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进行性炎症过程，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，我们知道得很多。在动脉粥样硬化的人类和动物模型的斑块和外膜中已经发现了B细胞和浆细胞，并且在小鼠模型中已经证明B细胞缺乏会促进动脉粥样硬化。然而，调节主动脉B细胞归巢的因素以及这些因素的调节对动脉粥样硬化的影响尚不清楚。通过细胞培养和动物实验，我们发现螺旋-环-螺旋因子（HLH） Id3是一种新的动脉粥样硬化保护因子，可以调节趋化因子受体的表达和B淋巴细胞的主动脉归巢，并证明Id3对B淋巴细胞介导的动脉粥样硬化保护至关重要。此外，我们最近在人类ID3基因中发现了一个单核苷酸多态性（SNP），该多态性编码一个ID3蛋白，该蛋白作为二聚化伴侣和bHLH e蛋白的显性负抑制剂E12的功能减弱。这种SNP与人类颈动脉内膜内侧厚度（cIMT）有关。携带编码Id3:E12二聚化减弱的Id3蛋白的小等位基因的人cIMT（亚临床动脉粥样硬化的标志物）增加。将小鼠、人类和生化数据结合起来，我们假设E12活性的丧失通过增加趋化因子受体表达和增加小鼠B淋巴细胞的动脉归巢来促进动脉粥样硬化保护，而人类ID3基因rs11574 （Id3105T）的多态性导致人类E12活性的拮抗作用降低，从而抑制趋化因子受体表达，降低人类B淋巴细胞的趋化性和动脉归巢。确定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的关键调节因子，不仅对进一步研究拓宽我们对动脉粥样硬化发生的免疫调节的理解范式具有重要意义，而且可能导致鉴定新的生物标志物（ID3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和使用新的试剂，我们提出以下目标来解决我们的假设：目标1：确定E12表达的调节是否调节B淋巴细胞中CCR6表面蛋白的表达和趋化性。目的2：确定B淋巴细胞中含有与E12拮抗减弱和cIMT增加相关的Id3多态性是否降低了CCR6表达和B淋巴细胞趋化性。目的3：确定体内E12在主动脉B细胞归巢和动脉粥样硬化保护中的作用，并确定rs11574处Id3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.