Antigen and lysophospholipid receptor regulation of lymphocyte development and fu

描述（由申请人提供）：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，抑制BCR信号和随后的抗体反应。LPA以低纳摩尔亲和力与LPA受体结合并发出信号，并且作为一种主要的溶血磷脂存在于血液中，浓度从高纳摩尔到低微摩尔。然而，尽管淋巴细胞表达几种LPA受体；对于LPA如何影响体液免疫的了解相对较少。我们研究的一个长期目标是了解bcr衍生的信号如何与通过gpcr（如趋化受体）传递的信号相交，并且该应用的目标是定义通过LPA受体在B系细胞上的LPA信号如何调节B淋巴细胞的发育和功能。LPA也被认为是一种炎症性脂质，其水平在许多慢性炎症性疾病（如癌症、自身免疫和病毒感染）中相当高。我们发现，在LPA水平升高的情况下，BCR信号进一步受到抑制。因此，我们还研究了LPA的病理生理水平如何改变骨髓中B细胞耐受诱导和边缘区和滤泡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，这些实验依赖于具有良好特征的B细胞耐受性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及其作为成熟B细胞在外周血中的功能。这些实验概述如下：目的1：表征LPA如何调节未成熟B细胞的发育和耐受性诱导。1一个。这些实验探讨LPA受体信号传导如何影响B淋巴生成，以及病理性LPA水平是否改变中央B细胞耐受性。目的2：表征导致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信号传导的信号通路。特别是，我们确定抗原特异性B细胞反应是否被所有抗原或仅具有一定（弱）亲和力的抗原抑制。目的3：描述局部autotaxin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设置是否改变其表达的调节。这些实验旨在确定局部限制性LPA产生与全局系统性LPA水平在调节B细胞抗体反应中的相对贡献，以及LPA产生如何在炎症和自身免疫环境中改变。的意义。鞘氨醇-1-磷酸（S1P）溶血磷脂已成为淋巴细胞发育、运输和定位的关键调节因子。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）。与在体内平衡条件下起重要作用的S1P相反，LPA具有炎性脂质的特征，并与慢性炎性疾病有关。值得注意的是，LPA如何调节免疫功能，特别是体液免疫，在很大程度上尚未被探索。这些实验的成功完成有望说明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受体信号传导与许多不同类型的癌症有关，并因可能的治疗干预而受到相当大的关注，因此这些发现也将是重要的

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.