CircZSWIM6 mediates dysregulation of ECM and energy homeostasis in ageing chondrocytes through RPS14 post-translational modification

Fostamatinib alleviates temporomandibular joint osteoarthritis by maintaining cartilage homeostasis through MAPK/NF-κB and AKT/mTOR pathways

Temporomandibular joint osteoarthritis (TMJ OA) is a common degenerative disease characterized by cartilage degeneration. However, the therapeutic strategies aimed to maintain cartilage homeostasis remain unclear. Fostamatinib (Fos) is a potential clinical drug for rheumatoid arthritis (RA) and predicted as target drug for many inflammatory diseases. In this study we investigated the therapeutic effects of Fos for TMJ OA and underlying mechanisms. Interleukin-1β (IL-1β) was used to construct a condylar chondrocyte injury model in vitro and rat TMJ OA models were induced by unilateral anterior crossbite (UAC) in vivo. Subsequently, a series of experiments were performed to assess the therapeutic effects and potential mechanisms of Fos in TMJ OA. Herein, we verified that Fos improved IL-1β-induced decrease in chondrocyte viability and proliferation, as well as inhibited cell apoptosis. Additionally, Fos could alleviate IL-1β-induced inflammation, ECM degradation, and chondrocyte phenotype change through blocking MAPK/NF-κB pathways, as well as promote chondrocyte autophagy by regulating AKT/mTOR pathways. The therapeutic effects of Fos on TMJ OA were further validated through rat UAC model in vivo. Overall, Fos could maintaining cartilage homeostasis through regulating chondrocyte inflammation, ECM degradation, and abnormal cell biological behaviors (apoptosis and autophagy), which made it a promising small molecule drug for TMJ OA early intervention.

Construction of AMPK-related circRNA network in mouse myocardial ischemia-reperfusion injury model

OBJECTIVE

To screen Myocardial ischemia-reperfusion Injury in mice. adenosine monophate-activatedprotein kinase (AMPK) -related differentially expressed circularRNA (circRNA) in MIRI model, Ampk-related circRNA network was drawn to provide possible ideas for the prevention and treatment of MIRI.

METHODS

The mouse MIRI model was constructed by ligation of the left anterior descending artery. After the model was successfully established, the related indicators of cardiac function were detected, and high-throughput sequencing was performed on the myocardial tissue of the mice.

RESULTS

MIRI model was successfully constructed, and two AMPK related differentially expressed loops (novel_circ_043550 and novel_circ_035243) were screened out. A circRNA-miRNA-mRNA network consisting of 2 circRNA, 28 microRNA(miRNA) and 229 messengerRNA (mRNA) was constructed.

CONCLUSIONS

This study reveals the differential expression of several AMPK-related circRNAs in MIRI in mice, and the AMPK-related circRNA regulatory network is constructed, suggesting that AMPK-related circRNA may have potential clinical application prospects as a potential molecular marker and therapeutic target for MIRI.

Procyanidin capsules provide a new option for long-term ROS scavenging in chronic inflammatory diseases

Chronic inflammatory diseases such as diabetic wounds and osteoarthritis are significant threats to human health. Failure to scavenge longstanding excessive reactive oxygen species (ROS) is an important cause of chronic inflammatory diseases, yet existing treatments that provide long-lasting therapeutic effects are limited. Here, procyanidin capsules were synthesized in a simple one-step way using calcium carbonate as a template. The biosafety of procyanidin capsules in vitro and in vivo was monitored by cytotoxicity and pathological sections. The therapeutic effect of procyanidin capsules in diabetic wounds and osteoarthritis was accessed by pathological evaluation combined with the quantification of inflammatory markers. The data showed that procyanidin capsules could long-term scavenge excessive ROS and effectively promote articular cartilage repair in osteoarthritis, accelerating diabetic wound healing. Lastly, transcriptome analysis suggested that procyanidin capsules commonly regulated adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) signaling in diabetic wounds and osteoarthritis. This study provides a straightforward protocol for creating procyanidin capsules, while presenting a promising new therapeutic option for long-term scavenging ROS in chronic inflammatory diseases.

Ageing-related bone and immunity changes: insights into the complex interplay between the skeleton and the immune system

Ageing as a natural irreversible process inherently results in the functional deterioration of numerous organ systems and tissues, including the skeletal and immune systems. Recent studies have elucidated the intricate bidirectional interactions between these two systems. In this review, we provide a comprehensive synthesis of molecular mechanisms of cell ageing. We further discuss how age-related skeletal changes influence the immune system and the consequent impact of immune system alterations on the skeletal system. Finally, we highlight the clinical implications of these findings and propose potential strategies to promote healthy ageing and reduce pathologic deterioration of both the skeletal and immune systems.

