Macrophages play a crucial role in inflammatory-mediated bone loss. Orthodontic tooth movement (OTM) is associated with inflammatory bone remodeling. However, whether and how macrophages contribute to mechanical force-induced OTM remains unknown. In this study, we hypothesized that polarization of M1-like macrophages may contribute to the OTM. Orthodontic nickel-titanium springs were applied to the upper first molars of rats or mice to induce OTM. The distance of OTM gradually increased after mechanical force was applied to the rats for 5 and 10 d. M1-like macrophage polarization and expression of M1 cytokine tumor necrosis factor (TNF)-α also increased after force application. More importantly, monocyte/macrophage depletion in mice by injection of clodronate liposomes decreased the distance of OTM and the number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts and CD68(+) macrophages, accompanied by reduced expressions of M1 markers TNF-α and inducible nitric oxide synthase (iNOS), whereas systemic transfusion of M1 macrophages in mice increased them. Further experiments showed that injection of recombinant TNF-α increased the distance of OTM and the number of TRAP-positive osteoclasts and CD68(+) macrophages, as well as upregulated the expression of TNF-α and iNOS. Blockage of TNF-α by etanercept injection reduced the distance of OTM and the number of TRAP-positive osteoclasts and CD68(+) macrophages, as well as decreased the levels of TNF-α and iNOS. These data suggest that M1-like macrophage polarization promotes alveolar bone resorption and consequent OTM after mechanical force application.

Oral squamous cell carcinoma (OSCC) is the most frequent oral cancer in the world, accounting for more than 90% of all oral cancer diagnosis. Circular RNAs (circRNAs) are large types of non-coding RNAs, demonstrating a great capacity of regulating the expression of genes. However, most of the functions of circRNAs are still unknown. Recent research revealed that circRNAs could serve as a miRNA-sponge, consequently regulating the expression of target genes indirectly, including oncogenes. In this study, we built an apoptotic model with TNF-α, and then we confirmed a circRNA associated with the apoptosis of OSCC cells, circDOCK1 by comparing the expression profile of circRNAs in an apoptotic model with that in untreated OSCC cells. We ascertained the presence of circDOCK1 with qRT-PCR and circRNA sequencing. The knockdown of the expression of circDOCK1 led to the increase of apoptosis. Utilizing multiple bioinformatics methods, we predicted the interactions among circRNAs, miRNAs and genes, and built the circDOCK1/miR-196a-5p/BIRC3 axis. Both the silencing of circDOCK1 with small interfering RNA and the upregulation of the expression of miR-196a-5p with mimics led OSCC cells to increase apoptosis and decrease BIRC3 formation. We further confirmed this outcome by comparing the expression of circDOCK1, miR-196a-5p and BIRC3 in oral squamous carcinoma tissue with those in para-carcinoma tissue, and examining the expression profile of circRNAs in oral squamous carcinoma tissue and para-carcinoma tissue with microarray. Our results demonstrated that circDOCK1 regulated BIRC3 expression by functioning as a competing endogenous RNA (ceRNA) and participated in the process of OSCC apoptosis. Thus, we propose that circDOCK1 could represent a novel potential biomarker and therapeutic target of OSCC.

RNA-based therapy is a promising and potential strategy for disease treatment by introducing exogenous nucleic acids such as messenger RNA (mRNA), small interfering RNA (siRNA), microRNA (miRNA) or antisense oligonucleotides (ASO) to modulate gene expression in specific cells. It is exciting that mRNA encoding the spike protein of COVID-19 (coronavirus disease 2019) delivered by lipid nanoparticles (LNPs) exhibits the efficient protection of lungs infection against the virus. In this review, we introduce the biological barriers to RNA delivery in vivo and discuss recent advances in non-viral delivery systems, such as lipid-based nanoparticles, polymeric nanoparticles, N -acetylgalactosamine (GalNAc)-siRNA conjugate, and biomimetic nanovectors, which can protect RNAs against degradation by ribonucleases, accumulate in specific tissue, facilitate cell internalization, and allow for the controlled release of the encapsulated therapeutics.

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Hydrogen sulfide (HS), a gasotransmitter, has been recently linked to mesenchymal stem cell (MSC) function and bone homeostasis. Periodontal ligament stem cells (PDLSCs) are the main MSCs in PDL, which respond to mechanical force to induce physiological activities during orthodontic tooth movement (OTM). However, it is unknown whether mechanical force might induce endogenous HS production by PDLSCs to regulate alveolar bone homeostasis. Here, we used a mouse OTM model to demonstrate that orthodontic force-induced endogenous HS production in PDL tissue was associated with macrophage accumulation and osteoclastic activity in alveolar bone. Then, we showed that mechanical force application induced cystathionine β-synthase (CBS) expression and endogenous HS production by PDLSCs. Moreover, blocking endogenous HS or systemically increasing HS levels could decrease or enhance force-induced osteoclastic activities to control tooth movement. We further revealed how force-induced HS production by PDLSCs contributed to the secretion of monocyte chemoattractant protein-1 (MCP-1) and the expression of receptor activator of nuclear factor-κB ligand/osteoprotegerin (RANKL/OPG) system by PDLSCs. The secretion and expression of these factors controlled macrophage migration and osteoclast differentiation. This study demonstrated that PDLSCs produced HS to respond to and transduce force signals. Force-induced gasotransmitter HS production in PDLSCs therefore regulated osteoclastic activities in alveolar bone and controlled the OTM process through the MCP-1 secretion and RANKL/OPG system.

In this study, a novel liquid self-emulsifying drug delivery system (SEDDS) containing curcumin was formulated and further developed into a solid form by a spray drying method using Aerosil 200 as the solid carrier. The optimum liquid SEDDS consisted of Lauroglycol Fcc, Labrasol and Transcutol HP as the oil phase, the surfactant and the co-surfactant at a weight ratio of 15.0 : 70.8 : 14.2 (w/w/w), respectively. There was no difference in droplet size between the emulsions obtained from the liquid and solid forms of SEDDS. Solid state characterization of the solid SEDDS was performed by scanning electron micrograph (SEM), differential scanning calorimetry (DSC), and X-ray powder diffraction (XRPD). The drug formulated in the solid SEDDS was quickly and completely dissolved within 5 min, both in 0.1 N HCl and phosphate buffer pH 6.8 dissolution media, whereas crude curcumin powder was significantly less dissoluble. The solid SEDDS formulation was stable for at least 3 months at 40°C with 75% relative humidity. After oral administration to rats, curcumin in the solid SEDDS resulted in significant improvement in in vivo absorption compared with that of curcumin powder. As the dose of curcumin formulated in solid SEDDS increased from 25 to 100 mg/kg, the C max and area under the drug concentration time curve (AUC) of curcumin were increased by 4.6 and 7.6 times, respectively. However, the over-proportional increase in the AUC in the higher dose group might be due to underestimation of AUC in the lower dose group. In conclusion, this solid SEDDS is a promising solid dosage form for poorly water-soluble curcumin.

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