B Cell Developmental Defect in Murine Lupus

描述（由研究者提供）：在NZ B/WF 1模型中描述了多个B细胞缺陷，但其在狼疮发病机制中的具体作用尚不清楚，超出了其作为自身抗体产生者的作用。限制因素之一是需要复杂的遗传背景，包括H-2 z等位基因，这限制了试剂的可用性和功能实验。我们已经产生了具有3个NZM 2410衍生的Sle基因组基因座的狼疮的新模型，所述基因座对于在B6背景下的疾病诱导是必要且足够的。这种三重同源B6.TC菌株由大约94%的B6基因组构成，但仍发展为完全渗透性狼疮性肾炎。B6.TC小鼠表现出与NZM 2410相同的B细胞发育缺陷，包括B1 a细胞在腹腔中蓄积和浆细胞在脾脏中蓄积，这是由于缺乏对CXCR 12的反应性，CXCR 12通常指导PC迁移到骨髓。我们建议使用B6. TC模型来描述这两种发育B细胞缺陷的遗传学和机制，并确定它们在狼疮发病机制中的作用。此外，我们建议在B6.TC上培育BCR Tg，以比较该菌株与FAS缺陷模型中B细胞耐受性的机制。为了实现这一目标，我们有三个具体目标：1。描述PerC B1 a在B6.TC小鼠中蓄积的机制，并评估其在发病机制中的作用。我们假设B6.TC小鼠中B1 a PerC蓄积是由内在B1 a细胞缺陷和非B细胞区室的异常调节引起的。我们预测，这种调节涉及STAT 4信号转导，因为STAT 4缺陷会阻止PerC B1 a在B6.TC中的积累。将评估这些假设，并在该过程中评价每个Sle基因座的贡献。最后，我们将讨论PerC B1 a细胞对自体抗体产生和混合BM嵌合体临床的贡献。2.确定导致B6.TC脾脏中PC蓄积的功能和遗传机制。我们假设这种缺陷是由PC分化过程中内在的B细胞缺陷和非B细胞因子造成的，这些非B细胞因子创造了“生存小生境”，支持脾脏中大量长寿PC的维持。我们认为这些因子涉及CD 40 L和IL-4，它们由B6.TC T细胞过表达。此外，STAT 6缺陷恢复正常的B6.TC PC迁移到脾脏。我们建议测试这些假设，并评估每个SLE基因座在这个过程中的贡献。3.使用RF特异性AM 14 H转基因模型确定B细胞耐受性丧失的机制。B6.TC小鼠自发产生类风湿因子。我们建议使用产生抗IgG 2aa RF的AM 14 H Tg来探索B6. TC模型中B细胞耐受性丧失的机制，与FAS缺陷模型中描述的机制进行比较。该B6.TC.AM14将构成追踪FAS完整自身免疫模型中自身反应性B细胞的命运和发展的非常有价值的工具。

DESCRIPTION (provided by investigator): Multiple B cell defects have been described in the NZB/WF1 model, but their specific role in lupus pathogenesis is unclear, beyond their role as autoantibody producers. One of the limiting factors has been the requirement of a complex genetic background, including the H-2z allele, which has restricted reagent availability and functional experiments. We have produced a new model of lupus with the 3 NZM2410-derived Sle genomic loci that are necessary and sufficient for disease induction on a B6 background. This triple congenic B6.TC strain is constituted by approximately 94% of B6 genome, but yet develops a fully penetrant lupus nephritis. B6.TC mice show the same B cell developmental defects as NZM2410, which include an accumulation of B1a cells in the peritoneal cavity and a splenic accumulation of plasma cells, due to an absence of responsiveness to CXCR12, which normally directs PC migration to the bone marrow. We propose to use the B6.TC model to characterize the genetics and the mechanisms of these two developmental B cell defects, and determine their role in lupus pathogenesis. In addition, we propose to breed a BCR Tg on B6.TC to compare the mechanisms of B cell tolerance in that strain to that of the FAS-deficient model. To accomplish this goal, we have three specific aims: 1. To characterize the mechanisms of PerC B1a accumulation in B6.TC mice, and to assess its role in pathogenesis. We hypothesize that B1a PerC accumulation in B6.TC mice results from intrinsic B1a cell defects and from an abnormal regulation from a non-B cell compartment. We predict that this regulation involves STAT4 signaling as STAT4 deficiency prevents PerC B1a accumulation in B6.TC. These hypotheses will be assessed, and the contribution of each Sle locus will be evaluated in the process. Finally, we will address the contribution of PerC B1a cells to autoAb production and clinical with mixed BM chimeras. 2. To determine the functional and genetic mechanisms leading to PC accumulation in B6.TC spleens. We hypothesize this defect results from intrinsic B cell defects during PC differentiation and non-B cell factors that create "survival niches" that support the maintenance of large number of long-lived PC in the spleen. We propose that these factors involve CD40L and IL-4, which are over-expressed by B6.TC T cells. Moreover, STAT6 deficiency restores normal B6.TC PC migration to the spleen. We propose to test these hypotheses and assess the contribution of each Sle locus in the process. 3. To determine the mechanisms responsible for the loss of B cell tolerance using the RF-specific AM14 H transgenic model. B6.TC mice spontaneously produce rheumatoid factor. We propose to use the AM14 H Tg that produce anti-IgG2aa RF to explore the mechanisms of loss of B cell tolerance in the B6.TC model, comparatively to the mechanisms described in the FAS deficient model. This B6.TC.AM14 will constitute a very valuable tool to track the fate and development of autoreactive B cells in a FAS intact autoimmune model.