MMP-dependent control of macrophage immune function

描述(申请人提供)：在从宿主防御到慢性炎症性疾病状态的一系列事件中，单核/巨噬细胞(MO)渗透到受影响的间质组织，在那里它们可以参与细胞外基质的蛋白水解性重塑和局部免疫反应。虽然长期以来一直认为S动员蛋白水解酶(特别是那些属于基质金属蛋白酶基因家族的酶)以通过细胞外基质屏障进行运输，但越来越多的证据表明，髓系细胞群通过依赖于细胞形状的机械扭曲的不依赖于蛋白酶的过程渗透到组织中。因此，虽然MOS表达基质金属蛋白酶，但这些酶的功能仍不清楚。为了确定MOS中替代的基质金属蛋白酶依赖的功能，我们将注意力集中在膜锚定的蛋白水解酶MT1-MMP.在旨在比较和对比野生型和MT1-MMP零MOS的组织侵袭行为的初步研究中，我们发现MO来源的MT1-MMPs并不像预测的那样，在调节细胞在体外或体内的运输方面发挥所需的作用。相反，MT1-MMP2+/+与MT1-MMP1-/-MOS的基因表达谱表明，该蛋白酶是MO炎症反应中心的基因网络的关键但未被怀疑的反式激活因子。有证据表明，MT1-MMP可能通过控制一个迄今未被描述的轴来发挥这一作用，在该轴中，内毒素-TLR4相互作用触发MT1-MMPs的表达，而MT1-MMPs随后作为PI3K？/Akt/GSK3信号和核小体重构因子的Mi-2/NuRD复合体所必需的激活物。结合另一组支持MT1-MMPs进入核室的可能性的初步数据，我们推测MT1-MMPs在免疫调节中起关键的协同转录激活作用。因此，我们建议：1)确定体外培养的MT1-MMP2/-巨噬细胞中LPSTLR4轴的功能状态；2)确定MT-MMP3启动的级联反应，将PI3K？-Akt-GSK3信号与依赖于Mi-2/NuRD的核小体重构联系起来；3)研究控制MO免疫反应的MT-MMP核转运途径。这些研究应该为MO依赖的细胞外基质周转与核小体重塑通路的协调提供新的和新的见解，核小体重塑通路标志着作为宿主防御中心的慢性炎症事件以及炎症性疾病状态。作为MT-MMPs和PI3K？在几乎所有的免疫细胞群体中都有表达，这些结果应该有助于勾勒出炎症和控制机制的新范式，这可能被证明有助于治疗干预。

DESCRIPTION (provided by applicant): During events ranging from host defense to chronic inflammatory disease states, monocytes/macrophages (MOs) infiltrate affected interstitial tissues where they can participate in both the proteolytic remodeling of the extracellular matrix and local immune responses. While M¿s have long been assumed to mobilize proteolytic enzymes (particularly those belonging to the matrix metalloproteinase gene family) in order to traffic through extracellular matrix barriers, increasing evidence suggests that myeloid cell populations infiltrate tissues via protease-independent processes relying instead on the mechanical distortion of cell shape. Hence, while MOs express matrix metalloproteinases, the function of these enzymes remain unclear. In an attempt to identify alternate matrix metalloproteinase-dependent functions in MOs, we have focused our attention on the membrane-anchored protease, MT1-MMP. In preliminary studies designed to compare and contrast the tissue-invasive behavior of wild-type and MT1-MMP-null MOs, we find that MO-derived MT1-MMP does not, as predicted, play a required role in regulating cell trafficking in vitro or in vivo. Instead, gene expression profiling of MT1-MMP+/+ versus MT1-MMP-/- MOs suggest that the protease acts as a critical but unsuspected, transactivator of the gene networks central to MO inflammatory responses. Evidence suggests that MT1-MMP may exert this effect by controlling a heretofore undescribed axis wherein LPS-TLR4 interactions trigger MT1-MMP expression which then acts as a required activator of PI3K?/Akt/GSK3 signaling and the Mi-2/NuRD complex of nucleosome remodeling factors. In combination with an additional body of preliminary data supporting the possibility that MT1-MMP traffics into the nuclear compartment, we postulate that MT1-MMP serves as co-transcriptional activators critical to immune regulation. As such, we propose to i) characterize the functional status of the LPS-TLR4 axis in MT1-MMP-/- macrophages in vitro, ii) define the MT-MMP-initiated cascades that link PI3K?-Akt-GSK3 signaling to Mi-2/NuRD-dependent nucleosome remodeling, iii) characterize the MT-MMP nuclear trafficking pathway that control MO immune responses. These studies should provide new and novel insights into the orchestration of MO-dependent extracellular matrix turnover with the nucleosomal remodeling pathways that mark chronic inflammatory events central to host defense as well as inflammatory disease states. As MT-MMPs and PI3K? are expressed in almost all immune cell populations, these results should serve to outline a new paradigm in inflammation and identification of control mechanisms that may prove conducive to therapeutic intervention.