The expression and function of microRNAs in chondrogenesis and osteoarthritis

Profiling microRNA expression in murine bone healing and non-union formation: Role of miR-140 during the early stage of bone healing

Although cellular and molecular mechanisms during the course of bone healing have been thoroughly investigated, the regulation of gene expression by microRNA during bone regeneration is still poorly understood. We hypothesized that nonunion formation is associated with different microRNA expression patterns and that target proteins of these microRNAs are differently expressed in callus tissue of nonunions compared to physiologically healing bones. In a well-established femoral osteotomy model in CD-1 mice osteotomies were induced which result either in healing or in nonunion formation. MicroRNA and target protein expression was evaluated by microarray, quantitative real-time polymerase chain reaction (qrt-PCR) and Western blot. Microarray analyses demonstrated 44 microRNAs to be relevant for nonunion formation compared to physiological bone healing. In nonunions qrt-PCR could validate a higher expression of microRNA-140-3p and microRNA-140-5p. This was associated with a reduced expression of Dnpep and stromal cell-derived factor (SDF)-1α, which are both known to be target proteins of microRNA-140 and also to be involved in the process of bone healing. These data suggest that an increased expression of microRNA-140-3p and microRNA-140-5p markedly contributes to the development of nonunions, most probably by affecting bone morphogenetic protein (BMP)-2 function during the early stage of healing due to a reduced SDF-1α expression.

The microRNAs miR-204 and miR-211 maintain joint homeostasis and protect against osteoarthritis progression

Osteoarthritis (OA) is a common, painful disease. Currently OA is incurable, and its etiology largely unknown, partly due to limited understanding of OA as a whole-joint disease. Here we report that two homologous microRNAs, miR-204 and miR-211, maintain joint homeostasis to suppress OA pathogenesis. Specific knockout of miR-204/-211 in mesenchymal progenitor cells (MPCs) results in Runx2 accumulation in multi-type joint cells, causing whole-joint degeneration. Specifically, miR-204/-211 loss-of-function induces matrix-degrading proteases in articular chondrocytes and synoviocytes, stimulating articular cartilage destruction. Moreover, miR-204/-211 ablation enhances NGF expression in a Runx2-dependent manner, and thus hyper-activates Akt signaling and MPC proliferation, underlying multiplex non-cartilaginous OA conditions including synovial hyperplasia, osteophyte outgrowth and subchondral sclerosis. Importantly, miR-204/-211-deficiency-induced OA is largely rescued by Runx2 insufficiency, confirming the miR-204/-211-Runx2 axis. Further, intraarticular administration of miR-204-expressing adeno-associated virus significantly decelerates OA progression. Collectively, miR-204/-211 are essential in maintaining healthy homeostasis of mesenchymal joint cells to counteract OA pathogenesis.

Osteoarthritis involves whole-joint tissue degeneration. Here, the authors show that miR-204 and miR-211 in mesenchymal joint cells regulate their proliferation, catabolic and osteogenic responses, and that disease progression is ameliorated by intra-articular miR-204 delivery in mice.

Upregulation of microRNA-9-5p inhibits apoptosis of chondrocytes through downregulating Tnc in mice with osteoarthritis following tibial plateau fracture

Osteoarthritis (OA) is a common degenerative joint disease which is typically progressed with age, affecting smaller joints of hands, lower limbs, and the vertebral column. It has been reported that microRNAs could regulate the biological processes of OA. Therefore, the purpose of this study was to elucidate miR-9-5p's role in regulating cartilage remodeling of OA mice following tibial plateau fracture (TPF) through regulation of tenascin C (Tnc). Initially, we determined the expression of miR-9-5p and Tnc in mice with OA and then testified their relationship. The results displayed a high expression of Tnc, but a poor expression of miR-9-5p with high methylation in OA. Tnc was confirmed to be a target gene of miR-9-5p. Moreover, based on gain- and loss-function experiments, an increase of miR-9-5p and loss of Tnc had the potential to inhibit cell apoptosis, while facilitating cell proliferation, migration, invasion, and cartilage remodeling of mice with OA following TPF. This was further demonstrated by a higher expression of type II collagen, lower type X collagen, and protogenin expression. Subsequently, downregulation of miR-9-5p aggravated the pathological changes of mice, illustrated by an increase in the Mankin score. In conclusion, the present study proved that overexpression of miR-9-5p suppressed chondrocytes apoptosis and promoted cartilage remodeling through downregulating of Tnc in mice with OA.

[Effects of cartilage progenitor cells and microRNA-140 on repair of osteoarthritic cartilage injury]

OBJECTIVE

To summarize the effect of cartilage progenitor cells (CPCs) and microRNA-140 (miR-140) on the repair of osteoarthritic cartilage injury, and analyze their clinical prospects.

METHODS

The recent researches regarding the CPCs, miR-140, and repair of cartilage in osteoarthritis (OA) disease were extensively reviewed and summarized.

RESULTS

CPCs possess the characteristics of self-proliferation, expression of stem cell markers, and multi-lineage differentiation potential, and their chondrogenic ability is superior to other tissues-derived mesenchymal stem cells. CPCs are closely related to the development of OA, but the autonomic activation and chondrogenic ability of CPCs around the osteoarthritic cartilage lesion cannot meet the requirements of complete cartilage repair. miR-140 specifically express in cartilage, and has the potential to activate CPCs by inhibiting key molecules of Notch signaling pathway and enhance its chondrogenic ability, thus promoting the repair of osteoarthritic cartilage injury. Intra-articular delivery of drugs is one of the main methods of OA treatment, although intra-articular injection of miR-140 has a significant inhibitory effect on cartilage degeneration in rats, it also exhibit some limitations such as non-targeted aggregation, low bioavailability, and rapid clearance. So it is a good application prospect to construct a carrier with good safety, cartilage targeting, and high-efficiency for miR-140 based on articular cartilage characteristics. In addition, CPCs are mainly dispersed in the cartilage surface, while OA cartilage injury also begins from this layer, it is therefore essential to emphasize early intervention of OA.

CONCLUSION

miR-140 has the potential to activate CPCs and promote the repair of cartilage injury in early OA, and it is of great clinical significance to further explore the role of miR-140 in OA etiology and to develop new OA treatment strategies based on miR-140.

MicroRNA-21-5p as a novel therapeutic target for osteoarthritis

OBJECTIVE

Growing evidence indicates that microRNAs (miRNA) play a critical role in the pathogenesis of OA, and overexpressing or silencing miRNA expression in OA models can contribute to the development of miRNA-based therapeutics. The objective of this study was to determine whether intra-articular injection of miRNA can inhibit OA progression.

METHODS

The miRNA expression profile was determined in OA cartilage tissues and controls. Functional analysis of the miRNAs on extracellular matrix degradation was performed after miRNA mimic or inhibitor transfection. Luciferase reporter assays and western blotting were employed to determine miRNA targets. To investigate the functional mechanism of miR-21-5p in OA development, miR-21-5pfl/flCol2a1-CreER and wild-type mice were subject to surgical destabilization of the medial meniscus. Therapeutically, wild-type mice undergoing surgical destabilization of the medial meniscus were treated with intra-articular injection of agomir- and antagomir-21-5p.

RESULTS

We found that expression of miR-21-5p was significantly up-regulated in OA cartilage tissues. The articular cartilage degradation of miR-21-5p conditional knockout mice was significantly alleviated compared with that of wild-type mice in spontaneous and destabilization of the medial meniscus models. Through gain-of-function and loss-of-function studies, miR-21-5p was shown to significantly affect matrix synthesis genes expression, and chondrocyte proliferation and apoptosis. Further, fibroblast growth factor 18 (FGF18) was identified as a target of miR-21-5p. Intra-articular injection of antagomir-21-5p significantly attenuated the severity of experimental OA. Clinically, FGF18 expression level was correlated with miR-21-5p expression and a modified Mankin scale.

CONCLUSION

Our findings reveal a miRNA functional pathway important for OA development, highlighting miRNA-21-5p silencing as an attractive therapeutic regimen in future clinical trials involving patients with OA.

