MicroRNA-218-5p as a Potential Target for the Treatment of Human Osteoarthritis

MiR-653-5p drives osteoarthritis pathogenesis by modulating chondrocyte senescence

BACKGROUND

Due to the unclear pathogenesis of osteoarthritis (OA), effective treatment for this ailment is presently unavailable. Accumulating evidence points to chondrocyte senescence as a key driver in OA development. This study aims to identify OA-specific microRNAs (miRNAs) targeting chondrocyte senescence to alleviate OA progression.

METHODS

We screened and identified miRNAs differentially expressed in OA and normal cartilage, then confirmed the impact of miR-653-5p on chondrocyte functions and senescence phenotypes through in vitro experiments with overexpression/silencing. We identified interleukin 6 (IL-6) as the target gene of miR-653-5p and confirmed the regulatory influence of miR-653-5p on the IL-6/JAK/STAT3 signaling pathway through gain/loss-of-function studies. Finally, we assessed the therapeutic efficacy of miR-653-5p on OA using a mouse model with destabilization of the medial meniscus.

RESULTS

MiR-653-5p was significantly downregulated in cartilage tissues and chondrocytes from OA patients. Overexpression of miR-653-5p promoted chondrocyte matrix synthesis and proliferation while inhibiting chondrocyte senescence. Furthermore, bioinformatics target prediction and the luciferase reporter assays identified IL-6 as a target of miR-653-5p. Western blot assays demonstrated that miR-653-5p overexpression inhibited the protein expression of IL-6, the phosphorylation of JAK1 and STAT3, and the expression of chondrocyte senescence phenotypes by regulating the IL-6/JAK/STAT3 signaling pathway. More importantly, the cartilage destruction was significantly alleviated and chondrocyte senescence phenotypes were remarkably decreased in the OA mouse model treated by agomiR-653-5p compared to the control mice.

CONCLUSIONS

MiR-653-5p showed a significant decrease in cartilage tissues of individuals with OA, leading to an upregulation of chondrocyte senescence phenotypes in the articular cartilage. AgomiR-653-5p emerges as a potential treatment approach for OA. These findings provide further insight into the role of miR-653-5p in chondrocyte senescence and the pathogenesis of OA.

[miR-515-5p targeting Toll-like receptor 4 regulates myeloid differentiation primary response gene 88/nuclear factor-kappa B pathway to inhibit apoptosis and inflammatory response of osteoarthritis chondrocytes]

Objective

To explore the molecular mechanism of miR-515-5p in inhibiting chondrocyte apoptosis and alleviating inflammatory response in osteoarthritis (OA).

Methods

Human cartilage cell line C28/I2 was cultured in vitro and treated with 10 ng/mL interleukin 1β (IL-1β) for 24 hours to construct an in vitro OA model. C28/I2 cells were transfected with miR mimics, mimics negative control (NC), over expression (oe)-NC, and oe-Toll-like receptor 4 (TLR4), respectively, and then treated with 10 ng/mL IL-1β for 24 hours to establish OA model. Cell proliferation capacity was detected by cell counting kit 8 and 5-Ethynyl-2'-deoxyuridine, cell apoptosis and cell cycle were detected by flow cytometry, and B-cell lymphoma 2 protion (Bcl-2), Bcl-2-associated X protein (Bax), cleaved-Caspase-3, TLR4, myeloid differentiation primary response gene 88 (MyD88), p65 and phosphorylated p65 (p-p65) protein expression levels were detected by Western blot. Real-time fluorescence quantitative PCR was used to detect mRNA expression levels of miR-515-5p and TLR4, and ELISA was used to detect pro-inflammatory factor prostaglandin E2 (PGE2), tumor necrosis factor α (TNF -α), and IL-6 levels in cell supernatant. The potential binding sites between miR-515-5p and TLR4 were predicted by BiBiServ2 database, and the targeting relationship between miR-515-5p and TLR4 was verified by dual luciferase reporting assay.

Results

After the treatment of C28/I2 cells with IL-1β, the expressions of miR-515-5p and Bcl-2 protein and the proliferation ability of C28/I2 cells significantly reduced. The expression levels of Bax and cleaved-Caspase-3 protein, the levels of pro-inflammatory factors (PGE2, TNF-α, IL-6) in the supernatant of C28/I2 cells, and the apoptosis of C28/I2 cells significantly increased. In addition, the proportion of the cells at S phase and G 2 phase decreased significantly, and the proportion of cells at G 1 phase increased significantly, suggesting that the cell cycle was blocked after IL-1β treatment. After transfection with miR mimics, the expression level of miR-515-5p in the cells significantly up-regulated, partially reversing the apoptosis of OA chondrocytes induced by IL-1β, and alleviating the cycle arrest and inflammatory response of OA chondrocytes. After treating C28/I2 cells with IL-1β, the mRNA and protein levels of TLR4 significantly increased. Overexpression of miR-515-5p targeted inhibition of TLR4 expression and blocked activation of MyD88/nuclear factor κB (NF-κB) pathway. Overexpression of TLR4 could partially reverse the effect of miR mimics on IL-1β-induced apoptosis and inflammation of OA chondrocytes.

Conclusion

miR-515-5p negatively regulates the expression of TLR4, inhibits the activation of MyD88/NF-κB pathway and apoptosis of OA chondrocytes, and effectively alleviates the inflammatory response of the cells.

miR-92a-3p-inspired shRNA exhibits pro-chondrogenic and chondrocyte protective effects in osteoarthritis treatment through targeting SMAD6/7

INTRODUCTION

Osteoarthritis (OA) compromises patients' quality of life and requires further study. Although miR-92a-3p was reported to possess chondroprotective effects, the underlying mechanism requires further clarification. The objectives of this study were to elucidate the mechanism by which miR-92a-3p alleviates OA and to examine the efficacy of shRNA-92a-3p, which was designed based on mature miR-92a-3p.

MATERIALS AND METHODS

TargetScan and luciferase reporter assay were used to predict the target of miR-92a-3p. Adipose-derived stem cells (ADSCs) were transfected with miR-92a-3p/miR-NC mimic for the analysis of chondrogenic biomarkers and SMAD proteins. ADSCs and osteoarthritic chondrocytes were transduced with shRNA-92a-3p for the analysis of chondrogenic biomarkers and SMAD proteins. OA was surgically induced in C57BL/6JJcl mice, and ADSCs with/without shRNA-92a-3p transduction were intra-articularly injected for the assessment of cartilage damage.

RESULTS

SMAD6 and SMAD7 were predicted as direct targets of miR-92a-3p by TargetScan and luciferase reporter assay. Transfection of the miR-92a-3p mimic resulted in a decrease in SMAD6 and SMAD7 levels and an increase in phospho-SMAD2/3, phospho-SMAD1/5/9, SOX9, collagen type II, and aggrecan levels in ADSCs. Furthermore, shRNA-92a-3p decreased SMAD6 and SMAD7 levels, and increased phospho-SMAD2/3, phospho-SMAD1/5/9, SOX9, collagen type II, and aggrecan levels in ADSCs and osteoarthritic chondrocytes. Additionally, ADSC-shRNA-92a-3p-EVs reduced the rate of decrease of SOX9, collagen type II, and aggrecan in osteoarthritic chondrocytes. In mice with surgically induced OA, shRNA-92a-3p-treated ADSCs alleviated cartilage damage more effectively than nontreated ADSCs.

CONCLUSIONS

miR-92a-3p and shRNA-92a-3p exhibit therapeutic effects in treating OA by targeting SMAD6 and SMAD7, thereby enhancing TGF-β signaling.

miR-4478 Accelerates Nucleus Pulposus Cells Apoptosis Induced by Oxidative Stress by Targeting MTH1

OBJECTIVES

Low back pain is the leading cause of disability in the elderly population and is strongly associated with intervertebral disk degeneration (IVDD). However, the precise molecular mechanisms regulating IVDD remain elusive. This study aimed to investigate the role of differentially expressed miRNAs in the pathogenesis of IVDD.

MATERIALS AND METHODS

We analyzed miRNA microarray datasets to identify differentially expressed miRNAs in IVDD progression and conducted quantitative real-time polymerase chain reaction and fluorescence in situ hybridization analysis to further confirm the differential expression of miR-4478 in nucleus pulposus (NP) tissues of patients diagnosed with IVDD. Using public databases of miRNA-mRNA interactions, we predicted the target genes of miR-4478, and subsequent flow cytometry and western blot analyses demonstrated the effect of MTH1 in H 2 O 2 -induced nucleus pulposus cells (NPCs) apoptosis. Finally, miR-4478 inhibitor was injected into NP tissues of the IVDD mouse model to explore the effect of miR-4478 in vivo.

RESULTS

miR-4478 was upregulated in NP tissues from IVDD patients. Silencing of miR-4478 inhibits H 2 O 2 -induced NPCs apoptosis. MTH1 was identified as a target gene for miR-4478, and miR-4478 regulates H 2 O 2 -induced NPCs apoptosis by modulating MTH1. In addition, downregulation of miR-4478 alleviated IVDD in a mouse model.

