Antigen and lysophospholipid receptor regulation of lymphocyte development and fu

描述(申请人提供)：B细胞抗原受体(BCR)信号控制B淋巴细胞的发育、选择和功能。我们实验室的工作已经确定，溶血磷脂，溶血磷脂酸(LPA)，向B系细胞表达的LPA5 G蛋白偶联受体发出信号，以抑制BCR信号和随后的抗体反应。LPA以低纳摩尔亲和力与LPA受体结合并传递信号，作为一种主要的溶血磷脂存在于血液中，以高纳摩尔到低微摩尔浓度存在。然而，尽管淋巴细胞表达几种LPA受体，但人们对LPA如何影响体液免疫知之甚少。我们研究的一个长期目标是了解BCR来源的信号如何与那些通过化学吸引受体等GPCRs传递的信号相交，这一应用的目标是确定通过B系细胞上的LPA受体的LPA信号如何调节B淋巴细胞的发育和功能。LPA也被认为是一种炎性脂质，在一些慢性炎症性疾病中，如癌症、自身免疫和病毒感染，其水平显著升高。我们发现，在这些升高的LPA水平，BCR信号被进一步抑制。因此，我们还研究了LPA的病理生理水平如何改变骨髓中B细胞耐受的诱导以及边缘带和滤泡B细胞群的抗体反应。为了解决这些问题，我们提出了体外和体内实验，依赖于具有良好特性的B细胞耐受和抗体反应的小鼠模型，以阐明LPA受体在B淋巴细胞在骨髓中的发育过程中的作用(S)以及它们作为外围成熟B细胞的功能。这些实验的具体目标概括如下：目标1：表征LPA如何调控未成熟B细胞的发育和耐受诱导。1A.确定LPA受体是否引导未成熟B细胞在骨髓中的定位在这些实验期间，询问LPA受体信号如何影响B淋巴细胞的生成，以及病理性LPA水平是否改变中央B细胞的耐受性。目的2：研究LPA抑制B细胞抗体反应的分子和细胞机制。在这里，我们定义了LPA调节B细胞反应的程度，以及LPA受体用来抑制BCR信号的信号通路。特别是，我们确定抗原特异性B细胞反应是被所有抗原抑制，还是只被某些(弱)亲和力的抗原抑制。目的3：研究局部自体趋化蛋白的表达如何影响LPA对B细胞反应的调节，以及炎症和自身免疫环境是否改变其表达的调节。这些实验旨在确定局部限制的LPA产生与全球全身性LPA水平在调节B细胞抗体反应中的相对贡献，以及在炎症和自身免疫环境中LPA产生可能如何改变。意义重大。鞘氨醇-1-磷酸(S1P)溶血磷脂是淋巴细胞发育、运输和定位的重要调节因子。然而，淋巴细胞和免疫系统的大多数其他细胞也表达G蛋白偶联受体，该受体识别另一种主要的溶血磷脂-溶血磷脂酸(LPA)。与在动态平衡条件下发挥重要作用的S1P不同，LPA具有炎性脂质的特征，并与慢性炎症性疾病有关。值得注意的是，LPA如何调节免疫功能，特别是体液免疫，在很大程度上还没有被探索。这些实验的成功完成有望阐明LPA如何调节B淋巴细胞的发育、选择和抗体反应。此外，由于LPA-LPA受体信号与许多不同类型的癌症有关，并在可能的治疗干预方面受到了相当大的关注，这些发现也将是重要的。 告知这些策略可能如何改变适应性免疫。

DESCRIPTION (provided by applicant): B cell antigen receptor (BCR) signaling controls the development, selection and function of B lymphocytes. Work in our lab has determined that the lysophospholipid, lysophosphatidic acid (LPA), signals to the LPA5 G-protein coupled receptor expressed by B lineage cells to suppress BCR signaling and subsequent antibody response. LPA binds and signals to LPA receptors with low nanomolar affinity and as a major lysophospholipid is present in blood at high nanomolar to low micromolar concentrations. However, despite that lymphocytes express several LPA receptors; relatively little is understood about how LPA influences humoral immunity. A long-term goal of our research has been to understand how BCR-derived signals intersect with those signals transmitted via GPCRs such as chemoattractant receptors and the goal of this application is to define how LPA signaling through LPA receptors on B lineage cells regulates the development and function of B lymphocytes. LPA has also been characterized as an inflammatory lipid and whose levels are considerably elevated in a number of chronic inflammatory disorders such as cancer, autoimmunity and viral infections. We show that at these heightened LPA levels BCR signaling is further inhibited. Thus, we also investigate how pathophysiological levels of LPA alter B cell tolerance induction in the bone marrow and antibody responses by marginal zone and follicular B cell populations. To address these issues, we propose in vitro and in vivo experiments that rely on well-characterized mouse models of B cell tolerance and antibody response to elucidate the role(s) of LPA receptors on B lymphocytes during their development in the bone marrow and their function as mature B cells in the periphery. These experiments are outlined in the following Specific Aims: Aim 1: Characterize how LPA regulates immature B cell development and tolerance induction. 1A. Establish if LPA receptors guide immature B cell localization in the bone marrow during These experiments ask how LPA receptor signaling influence B lymphopoeisis and if pathological LPA levels alters central B cell tolerance. Aim 2: Characterize the molecular and cellular mechanisms that lead to LPA suppression of B cell antibody responses. Here we define the extent to which LPA regulates B cell responses and the signaling pathways used by LPA receptors to inhibit BCR signaling. In particular, we determine if antigen-specific B cell responses are suppressed by all antigens or only antigens with certain (weak) affinity. Aim 3: Characterize how local autotaxin expression influences LPA regulation of B cell responses and if inflammatory and autoimmune settings alter the regulation of its expression. These experiments are designed to define the relative contributions of locally-restricted LPA production versus global systemic LPA levels in regulating the B cell antibody response and how LPA production may be altered in inflammatory and autoimmune settings. Significance. The sphingosine-1-phosphate (S1P) lysophospholipid has emerged as a critical regulator of lymphocyte development, trafficking and localization. However, lymphocytes and most other cells of the immune system also express G-protein coupled receptors that recognize another major lysophospholipid, lysophosphatidic acid (LPA). In contrast to S1P, that serves an important role under homeostatic conditions, LPA has features of an inflammatory lipid and has been associated with a chronic inflammatory disorders. Notably, how LPA regulates immune function and, specifically, humoral immunity is largely unexplored. The successful completion of these experiments is expected to illustrate how LPA functions to regulate the development, selection and antibody response by B lymphocytes. Furthermore, as LPA-LPA receptor signaling has been associated with a number of different types of cancer and has received considerable attention for possible therapeutic intervention, these findings will also be important to inform on how such strategies might alter adaptive immunity.