Epigenetics in osteoarthritis: Novel spotlight

Cardiovascular Mechano-Epigenetics: Force-Dependent Regulation of Histone Modifications and Gene Regulation

The local mechanical microenvironment impacts on the cell behavior. In the cardiovascular system, cells in both the heart and the vessels are exposed to continuous blood flow, blood pressure, stretching forces, and changing extracellular matrix stiffness. The force-induced signals travel all the way to the nucleus regulating epigenetic changes such as chromatin dynamics and gene expression. Mechanical cues are needed at the very early stage for a faultless embryological development, while later in life, aberrant mechanical signaling can lead to a range of pathologies, including diverse cardiovascular diseases. Hence, an investigation of force-generated epigenetic alteration at different time scales is needed to understand fully the phenotypic changes in disease onset and progression. That being so, cardiovascular mechano-epigenetics emerges as an attractive field of study. Given the rapid advances in this emergent field of research, this short review aims to provide an analysis of the state of knowledge of force-induced epigenetic changes in the cardiovascular field.

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

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

Tanshinone IIA Facilitates Efficient Cartilage Regeneration under Inflammatory Factors Caused Stress via Upregulating LncRNA NEAT1_2

(1) Background: Osteoarthritis (OA) is a crippling condition characterized by chondrocyte dedifferentiation, cartilage degradation, and subsequent cartilage defects. Unfortunately, there is a lack of effective medicines to facilitate the repair of cartilage defects in OA patients. In this study, we investigated the role of lncRNA NEAT1_2 in maintaining the chondrocyte phenotype and identified tanshinone IIA(TAN) as a natural medicine that enhances NEAT1_2 levels, resulting in efficient cartilage regeneration under inflammatory cytokines. (2) Methods: The transcriptional levels of NEAT1_2 and cartilage phenotype-related genes were identified by RT-qPCR. The siRNA interference approach was utilized to silence NEAT1_2; the Alamar Blue assay was performed to determine chondrocyte viability under inflammatory conditions. To evaluate the concentrations of collagen type II and glycosaminoglycans distributed by chondrocytes in vitro and in vivo, immunohistochemical staining and Safranin O staining were used. (3) Results: IL-1β suppresses NEAT1_2 and genes related to the chondrocytic phenotype, whereas TAN effectively upregulates them in a NEAT1_2-dependent manner. Consistently, TAN alleviated chondrocyte oxidative stress inhibited cartilage degradation by modulating the relevant genes and promoted efficient cartilage regeneration in vitro and in vivo when chondrocytes are exposed to inflammatory cytokines. (4) Conclusions: TAN enhances the expression of NEAT1_2 inhibited by IL-1β and affects the transcription of chondrocytic phenotype-related genes, which promotes cartilage regeneration in an inflammatory environment.

Osteoarthritis related epigenetic variations in miRNA expression and DNA methylation

Osteoarthritis (OA) is chronic arthritis characterized by articular cartilage degradation. However, a comprehensive regulatory network for OA-related microRNAs and DNA methylation modifications has yet to be established. Thus, we aimed to identify epigenetic changes in microRNAs and DNA methylation and establish the regulatory network between miRNAs and DNA methylation. The mRNA, miRNA, and DNA methylation expression profiles of healthy or osteoarthritis articular cartilage samples were downloaded from Gene Expression Omnibus (GEO) database, including GSE169077, GSE175961, and GSE162484. The differentially expressed genes (DEGs), differentially expressed miRNAs (DEMs), and differentially methylated genes (DMGs) were analyzed by the online tool GEO2R. DAVID and STRING databases were applied for functional enrichment analysis and protein-protein interaction (PPI) network. Potential therapeutic compounds for the treatment of OA were identified by Connectivity map (CMap) analysis. A total of 1424 up-regulated DEGs, 1558 down-regulated DEGs, 5 DEMs with high expression, 6 DEMs with low expression, 1436 hypermethylated genes, and 455 hypomethylated genes were selected. A total of 136 up-regulated and 65 downregulated genes were identified by overlapping DEGs and DEMs predicted target genes which were enriched in apoptosis and circadian rhythm. A total of 39 hypomethylated and 117 hypermethylated genes were obtained by overlapping DEGs and DMGs, which were associated with ECM receptor interactions and cellular metabolic processes, cell connectivity, and transcription. Moreover, The PPI network showed COL5A1, COL6A1, LAMA4, T3GAL6A, and TP53 were the most connective proteins. After overlapping of DEGs, DMGs and DEMs predicted targeted genes, 4 up-regulated genes and 11 down-regulated genes were enriched in the Axon guidance pathway. The top ten genes ranked by PPI network connectivity degree in the up-regulated and downregulated overlapping genes of DEGs and DMGs were further analyzed by the CMap database, and nine chemicals were predicted as potential drugs for the treatment of OA. In conclusion, TP53, COL5A1, COL6A1, LAMA4, and ST3GAL6 may play important roles in OA genesis and development.

Epigenetic Modifications of MiRNAs in Osteoarthritis: A Systematic Review on Their Methylation Levels and Effects on Chondrocytes, Extracellular Matrix and Joint Inflammation

Osteoarthritis (OA) is a joint disorder characterized by progressive degeneration of cartilage extracellular matrix (ECM), chondrocyte hypertrophy and apoptosis and inflammation. The current treatments mainly concern pain control and reduction of inflammation, but no therapeutic strategy has been identified as a disease-modifying treatment. Therefore, identifying specific biomarkers useful to prevent, treat or distinguish the stages of OA disease has become an immediate need of clinical practice. The role of microRNAs (miRNAs) in OA has been investigated in the last decade, and increasing evidence has emerged that the influence of the environment on gene expression through epigenetic processes contributes to the development, progression and aggressiveness of OA, in particular acting on the microenvironment modulations. The effects of epigenetic regulation, particularly different miRNA methylation during OA disease, were highlighted in the present systematic review. The evidence arising from this study of the literature conducted in three databases (PubMed, Scopus, Web of Science) suggested that miRNA methylation state already strongly impacts OA progression, driving chondrocytes and synoviocyte proliferation, apoptosis, inflammation and ECM deposition. However, the possibility of understanding the mechanism by which different epigenetic modifications of miRNA or pre-miRNA sequences drive the aggressiveness of OA could be the new focus of future investigations.

Emerging molecular biomarkers in osteoarthritis pathology

Osteoarthritis (OA) is the most common form of arthritis resulting in joint discomfort and disability, culminating in decline in life quality. Attention has been drawn in recent years to disease-associated molecular biomarkers found in readily accessible biofluids due to low invasiveness of acquisition and their potential to detect early pathological molecular changes not observed with traditional imaging methodology. These biochemical markers of OA have been found in synovial fluid, blood, and urine. They include emerging molecular classes, such as metabolites and noncoding RNAs, as well as classical biomarkers, like inflammatory mediators and by-products of degradative processes involving articular cartilage. Although blood-based biomarkers tend to be most studied, the use of synovial fluid, a more isolated biofluid in the synovial joint, and urine as an excreted fluid containing OA biomarkers can offer valuable information on local and overall disease activity, respectively. Furthermore, larger clinical studies are required to determine relationships between biomarkers in different biofluids, and their impacts on patient measures of OA. This narrative review provides a concise overview of recent studies of OA using these four classes of biomarkers as potential biomarker for measuring disease incidence, staging, prognosis, and therapeutic intervention efficacy.

Novel insights into the METTL3-METTL14 complex in musculoskeletal diseases

N6-methyladenosine (m⁶A) modification, catalyzed by methyltransferase complexes (MTCs), plays many roles in multifaceted biological activities. As the most important subunit of MTCs, the METTL3-METTL14 complex is reported to be the initial factor that catalyzes the methylation of adenosines. Recently, accumulating evidence has indicated that the METTL3-METTL14 complex plays a key role in musculoskeletal diseases in an m⁶A-dependent or -independent manner. Although the functions of m⁶A modifications in a variety of musculoskeletal diseases have been widely recognized, the critical role of the METTL3-METTL14 complex in certain musculoskeletal disorders, such as osteoporosis, osteoarthritis, rheumatoid arthritis and osteosarcoma, has not been systematically revealed. In the current review, the structure, mechanisms and functions of the METTL3-METTL14 complex and the mechanisms and functions of its downstream pathways in the aforementioned musculoskeletal diseases are categorized and summarized.

