Comparison of microRNA expression profiles of Kashin-Beck disease, osteoarthritis and rheumatoid arthritis

Potential involvement of connective tissue growth factor in chondrocytes apoptosis of Kashin-Beck disease

BACKGROUND

Kashin-Beck disease (KBD) is an endemic osteoarthropathy characterized by excessive chondrocytes apoptosis. T-2 toxin exposure has been proved to be its etiology. Connective tissue growth factor (CTGF) exerts a profound influence on cartilage growth and metabolism. We investigated the potential role of CTGF in KBD development and examined CTGF alterations under T-2 toxin stimulation.

METHODS

The levels of CTGF and chondrocyte apoptosis-related markers in cartilage and primary chondrocytes from KBD and control groups were measured using qRT-PCR, Western blotting, immunohistochemistry, and immunofluorescence. We analyzed expression changes of these genes in response to T-2 toxin. Apoptosis rates of chondrocytes induced by T-2 toxin were measured by flow cytometry and TUNEL assay. The active pharmaceutical ingredient targeting CTGF was screened through Comparative Toxicogenomics Database, and molecular docking was performed using AutoDock Tools.

RESULTS

The CTGF levels in KBD cartilage and chondrocytes were significantly elevated and positively associated with the levels of apoptosis-related genes. T-2 toxin exposure increased CTGF and apoptosis-related gene levels in chondrocytes, with apoptosis rates rising alongside T-2 toxin concentration. Curcumin was identified as targeting CTGF and exhibited effective binding. It could down-regulate CTGF, apoptosis-related genes, such as Cleaved caspase 3 and BAX, and also significantly reduce apoptosis rate in chondrocytes treated with T-2 toxin.

CONCLUSION

CTGF plays a crucial role in the development of KBD. Curcumin has shown potential in inhibiting CTGF levels and reducing chondrocyte apoptosis, highlighting its promise as a therapeutic agent for preventing cartilage damage in KBD. Our findings provided valuable insights into the pathogenesis of KBD and could promote the development of novel therapeutic strategies for this debilitating disease.

Modulation of Ras signaling pathway by exosome miRNAs in T-2 toxin-induced chondrocyte injury

This study aims to investigate the impact of T-2 toxin on the regulation of downstream target genes and signaling pathways through exosome-released miRNA in the development of cartilage damage in Kashin-Beck disease (KBD). Serum samples from KBD patients and supernatant from C28/I2 cells treated with T-2 toxin were collected for the purpose of comparing the differential expression of exosomal miRNA using absolute quantitative miRNA-seq. Target genes of differential exosomal miRNAs were identified using Targetscan and Miranda databases, followed by GO and KEGG enrichment analyses. Validation of key indicators of chondrocyte injury in KBD was conducted using Real-time quantitative PCR (RT-qPCR) and Immunohistochemical staining (IHC). A total of 20 exosomal miRNAs related to KBD were identified in serum, and 13 in chondrocytes (C28/I2). The identified exosomal miRNAs targeted 48,459 and 60,612 genes, primarily enriched in cell organelles and membranes, cell differentiation, and cytoskeleton in the serum, and the cytoplasm and nucleus, metal ion binding in chondrocyte (C28/I2). The results of the KEGG enrichment analysis indicated that the Ras signaling pathway may play a crucial role in the pathogenesis of KBD. Specifically, the upregulation of hsa-miR-181a-5p and hsa-miR-21-3p, along with the downregulation of hsa-miR-152-3p and hsa-miR-186-5p, were observed. Additionally, T-2 toxin intervention led to a significant downregulation of RALA, REL, and MAPK10 expression. Furthermore, the protein levels of RALA, REL, and MAPK10 were notably decreased in the superficial and middle layers of cartilage tissues from KBD. The induction of differential expression of chondrocyte exosomal miRNAs by T-2 toxin results in the collective regulation of target genes RALA, REL, and MAPK10, ultimately mediating the Ras signaling pathway and causing a disruption in chondrocyte extracellular matrix metabolism, leading to chondrocyte injury.

