Metformin limits osteoarthritis development and progression through activation of AMPK signalling

Mitochondrial quality control dysfunction in osteoarthritis: Mechanisms, therapeutic strategies & future prospects

Osteoarthritis (OA) is a prevalent chronic joint disease characterized by articular cartilage degeneration, pain, and disability. Emerging evidence indicates that mitochondrial quality control dysfunction contributes to OA pathogenesis. Mitochondria are essential organelles to generate cellular energy via oxidative phosphorylation and regulate vital processes. Impaired mitochondria can negatively impact cellular metabolism and result in the generation of harmful reactive oxygen species (ROS). Dysfunction in mitochondrial quality control mechanisms has been increasingly linked to OA onset and progression. This review summarizes current knowledge on the role of mitochondrial quality control disruption in OA, highlighting disturbed mitochondrial dynamics, impaired mitochondrial biogenesis, antioxidant defenses and mitophagy. The review also discusses potential therapeutic strategies targeting mitochondrial Quality Control in OA, offering future perspectives on advancing OA therapeutic strategies.

Piezo1 activation accelerates osteoarthritis progression and the targeted therapy effect of artemisinin

INTRODUCTION

Osteoarthritis (OA) is a devastating whole-joint disease affecting a large population worldwide with no cure; its mechanism remains poorly defined. Abnormal mechanical stress is the main pathological factor of OA.

OBJECTIVES

To investigate the effects of Piezo1 activation on OA development and progression and to explore Piezo1-targeting OA treatment.

METHODS

The expression levels of Piezo1 were determined in human OA cartilage and experimental OA mice. Mice with genetic Piezo1 deletion in chondrocytes or intra-articular injection of the Piezo1 activator Yoda1 were utilized to determine the effects on DMM-induced OA progression. Effects of artemisinin (ART), a potent antimalarial drug, on Piezo1 activation, chondrocyte metabolism and OA lesions were determined.

RESULTS

Piezo1 expression was elevated in articular chondrocytes in human OA and DMM-induced mouse OA cartilage. Piezo1 deletion in chondrocytes largely attenuates DMM-induced OA-like phenotypes. In contrast, intra-articular injection of Yoda1 aggravates the knee joint OA lesions in mice. PIEZO1 activation increases, while PIEZO1 siRNA knockdown decreases, expression of RUNX2 and catabolic enzymes MMP13 and ADAMTS5 in primary human articular chondrocytes in a PI3K-AKT dependent manner. We have provided strong evidence supporting that ART is a novel and potent inhibitor of Piezo1 activation in primary OA-HACs and all cell lines examined, including human endothelial HUVEC cells, ATDC5 chondrocyte-like cells and MLO-Y4 osteocytes-like cells. Results from in vitro experiments confirmed that ART decreases the Yoda1-induced increases in the levels of OA-related genes and p-PI3K and p-AKT proteins in OA-HACs and alleviates DMM-induced OA lesions in mice.

CONCLUSIONS

We establish a critical role of Piezo1 in promoting OA development and progression and define ART as a potential OA treatment.

Repurposing drugs for the treatment of osteoarthritis

OBJECTIVE

Currently, no disease-modifying therapies for osteoarthritis (OA) exist, and attempts to identify novel cellular targets have been challenging. Risk factors for OA include advanced age, obesity, and metabolic syndrome. This creates an attractive opportunity to repurpose existing drugs that are used to treat comorbidities commonly encountered in patients with OA, if those drugs possess OA disease modifying properties.

METHODS

This narrative review incorporates findings from knee or hand OA randomized clinical trials, post-hoc clinical trial analyses, prospective cohort studies, and observational data.

RESULTS

Drugs used for the treatment of rheumatoid arthritis (methotrexate; TNFa, IL-1, and IL-6 pathway inhibitors; hydroxychloroquine), atopic/allergic disease (anti-histamines), osteoporosis (bisphosphonates and vitamin D), type 2 diabetes (metformin and GLP-1 agonists), and cardiovascular disease (atorvastatin, fish oil, and beta blockers) were reviewed for their potential benefit in OA. This review outlines the successful attributes of repurposed drugs, the challenges in repurposing drugs, and strategies for future clinical trials to support OA drug repurposing. Potential drug candidates for OA may be identified through the use of existing datasets and via collaborations with researchers in other fields to include OA endpoints in future clinical trials.

CONCLUSION

Given the association of OA with several commonly treated comorbidities, drug repurposing is an appealing approach that could provide a favorable benefit-to-risk ratio for chronic OA treatment.

Metformin prevents the onset and progression of intervertebral disc degeneration: New insights and potential mechanisms (Review)

Metformin has been the go‑to medical treatment for addressing type 2 diabetes mellitus (T2DM) as a frontline oral antidiabetic. Obesity, cancer and bone deterioration are linked to T2DM, which is considered a metabolic illness. Numerous diseases associated with T2DM, such as tumours, cardiovascular disease and bone deterioration, may be treated with metformin. Intervertebral disc degeneration (IVDD) is distinguished by degeneration of the spinal disc, accompanied by the gradual depletion of proteoglycans and water in the nucleus pulposus (NP) of the IVD, resulting in lower back pain. The therapeutic effect of metformin on IVDD has also attracted much attention. By stimulating AMP‑activated kinase, metformin could enhance autophagy and suppress cell senescence, apoptosis and inflammation, thus effectively delaying IVDD. The present review aimed to systematically explain the development of IVDD and mechanism of metformin in the treatment and prevention of IVDD to provide a reference for the clinical application of metformin as adjuvant therapy in the treatment of IVDD.

Wnt/β-catenin signaling components and mechanisms in bone formation, homeostasis, and disease

Wnts are secreted, lipid-modified proteins that bind to different receptors on the cell surface to activate canonical or non-canonical Wnt signaling pathways, which control various biological processes throughout embryonic development and adult life. Aberrant Wnt signaling pathway underlies a wide range of human disease pathogeneses. In this review, we provide an update of Wnt/β-catenin signaling components and mechanisms in bone formation, homeostasis, and diseases. The Wnt proteins, receptors, activators, inhibitors, and the crosstalk of Wnt signaling pathways with other signaling pathways are summarized and discussed. We mainly review Wnt signaling functions in bone formation, homeostasis, and related diseases, and summarize mouse models carrying genetic modifications of Wnt signaling components. Moreover, the therapeutic strategies for treating bone diseases by targeting Wnt signaling, including the extracellular molecules, cytosol components, and nuclear components of Wnt signaling are reviewed. In summary, this paper reviews our current understanding of the mechanisms by which Wnt signaling regulates bone formation, homeostasis, and the efforts targeting Wnt signaling for treating bone diseases. Finally, the paper evaluates the important questions in Wnt signaling to be further explored based on the progress of new biological analytical technologies.

Injectable porous microspheres for articular cartilage regeneration through in situ stem cell recruitment and macrophage polarization

In situ mesenchymal stem cells (MSCs) regenerative therapy holds promising potential for treating osteoarthritis. However, MSCs engraftment and intra-articular inflammation limit the therapeutic efficacy of this approach. This study introduces porous microspheres (PMs) composed of aldehyde-modified poly(lactic-co-glycolic acid), that encapsulate platelet derived growth factor-AB and kartogenin. Metformin (Met) is also incorporated onto the microsphere through a Schiff base reaction to create PMs@Met. In vitro, in vivo and ex experiments revealed that PMs@Met can be injected into the joint cavity, effectively recruiting endogenous MSCs in situ. This approach creates a favorable environment for MSCs proliferation. It also controls the intra-articular inflammatory environment by modulating the polarization of synovial macrophages, ultimately promoting cartilage repair. In summary, our study presents an innovative tissue engineering strategy for the treatment of osteoarthritis-induced articular cartilage injuries. STATEMENT OF SIGNIFICANCE: Cell therapy using autologous mesenchymal stem cells (MSCs) has potential to slow the progression of osteoarthritis (OA). Nonetheless, there are some disadvantages to adopting in situ MSCs therapy, including difficulties with MSC engraftment into cartilage-deficient regions, the effect of intra-articular inflammation on MSC therapeutic efficacy, and attaining selective chondrogenic MSC differentiation. We created injectable PLGA microspheres (PMs) that were loaded with PDGF-AB and KGN. Metformin was bonded to the surface of microspheres using a Schiff base reaction. The microspheres can recruit intra-articular MSCs and encourage their development into chondrocytes. The microspheres actively modulate the inflammatory joint environment by altering synovial macrophage polarization, thereby supporting MSCs in effective cartilage treatment. To summarize, microspheres hold great potential in the treatment of OA.

The involvement of signaling pathways in the pathogenesis of osteoarthritis: An update

Osteoarthritis (OA) is one of the most common disabling pathologies, characterized by joint pain and reduced function, significantly worsening the quality of life. Even if important progresses have been made in OA research, little is yet known about the precise cellular and molecular mechanisms underlying OA. Understanding dysregulated signaling networks and their crosstalk in OA may offer a strong opportunity for the development of combined targeted therapies. Hence, this review highlights the recent findings on the main pathways involved in OA development, including Wnt, Notch, Hedgehog, MAPK, AMPK, and JAK/STAT, providing insights on current targeted therapies in OA patients' management.

The translational potential of this article

The identification of key signaling pathways involved in OA development and the investigation of their signaling crosstalk could pave the way for more effective treatments and improved management of OA patients in the future.

