CHROMOSOME 6P AND DEVELOPMENTAL DEFECTS

系统性红斑狼疮（SLE）是一种自身免疫性疾病，在美国影响超过20万名妇女，其特征是抗核抗体和肾小球肾炎的高发病率。 SLE的主要危险因素是早期经典途径补体成分C1、C2或C4的缺乏。 这种关联提出了一个悖论，因为免疫缺陷不会导致自身免疫性疾病。 一种解释是，早期补体参与维持B细胞耐受性，并且在其缺乏时，自身反应性B细胞在外周中积累，在外周中它们可能被激活。 本提案的目的是检验这一假设，分为3个具体目标：（i）检验早期经典途径补体成分C1、C4和C3直接参与自身反应性B淋巴细胞的阴性选择的假设。 在此目的中使用的方法是用两种良好建立的免疫球蛋白转基因模型（抗HEL和抗dsDNA）繁殖C1、C4或C3缺陷的小鼠，并确定补体在B细胞无反应性中是否是必需的。(ii)第二个目的是在一个明确的狼疮小鼠模型（即lpr品系）中检验经典途径补体缺乏导致疾病严重程度增加的假设。 这个目标的优点是，它将检查早期补体在对天然狼疮抗原如dsDNA和核蛋白的自身免疫应答中的重要性。(iii)第三个目标是检验C4基因缺失小鼠中受损的自身耐受性可以通过蛋白质替代或基因治疗来挽救的假设，如果是这样，则比较C4A和C4B同种型。 还将使用连接至sHEL抗原的C4 d融合蛋白来将免疫复合物的增溶与抗原通过C4 d靶向淋巴区室解偶联，从而检查C4在B细胞耐受中的机制。 这一目标是重要的，因为它将建立蛋白质或基因治疗狼疮的可行性，并澄清我们对B细胞耐受性的理解。

Systemic lupus erythematosus (SLE) is an autoimmune disorder which affects over 200,000 women in the USA and it is characterized by anti-nuclear antibodies and a high incidence of glomerulonephritis. A major risk factor for SLE is deficiency in early classical pathway complement components C1, C2 or C4. This association presents a paradox because it is not expected that an immune deficiency would result in an autoimmune disease. One explanation is that early complement is involved in maintenance of B cell tolerance and in its absence, self-reactive B cells accumulate in the periphery where they potentially may be activated. The goal of this proposal is to test this hypothesis and it is divided into 3 specific aims: (i) Test the hypothesis that early classical pathway complement components C1, C4 and C3 are directly involved in negative selection of self-reactive B lymphocytes. The approach used in this aim is to breed mice deficient in C1, C4, or C3 with two well established immunoglobulin transgenic models (anti-HEL and anti-dsDNA) and determine if complement is essential in B cell anergy. (ii) The second aim will test the hypothesis that deficiency in classical pathway complement results in increased severity of disease in a well defined mouse model of lupus, i.e. lpr strain. The advantage of this aim is that it will examine the importance of early complement in the autoimmune response to natural lupus antigens such as dsDNA and nuclear proteins. (iii) The third aim will test the hypothesis that impaired self-tolerance in C4null mice can be rescued by protein replacement or gene therapy and if so compare C4A and C4B isotypes. It will also examine the mechanism of C4 in B cell tolerance using a fusion protein of C4d linked to sHEL antigen to uncouple solubilization of immune complexes from targeting of antigen to the lymphoid compartment via C4d. This aim is important as it will establish the feasibility of protein or gene therapy in lupus and clarify our understanding of B cell tolerance.