Loganin ameliorates cartilage degeneration and osteoarthritis development in an osteoarthritis mouse model through inhibition of NF-κB activity and pyroptosis in chondrocytes

Exploration of the mode of death and potential death mechanisms of nucleus pulposus cells

Intervertebral disc degeneration (IVDD) is a common chronic orthopaedic disease in orthopaedics that imposes a heavy economic burden on people and society. Although it is well established that IVDD is associated with genetic susceptibility, ageing and obesity, its pathogenesis remains incompletely understood. Previously, IVDD was thought to occur because of excessive mechanical loading leading to destruction of nucleus pulposus cells (NPCs), but studies have shown that IVDD is a much more complex process associated with inflammation, metabolic factors and NPCs death and can involve all parts of the disc, characterized by causing NPCs death and extracellular matrix (ECM) degradation. The damage pattern of NPCs in IVDD is like that of some programmed cell death, suggesting that IVDD is associated with programmed cell death. Although apoptosis and pyroptosis of NPCs have been studied in IVDD, the pathogenesis of intervertebral disc degeneration can still not be fully elucidated by using only traditional cell death modalities. With increasing research, some new modes of cell death, PANoptosis, ferroptosis and senescence have been found to be closely related to intervertebral disc degeneration. Among these, PANoptosis combines essential elements of pyroptosis, apoptosis and necroptosis to form a highly coordinated and dynamically balanced programmed inflammatory cell death process. Furthermore, we believe that PANoptosis may also crosstalk with pyroptosis and senescence. Therefore, we review the progress of research on multiple deaths of NPCs in IVDD to provide guidance for clinical treatment.

Augmented Cornus officinalis Levels in Liuwei Dihuang Decoction Inhibits Nucleus Pulposus Cell Pyroptosis to Enhance Therapeutic Efficacy Against Intervertebral Disc Degeneration

Background

Intervertebral disc (IVD) degeneration (IVDD) is highly prevalent among the elderly population and stands as a leading cause of low back pain. Our prior studies have highlighted the therapeutic potential of Liuwei Dihuang decoction (LWDHD) and its component Cornus officinalis (CO)-derived compounds in alleviating IVDD and osteoarthritis, suggesting beneficial effects of CO in treating degenerative osteoarthropathies. However, uncertainty remains regarding the optimal CO dosage within LWDHD and its potential mechanism for effectively treating IVDD.

Objective

To ascertain the optimal dosage of CO within LWDHD for enhancing its therapeutic efficacy in treating IVDD, through a comparison of its effects across varied dosages using a mouse IVDD model.

Methods

Eight-week-old male C57BL/6J mice were subjected to a lumbar spine instability surgery to induce an IVDD model and received a modified LWDHD formulation containing varied dosages of CO (original dose of CO, or 5- or 10-time dose of CO (referred to as 1 × CO, 5 × CO, and 10 × CO)) for 8 weeks. The therapeutic efficacy on IVDD was evaluated through changes in lumbar spine function, histopathological morphology, extracellular matrix metabolism, nucleus pulposus cell viability, sensory nerve ingrowth, and nucleus pulposus (NP) cell pyroptosis.

Results

Augmenting CO levels in LWDHD led to a dose-dependent increase in the levels of CO-sourced active compounds in the plasma of mice. The modified LWDHD formulations, particularly the 5 × CO, exhibited a favorable pharmacological effect on lumbar function, structural integrity, ECM composition, NP cell viability, and sensory nerve ingrowth. Importantly, all 3 formulations notably mitigated NP cell pyroptosis by activating NRF2/KEAP1 pathway, with the 5 × CO formulation exhibiting superior efficacy. Additionally, a comprehensive score analysis indicated that 5 × CO formulation achieved the highest score.

Conclusion

These data underscore that elevating the dosage of CO to a specific threshold can enhance the effectiveness of LWDHD in treating IVDD.

MINK1 deficiency stimulates nucleus pulposus cell pyroptosis and exacerbates intervertebral disc degeneration

Intervertebral disc (IVD) degeneration, induced by aging and irregular mechanical strain, is highly prevalent in the elderly population, serving as a leading cause of chronic low back pain and disability. Evolving evidence has revealed the involvement of nucleus pulposus (NP) pyroptosis in the pathogenesis of IVD degeneration, while the precise regulatory mechanisms of NP pyroptosis remain obscure. Misshapen/Nck-interacting kinase (NIK)-related kinase 1 (MINK1), a serine-threonine protein kinase, has the potential to modulate the activation of NLRP3 inflammasome, indicating its pivotal role in governing pyroptosis. In this study, to assess the significance of MINK1 in NP pyroptosis and IVD degeneration, NP tissues from patients with varying degrees of IVD degeneration, and IVD tissues from both aging-induced and lumbar spine instability (LSI) surgery-induced IVD degeneration mouse models, with or without MINK1 ablation, were meticulously evaluated. Our findings indicated a notable decline in MINK1 expression in NP tissues of patients with IVD degeneration and both mouse models as degeneration progresses, accompanied by heightened matrix degradation and increased NP pyroptosis. Moreover, MINK1 ablation led to substantial activation of NP pyroptosis in both mouse models, and accelerating ECM degradation and intensifying the degeneration phenotype in mechanically stress-induced mice. Mechanistically, MINK1 deficiency triggered NF-κB signaling in NP tissues. Overall, our data illustrate an inverse correlation between MINK1 expression and severity of IVD degeneration, and the absence of MINK1 stimulates NP pyroptosis, exacerbating IVD degeneration by activating NF-κB signaling, highlighting a potential innovative therapeutic target in treating IVD degeneration.

Temporal progression of subchondral bone alterations in OA models involving induction of compromised meniscus integrity in mice and rats: A scoping review

OBJECTIVE

To categorize the temporal progression of subchondral bone alterations induced by compromising meniscus integrity in mouse and rat models of knee osteoarthritis (OA).

METHOD

Scoping review of investigations reporting subchondral bone changes with appropriate negative controls in the different mouse and rat models of OA induced by compromising meniscus integrity.

RESULTS

The available literature provides appropriate temporal detail on subchondral changes in these models, covering the entire spectrum of OA with an emphasis on early and mid-term time points. Microstructural changes of the subarticular spongiosa are comprehensively described; those of the subchondral bone plate are not. In mouse models, global subchondral bone alterations are unidirectional, involving an advancing sclerosis of the trabecular structure over time. In rats, biphasic subchondral bone alterations begin with an osteopenic degeneration and loss of subchondral trabeculae, progressing to a late sclerosis of the entire subchondral bone. Rat models, independently from the applied technique, relatively faithfully mirror the early bone loss detected in larger animals, and the late subchondral bone sclerosis observed in human advanced OA.

CONCLUSION

Mice and rats allow us to study the microstructural consequences of compromising meniscus integrity at high temporal detail. Thickening of the subchondral bone plate, an early loss of thinner subarticular trabecular elements, followed by a subsequent sclerosis of the entire subchondral bone are all important and reliable hallmarks that occur in parallel with the advancing articular cartilage degeneration. Thoughtful decisions on the study design, laterality, selection of controls and volumes of interest are crucial to obtain meaningful data.

Emerging technology has a brilliant future: the CRISPR-Cas system for senescence, inflammation, and cartilage repair in osteoarthritis

Osteoarthritis (OA), known as one of the most common types of aseptic inflammation of the musculoskeletal system, is characterized by chronic pain and whole-joint lesions. With cellular and molecular changes including senescence, inflammatory alterations, and subsequent cartilage defects, OA eventually leads to a series of adverse outcomes such as pain and disability. CRISPR-Cas-related technology has been proposed and explored as a gene therapy, offering potential gene-editing tools that are in the spotlight. Considering the genetic and multigene regulatory mechanisms of OA, we systematically review current studies on CRISPR-Cas technology for improving OA in terms of senescence, inflammation, and cartilage damage and summarize various strategies for delivering CRISPR products, hoping to provide a new perspective for the treatment of OA by taking advantage of CRISPR technology.

Sipeimine ameliorates osteoarthritis progression by suppression of NLRP3 inflammasome-mediated pyroptosis through inhibition of PI3K/AKT/NF-κB pathway: An in vitro and in vivo study

Background

Osteoarthritis (OA) is a chronic and degenerative condition that persists and progresses over time. Sipeimine (Sip), a steroidal alkaloid derived from Fritillariae Cirrhosae Bulbus, has attracted considerable attention due to its exceptional anti-inflammatory, analgesic, antioxidant, and anti-cancer characteristics. However, Sip's effects on OA and its mechanism still need further research.

Methods

This study utilized network pharmacology to identify initial targets for Sip. Functional associations of Sip in OA were clarified through Gene Ontology (GO) enrichment analysis, bioinformatically analyzing a list of targets. Subsequently, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis assessed pathways linked to Sip's therapeutic efficacy in OA. Molecular docking techniques explored Sip's binding affinity with key targets. In vitro experiments assessed Sip's impact on lipopolysaccharide (LPS)-induced pro-inflammatory factors and its protective effects on collagen-II and aggrecan degradation within the extracellular matrix (ECM). Western blotting and fluorescence analyses were conducted to determine Sip-mediated signaling pathways. Moreover, in vivo experiments using a mouse OA model validated Sip's therapeutic efficacy.