Core regulatory RNA molecules identified in articular cartilage stem/progenitor cells during osteoarthritis progression

Aim: To assess cartilage-derived stem/progenitor cells (CSPCs) in osteoarthritis (OA) by employing mRNA-miRNA-circRNA-lncRNA network biology approach. Methods: Differentially expressed (DE) RNAs in CSPCs from 2-/4-/8-month-old STR/Ort and CBA mice were identified to construct networks via RNA sequencing. Results: Compared with age-matched CBA mice, 4-/8-month-old STR/Ort mice had cartilage lesions and their CSPCs exhibited lower proliferative and differentiation capacity (decreased CD44 and CD90), and identified 7082 DE RNAs in STR/Ort mice were associated with strain differences or OA progression. OA-related core RNAs were identified via the networks constructed with the predominant DE RNAs, which were involved in the signaling pathways (NF-κB/MAPK/Hippo/Wnt/TGF-β/cytoskeleton organization). The core RNAs (miR-322-5p/miR-493-5p/miR-378c/CPNE1/Cdh2/PRDM16/CTGF/NCAM1) were validated in CSPCs from OA patients. Conclusion: RNA-based networks identifying core RNAs and signaling pathways contribute to CSPC-dependent OA mechanisms.

Potential Novel Prediction of TMJ-OA: MiR-140-5p Regulates Inflammation Through Smad/TGF-β Signaling

Temporomandibular joint osteoarthritis (TMJ-OA), mainly exhibit extracellular matrix loss and condylar cartilage degradation, is the most common chronic and degenerative maxillofacial osteoarthritis; however, no efficient therapy for TMJ-OA exists due to the poor understanding of its pathological progression. MicroRNA (miR)-140-5p is a novel non-coding microRNAs (miRNAs) that expressed in osteoarthritis specifically. To investigate the molecular mechanisms of miR-140-5p in TMJ-OA, primary mandibular condylar chondrocytes (MCCs) from C57BL/6N mice were treated with interleukins (IL)-1β or transfected with miR-140-5p mimics or inhibitors, respectively. The expression of matrix metallopeptidase (MMP)-13, miR-140-5p, nuclear factor (NF)-kB, Smad3 and transforming growth factor (TGF)-β3 were examined by western blotting or quantitative reverse-transcription polymerase chain reaction (qRT-PCR). The interaction between the potential binding sequence of miR-140-5p and the 3'-untranslated region (3'UTR) of Smad3 mRNA was testified by dual-luciferase assay. Small Interfering RNA of Smad3 (Si-Smad3) was utilized to further identify the role of Smad3 mediated by miR-140-5p. The data showed MMP13, miR-140-5p and NF-kB increased significantly in response to IL-1β inflammatory response in MCCs, meanwhile, Smad3 and TGF-β3 reduced markedly. Moreover, transfection of miR-140-5p mimics significantly suppressed the expression of Smad3 and TGF-β3 in MCCs, while miR-140-5p inhibitors acted in a converse manner. As the luciferase reporter of Smad3 mRNA observed active interaction with miR-140-5p, Smad3 was identified as a direct target of miR-140-5p. Additionally, the expression of TGF-β3 was regulated upon the activation of Smad3. Together, these data suggested that miR-140-5p may play a role in regulating mandibular condylar cartilage homeostasis and potentially serve as a novel prognostic factor of TMJ-OA-like pathology.

MicroRNA-218 promotes early chondrogenesis of mesenchymal stem cells and inhibits later chondrocyte maturation

Background

MicroRNAs (miRNAs) reportedly participate in the mesenchymal stem cell (MSC) chondrogenic differentiation regulation. We objected to examine how miR-218 regulate chondrogenic differentiation of synovium-derived MSCs (SDSCs) and the maturation of RCJ3.1C5.1 chondrocytes. SDSCs were sourced from the knee joint synovium of New Zealand white rabbits, and their multilineage differentiation potentials were examined. The level of miR-218 was measured during SDSC chondrogenic differentiation, together with determination of SDSCs chondrogenic markers and RCJ3.1C5.1 chondrocytes maturation markers expression level after transfection of miR-218 mimics/inhibitor.

Results

miR-218 expression was notably upregulated in early chondrogenesis but mostly ceased during the maturation phases of chondrogenic differentiation in SDSCs. The transfection of miR-218 mimics notably enhanced SDSCs chondrocytes differentiation, as evidenced by augmented expressions of chondrogenic markers (SOX9, COL2A1, ACAN, GAG, and COMP) in terms of mRNA and protein level, and the inhibition of miR-218 yielded opposite resutls. Additionally, miR-218 overexpression substantially suppressed the expression of osteogenic markers (ALP, BSP, COL1A1, OCN and OPN) during the early stage of chondrogenesis while increasing that of chondrogenic markers (SOX9, COL2A1, ACAN, GAG and COMP). However, miR-218 mimics notably suppressed maturation markers (CMP, COL10A1, MMP-13 and VEGF) expression in RCJ3.1C5.18 chondrocytes, and the miR-218 inhibitor promoted the expression of these maturation markers. We proposed miR-218 plays a regulatory role on 15-hydroxyprostaglandin dehydrogenase (HPGD), which plays a key role in chondrogenic differentiation, and this finding indicates that miR-218 directly regulates HPGD expression in SDSCs.

Conclusion

Our study suggests that miR-218 contributes to early chondrogenesis while suppressing later chondrocyte maturation. The miR-218-HPGD pathway offers us a perspective into how SDSCs differentiate into chondrogenic cells.

microRNA-590-5p targets transforming growth factor β1 to promote chondrocyte apoptosis and autophagy in response to mechanical pressure injury

This study aimed to investigate the role of miR-590-5p in chondrocyte apoptosis and autophagy in response to mechanical pressure injury in vitro, as well as to elucidate its regulatory mechanism in the pathogenesis of osteoarthritis. We applied mechanical pressure of 10 MPa to chondrocytes for 60 minutes to establish the chondrocyte model of experimentally induced mechanical injury. We then investigated the expression of miR-590-5p in the injury model and the effects of miR-590-5p dysregulation on the expression of cell apoptosis-related and autophagy-related proteins. Cell apoptosis was detected by flow cytometry. Moreover, the potential targets of miR-590-5p were investigated. Mechanical pressure injury resulted in a significantly increased expression of miR-590-5p. Suppression of miR-590-5p significantly increased chondrocytes viability, inhibited chondrocytes apoptosis and autophagy in response to mechanical pressure injury. In addition, mechanical pressure injury led to a decreased expression of transforming growth factor β1 (TGFβ1). Moreover, TGFβ1 was confirmed as a direct target of miR-590-5p. Knockdown of TGFβ1 significantly induced chondrocytes apoptosis and autophagy in response to mechanical pressure injury, which was contrary to the effects of miR-590-5p suppression. Furthermore, overexpression of TGFβ1 and miR-590-5p at the same time significantly reversed the effects of overexpression of miR-590-5p alone on chondrocytes apoptosis and autophagy. Our results indicate that upregulation of miR-590-5p may target TGFβ1 to promote chondrocyte apoptosis and autophagy in response to mechanical pressure injury, thus contributing to the pathogenesis of osteoarthritis.

MicroRNA-128a represses chondrocyte autophagy and exacerbates knee osteoarthritis by disrupting Atg12

Chondrocyte loss is a prominent feature of osteoarthritis (OA). Autophagy is indispensable in maintaining the metabolic activities of cells exposed to deleterious stress. The contribution of microRNA signaling to chondrocyte autophagy in OA development remains elusive. We uncovered an association between poor autophagy and increased miR-128a expressions in articular chondrocytes of patients with end-stage knee OA and in a rat anterior cruciate ligament transection (ACLT) model for OA development. Cartilage matrix degradation and severe OA histopathology was evident upon forced miR-128a expression within the articular compartment. Intra-articular injections with miR-128a antisense oligonucleotide stabilized chondrocyte autophagy and slowed ACLT-mediated articular tissue destruction, including cartilage erosion, synovitis, osteophyte formation, and subchondral plate damage. In vitro, miR-128 signaling hindered Atg12 expression, LC3-II conversion, and autophagic puncta formation through targeting the 3′-untranslated region of Atg12. It increased apoptotic programs, diminishing cartilage formation capacity of articular chondrocytes. Inactivating histone methyltransferase EZH2 reduced methyl histone H3K27 enrichment in the miR-128a promoter and upregulated miR-128a transcription in inflamed chondrocytes. Taken together, miR-128a-induced Atg12 loss repressed chondrocyte autophagy to aggravate OA progression. EZH2 inactivation caused H3K27 hypomethylation to accelerate miR-128a actions. Interruption of miR-128a signaling attenuated chondrocyte dysfunction and delayed OA development. Our data provide new insights into how miR-128a signaling affects chondrocyte survival and articular cartilage anabolism and highlight the potential of miR-128a targeting therapy to alleviate knee OA.

miR-324-5p is up regulated in end-stage osteoarthritis and regulates Indian Hedgehog signalling by differing mechanisms in human and mouse

The Hedgehog (Hh) signalling pathway plays important roles during embryonic development and in adult tissue homeostasis, for example cartilage, where its deregulation can lead to osteoarthritis (OA). microRNAs (miRNAs) are important regulators of gene expression, and have been implicated in the regulation of signalling pathways, including Hh, thereby impacting upon development and disease. Our aim was to identify the function of miRNAs whose expression is altered in OA cartilage. Here we identified an increase in miR-324-5p expression in OA cartilage and hypothesised that, as in glioma, miR-324-5p would regulate Hh signalling. We determined that miR-324-5p regulates osteogenesis in human mesenchymal stem cells (MSCs) and in mouse C3H10T1/2 cells. Luciferase reporter assays demonstrated that miR-324-5p directly regulated established targets GLI1 and SMO in human but not in mouse, suggesting species-dependent mechanism of Hh pathway regulation. Stable Isotope Labelling with Amino acids in Cell culture (SILAC), mass spectrometry and whole genome transcriptome analysis identified Glypican 1 (Gpc1) as a novel miR-324-5p target in mouse, which was confirmed by real-time RT-PCR, immunoblotting and 3′UTR-luciferase reporters. Knockdown of Gpc1 reduced Hh pathway activity, and phenocopied the effect of miR-324-5p on osteogenesis, indicating that miR-324-5p regulates Hh signalling in mouse via direct targeting of Gpc1. Finally, we showed that human GPC1 is not a direct target of miR-324-5p. Importantly, as well as identifying novel regulation of Indian Hedgehog (Ihh) signalling, this study demonstrates how a miRNA can show conserved pathway regulation in two species but by distinct mechanisms and highlights important differences between human diseases and mouse models.

TGF-β/SMAD signaling inhibits intermittent cyclic mechanical tension-induced degeneration of endplate chondrocytes by regulating the miR-455-5p/RUNX2 axis

A mechanical stimulation plays a pivotal role in maintaining normal cartilage function. Our objective was to reveal the mechanism of action of the tension-sensitive molecule miR-455-5p in the degeneration of endplate chondrocytes and to identify whether the transforming growth factor beta (TGF-β)/SMAD signaling pathway has a regulatory effect on it. The expression profiles of members of the TGF-β/SMAD pathway, miR-455-5p, and RUNX2 were determined by microRNA microarray analysis, reverse transcription quantitative polymerase chain reaction, luciferase reporter assay, and Western blot analysis. Intermittent cyclic mechanical tension (ICMT) induced the degeneration of endplate chondrocytes without affecting their viability. The tension-sensitive molecule miR-455-5p specifically bound to RUNX2, a gene involved in the degeneration of endplate chondrocytes. Activation of the TGF-β/SMAD signaling pathway upregulated miR-455-5p expression and thus inhibited RUNX2 levels. Therefore, the TGF-β/SMAD signaling pathway inhibits the ICMT-induced degeneration of endplate chondrocytes by regulating the miR-455-5p/RUNX2 axis.

IL-1β-induced miR-34a up-regulation inhibits Cyr61 to modulate osteoarthritis chondrocyte proliferation through ADAMTS-4

Osteoarthritis (OA) is the most prevalent degenerative joint disease with multifactorial etiology caused by risk factors. The degradation of aggrecan by upregulated ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) is the key event in the development of OA. ADAMTS-4 contributes to aggrecan degradation in human OA. Cysteine-rich angiogenic inducer 61 (Cyr61), which is associated with diseases related to chronic inflammation, is found in articular cartilage from patients with osteoarthritis and appears to suppress ADAMTS-4 activity, possibly leading to chondrocyte cloning. Herein, we first revealed that Cyr61 and ADAMTS-4 protein levels were remarkably increased in OA cartilage tissues and OA chondrocytes, and verified Cyr61 regulation of ADAMTS-4 in normal and OA chondrocyte. Further, we revealed that Cyr61 could promote OA chondrocyte proliferation through inhibiting ADAMTS-4. Overproduction of inflammatory cytokines plays a vital role in the pathological development of OA; herein, we demonstrated that IL-1β inhibited Cyr61, while promoted ADAMTS-4 expression. By using online tools and luciferase assays, we confirmed that miR-34a, a regulatory miRNA of chondrocyte proliferation, could directly bind to the 3'-UTR of Cyr61 to inhibit its expression; further, IL-1β regulated Cyr61 and ADAMTS-4 expression through miR-34a. In OA cartilage tissues, miR-34a, and IL-1β mRNA expression was up-regulated and positively correlated; miR-34a and Cyr61 mRNA was positively correlated, further indicating that suppressing miR-34a expression might rescue IL-1β-induced Cyr61 suppression, and promote OA chondrocyte proliferation. Taken together, we provided novel experimental basis for rescuing OA chondrocyte proliferation through miR-34a/Cyr61 axis.

The Involvement of MicroRNAs in Osteoarthritis and Recent Developments: A Narrative Review

Background:

Osteoarthritis (OA) is the most common chronic joint disease and it may progressively cause disability and compromise quality of life. Lately, the role of miRNAs in the pathogenesis of OA has drawn a lot of attention. miRNAs are small, single-stranded, non-coding molecules of RNA which regulate gene expression at post-transcriptional level. The dysregulation of the expression of several miRNAs affects pathways involved in OA pathogenesis.

Objective:

The purpose of this article is to review the literature on the involvement of miRNAs in the pathogenesis of OA and the implications on its diagnosis and treatment.

Materials and Methods:

An extensive electronic literature search was conducted by two researchers from January 2008 to August 2017. Titles and abstracts of papers were screened by the authors for further inclusion in the present work. Finally, full texts of the selected articles were retrieved.

Results:

Abnormally expressed miRNAs enhance the production of cartilage degrading enzymes, inhibit the expression of cartilage matrix components, increase the production of proinflammatory cytokines, facilitate chondrocyte apoptosis, suppress autophagy in chondrocytes and are involved in pain-related pathways. miRNAs are also incorporated in extra-cellular membranous vesicles such as exosomes and participate in the intercellular communication in osteoarthritic joints.

Conclusion:

Ongoing research on miRNAs has potential implications in the diagnosis and treatment of OA. Their different levels in peripheral blood and synovial fluid between OA patients and healthy population makes them candidates for being used as biomarkers of the disease, while targeting miRNAs may be a novel therapeutic strategy in OA.

Muscle miRNAome shows suppression of chronic inflammatory miRNAs with both prednisone and vamorolone

Corticosteroids are highly prescribed and effective anti-inflammatory drugs but the burden of side effects with chronic use significantly detracts from patient quality of life, particularly in children. Developing safer steroids amenable to long-term use is an important goal for treatment of chronic inflammatory diseases such as Duchenne muscular dystrophy (DMD). We have developed vamorolone (VBP15), a first-in-class dissociative glucocorticoid receptor (GR) ligand that shows the anti-inflammatory efficacy of corticosteroids without key steroid side effects in animal models. miRNAs are increasingly recognized as key regulators of inflammatory responses. To define effects of prednisolone and vamorolone on the muscle miRNAome, we performed a preclinical discovery study in the mdx mouse model of DMD. miRNAs associated with inflammation were highly elevated in mdx muscle. Both vamorolone and prednisolone returned these toward wild-type levels (miR-142-5p, miR-142-3p, miR-146a, miR-301a, miR-324-3p, miR-455-5p, miR-455-3p, miR-497, miR-652). Effects of vamorolone were largely limited to reduction of proinflammatory miRNAs. In contrast, prednisolone activated a separate group of miRNAs associated with steroid side effects and a noncoding RNA cluster homologous to human chromosome 14q32. Effects were validated for inflammatory miRNAs in a second, independent preclinical study. For the anti-inflammatory miRNA signature, bioinformatic analyses showed all of these miRNAs are directly regulated by, or in turn activate, the inflammatory transcription factor NF-κB. Moving forward miR-146a and miR-142 are of particular interest as biomarkers or novel drug targets. These data validate NF-κB signaling as a target of dissociative GR-ligand efficacy in vivo and provide new insight into miRNA signaling in chronic inflammation.

Comprehensive evaluation of differential lncRNA and gene expression in patients with intervertebral disc degeneration

The present study aimed to identify novel intervertebral disc degeneration (IDD)-associated long noncoding (lnc)RNAs and genes. The lncRNA and mRNA microarray dataset GSE56081 was downloaded from the Gene Expression Omnibus database and included 5 samples from patients with degenerative lumbar nucleus pulposus and 5 normal controls. Differentially expressed lncRNAs or differentially expressed genes (DEGs) were identified and co-expression network analysis was performed followed by functional analysis for genes in the network. Additionally, a microRNA (miRNA)-lncRNA-mRNA competing endogenous RNA (ceRNA) regulatory network was constructed based on DEGs and lncRNAs in the co-expression network. Furthermore, a literature search was performed to identify specific miRNAs that had been previously associated with IDD and a specific miRNA-associated ceRNA network was extracted from the co-expression network. A total of 967 genes and 137 lncRNAs were differentially expressed between IDD samples and controls. A co-expression network was constructed and contained 39 differentially expressed lncRNAs and 209 DEGs, which were primarily involved in ‘skeletal system development’, ‘response to mechanical stimulus’ and ‘bone development’. Furthermore, a ceRNA network was established, including 79 miRNAs, 9 downregulated lncRNAs and 148 DEGs. The identified miRNAs included a previously reported disease-associated miRNA, hsa-miR-140. The present study demonstrated that hsa-miR-140 was regulated by three lncRNAs in the hsa-miR-140-associated ceRNA network, including KCNQ1 opposite strand/antisense transcript 1 (KCNQ1OT1), OIP5 antisense RNA 1 (OIP5-AS1) and UGDH antisense RNA 1 (UGDH-AS1). KCNQ1OT1 was co-expressed with neurochondrin (NCDN) and lon peptidase 2, peroxisomal. In addition, the lncRNAs OIP5-AS1 and UGDH-AS1 targeted several overlapping co-expressed genes, including forkhead box F1 (FOXF1) and polycystin 1, transient receptor potential channel interacting (PKD1). Therefore, KCNQ1OT1 may regulate the expression of NCDN, and OIP5-AS1 and UGDH-AS1 may affect the expression of FOXF1 and PKD1 in IDD. Further experiments are required to validate the results of the present study, which may provide valuable insights into the identification of novel biomarkers associated with IDD.

Inhibition of miR-126 protects chondrocytes from IL-1β induced inflammation via upregulation of Bcl-2

OBJECTIVES

The aim of this study was to investigate the role of miR-126 in the development of osteoarthritis, as well as the potential molecular mechanisms involved, in order to provide a theoretical basis for osteoarthritis treatment and a novel perspective for clinical therapy.

METHODS

Human chondrocyte cell line CHON-001 was administrated by different doses of interleukin (IL)-1β to simulate inflammation. Cell viability, migration, apoptosis, IL-6, IL-8, and tumour necrosis factor (TNF)-α expression, as well as expression of apoptosis-related factors, were measured to assess inflammation. miR-126 expression was measured by quantitative polymerase chain reaction (qPCR). Cells were then transfected with miR-126 inhibitor to assess the effect of miR-126 on IL-1β-injured CHON-001 cells. Expression of B-cell lymphoma 2 (Bcl-2) and the activity of mitogen-activated protein kinase (MAPK) / Jun N-terminal kinase (JNK) signaling pathway were measured by Western blot to explore the underlying mechanism through which miR-126 affects IL-1β-induced inflammation.

RESULTS

After IL-1β administration, cell viability and migration were suppressed while apoptosis was enhanced. Expression of IL-6, IL-8, and TNF-α were all increased, and miR-126 was upregulated. In IL-1β-administrated CHON-001 cells, miR-126 inhibitor suppressed the effect of IL-1β on cell viability, migration, apoptosis, and inflammatory response. Bcl-2 expression was negatively regulated with miR-126 in IL-1β-administrated cells, and thus affected expressions of phosphorylated MAPK and JNK.

CONCLUSION

IL-1β-induced inflammatory markers and miR-126 was upregulated. Inhibition of miR-126 decreased IL-1β-induced inflammation and cell apoptosis, and upregulated Bcl-2 expression via inactivating the MAKP/JNK signalling pathway.Cite this article: C. D. Yu, W. H. Miao, Y. Y. Zhang, M. J. Zou, X. F. Yan. Inhibition of miR-126 protects chondrocytes from IL-1β induced inflammation via upregulation of Bcl-2. Bone Joint Res 2018;7:414-421. DOI: 10.1302/2046-3758.76.BJR-2017-0138.R1.

MiR-455-3p inhibits the degenerate process of chondrogenic differentiation through modification of DNA methylation

The aim of this work was to determine whether miR-455-3p regulates DNA methylation during chondrogenic differentiation of hMSCs. The expression of miR-455-3p and de novo methyltransferase DNMT3A was assessed in micromass culture of hBMSCs, which induced chondrogenic differentiation in vitro, and in E16.5 mice in vivo. A luciferase reporter assay was used to confirm whether miR-455-3p directly targets DNMT3A by interaction with the 3′-UTR. Using an Illumina Infinium Methylation EPIC microarray, genome-wide DNA methylation of hBMSCs with or without overexpressed miR-455-3p was examined for 28 days during induced chondrogenic differentiation. Here, we showed that miR-455-3p was more expressed during the middle stage of hBMSC chondrogenic differentiation, and less expressed in the late stage. DNMT3A was less expressed in the middle stage and more expressed in the late stage, and was also more expressed in the palms of miR-455-3p deletion mice compared to those of wild-type mice. The luciferase reporter assay demonstrated that miR-455-3p directly targets DNMT3A 3′-UTR. miR-455-3p overexpression inhibits the degenerate process during chondrogenic differentiation, while deletion of miR-455-3p in mice accelerated cartilage degeneration. Genome-wide DNA methylation analysis showed miR-455-3p overexpression regulates DNA methylation of cartilage-specific genes. GO analysis revealed PI3K-Akt signaling pathway was most hypomethylated. Our data show that miR-455-3p can regulate hMSC chondrogenic differentiation by affecting DNA methylation. Overexpression of miR-455-3p and DNA methylation inhibitors can thus potentially be utilized to optimize chondrogenic differentiation.

Exosomes and Stem Cells in Degenerative Disease Diagnosis and Therapy

Stroke can cause death and disability, resulting in a huge burden on society. Parkinson’s disease (PD) is a chronic neurodegenerative disorder characterized by motor dysfunction. Osteoarthritis (OA) is a progressive degenerative joint disease characterized by cartilage destruction and osteophyte formation in the joints. Stem cell therapy may provide a biological treatment alternative to traditional pharmacological therapy. Mesenchymal stem cells (MSCs) are preferred because of their differentiation ability and possible derivation from many adult tissues. In addition, the paracrine effects of MSCs play crucial anti-inflammatory and immunosuppressive roles in immune cells. Extracellular vesicles (EVs) are vital mediators of cell-to-cell communication. Exosomes contain various molecules such as microRNA (miRNA), which mediates biological functions through gene regulation. Therefore, exosomes carrying miRNA or other molecules can enhance the therapeutic effects of MSC transplantation. MSC-derived exosomes have been investigated in various animal models representing stroke, PD, and OA. Exosomes are a subtype of EVs. This review article focuses on the mechanism and therapeutic potential of MSC-derived exosomes in stroke, PD, and OA in basic and clinical aspects.

Mesenchymal stem cell transplantation in systemic lupus erythematous, a mesenchymal stem cell disorder

Systemic lupus erythematosus (SLE) is a chronic autoimmune and inflammatory disorder with involvement of several organs and systems such as the kidney, lung, brain and the hematopoietic system. As the most prevailing organ manifestation, lupus nephritis is the major cause of mortality and morbidity in SLE patients. The most classically and widely administered immunosuppressive medications, namely corticosteroids and cyclophosphamide, have eventuated in a remarkable amelioration in disease complications over the last few years and reduced the progression to end-stage multiorgan failure. Mesenchymal stem cells (MSCs) are considered as non-hematopoietic and multipotential progenitor cells, which are able to differentiate into multiple cell lineages such as chondrocytes, osteoblasts, myoblasts, endothelial cells, adipocytes, neuron-like cells, hepatocytes and cardiomyocytes. MSCs from SLE patients have demonstrated defects such as aberrant cytokine production. Moreover, impaired phenotype, growth and immunomodulatory functions of MSCs from patients with SLE in comparison to healthy controls have been reported. Therefore, it is hypothesized that SLE is potentially an MSC-mediated disease and, as a result, allogeneic rather than autologous MSC transplantation can be argued to be a potentially advantageous therapy for patients with SLE. On the other hand, the MSC senescence phenomenon may meet the current therapeutic approaches with challenges and demand more attention. Here, we discuss MSC transplantations to date in animal models and humans and focus on the MSC senescence complications in SLE patients.

MicroRNAs in orthopaedic research: Disease associations, potential therapeutic applications, and perspectives

MicroRNAs (miRNAs) are small non-coding RNAs that function to control many cellular processes by their ability to suppress expression of specific target genes. Tens to hundreds of target genes may be affected by one miRNA, thereby resulting in modulation of multiple pathways in any given cell type. Therefore, altered expression of miRNAs (i.e., during tissue development or in scenarios of disease or cellular stress) can have a profound impact on processes regulating cell differentiation, metabolism, proliferation, or apoptosis, for example. Over the past 5-10 years, thousands of reports have been published on miRNAs in cartilage and bone biology or disease, thus highlighting the significance of these non-coding RNAs in regulating skeletal development and homeostasis. For the purpose of this review, we will focus on miRNAs or miRNA families that have demonstrated function in vivo within the context of cartilage, bone or other orthopaedic-related tissues (excluding muscle). Specifically, we will discuss studies that have utilized miRNA transgenic mouse models or in vivo approaches to target a miRNA with the aim of altering conditions such as osteoarthritis, osteoporosis and bone fractures in rodents. We will not discuss miRNAs in the context skeletal cancers since this topic is worthy of a review of its own. Overall, we aim to provide a comprehensive description of where the field currently stands with respect to the therapeutic potential of specific miRNAs to treat orthopaedic conditions and current technologies to target and modify miRNA function in vivo. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:33-51, 2018.

Extracellular genomic biomarkers of osteoarthritis

INTRODUCTION

Osteoarthritis (OA), a chronic, debilitating and degenerative disease of the joints, is the most common form of arthritis. The seriousness of this prevalent and chronic disease is often overlooked. Disease modifying OA drug development is hindered by the lack of soluble biomarkers to detect OA early. The objective of OA biomarker research is to identify early OA prior to the appearance of radiographic signs and the development of pain. Areas covered: This review has focused on extracellular genomic material that could serve as biomarkers of OA. Recent studies have examined the expression of extracellular genomic material such as miRNA, lncRNA, snoRNA, mRNA and cell-free DNA, which are aberrantly expressed in the body fluids of OA patients. Changes in genomic content of peripheral blood mononuclear cells in OA could also function as biomarkers of OA. Expert commentary: There is an unmet need for soluble biomarkers for detecting and then monitoring OA disease progression. Extracellular genomic material research may also reveal more about the underlying pathophysiology of OA. Minimally-invasive liquid biopsies such as synovial fluid and blood sampling of genomic material may be more sensitive over radiography in the detection, diagnosis and monitoring of OA in the future.

Expression of miR-206 in Human Knee Articular Chondrocytes and Effects of miR-206 on Proliferation and Apoptosis of Articular Chondrocytes

BACKGROUND

Increasing evidence has demonstrated that microRNAs regulate the development of cartilage and osteogenesis. Whether miR-206 participates in the development of human articular cartilage remains largely unknown. This study aimed to investigate the role of miR-206 in human chondrocytes.

METHODS

Expression of miR-206 was initially assessed in human osteoarthritis (OA) tissues and articular chondrocytes through quantitative real-time polymerase chain reaction. The effects of miR-206 on proliferation and apoptosis of human chondrocytes were assessed by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) double staining assay. Then, the effects of miR-206 on type II collagen alpha 1 (Col2a1), aggrecan, runt-related transcription factor 2 (RUNX2) and matrix metalloproteinase13 (MMP13) were examined with quantitative real-time polymerase chain reaction and Western blot analysis.

RESULTS

MiR-206 was significantly increased in human OA tissues and chondrocytes. MiR-206 significantly inhibited the proliferation of chondrocytes, but promoted apoptosis. Expression of Col2a1 and aggrecan were dramatically decreased, and the expression of RUNX2 and MMP13 were significantly increased when miR-206 was overexpressed.

CONCLUSIONS

MiR-206 may participate in cartilage degradation in OA. Manipulation of the expression of miR-206 in human chondrocytes may be a novel therapeutic strategy for the treatment of OA.

Inhibition of miR-20 promotes proliferation and autophagy in articular chondrocytes by PI3K/AKT/mTOR signaling pathway

Osteoarthritis is a common cause of functional deterioration in older adults and is an immense burden on the aging population. The molecular mechanism underlying the regulation of chondrocyte requires further elucidation, particularly with respect to the role of microRNAs. The aim of this study was to identify and characterize the expression of miR-20 in normal and OA chondrocytes, and to determine its role in OA pathogenesis. MiR-20 expression in cartilage specimens was examined in 30 patients with knee osteoarthritis and 30 traumatic amputees. The effect of miR-20 on chondrocyte was also investigated in chondrocyte cell line. Transfection with miR-20 mimic or inhibitor was employed to investigate the effect of miR-20 on chondrocyte proliferation and autophagy. Cell proliferation activity was detected by MTT assay and clone formation, cell autophagy were evaluated by monodansylcadaverine staining and GFP-LC3 fluorescence microscopy. Western blotting and immunohistochemical were utilized to detect expressions of autophagy markers (LC3, Beclin1 and p62) and of relevant proteins in the PI3K/AKT/mTOR signaling pathway. The results demonstrated that miR-20 inhibit chondrocyte proliferation and autophagy by targeting ATG10 via PI3K/AKT/mTOR signaling pathway. Our data suggest that miR-20 has an important role in the pathogenesis of osteoarthritis and is a potential therapeutic target.

MiR-455-3p activates Nrf2/ARE signaling via HDAC2 and protects osteoblasts from oxidative stress

BACKGROUND

The important role of miR-455-3p in the pathogenesis of bone metabolism associated diseases is gradually emerging. This study aims to ascertain the involvement of miR-455-3p and its underlying mechanisms in osteoporosis.

METHODS

The osteoblast cell lines MC3T3-E1 was treated with ferric ammonium citrate (FAC) to mimic a pathological environment for osteoporosis. The cytotoxic effect of iron overload was assessed by proliferation, apoptosis and oxidative stress of osteoblasts using commercial kits. Molecular biological methods, including qRT-PCR analysis, cell transfection and luciferase reporter assays were used to explain the role of miR-455-3p and its potential mechanisms in osteoblast apoptosis.

RESULTS

FAC dramatically inhibited the proliferation of osteoblast cells MC3T3-E1 but increased the apoptosis. We also observed that FAC significantly down-regulated miR-455-3p in MC3T3-E1 cells but enhanced HDAC2 protein level. Moreover, miR-455-3p overexpression eliminated the effects of iron overload on osteoblast cell proliferation, apoptosis and oxidative stress. In addition, miR-455-3p regulated osteoblast cell proliferation, apoptosis and oxidative stress through regulating HDAC2-Nrf2/ARE signaling pathway. MiR-455-3p overexpression alleviated the oxidative stress injury in osteoporosis mice.

CONCLUSION

Our results demonstrated that miR-455-3p activated Nrf2/ARE signal pathway through suppressing Keap1 via negative regulating HDAC2 protein level, thereby suppressing oxidative stress and promoting osteoblasts growth.

MicroRNA-455-3p as a potential peripheral biomarker for Alzheimer's disease

The purpose of our study was to identify microRNAs (miRNAs) as early detectable peripheral biomarkers in Alzheimer's disease (AD). To achieve our objective, we assessed miRNAs in serum samples from AD patients and Mild cognitive impairment (MCI) subjects relative to healthy controls. We used Affymetrix microarray analysis and validated differentially expressed miRNAs using qRT-PCR. We further validated miRNA data using AD postmortem brains, amyloid precursor protein transgenic mice and AD cell lines. We identified a gradual upregulation of four miRNAs: miR-455-3p, miR-4668-5p, miR-3613-3p and miR-4674. A fifth miRNA, mir-6722, was down-regulated in persons with AD and mild cognitive impairment compared with controls. Validation analysis by qRT-PCR showed significant upregulation of only miR-455-3p (P = 0.007) and miR-4668-5p (P = 0.016) in AD patients compared with healthy controls. Furthermore, qRT-PCR analysis of the AD postmortem brains with different Braak stages also showed upregulation of miR-455-3p (P = 0.016). However, receiver operating characteristic curves (ROC) curve analysis revealed a significant area under curve (AUC) value only for miR-455-3p in the serum (AUROC = 0.79; P = 0.015) and brains (AUROC = 0.86; P = 0.016) of AD patients. Expression analysis of amyloid precursor protein transgenic mice also revealed high level of mmu-miR-455-3p (P = 0.004) in the cerebral cortex (AD-affected) region of brain and low in the non-affected area, i.e. cerebellum. Furthermore, human and mouse neuroblastoma cells treated with the amyloid-β(1-42) peptide also showed a similarly higher expression of miR-455-3p. Functional analysis of differentially expressed miRNAs via the miR-path indicated that miR-455-3p was associated in the regulation of several biological pathways. Genes associated with these pathways were found to have a crucial role in AD pathogenesis. An increase in miR-455-3p expression found in AD patients and Aβ pathologies unveiled its biomarker characteristics and a precise role in AD pathogenesis.

Intra-articular injection of microRNA-140 (miRNA-140) alleviates osteoarthritis (OA) progression by modulating extracellular matrix (ECM) homeostasis in rats

OBJECTIVE

Disruptions of extracellular matrix (ECM) homeostasis are key events in the pathogenesis of osteoarthritis (OA). MicroRNA-140 (miRNA-140) is expressed specifically in cartilage and regulates ECM-degrading enzymes. Our objective in this study was to determine if intra-articular injection of miRNA-140 can attenuate OA progression in rats.

DESIGN

miRNA-140 levels in human normal and OA cartilage derived chondrocytes and synovial fluid were assessed by polymerase chain reaction (PCR). After primary human chondrocytes were transfected with miRNA-140 mimic or inhibitor, PCR and western blotting were performed to quantify Collagen II, MMP-13, and ADAMTS-5 expression. An OA model was induced surgically in rats, and subsequently treated with one single intra-articular injection of miRNA-140 agomir. At 4, 8, and 12 weeks after surgery, OA progression were evaluated macroscopically, histologically, and immunohistochemically in these rats.

RESULTS

miRNA-140 levels were significantly reduced in human OA cartilage derived chondrocytes and synovial fluid compared with normal chondrocytes and synovial fluid. Overexpressing miRNA-140 in primary human chondrocytes promoted Collagen II expression and inhibited MMP-13 and ADAMTS-5 expression. miRNA-140 levels in rat cartilage were significantly higher in the miRNA-140 agomir group than in the control group. Moreover, behavioural scores, chondrocyte numbers, cartilage thickness and Collagen II expression levels in cartilage were significantly higher, while pathological scores and MMP-13 and ADAMTS-5 expression levels were significantly lower in the miRNA-140 agomir group than in the control group.

CONCLUSION

Intra-articular injection of miRNA-140 can alleviate OA progression by modulating ECM homeostasis in rats, and may have potential as a new therapy for OA.

Identification of transforming growth factor-beta-regulated microRNAs and the microRNA-targetomes in primary lung fibroblasts

Background

Lung fibroblasts are involved in extracellular matrix homeostasis, which is mainly regulated by transforming growth factor-beta (TGF-β), and are therefore crucial in lung tissue repair and remodeling. Abnormal repair and remodeling has been observed in lung diseases like COPD. As miRNA levels can be influenced by TGF-β, we hypothesized that TGF-β influences miRNA expression in lung fibroblasts, thereby affecting their function.

Materials and methods

We investigated TGF-β1-induced miRNA expression changes in 9 control primary parenchymal lung fibroblasts using miRNA arrays. TGF-β1-induced miRNA expression changes were validated and replicated in an independent set of lung fibroblasts composted of 10 controls and 15 COPD patients using qRT-PCR. Ago2-immunoprecipitation followed by mRNA expression profiling was used to identify the miRNA-targetomes of unstimulated and TGF-β1-stimulated primary lung fibroblasts (n = 2). The genes affected by TGF-β1-modulated miRNAs were identified by comparing the miRNA targetomes of unstimulated and TGF-β1-stimulated fibroblasts.

Results

Twenty-nine miRNAs were significantly differentially expressed after TGF-β1 stimulation (FDR<0.05). The TGF-β1-induced miR-455-3p and miR-21-3p expression changes were validated and replicated, with in addition, lower miR-455-3p levels in COPD (p<0.05). We identified 964 and 945 genes in the miRNA-targetomes of unstimulated and TGF-β1-stimulated lung fibroblasts, respectively. The TGF-β and Wnt pathways were significantly enriched among the Ago2-IP enriched and predicted targets of miR-455-3p and miR-21-3p. The miR-455-3p target genes HN1, NGF, STRADB, DLD and ANO3 and the miR-21-3p target genes HHEX, CHORDC1 and ZBTB49 were consistently more enriched after TGF-β1 stimulation.

Conclusion

Two miRNAs, miR-455-3p and miR-21-3p, were induced by TGF-β1 in lung fibroblasts. The significant Ago2-IP enrichment of targets of these miRNAs related to the TGF-β and/or Wnt pathways (NGF, DLD, HHEX) in TGF-β1-stimulated fibroblasts suggest a role for these miRNAs in lung diseases by affecting lung fibroblast function.

A bioinformatic analysis of microRNAs role in osteoarthritis

OBJECTIVE

To evaluate the underlying function of microRNAs (miRNAs) in osteoarthritis (OA).

DESIGN

A bioinformatic analysis of miRNAs-OA studies was completed in multiple databases. All identified articles were assessed using specific inclusion and exclusion criteria (Eligible case-control studies for the present study included those which investigated miRNAs differential expression in cartilage tissues and cells of OA and controls. Abstracts, case reports, conference presentations, editorials, and expert opinions were excluded.). We performed bioinformatic analysis and assessed which miRNAs are commonly elevated or decreased in cartilage of OA, and assessed putative targets of these miRNAs using TargetScan, Database for Annotation, Visualization and Integrated Discovery (DAVID), FunRich and String.

RESULTS

Fifty seven studies were included in this study. Our current review has identified 46 differentially expressed miRNAs involved in autophagy, inflammation, chondrocyte apoptosis, chondrocyte differentiation & homeostasis, chondrocyte metabolism and degradation of the extracellular matrix (ECM). Additionally, our literature search identified a wide range of miRNAs that have been shown to be differentially expressed in OA. The function of up-regulated miRNAs primarily target nucleus, whereas the function of down-regulated miRNAs primarily target transcription.

CONCLUSIONS

Comprehensive analysis of all miRNAs studies reveals cooperation in miRNA signatures and suggests that there may be two biologically synergic classes of miRNAs that are associated with OA. This finding suggests that miRNAs may be useful as diagnostic biomarkers and/or may provide new therapeutic targets in OA. Furthermore, a better understanding of the targets of these miRNAs will accelerate biomedical discoveries and improve clinical care based on new knowledge of OA-related disease mechanisms.

Long noncoding RNA DANCR regulates miR-1305-Smad 4 axis to promote chondrogenic differentiation of human synovium-derived mesenchymal stem cells

miRNAs have been reported to regulate cellular differentiation by modulating multiple signaling pathways. Long noncoding RNA (lnc RNA) DANCR was previously identified to be critical for the chondrogenesis of human synovium-derived mesenchymal stem cells (SMSC), however, the underlying molecular mechanism requires better understanding. Here, miRNA expression profiling in DANCR overexpressed in SMSCs identified significant down-regulation of miR-1305, which serves as a downstream target of DANCR. Notably, miR-1305 overexpression reversed DANCR-induced cell proliferation and chondrogenic differentiation of SMSCs, which suggested that miR-1305 antagonized the function of DANCR. Mechanistically, highly expressed miR-1305 resulted in the decreased expression of the TGF-β pathway member Smad4, and inhibition of miR-1305 enhanced the expression level of Smad4. Depletion of Smad4 suppressed the promotion of DANCR in cell proliferation and chondrogenesis of SMSCs. Collectively, our results characterized miR-1305-Smad4 axis as a major downstream functional mechanism of lncRNA DANCR in promoting the chondrogenesis in SMSCs.

Genomics and epigenomics in rheumatic diseases: what do they provide in terms of diagnosis and disease management?

Most rheumatic diseases are complex or multifactorial entities with pathogeneses that interact with both multiple genetic factors and a high number of diverse environmental factors. Knowledge of the human genome sequence and its diversity among populations has provided a crucial step forward in our understanding of genetic diseases, identifying many genetic loci or genes associated with diverse phenotypes. In general, susceptibility to autoimmunity is associated with multiple risk factors, but the mechanism of the environmental component influence is poorly understood. Studies in twins have demonstrated that genetics do not explain the totality of the pathogenesis of rheumatic diseases. One method of modulating gene expression through environmental effects is via epigenetic modifications. These techniques open a new field for identifying useful new biomarkers and therapeutic targets. In this context, the development of "-omics" techniques is an opportunity to progress in our knowledge of complex diseases, impacting the discovery of new potential biomarkers suitable for their introduction into clinical practice. In this review, we focus on the recent advances in the fields of genomics and epigenomics in rheumatic diseases and their potential to be useful for the diagnosis, follow-up, and treatment of these diseases. The ultimate aim of genomic studies in any human disease is to understand its pathogenesis, thereby enabling the prediction of the evolution of the disease to establish new treatments and address the development of personalized therapies.

Screening of candidate key genes associated with human osteosarcoma using bioinformatics analysis

The aim of the present study was to identify the key genes associated with osteosarcoma (OS) using a bioinformatics approach. Microarray data (GSE36004) was downloaded from the Gene Expression Omnibus database, including 19 OS cell lines and 6 normal controls. Differentially expressed genes (DEGs) in the OS cell lines were identified using the Limma package, and differentially methylated regions were screened with methyAnalysis in R. Copy number analysis was performed and genes with copy number gains/losses were further screened using DNAcopy and cghMCR packages. Functional enrichment analyses were performed using the Database for Annotation, Visualization and Integrated Discovery online tool, and protein-protein interactions were identified based on information obtained from the Search Tool for the Retrieval of Interacting Genes database. A total of 47 downregulated genes were screened in hyper-methylated regions, including the fragment crystallizable (Fc) region of immunoglobulin E, high affinity I, receptor for; γ polypeptide (FCER1G), leptin (LEP) and feline Gardner-Rasheed sarcoma viral oncogene homolog (FGR). In addition, a total of 17 upregulated genes, including the TPase family, AAA domain containing 2 (ATAD2) and cyclin-dependent kinase 4 (CDK4), exhibited copy number gains, while 5 downregulated genes, including Rho GTPase activating protein 9 (ARHGAP9) and major histocompatibility complex, class II, DO α (HLA-DOA), exhibited copy number losses. These results indicate that hyper-methylation of FCER1G, LEP, and FGR may serve a crucial function in the development of OS. In addition, copy number alterations of these DEGs, including ATAD2, CDK4, ARHGAP9 and HLA-DOA, may also contribute to OS progression. These DEGs may be candidate targets for the diagnosis and treatment of this disease.

miRNA-140 inhibits C3H10T1/2 mesenchymal stem cell proliferation by targeting CXCL12 during transforming growth factor-β3-induced chondrogenic differentiation

The aim of the present study was to investigate the role of microRNA (miRNA or miR)-140 in C3H10T1/2 mesenchymal stem cells (MSCs). Cluster analysis was used to evaluate the miRNA expression profile. The expression level of miRNA‑140 was validated by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR). TargetScan and microRNA.org databases were used to predict target miRNAs and cartilage‑associated target genes. Binding sites between miR‑140 and the target gene were predicted by bioinformatics software. A dual‑luciferase reporter assay was performed to determine whether miR‑140 could target C‑X‑C motif chemokine ligand 12 (CXCL12). Following the promotion/inhibition of miR‑140, 1, 7 and 14 days following transforming growth factor‑β3 (TGF‑β3)‑induction, western blotting was utilized to evaluate CXCL12 protein levels. MTT assays and alcian blue staining were applied to assess C3H10T1/2 MSC viability and chondrogenic differentiation, respectively. In the TGF‑β3‑induced group, RT‑qPCR verified that the mRNA level of Mus musculus (mmu)‑miR‑140 was significantly elevated when compared with the control group. miR‑140 was predicted to recognize and interact with CXCL12‑3'UTR and the dual luciferase reporter assay further validated that miR‑140 targeted the predicted region of CXCL12. CXCL12 was markedly decreased following miR‑140 overexpression and visibly increased following miR‑140 inhibition. In addition, the level of CXCL12 expression declined as the duration of induction increased. Following the promotion/inhibition of miR‑140, at 1 and 7 days following TGF‑β3‑induction, C3H10T1/2 MSCs inhibited or promoted cell viability, respectively, when compared with the control groups. In addition, in pellets achieved by chondrogenic differentiation following the induction of C3H10T1/2 MSCs for 7 days, alcian blue staining revealed no significant difference in characteristic extracellular matrix glycosaminoglycans between the miR‑140 up and downregulated groups, and their respective control groups. The present study concludes that miRNA‑140 inhibition promoted C3H10T1/2 MSC viability however, not C3H10T1/2 MSC differentiation by targeting and reducing CXCL12 protein levels during the process of TGF‑β3‑induced chondrogenic differentiation. In conclusion, the present study provided a potential target for the treatment of cartilage defection.

MiR-146b is down-regulated during the chondrogenic differentiation of human bone marrow derived skeletal stem cells and up-regulated in osteoarthritis

Articular cartilage injury can result in chondrocyte loss and diminishment of specialised extracellular matrix, which can progress to an osteoarthritic (OA) phenotype. Stem cells have emerged as a favourable approach for articular cartilage regeneration. Identification of miRNAs which influence stem cell fate offers new approaches for application of miRNAs to regenerate articular cartilage. Skeletal stem cells (SSCs) isolated from human bone marrow were cultured as high density micromass' using TGF-β3 to induce chondrogenesis. qPCR and TaqMan qPCR were used to assess chondrogenic gene and miRNA expression. Target prediction algorithms identified potential targets of miR-146b. Transient transfection with miR-146b mimic and western blotting was used to analyse SOX5. Human OA articular chondrocytes were examined for miR-146b expression. Chondrogenic differentiation of human bone marrow derived SSCs resulted in significant down-regulation of miR-146b. Gain of miR-146b function resulted in down-regulation of SOX5. MiR-146b expression was up-regulated in OA chondrocytes. These findings demonstrate the functional role of miR-146b in the chondrogenic differentiation of human bone marrow derived SSCs. MiR-146b may play a role in the pathophysiology of OA. Application of miR-146b combined with stem cell therapy could enhance regeneration of cartilaginous tissue and serve as a potential therapeutic target in the treatment of OA.

MicroRNA expression in esophageal squamous cell carcinoma: Novel diagnostic and prognostic biomarkers

The aim of the present study was to identify more effective molecular diagnostic biomarkers for esophageal squamous cell carcinoma (ESCC). The non‑coding RNA profile GSE43732, generated from 238 paired frozen tissues from 119 patients, was analyzed. Raw data were preprocessed and the differentially expressed miRNAs were screened by limma package with log2 fold change >2. Prognosis‑associated miRNAs were identified using receiver operating characteristic (ROC) and Kaplan-Meier (KM) curve analysis. miRNAs with an area under the ROC curve of ≥0.7 were selected. miRNA target genes were identified from verification and predictive databases, and an miRNA regulatory network was constructed and visualized using Cytoscape software. Gene Ontology and pathway enrichment analyses of the target genes were performed using TargetMine. A total of 107 differentially expressed miRNAs, including 54 upregulated and 53 downregulated miRNAs, were obtained. The KM survival curves revealed that 44 miRNAs were significantly associated with prognosis. Furthermore, 9 upregulated and 3 downregulated miRNAs were obtained. Two upregulated miRNAs, hsa‑miR‑143‑3p and hsa‑miR‑145‑5p, and two downregulated miRNAs, hsa‑miR‑182‑5p and hsa‑miR‑455‑5p, were identified and demonstrated to be associated with prognosis in ESCC. In addition, 8 known and 245 predicted target genes of hsa‑miR‑455‑5p were screened and the regulatory networks were constructed. Furthermore, these genes were functionally associated with macromolecule metabolic process and melanoma. In conclusion, two novel tumor suppressive miRNAs including miR‑182‑5p and miR‑455‑5p were identified. miR‑455‑5p in particular may be involved in the regulation of ESCC. These miRNAs may be used to predict the prognosis of ESCC.

