Novel mechanisms involving complement cascade in stem cell trafficking

修改项目摘要/摘要部分 这种竞争性更新的主要假设是基于新的令人兴奋的数据，这些数据进一步支持了 补体级联（ComC）和先天免疫的其他要素在动员 造血干/祖细胞（HSPC）。ComC通过i）经典的，ii）甘露聚糖结合， 凝集素（Mbl），和iii）替代途径，以及，正如我们已经报道的那样，缺乏共同远端 ComC的组成部分（C5-/-小鼠）是较差的动员者。然而，令我们惊讶的是，我们发现， 不激活经典ComC（C1 q-/-小鼠）是正常动员者。这种“差异”现在被解释为： 我们的最新结果显示，Mbl-dependent ComC通路的关键参与，而不是经典的 在动员的道路上。我们最近还发现，两种应激诱导的酶，血红素加氧酶1（HO-1） 和诱导型一氧化氮合成酶（iNOS）是细胞迁移的负调节剂。根据这些发现， 我们已经收集了一个建议，以一种全面的方式，解决先天因素的参与， HSPC动员中的免疫力（ComC、Gr-1+粒细胞/单核细胞、天然存在的抗体）。 在三个相互关联的具体目标，我们解决的关键：i）启动，ii）放大，和执行阶段， 动员。具体目标1。动员的起始阶段由Mbl-mediated ComC解释 activation.我们一直认为经典的ComC激活途径在触发 动员。然而，正如我们最近发现的那样，Mbl途径而不是经典途径在 这个过程动员剂的主要靶细胞是Gr-1+细胞，其除了蛋白水解和细胞毒性外， 脂肪分解酶也分泌ROS和ROS相关分子模式分子（DAMP）。而 蛋白水解酶和脂解酶干扰HSPC在骨髓（BM）小生境中的保留，ROS暴露 由天然存在的IgM抗体和从Gr-1+细胞释放的DAMP结合的新表位抗原， 由循环模式识别受体（PRR）Mbl识别，Mbl通过甘露聚糖结合凝集素丝氨酸 蛋白酶（MASP）激活ComC和凝血级联（CoaC）。具体目标2。扩增 动员阶段-C5转化酶的产生。由于C5裂解对于HSPC的排出至关重要， 从BM开始，该阶段的主要功能是产生C5转化酶活性。这种酶是作为 C3裂解的结果，其提供经典C5转化酶的元件，并且另外通过凝血酶， 其具有C5“转化酶样”活性。放大相位也被自发的 C3激活的扩增环和ComC激活的替代途径的可能参与 并将在这方面进行详细研究。具体目标3。ComC介导的动员的执行阶段。 我们最近的研究结果表明，HSPCs从BM中的排出受HO-1和iNOS的负控制，它们是 细胞迁移的负调节因子。我们将集中讨论这种现象的分子机制。是 预计这些成果将转化为制定更好的动员协议。 1

Modified Project Summary/Abstract Section The main hypothesis of this competing renewal is based on new exciting data that further supports the pivotal role of the complement cascade (ComC) and other elements of innate immunity in the mobilization of hematopoietic stem/progenitor cells (HSPCs). The ComC is activated by the i) classical, ii) mannan-binding lectin (Mbl), and iii) alternative pathways, and, as we already reported, mice that lack the common distal component of the ComC (C5–/– mice), are poor mobilizers. To our surprise, however, we found that mice that do not activate the classical ComC (C1q–/– mice) are normal mobilizers. This “discrepancy” is now explained by our latest results that show the pivotal involvement of the Mbl-dependent ComC pathway and not the classical pathway in mobilization. We also recently found that two stress-induced enzymes, heme oxygenase 1 (HO-1) and inducible nitric oxide synthetase (iNOS), are negative regulators of cell migration. Based on these findings, we have assembled a proposal that, in a comprehensive way, addresses the involvement of elements of innate immunity (ComC, Gr-1+ granulocytes/monocytes, naturally occurring antibodies) in the mobilization of HSPCs. In three interrelated specific aims, we address the crucial: i) inititation, ii) amplification, and execution phases of mobilization. Specific Aim 1. The initiation phase of mobilization is explained by Mbl-mediated ComC activation. We have maintained that the classical ComC activation pathway plays a crucial role in triggering mobilization. However, as we discovered recently, it is not the classical but the Mbl pathway that is crucial in this process. The main target cells for mobilizing agents are Gr-1+ cells, which, in addition to proteolytic and lipolytic enzymes, also secrete ROS and danger-associated molecular pattern molecules (DAMPs). While proteolyic and lipolytic enzymes perturb the retention of HSPCs in bone marrow (BM) niches, ROS-exposed neoepitope antigens bound by naturally occurring IgM antibodies and DAMPs released from Gr-1+ cells are recognized by the circulating pattern recognition receptor (PRR) Mbl, which, via mannan-binding lectin serine proteases (MASPs), activates the ComC and coagulation cascade (CoaC). Specific Aim 2. The amplification phase of mobilization - the generation of C5 convertase. Since C5 cleavage is crucial for egress of HSPCs from BM, the main function of this phase is generation of C5 convertase activity. This enzyme is generated as a result of C3 cleavage, which provides elements of classical C5 convertase, and additionally by thrombin, which has C5 “convertase-like” activity. The amplification phase is also modulated by a spontaneous amplification loop of C3 activation and by possible involvement of an alternative pathway of ComC activation and will be studied in detail in this aim. Specific Aim 3. Execution phase of ComC-mediated mobilization. Our recent results show that egress of HSPCs from BM is negatively controlled by HO-1 and iNOS, which are negative regulators of cell migration. We will focus on the molecular mechanisms of this phenomenon. It is expected that these results will be translated into the development of better mobilization protocols. 1