CONCLUSIONS

In summary, our study provides evidence that miR-4478 may aggravate IVDD through its target gene MTH1 by accelerating oxidative stress in NPCs and demonstrates that miR-4478 has therapeutic potential in IVDD treatment.

miR-199a-5p Reduces Chondrocyte Hypertrophy and Attenuates Osteoarthritis Progression via the Indian Hedgehog Signal Pathway

Osteoarthritis (OA), the most common type of arthritis, is an age-associated disease, characterized by the progressive degradation of articular cartilage, synovial inflammation, and degeneration of subchondral bone. Chondrocyte proliferation is regulated by the Indian hedgehog (IHH in humans, Ihh in animals) signaling molecule, which regulates hypertrophy and endochondral ossification in the development of the skeletal system. microRNAs (miRNAs, miRs) are a family of about 22-nucleotide endogenous non-coding RNAs, which negatively regulate gene expression. In this study, the expression level of IHH was upregulated in the damaged articular cartilage tissues among OA patients and OA cell cultures, while that of miR-199a-5p was the opposite. Further investigations demonstrated that miR-199a-5p could directly regulate IHH expression and reduce chondrocyte hypertrophy and matrix degradation via the IHH signal pathway in the primary human chondrocytes. The intra-articular injection of synthetic miR-199a-5p agomir attenuated OA symptoms in rats, including the alleviation of articular cartilage destruction, subchondral bone degradation, and synovial inflammation. The miR-199a-5p agomir could also inhibit the Ihh signaling pathway in vivo. This study might help in understanding the role of miR-199a-5p in the pathophysiology and molecular mechanisms of OA and indicate a potential novel therapeutic strategy for OA patients.

Integrative analysis of microRNA-320a-related genes in osteoarthritis cartilage

Objectives

To investigate microRNA-320a-related differentially expressed genes (DEGs) and pathways in osteoarthritis (OA) by bioinformatic analysis.

Methods

The target genes of microRNA-320a were searched and collected from MiRTarBase microRNA Targets dataset, the TargetScan Predicted Nonconserved microRNA Targets dataset and the TargetScan Predicted Conserved microRNA Targets dataset. OA-related microRNAs and OA-related target genes were collected from GeneCards databases. The pathway enrichment analysis of miRNAs ware performed by Funrich analysis tool. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis was obtained from Database for Annotation, Visualization and Integrated Discovery (DAVID). GeneMANIA and STRING are used for protein-protein interaction (PPI) network analysis. Module analysis was performed by Cytoscape.

Results

A total of 176 OA related miRNAs were searched and collected for enrichment analysis, and microRNA-320a was one of OA related miRNAs. Enrichment pathway and analysis of 1721 miRNA-320a-related target genes from MiRTarBase and TargetScan were performed using the online tools Metascape. And results shown that the biological processes were remarkably enriched in chromatin organization, cellular response to DNA damage stimuli, mRNA metabolic process, protein ubiquitination, and regulation of cell adhesion. And then we analysed miRNA-320a-targeted OA genes via KEGG, GO enrichment and PPI Network. Our results showed that miRNA-320a played a role in OA through FoxO signaling pathway, PI3K-Akt signaling pathway, focal adhesion, MAPK signaling pathway, HIF-1 signaling pathway and cellular senescence. And we speculate that MAPK signaling pathway plays a key role in the effect of miRNA-320a on OA.

Conclusion

This study implied microRNA-320a-related DEGs and dysregulated pathways in OA. The aim is to screen miRNA-320a-related genes and pathways in OA and, eventually, to improve the understanding of underlying mechanisms of miRNA-320a in OA.

Targeting Vascular Endothelial Growth Factor Receptors as a Therapeutic Strategy for Osteoarthritis and Associated Pain

Pain is the major reason that patients suffering from osteoarthritis (OA) seek medical care. We found that vascular endothelial growth factors (VEGFs) mediate signaling in OA pain pathways. To determine the specific contributions of VEGFs and their receptors (VEGFRs) to joint pathology and pain transmission during OA progression, we studied intra-articular (IA) injections of VEGF ligands into murine knee joints. Only VEGF ligands specific for the activation of VEGFR1, but not VEGFR2, induced allodynia within 30 min. Interventions in OA by inhibitors of VEGFRs were done in vivo using a preclinical murine OA model by IA injections of selective inhibitors of VEGFR1/VEGFR2 kinase (pazopanib) or VEGFR2 kinase (vandetanib). OA phenotypes were evaluated using pain-associated murine behavioral tests and histopathologic analyses. Alterations in VEGF/VEGFR signaling by drugs were determined in knee joints, dorsal root ganglia, and spinal cord by immunofluorescence microscopy. Pazopanib immediately relieved OA pain by interfering with pain transmission pathways. Pain reduction by vandetanib was mainly due to the inhibition of cartilage degeneration by suppressing VEGFR2 expression. In conclusion, IA administration of pazopanib, which simultaneously inhibits VEGFR1 and VEGFR2, can be developed as an ideal OA disease-modifying drug that rapidly reduces joint pain and simultaneously inhibits cartilage degeneration.

Overexpression of FTO alleviates osteoarthritis by regulating the processing of miR-515-5p and the TLR4/MyD88/NF-κB axis

OBJECTIVE

Osteoarthritis (OA) is regarded as the most prevalent chronic joint disease. Fat-mass and obesity-associated gene (FTO) is involved in OA alleviation. This study elucidated the role of FTO in OA and the associated mechanism.

METHODS

We established a cell injury model by stimulating human normal chondrocytes (C28/I2) with lipopolysaccharide (LPS), and measured cell viability, apoptosis, and inflammatory cytokines using CCK-8, flow cytometry, Western blot, and ELISA. TLR4, MyD88, p/t-p65, and p/t-IκBα levels, FTO, COX-2, and iNOS mRNA levels, and m6A methylation levels were measured by Western blot, RT-qPCR, and colorimetry. RNA immunoprecipitation and co-immunoprecipitation were conducted to confirm the interaction between FTO and DGCR8. pri-miR-515-5p process was regulated in an m6A-dependent manner. After predicting the presence of several binding sites between miR-515-5p and TLR4 on Targetscan, we further confirmed their relationship by dual-luciferase assay. OA rat models were established by monosodium iodoacetate injection. The pathological changes in knee joint were observed by HE staining.

RESULTS

FTO was diminished in LPS-induced C28/I2 cells. With the increase of LPS concentration, cell viability was repressed, apoptosis rate was increased, and inflammatory markers were promoted, which were annulled by FTO overexpression. FTO interacted with DGCR8 and modulated the pri-miR-515-5p processing in an m6A-dependent manner. miR-515-5p silencing partially averted the inhibitory effect of FTO on LPS-induced cell injury. Given that TLR4 was a direct target of miR-515-5p, miR-515-5p inactivated the MyD88/NF-κB pathway by targeting TLR4. FTO overexpression improved cartilage structure in OA rats, reduced apoptosis, inhibited inflammation in synovial fluid, and repressed the TLR4/MyD88/NF-κB axis.

CONCLUSION

FTO alleviated OA in an m6A-dependent manner via the miR-515-5p/TLR4/MyD88/NF-κB axis.

Comparison between articular chondrocytes and mesenchymal stromal cells for the production of articular cartilage implants

Focal lesions of articular cartilage give rise to pain and reduced joint function and may, if left untreated, lead to osteoarthritis. Implantation of in vitro generated, scaffold-free autologous cartilage discs may represent the best treatment option. Here we compare articular chondrocytes (ACs) and bone marrow-derived mesenchymal stromal cells (MSCs) for their ability to make scaffold-free cartilage discs. Articular chondrocytes produced more extracellular matrix per seeded cell than mesenchymal stromal cells. Quantitative proteomics analysis showed that articular chondrocyte discs contained more articular cartilage proteins, while mesenchymal stromal cell discs had more proteins associated with cartilage hypertrophy and bone formation. Sequencing analysis revealed more microRNAs associated with normal cartilage in articular chondrocyte discs, and large-scale target predictions, performed for the first time for in vitro chondrogenesis, suggested that differential expression of microRNAs in the two disc types were important mechanisms behind differential synthesis of proteins. We conclude that articular chondrocytes should be preferred over mesenchymal stromal cells for tissue engineering of articular cartilage.

Effect of miRNA-218-5p on Proliferation, Migration, Apoptosis and Inflammation of Vascular Smooth Muscle Cells in Abdominal Aortic Aneurysm and Extracellular Matrix Protein

Background

To explore the effects of miRNA-218-5p on inflammation and extracellular matrix proteins of vascular smooth muscle cell line in abdominal aortic aneurysm (AAA).

Methods

miR-218-5p expression was detected with RT-qPCR. The proliferative activity of vascular smooth muscle cells (VSMCs) was detected with CCK-8, the migration was detected by Transwell, and the apoptosis was detected with flow cytometry. The expression levels of inflammatory factors (IL-1β and IL-18) were detected by ELISA. The expression levels of proteins (MMP-9 and Netrin-1) and ADAMTS5 were detected by Western blot. The targeting relationship between miR-218-5p and ADAMTS5 was verified with dual-luciferase reporter assay.