Integration of miRNA in exosomes and single-cell RNA-seq profiles in endemic osteoarthritis, Kashin-Beck disease

Kashin-Beck disease (KBD) is an endemic, chronic degenerative joint disease in China. Exosomes miRNAs, as signaling molecules in intercellular communication, can transfer specific biological martials into target cell to regulate their function and might participate in the pathogenesis of KBD. We isolated serum and chondrocytes-derived exosomes, miRNA sequencing revealed exosomes miRNA profiles and differentially expressed miRNAs (DE-miRNAs) were identified. The target genes were predicted of known and novel DE-miRNAs with TargetScan 5.0 and miRanda 3.3a database. Single-cell RNA sequencing (scRNA-seq) was performed to identify chondrocyte clusters and their gene signatures in KBD. And we performed comparative analysis between the serum and chondrocytes-derived exosomes DE-miRNA target genes and differentially expressed genes of each cell clusters. A total of 20 DE-miRNAs were identified in serum-derived exosomes. In the miRNA expression of chondrocytes-derived exosomes, 53 DE-miRNAs were identified. 16,063 predicted targets were identified as the target genes in the serum-derived exosomes, 57,316 predicted targets were identified as the target genes in the chondrocytes-derived exosomes. Seven clusters were labeled by cell type according to the expression of previously described markers. Three hundred fifteen common genes were found among serum/chondrocytes-derived exosomes DE-miRNA target genes and DEGs identified by scRNA-seq analysis. We firstly integratly analyzed the serum and chondrocytes exosomes miRNA with single-cell RNA sequencing (scRNA-seq) data of KBD chondrocyte, the results showed that DE-miRNAs in exosomes might play a potential role in regulating genes expression in different KBD chondrocytes clusters by exosomes mediating cell-cell communications functions, which could improve the new diagnosis and treatment methods for KBD.

Whole-Transcriptome Sequencing of Knee Joint Cartilage from Kashin-Beck Disease and Osteoarthritis Patients

The aim of this study was to provide a comprehensive understanding of similarities and differences in mRNAs, lncRNAs, and circRNAs within cartilage for Kashin-Beck disease (KBD) compared to osteoarthritis (OA). We conducted a comparison of the expression profiles of mRNAs, lncRNAs, and circRNAs via whole-transcriptome sequencing in eight KBD and ten OA individuals. To facilitate functional annotation-enriched analysis for differentially expressed (DE) genes, DE lncRNAs, and DE circRNAs, we employed bioinformatic analysis utilizing Gene Ontology (GO) and KEGG. Additionally, using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), we validated the expression levels of four cartilage-related genes in chondrocytes. We identified a total of 43 DE mRNAs, 1451 DE lncRNAs, and 305 DE circRNAs in KBD cartilage tissue compared to OA (q value < 0.05; |log2FC| > 1). We also performed competing endogenous RNA network analysis, which identified a total of 65 lncRNA-mRNA interactions and 4714 miRNA-circRNA interactions. In particular, we observed that circRNA12218 had binding sites for three miRNAs targeting ACAN, while circRNA12487 had binding sites for seven miRNAs targeting COL2A1. Our results add a novel set of genes and non-coding RNAs that could potentially serve as candidate diagnostic biomarkers or therapeutic targets for KBD patients.

Integrative Analysis of Genome-Wide Association Studies and DNA Methylation Profile Identified Genetic Control Genes of DNA Methylation for Kashin-Beck Disease

OBJECTIVE

Epigenetic modifications of DNA are regarded as a crucial factor for understanding the molecular basis of complex phenotypes. This study aims to uncover insight into the epigenetic modifications for Kashin-Beck disease (KBD) by integrating genome-wide association studies (GWAS), methylation quantitative trait loci (meQTLs), and DNA methylation profiles data.

