Roy Bishnudeo, Neumann Ralf S, Snir Omri, Iversen Rasmus, Sandve Geir Kjetil, Lundin Knut E A, Sollid Ludvig M
Department of Immunology, Centre for Immune Regulation, University of Oslo, Oslo University Hospital, 0372 Oslo, Norway.
Department of Immunology, KG Jebsen Coeliac Disease Research Centre, University of Oslo, Oslo University Hospital, 0372 Oslo, Norway.
J Immunol. 2017 Jul 15;199(2):782-791. doi: 10.4049/jimmunol.1700169. Epub 2017 Jun 9.
Characterization of Ag-specific BCR repertoires is essential for understanding disease mechanisms involving humoral immunity. This is optimally done by interrogation of paired H chain V region (V) and L chain V region (V) sequences of individual and Ag-specific B cells. By applying single-cell high-throughput sequencing on gut lesion plasma cells (PCs), we have analyzed the transglutaminase 2 (TG2)-specific V:V autoantibody repertoire of celiac disease (CD) patients. Autoantibodies against TG2 are a hallmark of CD, and anti-TG2 IgA-producing gut PCs accumulate in patients upon gluten ingestion. Altogether, we analyzed paired V and V sequences of 1482 TG2-specific and 1421 non-TG2-specific gut PCs from 10 CD patients. Among TG2-specific PCs, we observed a striking bias in and gene usage, as well as pairing preferences with a particular presence of the pair. Selective and biased V:V pairing was particularly evident among expanded clones. In general, TG2-specific PCs had lower numbers of mutations both in V and V genes than in non-TG2-specific PCs. TG2-specific PCs using had particularly few mutations. Importantly, V segments paired with displayed proportionally low mutation numbers, suggesting that the low mutation rate among PCs is dictated by the BCR specificity. Finally, we observed selective amino acid changes in V and V and striking CDR3 length and J segment selection among TG2-specific pairs. Hence this study reveals features of a disease- and Ag-specific autoantibody repertoire with preferred V:V usage and pairings, limited mutations, clonal dominance, and selection of particular CDR3 sequences.
对抗原特异性B细胞受体库进行表征对于理解涉及体液免疫的疾病机制至关重要。通过对单个抗原特异性B细胞的重链V区（V）和轻链V区（V）序列进行配对分析，可实现最佳表征。通过对肠道病变浆细胞（PC）进行单细胞高通量测序，我们分析了乳糜泻（CD）患者的组织转谷氨酰胺酶2（TG2）特异性V:V自身抗体库。针对TG2的自身抗体是CD的一个标志，摄入麸质后，产生抗TG2 IgA的肠道PC在患者体内会积累。我们总共分析了来自10名CD患者的1482个TG2特异性和1421个非TG2特异性肠道PC的配对V和V序列。在TG2特异性PC中，我们观察到 和 基因使用存在显著偏差，以及特定 配对的偏好。在扩增克隆中，选择性和偏向性的V:V配对尤为明显。一般来说，TG特异性PC的V和V基因中的突变数量比非TG2特异性PC少。使用 的TG2特异性PC的突变特别少。重要的是，与 配对的V区段显示出成比例的低突变数量，这表明 PC中的低突变率是由BCR特异性决定的。最后，我们在TG2特异性 配对中观察到V和V的选择性氨基酸变化以及显著的CDR3长度和J区段选择。因此，本研究揭示了一种疾病和抗原特异性自身抗体库的特征，具有优先的V:V使用和配对、有限的突变、克隆优势以及特定CDR3序列的选择。
