Betaine Attenuates Osteoarthritis by Inhibiting Osteoclastogenesis and Angiogenesis in Subchondral Bone

Imrecoxib: Advances in Pharmacology and Therapeutics

Imrecoxib, a cyclooxygenase-2 (COX-2) selective non-steroidal anti-inflammatory drug (NSAID), was discovered via the balanced inhibition strategy of COX-1/COX-2. It is indicated for the relief of painful symptoms of osteoarthritis. There have been some pharmacological and therapeutic advances since the approval of imrecoxib in 2011. However, an update review in this aspect is not yet available. Relevant literature until January 2024 was identified by search of PubMed, Web of science, Embase and CNKI. From the perspective of efficacy, imrecoxib provides relief of osteoarthritis symptoms, and potential off-label use for treatment of idiopathic pulmonary fibrosis, perioperative pain, hand-foot syndrome, axial spondyloarthritis, COVID-19, cartilage injury, and malignancies such as lung and colon cancer. From a safety point of view, imrecoxib showed adverse effects common to NSAIDs; however, it has lower incidence of new-onset hypertension than other types of selective COX-2 inhibitors, less gastrointestinal toxicities than non-selective NSAIDs, weaker risk of drug interaction than celecoxib, and more suitable for elderly patients due to balanced inhibition of COX-1/COX-2. From a pharmacoeconomic perspective, imrecoxib is more cost-effective than celecoxib and diclofenac for osteoarthritis patients. With the deepening of the disease pathophysiology study of osteoarthritis, new therapeutic schemes and pharmacological mechanisms are constantly discovered. In the field of osteoarthritis treatment, mechanisms other than the analgesic and anti-inflammatory effects of COX-2 inhibitors are also being explored. Taken together, imrecoxib is a moderate selective COX-2 inhibitor with some advantages, and there would be more clinical applications and research opportunities in the future.

Bone and Joint-on-Chip Platforms: Construction Strategies and Applications

Organ-on-a-chip, also known as "tissue chip," is an advanced platform based on microfluidic systems for constructing miniature organ models in vitro. They can replicate the complex physiological and pathological responses of human organs. In recent years, the development of bone and joint-on-chip platforms aims to simulate the complex physiological and pathological processes occurring in human bones and joints, including cell-cell interactions, the interplay of various biochemical factors, the effects of mechanical stimuli, and the intricate connections between multiple organs. In the future, bone and joint-on-chip platforms will integrate the advantages of multiple disciplines, bringing more possibilities for exploring disease mechanisms, drug screening, and personalized medicine. This review explores the construction and application of Organ-on-a-chip technology in bone and joint disease research, proposes a modular construction concept, and discusses the new opportunities and future challenges in the construction and application of bone and joint-on-chip platforms.

Advances in exosome modulation of ferroptosis for the treatment of orthopedic diseases

Current treatments for orthopaedic illnesses frequently result in poor prognosis, treatment failure, numerous relapses, and other unpleasant outcomes that have a significant impact on patients' quality of life. Cell-free therapy has emerged as one of the most promising options in recent decades for improving the status quo. As a result, using exosomes produced from various cells to modulate ferroptosis has been proposed as a therapeutic method for the condition. Exosomes are extracellular vesicles that secrete various bioactive chemicals that influence disease treatment and play a role in the genesis and progression of orthopaedic illnesses. Ferroptosis is a recently defined kind of controlled cell death typified by large iron ion buildup and lipid peroxidation. An increasing number of studies indicate that ferroptosis plays a significant role in orthopaedic illnesses. Exosomes, as intercellular information transfer channels, have been found to play a significant role in the regulation of ferroptosis processes. Furthermore, accumulating research suggests that exosomes can influence the course of many diseases by regulating ferroptosis in injured cells. In order to better understand the processes by which exosomes govern ferroptosis in the therapy of orthopaedic illnesses. This review discusses the biogenesis, secretion, and uptake of exosomes, as well as the mechanisms of ferroptosis and exosomes in the therapy of orthopaedic illnesses. It focuses on recent research advances and exosome mechanisms in regulating iron death for the therapy of orthopaedic illnesses. The present state of review conducted both domestically and internationally is elucidated and anticipated as a viable avenue for future therapy in the field of orthopaedics.

Intra-Articular Injection of PLGA/Polydopamine Core-Shell Nanoparticle Attenuates Osteoarthritis Progression

Osteoarthritis (OA) is a common joint disease characterized by progressive cartilage degeneration. Unfortunately, currently available clinical drugs are mainly analgesics and cannot alleviate the development of OA. Kartogenin (KGN) has been found to promote the differentiation of bone marrow mesenchymal stem cells (BMSCs) into chondrocytes for the treatment of cartilage damage in early OA. However, KGN, as a small hydrophobic molecule, is rapidly cleared from the synovial fluid after intra-articular injection. This study synthesized a KGN-loaded nanocarrier based on PLGA/polydopamine core/shell structure to treat OA. The fluorescence signal of KGN@PLGA/PDA-PEG-E7 nanoparticles lasted for 4 weeks, ensuring long-term sustained release of KGN from a single intra-articular injection. In addition, the polyphenolic structure of PDA enables it to effectively scavenge reactive oxygen species, and the BMSC-targeting peptide E7 (EPLQLKM) endows KGN@PLGA/PDA-PEG-E7 NPs with an effective affinity for BMSCs. As a result, the KGN@PLGA/PDA-PEG-E7 nanoparticles could effectively induce cartilage in vitro and protect the cartilage and subchondral bone in a rat ACLT model. This therapeutic strategy could also be extended to the delivery of other drugs, targeting other tissues to treat joint diseases.