Results

Up-regulating miR-218-5p could significantly inhibit the proliferation and migration of VSMCs and induced the apoptosis (P<0.05). Down-regulating miR-218-5p could significantly promote the proliferation and migration of VSMCs and inhibit the apoptosis (P<0.05). Up-regulating miR-218-5p could inhibit the expression levels of THP-1 cytoinflammatory factors (IL-8 and IL-1β), MMP-9 and netrin-1. ADAMTS5 was the target gene of miR-218-5p. When there were both overexpression of ADAMTS5 and upregulation of miR-218-5p, the upregulation of miR-218-5p could alleviate the effects of overexpression of ADAMTS5 on the proliferation, migration and apoptosis of VSMCs.

Conclusion

miR-218-5p/ADAMTS-5 molecular axis regulates the proliferation, migration, and apoptosis of VSMCs, as well as the expression of THP-1 cell inflammatory molecules and extracellular matrix molecules.

miR-210-3p protects against osteoarthritis through inhibiting subchondral angiogenesis by targeting the expression of TGFBR1 and ID4

Excessive subchondral angiogenesis is a key pathological feature of osteoarthritis (OA), as it alters the balance of subchondral bone remodeling and causes progressive cartilage degradation. We previously found that miR-210-3p correlates negatively with angiogenesis, though the specific mechanism of miR-210-3p-related angiogenesis in subchondral bone during OA progression remains unclear. This study was conducted to identify the miR-210-3p-modulating subchondral angiogenesis mechanism in OA and investigate its therapeutic effect. We found that miR-210-3p expression correlated negatively with subchondral endomucin positive (Emcn+) vasculature in the knee joints of OA mice. miR-210-3p overexpression regulated the angiogenic ability of endothelial cells (ECs) under hypoxic conditions in vitro. Mechanistically, miR-210-3p inhibited ECs angiogenesis by suppressing transforming growth factor beta receptor 1 (TGFBR1) mRNA translation and degrading DNA-binding inhibitor 4 (ID4) mRNA. In addition, TGFBR1 downregulated the expression of ID4. Reduced ID4 levels led to a negative feedback regulation of TGFBR1, enhancing the inhibitory effect of miR-210-3p on angiogenesis. In OA mice, miR-210-3p overexpression in ECs via adeno-associated virus (AAV) alleviated cartilage degradation, suppressed the type 17 immune response and relieved symptoms by attenuating subchondral Emcn+ vasculature and subchondral bone remodeling. In conclusion, we identified a miR-210-3p/TGFBR1/ID4 axis in subchondral ECs that modulates OA progression via subchondral angiogenesis, representing a potential OA therapy target.

Role of exosomes in bone and joint disease metabolism, diagnosis, and therapy

Bone and joint diseases are prevalent and often fatal conditions in elderly individuals. Additionally, bone-derived cells may release exosomes that package and distribute a range of active substances, such as proteins, miRNAs, and numerous active factors, thereby facilitating material and information interchange between cells. Exososmes generated from bone may be utilized to manage bone production and resorption balance or even as biological or gene therapy carriers, depending on their properties and composition. In this review, we will discuss the composition, secretion, and uptake theory of exososmes, the role of exososmes in bone metabolism regulation, the pathogenesis and diagnosis of bone and joint diseases, and the application of exososmes in regenerative medicine. The findings will expand our understanding of the potential research and application space regarding exososmes.

YY1-induced lncRNA XIST inhibits cartilage differentiation of BMSCs by binding with TAF15 to stabilizing FUT1 expression

Introduction

The functional roles and mechanism of the XIST in osteoarthritis and the chondrogenic differentiation of BMSCs were clarified.

Methods

The expression levels of XIST, TAF15, FUT1 and YY1 were detected through quantitative RT-PCR. The protein expression of Sox9, ACAN, COL2A1 and FUT1 were detected by western blot and immunohistochemistry. The damage of cartilage tissue was detected by HE staining, and Safranin O-fast green. Alcian-Blue and Alizarin red S staining were performed to evaluate BMSCs chondrogenic differentiation. The relationship between XIST and TAF15, XIST and TAF15 were analyzed by RNA immunoprecipitation assay. Luciferase reporter assays and chromatin immunoprecipitation were performed to detect the interaction relationship between XIST and YY1. In addition, osteoarthritis mice were built to assess the function of XIST in vivo.

Results

The levels of XIST, TAF15 and FUT1 were upregulated in cartilage tissues from osteoarthritis patient. The level of XIST was decreased in BMSCs during chondrogenic differentiation. XIST overexpression inhibited the chondrogenic differentiation of BMSCs. Moreover, silencing of FUT1 reversed the effects of XIST overexpression on BMSCs chondrogenic differentiation. Mechanistically, in BMSCs, YY1 induced the expression of XIST in BMSCs, and XIST regulated FUT1 mRNA stability through targeting TAF15. Furthermore, silencing of XIST alleviated the symptoms of cartilage injury in OA mice.

Conclusion

Taken together, these results suggested that YY1 induced XIST was closely related to the chondrogenic differentiation of BMSCs and the progression of osteoarthritis by TAF15/FUT1 axis, and may be a new OA therapeutic target.

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XIST and TAF15 expression were upregulated in osteoarthritis.

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Overexpression of XIST suppressed the chondrogenic differentiation of BMSCs.

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XIST regulated BMSCs chondrogenic differentiation through enhancing FUT1 mRNA stability via TAF15.

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XIST silencing relieved cartilage damage in OA mice.

Crosstalk Among circRNA/lncRNA, miRNA, and mRNA in Osteoarthritis

Osteoarthritis (OA) is a joint disease that is pervasive in life, and the incidence and mortality of OA are increasing, causing many adverse effects on people's life. Therefore, it is very vital to identify new biomarkers and therapeutic targets in the clinical diagnosis and treatment of OA. ncRNA is a nonprotein-coding RNA that does not translate into proteins but participates in protein translation. At the RNA level, it can perform biological functions. Many studies have found that miRNA, lncRNA, and circRNA are closely related to the course of OA and play important regulatory roles in transcription, post-transcription, and post-translation, which can be used as biological targets for the prevention, diagnosis, and treatment of OA. In this review, we summarized and described the various roles of different types of miRNA, lncRNA, and circRNA in OA, the roles of different lncRNA/circRNA-miRNA-mRNA axis in OA, and the possible prospects of these ncRNAs in clinical application.

Recent Advances in Pharmacological Intervention of Osteoarthritis: A Biological Aspect

Osteoarthritis (OA) is a degenerative joint disease in the musculoskeletal system with a relatively high incidence and disability rate in the elderly. It is characterized by the degradation of articular cartilage, inflammation of the synovial membrane, and abnormal structure in the periarticular and subchondral bones. Although progress has been made in uncovering the molecular mechanism, the etiology of OA is still complicated and unclear. Nevertheless, there is no treatment method that can effectively prevent or reverse the deterioration of cartilage and bone structure. In recent years, in the field of pharmacology, research focus has shifted to disease prevention and early treatment rather than disease modification in OA. Biologic agents become more and more attractive as their direct or indirect intervention effects on the initiation or development of OA. In this review, we will discuss a wide spectrum of biologic agents ranging from DNA, noncoding RNA, exosome, platelet-rich plasma (PRP), to protein. We searched for key words such as OA, DNA, gene, RNA, exosome, PRP, protein, and so on. From the pharmacological aspect, stem cell therapy is a very special technique, which is not included in this review. The literatures ranging from January 2016 to August 2021 were included and summarized. In this review, we aim to help readers have a complete and precise understanding of the current pharmacological research progress in the intervention of OA from the biological aspect and provide an indication for the future translational studies.

CircRNA_0092516 regulates chondrocyte proliferation and apoptosis in osteoarthritis through the miR-337-3p/PTEN axis

The dysregulation of circular RNAs (circRNAs) has been identified in various human diseases. Here, we probed into the potential mechanism of circRNA_0092516 in osteoarthritis (OA). The expression of circRNA_0092516 was tested by quantitative real-time PCR. MTT, flow cytometry and western blot were applied to confirm the functions of circRNA_0092516 in vitro. Besides, RNA pull-down and dual-luciferase reporter gene experiments were applied to probe into the mechanism. circRNA_0092516 was raised in the tissues of OA patients and chondrocytes stimulated by IL-1β. The potential mechanism analysis expounded that circRNA_0092516 bound to miR-337-3p, and the interference with circRNA_0092516 boosted chondrocyte proliferation and restrained cell apoptosis through the miR-337-3p/phosphatase and tensin homolog (PTEN) axis, thereby improving OA. In-vivo experiments expounded that circRNA_0092516 regulated cartilage production through miR-337-3p. Overall, our data expounded that the interference with circRNA_0092516 boosted chondrocyte proliferation and restrained cell apoptosis through the miR-337-3p/PTEN axis, eventually slowed down the progress of OA.

Small Noncoding RNAs in Knee Osteoarthritis: The Role of MicroRNAs and tRNA-Derived Fragments

Knee osteoarthritis (OA) is a degenerative knee joint disease that results from the breakdown of joint cartilage and underlying bone, affecting about 3.3% of the world's population. As OA is a multifactorial disease, the underlying pathological process is closely associated with genetic changes in articular cartilage and bone. Many studies have focused on the role of small noncoding RNAs in OA and identified numbers of microRNAs that play important roles in regulating bone and cartilage homeostasis. The connection between other types of small noncoding RNAs, especially tRNA-derived fragments and knee osteoarthritis is still elusive. The observation that there is limited information about small RNAs different than miRNAs in knee OA was very surprising to us, especially given the fact that tRNA fragments are known to participate in a plethora of human diseases and a portion of them are even more abundant than miRNAs. Inspired by these findings, in this review we have summarized the possible involvement of microRNAs and tRNA-derived fragments in the pathology of knee osteoarthritis.