STAT3 promotes a youthful epigenetic state in articular chondrocytes

Epigenetic mechanisms guiding articular cartilage regeneration and age-related disease such as osteoarthritis (OA) are poorly understood. STAT3 is a critical age-patterned transcription factor highly active in fetal and OA chondrocytes, but the context-specific role of STAT3 in regulating the epigenome of cartilage cells remain elusive. In this study, DNA methylation profiling was performed across human chondrocyte ontogeny to build an epigenetic clock and establish an association between CpG methylation and human chondrocyte age. Exposure of adult chondrocytes to a small molecule STAT3 agonist decreased DNA methylation, while genetic ablation of STAT3 in fetal chondrocytes induced global hypermethylation. CUT&RUN assay and subsequent transcriptional validation revealed DNA methyltransferase 3 beta (DNMT3B) as one of the putative STAT3 targets in chondrocyte development and OA. Functional assessment of human OA chondrocytes showed the acquisition of progenitor-like immature phenotype by a significant subset of cells. Finally, conditional deletion of Stat3 in cartilage cells increased DNMT3B expression in articular chondrocytes in the knee joint in vivo and resulted in a more prominent OA progression in a post-traumatic OA (PTOA) mouse model induced by destabilization of the medial meniscus (DMM). Taken together these data reveal a novel role for STAT3 in regulating DNA methylation in cartilage development and disease. Our findings also suggest that elevated levels of active STAT3 in OA chondrocytes may indicate an intrinsic attempt of the tissue to regenerate by promoting a progenitor-like phenotype. However, it is likely that chronic activation of this pathway, induced by IL-6 cytokines, is detrimental and leads to tissue degeneration.

Extracellular vesicles in osteoarthritis of peripheral joint and temporomandibular joint

Osteoarthritis (OA) is a disabling disease with significant morbidity worldwide. OA attacks the large synovial joint, including the peripheral joints and temporomandibular joint (TMJ). As a representative of peripheral joint OA, knee OA shares similar symptoms with TMJ OA. However, these two joints also display differences based on their distinct development, anatomy, and physiology. Extracellular vesicles (EVs) are phospholipid bilayer nanoparticles, including exosomes, microvesicles, and apoptotic bodies. EVs contain proteins, lipids, DNA, micro-RNA, and mRNA that regulate tissue homeostasis and cell-to-cell communication, which play an essential role in the progression and treatment of OA. They are likely to partake in mechanical response, extracellular matrix degradation, and inflammatory regulation during OA. More evidence has shown that synovial fluid and synovium-derived EVs may serve as OA biomarkers. More importantly, mesenchymal stem cell-derived EV shows a therapeutic effect on OA. However, the different function of EVs in these two joints is largely unknown based on their distinct biological characteristic. Here, we reviewed the effects of EVs in OA progression and compared the difference between the knee joint and TMJ, and summarized their potential therapeutic role in the treatment of OA.

Modulation of MicroRNA Expression During In Vitro Chondrogenesis

Since their discovery in 1993, microRNAs (miRNAs) are now recognized as important epigenetic regulators of many mammalian cellular processes including proliferation, apoptosis, metabolism, and differentiation. These small non-coding RNAs function by interacting with specific regions in the 3'-untranslated region of mRNAs, thereby resulting in mRNA degradation or suppression of translation. Since miRNAs have the ability to target many mRNAs within a given cell type, a number of cellular pathways and networks may be regulated as a result. To study the function of miRNAs, a number of methods can be used to modulate their activity in cells such as synthetic mimics or antagomirs for short-term assays or viral-based approaches for longer-term experiments such as cell differentiation assays. In this chapter, we provide our methodology to constitutively overexpress a desired miRNA during in vitro chondrogenesis of human cartilage progenitor cells (CPCs). Specifically, we describe how we obtain CPCs from human articular cartilage specimens, how we generate and titrate lentivirus engineered to overexpress a precursor miRNA, how we transduce CPCs with lentivirus and differentiate them toward the chondrocyte lineage, and how we extract RNA and measure expression levels of the miRNA of interest during in vitro chondrogenesis. We also provide some data from our laboratory demonstrating that we can achieve and maintain miRNA overexpression for up to 14 days in cartilage pellet cultures. We predict that these lentiviral-based approaches will also be useful to study how miRNA modulation of progenitor cells affects cell differentiation and extracellular matrix production within three-dimensional biomaterial scaffolds.

Mesenchymal stem cells-derived microvesicles versus platelet-rich plasma in the treatment of monoiodoacetate-induced temporomandibular joint osteoarthritis in Albino rats

Temporomandibular joint osteoarthritis (TMJ-OA) is a serious disease, designated by severe joint pain and dysfunction. Limitations of current therapeutics have led to an increased interest in regenerative strategies. Recently, the non-surgical treatment of OA has seen increased use of biologic injectable therapies like mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP). Although these biotherapies represent an admirable effort, more studies are necessary to determine their efficacy. Thus, the aim of this study was to assess the curative potential of a single intra-articular injection of bone marrow MSCs-derived microvesicles (BM-MSCs-MVs) versus a single intra-articular injection of PRP in monoiodoacetate (MIA)-induced TMJ-OA model in Albino rats. Forty-eight male rats were used. A single intra-articular unilateral MIA injection was utilized to induce TMJ-OA. One week post induction, rats were sorted into 3 groups (16 rats each): group (I): received no treatment, groups (II) & (III): received BM-MSCs-MVs and PRP respectively. Scarification was done at 2 and 4 weeks from onset of treatment. Histological changes of the condylar TMJ were examined with H&E staining. Expression of IL-1β, TNF-α, NF-κB, MMP-13, MMP-3, and collagen ΙΙ markers was detected using real-time PCR. Histologically, the osteoarthritic group exhibited degenerated condylar tissues which were aggravated at 4 weeks. Oppositely, a marked improvement in the condylar TMJ histology was noticed in both the BM-MSCs-MVs-and PRP-treated groups at both time intervals. Additionally, the treated groups showed a decrease in IL-1β, TNF-α, NF-κB, MMP-13 and MMP-3 and an increase in collagen ΙΙ genes expression in contrast to the untreated group. Moreover, this difference was significant in the BM-MSCs-MVs group as compared to the PRP-treated group. Our results concluded that BM-MSCs-MVs as well as PRP treatments were able to target the key pathological features in OA, mainly inflammation and matrix degradation, and helped in restoring condylar structure in TMJ-OA rat model. However, BM-MSCs-MVs treatment exhibited more efficient therapeutic potential as compared to PRP treatment.

miR-150-5p and XIST interaction controls monocyte adherence: Implications for osteoarthritis therapy

Recent literature highlights the importance of microRNAs (miRNAs) functioning as diagnostic biomarkers and therapeutic agents in osteoarthritis (OA) and regulators of gene expression. In OA pathogenesis, cell adhesion molecules (CAMs), especially vascular cell adhesion protein 1 (VCAM-1), recruit monocyte infiltration to inflamed synovial tissues and thus accelerate OA progression. Up until now, little has been known about the regulatory mechanisms between miRNAs, long non-coding RNAs (lncRNAs) and VCAM-1 during OA progression. The evidence in this article emphasizes that the functional feature of miR-150-5p is an interaction with the lncRNA X-inactive specific transcript (XIST), which regulates VCAM-1-dependent monocyte adherence in OA synovial fibroblasts (OASFs). Levels of VCAM-1, CD11b (a monocyte marker) and XIST expression were higher in human synovial tissue samples and OASFs, while levels of miR-150-5p were lower in human OA synovial tissue compared with non-OA specimens. XIST enhanced VCAM-1-dependent monocyte adherence to OASFs. Upregulation of miR-150-5p inhibited the effects of XIST upon monocyte adherence. Administration of miR-150-5p effectively ameliorated OA severity in anterior cruciate ligament transection (ACLT) rats. The interaction of miR-150-5p and XIST regulated VCAM-1-dependent monocyte adherence and attenuated OA progression. Our findings suggest that miR-150-5p is a promising small-molecule therapeutic strategy for OA.