Subchondral osteoclasts and osteoarthritis: new insights and potential therapeutic avenues

Osteoarthritis (OA) is the most common joint disease, and good therapeutic results are often difficult to obtain due to its complex pathogenesis and diverse causative factors. After decades of research and exploration of OA, it has been progressively found that subchondral bone is essential for its pathogenesis, and pathological changes in subchondral bone can be observed even before cartilage lesions develop. Osteoclasts, the main cells regulating bone resorption, play a crucial role in the pathogenesis of subchondral bone. Subchondral osteoclasts regulate the homeostasis of subchondral bone through the secretion of degradative enzymes, immunomodulation, and cell signaling pathways. In OA, osteoclasts are overactivated by autophagy, ncRNAs, and Rankl/Rank/OPG signaling pathways. Excessive bone resorption disrupts the balance of bone remodeling, leading to increased subchondral bone loss, decreased bone mineral density and consequent structural damage to articular cartilage and joint pain. With increased understanding of bone biology and targeted therapies, researchers have found that the activity and function of subchondral osteoclasts are affected by multiple pathways. In this review, we summarize the roles and mechanisms of subchondral osteoclasts in OA, enumerate the latest advances in subchondral osteoclast-targeted therapy for OA, and look forward to the future trends of subchondral osteoclast-targeted therapies in clinical applications to fill the gaps in the current knowledge of OA treatment and to develop new therapeutic strategies.

A 70% Ethanol Neorhodomela munita Extract Attenuates RANKL-Induced Osteoclast Activation and H2O2-Induced Osteoblast Apoptosis In Vitro

The rapid aging of the population worldwide presents a significant social and economic challenge, particularly due to osteoporotic fractures, primarily resulting from an imbalance between osteoclast-mediated bone resorption and osteoblast-mediated bone formation. While conventional therapies offer benefits, they also present limitations and a range of adverse effects. This study explores the protective impact of Neorhodomela munita ethanol extract (EN) on osteoporosis by modulating critical pathways in osteoclastogenesis and apoptosis. Raw264.7 cells and Saos-2 cells were used for in vitro osteoclast and osteoblast models, respectively. By utilizing various in vitro methods to detect osteoclast differentiation/activation and osteoblast death, it was demonstrated that the EN's potential to inhibit RANKL induced osteoclast formation and activation by targeting the MAPKs-NFATc1/c-Fos pathway and reducing H2O2-induced cell death through the downregulation of apoptotic signals. This study highlights the potential benefits of EN for osteoporosis and suggests that EN is a promising natural alternative to traditional treatments.

Osteoclasts and osteoarthritis: Novel intervention targets and therapeutic potentials during aging

Osteoarthritis (OA), a chronic degenerative joint disease, is highly prevalent among the aging population, and often leads to joint pain, disability, and a diminished quality of life. Although considerable research has been conducted, the precise molecular mechanisms propelling OA pathogenesis continue to be elusive, thereby impeding the development of effective therapeutics. Notably, recent studies have revealed subchondral bone lesions precede cartilage degeneration in the early stage of OA. This development is marked by escalated osteoclast-mediated bone resorption, subsequent imbalances in bone metabolism, accelerated bone turnover, and a decrease in bone volume, thereby contributing significantly to the pathological changes. While the role of aging hallmarks in OA has been extensively elucidated from the perspective of chondrocytes, their connection with osteoclasts is not yet fully understood. There is compelling evidence to suggest that age-related abnormalities such as epigenetic alterations, proteostasis network disruption, cellular senescence, and mitochondrial dysfunction, can stimulate osteoclast activity. This review intends to systematically discuss how aging hallmarks contribute to OA pathogenesis, placing particular emphasis on the age-induced shifts in osteoclast activity. It also aims to stimulate future studies probing into the pathological mechanisms and therapeutic approaches targeting osteoclasts in OA during aging.

Mechanisms of vascular invasion after cartilage injury and potential engineering cartilage treatment strategies

Articular cartilage injury is one of the most common diseases in orthopedic clinics. Following an articular cartilage injury, an inability to resist vascular invasion can result in cartilage calcification by newly formed blood vessels. This process ultimately leads to the loss of joint function, significantly impacting the patient's quality of life. As a result, developing anti-angiogenic methods to repair damaged cartilage has become a popular research topic. Despite this, tissue engineering, as an anti-angiogenic strategy in cartilage injury repair, has not yet been adequately investigated. This exhaustive literature review mainly focused on the process and mechanism of vascular invasion in articular cartilage injury repair and summarized the major regulatory factors and signaling pathways affecting angiogenesis in the process of cartilage injury. We aimed to discuss several potential methods for engineering cartilage repair with anti-angiogenic strategies. Three anti-angiogenic tissue engineering methods were identified, including administering angiogenesis inhibitors, applying scaffolds to manage angiogenesis, and utilizing in vitro bioreactors to enhance the therapeutic properties of cultured chondrocytes. The advantages and disadvantages of each strategy were also analyzed. By exploring these anti-angiogenic tissue engineering methods, we hope to provide guidance for researchers in related fields for future research and development in cartilage repair.

Tanshinone IIA attenuates osteoarthritis via inhibiting aberrant angiogenesis in subchondral bone

Excessive angiogenesis in subchondral bone is a pathological feature of osteoarthritis (OA). Tanshinone IIA (TIIA), an active compound found in Salvia miltiorrhiza, demonstrates significant anti-angiogenic properties. However, the effect of TIIA on abnormal subchondral angiogenesis in OA is still unclear. This study aims to investigate the mechanism of TIIA in modulating subchondral bone angiogenesis during OA and assess its therapeutic potential in OA. Our findings demonstrate that TIIA attenuated articular cartilage degeneration, normalized subchondral bone remodeling, and effectively suppressed aberrant angiogenesis within subchondral bone in monosodium iodoacetate (MIA)-induced OA mice. Additionally, the angiogenesis capacity of primary CD31hiEmcnhi endothelial cells was observed to be significantly reduced after treatment with TIIA in vitro. Mechanically, TIIA diminished the proportion of hypertrophic chondrocytes, ultimately leading to a substantial reduction in the secretion of vascular endothelial growth factor A (VEGFA). The supernatant of hypertrophic chondrocytes promoted the tube formation of CD31hiEMCNhi endothelial cells, whereas TIIA inhibited this process. Furthermore, TIIA effectively suppressed the expression of vascular endothelial growth factor receptor 2 (VEGFR2) along with its downstream MAPK pathway in CD31hiEmcnhi endothelial cells. In conclusion, our data indicated that TIIA could effectively inhibit the abnormal angiogenesis in subchondral bone during the progression of OA by suppressing the VEGFA/VEFGR2/MAPK pathway. These findings significantly contribute to our understanding of the abnormal angiogenesis in OA and offer a promising therapeutic target for OA treatment.

