Impaired pericyte recruitment and abnormal retinal angiogenesis as a result of angiopoietin-2 overexpression

Yuxi Feng; Franziska vom Hagen; Frederick Pfister; Snezana Djokic; Sigrid Hoffmann; Walter Back; Patrick Wagner; Jihong Lin; Urban Deutsch; Hans-Peter Hammes

doi:10.1160/TH06-05-0277

Thrombosis and Haemostasis, Table of Contents

Thromb Haemost 2007; 97(01): 99-108
DOI: 10.1160/TH06-05-0277

Endothelium and Vascular Development

Schattauer GmbH

Impaired pericyte recruitment and abnormal retinal angiogenesis as a result of angiopoietin-2 overexpression

Authors

Yuxi Feng

¹5^th Medical Clinic, Faculty of Clinical Medicine, University of Heidelberg, Mannheim, Germany
Franziska vom Hagen

¹5^th Medical Clinic, Faculty of Clinical Medicine, University of Heidelberg, Mannheim, Germany
Frederick Pfister

¹5^th Medical Clinic, Faculty of Clinical Medicine, University of Heidelberg, Mannheim, Germany
Snezana Djokic

¹5^th Medical Clinic, Faculty of Clinical Medicine, University of Heidelberg, Mannheim, Germany
Sigrid Hoffmann

²Medical Research Center, Faculty of Clinical Medicine, University of Heidelberg, Mannheim, Germany
Walter Back

³Institute of Pathology, Faculty of Clinical Medicine, University of Heidelberg, Mannheim, Germany
Patrick Wagner

⁴Max-Planck-Institute for Physiological and Clinical Research, Bad Nauheim, Germany
Jihong Lin

¹5^th Medical Clinic, Faculty of Clinical Medicine, University of Heidelberg, Mannheim, Germany
Urban Deutsch

⁴Max-Planck-Institute for Physiological and Clinical Research, Bad Nauheim, Germany

⁵Max-Planck-Institute for Vascular Biology, c/o Institute of Cell Biology, ZMBE, University of Muenster, Muenster, Germany and Theodor Kocher Institute, University of Berne, Berne, Switzerland
Hans-Peter Hammes

¹5^th Medical Clinic, Faculty of Clinical Medicine, University of Heidelberg, Mannheim, Germany

Abstract

Summary

Angiopoietin-2 (Ang2) is among the relevant growth factors induced by hypoxia and plays an important role in the initiation of retinal neovascularizations. Ang2 is also involved in incipient diabetic retinopathy, as it may cause pericyte loss. To investigate the impact of Ang2 on developmental and hypoxia-induced angiogenesis, we used a transgenic mouse line overexpressing human Ang2 in the mouse retina. Transgenic mice displayed a reduced coverage of capillaries with pericytes (-14 %; p<0.01) and a 46% increase of vascular density of the capillary network at postnatal day 10 compared to wild type mice. In the model of oxygen-induced retinopathy (OIR), Ang2 overexpression resulted in enhanced preretinal (+103%) and intraretinal neovascularization (+29%). Newly formed intraretinal vessels in OIR were also pericyte-deficient (-26 %; p<0.01). The total expression of Ang2 in transgenic mice was seven-fold, compared with wild type controls. Ang2 modulated expression of genes encoding VEGF (+65%) and Ang1 (+79%) in transgenic animals. These data suggest that Ang2 is involved in pericyte recruitment, and modulates intraretinal, and preretinal vessel formation in the eye under physiological and pathological conditions.

