Pathogenesis of Inflammation-driven Intervertebral Disc Herniation: The Role of Syndecan 4

椎间盘退变的病因与腰痛的关系一直受到 接受严格的审查退化被认为是由一些非正常的生产， 促炎细胞因子，特别是TNF-α和IL-1β。虽然这些研究表明， 细胞因子在椎间盘退变和突出发病机制中的作用，在阐明新的 治疗靶点来阻断炎症。这种缺陷源于我们对分子生物学的缺乏了解。 调节和连接腺嘌呤依赖性基质降解与免疫细胞迁移到 椎间盘通过环状缺损。有趣的是，我们正在进行的工作发现了一个意想不到的协同作用， 硫酸乙酰肝素（HS）蛋白聚糖syndecan 4（SDC 4）和这两种关键的炎性细胞因子。的目标 拟议的研究是建立在SDC 4在椎间盘突出发病机制中的核心作用的基础上 和炎症。我们提出了两个相互关联的假设，每一个假设都针对一个单独的问题， 疾病过程的关联阶段。第一阶段涉及炎性细胞因子对细胞增殖的影响。 富含聚集蛋白聚糖的基质降解的调节。我们将检验SDC 4通过HS侧链 通过ADAMTS和MMP活化促进富含聚集蛋白聚糖的基质降解。使用 在用细胞因子和RNA-Seq方法处理的NP细胞中SDC 4的功能获得和丧失研究中，我们将 鉴定新SDC 4应答基因。我们还将测量MMPs、ADAMTS-1和 在SDC 4脱落中由NP细胞产生的ADAM 17。此外，我们将确定SDC 4水平的变化 与人组织中的聚集蛋白聚糖和胶原蛋白周转有关。疾病过程的第二阶段是 其特征在于NP和AF的结构变化以及瓣环撕裂和疝的形成。我们 我建议测试这一假设，即在椎间盘突出的炎症环境中，SDC 4起着重要的作用。 通过控制选择的趋化因子（CCL 5，IL-8和 SDF-1）。这将使用从SDC 4-/-小鼠分离的原代巨噬细胞来实现。 使用特征明确的疼痛的人类椎间盘组织，我们将把趋化因子和SDC 4水平的变化联系起来， 免疫细胞活化、浸润和基质降解。最后，为了探索SDC 4在体内的重要性， 在TNF-α驱动椎间盘突出的发病机制中，我们将hTNF tg小鼠与SDC 4-/-动物杂交， hTNFtg，SDC 4-/-小鼠。确定SDC 4缺陷是否可提供针对尼古丁依赖性椎间盘的保护 我们将比较运动节段的分子，结构和生物力学特性， hTNFtg。据我们所知，这将是第一次尝试解决SDC 4对 连接退行性级联反应和疝形成的启动和传播的机制， 炎性细胞因子这些研究将为今后介入治疗的发展奠定基础。 靶向SDC 4依赖性分解代谢和退行性椎间盘疾病的炎症阶段的策略。

The relationship between the etiology of intervertebral disc degeneration and low back pain has been subjected to considerable scrutiny. Degeneration is thought to be initiated by the abnormal production of a number of pro-inflammatory cytokines, in particular TNF-α and IL-1β. While these studies have shown involvement of cytokines in pathogenesis of disc degeneration and herniation, progress has been slow in delineating new therapeutic targets to block inflammation. This deficit stems from our lack of understanding of molecular mediators that regulate and link cytokine-dependent matrix degradation with immune cell migration into the disc through annular defects. Interestingly, our ongoing work has found an unexpected synergism between heparan sulfate (HS) proteoglycan syndecan4 (SDC4) and these two key inflammatory cytokines. The goal of the proposed investigations is to build on the central role of SDC4 in the pathogenesis of the disc herniation and inflammation. We have formulated two interrelated hypotheses each of which addresses a separate but linked phase of the disease process. The first phase relates to the effect of the inflammatory cytokines on the regulation of aggrecan rich matrix degradation. We will test the hypothesis that SDC4 through HS side chains promotes cytokine-dependent aggrecan rich matrix degradation through ADAMTS and MMP activation. Using gain and loss-of-function studies of SDC4 in NP cells treated with cytokines and RNA-Seq approach we will identify novel SDC4 responsive genes. We will also measure the contribution of MMPs, ADAMTS-1 and ADAM17 produced by NP cells in SDC4 shedding. In addition, we will determine how changes in SDC4 levels relate to aggrecan and collagen turnover in human tissues. The second stage of the disease process is characterized by structural changes in the NP and AF and formation of annular tears and herniations. We propose to test the hypothesis that that in inflammatory milieu of the herniated disc, SDC4 plays an important role in macrophage activation and migration by controlling the activity of select chemokines (CCL5, IL-8 and SDF-1) secreted by the disc cells. This will be achieved using primary macrophages isolated from SDC4-/- mice. Using well characterized painful human disc tissues, we will link changes in chemokines and SDC4 levels to immune cell activation, infiltration and matrix degradation. Finally, to explore the in vivo importance of SDC4 in pathogenesis of TNF--driven disc herniation, we will cross hTNFtg mice with SDC4 -/- animals to generate hTNFtg,SDC4-/- mice. To establish if a deficiency in SDC4 provides protection against cytokine-dependent disc herniation, we will compare molecular, structural and biomechanical properties of the motion segments with that of hTNFtg. To our knowledge, this would be the first attempt to address the contribution of SDC4 to mechanisms linking initiation and propagation of the degenerative cascade and herniation driven by inflammatory cytokines. These studies will provide a foundation for future development of interventional strategies to target SDC4 dependent catabolic and inflammatory phases of degenerative disc disease.