Tumor-targeted nano-assemblies for energy-blocking cocktail therapy in cancer

Starvation therapy aims to "starve" tumor cells by cutting off their nutritional supply. However, due to the complex and varied energy metabolism of tumors, targeting a single nutrient supply often fails to yield significant therapeutic benefits. This study proposes a tumor energy cocktail therapy that combines metformin, an oxidative phosphorylation inhibitor, with 2-deoxy-d-glucose (2-DG), a glycolysis inhibitor, to target tumor cells. To minimize the dosage of both drugs, we have developed a drug delivery strategy that prepared metformin as a nanoderivative, denoted as MA-dots. These MA-dots not only preserve the antitumor properties of metformin but also serve as a targeted delivery platform for 2-DG, ensuring its direct reach to the tumor site. Upon reaching the acidic tumor environment, the composite disintegrates, releasing 2-DG to inhibit glycolysis by targeting hexokinase 2 (HK2), the key enzyme in glycolysis, while MA-dots inhibit mitochondrial OXPHOS. This dual action significantly reduces ATP production in tumor cells, leading to apoptosis. In human lung tumor cells, the half-maximal inhibitory concentration (IC50) of 2-DG@MA-dots was significantly lower than that of either metformin or 2-DG alone, showing a nearly 100-fold and 30-fold reduction in IC50 values to 11.78 µg mL-1, from 1159 µg mL-1 and 351.20 µg mL-1, respectively. In studies with A549 tumor-bearing mice, the combination of low-dose 2-DG and metformin did not impede tumor growth, whereas 2-DG@MA-dots markedly decreased tumor volume, with the mean final tumor volume in the combination treatment group being approximately 89 times greater than that in the 2-DG@MA-dot group. STATEMENT OF SIGNIFICANCE: Metformin is a promising antitumor agent capable of modulating mitochondrial oxidative phosphorylation to inhibit cancer growth. However, its antitumor efficacy is limited when used alone due to compensatory energy mechanisms. Hence, we introduced glycolysis inhibitor 2-deoxy-d-glucose (2-DG) to inhibit an alternative tumor energy pathway. In our study, we developed a drug delivery strategy using metformin-derived nanomedicine (MA-dots) to load 2-DG. This approach enables the co-delivery of both drugs and their synergistic effect at the tumor site, disrupting both energy pathways and introducing an innovative "energy cocktail therapy".

Cathelicidin-BF regulates the AMPK/SIRT1/NF-κB pathway to ameliorate murine osteoarthritis: In vitro and in vivo studie

Osteoarthritis (OA) is a chronic degenerative disease with a significant prevalence that causes cartilage damage and can lead to disability. The main factors contributing to the onset and progression of OA include inflammation and degeneration of the extracellular matrix. Cathelicidin-BF (BF-30), a natural peptide derived from Bungarus fasciatus venom, has shown multiple important pharmacological effects. However, the action mechanism of BF-30 in OA treatment remains to be elucidated. In this research, X-ray and Safranin O staining were employed to evaluate the imageology and histomorphology differences in the knee joints of mice in vivo. Techniques such as Western blot analysis, RT-qPCR, ELISA, and immunofluorescence staining were applied to examine gene and protein level changes in in vitro experiments. It was found that BF-30 significantly decreased inflammation and enhanced extracellular matrix metabolism. For the first time, it was demonstrated that the positive effects of BF-30 are mediated through the activation of the AMPK/SIRT1/NF-κB pathway. Moreover, when BF-30 was co-administered with Compound C, an AMPK inhibitor, the therapeutic benefits of BF-30 were reversed in both in vivo and in vitro settings. In conclusion, the findings suggest that BF-30 could be a novel therapeutic agent for OA improvement.

Metformin as adjuvant therapy in obese knee osteoarthritis patients

AIMS

This study aimed at investigating the efficacy of metformin as adjuvant therapy for obese knee osteoarthritis (OA) patients, considering its anti-inflammatory and cartilage-protective effects.

PATIENTS AND METHODS

In this randomized, double-blind, placebo-controlled study, 50 obese knee OA patients were assigned randomly to two groups, the metformin group (n = 25) which was treated with metformin 500 mg orally BID plus celecoxib 200 mg orally once daily, and the placebo group (n = 25) which was treated with placebo tablets BID plus celecoxib 200 mg orally once daily for 12 weeks. Cartilage Oligomeric Matrix Protein (COMP), C-terminal cross-linked telopeptide of type I collagen (CTX-1), and Interleukin 1-beta (IL-1β) serum levels were measured, while Western Ontario and McMaster Universities Arthritis Index (WOMAC) score assessed knee pain, stiffness, and physical function at baseline and after 12 weeks.

RESULTS

Following a 12-week treatment, the metformin group exhibited significantly reduced levels of COMP, CTX-1, and IL-1β in the serum compared to the placebo group (p = 0.0081, p = 0.0106, and p = 0.0223, respectively). Furthermore, metformin group produced significant improvements in WOMAC total scale (p < 0.0001), specifically in knee pain, stiffness, and physical function compared to placebo group (p < 0.0001, p < 0.0001, and p < 0.0001, respectively).

CONCLUSION

Metformin as an adjuvant therapy in obese knee OA patients may have beneficial effects on cartilage degradation and inflammation, as evidenced by the significant decreases in serum COMP, CTX-1, and IL-1β levels. Additionally, metformin may improve clinical outcomes, as shown by the significant improvements in WOMAC scores.

CLINICALTRIALS

GOV ID

NCT05638893/Registered December 6, 2022 - Retrospectively.

Acacetin targets STING to alleviate the destabilization of the medial meniscus-induced osteoarthritis in mice

Osteoarthritis (OA) is a common joint disorder affecting about 7% of the global population, primarily characterized by the gradual loss of articular cartilage. This degeneration results from local inflammation, matrix depletion, and direct cartilage damage. A critical element in this process is the activation of the stimulator of the interferon genes (STING) pathway. Emerging evidence highlights its potential as a therapeutic target, with natural products showing promise as inhibitors. Our study centers on Acacetin, a basic unit of polyketides known for its anti-inflammatory properties. Prior research has highlighted its potential interaction with STING based on the structure. Thus, this study aimed to assess the effectiveness of Acacetin as a STING inhibitor and its protective role against OA. In vitro experiments showed that Acacetin pretreatment not only mitigated interleukin-1β (IL-1β)-induced cytotoxicity but also decreased the inflammatory response and degeneration in chondrocytes stimulated IL-1β. In vivo studies revealed that Acacetin administration significantly reduced articular cartilage destruction, abnormal bone remodeling, and osteophyte formation in a model of OA induced by destabilization of the medial meniscus (DMM). Mechanistically, Acacetin was found to interact directly with STING, and inhibit IL-1β-induced activation of STING, along with the subsequent phosphorylation of the TBK1/NF-κB pathway in chondrocytes. In conclusion, our findings establish Acacetin as an effective inhibitor of STING that protects chondrocytes from IL-1β-induced damage and slows the progression of OA in mice.

Pip5k1γ promotes anabolism of nucleus pulposus cells and intervertebral disc homeostasis by activating CaMKII-Ampk pathway in aged mice

Degenerative disc disease (DDD) represents a significant global health challenge, yet its underlying molecular mechanisms remain elusive. This study aimed to investigate the role of type 1 phosphatidylinositol 4-phosphate 5-kinase (Pip5k1) in intervertebral disc (IVD) homeostasis and disease. All three Pip5k1 isoforms, namely Pip5k1α, Pip5k1β, and Pip5k1γ, were detectable in mouse and human IVD tissues, with Pip5k1γ displaying a highest expression in nucleus pulposus (NP) cells. The expression of Pip5k1γ was significantly down-regulated in the NP cells of aged mice and patients with severe DDD. To determine whether Pip5k1γ expression is required for disc homeostasis, we generated a Pip5k1γfl/fl; AggrecanCreERT2 mouse model for the conditional knockout of the Pip5k1γ gene in aggrecan-expressing IVD cells. Our findings revealed that the conditional deletion of Pip5k1γ did not affect the disc structure or cellular composition in 5-month-old adult mice. However, in aged (15-month-old) mice, this deletion led to several severe degenerative disc defects, including decreased NP cellularity, spontaneous fibrosis and cleft formation, and a loss of the boundary between NP and annulus fibrosus. At the molecular level, the absence of Pip5k1γ reduced the anabolism of NP cells without markedly affecting their catabolic or anti-catabolic activities. Moreover, the loss of Pip5k1γ significantly dampened the activation of the protective Ampk pathway in NP cells, thereby accelerating NP cell senescence. Notably, Pip5k1γ deficiency blunted the effectiveness of metformin, a potent Ampk activator, in activating the Ampk pathway and mitigating lumbar spine instability (LSI)-induced disc lesions in mice. Overall, our study unveils a novel role for Pip5k1γ in promoting anabolism and maintaining disc homeostasis, suggesting it as a potential therapeutic target for DDD.

Animal Models of Osteoarthritis: Updated Models and Outcome Measures 2016-2023

Purpose

Osteoarthritis (OA) is a global musculoskeletal disorder that affects primarily the knee and hip joints without any FDA-approved disease-modifying therapies. Animal models are essential research tools in developing therapies for OA; many animal studies have provided data for the initiation of human clinical trials. Despite this, there is still a need for strategies to recapitulate the human experience using animal models to better develop treatments and understand pathogenesis. Since our last review on animal models of osteoarthritis in 2016, there have been exciting updates in OA research and models. The main purpose of this review is to update the latest animal models and key features of studies in OA research.

