N6-methyladenosine (m6A) methyltransferase METTL3-mediated LINC00680 accelerates osteoarthritis through m6A/SIRT1 manner.

Increasing evidence suggest the biological roles of N6-methyladenosine (m6A) and long noncoding RNAs (lncRNAs) in the bone disease, especially osteoarthritis (OA). However, the interaction of m6A and lncRNA in osteoarthritis is still unclear. Here, we found that a m6A-related lncRNA LINC00680 upregulated in the OA tissue and IL-1ß-induced isolated primary chondrocytes. Functionally, in IL-1ß-induced chondrocytes, silencing of LINC00680 recovered the proliferation and repressed the extracellular matrix (ECM) degradation. Mechanistically, m6A methyltransferase METTL3 combined tithe the m6A site of LINC00680 to up-regulate its expression. Moreover, LINC00680 interacted with SIRT1 mRNA through binding at m6A site on SIRT1 mRNA 3'-UTR, thereby enhancing the stability of SIRT1 mRNA. Overall, these findings exhibited a role of LINC00680/m6A/SIRT1 mRNA complex in chondrocytes. Taken together, the present study intends to uncover the mechanism by which METTL3-mediated LINC00680 accelerates OA progression, which may provide novel insight for OA.

Effects of intra-articular D-amino acids combined with systemic vancomycin on an experimental Staphylococcus aureus-induced periprosthetic joint infection.

BACKGROUND: The D-isoforms of amino acids (D-AAs) exhibit anti-biofilm potential against a diverse range of bacterial species in vitro, while its role in vivo remains unclear. The aim of this study was to investigate the effects of a combination of D-AAs and vancomycin on a PJI rat model. METHODS: Eight-week-old male SD rats were randomized to the control group, sham group, vancomycin group, D-AAs-vancomycin group. After treatment for 6 weeks, we analysed the levels of inflammatory factors in serum, behavioural change, imaging manifestations. The anti-biofilm ability of D-AAs was detected by crystal violet staining and scanning electron microscope observation, and its ability to assist antibiotics in killing bacteria was assessed by culture of bacteria. Additionally, micro-CT and histological analysis were used to evaluate the impact of D-AAs combined with vancomycin on the bone remodelling around the prosthesis. RESULTS: The group treated with a D-AAs-vancomycin combination sustained normal weight gain and exhibited reduced the serum levels of α2M, IL-1ß, IL-6, IL-10, TNF-α and PGE2. Moreover, treated with D-AAs in combination with vancomycin improved the weight-bearing activity performance, increased the sizes and widths of distal femurs, and improved Rissing scale scoring. In particular, treatment using D-AAs enhanced the ability of vancomycin to eradicate Staphylococcus aureus, as demonstrated by the dispersion of existing biofilms and the inhibition of biofilm formation that occurred in a concentration-dependent manner. This treatment combination also resulted in a reduction in bacterial burden with in the soft tissues, bones, and implants. Furthermore, D-AAs-vancomycin combination treatment attenuated abnormal bone remodelling around the implant, as evidenced by an observed increase in BMD, BV/TV, and Tb.Th and the presence of reduced Trap+ osteoclasts and elevated osterix+ osteo-progenitors. CONCLUSIONS: Combining D-AAs with vancomycin provides an effective therapeutic strategy for the treatment of PJI by promoting biofilm dispersion to enhance antimicrobial activity.

Filamin B extensively regulates transcription and alternative splicing, and is associated with apoptosis in HeLa cells.

Post­transcriptional mechanisms are an important approach in the treatment of cancer, and may also be hijacked by tumor cells to help adapt to the local microenvironment. Filamin B (FLNB), an actin­binding protein that provides crucial scaffolds for cell motility and signaling, has also been identified as an RNA­binding protein. Recent studies demonstrated that FLNB might play an important role, not only in skeletal development, but also in regulating tumorigenesis; however, the effects of dysregulated expression of FLNB at the molecular level are not clear. In the present study, RNA­sequencing was performed to analyze changes in overall transcriptional and alternative splicing between the knocked­down FLNB and the control in HeLa cells. Decreased FLNB levels resulted in significantly lower apoptosis compared with control cells. FLNB knockdown extensively regulated the expression of genes in cell apoptosis, tumorigenesis, metastases, transmembrane transport and cartilage development. Moreover, FLNB regulated alternative splicing of a large number of genes involved in 'cell death' and the 'apoptotic process'. Some genes and alternative splicing related to skeletal development were enriched and regulated by FLNB. Reverse transcription­quantitative­PCR identified FLNB­regulated transcription and alternative splicing of genes, such as NLR family apoptosis inhibitory protein, interleukin 23 subunit α, metastasis associated lung adenocarcinoma transcript 1, phosphofurin acidic cluster sorting protein 2, bone morphogenetic protein 7, matrix metallopeptidase 13, collagen type II α 1 chain, fibroblast growth factor receptor 2 and vitamin D receptor. The present study is the first study, to the best of the authors' knowledge, to provide transcriptome­wide analysis of differential gene expression and alternative splicing upon FLNB silencing. The present results suggested that FLNB may play an important regulatory role in cervical cancer cell apoptosis via regulation of transcription and alternative splicing, which provide insight for the current understanding of the mechanisms of FLNB­mediated gene regulation.