Research progress of procyanidins in repairing cartilage injury after anterior cruciate ligament tear

Anterior cruciate ligament (ACL) tear is a common sports-related injury, and cartilage injury always emerges as a serious complication following ACL tear, significantly impacting the physical and psychological well-being of affected individuals. Over the years, efforts have been directed toward finding strategies to repair cartilage injury after ACL tear. In recent times, procyanidins, known for their anti-inflammatory and antioxidant properties, have emerged as potential key players in addressing this concern. This article focuses on summarizing the research progress of procyanidins in repairing cartilage injury after ACL tear. It covers the roles, mechanisms, and clinical significance of procyanidins in repairing cartilage injury following ACL tear and explores the future prospects of procyanidins in this domain. This review provides novel insights and hope for the repair of cartilage injury following ACL tear.

Comparative study of 1H-NMR metabolomic profile of canine synovial fluid in patients affected by four progressive stages of spontaneous osteoarthritis

The study aimed to assess the metabolomic profile of the synovial fluid (SF) of dogs affected by spontaneous osteoarthritis (OA) and compare any differences based on disease progression. Sixty client-owned dogs affected by spontaneous OA underwent clinical, radiographic, and cytologic evaluations to confirm the diagnosis. The affected joints were divided into four study groups based on the Kallgreen-Lawrence classification: OA1 (mild), OA2 (moderate), OA3 (severe), and OA4 (extremely severe/deforming). The osteoarthritic joint's SF was subjected to cytologic examination and 1H-NMR analysis. The metabolomic profiles of the study groups' SF samples were statistically compared using one-way ANOVA. Sixty osteoarthritic joints (45 stifles, 10 shoulders and 5 elbows) were included in the study. Fourteen, 28, and 18 joints were included in the OA1, OA2, and OA3 groups, respectively (0 joints in the OA4 group). Metabolomic analysis identified 48 metabolites, five of which were significantly different between study groups: Mannose and betaine were elevated in the OA1 group compared with the OA2 group, and the 2-hydroxyisobutyrate concentration decreased with OA progression; in contrast, isoleucine was less concentrated in mild vs. moderate OA, and lactate increased in severe OA. This study identified different 1H-NMR metabolomic profiles of canine SF in patients with progressive degrees of spontaneous OA, suggesting 1H-NMR metabolomic analysis as a potential alternative method for monitoring OA progression. In addition, the results suggest the therapeutic potentials of the metabolomic pathways that involve mannose, betaine, 2-hydroxyisobutyrate, isoleucine, and lactate.

Targeting the JAK2/STAT3 signaling pathway for chronic pain

Chronic pain is a notable health concern because of its prevalence, persistence, and associated mental stress. Drugs targeting chronic pain with potent abirritation, and minimal side effects remain unidentified. Substantial evidence indicates that the Janus Kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathway plays a distinct and critical role in different stages of chronic pain. Aberrant activation of the JAK2/STAT3 signaling pathway is evident in multiple chronic pain models. Moreover, an increasing number of studies have demonstrated that the downregulation of JAK2/STAT3 can attenuate chronic pain in different animal models. In this review, we investigated the mechanism and role of the JAK2/STAT3 signaling pathway in modulating chronic pain. The aberrant activation of JAK2/STAT3 can trigger chronic pain by interacting with microglia and astrocytes, releasing proinflammatory cytokines, inhibiting anti-inflammatory cytokines, and regulating synaptic plasticity. We also retrospectively reviewed current reports on JAK2/STAT3 pharmacological inhibitors that demonstrated their significant therapeutic potential in different types of chronic pain. In summary, our results provide strong evidence that the JAK2/STAT3 signaling pathway is a promising therapeutic target for chronic pain.

Small Joint Organoids 3D Bioprinting: Construction Strategy and Application

Osteoarthritis (OA) is a chronic disease that causes pain and disability in adults, affecting ≈300 million people worldwide. It is caused by damage to cartilage, including cellular inflammation and destruction of the extracellular matrix (ECM), leading to limited self-repairing ability due to the lack of blood vessels and nerves in the cartilage tissue. Organoid technology has emerged as a promising approach for cartilage repair, but constructing joint organoids with their complex structures and special mechanisms is still challenging. To overcome these boundaries, 3D bioprinting technology allows for the precise design of physiologically relevant joint organoids, including shape, structure, mechanical properties, cellular arrangement, and biological cues to mimic natural joint tissue. In this review, the authors will introduce the biological structure of joint tissues, summarize key procedures in 3D bioprinting for cartilage repair, and propose strategies for constructing joint organoids using 3D bioprinting. The authors also discuss the challenges of using joint organoids' approaches and perspectives on their future applications, opening opportunities to model joint tissues and response to joint disease treatment.

Single-cell RNA sequencing in osteoarthritis

Osteoarthritis is a progressive and heterogeneous joint disease with complex pathogenesis. The various phenotypes associated with each patient suggest that better subgrouping of tissues associated with genotypes in different phases of osteoarthritis may provide new insights into the onset and progression of the disease. Recently, single-cell RNA sequencing was used to describe osteoarthritis pathogenesis on a high-resolution view surpassing traditional technologies. Herein, this review summarizes the microstructural changes in articular cartilage, meniscus, synovium and subchondral bone that are mainly due to crosstalk amongst chondrocytes, osteoblasts, fibroblasts and endothelial cells during osteoarthritis progression. Next, we focus on the promising targets discovered by single-cell RNA sequencing and its potential applications in target drugs and tissue engineering. Additionally, the limited amount of research on the evaluation of bone-related biomaterials is reviewed. Based on the pre-clinical findings, we elaborate on the potential clinical values of single-cell RNA sequencing for the therapeutic strategies of osteoarthritis. Finally, a perspective on the future development of patient-centred medicine for osteoarthritis therapy combining other single-cell multi-omics technologies is discussed. This review will provide new insights into osteoarthritis pathogenesis on a cellular level and the field of applications of single-cell RNA sequencing in personalized therapeutics for osteoarthritis in the future.

