LONP1 downregulation with ageing contributes to osteoarthritis via mitochondrial dysfunction.

Osteoarthritis (OA) is an age-related disorder and an important cause of disability that is characterized by a senescence-associated secretory phenotype and matrix degradation leading to a gradual loss of articular cartilage integrity. Mitochondria, as widespread organelles, are involved in regulation of complex biological processes such as energy synthesis and cell metabolism, which also have bidirectional communication with the nucleus to help maintain cellular homeostasis and regulate adaptation to a broad range of stressors. In light of the evidence that OA is strongly associated with mitochondrial dysfunction. In addition, mitochondria are considered to be the culprits of cell senescence, and mitochondrial function changes during ageing are considered to have a controlling role in cell fate. Mitochondrial dysfunction is also observed in age-related OA, however, the internal mechanism by which mitochondrial function changes with ageing to lead to the development of OA has not been elucidated. In this study, we found that the expression of Lon protease 1 (LONP1), a mitochondrial protease, was decreased in human OA cartilage and in ageing rat chondrocytes. Furthermore, LONP1 knockdown accelerated the progression and severity of osteoarthritis, which was associated with aspects of mitochondrial dysfunction including oxidative stress, metabolic changes and mitophagy, leading to downstream MAPK pathway activation. Antioxidant therapy with resveratrol suppressed oxidative stress and MAPK pathway activation induced by LONP1 knockdown to mitigate OA progression. Therefore, our findings demonstrate that LONP1 is a central regulator of mitochondrial function in chondrocytes and reveal that downregulation of LONP1 with ageing contributes to osteoarthritis.

Chondroitin sulfate microspheres anchored with drug-loaded liposomes play a dual antioxidant role in the treatment of osteoarthritis.

Reactive oxygen species (ROS) play a critical role in the pathogenesis of osteoarthritis. The injection of a single antioxidant drug is characterized by low drug utilization and short residence time in the articular cavity, limiting the therapeutic effect of antioxidant drugs on osteoarthritis. Currently, the drug circulation half-life can be extended using delivery vehicles such as liposomes and microspheres, which are widely used to treat diseases. In addition, the composite carriers of liposomes and hydrogel microspheres can combine the advantages of different material forms and show stronger plasticity and flexibility than traditional single carriers, which are expected to become new local drug delivery systems. Chondroitin sulfate, a sulfated glycosaminoglycan commonly found in native cartilage, has good antioxidant properties and degradability and is used to develop an injectable chondroitin sulfate hydrogel by covalent modification with photo-cross-linkable methacryloyl groups (ChsMA). Herein, ChsMA microgels anchored with liquiritin (LQ)-loaded liposomes (ChsMA@Lipo) were developed to delay the progression of osteoarthritis by dual antioxidation. On the one hand, the antioxidant drug LQ wrapped in ChsMA@Lipo microgels exhibits significant sustained-release kinetics due to the double obstruction of the lipid membrane and the hydrogel matrix network. On the other hand, ChsMA can eliminate ROS through degradation into chondroitin sulfate monomers by enzymes in vivo. Therefore, ChsMA@Lipo, as a degradable and dual antioxidant drug delivery platform, is a promising option for osteoarthritis treatment. STATEMENT OF SIGNIFICANCE: Compared with the traditional single carrier, the composite carriers of hydrogel microspheres and liposome can complement the advantages of different materials, which shows stronger plasticity and flexibility, and is expected to become a new and efficient drug delivery system. ChsMA@Lipo not only attenuates IL-1ß-induced ECM degradation in chondrocytes but also inhibits the M1 macrophages polarization and the inflammasome activation. The obtained ChsMA@Lipo alleviates the progression of osteoarthritis in vivo, which is promising for osteoarthritis treatment.

Nitidine Chloride Alleviates Inflammation and Cellular Senescence in Murine Osteoarthritis Through Scavenging ROS.

