Characterization of host-parasite interactions between the oral mucosa and the protozoan Entamoeba gingivalis that drive tissue invasion, destruction and microbial dysbiosis

牙周炎（PD）是一种常见的口腔炎症性疾病，在西方国家，严重形式的患病率为11%。疾病的过程导致牙齿和牙槽骨的结缔组织的破坏，随后牙齿脱落。PD的特征在于龈下微生物群的微生物转移。这种菌群失调长期激活易感个体的免疫系统，导致牙周组织的破坏。确定驱动生态失调、炎症和组织破坏的特定病原体将有助于PD的诊断和治疗。与口腔炎症部位的微生物多样性普遍减少相反，原生动物生殖内阿米巴（E。牙龈炎）的rRNA显著增加，贡献了在PD中发现的仅次于人rRNA的第二丰富的rRNA。在我们的前期工作中，我们检测到了E。在76%的发炎牙周袋和20%的健康口腔中发现了牙龈炎，并证明它会引发炎症，破坏口腔屏障，并能够侵入口腔粘膜，在那里它移动并以宿主细胞为食。与结肠寄生虫E.虽然与溶组织阿米巴有关，但我们的初步数据表明，这种口腔内阿米巴的入侵策略涉及粘蛋白和基质金属蛋白酶（MMP）的功能。这些蛋白质的胞吐作用分别由囊泡相关膜蛋白VAMP 8和VAMP 3协调。两者都是已发表的PD遗传风险位点。为了详细阐明防御和感染机制，我们将描述VAMP8和VAMP3在E. gingivalis感染，定义粘蛋白和MMP依赖的组织侵入和破坏策略，并确定这种原生动物寄生虫与口服抗菌肽的相互关系。此外，我们将进行从头测序的E。gingivalis基因组我们将进一步确定口腔细菌，优先吞噬的大肠杆菌。牙龈炎由于这种寄生虫的致病机制可能是目前病因学概念无法解释的破坏性PD形式的重要微生物触发因素，并且还可能导致PD相关全身性疾病（如口腔癌和心血管疾病）的风险增加，因此我们预计我们的结果与牙科和普通医学高度相关。

Periodontitis (PD) is a common inflammatory disease of the oral cavity, with prevalence rates of 11% in Western countries for severe forms. The course of disease leads to destruction of the connective tissue of the teeth and alveolar bone with subsequent tooth loss. PD is characterized by a microbial shift of the subgingival microbiota. The dysbiosis chronically activates the immune system in predisposed individuals leading to destruction of the periodontium. Identification of a specific pathogen that drives dysbiosis, inflammation and tissue destruction would help in the diagnosis and treatment of PD. In contrast to the generally reduced microbial diversity at the sites of oral inflammation, the prevalence of the protozoan Entamoeba ginigivalis (E. gingivalis) is significantly increased, contributing the second most abundant rRNA found in PD after human rRNA. In our preliminary works, we detected E. gingivalis in 76% of inflamed periodontal pockets and in 20% of the healthy oral cavities, and gave evidence that it triggers inflammation, drives destruction of the oral barrier and is able to invade the oral mucosa where it moves and feeds on host cells. Similar to the colonic parasite E. histolytica, to which it is related, our preliminary data indicated that the invasion strategies of this oral Entamoeba species involve mucin and matrix metalloproteinase (MMP) function. The exocytosis of these proteins is orchestrated by the vesicle associated membrane proteins VAMP8 and VAMP3, respectively. Both are published genetic risk loci of PD. To elucidate the defense and infection mechanisms in detail, we will characterize the role of VAMP8 and VAMP3 in the pathogenicity of E. gingivalis infection, define the mucin and MMP-depending tissue invasion and destruction strategies, and identify the interrelation of this protozoan parasite with oral antimicrobial peptides. Additionally, we will perform de novo sequencing of the E. gingivalis genome. We will further identify the oral bacteria that are preferentially phagocytosed by E. gingivalis. Because the pathogenic mechanisms of this parasite could be an important microbial trigger of destructive forms of PD that cannot be explained by current etiological concepts, and could also contribute to an increased risk for PD-associated systemic diseases like oral cancer and cardiovascular diseases, we anticipate our results highly relevant to dental and general medicine.