Results

The results from network pharmacology revealed a total of 57 candidate targets for Sip in OA treatment. GO enrichment analysis demonstrated a robust correlation between Sip and inflammatory response, response to LPS and NF-κB-inducing kinase activity in OA. KEGG enrichment analysis highlighted the significance of NF-κB and PI3K-AKT pathways in Sip's therapeutic potential for OA. Furthermore, molecular docking results demonstrated Sip's robust binding affinity with p65 and PI3K. In vitro experiments demonstrated Sip's effectively suppressed the expression of pro-inflammatory factors induced by LPS, such as COX-2, iNOS, IL-1β, and IL-18. Besides, Sip counteracted the degradation of collagen-II and aggrecan within the ECM and the expression of MMP-13 and ADAMTS-5 mediated by LPS. The safeguarding effects of Sip were ascribed to its inhibition of PI3K/AKT/NF-κB pathway and NLRP3 inflammasome mediated pyroptosis. Additionally, in vivo experiments revealed that Sip could alleviate the subchondral remodeling, cartilage degeneration, synovitis as well as ECM degradation a mouse model of OA.

Conclusion

Sip exhibited potential in attenuating OA progression by suppressing the PI3K/AKT/NF-κB pathway, consequently inhibiting the activation of NLRP3 inflammasome and pyroptosis.

The translational potential statement

The translational potential of this articleThis study provides a biological rationale for the use of Sip as a potential candidate for OA treatment, provide a new concept for the cartilage targeted application of natural compounds.

Reactive oxygen species (ROS)-mediated M1 macrophage-dependent nanomedicine remodels inflammatory microenvironment for osteoarthritis recession

Osteoarthritis (OA) is a common chronic inflammatory disorder. Effective remodeling of inflammatory microenvironment in the joint is a promising strategy to prevent OA. However, current drugs remain unsatisfactory due to a lack of targeted and effective ways for relieving inflammatory conditions in OA joints. Bortezomib (BTZ), a proteasome inhibitor, could effectively inhibit proinflammatory cytokines but with poor accumulation in the inflammatory tissues. To overcome the shortcomings of BTZ delivery and to improve the efficacy of OA therapy, herein, we designed a novel nanomedicine (denoted as BTZ@PTK) by the co-assembly of BTZ and an amphiphilic copolymer (denoted as PTK) with ROS-cleaved thioketal (TK) linkages. The TK units in BTZ@PTK are first cleaved by the excessive ROS at OA sites, and then triggered the controlled release of BTZ, resulting in the accurate delivery and the inflammatory microenvironment remodeling. Accordingly, BTZ@PTK suppressed ROS generation and proinflammatory cytokines while promoting M1 macrophage apoptosis in lipopolysaccharide (LPS)-activated RAW264.7 macrophages or LPS/IFN-γ-treated primary macrophages, which leads to a better effect than BTZ. In OA mice, BTZ@PTK passively accumulates into inflamed joints to attenuate pain sensitivity and gait abnormality. Importantly, BTZ@PTK treatment successfully ameliorates synovitis with the reduction of synovial hyperplasia and synovitis scores by suppressing M1 macrophage polarization and promoting M1 macrophage apoptosis in the synovium, thereby delaying cartilage damage. Collectively, BTZ@PTK can effectively modulate inflammatory microenvironment for OA recession by activating M1 macrophage apoptosis and inhibiting M1macrophage-mediated inflammatory response.

Natural products in osteoarthritis treatment: bridging basic research to clinical applications

Osteoarthritis (OA) is the most prevalent degenerative musculoskeletal disease, severely impacting the function of patients and potentially leading to disability, especially among the elderly population. Natural products (NPs), obtained from components or metabolites of plants, animals, microorganisms etc., have gained significant attention as important conservative treatments for various diseases. Recently, NPs have been well studied in preclinical and clinical researches, showing promising potential in the treatment of OA. In this review, we summed up the main signaling pathways affected by NPs in OA treatment, including NF-κB, MAPKs, PI3K/AKT, SIRT1, and other pathways, which are related to inflammation, anabolism and catabolism, and cell death. In addition, we described the therapeutic effects of NPs in different OA animal models and the current clinical studies in OA patients. At last, we discussed the potential research directions including in-depth analysis of the mechanisms and new application strategies of NPs for the OA treatment, so as to promote the basic research and clinical transformation in the future. We hope that this review may allow us to get a better understanding about the potential bioeffects and mechanisms of NPs in OA therapy, and ultimately improve the effectiveness of NPs-based clinical conservative treatment for OA patients.

Pyroptosis in Osteoarthritis: Molecular Mechanisms and Therapeutic Implications

Osteoarthritis (OA) is a chronic disease that causes pain and functional impairment by affecting joint tissue. Its global impact is noteworthy, causing significant economic losses and property damage. Despite extensive research, the underlying pathogenesis of OA remain an area of ongoing investigation. It has recently been discovered that the OA progression is significantly influenced by pyroptosis. Pyroptosis is a complex process that involves three pathways culminating in the assembly of Gasdermin-D (GSDMD)-N-terminal (GSDMD-NT) into pores through aggregation on the plasma membrane. The aggregation of GSDMD-NT proteins stimulates the release of inflammatory mediators, such as Interleukin-1β (IL-1β), Interleukin-18 (IL-18), and Matrix Metallopeptidase 13 (MMP13), ultimately leading to cellular lysis. The pyroptosis process in specific cells, including synovial macrophages, fibroblast-like synoviocytes (FLS), chondrocytes, and subchondral osteoblasts, contributs factor to the development of OA. Currently, the specific cells that undergo pyroptosis first are not yet fully understood, and it remains unknown whether pyroptosis in one cell can trigger the same process in other cells. Therefore, targeting pyroptosis could potentially offer a novel treatment approach for OA patients. We present a comprehensive analysis of the molecular mechanisms and key features of pyroptosis. We also outline the current research progress on various aspects, including synovial tissue, articular cartilage, extracellular matrix (ECM), and subchondral bone, with a focus on pyroptosis. The aim is to provide theoretical references for the effective management of OA.

α-Solanine attenuates chondrocyte pyroptosis to improve osteoarthritis via suppressing NF-κB pathway

α-Solanine has been shown to exhibit anti-inflammatory and anti-tumour properties; however, its efficacy in treating osteoarthritis (OA) remains ambiguous. The study aimed to evaluate the therapeutic effects of α-solanine on OA development in a mouse OA model. The OA mice were subjected to varying concentrations of α-solanine, and various assessments were implemented to assess OA progression. We found that α-solanine significantly reduced osteophyte formation, subchondral sclerosis and OARSI score. And it decreased proteoglycan loss and calcification in articular cartilage. Specifically, α-solanine inhibited extracellular matrix degradation by downregulating collagen 10, matrix metalloproteinase 3 and 13, and upregulating collagen 2. Importantly, α-solanine reversed chondrocyte pyroptosis phenotype in articular cartilage of OA mice by inhibiting the elevated expressions of Caspase-1, Gsdmd and IL-1β, while also mitigating aberrant angiogenesis and sensory innervation in subchondral bone. Mechanistically, α-solanine notably hindered the early stages of OA progression by reducing I-κB phosphorylation and nuclear translocation of p65, thereby inactivating NF-κB signalling. Our findings demonstrate the capability of α-solanine to disrupt chondrocyte pyroptosis and sensory innervation, thereby improving osteoarthritic pathological progress by inhibiting NF-κB signalling. These results suggest that α-solanine could serve as a promising therapeutic agent for OA treatment.

Network pharmacology integrated with experimental validation revealed the mechanism of Fengshi Gutong Capsule in the treatment of osteoarthritis

ETHNOPHARMACOLOGICAL RELEVANCE

Fengshi Gutong Capsule (FSGTC) is a commonly used Chinese medicine for the treatment of joint pain caused by osteoarthritis (OA). However, the mechanism of action of FSGTC for OA remains unclear.

AIM OF THE STUDY

This study aimed to explore the alleviating effects and potential mechanisms of action of FSGTC for OA through data mining, network pharmacology, and in vitro experiments.

MATERIALS AND METHODS

High-performance liquid chromatography (HPLC) was performed to establish the fingerprints of FSGTC and detect the components of FSGTC absorbed in the blood. The effects of FSGTC on inflammation, immunity, and liver and kidney functions in patients with OA were evaluated by mining clinical data. The potential targets and pathways of FSGTC were screened using network pharmacology. Subsequently, CCK-8 assay, flow cytometry, western blotting, RT-qPCR, ELISA, and immunofluorescence were performed in IL-1β-stimulated chondrocytes for further validation.

RESULTS

Eighty-seven common peaks and 10 components were identified using the HPLC fingerprints of 12 batches of samples, and the similarity was in the range of 0.973-0.998. Retrospective clinical analysis demonstrated a significant reduction in inflammatory response levels among patients with OA who received FSGTC treatment. Network pharmacology analysis revealed that FSGTC potentially targeted processes related to inflammation, oxidative stress, and apoptosis. The phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT), The nuclear factor-κB (NF-κB), and janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathways were predicted to be the main pathways involved in the therapeutic effects of FSGTC in OA. In vitro, FSGTC-containing serum aided the proliferation of chondrocytes stimulated by IL-1β, while concurrently mitigating apoptosis, suppressing the expression of inflammatory cytokines and oxidative molecules, and inhibiting the degradation of the chondrocyte extracellular matrix (ECM).