Assessment of the circulatory concentrations of cathepsin D, cathepsin K, and alpha-1 antitrypsin in patients with knee osteoarthritis

BACKGROUND

Evidence has shown that cysteine protease enzymes, such as cathepsin D, cathepsin A, cathepsin K, and alpha-1 antitrypsin (AAT) are involved in the chronic degenerative joint process. This study aimed to determine the potential involvement of cathepsin K, cathepsin D, and AAT in patients with osteoarthritis (OA).

METHODS

This study was performed on 31 patients with knee OA and 29 age- and sex-matched healthy subjects (both with Fars ethnicity from Iran). American College of Rheumatology (ACR) criteria were used to diagnose OA patients. The clinical status of the patients was scored by Western Ontario McMaster Universities Osteoarthritis (WOMAC), and pain intensity was measured by the Visual Analog Scale (VAS). The serum level of AAT was measured using high-resolution cellulose acetate electrophoresis. Additionally, serum levels of cathepsin D and cathepsin K were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The findings showed that the serum level of cathepsin K was significantly increased in OA patients compared to healthy subjects (P = 0.01), while there was no significant difference between serum level of cathepsin D in study groups (P = 0.2). In addition, the serum concentration of AAT was significantly decreased in OA patients compared to healthy subjects (P = 0.003). There was a significant correlation between WOMAC score and age (r = 0.644, P = 0.0001) and VAS (r = 0.866, P < 0.0001) in OA patients.

CONCLUSIONS

The decreased level of AAT in OA patients and a rise in serum level of cathepsin K are involved in the pathogenesis of OA via stimulation of bone resorption and cartilage degradation.

Epigenetic Regulation of Chondrocytes and Subchondral Bone in Osteoarthritis

The aim of this review is to provide an updated review of the epigenetic factors involved in the onset and development of osteoarthritis (OA). OA is a prevalent degenerative joint disease characterized by chronic inflammation, ectopic bone formation within the joint, and physical and proteolytic cartilage degradation which result in chronic pain and loss of mobility. At present, no disease-modifying therapeutics exist for the prevention or treatment of the disease. Research has identified several OA risk factors including mechanical stressors, physical activity, obesity, traumatic joint injury, genetic predisposition, and age. Recently, there has been increased interest in identifying epigenetic factors involved in the pathogenesis of OA. In this review, we detail several of these epigenetic modifications with known functions in the onset and progression of the disease. We also review current therapeutics targeting aberrant epigenetic regulation as potential options for preventive or therapeutic treatment.

Clinical Overview of Arthritis with a Focus on Management Options and Preventive Lifestyle Measures for Its Control

ABSTRACT:

Arthritis is the spectrum of conditions that cause swelling and tenderness of one or more body joints with key symptoms of joint pain and stiffness. Its progression is closely tied to age. Although there are a number of arthritis types, such as, ankylosing, gout, joint infections, juvenile idiopathic, reactive and septic; the two most common types are osteoarthritis and rheumatoid arthritis. Osteoarthritis causes the articulating smooth cartilage that covers the ends of bones, where they form a joint, to breakdown. Rheumatoid arthritis is a disease in which the immune system attacks joints, beginning with the cartilaginous lining of the joints. The latter is considered a systemic disease, i.e. affecting many parts of the body, but the respiratory system is involved in 10 to 20 % of all mortality. Osteoarthritis is one of the leading causes of disability globally. Several preventive measures to control arthritis have been suggested, such as the use of analgesics, non-steroid anti-inflammatory drugs, moderate to vigorous physical activity and exercise, reducing sedentary hours, getting adequate sleep and maintaining a healthy body weight. Foods including, a Mediterranean diet rich in fruits and vegetables, fish oil, medicinal plants and microbiota are vital protective methods. The intake of vitamins such as A and C, minerals e.g., selenium and zinc; poly unsaturated and n-3 fatty acids is also a significant preventive measures.

Anti-inflammatory and immunomodulatory effects of the extracellular vesicles derived from human umbilical cord mesenchymal stem cells on osteoarthritis via M2 macrophages

Osteoarthritis (OA) is a degenerative illness that greatly impacts the life quality of patients. Currently, the therapeutic approaches for OA are very limited in clinical. The extracellular vesicles (EVs) derived from different mesenchymal stem cells displayed a prominent therapeutic effect on OA. But most EVs have limited resources and the risks of host rejection, immunological response, and etc. Human umbilical cord mesenchymal stem cells (hUCMSCs) hold the advantages of easy availability, minimal immune rejection, and excellent immunomodulatory effects, although hUCMSCs-EVs have seldom been applied in OA. Herein, we investigated the potential immunomodulatory and anti-inflammatory effects of hUCMSCs-EVs on the treatment of OA. In our results, the treatment of hUCMSCs-EVs promoted the polarization of M2-type macrophages and the expression of anti-inflammation-related cytokines (IL-10). Notably, the supernate of M2 macrophages induced by hUCMSCs-EVs inhibited the level of inflammation-associated factors in OA chondrocytes caused by IL-1β. Further, injection of hUCMSCs-EVs in the articular lumen ameliorated progression of OA and exerted chondroprotective potential based on the OA joint model created by the surgical transection of the anterior cruciate ligament (ACLT). In addition, we found five highly enriched miRNAs in hUCMSCs-EVs, including has-miR-122-5p, has-miR-148a-3p, has-miR-486-5p, has-miR-let-7a-5p, and has-miR-100-5p by High-throughput sequencing of miRNAs, with targeted genes mainly enriched in the PI3K-Akt signaling pathway. Furthermore, we also detected the protein abundance of hUCMSCs-EVs using liquidation chromatography with tandem quadrupole mass spectrometry (LC–MS/MS) analysis. Thus, our study indicates that hUCMSCs-EVs can alleviate cartilage degradation during the OA progression, mechanically may through delivering key proteins and modulating the PI3K-Akt signaling pathway mediated by miRNAs to promote polarization of M2 macrophage, exhibiting potent immunomodulatory potential. The current findings suggest that hUCMSCs-EVs might serve as a new reagent for the therapy of OA.

Graphical Abstract

Small non-coding RNA landscape of extracellular vesicles from a post-traumatic model of equine osteoarthritis

Extracellular vesicles comprise an as yet inadequately investigated intercellular communication pathway in the field of early osteoarthritis. We hypothesised that the small non-coding RNA expression pattern in synovial fluid and plasma would change during progression of experimental osteoarthritis. In this study, we conducted small RNA sequencing to provide a comprehensive overview of the temporal expression profiles of small non-coding transcripts carried by extracellular vesicles derived from plasma and synovial fluid for the first time in a posttraumatic model of equine osteoarthritis. Additionally, we characterised synovial fluid and plasma-derived extracellular vesicles with respect to quantity, size, and surface markers. The different temporal expressions of seven microRNAs in plasma and synovial fluid-derived extracellular vesicles, eca-miR-451, eca-miR-25, eca-miR-215, eca-miR-92a, eca-miR-let-7c, eca-miR-486-5p, and eca-miR-23a, and four snoRNAs, U3, snord15, snord46, and snord58, represent potential biomarkers for early osteoarthritis. Bioinformatics analysis of the differentially expressed microRNAs in synovial fluid highlighted that in early osteoarthritis these related to the inhibition of cell cycle, cell cycle progression, DNA damage and cell proliferation as well as increased cell viability and differentiation of stem cells. Plasma and synovial fluid-derived extracellular vesicle small non-coding signatures have been established for the first time in a temporal model of osteoarthritis. These could serve as novel biomarkers for evaluation of osteoarthritis progression or act as potential therapeutic targets.