Endothelial Stat3 activation promotes osteoarthritis development

The mechanism of the balance between subchondral angiogenesis and articular damage within osteoarthritis (OA) progression remains a mystery. However, the lack of specific drugs leads to limited clinical treatment options for OA, frequently failing to prevent eventual joint destruction in patients. Increasing evidence suggests that subchondral bone angiogenesis precedes cartilage injury, while proliferating endothelial cells (ECs) induce abnormal bone formation. Signal transducer and activator of transcription 3 (Stat3) is triggered by multiple cytokines in the OA microenvironment. Here, we observed elevated Stat3 activation in subchondral bone H-type vessels. Endothelial Stat3 activation will lead to stronger cell proliferation, migration and angiogenesis by simulating ECs in OA. In contrast, either Stat3 activation inhibition or knockdown of Stat3 expression could relieve such alterations. More interestingly, blocking Stat3 in ECs alleviated angiogenesis-mediated osteogenic differentiation and chondrocyte lesions. Stat3 inhibitor reversed surgically induced subchondral bone H-type vessel hyperplasia in vivo, significantly downregulating vessel volume and vessel number. Due to the reduced angiogenesis, subchondral bone deterioration and cartilage loss were alleviated. Overall, our data suggest that endothelial Stat3 activation is an essential trigger for OA development. Therefore, targeted Stat3 blockade is a novel promising therapeutic regimen for OA.

Network pharmacology-based pharmacological mechanism prediction of Lycii Fructus against postmenopausal osteoporosis

Postmenopausal osteoporosis (PMOP) has become one of most frequent bone diseases worldwide with aging population. Lycii Fructus, a common plant fruit with the property of drug homologous food, has long since been used to treat PMOP. The aim of this study is to explore pharmacological mechanisms of Lycii Fructus against PMOP through using network pharmacology approach. The active ingredients of Lycii Fructus were obtained from Traditional Chinese Medicine System Pharmacology database. Target fishing was performed on these ingredients in UniProt database for identification of the relative targets. Then, we screened the targets related to PMOP using GeneCards database and DisGeNET database. The overlapping genes between PMOP and Lycii Fructus were obtained to perform protein-protein interaction, gene ontology analysis, Kyoto Encyclopedia of Genes and Genomes analysis. A total of 35 active ingredients were identified in Lycii Fructus, and fished 158 related targets. Simultaneously, 292 targets associated with PMOP were obtained from GeneCards database and DisGeNET database. By drawing Venn diagram, 41 overlapping genes were obtained, and were considered as therapeutically relevant. Gene ontology enrichment analysis predicted that anti-inflammation and promotion of angiogenesis might be 2 potential mechanism of Lycii Fructus for PMOP treatment. Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed several pathways, such as IL-17 pathway, TNF pathway, MAPK pathway, PI3K-Akt signaling pathway and HIF signaling pathway were involved in regulating these 2 biological processes. Through the method of network pharmacology, we systematically investigated the mechanisms of Lycii Fructus against PMOP. The identified multi-targets and multi-pathways provide new insights to further determinate its exact pharmacological mechanisms.

Four-Arm Polymer-Guided Formation of Curcumin-Loaded Flower-Like Porous Microspheres as Injectable Cell Carriers for Diabetic Wound Healing

Stem cell injection is an effective approach for treating diabetic wounds; however, shear stress during injections can negatively affect their stemness and cell growth. Cell-laden porous microspheres can provide shelter for bone mesenchymal stem cells (BMSC). Herein, curcumin-loaded flower-like porous microspheres (CFPM) are designed by combining phase inversion emulsification with thermally induced phase separation-guided four-arm poly (l-lactic acid) (B-PLLA). Notably, the CFPM shows a well-defined surface topography and inner structure, ensuring a high surface area to enable the incorporation and delivery of a large amount of -BMSC and curcumin. The BMSC-carrying CFPM (BMSC@CFPM) maintains the proliferation, retention, and stemness of -BMSCs, which, in combination with their sustainable curcumin release, facilitates the endogenous production of growth/proangiogenic factors and offers a local anti-inflammatory function. An in vivo bioluminescence assay demonstrates that BMSC@CFPM can significantly increase the retention and survival of BMSC in wound sites. Accordingly, BMSC@CFPM, with no significant systemic toxicity, could significantly accelerate diabetic wound healing by promoting angiogenesis, collagen reconstruction, and M2 macrophage polarization. RNA sequencing further unveils the mechanisms by which BMSC@CFPM promotes diabetic wound healing by increasing -growth factors and enhancing angiogenesis through the JAK/STAT pathway. Overall, BMSC@CFPM represents a potential therapeutic tool for diabetic wound healing.

Lipid peroxidation in osteoarthritis: focusing on 4-hydroxynonenal, malondialdehyde, and ferroptosis

Osteoarthritis (OA) is a multifactorial and increasingly prevalent degenerative disease that affects the whole joint. The pathogenesis of OA is poorly understood and there is a lack of therapeutic interventions to reverse the pathological process of this disease. Accumulating studies have shown that the overproduction of reactive oxygen species (ROS) and ROS-induced lipid peroxidation are involved in the pathogenesis of OA. 4-Hydroxy-2-nonenal (4-HNE) and malondialdehyde (MDA) have received considerable attention for their role in cartilage degeneration and subchondral bone remodeling during OA development. Ferroptosis is a form of cell death characterized by a lack of control of membrane lipid peroxidation and recent studies have suggested that chondrocyte ferroptosis contributes to OA progression. In this review, we aim to discuss lipid peroxidation-derived 4-HNE and MDA in the progression of OA. In addition, the therapeutic potential for OA by controlling the accumulation of lipid peroxidation and inhibiting chondrocyte ferroptosis are discussed.

Mesenchymal Stromal Cells-Derived Extracellular Vesicles as Potential Treatments for Osteoarthritis

Osteoarthritis (OA) is a degenerative disease of the joints characterized by cartilage damage and severe pain. Despite various pharmacological and surgical interventions, current therapies fail to halt OA progression, leading to high morbidity and an economic burden. Thus, there is an urgent need for alternative therapeutic approaches that can effectively address the underlying pathophysiology of OA. Extracellular Vesicles (EVs) derived from mesenchymal stromal cells (MSCs) represent a new paradigm in OA treatment. MSC-EVs are small membranous particles released by MSCs during culture, both in vitro and in vivo. They possess regenerative properties and can attenuate inflammation, thereby promoting cartilage healing. Importantly, MSC-EVs have several advantages over MSCs as cell-based therapies, including lower risks of immune reactions and ethical issues. Researchers have recently explored different strategies, such as modifying EVs to enhance their delivery, targeting efficiency, and security, with promising results. This article reviews how MSC-EVs can help treat OA and how they might work. It also briefly discusses the benefits and challenges of using MSC-EVs and talks about the possibility of allogeneic and autologous MSC-EVs for medical use.

