Follicular dendritic cell-secreted protein is decreased in experimental periodontitis concurrently with the increase of interleukin-17 expression and the Rankl/ Opg mRNA ratio.

Background and Objective T-helper type 17 ( Th17) cells produce interleukin-17 ( IL-17) and help to protect against inflammation and infection in periodontal disease. Furthermore, while follicular dendritic cell-secreted protein ( FDC- SP) may be involved in the inflammation of periodontal tissue, the biological role of FDP- SP in periodontal disease is still unknown. The purpose of the present study was to clarify the expression of IL-17 and FDC- SP in experimental periodontitis in rats. Material and Methods Seven-week-old male Wistar rats were divided into baseline control, sham and test groups. Experimental periodontitis was induced by placing a ligature in the mesiopalatal area, and untreated rats served as a baseline control group. Morphological changes in alveolar bone were investigated 7, 14 and 28 d after treatment. Expression of the Rankl, osteoprotegerin ( Opg) and Il17 genes was analyzed 5 and 7 d after the induction of experimental periodontitis. Results Alveolar bone resorption progressed in the test group for 7 d, but not thereafter. At 5 d after the induction of periodontitis, the Rankl/ Opg mRNA ratio and the expression of IL-17 in the test group were significantly increased compared with the respective values in the baseline control group; however, there were no significant differences between the test and control groups at 7 d. The expression of FDC- SP was significantly decreased in the test group compared with the baseline control group at 5 and 7 d after the induction of periodontitis, and this value had returned to normal levels at 14 and 28 d. Conclusion These results suggest that both IL-17 and FDC- SP could be involved in the inflammatory response, and FDC- SP in the junctional epithelium might play an important role in the Th17 cell-related immune response. [ABSTRACT FROM AUTHOR]