Role of arginine deficiency in pathogenesis of lupus

描述(由申请人提供)：系统性红斑狼疮(SLE)的免疫学特征包括多克隆B细胞激活和产生特定的自身抗体。然而，自身免疫反应仅高度受限于少数抗原，这表明存在专门选择靶抗原的机制。抗小核核糖核蛋白自身抗体(SnRNPs：SM和nRNP)经常在SLE、MRL小鼠和Pristane治疗的正常小鼠中产生。在Pristane治疗的小鼠中，U1-70K具有异常高的精氨酸含量(21%)，似乎是自身免疫过程的中心。炎症部位的激活的巨噬细胞和精氨酸酶消耗精氨酸。此外，存在于高等植物中的L-精氨酸的非蛋白质氨基酸同系物L-刀豆氨酸可能有效地结合到蛋白质中，产生异常蛋白质，这些蛋白质可能产生能够触发自身免疫的隐蔽表位。在这项研究中，我们将调查为什么U1SnRNPs在Pristane诱导的狼疮中被选择性地靶向。我们假设富含精氨酸的U1-70K在精氨酸缺乏的Pristane肉芽肿中异常，产生启动自身免疫的隐蔽表位。在目标1中，将通过氨基酸分析来检查Pristane处理的小鼠是否存在精氨酸缺乏。精氨酸代谢(摄取、消耗和再转化)也将被评估。在目标2中，将通过免疫沉淀、氨基酸分析和质谱分析来评估在精氨酸缺乏的条件下体外在L-刀豆碱存在下合成的U1-70K的修饰情况。普瑞斯坦处理的小鼠细胞中的U1-70K也将被检测。在目标3中，异常的UlsRNPs(精氨酸缺乏，含L-刀豆氨酸)是否能够触发特异性的自身免疫反应将通过纯化的UlSnRNPs或由这些条件产生的凋亡细胞免疫小鼠来研究。

DESCRIPTION (provided by applicant): Immunological characteristics of systemic lupus erythematosus (SLE) include polyclonal B-cell activation and production of specific autoantibodies. However, the autoimmune response is highly restricted to only a few antigens, indicating that there are mechanisms to specifically select target antigens. Autoantibodies to small nuclear ribonucleoproteins (snRNPs: Sm and nRNP) are frequently produced in SLE, MRL mice, and pristane-treated normal mice. In pristane-treated mice, the U1-70K, which has an unusually high arginine content (21%), appears central to the autoimmune process. Arginine is consumed by activated macrophages and arginases in inflammatory sites. In addition, L-canavanine, a non-protein amino acid homologue of L-arginine present in higher plants, may be efficiently incorporated into proteins, producing aberrant proteins that could create cryptic epitopes capable of triggering autoimmunity. In this study, we will investigate why U1 snRNPs are selectively targeted in pristane-induced lupus. We hypothesize that the arginine-rich U1-70K is aberrant in arginine-deficient pristane granulomas, generating cryptic epitopes that initiate autoimmunity. In aim 1, whether arginine is deficient in pristane-treated mice will be examined by amino acids analysis. Arginine metabolism (uptake, consumption, and reconversion) also will be evaluated. In Aim 2, U1-70K synthesized in arginine-deficient conditions and in the presence of L-canavanine in vitro will be evaluated for modifications by immunoprecipitation, amino acid analysis, and mass spectrometry. U1-70K from cells in pristane-treated mice also will be examined. In Aim 3, whether aberrant UlsnRNPs (arginine-deficient, L-canavanine containing) can trigger a specific autoimmune response will be investigated by immunizing mice with purified UlsnRNPs or apoptotic cells derived from these conditions.