DESIGN

The knee articular cartilages of 5 KBD patients and 5 healthy controls were collected for DNA methylation profiling, using Illumina Infinium HumanMethylation450 BeadChip. Mass spectrograph validation of identified differently methylated genes was conducted using independent samples of 4 KBD patients and 3 healthy controls, together with a previous sample of 2743 Han Chinese individuals of GWAS study for KBD and a study of 697 normal subjects for meQTLs annotation datasets. KBD GWAS single nucleotide polymorphisms (SNPs) and normal meQTLs SNPs were integrated with DNA methylation profiles of KBD articular cartilage to identify genetic control (GC) genes of DNA methylation for KBD. Quantitative polymerase chain reaction (qPCR) was performed to validate the mRNA expression of several identified candidate genes.

RESULTS

A total of 162 CpG sites, 253 SNPs, and 123 GC genes for KBD were identified. Enrichment analysis detected 642 marked GO terms and 19 KEGG pathways (P < 0.05). Six potential key GC genes were conducted for qPCR experiment (ERG, MN1, MITF, WISP1, TRIO, and NOSTRIN).

CONCLUSIONS

The results suggest that GC genes of DNA methylation may lead to the erosion of cartilage in KBD, which may help us in understanding the epigenetic alteration of KBD.

Novel NFκB Inhibitor SC75741 Mitigates Chondrocyte Degradation and Prevents Activated Fibroblast Transformation by Modulating miR-21/GDF-5/SOX5 Signaling

Osteoarthritis (OA) is a common articular disease manifested by the destruction of cartilage and compromised chondrogenesis in the aging population, with chronic inflammation of synovium, which drives OA progression. Importantly, the activated synovial fibroblast (AF) within the synovium facilitates OA through modulating key molecules, including regulatory microRNAs (miR's). To understand OA associated pathways, in vitro co-culture system, and in vivo papain-induced OA model were applied for this study. The expression of key inflammatory markers both in tissue and blood plasma were examined by qRT-PCR, western blot, immunohistochemistry, enzyme-linked immunosorbent assay (ELISA) and immunofluorescence assays. Herein, our result demonstrated, AF-activated human chondrocytes (AC) exhibit elevated NFκB, TNF-α, IL-6, and miR-21 expression as compared to healthy chondrocytes (HC). Importantly, AC induced the apoptosis of HC and inhibited the expression of chondrogenesis inducers, SOX5, TGF-β1, and GDF-5. NFκB is a key inflammatory transcription factor elevated in OA. Therefore, SC75741 (an NFκB inhibitor) therapeutic effect was explored. SC75741 inhibits inflammatory profile, protects AC-educated HC from apoptosis, and inhibits miR-21 expression, which results in the induced expression of GDF-5, SOX5, TGF-β1, BMPR2, and COL4A1. Moreover, ectopic miR-21 expression in fibroblast-like activated chondrocytes promoted osteoblast-mediated differentiation of osteoclasts in RW264.7 cells. Interestingly, in vivo study demonstrated SC75741 protective role, in controlling the destruction of the articular joint, through NFκB, TNF-α, IL-6, and miR-21 inhibition, and inducing GDF-5, SOX5, TGF-β1, BMPR2, and COL4A1 expression. Our study demonstrated the role of NFκB/miR-21 axis in OA progression, and SC75741's therapeutic potential as a small-molecule inhibitor of miR-21/NFκB-driven OA progression.

Identification of HIF-1α/VEGFA signaling pathway and transcription factors in Kashin-Beck disease by integrated bioinformatics analysis

