She Haicheng, Nakazawa Toru, Matsubara Akihisa, Hisatomi Toshio, Young Tara A, Michaud Norman, Connolly Edward, Hafezi-Moghadam Ali, Gragoudas Evangelos S, Miller Joan W
Angiogenesis and Laser Laboratories, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114, USA.
Invest Ophthalmol Vis Sci. 2007 May;48(5):2268-77. doi: 10.1167/iovs.06-0979.
To investigate the role of nitric oxide synthase (NOS) in photoreceptor degeneration associated with photodynamic therapy (PDT) in a laser-induced model of choroidal neovascularization (CNV).
PDT was performed in monkey and Brown Norway rats with laser-induced CNV. L-NAME, a NOS inhibitor, or saline was injected intraperitoneally in rats with CNV. An NO donor, or saline, was injected intravitreously into normal rats. Photoreceptor apoptosis was evaluated by TUNEL and electron microscopy. NOS, ED-1, and cleaved-caspase-3 (c-casp-3) expression were determined by immunohistochemistry. CNV lesions were examined by fluorescence angiography and choroidal flat mount.
TUNEL and electron microscopy showed photoreceptor apoptosis after PDT. In rats, there were significantly more TUNEL-positive cells in the photoreceptors 24 hours after PDT, whereas in the CNV lesions there were more TUNEL-positive cells 6 hours after PDT. C-casp-3 was detected in the CNV lesions but not in the photoreceptors after PDT. There was no difference in the numbers of ED-1-positive macrophages before and after PDT. However, inducible NOS (iNOS) was increased after PDT in macrophages. Intravitreous injection of the NO donor without PDT also induced substantial photoreceptor apoptosis. L-NAME-treated animals had significantly fewer TUNEL-positive cells in the photoreceptors than saline-treated animals after PDT (P < 0.05). There were no differences in CNV size and leakage between L-NAME- and saline-treated groups.
iNOS expression in macrophages contributes to PDT-induced photoreceptor degeneration. NOS inhibition reduces PDT-induced photoreceptor degeneration without compromising the treatment effect of PDT in an experimental model of CNV.
在激光诱导的脉络膜新生血管（CNV）模型中，研究一氧化氮合酶（NOS）在与光动力疗法（PDT）相关的光感受器退变中的作用。
对激光诱导CNV的猴子和棕色挪威大鼠进行PDT。将NOS抑制剂L-NAME或生理盐水腹腔注射到患有CNV的大鼠体内。将一氧化氮供体或生理盐水玻璃体内注射到正常大鼠体内。通过TUNEL和电子显微镜评估光感受器凋亡。通过免疫组织化学测定NOS、ED-1和裂解的半胱天冬酶-3（c-casp-3）的表达。通过荧光血管造影和脉络膜平铺片检查CNV病变。
TUNEL和电子显微镜显示PDT后光感受器凋亡。在大鼠中，PDT后24小时光感受器中的TUNEL阳性细胞明显更多，而在CNV病变中，PDT后6小时有更多TUNEL阳性细胞。PDT后在CNV病变中检测到c-casp-3，但在光感受器中未检测到。PDT前后ED-1阳性巨噬细胞的数量没有差异。然而，PDT后巨噬细胞中的诱导型NOS（iNOS）增加。在未进行PDT的情况下玻璃体内注射一氧化氮供体也诱导了大量光感受器凋亡。与生理盐水处理的动物相比，L-NAME处理的动物在PDT后光感受器中的TUNEL阳性细胞明显更少（P < 0.05）。L-NAME处理组和生理盐水处理组之间的CNV大小和渗漏没有差异。
巨噬细胞中iNOS的表达导致PDT诱导的光感受器退变。在CNV的实验模型中，抑制NOS可减少PDT诱导的光感受器退变，而不影响PDT的治疗效果。
