2023, Vol. 27 ›› Issue (8): 1187-1192

Expression of forkhead box protein 3 in refractory periapical periodontitis in rats with Enterococcus faecalis infection

Li Mengfei1, Zhang Hong2, Zhao Shaojian1, Yin Guanghao1, Wang Qibao2   

Abstract: BACKGROUND: Refractory periapical periodontitis, with Enterococcus faecalis as a dominant bacterium, is a disease that continues with persistent inflammation and bone resorption after repeated and multiple root canal treatments. Multiple experiments have shown that forkhead box protein 3 (Foxp3) is involved in various inflammatory diseases by influencing the body’s autoimmune response.
OBJECTIVE: To observe the expression of Foxp3 in refractory periapical periodontitis in Enterococcus faecalis-infected rats.
METHODS: Thirty-three Sprague-Dawley rats at the age of 6 weeks were selected as experimental objects, 32 of which were randomly selected and divided into control and experimental groups. These 32 rats were submitted to open pulp in the central fossa of bilateral mandibular first molars under painless conditions. PBS pellets and Enterococcus faecalis suspension pellets were placed into the pulp in the control and experimental groups, respectively, followed by light curing after placing flowing resin in the bilateral inner medullary cavities. At 1, 2, 3, 4 weeks after regular water and food feeding in room temperature, four rats from each group were randomly selected for euthanasia. Rats aged 0 week without dental pulp opening were used as blank controls. Hematoxylin-eosin staining was to observe the inflammatory histopathological changes in the experimental periapical sites of rats. RT-PCR and immunohistochemical detection were used to detect the expression of Foxp3 in the periapical tissue.
RESULTS AND CONCLUSION: Hematoxylin-eosin staining results showed that: the animal models of periapical periodontitis were successfully established in the control and experimental groups and obvious inflammatory cell infiltration was seen in the periapical tissue. The results of RT-PCR showed that the mRNA expression level of Foxp3 in the periapical tissue in the control group rose in a stepwise manner from 1 to 4 weeks, while the mRNA expression level of Foxp3 in the periapical tissue in the experimental group decreased after peaking at 3 weeks (P < 0.05). Immunohistochemical results showed that the Foxp3-positive cell expression in the control group increased with time, while that in the experimental group decreased at the 4th week after the expression peaked at the 3rd week, which was consistent with the results of RT-PCR (P < 0.05). To conclude, Foxp3 is involved in the progression of chronic and refractory periapical periodontitis. In the chronic phase of inflammation, the expression of Foxp3 is significantly decreased in refractory periapical periodontitis, suggesting that it may have some relationship with Enterococcus faecalis.
Key words: chronic periapical periodontitis, refractory periapical periodontitis, Enterococcus faecalis, FOXP3, rat