Artesunate relieves subchondral bone osteoclast-mediated osteoarthritis pain / 中国组织工程研究

BACKGROUND: Studies have shown that osteoclasts induce aberrant in growth of sensory nerves into the subchondral bone by secreting netrin-1, resulting in a reduced pain threshold in an osteoarthritis animal model. Therefore, we assume that inhibition of osteoclasts can alleviate sensory nerve-mediated pain symptoms. OBJECTIVE: To investigate whether artesunate inhibits subchondral bone osteoclasts and reduces sensory nerve-mediated pain, providing experimental data for the treatment of osteoarthritis pain using artesunate. METHODS: C57BL/6J male mice were randomly assigned to a sham operation group, a placebo group and an artesunate group, with 10 mice per group. The mice in the sham operation group were only subjected to right knee capsulotomy with no damage to the other structures. Moreover, there was no intervention after operation. In the other two groups, the mice received an anterior cruciate ligament transection of the right knee to establish the osteoarthritis model, followed by treatment with artesunate (artesunate group, 100 mg/kg per day) or equivalent volume of 5% NaHCO3 (placebo group) via intraperitoneal injection. Fourteen days after surgery, the footprint trial was performed, and the levels of tartrate-resistant acid phosphatase 5b (TRAcP5b), cathepsin K and carboxy-terminal telopeptide of type I collagen (CTX-I) in the peripheral blood were detected using ELISA. The knee joint specimens of each group were subjected to Safranin O-Fast Green staining, histological scoring, tartrate-resistant acid phosphatase (TRAP) staining and immunohistochemical staining with netrin-1 and calcitonin gene-related peptide (CGRP). RESULTS AND CONCLUSION: The percentage of ipsilateral contact area of the right hindpaw in the footprint trial was significantly higher in the sham operation group and artesunate group than the placebo group (P 0.05). No significant differences were observed in the serum levels of TRAcP5b, cathepsin K and CTX-I between the groups (P > 0.05). Based on the Safranin O-Fast Green staining, the cartilage histology score was significantly lower in the sham operation group and the artesunate group than the placebo group (P 0.05). TRAP staining indicated that compared with the placebo group, the Trap+ osteoclasts were significantly lower in the sham operation group and the artesunate group (P 0.05). Compared with the placebo group, the netrin-1+ and CGRP+ sensory nerves in the subchondral bone were significantly decreased in the sham operation group and the artesunate group (P 0.05). Our findings from this study indicate that artesunate improves sensory nerve-mediated pain by inhibiting netrin-1 secreted by subchondral bone osteoclasts, and has therapeutic potential to alleviate osteoarthritis pain.

Artesunate alleviates interleukin­1ß­induced inflammatory response and apoptosis by inhibiting the NF­κB signaling pathway in chondrocyte­like ATDC5 cells, and delays the progression of osteoarthritis in a mouse model.

Osteoarthritis (OA) is a progressive and degenerative joint disorder that is highly prevalent worldwide and for which there is currently no effective medical therapy. Artesunate (ART), a natural compound used to treat malaria, possesses diverse biological properties, including the regulation of inflammation and apoptosis in various cells; however, its role in OA remains unclear. The aim of the present study was to investigate the effects of ART on interleukin (IL)­1ß­induced chondrocyte­like ATDC5 cells and in an OA mouse model. The results revealed that ART dose­dependently relieved the inhibitory effect of IL­1ß on cell viability. Moreover, ART significantly reduced the overexpression of matrix metalloproteinase (MMP)­3, MMP­13, a disintegrin and metalloproteinase with thrombospondin motifs­5 and cyclooxygenase­2 at both the gene and protein levels in chondrocyte­like ATDC5 cells stimulated by IL­1ß. Furthermore, ART decreased the expression of pro­apoptotic Bax, cleaved caspase­3 and cleaved caspase­7 in a dose­dependent manner, and increased the expression of the anti­apoptotic factor Bcl­2. These changes were mediated by the inhibitory effect of ART on the nuclear factor­κB signaling pathway, defined as repression of the phosphorylation of IκBα and p65, and improved redistribution of p65. Additionally, ART blocked the advancement of the calcified cartilage zone and the loss of proteoglycan, and lowered histological scoring of OA in a mouse model. Taken together, these results indicate that ART may be of value as a therapeutic agent for OA.

Artesunate, an Anti-Malaria Agent, Attenuates Experimental Osteoarthritis by Inhibiting Bone Resorption and CD31hiEmcnhi Vessel Formation in Subchondral Bone.

Osteoarthritis (OA) is a common and debilitating joint disease worldwide without interventions available to reverse its progression. Artesunate (ART), an anti-malaria agent, possesses diverse biological activities, including the inhibition of osteoclastogenesis and angiogenesis in various cells, but its role in subchondral bone during OA progression is not known. Here, we explored the curative effects of ART on the pathogenesis of OA in anterior cruciate ligament transection (ACLT) mice models. We found that ART attenuated articular cartilage degeneration, defined by lowered histologic scoring of OA and retarded calcification of the cartilage zone. Moreover, ART improved the expression of lubricin and aggrecan and reduced the expression of collagen X (Col X) and matrix metalloproteinase-13 (MMP-13). In parallel, ART normalized abnormal subchondral bone remodeling by maintaining bone volume fraction (BV/TV) and subchondral bone plate thickness (SBP Th) and reducing trabecular pattern factor (Tb.pf) compared to the vehicle-treated mice. Our results indicated that ART suppressed osteoclastic bone resorption through regulating RANKL-OPG system, restored coupled bone remodeling by indirectly inhibiting TGF-ß/Smad2/3 signaling. Additionally, ART abrogated CD31hiEmcnhi vessel formation via downregulating the expression of vascular endothelial growth factor (VEGF) and angiogenin-1 in subchondral bone. In conclusion, ART attenuates ACLT-induced OA by blocking bone resorption and CD31hiEmcnhi vessel formation in subchondral bone, indicating that this may be a new therapeutic alternative for OA.