Graduate Group in Immunology, University of California, Davis, Davis, CA.
Center for Immunology and Infectious Diseases, University of California, Davis, Davis, CA.
J Immunol. 2023 Sep 15;211(6):994-1005. doi: 10.4049/jimmunol.2200890.
Long-lived T-dependent B cell responses fail to develop during persistent infection of mice with Borrelia burgdorferi, the causative agent of Lyme disease, raising questions about the induction and/or functionality of anti-B. burgdorferi adaptive immune responses. Yet, a lack of reagents has limited investigations into B. burgdorferi-specific T and B cells. We attempted two approaches to track B. burgdorferi-induced CD4 T cells. First, a B. burgdorferi mutant was generated with an influenza hemagglutinin (HA) peptide, HA111-119, inserted into the B. burgdorferi arthritis-related protein (Arp) locus. Although this B. burgdorferi arp::HA strain remained infectious, peptide-specific TCR transgenic CD4 T cells in vitro, or adoptively transferred into B. burgdorferi arp::HA-infected BALB/c mice, did not clonally expand above those of recipients infected with the parental B. burgdorferi strain or a B. burgdorferi mutant containing an irrelevant peptide. Some expansion, however, occurred in B. burgdorferi arp::HA-infected BALB/c SCID mice. Second, a (to our knowledge) newly identified I-Ab-restricted CD4 T cell epitope, Arp152-166, was used to generate Arp MHC class II tetramers. Flow cytometry showed small numbers of Arp-specific CD4 T cells emerging in mice infected with B. burgdorferi but not with Arp-deficient Borrelia afzelii. Although up to 30% of Arp-specific CD4 T cells were ICOS+PD-1+CXCR5+BCL6+ T follicular helper cells, their numbers declined after day 12, before germinal centers (GCs) are prominent. Although some Arp-specific B cells, identified using fluorochrome-labeled rArp proteins, had the phenotype of GC B cells, their frequencies did not correlate with anti-Arp serum IgG. The data suggest a failure not in the induction, but in the maintenance of GC T follicular helper and/or B cells to B. burgdorferi.
伯氏疏螺旋体（Borrelia burgdorferi）是导致莱姆病的病原体，在其持续感染小鼠的过程中，长寿命的 T 依赖性 B 细胞反应未能发育，这引发了对诱导和/或抗伯氏疏螺旋体适应性免疫反应的功能的质疑。然而，缺乏试剂限制了对伯氏疏螺旋体特异性 T 细胞和 B 细胞的研究。我们尝试了两种方法来跟踪伯氏疏螺旋体诱导的 CD4 T 细胞。首先，生成了一种伯氏疏螺旋体突变体，该突变体在关节炎相关蛋白（Arp）基因座中插入了流感血凝素（HA）肽 HA111-119。尽管这种伯氏疏螺旋体 arp::HA 菌株仍然具有传染性，但在体外或过继转移到伯氏疏螺旋体 arp::HA 感染的 BALB/c 小鼠中，肽特异性 TCR 转基因 CD4 T 细胞并未比感染亲本伯氏疏螺旋体菌株或含有无关肽的伯氏疏螺旋体突变体的受体克隆扩增。然而，在伯氏疏螺旋体 arp::HA 感染的 BALB/c SCID 小鼠中发生了一些扩增。其次，我们使用一种（据我们所知）新鉴定的 I-Ab 限制性 CD4 T 细胞表位 Arp152-166，生成了 Arp MHC 类 II 四聚体。流式细胞术显示，在感染伯氏疏螺旋体的小鼠中出现了少量的 Arp 特异性 CD4 T 细胞，但在感染 Arp 缺失的伯氏疏螺旋体 afzelii 的小鼠中没有出现。尽管高达 30%的 Arp 特异性 CD4 T 细胞是 ICOS+PD-1+CXCR5+BCL6+滤泡辅助 T 细胞，但在生发中心（GC）变得明显之前，它们的数量在第 12 天后下降。虽然使用荧光标记的 rArp 蛋白鉴定了一些 Arp 特异性 B 细胞，它们具有 GC B 细胞的表型，但它们的频率与抗 Arp 血清 IgG 无关。数据表明，不是在诱导方面，而是在维持 GC 滤泡辅助 T 细胞和/或 B 细胞对伯氏疏螺旋体的反应方面存在失败。
