Effects of a flavonoid-rich extract of Citrus bergamia on an experimental model of periodontitis in rats

Objective: aim of the study was to investigate the effects of a flavonoid-rich fraction of Bergamot juice (BJe) in rats affected by LPS-induced periodontitis. Main methods: fourteen days after LPS injection, radiographic analyses of periodontal sites were performed and gingivomucosal tissues surrounding the mandibular first molar were harvested for histological, immunohistochemical and molecular analyses. Results: LPS significantly promoted edema formation, tissue damage and increased neutrophil infiltration. NF-κB translocation as well as TNF-α and IL-1β expression were found to be up-regulated. Additionally, the increased myeloperoxidase activity was associated with up-regulation of adhesion molecules. Immunohistochemical analysis for nitrotyrosine and poly ADP-ribose displayed an intense staining in the gingivomucosal tissue. Oral administration of BJe for 14 consecutive days was found to reduce tissue injury and lower several markers of gingival inflammation including nuclear NF-κB translocation, cytokines expression, myeloperoxidase activity and the expression of some adhesion molecules such as ICAM and P-selectin. Moreover, both nitrosative stress and PARP positive staining were reduced after BJe treatment, while Bax expression was downregulated and Bcl-2 expression was upregulated. Conclusion: BJe improves LPS-induced periodontitis in rats by reducing the typical markers of inflammation, thus suggesting its potential in the treatment of periodontal diseases.