Crosstalk of ubiquitin system and non-coding RNA in fibrosis

Chronic tissue injury triggers changes in the cell type and microenvironment at the site of injury and eventually fibrosis develops. Current research suggests that fibrosis is a highly dynamic and reversible process, which means that human intervention after fibrosis has occurred has the potential to slow down or cure fibrosis. The ubiquitin system regulates the biological functions of specific proteins involved in the development of fibrosis, and researchers have designed small molecule drugs to treat fibrotic diseases on this basis, but their therapeutic effects are still limited. With the development of molecular biology technology, researchers have found that non-coding RNA (ncRNA) can interact with the ubiquitin system to jointly regulate the development of fibrosis. More in-depth explorations of the interaction between ncRNA and ubiquitin system will provide new ideas for the clinical treatment of fibrotic diseases.

A multifunctional nanogel encapsulating layered double hydroxide for enhanced osteoarthritis treatment via protection of chondrocytes and ECM

Osteoarthritis (OA) is characterized by progressive and irreversible damage to the articular cartilage and a consecutive inflammatory response. However, the majority of clinical drugs for OA treatment only alleviate symptoms without addressing the fundamental pathology. To mitigate this issue, we developed an inflammation-responsive carrier and encapsulated bioactive material, namely, LDH@TAGel. The LDH@TAGel was designed with anti-inflammatory and antioxidative abilities, aiming to directly address the pathology of cartilage damage. In particular, LDH was confirmed to restore the ECM secretion function of damaged chondrocytes and attenuate the expression of catabolic matrix metalloproteinases (Mmps). While TAGel showed antioxidant properties by scavenging ROS directly. In vitro evaluation revealed that the LDH@TAGel could protect chondrocytes from inflammation-induced oxidative stress and apoptosis via the Nrf2/Keap1 system and Pi3k-Akt pathway. In vivo experiments demonstrated that the LDH@TAGel could alleviated the degeneration and degradation of cartilage induced by anterior cruciate ligament transection (ACLT). The OARSI scores indicating OA severity decreased significantly after three weeks of intervention. Moreover, the IVIS image revealed that LDH@TAGel enhances the controlled release of LDH in a manner that can be customized according to the severity of OA, allowing adaptive, precise treatment. In summary, this novel design effectively alleviates the underlying pathological causes of OA-related cartilage damage and has emerged as a promising biomaterial for adaptive, cause-targeted OA therapies.

Bisdemethoxycurcumin, a curcumin, protects chondrocytes, and reduces cartilage inflammation via the NRF2/HO-1/NLRP3 pathway

BACKGROUND

The objective of this thesis is to evaluate the effect of bisdemethoxycurcumin (BDMC) on osteoarthritis (OA) and comprehensively evaluate the role of the Nuclear Factor erythroid 2-Related Factor 2 (Nrf2) signalling pathway in chondrocytes.

METHOD

In our study, we treated chondrocytes with BDMC in an in vitro chondrocyte assay and measured its influence on extracellular matrix (ECM) expression, downstream heme oxygenase-1 (HO-1) and NOD-like receptor thermal protein domain associated protein 3 (NLRP3) levels.

RESULTS

Our study indicates that BDMC significantly activates the Nrf2 signaling pathway in chondrocytes in vitro. Furthermore, the expression of matrix metalloproteinase 3, interleukin 1β, recombinant a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)4 and (ADAMTS)5 was significantly suppressed by BDMC.

CONCLUSION

This study confirms the potential for BDMC to activate the Nrf2/HO-1/NLRP3 signalling pathway and alleviate OA symptoms. Therefore, BDMC is a promising therapeutic agent for OA that offers new insights and treatment methods.

Circ-Slain2 Alleviates Cartilage Degradation and Inflammation of TMJOA

Temporomandibular joint osteoarthritis (TMJOA) is a degenerative disease with the cessation of matrix anabolism and aggravation of inflammation, which results in severe pain and impaired joint function. However, the mechanisms are not well understood. Circular RNAs (circRNAs) are reported to have various biological functions and participate in the development, diagnosis, prognosis, and treatment of different diseases. This study aimed to investigate the roles and mechanisms of circ-slain2 in TMJOA. We first established TMJOA mouse models and found circ-slain2 was lowly expressed in the cartilage of TMJOA through sequencing data. We observed that circ-slain2 is predominantly localized in the cytoplasm and downregulated in mouse condylar chondrocytes (mCCs) treated with tumor necrosis factor α (TNFα) and interferon γ (IFNγ). Micro-computed tomography and histological examination showed that intra-articular injection of circ-slain2 overexpressing adeno-associated virus could alleviate cartilage catabolism and synovial inflammation to relieve TMJOA in vivo. In addition, elevated circ-slain2 also showed anticatabolic and anti-inflammatory effects on IFNγ- and TNFα-stimulated mouse condylar chondrocytes (mCCs). Functional enrichment analysis indicated that protein processing in endoplasmic reticulum (ER) was associated with TMJOA, and further functional experiments confirmed that circ-slain2 could suppress ER stress in OA mCCs. RNA binding protein immunoprecipitation assay revealed an overt interaction between activating transcription factor 6 (ATF6) and circ-slain2. Inhibition of the expression of both ATF6 and circ-slain2 resulted in dilation of the ER and enhanced the expression of ER stress markers, whose ER stress level was higher than inhibition of ATF6 but lower than knockdown of circ-slain2 expression. Collectively, our research demonstrated that circ-slain2 could regulate ATF6 to relieve ER stress, reducing temporomandibular joint cartilage degradation and synovial inflammation. These findings provide prospects for developing novel osteoarthritis therapies based on circ-slain2 by focusing on reducing the inflammation of synovium and the imbalance between matrix synthesis and degradation.

