Genetic Regulation of B Lymphocyte Aortic Homing and Atheroprotection

描述（由申请人提供）：动脉粥样硬化是一种渐进性炎症过程，导致大动脉斑块形成。关于巨噬细胞和T细胞向血管壁的募集及其在斑块进展中的作用，我们已经知道很多。在整个疾病过程中，在动脉粥样硬化的人和动物模型中的斑块和外膜中已经鉴定出B细胞和浆细胞，并且已经显示整体B细胞缺乏促进鼠模型中的动脉粥样硬化。然而，调节主动脉B细胞归巢的因子以及这些因子的调节对动脉粥样硬化形成的影响仍然未知。利用细胞培养和动物研究，我们已经确定了螺旋-环-螺旋因子（HLH），Id 3，作为一种新的动脉粥样硬化保护因子，调节趋化因子受体的表达和主动脉归巢的B淋巴细胞，并证明Id 3是必不可少的B淋巴细胞介导的动脉粥样硬化保护。此外，我们最近已经确定了一个单核苷酸多态性（SNP）在人类ID 3基因编码的Id 3蛋白作为一个二聚化伴侣和显性负抑制剂的bHLH E-蛋白，E12的衰减功能。该SNP与人类颈动脉内膜中层厚度（cIMT）相关。具有编码Id 3：E12二聚化减弱的Id 3蛋白的次要等位基因的人具有cIMT（亚临床动脉粥样硬化的标志物）增加。将小鼠、人和生物化学数据结合在一起，使我们假设E12活性的丧失通过增加小鼠中趋化因子受体表达和增加B淋巴细胞的动脉归巢来促进动脉粥样硬化保护，并且导致人E12活性拮抗作用降低的人ID 3基因rs 11574（Id 3105 T）多态性允许抑制趋化因子受体表达，减少人B淋巴细胞的趋化性和动脉归巢。E12作为主动脉B淋巴细胞归巢和B淋巴细胞介导的动脉粥样硬化保护作用的关键调节因子的鉴定不仅对进一步研究以拓宽我们对动脉粥样硬化形成的免疫调节的理解范式很重要，而且还可能导致鉴定新的生物标志物（ID 3基因多态性）和促进人类动脉粥样硬化保护的创新策略。基于我们令人信服的初步数据，并利用新的试剂，我们提出了以下目标，以解决我们的假设：目的1：确定是否调节E12的表达调控CCR 6表面蛋白的表达和趋化性在B淋巴细胞。目标二：确定携带Id 3多态性的B淋巴细胞是否具有降低的CCR 6表达和降低的B淋巴细胞趋化性，Id 3多态性与E12拮抗作用减弱和人体cIMT增加相关。目标3：确定E12在体内对主动脉B细胞归巢和动脉粥样硬化保护的作用，并确定Id 3在rs 11574的多态性是否改变主动脉B细胞归巢。

DESCRIPTION (provided by applicant): Atherosclerosis is a progressive, inflammatory process leading to plaque formation in large arteries. Much is known about recruitment of macrophages and T cells to the vessel wall and their role in plaque progression. B cells and plasma cells have been identified in plaque and adventitia in humans and animal models of atherosclerosis throughout the course of disease and global B cell deficiency has been shown to promote atherosclerosis in murine models. Yet, the factors that regulate aortic B cell homing and the impact of modulation of these factors on atherogenesis, remain unknown. Using cell culture and animal studies, we have identified the helix-loop-helix factor (HLH), Id3, as a novel atheroprotective factor that regulates expression of chemokine receptors and aortic homing of B lymphocytes and demonstrated that Id3 was essential for B lymphocyte-mediated atheroprotection. In addition, we have recently identified a single nucleotide polymorphism (SNP) in the human ID3 gene that encodes an Id3 protein with attenuated function as a dimerization partner and dominant negative inhibitor of the bHLH E-protein, E12. This SNP is associated with carotid intima medial thickness (cIMT) in humans. Humans with the minor allele encoding an Id3 protein with attenuated Id3:E12 dimerization have an increase in cIMT (marker of subclinical atherosclerosis). Taking the mouse, human and biochemical data together, leads us to hypothesize that loss of E12 activity promotes atheroprotection through increased chemokine receptor expression and increased arterial homing of B lymphocytes in mice and that polymorphism in the human ID3 gene at rs11574 (Id3105T) resulting in reduced antagonism of human E12 activity allows repression of chemokine receptor expression, reducing chemotaxis and arterial homing of human B lymphocytes. Identification of E12 as a critical regulator of aortic B lymphocyte homing and B lymphocyte-mediated atheroprotection is not only important for further studies to broaden the paradigm of our understanding of immune regulation of atherogenesis, but may also lead to identification of novel biomarkers (ID3 gene polymorphism) and innovative strategies to promote atheroprotection in humans. Based on our compelling preliminary data and utilizing novel reagents, we propose the following aims to address our hypothesis: Aim 1: Determine if modulation of E12 expression regulates CCR6 surface protein expression and chemotaxis in B lymphocytes. Aim 2: Determine if B lymphocytes harboring the Id3 polymorphism associated with attenuated antagonism of E12 and increased cIMT in humans have reduced CCR6 expression and reduced B lymphocyte chemotaxis. Aim 3: Determine the role of E12 on aortic B cell homing and atheroprotection in vivo and determine if polymorphism in Id3 at rs11574 alters aortic B cell homing.