Host Response to Challenge with Porphyromonas gingivalis DNA

描述(申请人提供)：牙周病是最常见的人类疾病之一，困扰着15%的人口。最近的数据表明，牙周炎是许多其他全身并发症的致病原因。牙龈假单胞菌是一种最致命的牙周病原体，也是本病发生发展的病原菌之一。在没有这种疾病的情况下，它也存在于口腔中。虽然细菌与宿主的相互作用对于了解疾病的发病机制非常重要，但宿主以及参与相互作用的病原菌成分仍然知之甚少。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。它还被证明可以防止这些细胞中的凋亡，复制并扩散到周围的细胞。有趣的是，牙龈假单胞菌已被证明在健康和易感宿主中都有这些活动。研究还揭示了牙龈假单胞菌的复杂性，这是由于根据宿主细胞类型、细菌菌株、初始接种、使用活的(代谢活性的)细菌与死亡的细菌或特定细菌成分(如半胱氨酸蛋白酶、脂多糖)的存在而产生的不同结果，并与之密切相关。一些研究集中在用细菌成分挑战Toll样受体介导的宿主细胞反应，以深入了解先天免疫反应的启动。在这些细菌成分中，对DNA的关注很少，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，我们将重点研究一种细菌成分，DNA。本研究的具体目的包括：(1)两个口腔上皮细胞株和两个患者的原代细胞对牙龈假单胞菌W83 DNA攻击的反应的表征；(2)TLR9在介导这一反应中的作用；(3)可能在这种相互作用中发挥作用的其他DNA受体。初步的体外研究表明，口腔上皮细胞系HN4对牙龈假单胞菌DNA的攻击具有转录水平上的基因调控作用。此外，我们还证明了HN4细胞摄取CpG寡核苷酸。另一项初步研究表明，在TLR9基因敲除的HN4细胞系中，基因调控似乎没有受到明显影响，因此，我们计划检测细胞质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。 公共卫生相关性：这项研究将有助于更好地理解宿主反应的机制，这些机制有助于牙龈假单胞菌W83的发病。这些研究可能会揭示预防牙周病的潜在靶点。

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.