Paracrine modulation of CXCR4 by IGF-1 and VEGF: implications for choroidal neovascularization.
OBJECTIVE
Modulators of angiogenesis typically work in an orchestrated manner. The authors examined the interaction between insulinlike growth factor (IGF)-1, vascular endothelial growth factor (VEGF), and stromal derived factor (SDF)-1 in vivo and in vitro using angiogenesis models.


METHODS
The angiogenic effect of SDF-1, alone or in combination with IGF-1 and VEGF, was assessed in human lung microvascular endothelial cells using capillary tube formation and thymidine incorporation. Immunohistochemical analysis for CD31, SDF-1, and CXCR4 was performed on mouse eyes 2 weeks after the initiation of laser rupture of Bruch's membrane, a choroidal neovascularization (CNV) model. CXCR4 antagonist and CXCR4 blocking antibody were tested on inhibition of CNV lesion size in this model. Real-time PCR was used to determine mRNA levels for SDF-1, VEGF, IGF-1, and their cognate receptors in the retinal pigment epithelium/choroid complex of mice that underwent this CNV model.


RESULTS
IGF-1 and VEGF demonstrated an additive effect on SDF-1-induced in vitro angiogenesis. CXCR4 immunoreactivity was present in both normal and laser-injured mice at the laser burn site and at the ganglion cell layer, the anterior portion of the inner nuclear layer, photoreceptors, and choroidal stroma. SDF-1 was observed in identical locations but was not seen in photoreceptors. mRNA levels for SDF-1, VEGF, and IGF-1 and their receptors were increased after laser injury. CXCR4-neutralizing antibody reduced neovascularization when injected subretinally but not intraperitoneally or intravitreally.


CONCLUSIONS
The potent proangiogenic factors IGF-1 and VEGF both stimulate SDF-1-induced angiogenesis. Local inhibition of CXCR4 is required for an antiangiogenic effect in CNV lesions.
Sengupta
Nilanjana
N
Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610-0267, USA.
Afzal
Aqeela
A
Caballero
Sergio
S
Chang
Kyung-Hee
KH
Shaw
Lynn C
LC
Pang
Ji-Jing
JJ
Bond
Vincent C
VC
Bhutto
Imran
I
Baba
Takayuki
T
Lutty
Gerard A
GA
Grant
Maria B
MB
D042501:Angiogenic Proteins / Q000494:pharmacology*; D000818:Animals; D054377:Chemokine CXCL12 / Q000235:genetics / Q000494:pharmacology; D020256:Choroidal Neovascularization / Q000378:metabolism* / Q000473:pathology; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000473:pathology; D006801:Humans; D007267:Injections; D007274:Injections, Intraperitoneal; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000494:pharmacology*; D017075:Laser Coagulation; D008168:Lung / Q000166:cytology; D051379:Mice; D008810:Mice, Inbred C57BL; D019899:Paracrine Communication / Q000502:physiology*; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D019718:Receptors, CXCR4 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000494:pharmacology*; D014822:Vitreous Body
D042501:Angiogenic Proteins; C514936:CXCR4 protein, mouse; D054377:Chemokine CXCL12; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D012333:RNA, Messenger; D019718:Receptors, CXCR4; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; D007334:Insulin-Like Growth Factor I