VNAR single-domain antibodies specific for BAFF inhibit B cell development by molecular mimicry.
VNAR single-domain antibodies specific for BAFF inhibit B cell development by molecular mimicry.
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DOI：
10.1016/j.molimm.2016.05.009
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发表时间：
2016-07
影响因子：
3.6
通讯作者：
Rutkowski JL
中科院分区：
文献类型：
--
作者：
Häsler J;Flajnik MF;Williams G;Walsh FS;Rutkowski JL
B细胞活化因子（BAFF）在B细胞稳态中起主导作用。然而，过量的BAFF促进自身反应性B细胞的发展，并且已经开发了几种抗体来阻断其活性。具有额外功能的双特异性抗体代表了下一波生物制剂，可能在治疗复杂的自身免疫性疾病方面更有效。来自免疫球蛋白新抗原受体（VNAR）的单个可变结构域是可以与单特异性抗体组合以开发双特异性试剂的最小抗体识别单元之一。我们从半合成噬菌体展示文库中分离出一组具有低nM效力的BAFF结合VNARs，并检查其功能活性。抗BAFF VNAR阻断了BAFF与其所有三种受体（BR3、TACI和BCMA）的结合，并且在CDR3区域中发现的保守DXL受体基序的存在表明分子模拟是拮抗作用的机制。将一个克隆格式化为Fc融合物用于功能测试，并且发现其在脾细胞增殖测定中以相等的离体效力抑制小鼠和人BAFF。在小鼠中，亚慢性给药减少了未成熟和过渡性中间B细胞和成熟B细胞亚群的数量。这些结果表明VNAR单结构域抗体作为选择性B细胞抑制剂发挥作用，并提供了靶向B细胞疾病的替代分子形式。
B cell-activating factor (BAFF) plays a dominant role in the B cell homeostasis. However, excessive BAFF promotes the development of autoreactive B-cells and several antibodies have been developed to block its activity. Bispecific antibodies with added functionality represent the next wave of biologics that may be more effective in the treatment of complex autoimmune disease. The single variable domain from the immunoglobulin new antigen receptor (VNAR) is one of the smallest antibody recognition units that could be combined with monospecific antibodies to develop bispecific agents. We isolated a panel of BAFF-binding VNARs with low nM potency from a semi-synthetic phage display library and examined their functional activity. The anti-BAFF VNARs blocked the binding of BAFF to all three of its receptors (BR3, TACI and BCMA) and the presence of the conserved DXL receptor motif found in the CDR3 regions suggests molecular mimicry as the mechanism of antagonism. One clone was formatted as an Fc fusion for functional testing and it was found to inhibit both mouse and human BAFF with equal potency ex vivo in a splenocyte proliferation assay. In mice, subchronic administration reduced the number of immature and transitional intermediates B cells and mature B cell subsets. These results indicate that VNAR single domain antibodies function as selective B-cell inhibitors and offer an alternative molecular format for targeting B-cell disorders.