Method

We used our existing classification method and screened articles in PubMed and bibliographic search for animal OA models between 2016 and 2023. Relevant and high-cited articles were chosen for inclusion in this narrative review.

Results

Recent studies were analyzed and classified. We also identified ex vivo models as an area of ongoing research. Each animal model offers its own benefit in the study of OA and there are a full range of outcome measures that can be assessed. Despite the vast number of models, each has its drawbacks that have limited translating approved therapies for human use.

Conclusion

Depending on the outcome measures and objective of the study, researchers should pick the best model for their work. There have been several exciting studies since 2016 that have taken advantage of regenerative engineering techniques to develop therapies and better understand OA.

Lay Summary

Osteoarthritis (OA) is a chronic debilitating disease without any cure that affects mostly the knee and hip joints and often results in surgical joint replacement. Cartilage protects the joint from mechanical forces and degrades with age or in response to injury. The many contributing causes of OA are still being investigated, and animals are used for preclinical research and to test potential new treatments. A single consensus OA animal model for preclinical studies is non-existent. In this article, we review the many animal models for OA and provide a much-needed update on studies and model development since 2016.

Gene expression and immune infiltration analysis comparing lesioned and preserved subchondral bone in osteoarthritis

Background

Osteoarthritis (OA) is a degenerative disease requiring additional research. This study compared gene expression and immune infiltration between lesioned and preserved subchondral bone. The results were validated using multiple tissue datasets and experiments.

Methods

Differentially expressed genes (DEGs) between the lesioned and preserved tibial plateaus of OA patients were identified in the GSE51588 dataset. Moreover, functional annotation and protein-protein interaction (PPI) network analyses were performed on the lesioned and preserved sides to explore potential therapeutic targets in OA subchondral bones. In addition, multiple tissues were used to screen coexpressed genes, and the expression levels of identified candidate DEGs in OA were measured by quantitative real-time polymerase chain reaction. Finally, an immune infiltration analysis was conducted.

Results

A total of 1,010 DEGs were identified, 423 upregulated and 587 downregulated. The biological process (BP) terms enriched in the upregulated genes included "skeletal system development", "sister chromatid cohesion", and "ossification". Pathways were enriched in "Wnt signaling pathway" and "proteoglycans in cancer". The BP terms enriched in the downregulated genes included "inflammatory response", "xenobiotic metabolic process", and "positive regulation of inflammatory response". The enriched pathways included "neuroactive ligand-receptor interaction" and "AMP-activated protein kinase signaling". JUN, tumor necrosis factor α, and interleukin-1β were the hub genes in the PPI network. Collagen XI A1 and leucine-rich repeat-containing 15 were screened from multiple datasets and experimentally validated. Immune infiltration analyses showed fewer infiltrating adipocytes and endothelial cells in the lesioned versus preserved samples.

Conclusion

Our findings provide valuable information for future studies on the pathogenic mechanism of OA and potential therapeutic and diagnostic targets.

A sono-responsive antibacterial nanosystem co-loaded with metformin and bone morphogenetic protein-2 for mitigation of inflammation and bone loss in experimental peri-implantitis

Background

Dental implants have become an increasingly popular option for replacing missing teeth, and the prevalence of peri-implantitis has also increased, which is expected to become a public health problem worldwide and cause high economic and health burdens. This scenario highlights the need for new therapeutic options to treat peri-implantitis.

Methods

In this study, we proposed a novel sono-responsive antibacterial nanosystem co-loaded with metformin (Met) and bone morphogenetic protein-2 (BMP-2) to promote efficacy in treating peri-implantitis. We introduced the zeolitic imidazolate framework-8 (ZIF-8) as a carrier for hematoporphyrin monomethyl ether (HMME) to enhance the antibacterial effect of sonodynamic antibacterial therapy and tested its reactive oxygen species (ROS) production efficiency and bactericidal effect in vitro. Afterward, HMME-loaded ZIF-8, BMP-2-loaded polylactic acid-glycolic acid (PLGA), and Met were incorporated into gelatin methacryloyl (GelMA) hydrogels to form HMME@ZIF-8/Met/BMP-2@PLGA/GelMA composite hydrogels, and the biocompatibility of which was determined in vitro and in vivo. A bacterial-induced peri-implantitis model in the maxilla of rats was established to detect the effects of the composite hydrogels with adjunctive use of ultrasound on regulating inflammation and promoting bone tissue repair in vivo.

Results

The results indicated that HMME@ZIF-8 with ultrasound stimulation demonstrated more better ROS production efficiency and antimicrobial efficacy. The composite hydrogels had good biocompatibility. Ultrasound-assisted application of the composite hydrogels reduced the release of the inflammatory factors IL-6 and TNF-α and reduced bone loss around the implant in rats with bacterial-induced peri-implantitis.

Conclusion

Our observations suggest that HMME@ZIF-8 may be a new good sonosensitizer material for sonodynamic antibacterial therapy. The use of HMME@ZIF-8/Met/BMP-2@PLGA/GelMA composite hydrogels in combination with ultrasound can provide a novel option for treating peri-implantitis in the future.

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.

Osteoarthritis: Insights into Diagnosis, Pathophysiology, Therapeutic Avenues, and the Potential of Natural Extracts

Osteoarthritis (OA) stands as a prevalent and progressively debilitating clinical condition globally, impacting joint structures and leading to their gradual deterioration through inflammatory mechanisms. While both non-modifiable and modifiable factors contribute to its onset, numerous aspects of OA pathophysiology remain elusive despite considerable research strides. Presently, diagnosis heavily relies on clinician expertise and meticulous differential diagnosis to exclude other joint-affecting conditions. Therapeutic approaches for OA predominantly focus on patient education for self-management alongside tailored exercise regimens, often complemented by various pharmacological interventions primarily targeting pain alleviation. However, pharmacological treatments typically exhibit short-term efficacy and local and/or systemic side effects, with prosthetic surgery being the ultimate resolution in severe cases. Thus, exploring the potential integration or substitution of conventional drug therapies with natural compounds and extracts emerges as a promising frontier in enhancing OA management. These alternatives offer improved safety profiles and possess the potential to target specific dysregulated pathways implicated in OA pathogenesis, thereby presenting a holistic approach to address the condition's complexities.

Collagen type X expression and chondrocyte hypertrophic differentiation during OA and OS development

Chondrocyte hypertrophy and the expression of its specific marker, the collagen type X gene (COL10A1), constitute key terminal differentiation stages during endochondral ossification in long bone development. Mutations in the COL10A1 gene are known to cause schmid type metaphyseal chondrodysplasia (SMCD) and spondyloepiphyseal dyschondrodysplasia (SMD). Moreover, abnormal COL10A1 expression and aberrant chondrocyte hypertrophy are strongly correlated with skeletal diseases, notably osteoarthritis (OA) and osteosarcoma (OS). Throughout the progression of OA, articular chondrocytes undergo substantial changes in gene expression and phenotype, including a transition to a hypertrophic-like state characterized by the expression of collagen type X, matrix metalloproteinase-13, and alkaline phosphatase. This state is similar to the process of endochondral ossification during cartilage development. OS, the most common pediatric bone cancer, exhibits characteristics of abnormal bone formation alongside the presence of tumor tissue containing cartilaginous components. This observation suggests a potential role for chondrogenesis in the development of OS. A deeper understanding of the shifts in collagen X expression and chondrocyte hypertrophy phenotypes in OA or OS may offer novel insights into their pathogenesis, thereby paving the way for potential therapeutic interventions. This review systematically summarizes the findings from multiple OA models (e.g., transgenic, surgically-induced, mechanically-loaded, and chemically-induced OA models), with a particular focus on their chondrogenic and/or hypertrophic phenotypes and possible signaling pathways. The OS phenotypes and pathogenesis in relation to chondrogenesis, collagen X expression, chondrocyte (hypertrophic) differentiation, and their regulatory mechanisms were also discussed. Together, this review provides novel insights into OA and OS therapeutics, possibly by intervening the process of abnormal endochondral-like pathway with altered collagen type X expression.

FTH1 protects against osteoarthritis by MAPK pathway inhibition of extracellular matrix degradation

OBJECTIVE

Ferritin heavy chain 1 (FTH1) is an important subunit of ferro-storing proteins and is indispensable for iron metabolism. Though it has been extensively studied in numerous organs and diseases, the relationship between FTH1 and osteoarthritis (OA) is unclear.

DESIGN

Primary murine chondrocytes and cartilage explants were treated with FTH1 siRNA for 72 h. Mice were injected with adenovirus expressing FTH1 after destabilized medial meniscus (DMM) surgery. These approaches were used to determine the effect of FTH1 expression on the pathophysiology of OA.

RESULTS

FTH1 expression was down regulated in OA patients and mice after DMM surgery. Knock down of FTH1 induced articular cartilage damage and extracellular matrix degradation in cartilage explants. Further, over expression of FTH1 reduced the susceptibility of chondrocytes to ferroptosis and reversed decrements in SOX9 and aggrecan after DMM surgery. Moreover, FTH1 relieved OA by inhibition of the chondrocyte MAPK pathway.

