Molecular analysis of the interaction between immune function and bone metabolisms in periodontitis

通过对牙周病原菌、免疫反应和骨代谢的检测，阐明牙周炎免疫反应和骨代谢之间的相互作用。建立了牙周病细菌的实时定量聚合酶链式反应检测体系。基于该系统，我们发现在心血管疾病合并牙周炎患者手术切除的血管中经常检测到牙周病原菌。此外，牙周炎患者的单核细胞比健康人的单核细胞活化。牙周治疗后即刻血清IL-6浓度明显升高。提示牙周炎可能通过菌血症或激活的单核细胞产生炎性细胞因子而影响全身健康。骨代谢受破骨细胞和成骨细胞的调节，破骨细胞的分化受成骨细胞产生的RANKL和OPG调节。我们曾报道，RANKL在重度牙周炎病变中高表达，牙周炎组织中的T细胞表达RANKL。牙周膜成纤维细胞(PDL)和牙龈成纤维细胞均产生OPG。IL-1促进PDL RANKL的表达，是HGF的5倍，但OPG的产生低于HGF。

Periodontopathic bacteria, immune responses and bone metabolisms were examined to clarify the interaction between immune responses and bone metabolisms in periodontitis. We have established the detection system for periodontopathic bacteria using real-time PCR analysis. Based on the system, we have found that periodontopathic bacteria were frequently detected in the surgically removed vessels from the cardio-vascular disease patients with periodontitis. In addition, monocytes from periodontitis patients were activated compared with healthy subjects. Serum IL-6 concentration was significantly elevated immediately after periodontal treatment. These results suggested that periodontitis might affect systemic health through bacteremia or production of inflammatory cytokines by activated monocytes. Bone metabolisms are regulated by osteoclasts and osteoblasts, and osteoclast differentiation is regulated by RANKL and OPG produced by osteoblasts. We have reported that RANKL expression was high in severe periodontitis lesion, and T-cells from periodontitis tissue expressed RANKL. Both periodontal ligament fibroblasts (PDL) and gingival fibroblasts produced OPG. IL-1 augmented RANKL expression in PDL five times higher than HGF, but OPG production was lower than HGF.