Advances in single-cell sequencing and its application to musculoskeletal system research

In recent years, single-cell sequencing (SCS) technologies have continued to advance with improved operating procedures and reduced cost, leading to increasing practical adoption among researchers. These emerging technologies have superior abilities to analyse cell heterogeneity at a single-cell level, which have elevated multi-omics research to a higher level. In some fields of research, application of SCS has enabled many valuable discoveries, and musculoskeletal system offers typical examples. This article reviews some major scientific issues and recent advances in musculoskeletal system. In addition, combined with SCS technologies, the research of cell or tissue heterogeneity in limb development and various musculoskeletal system clinical diseases also provides new possibilities for treatment strategies. Finally, this article discusses the challenges and future development potential of SCS and recommends the direction of future applications of SCS to musculoskeletal medicine.

Autophagy and Polyphenols in Osteoarthritis: A Focus on Epigenetic Regulation

Autophagy is an intracellular mechanism that maintains cellular homeostasis in different tissues. This process declines in cartilage due to aging, which is correlated with osteoarthritis (OA), a multifactorial and degenerative joint disease. Several studies show that microRNAs regulate different steps of autophagy but only a few of them participate in OA. Therefore, epigenetic modifications could represent a therapeutic opportunity during the development of OA. Besides, polyphenols are bioactive components with great potential to counteract diseases, which could reverse altered epigenetic regulation and modify autophagy in cartilage. This review aims to analyze epigenetic mechanisms that are currently associated with autophagy in OA, and to evaluate whether polyphenols are used to reverse the epigenetic alterations generated by aging in the autophagy pathway.

Role of microRNA Shuttled in Small Extracellular Vesicles Derived From Mesenchymal Stem/Stromal Cells for Osteoarticular Disease Treatment

Osteoarticular diseases (OD), such as rheumatoid arthritis (RA) and osteoarthritis (OA) are chronic autoimmune/inflammatory and age-related diseases that affect the joints and other organs for which the current therapies are not effective. Cell therapy using mesenchymal stem/stromal cells (MSCs) is an alternative treatment due to their immunomodulatory and tissue differentiation capacity. Several experimental studies in numerous diseases have demonstrated the MSCs’ therapeutic effects. However, MSCs have shown heterogeneity, instability of stemness and differentiation capacities, limited homing ability, and various adverse responses such as abnormal differentiation and tumor formation. Recently, acellular therapy based on MSC secreted factors has raised the attention of several studies. It has been shown that molecules embedded in extracellular vesicles (EVs) derived from MSCs, particularly those from the small fraction enriched in exosomes (sEVs), effectively mimic their impact in target cells. The biological effects of sEVs critically depend on their cargo, where sEVs-embedded microRNAs (miRNAs) are particularly relevant due to their crucial role in gene expression regulation. Therefore, in this review, we will focus on the effect of sEVs derived from MSCs and their miRNA cargo on target cells associated with the pathology of RA and OA and their potential therapeutic impact.

Evaluation of the Effect of Cannabidiol on Naturally Occurring Osteoarthritis-Associated Pain: A Pilot Study in Dogs

The objective of this study was to provide preliminary data describing the safety and effect of cannabidiol (CBD) for symptom relief of canine osteoarthritis-associated pain in a clinical setting using objective outcome measures. Twenty-three client-owned dogs with naturally occurring osteoarthritis of appendicular joints completed this prospective, double-blinded, crossover, placebo-controlled study. Baseline data were acquired for 4 wk, followed by random allocation to either placebo or CBD treatment for 6 wk, followed by 6 wk with the opposite treatment. Outcome measures included objective gait analysis, activity counts (via accelerometry) and clinical metrology instruments. There were no differences noted between groups at any time point for any of the recorded outcome measures. Adverse events associated with CBD administration included elevation in liver enzymes (n = 14) and vomiting (n = 2).

Blocking HOTAIR protects human chondrocytes against IL-1β-induced cell apoptosis, ECM degradation, inflammatory response and oxidative stress via regulating miR-222-3p/ADAM10 axis

BACKGROUND

Long non-coding RNA (lncRNA) HOX transcript antisense RNA (HOTAIR) contributes to cartilage damages including osteoarthritis (OA). While, its role and mechanism in chondrocytes is incompletely clear.

METHODS

HOTAIR, microRNA (miR)-222-3p and ADAM metalloproteinase-like domain 10 (ADAM10) expressions were detected by real-time quantitative PCR and western blotting. The interaction between miR-222-3p and HOTAIR or ADAM10 was confirmed by dual-luciferase reporter assay. Cell injury was measured by MTS method, flow cytometry, western blotting, enzyme-linked immunosorbent assay for collagen Type II, type X, sex determining region Y-box 9 (SOX9), matrix metalloproteinase (MMP)-13, interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-α, and special assay kits for malondialdehyde (MDA), reactive oxygen species (ROS) and superoxide dismutase (SOD).

RESULTS

HOTAIR was highly expressed in human OA cartilages and IL-1β-induced OA model in immortalized chondrocytes (C-28/I2). Under IL-1β stress, blocking HOTAIR was responsible to high mitochondrial activity and low early apoptosis rate, accompanied with increased B cell lymphoma (Bcl)-2 and LC3B-II/I proteins, boosted IL-10 and SOD productions, suppressed cleaved caspase-3 and p62 proteins, and decreased MDA and ROS levels, as well as elevated secretions of Type II collagen, Type X collagen, SOX9, MMP-13, IL-6, and TNF-α. Moreover, miR-222-3p was a target of HOTAIR, and its overexpression and knockdown could suppress and aggravate IL-1β-induced chondrocytes injury. Furthermore, restoring ADAM10, a target gene of miR-222-3p, counteracted the protective role of miR-222-3p upregulation.

CONCLUSION

HOTAIR might contribute to IL-1β-induced chondrocytes death, inflammation, extracellular matrix degradation, and oxidative stress in OA via miR-222-3p/ADAM10 axis.

Human bone mesenchymal stem cells-derived exosomal miRNA-361-5p alleviates osteoarthritis by downregulating DDX20 and inactivating the NF-κB signaling pathway

Osteoarthritis (OA) is a chronic disease featured by joint hyperplasia, deterioration of articular cartilage, and progressive degeneration. Abnormal expression of microRNAs (miRNAs) has been found to be implicated in the pathological process of OA. In this study, the role of miR-361-5p transferred by exosomes derived from human bone mesenchymal stem cells (hBMSCs) in OA was investigated. The expression of Asp-Glu-Ala-Asp-box polypeptide 20 (DDX20) and miR-361-5p in interleukin-1β (IL-1β)-treated chondrocytes was determined by reverse transcription quantitative polymerase chain reaction. DDX20 was knocked down by transfection of short hairpin RNA targeting DDX20, and the effects of DDX20 downregulation on IL-1β-induced damage of chondrocytes were detected. The interaction between DDX20 and miR-361-5p was tested by luciferase report assay. hBMSCs-derived exosomes loaded with miR-361-5p were co-incubated with chondrocytes followed by detection of cell viability, proliferation and inflammatory response. An OA rat model was established to further explore the role of miR-361-5p in vivo. Western blot, luciferase reporter and immunofluorescence staining assays were used to evaluate the activation of the nuclear factor kappa-B (NF-κB) signaling pathway. We found that DDX20 was upregulated, while miR-361-5p was underexpressed in IL-1β-treated chondrocytes. Downregulation of DDX20 inhibits levels of matrix metalloproteinases (MMPs) and suppresses inflammation induced by IL-1β. Mechanistically, miR-361-5p was verified to directly target DDX20. In addition, hBMSC-derived exosomes-transferred miR-361-5p alleviates chondrocyte damage and inhibits the NF-κB signaling pathway via targeting DDX20. Inhibition of NF-κB signaling reverses the effect of overexpressed DDX20 on IL-1β-induced chondrocyte damage. Moreover, exosomal miR-361-5p alleviates OA damage in vivo. Overall, hBMSC-derived exosomal miR-361-5p alleviates OA damage by targeting DDX20 and inactivating the NF-κB signaling pathway.