Keywords

Angiopoietin-2 - pericyte - angiogenesis - hypoxia - neovascularization

Full Text

References

References
1 Kahn HA, Hiller R. Blindness caused by diabetic retinopathy. Am J Ophthalmol 1974; 78: 58-67.
2 Moss SE. et al Ten-year incidence of visual loss in a diabetic population. Ophthalmology 1994; 101: 1061-70.
3 Thylefors B. et al Global data on blindness. Bull World Health Organ 1995; 73: 115-21.
4 Smith LE. et al Oxygen-induced retinopathy in the mouse. Invest Ophthalmol Vis Sci 1994; 35: 101-11.
5 Pierce EA. et al Vascular endothelial growth factor/ vascular permeability factor expression in a mouse model of retinal neovascularization. Proc Natl Acad Sci U S A 1995; 92: 905-9.
6 Miller JW. et al Vascular endothelial growth factor in ocular neovascularization and proliferative diabetic retinopathy. Diabetes Metab Rev 1997; 13: 37-50.
7 Shweiki D. et al Vascular endothelial growth factor induced by hypoxia may mediate hypoxia-initiated angiogenesis. Nature 1992; 359: 843-5.
8 Levy AP. et al Transcriptional regulation of the rat vascular endothelial growth factor gene by hypoxia. J Biol Chem 1995; 270: 13333-40.
9 Aiello LP. et al Hypoxic regulation of vascular endothelial growth factor in retinal cells. Arch Ophthalmol 1995; 113: 1538-44.
10 Aiello LP. et al Suppression of retinal neovascularization in vivo by inhibition of vascular endothelial growth factor (VEGF) using soluble VEGF-receptor chimeric proteins. Proc Natl Acad Sci USA 1995; 92: 10457-61.
11 Ozaki H. et al Blockade of vascular endothelial cell growth factor receptor signaling is sufficient to completely prevent retinal neovascularization. Am J Pathol 2000; 156: 697-707.
12 Maisonpierre PC. et al Angiopoietin-2, a natural antagonist for Tie2 that disrupts in vivo angiogenesis. Science 1997; 277: 55-60.
13 Thurston G. et al. Angiopoietin-1 protects the adult vasculature against plasma leakage. Nat Med 20006 460-3.
14 Lobov IB. et al Angiopoietin-2 displays VEGF-dependent modulation of capillary structure and endothelial cell survival in vivo. Proc Natl Acad Sci USA 2002; 99: 11205-10.
15 Hammes HP. et al Angiopoietin-2 causes pericyte dropout in the normal retina: evidence for involvement in diabetic retinopathy. Diabetes 2004; 53: 1104-10.
16 Sato TN. et al Distinct roles of the receptor tyrosine kinases Tie-1 and Tie-2 in blood vessel formation. Nature 1995; 376: 70-74.
17 Suri C. et al Requisite role of angiopoietin-1, a ligand for the TIE2 receptor, during embryonic angiogenesis. Cell 1996; 87: 1171-80.
18 Thurston G. et al Leakage-resistant blood vessels in mice transgenically overexpressing angiopoietin-1. Science 1999; 286: 2511-4.
19 Takagi H. et al Potential role of the angiopoietin/ tie2 system in ischemia-induced retinal neovascularization. Invest Ophthalmol Vis Sci 2003; 44: 393-402.
20 Pichiule P. et al Hypoxic regulation of angiopoietin-2 expression in endothelial cells. J Biol Chem 2004; 279: 12171-80.
21 Jain R. Molecular regulation of vessel maturation. Nat Med 2003; 9: 685-93.
22 Hanahan D. Signaling vascular morphogenesis and maintenance. Science 1997; 277: 48-50.
23 Holash J. et al New model of tumor angiogenesis: dynamic balance between vessel regression and growth mediated by angiopoietins and VEGF. Oncogene 1999; 18: 5356-62.
24 Carmeliet P. Angiogenesis in health and disease. Nat Med 2003; 9: 653-60.
25 Gale NW. et al Angiopoietin-2 is required for postnatal angiogenesis and lymphatic patterning, and only the latter role is rescued by angiopoietin-1. Dev Cell 2002; 3: 411-23.
26 Oh H. et al Hypoxia and vascular endothelial growth factor selectively up-regulate angiopoietin-2 in bovine microvascular endothelial cells. J Biol Chem 1999; 274: 15732-9.
27 Hackett SF. et al Angiopoietin 2 expression in the retina: upregulation during physiologic and pathologic neovascularization. J Cell Physiol 2000; 184: 275-84.
28 Hackett SF. et al Angiopoietin-2 plays an important role in retinal angiogenesis. J Cell Physiol 2002; 192: 182-7.
29 Park YS. et al Hypoxia and vascular endothelial growth factor acutely up-regulate angiopoietin-1 and Tie2 mRNA in bovine retinal pericytes. Microvasc Res 2003; 65: 125-31.
30 Matsumara T. et al Hyperglycemia increases angiopoietin-2 expression in retinal Muller cells through through superoxide-induced overproduction of a-oxoaldehyde age precursors. Diabetes 2000; 49 (Suppl. 01) A55 (Abstract)
31 Oshima Y. et al Different effects of angiopoietin-2 in different vascular beds: new vessels are most sensitive. FASEB J 2005; 19: 963-5.
32 Tidhar A. et al A novel transgenic marker for migrating limb muscle precursors and for vascular smooth muscle cells. Dev Dyn 2001; 220: 60-73.
33 Hammes HP. et al Subcutaneous injection of a cyclic peptide antagonist of vitronectin receptor-type integrins inhibits retinal neovascularization. Nat Med 1996; 2: 529-33.
34 Gardiner TA. et al Inhibition of tumor necrosis factor-alpha improves physiological angiogenesis and reduces pathological neovascularization in ischemic retinopathy. Am J Pathol 2005; 166: 637-44.
35 Gerhardt H. et al VEGF guides angiogenic sprouting utilizing endothelial tip cell filopodia. J Cell Biol 2003; 161: 1163-77.
36 Das A. et al Angiopoietin/Tek interactions regulate mmp-9 expression and retinal neovascularization. Lab Invest 2003; 83: 1637-45.
37 Daly C. et al Angiopoietin-1 modulates endothelial cell function and gene expression via the transcription factor FKHR (FOXO1). Genes Dev 2004; 18: 1060-71.
38 Potente M. et al Involvement of Foxo transcription factors in angiogenesis and postnatal neovascularization. J Clin Invest 2005; 115: 2382-92.
39 Furuyama T. et al Abnormal angiogenesis in Foxo1 (Fkhr)-deficient mice. J Biol Chem 2004; 279: 34741-9.
40 Armulik A. et al Endothelial/pericyte interactions. Circ Res 2005; 97: 512-23.
41 Iivanainen E. et al Angiopoietin-regulated recruitment of vascular smooth muscle cells by endothelialderived heparin binding EGF-like growth factor. FASEB J 2003; 17: 1609-21.
42 Hammes HP. et al Pericytes and the pathogenesis of diabetic retinopathy. Diabetes 2002; 51: 3107-12.
43 Hoffmann J. et al Endothelial survival factors and spatial completion, but not pericyte coverage of retinal capillaries, determine vessel plasticity. FASEB J 2005; 19: 2035-6.
44 Kim I. et al Angiopoietin-2 at high concentration can enhance endothelial cell survival through the phosphatidylinositol 3’-kinase/Akt signal transduction pathway. Oncogene 2000; 19: 4549-52.