Potential roles of miR-335-5p on pathogenesis of experimental periodontitis

Background and objective Periodontitis is a prevalent oral disease responsible for tooth loss. MicroRNAs have been proven crucial in bone disorders over the past decades. Promotive effect on osteogenic activities by microRNA-335-5p (miR-335-5p) has been well demonstrated, but its role involved in the pathogenesis of periodontitis remains elusive. In this study, we established experimental periodontitis (EP) on transgenic mice overexpressing miR-335-5p (335-Tg) to investigate the novel effects of miR-335-5p on periodontal inflammation and bone loss. Methods Experimental periodontitis was established via ligation. The expression of inflammatory and osteoclastic genes was examined by quantitative real-time PCR (qPCR). Morphology of alveolar bone was analyzed by microcomputed tomography (μCT). Hematoxylin and eosin (H&E), tartrate-resistant acid phosphatase (TRAP), and Toll-like receptor 4 (TLR4) immunohistochemistry (IHC) staining were conducted for histological analysis. Results The expression of miR-335-5p decreased significantly in the periodontal tissues of EP. Compared to the WT-EP group, μCT analysis showed less bone loss in the 335-Tg-EP group accompanying with a decreased number of TRAP-positive osteoclasts. H&E and IHC staining exhibited attenuated inflammation and TLR4 expression in the 335-Tg-EP group. Furthermore, reduced expressions of IL-1β, IL-6, TNF-α, and TLR4 were also detected in the 335-Tg-EP group. Overexpression of miR-335-5p in vivo weakened the periodontal bone destruction and inflammation compared with the WT-EP group. Conclusions Our data exhibit novel roles of miR-335-5p in preventing bone loss and inflammation in experimental periodontitis.