CONCLUSIONS

FSGTC alleviates the inflammatory response in patients with OA. This therapeutic effect was attributed to its anti-inflammatory and antioxidant properties, and its ability to promote IL-1β-induced chondrocyte proliferation, inhibit apoptosis, and prevent the degradation of extracellular matrix. These favorable results were associated with the inhibition of the PI3K/AKT, NF-κB, and JAK2/STAT3 signaling pathways.

A comprehensive review of Cornus officinalis: health benefits, phytochemistry, and pharmacological effects for functional drug and food development

Introduction

Cornus officinalis sieb. et zucc, a deciduous tree or shrub, is renowned for its "Cornus flesh" fruit, which is widely acknowledged for its medicinal value when matured and dried. Leveraging C. officinalis as a foundational ingredient opens avenues for the development of environmentally friendly health foods, ranging from beverages and jams to preserves and canned products. Packed with diverse bioactive compounds, this species manifests a spectrum of pharmacological effects, including anti-inflammatory, antioxidant, antidiabetic, immunomodulatory, neuroprotective, and cardiovascular protective properties.

Methods

This study employs CiteSpace visual analysis software and a bibliometric analysis platform, drawing upon the Web of Science (WOS) database for literature spanning the last decade. Through a comprehensive analysis of available literature from WOS and Google Scholar, we present a thorough summary of the health benefits, phytochemistry, active compounds, and pharmacological effects of C. officinalis. Particular emphasis is placed on its potential in developing functional drugs and foods.

Results and Discussion

While this review enhances our understanding of C. officinalis as a prospective therapeutic agent, its clinical applicability underscores the need for further research and clinical studies to validate findings and establish safe and effective clinical applications.

Exploration and breakthrough in the mode of chondrocyte death - A potential new mechanism for osteoarthritis

Osteoarthritis (OA) is a frequent chronic joint disease in orthopedics that effects individuals and society significantly. Obesity, aging, genetic susceptibility, and joint misalignment are all known risk factors for OA, but its pathomechanism is still poorly understood. Researches have revealed that OA is a much complex process related to inflammation, metabolic and chondrocyte death. It can affect all parts of the joint and is characterized by causing chondrocyte death and extracellular matrix descent. Previously, OA was thought to develop from excessive mechanical loading leading to the destruction of articular cartilage. Since some programmed cell deaths and OA share a pattern of chondrocyte destruction, it is likely that OA also involves programmed cell death. Even though chondrocyte apoptosis and pyroptosis have been investigated in OA, clarifing solely conventional cell death pathways is still insufficient to understand the pathophysiology of osteoarthritis. With more researches, it has been discovered that osteoarthritis and other new cell death processes, including PANoptosis, ferroptosis, and cell senescence, are strongly associated. Among these, PANoptosis combines the key traits of pyroptosis, cell apoptosis, and necrotic apoptosis into a highly coordinated and dynamically balanced programmed inflammatory cell death mechanism. Furthermore, we think that PANopotosis might obstruct necroptosis and cell senescence. Therefore, in order to offer direction for therapeutic treatment, we evaluate the development of research on multiple cell death of chondrocytes in OA.

Inhibition of Caspase-1-mediated pyroptosis promotes osteogenic differentiation, offering a therapeutic target for osteoporosis

BACKGROUND

Pyroptosis, an emerging inflammatory form of cell death, has been previously demonstrated to stimulate a massive inflammatory response, thus hindering the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Nevertheless, the impact of pyroptosis in thwarting osteogenic differentiation and exacerbating the advancement of osteoporosis (OP) remains enigmatic.

METHODS

We evaluated the expression levels of pyroptosis-associated indicators, including NOD-like receptor family pyrin domain-containing protein 3 (NLRP3), CASPASE-1, IL-1β, and IL-18, in specimens obtained from femoral heads of OP patients, as well as in an ovariectomy-induced mouse model of OP. Subsequently, the precise roles of pyroptosis in osteogenic differentiation were investigated using bioinformatics analysis, alongside morphological and biochemical assessments.

RESULTS

The pivotal pyroptotic proteins, including NLRP3, Caspase-1, IL-1β, and IL-18, exhibited significant upregulation within the bone tissue samples of clinical OP cases, as well as in the femoral tissues of ovariectomy (OVX)-induced mouse OP model, displaying a negatively associated with compromised osteogenic capacity, as represented by lessened bone mass, suppressed expression of osteogenic proteins such as Runt-related transcription factor 2 (RUNX2), Alkaline phosphatase (ALP), Osterix (OSX), and Osteopontin (OPN), and increased lipid droplets. Moreover, bioinformatics analysis substantiated shared gene expression patterns between pyroptosis and OP pathology, encompassing NLRP3, Caspase-1, IL-1β, IL-18, etc. Furthermore, our in vitro investigation using ST2 cells revealed that dexamethasone treatment prominently induced pyroptosis while impeding osteogenic differentiation. Notably, gene silencing of Caspase-1 effectively counteracted the inhibitory effects of dexamethasone on osteogenic differentiation, as manifested by increased ALP activity and enhanced expression of RUNX2, ALP, OSX, and OPN.

CONCLUSION

Our findings unequivocally underscore that inhibition of Caspase-1-mediated pyroptosis promotes osteogenic differentiation, providing a promising therapeutic target for managing OP.

Loganin alleviates myocardial ischemia-reperfusion injury through GLP-1R/NLRP3-mediated pyroptosis pathway

Myocardial ischemia-reperfusion (I/R) injury is one of main pathological manifestations of cardiovascular outcomes related to NLRP3 inflammasome-mediated pyroptosis pathway. Loganin is an iridoid glycoside extracted from traditional Chinese medicines, which has multiple activities. However, the roles and mechanism of loganin in myocardial I/R injury remain largely unknown. The models of myocardial I/R injury were established using I/R-treated rats or OGD/R-treated H9C2 cardiomyocytes. Myocardial damage was assessed by TTC and hematoxylin-eosin staining. Pyroptosis-related marker levels were detected by immunohistochemistry, immunofluorescence and western blotting assays. Cell proliferation was examined via EdU assay. Cell apoptosis was investigated by LDH release and flow cytometry. The integrity of cell membrane was analyzed via Dil staining. GLP-1R and NLRP3 levels were detected by immunofluorescence and western blotting assays. Our results showed that loganin suppressed I/R-induced myocardial damage in rats by reducing myocardial infarct, injury and pyroptosis. In addition, loganin attenuated OGD/R-induced cardiomyocyte apoptosis through increasing cell proliferation and reducing LDH release and apoptotic rate. Loganin also mitigated OGD/R-induced cardiomyocyte pyroptosis by reducing cell membrane damage and levels of cleaved caspase-1, IL-1β and IL-18. Furthermore, loganin repressed GLP-1R/NLRP3 pathway activation in OGD/R-treated H9C2 cardiomyocytes by enhancing GLP-1R expression and decreasing NLRP3 level. GLP-1R/NLRP3 activation by GLP-1R inhibition or NLRP3 overexpression reversed the suppressive effects of loganin on OGD/R-induced cardiomyocyte pyroptosis. These data indicated that loganin prevented OGD/R-induced proliferation inhibition, apoptosis and pyroptosis in OGD/R-treated cardiomyocytes by inhibiting GLP-1R/NLRP3 activity, indicating the therapeutic potential of loganin in myocardial I/R injury.

Advances in understanding effects of miRNAs on apoptosis, autophagy, and pyroptosis in knee osteoarthritis

MicroRNAs (miRNAs) are a class of endogenous small non-coding RNAs. MicroRNAs-mediated signaling pathways play a critical regulatory role in inducing apoptosis, autophagy, and pyroptosis in developing knee osteoarthritis (KOA). Given this, we searched databases, such as PubMed, using keywords including "miRNA," "knee osteoarthritis," "apoptosis," "autophagy," "pyroptosis", and their combinations. Through an extensive literature review, we conclude that miRNAs can be modulated through various signaling pathways, such as Wnt/β-catenin, TGF-β, PI3K/AKT/mTOR, and NLRP3/Caspase-1, to regulate apoptosis, autophagy, and pyroptosis in KOA. Furthermore, we note that P2X7R and HMGB1 may be crucial regulatory molecules involved in the interconnected regulation of apoptosis, autophagy, and pyroptosis in KOA. Additionally, we describe that miR-140-5p and miR-107 can modulate the advancement of KOA chondrocytes by targeting distinct molecules involved in apoptosis, autophagy, and pyroptosis, respectively. Therefore, we conclude that miRNAs may be potential biomarkers and therapeutic targets for the early prediction, diagnosis, and effective therapeutic approaches of KOA.

Bone marrow stem cells incubated with ellipticine regenerate articular cartilage by attenuating inflammation and cartilage degradation in rabbit model

BACKGROUND

Ellipticine (Ellip.) was recently reported to have beneficial effects on the differentiation of adipose-derived stem cells into mature chondrocyte-like cells. On the other hand, no practical results have been derived from the transplantation of bone marrow stem cells (BMSCs) in a rabbit osteoarthritis (OA) model.

OBJECTIVES

This study examined whether autologous BMSCs incubated with ellipticine (Ellip.+BMSCs) could regenerate articular cartilage in rabbit OA, a model similar to degenerative arthritis in human beings.

