Hardy Pierre, Beauchamp Martin, Sennlaub Florian, Gobeil Fernand, Tremblay Lise, Mwaikambo Bupe, Lachapelle Pierre, Chemtob Sylvain
Department of Obstetrics, Research Center Sainte-Justine Hospital and University of Montreal, Montreal, Quebec, Canada, H3T 1C5.
Prostaglandins Leukot Essent Fatty Acids. 2005 May;72(5):301-25. doi: 10.1016/j.plefa.2005.02.004.
Ischemic proliferative retinopathy develops in various retinal disorders, including retinal vein occlusion, diabetic retinopathy and retinopathy of prematurity. Ischemic retinopathy remains a common cause of visual impairment and blindness in the industrialized world due to relatively ineffective treatment. Oxygen-induced retinopathy (OIR) is an established model of retinopathy of prematurity associated with vascular cell injury culminating in microvascular degeneration, which precedes an abnormal neovascularization. The retina is a tissue particularly rich in polyunsaturated fatty acids and the ischemic retina becomes highly sensitive to lipid peroxidation initiated by oxygenated free radicals. Consequently, the retina constitutes an excellent model for testing the functional consequences of membrane lipid peroxidation. Retinal tissue responds to physiological and pathophysiological stimuli by the activation of phospholipases and the consequent release from membrane phospholipids of biologically active metabolites. Activation of phospholipase A(2) is the first step in the synthesis of two important classes of lipid second messengers, the eicosanoids and a membrane-derived phospholipid mediator platelet-activating factor (PAF). These lipid mediators accumulate in the retina in response to injury and a physiologic role of these metabolites in retinal vasculature remains for the most part to be determined; albeit proposed roles have been suggested for some. The eicosanoids, in particular the prostanoids, thromboxane (TXA2) and PAF are abundantly generated following an oxidant stress and contribute to neurovascular injury. TXA2 and PAF play an important role in the retinal microvacular degeneration of OIR by directly inducing endothelial cell death and potentially could contribute to the pathogenesis of ischemic retinopathies. Despite these advances there are still a number of important questions that remain to be answered before we can confidently target pathological signals. This review focuses on mechanisms that precede the development of neovascularization, most notably regarding the role of lipid mediators that partake in microvascular degeneration.
缺血性增殖性视网膜病变发生于多种视网膜疾病,包括视网膜静脉阻塞、糖尿病视网膜病变和早产儿视网膜病变。在工业化国家,由于治疗效果相对不佳,缺血性视网膜病变仍然是视力损害和失明的常见原因。氧诱导性视网膜病变(OIR)是一种已确立的早产儿视网膜病变模型,与血管细胞损伤相关,最终导致微血管变性,随后出现异常的新生血管形成。视网膜是一个富含多不饱和脂肪酸的组织,缺血的视网膜对由氧化自由基引发的脂质过氧化变得高度敏感。因此,视网膜构成了一个测试膜脂质过氧化功能后果的理想模型。视网膜组织通过磷脂酶的激活以及随之从膜磷脂中释放生物活性代谢物来响应生理和病理生理刺激。磷脂酶A2的激活是合成两类重要脂质第二信使(类花生酸和一种膜衍生的磷脂介质血小板活化因子(PAF))的第一步。这些脂质介质在视网膜中因损伤而积累,这些代谢物在视网膜血管系统中的生理作用在很大程度上仍有待确定;尽管已经有人提出了一些可能的作用。类花生酸,特别是前列腺素、血栓素(TXA2)和PAF在氧化应激后大量产生,并导致神经血管损伤。TXA2和PAF通过直接诱导内皮细胞死亡在OIR的视网膜微血管变性中起重要作用,并且可能促成缺血性视网膜病变的发病机制。尽管有这些进展,但在我们能够自信地靶向病理信号之前,仍有许多重要问题有待解答。本综述重点关注新生血管形成之前的机制,最显著的是参与微血管变性的脂质介质的作用。