Host responses against heat shock proteins from periodontopathogenic bacteria

口腔微生物的代谢在很大程度上受到环境变化的影响，这也导致应激蛋白如热休克蛋白（HSPs）的合成。热休克蛋白属于一些高度保守的同源家族。由于HSPs是牙周病的免疫显性抗原，因此我们将其作为牙周病的病原体进行研究。结果表明，牙周致病菌来源的HSP 60家族的GroEL样蛋白与人源的GroEL样蛋白具有交叉反应表位。直接使用对应于弯曲杆菌GroEL样蛋白的PCR产物确定核苷酸序列，并进行分析。将推导的氨基酸序列与人HSP 60的氨基酸序列进行比对，证实了其全长的相似性。同源性较高的热休克蛋白及其与宿主分子的共同表位可能是导致自身免疫反应的重要原因，直链梭菌和伴放线杆菌中天然的GroEL样蛋白具有生物学活性。直链梭菌GroEL样蛋白刺激培养上清液中的人牙龈成纤维细胞的汇合单层分泌白细胞介素-6（IL-6）和IL-8。在22小时孵育期间，IL-6和IL-8的量分别增加了5.4倍和3.5倍。伴放线菌GroEL样蛋白在较高浓度下对体外培养的牙周膜上皮细胞和HaCaT上皮细胞均具有显著的细胞毒性作用。另一方面，我们利用免疫电镜技术，用特异性抗体对伴放线菌GroEL样蛋白进行了外部定位。这些结果表明，伴放线放线菌GroEL-like蛋白和直肌放线菌GroEL-like蛋白具有影响宿主细胞的生物学活性，可能在牙周病中发挥重要作用。

The metabolism of oral microorganisms is largely influenced by the changing environment which also lead to the synthesis of stress proteins such as heat shock proteins (HSPs). HSPs belong to some families of highly conserved homology. We focused on the periodontal disease and HSPs as periodontopathogen because these proteins were immunodominant antigens. Our results indicated that the GroEL-like protein, belonging to HSP60 family, from periodontopathogens possessed epitope cross-reactive with that from human origin. The nucleotide sequence was determined directly using the PCR product corresponding to the Campylobacter rectus GroEL-like protein, and analyzed. By the comparison of the alignment of the deducted amino acid sequence with those of human HSP60, the similarity throughout its length was confirmed. It is possible that high homology of HSPs within the same family and their common epitopes with host molecule lead to autoimmune responses.The native GroEL-like protein from C.rectus and Actinobacillus actinomycetemcomitans possessed biological activities. The C.rectus GroEL-like protein stimulated both interleukin-6 (IL-6) and IL-8 secretion by a confluent monolayer of human gingival fibroblast in their culture supernatant. During the 22h-incubation, the amounts of IL-6 and IL-8 were increased by 5.4- and 3.5-fold, respectively. A.actinomycetemcomitans GroEL-like protein had a significant cytotoxic effect on both periodontal ligament epithelial cells and HaCaT epithelial cells grown in vitro at higher concentrations. On the other hand, we determined the external localization of A.actinomycetemcomitans GroEL-like protein with specific antibodies using immunoelectron microscopy. These results demonstrated that the A.actinomycetemcomitans GroEL-like protein and the C.rectus GroEL-like protein possessed biological activities influencing on the host cells, therefore, these proteins could play important roles in periodontal disease.