Secoisolariciresinol diglucoside Ameliorates Osteoarthritis via Nuclear factor-erythroid 2-related factor-2/ nuclear factor kappa B Pathway: In vitro and in vivo experiments

Osteoarthritis (OA) is an age-related joint disease in which inflammation and extracellular matrix (ECM) degradation play a crucial role in the destruction of articular cartilage. Secoisolariciresinol diglucoside (SDG), the main lignan in wholegrain flaxseed, which has been reported to remarkably suppress inflammation and oxidative stress, may have potential therapeutic value in OA. In this study, the effect and mechanism of SDG against cartilage degeneration were verified in the destabilization of the medial meniscus (DMM) and collagen-induced (CIA) arthritis models and interleukin-1β (IL-1β)-stimulated osteoarthritis chondrocyte models. From our experiments, SDG treatment downregulated the expression of pro-inflammatory factors induced by IL-1β in vitro, including inducible nitric oxide synthase (INOS), cyclooxygenase-2 (COX2), tumor necrosis factor (TNF-α), and interleukin 6 (IL-6). Additionally, SDG promoted the expression of collagen II (COL2A1) and SRY-related high-mobility-group-box gene 9(SOX9), while suppressing the expression of a disintegrin and metalloproteinase with thrombospondin motifs 5(ADAMTS5) and matrix metalloproteinases 13(MMP13), which leads to catabolism. Consistently, in vivo, SDG has been identified to have chondroprotective effects in DMM-induced and collagen-induced arthritis models. Mechanistically, SDG exerted its anti-inflammation and anti-ECM degradation effects by activating the Nrf2/HO-1 pathway and inhibiting the nuclear factor kappa B (NF-κB) pathway. In conclusion, SDG ameliorates the progression of OA via the Nrf2/NF-κB pathway, which indicates that SDG may have therapeutic potential for OA.

Maintaining hypoxia environment of subchondral bone alleviates osteoarthritis progression

Abnormal subchondral bone remodeling featured by overactivated osteoclastogenesis leads to articular cartilage degeneration and osteoarthritis (OA) progression, but the mechanism is unclear. We used lymphocyte cytosolic protein 1 (Lcp1) knockout mice to suppress subchondral osteoclasts in a mice OA model with anterior cruciate ligament transection (ACLT), and Lcp1^-/- mice showed decreased bone remodeling in subchondral bone and retarded cartilage degeneration. For mechanisms, the activated osteoclasts in subchondral bone induced type-H vessels and elevated oxygen concentration, which ubiquitylated hypoxia-inducible factor 1 alpha subunit (HIF-1α) in chondrocytes and led to cartilage degeneration. Lcp1 knockout impeded angiogenesis, which maintained hypoxia environment in joints and delayed the OA progression. Stabilization of HIF-1α delayed cartilage degeneration, and knockdown of Hif1a abolished the protective effects of Lcp1 knockout. Last, we showed that Oroxylin A, an Lcp1-encoded protein l-plastin (LPL) inhibitor, could alleviate OA progression. In conclusion, maintaining hypoxic environment is an attractive strategy for OA treatment.

Identification of kukoamine a as an anti-osteoporosis drug target using network pharmacology and experiment verification

BACKGROUND

Osteoporosis (OP) is a major and growing public health problem characterized by decreased bone mineral density and destroyed bone microarchitecture. Previous studies found that Lycium Chinense Mill (LC) has a potent role in inhibiting bone loss. Kukoamine A (KuA), a bioactive compound extract from LC was responsible for the anti-osteoporosis effect. This study aimed to investigate the anti-osteoporosis effect of KuA isolated from LC in treating OP and its potential molecular mechanism.

METHOD

In this study, network pharmacology and molecular docking were investigated firstly to find the active ingredients of LC such as KuA, and the target genes of OP by the TCMSP platform. The LC-OP-potential Target gene network was constructed by the STRING database and network maps were built by Cytoscape software. And then, the anti-osteoporotic effect of KuA in OVX-induced osteoporosis mice and MC3T3-E1 cell lines were investigated and the potential molecular mechanism including inflammation level, cell apoptosis, and oxidative stress was analyzed by dual-energy X-ray absorptiometry (DXA), micro-CT, ELISA, RT-PCR, and Western Blotting.

RESULT

A total of 22 active compounds were screened, and we found KuA was identified as the highest active ingredient. Glycogen Phosphorylase (PYGM) was the target gene associated with a maximum number of active ingredients of LC and regulated KuA. In vivo, KuA treatment significantly increased the bone mineral density and improve bone microarchitecture for example increased BV/TV, Tb.N and Tb.Th but reduced Tb.Sp in tibia and lumber 4. Furthermore, KuA increased mRNA expression of osteoblastic differentiation-related genes in OVX mice and protects against OVX-induced cell apoptosis, oxidative stress level and inflammation level. In vitro, KuA significantly improves osteogenic differentiation and mineralization in cells experiment. In addition, KuA also attenuated inflammation levels, cell apoptosis, and oxidative stress level.

CONCLUSION

The results suggest that KuA could protect against the development of OP in osteoblast cells and ovariectomized OP model mice and these found to provide a better understanding of the pharmacological activities of KuA again bone loss.

