Lactobacillus helveticus Prevents Periodontitis Induced by Aggregatibacter actinomycetemcomitans in Rats by Regulating β-Defensins

Abstract

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 β-defensins, tumor necrosis factor-α (TNF-α), interleukin- (IL-) 1β, and IL-6 and the number of A. actinomycetemcomitans in rat gingival tissues by quantitative reverse transcriptase polymerase chain reaction. The levels of IL-1β, 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 β-defensins in the gingival tissue of the LH2171 group increased significantly.

Conclusion: L. helveticus improves alveolar bone resorption and increases the expression of β-defensins thereby inhibiting the number of A. actinomycetemcomitans and thus prevents periodontitis.

Figure 1

The distance from the cement-enamel junction (CEJ) to the alveolar bone crest (ABC) in each group. Results are expressed as the means ± SD. ^∗P < 0.05 and ^∗∗P < 0.01vs. the Sham group. ^#P < 0.05vs. the Trehalose group.

Figure 2

Histopathological changes of hemimaxillary tissues in rats of each group observed by H&E staining. Magnifications, 100x and 400x. Scale bar = 200 μm. GE: gingival epithelium; PDL: periodontal ligament fibers; ALB: alveolar bone.

Figure 3

The expression of A. actinomycetemcomitans in the gingival tissue of rats in each group was detected by qRT-PCR. Results are expressed as the means ± SD of triplicate assays from three independent experiments. ^∗∗P < 0.01vs. the Sham group. ^##P < 0.01vs. the Trehalose group.

Figure 4

Expression and release of inflammatory factors in rats. (a) qRT-PCR was used to detect the expression level of IL-1β in the gingival tissues of rats on days 36 and 65 in each group; (b) qRT-PCR was used to detect the expression level of IL-6 in the gingival tissues of rats on days 36 and 65 in each group; (c) qRT-PCR was used to detect the expression level of TNF-α in the gingival tissues of rats on days 36 and 65 in each group; (d) ELISA was used to detect the release of IL-1β, IL-6, and TNF-α in the gingival tissues of rats in each group on day 65. Results are expressed as the means ± SD of triplicate assays from three independent experiments. ^∗∗P < 0.01vs. the Sham group. ^##P < 0.01vs. the Trehalose group.

Figure 5

The expression of β-defensins in the gingival tissue of rats in each group was detected by qRT-PCR. Results were expressed as the means ± SD of triplicate assays from three independent experiments. ^∗∗P < 0.01vs. the Sham group. ^##P < 0.01vs. the Trehalose group.