Emodin is an active herbal component traditionally used in East Asian countries for treating a variety of diseases. The present study investigated the effects of emodin on specific virulence factors of Streptococcus mutans (S. mutans) in vitro and on caries development in vivo. The growth and acid production of S. mutans were significantly inhibited by emodin (0.5–2 mg/ml). Emodin also significantly suppressed the synthesis of insoluble glucans by S. mutans. Furthermore, the topical application of emodin reduced the incidence and severity of carious lesions in rats. These results suggest that the natural compound emodin may be a novel pharmacological agent for the prevention and treatment of dental caries.

Background The role of periodontal ligament stem cells (PDLSCs) and macrophage polarization in periodontal tissue regeneration and bone remodeling during orthodontic tooth movement (OTM) has been well documented. Nevertheless, the interactions between macrophages and PDLSCs in OTM remain to be investigated. Consequently, the present study was proposed to explore the effect of different polarization states of macrophages on the osteogenic differentiation of PDLSCs. Methods After M0, M1 and M2 macrophage-derived exosomes (M0-exo, M1-exo and M2-exo) treatment of primary cultured human PDLSCs, respectively, mineralized nodules were observed by Alizarin red S staining, and the expression of ALP and OCN mRNA and protein were detected by RT-qPCR and Western blotting, correspondingly. Identification of differentially expressed microRNAs (DE-miRNA) in M0-exo and M2-exo by miRNA microarray, and GO and KEGG enrichment analysis of DE-miRNA targets, and construction of protein–protein interaction networks. Results M2-exo augmented mineralized nodule formation and upregulated ALP and OCN expression in PDLSCs, while M0-exo had no significant effect. Compared to M0-exo, a total of 52 DE-miRNAs were identified in M2-exo. The expression of hsa-miR-6507-3p, hsa-miR-4731-3p, hsa-miR-4728-3p, hsa-miR-3614-5p and hsa-miR-6785-3p was significantly down-regulated, and the expression of hsa-miR-6085, hsa-miR-4800-5p, hsa-miR-4778-5p, hsa-miR-6780b-5p and hsa-miR-1227-5p was significantly up-regulated in M2-exo compared to M0-exo. GO and KEGG enrichment analysis revealed that the downstream targets of DE-miRNAs were mainly involved in the differentiation and migration of multiple cells. Conclusions In summary, we have indicated for the first time that M2-exo can promote osteogenic differentiation of human PDLSCs, and have revealed the functions and pathways involved in the DE-miRNAs of M0-exo and M2-exo and their downstream targets.