Kashin-Beck disease (KBD) is a chronic and endemic osteoarthropathy. The pathogenesis of KBD has yet to be fully elucidated, although previous studies have shown that its etiology may be associated with low selenium abundance and high exposure to mycotoxins, such as T-2 toxin. In the present study, the Comparative Toxicogenomics Database was used to identify key genes associated with KBD, T-2 toxin and selenium. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were used to identify the biological processes and pathways that key genes may be associated with. By searching the Search Tool for the Retrieval of Interacting Genes database and the Molecular Complex Detection plug-in with Cytoscape, it was possible to construct a KBD-associated protein-protein interaction (PPI) network, and screen the core modules and genes. Western blot analysis was subsequently used to verify the expression levels of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor A (VEGFA), two components that are associated with the HIF-1 signaling pathway in KBD disease. Via this approach, a total of 301 key genes were identified that were associated with KBD, T-2 toxin and selenium. The results of the GO and KEGG enrichment analyses demonstrated that these key genes were mainly involved in the process of apoptosis. Previous studies have demonstrated that excessive apoptosis of chondrocytes plays a crucial role in the pathophysiology of KBD, and that HIF-1α has an important role in chondrocyte apoptosis; therefore, the present study was focused on the expression level of HIF-1α in KBD. By analyzing the PPI network constructed from the key genes, a total of 10 core genes were obtained that may be associated with KBD. The results of western blotting experiments revealed that, after treating chondrocytes with different concentrations of T-2 toxin, the expression levels of HIF-1α and VEGFA were markedly downregulated. The iRegulon plug-in for Cytoscape was used to predict the transcription factors that may regulate HIF-1α and VEGFA in the HIF-1 signaling pathway. Using this approach, 10 core genes and 15 transcription factors were obtained. These results may help to clarify the pathogenesis of KBD, thereby providing further avenues for the therapeutic treatment of KBD.

Comparison of the major cell populations among osteoarthritis, Kashin-Beck disease and healthy chondrocytes by single-cell RNA-seq analysis

Chondrocytes are the key target cells of the cartilage degeneration that occurs in Kashin–Beck disease (KBD) and osteoarthritis (OA). However, the heterogeneity of articular cartilage cell types present in KBD and OA patients and healthy controls is still unknown, which has prevented the study of the pathophysiology of the mechanisms underlying the roles of different populations of chondrocytes in the processes leading to KBD and OA. Here, we aimed to identify the transcriptional programmes and all major cell populations in patients with KBD, patients with OA and healthy controls to identify the markers that discriminate among chondrocytes in these three groups. Single-cell RNA sequencing was performed to identify chondrocyte populations and their gene signatures in KBD, OA and healthy cells to investigate their differences as related to the pathogenetic mechanisms of these two osteochondral diseases. We performed immunohistochemistry and quantitative reverse-transcription PCR (qRT-PCR) assays to validate the markers for chondrocyte population. Ten clusters were labelled by cell type according to the expression of previously described markers, and one novel population was identified according to the expression of a new set of markers. The homeostatic and mitochondrial chondrocyte populations, which were identified by the expression of the unknown markers MT1X and MT2A and MT-ND1 and MT-ATP6, were markedly expanded in KBD. The regulatory chondrocyte population, identified by the expression of CHI3L1, was markedly expanded in OA. Our study allows us to better understand the heterogeneity of chondrocytes in KBD and OA and provides new evidence of differences in the pathogenetic mechanisms between these two diseases.

Dietary Selenium Regulates microRNAs in Metabolic Disease: Recent Progress

Selenium (Se) is an essential element for the maintenance of a healthy physiological state. However, due to environmental and dietary factors and the narrow safety range of Se, diseases caused by Se deficiency or excess have gained considerable traction in recent years. In particular, links have been identified between low Se status, cognitive decline, immune disorders, and increased mortality, whereas excess Se increases metabolic risk. Considerable evidence has suggested microRNAs (miRNAs) regulate interactions between the environment (including the diet) and genes, and play important roles in several diseases, including cancer. MiRNAs target messenger RNAs to induce changes in proteins including selenoprotein expression, ultimately generating disease. While a plethora of data exists on the epigenetic regulation of other dietary factors, nutrient Se epigenetics and especially miRNA regulated mechanisms remain unclear. Thus, this review mainly focuses on Se metabolism, pathogenic mechanisms, and miRNAs as key regulatory factors in Se-related diseases. Finally, we attempt to clarify the regulatory mechanisms underpinning Se, miRNAs, selenoproteins, and Se-related diseases.

Microbiome-miRNA interactions in the progress from undifferentiated arthritis to rheumatoid arthritis: evidence, hypotheses, and opportunities

The human microbiome has attracted attention for its potential utility in precision medicine. Increasingly, more researchers are recognizing changes in intestinal microbiome can upset the balance between pro- and anti-inflammatory factors of host immune system, potentially contributing to arthritis immunopathogenesis. Patients who develop rheumatoid arthritis from undifferentiated arthritis can face multiple irreversible joint lesions and even deformities. Strategies for identifying undifferentiated arthritis patients who have a tendency to develop rheumatoid arthritis and interventions to prevent rheumatoid arthritis development are urgently needed. Intestinal microbiome dysbiosis and shifts in the miRNA profile affect undifferentiated arthritis progression, and may play an important role in rheumatoid arthritis pathophysiologic process via stimulating inflammatory cytokines and disturbing host and microbial metabolic functions. However, a causal relationship between microbiome–miRNA interactions and rheumatoid arthritis development from undifferentiated arthritis has not been uncovered yet. Changes in the intestinal microbiome and miRNA profiles of undifferentiated arthritis patients with different disease outcomes should be studied together to uncover the role of the intestinal microbiome in rheumatoid arthritis development and to identify potential prognostic indicators of rheumatoid arthritis in undifferentiated arthritis patients. Herein, we discuss the possibility of microbiome–miRNA interactions contributing to rheumatoid arthritis development and describe the gaps in knowledge regarding their influence on undifferentiated arthritis prognosis that should be addressed by future studies.

Assessing the Health Loss from Kashin-Beck Disease and Its Relationship with Environmental Selenium in Qamdo District of Tibet, China

Kashin-Beck Disease (KBD) is one of major endemic diseases in China. In this study, we estimated the health loss from KBD in Qamdo district of Tibet using the years lived with disability (YLD) metric and investigated the influence of environmental selenium (Se) on it by multiple regression model. The results showed that YLD rates produced a different ranking of health loss of KBD from that produced by prevalence rates between Basu and Luolong County, with higher health loss from KBD (43.61 YLD/1000) but lower prevalence (17.86%) in Basu County. YLD rates in two counites were both highest for the 45-64 years age group. Compared with the prevalence rate, the YLD rate had a closer relation to environmental Se and was significantly negatively correlated with Se in both soil and highland barley. The multiple linear regression further revealed that Se contents in cultivated soil and highland barley were main influencing factors for the health loss of KBD, which could explain 90.5% of the variation in YLD rates. The information obtained highlights the significance of the YLD metric in exploring the environmental etiology of KBD and provides important information on which to base decisions on future prevention and control of endemic diseases.

LINC00623/miR-101/HRAS axis modulates IL-1β-mediated ECM degradation, apoptosis and senescence of osteoarthritis chondrocytes

Chondrocyte apoptosis and extracellular matrix (ECM) degeneration have been implicated in the pathogenesis of osteoarthritis (OA). Based on previously reported microarray analysis, HRAS (Harvey rat sarcoma viral oncogene homolog), a member of the RAS protein family, was chosen as a potential regulator of OA chondrocyte apoptosis and ECM degradation. HRAS expression was downregulated in OA tissues, particularly in mild-OA tissues. HRAS overexpression partially attenuated IL-1β-induced OA chondrocyte apoptosis and ECM degradation. Similar to HRAS, the long non-coding RNA LINC00623 was downregulated in OA tissues. LINC00623 knockdown enhanced IL-1β-induced OA chondrocyte apoptosis and ECM degradation, which could be partially reversed by HRAS overexpression. It has been reported that lncRNAs act as ceRNAs of miRNAs to exert their function. Herein, miR-101 was predicted to bind to both LINC00623 and HRAS, which was further confirmed by luciferase reporter and RIP assays. LINC00623 competed with HRAS for miR-101 binding, therefore reducing the inhibitory effect of miR-101 on HRAS expression. More importantly, the effect of LINC00623 was partially eliminated by miR-101 inhibition. Overall, the LINC00623/miR-101/HRAS axis modulates OA chondrocyte apoptosis, senescence and ECM degradation through MAPK signaling, which might play a critical role in OA development.

