Roles of Salivary Components in Streptococcus mutans Colonization in a New Animal Model Using NOD/SCID.e2f1−/− Mice

Streptococcus mutans plays an important role in biofilm formation on the tooth surface and is the primary causative agent of dental caries. The binding of S. mutans to the salivary pellicle is of considerable etiologic significance and is important in biofilm development. Recently, we produced NOD/SCID.e2f1−/− mice that show hyposalivation, lower salivary antibody, and an extended life span compared to the parent strain: NOD.e2f1−/−. In this study we used NOD/SCID.e2f1−/− 4 or 6 mice to determine the roles of several salivary components in S. mutans colonization in vivo. S. mutans colonization in NOD/SCID.e2f1−/− mice was significantly increased when mice were pre-treated with human saliva or commercial salivary components. Interestingly, pre-treatment with secretory IgA (sIgA) at physiological concentrations promoted significant colonization of S. mutans compared with sIgA at higher concentrations, or with human saliva or other components. Our data suggest the principal effects of specific sIgA on S. mutans occur during S. mutans colonization, where the appropriate concentration of specific sIgA may serve as an anti-microbial agent, agglutinin, or an adherence receptor to surface antigens. Further, specific sIgA supported biofilm formation when the mice were supplied 1% sucrose water and a non-sucrose diet. The data suggests that there are multiple effects exerted by sIgA in S. mutans colonization, with synergistic effects evident under the condition of sIgA and limited nutrients on colonization in NOD/SCID.e2f1−/− mice. This is a new animal model that can be used to assess prevention methods for dental biofilm-dependent diseases such as dental caries

Evaluation of salivary flow in patients during head and neck radiotherapy Análise do fluxo salivar em pacientes durante a radioterapia em cabeça e pescoço

Radiotherapy is frequently employed for the treatment of head and neck squamous cell carcinoma. Among the side effects, xerostomia is one of the most important. With the objective of evaluating the role of radiotherapy in salivary flow, we performed three salivary sample collections: at the beginning of, during, and immediately after radiotherapy. The results showed that the salivary flow values of the first collection were very similar to those of the control group. However, during treatment, there was a significant decrease of the salivary flow (p = 0.0008), which continued low immediately after radiotherapy (p = 0.0009). Our study showed that radiotherapy leads to an important reduction of salivary flow during and after radiotherapy.<br>A radioterapia é um tratamento comumente empregado em pacientes portadores de carcinomas espinocelulares em cabeça e pescoço. Entre os efeitos colaterais locais, a xerostomia é um dos mais importantes. Com o objetivo de avaliar o efeito da radioterapia sobre o fluxo salivar, foram feitas 3 coletas salivares: no início, em um período intermediário e posteriormente ao tratamento radioterápico. Os resultados obtidos demonstraram médias de fluxo salivar semelhantes entre a coleta inicial e o grupo controle. Com o decorrer da radioterapia, houve diminuição significativa do fluxo salivar na coleta intermediária (p = 0,0008), que se manteve após o término da radioterapia (p = 0,0009). Nosso estudo enfatiza que há redução significativa do fluxo salivar durante e após a radioterapia