Osteoarthritis (OA) is characterized by cartilage degeneration and inflammation. Procyanidin B2 (PCB2), a natural flavonoid compound, exhibits potential anti-inflammatory and anti-oxidative effects against several diseases. However, its curative effects on OA remain unclear. Herein, we explored the anti-arthritic effects of PCB2 on OA onset and progress and its potential mechanism. CCK-8 assays and EdU staining were used to assess the cytotoxic effects and cell proliferation activity of PCB2. Flow cytometry was used to detect apoptosis in chondrocytes. ELISA, qPCR, and western blotting, were applied to explore the expression of apoptosis and senescence-associated secretion phenotype (SASP) factors. The Nrf2/NF-κB signaling cascade was explored using immunofluorescence and western blotting. Additionally, we silenced the Nrf2 gene using siRNAs to verify its function in PCB2 regulation of senescence and apoptosis phenotypes. Safranin O-Fast Green (SO) and immunohistochemical staining were used to explore the effects of PCB2 on OA model rats. PCB2 dampened interleukin (IL)-1β-triggered expression of SASP factors in vitro. Additionally, PCB2 diminished IL-1β-triggered destruction of the extracellular matrix (ECM) via downregulating the expression of MMPs, while upregulating the expression of collagen II and aggrecan. In addition, PCB2 treatment reduced IL-1β-induced apoptosis of chondrocytes. Mechanistically, PCB2 could attenuated chondrocyte senescence in vitro via the Nrf2/NF-κB pathway. Moreover, PCB2 exhibited anti-apoptotic properties via the Nrf2/BAX/Bcl-2 pathway. PCB2 alleviated knee cartilage degeneration in an OA rat model. Our results suggest that PCB2 may be used as a therapeutic agent for OA.

Background: The defense response is a type of self-protective response of the body that protects it from damage by pathogenic factors. Although these reactions make important contributions to the occurrence and development of tumors, the role they play in osteosarcoma (OS), particularly in the immune microenvironment, remains unpredictable. Methods: This study included the clinical information and transcriptomic data of 84 osteosarcoma samples and the microarray data of 12 mesenchymal stem cell samples and 84 osteosarcoma samples. We obtained 129 differentially expressed genes related to the defense response (DRGs) by taking the intersection of differentially expressed genes with genes involved in the defense response pathway, and prognostic genes were screened using univariate Cox regression. Least absolute shrinkage and selection operator (LASSO) penalized Cox regression and multivariate Cox regression were then used to establish a DRG prognostic signature (DGPS) via the stepwise method. DGPS performance was examined using independent prognostic analysis, survival curves, and receiver operating characteristic (ROC) curves. In addition, the molecular and immune mechanisms of adverse prognosis in high-risk populations identified by DGPS were elucidated. The results were well verified by experiments. Result: BNIP3, PTGIS, and ZYX were identified as the most important DRGs for OS progression (hazard ratios of 2.044, 1.485, and 0.189, respectively). DGPS demonstrated outstanding performance in the prediction of OS prognosis (area under the curve (AUC) values of 0.842 and 0.787 in the training and test sets, respectively, adj-p < 0.05 in the survival curve). DGPS also performed better than a recent clinical prognostic approach with an AUC value of only 0.674 [metastasis], which was certified in the subsequent experimental results. These three genes regulate several key biological processes, including immune receptor activity and T cell activation, and they also reduce the infiltration of some immune cells, such as B cells, CD8+ T cells, and macrophages. Encouragingly, we found that DGPS was associated with sensitivity to chemotherapeutic drugs including JNK Inhibitor VIII, TGX221, MP470, and SB52334. Finally, we verified the effect of BNIP3 on apoptosis, proliferation, and migration of osteosarcoma cells through experiments. Conclusions: This study elucidated the role and mechanism of BNIP3, PTGIS, and ZYX in OS progression and was well verified by the experimental results, enabling reliable prognostic means and treatment strategies to be proposed for OS patients.