Circular RNA SLTM as a miR-421-competing endogenous RNA to mediate HMGB2 expression stimulates apoptosis and inflammation in arthritic chondrocytes

Osteoarthritis (OA) is the most common age-related joint disease characterized by chronic inflammation, progressive articular cartilage destruction, and subchondral sclerosis. Accumulating evidence suggests that circular RNAs (circRNAs) play key roles in OA, but the function of circSLTM in OA remains greatly unknown. Therefore, this study focused on interleukin-1β (IL-1β)-treated primary human chondrocytes as well as a rat model to investigate the expression pattern and functional role of circSLTM in OA in vitro and in vivo. CircSLTM and high mobility group protein B2 (HMGB2) were upregulated in IL-1β-induced chondrocytes, whereas miR-421 was downregulated. Knockdown of circSLTM or overexpression of miR-421 ameliorated IL-1β-induced chondrocyte apoptosis and inflammation. The regulatory relationship between circSLTM and miR-421, as well as that between miR-421 and HMGB2, was predicted by bioinformatics and then verified by the RNA immunoprecipitation experiment and dual-luciferase reporter gene assay. Furthermore, silencing of circSLTM increased cartilage destruction and decreased cartilage tissue apoptosis rate and inflammation in a rat model of OA. Taken together, our findings demonstrate the fundamental role of circSLTM in OA progression and provide a potential molecular target for OA therapy.

Treatment with Mesenchymal Stem Cell-Derived Nanovesicle-Containing Gelatin Methacryloyl Hydrogels Alleviates Osteoarthritis by Modulating Chondrogenesis and Macrophage Polarization

Osteoarthritis is a degenerative disorder that can severely affect joints, and new treatment strategies are urgently needed. Administration of mesenchymal stem cell (MSC)-derived exosomes is a promising therapeutic strategy in osteoarthritis treatment. However, the poor yield of exosomes is an obstacle to the use of this modality in the clinic. Herein, a promising strategy is developed to fabricate high-yield exosome-mimicking MSC-derived nanovesicles (MSC-NVs) with enhanced regenerative and anti-inflammatory capabilities. MSC-NVs are prepared using an extrusion approach and are found to increase chondrocyte and human bone marrow MSC differentiation, proliferation, and migration, in addition to inducing M2 macrophage polarization. Furthermore, gelatin methacryloyl (GelMA) hydrogels loaded with MSC-NVs (GelMA-NVs) are formulated, which exhibit sustained release of MSC-NVs and are shown to be biocompatible with excellent mechanical properties. In a mouse osteoarthritis model constructed by surgical destabilization of the medial meniscus (DMM), GelMA-NVs effectively ameliorate osteoarthritis severity, reduce the secretion of catabolic factors, and enhance matrix synthesis. Furthermore, GelMA-NVs induce M2 macrophage polarization and inflammatory response inhibition in vivo. The findings demonstrate that GelMA-NVs hold promise for osteoarthritis treatment through modulation of chondrogenesis and macrophage polarization.

Total lignans from Vitex negundo seeds attenuate osteoarthritis and their main component vitedoin A alleviates osteoclast differentiation by suppressing ERK/NFATc1 signaling

The seeds of Vitex negundo have been used for inflammation-related disease treatment in traditional medicine. This study focused on the anti-osteoarthritis (OA) effects of the total lignans of V. negundo seeds (TOV) in monosodium iodoacetate-induced osteoarthritis rats and its pharmacokinetic properties, as well as the effects and potential mechanism of its main components VN1 (6-hydroxy-4-(4-hydroxy-3-methoxy-phenyl)-3-hydro-xymethyl-7-methoxy-3,4-dihydro-2-naphthaldehydeb) and VN2 (vitedoin A) on receptor activator of NF-κB ligand (RANKL)-induced osteoclast differentiation in bone marrow macrophages (BMMs). TOV significantly attenuated osteoarthritis, leading to an increase in pain thresholds, improvement of knee articular cartilages and chondrocytes loss, and decreased total joint scores and serum levels of TNF-α, interleukin-1β (IL-1β), and prostaglandin E2 (PGE2) in osteoarthritis rats. The half-time (T_1/2 ) was 2.82 h and 1.33 h, and the bioavailability was 15.34%-21.89% and 16.29%-22.11%, for VN1 and VN2, respectively. VN2, rather than VN1, remarkably inhibited tartrate-resistant acid phosphatase (TRAP) activity, reduced the number of TRAP-positive multinuclear cells, diminished the formation of actin ring, and decreased mRNA levels of cathepsin K (CTSK), TRAP, nuclear factor of activated T cell 1 (NFATc1), and osteoclast-associated receptor, as well as downregulated protein levels of p-ERK (phosphorylated extracellular signal-regulated kinase), TRAP, CTSK and NFATc1 in BMMs. These findings suggest TOV has promising therapeutic potential for OA treatment and VN2, in particular, attenuates osteoclast differentiation by suppressing ERK/NFATc1 signaling and actin ring, mainly accounting for the anti-OA efficacy of TOV.

Selection and identification of a novel ssDNA aptamer targeting human skeletal muscle

Skeletal muscle disorders have posed great threats to health. Selective delivery of drugs and oligonucleotides to skeletal muscle is challenging. Aptamers can improve targeting efficacy. In this study, for the first time, the human skeletal muscle-specific ssDNA aptamers (HSM01, etc.) were selected and identified with Systematic Evolution of Ligands by Exponential Enrichment (SELEX). The HSM01 ssDNA aptamer preferentially interacted with human skeletal muscle cells in vitro. The in vivo study using tree shrews showed that the HSM01 ssDNA aptamer specifically targeted human skeletal muscle cells. Furthermore, the ability of HSM01 ssDNA aptamer to target skeletal muscle cells was not affected by the formation of a disulfide bond with nanoliposomes in vitro or in vivo, suggesting a potential new approach for targeted drug delivery to skeletal muscles via liposomes. Therefore, this newly identified ssDNA aptamer and nanoliposome modification could be used for the treatment of human skeletal muscle diseases.

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Using SELEX, our study selected and identified a human skeletal muscle-specific ssDNA aptamer.

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HSM01 ssDNA aptamer preferentially interacts with human skeletal muscle cells in vitro and in vivo.

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When linked with nanoliposomes, the skeletal muscle cells targeting ability still remains the same.

