Alpha-Actinin:Renal Pathogenicity of anti-DNA Antibodies

描述(申请人提供)：抗双链抗体(DS) DNA是系统性红斑狼疮特有的血清学标志。虽然它一直是 证明了抗dsDNA抗体在 狼疮性肾炎的发病机制，损伤机制尚不完全 明白了。实验证据有力地表明，至少有一些 抗dsDNA抗体因其直接的交叉反应而致病。 与肾脏抗原有关。我们最近证明了一种致病的抗双链DNA 抗体(R4A)与细胞表面表达的100kD蛋白结合 红斑狼疮易感MRL-LPR/LPR小鼠来源的系膜细胞系 DNA酶处理裂解物不影响结合。在很大程度上， 非自身免疫性肾小球系膜细胞系裂解产物减少 小鼠，提示抗原的表达和/或可用性在 靶器官可能是决定狼疮易感性的一个因素。 肾炎。R4A结合的100kD蛋白鉴定为AS α-肌动蛋白，Western证实R4A与α-肌动蛋白结合 印迹、酶联免疫吸附试验和抑制试验。高滴度的抗α-肌动蛋白 在狼疮小鼠的血清和肾洗脱液中发现抗体 肾炎，以及狼疮患者的血清中。 这项提议的目标是研究是否与α-肌动蛋白发生交叉反应 可能是某些抗DNA抗体肾脏致病性的重要决定因素 抗体，如果α-肌动蛋白的表达受基因调控和 受性别和接触细胞因子的影响。我们将确定是否 抗α-肌动蛋白抗体是致病的，如果它们与 DsDNA，用α-肌动蛋白免疫小鼠，并研究 正常小鼠和自身免疫小鼠的抗α-肌动蛋白抗体反应。这个 α-肌动蛋白抗原展示水平差异的分子基础 将研究自身免疫和非自身免疫小鼠品系之间的关系，以及 年龄、性别和已知狼疮肾脏中存在的细胞因子对 将测定α-肌动蛋白的表达和抗体结合力。最后，我们 将确定致病原识别的α-肌动蛋白表位 抗dsDNA抗体了解抗α-肌动蛋白的产生 抗体，并确定α-肌动蛋白多肽在小鼠体内的潜力 急性狼疮性肾炎的治疗。

DESCRIPTION (provided by applicant): Antibodies against double stranded (ds) DNA are a characteristic serologic hallmark of SLE. While it has been demonstrated that anti-dsDNA antibodies play a critical role in the pathogenesis of lupus nephritis, the mechanisms of injury are incompletely understood. Experimental evidence strongly suggests that at least some anti-dsDNA antibodies are pathogenic by virtue of their direct cross-reactivity with renal antigen. We recently demonstrated that a pathogenic anti-dsDNA antibody (R4A) binds to a 100 kD protein expressed on the cell surface of a mesangial cell line derived from a lupus-prone MRL-lpr/lpr mouse, and that DNAse treatment of the lysate does not affect binding. Binding was greatly diminished in lysates of a mesangial cell line derived from a non-autoimmune mouse, suggesting that antigen expression and/or availability at the level of the target organ may be a factor in determining susceptibility to lupus nephritis. Following identification of the 100 kD protein bound by R4A as alpha-actinin, the binding of R4A to alpha-actinin was confirmed by Western blot, ELISA, and inhibition studies. High titers of anti-alpha-actinin antibodies were found in the serum and kidney eluates of lupus mice with nephritis, and in the serum of lupus patients. The goals of this proposal are to study if cross-reactivity with alpha-actinin may be an important determinant of the renal pathogenicity of some anti-DNA antibodies, and if the expression of alpha-actinin is genetically regulated and modulated by gender and exposure to cytokines. We will determine if anti-alpha-actinin antibodies are pathogenic and if they cross-react with dsDNA, by immunization of mice with alpha-actinin and studying the anti-alpha-actinin antibody response in normal and autoimmune mice. The molecular basis for the differential levels of antigen display of alpha-actinin between autoimmune and non-autoimmune mouse strains will be studied, and the effects of age, gender, and cytokines known to be present in lupus kidneys on alpha-actinin expression and antibody binding will be determined. Finally, we will identify the epitopes of alpha-actinin that are recognized by pathogenic anti-dsDNA antibodies to understand the generation of anti-alpha-actinin antibodies, and determine the potential of alpha-actinin peptides in the treatment of acute lupus nephritis.