齲蝕関連細菌の樹状細胞成熟に及ぼす影響について

Dendritic cells are known as potent antigen presenter to T cells and play important roles in the initiation of immune responses. When immature dendritic cells are exposed to antigens, they begin to maturate by changing their expression of membrane molecules, i.e., MHC class II, CD86, and CD83, and home to a regional lymph node to present the antigens to T cells. In dental pulp, dendritic cells are observed beneath the odontoblast layer. Immune system in pulp may start to work when these dendritic cells encounter antigens of microorganisms invading dentinal tubules. However, the priming potential of the bacteria in carious lesions on the maturation of dendritic cells is still unknown. Hence, we investigate the maturation of dendritic cells induced by the bacteria in carious lesions using a co-culture system. In this system, we selected 6 species of bacteria frequently detected in carious lesions. Dendritic cells derived from peripheral blood monocytes were co-cultured with these heat-killed bacteria. Bacteria in the carious lesion would be modified by serum components (immunoglobulins, complements) or a saliva component (sIgA). These modifications may influence the maturation process of pulp dendritic cells when these cells have been primed with those bacteria. Thus, we also investigate the influences of serum or saliva-treatment of the bacteria on the maturation of dendritic cells. When dendritic cells were co-cultured with Streptococcus mutans, their expression of MHC class II, CD86, and CD83 up-regulated with the increasing number of stimulating bacteria, and these stimulated dendritic cells produced IL-8 and IL-12 in dose-dependent manner. These facts indicated that dendritic cells maturated by the stimulation of S. mutans. Maturation of dendritic cells was also induced by the other bacteria, i.e., S. sobrinus, S. sanguis, S. mitis, Actinomyces viscosus, Lactobacillus casei ; indicating maturation of dendritic cells occurred regardless of species of stimulating bacteria. When dendritic cells were co-cultured with serum-treated S. mutans, they showed higher expression of CD86 and CCR7, a chemokine receptor, and the production of IL-8 and IL-12 ; indicating their maturation was enhanced. On the other hand, dendritic cells co-cultured with saliva-treated S. mutans showed lower expression of CD86 and production of IL-12, which indicated the inhibition of dendritic cell maturation. In conclusion, the bacteria in carious lesion could induce maturation of pulp dendritic cells dose-dependently, and serum component could enhance the maturation of dendritic cells while saliva component would inhibit the maturation of them.

公開日:2010年1月24日で登録したコンテンツは、国立情報学研究所において電子化したものです。