LncRNA KCNQ1OT1 attenuates osteoarthritic chondrocyte dysfunction via the miR-218-5p/PIK3C2A axis

The occurrence of osteoarthritis is closely related to chondrocyte dysfunction caused by cellular inflammatory response and matrix degradation, which seriously affect the quality of life of patients. Therefore, this study aimed to investigate the role of potassium voltage-gated channel subfamily Q member 1 overlapping transcript 1 (KCNQ1OT1), a member of the lncRNA voltage-gated channel subfamily Q, in the development of osteoarthritis. In this study, RT-qPCR results showed that KCNQ1OT1 expression was downregulated in osteoarthritic chondrocytes compared with normal chondrocytes. In addition, upregulation of KCNQ1OT1 significantly enhanced the viability of osteoarthritic chondrocytes, inhibited cell apoptosis, and reduced the release of inflammatory cytokines and metal matrix enzymes. Next, bioinformatics analysis and luciferase reporter gene analysis predicted and validated the targeting relationship between KCNQ1OT1 and miR-218-5p. We found that the expression of miR-218-5p was significantly upregulated in osteoarthritic chondrocytes, and knockdown of miR-218-5p significantly enhanced the viability of osteoarthritic chondrocytes, inhibited apoptosis, and decreased the abundance of inflammatory cytokines and metal matrix enzymes. Furthermore, the targeting relationship between miR-218-5p and recombinant phosphoinositide-3-kinase class-2-alpha polypeptide (PIK3C2A) was identified, and overexpression of PIK3C2A enhanced cell viability, and reduced apoptosis and secretion of inflammatory factors. Finally, we found that miR-218-5p overexpression reversed the protective effect of overexpression of KCNQ1OT1 or PIK3C2A on osteoarthritic chondrocytes. In conclusion, our results demonstrated that KCNQ1OT1 upregulated PIK3C2A and activated the PI3K/AKT/mTOR pathway to reduce chondrocyte dysfunction by targeting miR-218-5p, providing new insights into the pathogenesis of osteoarthritis.

MicroRNA-197 regulates chondrocyte proliferation, migration, and inflammation in pathogenesis of osteoarthritis by targeting EIF4G2

Recent studies have demonstrated that microRNAs (miRNAs) are involved in many pathological conditions including osteoarthritis (OA). In the present study, we aimed to investigate the role of miR-197 in OA and the potential molecular mechanism. The expression levels of miR-197 were detected by quantitative real-time PCR analysis. Cell proliferation and migration abilities were performed by 3-(4,5-dimethylthiazol-2-yl)-2,5-di-phenyltetrazolium bromide and transwell assays. The concentrations of inflammatory cytokines, including IL-1β, IL-6, and TNF-α, were detect using ELISA assay. Furthermore, luciferase reporter and rescue assays were applied to identify the functional target gene of miR-197 in OA. The results showed that miR-197 expression was significantly down-regulated in the OA cartilage tissues compared with normal cartilage tissues, accompanied by up-regulation of EIF4G2 expression. An inverse correlation was found between EIF4G2 and miR-197 expressions in OA cartilage tissues. Treatment with miR-197 mimics promoted the growth and migration abilities of chondrocytes, while miR-197 inhibitors induced the opposite effects. Furthermore, restoration of miR-197 significantly decreased IL-1β, IL-6, and TNF-α expression, whereas knockdown of miR-197 led to a induction in these inflammatory mediators. Moreover, EIF4G2 was predicted and confirmed as a directly target of miR-197. Overexpressed miR-197 could down-regulate EIF4G2 expression in chondrocytes, while miR-197 knockdown could elevate EIF4G2 expression. Additionally, EIF4G2 overexpression reversed the effects of miR-197 mimics on chondrocytes proliferation, migration, and inflammation. Taken together, our study demonstrated that miR-197 promotes chondrocyte proliferation, increases migration, and inhibits inflammation in the pathogenesis of OA by targeting EIF4G2, indicating the potential therapeutic targets of the miR-197/EIF4G2 axis for OA treatment.

Decreased miR-214-3p activates NF-κB pathway and aggravates osteoarthritis progression

Background

Osteoarthritis (OA), a disease with whole-joint damage and dysfunction, is the leading cause of disability worldwide. The progressive loss of hyaline cartilage extracellular matrix (ECM) is considered as its hallmark, but its exact pathogenesis needs to be further clarified. MicroRNA(miRNA) contributes to OA pathology and may help to identify novel biomarkers and therapies against OA. Here we identified miR-214–3p as an important regulator of OA.

Methods

qRT-PCR and in situ hybridization were used to detect the expression level of miR-214–3p. The function of miR-214–3p in OA, as well as the interaction between miR-214–3p and its downstream mRNA target (IKBKB), was evaluated by western blotting, immunofluorescence, qRT-PCR and luciferase assay. Mice models were introduced to examine the function and mechanism of miR-214–3p in OA in vivo.

Findings

In our study, we found that miR-214–3p, while being down-regulated in inflamed chondrocytes and OA cartilage, regulated ECM metabolism and cell apoptosis in the cartilage. Mechanically, the protective effect of miR-214–3p downregulated the IKK-β expression and led to the dysfunction of NF-κB signaling pathway. Furthermore, intra-articular injection of miR-214–3p antagomir in mice joints triggered spontaneous cartilage loss while miRNA-214–3p agomir alleviated OA in the experimental mouse models.

Interpretation

Decreased miR-214–3p activates the NF-κB signaling pathway and aggravates OA development through targeting IKKβ, suggesting miR-214–3p may be a novel therapeutic target for OA.

Funding

This study was financially supported by grants from the National Natural Science Foundation of China (81,773,532, 81,974,342).

RETRACTED: Inhibited microRNA-218-5p attenuates synovial inflammation and cartilage injury in rats with knee osteoarthritis by promoting sclerostin

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Concern was raised about the reliability of the Western blot results in Figs. 1C and 7B, which appear to have the same eyebrow shaped phenotype as many other publications tabulated here (https://docs.google.com/spreadsheets/d/149EjFXVxpwkBXYJOnOHb6RhAqT4a2llhj9LM60MBffM/edit#gid=0). The journal requested the corresponding author comment on these concerns and provide the raw data. However the authors were not able to satisfactorily fulfil this request and therefore the Editor-in-Chief decided to retract the article.

Mechanism of miR-218-5p in autophagy, apoptosis and oxidative stress in rheumatoid arthritis synovial fibroblasts is mediated by KLF9 and JAK/STAT3 pathways

This study was aimed to investigate the effects of miR-218-5p on the proliferation, apoptosis, autophagy, and oxidative stress of rheumatoid arthritis synovial fibroblasts (RASFs), and the related mechanisms. Quantitative reverse transcription-PCR showed that the expression of miR-218-5p in rheumatoid arthritis synovial tissue was significantly higher than that in healthy synovial tissue. Compared with healthy synovial fibroblasts, miR-218-5p expression was obviously upregulated in RASFs, while KLF9 protein expression was markedly downregulated. Mechanistically, miR-218-5p could directly bind to the 3' untranslated region of KLF9 to inhibit the expression of KLF9. Additionally, transfection of miR-218-5p small interfering RNA (siRNA) inhibited the proliferation but promoted apoptosis and autophagy of RASFs. Simultaneously, miR-218-5p silencing reduced reactive oxygen species and malondialdehyde levels and increased superoxide dismutase and glutathione peroxidase activity to improve oxidative stress in RASFs. More importantly, the introduction of KLF9 siRNA reversed the effects of miR-218-5p siRNA transfection on RASF proliferation, apoptosis, autophagy, and oxidative stress. What is more, silencing miR-218-5p inhibited the activation of JAK2/STAT3 signaling pathway by targeting KLF9. Collectively, knockdown of miR-218-5p could regulate the proliferation, apoptosis, autophagy and oxidative stress of RASFs by increasing the expression of KLF9 and inhibiting the activation of the JAK2/STAT3 signaling pathway, which may provide a potential target for the mechanism research of RA.

