Macrophage Elastase in Host Defense

描述（由申请人提供）：基质金属蛋白酶（MMP）是一种 一组基质降解酶，其异常或过度表达可 导致多种组织破坏性疾病。关于这一点，我们所知甚少。 MMPs的正常生理功能。我们目前的数据表明，巨噬细胞弹性蛋白酶 MMP-12是唯一具有直接抗微生物活性的MMP。MMP-12作用 在肺巨噬细胞内作为抵御微生物的第一道防线， 肺泡空间。基质金属蛋白酶在促进肿瘤生长中的作用是众所周知的 进展然而，随着血管抑制素的发现， 纤溶酶原的蛋白水解片段，很明显，蛋白酶可以被 参与限制肿瘤生长。我们目前的证据表明，MMP-12发挥了重要作用， 在限制肺内肿瘤生长方面起主要作用。该物业可能有 临床重要性，因为至少有6项使用MMP抑制剂的III期试验 癌症治疗和两个关节炎去年停止与此有关 某些MMPs限制肿瘤生长的特性被低估。进一步 确定巨噬细胞和MMP-12在宿主防御细菌中的作用， 在肺肿瘤，我们建议：1。检验MMP-12 代表一种新的巨噬细胞介导的细胞内抗菌剂。我们 提供了初步数据，MMP-12-/-小鼠在应答中具有较差的结果， 对鼠伤寒沙门氏金黄色葡萄球菌肺炎，MMP-12-/-巨噬细胞具有受损的细胞内 杀死S。金黄色葡萄球菌，并显示MMP-12具有直接的抗微生物能力。 这种活性与催化能力无关， 非催化C末端结构域。建议进行研究，以确定光谱 MMP-12影响的细菌。我们还将定义 MMP-12负责该活性。2.我们将扩展这样的假设： MMP-12通过抑制血管生成干扰肿瘤生长，并进一步 确定潜在的作用机制。我们提供的初步数据表明，MMP-12 是维持刘易斯肺细胞癌（LLC）转移的休眠所必需的。 这种活性似乎与抑制血管生成有关。这不仅仅是 由于血管抑素的生成。另外的抗血管生成蛋白片段 发挥作用，我们假设MMP-12也干扰MMP-2介导的 促进肿瘤生长。MMP-12可能通过切割MMP-2以及 通过与MMP-2竞争内皮细胞和肿瘤细胞结合， 其C-末端结构域。3.我们将确定肺巨噬细胞的作用， 发展、细菌感染和肿瘤进展。我们将利用 MMP-12巨噬细胞特异性表达与白喉完全生成的关系 毒素（DT）“敲入”MMP-12基因座。我们假设这将导致 在缺乏肺（和腹膜）巨噬细胞的小鼠中，这些小鼠 会经历正常的肺部发育如果这个假设是正确的，那么 小鼠将用于研究宿主防御中巨噬细胞的需求， 炎症如果突变是致命的或肺 巨噬细胞，然后肺特异性转基因小鼠将被用来诱导 表达DT。

DESCRIPTION (provided by applicant): Matrix metalloproteinases (MMPs) are a group of matrix degrading enzymes whose aberrant or excessive expression can lead to a variety of tissue destructive diseases. Less is known about the normal physiologic functions of MMPs. We present data that macrophage elastase (MMP-12) is the only MMP that has direct antimicrobial activity. MMP-12 acts within the lung macrophage as the first line of defense against microbes within the alveolar space. MMPs are well known for their roles in promoting tumor progression. However, with the discovery of angiostatin, an antiangiogenic proteolytic fragment of plasminogen, it became clear that proteinases can be involved in limiting tumor growth. We present evidence that MMP-12 plays a major role in limiting tumor growth within the lung. This property might have clinical importance since at least 6 phase 3 trials using MMP inhibitors for cancer therapy and two for arthritis were stopped last year related to this under-appreciated property of certain MMPs to limit tumor growth. To further define the role of macrophages and MMP-12 in host defense against bacteria and tumors in the lung, we propose to: 1. Test the hypothesis that MMP-12 represents a novel macrophage-mediated intracellular antimicrobial agent. We provide preliminary data that MMP-12-/- mice have a poorer outcome in response to S. aureus pneumonia, MMP-12-/- macrophages have impaired intracellular killing of S. aureus, and show that MMP-12 has direct antimicrobial capacity. This activity is independent of catalytic capacity and involves the non-catalytic C-terminal domain. Studies are proposed to define the spectrum of bacteria influenced by MMP-12. We will also define the structural components of MMP-12 responsible for this activity. 2. We will extend the hypothesis that MMP-12 interferes with tumor growth via inhibition of angiogenesis and further define potential mechanisms of action. We provide preliminary data that MMP-12 is required to maintain dormancy of Lewis lung cell carcinoma (LLC) metastases. This activity appears related to inhibition of angiogenesis. This is not merely due to generation of angiostatin. Additional antiangiogenic protein fragments play a role, and we postulate that MMP-12 also interferes with MMP-2-mediated promotion of tumor growth. MMP-12 might do this by cleavage of MMP-2 as well as by competition with MMP-2 for endothelial cell and tumor cell binding through its C-terminal domain. 3. We will determine the role of macrophages in lung development, bacterial infection, and tumor progression. We will take advantage of MMP-12 macrophage specific expression and complete generation of diphtheria toxin (DT) "knock-in" to the MMP-12 locus. We hypothesize that this will result in mice deficient in lung (and peritoneal) macrophages, and that these mice will undergo normal lung development. If this hypothesis is correct, then the mice will be used to study the requirement of macrophages in host defense and inflammation. If the mutation is lethal or not fully deficient in pulmonary macrophages, then lung-specific transgenic mice will be used to inducibly express DT in lungs of mature mice.