Analysis of mRNA Expression and DNA Methylation Datasets According to the Genomic Distribution of CpG Sites in Osteoarthritis

Objectives Transcriptional changes in cartilage can impact function by causing degradation such as that which occurs during the development of osteoarthritis (OA). Epigenetic regulation may be a key factor leading to transcriptional changes in OA. In this study, we performed a combined analysis of DNA methylation and gene expression microarray datasets and identified key transcription factors (TFs) central to the regulation of gene expression in OA. Methods A DNA methylation profile dataset (GSE63106) and a gene expression profiling dataset (GSE114007) were extracted from the Gene Expression Omnibus (GEO). We used ChAMP methylation analysis and the Limma package to identify differentially methylation genes (DMGs) and differentially expressed genes (DEGs) from normal and human knee cartilage samples in OA. Function enrichment analysis of DMGs was conducted using the DAVID database. A combined analysis of DEGs and DMGs was conducted to identify key TFs in OA. We then validated the mRNA expression of selected TFs in normal and OA cartilage by RT-qPCR. Primary chondrocytes were cultured and treated with the DNA methylation inhibitor 5-Aza-2-deoxycytidine (5-Aza) for functional validation. Results We identified 2,170 differential methylation sites (DMS) containing 1005 genes and 1986 DEGs between normal human and OA cartilage. Functional analysis of DMGs revealed that focal adhesion, extracellular matrix (ECM)-receptor interactions, the PI3K-Akt signaling pathway, and the FoxO signaling pathway were involved in OA. Integrated analysis showed a subset of 17 TFs. Four TFs (ELF3, SOX11, RARA, and FOXD2) were validated. RT-qPCR results showed the mRNA expression of SOX11, RARA, and FOXD2 were consistent with the results from the mRNA expression data. However, the expression of ELF3 could not be validated. Upon 5-Aza-2'-deoxycytidine (5-Aza) treatment, the mRNA levels of ELF3 and SOX11 were down-regulated, whilst RARA was up-regulated, and FOXD2 showed no significant change in expression level. Conclusions the effect of DNA methylation on the transcriptional regulation is related to the distribution of methylated sites across the genome. Epigenetic studies on the positions of DMS in transcriptional units can inform a better understanding of the function of DNA methylation and its transcription regulation.

Data Integration Reveals the Potential Biomarkers of Circulating MicroRNAs in Osteoarthritis

The abnormal expression of circulating miRNAs (c-miRNAs) has become an emerging field in the development of miRNAs-based diagnostic and therapeutic tools for human diseases, including osteoarthritis (OA). OA is the most common form of arthritis leading to disability and a major socioeconomic burden. The abnormal expression of miRNAs plays important roles in the pathogenesis of OA. Unraveling the role of miRNAs in the pathogenesis of OA will throw light on the potential for the development of miRNAs-based diagnostic and therapeutic tools for OA. This article reviews and highlights recent advances in the study of miRNAs in OA, with specific demonstration of the functions of miRNA, especially c-miRNA, in OA pathogenesis as well as its potential implication in the treatment of OA. Based on a systematic literature search using online databases, we figured out the following main points: (1) the integrative systematic review of c-mRNAs and its target genes related to OA pathogenesis; (2) the potential use of c-miRNAs for OA diagnosis purposes as potential biomarkers; and (3) for therapeutic purposes, and we also highlight certain remedies that regulate microRNA expression based on its target genes.

Comprehensive analysis of lncRNA and mRNA based on expression microarray profiling reveals different characteristics of osteoarthritis between Tibetan and Han patients

Background

Osteoarthritis (OA) is thought to be the most prevalent chronic joint disease, especially in Tibet of China. Here, we aimed to explore the integrative lncRNA and mRNA landscape between the OA patients of Tibet and Han.

Methods

The lncRNA and mRNA expression microarray profiling was performed by SurePrint G3 Human Gene Expression 8x60K v2 Microarray in articular cartilage samples from OA patients of Han nationality and Tibetans, followed by GO, KEGG, and trans-regulation and cis-regulation analysis of lncRNA and mRNA.

Results

We found a total of 117 lncRNAs and 297 mRNAs differently expressed in the cartilage tissues of Tibetans (n = 5) comparing with those of Chinese Han (n = 3), in which 49 lncRNAs and 158 mRNAs were upregulated, and 68 lncRNAs and 139 mRNAs were downregulated. GO and KEGG analysis showed that several unreported biological processes and signaling pathways were particularly identified. LncRNA-mRNA co-expression analysis revealed a remarkable lncRNA-mRNA relationship, in which OTOA may play a critical role in the different mechanisms of the OA progression between Tibetans and Chinese Han.

Conclusion

This study identified different lncRNA/mRNA expression profiling between OA patients of Tibetans and Han, which were involved in many characteristic biological processes and signaling pathways.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02213-y.

Understanding osteoarthritis pathogenesis: a multiomics system-based approach

PURPOSE OF REVIEW

Osteoarthritis is a heterogeneous, multifactorial condition regulated by complex biological interactions at multiple levels. Comprehensive understanding of these regulatory interactions is required to develop feasible advances to improve patient outcomes. Improvements in technology have made extensive genomic, transcriptomic, epigenomic, proteomic, and metabolomic profiling possible. This review summarizes findings over the past 20 months related to omics technologies in osteoarthritis and examines how using a multiomics approach is necessary for advancing our understanding of osteoarthritis as a disease to improve precision osteoarthritis treatments.

RECENT FINDINGS

Using the search terms 'genomics' or 'transcriptomics' or 'epigenomics' or 'proteomics' or 'metabolomics' and 'osteoarthritis' from January 1, 2018 to August 31, 2019, we identified advances in omics approaches applied to osteoarthritis. Trends include untargeted whole genome, transcriptome, proteome, and metabolome analyses leading to identification of novel molecular signatures, cell subpopulations and multiomics validation approaches.

SUMMARY

To address the complexity of osteoarthritis, integration of multitissue analyses by multiomics approaches with the inclusion of longitudinal clinical data is necessary for a comprehensive understanding of the disease process, and for appropriate development of efficacious diagnostics, prognostics, and biotherapeutics.

Vitamin D and Lung Cancer; Association, Prevention, and Treatment

Lung cancer is one of the common types of malignant disorders and the most prevalent cause of cancer-related mortality in the world. Although a wide range of approaches has been examined, strategies in prevention and treatment of lung cancer are still inadequate. Studies show that Vitamin D (VitD) is involved in various biological pathways and has been associated with the etiopathogenesis of several diseases, like cancers. In Vitro and In Vivo experiments have disclosed that VitD plays immunomodulatory and anti-tumor functions. Several lines of evidence have indicated that VitD is involved in the inflammatory settings of the lung. Epidemiological studies have reported that sufficient levels of VitD might be critical in the prevention of lung cancer. Polymorphisms in the genes encoding the different molecules involved in the signaling of VitD might affect the lung cancer risk as well as the quality and quantity of responses to different treatments. In this review article, we intended to clarify the implications of VitD in the normal biology and physiology of the lung and discuss diverse line of evidence about the possible role of VitD in the prevention or treatment of lung cancer.

