Department of Oral Medicine, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
Arch Oral Biol. 2012 Jul;57(7):964-72. doi: 10.1016/j.archoralbio.2012.01.014. Epub 2012 Feb 19.
Aggregatibacter actinomycetemcomitans is known to be a major cause of localized aggressive periodontitis. Previous research has suggested that A. actinomycetemcomitans can damage many types of host cells. There is evidence for the ability of this organism to invade endothelial and epithelial cells, but information pertaining to its potential for invading gingival fibroblasts is very limited. Internalization of bacteria is not only responsible for damaging host tissue but also a means to evade the host immune response. It was hypothesized that A. actinomycetemcomitans can invade and reside in human gingival fibroblasts (HGF).
Primary cultures of HGF were infected with A. actinomycetemcomitans at a ratio of 1:100. Bacterial internalization was determined by an antibiotic protection assay. Bacterial-fibroblast interaction was examined using phase-contrast, scanning and transmission electron microscopy.
It was demonstrated that A. actinomycetemcomitans was internalized into HGF at an efficiency of 0.084%. Transmission electron microscopic study showed the presence of A. actinomycetemcomitans in the cytoplasm of HGF without the surrounding membrane. Scanning electron micrographs revealed the sloughing of HGF surfaces on which A. actinomycetemcomitans adhered. Rounded cells, attachment loss and damaged cells were also observed.
It is concluded that the attachment and invasion of A. actinomycetemcomitans into human gingival fibroblasts play a role in periodontal tissue damage and may also be a means of immune evasion.
放线共生放线杆菌是导致局限性侵袭性牙周炎的主要原因之一。先前的研究表明，放线共生放线杆菌可以破坏多种宿主细胞。有证据表明该菌能够侵袭内皮细胞和上皮细胞，但关于其侵袭牙龈成纤维细胞的能力的信息非常有限。细菌的内化不仅负责破坏宿主组织，也是逃避宿主免疫反应的一种手段。假设放线共生放线杆菌可以侵袭并定殖于人牙龈成纤维细胞（HGF）。
用 A. actinomycetemcomitans 以 1:100 的比例感染原代培养的 HGF。通过抗生素保护试验测定细菌内化。使用相差、扫描和透射电子显微镜检查细菌-成纤维细胞相互作用。
证明 A. actinomycetemcomitans 以 0.084%的效率内化到 HGF 中。透射电子显微镜研究显示，A. actinomycetemcomitans 存在于 HGF 的细胞质中，没有周围的膜。扫描电子显微镜显示出 A. actinomycetemcomitans 附着的 HGF 表面脱落。还观察到圆形细胞、附着丧失和受损细胞。
结论是 A. actinomycetemcomitans 对人牙龈成纤维细胞的附着和侵袭在牙周组织损伤中起作用，也可能是免疫逃避的一种手段。
