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

腰椎间盘退变的病因与下腰痛的关系 进行了相当严格的审查。退化被认为是由大量的异常产生的 促炎细胞因子，尤其是肿瘤坏死因子-α和白介素1-β。虽然这些研究表明， 细胞因子在腰椎间盘退变和突出发病机制中的作用 治疗靶点，以阻止炎症。这一缺陷源于我们对分子的缺乏了解 调节和连接细胞因子依赖的基质降解与免疫细胞迁移到 圆盘穿过环形缺陷。有趣的是，我们正在进行的工作发现了出人意料的协同效应 硫酸乙酰肝素(HS)、蛋白多糖Syndecan4(SDC4)和这两种关键的炎性细胞因子。的目标是 建议的研究是建立在SDC4在腰椎间盘突出症发病机制中的核心作用的基础上 和炎症。我们已经制定了两个相互关联的假设，每个假设都解决了一个单独的但 疾病过程的关联阶段。第一阶段涉及炎性细胞因子对血管内皮细胞的影响 富集聚糖基质降解的调控。我们将检验SDC4通过HS侧链的假设 通过ADAMTS和基质金属蛋白酶的激活促进细胞因子依赖的聚集素富含基质的降解。vbl.使用 在细胞因子和RNA-Seq方法处理的NP细胞中SDC4的获得和功能丧失的研究 鉴定新的SDC4反应基因。我们还将衡量MMPs、ADAMTS-1和 在SDC4脱落过程中，NP细胞产生ADAM17。此外，我们将确定SDC4水平如何变化 与聚集素和胶原在人体组织中的周转有关。疾病过程的第二阶段是 以NP和AF的结构变化为特征，形成环状撕裂和突出。我们 建议检验这一假设，即在突出的椎间盘炎症环境中，SDC4起着重要的作用 通过控制特定趋化因子(CCL5、IL-8和IL-8)的活性在巨噬细胞活化和迁移中的作用 SDF-1)由视盘细胞分泌。这将使用从SDC4-/-小鼠分离的原代巨噬细胞来实现。 利用具有良好特征的人类腰椎间盘疼痛组织，我们将把趋化因子和SDC4水平的变化与 免疫细胞活化、渗透和基质降解。最后，探讨SDC4在体内的重要性 在肿瘤坏死因子-驱动的腰椎间盘突出的发病机制中，我们将hTNFtg小鼠与SDC4-/-动物杂交来产生 HTNFtg、SDC4-/-小鼠。确定SDC4缺陷是否提供了对细胞因子依赖型椎间盘的保护 我们将比较运动节段的分子、结构和生物力学特性与 HTNFtg。据我们所知，这将是第一次尝试解决SDC4对 简并级联和腹股沟的启动和传播机制 炎性细胞因子。这些研究将为今后介入治疗的发展提供基础。 针对退行性间盘疾病的SDC4依赖的分解代谢和炎症阶段的策略。

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.