Host Response to Challenge with Porphyromonas gingivalis DNA

描述（由申请人提供）：牙周病是最常见的人类疾病之一，折磨着15%的人口。最近的数据表明牙周炎是许多其他系统性并发症的致病疾病。牙龈卟啉单胞菌被认为是最致命的牙周病病原体之一，也是牙周病发展的病原。在没有疾病的情况下，它也存在于口腔中。尽管细菌与宿主的相互作用对于了解疾病机制具有重要意义，但对宿主以及参与相互作用的病原体成分仍然知之甚少。体外研究表明，牙龈假单胞菌可以侵袭多种细胞类型，包括牙龈上皮细胞。它也被证明可以防止这些细胞的凋亡，复制并传播到周围细胞。有趣的是，牙龈卟啉卟啉菌已被证明在健康和易感宿主中都能进行这些活动。研究也揭示了牙龈卟啉卟啉的复杂性，由于不同的结果根据，并密切相关；宿主细胞类型、菌株、初始接种、活菌（代谢活性）与死菌的使用，或特定细菌成分（如半胱氨酸蛋白酶、脂多糖）的存在。一些研究集中在受细菌成分挑战的toll样受体介导的宿主细胞反应上，以深入了解先天免疫反应的开始。在这些细菌成分中，很少有人关注DNA，特别是在口腔上皮细胞中。为了进一步了解牙龈假单胞菌的发病机制，我们将重点关注细菌的一个组成部分，DNA。本研究的具体目的包括：(1)表征两种口腔上皮细胞系和两名患者的原代细胞对牙龈假单胞菌W83 DNA攻击的反应，(2)TLR9在介导这种反应中的作用，以及(3)其他可能在这种相互作用中发挥作用的DNA受体。初步的体外研究表明，口腔上皮细胞系HN4在转录水平上通过基因调控对来自牙龈假单胞菌的DNA的攻击作出反应。此外，我们已经证明HN4细胞摄取CpG寡核苷酸。另外一项初步研究表明，TLR9敲低的HN4细胞系受到牙龈假单胞菌DNA攻击后，基因调控似乎没有受到显著影响，因此，我们计划研究细胞质DNA受体DAI，它也可能在牙龈假单胞菌的发病机制中发挥作用。

DESCRIPTION (provided by applicant): Periodontal disease is one of the most common human diseases afflicting 15% of the population. Recent data has implicated periodontitis as a causative disease for many other systemic complications. Porphoromonas gingivalis is named one of the most virulent periodontopathogens and an etiological agent in the progression of this disease. It also is present in the oral cavity in the absence of the disease. Although the interaction of the bacterium with the host is of major importance for the understanding of the disease mechanisms, both the host as well as the pathogen components involved in the interaction remain poorly understood. In vitro studies have revealed that P. gingivalis can invade a variety of cell types including gingival epithelial cells. It has also been demonstrated to prevent apoptosis in these cells, replicate, and disseminate to surrounding cells. Interestingly, P. gingivalis has been shown to perform these activities in both healthy and susceptible hosts. Studies have also reveled the complex nature of P. gingivalis due to varying results according to, and closely associated with; the host cell type, bacterial strain, initial inoculation, and the use of live (metabolically active) versus dead bacteria, or the presence of specific bacterial components (e.g. cysteine proteinases, LPS). Several studies have focused on the host cell responses mediated by Toll-like receptors challenged with bacterial components to gain insight on the initiation of the innate immune response. Of these bacterial components, little attention has been paid to DNA, especially in oral epithelial cells. To further understand the pathogenesis of P. gingivalis, we will be focusing on one bacterial component, DNA. The specific aims of this study include: (1) The characterization of the response of two oral epithelial cell lines and primary cells harvested from two patients to challenge with P. gingivalis W83 DNA, (2) The role of TLR9 in mediating this response, and (3) other DNA receptors that may play a role in this interaction. Initial in vitro studies revealed that the oral epithelial cell line HN4 responds to challenge with DNA derived from P. gingivalis with gene regulation at the transcriptional level. In addition, we have demonstrated that HN4 cells uptake CpG oligonucleotides. An additional preliminary study has shown that gene regulation does not seem to be significantly impacted in TLR9 knockdown HN4 cell lines that were challenged with P. gingivalis DNA, therefore, we plan to examine the cytosolic DNA receptor DAI, which also may play a role in the pathogenesis of P. gingivalis. Public health Relevance: This study will lead to a greater understanding of the mechanisms of the host response that contribute to the pathogenesis of P. gingivalis W83. These studies may then reveal potential targets for preventing the initiation of periodontal disease.