RESUMO
Objective: To study the preventive effect of Lactobacillus helveticus (L. helveticus) on periodontitis induced by Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) in rats. Methods: Eighteen 8-week-old female rats were randomly divided into three groups: Sham group, Trehalose group, and L. helveticus SBT2171 (LH2171) group. We measured the distance of the cementoenamel junction-alveolar bone crest (CEJ-ABC) to evaluate alveolar bone resorption. Hematoxylin-eosin staining was used to observe the histopathological changes of rat hemimaxillary tissues. We detected the expression of ß-defensins, tumor necrosis factor-α (TNF-α), interleukin- (IL-) 1ß, and IL-6 and the number of A. actinomycetemcomitans in rat gingival tissues by quantitative reverse transcriptase polymerase chain reaction. The levels of IL-1ß, IL-6, and TNF-α in rat gingival tissues were also measured by enzyme-linked immunosorbent assay. Results: Compared with the Trehalose group, the distance of CEJ-ABC was prominently reduced and alveolar bone resorption was notably improved in the LH2171 group. And the infiltration of inflammatory cells in the hemimaxillary tissue decreased obviously, periodontal fibers were arranged neatly, connective tissue small blood vessels proliferated, and the number of A. actinomycetemcomitans reduced significantly in the LH2171 group. In addition, the mRNA expression and release of inflammatory factors in the gingival tissues in the LH2171 group were notably lower than those in the Trehalose group. On the 21st and 36th day, the expression of ß-defensins in the gingival tissue of the LH2171 group increased significantly. Conclusion: L. helveticus improves alveolar bone resorption and increases the expression of ß-defensins thereby inhibiting the number of A. actinomycetemcomitans and thus prevents periodontitis.