial growth factor promotes endothelial survival by induction of poly(ADP-ribose)-polymerase expression in the human vasculature. J Thromb Haemost. 2010.
2.
Herzog Y, Kalcheim C, Kahane N, Reshef R, Neufeld G. Differential expression of neuropilin-1 and neuropilin-2 in arteries and veins. Mech Dev. 2001;109(1):115-9.
3.
Vogel C, et al. Flt-1, but not Flk-1 mediates hyperpermeability through activation of the PI3-K/Akt pathway. J Cell Physiol. 2007;212:236–43. DOI: 10.1002/jcp.21022 Externer Link
4.
Zachary I. Signaling mechanisms mediating vascular protective actions of vascular endothelial growth factor. Am J Physiology, Cell Physiology. 2001;280:C1375–C86.
5.
Spence GM, et al. Vascular endothelial growth factor levels in serum and plasma following esophageal cancer resection-relationship to platelet count. Int J Biol Markers. 2002;17(2):119-24.