Molecular Genetics of Oral Inflammatory Diseases Group, Institute for Dental and Craniofacial Sciences, Department of Periodontology, Oral Medicine and Oral Surgery, Charité - University Medicine Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.
Department of Molecular Parasitology, Institute of Biology, Humboldt-Universität zu Berlin, Berlin, Germany.
Front Cell Infect Microbiol. 2023 Jul 4;13:1201394. doi: 10.3389/fcimb.2023.1201394. eCollection 2023.
Entamoeba is an anaerobic protozoan that is strongly associated with inflamed periodontal pockets. It is able to invade the mucosal epithelium of the human host, where it can feed on epithelial cells and elicit a severe innate immune response. Unlike other species, it is considered that cannot form cysts, because it is a non-infectious protozoan. The lack of encystation capability would make it susceptible to periodontal treatment. However, it is not clear how the human host becomes infected with trophozoites. We investigated the ability of to encapsulate in response to an unfavorable environment .
Different strains of , isolated from inflamed periodontal pocket samples, were cultured for 8 days in the presence or absence of the antimicrobials amoxycillin and metronidazole. To reveal cyst formation, we investigated the morphology and ultrastructure of the amoeba by light, fluorescence, transmission and scanning electron microscopy. We also used the fluorescent dye calcofluor white M2R to demonstrate chitin present in the cyst wall.
We observed exocysts and an intra-cystic space separating the encapsulated trophozoite from the environment. Remarkably, cysts showed a smooth surface, polygonal edges and smaller size compared to free-living trophozoites. In addition, encapsulated trophozoites that detached from the cyst wall had a dense cytoplasma without phagocytic vesicles. The cyst walls consisted of chitin as in other species. The encapsulated trophozoids were mononuclear after antibioticinduced encapsulation.
We conclude that cyst formation has significant implications for dissemination and infection and may explain why established treatment approaches often fail to halt periodontal tissue destruction during periodontitis and peri-implantitis.
内阿米巴是一种厌氧原生动物，与发炎的牙周袋密切相关。它能够侵袭人类宿主的黏膜上皮细胞，在那里它可以以上皮细胞为食，并引发严重的先天免疫反应。与其他物种不同，内阿米巴被认为不能形成囊泡，因为它是一种非传染性的原生动物。缺乏形成囊泡的能力会使其易受牙周治疗的影响。然而，目前尚不清楚人体宿主是如何感染内阿米巴滋养体的。我们研究了内阿米巴在不利环境下形成囊泡的能力。
从发炎的牙周袋样本中分离出不同株的内阿米巴，在存在或不存在抗菌药物阿莫西林和甲硝唑的情况下培养 8 天。为了揭示囊泡形成，我们通过光镜、荧光显微镜、透射电镜和扫描电镜观察了变形虫的形态和超微结构。我们还使用荧光染料 calcofluor white M2R 来证明囊壁中存在几丁质。
我们观察到了外囊泡和一个囊内空间，将包裹的滋养体与环境隔离开来。值得注意的是，与自由生活的滋养体相比，囊泡表面光滑，边缘呈多边形，体积更小。此外，从囊壁上脱落的包裹滋养体具有致密的细胞质，没有吞噬小泡。囊壁由几丁质组成，与其他内阿米巴物种相同。在抗生素诱导的囊泡形成后，包裹的滋养体呈单核。
我们得出结论，内阿米巴囊泡的形成对内阿米巴的传播和感染具有重要意义，这可能解释了为什么在牙周炎和种植体周围炎期间，已有的治疗方法往往无法阻止牙周组织的破坏。