Quercitrin alleviates cartilage extracellular matrix degradation and delays ACLT rat osteoarthritis development: An in vivo and in vitro study

Introduction: Disruptions of extracellular matrix (ECM) degradation homeostasis play a significant role in the pathogenesis of osteoarthritis (OA). Matrix metalloproteinase 13 (MMP13) and collagen Ⅱ are important components of ECM. Earlier we found that quercitrin could significantly decrease MMP13 gene expression and increase collagen Ⅱ gene expression in IL-1β-induced rat chondrocytes and human chondrosarcoma (SW1353) cells. Objectives: The effects and mechanism of quercitrin on OA were explored. Methods: Molecular mechanisms of quercitrin on OA were studied in vitro in primary chondrocytes and SW1353 cells. An anterior cruciate ligament transection (ACLT) rat model of OA was used to investigate the effect of quercitrin in vivo. Micro-CT analysis and Safranin O-Fast Green Staining of knee joint samples were performed to observe the damage degree of tibial subchondral bone. Immunohistochemistry of knee joint samples were conducted to observe the protein level of MMP13, collagen Ⅱ and p110α in articular cartilage. Results: In vitro, quercitrin promoted cell proliferation and delayed ECM degradation by regulating MMP13 and collagen II gene and protein expressions. Moreover, quercitrin activated the Phosphatidylinositol 3-kinase p110α (p110α)/AKT/mTOR signaling pathway by targeting p110α. We also firstly showed that the gene expression level of p110α was remarkably decreased in cartilage of OA patients. The results showed that intra-articular injection of quercitrin increased bone volume/tissue volume of tibial subchondral bone and cartilage thickness and reduced the Osteoarthritis Research Society International scores in OA rats. Meanwhile, immunohistochemical results showed that quercitrin exerted anti-OA effect by delaying ECM degradation. Conclusion: These findings suggested that quercitrin may be a prospective disease-modifying OA drug for prevention and treatment of early stage OA.

Circ_0045714 alleviates TNF-α-induced chondrocyte injury and extracellular matrix degradation through miR-218-5p/HRAS axis

Emerging evidence suggests that dysregulated circular RNAs (circRNAs) play a pivotal role in osteoarthritis (OA). Circ_0045714 is a functional circRNAs, and has been revealed to involve in the process of OA. However, the molecular mechanisms by which circ_0045714 regulates OA progression are not thoroughly elucidated. Circ_0045714 expression was decreased in OA and TNF-α-induced chondrocytes, ectopic overexpression of circ_0045714 abolished TNF-α-induced cell apoptosis, inflammation, extracellular matrix (ECM) degradation promotion and proliferation inhibition. In a mechanical study, circ_0045714 targeted miR-218-5p, and miR-218-5p overexpression reversed the effects of circ_0045714 on TNF-α-induced chondrocytes. Besides that, HRAS was a target of miR-218-5p, and HRAS knockdown attenuated the protective effects of miR-218-5p inhibition on TNF-α-induced chondrocyte dysfunction. Additionally, circ_0045714 could regulate HRAS expression via miR-218-5p in chondrocytes. Up-regulation of circ_0045714 suppressed TNF-α-induced chondrocyte growth inhibition, inflammation, and ECM degradation via miR-218-5p/HRAS axis, suggesting a novel insight into the pathogenesis of OA and the potential protective role of circ_0045714 in the occurrence and development of OA.

MiR-218 affects hypertrophic differentiation of human mesenchymal stromal cells during chondrogenesis via targeting RUNX2, MEF2C, and COL10A1

Background

Human mesenchymal stromal cells (MSC) hold hopes for cartilage regenerative therapy due to their chondrogenic differentiation potential. However, undesirable occurrence of calcification after ectopic transplantation, known as hypertrophic degeneration, remains the major obstacle limiting application of MSC in cartilage tissue regeneration approaches. There is growing evidence that microRNAs (miRs) play essential roles in post-transcriptional regulation of hypertrophic differentiation during chondrogenesis. Aim of the study was to identify new miR candidates involved in repression of hypertrophy-related targets.

Methods

The miR expression profile in human articular chondrocytes (AC) was compared to that in hypertrophic chondrocytes derived from human MSC by microarray analysis, and miR expression was validated by qPCR. Putative targets were searched by in silico analysis and validated by miR reporter assay in HEK293T, by functional assays (western blotting and ALP-activity) in transiently transfected SaOS-2 cells, and by a miR pulldown assay in human MSC. The expression profile of miR-218 was assessed by qPCR during in vitro chondrogenesis of MSC and re-differentiation of AC. MSC were transfected with miR-218 mimic, and differentiation outcome was assessed over 28 days. MiR-218 expression was quantified in healthy and osteoarthritic cartilage of patients.

Results

Within the top 15 miRs differentially expressed between chondral AC versus endochondral MSC differentiation, miR-218 was selected as a candidate miR predicted to target hypertrophy-related genes. MiR-218 was downregulated during chondrogenesis of MSC and showed a negative correlation to hypertrophic markers, such as COL10A1 and MEF2C. It was confirmed in SaOS-2 cells that miR-218 directly targets hypertrophy-related COL10A1, MEF2C, and RUNX2, as a gain of ectopic miR-218 mimic caused drop in MEF2C and RUNX2 protein accumulation, with attenuation of COL10A1 expression and significant concomitant reduction of ALP activity. A miR pulldown assay confirmed that miR-218 directly targets RUNX2, MEF2C in human MSC. Additionally, the gain of miR-218 in human MSC attenuated hypertrophic markers (MEF2C, RUNX2, COL10A1, ALPL), although with no boost of chondrogenic markers (GAG deposition, COL2A1) due to activation of WNT/β-catenin signaling. Moreover, no correlation between miR-218 expression and a pathologic phenotype in the cartilage of osteoarthritis (OA) patients was found.

Conclusions

Although miR-218 was shown to target pro-hypertrophic markers MEF2C, COL10A1, and RUNX2 in human MSC during chondrogenic differentiation, overall, it could not significantly reduce the hypertrophic phenotype or boost chondrogenesis. This could be explained by a concomitant activation of WNT/β-catenin signaling counteracting the anti-hypertrophic effects of miR-218. Therefore, to achieve a full inhibition of the endochondral pathway, a whole class of anti-hypertrophic miRs, including miR-218, needs to be taken into consideration.

miR-152 Attenuates Apoptosis in Chondrocytes and Degeneration of Cartilages in Osteoarthritis Rats via TCF-4 Pathway

Introduction

Osteoarthritis (OA) is associated with deregulation of various miRNAs (miRs). The present study reported protective effect of miR-152 in osteoarthritis.

Methods

Tissue cartilage tissues of OA and normal subjects were used, rat model of anterior cruciate ligament transection (ACLT) was developed. Cartilage study was done by Safranin O-fast green, histological and immunostaining. The chondrocytes were isolated from tissues and were treated with IL-1β and infected with miR-152 or TCF-4 cloned lentiviral vectors. MTT assay was done for cell viability, apoptosis by Annexin-V-FITC staining. Expressions of proteins by western blot assay. Collagen-II assay was done by immunofluroscent assay. Luciferase activity by dual luciferase reporter assay.

Results

Upregulation of miR-152 improved viability of chondrocytes, decreased apoptosis and balanced the catabolic and anabolic factors of extracellular matrix in vitro. Injecting miR-152 lentivirus in rats improved articular cartilage in osteoarthritis ACLT rats. Bioinformatics analysis suggested TCF-4 as favorable target gene of miR-152, having binding site on the 3'UTR region of TCF-4 mRNA and inhibited the expression of TCF-4. Osteoarthritis tissue cartilage both from humans and rats showed expression of miR-152 inversely linked with expression of TCF-4.

Conclusion

Present study concludes miR-152 diminished the progression of osteoarthritis partially by inhibiting the expression of TCF-4.

Knockout of miR-21-5p alleviates cartilage matrix degradation by targeting Gdf5 in temporomandibular joint osteoarthritis

AIMS

The study aimed to determine whether the microRNA miR21-5p (MiR21) mediates temporomandibular joint osteoarthritis (TMJ-OA) by targeting growth differentiation factor 5 (Gdf5).

METHODS

TMJ-OA was induced in MiR21 knockout (KO) mice and wild-type (WT) mice by a unilateral anterior crossbite (UAC) procedure. Mouse tissues exhibited histopathological changes, as assessed by: Safranin O, toluidine blue, and immunohistochemistry staining; western blotting (WB); and quantitative real-time polymerase chain reaction (RT-qPCR). Mouse condylar chondrocytes were transfected with a series of MiR21 mimic, MiR21 inhibitor, Gdf5 siRNA (si-GDF5), and flag-GDF5 constructs. The effects of MiR-21 and Gdf5 on the expression of OA related molecules were evaluated by immunofluorescence, alcian blue staining, WB, and RT-qPCR.

RESULTS

UAC altered the histological structure and extracellular matrix content of cartilage in the temporomandibular joint (TMJ), and KO of MiR21 alleviated this effect (p < 0.05). Upregulation of MiR21 influenced the expression of TMJ-OA related molecules in mandibular condylar chondrocytes via targeting Gdf5 (p < 0.05). Gdf5 overexpression significantly decreased matrix metalloproteinase 13 (MMP13) expression (p < 0.05) and reversed the effects of MiR21 (p < 0.05).

CONCLUSION

MiR21, which acts as a critical regulator of Gdf5 in chondrocytes, regulates TMJ-OA related molecules and is involved in cartilage matrix degradation, contributing to the progression of TMJ-OA. Cite this article: Bone Joint Res 2020;9(10):689-700.

Down-regulation of MiR-138-5p Protects Chondrocytes ATDC5 and CHON-001 from IL-1 β-induced Inflammation Via Up-regulating SOX9

BACKGROUND

Osteoarthritis (OA) pertains to a chronic disease of degenerative joints distinguished by articular cartilage destruction, subchondral bone remodeling, osteophyte formation, and inflammatory changes. Chondrocyte apoptosis is inextricably linked to cartilage degeneration. SRY-related high-mobility-group-box 9 (SOX9) is a well-acknowledged transcription factor in the chondrogenesis. Nevertheless, the detailed function of miR-138-5p/SOX9 in OA remains to be fully clarified.

