IL-27-producing B cells in the antibody response

项目摘要-抗体反应中产生IL-27的B细胞 基于我们的新发现，B细胞可以被诱导表达高水平的IL-27(IL27p28/EBI3异源二聚体)， 这项建议将探索IL-27和产生IL-27的B细胞作用的分子和细胞机制 类转换抗体(Ab)反应中的细胞(B-27细胞)。正如我们所争辩的，B-27细胞决定了 以及T依赖的抗体反应的质量，包括由病毒感染引起的反应。正如我们还争辩的那样，他们 作为“辅助”B细胞来增强其目标“效应”B细胞的功能，即那些对抗原有反应的B细胞 并分化为产生免疫球蛋白的细胞。这种类别切换的抗体包括IgG1，它直接中和 病毒，以及人IgG3和小鼠IgG2a/IgG2c(IgG2a)，具有额外的抗病毒效应功能。 由于先天免疫受体信号和获得性免疫受体信号诱导的独特要求，B-27 细胞处于战略地位，以介导TLR配体在增强抗体反应中的强大作用。 我们假设B-27细胞是以依赖于转录因子BATF3的方式诱导的，并且 协同IFNG优化抗体应答，促进细胞增殖、存活和充分分化 产生免疫球蛋白的B细胞。这是基于我们令人信服的初步数据表明：(I)作为一个重要的 IL-27的来源，B细胞经TLR配体激活后经Tfh刺激后产生IL-27 细胞刺激CD154和IL-21；(Ii)B细胞特异性Il27p28、EBI3或BATF3基因缺陷小鼠在 IL-27的产生和特异性的IgG2a反应；(Iii)IL-27激活STATS，将CSR导向IgG2a并促进 CD154和IL-21体外刺激B细胞存活和浆细胞分化；以及(Iv)IL-27和IFNG 共同促进B细胞体外生长和分化，反之，联合IL-27R和IFNgR缺陷 在B细胞中消除特异性的IgG2a反应，并显著削弱体内的IgG1反应。 为了验证我们的假设，我们将(目标1)表征在TG(Il27p28-GFP)报告小鼠中诱导的B-27细胞 由痘苗病毒(VV)感染，该病毒也被用作各种疫苗的载体，或免疫 结合型半抗原NP-CGG与明矾和TLR配体脂多糖混合；测定B-27细胞的协同作用 IFNG在特异性免疫球蛋白应答和潜在效应B细胞增殖、存活、CSR/SHM、浆细胞中的作用 和记忆B细胞分化。我们还将(目标2)讨论BATF3的潜在作用机制 在体外通过鉴定其在Il27p28基因座上的顺式元件和配对转录因子进行诱导； 分析B细胞BATF3的诱导及其对病毒感染B-27细胞生成和抗体应答的影响 体内注射NP-CGG/明胶/脂多糖。最后，我们将(目标3)分析B细胞IL-27R和IFNgR的协同作用 体内VV感染和刺激下优化效应B细胞生长和分化的信号 CD154和IL-21在体外的相互作用；并阐述其潜在的机制，重点是它们在调控中的协同作用 STAT信号输出和基因表达。通过揭示B-27细胞的机制和功能，我们的研究 将对了解免疫球蛋白对病毒感染的反应和疫苗开发产生持续的影响。

PROJECT SUMMARY – IL-27-producing B cells in the antibody response Built on our novel findings that B cells can be induced to express high levels of IL-27 (IL27p28/EBI3 heterodimer), this proposal will explore molecular and cellular mechanisms underlying the role of IL-27 and IL-27-producing B cells (B-27 cells) in class-switched antibody (Ab) responses. As we contend, B-27 cells shape the magnitude and quality of T-dependent Ab responses, including those elicited by viral infections. As we also contend, they do so as “helper” B cells to enhance the function of their target “effector” B cells, i.e., those responding to antigens and differentiating into IgG-producing cells. Such class-switched Abs include IgG1, which directly neutralizes virus, and human IgG3 and mouse IgG2a/IgG2c (IgG2a), which have additional anti-viral effector functions. Owing to the unique requirement of both innate and adaptive immune receptor signals for their induction, B-27 cells are strategically positioned to mediate the potent effect of TLR ligands in boosting the Ab response. We hypothesize that B-27 cells are induced in a manner dependent on transcription factor BATF3, and optimize the Ab response by cooperating with IFNg to promote proliferation, survival and full differentiation of IgG-producing B cells. This is based on our compelling preliminary data indicating that: (i) as an important source of IL-27, B cells are induced to produce IL-27 after priming by TLR ligands and then stimulation by Tfh cell stimuli CD154 and IL-21; (ii) mice with B cell-specific deficiency in Il27p28, Ebi3 or Batf3 are impaired in IL-27 production and specific IgG2a responses; (iii) IL-27 activates STATs, directs CSR to IgG2a and promotes survival and plasma cell differentiation in B cells stimulated by CD154 and IL-21 in vitro; and (iv) IL-27 and IFNg together boost B cell growth and differentiation in vitro, and, conversely, combined IL-27R and IFNgR deficiency in B cells abrogates specific IgG2a responses and significantly impairs IgG1 responses in vivo. To test our hypothesis, we will (Aim 1) characterize B-27 cells induced in Tg(Il27p28-Gfp) reporter mice upon infection by vaccinia virus (VV), which is also used as a vector of a variety of vaccines, or immunization with conjugated hapten NP-CGG mixed with alum and TLR ligand LPS; and determine the cooperation of B-27 cells with IFNg in specific IgG responses and underlying effector B cell proliferation, survival, CSR/SHM, plasma cell and memory B cell differentiation. We will also (Aim 2) address the mechanisms underlying the role of BATF3 in Il27p28 induction by identifying its cis-elements in the Il27p28 locus and partner transcription factors in vitro; and analyze induction of B cell BATF3 and its impact on B-27 cell generation and Ab responses to VV infection and NP-CGG/alum/LPS in vivo. Finally, we will (Aim 3) analyze the cooperation of B-cell IL-27R and IFNgR signals in optimizing effector B cell growth and differentiation in response to VV infection in vivo and stimulation with CD154 and IL-21 in vitro; and address the underlying mechanisms, focusing on their synergy in regulating STAT signal outputs and gene expression. By unveiling the mechanisms and function of B-27 cells, our studies will have a sustained impact on the understanding of IgG responses to viral infections and vaccine development.