METHODS

A portion of rabbit articular cartilage was surgically removed, and Ellip.+BMSCs were transplanted into the lesion area. After two and four weeks of treatment, the serum levels of proinflammatory cytokines, i.e., tumor necrosis factor α (TNF-α) and prostaglandin E2 (PGE2), were analyzed, while macroscopic and micro-computed tomography (CT) evaluations were conducted to determine the intensity of cartilage degeneration. Furthermore, immuno-blotting was performed to evaluate the mitogen-activated protein kinases, PI3K/Akt, and nuclear factor-κB (NF-κB) signaling in rabbit OA models. Histological staining was used to confirm the change in the pattern of collagen and proteoglycan in the articular cartilage matrix.

RESULTS

The transplantation of Ellip.+BMSCs elicited a chondroprotective effect by reducing the inflammatory factors (TNF-α, PGE2) in a time-dependent manner. Macroscopic observations, micro-CT, and histological staining revealed articular cartilage regeneration with the downregulation of matrix-metallo proteinases (MMPs), preventing articular cartilage degradation. Furthermore, histological observations confirmed a significant boost in the production of chondrocytes, collagen, and proteoglycan compared to the control group. Western blotting data revealed the downregulation of the p38, PI3K-Akt, and NF-κB inflammatory pathways to attenuate inflammation.

CONCLUSIONS

The transplantation of Ellip.+BMSCs normalized the OA condition by boosting the recovery of degenerated articular cartilage and inhibiting the catabolic signaling pathway.

Mechanistic and therapeutic insights into the function of NLRP3 inflammasome in sterile arthritis

The NLRP3 inflammasome, which belongs to the pyrin domain containing 3 family of NOD-like receptors, has a significant impact on both the innate and adaptive immune responses. Regulating host immune function and protecting against microbial invasion and cell damage, the NLRP3 inflammasome plays a crucial role. By triggering caspase-1, it facilitates the development of the inflammatory cytokines IL-1β and IL-18, and triggers cell pyroptosis, resulting in cell lysis and demise. Common sterile arthritis includes osteoarthritis (OA), rheumatoid arthritis (RA) and gouty arthritis (GA), all of which manifest as bone destruction and synovial inflammation in a complex inflammatory state, placing a significant medical burden on the families of patients and government agencies. In the past few years, there has been a growing interest in investigating the impact of cell pyroptosis on arthritis development, particularly the widespread occurrence of pyroptosis mediated by the NLRP3 inflammasome. The NLRP3 inflammasome's biological properties are briefly described in this review, along with the presentation of the fundamental processes of pyroptosis resulting from its activation. Furthermore, we provide a summary of the advancements made in studying the NLRP3 inflammasome in various forms of arthritis and enumerate the intervention approaches that target the NLRP3-mediated pyroptosis, either directly or indirectly. These discoveries lay the groundwork for future investigations on medications for arthritis, offering fresh approaches for the clinical identification and treatment of this condition.

Mir-25-3p in extracellular vesicles from fibroblast-like synoviocytes alleviates pyroptosis of chondrocytes in knee osteoarthritis

Knee osteoarthritis (KOA) is defined as a joint disease that occurs mostly among elderly people. Fibroblast-like synoviocytes-derived extracellular vesicles (FLS-EVs) have impacts on the treatment of OA. This study elucidated the mechanism of miR-25-3p in pyroptosis of chondrocytes in KOA. FLSs and EVs were extracted from neonatal mice; destabilization of the medial meniscus (DMM) was used to simulate KOA in mice, followed by the evaluation of cartilage damage and the contents of MMP-3 and MMP-13 in KOA mice. Lipopolysaccharide (LPS) was used to induce inflammation damage in mouse chondrocytes ATDC5, and the cell viability and the expressions of NLRP3, Cleaved-Caspase-1, GSDMD-N, IL-18, and IL-1β were examined. We found that FLS-EV treatment mitigated the knee-joint damage and symptoms of KOA mice, decreased MMP-3 and MMP-13, and inhibited pyroptosis of chondrocytes in DMM mice and LPS-induced ATD5 cells. Then, Cy3-labeled miR-25-3p in mice chondrocytes was observed and the expressions and the binding relation of miR-25-3p and cytoplasmic polyadenylation element-binding protein 1 (CPEB1) were verified. It showed that FLS-EVs carried miR-25-3p into chondrocytes, and upregulated miR-25-3p expression while inhibited CPEB1 transcription, resulting in mitigation of pyroptosis of chondrocytes, and CPEB1 overexpression reversed the inhibition of FLS-EVs on pyroptosis of chondrocytes in KOA.

Prevention and treatment of inflammatory arthritis with traditional Chinese medicine: Underlying mechanisms based on cell and molecular targets

Inflammatory arthritis, primarily including rheumatoid arthritis, osteoarthritis and ankylosing spondylitis, is a group of chronic inflammatory diseases, whose general feature is joint dysfunction with chronic pain and eventually causes disability in older people. To date, both Western medicine and traditional Chinese medicine (TCM) have developed a variety of therapeutic methods for inflammatory arthritis and achieved excellent results. But there is still a long way to totally cure these diseases. TCM has been used to treat various joint diseases for thousands of years in Asia. In this review, we summarize clinical efficacies of TCM in inflammatory arthritis treatment after reviewing the results demonstrated in meta-analyses, systematic reviews, and clinical trials. We pioneered taking inflammatory arthritis-related cell targets of TCM as the entry point and further elaborated the molecular targets inside the cells of TCM, especially the signaling pathways. In addition, we also briefly discussed the relationship between gut microbiota and TCM and described the role of drug delivery systems for using TCM more accurately and safely. We provide updated and comprehensive insights into the clinical application of TCM for inflammatory arthritis treatment. We hope this review can guide and inspire researchers to further explore mechanisms of the anti-arthritis activity of TCM and make a great leap forward in comprehending the science of TCM.

Iridoids and active ones in patrinia: A review

Iridoid is a special class of monoterpenoids, whose basic skeleton is the acetal derivative of antinodilaldehyde with a bicyclic H-5/H-9β, β-cisfused cyclopentan pyran ring. They were often existed in Valerianaceae, Rubiaceae, Scrophulariaceae and Labiaceae family, and has various biological activities, such as anti-inflammatory, hypoglycemic, neuroprotection, and soon. In this review, iridoids from Patrinia (Valerianaceae family), and the active ones as well as their mechanisms in recent 20 years were summarized. Up to now, a total of 115 iridoids had been identified in Patrinia, among which 48 had extensive biological activities mainly presented in anti-inflammatory, anti-tumor and neuroprotective. And the mechanisms involved in MAPK, NF-κB and JNK signal pathways. The summary for iridoids and their activities will provide the evidence to exploit the iridoids in Patrinia.

Identification of the Main Chemical constituents and mechanism of Renshen Guben oral liquid against Renal Fibrosis

BACKGROUND

Renal fibrosis is the late stage of many chronic kidney diseases (CKD). Clinically, there is almost no effective treatment for renal fibrosis except dialysis. Renshen Guben oral liquid (RSGB) is a Chinese patent medicine approved by National Medical Products Administration (NMPA), which is suitable for clinical patients with chronic nephritis. Currently, the chemical constituents of RSGB remains unclear, and its efficacy and mechanism on renal fibrosis have not been reported.

METHODS

In our research, ultra-high performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS/MS) was employed to describe the chemical profile of RSGB, unilateral ureteral obstruction (UUO) model in mice was established to evaluate the beneficial effect of RSGB on renal fibrosis by biochemical indexes, HE and Masson staining. RNA sequencing and "constituents-targets-pathways" multi-dimensional network was established to mine the mechanisms of RSGB. Key targets were verified by quantitative real-time PCR (qRT-PCR) and western bolt (WB).

RESULTS

A total of 201 constituents were identified or tentatively characterized, 15 of which were confirmed with standards. The number of triterpenes was the highest with 49, followed by phenols with 46. RSGB ameliorated the blood urea nitrogen (BUN) and serum creatinine (Scr) levels in serum, normalizing pathological structure of kidney tissue. RNA sequencing revealed that RSGB regulates 226 differential genes, which were involved in kidney development. According to the "constituents-targets-pathways" network, 26 key active constituents may mainly regulate the inflammatory immune system through 88 corresponding targets. qRT-PCR and WB results showed that RSGB inhibited the activation of the Tgfβ1/Smad2/3 pathway, Wnt4/β-Catenin pathway and NGFR/NF-κB pathway.

CONCLUSIONS

Overall, our study, for the first time, characterized 201 chemical constituents in RSGB, and 26 of them were screened out to alleviates renal fibrosis mainly through Tgfβ1/Smad2/3 pathway, Wnt4/β-catenin pathway and NGFR/NF-κB pathway, which may provide a new research strategy for research on the mechanism of traditional Chinese Medicine.

Monotropein attenuates apoptosis and pyroptosis in chondrocytes and alleviates osteoarthritis progression in mice

BACKGROUND

Osteoarthritis (OA) is a chronic degenerative joint disease characterized by loss of joint function, which seriously reduces the quality of life of the elderly and imposes a heavy socioeconomic burden worldwide. Monotropein (MON), the main active ingredient of Morinda officinalis F.C. How, has exhibited therapeutic effects in different disease models. However, its potential effects on chondrocytes in an arthritic model remain unclear. This study aimed to evaluate the effects of MON in chondrocytes and a mouse model of OA, and explore the potential mechanisms.

