Aberrant expression of microRNAs in T cells from patients with ankylosing spondylitis contributes to the immunopathogenesis

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.

Expression levels of the microRNA maturing microprocessor complex components; Drosha, Dicer, and DGCR8 in PBMCs from ankylosing spondylitis patients

Objective/Aim:

Two major enzymes in the microRNA maturation process, Dicer and Drosha, as well as DGCR8, the assistant of Drosha, function in the microprocessor complex. In this survey, the mRNA expression profiles of Drosha, Dicer, and DGCR8 in peripheral blood mononuclear cells (PBMCs) from ankylosing spondylitis (AS) patients and healthy controls were measured

Methods:

Forty patients with AS and 40 age and gender matched healthy individuals were included in the study. PBMCs were separated, total RNA content of the cells was isolated, and first strand cDNA was synthesized. Quantitative analysis was performed through real-time PCR using the SYBR Green gene expression master mix.

Results:

AS cases expressed the Drosha mRNA almost equal to that of healthy controls (Fold Change= −0.94; P= 0.200). However, both Dicer and DGCR8 mRNA expressions were downregulated in patients relative to healthy subjects (Fold Change= −0.54 and −0.60; P= 0.002 and 0.004, respectively).

Conclusion:

Our results suggest that downregulation of miRNA maturation components, namely Dicer and DGCR8 may be contributing in the pathogenesis procedure of AS.

Ankylosing spondylitis: beyond genome-wide association studies

PURPOSE OF REVIEW

This article discusses genomic investigations in ankylosing spondylitis (AS) beyond genome-wide association (GWA) studies, but prior to this, genetic variants achieving genome-wide significance will be summarized highlighting key pathways contributing to disease pathogenesis.

RECENT FINDINGS

Evidence suggests that disease pathogenesis is attributed to a complex interplay of genetic, environmental and immunological factors. GWA studies have greatly enhanced our understanding of AS pathogenesis by illuminating distinct immunomodulatory pathways affecting innate and acquired immunity, most notably the interleukin-23/interleukin-17 pathway. However, despite the wealth of new information gleaned from such studies, a fraction of the heritability (24.4%) has been explained. This review will focus on investigations beyond GWA studies including copy number variants, gene expression profiling, including microRNA (miRNA), epigenetics, rare variants and gene-gene interactions.

SUMMARY

To address the 'missing heritability' and advance beyond GWA studies, a concerted effort involving rethinking of study design and implementation of newer technologies will be required. The coming of age of next-generation sequencing and advancements in epigenetic and miRNA technologies, combined with familial-focused investigations using well-characterized cohorts, is likely to reveal some of the hidden genomic mysteries associated with AS.

Epigenetic Modulation as a Therapeutic Prospect for Treatment of Autoimmune Rheumatic Diseases

Systemic inflammatory rheumatic diseases are considered as autoimmune diseases, meaning that the balance between recognition of pathogens and avoidance of self-attack is impaired and the immune system attacks and destroys its own healthy tissue. Treatment with conventional Disease Modifying Antirheumatic Drugs (DMARDs) and/or Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) is often associated with various adverse reactions due to unspecific and toxic properties of those drugs. Although biologic drugs have largely improved the outcome in many patients, such drugs still pose significant problems and fail to provide a solution to all patients. Therefore, development of more effective treatments and improvements in early diagnosis of rheumatic diseases are badly needed in order to increase patient's functioning and quality of life. The reversible nature of epigenetic mechanisms offers a new class of drugs that modulate the immune system and inflammation. In fact, epigenetic drugs are already in use in some types of cancer or cardiovascular diseases. Therefore, epigenetic-based therapeutics that control autoimmunity and chronic inflammatory process have broad implications for the pathogenesis, diagnosis, and management of rheumatic diseases. This review summarises the latest information about potential therapeutic application of epigenetic modification in targeting immune abnormalities and inflammation of rheumatic diseases.

