Caracterização das alterações teciduais em dois modelos de indução de doença periodontal experimental em camundongos

Periodontitis is an infectious disease characterized by a chronic inflammatory process of periodontal mediated and modulated by the host. This disease results in the destruction of conective tissue and supporting tissues of the teeth. In order to evaluate both the pathogenesis of periodontal disease and the various treatment modalities, different animal models of experimental periodontitis have been proposed and used. The benefit of using these models results in the fact that they allow an evaluation of a longitudinal disease with similar characteristics of start and progression in several animals. The aim of this study was to characterize and evaluate tissue changes caused by two models of experimental periodontal disease in mice: ligature and oral gavage. For this, 48 C57/BL6 mice wild type (WT) mice were divided into 4 groups: Group C - Negative Control, Group L - Ligature (induction of periodontal disease by ligatures), Group G-Pg - Porphyromonas gingivalis Gavage (induction by Pg inoculations) and Group G-PgFn - Porphyromonas gingivalis + Fusobacterium nucleatum Gavage. The animals were sacrificed at two experimental periods: 45 and 60 days after the induction onset of periodontal disease. Significant bone loss only in the group L by means of stereometric analysis, computed microtomography (μCT) and immunohistochemistry was observed. The bacterial colonization in groups of gavage was confirmed by PCR in real time. We conclude that the model of ligature was effective in inducing periodontal disease parameters used in contrast to oral gavage.A periodontite é uma doença infecciosa caracterizada por um processo inflamatório crônico do periodonto mediada e modulada pelo hospedeiro. Esta patologia resulta na destruição do tecido conjuntivo gengival e dos tecidos de suporte dos dentes. De modo a avaliar tanto a patogênese da doença periodontal quanto as diversas modalidades de tratamento, diferentes modelos animais de periodontite experimental têm sido propostos e utilizados. O benefício do uso destes modelos resulta no fato de que eles permitem uma avaliação da doença de uma forma longitudinal, com características de início e progressão semelhantes em diversos animais. O objetivo deste estudo foi caracterizar e avaliar comparativamente as alterações teciduais provocadas por dois modelos de doença periodontal experimental em camundongos: ligadura e gavagem oral. Para isto, foram utilizados 48 camundongos C57/BL6 wild type (WT), divididos em 4 grupos: Grupo C - Controle negativo, Grupo L – Ligadura (indução da doença periodontal por meio de ligaduras), Grupo G-Pg – Gavagem de Porphyromonas gingivalis (indução por meio de inoculações de Pg) e Grupo G-PgFn – Gavagem de Porphyromonas gingivalis + Fusobacterium nucleatum. Os animais foram sacrificados em dois períodos experimentais: 45 e 60 dias após o início da indução da doença periodontal. Observou-se perda óssea alveolar significativa apenas no grupo L, por meio de análise estereométrica, microtomografia computadorizada(μCT) e imunohistoquímica. A colonização bacteriana nos grupos de gavagem foi confirmada por meio de PCR em tempo real. Concluímos que o modelo de ligadura foi efetivo em induzir a doença periodontal nos parâmetros utilizados ao contrário da gavagem oral

Long-term evaluation of oral gavage with periodontopathogens or ligature induction of experimental periodontal disease in mice

To evaluate in long-term periods the destruction of periodontal tissues and bacterial colonization induced by oral gavage with periodontopathogens or ligature experimental periodontal disease models. Forty-eight C57BL/6 J mice were divided into four groups: group C: negative control; group L: ligature; group G-Pg: oral gavage with Porphyromonas gingivalis; and group G-PgFn: oral gavage with Porphyromonas gingivalis associated with Fusobacterium nucleatum. Mice were infected by oral gavage five times in 2-day intervals. After 45 and 60 days, animals were sacrificed and the immune-inflammatory response in the periodontal tissue was assessed by stereometric analysis. The alveolar bone loss was evaluated by live microcomputed tomography and histometric analysis. qPCR was used to confirm the bacterial colonization in all the groups. Data were analyzed using the Kruskal-Wallis, Wilcoxon, and ANOVA tests, at 5 % of significance level. Ligature model induced inflammation and bone resorption characterized by increased number of inflammatory cells and decreased number of fibroblasts, followed by advanced alveolar bone loss at 45 and 60 days (p < 0.05). Bacterial colonization in groups G-Pg and G-PgFn was confirmed by qPCR but inflammation and bone resorption were not observed (p < 0.05). The ligature model but not the oral gavage models were effective to induce inflammation and bone loss in long-term periods. Pg colonization was observed in all models of experimental periodontal disease induction, independent of tissue alterations. These mice models of periodontitis validates, compliments, and enhances published PD models that utilize ligature or oral gavage and supports the importance of a successful colonization of a susceptible host, a bacterial invasion into vulnerable tissue, and host-bacterial interactions that lead to tissue destruction. The ligature model was an effective approach to induce inflammation and bone loss similar to human periodontitis, but the oral gavage models were not efficient in inducing periodontal inflammation and tissue destruction in the conditions studied. Ligature models can provide a basis for future interventional studies that contribute to the understanding of the disease pathogenesis and the complex host response to microbial challenge.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP