Quercetin-loaded mesoporous nano-delivery system remodels osteoimmune microenvironment to regenerate alveolar bone in periodontitis via the miR-21a-5p/PDCD4/NF-κB pathway.

BACKGROUND: Impaired osteo-/angiogenesis, excessive inflammation, and imbalance of the osteoimmune homeostasis are involved in the pathogenesis of the alveolar bone defect caused by periodontitis. Unfortunately, there is still a lack of ideal therapeutic strategies for periodontitis that can regenerate the alveolar bone while remodeling the osteoimmune microenvironment. Quercetin, as a monomeric flavonoid, has multiple pharmacological activities, such as pro-regenerative, anti-inflammatory, and immunomodulatory effects. Despite its vast spectrum of pharmacological activities, quercetin's clinical application is limited due to its poor water solubility and low bioavailability. RESULTS: In this study, we fabricated a quercetin-loaded mesoporous bioactive glass (Quercetin/MBG) nano-delivery system with the function of continuously releasing quercetin, which could better promote the bone regeneration and regulate the immune microenvironment in the alveolar bone defect with periodontitis compared to pure MBG treatment. In particular, this nano-delivery system effectively decreased injection frequency of quercetin while yielding favorable therapeutic results. In view of the above excellent therapeutic effects achieved by the sustained release of quercetin, we further investigated its therapeutic mechanisms. Our findings indicated that under the periodontitis microenvironment, the intervention of quercetin could restore the osteo-/angiogenic capacity of periodontal ligament stem cells (PDLSCs), induce immune regulation of macrophages and exert an osteoimmunomodulatory effect. Furthermore, we also found that the above osteoimmunomodulatory effects of quercetin via macrophages could be partially blocked by the overexpression of a key microRNA--miR-21a-5p, which worked through inhibiting the expression of PDCD4 and activating the NF-κB signaling pathway. CONCLUSION: In summary, our study shows that quercetin-loaded mesoporous nano-delivery system has the potential to be a therapeutic approach for reconstructing alveolar bone defects in periodontitis. Furthermore, it also offers a new perspective for treating alveolar bone defects in periodontitis by inhibiting the expression of miR-21a-5p in macrophages and thereby creating a favorable osteoimmune microenvironment.

Low-cost and highly efficient production of bacterial cellulose from sweet potato residues: Optimization, characterization, and application.

Bacterial cellulose (BC) is an emerging biological material with unique properties and structure, which has attracted more and more attention. In this study, Gluconacetobacter xylinus was used to convert sweet potato residues (SPR) hydrolysate to BC. SPR was directly used without pretreatment, and almost no inhibitors were generated, which was beneficial to subsequent glucan conversion and SPR-BC synthesis. SPR-BC production was 11.35 g/L under the optimized condition. The comprehensive structural characterization and mechanical analysis demonstrated that the crystallinity, maximum thermal degradation temperature, and tensile strength of SPR-BC were 87.39%, 263 °C, and 6.87 MPa, respectively, which were superior to those of BC produced with the synthetic medium. SPR-BC was added to rice straw pulp to enhance the bonding force between fibers and the indices of tensile, burst, and tear of rice straw paper. The indices were increased by 83.18%, 301.27%, and 169.58%, respectively. This research not only expanded the carbon source of BC synthesis, reduced BC production cost, but also improved the quality of rice straw paper.