CONCLUSION

This study found FTH1 to play an essential role in extracellular matrix degradation, ferroptosis, and chondrocytes senescence during OA progression. Further, injection of adenovirus expressing FTH1 may be a potential strategy for OA prevention and therapy.

Near Infrared Responsive Gold Nanorods Attenuate Osteoarthritis Progression by Targeting TRPV1

Osteoarthritis (OA) is the most common degenerative joint disease worldwide, with the main pathological manifestation of articular cartilage degeneration. It have been investigated that pharmacological activation of transient receptor potential vanilloid 1 (TRPV1) significantly alleviated cartilage degeneration by abolishing chondrocyte ferroptosis. In this work, in view of the thermal activated feature of TRPV1, Citrate-stabilized gold nanorods (Cit-AuNRs) is conjugated to TRPV1 monoclonal antibody (Cit-AuNRs@Anti-TRPV1) as a photothermal switch for TRPV1 activation in chondrocytes under near infrared (NIR) irradiation. The conjugation of TRPV1 monoclonal antibody barely affect the morphology and physicochemical properties of Cit-AuNRs. Under NIR irradiation, Cit-AuNRs@Anti-TRPV1 exhibited good biocompatibility and flexible photothermal responsiveness. Intra-articular injection of Cit-AuNRs@Anti-TRPV1 followed by NIR irradiation significantly activated TRPV1 and attenuated cartilage degradation by suppressing chondrocytes ferroptosis. The osteophyte formation and subchondral bone sclerosis are remarkably alleviated by NIR-inspired Cit-AuNRs@Anti-TRPV1. Furthermore, the activation of TRPV1 by Cit-AuNRs@Anti-TRPV1 evidently improved physical activities and alleviated pain of destabilization of the medial meniscus (DMM)-induced OA mice. The study reveals Cit-AuNRs@Anti-TRPV1 under NIR irradiation protects chondrocytes from ferroptosis and attenuates OA progression, providing a potential therapeutic strategy for the treatment of OA.

Aging and the emerging role of cellular senescence in osteoarthritis

OBJECTIVE

The correlation between age and incidence of osteoarthritis (OA) is well known but the causal mechanisms involved are not completely understood. This narrative review summarizes selected key findings from the past 30 years that have elucidated key aspects of the relationship between aging and OA.

METHODS

The peer-reviewed English language literature was searched on PubMed using keywords including senescence, aging, cartilage, and osteoarthritis, for original studies and reviews published from 1993 to 2023 with a major focus on more recent studies. Manuscripts most relevant to aging and OA that examined one or more of the hallmarks of aging were selected for further review.

RESULTS

All proposed hallmarks of aging have been observed in articular cartilage and some have also been described in other joint tissues. Hallmarks include genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, disabled macroautophagy, chronic inflammation, and dysbiosis. There is evidence that these age-related changes contribute to the development of OA in part by promoting cellular senescence. Senescence may therefore serve as a downstream mediator that connects numerous aging hallmarks to OA, likely through the senescence-associated secretory phenotype that is characterized by increased production of proinflammatory cytokines and matrix metalloproteinases.

CONCLUSIONS

Progress over the past 30 years has provided the foundation for emerging therapies, such as senolytics and senomorphics, that hold promise for OA disease modification. Mechanistic studies utilizing physiologically-aged animals and cadaveric human joint tissues will be important for continued progress.

Apoptotic body-inspired nanotherapeutics efficiently attenuate osteoarthritis by targeting BRD4-regulated synovial macrophage polarization

Bromodomain-containing protein 4 (BRD4) is the most well-studied BET protein that is important for the innate immune response. We recently revealed that targeting BRD4 triggers apoptosis in tumor-associated macrophages, but its role in synovial macrophages and joint inflammation is largely unknown. Herein, we demonstrated that BRD4 was highly expressed in the iNOS-positive M1 macrophages in the human and mouse osteoarthritis (OA) synovium, and conditional knockout of BRD4 in the myeloid lineage using Lyz2-cre; BRD4flox/flox mice significantly abolished anterior cruciate ligament transection (ACLT)-induced M1 macrophage accumulation and synovial inflammation. Accordingly, we successfully constructed apoptotic body-inspired phosphatidylserine-containing nanoliposomes (PSLs) loaded with the BRD4 inhibitor JQ1 to regulate inflammatory macrophages. JQ1-loaded PSLs (JQ1@PSLs) exhibited a higher cellular uptake by macrophages than fibroblast-like synoviocytes (FLSs) in vitro and in vivo, as well as the reduction in proinflammatory M1 macrophage polarization. Intra-articular injections of JQ1@PSLs showed prolonged retention within the joint, and remarkably reduced synovial inflammation and joint pain via suppressing M1 polarization accompanied by reduced TRPA1 expression by targeted inhibition of BRD4 in the macrophages, thus attenuating cartilage degradation during OA development. The results show that BRD4-inhibiting JQ1@PSLs can targeted-modulate macrophage polarization, which opens a new avenue for efficient OA therapy via a "Trojan horse".

The role of targeting glucose metabolism in chondrocytes in the pathogenesis and therapeutic mechanisms of osteoarthritis: a narrative review

Osteoarthritis (OA) is a common degenerative joint disease that can affect almost any joint, mainly resulting in joint dysfunction and pain. Worldwide, OA affects more than 240 million people and is one of the leading causes of activity limitation in adults. However, the pathogenesis of OA remains elusive, resulting in the lack of well-established clinical treatment strategies. Recently, energy metabolism alterations have provided new insights into the pathogenesis of OA. Accumulating evidence indicates that glucose metabolism plays a key role in maintaining cartilage homeostasis. Disorders of glucose metabolism can lead to chondrocyte hypertrophy and extracellular matrix degradation, and promote the occurrence and development of OA. This article systematically summarizes the regulatory effects of different enzymes and factors related to glucose metabolism in OA, as well as the mechanism and potential of various substances in the treatment of OA by affecting glucose metabolism. This provides a theoretical basis for a better understanding of the mechanism of OA progression and the development of optimal prevention and treatment strategies.

Therapeutic potential of hydrogen sulfide in osteoarthritis development

The pathological mechanisms and treatments of osteoarthritis (OA) are critical topics in medical research. This paper reviews the regulatory mechanisms of hydrogen sulfide (H2S) in OA and the therapeutic potential of H2S donors. The review highlights the importance of changes in the endogenous H2S pathway in OA development and systematically elaborates on the role of H2S as a third gaseous transmitter that regulates inflammation, oxidative stress, and pain associated with OA. It also explains how H2S can lessen bone and joint inflammation by inhibiting leukocyte adhesion and migration, reducing pro-inflammatory mediators, and impeding the activation of key inflammatory pathways such as nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK). Additionally, H2S is shown to mitigate mitochondrial dysfunction and endoplasmic reticulum stress, and to modulate Nrf2, NF-κB, PI3K/Akt, and MAPK pathways, thereby decreasing oxidative stress-induced chondrocyte apoptosis. Moreover, H2S alleviates bone and joint pain through the activation of Kv7, K-ATP, and Nrf2/HO-1-NQO1 pathways. Recent developments have produced a variety of H2S donors, including sustained-release H2S donors, natural H2S donors, and synthetic H2S donors. Understanding the role of H2S in OA can lead to the discovery of new therapeutic targets, while innovative H2S donors offer promising new treatments for patients with OA.

Carveol alleviates osteoarthritis progression by acting on synovial macrophage polarization transformation: An in vitro and in vivo study

Osteoarthritis (OA) is a heterogeneous disease that affects the entire joint. Its pathogenesis involves hypertrophy and hyperplasia of synovial cells and polarization infiltration of macrophages, in which macrophages, as a potential target, can delay the progression of the disease by improving the immune microenvironment in OA. To investigate the role and regulatory mechanism of Carveol in cartilage and synovial macrophage reprogramming and crosstalk during the development of OA. RAW264.7 mouse macrophage cell line was mainly used to stimulate macrophages to polarization towards M1 and M2 by LPS, IL4+IL13, respectively. Different concentrations of Carveol were given to intervene, and macrophage culture medium was collected to intervene mouse C57BL6J chondrocytes. ROS assay kit, western blotting, cellular immunofluorescence, scanning microscope and section histology were used to evaluate the effect of Carveol on anti-M1-polarization, M2-polarization promotion and cartilage protection. The mouse destabilization of medial meniscus (DMM) model was observed by micro-CT scan and histology. We found that CA could inhibit the increase of macrophage inflammation level under the intervention of LPS and promote the production of M2 anti-inflammatory substances under the intervention of IL-4+IL13. In addition, Carveol activated NRF2/HO-1/NQO1 pathway and enhanced ROS clearance in chondrocytes under the intervention of macrophage culture medium. The phosphorylation of I-κBα is inhibited, which further reduces the phosphorylation of P65 downstream of nuclear factor-κB (NF-κB) signaling pathway. In addition, Carveol inhibits mitogen activated protein kinase (MAPK) signaling molecules P-JNK, P-ERK and P-P38, and inhibits the production of inflammatory mediators. In vivo, Carveol can reduce osteophytes and bone spurs induced by DMM, reduce hypertrophy of synovial cells, reduce infiltration of macrophages, inhibit subchondral bone destruction, and reduce articular cartilage erosion. Our study suggests that synovial macrophages are potential targets for OA treatment, and Carveol is an effective candidate for OA treatment.

