Rationale: Osteoporosis is a severe bone disorder that is a threat to our aging population. Excessive osteoclast formation and bone resorption lead to changes in trabecular bone volume and architecture, leaving the bones vulnerable to fracture. Therapeutic approaches of inhibiting osteoclastogenesis and bone resorption have been proven to be an efficient approach to prevent osteoporosis. In our study, we have demonstrated for the first time that Loureirin B (LrB) inhibits ovariectomized osteoporosis and explored its underlying mechanisms of action in vitro. Methods: We examined the effects of LrB on RANKL-induced osteoclast differentiation and bone resorption, and its impacts on RANKL-induced NFATc1 activation, calcium oscillations and reactive oxygen species (ROS) production in osteoclasts in vitro. We assessed the in vivo efficacy of LrB using an ovariectomy (OVX)-induced osteoporosis model, which was analyzed using micro-computed tomography (micro-CT) and bone histomorphometry. Results: We found that LrB represses osteoclastogenesis, bone resorption, F-actin belts formation, osteoclast specific gene expressions, ROS activity and calcium oscillations through preventing NFATc1 translocation and expression as well as affecting MAPK-NFAT signaling pathways in vitro. Our in vivo study indicated that LrB prevents OVX-induced osteoporosis and preserves bone volume by repressing osteoclast activity and function. Conclusions: Our findings confirm that LrB can attenuate osteoclast formation and OVX-induced osteoporosis. This novel and exciting discovery could pave the way for the development of LrB as a potential therapeutic treatment for osteoporosis.

Background: Osteoporosis and atherosclerosis are common in the elderly population, conferring a heavy worldwide burden. Evidence links osteoporosis and atherosclerosis but the exact underlying common mechanism of its occurrence is unclear. The purpose of this study is to further explore the molecular mechanism between osteoporosis and atherosclerosis through integrated bioinformatic analysis.Methods: The microarray data of osteoporosis and atherosclerosis in the Gene Expression Omnibus (GEO) database were downloaded. The Weighted Gene Co-Expression Network Analysis (WGCNA) and differentially expressed genes (DEGs) analysis were used to identify the co-expression genes related to osteoporosis and atherosclerosis. In addition, the common gene targets of osteoporosis and atherosclerosis were analyzed and screened through three public databases (CTD, DISEASES, and GeneCards). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed by Metascape. Then, the common microRNAs (miRNAs) in osteoporosis and atherosclerosis were screened out from the Human microRNA Disease Database (HMDD) and the target genes of whom were predicted through the miRTarbase. Finally, the common miRNAs–genes network was constructed by Cytoscape software.Results: The results of common genes analysis showed that immune and inflammatory response may be a common feature in the pathophysiology of osteoporosis and atherosclerosis. Six hub genes (namely, COL1A1, IBSP, CTSD, RAC2, MAF, and THBS1) were obtained via taking interaction of different analysis results. The miRNAs–genes network showed that has-let-7g might play an important role in the common mechanisms between osteoporosis and atherosclerosis.Conclusion: This study provides new sights into shared molecular mechanisms between osteoporosis and atherosclerosis. These common pathways and hub genes may offer promising clues for further experimental studies.

Vitamin K2 (VK2) is an effective compound for anti-ferroptosis and anti-osteoporosis, and Semen sojae praeparatum (Dandouchi in Chinese) is the main source of VK2. Chondrocyte ferroptosis and extracellular matrix (ECM) degradation playing a role in the pathogenesis of osteoarthritis (OA). Glutathione peroxidase 4 (GPX4) is the intersection of two mechanisms in regulating OA progression. But no studies have elucidated the therapeutic effects and mechanisms of VK2 on OA. This study utilized an in vivo rat OA model created via anterior cruciate ligament transection (ACLT) and an in vitro chondrocyte oxidative damage model induced by TBHP to investigate the protective effects and mechanisms of action of VK2 in OA. Knee joint pain in mice was evaluated using the Von Frey test. Micro-CT and Safranin O-Fast Green staining were employed to observe the extent of damage to the tibial cartilage and subchondral bone, while immunohistochemistry and PCR were used to examine GPX4 levels in joint cartilage. The effects of VK2 on rat chondrocyte viability were assessed using CCK-8 and flow cytometry assays, and chondrocyte morphology was observed with toluidine blue and alcian blue staining. The impact of VK2 on intracellular ferroptosis-related markers was observed using fluorescent staining and flow cytometry. Protein expression changes were detected by immunofluorescence and Western blot analysis. Furthermore, specific protein inhibitors were applied to confirm the dual-regulatory effects of VK2 on GPX4. VK2 can increase bone mass and cartilage thickness in the subchondral bone of the tibia, and reduce pain and the OARSI score induced by OA. Immunohistochemistry results indicate that VK2 exerts its anti-OA effects by regulating GPX4 to delay ECM degradation. VK2 can inhibit the activation of the MAPK/NFκB signaling pathway caused by reduced expression of intracellular GPX4, thereby decreasing ECM degradation. Additionally, VK2 can reverse the inhibitory effect of RSL3 on GPX4, increase intracellular GSH content and the GSH/GSSG ratio, reduce MDA content, and rescue chondrocyte ferroptosis. The protective mechanism of VK2 may involve its dual-target regulation of GPX4, reducing chondrocyte ferroptosis and inhibiting the MAPK/NFκB signaling pathway to decelerate the degradation of the chondrocyte extracellular matrix.

