A2E, a component of lipofuscin, is pro-angiogenic in vivo.
A recent study in vitro demonstrated that a major lipofuscin component, A2E, serves as a retinoic acid receptor ligand. The current study investigated the effects of A2E on retinal pigment epithelial (RPE) cells in vivo and was performed to extend the understanding of the effects of A2E. Firstly, subretinal injection of A2E was performed and 3 weeks after the injection, and it was demonstrated that subretinal injection of A2E induced RPE cell death, and concomitant upregulation of vascular endothelial growth factor (VEGF) in the RPE and choroid. The upregulation of VEGF was attenuated by an RARalpha antagonist. Next we performed laser photocoagulation in mice that accumulated A2E either after subretinal injection, by Ccl2 gene knockout or by aging demonstrated that mice that accumulated A2E in the RPE, which showed higher rates of choroidal neobascularization (CNV) formation after weak laser injury than the controls and the formation of CNV was inhibited by an RARalpha antagonist in all models tested. The data suggest that A2E accumulation induces RPE cell death, and concomitant increase of VEGF. Accumulation of A2E alone is not sufficient to induce CNV in vivo, but induces the expression of VEGF in RPE and choroid. The mice that accumulated A2E in RPE cells are vulnerable to CNV development via RAR activation, at least in part.
Department of Ophthalmology, University of Tokyo School of Medicine, Tokyo, Japan.
Aya
A
Iriyama
Yuji
Y
Inoue
Hidenori
H
Takahashi
Yasuhiro
Y
Tamaki
Woo-Dong
WD
Jang
Yasuo
Y
Yanagi
D000818:Animals; D016923:Cell Death / Q000502:physiology; D002829:Choroid / Q000098:blood supply / Q000378:metabolism / Q000473:pathology; D020256:Choroidal Neovascularization / Q000378:metabolism*; D017075:Laser Coagulation; D008062:Lipofuscin / Q000737:chemistry* / Q000378:metabolism; D051379:Mice; D011726:Pyridinium Compounds / Q000737:chemistry / Q000494:pharmacology*; D051381:Rats; D018168:Receptors, Retinoic Acid / Q000235:genetics / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000166:cytology* / Q000187:drug effects* / Q000473:pathology; D000072482:Retinoic Acid Receptor alpha; D012176:Retinoids / Q000737:chemistry / Q000494:pharmacology*; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
C112040:A2-E (N-retinylidene-N-retinylethanolamine); D008062:Lipofuscin; D011726:Pyridinium Compounds; C000607072:Rara protein, mouse; C000607073:Rara protein, rat; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; D012176:Retinoids; D042461:Vascular Endothelial Growth Factor A