Osteopontin and Integrins in Innate Immune Responses to Polymicrobial Infection

描述(申请人提供)：牙根管和牙髓腔的牙髓感染是一种多菌的局部感染，可导致组织破坏和骨丢失，通常导致牙齿脱落。这些感染的治疗仍然效率低下，失败率高达30%。迫切需要新的方法来控制这些感染。宿主对这些感染的详细反应机制仍不完全清楚。了解这些机制对于它们的控制以及其他多菌感染的控制至关重要，例如糖尿病患者中常见的那些感染。该项目的长期目标是为这些感染开发新的有效和高效的治疗方案。这项应用的目的是了解骨桥蛋白(OPN)-整合素轴在宿主对牙髓感染反应中的作用。OPN是一种分泌的小整合素结合蛋白，在牙髓感染的小鼠模型中具有保护作用，在该模型中，缺乏骨桥蛋白(OPN)的小鼠比WT小鼠有更大的炎症反应和骨丢失。OPN的作用可能是对先天免疫系统的影响，而先天免疫系统是宿主抵御这些感染的主要手段。骨桥蛋白与一系列整合素相互作用，增强包括巨噬细胞和中性粒细胞在内的髓系细胞的迁移和/或功能。这一建议的中心假设是，OPN通过含有v的整合素和/或9整合素来传递信号，以最大化髓系细胞类型在细菌感染时的迁移和效应功能。虽然骨桥蛋白对髓系细胞迁移的影响已经得到了很好的证实，但这种作用的机制及其与整合素的相互作用仍不清楚。本提案中描述的实验旨在回答这些问题，并开始描述OPN结合整合素在根管感染中的作用。在具体目标1中，将使用皮下腔感染模型来确定缺乏OPN的小鼠骨髓细胞聚集和细菌杀伤的早期缺陷。在目标2中，缺乏一种或多种OPN结合整合素的髓系细胞将用于体外试验，以确定与OPN对迁移和功能的影响有关的整合素。新的假说，即OPN的作用机制包括对细胞内循环的影响，将得到检验。目的3将利用所有细胞或仅在髓系细胞中缺乏OPN结合整合素的小鼠，确定OPN结合整合素在牙髓感染的先天免疫反应中的独特作用。这一方法在探索OPN的新作用机制和阐明OPN结合整合素在宿主对多菌感染反应中的未知作用方面具有创新性。该项目特别重要，因为整合素及其配体是NOEL治疗干预的潜在细胞外靶点。

DESCRIPTION (provided by applicant): Endodontic infection of tooth root canals and pulp chambers are polymicrobial localized infections that can cause tissue destruction and bone loss, often resulting in tooth loss. Treatment of these infections remains inefficient, with up to a 30% failure rate. There is a strong need for novel approaches to control these infections. The detailed mechanism of the host response to these infections remains incompletely understood. Understanding these mechanisms will be critically important in their control, as well as the control of other polymicrobial infections such as those that are common in diabetic patients. The long term goal of this project is to develop novel effective and efficient treatment regimens for these infections. The objective of this application is to understand the role of the osteopontin (OPN)-integrin axis in the host response to endodontic infection. OPN is a secreted small integrin-binding protein that has a protective effect in a mouse model of endodontic infection, where mice lacking osteopontin (OPN) have significantly greater inflammatory response and bone loss than WT mice. The effect of OPN is likely to be on the innate immune system, which is the primary means of host defense against these infections. Osteopontin interacts with a series of integrins to enhance migration and/or function of myeloid cells including macrophages and neutrophils. The central hypothesis of this proposal is that OPN signals through ¿v-containing integrins and/or the ¿9¿1 integrin to maximize migration and effector functions of myeloid cell types in response to bacterial infection. While the effect of OPN on migration of myeloid cells has been well established, the mechanism of this effect and the integrins with which it interacts are still poorly understood. Experiments described in this proposal are designed to answer these questions and to begin to describe the role of the OPN-binding integrins in endodontic infection. In Specific Aim 1, a subcutaneous chamber infection model will be used to determine the early defects in myeloid cell accumulation and bacterial killing in mice lacking OPN. In Aim 2, myeloid cells deficient for one or more of several OPN-binding integrins: the ¿v, ¿9, ¿3 or ¿5 integrin will be used in in vitro assays to define the integrins responsible fr the effects of OPN on migration and function. The novel hypothesis that the mechanism of action of OPN includes effects on endocytic recycling will be tested. Aim 3 will determine the unique role of the OPN-binding integrins in the innate immune response to endodontic infection, using mice deficient for these integrins in all cells, or just in myeloid cells. This approach is innovative in exploring new mechanisms of action of OPN and elucidating the uncharacterized role of the OPN-binding integrins in the host response to polymicrobial infection. The project is especially significant since integrins and their ligands are potential extracellular targets for noel therapeutic interventions.