Osteoarthritis (OA) is one of the most common chronic musculoskeletal disorder worldwide, representing a major source of disability, pain and socioeconomic burden. Yet the effective pharmaceutical treatments applied in the clinical works are merely symptomatic management with uncertainty around their long-term safety and efficacy, namely no drugs currently are capable of modulating the biological progression of OA. Here, we identified the potent anti-inflammatory as well as anti-oxidative properties of Nitidine Chloride (NitC), a bioactive phytochemical alkaloid extracted from natural herbs, in IL-1ß-treated rat articular chondrocytes (RACs), LPS-stimulated RAW 264.7 and rat osteoarthritic models in vivo. We demonstrated NitC remarkably inhibited the production of inflammatory mediators including COX2 and iNOS, suppressed the activation of MAPK and NF-κB cell signaling pathway and reduced the expression of extracellular matrix (ECM) degrading enzymes including MMP3, MMP9 and MMP13 in IL-1ß-treated RACs. Several emerging bioinformatics tools were performed to predict the underlying mechanism, the result of which indicated the potential reactive oxygen species (ROS) clearance potential of NitC. Further, NitC exhibited its anti-oxidative potential through ameliorating cellular senescence in IL-1ß-treated RACs and decreasing NLRP3 inflammasomes activation in LPS-stimulated RAW 264.7 via scavenging ROS. Additionally, X-ray, micro-CT and other experiments in vivo demonstrated that intra-articular injection of NitC significantly alleviated the cartilage erosion, ECM degradation and subchondral alterations in OA progression. In conclusion, the present study reported the potent anti-inflammatory and anti-oxidative potential of NitC in OA biological process, providing a promising therapeutic agent for OA management.

circFAM160A2 Promotes Mitochondrial Stabilization and Apoptosis Reduction in Osteoarthritis Chondrocytes by Targeting miR-505-3p and SIRT3.

Competitive endogenous RNAs (ceRNAs), as a newly identified regulating mechanism, have been demonstrated to play a crucial role in various human diseases. An increasing number of recent studies have revealed that circular RNAs (circRNAs) can function as ceRNAs. However, little is known about the role of circFAM160A2 in the pathological process of osteoarthritis (OA). This study is the first to examine the crucial role of the circFAM160A2-miR-505-3p-SIRT3 axis in osteoarthritis progression. miR-505-3p was selected from the interaction of a microRNA (miRNA) microarray comparing chondrocytes in OA and normal conditions and prediction results from TargetScan. RT-qPCR was performed to assess the expression of circFAM160A2, miR-505-3p, and SIRT3. A dual luciferase assay was used to validate the binding of circFAM160A2, miR-505-3p, and SIRT3. We used lentivirus and adeno-associated virus to establish in vitro and in vivo overexpression models. Western blotting, apoptosis assay, ROS detection assay, Safranin O staining, and CCK-8 assay were employed to assess the role of circFAM160A2, miR-505-3p, and SIRT3. We found that miR-505-3p was upregulated and circFAM160A2 was downregulated in OA. While overexpression of circFAM160A2 decreased the production of extracellular matrix (ECM) degrading enzymes and ameliorated chondrocyte apoptosis and mitochondrial dysfunction, inhibition of miR-505-3p could reverse the protective effect of circFAM160A2 on the OA phenotype both in vitro and in vivo. In conclusion, circFAM160A2 can promote mitochondrial stabilization and apoptosis reduction in OA chondrocytes by targeting miR-505-3p and SIRT3, which might be a potential therapeutic target for OA therapy.

Self-Assembling Myristoylated Human α-Defensin 5 as a Next-Generation Nanobiotics Potentiates Therapeutic Efficacy in Bacterial Infection.

The increasing prevalence of antibacterial resistance globally underscores the urgent need to the update of antibiotics. Here, we describe a strategy for inducing the self-assembly of a host-defense antimicrobial peptide (AMP) into nanoparticle antibiotics (termed nanobiotics) with significantly improved pharmacological properties. Our strategy involves the myristoylation of human α-defensin 5 (HD5) as a therapeutic target and subsequent self-assembly in aqueous media in the absence of exogenous excipients. Compared with its parent HD5, the C-terminally myristoylated HD5 (HD5-myr)-assembled nanobiotic exhibited significantly enhanced broad-spectrum bactericidal activity in vitro. Mechanistically, it selectively killed Escherichia coli ( E. coli) and methicillin-resistant Staphylococcus aureus (MRSA) through disruption of the cell wall and/or membrane structure. The in vivo results further demonstrated that the HD5-myr nanobiotic protected against skin infection by MRSA and rescued mice from E. coli-induced sepsis by lowering the systemic bacterial burden and alleviating organ damage. The self-assembled HD5-myr nanobiotic also showed negligible hemolytic activity and substantially low toxicity in animals. Our findings validate this design rationale as a simple yet versatile strategy for generating AMP-derived nanobiotics with excellent in vivo tolerability. This advancement will likely have a broad impact on antibiotic discovery and development efforts aimed at combating antibacterial resistance.