MECHANISMS OF NOVEL ANTI-INFLAMMATORY ACTIONS OF SLPI

描述(由申请人提供)： 分泌性白细胞蛋白酶抑制物(SLPI)和原上皮蛋白(Pepi)最初被发现是两种不相关的上皮细胞分泌产物。SLPI是一种小的12 kDa白细胞蛋白酶抑制剂，而Pepi最为人所知的是上皮蛋白(Epis)的前体，EPIS是一组功能未知的6 kDa多肽，存在于不同的组织和体液中。白细胞，特别是巨噬细胞，也是SLPI和Pepi的丰富来源。在巨噬细胞中，这两种蛋白的表达都受到微生物产物如脂多糖(LPS)的上调。我们已经确定Pepi是一种与SLPI相互作用的蛋白质。我们还发现，Pepi和Epis具有相反的生物活性。EPIS促进炎症反应，而PEPI则下调炎症反应。SLPI与Pepi的结合阻止了其向Epi的转化。SLPI和PEPI均可阻断肿瘤坏死因子诱导的中性粒细胞活化。SLPI还抑制巨噬细胞对内毒素的反应。因此，SLPI和PEPI似乎是一对宿主衍生的抗炎介质，用于防止过度的先天免疫反应。SLPI和PEPI抗炎作用的潜在机制尚不清楚。本项目的目的是进一步探讨SLPI和PEPI的抗炎作用机制。我们将集中于：(1)鉴定Pepi/Epi在白细胞炎症反应中的作用；(2)了解slpi和Pepi影响巨噬细胞功能的分子基础；以及(3)利用Pepi和slpi基因敲除小鼠和slpi转基因小鼠，检测SLPI和Pepi在三种体内炎症模型(皮肤创伤、烟雾诱导的肺气肿和盲肠结扎和穿孔诱导的感染性休克)中的作用。阐明SLPI和PEPI是如何干扰内毒素信号转导的特定步骤的，可能会对包括感染性休克在内的炎症相关疾病的病理生理学以及新的治疗策略的开发具有重要的意义。

DESCRIPTION (provided by applicant): Secretory leukocyte protease inhibitor (SLPI) and proepithelin (PEPI) were originally discovered as two unrelated secreted products of epithelial cells. SLPI is a small 12-kDa leukocyte protease inhibitor, while PEPI is best known as the precursor for epithelins (EPIs), a group of 6-kDa peptides with unknown functions that are found in diverse tissues and body fluids. Leukocytes, especially macrophages, are also rich sources of SLPI and PEPI. Expression of both proteins is upregulated in macrophages by microbial products such as lipopolysaccharide (LPS). We have identified PEPI as a SLPI interacting protein. We also discovered that PEPI and EPIs exert opposing biological activities. EPIs promote whereas PEPI downregulates inflammatory reactions. Binding of PEPI by SLPI prevents its conversion to EPIs. Both SLPI and PEPI block TNF-triggered neutrophil activation. SLPI also suppresses the macrophage response to LPS. Thus, SLPI and PEPI appear to be a pair of host-derived anti-inflammatory mediators that serve to prevent excess innate immune responses. The underlying mechanisms for the anti-inflammatory actions of SLPI and PEPI are poorly understood. The goal of this project is to further explore the mechanisms of the novel anti-inflammatory actions of SLPI and PEPI. We will focus on: (1) characterizing the role of PEPI/EPIs in the inflammatory responses of leukocytes; (2) understanding the molecular basis by which SLPI and PEPI affect macrophage function; and (3) testing the role of SLPI and PEPI in three in vivo inflammation models (cutaneous wounding, smoke-induced emphysema and septic shock induced by cecal-ligation and puncture) using PEPI and SLPI knock out mice and SLPI transgenic mice. Elucidating how SLPI and PEPI interfere with specific steps in LPS signaling may contribute important insights to the pathophysiology of inflammation-related diseases including septic shock and to the development of novel therapeutic strategies.