Project 3: Regulation of atheroprotective IgM - producing B cells in murine and human atherosclerosis

项目3摘要 我们和其他人在小鼠身上广泛研究了B-1细胞，清楚地表明这些细胞和 它们产生的低密度脂蛋白氧化特异表位(IgMOSE)的IgM是抗 炎症和阻止动脉粥样硬化(AS)的发展。然而，尽管有大量证据 人血浆IgM水平与OSE、丙二醛修饰低密度脂蛋白(IgMMDA-LDL)的关系 与较少的冠心病和较少的心血管事件相关，识别产生IgMMDA-LDL 人类B细胞仍然难以捉摸。我们来自上一个周期的新数据，利用油井 具有特征性的腔静脉队列和循环B细胞的高维表型，是第一次 鉴定产生IgMMDA-LDL的人类B细胞亚型，并证明它们确实是 与血浆中高水平的IgMMDA-LDL相关，并与冠心病严重程度呈负相关 人类。这些亚型中的一种(B27+IgM+24hi细胞)运输到脾，可能是 体内受丙二醛抗原刺激产生较高水平的IgMMDA-LDL。我们的发现揭示了 唾液酸糖蛋白CD24调控趋化因子表达的新发现 CCR6受体与这些细胞的脾定位。CD24，一个GPI锚定的 驻留在脂筏中的唾液酸糖蛋白，调节IgM bcr的信号传递，但没有 此前曾与小鼠或人类AS有牵连。利用我们的抗体和转录组 对核心(核心B)进行测序，我们发现B27+IgM+24HI细胞表达更多CCR6和IgM 特别是在低CAD和高CAD的受试者中，我们发现了信号分子 CCR6下游和IgM BCR与冠心病严重程度相关。因此，我们 假设患有严重冠心病和快速冠心病进展的人较少 B27+IgM+24HI细胞和CD24作为促进关键表面受体功能的变阻器 和B27+IgM+细胞中导致IgMOSE和IgMOSE产生增加的信号通路 动脉粥样硬化保护。我们将利用新的临床队列(目标1)和功能的丧失和获得 体外和体内方法(目标2)以确定CD24调节 B27+IgM+表型，特别强调CCR6、BCR、关键信号事件和 动脉粥样硬化中的免疫球蛋白谱。

Project 3 Summary We and others have extensively studied B-1 cells in mice, clearly showing that these cells and the IgM to oxidation-specific epitopes (OSE) on LDL (IgMOSE) that they produce are anti- inflammatory and block atherosclerosis (AS) development. Yet, despite a wealth of evidence that plasma levels of IgM to the OSE, malondialdehyde-modified LDL (IgMMDA-LDL) in humans are associated with less CAD and fewer CV events, identification of the IgMMDA-LDL producing human B cell has remained elusive. Our novel data from the previous cycle, utilizing the well characterized CAVA cohort and high dimensional phenotyping of circulating B cells, are the first to identify human B cell subtypes that produce IgMMDA-LDL, and demonstrate that they are indeed associated with high plasma levels of IgMMDA-LDL and inversely correlated with CAD severity in humans. One of these subtypes (B27+IgM+24hi cells) trafficked to the spleen and could be stimulated by MDA antigen to produce higher levels of IgMMDA-LDL in vivo. Our findings revealed the novel discovery that the sialogycoprotein, CD24, regulated expression of the chemokine receptor CCR6 and splenic localization of these cells. CD24, a GPI-anchored sialoglycoprotein that resides in lipid rafts and regulates signaling of the IgM BCR, has not previously been implicated in murine or human AS. Utilizing our antibody and transcriptome sequencing core (Core B), we discovered that B27+IgM+24hi cells express more CCR6 and IgM specifically in subjects with low compared to high CAD and we identified signaling molecules downstream of CCR6 and the IgM BCR associated with CAD severity. Accordingly, we hypothesize that humans with severe CAD and rapid CAD progression have fewer B27+IgM+24hi cells and that CD24 acts as a rheostat promoting key surface receptor function and signaling pathways in B27+IgM+ cells leading to enhanced production of IgMOSE and atheroprotection. We will utilize novel clinical cohorts (aim 1) and loss- and gain- of function approaches in vitro and in vivo (aim 2) to define the mechanisms whereby CD24 regulates the B27+IgM+ phenotype with particular emphasis on CCR6, the BCR, key signaling events and the IgM repertoire in atherosclerosis.