VEGF164(165) as the pathological isoform: differential leukocyte and endothelial responses through VEGFR1 and VEGFR2.
OBJECTIVE
Vascular endothelial growth factor (VEGF) induces angiogenesis and vascular permeability and is thought to be operative in several ocular vascular diseases. The VEGF isoforms are highly conserved among species; however, little is known about their differential biological functions in adult tissue. In the current study, the inflammatory potential of two prevalent VEGF isoform splice variants, VEGF(120(121)) and VEGF(164(165)), was studied in the transparent and avascular adult mouse cornea.


METHODS
Controlled-release pellets containing equimolar amounts of VEGF(120) and VEGF(164) were implanted in corneas. The mechanisms underlying this differential response of VEGF isoforms were explored. The response of VEGF in cultured endothelial cells was determined by Western blot analysis. The response of VEGF isoforms in leukocytes was also investigated.


RESULTS
VEGF(164) was found to be significantly more potent at inducing inflammation. In vivo blockade of VEGF receptor (VEGFR)-1 significantly suppressed VEGF(164)-induced corneal inflammation. In vitro, VEGF(165) more potently stimulated intracellular adhesion molecule (ICAM)-1 expression on endothelial cells, an effect that was mediated by VEGFR2. VEGF(164) was also more potent at inducing the chemotaxis of monocytes, an effect that was mediated by VEGFR1. In an immortalized human leukocyte cell line, VEGF(165) was found to induce tyrosine phosphorylation of VEGFR1 more efficiently.


CONCLUSIONS
Taken together, these data identify VEGF(164(165)) as a proinflammatory isoform and identify multiple mechanisms underlying its proinflammatory biology.
Usui
Tomohiko
T
Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, USA.
Ishida
Susumu
S
Yamashiro
Kenji
K
Kaji
Yuichi
Y
Poulaki
Vasiliki
V
Moore
Johnny
J
Moore
Tara
T
Amano
Shiro
S
Horikawa
Yoshitaka
Y
Dartt
Darlene
D
Golding
Matthew
M
Shima
David T
DT
Adamis
Anthony P
AP
D000818:Animals; D015153:Blotting, Western; D018929:Cell Culture Techniques; D002634:Chemotaxis, Leukocyte / Q000187:drug effects; D003315:Cornea / Q000187:drug effects* / Q000473:pathology; D016510:Corneal Neovascularization / Q000139:chemically induced* / Q000473:pathology; D004730:Endothelium, Vascular / Q000187:drug effects*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D019169:Jurkat Cells / Q000187:drug effects; D007958:Leukocyte Count; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010766:Phosphorylation; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
D020033:Protein Isoforms; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; D018799:Intercellular Adhesion Molecule-1; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2