Physical Activity Prevents Cartilage Degradation: A Metabolomics Study Pinpoints the Involvement of Vitamin B6

Osteoarthritis (OA) is predominantly characterized by the progressive degradation of articular cartilage, the connective tissue produced by chondrocytes, due to an imbalance between anabolic and catabolic processes. In addition, physical activity (PA) is recognized as an important tool for counteracting OA. To evaluate PA effects on the chondrocyte lineage, we analyzed the expression of SOX9, COL2A1, and COMP in circulating progenitor cells following a half marathon (HM) performance. Therefore, we studied in-depth the involvement of metabolites affecting chondrocyte lineage, and we compared the metabolomic profile associated with PA by analyzing runners’ sera before and after HM performance. Interestingly, this study highlighted that metabolites involved in vitamin B6 salvage, such as pyridoxal 5′-phosphate and pyridoxamine 5′-phosphate, were highly modulated. To evaluate the effects of vitamin B6 in cartilage cells, we treated differentiated mesenchymal stem cells and the SW1353 chondrosarcoma cell line with vitamin B6 in the presence of IL1β, the inflammatory cytokine involved in OA. Our study describes, for the first time, the modulation of the vitamin B6 salvage pathway following PA and suggests a protective role of PA in OA through modulation of this pathway.

Osteoarthritis year in review 2018: genetics and epigenetics

OBJECTIVE

This review was designed to identify highlights of the osteoarthritis (OA) genetics and epigenetics literature published between April 2017 and January 2018.

DESIGN

A Pubmed literature search was conducted using the keywords 'osteoarthritis' and each of the following: 'genomic', 'genetic', 'epigenomic', 'epigenetic', 'histone', 'noncoding RNA', 'miRNA', 'lncRNA', 'DNA methylation', 'DNA hydroxymethylation', 'DNMT', and 'TET'. The dates of publication were restricted to 4/1/2017-1/15/2018. Results were compared to the same search terms limited to 4/1/2016-1/15/2017.

RESULTS

Virtually all search term combinations demonstrated a decrease in papers published this year compared to last, with epigenetic and miRNA/lncRNA research being stable. Despite this, numerous advances were made this year, including the second large genome-wide association study (GWAS) study of hand OA, a new twin study of hip and knee OA concordance, an extensive study of GDF5 evolution, analyses of the contribution of Dnmt3a to OA, a description of DNA methylation in a nonhuman primate model of OA, and an integrated, multi-omics analysis of DNA methylation, mRNA, and protein expression in human OA samples, among others. A variety of micro- and a few circular-RNA studies were also published, highlighting the importance of noncoding RNA in both the pathogenesis and potential treatment of OA.

CONCLUSION

Although publications have decreased slightly in the last year, genetics and epigenetics continue to be a topic of substantial research in OA, and considerable progress continues to be made in the field.

Differential miRNAomics of the synovial membrane in knee osteoarthritis induced by bilateral anterior cruciate ligament transection in rats

