Genetic Regulation of B Lymphocyte Aortic Homing and Atheroprotection

描述(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细胞在血管壁上的募集以及它们在斑块进展中的作用，人们已经知道了很多。在人类的斑块和外膜中已经发现了B细胞和浆细胞，并在整个疾病过程中建立了动脉粥样硬化的动物模型，在小鼠模型中，全球B细胞缺陷被证明促进了动脉粥样硬化。然而，调节主动脉B细胞归巢的因素以及这些因素对动脉粥样硬化形成的影响尚不清楚。通过细胞培养和动物实验，我们发现螺旋-环-螺旋因子ID3是一种新的动脉粥样硬化保护因子，调节B淋巴细胞趋化因子受体的表达和主动脉归巢，证明ID3在B淋巴细胞介导的动脉粥样硬化保护中是必不可少的。此外，我们最近在人类ID3基因中发现了一种单核苷酸多态性(SNP)，它编码一种ID3蛋白，其功能减弱，是bHLHE蛋白E12的二聚化伙伴和显性负抑制因子。这种SNP与人类颈动脉内膜中层厚度(CIMT)相关。具有编码ID3蛋白的微小等位基因且ID3：E12二聚化减弱的人，其cIMT(亚临床动脉粥样硬化的标记物)增加。综合小鼠、人类和生化数据，我们假设E12活性的丧失通过增加趋化因子受体的表达和增加小鼠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)的多态导致人E12活性的拮抗作用降低，从而抑制趋化因子受体的表达，减少人B淋巴细胞的趋化和动脉归巢。确定E12是主动脉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，不仅对于进一步研究拓宽我们对动脉粥样硬化形成的免疫调节的范式具有重要意义，而且还可能导致识别新的生物标志物(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利用新的试剂，我们提出了以下目的来解决我们的假设：目的1：确定E12表达的调节是否调节B淋巴细胞表面CCR6蛋白的表达和趋化作用。目的：研究人类携带与E12拮抗减弱和CIMT增加相关的ID3基因多态性的B淋巴细胞是否降低了CCR6的表达，降低了B淋巴细胞的趋化能力。目的：研究E12基因在体内对主动脉B细胞归巢和动脉粥样硬化保护中的作用，以及rs11574位ID3基因多态性是否改变了主动脉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.