Oz Helieh S, Chen Theresa S, Nagasawa Herbert
Center for the Oral Health Research and Department of Internal Medicine, University of Kentucky Medical Center, Lexington, KY 40536, USA.
Transl Res. 2007 Aug;150(2):122-9. doi: 10.1016/j.trsl.2006.12.010. Epub 2007 May 23.
Oxidant-mediated injury plays an important role in the pathophysiology of inflammatory bowel disease (IBD). Recently, antioxidants were shown to modulate colitis in mice. In this study, the protective effects of L-cysteine and glutathione (GSH) prodrugs are further evaluated against progression of colitis in a murine model. ICR mice were fed compounds incorporated into chow as follows: Group (A) received chow supplemented with vehicle. Group (B) was provided 2-(RS)-n-propylthiazolidine-4(R)-carboxylic-acid (PTCA), a cysteine prodrug. Group (C) received D-ribose-L-cysteine (RibCys), another cysteine prodrug that releases L-cysteine. Group (D) was fed L-cysteine-glutathione mixed sulfide (CySSG), a ubiquitous GSH derivative present in mammalian cells. After 3 days, the animals were further provided with normal drinking water or water supplemented with dextran sodium sulfate (DSS). Mice administered DSS developed severe colitis and suffered weight loss. Colonic lesions significantly improved in animals treated with PTCA and RibCys and, to a lesser extent, with CySSG therapy. Hepatic GSH levels were depleted in colitis animals (control vs DSS, P < 0.001), and normalized with prodrug therapies (control vs treatments, P > 0.05). Protein expressions of serum amyloid A and inflammatory cytokines [interleukin (IL)-6, IL-12, tumor necrosis factor-alpha (TNF-alpha), osteopontin (OPN)] were significantly increased in colitis animals and improved with therapies. Immunohistochemistry and Western blot analyses showed significant upregulation of the macrophage-specific markers, COX-2 and CD68, which suggests macrophage activation and infiltration in the colonic lamina propria in colitis animals. These abnormalities were attenuated in prodrug-treated mice. In conclusion, these data strongly support the novel action of the PTCA against colitis, which further supports a possible therapeutic application for IBD patients.
氧化应激介导的损伤在炎症性肠病（IBD）的病理生理学中起重要作用。最近，抗氧化剂被证明可调节小鼠结肠炎。在本研究中，进一步评估了L-半胱氨酸和谷胱甘肽（GSH）前药对小鼠模型中结肠炎进展的保护作用。将ICR小鼠喂食掺入饲料中的化合物，如下：组（A）接受补充有赋形剂的饲料。组（B）给予2-(RS)-正丙基噻唑烷-4(R)-羧酸（PTCA），一种半胱氨酸前药。组（C）接受D-核糖-L-半胱氨酸（RibCys），另一种释放L-半胱氨酸的半胱氨酸前药。组（D）喂食L-半胱氨酸-谷胱甘肽混合硫化物（CySSG），一种存在于哺乳动物细胞中的普遍存在的GSH衍生物。3天后，给动物进一步提供正常饮用水或补充有葡聚糖硫酸钠（DSS）的水。给予DSS的小鼠发生严重结肠炎并体重减轻。用PTCA和RibCys治疗的动物结肠病变明显改善，用CySSG治疗的动物改善程度较小。结肠炎动物肝脏GSH水平降低（对照组与DSS组，P < 0.001），前药治疗后恢复正常（对照组与治疗组，P > 0.05）。血清淀粉样蛋白A和炎性细胞因子[白细胞介素（IL）-6、IL-12、肿瘤坏死因子-α（TNF-α）、骨桥蛋白（OPN）]的蛋白表达在结肠炎动物中显著增加，并通过治疗得到改善。免疫组织化学和蛋白质印迹分析显示巨噬细胞特异性标志物COX-2和CD68显著上调，这表明结肠炎动物结肠固有层中巨噬细胞活化和浸润。这些异常在接受前药治疗的小鼠中减轻。总之，这些数据有力地支持了PTCA对结肠炎的新作用，这进一步支持了IBD患者可能的治疗应用。
