Department of Oral Medicine, Division of Endodontics, Kanagawa Dental College, Yokosuka 238-8580, Japan.
Arch Oral Biol. 2012 Nov;57(11):1522-8. doi: 10.1016/j.archoralbio.2012.07.012. Epub 2012 Aug 28.
Actinomyces naeslundii, plays an important role in forming dental biofilms and causes gingival inflammation. Although peptidoglycan, the major cell wall component of Gram-positive bacteria, has been demonstrated to induce inflammatory cytokines, little is known about the association of peptidoglycan with alveolar bone resorption. This study investigated the involvement of peptidoglycan from A. naeslundii in osteoclast formation and bone resorption.
Osteoclast formation and function induced by peptidoglycan of A. naeslundii T14V were examined using the co-culture system of MCTC3/PA6 cells and BALB/c mouse bone marrow cells. Osteoclast formation was evaluated to count TRAP-positive multi-nuclei cells as osteoclasts. The function of osteoclasts was assessed by measuring the areas of pits absorbed. Inflammatory cytokine genes expressions, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α, were examined by RT-PCR analysis using murine peritoneal macrophages. Experimental periodontitis was performed in Sprague-Dawley rats orally infected with A. naeslundii.
TRAP-positive multi-nuclei cells and the areas of pits induced by peptidoglycan were significantly greater than controls (p<0.01). Gene expression levels of IL-1β, IL-6, and TNF-α induced by A. naeslundii PGN were stronger than controls. In experimental periodontitis, bone loss of A. naeslundii-infected rats was comparable to that of rats induced by Porphyromonas gingivalis, which has been reported to be a periodontal pathogenic agent, being significantly greater than that of the sham group (p<0.01).
These results suggest that peptidoglycan of A. naeslundii is an important virulence factor in the development of periodontitis.
放线菌奈瑟氏菌在形成牙菌斑和引起牙龈炎症方面起着重要作用。虽然革兰氏阳性菌的主要细胞壁成分肽聚糖已被证明能诱导炎症细胞因子，但人们对肽聚糖与牙槽骨吸收的关系知之甚少。本研究探讨了放线菌奈瑟氏菌肽聚糖在破骨细胞形成和骨吸收中的作用。
使用 MCTC3/PA6 细胞和 BALB/c 小鼠骨髓细胞的共培养系统，检测放线菌奈瑟氏菌 T14V 肽聚糖诱导的破骨细胞形成和功能。通过计数 TRAP 阳性多核细胞作为破骨细胞来评估破骨细胞的形成。通过测量吸收陷窝的面积来评估破骨细胞的功能。通过 RT-PCR 分析检测炎性细胞因子基因表达，如白细胞介素（IL）-1β、IL-6 和肿瘤坏死因子（TNF）-α，使用鼠腹腔巨噬细胞。通过口腔感染放线菌奈瑟氏菌在 Sprague-Dawley 大鼠中进行实验性牙周炎。
TRAP 阳性多核细胞和肽聚糖诱导的陷窝面积明显大于对照组（p<0.01）。放线菌奈瑟氏菌 PGN 诱导的 IL-1β、IL-6 和 TNF-α基因表达水平强于对照组。在实验性牙周炎中，感染放线菌奈瑟氏菌大鼠的骨丢失与已报道的牙周病病原体牙龈卟啉单胞菌诱导的大鼠相当，明显大于假手术组（p<0.01）。
这些结果表明，放线菌奈瑟氏菌的肽聚糖是牙周炎发展的重要毒力因子。