The differential microRNA (miRNA) omics of the synovial membrane were investigated using a rat model of knee osteoarthritis (KOA) induced by bilateral anterior cruciate ligament transection, which produced pathological biomarkers in KOA. Sprague‑Dawley rats were randomly divided into two groups; Sham‑operated and KOA‑operated group. The KOA rats were subjected to bilateral anterior cruciate ligament transection. After 6 weeks, total RNA was extracted from the knee joint synovial membrane of the rats and a microRNA (miR) microarray was performed to identify differentially expressed miRs. Subsequently, the obtained differentially expressed miRs were validated by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) analysis. A total of 24 miRs were identified with alterations ≥1.5‑fold in the synovial membrane in the KOA‑operated group compared with the sham‑operated group, of which 4 miRs (miR‑532‑5p, ‑200b‑5p, ‑377‑3p and ‑759‑5p) were decreased and 20 miRs (miR‑382‑3p, ‑223‑3p, ‑100‑5p, ‑30d‑5p, ‑183‑5p, ‑130, ‑92b‑3p, ‑125b‑3p, ‑151‑3p, ‑155‑3p, 27a‑3p, ‑146b‑3p, ‑885‑5p, ‑352, ‑184, ‑345‑5p, ‑30a‑5p and ‑9a‑5p) were increased. Subsequently, RT‑qPCR was used to validate the expressions of miR‑223, ‑100, ‑345, ‑130, ‑382, ‑377, ‑352, ‑200b, ‑9a and ‑183, which were upregulated by a fold change of ≥1.5 in synovial membranes of KOA rats compared with shams. Furthermore, in vitro miR‑223 mimic could suppress the luciferase activity of NACHT, LRR and PYD domains‑containing protein 3 (NLRP3) 3' untranslated region by detecting of dual luciferase reporter vector. Additionally, the expression of NLRP3, interleukin (IL)‑1β and IL‑18 significantly increased in the synovial membrane of KOA rats. A total of 24 different miRs were determined by comparing the miRNAomics in the synovial membrane of the KOA model rats. Furthermore, the miR‑233‑regulated NLRP3 inflammasome was implicated in synovial membrane injury, which may be an important mechanism of KOA pathogenesis.

The role of lncRNA XIST/miR-211 axis in modulating the proliferation and apoptosis of osteoarthritis chondrocytes through CXCR4 and MAPK signaling

Long noncoding RNAs (lncRNAs) participate in multiple diverse diseases, including osteoarthritis (OA). Here, we explored the role of lncRNA XIST in OA and identified the potential molecular mechanisms. The expression of XIST in cartilage samples in patients with OA was significantly upregulated. XIST knockdown remarkably suppressed IL-1β-suppressed OA chondrocyte proliferation while promoted IL-1β-induced cell apoptosis. By employing online tools, miRNAs related to CXCR4, a major contributor to chondrocyte apoptosis, and XIST were selected. miR-211 expression could be significantly inhibited by IL-1β stimulation, and miR-211 negatively regulated XIST expression and CXCR4 protein levels. Through direct binding, XIST served as a ceRNA for miR-211 to counteract miR-211-mediated CXCR4 repression, thereby modulating chondrocyte proliferation and apoptosis through downstream MAPK signaling. In OA tissues, miR-211 expression was significantly downregulated while CXCR4 mRNA expression was upregulated. miR-211 was negatively correlated with XIST and CXCR4, respectively, while XIST and CXCR4 was positively correlated in tissue samples. In conclusion, the study revealed that lncRNA XIST can promote the proliferation of OA chondrocytes and promote apoptosis through the miR-211/CXCR4 axis. Thus, lncRNA XIST might be considered as a potential therapeutic target for OA treatment.

Osteoarthritis year in review 2017: genetics and epigenetics

OBJECTIVE

The purpose of this review is to describe highlights from original research publications related to osteoarthritis (OA), epigenetics and genomics with the intention of recognising significant advances.

DESIGN

To identify relevant papers a Pubmed literature search was conducted for articles published between April 2016 and April 2017 using the search terms 'osteoarthritis' together with 'genetics', 'genomics', 'epigenetics', 'microRNA', 'lncRNA', 'DNA methylation' and 'histone modification'.

RESULTS

The search term OA generated almost 4000 references. Publications using the combination of descriptors OA and genetics provided the most references (82 references). However this was reduced compared to the same period in the previous year; 8.1-2.1% (expressed as a percentage of the total publications combining the terms OA and genetics). Publications combining the terms OA with genomics (29 references), epigenetics (16 references), long non-coding RNA (lncRNA) (11 references; including the identification of novel lncRNAs in OA), DNA methylation (21 references), histone modification (3 references) and microRNA (miR) (79 references) were reviewed. Potential OA therapeutics such as histone deacetylase (HDAC) inhibitors have been identified. A number of non-coding RNAs may also provide targets for future treatments.

CONCLUSION

There continues to be a year on year increase in publications researching miRs in OA (expressed as a percentage of the total publications), with a doubling over the last 4 years. An overview on the last year's progress within the fields of epigenetics and genomics with respect to OA will be given.