Department of Oromaxillofacial Infection and Immunity, Brain Korea 21 CLS, School of Dentistry and Dental Research Institute, Seoul National University, Seoul 110-749, Korea.
Mol Cells. 2010 Dec;30(6):519-26. doi: 10.1007/s10059-010-0142-8. Epub 2010 Nov 5.
The role of Fusobacterium nucleatum in oral health and disease is controversial. We have previously shown that F. nucleatum invades gingival epithelial cells. However, the destiny of the internalized F. nucleatum is not clear. In the present study, the intracellular destiny of F. nucleatum and its cytopathic effect on gingival epithelial cells were studied. The ability of F. nucleatum and seven other oral bacterial species to invade immortalized human gingival epithelial (HOK-16B) cells were compared by confocal microscopy and flow cytometry. F. nucleatum had the highest invasive capacity, comparable to that of Porphyromonas gingivalis, a periodontal pathogen. Confocal microscopic examination revealed colocalization of internalized F. nucleatum with endosomes and lysosomes. Examination by transmission electron microscopy revealed that most intracellular F. nucleatum was located within vesicular structures with single enclosed membranes. Furthermore, F. nucleatum could not survive within gingival epithelial cells and had no cytopathic effects on host cells. Interestingly, endosomal maturation played a role in induction of the antimicrobial peptides human beta defensin (HBD)-2 and -3 by F. nucleatum from gingival epithelial cells. F. nucleatum is destined to enter an endocytic degradation pathway after invasion and has no cytopathic effect on gingival epithelial cells, which may cast new light on the role of F. nucleatum in the pathogenesis of periodontitis.
具核梭杆菌在口腔健康和疾病中的作用存在争议。我们之前已经表明，具核梭杆菌能够侵袭牙龈上皮细胞。然而，内化的具核梭杆菌的命运尚不清楚。在本研究中，我们研究了具核梭杆菌的细胞内命运及其对牙龈上皮细胞的细胞病变作用。通过共聚焦显微镜和流式细胞术比较了具核梭杆菌和其他七种口腔细菌物种侵袭永生化人牙龈上皮（HOK-16B）细胞的能力。具核梭杆菌具有最高的侵袭能力，与牙周病病原体牙龈卟啉单胞菌相当。共聚焦显微镜检查显示内化的具核梭杆菌与内体和溶酶体共定位。透射电子显微镜检查显示，大多数细胞内的具核梭杆菌位于具有单个封闭膜的囊泡结构内。此外，具核梭杆菌不能在牙龈上皮细胞内存活，也不会对宿主细胞产生细胞病变作用。有趣的是，内体成熟在诱导牙龈上皮细胞中由具核梭杆菌产生的人β防御素（HBD）-2 和 -3 中发挥作用。具核梭杆菌在入侵后注定要进入内吞降解途径，并且对牙龈上皮细胞没有细胞病变作用，这可能为具核梭杆菌在牙周炎发病机制中的作用提供新的认识。
