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

牙周炎是一种常见的口腔炎症性疾病，在西方国家严重的患病率为11%。病程导致牙齿和牙槽骨的结缔组织破坏，继而牙齿脱落。PD的特征是龈下微生物区系的微生物移位。这种生物失调长期激活易患个体的免疫系统，导致牙周组织的破坏。识别导致生物失调、炎症和组织破坏的特定病原体将有助于帕金森病的诊断和治疗。与口腔炎症部位微生物多样性普遍下降相反，原生动物牙龈内阿米巴(E.gigivalis)的流行率显著增加，在帕金森病中仅次于人类rRNA。在我们的初步工作中，我们在76%的牙周炎牙周袋和20%的健康口腔中检测到牙龈埃希氏菌，并提供了证据表明，它引发炎症，驱动口腔屏障的破坏，并能够入侵口腔粘膜，在那里它移动并以宿主细胞为食。与与其相关的结肠寄生虫组织内阿米巴相似，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(MMPs)功能。这些蛋白的胞吐作用分别由囊泡相关膜蛋白VAMP8和VAMP3协调。这两个都是已公布的帕金森病的遗传风险基因座。为了更详细地阐明VAMP8和VAMP3的防御和感染机制，我们将研究VAMP8和VAMP3在牙周炎致病中的作用，确定依赖粘蛋白和基质金属蛋白酶的组织侵袭和破坏策略，并确定这种原虫寄生虫与口腔抗菌肽的相互关系。此外，我们还将对牙龈假单胞菌基因组进行从头测序。我们将进一步鉴定哪些口腔细菌优先被牙周炎埃希氏菌吞噬。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PD破坏性形式的重要微生物触发因素，还可能导致与PD相关的系统性疾病(如口腔癌和心血管疾病)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.