Contribution of the Collagen-Binding Proteins of Streptococcus mutans to Bacterial Colonization of Inflamed Dental Pulp
Contribution of the Collagen-Binding Proteins of Streptococcus mutans to Bacterial Colonization of Inflamed Dental Pulp
复制标题
变形链球菌胶原结合蛋白对发炎牙髓细菌定殖的贡献
作者：
R. Nomura;Y. Ogaya;K. Nakano
变形链球菌是引起龋病的主要病原菌。胶原结合蛋白(CBPS)(约120 kDa)，又称CNM和CBM，是变形链球菌与胶原组织黏附相关的重要细胞表面抗原。此外，CBP阳性的变形链球菌与各种涉及菌血症的系统性疾病有关，如感染性心内膜炎。牙髓感染被认为是菌血症的一个重要原因，但对牙髓组织中是否存在变形链球菌知之甚少。本研究以CBPS为重点，对变形链球菌在牙髓组织中的分布和毒力进行了研究。利用人牙髓成纤维细胞(HDPF)分析了不同变形链球菌的黏附和侵袭特性。CBP阳性菌株对HDPF的粘附率显著高于CBP缺陷同基因突变菌株(P<；0.001)。此外，CBP阳性菌株诱导HDPF增殖，这可能是增生性牙髓炎发生的机制之一。用聚合酶链式反应分析从感染根管标本中分离的变形链球菌的分布。我们发现，大约50%的根管标本对变形链球菌呈阳性。这些菌株中约有20%是CNM阳性，而没有分离到CBM阳性菌株。从标本中分离出的CNM阳性菌株对HDPFs有粘附性。我们的结果表明CBP阳性的变形链球菌在牙髓中有很高的定植能力。这可能是各种系统性疾病的一个可能的毒力因素。
Streptococcus mutans is a major pathogen of dental caries. Collagen-binding proteins (CBPs) (approximately 120 kDa), termed Cnm and Cbm, are regarded as important cell surface antigens related to the adherence of S. mutans to collagenous tissue. Furthermore, CBP-positive S. mutans strains are associated with various systemic diseases involving bacteremia, such as infective endocarditis. Endodontic infection is considered to be an important cause of bacteremia, but little is known regarding the presence of S. mutans in dental pulp tissue. In the present study, the distribution and virulence of S. mutans in dental pulp tissues were investigated by focusing on CBPs. Adhesion and invasion properties of various S. mutans strains were analyzed using human dental pulp fibroblasts (HDPFs). CBP-positive strains had a significantly higher rate of adhesion to HDPFs compared with CBP-defective isogenic mutant strains (P<0.001). In addition, CBP-positive strains induced HDPF proliferation, which is a possible mechanism related to development of hyperplastic pulpitis. The distribution of S. mutans strains isolated from infected root canal specimens was then analyzed by PCR. We found that approximately 50% of the root canal specimens were positive for S. mutans. Approximately 20% of these strains were Cnm-positive, while no Cbm-positive strains were isolated. The Cnm-positive strains isolated from the specimens showed adhesion to HDPFs. Our results suggest that CBP-positive S. mutans strains exhibit high colonization in dental pulp. This could be a possible virulence factor for various systemic diseases.