Neu Josef, Afzal Aqeela, Pan Hao, Gallego Esteban, Li Nan, Li Calzi Sergio, Caballero Sergio, Spoerri Polyxenie E, Shaw Lynn C, Grant Maria B
Departments of Pharmacology and Therapeutics, University of Florida, Gainesville 32610-0267, USA.
Invest Ophthalmol Vis Sci. 2006 Jul;47(7):3151-5. doi: 10.1167/iovs.05-1473.
Premature infants undergoing intensive care are highly vulnerable to amino acid deprivation. Supplementation of glutamine or arginine has resulted in beneficial effects in human neonates. This study was conducted to examine the effect of the dipeptide arginyl-glutamine (Arg-Gln) on vascular endothelial cell growth factor (VEGF) levels in primary human retinal pigment epithelial (hRPE) cell cultures and on inhibition of neovascularization in the oxygen-induced retinopathy (OIR) model.
The effects of Arg-Gln on VEGF levels were measured in supernates from hRPE cells by using ELISAs. For in vivo studies, mouse pups received twice-daily intraperitoneal injections of Arg-Gln, a control dipeptide (Ala-Gly) or were not injected. Retinal flatmounts from one cohort were prepared and retinal vessel morphology examined. The contralateral eyes were embedded, sectioned, and stained to count preretinal neovascular nuclei. RNA was isolated from retinas of selected animals and was used to quantify VEGF mRNA by real-time RT-PCR.
Treatment of hRPE cells with Arg-Gln decreased VEGF levels in a dose-dependent manner. In the OIR model, Arg-Gln at 5 g/kg per day reduced preretinal neovascularization by 82%+/-7% (P<0.005), when compared with the control dipeptide Ala-Gly, and reduced VEGF mRNA by 64%+/-9% (P<0.001).
Arg-Gln dramatically inhibited retinal neovascularization in the OIR model. This effect was associated with a reduction in retinal VEGF mRNA levels. Similarly the dipeptide reduced VEGF expression in hRPE cells, a cell type likely to respond to retinal hypoxia by expressing VEGF. Arg-Gln appears to be safe and, with future studies in human infants, may prove beneficial in the prevention of ROP.
接受重症监护的早产儿极易出现氨基酸缺乏。补充谷氨酰胺或精氨酸已在人类新生儿中产生有益效果。本研究旨在探讨二肽精氨酰 - 谷氨酰胺（Arg - Gln）对原代人视网膜色素上皮（hRPE）细胞培养物中血管内皮生长因子（VEGF）水平以及对氧诱导性视网膜病变（OIR）模型中新生血管形成抑制作用的影响。
通过酶联免疫吸附测定法（ELISA）测量hRPE细胞培养上清液中Arg - Gln对VEGF水平的影响。在体内研究中，幼鼠每天接受两次腹腔注射Arg - Gln、对照二肽（丙氨酰 - 甘氨酸）或不注射。制备一组幼鼠的视网膜平铺标本并检查视网膜血管形态。对侧眼进行包埋、切片和染色，以计数视网膜前新生血管核。从选定动物的视网膜中分离RNA，并用于通过实时逆转录聚合酶链反应（RT - PCR）定量VEGF mRNA。
用Arg - Gln处理hRPE细胞以剂量依赖性方式降低VEGF水平。在OIR模型中，与对照二肽丙氨酰 - 甘氨酸相比，每天5 g/kg的Arg - Gln使视网膜前新生血管形成减少82%±7%（P<0.005），并使VEGF mRNA减少64%±9%（P<0.001）。
Arg - Gln在OIR模型中显著抑制视网膜新生血管形成。这种作用与视网膜VEGF mRNA水平的降低有关。同样，该二肽降低了hRPE细胞中的VEGF表达，hRPE细胞是一种可能通过表达VEGF对视网膜缺氧作出反应的细胞类型。Arg - Gln似乎是安全的，并且随着未来在人类婴儿中的研究，可能在预防早产儿视网膜病变（ROP）方面被证明是有益的。