MATERIALS AND METHODS

Murine primary chondrocytes were pretreated with 10 ng/ml interleukin (IL)-1β for 24 h to establish an in vitro model of OA, and then treated with different concentrations of MON (0, 25, 50 and 100 μM) for 24 h. The proliferation of the chondrocytes was assayed using ethynyl-deoxyuridine (EdU) staining. Immunofluorescence staining, western blotting and TUNEL staining were performed to assess the effects of MON on cartilage matrix degradation, apoptosis and pyroptosis. The mouse model of OA was constructed by surgical destabilization of the medial meniscus (DMM), and the animals were randomly divided into the sham-operated, OA and OA + MON groups. Following OA induction, the mice were given intraarticular injection of 100 μM MON or equal volume of normal saline twice a week for 8 weeks. The effects of MON on cartilage matrix degradation, apoptosis and pyroptosis were assessed as indicated.

RESULTS

MON significantly accelerated the proliferation of chondrocytes, and inhibited cartilage matrix degradation, apoptosis and pyroptosis in the IL-1β-stimulated cells by blocking the nuclear factor-kappa B (NF-κB) signaling pathway. In the mouse model as well, MON treatment alleviated OA progression and promoted cartilage repair by inhibiting cartilage matrix degradation, and chondrocyte apoptosis and pyroptosis through the inactivation of the NF-κB signaling pathway. Furthermore, the MON-treated arthritic mice exhibited better articular tissue morphology and lower OARSI scores.

CONCLUSIONS

MON alleviated OA progression by inhibiting cartilage matrix degradation, and the apoptosis and pyroptosis of chondrocytes via NF-κB pathway inactivation, and is a promising alternative for the treatment of OA.

Mechanical stress protects against chondrocyte pyroptosis through TGF-β1-mediated activation of Smad2/3 and inhibition of the NF-κB signaling pathway in an osteoarthritis model

Osteoarthritis (OA) is a degenerative disease that is difficult to cure owing to its complicated pathogenesis. Exercise therapy has been endorsed as a primary treatment option. However, it remains controversial how exercise intensity regulates OA progression. Here, a declining propensity for TGF-β1 was predicted via bioinformatics analysis of microarray GSE57218 and validated in cartilage samples obtained from arthroplasty. Based on this, cyclic tensile strain or TGF-β1 intervention was performed on human OA chondrocytes, and we found that moderate-intensity mechanical loads protected chondrocytes against pyroptosis. During this process, the elevation of TGF-β1 is mechanically stimuli-dependent and exerts an inhibitory effect on chondrocyte pyroptosis. Moreover, we elucidated that TGF-β1 activated Smad2/3 and inhibited the NF-κB signaling pathway to suppress chondrocyte pyroptosis. Furthermore, we established a rat knee OA model by intra-articular injection of monosodium iodoacetate and performed treadmill exercises of different intensities. Similar to the in vitro results, we demonstrated that moderate-intensity treadmill exercise had an outstanding chondroprotective effect. An inappropriate intensity of mechanical stimulation may aggravate OA both in vivo and in vitro. Overall, our findings demonstrated that activation of the TGF-β1/Smad2/Smad3 axis and inhibition of NF-κB coordinately inhibit chondrocyte pyroptosis under mechanical loads. This study sheds light on the future development of safe and effective exercise therapies for OA.

Activation of Nrf2/HO-1 antioxidant signaling correlates with the preventive effect of loganin on oxidative injury in ARPE-19 human retinal pigment epithelial cells

BACKGROUND

Loganin, a type of iridoid glycoside derived from Corni Fructus, is known to have beneficial effects various chronic diseases. However, studies on mechanisms related to antioxidant efficacy in human retinal pigment epithelial (RPE) cells have not yet been conducted.

OBJECTIVES

This study was to investigate whether loganin could inhibit oxidative stress-mediated cellular damage caused by hydrogen peroxide (H₂O₂) in human RPE ARPE-19 cells.

METHODS

The preventive effect of loganin on H₂O₂-induced cytotoxicity, reactive oxygen species (ROS) generation, DNA damage and apoptosis was investigated. In addition, immunofluorescence staining and immunoblotting analysis were applied to evaluate the related mechanisms.

RESULTS

The loss of cell viability and increased ROS accumulation in H₂O₂-treated ARPE-19 cells were significantly abrogated by loganin pretreatment, which was associated with activation of nuclear factor erythroid 2-related factor 2 (Nrf2) and increased expression of heme oxygenase-1 (HO-1). Loganin also markedly attenuated H₂O₂-induced DNA damage, ultimately ameliorating apoptosis. In addition, H₂O₂-induced mitochondrial dysfunction was reversed in the presence of loganin as indicated by preservation of mitochondrial integrity, decrease of Bax/Bcl-2 expression ratio, reduction of caspase-3 activity and suppression of cytochrome c release into the cytoplasm. However, zinc protoporphyrin, a selective inhibitor of HO-1, remarkably alleviated the preventive effect offered by loganin against H₂O₂-mediated ARPE-19 cell injury, suggesting a critical role of Nrf2-mediated activation of HO-1 in the antioxidant activity of loganin.

CONCLUSION

The results of this study suggest that loganin-induced activation of the Nrf2/HO-1 axis is at least involved in protecting at least ARPE-19 cells from oxidative injury.

Pyroptosis and degenerative diseases of the elderly

Pyroptosis is a recently described mechanism of programmed cell death mediated by proteins of the gasdermin family. Widely recognized signaling cascades include the classical, non-classical, caspase-3-dependent gasdermin E and caspase-8-dependent gasdermin D pathways. Additional pyroptotic pathways have been subsequently reported. With the rising prevalence of advanced age, the role of pyroptosis in the degenerative diseases of the elderly has attracted increased research attention. This article reviews the primary mechanisms of pyroptosis and summarizes progress in the research of degenerative diseases of the elderly such as presbycusis, age-related macular degeneration, Alzheimer's disease, intervertebral disc degeneration, and osteoarthritis.

Osteoarthritis: pathogenic signaling pathways and therapeutic targets

Osteoarthritis (OA) is a chronic degenerative joint disorder that leads to disability and affects more than 500 million population worldwide. OA was believed to be caused by the wearing and tearing of articular cartilage, but it is now more commonly referred to as a chronic whole-joint disorder that is initiated with biochemical and cellular alterations in the synovial joint tissues, which leads to the histological and structural changes of the joint and ends up with the whole tissue dysfunction. Currently, there is no cure for OA, partly due to a lack of comprehensive understanding of the pathological mechanism of the initiation and progression of the disease. Therefore, a better understanding of pathological signaling pathways and key molecules involved in OA pathogenesis is crucial for therapeutic target design and drug development. In this review, we first summarize the epidemiology of OA, including its prevalence, incidence and burdens, and OA risk factors. We then focus on the roles and regulation of the pathological signaling pathways, such as Wnt/β-catenin, NF-κB, focal adhesion, HIFs, TGFβ/ΒΜP and FGF signaling pathways, and key regulators AMPK, mTOR, and RUNX2 in the onset and development of OA. In addition, the roles of factors associated with OA, including MMPs, ADAMTS/ADAMs, and PRG4, are discussed in detail. Finally, we provide updates on the current clinical therapies and clinical trials of biological treatments and drugs for OA. Research advances in basic knowledge of articular cartilage biology and OA pathogenesis will have a significant impact and translational value in developing OA therapeutic strategies.

Ginsenoside Compound K Ameliorates Osteoarthritis by Inhibiting the Chondrocyte Endoplasmic Reticulum Stress-Mediated IRE1α-TXNIP-NLRP3 Axis and Pyroptosis

Osteoarthritis (OA) is a common joint disease, and studies have reported that the endoplasmic reticulum stress (ERS) in chondrocytes caused by the cartilage tissue damage could mediate the activation of Nod-like receptor protein 3 (NLRP3) inflammasomes through inositol-requiring enzyme 1 alpha (IRE1α) and thioredoxin interacting protein (TXNIP). Ginsenoside compound K (CK) has an inhibitory effect on IRE1α activation. However, the role of IRE1α-TXNIP and its interaction with CK are still unclear. In this study, we examined the role and mechanism of action of CK in OA. We found that CK ameliorated OA and ERS in IL-1β-treated chondrocytes and a monoiodoacetate-induced rat OA model. The effect of CK on inflammation, pyroptosis, and ERS was blocked by the ERS inducer tunicamycin. In conclusion, CK hindered OA progression by inhibiting the ERS-IRE1α-TXNIP-NLRP3 axis. Overall, our data indicate that CK could be useful in the treatment of OA and other chronic inflammatory diseases.

Pyroptosis in bone loss

Pyroptosis could be responsible for the bone loss from bone metabolic diseases, leading to the negative impact on people's health and life. It has been shown that osteoclasts, osteoblasts, macrophages, chondrocytes, periodontal and gingival cells may be involved in bone loss linked with pyroptosis. So far, the involved mechanisms have not been fully elucidated. In this review, we introduced the related cells involved in the pyroptosis associated with bone loss and summarized the role of these cells in the bone metabolism during the process of pyroptosis. We also discuss the clinical potential of targeting mechanisms in the osteoclasts, osteoblasts, macrophages, chondrocytes, periodontal and gingival cells touched upon pyroptosis to treat bone loss from bone metabolic diseases as well as the challenges of avoiding potential side effects and producing efficient treatment methods.

