Matrix Metalloproteinase Regulation of Leukocyte Infiltration during Wound Repair

描述（由申请人提供）： 在现有组织完整性丧失后，伤口闭合对于维持保护性表皮屏障至关重要，所述保护性表皮屏障保护宿主免受环境侵害并防止水分流失。在伤口修复过程中的一个基本的初始反应是循环白细胞的流入，其清洁伤口并且还提供激活剂和生长因子以刺激纤维形成和新血管形成。基质金属蛋白酶（MMP）家族成员，如MMP 3，是白细胞浸润的潜在关键调节因子。MMP 3在经历组织重塑的过程中在表皮中上调。MMP 3无效的小鼠具有切除伤口的延迟闭合，并且在许多模型系统中显示白细胞浸润减少。此外，我们发现MMP 3-/-动物对SCC进展的敏感性增加，这与在肿瘤进展的所有阶段中明显的中性粒细胞和巨噬细胞浸润的减少有关。基于这些观察结果，我们提出MMP 3在创伤修复过程中调节保护性宿主防御反应，这反映了SCC过程中的保护性抗肿瘤反应。许多已知影响免疫细胞功能的分子可以被MMP 3或由MMP 3激活的基质蛋白酶直接靶向水解和释放。我们假设MMP 3与其他基质蛋白酶结合，直接增强白细胞外渗，随后影响伤口修复过程。白细胞浸润到炎症部位需要协调调节多个步骤，包括内皮上的阻滞、通过内皮屏障的迁移和通过结缔组织朝向炎症部位的定向迁移。MMP 3由多种细胞类型表达，包括角质形成细胞、成纤维细胞、内皮细胞和单核细胞，并且可以激活其他基质蛋白酶类别;因此，MMP 3和其他MMP可以调节最佳白细胞外渗所需的多个关键步骤。本项目的目的是阐明MMP 3在伤口愈合过程中白细胞外渗中的功能作用。具体目的1：使用体内小鼠模型鉴定白细胞、成纤维细胞和角质形成细胞对MMP 3依赖性白细胞浸润到伤口环境中的细胞基质蛋白酶贡献，所述体内小鼠模型不存在或具有单个MMP家族成员的靶向过表达。具体目标2。为了检验MMP 3活性调节受伤表皮中随后的MMP家族成员的活化的假设。具体目标3：确定MMP 3和基质蛋白酶依赖性跨内皮迁移过程中调控的细胞机制。这些研究将提供新的见解MMP 3和其他基质蛋白酶在白细胞跨内皮迁移的作用，并提供了一个体内模型系统，在临床环境中测试MMP抑制剂。 公共卫生相关性： 皮肤的创伤需要愈合以维持正常的健康。伤口愈合的一个重要部分是炎症。基质金属蛋白酶如MMP 3可能在伤口愈合过程中调节炎症中起关键作用。

DESCRIPTION (provided by applicant): Upon loss of existing tissue integrity, wound closure is critical for maintenance of the protective epidermal barrier that shields the host from environmental insult and prevents water loss. An essential, initial response during wound repair is the influx of circulating leukocytes that cleanse the wound and also provide activators and growth factors to stimulate fibrogenesis and neovascularization. Members of the matrix metalloproteinase (MMP) family, such as MMP3, are potential key regulators of leukocyte infiltration. MMP3 is upregulated in the epidermis during processes undergoing tissue remodeling. Mice which are null for MMP3 have delayed closure of excisional wounds and demonstrate reduced infiltration of leukocytes in a number of model systems. Furthermore, we find that MMP3-/- animals have an increased sensitivity to SCC progression that is associated with a reduction in neutrophil and macrophage infiltration evident throughout all stages of tumor progression. Based upon these observations, we propose that MMP3 regulates a protective host defense response during wound repair that is reflective of a protective, antitumorigenic response during SCC. A number of molecules known to affect immune cell function can be directly targeted for hydrolysis and release by MMP3 or matrix proteinases which are activated by MMP3. We hypothesize that MMP3, in combination with other matrix proteinases, directly enhances leukocyte extravasation that subsequently influences the wound repair process. Leukocyte infiltration into sites of inflammation requires the coordinate regulation of multiple steps including arrest on endothelium, migration through the endothelial barrier and directed migration through connective tissue towards the site of inflammation. MMP3 is expressed by a variety of cell types including keratinocytes, fibroblasts, endothelial cells and monocytes and can activate other matrix proteinase classes; thus, MMP3 and other MMPs may modulate multiple key steps required for optimal leukocyte extravasation. The goal of this project is to elucidate the functional role of MMP3 in leukocyte extravasation during wound healing. Our specific aims will test our hypothesis as follows: Specific Aim 1: To identity the cellular matrix proteinase contributions of leukocytes, fibroblasts and keratinocytes to MMP3 dependent leukocyte infiltration into the wound environment using in vivo mouse models that are null for or have targeted overexpression of individual MMP family members. Specific Aim 2. To test the hypothesis that MMP3 activity regulates activation of subsequent MMP family members in wounded epidermis. Specific Aim 3: To identity the cellular mechanisms regulated during MMP3 and matrix protease dependent transendothelial migration in vitro. These studies will provide novel insights into the role of MMP3 and other matrix proteinases during leukocyte transendothelial migration and provide an in vivo model system for testing MMP inhibitors in a clinical setting. PUBLIC HEALTH RELEVANCE: Wounding of the skin requires healing to maintain normal health. An essential part of wound healing is inflammation. Matrix Metalloproteinases such as MMP3 may play a key role in regulating inflammation during wound healing.