Metformin for knee osteoarthritis with obesity: study protocol for a randomised, double-blind, placebo-controlled trial

INTRODUCTION

Over half of the populations with knee osteoarthritis (OA) have obesity. These individuals have many other shared metabolic risk factors. Metformin is a safe, inexpensive, well-tolerated drug that has pleiotropic effects, including structural protection, anti-inflammatory and analgesic effects in OA, specifically the knee. The aim of this randomised, double-blind, placebo-controlled trial is to determine whether metformin reduces knee pain over 6 months in individuals with symptomatic knee OA who are overweight or obese.

METHODS AND ANALYSIS

One hundred and two participants with symptomatic knee OA and overweight or obesity will be recruited from the community in Melbourne, Australia, and randomly allocated in a 1:1 ratio to receive either metformin 2 g or identical placebo daily for 6 months. The primary outcome is reduction of knee pain [assessed by 100 mm Visual Analogue Scale (VAS)] at 6 months. The secondary outcomes are OMERACT-OARSI (Outcome Measures in Rheumatology-Osteoarthritis Research Society International) responder criteria [Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain, function and participant's global assessment (VAS)] at 6 months; change in knee pain, stiffness, function using WOMAC at 6 months and quality of life at 6 months. Adverse events will be recorded. The primary analysis will be by intention to treat, including all participants in their randomised groups.

ETHICS AND DISSEMINATION

Ethics approval has been obtained from the Alfred Hospital Ethics Committee (708/20) and Monash University Human Research Ethics Committee (28498). Written informed consent will be obtained from all the participants. The findings will be disseminated through peer-review publications and conference presentations.

TRIAL REGISTRATION NUMBER

ACTRN12621000710820 .

New insight of the pathogenesis in osteoarthritis: the intricate interplay of ferroptosis and autophagy mediated by mitophagy/chaperone-mediated autophagy

Ferroptosis, characterized by iron accumulation and lipid peroxidation, is a form of iron-driven cell death. Mitophagy is a type of selective autophagy, where degradation of damaged mitochondria is the key mechanism for maintaining mitochondrial homeostasis. Additionally, Chaperone-mediated autophagy (CMA) is a biological process that transports individual cytoplasmic proteins to lysosomes for degradation through companion molecules such as heat shock proteins. Research has demonstrated the involvement of ferroptosis, mitophagy, and CMA in the pathological progression of Osteoarthritis (OA). Furthermore, research has indicated a significant correlation between alterations in the expression of reactive oxygen species (ROS), adenosine monophosphate (AMP)-activated protein kinase (AMPK), and hypoxia-inducible factors (HIFs) and the occurrence of OA, particularly in relation to ferroptosis and mitophagy. In light of these findings, our study aims to assess the regulatory functions of ferroptosis and mitophagy/CMA in the pathogenesis of OA. Additionally, we propose a mechanism of crosstalk between ferroptosis and mitophagy, while also examining potential pharmacological interventions for targeted therapy in OA. Ultimately, our research endeavors to offer novel insights and directions for the prevention and treatment of OA.

Risk of metabolic abnormalities in osteoarthritis: a new perspective to understand its pathological mechanisms

Although aging has traditionally been viewed as the most important risk factor for osteoarthritis (OA), an increasing amount of epidemiological evidence has highlighted the association between metabolic abnormalities and OA, particularly in younger individuals. Metabolic abnormalities, such as obesity and type II diabetes, are strongly linked to OA, and they affect both weight-bearing and non-weight-bearing joints, thus suggesting that the pathogenesis of OA is more complicated than the mechanical stress induced by overweight. This review aims to explore the recent advances in research on the relationship between metabolic abnormalities and OA risk, including the impact of abnormal glucose and lipid metabolism, the potential pathogenesis and targeted therapeutic strategies.

Epigenetic modification and exosome effects on autophagy in osteoarthritis

Osteoarthritis (OA) is a degenerative disease that leads to joint pain and stiffness and is one of the leading causes of disability and pain worldwide. Autophagy is a highly conserved self-degradation process, and its abnormal function is closely related to human diseases, including OA. Abnormal autophagy regulates cell aging, matrix metalloproteinase metabolism, and reactive oxygen metabolism, which are key in the occurrence and development of OA. There is evidence that drugs directly or indirectly targeting autophagy significantly hinder the progress of OA. In addition, the occurrence and development of autophagy in OA are regulated by many factors, including epigenetic modification, exosomes, crucial autophagy molecules, and signaling pathway regulation. Autophagy, as a new therapeutic target for OA, has widely influenced the pathological mechanism of OA. However, determining how autophagy affects OA pathology and its use in the treatment and diagnosis of targets still need further research.

Calcipotriol suppresses GPX4-mediated ferroptosis in OA chondrocytes by blocking the TGF-β1 pathway

Globally, tens of millions of individuals experience osteoarthritis (OA), a degenerative joint condition for which a definitive cure is currently lacking. This condition is characterized by joint inflammation and the progressive deterioration of articular cartilage. In this study, western blotting, quantitative reverse-transcription polymerase chain reaction, and immunofluorescence analysis were performed to elucidate the molecular mechanisms by which calcipotriol alleviates chondrocyte ferroptosis. The effect of calcipotriol on reactive oxygen species and lipid peroxidation levels in chondrocytes was assessed using dihydroethidium staining and the fluorescent dye BODIPY. To replicate OA, the destabilized medial meniscus model was employed, followed by the injection of calcipotriol into the knee articular cavity. Morphological analysis was conducted through hematoxylin and eosin staining, safranin O-Fast green staining, and micro-computed tomography analysis. Immunohistochemical analysis was performed to validate the effect of calcipotriol in vivo. Our results demonstrate that the expression of SOX9, col2a1, and Aggrecan, as well as MMP13 and ADAMTS5 protein expression levels, decrease upon treatment with calcipotriol in interleukin-1β stimulated chondrocytes. Despite these promising outcomes, the exact mechanism underlying calcipotriol's therapeutic effect on OA remains uncertain. We discovered that calcipotriol inhibits chondrocyte GPX4-mediated ferroptosis by suppressing the expression of transforming growth factor-β1. Furthermore, our study established an in vivo model of OA using rats with medial meniscus instability. Our experiments on rats with OA revealed that intra-articular calcipotriol injection significantly reduces cartilage degradation caused by the disease. Our findings suggest that calcipotriol can mitigate OA by impeding GPX4-mediated ferroptosis of chondrocytes, achieved through the suppression of the TGF-β1 pathway.

Barasertib impedes chondrocyte senescence and alleviates osteoarthritis by mitigating the destabilization of heterochromatin induced by AURKB

Osteoarthritis (OA) is a common joint disease characterized by progressive cartilage loss that causes disability worldwide. The accumulation of senescent chondrocytes in aging human cartilage contributes to the high incidence of OA. Heterochromatin instability, the hallmark and driving factor of senescence, regulates the expression of the senescence-associated secretory phenotype that induces inflammation and cartilage destruction. However, the role of heterochromatin instability in OA progression remains unclear. In this work, we identified AURKB as a key senescence-associated chromatin regulator using bioinformatics methods. We found that AURKB was upregulated in OA cartilage and chondrocytes exposed to abnormal mechanical strain. Overexpression of AURKB could cause senescence and heterochromatin instability. Furthermore, the AURKB inhibitor Barasertib reversed senescence and heterochromatin instability in chondrocytes and alleviated OA in a rat model. Mechanistically, abnormal mechanical strain increased AURKB levels through the Piezo1/Ca2+ signaling axis. Blocking Piezo1/Ca2+ signaling by short interfering RNA against Piezo1 and Ca2+ chelator BAPTA could reduce the expression of AURKB and alleviate senescence in chondrocytes exposed to abnormal mechanical strain. In conclusion, our data confirmed that abnormal mechanical strain increases the expression of AURKB by activating the Piezo1/Ca2+ signaling axis, leading to destabilized heterochromatin and senescence in chondrocytes, whereas Barasertib consolidates heterochromatin, counteracts senescence and alleviates OA.

The roles of the Hippo-YAP signalling pathway in Cartilage and Osteoarthritis

Osteoarthritis (OA) is an age-related disease, characterized by cartilage degeneration. The pathogenesis of OA is complicated and the current therapeutic approaches for OA are limited. Cartilage, an integral part of the skeletal system composed of chondrocytes, is essential for skeletal development, tissue patterning, and maintaining the normal activity of joints. The development, homeostasis and degeneration of cartilage are tightly associated with OA. Over the past decade, accumulating evidence indicates that Hippo/YAP is a vital biochemical signalling pathway that strictly governs tissue development and homeostasis. The joint tissues, especially for cartilage, are sensitive to changes of Hippo/YAP signalling. In this review, we summarize the role of Hippo/YAP signalling in cartilage and discuss its involvement in OA progression from points of cartilage degradation, subchondral bone remodeling, and synovial alteration. We also highlight the potential therapeutic implications of Hippo/YAP signalling and further discuss current limitations and controversy on Hippo/YAP-based application for OA treatment.

miR-204 ameliorates osteoarthritis pain by inhibiting SP1-LRP1 signaling and blocking neuro-cartilage interaction

Osteoarthritis (OA) is a painful degenerative joint disease and is the leading cause of chronic disability among elderly individuals. To improve the quality of life for patients with OA, the primary goal for OA treatment is to relieve the pain. During OA progression, nerve ingrowth was observed in synovial tissue and articular cartilage. These abnormal neonatal nerves act as nociceptors to detect OA pain signals. The molecular mechanisms for transmitting OA pain in the joint tissues to the central nerve system (CNS) is currently unknown. MicroRNA miR-204 has been demonstrated to maintain the homeostasis of joint tissues and have chondro-protective effect on OA pathogenesis. However, the role of miR-204 in OA pain has not been determined. In this study, we investigated interactions between chondrocytes and neural cells and evaluated the effect and mechanism of miR-204 delivered by exosome in the treatment of OA pain in an experimental OA mouse model. Our findings demonstrated that miR-204 could protect OA pain by inhibition of SP1- LDL Receptor Related Protein 1 (LRP1) signaling and blocking neuro-cartilage interaction in the joint. Our studies defined novel molecular targets for the treatment of OA pain.

