n-butyric acid produced by P. endodontalis reactivated latent EBV.
Aim To assess whether Epstein–Barr virus (EBV) reactivation is triggered by persistent apical periodontitis‐related microbes using in vitro and ex vivo methodologies. Methodology Surgically removed human periapical granulomas (n = 50) and healthy gingival tissues (n = 10) were analysed to determine the presence of EBV and seven persistent apical periodontitis‐related microbes. In addition, real‐time polymerase chain reaction was used to detect the mRNA expression of BZLF‐1, an immediate–early gene of EBV. Expression of latent membrane protein (LMP)‐1 and ZEBRA, an early lytic protein of EBV encoded by BZLF‐1, was also examined using triple‐colour immunofluorescence staining. n‐Butyric acid produced by the microbes was quantified, and luciferase assays were performed in association with bacterial lysates. In addition, Daudi cells were cultured with bacterial lysates, and the expression levels of BZLF‐1 mRNA and ZEBRA protein were determined. Results EBV DNA and BZLF‐1 mRNA were detected in 47 out of 50 periapical granulomas, but not in healthy gingival tissues. The EBV DNA copy number and the number of Fusobacterium nucleatum were significantly positively correlated with BZLF‐1 expression in periapical granulomas. The number of Prevotella intermedia was slightly correlated with BZLF‐1 expression; however, the other microbes were not. CD79a‐positive B cells in periapical granulomas, but not those in healthy gingival tissues, expressed both LMP‐1 and ZEBRA. n‐Butyric acid production was the highest in F. nucleatum and the lowest in P. intermedia. Enterococcus faecalis, Candida albicans and the other tested microbes did not produce n‐butyric acid. An F. nucleatum lysate exhibited significantly increased BZLF‐1‐luciferase activity in the same manner of commercial butyric acid, whereas P. intermedia did not. F. nucleatum also induced the expression of BZLF‐1 mRNA and ZEBRA protein by Daudi cells, indicating that EBV reactivation was induced. Conclusion Among the persistent apical periodontitis‐related bacteria that were tested, F. nucleatum most strongly reactivated latent EBV, whereas E. faecalis and C. albicans as well as the other microbes did not.
These findings suggest that SIRT1 may stimulate angiogenesis in periapical granulomas by triggering the proliferation of endothelial cells and inducing VEGF and VE-cadherin expression.
Background/Aim: S100A4 expression is associated with the pathology of chronic inflammatory diseases. In this study, we investigated the role of S100A4 and four inflammatory mediators IĸB, in human periapical granulomas (PGs). Materials and Methods: S100A4 expression in PGs obtained by apicoectomy was examined by immunohistochemistry. Further, the expression of S100A4 and four inflammatory mediators was compared between PGs and healthy gingival tissues (HGTs) using real-time PCR. Results: In the PGs, S100A4 was found to be expressed in endothelial cells and fibroblasts. Furthermore, real-time PCR revealed that the expression of S100A4 and IL-1β in PGs was significantly higher than that in HGTs. Although a correlation between the expression of S100A4 and IĸB or IL-10 was not detected, a positive correlation between the expression of S100A4 and IL-1β or TNF-α was observed. Conclusion: The expression of S100A4 correlates with the pathogenesis of PGs.
It has been reported that Forkhead box transcription factor class O3a (Foxo3a) is expressed in rheumatoid arthritis, a chronic inflammatory condition accompanied by bone resorption, and plays a role in its pathology. However, it has remained unclear whether Foxo3a is involved in the pathogenesis of periapical granulomas. The present study was performed to compare the expression of Foxo3a in periapical granulomas and healthy gingival tissues. Samples were obtained surgically from patients, and subjected to hematoxylin-eosin staining for histopathologic diagnosis. Two-color immunofluorescence staining was also performed using antibodies against Foxo3a and markers for three types of inflammatory cells: neutrophils, T lymphocytes, and B lymphocytes. This revealed that Foxo3a was expressed in all three cell types in periapical granulomas but not in healthy gingival tissues. Foxo3a was expressed in 82.1%, 78.3%, and 77.5% of neutrophils, T lymphocytes, and B lymphocytes, respectively, and statistical analysis using the Kruskal-Wallis test followed by the Steel-Dwass test showed no significant difference of Foxo3a expression among the three cell types. Our results suggest that Foxo3a transcription factors may be involved in the pathogenesis of periapical granulomas.
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