Osteolytic diseases are typified by over‐enhanced formation and resorbing function of osteoclasts and have a major impact on human health. Inhibition of osteoclastic differentiation and function is a key strategy for clinical therapy of osteolytic conditions. Maackiain is a natural compound extracted from Sophora flavescens, which has been applied to anti‐allergic and anti‐tumour treatments. The present results showed that Maackiain could restrain receptor activator of nuclear factor‐κB ligand (RANKL)‐stimulated osteoclast formation and hydroxyapatite resorption dose‐dependently, and interrupt the structures of F‐actin belts in the mature osteoclasts. It also repressed the expressions of osteoclast‐specific genes and proteins. Furthermore, Maackiain could inhibit RANKL‐stimulated NF‐κB and calcium signalling pathways, and dampen Nuclear factor of activated T cell cytoplasmic 1 activity, protein expression and translocation into the nucleus. These results revealed that Maackiain may have a potential therapeutic effect on osteoclast‐related disorders.

Purpose. The aim of this study is to explore pathological mechanisms of bone fragility in type 2 diabetes mellitus (T2DM) patients. Methods. Identifying common genes for T2DM and osteoporosis by taking the intersection is shared by the Comparative Toxicogenomics Database (CTD), DISEASES, and GeneCards databases. The differentially expressed genes (DEGs) and the differentially expressed miRNAs (DEMs) were identified by analyzing the Gene Expression Omnibus (GEO) datasets (GSE35958, GSE43950, and GSE70318). FunRich and miRNet were applied to predict potential upstream transcription factors and downstream target genes of candidate DEMs, respectively. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed to explore potential mechanisms using Metascape. Eventually, a miRNA‐gene network was constructed by Cytoscape software. Results. 271 common targets and 35 common DEGs between T2DM and osteoporosis were screened out in the above databases, and a total of ten DEMs were obtained in the GSE70318. SP1 was predicted to potentially regulate most of the DEMs. Enrichment analysis showed the PI3K‐Akt signaling pathway and AGE‐RAGE signaling pathway in diabetic complications may play an important role in diabetic skeletal fragility. Two genes (NAMPT and IGFBP5) were considered as key genes involving in the development of diabetic osteoporosis. Through the construction of the miRNA‐gene network, most of the hub genes were found to be potentially modulated by miR‐96‐5p and miR‐7‐5p. Conclusion. The study uncovered several important genes, miRNAs, and pathological mechanisms involved in diabetic skeletal fragility, among which the PI3K‐Akt signaling pathway and AGE‐RAGE signaling pathway in diabetic complications may play important roles.

Background: Picroside II (P-II) is the main bioactive constituent of Picrorhiza Kurroa, a traditional Chinese herb of interest for its proven anti-inflammatory properties. Its beneficial effects have been noted across several physiological systems, including the nervous, circulatory, and digestive, capable of treating a wide range of diseases. Nevertheless, the potential of Picroside II to treat osteoarthritis (OA) and the mechanisms behind its efficacy remain largely unexplored. Aim: This study aims to evaluate the efficacy of Picroside II in the treatment of osteoarthritis and its potential molecular mechanisms. Methods: In vitro, we induced cellular inflammation in chondrocytes with lipopolysaccharide (LPS) and subsequently treated with Picroside II to assess protective effect on chondrocyte. We employed the Cell Counting Kit-8 (CCK-8) assay to assess the impact of Picroside II on cell viability and select the optimal Picroside II concentration for subsequent experiments. We explored the effect of Picroside II on chondrocyte pyroptosis and its underlying molecular mechanisms by qRT-PCR, Western blot (WB) and immunofluorescence. In vivo, we established the destabilization of the medial meniscus surgery to create an OA mouse model. The therapeutic effects of Picroside II were then assessed through Micro-CT scanning, Hematoxylin-eosin (H&E) staining, Safranin O-Fast Green (S&F) staining, immunohistochemistry and immunofluorescence. Results: In in vitro studies, toluidine blue and CCK-8 results showed that a certain concentration of Picroside II had a restorative effect on the viability of chondrocytes inhibited by LPS. Picroside II notably suppressed the expression levels of caspase-1, IL-18, and IL-1β, which consequently led to the reduction of pyroptosis. Moreover, Picroside II was shown to decrease NLRP3 inflammasome activation, via the MAPK/NF-κB signaling pathway. In vivo studies have shown that Picroside II can effectively reduce subchondral bone destruction and osteophyte formation in the knee joint of mice after DMM surgery. Conclusions: Our research suggests that Picroside II can inhibit chondrocyte pyroptosis and ameliorate osteoarthritis progression by modulating the MAPK/NF-κB signaling pathway.