New insights toward the pathogenesis of ankylosing spondylitis; genetic variations and epigenetic modifications

Ankylosing spondylitis (AS) is a chronic inflammatory autoimmune disease, characterized by typically an axial arthritis. AS is the prototype of a group of disorders called spondyloarthropathies, which is believed to have common clinical manifestations and genetic predisposition. To date, the exact etiology of AS remains unclear. Over the past few years, however, the role of genetic susceptibility and epigenetic modifications caused through environmental factors have been extensively surveyed with respect to the pathogenesis of AS, resulted in important advances. This review article focuses on the recent advances in the field of AS research, including HLA and non-HLA susceptibility genes identified in genome-wide association studies (GWAS), and aberrant epigenetic modifications of gene loci associated with AS. HLA genes most significantly linked with AS susceptibility include HLA-B27 and its subtypes. Numerous non-HLA genes such as those in ubiquitination, aminopeptidases and MHC class I presentation molecules like ERAP-1 were also reported. Moreover, epigenetic modifications occurred in AS has been summarized. Taken together, the findings presented in this review attempt to explain the circumstance by which both genetic variations and epigenetic modifications are involved in triggering and development of AS. Nonetheless, several unanswered dark sides continue to clog our exhaustive understanding of AS. Future researches in the field of epigenetics should be carried out to extend our vision of AS etiopathogenesis.

Identification of Serum miR-146a and miR-155 as Novel Noninvasive Complementary Biomarkers for Ankylosing Spondylitis

STUDY DESIGN

Prospective serum microRNAs study.

OBJECTIVE

To investigate differentially expressed serum microRNAs (miRNAs) between ankylosing spondylitis (AS) patients and controls, and to evaluate the potential of miRNAs as biomarkers for AS.

SUMMARY OF BACKGROUND DATA

There is an urgent need to explore novel biomarkers with more high sensitivity and specificity for the diagnosis of AS, especially for early-stage AS. Recently, the discovery of miRNAs has paved a new avenue for the diagnosis of cancers and other diseases, However, the global serum miRNAs pattern in AS patients has never been determined.

METHODS

An initial screening of miRNA expression by Solexa sequencing was performed using serum samples pooled from 10 AS patients and 10 controls, respectively. Subsequently, differential expression was validated using hydrolysis probe-based stem-loop quantitative reverse transcription polymerase chain reaction (qRT-PCR). Furthermore, AS patients were divided into group A (kyphosis <70°) and group B (kyphosis ≥70°). Disease activity and functional status were evaluated by Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and the Bath Ankylosing Spondylitis Functional Index (BASFI), respectively. The areas under the receiver-operating characteristic (ROC) curves of identified miRNAs were analyzed.

RESULTS

Nineteen serum miRNAs were differentially expressed in AS patients compared with controls. After qRT-PCR confirmation, miR-146a and miR-155 were significantly upregulated in AS patients. The areas under the ROC curves using miR-146a and miR-155 were 0.917 and 0.964, respectively. Importantly, the miR-155 expression level in group B was significantly higher than that in group A. In addition, significant correlation was observed between miR-155 expression level and BASDAI (r = 0.5, P < 0.01).

CONCLUSION

Detection of serum miRNAs (miR-146a and miR-155) may serve as novel complementary biomarkers for AS. Moreover, the expression level of miR-155 is suggested to be associated with disease activity and the severity of thoracolumbar kyphosis secondary to AS.

LEVEL OF EVIDENCE

NA.

Identification of TLR2 and TLR4‑induced microRNAs in human mesenchymal stem cells and their possible roles in regulating TLR signals

Toll-like receptors (TLRs) are expressed in human bone marrow-derived mesenchymal stromal cells (BM-MSCs), and the activation of TLRs is important in proliferation, differentiation, migration and hematopoiesis-supporting functions of BM-MSCs. However, the molecular mechanisms underlying these processes remain to be elucidated. MicroRNAs (miRNAs) are involved in various biological functions by mediating mRNA degradation or inhibiting translation of target genes. The present study aimed to identify whether TLRs regulate the expression of miRNAs in BM-MSCs and elucidate the regulatory roles of miRNAs. Illumina high-throughput sequencing was used to profile miRNAs expressed in BM-MSCs stimulated with TLR2 agonist, PAM₃CSK4 (PM) or TLR4 agonist, lipopolysaccharides (LPS). A marked expression change upon PM or LPS treatment was observed for 164 known miRNAs and six novel miRNAs that were identified. The expression of six novel miRNAs and 40 randomly selected known miRNAs was further validated by reverse transcription-quantitative polymerase chain reaction. In addition, bioinformatic methods were used to predict the potential target genes of the abundant known miRNAs. The gene ontology analysis demonstrated that predicted targets were enriched in the regulation of signal transduction, cellular processes and macromolecule metabolic processes. Kyoto Encyclopedia of Genes and Genomes pathway analysis suggested that these potential targets were involved in numerous important pathways, predominantly including mitogen-activated protein kinase, phosphati-dylinositol-4,5-bisphosphate 3-kinase-Akt, neurotrophin and cancer-associated signaling pathways. The present study aimed to identify the global expression change of miRNAs in BM-MSCs stimulated with LPS and PM, providing the opportunity to further elucidate the roles of miRNAs in mediating TLR signals to regulate the functions of BM-MSCs.

