Uncommon structural motifs dominate the antigen binding site in human autoantibodies reactive with basement membrane collagen.
Uncommon structural motifs dominate the antigen binding site in human autoantibodies reactive with basement membrane collagen.
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DOI：
10.1016/j.molimm.2016.07.004
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发表时间：
2016-08
影响因子：
3.6
通讯作者：
Clark AG
中科院分区：
文献类型：
--
作者：
Foster MH;Buckley ES;Chen BJ;Hwang KK;Clark AG
自身抗体在多种自身免疫性疾病中介导器官破坏，但其在患者中的起源仍然知之甚少。为了探索疾病相关自身抗体的遗传起源和结构，我们用人CD 34+造血干细胞移植免疫缺陷小鼠，并用IV型胶原蛋白α 3链的非胶原蛋白-1（NC 1）结构域免疫。该抗原在肺和肾中表达，并且在抗肾小球基底膜（GBM）肾炎和肺出血肾炎综合征（GPS）（原型人类器官特异性自身免疫性疾病）中被自身抗体靶向。使用Epstein巴尔病毒转化和细胞融合，回收六种人抗α 3（IV）NC 1胶原单克隆自身抗体（mAb），包括与人肾反应的亚群和与患者IgG识别的表位反应的亚群。序列分析显示，在所有6种mAb中，长至异常长的重链互补决定区3（HCDR 3）是抗原结合的主要位点。平均HCDR 3长度为25.5个氨基酸（范围20-36），由固有的长DH和JH基因以及非模板化N-核苷酸的延伸区域产生。长HCDR 3适合于形成非连续抗原接触并结合隐藏于常规抗体的凹陷的免疫学沉默表位，如用自身抗原交叉反应性广泛中和抗HIV IG（bnAb）所见。抗-α 3（IV）NC 1胶原mAb还显示优先使用未突变的可变区基因，所述未突变的可变区基因在与天然多反应性IG共有特征的人慢性淋巴细胞白血病抗体中富集。我们的研究结果表明，致病性抗胶原蛋白IG，bnAb，和自身反应性IG与恶性肿瘤，所有这些都产生于B细胞表达的非常规结构元素，可能需要短暂的逃避成功的扩张的耐受性之间的关系。
Autoantibodies mediate organ destruction in multiple autoimmune diseases, yet their origins in patients remain poorly understood. To probe the genetic origins and structure of disease-associated autoantibodies, we engrafted immunodeficient mice with human CD34+ hematopoietic stem cells and immunized with the non-collagenous-1 (NC1) domain of the alpha3 chain of type IV collagen. This antigen is expressed in lungs and kidneys and is targeted by autoantibodies in anti-glomerular basement membrane (GBM) nephritis and Goodpasture syndrome (GPS), prototypic human organ-specific autoimmune diseases. Using Epstein Barr virus transformation and cell fusion, six human anti-alpha3(IV)NC1 collagen monoclonal autoantibodies (mAb) were recovered, including subsets reactive with human kidney and with epitopes recognized by patients’ IgG. Sequence analysis reveals a long to exceptionally long heavy chain complementarity determining region3 (HCDR3), the major site of antigen binding, in all six mAb. Mean HCDR3 length is 25.5 amino acids (range 20–36), generated from inherently long DH and JH genes and extended regions of non-templated N-nucleotides. Long HCDR3 are suited to forming noncontiguous antigen contacts and to binding recessed, immunologically silent epitopes hidden from conventional antibodies, as seen with self-antigen crossreactive broadly neutralizing anti-HIV Ig (bnAb). The anti-alpha3(IV)NC1 collagen mAb also show preferential use of unmutated variable region genes that are enriched among human chronic lymphocytic leukemia antibodies that share features with natural polyreactive Ig. Our findings suggest unexpected relationships between pathogenic anti-collagen Ig, bnAb, and autoreactive Ig associated with malignancy, all of which arise from B cells expressing unconventional structural elements that may require transient escape from tolerance for successful expansion.