Laboratory of Eye Histochemistry and Pharmacology, Institute of Experimental Medicine, Academy of Sciences of Czech Republic, Vídenská 1083, 14220 Prague 4, Czech Republic.
Graefes Arch Clin Exp Ophthalmol. 2011 Aug;249(8):1185-94. doi: 10.1007/s00417-011-1676-y. Epub 2011 Apr 15.
Trehalose, a nonreducing disaccharide of glucose, is synthesized as a stress response factor when cells are exposed to stressful conditions. In the cornea, oxidative stress plays the key role in the development of acute corneal inflammatory response to UVB rays, photokeratitis. We found previously that trehalose reduced UVB-induced oxidative effects on the formation of cytotoxic peroxynitrite, apoptotic corneal epithelial cell death and changes in corneal optics. The aim of the present study was to examine whether trehalose might inhibit UVB-mediated proinflammatory cytokine and matrix metalloproteinase induction and the development of an antioxidant/pro-oxidant imbalance in the corneal epithelium, changes found previously to be strongly involved in the acute corneal UVB-induced inflammation. The expression of heat shock protein 70 as a potential biomarker for corneal UVB-induced damage was also examined.
The corneas of New Zealand white rabbits were irradiated with UVB rays, 312 nm, daily dose of 0.5 J/cm(2) for 4 days. During the irradiation, trehalose drops were applied on the right eye and buffered saline on the left eye. One day after the end of irradiations, the animals were killed and the corneas examined immunohistochemically for the expression of antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase), pro-oxidant xanthine oxidoreductase/xanthine oxidase, proinflammatory cytokines (interleukin-6, interleukin-8), matrix metalloproteinase-9 and heat shock protein 70.
After buffered saline treatment during UVB irradiation, an antioxidant/pro-oxidant imbalance appeared in the corneal epithelium: The expression of antioxidant enzymes was highly reduced, whereas the expression of pro-oxidant xanthine oxidase was increased. The pronounced expression of pro-inflammatory cytokines, matrix metalloproteinase and heat shock protein 70 was found in the UVB-irradiated corneal epithelium. Trehalose application significantly suppressed all the above-mentioned UVB-induced corneal disturbances.
Trehalose favorably influenced the oxidative damage of the cornea caused by UVB rays. Trehalose suppressed proinflammatory cytokine induction. It is suggested that suppression of proinflammatory cytokines contributed strongly to reduced matrix metalloproteinase and xanthine oxidase expression in the UVB-irradiated corneal epithelium and to the decreased development of an antioxidant/pro-oxidant imbalance. The overexpression of heat shock protein 70 found in UVB-irradiated cornea after buffered saline treatment was reduced after trehalose application.
海藻糖是葡萄糖的非还原二糖，当细胞暴露于应激条件下时，它作为应激反应因子被合成。在角膜中，氧化应激在急性角膜炎症反应的发展中起关键作用，这种炎症反应是由 UVB 射线引起的光角膜炎引起的。我们之前发现，海藻糖可以减少 UVB 对细胞毒性过氧亚硝酸盐形成、凋亡角膜上皮细胞死亡和角膜光学变化的诱导作用。本研究的目的是研究海藻糖是否可以抑制 UVB 介导的促炎细胞因子和基质金属蛋白酶的诱导，并抑制角膜上皮细胞中抗氧化/促氧化剂失衡的发展，我们之前发现这种失衡与急性角膜 UVB 诱导的炎症有很强的关系。还检查了热休克蛋白 70 的表达，作为角膜 UVB 诱导损伤的潜在生物标志物。
新西兰白兔的角膜每天用 312nm 的 UVB 射线照射，剂量为 0.5J/cm2，共照射 4 天。在照射过程中，右眼滴注海藻糖，左眼滴注缓冲盐水。照射结束后 1 天，处死动物，用免疫组化法检测抗氧化酶（过氧化氢酶、超氧化物歧化酶、谷胱甘肽过氧化物酶）、促氧化剂黄嘌呤氧化还原酶/黄嘌呤氧化酶、促炎细胞因子（白细胞介素-6、白细胞介素-8）、基质金属蛋白酶-9 和热休克蛋白 70 的表达。
在 UVB 照射期间用缓冲盐水处理后，角膜上皮出现抗氧化/促氧化剂失衡：抗氧化酶的表达明显减少，而促氧化剂黄嘌呤氧化酶的表达增加。在 UVB 照射的角膜上皮中发现了明显的促炎细胞因子、基质金属蛋白酶和热休克蛋白 70 的表达。海藻糖的应用显著抑制了所有上述由 UVB 引起的角膜紊乱。
海藻糖对 UVB 射线引起的角膜氧化损伤有良好的影响。海藻糖抑制了促炎细胞因子的诱导。研究表明，抑制促炎细胞因子对减少 UVB 照射的角膜上皮中基质金属蛋白酶和黄嘌呤氧化酶的表达以及减少抗氧化/促氧化剂失衡的发展有重要作用。在用缓冲盐水处理后的 UVB 照射角膜中发现的热休克蛋白 70 的过度表达，在用海藻糖处理后减少。
