Table_4_Transcriptional Analysis of the Human IgE-Expressing Plasma Cell Differentiation Pathway.xlsx

IgE is secreted by plasma cells (PCs) and is central to allergic disease. Using an ex vivo tonsil B cell culture system, which mimics the Th2 responses in vivo, we have recently characterized the development pathway of human IgE-expressing PCs. In this system, as in mice, we reported the predisposition of IgE-expressing B cells to differentiate into PCs. To gain a comprehensive understanding of the molecular events involved in the differentiation of human IgE+ B cells into PCs we have used the Illumina HumanHT-12 v4 Expression BeadChip array to analyse the gene expression profile of ex vivo generated human IgE+ B cells at various stages of their differentiation into PCs. We also compared the transcription profiles of IgE+ and IgG1+ cells to discover isotype-specific patterns. Comparisons of IgE+ and IgG1+ cell transcriptional profiles revealed molecular signatures specific for IgE+ cells, which diverge from their IgG1+ cell counterparts upon differentiation into PCs. At the germinal center (GC) stage of development, unlike in some mouse studies of IgE biology, we observed similar rates of apoptosis and no significant differences in the expression of apoptosis-associated genes between the IgE+ and IgG1+ B cells. We identified a gene interaction network associated with early growth response 1 (EGR1) that, together with the up-regulated IRF4, may account for the predisposition of IgE+ B cells to differentiate into PCs. However, despite their swifter rates of PC differentiation, the transcription profile of IgE+ PCs is more closely related to IgE+ and IgG1+ plasmablasts (PBs) than to IgG1+ PCs, suggesting that the terminal differentiation of IgE+ cells is impeded. We also show that IgE+ PCs have increased levels of apoptosis suggesting that the IgE+ PCs generated in our in vitro tonsil B cell cultures, as in mice, are short-lived. We identified gene regulatory networks as well as cell cycle and apoptosis signatures that may explain the diverging PC differentiation programme of these cells. Overall, our study provides a detailed analysis of the transcriptional pathways underlying the differentiation of human IgE-expressing B cells and points to molecular signatures that regulate IgE+ PC differentiation and function.

免疫球蛋白E（IgE）由浆细胞（plasma cells, PCs）分泌，在过敏性疾病中发挥核心致病作用。我们借助模拟体内2型辅助性T细胞（Th2）应答的离体扁桃体B细胞培养体系，近期阐明了人IgE阳性浆细胞的发育通路。正如小鼠模型中的研究结果，本体系中我们同样观察到IgE阳性B细胞易于分化为浆细胞的倾向性。为全面解析人IgE阳性B细胞向浆细胞分化过程中的分子事件，我们采用Illumina HumanHT-12 v4表达微珠芯片阵列，对离体培养获得的、处于向浆细胞分化不同阶段的人IgE阳性B细胞的基因表达谱进行了分析。我们还对IgE阳性与IgG1阳性细胞的转录谱进行了比对，以挖掘同种型特异性的表达模式。对两类细胞转录谱的比对结果显示，IgE阳性细胞具有特异性的分子特征，其在分化为浆细胞时与IgG1阳性对应细胞出现表达差异。在发育的生发中心（germinal center, GC）阶段，与部分针对IgE生物学特性的小鼠研究不同，我们观察到IgE阳性与IgG1阳性B细胞的细胞凋亡率相近，且凋亡相关基因的表达无显著差异。我们鉴定出一个与早期生长应答因子1（EGR1）相关的基因互作网络，该网络与上调表达的干扰素调节因子4（IRF4）协同，或可解释IgE阳性B细胞易于分化为浆细胞的倾向性。然而，尽管IgE阳性浆细胞的分化速度更快，但其转录谱与IgE阳性及IgG1阳性浆母细胞（PBs）的相关性，要高于与IgG1阳性浆细胞的相关性，这提示IgE阳性细胞的终末分化过程受到阻滞。我们还发现，IgE阳性浆细胞的细胞凋亡水平升高，表明我们通过体外扁桃体B细胞培养获得的IgE阳性浆细胞，与小鼠模型中的情况一致，均为寿命较短的细胞群体。我们鉴定出的基因调控网络、细胞周期及细胞凋亡特征，或可解释这类细胞分化为浆细胞的异常程序。综上，本研究对人IgE阳性B细胞向浆细胞分化的转录调控通路进行了详尽解析，并揭示了调控IgE阳性浆细胞分化与功能的分子特征。