Association of Metformin Use with Iron Deficiency Anemia in Urban Chinese Patients with Type 2 Diabetes

BACKGROUND

Previous evidence yielded contradictory findings on the relationship between metformin and anemia. This study aims to assess whether metformin use is associated with iron-deficiency anemia (IDA) risk in patients with type 2 diabetes (T2D) in Beijing, China.

METHODS

Overall, 60,327 newly diagnosed T2D patients were included based on a historical cohort study design. The information pertaining to these patients was gathered from the Beijing Medical Claim Data for Employees Database. These patients were then categorized into the metformin and non-metformin groups and matched on a 1:1 propensity score based on their initial antidiabetic prescription. The Cox proportional hazards models were utilized to calculate the incidences and the hazard ratios (HRs).

RESULTS

The study enrolled 27,960 patients with type 2 diabetes, with 13,980 patients in each of the initial glucose-lowering prescription groups: metformin and non-metformin. During a median follow-up period of 4.84 years, 4832 patients developed IDA. The incidence of IDA was significantly lower in the metformin group (26.08/1000 person-years) than in the non-metformin group (43.20/1000 person-years). Among the three groups divided by the proportion of days covered by metformin, we found a negative correlation between the proportion of days covered by metformin and the risk of IDA. The risk of IDA in patients with a proportion of days covered by metformin of <20%, 20-79%, and ≥80% was 0.43 (0.38, 0.48), 0.37 (0.34, 0.42), and 0.91 (0.85, 0.98), respectively, compared to the non-metformin group. We also performed subgroup analyses and sensitivity analyses: the incidence of IDA in the metformin group was lower than that in the non-metformin group in all subgroups, and the protective effect was more significant in subgroups of patients aged ≥65, with Charlson comorbidity index (CCI) ≥2, and with gastric acid inhibitor use.

CONCLUSIONS

In Chinese patients with T2DM, metformin treatment was associated with a decreased risk of IDA admission, and this risk responded positively to the proportion of days covered by metformin. These findings suggest that metformin may have a pleiotropic effect on IDA in patients with type 2 diabetes. Our study has important clinical implications for the management of patients with diabetes and other conditions that increase the risk of IDA.

[Research progress on the role of chondrocyte mitochondrial homeostasis imbalance in the pathogenesis of osteoarthritis]

Objective

To summarize the role of chondrocyte mitochondrial homeostasis imbalance in the pathogenesis of osteoarthritis (OA) and analyze its application prospects.

Methods

The recent literature at home and abroad was reviewed to summarize the mechanism of mitochondrial homeostasis imbalance, the relationship between mitochondrial homeostasis imbalance and the pathogenesis of OA, and the application prospect in the treatment of OA.

Results

Recent studies have shown that mitochondrial homeostasis imbalance, which is caused by abnormal mitochondrial biogenesis, the imbalance of mitochondrial redox, the imbalance of mitochondrial dynamics, and damaged mitochondrial autophagy of chondrocytes, plays an important role in the pathogenesis of OA. Abnormal mitochondrial biogenesis can accelerate the catabolic reaction of OA chondrocytes and aggravate cartilage damage. The imbalance of mitochondrial redox can lead to the accumulation of reactive oxygen species (ROS), inhibit the synthesis of extracellular matrix, induce ferroptosis and eventually leads to cartilage degradation. The imbalance of mitochondrial dynamics can lead to mitochondrial DNA mutation, decreased adenosine triphosphate production, ROS accumulation, and accelerated apoptosis of chondrocytes. When mitochondrial autophagy is damaged, dysfunctional mitochondria cannot be cleared in time, leading to ROS accumulation, which leads to chondrocyte apoptosis. It has been found that substances such as puerarin, safflower yellow, and astaxanthin can inhibit the development of OA by regulating mitochondrial homeostasis, which proves the potential to be used in the treatment of OA.

Conclusion

The mitochondrial homeostasis imbalance in chondrocytes is one of the most important pathogeneses of OA, and further exploration of the mechanisms of mitochondrial homeostasis imbalance is of great significance for the prevention and treatment of OA.

What is new in pharmacological treatment for osteoarthritis?

Osteoarthritis (OA) is a degenerative joint disease in which structural changes of hyaline articular cartilage, subchondral bone, ligaments, capsule, synovium, muscles, and periarticular changes are involved. The knee is the most commonly affected joint, followed by the hand, hip, spine, and feet. Different pathological mechanisms are at play in each of these various involvement sites. Although systemic inflammation is more prominent in hand OA, knee and hip OA have been associated with excessive joint load and injury. As OA has varied phenotypes and the primarily affected tissues differ, treatment options must be tailored accordingly. In recent years, ongoing efforts have been made to develop disease-modifying options that halt or slow disease progression. Many are still in clinical trials, and as insights into the pathogenesis of OA evolve, novel therapeutic strategies will be developed. In this chapter, we provide an overview of the novel and emerging strategies in the management of OA.

L-carnitine alleviates synovitis in knee osteoarthritis by regulating lipid accumulation and mitochondrial function through the AMPK-ACC-CPT1 signaling pathway

BACKGROUND

Knee osteoarthritis (KOA) is a disability-associated condition that is rapidly growing with the increase in obesity rates worldwide. There is a pressing need for precise management and timely intervention in the development of KOA. L-carnitine has been frequently recommended as a supplement to increase physical activity in obese individuals due to its role in fatty acid metabolism, immune disorders, and in maintaining the mitochondrial acetyl-CoA/CoA ratio. In this study, we aimed to investigate the anti-inflammatory effects of L-carnitine on KOA and delineate a potential molecular mechanism.

METHODS

Lipopolysaccharide-stimulated primary rat fibroblast-like synoviocytes (FLS) were treated with an AMP-activated protein kinase (AMPK) inhibitor or siRNA and carnitine palmitoyltransferase 1 (CPT1) siRNA to examine the synovial protective effects of L-carnitine. An anterior cruciate ligament transection model of rats was treated with an AMPK agonist (metformin) and CPT1 inhibitor (etomoxir) to define the therapeutic effects of L-carnitine.

RESULTS

L-carnitine displayed a protective effect against synovitis of KOA in vitro and in vivo experiments. Specifically, L-carnitine treatment can reduce synovitis by inhibiting AMPK-ACC-CPT1 pathway activation and showed an increase in fatty acid β-oxidation, a lower lipid accumulation, and a noticeable improvement in mitochondrial function.

CONCLUSIONS

Our data suggested that L-carnitine can mitigate synovitis in FLS and synovial tissue, and the underlying mechanism may be related to improving mitochondrial function and reducing lipid accumulation via the AMPK-ACC-CPT1 signaling pathway. Therefore, L-carnitine may be a potential treatment strategy for KOA.

Oxymatrine ameliorates osteoarthritis via the Nrf2/NF-κB axis in vitro and in vivo

PURPOSE

Osteoarthritis (OA) is a common degenerative joint disorder. Currently, the underlying etiology of OA is still far from fully elucidated and there is no cure for OA progression. Previous studies have demonstrated that oxymatrine (OMT) could inhibit inflammation and oxidative stress in several animal models. However, the potential effects of OMT on OA remain largely elusive. The aim of the study is to investigate the anti-inflammatory and chondrocyte protective effect of OMT, and delineate the potential mechanism in vitro and in vivo.

METHODS

Western blotting, RT-qPCR, ELISA and tissue staining were employed to explore the mechanisms by which OMT exerted a protective effect on IL-1β-induced production of pro-inflammation cytokines and extracellular matrix (ECM) degradation in primary murine chondrocytes and DMM mouse models.

RESULTS

The results showed that OMT reduced the IL-1β-induced over-production of pro-inflammation cytokines and ECM degradation. Mechanistically, OMT inhibited the NF-κB pathway via activating Nrf2. In vivo studies also demonstrated that OMT ameliorated OA progression.

CONCLUSIONS

OMT reduced pro-inflammation cytokines, ECM degradation and OA progression via activating Nrf2 and inhibiting NF-κB pathway.

Cystathionine-γ-lyase attenuates inflammatory response and pain of osteoarthritis

The chronic articular disease osteoarthritis (OA) is characterized by osteophyte generation, subchondral bone remodeling, and cartilage deterioration. Low levels of H2S catalyzed by cystathionine-γ-lyase (CSE) encoded by Cthhas neuroprotective, cardioprotective, anti-apoptotic, and anti-inflammatory effects thus, Cth is being developed as a potential therapy for the management of the pathogenesis and symptoms of osteoarthritis. Single-cell RNA sequencing (scRNA-seq) and immunohistochemistry of human cartilage revealed that the expression of CTH was decreased in OA patients. We found that Cthoverexpression decrease IL-1β-induced overactivation of the NF-κB signaling pathway. In vivo, Cthoverexpression relieved pain response and cartilage damage in the anterior cruciate ligament transection (ACLT) rat model. In vitro, CSE alleviated chondrocytes catabolism, inflammation, apoptosis, and senescence, and suppressed the NF-κB pathway. We postulate that CSE has therapeutic effects in suppressing inflammation and degeneration in OA and should be further investigated clinically.