The Role of MicroRNAS in Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a common and genetically heterozygous inflammatory rheumatic disease characterized by new bone formation, ankylosis and inflammation of hip, sacroiliac joints and spine. Until now, there is no method for early diagnosis of AS and the effective treatment available for AS patients remain largely undefined.We searched articles indexed in PubMed (MEDLINE) database using Medical Subject Heading (MeSH) or Title/Abstract words ("microRNA" and "ankylosing spondylitis") from inception up to November 2015.Genetic polymorphisms of miRNAs and their targets might alter the risk of AS development whereas certain miRNAs exhibit correlation with inflammatory index.Let-7i and miR-124 were upregulated whereas miR-130a was downregulated in circulating immune cells of AS patients. These deregulated miRNAs could modulate key immune cell functions, such as cytokine response and T-cell survival.miRNA deregulation is key to AS pathogenesis. However, clinical utilization of miRNAs for management of AS patients requires further support from future translational studies.

An ankylosing spondylitis-associated genetic variant in the IL23R-IL12RB2 intergenic region modulates enhancer activity and is associated with increased Th1-cell differentiation

Objectives

To explore the functional basis for the association between ankylosing spondylitis (AS) and single-nucleotide polymorphisms (SNPs) in the IL23R-IL12RB2 intergenic region.

Methods

We performed conditional analysis on genetic association data and used epigenetic data on chromatin remodelling and transcription factor (TF) binding to identify the primary AS-associated IL23R-IL12RB2 intergenic SNP. Functional effects were tested in luciferase reporter assays in HEK293T cells and allele-specific TF binding was investigated by electrophoretic mobility gel shift assays. IL23R and IL12RB2 mRNA levels in CD4+ T cells were compared between cases homozygous for the AS-risk ‘A’ allele and the protective ‘G’ allele. The proportions of interleukin (IL)-17A+ and interferon (IFN)-γ+ CD4+ T-cells were measured by fluorescence-activated cell sorting and compared between these AS-risk and protective genotypes.

Results

Conditional analysis identified rs11209032 as the probable causal SNP within a 1.14 kb putative enhancer between IL23R and IL12RB2. Reduced luciferase activity was seen for the risk allele (p<0.001) and reduced H3K4me1 methylation observed in CD4+ T-cells from ‘A/A’ homozygotes (p=0.02). The binding of nuclear extract to the risk allele was decreased ∼3.5-fold compared with the protective allele (p<0.001). The proportion of IFN-γ+ CD4+ T-cells was increased in ‘A/A’ homozygotes (p=0.004), but neither IL23R nor IL12RB2 mRNA was affected.

Conclusions

The rs11209032 SNP downstream of IL23R forms part of an enhancer, allelic variation of which may influence Th1-cell numbers. Homozygosity for the risk ‘A’ allele is associated with more IFN-γ-secreting (Th1) cells. Further work is necessary to explain the mechanisms for these important observations.

Activation of mTOR (mechanistic target of rapamycin) in rheumatic diseases

Mechanistic target of rapamycin (mTOR, also known as mammalian target of rapamycin) is a ubiquitous serine/threonine kinase that regulates cell growth, proliferation and survival. These effects are cell-type-specific, and are elicited in response to stimulation by growth factors, hormones and cytokines, as well as to internal and external metabolic cues. Rapamycin was initially developed as an inhibitor of T-cell proliferation and allograft rejection in the organ transplant setting. Subsequently, its molecular target (mTOR) was identified as a component of two interacting complexes, mTORC1 and mTORC2, that regulate T-cell lineage specification and macrophage differentiation. mTORC1 drives the proinflammatory expansion of T helper (TH) type 1, TH17, and CD4(-)CD8(-) (double-negative, DN) T cells. Both mTORC1 and mTORC2 inhibit the development of CD4(+)CD25(+)FoxP3(+) T regulatory (TREG) cells and, indirectly, mTORC2 favours the expansion of T follicular helper (TFH) cells which, similarly to DN T cells, promote B-cell activation and autoantibody production. In contrast to this proinflammatory effect of mTORC2, mTORC1 favours, to some extent, an anti-inflammatory macrophage polarization that is protective against infections and tissue inflammation. Outside the immune system, mTORC1 controls fibroblast proliferation and chondrocyte survival, with implications for tissue fibrosis and osteoarthritis, respectively. Rapamycin (which primarily inhibits mTORC1), ATP-competitive, dual mTORC1/mTORC2 inhibitors and upstream regulators of the mTOR pathway are being developed to treat autoimmune, hyperproliferative and degenerative diseases. In this regard, mTOR blockade promises to increase life expectancy through treatment and prevention of rheumatic diseases.

