Olchawa Magdalena M, Herrnreiter Anja M, Pilat Anna K, Skumatz Christine M B, Niziolek-Kierecka Magdalena, Burke Janice M, Sarna Tadeusz J
Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland.
Department of Ophthalmology, Eye Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
Free Radic Biol Med. 2015 Dec;89:873-82. doi: 10.1016/j.freeradbiomed.2015.10.411. Epub 2015 Oct 23.
Zeaxanthin and α-tocopherol have been previously shown to efficiently protect liposomal membrane lipids against photosensitized peroxidation, and to protect cultured RPE cells against photodynamic killing. Here the protective action of combined zeaxanthin and α-tocopherol was analyzed in ARPE-19 cells subjected to photodynamic (PD) stress mediated by rose Bengal (RB) or merocyanine-540 (MC-540) at sub-lethal levels. Stress-induced cytotoxicity was analyzed by the MTT assay. The peroxidation of membrane lipids was determined by HPLC-EC (Hg) measurements of cholesterol hydroperoxides using cholesterol as a mechanistic reporter molecule. The specific phagocytosis of FITC-labeled photoreceptor outer segments (POS) isolated from bovine retinas was measured by flow cytometry, and the levels of phagocytosis receptor proteins αv integrin subunit, β5 integrin subunit and MerTK were quantified by Western blot analysis. Cytotoxicity measures confirmed that PD stress levels used for phagocytosis analysis were sub-lethal and that antioxidant supplementation protected against higher, lethal PD doses. Sub-lethal PD stress mediated by both photosensitizers induced the accumulation of 5α-OOH and 7α/β-OOH cholesterol hydroperoxides and the addition of the antioxidants substantially inhibited their accumulation. Antioxidant delivery prior to PD stress also reduced the inhibitory effect of stress on POS phagocytosis and partially reduced the stress-induced diminution of phagocytosis receptor proteins. The use of a novel model system where oxidative stress was induced at sub-lethal levels enable observations that would not be detectable using lethal stress models. Moreover, novel observations about the protective effects of zeaxanthin and α-tocopherol on photodynamic damage to ARPE-19 cell membranes and against reductions in the abundance of receptor proteins involved in POS phagocytosis, a process essential for photoreceptor survival, supports the importance of the antioxidants in protecting of the retina against photooxidative injury.
叶黄素和α-生育酚此前已被证明能有效保护脂质体膜脂免受光致敏过氧化作用,并保护培养的视网膜色素上皮(RPE)细胞免受光动力杀伤。在此,我们分析了叶黄素和α-生育酚联合使用对ARPE - 19细胞的保护作用,这些细胞受到亚致死水平的孟加拉玫瑰红(RB)或部花青 - 540(MC - 540)介导的光动力(PD)应激。通过MTT法分析应激诱导的细胞毒性。使用胆固醇作为机制报告分子,通过高效液相色谱 - 电化学检测(汞)法测量胆固醇氢过氧化物来确定膜脂的过氧化作用。通过流式细胞术测量从牛视网膜分离的异硫氰酸荧光素(FITC)标记的光感受器外段(POS)的特异性吞噬作用,并通过蛋白质免疫印迹分析对吞噬受体蛋白αv整合素亚基、β5整合素亚基和MerTK的水平进行定量。细胞毒性测量证实,用于吞噬作用分析的PD应激水平是亚致死的,并且补充抗氧化剂可保护细胞免受更高的致死性PD剂量的损伤。两种光敏剂介导的亚致死性PD应激均诱导了5α - OOH和7α/β - OOH胆固醇氢过氧化物的积累,而添加抗氧化剂可显著抑制它们的积累。在PD应激之前递送抗氧化剂还降低了应激对POS吞噬作用的抑制作用,并部分减轻了应激诱导的吞噬受体蛋白减少。使用在亚致死水平诱导氧化应激的新型模型系统能够观察到使用致死应激模型无法检测到的现象。此外,关于叶黄素和α - 生育酚对ARPE - 19细胞膜光动力损伤以及对参与POS吞噬作用(光感受器存活所必需的过程)的受体蛋白丰度降低的保护作用的新观察结果,支持了抗氧化剂在保护视网膜免受光氧化损伤方面的重要性。