MATERIALS AND METHODS

qRT-PCR was performed to measure the expressions of miR-138-5p and SOX9 mRNA in OA and normal cartilage tissues and cells. Human chondrocyte cell lines, CHON-001 and ATDC5, were treated with different doses of interleukin-1β (IL-1β) to simulate the inflammatory response environment of OA. miR-138-5p mimics, miR-138-5p inhibitors, and SOX9 small interfering RNA (siRNA) were constructed and transfected into CHON-001 and ATDC5 cells. CCK-8 was conducted to determine the cell viability and transwell assay was used to monitor the migration of cells. Western blot was carried out to detect the expressions of apoptosis- related factors. Enzyme-linked immunosorbent assay (ELISA) was adopted to measure the contents of inflammatory factors. TargetScan predicted SOX9 was a target gene of miR-138-5p, which was then verified by luciferase assay.

RESULTS

miR-138-5p expression was down-regulated in OA and regulated SOX9 expression. The downregulation of miR-138-5p facilitated the proliferation and migration of CHON-001 and ATDC5 cells, while impeded their apoptosis and inflammatory response. Besides, down-regulated SOX9 can counteract the promoting effect of down-regulated miR-138-5p on the proliferation and migration of chondrocytes.

CONCLUSION

miR-138-5p can arrest the proliferation and migration of CHON-001 and ATDC5 via restraining SOX9, and facilitate the apoptosis and inflammation. This study revealed the protective effect of down-regulated miR-138-5p on the inflammatory injury of chondrocytes caused by IL-1β.

MicroRNA-613 alleviates IL-1β-induced injury in chondrogenic CHON-001 cells by targeting fibronectin 1

BACKGROUND

Osteoarthritis (OA) is an aging-related chronic degenerative joint disease. A number of miRNAs have been found to be involved in the development of OA, but the role of miR-613 in OA remains unclear. Thus, this study aimed to investigate the role of miR-613 during the progression of OA.

METHODS

CHON-001 cells were transfected with miR-613 agonist for 48 h, and then exposed to 10 ng/mL IL-1β for 24 h. Cell viability, cell proliferation and cell apoptosis in CHON-001 cells were assessed by CCK-8, immunofluorescence, and flow cytometry assays, respectively. In addition, the dual luciferase reporter system assay was used to determine the interaction of miR-613 and fibronectin 1 in CHON-001 cells.

RESULTS

The level of miR-613 was significantly decreased in IL-1β-treated CHON-001 cells. Overexpression of miR-613 markedly inhibited IL-1β-induced apoptosis in CHON-001 cells. In addition, upregulation of miR-613 obviously alleviated IL-1β-induced inflammatory response and cartilage matrix degradation in CHON-001 cells. Meanwhile, fibronectin 1 was identified as a direct binding target of miR-613 in CHON-001 cells. Overexpression of miR-613 alleviated IL-1β-induced injury in CHON-001 cells via downregulating the expression of fibronectin 1. Furthermore, overexpression of miR-613 alleviated cartilage degradation, and reduced OARSI scores and subchondral bone thickness in a mouse model of OA.

CONCLUSION

Our data indicated that overexpression of miR-613 could inhibit IL-1β-induced injury in CHON-001 cells via decreasing the level fibronectin 1 in vitro, and alleviate the symptoms of OA in vivo. Therefore, miR-613 might be a potential therapeutic option for the treatment of OA.

TGF-β1-induced expression of collagen type II and ACAN is regulated by 4E-BP1, a repressor of translation

Eukaryotic initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1) binds eIF4E and represses protein translation by displacing it from the mRNA. In this study, we investigated the influence of 4E-BP1 translational apparatus on the regulation of transforming growth factor-beta 1 (TGF-β1)-induced anabolic signaling in chondrocytes. The level of 4E-BP1 expression was significantly higher in human OA cartilage than normal cartilage. TGF-β1 increased total protein synthesis, including aggrecan (ACAN) and collagen type II (Col II), together with activation of Akt/mTOR signaling pathway. mTOR silencing significantly suppressed ACAN and Col II expressions through decreasing TGF-β1-induced phosphorylation of 4E-BP1. On the contrary, 4E-BP1 knockdown promoted total protein synthesis but suppressed Col II and ACAN expressions with decreased expression of Smad2/3 and Smad4 and increased expression of inhibitory Smad6 and Smad7. TGF-β1 suppressed the interaction of 4E-BP1 and eIF4E and subsequently enhanced protein synthesis. Furthermore, 4E-BP1 regulated translation levels of inhibitory Smads, which decreased the accumulation of nuclear Smad2/3 complexes on the promoter of ACAN and Col II genes, subsequently affecting transcription of ACAN and Col II. These results demonstrated that TGF-β1-modulated phosphorylation of 4EBP1 plays a role in the expression of Col II and ACAN through differential alteration of Smad signaling pathway.

The PI3K/AKT/mTOR signaling pathway in osteoarthritis: a narrative review

Osteoarthritis (OA) is a complicated degenerative disease that affects whole joint tissue. Currently, apart from surgical approaches to treat late stage OA, effective treatments to reverse OA are not available. Thus, the mechanisms leading to OA, and more effective approaches to treat OA should be investigated. According to available evidence, the PI3K/AKT/mTOR signaling pathway is essential for normal metabolism of joint tissues, but is also involved in development of OA. To provide a wide viewpoint to roles of PI3K/AKT/mTOR signaling pathway in osteoarthritis, a comprehensive literature search was performed using PubMed terms 'PI3K OR AKT OR mTOR' and 'osteoarthritis'. This review highlights the role of PI3K/AKT/mTOR signaling in cartilage degradation, subchondral bone dysfunction, and synovial inflammation, and discusses how this signaling pathway affects development of the disease. We also summarize recent evidences of therapeutic approaches to treat OA by targeting the PI3K/AKT/mTOR pathway, and discuss potential challenges in developing these strategies for clinical treatment of OA.

Long non-coding RNA SNHG15 is a competing endogenous RNA of miR-141-3p that prevents osteoarthritis progression by upregulating BCL2L13 expression

Increasing evidence has demonstrated that the dysregulated expression of long noncoding RNAs (lncRNAs) has important roles in the progression of osteoarthritis (OA), but the function of the lncRNA SNHG15 remains unclear. In the present study, we observed that SNHG15 was downregulated in OA cartilage tissues and IL-1β-induced chondrocytes. The lower expression of SNHG15 was negatively associated with the observed modified Mankin scale scores, extracellular matrix (ECM) degradation and chondrocyte apoptosis. Downregulated expression of SNHG15 increased chondrocyte viability and decreased chondrocyte apoptosis and ECM degradation in vitro and reduced damage to articular cartilage in vivo. Mechanistically, we demonstrated that SNHG15 overexpression promotes the expression of BCL2L13 by sponging miR-141-3p. The higher expression of miR-141-3p was negatively correlated with SNHG15 and BCL2L13 levels in OA cartilage tissues, and a positive correlation was also shown between SNHG15 and BCL2L13 levels. Furthermore, ectopic expression of miR-141-3p or knockdown of BCL2L13 expression could both reduce the effects of SNHG15 on chondrocyte proliferation, apoptosis and ECM degradation. Collectively, these findings reveal that SNHG15 inhibits OA progression by acting as an miR-141-3p sponge to promote BCL2L13 expression, suggesting that knockdown of SNHG15 expression in chondrocytes can be a potential therapeutic strategy to ameliorate OA progression.

Noncoding RNAs: New regulatory code in chondrocyte apoptosis and autophagy

Osteoarthritis (OA) is a bone and joint disease characterized by progressive cartilage degradation. In the face of global trends of population aging, OA is expected to become the fourth most common disabling disease by 2020. Nevertheless, the detailed pathogenesis of OA has not yet been elucidated. Noncoding RNAs (ncRNAs), including long noncoding RNAs, microRNAs, and circular RNAs, do not encode proteins but have recently emerged as important regulators of apoptosis and autophagy of chondrocytes, thereby highlighting a potential role in chondrocyte injury leading to OA onset and progression. We here review recent findings on these regulatory roles of ncRNAs to provide new directions for research on the pathogenesis of OA and offer new therapeutic targets for prevention and treatment. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA in Disease and Development > RNA in Development.

Carbonic Anhydrase 12 Protects Endplate Cartilage From Degeneration Regulated by IGF-1/PI3K/CREB Signaling Pathway

Lumbar intervertebral disc degeneration (IVDD) is the most common cause of low back pain (LBP). Among all the factors leading to IVDD, lumbar cartilage endplate (LCE) degeneration is considered a key factor. In the present study, we investigate the effect and regulation of carbonic anhydrase 12 (CA12) in LCE, which catalyzes hydration of CO₂ and participates in a variety of biological processes, including acid-base balance and calcification. Our results show that CA12, downregulated in degenerated LCE, could maintain anabolism and prevent calcification in the endplate. Furthermore, CA12 is regulated by the IGF-1/IGF-1R/PI3K/CREB signaling pathway. When we overexpressed CA12 in LCE, the decreased anabolism induced by inflammatory cytokine could be rescued. In contrast, reducing CA12 expression, either with siRNA, PI3Kinhibitor, or CREB inhibitor, could downregulate anabolism and cause apoptosis and then calcification in LCE. The protective effects of IGF-1 are even diminished with low-expressed CA12. Similar results are also obtained in an ex vivo model. Consequently, our results reveal a novel pathway, IGF-1/IGF-1R/PI3K/CREB/CA12, that takes a protective role in LCE degeneration by maintaining anabolism and preventing calcification and apoptosis. This study proposes a novel molecular target, CA12, to delay LCE degeneration.

