IL-27-producing B cells in the antibody response

项目总结-抗体应答中产生IL-27的B细胞 基于我们的新发现，即B细胞可以被诱导表达高水平的IL-27（IL 27 p28/EBI 3异源二聚体）， 该计划将探索IL-27和产生IL-27的B的分子和细胞机制 细胞（B-27细胞）的类别转换抗体（Ab）反应。正如我们所说，B-27细胞塑造了 和T依赖性抗体应答的质量，包括由病毒感染引起的应答。正如我们所主张的，他们 作为“辅助”B细胞来增强其靶“效应”B细胞的功能，即，那些对抗原有反应的 并分化成IgG产生细胞。此类类别转换的Ab包括IgG 1，其直接中和 病毒，以及人IgG 3和小鼠IgG 2a/IgG 2c（IgG 2a），其具有额外的抗病毒效应子功能。 由于先天性和适应性免疫受体信号对它们的诱导的独特要求，B-27 细胞被策略性地定位以介导TLR配体在增强Ab应答中的有效作用。 我们假设B-27细胞以依赖于转录因子BATF 3的方式被诱导， 通过与IFNg合作来优化Ab反应，以促进细胞的增殖、存活和完全分化， 产生IgG的B细胞。这是基于我们令人信服的初步数据表明：（一）作为一个重要的 IL-27的来源，B细胞在用TLR配体引发然后用Tfh刺激后被诱导产生IL-27 细胞刺激物CD 154和IL-21;（ii）在IL 27 p28、Ebi 3或Batf 3中具有B细胞特异性缺陷的小鼠， IL-27产生和特异性IgG 2a应答;（iii）IL-27激活STAT，将CSR引导至IgG 2a，并促进 体外由CD 154和IL-21刺激的B细胞中的存活和浆细胞分化;和（iv）IL-27和IFNg 在体外共同促进B细胞生长和分化，相反，联合IL-27 R和IFN γ R缺乏 在B细胞中，消除特异性IgG 2 a应答并显著损害体内IgG 1应答。 为了检验我们的假设，我们将（目的1）表征在Tg（IL 27 p28-GFP）报告小鼠中诱导的B-27细胞， 通过牛痘病毒（VV）感染，其也用作多种疫苗的载体，或用 结合半抗原NP-CGG与明矾和TLR配体LPS混合，并测定B-27细胞的协同作用 在特异性IgG应答和潜在效应B细胞增殖、存活、CSR/SHM、浆细胞 和记忆B细胞分化。我们还将（目标2）解决的机制，潜在的作用，BATF 3 通过体外鉴定IL 27 p28基因座的顺式元件和配偶体转录因子来诱导IL 27 p28; 并分析B细胞BATF 3的诱导及其对B-27细胞生成和VV感染的Ab应答的影响 和NP-CGG/明矾/LPS体内。最后，我们将（目的3）分析B细胞IL-27 R和IFNgR的协同作用， 在响应体内VV感染和刺激而优化效应B细胞生长和分化中的信号 与CD 154和IL-21在体外;并解决潜在的机制，重点是它们在调节 STAT信号输出和基因表达。通过揭示B-27细胞的机制和功能， 将对理解IgG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.