Loganin Prevents Hepatic Steatosis by Blocking NLRP3 Inflammasome Activation

Activation of the NLRP3 inflammasome is a necessary process to induce fibrosis in nonalcoholic fatty liver disease (NAFLD). Nonalcoholic steatohepatitis (NASH) is a kind of NAFLD that encompasses the spectrum of liver disease. It is characterized by inflammation and ballooning of hepatocytes during steatosis. We tested whether inhibiting the NLRP3 inflammasome could prevent the development and pathology of NASH. We identified loganin as an inhibitor of the NLRP3 inflammasome and investigated whether in vivo administration of loganin prevented NASH symptoms using a methionine-choline deficient (MCD) diet model in mice. We found that loganin inhibited the NLRP3 inflammasome activation triggered by ATP or nigericin, as shown by suppression of the production of interleukin (IL)-1β and caspase-1 (p10) in mouse primary macrophages. The speck formation of apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) was blocked by loganin, showing that the assembly of the NLRP3 inflammasome complex was impaired by loganin. Administration of loganin reduced the clinical signs of NASH in mice fed the MCD diet, including hepatic inflammation, fat accumulation, and fibrosis. In addition, loganin reduced the expression of NLRP3 inflammasome components in the liver. Our findings indicate that loganin alleviates the inflammatory symptoms associated with NASH, presumably by inhibiting NLRP3 inflammasome activation. In summary, these findings imply that loganin may be a novel nutritional and therapeutic treatment for NASH-related inflammation.

Targeting inflammasome-dependent mechanisms as an emerging pharmacological approach for osteoarthritis therapy

Arthritic diseases have attracted enormous scientific interest because of increased worldwide prevalence and represent a significant socioeconomic burden. Osteoarthritis (OA) is the most prevalent form of arthritis. It is a disorder of the diarthrodial joints, characterized by degeneration and loss of articular cartilage associated with adjacent subchondral bone changes. Chronic and unresolving inflammation has been identified as a critical factor driving joint degeneration and pain in OA. Despite numerous attempts at therapeutic intervention, no effective disease-modifying agents targeting OA inflammation are available to the patients. Inflammasomes are protein complexes known to play a critical role in the inflammatory pathology of several diseases, and their roles in OA pathogenesis have become evident over the last decade. In this sense, it is relevant to evaluate the vital role of inflammasomes as potential modulators of pathogenic features in OA. This review will provide an overview and perspectives on why understanding inflammasome activation is critical for identifying effective OA therapies. We elaborate on the contribution of extracellular mediators from the circulatory system and synovial fluid as well as intracellular activators within the synovial fibroblasts and articular chondrocytes toward invoking the inflammasome in OA. We further discuss the merits of emerging inflammasome targeting therapies and speculate on the potential strategies for inflammasome blockade for OA therapy.

Knockdown of LINC01138 protects human chondrocytes against IL-1β-induced damage by regulating the hsa-miR-1207-5p/KIAA0101 axis

INTRODUCTION

Long intergenic non-protein coding RNA 1138 (LINC01138) plays a vital role in human cancers. In this study, we aimed to investigate the effect of LINC01138 on the progression of osteoarthritis (OA) and explore its potential mechanism of action.

METHODS

The expression of LINC01138, hsa-miR-1207-5p, and KIAA0101 in OA tissues and normal tissues was analyzed using GSEA datasets and confirmed in human specimens. Human chondrocytes were treated with interleukin (IL)-1β to establish an OA cell model. Quantitative real time PCR(qRT-PCR), enzyme-linked immunosorbent assay, and western blotting analyses were performed to evaluate the role of LINC01138, hsa-miR-1207-5p, and KIAA0101 during extracellular matrix (ECM) protein degeneration and cellular inflammatory response. The target relationship was predicted using DIANA-TarBase and TargetScan. The binding effects were verified by dual-luciferase reporter assay.

RESULTS

LINC01138 expression was higher in OA tissues than in normal controls. LINC01138 levels increased in chondrocytes treated with IL-1β. Silencing of LINC01138 attenuated the IL-1β-induced decrease in Col2α1, aggrecan, and sulphated glycosaminoglycan (sGAG), and inhibited the IL-1β-induced increase in matrix metalloproteinase (MMP)-13, IL-6, and tumor necrosis factor (TNF)-α. miR-1207-5p is weakly expressed in OA tissues and cell models. The inhibition of hsa-miR-1207-5p, a target of LINC01138, attenuated the effects of LINC01138 silencing on chondrocyte ECM degeneration and inflammatory responses. Silencing KIAA0101, a target of hsa-miR-1207-5p, alleviated the effect of hsa-miR-1207-5p on chondrocyte ECM degeneration and inflammatory responses. Furthermore, silencing of KIAA0101 inhibited the JAK/STAT and Wnt signaling pathways.

CONCLUSION

Silencing LINC01138 protected chondrocytes from IL-1β-induced damage, possibly by regulating the hsa-miR-1207-5p/KIAA0101 axis.

Pyroptosis in inflammatory bone diseases: Molecular insights and targeting strategies

Inflammatory bone diseases include osteoarthritis (OA) and rheumatoid arthritis (RA), which can cause severe bone damage in a chronic inflammation state, putting tremendous pressure on the patients' families and government agencies regarding medical costs. In addition, the complexity of osteoimmunology makes research on these diseases difficult. Hence, it is urgent to determine the potential mechanisms and find effective drugs to target inflammatory bone diseases to reduce the negative effects of these diseases. Recently, pyroptosis, a gasdermin-induced necrotic cell death featuring secretion of pro-inflammatory cytokines and lysis, has become widely known. Based on the effect of pyroptosis on immunity, this process has gradually emerged as a vital component in the etiopathogenesis of inflammatory bone diseases. Herein, we review the characteristics and mechanisms of pyroptosis and then focus on its clinical significance in inflammatory bone diseases. In addition, we summarize the current research progress of drugs targeting pyroptosis to enhance the therapeutic efficacy of inflammatory bone diseases and provide new insights for future directions.

Serum periostin level is not sufficient to serve as a clinically applicable biomarker of osteoarthritis

BACKGROUND

Emerging knowledge has highlighted the role of periostin (POSTN) in osteoarthritis (OA) process; however, whether POSTN is suitable as a biomarker of OA remains unclear. This study aimed to investigate the potential value of POSTN as a biomarker of OA.

METHODS

Ten 6-month-old female Sprague-Dawley (SD) rats were used in this study. Five rats underwent ovariectomy (OVX) operation and the others were carried out sham operation. Thirty-two patients with OA and eighteen patients who had meniscus injuries or ligament injuries but with intact articular cartilages were recruited in this study from January to July 2019 at the Peking University International Hospital. We first detected the expression of POSTN in the cartilage of OVX induced OA rats and different compartments of the knee joint in patients with OA using immunohistochemistry. Besides, serum POSTN levels in patients with or without OA were examined using enzyme-linked immunosorbent assay (ELISA). The associations among serum POSTN levels, clinical symptoms, and radiological severity were assessed according to the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores and, Kellgren-Lawrence (KL) grading, respectively. Finally, multivariable cumulative link models were established to evaluate the validity of serum POSTN level as a predictor of knee OA.

RESULTS

The significantly higher POSTN expression was found in OVX-OA rats than Sham rats, while, the expression of POSTN was significantly higher in the torn cartilage of patients with OA. However, the serum POSTN level did not differ significantly between patients with and without OA. Additionally, we found no remarkable associations between serum POSTN level and WOMAC scores and KL grading. Subsequent analysis revealed that serum POSTN was not a significant predictor of OA.

CONCLUSION

Thus, although POSTN may be involved OA process and local POSTN is valuable in disease diagnosis and distinguishing of the severity of disease, its serum level is not sufficient to serve as a candidate biomarker of OA given the current analysis technology.

Tolerogenic nanoparticles induce type II collagen-specific regulatory T cells and ameliorate osteoarthritis

Local inflammation in the joint is considered to contribute to osteoarthritis (OA) progression. Here, we describe an immunomodulating nanoparticle for OA treatment. Intradermal injection of lipid nanoparticles (LNPs) loaded with type II collagen (Col II) and rapamycin (LNP-Col II-R) into OA mice effectively induced Col II-specific anti-inflammatory regulatory T cells, substantially increased anti-inflammatory cytokine expression, and reduced inflammatory immune cells and proinflammatory cytokine expression in the joints. Consequently, LNP-Col II-R injection inhibited chondrocyte apoptosis and cartilage matrix degradation and relieved pain, while injection of LNPs loaded with a control peptide and rapamycin did not induce these events. Adoptive transfer of CD4⁺CD25⁺ T cells isolated from LNP-Col II-R-injected mice suggested that T_regs induced by LNP-Col II-R injection were likely responsible for the therapeutic effects. Collectively, this study suggests nanoparticle-mediated immunomodulation in the joint as a simple and effective treatment for OA.

Emerging pharmaceutical therapeutics and delivery technologies for osteoarthritis therapy

Osteoarthritis (OA) is one of the most common joint degenerative diseases in the world. At present, the management of OA depends on the lifestyle modification and joint replacement surgery, with the lifespan of prosthesis quite limited yet. Effective drug treatment of OA is essential. However, the current drugs, such as the non-steroidal anti-inflammatory drugs and acetaminophen, as well as glucosamine, chondroitin sulfate, hyaluronic acid, are accompanied by obvious side effects, with the therapeutic efficacy to be enhanced. Recently, novel reagents such as IL-1 antagonists and nerve growth factor inhibitors have entered clinical trials. Moreover, increasing evidence demonstrated that active ingredients of natural plants have great potential for treating OA. Meanwhile, the use of novel drug delivery strategies may overcome the shortcomings of conventional preparations and enhance the bioavailability of drugs, as well as decrease the side effects significantly. This review therefore summarizes the pathological mechanisms, management strategies, and research progress in the drug molecules including the newly identified active ingredient derived from medicinal plants for OA therapy, with the drug delivery technologies also summarized, with the expectation to provide the summary and outlook for developing the next generation of drugs and preparations for OA therapy.