Epigenetics as a mediator of genetic risk in osteoarthritis: role during development, homeostasis, aging, and disease progression

The identification of genomic loci that are associated with osteoarthritis (OA) has provided a starting point for understanding how genetic variation activates catabolic processes in the joint. However, genetic variants can only alter gene expression and cellular function when the epigenetic environment is permissive to these effects. In this review, we provide examples of how epigenetic shifts at distinct life stages can alter the risk for OA, which we posit is critical for the proper interpretation of genome-wide association studies (GWAS). During development, intensive work on the growth and differentiation factor 5 (GDF5) locus has revealed the importance of tissue-specific enhancer activity in controlling both joint development and the subsequent risk for OA. During homeostasis in adults, underlying genetic risk factors may help establish beneficial or catabolic "set points" that dictate tissue function, with a strong cumulative effect on OA risk. During aging, methylation changes and the reorganization of chromatin can "unmask" the effects of genetic variants. The destructive function of variants that alter aging would only mediate effects after reproductive competence and thus avoid any evolutionary selection pressure, as consistent with larger frameworks of biological aging and its relationship to disease. A similar "unmasking" may occur during OA progression, which is supported by the finding of distinct expression quantitative trait loci (eQTLs) in chondrocytes depending on the degree of tissue degradation. Finally, we propose that massively parallel reporter assays (MPRAs) will be a valuable tool to test the function of putative OA GWAS variants in chondrocytes from different life stages.

Metformin improves fibroblast metabolism and ameliorates arthrofibrosis in rats

Background

Emerging studies have suggested an essential role of fibroblast metabolic reprogramming in the pathogenesis of arthrofibrosis. The metabolic modulator metformin appears to be a therapeutic candidate for fibrotic disorders. However, whether metformin could alleviate arthrofibrosis has not been defined. In this study we have determined if treatment with metformin has beneficial effect on arthrofibrosis and its underlying mechanism.

Methods

Articular capsule samples were collected from patients with/without arthrofibrosis to perform gene and protein expression analysis. Arthrofibrosis animal model was established to examine the anti-fibrotic effect of metformin. Cell culture experiments were conducted to determine the mechanism by which metformin inhibits fibroblast activation.

Results

We found that glycolysis was upregulated in human fibrotic articular capsules. In an arthrofibrosis animal model, intra-articular injection of metformin mitigated inflammatory reactions, downregulated expression of both fibrotic and glycolytic markers, improved range of motion (ROM) of the joint, and reduced capsular fibrosis and thickening. At the cellular level, metformin inhibited the activation of fibroblasts and mitigated the abundant influx of glucose into activated fibroblasts. Interestingly, metformin prompted a metabolic shift from oxidative phosphorylation to aerobic glycolysis in activated fibroblasts, resulting in the anti-fibrotic effect of metformin.

Conclusion

Metformin decreased glycolysis, causing a metabolic shift toward aerobic glycolysis in activated fibroblasts and has beneficial effect on the treatment of arthrofibrosis.The translational potential of this article: The findings of this study demonstrated the therapeutic effect of metformin on arthrofibrosis and defined novel targets for the treatment of articular fibrotic disorders.

LKB1 Regulates Inflammation of Fibroblast-like Synoviocytes from Patients with Rheumatoid Arthritis via AMPK-Dependent SLC7A11-NOX4-ROS Signaling

Fibroblast-like synoviocytes (FLS) in rheumatoid arthritis (RA) patients have increased reactive oxygen species (ROS) levels and an impaired redox balance compared with FLS from control patients. Liver kinase B1 (LKB1) plays a key role in ROS scavenging and cellular metabolism in various cancers. Here, we aimed to determine the specific mechanism of LKB1 in RA pathogenesis. FLS were obtained from RA patients (n = 10). siRNA-induced LKB1 deficiency in RA FLS increased ROS levels via NADPH oxidase 4 (NOX4) upregulation. RA FLS migration and expression of inflammatory factors, including interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor-alpha (TNF-α), and vascular endothelial growth factor (VEGF), were enhanced by LKB1 deficiency. LKB1-deficient RA FLS showed increased sensitivity to oxidative stress damage caused by hydrogen peroxidase exposure. siRNA-induced solute carrier family 7 member 11 (SLC7A11) deficiency in RA FLS enhanced NOX4 and ROS expression and increased cell migration. When LKB1-deficient RA FLS were stimulated with an AMP-activated protein kinase (AMPK) activator, the LKB1-inhibition-induced cell migration significantly decreased through the restoration of SLC7A11/NOX4 expression. LKB1 regulates the AMPK-mediated SLC7A11-NOX4-ROS pathway to control cell migration and inflammation. Our data indicate that LKB1 is a key regulator of redox homeostasis in RA FLS.

Upregulation of β-catenin signaling represents a single common pathway leading to the various phenotypes of spinal degeneration and pain

Spine degeneration is an aging-related disease, but its molecular mechanisms remain unknown, although elevated β-catenin signaling has been reported to be involved in intervertebral disc degeneration. Here, we determined the role of β-catenin signaling in spinal degeneration and in the homeostasis of the functional spinal unit (FSU), which includes the intervertebral disc, vertebra and facet joint and is the smallest physiological motion unit of the spine. We showed that pain sensitivity in patients with spinal degeneration is highly correlated with β-catenin protein levels. We then generated a mouse model of spinal degeneration by transgenic expression of constitutively active β-catenin in Col2⁺ cells. We found that β-catenin-TCF7 activated the transcription of CCL2, a known critical factor in osteoarthritic pain. Using a lumbar spine instability model, we showed that a β-catenin inhibitor relieved low back pain. Our study indicates that β-catenin plays a critical role in maintaining spine tissue homeostasis, its abnormal upregulation leads to severe spinal degeneration, and its targeting could be an avenue to treat this condition.

DNA Supramolecular Hydrogel-Enabled Sustained Delivery of Metformin for Relieving Osteoarthritis

Osteoarthritis (OA) is a musculoskeletal disorder affecting ∼500 million people worldwide. Metformin (MET), as an oral hypoglycemic drug approved by the Food and Drug Administration, has displayed promising potential for treating OA. Nonetheless, in the articular cavity, MET suffers from rapid clearance and cannot circumvent the severe inflammatory environment, greatly confining the therapeutic efficacy. Herein, DNA supramolecular hydrogel (DSH) has been utilized as a sustained drug delivery vehicle for MET to treat OA, which dramatically prolonged the retention time of MET in the articular cavity from 3 to 14 days and simultaneously exerted a greater anti-inflammatory effect. Our delivery platform, termed MET@DSH, better protects cartilage than single-agent MET. Additionally, the corresponding molecular mechanisms underlying the therapeutic effects were also analyzed. We anticipate this DNA supramolecular hydrogel-enabled sustained drug delivery and anti-inflammatory strategy will reshape the current landscape of OA treatment.

FTO-mediated m6A demethylation of pri-miR-3591 alleviates osteoarthritis progression

OBJECTIVES

Increasing evidence have demonstrated the N6-methyladenosine (m⁶A) plays critical roles in osteoarthritis (OA) progression, but the role of m⁶A in OA has not been completely illuminated. Herein, we investigated the function and underlying mechanism of m⁶A demethylase fat mass and obesity-associated protein (FTO) in OA progression.

MATERIALS AND METHODS

The FTO expression was detected in mice OA cartilage tissues and lipopolysaccharide (LPS)-stimulated chondrocytes. Gain-of-function assays was used to evaluate the role of FTO in OA cartilage injury in vitro and in vivo. The miRNA-sequencing, RNA-binding protein immunoprecipitation (RIP), luciferase reporter assay, and in vitro pri-miRNA processing assays were conducted to confirm that FTO modulated the pri-miR-3591 process in an m6A-dependent manner and then the binding sites of miR-3591-5p with PRKAA2.

RESULTS

FTO was outstandingly downregulated in LPS-stimulated chondrocytes and OA cartilage tissues. FTO overexpression enhanced the proliferation, suppressed apoptosis, and decreased degradation of extracellular matrix in LPS-induced chondrocytes, whereas FTO knockdown contributed to the opposite effects. In vivo animal experiments showed that FTO overexpression markedly alleviated OA mice cartilage injury. Mechanically, FTO-mediated m6A demethylation of pri-miR-3591 leaded to a maturation block of miR-3591-5p, which relieved the inhibitory effect of miR-3591-5p on PRKAA2 and then promoted the increase of PRKAA2, thereby alleviating OA cartilage damage.

CONCLUSIONS

Our results attested that FTO alleviated the OA cartilage damage by mediating FTO/miR-3591-5p/PRKAA2 axis, which provided fresh insights into the therapeutic strategies for OA.

