Self-reactive B cells traverse a perfect storm of somatic mutagenesis to cause a virus-induced autoimmune disease. Self-reactive B cells traverse a perfect storm of somatic mutagenesis to cause a virus-induced autoimmune disease

The unexplained association between infection and autoimmune disease is strongest for hepatitis C virus-induced cryoglobulinemic vasculitis (HCV-CV). We traced the evolution of the pathogenic rheumatoid factor (RF) autoantibodies in four HCV-CV patients by deep single cell multi-omic analysis, revealing three sources of B cell somatic mutation converged to drive accumulation of a large disease causing clone. A sensitive method for quantifying low affinity binding revealed three recurring heavy/light chain combinations created byV(D)Jrecombination bound self IgG but not viral E2 antigen. Whole genome sequencing revealed accumulation of thousands of somatic mutations, at levels comparable to CLL and normal memory B cells, but with 1-2 corresponding to driver mutations found recurrently in B cell leukemia/lymphoma.V(D)Jhypermutation created autoantibodies with compromised solubility in complex with self-IgG. In this virus-induced autoimmune disease, infection promotes a perfect storm of somatic mutagenesis in the descendants of a single B cell Overall design: We performed single cell RNA sequencing analysis of CD19+CD20+B cells sorted from the blood of a patient with hepatitis C virus-induced cryoglobulinemic vasculitis (HCV-CV), after HCV clearance with direct acting anti-viral (DAA) therapy. Gene expression (10X 3’) and immunoglobulin receptor sequencing (RAGE-seq) were performed for each individual B cell.

感染与自身免疫病之间存在的未解关联，在丙型肝炎病毒（hepatitis C virus, HCV）诱导的冷球蛋白血症性血管炎（cryoglobulinemic vasculitis, HCV-CV）中表现最为显著。本研究通过深度单细胞多组学分析，追踪了4例HCV-CV患者体内致病性类风湿因子（rheumatoid factor, RF）自身抗体的演化历程，发现B细胞体细胞突变的三种来源共同驱动了致病克隆的大量扩增。通过一种可定量低亲和力结合的灵敏实验方法，研究发现经V(D)J重组（V(D)J recombination）产生的三种重复出现的重/轻链组合可结合自身IgG，但无法结合病毒E2抗原。全基因组测序结果显示，此类样本中积累了数千个体细胞突变，突变水平与慢性淋巴细胞白血病（chronic lymphocytic leukemia, CLL）及正常记忆B细胞相当，但其中1-2个为B细胞白血病/淋巴瘤中反复检出的驱动突变。V(D)J高突变使自身抗体与自身IgG形成的复合物溶解度下降。在这种病毒诱导的自身免疫病中，感染可触发单个B细胞后代发生体细胞突变的“完美风暴”效应。实验整体设计：本研究对1例经直接作用抗病毒药物（direct acting anti-viral, DAA）治疗清除HCV的HCV-CV患者外周血中分选得到的CD19+CD20+B细胞开展了单细胞RNA测序分析，并对每个单个B细胞同时进行基因表达（10X 3’端）及免疫球蛋白受体测序（RAGE-seq）。