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细胞活化和特异性自身抗体的产生。然而，自身免疫反应高度局限于少数抗原，这表明存在特异性选择靶抗原的机制。小核核糖核蛋白自身抗体（snRNPs: Sm和nRNP）在SLE、MRL小鼠和经前列腺素治疗的正常小鼠中经常产生。在普利斯坦治疗的小鼠中，具有异常高精氨酸含量（21%）的U1-70K似乎在自身免疫过程中起核心作用。炎症部位的活化巨噬细胞和精氨酸酶消耗精氨酸。此外，l -菜籽酸是高等植物中l -精氨酸的一种非蛋白质氨基酸同源物，可以有效地结合到蛋白质中，产生异常蛋白，从而产生能够触发自身免疫的隐性表位。在这项研究中，我们将研究为什么U1 snRNPs在前列腺素诱导的狼疮中被选择性靶向。我们假设富含精氨酸的U1-70K在缺乏精氨酸的前列腺肉芽肿中是异常的，产生启动自身免疫的隐性表位。在目的1中，将通过氨基酸分析来检查精氨酸是否在蛋白酶处理的小鼠中缺乏。精氨酸代谢（摄取、消耗和再转化）也将被评估。在Aim 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条件下和L-canavanine存在下体外合成的U1-70K的修饰性。也将检测前列腺素处理小鼠细胞中的U1-70K。在Aim 3中，将通过纯化UlsnRNPs或来源于这些疾病的凋亡细胞免疫小鼠来研究异常UlsnRNPs（精氨酸缺乏，L-canavanine containing）是否可以触发特异性自身免疫反应。

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.