Pathogenic mechanisms of F. alocis

描述（由申请人提供）：牙周病是人类最常见的细菌感染之一，对卫生保健系统造成了重大负担。基于分子的细菌检测技术的最新发展已经确定了许多以前未被认识或未被重视的与牙周病变相关的微生物。其中一种新出现的病原体是革兰氏阳性厌氧菌嗜酸丝状杆菌。这种微生物是牙龈下生物膜的一个组成部分，与健康的人相比，在牙周病的部位数量增加。F. alocis产生蛋白酶，可侵袭牙龈上皮细胞；然而，关于这种有机体的潜在致病性，人们所知甚少。为了利用人类微生物组研究，有必要对新鉴定的生物体进行功能表征。因此，在这项研究中，我们将有助于评估F. alocis在体外和体内的致病潜力。我们的初步数据表明，金黄色葡萄球菌可以诱导牙龈上皮细胞凋亡

DESCRIPTION (provided by applicant): Periodontal diseases are one of the most common bacterial infections of humans and impose a significant burden on the health care system. Recent developments in molecular based bacterial detection technologies have identified a number of previously unrecognized or under-appreciated organisms as associated with periodontal lesions. One such emerging pathogen is the gram-positive anaerobe Filifactor alocis. This organism is a constituent of subgingival biofilms and is present in elevated numbers at site of periodontal disease as compared to health. F. alocis produces proteases and can invade gingival epithelial cells; however, little else is known regarding the potential pathogeniciy of the organism. In order to capitalize on the human microbiome studies it is necessary to functionally characterize the newly identified organisms. Hence, in this study we shall contribute to the process of assessing the pathogenic potential of F. alocis in vitro and in vivo. Our preliminary data indicate that F. alocis can induce apoptosis in gingival epithelial cells an event with relevance to disruption of periodontal tissue homeostasis. The first goal of the current proposal, therefore, is to begin to characterize the mechanistic basis of F. alocis-induced apoptosis. We will focus on the MEK-FOXO pathway as preliminary data show that F. alocis can inhibit MEK and potentially activate the pro-apoptotic transcriptional factor FOXO. The role of MEK will be assessed by gene knockin experiments with constitutively mutants, and the relevance of FOXO determined by reporter assays and siRNA knockdowns. Secondly, we will establish the in vivo characteristics of F. alocis in the mouse chamber model. The ability of F. alocis to survive and replicate in vivo will be established and, in addition, host cytokine responses, neutrophil recruitment and apoptosis will be assayed. These studies will generate both in vitro and in vivo data that will begin to establish the pathogenic credentials of F. alocis and provide a platform for future studies directed toward a more comprehensive understanding of molecular and cellular pathogenic mechanisms. Ultimately, the knowledge gained could be translated into novel diagnostic, therapeutic or preventive strategies for periodontal diseases.