Micro-Ribonucleic Acid Profiles From Microarray in Ankylosing Spondylitis

Objectives

This study aims to detect candidate micro-ribonucleic acids (miRNAs) from microarray within peripheral blood mononuclear cells and synovial fluid mononuclear cells in patients with ankylosing spondylitis (AS).

Patients and methods

Samples from three AS patients (3 males, mean age 37.3±2.5 years; range 35 to 40 years) and three healthy controls (3 males, mean age 39.0±2.6 years; range 37 to 42 years) were obtained for miRNA microarray. The microarray experiment proceeded only when the quality of total RNAs were considered to have "passed", and their integrity was good by total RNA quality control using Agilent Bioanalyzer 2100. Hierarchical clustering was performed to understand the impact of the storage condition on the miRNA expression profiles. MiScript primer assays were used for semiquantitative determination of the expression of human miRNAs to validate results from miRNA microarray.

Results

A total of 887 miRNAs were screened by microarray among groups. After normalization of the raw data, we noted that the expression of five miRNAs was significantly lower (fold change ≤0.5 and p≤0.05) and only hsa-miR-424-5p was significantly higher in AS peripheral blood mononuclear cell (fold change ≥2 and p≤0.05). In AS synovial fluid mononuclear cells, we identified that expressions of 16 miRNAs were significantly down regulated whereas only hsa-miR-424-5p was significantly upregulated (fold change ≥2 and p≤0.05). All above-mentioned miRNAs were reevaluated for further validation. Finally, significantly increased hsa-miR-424-5p and decreased hsa-miR-377 were found in synovial fluid mononuclear cells from AS patients compared with healthy controls. Based on target prediction programs and published papers, potential target genes and its pathways were screened.

Conclusion

miR-424-5p was increased and miR-377 was decreased in synovial fluid mononuclear cells from patients with AS. These two miRs might have functional roles in patients with arthritis via different pathways.

Role of histone deacetylase 3 in ankylosing spondylitis via negative feedback loop with microRNA-130a and enhancement of tumor necrosis factor-1α expression in peripheral blood mononuclear cells

The present study was performed to investigate the molecular mechanism of ankylosing spondylitis (AS). The interaction between micro (mi)RNA‑130a and its target tumor necrosis factor (TNF)‑1α and histone deactylase (HDAC)3 was assessed in peripheral blood mononuclear cells (PBMCs) from AS patients. Increased HDAC3 and decreased miRNA‑130a levels were observed in PBMCs from AS patients. HDAC3 knockdown or HDAC3 inhibition promoted the expression of miRNA‑130a, and HDAC3 was recruited to the promoter region of the gene encoding miRNA‑130a in PBMCs. In addition, miR‑130a overexpression led to a decrease, whereas miR‑130a inhibition led to an increase of TNF‑1α expression in PBMCs. Furthermore, HDAC3 knockdown or HDAC3 inhibition was associated with simultaneous upregulation of the expression of miR‑130a and downregulation of the expression of TNF‑1α in PBMCs. These results indicated that HDAC3 was involved in the regulation of the underlying molecular mechanism of AS by forming a negative feedback loop with miR-130a and enhancement of TNF-1α expression.

MicroRNA-124 involves in ankylosing spondylitis by targeting ANTXR2

OBJECTIVES

A recent genome-wide association study or GWAS identified that anthrax roxin receptor 2 (ANTXR2) was one of the risk loci for ankylosing spondylitis (AS). Previous study also showed that ANTXR2 could potentially affect new bone formation. This study aimed to investigate the possible mechanisms of ANTXR2 involved in AS pathogenesis.

