Department of Restorative Dentistry, Endodontic Division, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil; Department of Oral Biology, University of Florida, Gainesville, Florida.
Department of Oral Biology, University of Florida, Gainesville, Florida.
J Endod. 2020 Dec;46(12):1876-1883. doi: 10.1016/j.joen.2020.09.002. Epub 2020 Sep 11.
Streptococcus mutans plays an important role in caries etiology and eventually in systemic infections. However, it is often found in infected root canals, but the pathophysiological characteristics of strains residing in this site are largely unknown. Here, we characterized strains of S. mutans isolated from root canals of primary (PI) and secondary/persistent (SI) endodontic infections in relation to serotype and genotype; presence of genes coding for collagen binding proteins (CBPs); collagen binding activity and biofilm formation capacity; ability to withstand environmental stresses; systemic virulence in Galleria mellonella; and invasion of human coronary artery endothelial cells and human dental pupal fibroblasts. Samples from 10 patients with PI and 10 patients with SI were collected, and a total of 14 S. mutans isolates, belonging to 3 genotypes, were obtained. Of these, 13 were serotype c, and 1 was serotype k. When compared with the reference strains, the clinical isolates were hypersensitive to hydrogen peroxide. Remarkably, all 14 strains harbored and expressed the CBP-encoding gene cbm, showing increased binding to collagen, enhanced systemic virulence in G. mellonella, and ability to invade human coronary artery endothelial cells and human dental pupal fibroblasts when compared with CBP-negative strains. Whole genome sequence analysis of PI and SI isolates revealed that these strains are phylogenetically related but genetically distinct from each other. Our findings highlight the importance of CBPs in facilitating colonization and persistence of S. mutans in collagenous substrates such as root canals and their potential role in the pathogenesis of endodontic infections.
变形链球菌在龋病病因学中起重要作用，并最终导致全身感染。然而，它常存在于感染的根管中，但驻留在该部位的菌株的病理生理特征在很大程度上尚不清楚。在这里，我们根据血清型和基因型、编码胶原结合蛋白（CBPs）的基因存在情况、胶原结合活性和生物膜形成能力、对环境应激的耐受能力、在金龟子幼虫中的系统毒力以及对人冠状动脉内皮细胞和人牙髓成纤维细胞的侵袭能力，对来源于初发性（PI）和继发性/持续性（SI）牙髓感染根管的变形链球菌菌株进行了特征描述。收集了 10 例 PI 和 10 例 SI 患者的样本，共获得了 14 株变形链球菌分离株，属于 3 种基因型。其中 13 株为血清型 c，1 株为血清型 k。与参考菌株相比，临床分离株对过氧化氢更为敏感。值得注意的是，所有 14 株菌均携带和表达 CBP 编码基因 cbm，与 CBP 阴性菌株相比，其对胶原的结合能力增强，在金龟子幼虫中的系统毒力增强，并且能够侵袭人冠状动脉内皮细胞和人牙髓成纤维细胞。PI 和 SI 分离株的全基因组序列分析表明，这些菌株在系统发育上相关，但在遗传上彼此不同。我们的研究结果强调了 CBPs 在促进变形链球菌在胶原基质如根管中的定植和持续存在中的重要性，以及它们在牙髓感染发病机制中的潜在作用。
