MMP-8 as a novel therapeutic target in sepsis

描述（由申请人提供）：感染性休克是成人和儿童的主要公共卫生问题，因此需要开发新的靶点和治疗策略。基于以微阵列为中心的临床研究和后续以动物为中心的实验，我们已经确定基质金属肽酶-8 （MMP-8）作为脓毒症病理的候选靶点。MMP-8是一种中性粒细胞产物，在细胞外基质转换过程中分裂1型胶原蛋白。然而，现在已经证明MMP-8也可以调节急性炎症，并可能在败血症病理中发挥作用。该建议的总体假设是MMP-8的表达和活性在脓毒症病理中起主要作用。我们现在提议通过四个互补的具体目标来检验这一假设。在Specific Aim 1中，我们将检验抑制MMP-8活性改善脓毒症病理相关的多个终点的假设。该实验将使用MMP-8缺失动物和MMP-8活性的药理学抑制剂。在特异性目标2中，我们将检验发育年龄影响MMP-8在脓毒症中的作用的假设。该研究将使用适用于1周龄小鼠幼崽的脓毒症模型，并将利用MMP-8缺失小鼠和MMP-8活性的药理学抑制剂。在Specific Aim 3中，我们将验证骨髓源性细胞是脓毒症中MMP-8基因调控的主要来源这一假设。该Aim的体内实验将涉及将MMP-8空骨髓过继移植到野生型小鼠，反之亦然。本研究的体外实验将系统地阐明导致中性粒细胞和单核细胞中MMP-8基因重新表达的信号机制。在Specific Aim 4中，我们将检验1型胶原降解产物参与MMP-8调节炎症机制的假设。本Aim的体外实验将测试条件培养基的能力，条件培养基来源于经活化的MMP-8处理的1型胶原包被组织培养板，以激活巨噬细胞。本Aim的体内实验将测量具有1型胶原突变的小鼠对败血症的反应，这种突变使其能够抵抗MMP-8的切割。本课题的主要成果包括：确立MMP-8作为脓毒症的新治疗靶点，阐明发育如何影响MMP-8在脓毒症中的作用，阐明MMP-8在脓毒症中的主要细胞来源，全面了解炎症过程中MMP-8表达的信号机制。以及mmp -8依赖性1型胶原降解产物作为先天免疫系统危险相关分子模式的建立。

DESCRIPTION (provided by applicant): Septic shock is a major public health problem in both adults and children, and consequently there is a need to develop novel targets and therapeutic strategies. Based on microarray-centered clinical studies and follow up animal-centered experiments, we have indentified matrix metallopeptidase-8 (MMP-8) as a candidate target in sepsis pathology. MMP-8 is best known as a neutrophil product that cleaves collagen type 1 during extra-cellular matrix turnover. However, it has now become evident that MMP-8 also modulates acute inflammation and may play a role in sepsis pathology. The overarching hypothesis of this proposal is that MMP-8 expression and activity play a major role in sepsis pathology. We are now proposing to test this hypothesis via four complementary Specific Aims. In Specific Aim 1 we will test the hypothesis that inhibition of MMP-8 activity improves multiple endpoints relevant to sepsis pathology. This Aim will use MMP-8 null animals and a pharmacologic inhibitor of MMP-8 activity. In Specific Aim 2 we will test the hypothesis that developmental age influences the role of MMP-8 in sepsis. This Aim will use a sepsis model adaptable to 1 week old mouse pups, and will also make use of MMP-8 null mice and a pharmacologic inhibitor of MMP-8 activity. In Specific Aim 3 we will test the hypothesis that bone marrow-derived cells are the main source of MMP-8 gene regulation in sepsis. The in vivo experiments for this Aim will involve adoptive transfer of MMP-8 null bone marrow to wild-type mice, and vice versa. The in vitro experiments for this Aim will systematically elucidate the signaling mechanisms that lead to de novo MMP-8 gene expression in neutrophils and monocytes. In Specific Aim 4 we will test the hypothesis that collagen type 1 degradation products are involved in the mechanism by which MMP-8 regulates inflammation. The in vitro experiments for this Aim will test the ability of conditioned media, derived from collagen type 1 coated tissue culture plates treated with activated MMP-8, to activate macrophages. The in vivo experiments for this Aim will measure the response to sepsis in mice having a mutation of collagen type 1, which renders it resistant to cleavage by MMP-8. The major deliverables of this proposal include the establishment of MMP-8 as a novel therapeutic target in sepsis, the elucidation of how development influences the role of MMP-8 in sepsis, the elucidation of the major cellular source of MMP-8 in sepsis, a comprehensive understanding of the signaling mechanisms involved in MMP-8 expression during inflammation, and the establishment of MMP-8-dependent collagen type 1 degradation products as danger associated molecular patterns for the innate immune system.