Alterations in germinal center formation and B cell activation during severe Orientia tsutsugamushi infection in mice.
Alterations in germinal center formation and B cell activation during severe Orientia tsutsugamushi infection in mice.
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小鼠严重的东方tsutsugamushi感染期间生发中心形成和B细胞活化的改变。
DOI：
10.1371/journal.pntd.0011090
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发表时间：
2023-05
影响因子：
3.8
通讯作者：
中科院分区：
文献类型：
--
作者：
森林斑疹伤寒是由细胞内的东方体(OT)引起的一种研究较少但危及生命的疾病。OT感染患者的细胞和体液免疫不是持久的，早在感染后一年就会减弱；然而，其潜在的机制尚不清楚。到目前为止，还没有研究检查OT感染的人或实验动物的生发中心(GC)或B细胞反应。这项研究旨在评估重症OT感染急性期的体液免疫反应和B细胞功能障碍的可能机制。在接种OTKarp后，我们检测了抗原特异性抗体效价，发现IgG2c是感染引起的主要同型。通过免疫组织学、B细胞(B220)、T细胞(CD3)和GCs(GL-7)共染色来评估脾GC反应。感染后第4天(D4)可见有机化的GC，第8天几乎不见，并伴有散在分布于脾组织的T细胞。流式细胞术显示D4和D8的GC B细胞和T滤泡辅助(TFH)细胞数量相当，表明GC的崩溃不是由于D8时这些细胞亚型的过度死亡所致。B细胞RNAseq分析显示，与B细胞黏附和共刺激相关的基因在D8和D4的表达有显著差异。S1PR2(一种GC特异性黏附基因)的显著下调在D8时最为明显，这与GC的形成中断有关。信号通路分析发现，在D8时，71%的B细胞激活基因下调，这表明在严重感染期间B细胞的激活减弱。这是首次研究OT感染时B/T细胞微环境的破坏和B细胞反应的失调，这可能有助于理解与斑疹伤寒相关的一过性免疫。森林斑疹伤寒是一种未被充分研究的疾病，它是由细胞内的恙虫病杆菌引起的。丛林斑疹伤寒的一个特征是感染后无法解释的、不可持久的免疫力。虽然已知细胞免疫反应对控制这种感染很重要，但我们对B细胞和GC反应的了解仍然有限。在这项研究中，我们使用我们最近建立的严重斑疹伤寒小鼠模型，检测了B细胞的激活和GC反应。我们检测了细菌抗原特异性抗体效价，并确定干扰素-γ驱动的Ig G亚型为主要的Ig G亚型。我们还发现，钩端螺旋体感染破坏了脾的形态，表现为T细胞随机分散和GC结构丢失。对纯化的脾B细胞的转录分析表明，在严重感染阶段，编码关键黏附和共刺激分子的基因，包括GC黏附基因S1PR2的表达减少。在感染过程中，与B细胞受体信号转导、B细胞激活和分化相关的几条体液免疫反应通路显著下调。这项研究是首次报道森林斑疹伤寒小鼠模型的体液免疫，并提供了B细胞和GC反应在急性感染期间受损的详细证据。
Scrub typhus is a poorly studied but life-threatening disease caused by the intracellular bacterium Orientia tsutsugamushi (Ot). Cellular and humoral immunity in Ot-infected patients is not long-lasting, waning as early as one-year post-infection; however, its underlying mechanisms remain unclear. To date, no studies have examined germinal center (GC) or B cell responses in Ot-infected humans or experimental animals. This study was aimed at evaluating humoral immune responses at acute stages of severe Ot infection and possible mechanisms underlying B cell dysfunction. Following inoculation with Ot Karp, a clinically dominant strain known to cause lethal infection in C57BL/6 mice, we measured antigen-specific antibody titers, revealing IgG2c as the dominant isotype induced by infection. Splenic GC responses were evaluated by immunohistology, co-staining for B cells (B220), T cells (CD3), and GCs (GL-7). Organized GCs were evident at day 4 post-infection (D4), but they were nearly absent at D8, accompanied by scattered T cells throughout splenic tissues. Flow cytometry revealed comparable numbers of GC B cells and T follicular helper (Tfh) cells at D4 and D8, indicating that GC collapse was not due to excessive death of these cell subtypes at D8. B cell RNAseq analysis revealed significant differences in expression of genes associated with B cell adhesion and co-stimulation at D8 versus D4. The significant downregulation of S1PR2 (a GC-specific adhesion gene) was most evident at D8, correlating with disrupted GC formation. Signaling pathway analysis uncovered downregulation of 71% of B cell activation genes at D8, suggesting attenuation of B cell activation during severe infection. This is the first study showing the disruption of B/T cell microenvironment and dysregulation of B cell responses during Ot infection, which may help understand the transient immunity associated with scrub typhus. Scrub typhus is an understudied disease caused by the intracellular bacterium O. tsutsugamushi. A hallmark of scrub typhus is the unexplained, non-durable immunity after infection. While cellular immune responses are known to be important for controlling this infection, our understanding of B cell and GC responses remains limited. In this study, we examined B cell activation and GC responses using our recently established murine model of severe scrub typhus. We measured bacterial antigen-specific antibody titers and identified IgG2c, an IFN-γ-driven isotype, as the major IgG subtype. We also found that O. tsutsugamushi infection disrupted spleen morphology, exemplified by randomly dispersed T cells and lost GC structures. Transcriptomic analysis of purified splenic B cells demonstrated reduced expression of genes encoding critical adhesion and co-stimulation molecules, including GC-adhesion gene S1PR2, at severe stages of infection. Several humoral immune response pathways relevant to B cell receptor signaling, B cell activation and differentiation were significantly downregulated during infection. This study is the first report describing humoral immunity in a scrub typhus mouse model and provides detailed evidence that B cell and GC responses are impaired during acute infection.
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DOI：
10.1093/bioinformatics/btu638
发表时间：
2015-01-15
期刊：
Bioinformatics (Oxford, England)
影响因子：
--
作者：
Anders S;Pyl PT;Huber W
通讯作者：
Huber W
影响因子：
2.9
作者：
Jiang J;Richards AL
通讯作者：
Richards AL
影响因子：
3.3
作者：
Hwang, Joo-Hee;Hwang, Jeong-Hwan;Lee, Chang-Seop
通讯作者：
Lee, Chang-Seop
影响因子：
16.6
作者：
通讯作者：
--
影响因子：
13.2
作者：
Ha, Na-Young;Kim, Yuri;Cho, Nam-Hyuk
通讯作者：
Cho, Nam-Hyuk