Dysregulated mitophagy is essential for mitochondrial quality control within human cancers. However, identifying hub genes regulating mitophagy and developing mitophagy‐based treatments to combat drug resistance remains challenging. Herein, BayeDEM (Bayesian‐optimized Deep learning for identifying Essential genes of Mitophagy) was proposed for such a task. After Bayesian optimization, BayeDEM demonstrated its excellent performance in identifying critical genes regulating mitophagy of osteosarcoma (area under curve [AUC] of ROC: 98.96%; AUC of PR curve: 100%). CERS1 was identified as the most essential gene regulating mitophagy (mean (|SHAP value|): 4.14). Inhibition of CERS1 sensitized cisplatin‐resistant osteosarcoma cells to cisplatin, restricting their growth, proliferation, invasion, migration and colony formation and inducing apoptosis. Mechanistically, inhibition of CERS1 restricted mitophagy to destroy the mitochondrial quality control in cisplatin‐resistant osteosarcoma cells, including mitochondrial membrane potential loss and unfavourable mitochondrial dynamics, rendering them susceptible to cisplatin‐induced apoptosis. More importantly, mitophagy facilitated the immunosuppressive microenvironment formation by significantly modulating T‐cell differentiation, adhesion and antigen presentation, and mitophagy mainly affects malignant osteoblasts in the early‐mid developmental stage. Immunologically, mitophagy potentially modulated the MIF signalling transmission between malignant osteoblasts and B cells, DCs, CD8+ T cells, NK cells and monocytes through the MIF‐(CD74 + CXCR4) receptor–ligand interaction, thereby modulating the biological functions of these immune cells. Collectively, BayeDEM emerged as a promising tool for oncologists to identify pivotal genes governing mitophagy, thereby enabling mitophagy‐centric therapeutic strategies to counteract drug resistance.

Background: Glucocorticoids (GCs) are a key pathogenic factor in steroid-induced avascular necrosis of the femoral head (SANFH). GCs can directly damage bone microvascular endothelial cells (BMECs), leading to impaired intraosseous blood supply. Recent studies suggest the Hippo signaling pathway may be involved in the pathogenesis of SANFH; however, its role in vascular endothelial repair and angiogenesis remains unclear. This study aims to investigate the therapeutic effects of human umbilical cord mesenchymal stem cells (hUC-MSCs) on SANFH, with a particular focus on their protective or reparative mechanisms on BMECs. Methods: In vivo, a SANFH mouse model is established and divided into NC, MPS, and hUC-MSCs groups, followed by Micro-CT imagin, hematoxylin and eosin (HE) staining and immunohistochemistry (IHC) (n = 8 per group). In vitro, BMECs are divided into NC, dexamethasone (Dex), hUC-MSCs, and Fer-1 groups to analyze cellular biological behaviors. Target protein expression is assessed using Western blotting and immunofluorescence microscopy. Ferroptosis-related markers are detected via biochemical assays. Mitochondrial ultrastructural changes are observed using transmission electron microscopy. Results: In vivo, the MPS group exhibited significant bone cavitation, sparse trabeculae, and disrupted trabecular architecture in the femoral head. The hUC-MSCs group showed marked improvement in bone microstructure, HE staining showed a significant decrease in the empty lacunae rate in the femoral head, and IHC results revealed markedly increased expression of cluster of differentiation 31 (CD31) and vascular endothelial growth factor (VEGF). In vitro, Dex stimulation suppressed BMECs proliferation. In Dex-treated cells, levels of intracellular reactive oxygen species (ROS), lipid peroxides, ferrous ion (Fe²⁺), malondialdehyde (MDA), acyl-CoA synthetase long chain family member 4 (ACSL4) and nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) were all increased, while expression of glutathione (GSH) and glutathione Peroxidase 4 (GPX4) was reduced. Transmission electron microscopy revealed plasma membrane rupture and reduction or loss of mitochondrial cristae. Furthermore, Dex promoted Hippo-mediated phosphorylation of Yes-associated protein (YAP)/Transcriptional coactivator with PDZ-binding motif (TAZ), upregulated NOX4 expression, and suppressed CD31 and VEGF expression. Following hUC-MSCs treatment, BMECs demonstrated enhanced proliferation, migration, and tube-forming capacity. Cellular GSH and GPX4 levels increased, antioxidant capacity was restored, peroxide accumulation decreased, and cells were protected from ferroptosis-effects comparable to those in the Fer-1 group. Additionally, hUC-MSCs inhibited YAP/TAZ phosphorylation and promoted elevated expression of CD31 and VEGF. Conclusions: These findings suggest that hUC-MSCs may attenuate Dex-induced ferroptosis in BMECs, enhance BMEC migration and angiogenesis, and improve femoral head microstructure in SANFH through modulation of the Hippo-YAP/TAZ signaling pathway. This study provides novel insights into the therapeutic potential of hUC-MSCs for SANFH.