Targeted and responsive biomaterials in osteoarthritis

Osteoarthritis (OA) is a degenerative disease characterized by loss of articular cartilage and chronic inflammation, involving multiple cellular dysfunctions and tissue lesions. The non-vascular environment and dense cartilage matrix in the joints tend to block drug penetration, resulting in low drug bioavailability. There is a desire to develop safer and more effective OA therapies to meet the challenges of an aging world population in the future. Biomaterials have achieved satisfactory results in improving drug targeting, prolonging the duration of action, and achieving precision therapy. This article reviews the current basic understanding of the pathological mechanisms and clinical treatment dilemmas of OA, summarizes and discusses the advances for different kinds of targeted and responsive biomaterials in OA, seeking to provide new perspectives for the treatment of OA. Subsequently, limitations and challenges in clinical translation and biosafety are analyzed to guide the development of future therapeutic strategies for OA. As the need for precision medicine rises over time, emerging multifunctional biomaterials based on tissue targeting and controlled release will become an irreplaceable part of OA management.

Caspase-1 and Cathepsin B Inhibitors from Marine Invertebrates, Aiming at a Reduction in Neuroinflammation

Neuroinflammation is a condition associated with several types of dementia, such as Alzheimer’s disease (AD), mainly caused by an inflammatory response to amyloid peptides that induce microglial activation, with subsequent cytokine release. Neuronal caspase-1 from inflammasome and cathepsin B are key enzymes mediating neuroinflammation in AD, therefore, revealing new molecules to modulate these enzymes may be an interesting approach to treat neurodegenerative diseases. In this study, we searched for new caspase-1 and cathepsin B inhibitors from five species of Brazilian marine invertebrates (four cnidarians and one echinoderm). The results show that the extract of the box jellyfish Chiropsalmus quadrumanus inhibits caspase-1. This extract was fractionated, and the products monitored for their inhibitory activity, until the obtention of a pure molecule, which was identified as trigonelline by mass spectrometry. Moreover, four extracts inhibit cathepsin B, and Exaiptasia diaphana was selected for subsequent fractionation and characterization, resulting in the identification of betaine as being responsible for the inhibitory action. Both molecules are already found in marine organisms, however, this is the first study showing a potent inhibitory effect on caspase-1 and cathepsin B activities. Therefore, these new prototypes can be considered for the enzyme inhibition and subsequent control of the neuroinflammation.

Roles of the calcified cartilage layer and its tissue engineering reconstruction in osteoarthritis treatment

Sandwiched between articular cartilage and subchondral bone, the calcified cartilage layer (CCL) takes on both biomechanical and biochemical functions in joint development and ordinary activities. The formation of CCL is not only unique in articular cartilage but can also be found in the chondro-osseous junction adjacent to the growth plate during adolescence. The formation of CCL is an active process under both cellular regulation and intercellular communication. Abnormal alterations of CCL can be indications of degenerative diseases including osteoarthritis. Owing to the limited self-repair capability of articular cartilage and core status of CCL in microenvironment maintenance, tissue engineering reconstruction of CCL in damaged cartilage can be of great significance. This review focuses on possible tissue engineering reconstruction methods targeting CCL for further OA treatment.

Psoralen downregulates osteoarthritis chondrocyte inflammation via an estrogen-like effect and attenuates osteoarthritis

Estrogen and its receptor play a positive role in the development of osteoarthritis (OA). Psoralen is a plant-derived estrogen analog. This study aimed to verify whether psoralen inhibits OA through an estrogen-like effect. First, human primary chondrocytes in the late stage of OA were extracted to complete collagen type II immunofluorescence staining and cell proliferation experiments. Subsequently, estrogen, psoralen and estrogen receptor antagonists were co-cultured with OA chondrocytes, and RT-PCR was performed to detect the gene expression. A rabbit OA model was subsequently made by anterior cruciate ligament transection (ACLT). They were set as Sham group, OA group and Psoralen group, respectively. The articular cartilage samples were taken after 5 weeks of treatment, and the effect was observed by gross observation, histological staining, micro-CT scanning of subchondral bone. The results of cellular experiments displayed that the cultured cells were positive for collagen II fluorescence staining and 12 μg/mL psoralen was selected as the optimal concentration. In addition, psoralen had effects similar to estrogen, promoting the expression of estrogen tar-get genes CTSD, PGR and TFF1 and decreasing the expression of the inflammation-related gene TNF- α, IL-1β and IL-6. The effect of psoralen was blocked after the use of an estrogen receptor antagonist. Further animal experiments indicated that the psoralen group showed less destruction of cartilage tissue and decreased OASRI scores compared with the OA group. A subchondral bone CT scan demonstrated that psoralen significantly increased subchondral bone mineral density (BMD), trabecular thickness and trabecular number and decreased trabecular separation. In summary, psoralen inhibits the inflammatory production of chondrocytes, which is related to estrogen-like effect, and can be used to attenuate the progression of OA.

Recent Advances in Reactive Oxygen Species (ROS)-Responsive Polyfunctional Nanosystems 3.0 for the Treatment of Osteoarthritis

Osteoarthritis (OA) is an inflammatory and degenerative joint disease with severe effects on individuals, society, and the economy that affects millions of elderly people around the world. To date, there are no effective treatments for OA; however, there are some treatments that slow or prevent its progression. Polyfunctional nanosystems have many advantages, such as controlled release, targeted therapy and high loading rate, and have been widely used in OA treatment. Previous mechanistic studies have revealed that inflammation and ROS are interrelated, and a large number of studies have demonstrated that ROS play an important role in different types of OA development. In this review article, we summarize third-generation ROS-sensitive nanomaterials that scavenge excessive ROS from chondrocytes and osteoclasts in vivo. We only focus on polymer-based nanoparticles (NPs) and do not review the effects of drug-loaded or heavy metal NPs. Mounting evidence suggests that polyfunctional nanosystems will be a promising therapeutic strategy in OA therapy due to their unique characteristics of being sensitive to changes in the internal environment.

