Affiliations: [a] Hospital of Stomatology, Zunyi Medical University, Zunyi, Guizhou, China
| [b] Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, Jiangsu, China
Correspondence:
[*]
Correspondence to: Song Ge, Hospital of Stomatology, Zunyi Medical University, Zunyi, Guizhou 563003, China. Tel.: +86 851 28635717; E-mail: gesong007b@163.com and Fuhua Yan, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, Jiangsu 210008, China. Tel.: +86 25 8362 0253; E-mail: yanfh@nju.edu.cn.
Note: [1
] These authors contributed equally to this work.
Abstract: Background:Although periodontitis is reportedly associated with increased cognitive decline in Alzheimer’s disease, the mechanisms underlying this process remain unknown. Porphyromonas gingivalis lipopolysaccharide (P.g-LPS) is an endotoxin associated with periodontal disease. Objective: We investigated the effect of periodontitis on learning capacity and memory of amyloid-β protein precursor (AβPP)/presenilin (PS1) transgenic mice along with the mechanisms underlying these effects. Methods: Mice were randomly assigned to three groups, namely AβPP/PS1 (control), P.g-LPS Injection, and P.g-LPS Injection + Ligation. Mice from the P.g-LPS Injection group were injected with P.g-LPS in the periodontal tissue three times per week for 8 weeks, while mice from the P.g-LPS Injection + Ligation group were injected with P.g-LPS and subjected to ligation of the gingival sulcus of the maxillary second molar. Results: Expression of gingival proinflammatory cytokines as well as alveolar bone resorption in P.g-LPS-injected and ligatured mice was increased compared to that in control mice. Mice in the P.g-LPS Injection + Ligation group exhibited cognitive impairment and a significant reduction in the number of neurons. Glial cell activation in the experimental groups with significantly increased amyloid-β (Aβ) levels was more pronounced relative to the control group. Induction of periodontitis was concurrent with an increase in cyclooxygenase-2, inducible nitric oxide synthase, AβPP, and beta-secretase 1 expression and a decrease in A disintegrin and metalloproteinase domain-containing protein 10 expression. Conclusion: These findings indicated that periodontitis exacerbated learning and memory impairment in AβPP/PS1 mice and augmented Aβ and neuroinflammatory responses. Our study provides a theoretical basis for risk prediction and early intervention of Alzheimer’s disease and periodontitis.
