Role of nonproteolytically activated prorenin in pathologic, but not physiologic, retinal neovascularization.
OBJECTIVE
Recently, it was revealed that the inhibition of nonproteolytic activation of prorenin led to significant suppression of ocular inflammation in endotoxin-induced uveitis. The purpose of the present study was to investigate whether nonproteolytically activated prorenin plays a role in ischemia-induced retinal neovascularization.


METHODS
C57BL/6 neonatal mice were reared in an 80% concentration of oxygen from postnatal (P) day 7 to P12, followed by room-air breathing to P17 to induce ischemia-initiated retinal neovascularization. Tissue localization of activated prorenin and prorenin receptor was examined by immunohistochemistry. Animals received intraperitoneal injections of handle-region peptide (HRP), a decoy peptide corresponding to the handle region of prorenin, which inhibits prorenin receptor-mediated upregulation of the renin-angiotensin system (RAS). A concanavalin A lectin perfusion-labeling technique was used to evaluate the areas of physiologic and pathologic retinal new vessels and the number of leukocytes adhering to the vasculature. Retinal mRNA expression and protein levels of intercellular adhesion molecule (ICAM)-1, vascular endothelial growth factor (VEGF), VEGF receptor (VEGFR)-1, and VEGFR-2 were examined by RT-PCR and ELISA.


RESULTS
Retinal vessels in ischemic retinopathy eyes were positive for activated prorenin and prorenin receptor. Pathologic, but not physiologic, retinal neovascularization was significantly attenuated in HRP-treated mice compared with vehicle- or control peptide-treated animals. The number of adherent leukocytes was also significantly reduced. Retinal mRNA expression and protein levels of ICAM-1, VEGF, VEGFR-1, and VEGFR-2 in ischemic retinopathy were also significantly suppressed by the application of HRP.


CONCLUSIONS
The present findings suggest that nonproteolytic activation of prorenin selectively promotes pathologic, but not physiologic, retinal neovascularization through the inflammatory processes related to pathologic neovascularization.
Satofuka
Shingo
S
Laboratory of Retinal Cell Biology, Keio University School of Medicine, Tokyo, Japan.
Ichihara
Atsuhiro
A
Nagai
Norihiro
N
Koto
Takashi
T
Shinoda
Hajime
H
Noda
Kousuke
K
Ozawa
Yoko
Y
Inoue
Makoto
M
Tsubota
Kazuo
K
Itoh
Hiroshi
H
Oike
Yuichi
Y
Ishida
Susumu
S
D000818:Animals; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D007124:Immunoenzyme Techniques; D007274:Injections, Intraperitoneal; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D007511:Ischemia / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018919:Neovascularization, Physiologic; D010446:Peptide Fragments / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020318:Rats, Long-Evans; D011956:Receptors, Cell Surface / Q000378:metabolism; D012083:Renin / Q000737:chemistry / Q000502:physiology*; D015861:Retinal Neovascularization / Q000209:etiology* / Q000378:metabolism / Q000517:prevention & control; D012171:Retinal Vessels / Q000378:metabolism; D012173:Retinitis / Q000209:etiology* / Q000378:metabolism / Q000517:prevention & control; D020133:Reverse Transcriptase Polymerase Chain Reaction; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000235:genetics / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics / Q000378:metabolism; D000093342:Prorenin Receptor; D000092502:Renin Inhibitors
D018799:Intercellular Adhesion Molecule-1; D010446:Peptide Fragments; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D012083:Renin; D042461:Vascular Endothelial Growth Factor A; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2; D000093342:Prorenin Receptor; D000092502:Renin Inhibitors; C090509:Icam1 protein, mouse; C467480:vascular endothelial growth factor A, mouse; C467498:vascular endothelial growth factor A, rat