Department of Biochemistry, Faculty of Medicine, A.M.U., Aligarh 202 002, India.
Hum Immunol. 2011 Mar;72(3):219-25. doi: 10.1016/j.humimm.2010.12.004. Epub 2010 Dec 20.
Peroxynitrite is a potent oxidant and nitrating agent and has in vivo existence. It is a powerful proinflammatory substance and may increase vascular permeability in inflamed tissues. Systemic lupus erythematosus (SLE) is an autoimmune inflammatory disease of unknown etiology. Since its discovery, numerous self- and non-self, nuclear, and cytoplasmic antigens have been suggested as stimuli for SLE initiation, but the exact trigger is yet to be identified. In this study, an attempt has been made to investigate the binding characteristics of SLE anti-DNA autoantibodies to native DNA and native and peroxynitrite-modified H2A histone to explore the possible role of modified protein antigen(s) in SLE initiation and progression. The nuclear protein (H2A histone) was modified by peroxynitrite synthesized in our laboratory. The peroxynitrite-modified H2A revealed generation of nitrotyrosine, dityrosine, and carbonyls when subjected to investigation by physicochemical methods. Binding characteristics and specificity of SLE anti-DNA antibodies were analyzed by direct binding and inhibition enzyme-linked immunosorbent assay. The data show preferential binding of SLE autoantibodies to peroxynitrite-modified H2A histone in comparison with native H2A histone or native DNA. A band shift assay further substantiated the enhanced recognition of peroxynitirite-modified H2A histone by anti-DNA autoantibodies. The results suggest that peroxynitrite modification of self-antigen(s) can generate neoepitopes capable of inducing SLE characteristic autoantibodies. The preferential binding of peroxynitrite-modified H2A histone by SLE anti-DNA antibodies points out the likely role of oxidatively modified and nitrated H2A histone in the initiation/progression of SLE. Moreover, oxidatively modified and nitrated nuclear protein antigen, rather than nucleic acid antigens, appear to be more suitable as a trigger for SLE.
过氧亚硝酸盐是一种强氧化剂和硝化剂，具有体内存在。它是一种强大的促炎物质，可能会增加炎症组织的血管通透性。系统性红斑狼疮（SLE）是一种病因不明的自身免疫性炎症性疾病。自发现以来，已经提出了许多自身和非自身、核和细胞质抗原作为 SLE 发病的刺激物，但确切的触发因素仍未确定。在这项研究中，我们试图研究 SLE 抗 DNA 自身抗体与天然 DNA 以及天然和过氧亚硝酸盐修饰的 H2A 组蛋白的结合特性，以探索修饰蛋白抗原（s）在 SLE 发病和进展中的可能作用。核蛋白（H2A 组蛋白）被我们实验室合成的过氧亚硝酸盐修饰。过氧亚硝酸盐修饰的 H2A 通过物理化学方法检测到硝基酪氨酸、二酪氨酸和羰基的生成。通过直接结合和抑制酶联免疫吸附试验分析了 SLE 抗 DNA 抗体的结合特性和特异性。数据显示，与天然 H2A 组蛋白或天然 DNA 相比，SLE 自身抗体优先与过氧亚硝酸盐修饰的 H2A 组蛋白结合。带移位试验进一步证实了抗 DNA 自身抗体对过氧亚硝酸盐修饰的 H2A 组蛋白的增强识别。结果表明，自身抗原的过氧亚硝酸盐修饰可以产生能够诱导 SLE 特征性自身抗体的新表位。SLE 抗 DNA 抗体对过氧亚硝酸盐修饰的 H2A 组蛋白的优先结合指出，氧化修饰和硝化的 H2A 组蛋白可能在 SLE 的起始/进展中起作用。此外，氧化修饰和硝化的核蛋白抗原，而不是核酸抗原，似乎更适合作为 SLE 的触发因素。