Expression levels of microRNA‑455 and its potential functions by targeting IGF‑1R in melanoma

Melanoma has the highest fatality and malignancy of all skin cancers. In cancer, microRNAs (miRNAs) act as tumor suppressors or oncogenes, and inactivation of oncogenic miRNAs or restoration of tumor suppressor miRNAs has potential for cancer treatment. In the present study, miR‑455 expression levels were examined in melanoma tissues and cell lines, and miR‑455 was significantly downregulated in melanoma compared with matched normal tissues or normal epidermal melanocytes. In addition, increasing miR‑455 expression in melanoma cells reduced cell proliferation and invasion. Bioinformatic analysis revealed that insulin‑like growth factor 1 receptor (IGF‑1R) was a putative target of miR‑455. Luciferase reporter assays, reverse transcription‑quantitative polymerase chain reaction and western blot confirmed that miR‑455 targeted the 3'‑untranslated region of IGF‑1R and thus regulated the biological processes of melanoma cells. IGF‑1R knockdown resulted in similar effects as miR‑455 overexpression in melanoma cells. In summary, these findings indicated that miR‑455 was downregulated in melanoma, and inhibited proliferation and invasion of melanoma cells through directly targeting IGF‑1R. This also suggested that the restoration of miR‑455 may be worth investigation as a therapeutic treatment for patients with melanoma.

Upregulation of microRNA-125b-5p is involved in the pathogenesis of osteoarthritis by downregulating SYVN1

Osteoarthritis (OA) is a degenerative disease characterized by deterioration of articular cartilage. The aim of this study was to identify and characterize the expression of microRNA-125b-5p (miR-125b-5p) in normal and OA synovial cells, and to determine its role in OA pathogenesis. First, the levels of miR-125b-5p and synoviolin 1 (SYVN1) were detected among normal, mild OA and severe OA groups with the use of quantitative PCR. Computational analysis was used to search for the target of the miR-125b-5p, and luciferase reporter assay system was used to validate SYVN1 as the target gene of miR-125b-5p. Then the SYVN1 expression level of cells transfected with miR-125b-5p mimics or inhibitors was estimated using quantitative PCR and western blotting. Finally, MTT assay was employed to estimate the effect of miR-125b-5p on apoptosis. We enrolled 36 participants consisting of 12 normal control, 12 mild OA and 12 severe OA, furthermore, we performed quantitative PCR to detect the levels of miR-125b-5p and SYVN1 among those groups, and found that miR-125b-5p was expressed at highest level in severe OA compared with normal control and mild OA groups, while SYVN1 was expressed at the lowest level in severe OA. Additionally, we identified that SYVN1 is a target of miR-125b-5p by using computational analysis and luciferase assay. Transfection with miR-125b-5p mimic or inhibitor was employed to investigate the effect of miR-125b-5p on expression of SYVN1 in synovial cells, and synovial cell viability and apoptosis, and the results showed that miR-125b-5p mimics significant decreased the expression of SYVN1, a substantially promoted apoptosis of synovial cells, while miR-125b-5p inhibitors remarkably increased the level of SYVN1, and substantially suppressed apoptosis of synovial cells. The data suggested that miR-125b-5p promoted apoptosis of synovial cells through targeting SYVN1 gene, with important implication for validating miR-125b-5p as a potential target for OA therapy.

Osteoarthritis year in review 2016: genetics, genomics and epigenetics

The purpose of this narrative review is to provide an overview of last year's publications in the field of genetics, genomics and epigenetics in the osteoarthritis (OA) field. Major themes arising from a Pubmed search on (epi)genetics in OA were identified. In addition, general developments in the fast evolving field of (epi)genetics are reviewed and relevance for the OA field is summarized. In the last 5 years, a number of genome-wide association studies have identified a modest number of genetic loci associated to OA. Continued functional research into these DNA variants is showing putative biological mechanisms underlying these associations. Over the last year, no additional large genome-wide association studies were published, but there clearly remains much to be discovered in the OA genetic field. A lot of research has been done into the epigenetics of OA over the last year. Several genome-wide screens examining the methylome of osteoarthritic cartilage were done. Pathway analysis confirmed deregulation of developmental and extracellular pathways in OA cartilage. Over the last year many microRNAs (miRNAs) have been identified that potentially play important roles in cartilage homeostasis and/or OA process. Continued research will learn whether these identified miRNAs are truly causal and can be used in clinical applications. Many of the epigenetic findings need further confirmation, but they highlight potential novel pathways involved in cartilage biology and OA.

Emerging roles for long noncoding RNAs in skeletal biology and disease

Normal skeletal development requires tight coordination of transcriptional networks, signaling pathways, and biomechanical cues, and many of these pathways are dysregulated in pathological conditions affecting cartilage and bone. Recently, a significant role has been identified for long noncoding RNAs (lncRNAs) in developing and maintaining cellular phenotypes, and improvements in sequencing technologies have led to the identification of thousands of lncRNAs across diverse cell types, including the cells within cartilage and bone. It is clear that lncRNAs play critical roles in regulating gene expression. For example, they can function as epigenetic regulators in the nucleus via chromatin modulation to control gene transcription, or in the cytoplasm, where they can function as scaffolds for protein-binding partners or modulate the activity of other coding and noncoding RNAs. In this review, we discuss the growing list of lncRNAs involved in normal development and/or homeostasis of the skeletal system, the potential mechanisms by which these lncRNAs might function, and recent improvements in the methodologies available to study lncRNA functions in vitro and in vivo. Finally, we address the likely utility of lncRNAs as biomarkers and therapeutic targets for diseases of the skeletal system, including osteoarthritis, osteoporosis, and in cancers of the skeletal system.

Inflammation and epigenetic regulation in osteoarthritis

Osteoarthritis (OA) was once defined as a non-inflammatory arthropathy, but it is now well-recognized that there is a major inflammatory component to this disease. In addition to synovial cells, articular chondrocytes and other cells of diarthrodial joints are also known to express inflammatory mediators. It has been proposed that targeting inflammation pathways could be a promising strategy to treat OA. There have been many reports of cross-talk between inflammation and epigenetic factors in cartilage. Specifically, inflammatory mediators have been shown to regulate levels of enzymes that catalyze changes in DNA methylation and histone structure, as well as alter levels of non-coding RNAs. In addition, expression levels of a number of these epigenetic factors have been shown to be altered in OA, thereby suggesting potential interplay between inflammation and epigenetics in this disease. This review provides information on inflammatory pathways in arthritis and summarizes published research on how epigenetic regulators are affected by inflammation in chondrocytes. Furthermore, we discuss data showing how altered expression of some of these epigenetic factors can induce either catabolic or anti-catabolic effects in response to inflammatory signals. A better understanding of how inflammation affects epigenetic factors in OA may provide us with novel therapeutic strategies to treat this condition.

Roles of microRNA and signaling pathway in osteoarthritis pathogenesis

Osteoarthritis (OA) is a common chronic degenerative joint disease, with complicated pathogenic factors and undefined pathogenesis. Various signaling pathways play important roles in OA pathogenesis, including genetic expression, matrix synthesis and degradation, cell proliferation, differentiation, apoptosis, and so on. MicroRNA (miRNA) is a class of non-coding RNA in Eukaryon, regulating genetic expression on the post-transcriptional level. A great number of miRNAs are involved in the development of OA, and are closely associated with different signaling pathways. This article reviews the roles of miRNAs and signaling pathways in OA, looking toward having a better understanding of its pathogenesis mechanisms and providing new therapeutic targets for its treatment.

Insights on Molecular Mechanisms of Chondrocytes Death in Osteoarthritis

Osteoarthritis (OA) is a joint pathology characterized by progressive cartilage degradation. Medical care is mainly based on alleviating pain symptoms. Compelling studies report the presence of empty lacunae and hypocellularity in cartilage with aging and OA progression, suggesting that chondrocyte cell death occurs and participates to OA development. However, the relative contribution of apoptosis per se in OA pathogenesis appears complex to evaluate. Indeed, depending on technical approaches, OA stages, cartilage layers, animal models, as well as in vivo or in vitro experiments, the percentage of apoptosis and cell death types can vary. Apoptosis, chondroptosis, necrosis, and autophagic cell death are described in this review. The question of cell death causality in OA progression is also addressed, as well as the molecular pathways leading to cell death in response to the following inducers: Fas, Interleukin-1β (IL-1β), Tumor Necrosis factor-α (TNF-α), leptin, nitric oxide (NO) donors, and mechanical stresses. Furthermore, the protective role of autophagy in chondrocytes is highlighted, as well as its decline during OA progression, enhancing chondrocyte cell death; the transition being mainly controlled by HIF-1α/HIF-2α imbalance. Finally, we have considered whether interfering in chondrocyte apoptosis or promoting autophagy could constitute therapeutic strategies to impede OA progression.