LncRNA NEAT1 regulates chondrocyte proliferation and apoptosis via targeting miR-543/PLA2G4A axis

Osteoarthritis (OA), which is characterized by articular cartilage degeneration, shows a gradually increasing incidence with age. This study explored the molecular mechanism underlying the proliferation and apoptosis of chondrocytes during OA progression. In this study, chondrocytes were isolated from human knee cartilages. The targeted relationship among nuclear enriched abundant transcript 1 (NEAT1), microRNA-543 (miR-543) and PLA2G4A was predicted on TargetScan V7.2 and starBase and validated by performing dual-luciferase reporter assay. High-expressed NEAT1 was detected in OA cartilage and chondrocytes. NEAT1 was negatively correlated with miR-543 and was low-expressed in OA cartilage and PLA2G4A was negatively correlated with miR-543 and was high-expressed in OA cartilage. In OA chondrocytes, the overexpressed NEAT1 inhibited the expressions of p-Akt1 and Bcl-2 and upregulated that of matrix metalloprotease (MMP)-3, MMP-9, MMP-13, interleukin (IL)-6 and IL-8, but such effects of overexpressed NEAT1 were reversed by miR-543 mimic. SiRNA-NEAT1 exerted an opposite effect to NEAT1 overexpression on OA chondrocytes, but this could be reversed by miR-543 inhibitor. The effect of PLA2G4A overexpression was the opposite to miR-543 mimic on OA chondrocytes. In conclusion, NEAT1 could sponge miR-543 to induce PLA2G4A expression, inhibit chondrocyte proliferation and promote apoptosis.

MiR-155 promotes interleukin-1β-induced chondrocyte apoptosis and catabolic activity by targeting PIK3R1-mediated PI3K/Akt pathway

Osteoarthritis (OA) is a common joint disease characterized by progressive cartilage degradation, in which elevated chondrocyte apoptosis and catabolic activity play an important role. MicroRNA-155 (miR-155) has recently been shown to regulate apoptosis and catabolic activity in some pathological circumstances, yet, whether and how miR-155 is associated with OA pathology remain unexplored. We report here that miR-155 level is significantly up-regulated in human OA cartilage biopsies and also in primary chondrocytes stimulated by interleukin-1β (IL-1β), a pivotal pro-catabolic factor promoting cartilage degradation. Moreover, miR-155 inhibition attenuates and its overexpression promotes IL-1β-induced apoptosis and catabolic activity in chondrocytes in vitro. We also demonstrate that the PIK3R1 (p85α regulatory subunit of phosphoinositide 3-kinase (PI3K)) is a target of miR-155 in chondrocytes, and more importantly, PIK3R1 restoration abrogates miR-155 effects on chondrocyte apoptosis and catabolic activity. Mechanistically, PIK3R1 positively regulates the transduction of PI3K/Akt pathway, and a specific Akt inhibitor reverses miR-155 effects on promoting chondrocyte apoptosis and catabolic activity, phenocopying the results obtained via PIK3R1 knockdown, hence establishing that miR-155 promotes chondrocyte apoptosis and catabolic activity through targeting PIK3R1-mediated PI3K/Akt pathway activation. Altogether, our study discovers novel roles and mechanisms of miR-155 in regulating chondrocyte apoptosis and catabolic activity, providing an implication for therapeutically intervening cartilage degradation and OA progression.

Regulatory T Cells in Bioactive Peptides-Induced Oral Tolerance; a Two-Edged Sword Related to the Risk of Chronic Diseases: A Systematic Review

This systematic review assesses the literature regarding beneficial and potential detrimental effects of bioactive peptides (BPs), focusing on evidence of regulatory T cells (T-regs) mediated oral tolerance (OT), collagen hydrolysate (CH) supplementation in osteoarthritis (OA) and the association of T-regs with chronic disease. The systematic search was done for articles published from inception to April 2019 using the PubMed and Scopus databases. About 3081 papers were identified by three different search strategies and screened against inclusion criteria which resulted in the inclusion of 22 articles. From the included articles, 12 papers were related to treatment of different disease in vivo by oral administration of BPs, six articles evaluated the effects of CH supplementation, as a rich source of BPs, on OA pain-relief and four observational studies assessed the association of circulating T-regs and risk of cancer and cardiovascular disease (CVD). The evidence obtained from first search strategy, indicated that oral administration of BPs improve clinical manifestations of animal models of allergy, arthritis, atherosclerosis, ulcerative colitis and allograft rejection by T-regs expansion; while, observational studies showed that although higher levels of circulating T-regs reduced risk of CVD and allergy, but, increased risk of solid cancers.

MiR-455-3p reduces apoptosis and alleviates degeneration of chondrocyte through regulating PI3K/AKT pathway

AIMS

This study aimed to explore the functions of miR-455-3p, PTEN, and PI3K/AKT pathway in osteoarthritis.

MATERIALS AND METHODS

We used the human bone marrow stem cell (BMSC), healthy chondrocytes, osteoarthritis chondrocytes (OA), and the IL-1β/TNF-α-treated chondrocyte model to explore the relationship between miR-455-3p and PTEN. Mimic or inhibitor was used to transfect chondrocytes to determine whether miR-455-3p can regulate PTEN and influence COL2A1 and MMP13. Apoptosis was detected by flow cytometry. A luciferase report was applied to verify the targeted binding. KO mice were applied to investigate PTEN and pAKT expression and the effect on chondrocytes in vivo.

KEY FINDINGS

MiR-455-3p and PTEN were reverse in chondrogenesis and healthy cartilage versus OA cartilage. Similar trends were noted in IL-1β model. PTEN and MMP13 decreased and COL2A1 increased after overexpressing miR-455-3p, whereas the inhibition showed opposite results. Flow cytometry showed that miR-455-3p could reduce the apoptosis of chondrocytes. The results of luciferase revealed that miR-455-3p could affect fluorescence activity of PTEN by targeting its 3'-UTR. Finally, we found a marked increased in the expression of PTEN in KO mice relative to WT mice, while pAKT levels decreased.

SIGNIFICANCE

It can be supported that miR-455-3p can reduce the apoptosis of chondrocytes and alleviate OA through regulating PI3K/AKT pathway, which may be expected to be a target for the treatment of osteoarthritis.

Nanotechnological Strategies for Osteoarthritis Diagnosis, Monitoring, Clinical Management, and Regenerative Medicine: Recent Advances and Future Opportunities

PURPOSE OF REVIEW

In this review article, we discuss the potential for employing nanotechnological strategies for the diagnosis, monitoring, and clinical management of osteoarthritis (OA) and explore how nanotechnology is being integrated rapidly into regenerative medicine for OA and related osteoarticular disorders.

RECENT FINDINGS

We review recent advances in this rapidly emerging field and discuss future opportunities for innovations in enhanced diagnosis, prognosis, and treatment of OA and other osteoarticular disorders, the smart delivery of drugs and biological agents, and the development of biomimetic regenerative platforms to support cell and gene therapies for arresting OA and promoting cartilage and bone repair. Nanotubes, magnetic nanoparticles, and other nanotechnology-based drug and gene delivery systems may be used for targeting molecular pathways and pathogenic mechanisms involved in OA development. Nanocomposites are also being explored as potential tools for promoting cartilage repair. Nanotechnology platforms may be combined with cell, gene, and biological therapies for the development of a new generation of future OA therapeutics. Graphical Abstract.

RETRACTED: Human bone mesenchymal stem cells-derived exosomes overexpressing microRNA-26a-5p alleviate osteoarthritis via down-regulation of PTGS2

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 Figures 2E, 3D and F, 4B, E+G, 5D+I, and 6D+F, which appear to have a similar phenotype as contained in many other publications, detailed here: https://pubpeer.com/publications/73C0A79F5EDF9ECC9818CE2D9B2A09; and here: https://docs.google.com/spreadsheets/d/1r0MyIYpagBc58BRF9c3luWNlCX8VUvUuPyYYXzxWvgY/edit#gid=262337249. The provenance of the flow cytometry data in Figure 5A was also questioned, as it appeared to have histograms that were hand drawn. The journal requested the corresponding author comment on these concerns and provide the raw data. The authors did not respond to this request and therefore the Editor-in-Chief decided to retract the article.

