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

项目3摘要 我们和其他人已经在小鼠中广泛研究了B-1细胞，清楚地表明这些细胞和 它们产生的针对低密度脂蛋白氧化特异性表位（OSE）的IgM（IgMOSE）是抗- 炎症和阻断动脉粥样硬化（AS）发展。然而，尽管有大量的证据 人血浆中OSE、丙二醛修饰的低密度脂蛋白（IgMMDA-LDL）的IgM水平 与较少的CAD和较少的CV事件相关， 人类B细胞仍然是难以捉摸。我们从上一个周期获得的新数据， 特征性CAVA队列和循环B细胞的高维表型，是第一个 鉴定产生IgMMDA-LDL的人B细胞亚型，并证明它们确实是 与高血浆IgMMDA-LDL水平相关，与CAD严重程度呈负相关， 人类其中一种亚型（B27+IgM+24 hi细胞）被运输到脾脏，并可能被转移到淋巴细胞。 MDA抗原刺激产生更高水平的IgMMDA-LDL。我们的发现表明 唾液酸糖蛋白CD 24调节趋化因子表达的新发现 受体CCR 6和这些细胞的脾定位。CD 24，GPI锚定的 唾液酸糖蛋白存在于脂筏中并调节IgM BCR的信号传导， 先前与鼠或人AS有关。利用我们的抗体和转录组 测序核心（Core B），我们发现B27+IgM+24 hi细胞表达更多的CCR 6和IgM 特别是在低CAD与高CAD的受试者中，我们鉴定了信号分子， CCR 6下游和IgM BCR与CAD严重程度相关。因此我们 假设患有严重CAD和快速CAD进展的人具有较少的 B27+IgM+24 hi细胞，CD 24作为变阻器促进关键表面受体功能 和B27+IgM+细胞中的信号传导途径，导致IgMOSE的产生增强， 动脉粥样硬化保护我们将利用新的临床队列（目标1）以及功能的丧失和获得 在体外和体内的方法（目的2），以确定机制，其中CD 24调节 B27+IgM+表型，特别强调CCR 6、BCR、关键信号传导事件和 动脉粥样硬化中的IgM库。

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.