Comprehensive comparative analysis of histopathology and gene expression in subchondral bone between kashin-beck disease and primary osteoarthritis

Kashin-Beck disease (KBD) is an endemic, degenerative osteoarthropathy that exhibits some similar characteristics to osteoarthritis (OA) but with different etiologies and pathogeneses. In addition to cartilage damage, microstructural changes of bone were observed in KBD. This study aimed to comparatively demonstrate the general histopathological changes, transcriptomics, and differentially expressed miRNAs of subchondral bone between KBD and OA. Tibial plateau subchondral bone samples were collected from eighteen patients with KBD and eighteen patients with OA. Histopathological changes were examined by hematoxylin-eosin (HE) staining, safranin O-fast green staining, and picrosirius red staining. RNA sequencing and miRNA array analysis were performed to screen the differentially expressed genes (DEGs) and differentially expressed miRNAs (DEMs), respectively. The subchondral bone samples of the tibial plateau of KBD and OA both showed increased thickness and sclerosis. A total of 179 DEGs and 124 DEMs were identified in subchondral bone between KBD and OA, which were involved in several vital GO terms and KEGG signaling pathways. Our results suggest that the pathological mechanisms of subchondral bone are different between KBD and OA, although they exhibit similar histopathological features. Integrated analysis revealed several genes such as ADAMTS14, SLC13A5, and CEACAM1, that may be crucial DEGs in subchondral bone between KBD and OA, suggesting that these genes could serve as potential differential diagnostic biomarkers for subchondral bone lesions in KBD and OA. These findings provide valuable information for further clarifying pathological changes in subchondral bone in KBD and OA.

Rutin Inhibits the Progression of Osteoarthritis Through CBS-Mediated RhoA/ROCK Signaling

Osteoarthritis (OA) is a chronic joint disease characterized by the deterioration of cartilage and subchondral bone in the joints. Currently, there is no complete cure for OA, only treatments designed to temporarily relieve pain and improve function. Compared with the high cost of surgical treatment, medical treatment of OA is more acceptable and cost-effective. Rutin, as a flavonoid, has been shown to have anti-OA properties. We evaluated the effects of rutin on chondrocytes in lipopolysaccharide (LPS)-induced OA and on OA in rats induced by anterior cruciate ligament transection. We found that rutin effectively reduced the expression levels of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), and matrix metalloproteinase 13 (MMP-13) and increased the expression of Col II and aggrecan (p < 0.001). In addition, we also found that rutin increased the expression of cystathionine-β-synthase (CBS) and inhibited the expression of Rho-related coiled-coil protein kinase (ROCK) in chondrocytes (p < 0.05), thereby effectively inhibiting the inflammatory progression of OA. We concluded that rutin inhibits the inflammatory progression of OA through the CBS-mediated RhoA/ROCK signaling pathway.

Interaction of Neurovascular Signals in the Degraded Condylar Cartilage

Introduction: Degradation of the condylar cartilage during temporomandibular joint osteoarthritis (TMJ-OA) results in the infiltration of nerves, blood vessels and inflammatory cells from the subchondral bone into the cartilage. The interaction among innervation, angiogenesis and inflammation in the condylar cartilage of TMJ-OA remains largely unknown.

Method: In the present study, microarray-based transcriptome analysis was used to detect, and quantitative real-time polymerase chain reaction was used to validate transcriptome changes in the condylar cartilage from a well-established rat TMJ-OA model. Gene ontology (GO), Kyoto encyclopedia of genes and genomes (KEGG) pathway and protein-protein interaction (PPI) analyses were conducted.

Result: There were 1817 differentially expressed genes (DEGs, fold change ≥2, p < 0.05) between TMJ-OA and control cartilages, with 553 up-regulated and 1,264 down-regulated genes. Among those genes, representative DEGs with known/suspected roles in innervation, angiogenesis and inflammation were further validated by enriched GO terms and KEGG pathways. The DEGs related to innervation were predominately enriched in the GO terms of neurogenesis, generation of neurons, and KEGG pathways of cholinergic synapse and neurotrophin signaling. Genes related to angiogenesis were enriched in GO terms of vasculature and blood vessel development, and KEGG pathways of hypoxia-inducible factor 1 (HIF-1) pathway and calcium signaling pathway. For inflammation, the DEGs were enriched in the GO terms of immune system process and immune response, and KEGG pathways of Toll-like receptor and transforming growth factor β (TGFβ) signaling. Analysis with PPI indicated that the aforementioned DEGs were highly-interacted. Several hub genes such as v-akt murine thymoma viral oncogene homolog 1 (Akt1), glycogen synthase kinase 3β (Gsk3b), fibroblast growth factor 2 (Fgf2) and nerve growth factor receptor (Ngfr) were validated.

Conclusion: The present study demonstrated, for the first time, that intimate interactions exist among innervation, angiogenesis and inflammation in the condylar cartilage of TMJ-OA.

Stat3 Signaling Pathway: A Future Therapeutic Target for Bone-Related Diseases

Signal transducer and activator of transcription 3 (Stat3) is activated by phosphorylation and translocated to the nucleus to participate in the transcriptional regulation of DNA. Increasing evidences point that aberrant activation or deletion of the Stat3 plays a critical role in a broad range of pathological processes including immune escape, tumorigenesis, and inflammation. In the bone microenvironment, Stat3 acts as a common downstream response protein for multiple cytokines and is engaged in the modulation of cellular proliferation and intercellular interactions. Stat3 has direct impacts on disease progression by regulating mesenchymal stem cells differentiation, osteoclast activation, macrophage polarization, angiogenesis, and cartilage degradation. Here, we describe the theoretical basis and key roles of Stat3 in different bone-related diseases in combination with in vitro experiments and animal models. Then, we summarize and categorize the drugs that target Stat3, providing potential therapeutic strategies for their use in bone-related diseases. In conclusion, Stat3 could be a future target for bone-related diseases.

Research Progress of Exosomes in Bone Diseases: Mechanism, Diagnosis and Therapy

With the global escalation of the aging process, the number of patients with bone diseases is increasing year by year. Currently, there are limited effective treatments for bone diseases. Exosome, as a vital medium in cell-cell communication, can mediate tissue metabolism through the paracrine transmission of various cargos (proteins, nucleic acids, lipids, etc.) carried by itself. Recently, an increasing number of researchers have proven that exosomes play essential roles in the formation, metabolism, and pathological changes of bone and cartilage. Because exosomes have the advantages of small size, rich sources, and low immunogenicity, they can be used not only as substitutes for the traditional treatment of bone diseases, but also as biomarkers for the diagnosis of bone diseases. This paper reviews the research progress of several kinds of cells derived-exosomes in bone diseases and provides a theoretical basis for further research and clinical application of exosomes in bone diseases in the future.