Osteoarthritis from evolutionary and mechanistic perspectives

Developmental osteogenesis and the pathologies associated with tissues that normally are mineralized are active areas of research. All of the basic cell types of skeletal tissue evolved in early aquatic vertebrates. Their characteristics, transcription factors, and signaling pathways have been conserved, even as they adapted to the challenge imposed by gravity in the transition to terrestrial existence. The response to excess mechanical stress (among other factors) can be expressed in the pathologic phenotype described as osteoarthritis (OA). OA is mediated by epigenetic modification of the same conserved developmental gene networks, rather than by gene mutations or new chemical signaling pathways. Thus, these responses have their evolutionary roots in morphogenesis. Epigenetic channeling and heterochrony, orchestrated primarily by microRNAs, maintain the sequence of these responses, while allowing variation in their timing that depends at least partly on the life history of the individual.

DNA methyltransferase genes polymorphisms are associated with primary knee osteoarthritis: a matched case-control study

DNA methylation is an epigenetic mechanism involved in the development of primary osteoarthritis (OA). The association between DNA methyltransferases (DNMTs) genes polymorphisms and diseases in which DNA methylation plays a role in their pathogenesis has been described (e.g., cancer); however, its relationship with OA has not been investigated. The aim of this study was to analyze the association between DNMT1, DNMT3A, and DNMT3B polymorphisms with radiologic primary knee OA in Mexican mestizo population. A matched case-control study was conducted (ratio, 1:1). Cases included 244 subjects with definite radiographic knee OA (grade ≥ 2). Controls were matched by age and gender and were subjects with no definite radiographic knee OA/normal (grade < 2). The DNMTs polymorphisms were genotyped by TaqMan allelic discrimination assays. Conditional logistic regression was carried out, and the genetic association was tested under co-dominant, dominant, and recessive inheritance models. Haplotypes for DNMT1 polymorphisms were constructed and their associations were also tested. The CC genotypes of rs2228611 and rs2228612 of DNMT1 were associated with a lower risk for primary knee OA under a co-dominant and a recessive model [OR (95% CI) 0.4 (0.2-0.8)/0.5 (0.3-0.8) and 0.3 (0.1-0.8)/0.3 (0.1-0.7), respectively]. The CT haplotype of DNMT1 polymorphisms was associated with a lower risk [OR (95% CI) 0.71 (0.51-0.97)]. The CC genotype of rs2424913 of DNMT3B was associated with an increased risk under a co-dominant and a dominant model [OR (95% CI) 3.0 (1.1-8.0), and 1.6 (1.1-2.4), respectively]. Our results show that DNMTs polymorphisms are associated with primary knee OA.

Long Noncoding RNA Nuclear Enriched Abundant Transcript 1 (NEAT1) Regulates Proliferation, Apoptosis, and Inflammation of Chondrocytes via the miR-181a/Glycerol-3-Phosphate Dehydrogenase 1-Like (GPD1L) Axis

Background

Osteoarthritis (OA) is one of the most common chronic musculoskeletal diseases, yet to date it lacks effective therapeutic strategies. Increasing evidence suggests that long noncoding RNAs (lncRNAs) serve pivotal roles in the occurrence and development of OA. However, the possible molecular mechanism involving lncRNAs, such as nuclear enriched abundant transcript 1 (NEAT1), in OA progression is still unclear.

Material/Methods

First, NEAT1 and miR-181a expression in OA synovium tissues and normal synovium tissues were detected. Then, the effect of NEAT1 on modulating growth ability, apoptosis, and inflammation in OA chondrocytes was investigated by a series of loss-function experiments. Next, the correlation between NEAT1, miR-181a, and glycerol-3-phosphate dehydrogenase 1-like (GPD1L) was fully investigated. Finally, the downregulation of miR-181a was employed as a recovery experiment to explore the functional mechanism of NEAT1 in OA.

Results

In the present study, we found that NEAT1 expression was downregulated in OA tissues, while miR-181a expression was prominently upregulated. Moreover, reduced expression of NEAT1 suppressed cell growth while elevating the apoptotic rate and increasing the abundance of inflammatory cytokines released in OA chondrocytes. Furthermore, we clarified that miR-181a was a direct sponge of NEAT1, and GPD1L was able to bind to miR-181a. Additionally, we found that downregulation of miR-181a was able to attenuate the effect of NEAT1 on apoptosis, inflammatory response, and proliferation in OA chondrocytes.

Conclusions

Our findings indicate that downregulation of NEAT1 aggravated progression of OA via modulating the miR-181a/GPD1L axis, providing a novel insight into the mechanism of OA pathogenesis.

MicroRNA Mediate Visfatin and Resistin Induction of Oxidative Stress in Human Osteoarthritic Synovial Fibroblasts Via NF-κB Pathway

Synovial membrane inflammation actively participate to structural damage during osteoarthritis (OA). Adipokines, miRNA, and oxidative stress contribute to synovitis and cartilage destruction in OA. We investigated the relationship between visfatin, resistin and miRNA in oxidative stress regulation, in human OA synovial fibroblasts. Cultured cells were treated with visfatin and resistin. After 24 h, we evaluated various pro-inflammatory cytokines, metalloproteinases (MMPs), type II collagen (Col2a1), miR-34a, miR-146a, miR-181a, antioxidant enzymes, and B-cell lymphoma (BCL)2 by qRT-PCR, apoptosis and mitochondrial superoxide production by cytometry, p50 nuclear factor (NF)-κB by immunofluorescence. Synoviocytes were transfected with miRNA inhibitors and oxidative stress evaluation after adipokines stimulus was performed. The implication of NF-κB pathway was assessed by the use of a NF-κB inhibitor (BAY-11-7082). Visfatin and resistin significantly up-regulated gene expression of interleukin (IL)-1β, IL-6, IL-17, tumor necrosis factor (TNF)-α,MMP-1, MMP-13 and reduced Col2a1. Furthermore, adipokines induced apoptosis and superoxide production, the transcriptional levels of BCL2, superoxide dismutase (SOD)-2, catalase (CAT), nuclear factor erythroid 2 like 2 (NRF2), miR-34a, miR-146a, and miR-181a. MiRNA inhibitors counteracted adipokines modulation of oxidative stress. Visfatin and resistin effects were suppressed by BAY-11-7082. Our data suggest that miRNA may represent possible mediators of oxidative stress induced by visfatin and resistin via NF-κB pathway in human OA synoviocytes.

microRNAs are potentially regulating the survivin gene in PBMCs from systemic sclerosis patients

Background: Survivin is an important anti-apoptotic protein and is involved in increasing auto-reactivity during the autoimmune diseases like systemic sclerosis (SSc).Aims: In the current study, we investigate the expression level of total survivin (survivin-TS) and its three important variants alongside with evaluation of the expression level of important microRNAs (miRNAs) that are involved in survivin expression regulation.Methods: Peripheral blood mononuclear cells (PBMCs) were isolated from 50 healthy controls, 25 diffuse cutaneous SSc (DcSSc), and 25 limited cutaneous SSc (LcSSc) patients. RNA was extracted and single-strand cDNA was synthesized. Quantitative real-time PCR was used to evaluate the expression level of survivin-TS and its variants as well the miRNAs.Results: Overexpression of survivin-2B and downregulation of survivin wild-type (survivin-WT) were found in total-SSc patients; however, expression level of survivin-TS had no significant difference. The expression levels of miR-335-5p, miR-485-5p, miR-16-5p, miR-150-5p, miR-34a-5p, miR-218-5p and miR-708-5p were higher in total-SSc patients. Significantly negative correlations were found between transcript levels of miR-150-5p, miR-16-5p, and miR-485-5p with survivin-TS mRNA expression.Conclusion: Survivin variants had altered expression in total-SSc patients. In addition, miRNAs might potentially and negatively regulate the survivin-TS expression. Altered expression of survivin, regulated by miRNAs, may result in apoptosis resistance and auto-reactivity in lymphocytes from patients and have important roles in SSc pathogenicity.

