PURPOSE: In ischemic retinopathies, the misdirection of reparative angiogenesis away from the hypoxic retina leads to pathologic neovascularization. Thus, therapeutic strategies that reverse this trend would be extremely beneficial. Nitric oxide (NO) produced by endothelial nitric oxide synthase (eNOS) is an important mediator of vascular endothelial growth factor (VEGF) function facilitating vascular growth and maturation. However, in addition to NO, eNOS can also produce superoxide (O(2)(-)), exacerbating pathology. Here, our aim was to investigate the effect of eNOS overexpression on vascular closure and subsequent recovery of the ischemic retina. METHODS: Mice overexpressing eNOS-GFP were subjected to oxygen-induced retinopathy (OIR) and changes in retinal vascularization quantified. Background angiogenic drive was assessed during vascular development and in aortic rings. NOS activity was measured by Griess assay or conversion of radiolabeled arginine to citrulline, nitrotyrosine (NT), and superoxide by immunolabeling and dihydroethidium fluorescence and VEGF by ELISA. RESULTS: In response to hyperoxia, enhanced eNOS expression led to increased NOS-derived superoxide and dysfunctional NO production, NT accumulation, and exacerbated vessel closure associated with tetrahydrobiopterin (BH₄) insufficiency. Despite worse vaso-obliteration, eNOS overexpression resulted in elevated hypoxia-induced angiogenic drive, independent of VEGF production. This correlated with increased vascular branching similar to that observed in isolated aortas and during development. Enhanced recovery was also associated with neovascular tuft formation, which showed defective NO production and increased eNOS-derived superoxide and NT levels. CONCLUSIONS: In hyperoxia, reduced BH₄ bioavailability causes overexpressed eNOS to become dysfunctional, exacerbating vaso-obliteration. In the proliferative phase, however, eNOS has important prorepair functions enhancing angiogenic growth potential and recovery in ischemia.
PURPOSE: In ischemic retinopathies, the misdirection of reparative angiogenesis away from the hypoxic retina leads to pathologic neovascularization. Thus, therapeutic strategies that reverse this trend would be extremely beneficial. Nitric oxide (NO) produced by endothelial nitric oxide synthase (eNOS) is an important mediator of vascular endothelial growth factor (VEGF) function facilitating vascular growth and maturation. However, in addition to NO, eNOS can also produce superoxide (O(2)(-)), exacerbating pathology. Here, our aim was to investigate the effect of eNOS overexpression on vascular closure and subsequent recovery of the ischemic retina. METHODS:Mice overexpressing eNOS-GFP were subjected to oxygen-induced retinopathy (OIR) and changes in retinal vascularization quantified. Background angiogenic drive was assessed during vascular development and in aortic rings. NOS activity was measured by Griess assay or conversion of radiolabeled arginine to citrulline, nitrotyrosine (NT), and superoxide by immunolabeling and dihydroethidium fluorescence and VEGF by ELISA. RESULTS: In response to hyperoxia, enhanced eNOS expression led to increased NOS-derived superoxide and dysfunctional NO production, NT accumulation, and exacerbated vessel closure associated with tetrahydrobiopterin (BH₄) insufficiency. Despite worse vaso-obliteration, eNOS overexpression resulted in elevated hypoxia-induced angiogenic drive, independent of VEGF production. This correlated with increased vascular branching similar to that observed in isolated aortas and during development. Enhanced recovery was also associated with neovascular tuft formation, which showed defective NO production and increased eNOS-derived superoxide and NT levels. CONCLUSIONS: In hyperoxia, reduced BH₄ bioavailability causes overexpressed eNOS to become dysfunctional, exacerbating vaso-obliteration. In the proliferative phase, however, eNOS has important prorepair functions enhancing angiogenic growth potential and recovery in ischemia.
Authors: Masuko Ushio-Fukai; Yan Tang; Tohru Fukai; Sergey I Dikalov; Yuxian Ma; Mitsuaki Fujimoto; Mark T Quinn; Patrick J Pagano; Chad Johnson; R Wayne Alexander Journal: Circ Res Date: 2002-12-13 Impact factor: 17.367
Authors: J B Laursen; M Somers; S Kurz; L McCann; A Warnholtz; B A Freeman; M Tarpey; T Fukai; D G Harrison Journal: Circulation Date: 2001-03-06 Impact factor: 29.690
Authors: D Fukumura; T Gohongi; A Kadambi; Y Izumi; J Ang; C O Yun; D G Buerk; P L Huang; R K Jain Journal: Proc Natl Acad Sci U S A Date: 2001-02-27 Impact factor: 11.205
Authors: H Ozaki; M S Seo; K Ozaki; H Yamada; E Yamada; N Okamoto; F Hofmann; J M Wood; P A Campochiaro Journal: Am J Pathol Date: 2000-02 Impact factor: 4.307
Authors: Nuria Matesanz; Grace Park; Hollie McAllister; William Leahey; Adrian Devine; Gary E McVeigh; Tom A Gardiner; Denise M McDonald Journal: Invest Ophthalmol Vis Sci Date: 2010-08-11 Impact factor: 4.799
Authors: Akira Ando; Amy Yang; Keisuke Mori; Haruhiko Yamada; Eri Yamada; Kyoichi Takahashi; Jina Saikia; Min Kim; Michele Melia; Mark Fishman; Paul Huang; Peter A Campochiaro Journal: J Cell Physiol Date: 2002-04 Impact factor: 6.384
Authors: Jutamas Suwanpradid; Modesto Rojas; M Ali Behzadian; R William Caldwell; Ruth B Caldwell Journal: PLoS One Date: 2014-11-06 Impact factor: 3.240
Authors: Kevin S Edgar; Orla M Galvin; Anthony Collins; Zvonimir S Katusic; Denise M McDonald Journal: Invest Ophthalmol Vis Sci Date: 2017-01-01 Impact factor: 4.799
Authors: Takeshi Ninchoji; Dominic T Love; Ross O Smith; Marie Hedlund; Dietmar Vestweber; William C Sessa; Lena Claesson-Welsh Journal: Elife Date: 2021-04-28 Impact factor: 8.140