Silencing of STUB1 relieves osteoarthritis via inducing NRF2-mediated M2 macrophage polarization

OBJECTIVES

Shifting macrophages towards an anti-inflammatory state is key in treating osteoarthritis (OA) by reducing inflammation and tissue damage. However, the underlying mechanisms guiding this shift remain largely undefined. STUB1, an E3 ubiquitin ligase, known for its regulatory role in macrophage polarization. This study aims to explore the function and underlying action mechanisms of STUB1 in OA.

METHODS

An in vivo OA model was established in rats. Hematoxylin-Eosin and safranin O-fast green staining were performed to reveal the hispathological injuries in knee-joint tissues. Immunohistochemistry and flow cytometry were performed to detect the distribution of M1 and M2 macrophages. The inflammatory response (TNF-α and IL-6 levels) was evaluated by ELISA. In vitro, the interaction between STUB1 and NFR2 was determined by CO-IP and pull-down assays. After treated with LPS (an in vitro model of OA), the viability and apoptosis of chondrocytes were measured by CCK-8 and flow cytometry, respectively.

RESULTS

Silencing STUB1 alleviated OA in rats, as indicated by reduced subchondral bone thickness, knee synovitis score, histopathological damages, and inflammatory response. STUB1 silencing also decreased M1 macrophages and increased M2 macrophages in both in vivo and in vitro settings. NRF2 was identified as a target of STUB1, with STUB1 mediating its ubiquitination. Silencing NRF2 reversed the effects of STUB1 silencing on inducing M2 macrophage polarization. Furthermore, silencing STUB1 upregulated NRF2 expression in LPS-treated chondrocytes, promoting cell viability and inhibiting apoptosis.

CONCLUSION

Silencing STUB1 induces M2 macrophage polarization by inhibiting NRF2 ubiquitination, thereby contributing to the mitigation of OA.

Circular RNA circARPC1B functions as a stabilisation enhancer of Vimentin to prevent high cholesterol-induced articular cartilage degeneration

BACKGROUND

Osteoarthritis (OA) is a prevalent and debilitating condition, that is, directly associated with cholesterol metabolism. Nevertheless, the molecular mechanisms of OA remain largely unknown, and the role of cholesterol in this process has not been thoroughly investigated. This study aimed to investigate the role of a novel circular RNA, circARPC1B in the relationship between cholesterol and OA progression.

METHODS

We measured total cholesterol (TC) levels in the synovial fluid of patients with or without OA to determine the diagnostic role of cholesterol in OA. The effects of cholesterol were explored in human and mouse chondrocytes in vitro. An in vivo OA model was also established in mice fed a high-cholesterol diet (HCD) to explore the role of cholesterol in OA. RNAseq analysis was used to study the influence of cholesterol on circRNAs in chondrocytes. The role of circARPC1B in the OA development was verified through circARPC1B overexpression and knockdown. Additionally, RNA pulldown assays and RNA binding protein immunoprecipitation were used to determine the interaction between circARPC1B and Vimentin. CircARPC1B adeno-associated virus (AAV) was used to determine the role of circARPC1B in cholesterol-induced OA.

RESULTS

TC levels in synovial fluid of OA patients were found to be elevated and exhibited high sensitivity and specificity as predictors of OA diagnosis. Moreover, elevated cholesterol accelerated OA progression. CircARPC1B was downregulated in chondrocytes treated with cholesterol and played a crucial role in preserving the extracellular matrix (ECM). Mechanistically, circARPC1B is competitively bound to the E3 ligase synoviolin 1 (SYVN1) binding site on Vimentin, inhibiting the proteasomal degradation of Vimentin. Furthermore, circARPC1B AAV infection alleviates Vimentin degradation and OA progression caused by high cholesterol.

CONCLUSIONS

These findings indicate that the cholesterol-circARPC1B-Vimentin axis plays a crucial role in OA progression, and circARPC1B gene therapy has the opportunity to provide a potential therapeutic approach for OA.

Regeneration of articular cartilage defects: Therapeutic strategies and perspectives

Articular cartilage (AC), a bone-to-bone protective device made of up to 80% water and populated by only one cell type (i.e. chondrocyte), has limited capacity for regeneration and self-repair after being damaged because of its low cell density, alymphatic and avascular nature. Resulting repair of cartilage defects, such as osteoarthritis (OA), is highly challenging in clinical treatment. Fortunately, the development of tissue engineering provides a promising method for growing cells in cartilage regeneration and repair by using hydrogels or the porous scaffolds. In this paper, we review the therapeutic strategies for AC defects, including current treatment methods, engineering/regenerative strategies, recent advances in biomaterials, and present emphasize on the perspectives of gene regulation and therapy of noncoding RNAs (ncRNAs), such as circular RNA (circRNA) and microRNA (miRNA).