Tanshinone I Inhibits IL-1β-Induced Apoptosis, Inflammation And Extracellular Matrix Degradation In Chondrocytes CHON-001 Cells And Attenuates Murine Osteoarthritis

Background

Osteoarthritis (OA) is a prevalent degenerative joint disease, which was characterized by inflammation and cartilage degradation. Accumulating evidence has demonstrated that Tanshinone I has an anti-inflammatory effect in various diseases. However, the efficacy of Tanshinone I as an anti-inflammatory agent in OA remains unclear. This study aimed to explore the role of Tanshinone I on OA both in vitro and in vivo.

Methods

CHON-001 cells were treated with IL-1β (10 ng/mL) for 72 hrs to induce OA model in vitro. Meanwhile, CHON-001 cells were pre-treated with 20 μM Tanshinone I for 24 hrs and then stimulated with IL-1β (10 ng/mL) for 72 hrs. CCK-8, immunofluorescence and flow cytometry assays were used to detect the viability, proliferation and apoptosis in CHON-001 cells, respectively. Western blotting assay was used to detect the levels of collagen II, aggrecan, MMP-13, cleaved caspase 1, Gasdermin D, SOX11 and p-NF-κB in CHON-001 cells. In addition, the mouse model of OA was built by anterior cruciate ligament transection (ACLT) in the right knee. Meanwhile, the mice were administrated with 10 or 30 mg/kg Tanshinone I for 8 weeks. Safranin-O/Fast Green staining was used to assess cartilage destruction in a mouse model of OA.

Results

In this study, IL-1β significantly induced apoptosis, extracellular matrix degradation and inflammatory response in CHON-001 cells. Tanshinone I significantly inhibited IL-1β-induced apoptosis in CHON-001 cells. In addition, the IL-1β-induced collagen II, aggrecan degradation, SOX11 downregulation, and MMP-13 and p-NF-κB upregulation in CHON-001 cells were notably reversed by Tanshinone I treatment. Moreover, Tanshinone I alleviated cartilage destruction and synovitis and reduced OARSI scores and subchondral bone thickness in a mouse model of OA.

Conclusion

Our findings showed that Tanshinone I could alleviate the progression of OA in vitro and in vivo. These results demonstrated that Tanshinone I might be regarded as a promising therapeutic agent for the treatment of OA.

CircRNA-104718 acts as competing endogenous RNA and promotes hepatocellular carcinoma progression through microRNA-218-5p/TXNDC5 signaling pathway

Accumulating evidences indicate that circular RNAs (circRNAs) play a vital role in diverse cancer biology. However, the contributions of circRNAs to hepatocellular carcinoma (HCC) and their underlying mechanism remain largely unknown. The present study aims at investigating the role of circRNA-104718 in HCC progression, which has been observed to be significantly up-regulated in HCC tissues. We found that, higher expression of circRNA-104718 also leds to a poor prognosis in HCC patients. Using luciferase binding assays and RNA immunoprecipitation studies, we identified circRNA-104718 is physically associated and co-expressed with microRNA (miR)-218-5p in HCC. Mechanistically, we demonstrated that circRNA-104718 functions as a competing endogenous RNAs (ceRNAs) and competes with thioredoxin domain-containing protein 5 (TXNDC5) mRNA and directly binds to miR-218-5p. Functionally, we found that ectopically expressed circRNA-104718 accelerated cell proliferation, migration, invasion, and inhibited apoptosis. In vivo studies on a nude mice model showed that circRNA-104718 overexpression could increase the tumor size and the rate of metastasis. Silencing of circRNA-104718 could decrease both the tumor size and metastasis significantly. Conversely, we also observed overexpression of miR-218-5p could in turn decrease the proliferation, migration, invasion, and increase apoptosis. Furthermore, circRNA-104718 could relieve the suppression of miR-218-5p target TXNDC5 and thereby cause an inhibition of miR’s functions. In summary, our results indicate that circRNA-104718 acts as a ceRNA and promotes HCC progression through the targeting of miR-218-5p/TXNDC5 signaling pathway. Thus, we propose that circRNA-104718 would be a promising target for HCC diagnosis and therapy.

MiR-218-5p Suppresses the Killing Effect of Natural Killer Cell to Lung Adenocarcinoma by Targeting SHMT1

PURPOSE

Lung adenocarcinoma (LA) is one of the major types of lung cancer. MicroRNAs (miRNAs) play an essential role in regulating responses of natural killer (NK) cells to cancer malignancy. However, the mechanism of miR-218-5p involved in the killing effect of NK cells to LA cells remains poorly understood.

MATERIALS AND METHODS

The expression of miR-218-5p was examined by quantitative real-time polymerase chain reaction (qRT-PCR). Serine hydroxymethyl transferase 1 (SHMT1) level was detected by qRT-PCR or western blots. Cytokines production of interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) were detected by ELISA. The killing effect of NK cells to LA cells was investigated using lactate dehydrogenase cytotoxicity assay kit. The interaction of miR-218-5p and SHMT1 was probed by luciferase activity assay. Xenograft model was established to investigate the killing effect of NK cells in vivo.

RESULTS

miR-218-5p was enhanced and SHMT1 was inhibited in NK cells of LA patients, whereas stimulation of interleukin-2 (IL-2) reversed their abundances. Addition of miR-218-5p reduced IL-2-induced cytokines expression and cytotoxicity in NK-92 against LA cells. Moreover, SHMT1 was negatively regulated by miR-218-5p and attenuated miR-218-5p-mediated effect on cytotoxicity, IFN-γ and TNF-α secretion in IL-2-activated NK cells. In addition, miR-218-5p exhaustion inhibited tumor growth by promoting killing effect of NK cells.

CONCLUSION

miR-218-5p suppresses the killing effect of NK cells to LA cells by targeting SHMT1, providing a potential target for LA treatment by ameliorating NK cells function.

miR-93-5p attenuates IL-1β-induced chondrocyte apoptosis and cartilage degradation in osteoarthritis partially by targeting TCF4

MicroRNAs (miRNAs, miRs) are frequently dysregulated in osteoarthritis (OA), but the role of specific miRNAs in OA remains unclear. In this study, we found that miR-93-5p is underexpressed in human and rat OA-affected cartilage (compared with normal cartilage) as well as in IL-1β-treated chondrocytes. Overexpression of miR-93-5p promoted chondrocyte viability, suppressed chondrocyte apoptosis, and maintained the balance between anabolic and catabolic factors of the extracellular matrix in vitro. Similarly, injection of a miR-93-5p-expressing lentivirus alleviated the destruction of articular cartilage in a rat model of OA (anterior cruciate ligament transection). Furthermore, TCF4 was identified as a direct target gene of miR-93-5p. miR-93-5p directly targeted the 3' untranslated region (3'-UTR) of TCF4 mRNA and repressed TCF4 expression. Overexpression of TCF4 attenuated the effects of miR-93-5p on chondrocyte apoptosis and functions. Finally, analyses of miR-93-5p and TCF4 in OA-affected cartilage tissues revealed that miR-93-5p expression inversely correlated with TCF4 expression. Altogether, these findings indicate that miR-93-5p slows OA progression partially by suppressing TCF4 expression, and this phenomenon may provide novel insights into the function of miRNA in OA.

Modulated Autophagy by MicroRNAs in Osteoarthritis Chondrocytes

Osteoarthritis (OA) is a chronic joint disease characterized by articular cartilage regression. The etiology of OA is diverse, the exact pathogenesis of which remains unclear. Autophagy is a conserved maintenance mechanism in eukaryotic cells. Dysfunction of chondrocyte autophagy is regarded as a crucial pathogenesis of cartilage degradation in OA. MircoRNAs (miRNAs) are a category of small noncoding RNAs, acting as posttranscriptional modulators that regulate biological processes and cell signaling pathways via target genes. A series of miRNAs are involved in the progression of chondrocyte autophagy and are connected with numerous factors and pathways. This article focuses on the mechanisms of chondrocyte autophagy in OA and reviews the role of miRNA in their modulation. Potentially relevant miRNAs are also discussed in order to provide new directions for future research and improve our understanding of the autophagic network of miRNAs.

circRNA.33186 Contributes to the Pathogenesis of Osteoarthritis by Sponging miR-127-5p

Osteoarthritis (OA), the most prevalent age-related joint disorder, is characterized by chronic inflammation, progressive articular cartilage destruction, and subchondral bone sclerosis. Accumulating evidences indicate that circular RNAs (circRNAs) play a critical role in various diseases, but the function of circRNAs in OA remains largely unknown. Here we showed that circRNA.33186 was significantly upregulated in IL-1β)-treated chondrocytes and in cartilage tissues of a destabilized medial meniscus (DMM)-induced OA mouse model. Knockdown of circRNA.33186 increased anabolic factor (type II collagen) expression and decreased catabolic factor (MMP-13) expression. Knockdown of circRNA.33186 also promoted proliferation and inhibited apoptosis in IL-1β-treated chondrocytes. Silencing of circRNA.33186 in vivo markedly alleviated DMM-induced OA. Mechanistic study showed that circRNA.33186 directly binds to and inhibits miR-127-5p, thereby increasing MMP-13 expression, and contributes to OA pathogenesis. Taken together, our findings demonstrated a fundamental role of circRNA.33186 in OA progression and provide a potential drug target in OA therapy.