The Effect of the Phytocomplex Electrophoresis on the Clinical Symptomatology and Quality of Life of Patients with the Knee Joint Osteoarthritis

BACKGROUND:

Improving the effectiveness of rehabilitation of patients with osteoarthritis necessitates the use of drug electrophoresis with sinusoidal modulated currents (SMC-electrophoresis) in conjunction with drug therapy. The phytocomplex is proposed for electrophoresis composed of the compared, alfalfa and hops dry extract, containing flavonoids, coumestans, polysaccharides, steroids, essential amino acids, vitamins, mineral components and causing its possible use in osteoarthritis.

AIM:

The research aims to study the effect of the phytocomplex SMC-electrophoresis on the clinical symptoms and quality of life of patients with the knee joint osteoarthritis.

METHODS:

One hundred and eight patients were randomly distributed into 3 groups (n = 36). The phytocomplex SMC-electrophoresis was assigned to the first group, the amplipulse therapy (SMC) – to the second group, and the “basic” drug therapy – to the third group. The drug therapy of the patients of the third group was comparable with the drug treatment of those in the first two groups. The concentration of phytocomplex in the working solution was 10%. The electrotherapy was carried out in the aligned SMC mode in the first and fourth kind of works. Comparative indicators were as follows: WOMAC index, pain level on a visual analogue scale (VAS), Lequesne index, joint range of motion (JROM), articular and tendon indices, quality of life as per Health Assessment Questionnaire (HAQ).

RESULTS:

The use of the phytocomplex SMC-electrophoresis had a more pronounced positive effect on pain, knee joint function and quality of life of the patients compared with the treatment with drugs alone or using amplitude therapy. This was especially pronounced immediately after the rehabilitation. The analgesic effect was consistently maintained in the patients of the first group for up to 6 – 12 months, the second group – up to 3 – 6 months in terms of the level of pain according to the WOMAC and Lequesne indices, VAS, articular and tendon indices. Stable results have been obtained for improving the functions of the knee joint for up to 6 – 12 months using the phytocomplex SMC-electrophoresis as per the WOMAC and Lequesne indices. In the treatment by the phytocomplex SMC-electrophoresis, no side effects were registered.

CONCLUSION:

The obtained results give grounds for further research on the evaluation of the effectiveness of using the phytocomplex SMC-electrophoresis in microcirculatory disorders in the affected joint, for correcting connective tissue metabolism and electrolyte metabolism in the patients with the knee joint osteoarthritis.

TMF inhibits miR-29a/Wnt/β-catenin signaling through upregulating Foxo3a activity in osteoarthritis chondrocytes

Background: miR-29a, a downstream factor of Wnt/β-catenin signaling, promotes the activity of the Wnt/β-catenin signaling in a positive feedback loop. Our previous work showed that 5,7,3ʹ,4ʹ-tetramethoxyflavone (TMF), a major constituent from Murraya exotica L., exhibited chondroprotective activity by inhibiting the activity of Wnt/β-catenin signaling.

Purpose: To investigate whether TMF showed the inhibitory effects on miR-29a/β-catenin signaling by up regulation of Foxo3a expression.

Methods: Rat knee OA models were duplicated by using Hulth’s method. TMF (5 μg/mL and 20 μg/mL) was used for administration to cultured cells, which were isolated from the rat cartilages. Analysis of chondrocytes apoptosis, gene expression, and protein expression were conducted. In addition, miR-29a mimics and pcDNA3.1(+)-Foxo3a vector were used for transfection, luciferase reporter assay for detecting the activity of Wnt/β-catenin signaling, and co-immunoprecipitation for determining proteins interaction.

Results: TMF down regulated miR-29a/β-catenin signaling activity and cleaved caspase-3 expression and up regulated Foxo3a expression in OA rat cartilages. In vitro, miR-29a mimics down regulated the expression of Foxo3a and up regulated the activity of Wnt/β-catenin signaling and cleaved caspase-3 expression. TMF ameliorated miR-29a/β-catenin-induced chondrocytes apoptosis by up regulation of Foxo3a expression.

Conclusion: TMF exhibited chondroprotective activity by up regulating Foxo3a expression and subsequently inhibiting miR-29a/Wnt/β-catenin signaling activity.

DNA methylation regulates miR-140-5p and miR-146a expression in osteoarthritis

AIMS

Previous studies have demonstrated that transcriptional silencing of miRNAs due to DNA hypermethylation is associated with different pathologies. It has also been reported that abnormal expression of miR-140-5p and miR-146a is linked to osteoarthritis (OA) progression. In this study, we investigated the role of DNA methylation on miR-140-5p and miR-146a expression in OA.

MAIN METHODS

miR-140-5p and miR-146a expression was investigated by qRT-PCR. The methylation status of miR-140 and miR-146a regulatory regions was analyzed using qMSP and bisulfite sequencing analysis. SMAD-3 and NF-kB binding to miR-140 and miR-146a regulatory regions was assessed by ChIP assay and knockdown experiments. OA-related genes' expression was evaluated in 5-AzadC, miRNAs inhibitor and 5-AzadC/miRNAs inhibitor-treated cells.

KEY FINDINGS

Hypermethylation of specific CpG sites in miR-140 and miR-146a regulatory regions was associated with downregulation of miR-140-5p and miR-146a in OA chondrocytes and synoviocytes, respectively. 5-AzadC-induced miR-140-5p and miR-146a upregulation was observed in OA chondrocytes and synoviocytes. Moreover, we found decreased binding affinity of SMAD-3 and NF-kB transcription factors on the hypermethylated miR-140-5p and miR-146a regulatory regions, respectively. Downregulation of MMP-13 and ADAMTS-5 in 5-AzadC-treated OA chondrocytes was prevented by miR-140-5p inhibitor transfection. Similarly, 5-AzadC-treated OA synoviocytes showed decreased expression of IRAK-1, IL1Β and IL-6, which was reversed following 5-AzadC-/miR-146a inhibitor treatment.

SIGNIFICANCE

Our results strongly suggest the impact of DNA methylation on miR-140-5p and miR-146a suppression in OA chondrocytes and synoviocytes, contributing to OA pathogenesis.

A Long Noncoding RNA (lncRNA)-Associated Competing Endogenous RNA (ceRNA) Network Identifies Eight lncRNA Biomarkers in Patients with Osteoarthritis of the Knee

Background

Osteoarthritis (OA) of the knee is a common disease that is associated with chronic pain. This study aimed to identify and investigate the functional role of biomarkers associated with long noncoding RNA (lncRNA) in the progression of OA of the knee by lncRNA-associated competing endogenous RNA (ceRNA) integrated network analysis.

Material/Methods

High-quality microRNA (miRNA)-lncRNA and miRNA-mRNA interactions and lncRNA and mRNA expression profiles for patients with OA of the knee with mild and severe pain were obtained from the Gene Expression Omnibus (GEO) database (GSE99662). A three-step computational method was used to construct the lncRNA-associated ceRNA interaction network in OA by integrating miRNA-lncRNA/mRNA interactions and lncRNA/mRNA expression profiles in patients with OA with mild and severe pain.

Results

A total of 1,870 dysregulated lncRNA-mRNA interactions were obtained in the lncRNA-associated ceRNA network in OA, including 476 gain and 1,394 loss interactions, covering 131 lncRNAs and 1,251 mRNAs. Characterization of the lncRNA-associated ceRNA network in OA indicated that lncRNAs had roles in the network. Further differential expression analysis identified eight lncRNA biomarkers, which could distinguish between patients with OA with mild pain and severe pain. These lncRNA-associated interactions showed significantly different co-expression patterns in samples from patients with OA of the knee associated with mild pain.

Conclusions

Integrated network analysis of lncRNA-associated ceRNA identified eight lncRNA molecular biomarkers associated with the progression of OA of the knee.