Pyroptosis and Intervertebral Disc Degeneration: Mechanistic Insights and Therapeutic Implications

Low back pain (LBP) is a common problem worldwide, resulting in great patient suffering and great challenges for the social health system. Intervertebral disc (IVD) degeneration (IVDD) is widely acknowledged as one of the key causes of LBP. Accumulating evidence suggests that aberrant pyroptosis of IVD cells is involved in the pathogenesis of IVDD progression, however, the comprehensive roles of pyroptosis in IVDD have not been fully established, leaving attempts to treat IVDD with anti-pyroptosis approaches questionable. In this review, we summarize the characteristics of pyroptosis and emphasize the effects of IVD cell pyroptosis on the pathological progression of IVDD, including secretion of cytokines, nucleus pulposus cell apoptosis and autophagy, accelerated extracellular matrix degradation, annulus fibrosus rupture, cartilage endplate calcification, vascularization, sensory and sympathetic fiber neoinnervation, and infiltrating lymphatic vessels. Finally, we discuss several interventions used to treat IVDD by targeting pyroptosis. This review provides novel insights into the crucial role of IVD cell pyroptosis in IVDD pathogenesis, and could be informative for developing novel therapeutic approaches for IVDD and LBP.

α-Chaconine Facilitates Chondrocyte Pyroptosis and Nerve Ingrowth to Aggravate Osteoarthritis Progression by Activating NF-κB Signaling

BACKGROUND

With the rapid growth of the elderly population, the incidence of osteoarthritis (OA) increases annually, which has attracted extensive attention in public health. The roles of dietary intake in controlling joint disorders are perhaps one of the most frequently posed questions by OA patients, while the information about the interaction between dietary intake and OA based on scientific research is limited. α-Chaconine is the richest glycoalkaloid in eggplants such as potatoes. Previous evidence suggests that α-Chaconine is a toxic compound to nervous and digestive systems with potentially severe and fatal consequences for humans and farm animals, but its effect on OA development remains obscure.

OBJECTIVE

To determine whether α-Chaconine deteriorates OA progression through sensory innervation and chondrocyte pyroptosis via regulating nuclear factor-κB (NF-κB) signaling, providing evidence for a possible linkage between α-Chaconine and OA progression.

METHODS

We established a mouse OA model by destabilization of medial meniscus (DMM) surgery and then intra-articular injection of 20 or 100 μM α-Chaconine into the OA mice for 8 and 12 weeks. The severity of OA progression was evaluated by histological staining and radiographic analyses. The expressions of matrix metabolic indicators, Col2, Mmp3, and Mmp13, as well as pyroptosis-related proteins, Nlrp3, Caspase-1, Gsdmd, IL-1β, IL-18, were determined by immunohistochemistry. And the changes in sensory nerve ingrowth and activity of NF-κB signaling were determined by immunofluorescence.

RESULTS

We found that α-Chaconine could exacerbate mouse OA progression, resulting in subchondral sclerosis, osteophyte formation, and higher OARSI scores. Specifically, α-Chaconine could augment cartilage matrix degradation and induce chondrocyte pyroptosis and nerve ingrowth. Mechanistical analysis revealed that α-Chaconine stimulated NF-κB signaling by promoting I-κB α phosphorylation and p65 nuclear translocation.

CONCLUSION

Collectively, our findings raise the possibility that α-Chaconine intake can boost chondrocyte pyroptosis and nerve ingrowth to potentiate OA progression by activating NF-κB signaling.

Medicinal plants and their secondary metabolites in alleviating knee osteoarthritis: A systematic review

BACKGROUND

With the increasing ages of the general population, the incidence of knee osteoarthritis (KOA) is also rising, and KOA has become a major health problem worldwide. Recently, medicinal plants and their secondary metabolites have gained interest due to their activity in treating KOA. In this paper, a comprehensive systematic review of the literature was performed concerning the effects of medicinal plant extracts and natural compounds against KOA in recent years. The related molecular pathways of natural compounds against KOA were summarized, and the possible crosstalk among components in chondrocytes was discussed to propose possible solutions for the current situation of treating KOA.

PURPOSE

This review focused on the molecular mechanisms by which medicinal plants and their secondary metabolites act against KOA.

METHODS

Literature searches were performed in the PUBMED, Embase, Science Direct, and Web of Science databases for a 10-year period from 2011 to 2022 with the search terms "medicinal plants," "bioactive compounds," "natural products," "phytochemical," "knee osteoarthritis," "knee joint osteoarthritis," "knee osteoarthritis," "osteoarthritis of the knee," and "osteoarthritis of knee joint."

RESULTS

According to the results, substantial plant extracts and secondary metabolites show a positive effect in fighting KOA. Plant extracts and their secondary metabolites can affect the diagnostic and prognostic biomarkers of KOA. Natural products inhibit the expression of MMP1, MMP3, MMP19, syndecan IV, ADAMTS-4, ADAMTS-5, iNOS, COX-2, collagenases, IL-6, IL-1β, and TNF-α in vitro and in vivo and . Cytokines also upregulate the expression of collagen II and aggrecan. The main signaling pathways affected by the extracts and isolated compounds include AMPK, SIRT, NLRP3, MAPKs, PI3K/AKT, mTOR, NF-κB, WNT/β-catenin, JAK/STAT3, and NRF2, as well as the cell death modes apoptosis, autophagy, pyroptosis, and ferroptosis.

CONCLUSION

The role of secondary metabolites in different signaling pathways supplies a better understanding of their potential to develop further curative options for KOA.

Dexamethasone attenuates dry eye-induced pyroptosis by regulating the KCNQ1OT1/miR-214 cascade

Dry eye disease (DED) is an inflammatory disorder of the ocular surface seriously affecting the quality of life of patients. Topical dexamethasone (Dex) administration protects the cornea from the hyperosmotic stress (HS) induced by tears. Pyroptosis participates in the activation of epithelial inflammation during DED. However, it remains unclear whether Dex attenuates the progression of DED through pyroptosis. In this study, we aimed to investigate the effect of Dex on DED using both cell and animal models and its underlying mechanism. The inflammatory factors contained in tears were detected using a cytokine assay. The pyroptosis in DED mice and human corneal epithelial cells (HCECs) treated with hyperosmotic medium under various treatments was evaluated by immunohistochemical assays (IHC) or western blotting (WB). RNA expression was manipulated with siRNA or agomir microRNAs and measured using a polymerase chain reaction. The scratch assay was used to assess the migration rate of HCECs. Remaining corneal defects were evaluated using fluorescein staining and photographed using a digital camera. Dex could suppress the release of inflammatory factors and notably attenuate pyroptosis, KCNQ1OT1 expression, and NF-κB activation induced by HS injury in vivo and in vitro. KCNQ1OT1 upregulation could activate pyroptosis by sponging miR-214. Furthermore, KCNQ1OT1 knockdown and miR-214 overexpression reversed the effect of HS, promoted the migration of HCECs, and accelerated corneal wound healing. Dex effectively suppressed HS-induced pyroptosis through the KCNQ1OT1/miR-214/caspase-1 signaling axis by inhibiting the NF-κB activation. Our results provide a novel understanding of the mechanism of Dex as an anti-inflammatory drug in DED.

Current understanding of osteoarthritis pathogenesis and relevant new approaches

Osteoarthritis (OA) is the most common degenerative joint disease that causes painful swelling and permanent damage to the joints in the body. The molecular mechanisms of OA are currently unknown. OA is a heterogeneous disease that affects the entire joint, and multiple tissues are altered during OA development. To better understand the pathological mechanisms of OA, new approaches, methods, and techniques need to be used to understand OA pathogenesis. In this review, we first focus on the epigenetic regulation of OA, with a particular focus on DNA methylation, histone modification, and microRNA regulation, followed by a summary of several key mediators in OA-associated pain. We then introduce several innovative techniques that have been and will continue to be used in the fields of OA and OA-associated pain, such as CRISPR, scRNA sequencing, and lineage tracing. Next, we discuss the timely updates concerning cell death regulation in OA pathology, including pyroptosis, ferroptosis, and autophagy, as well as their individual roles in OA and potential molecular targets in treating OA. Finally, our review highlights new directions on the role of the synovial lymphatic system in OA. An improved understanding of OA pathogenesis will aid in the development of more specific and effective therapeutic interventions for OA.

Pyroptosis: A Novel Intervention Target in the Progression of Osteoarthritis

Osteoarthritis (OA) is one of the most common chronic joint diseases and is gradually becoming the main cause of disability and joint pain in the elderly worldwide. Pyroptosis is a regulated programmed cell death triggered by inflammasomes. It leads to cell swelling, lysis, and bioactive molecule secretion. Studies found that the damaged chondrocytes in OA joints had morphological characteristics of pyroptosis, and the cytokines associated with pyroptosis in synovial fluid increased, indicating that pyroptosis may have certain impacts on the pathological progression of OA. This review briefly summarizes the molecular mechanisms of pyroptosis and the epidemiology and pathogenesis of OA. Furthermore, we discussed the role of pyroptosis in articular cartilage and synovium during OA and reviewed the progress of pyroptosis-related molecules in the targeted therapy of OA joints, hoping to provide feasible directions for the diversified treatment of OA.