MicroRNA‑93 inhibits chondrocyte apoptosis and inflammation in osteoarthritis by targeting the TLR4/NF‑κB signaling pathway

Osteoarthritis (OA) is a serious disease of the articular cartilage, and inflammation has been implicated in its pathogenesis. Previously, microRNAs (miRNAs) have been proposed as novel regulators of inflammation, however, the functional role of microRNAs in regulating inflammation in OA remains to be fully elucidated. The aim of the present study was to investigate the roles of miRNAs in OA inflammation and the underlying molecular mechanism. Firstly, the miRNA expression patterns were analyzed in the articular cartilage tissues from experimental OA mice using an miRNA microarray. miRNA (miR)-93 was identified with particular interest due to its reported effects on apoptosis and inflammation suppression. Subsequently, the expression of miR-93 was further validated in the articular cartilage tissues of OA mice and lipopolysaccharide (LPS)-stimulated primary chondrocytes. Using this LPS-induced chondrocyte injury model, the overexpression of miR-93 enhanced cell viability, improved cell apoptosis and attenuated the inflammatory response, as reflected by reductions in pro-inflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6. In addition, Toll-like receptor 4 (TLR4), an important regulator of the nuclear factor-κB (NF-κB) signaling pathway, was identified as a direct target of miR-93 in chondrocytes. Furthermore, the restoration of TLR4 markedly abrogated the inhibitory effects of miR-93 on the chondrocyte apoptosis and inflammation induced by LPS. In addition, the overexpression of miR-93 by agomir-miR-93 significantly inhibited the levels of pro-inflammatory cytokines and cell apoptosis, whereas antagomir-93 exacerbated apoptosis and inflammation in vivo. Taken together, the results of the study suggested that miR-93 may be a promising therapeutic target for the treatment of human OA.

Preclinical development of a microRNA-based therapy for intervertebral disc degeneration

Understanding the molecular mechanisms regulating the maintenance and destruction of intervertebral disc may lead to the development of new therapies for intervertebral disc degeneration (IDD). Here we present evidence from miRNA microarray analyses of clinical data sets along with in vitro and in vivo experiments that miR-141 is a key regulator of IDD. Gain- and loss-of-function studies show that miR-141 drives IDD by inducing nucleus pulposus (NP) apoptosis. Furthermore, miR-141 KO in mice attenuated spontaneous and surgically induced IDD. Mechanistically, miR-141 promotes IDD development by targeting and depleting SIRT1, a negative regulator of NF-κB pathway. Therapeutically, upregulation or downregulation of miR-141 by nanoparticle delivery in IDD model aggravated or alleviated experimental IDD, respectively. Our findings reveal a novel mechanism by which miR-141, in part, promotes IDD progression by interacting with SIRT1/NF-κB pathway. Blockade of miR-141 in vivo may serve as a potential therapeutic approach in the treatment of IDD.

Intervertebral disk degeneration (IDD) is characterized by changes in the nucleus pulposus (NP) extra cellular matrix that compromise disk structural integrity. In a miRNA screen of human IDD patient NP tissue, the authors identify deregulated miR-141 and show that direct injection of nanoparticle-coupled miR-141 into the NP alleviates IDD in mice.

microRNA-181a-5p antisense oligonucleotides attenuate osteoarthritis in facet and knee joints

OBJECTIVES

We recently identified microRNA-181a-5p (miR-181a-5p) as a critical mediator involved in the destruction of lumbar facet joint (FJ) cartilage. In this study, we tested if locked nucleic acid (LNA) miR-181a-5p antisense oligonucleotides (ASO) could be used as a therapeutic to limit articular cartilage degeneration.

METHODS

We used a variety of experimental models consisting of both human samples and animal models of FJ and knee osteoarthritis (OA) to test the effects of LNA-miR-181a-5p ASO on articular cartilage degeneration. Histopathological analysis including immunohistochemistry and in situ hybridisation were used to detect key OA catabolic markers and microRNA, respectively. Apoptotic/cell death markers were evaluated by flow cytometry. qPCR and immunoblotting were applied to quantify gene and protein expression.

RESULTS

miR-181a-5p expression was increased in human FJ OA and knee OA cartilage as well as injury-induced FJ OA (rat) and trauma-induced knee OA (mouse) cartilage compared with control cartilage, correlating with classical OA catabolic markers in human, rat and mouse cartilage. We demonstrated that LNA-miR-181a-5p ASO in rat and mouse chondrocytes reduced the expression of cartilage catabolic and chondrocyte apoptotic/cell death markers in vitro. Treatment of OA-induced rat FJ or mouse knee joints with intra-articular injections of in vivo grade LNA-miR-181a-5p ASO attenuated cartilage destruction, and the expression of catabolic, hypertrophic, apoptotic/cell death and type II collagen breakdown markers. Finally, treatment of LNA-miR-181a-5p ASO in cultures of human knee OA chondrocytes (in vitro) and cartilage explants (ex vivo) further demonstrated its cartilage protective effects.

CONCLUSIONS

Our data demonstrate, for the first time, that LNA-miR-181a-5p ASO exhibit cartilage-protective effects in FJ and knee OA.

miR‑204‑5p inhibits the occurrence and development of osteoarthritis by targeting Runx2

One of the hallmarks of osteoarthritis (OA) development is endochondral ossification, in which Runt-related transcription factor-2 (Runx2) is aberrantly expressed. Runx2 was previously identified to be regulated by microRNA-204-5p (miR-204-5p). The aim of the present study was to investigate the potential function of miR-204-5p regulating Runx2 during the development of OA and the underlying molecular mechanism. The expression levels of miR-204-5p and Runx2 were determined in tissue specimens. Rat OA models were established by transecting the anterior and posterior cruciate ligaments and removing the meniscus. Rats were treated with miR-204-5p agomir and miR-204-5p negative control (NC). All in vitro experiments were performed using rat primary chondrocytes and the SW-1353 human bone chondrosarcoma cell line. It was identified that the expression of miR-204-5p was significantly decreased, whereas Runx2 was significantly increased, in human OA tissues compared with in non-OA tissues, and levels were inversely associated with each other in primary chondrocytes and chondrosarcoma cells. Overexpression of miR-204-5p decreased the proliferation of chondrocytes and SW-1353 cells. Using a luciferase reporter assay, Runx2 was identified to be a direct target of miR-204-5p in chondrocytes and overexpressed miR-204-5p altered the expression of collagens II, X and matrix metalloproteinase (MMP)-1 and MMP-13 in primary chondrocytes and SW-1353 cells. Histological analysis revealed that miR-204-5p treatment ameliorated the OA-like phenotype that is reflected by assessment of cartilage thickness and Mankin's score. Runx2 expression was gradually increased as the rats increased in age. At 10 weeks of miR-204-5p agomir treatment, altered expression levels of collagens II and X, cartilage oligomeric matrix protein fragment, aggrecan, MMP-1 and MMP-13 were observed in the treatment group compared with the NC group. In conclusion, the results of the present study indicated that miR-204-5p decreases chondrocyte proliferation and ameliorates the OA-like phenotype in rats with surgically induced OA by targeting Runx2.

miR-296-3p Negatively Regulated by Nicotine Stimulates Cytoplasmic Translocation of c-Myc via MK2 to Suppress Chemotherapy Resistance

This study aimed to identify mechanisms by which microRNA 296-3p (miR-296-3p) functions as a tumor suppressor to restrain nasopharyngeal carcinoma (NPC) cell growth, metastasis, and chemoresistance. Mechanistic studies revealed that miR-296-3p negatively regulated by nicotine directly targets the oncogenic protein mitogen-activated protein kinase-activated protein kinase-2 (Mapkapk2) (MK2). Suppression of MK2 downregulated Ras/Braf/Erk/Mek/c-Myc and phosphoinositide-3-kinase (PI3K)/Akt/c-Myc signaling and promoted cytoplasmic translocation of c-Myc, which activated miR-296-3p expression by a feedback loop. This ultimately inhibited cell cycle progression, epithelial-to-mesenchymal transition (EMT), and chemoresistance of NPC. In addition, nicotine as a key component of tobacco was observed to suppress miR-296-3p and thus elevate MK2 expression by inducing PI3K/Akt/c-Myc signaling. In clinical samples, reduced miR-296-3p as an unfavorable factor was inversely correlated with MK2 and c-Myc expression. These results reveal a novel mechanism by which miR-296-3p negatively regulated by nicotine directly targets MK2-induced Ras/Braf/Erk/Mek/c-Myc or PI3K/AKT/c-Myc signaling to stimulate its own expression and suppress NPC cell proliferation and metastasis. miR-296-3p may thus serve as a therapeutic target to reverse chemotherapy resistance of NPC.