Inflammasome Danger Signaling:A Novel Target to Prevent Debris Induced Osteolysis

描述(由申请人提供)：由于植入碎片引起的炎症反应，如果接受者存活足够长，在美国每年进行的所有一百万例关节置换手术预计最终都会失败。这对数百万老年人来说尤其令人担忧，他们在生命的最后几十年可能需要修改，因为在这些人中，大手术的死亡率可能高达13%(而75岁患者的死亡率为1%)。目前还没有延长植入物寿命的非手术治疗方法。众所周知，碎片诱导的炎症可以诱导局部先天免疫反应，即单核/巨噬细胞激活核因子，分泌IL-1、TNF、IL-6和IL-8，从而导致局部炎症。然而，植入物碎片是无菌的，相对惰性，不呈现典型病原体的分子模式。那么，细胞外和细胞内机制如何感知和响应外源非生物挑战因素，如植入碎片？最近的进展表明，“炎症体”参与了危险信号传递途径。我们最近发表的关于植入碎片诱导的炎症体激活的初步发现为这一途径提供了重要的见解，该途径可以感知接触某些非生物挑战剂引发的应激和危险信号，包括现代疫苗中存在的颗粒佐剂。这些结果表明，炎症体危险信号是增强天然巨噬细胞对植入碎片的反应的中心(即从最初的溶酶体失稳和NADPH氧化酶诱导的ROS，到NALP3-ASC齐聚，以及Caspase1将原-IL-1转化为IL-1。我们的长期目标是了解如何操纵炎性小体途径来减轻种植体碎片的不良影响。这项建议的目的是确定这一方法的实用性以及如何最好地减轻种植体碎屑引起的骨溶解。几个关键问题是：1)炎性小体途径的哪个成分(S)最有针对性地减少碎屑介导的炎症？2)抑制碎屑诱导的炎性小体激活能否导致体内无菌性溶骨作用的减少，即它是药物治疗的有效靶点吗？3)碎屑诱导的炎性小体激活是否优先发生在碎屑诱导的无菌性溶骨症患者中？我们建议在以下中心假设下考察这三个问题。我们推测种植体碎屑诱导的炎症危险信号是种植体碎屑免疫反应的中心环节，阻断这种反应是减轻种植体碎屑引起的无菌性骨溶解的有效手段。我们计划测试我们的中心假设，并通过追求以下三个具体目标来实现此应用程序的目标。具体目的1是确定，临床上可用的炎症体特异性药物在预防一般巨噬细胞炎症反应方面是否与其他(非临床)炎症体途径特异性抑制剂一样有效，以及溶酶体失稳是否在Debrs诱导的炎症体激活的启动中起关键作用。具体目的2是利用已建立的动物模型，确定阻断炎症体途径对颗粒诱导的炎症和无菌磨损颗粒诱导的骨溶解的影响。具体目标3是确定通过阻断炎症小体途径来治疗碎屑引起的炎症的临床相关性。我们将测试选择性炎性小体抑制对磨屑诱导的促炎细胞因子产生的有效性，并通过定量免疫组织化学和组织细胞因子表达来确定这些作用是否与种植周围组织的炎性小体活动相关。这项翻译研究将确定炎性小体危险信号对种植体碎片的激活是否是从药物上解决无菌骨溶解的有效新靶点。我们希望在很大程度上促进我们对无菌非生物植入碎片如何实际诱导免疫系统反应，从而导致无菌骨溶解的理解。这些结果将为数百万接受植入物的人提供积极的影响和潜在的有效治疗，特别是那些75岁以上的人，他们可能能够阻止植入物碎片相关的骨溶解，无限期推迟翻修全关节置换手术的相关发病率和死亡率。

DESCRIPTION (provided by applicant): All of the > one million total joint replacements/year that are performed in the United States are expected to eventually fail if their recipients live log enough, due to implant debris induced inflammatory responses. This is particularly troubling for millions of elderly people who may need a revision in their last decades of life where the incidence of mortality of major surgery can be as high as 13% (vs. <1% in patients <75 years of age). Non-surgical treatments to extend implant life are currently unavailable. Debris induced inflammation is well known to induce local innate immune responses, i.e. monocytes/macrophages activate NF and secretion of IL-1, TNF, IL-6 and IL-8 resulting in localized inflammation. However, implant debris are sterile, relatively inert, and do not present the molecular patterns of a typical pathogen. So, how do extra- and intracellular mechanisms sense and respond to exogenous non-biological challenge agents such as implant debris? Recent progress points to the involvement of the "inflammasome", a danger signaling pathway. Our recently published initial findings on implant debris-induced inflammasome activation provide an important insight into this pathway that can sense stress and danger signals triggered by contact with certain non-biological challenge agents, including particulate adjuvants present in modern vaccines. These results suggest that inflammasome danger signaling is central to potentiating innate macrophage-based responses to implant debris (i.e. from initial lysosomal destabilization and NADPH oxidase induction of ROS, to NALP3-ASC oligomerization, and Caspase 1 conversion of pro-IL-1 to IL-1. Our long term goal is to understand how to manipulate the inflammasome pathway to mitigate the untoward effects of implant debris. The objective of this proposal is to determine both the utility of this approach an how best to mitigate implant debris induced osteolysis. Several key questions are: 1) what component(s) of the inflammasome pathway are best targeted to reduce debris-mediated inflammation? 2) Can inhibition of debris induced inflammasome activation lead to decreased aseptic osteolysis in vivo, i.e. is it a viable target for pharmacotherapy? 3) Does debris induced inflammasome activation preferentially occur in people with debris-induced aseptic osteolysis? We propose to examine these three questions under the following central hypothesis. We hypothesize that implant debris induced inflammasome danger signaling is central to implant debris immune reactivity and blocking this response is an effective means to mitigate implant debris induced aseptic osteolysis. We plan to test our central hypothesis and accomplish the objective of this application by pursuing the following three specific aims. Specific Aim 1 is to determine, whether clinically available inflammasome-specific drugs are as effective in preventing general macrophage inflammatory responses vs. other (non-clinical) inflammasome-pathway-specific inhibitors and if lysosomal destabilization is critical for the initiation of debrs-induced inflammasome activation. Specific Aim 2 is to determine the effect of blocking the inflammasome pathway on particle induced inflammation and aseptic wear debris-induced osteolysis using an established animal model. Specific Aim 3 is to determine the clinical relevance of treating debris-induced inflammation by blocking the inflammasome pathway. We will test the effectiveness of selective inflammasome inhibition on wear debris-induced pro-inflammatory cytokine production by primary monocyte/macrophage cultures from arthroplasty cohorts, and determine if these effects correlate with inflammasome activity in peri-implant tissues determined by quantitative immunohistochemistry and tissue cytokine expression. This translational study will determine if inflammasome danger signaling activation to implant debris is an effective new target for pharmacologically addressing aseptic osteolysis. We expect to substantially forward our understanding of how sterile non-biological implant debris actually induces an immune system response that leads to aseptic osteolysis. Such results will provide a positive impact and potentially powerful treatment for millions of people with implants, particularly those over 75 years of age, who may be able to block implant debris associated osteolysis, postponing indefinitely the associated morbidity and mortality of revision total joint replacement surgery.