The Herbal Combination of Radix astragali, Radix angelicae sinensis, and Caulis lonicerae Regulates the Functions of Type 2 Innate Lymphocytes and Macrophages Contributing to the Resolution of Collagen-Induced Arthritis

Type 2 innate lymphocytes (ILC2s), promoting inflammation resolution, was a potential target for rheumatoid arthritis (RA) treatment. Our previous studies confirmed that R. astragali and R. angelicae sinensis could intervene in immunologic balance of T lymphocytes. C. lonicerae also have anti-inflammatory therapeutic effects. In this study, the possible molecular mechanisms of the combination of these three herbs for the functions of ILC2s and macrophages contributing to the resolution of collagen-induced arthritis (CIA) were studied. Therefore, we used R. astragali, R. angelicae sinensis, and C. lonicerae as treatment. The synovial inflammation and articular cartilage destruction were alleviated after herbal treatment. The percentages of ILC2s and Tregs increased significantly. The differentiation of Th17 cells and the secretion of IL-17 and IFN-γ significantly decreased. In addition, treatment by the combination of these three herbs could increase the level of anti-inflammatory cytokine IL-4 secreted, active the STAT6 signaling pathway, and then contribute to the transformation of M1 macrophages to M2 phenotype. The combination of the three herbs could promote inflammation resolution of synovial tissue by regulating ILC2s immune response network. The synergistic effects of three drugs were superior to the combination of R. astragali and R. angelicae sinensis or C. lonicerae alone.

LncRNA MINCR attenuates osteoarthritis progression via sponging miR-146a-5p to promote BMPR2 expression

The purposes of this study are to explore the function and regulatory mechanism of a novel lncRNA MYC-Induced Long non-coding RNA (MINCR) in osteoarthritis (OA). The expression of lncRNA MINCR, miR-146a-5p, and bone morphogenetic protein receptor 2 (BMPR2), Sry-type high-mobility-group box 9 (SOX9), collagen type II alpha 1 (COL2A1), Aggrecan, metalloproteinase with thrombospondin motifs-4 (ADAMTS-4), Matrix metalloproteinase 3 (MMP3), MMP13, COL2A1, and Aggrecan were determined using quantitative real-time PCR (qRT-PCR), western blot, immunohistochemistry (IHC) and immunofluorescence (IF) in vitro and in vivo. And distribution and expression of MINCR were examined by fluorescence in situ hybridization (FISH). Cell proliferation and apoptosis were detected by cell counting kit-8 (CCK-8) assay, 5-Ethynyl-2'-deoxyuridine (EdU) staining, Annexin V-FITC/Propidium Iodide (PI), and Terminal Deoxynucleotidyl transferase-mediated dUTP Nick-End Labeling (TUNEL) staining in vitro and in vivo. The anterior cruciate ligament transection (ACLT) rat model was constructed to analyze the MINCR/miR-146a-5p/BMPR2 axis in vivo. The cartilage degeneration was determined by pathological staining with Hematoxylin and Eosin (H&E) and Safranin O staining. The binding relationship between MINCR and miR-146a-5p, and between miR-146a-5p and BMPR2 were determined by a dual-luciferase reporter gene, RNA Immunoprecipitation (RIP) assay, and RNA-pull down assays. Here, MINCR and BMPR2 were downregulated whereas miR-146a-5p was upregulated in OA cartilage tissues compared with control as well as IL-1β-induced chondrocytes compared with normal chondrocytes. Function experiments indicated that MINCR upregulation promoted cell proliferation and inhibited apoptosis and extracellular matrix (ECM)-degeneration. We also proved the binding relationship between MINCR and miR-146a-5p, and the BMPR2 acted as a target of miR-146a-5p. Mechanism analysis using rescue experiments in vitro and in vivo, MINCR silencing reversed the effects of miR-146a-5p downregulation in OA. Overexpression of miR-146a-5p also reversed the function of BMPR2 overexpression in OA. These data indicated that MINCR prevented OA progression via targeting miR-146a-5p to promote BMPR2 expression.

HIF-1α in Osteoarthritis: From Pathogenesis to Therapeutic Implications

Osteoarthritis is a common age-related joint degenerative disease. Pain, swelling, brief morning stiffness, and functional limitations are its main characteristics. There are still no well-established strategies to cure osteoarthritis. Therefore, better clarification of mechanisms associated with the onset and progression of osteoarthritis is critical to provide a theoretical basis for the establishment of novel preventive and therapeutic strategies. Chondrocytes exist in a hypoxic environment, and HIF-1α plays a vital role in regulating hypoxic response. HIF-1α responds to cellular oxygenation decreases in tissue regulating survival and growth arrest of chondrocytes. The activation of HIF-1α could regulate autophagy and apoptosis of chondrocytes, decrease inflammatory cytokine synthesis, and regulate the chondrocyte extracellular matrix environment. Moreover, it could maintain the chondrogenic phenotype that regulates glycolysis and the mitochondrial function of osteoarthritis, resulting in a denser collagen matrix that delays cartilage degradation. Thus, HIF-1α is likely to be a crucial therapeutic target for osteoarthritis via regulating chondrocyte inflammation and metabolism. In this review, we summarize the mechanism of hypoxia in the pathogenic mechanisms of osteoarthritis, and focus on a series of therapeutic treatments targeting HIF-1α for osteoarthritis. Further clarification of the regulatory mechanisms of HIF-1α in osteoarthritis may provide more useful clues to developing novel osteoarthritis treatment strategies.

Dehydrocorydaline Accelerates Cell Proliferation and Extracellular Matrix Synthesis of TNFα-Treated Human Chondrocytes by Targeting Cox2 through JAK1-STAT3 Signaling Pathway

Osteoarthritis (OA) causes severe degeneration of the meniscus and cartilage layer in the knee and endangers joint integrity and function. In this study, we utilized tumor necrosis factor α (TNFα) to establish in vitro OA models and analyzed the effects of dehydrocorydaline (DHC) on cell proliferation and extracellular matrix (ECM) synthesis in human chondrocytes with TNFα treatment. We found that TNFα treatment significantly reduced cell proliferation and mRNA and protein expression levels of aggrecan and type II collagen, but caused an increase in mRNA and protein expression levels of type I collagen, matrix metalloproteinase 1/13 (MMP1/13), and prostaglandin-endoperoxide synthase 2 (PTGS2, also known as Cox2) in human chondrocytes. DHC significantly promoted the cell activity of normal human chondrocytes without showing cytotoxity. Moreover, 10 and 20 μM DHC clearly restored cell proliferation, inhibited mRNA and protein expression levels of type I collagen, MMP 1/13, and Cox2, and further increased those of aggrecan and type II collagen in the TNFα-treated human chondrocytes. RNA transcriptome sequencing indicated that DHC could improve TNFα-induced metabolic abnormalities and inflammation reactions and inhibit the expression of TNFα-induced inflammatory factors. Furthermore, we found that the JAK1-STAT3 signaling pathway was confirmed to be involved in the regulatory effects of DHC on cell proliferation and ECM metabolism of the TNFα-treated human chondrocytes. Lastly, to explore the effects of DHC in vivo, we established an anterior cruciate ligament transection (ACLT)-stimulated rat OA model and found that DHC administration significantly attenuated OA development, inhibited the enzymatic hydrolysis of ECM, and reduced phosphorylated JAK1 and STAT3 protein expression in vivo after ACLT for 6 weeks. These results suggest that DHC can effectively relieve OA progression, and it has a potential to be utilized for the clinical prevention and therapy of OA as a natural small molecular drug.

The preventive effect of loganin on oxidative stress-induced cellular damage in human keratinocyte HaCaT cells

Loganin is a type of iridoid glycosides isolated from Corni fructus and is known to have various pharmacological properties, but studies on its antioxidant activity are still lacking. Therefore, in this study, the preventive effect of loganin on oxidative stress-mediated cellular damage in human keratinocyte HaCaT cells was investigated. Our results show that loganin pretreatment in a non-toxic concentration range significantly improved cell survival in hydrogen peroxide (H₂O₂)-treated HaCaT cells, which was associated with inhibition of cell cycle arrest at the G2/M phase and induction of apoptosis. H₂O₂-induced DNA damage and reactive oxygen species (ROS) generation were also greatly reduced in the presence of loganin. Moreover, H₂O₂ treatment enhanced the cytoplasmic release of cytochrome c, upregulation of the Bax/Bcl-2 ratio and degradation of cleavage of poly (ADP-ribose) polymerase, whereas loganin remarkably suppressed these changes. In addition, loganin obviously attenuated H₂O₂-induced autophagy while inhibiting the increased accumulation of autophagosome proteins, including as microtubule-associated protein 1 light chain 3-II and Beclin-1, and p62, an autophagy substrate protein, in H₂O₂-treated cells. In conclusion, our current results suggests that loganin could protect HaCaT keratinocytes from H₂O₂-induced cellular injury by inhibiting mitochondrial dysfunction, autophagy and apoptosis. This finding indicates the applicability of loganin in the prevention and treatment of skin diseases caused by oxidative damage.