SPTLC2 ameliorates chondrocyte dysfunction and extracellular matrix metabolism disturbance in vitro and in vivo in osteoarthritis

Disturbances in chondrocyte extracellular matrix (ECM) metabolism in osteoarthritis (OA) are a major cause of OA and potentially lead to personal disability, placing a huge burden on society. Chondrocyte apoptosis and ECM catabolism have a major role in the OA process. Firstly, bioinformatics analysis was performed to screen differentially expressed genes (DEGs) in OA, and serine palmitoyltransferase subunit 2 (SPTLC2) was chosen, which had high-level expression in the OA cartilage tissues and OA chondrocytes. Overexpression and knockdown of SPTLC2 were achieved in OA chondrocytes and normal chondrocytes respectively to study the effect of SPTLC2 upon ECM metabolism of chondrocytes. Cell viability and apoptosis were measured using MTT and flow cytometry analyses; SPTLC2 overexpression enhanced the OA chondrocyte viability and decreased apoptotic rate. In addition, Western blot detection of ECM-related factors (Collagen I, Collage II, MMP-1, MMP-3, and MMP-13) revealed that SPTLC2 overexpression promoted the expression of collagens (Collagen I and Collage II) and suppressed matrix metalloproteinase (MMP-1, MMP-3, and MMP-13) level. In contrast, SPTLC2 knockdown in normal chondrocytes showed opposite effects on cell viability, apoptosis, and ECM degeneration. The articular cartilage of OA rats was transfected with lentivirus overexpressing SPTLC2; HE and Safranin-O fast green demonstrated that SPTLC2 overexpression could alleviate chondrocyte injuries and slow down the development of OA. In conclusion, SPTLC2 plays a role in OA and may be a potential target gene for the treatment of OA.

Metformin attenuates symptoms of osteoarthritis: role of genetic diversity of Bcl2 and CXCL16 in OA

OBJECTIVE

This study aimed to evaluate the effectiveness of metformin versus placebo in overweight patients with knee osteoarthritis (OA). In addition, to assess the effects of inflammatory mediators and apoptotic proteins in the pathogenesis of OA, the genetic polymorphisms of two genes, one related to apoptosis (rs2279115 of Bcl-2) and the other related to inflammation (rs2277680 of CXCL-16), were investigated.

METHODS

In this double-blind placebo-controlled clinical trial, patients were randomly divided to two groups, one group receiving metformin (n = 44) and the other one receiving an identical inert placebo (n = 44) for 4 consecutive months (starting dose 0.5 g/day for the first week, increase to 1 g/day for the second week, and further increase to 1.5 g/day for the remaining period). Another group of healthy individuals (n = 92) with no history and diagnosis of OA were included in this study in order to evaluate the role of genetics in OA. The outcome of treatment regimen was evaluated using the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire. The frequency of variants of rs2277680 (A181V) and rs2279115 (938C>A) were determined in extracted DNAs using PCR-RFLP method.

RESULTS

Our results indicated an increase in scores of pain (P ≤ 0.0001), activity of daily living (ADL) (P ≤ 0.0001), sport and recreation (Sport/Rec) (P ≤ 0.0001), and quality of life (QOL) (P = 0.003) and total scores of the KOOS questionnaire in the metformin group compared to the placebo group. Susceptibility to OA was associated with age, gender, family history, CC genotype of 938C>A (Pa = 0.001; OR = 5.2; 95% CI = 2.0-13.7), and GG+GA genotypes of A181V (Pa = 0.04; OR = 2.1; 95% CI = 1.1-10.5). The C allele of 938C>A (Pa = 0.04; OR = 2.2; 95% CI = 1.1-9.8) and G allele of A181V (Pa = 0.02; OR = 2.2; 95% CI = 1.1-4.8) were also associated with OA.

CONCLUSION

Our findings support the possible beneficial effects of metformin on improving pain, ADL, Sport/Rec, and QOL in OA patients. Our findings support the association between the CC genotype of Bcl-2 and GG+GA genotypes of CXCL-16 and OA.

Targeting CD38 to Suppress Osteoarthritis Development and Associated Pain After Joint Injury in Mice

OBJECTIVE

This study was undertaken to determine the role of CD38, which can function as an enzyme to degrade NAD⁺ , in osteoarthritis (OA) development.

METHODS

Human knee cartilage from normal donors and OA donors were examined for CD38 expression. "Gain-of-function," through overexpression of CD38 via transient transfection, and "loss-of-function," through pharmacologic inhibition of CD38, approaches were used to assess the effects of CD38 on intracellular NAD⁺ :NADH ratio and catabolic activity in chondrocytes. We also initiated joint injury-induced OA by surgical destabilization of the medial meniscus (DMM) in CD38 knockout mice and wild-type (WT; C57BL/6) mice and in WT male mice in the presence or absence of apigenin treatment. Cartilage degradation, synovial inflammation, subchondral bone changes, and pain behavior were evaluated after DMM surgery. We also examined expression of CD38 and the neuropeptide calcitonin gene-related peptide (CGRP) in knee sections from these mice.

RESULTS

CD38 expression was up-regulated in human knee OA cartilage and in chondrocytes stimulated with the proinflammatory cytokine interleukin-1β (IL-1β). Overexpression of CD38 in chondrocytes resulted in reduced cellular NAD⁺ :NADH ratio and augmented catabolic responses to IL-1β. These effects were reversed by pharmacologic inhibition of CD38. Cartilage degradation and synovial inflammation, associated with increased CD38 expression in cartilage and synovium, osteophyte formation and subchondral bone sclerosis, and pain-like behavior linked to increased CGRP expression in the synovium were observed in WT mice after joint injury. Such effects were significantly reduced in mice deficient in CD38 through either genetic knockout or pharmacologic inhibition.

CONCLUSION

CD38 deficiency exerts OA disease-modifying effects. Inhibition of CD38 has the potential to be a novel therapeutic approach for OA treatment.

Development of Osteoarthritis in Adults With Type 2 Diabetes Treated With Metformin vs a Sulfonylurea

IMPORTANCE

Metformin may have a protective association against developing osteoarthritis (OA), but robust epidemiological data are lacking.

OBJECTIVE

To determine the risk of OA and joint replacement in individuals with type 2 diabetes treated with metformin compared with a sulfonylurea.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study used claims data from the Optum deidentified Clinformatics Data Mart Database between December 2003 and December 2019. Participants included individuals aged 40 years or older with at least 1 year of continuous enrollment and type 2 diabetes. Individuals with type 1 diabetes or a prior diagnosis of OA, inflammatory arthritis, or joint replacement were excluded. Time-conditional propensity score matching was conducted using age, sex, race, Charlson comorbidity score, and treatment duration to create a prevalent new-user cohort. Data were analyzed from April to December 2021.

EXPOSURES

Treatment with metformin or a sulfonylurea.

MAIN OUTCOMES AND MEASURES

The outcomes of interest were incident OA and joint replacement. Cox proportional hazard models were used to calculate adjusted hazard ratios (aHRs) of incident OA and joint replacement. In a sensitivity analysis, individuals only ever treated with metformin were compared with individuals only ever treated with a sulfonylurea, allowing for longer-term follow up of the outcome (even after stopping the medication of interest).

RESULTS

After time-conditional propensity score matching, the metformin and control groups each included 20 937 individuals (mean [SD] age 62.0 [11.5] years; 24 379 [58.2%] males). In the adjusted analysis, the risk of developing OA was reduced by 24% for individuals treated with metformin compared with a sulfonylurea (aHR, 0.76; 95% CI, 0.68-0.85; P < .001), but there was no significant difference for risk of joint replacement (aHR, 0.80; 95% CI, 0.50-1.27; P = .34). In the sensitivity analysis, the risk of developing OA remained lower in individuals treated with metformin compared with a sulfonylurea (aHR, 0.77; 95% CI, 0.65-0.90; P < .001) and the risk of joint replacement remained not statistically significant (aHR, 1.04; 95% CI, 0.60-1.82; P = .89).

CONCLUSIONS AND RELEVANCE

In this cohort study of individuals with diabetes, metformin treatment was associated with a significant reduction in the risk of developing OA compared with sulfonylurea treatment. These results further support preclinical and observational data that suggest metformin may have a protective association against the development of OA; future interventional studies with metformin for the treatment or prevention of OA should be considered.

Targeting macrophage polarization as a promising therapeutic strategy for the treatment of osteoarthritis

Osteoarthritis (OA) is a chronic osteoarthropathy characterized by the progressive degeneration of articular cartilage and synovial inflammation. Early OA clinical treatments involve intra-articular injection of glucocorticoids, oral acetaminophen and non-steroidal anti-inflammatory drugs (NSAIDs), which are used for anti-inflammation and pain relief. However, long-term use of these agents will lead to inevitable side effects, even aggravate cartilage loss. At present, there are no disease-modifying OA drugs (DMOADs) yet approved by regulatory agencies. Polarization regulation of synovial macrophages is a new target for OA treatment. Inhibiting M1 polarization and promoting M2 polarization of synovial macrophages can alleviate synovial inflammation, relieve joint pain and inhibit articular cartilage degradation, which is a promising strategy for OA treatment. In this study, we describe the molecular mechanisms of macrophage polarization and its key role in the development of OA. Subsequently, we summarize the latest progress of strategies for OA treatment through macrophage reprogramming, including small molecule compounds (conventional western medicine and synthetic compounds, monomer compounds of traditional Chinese medicine), biomacromolecules, metal/metal oxides, cells, and cell derivatives, and interprets the molecular mechanisms, hoping to provide some information for DMOADs development.