METHODS

The expression level of ANTXR2 and miR-124 in peripheral blood was detected by quantitative real-time polymerase chain reaction or qRT-PCR. ANTXR2 was predicted to be a target gene of miR-124 by TargetScan, which was confirmed by luciferase reporter assays. Western blot analysis was used to further investigate the effect of miR-124 on c-Jun N-terminal kinase (JNK) activation and evaluate the activated status of autophagy.

RESULTS

We evidenced that ANTXR2 was downregulated and miR-124 was upregulated in peripheral blood from AS patients. Intriguingly, miR-124 targeted ANTXR2 and overexpression of miR-124 in Jurkat cells notably inhibited ANTXR2 expression. ANTXR2 inhibition by miR-124 promoted JNK activation and induced autophagy.

CONCLUSIONS

Our results suggested that miR-124 might induce autophagy to participate in AS by targeting ANTXR2, which might be implicated in pathological process of AS.

Anti-citrullinated protein antibodies suppress let-7a expression in monocytes from patients with rheumatoid arthritis and facilitate the inflammatory responses in rheumatoid arthritis

We hypothesized that anti-citrullinated protein antibodies (ACPAs) could affect the expression of miRNAs in monocytes and contribute to the inflammatory responses in rheumatoid arthritis (RA). The expression profiles of 270 human miRNAs, co-cultured with ACPAs or human immunoglobulin G (IgG), were analyzed using real-time polymerase chain reaction. Ten miRNAs exhibited differential expression in U937 cells after co-cultured with ACPAs compared with human IgG. The expression levels of these miRNAs were investigated in monocytes from 21 ACPA-positive RA patients and 13 controls. Among these miRNAs, the expression levels of let-7a was decreased in monocytes from ACPA-positive RA patients. The expression levels of let-7a showed a negative correlation with positivity of rheumatoid factor in patients sampled. We found that transfection of U937 cells with let-7a mimic suppressed K-Ras protein expression. In the ACPA-mediated signaling pathway, transfection of U937 cells with let-7a mimic suppressed the ACPA-enhanced phosphorylation of c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase 1/2 (ERK1/2), and the expression and secretion of interleukin (IL)-1β. In conclusion, ACPA-mediated decreased let-7a expression in monocytes from ACPA-positive RA patients. Decreased let-7a expression was associated with the positivity of RF in ACPA-positive RA patients. The decreased expression of let-7a could facilitate the inflammatory pathway via enhanced ACPA-mediated phosphorylation of ERK1/2 and JNK and increased expression of IL-1β through an increase in the expression of Ras proteins.

miR-573 is a negative regulator in the pathogenesis of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by abnormal inflammation, angiogenesis, and cartilage destruction. Our previous study demonstrated an increased expression of thioredoxin domain containing 5 (TXNDC5) in the synovial tissues of RA, and its overexpression was implicated in RA pathology. Although TXNDC5 variation is linked to genetic susceptibility to RA, the regulation of its abnormal expression has not been well defined. Here, we show that TXNDC5 is directly targeted by microRNA (miR)-573, and TXNDC5, in turn, mediates the suppressive effect of miR-573 on the invasion of synovial fibroblasts of RA (RASFs). miR-573 overexpression suppressed the expression of interleukin 6 (IL-6) and cyclooxygenase 2 in RASFs, as well as the production of tumor necrosis factor-alpha and interleukin-1 beta by activated THP-1 cells in response to lipopolysaccharide (LPS) stimulation. Moreover, treatment with conditioned medium of RASFs transfected with miR-573 mimic inhibited the angiogenic ability of human umbilical vein endothelial cells (HUVECs). Of note, epidermal growth factor receptor and Toll-like receptor 2 were validated as new direct targets of miR-573, and mediate the regulation of miR-573 on IL-6 production as well as the angiogenesis of HUVECs. In addition, exogenous miR-573 expression suppressed the activation of mitogen-activated protein kinase (MAPK), signal transducer and activator of transcription 3, and phosphatidylinositol-3 kinase/activate protein kinase B in RASFs in response to LPS. Indeed, MAPK signaling was essential to ensure the function of miR-573. Taken together, our study points toward the protective roles of miR-573 in the pathological process of RA and suggests a potential target in the treatment of RA.

Association Study of IL-12B Polymorphisms Susceptibility with Ankylosing Spondylitis in Mainland Han Population

OBJECTIVE

This study aims to determine whether the genetic polymorphisms of IL-12B gene is a susceptibility factor to Ankylosing spondylitis (AS) in mainland Han Chinese population.

METHOD

Eight single-nucleotide polymorphisms (SNPs) (rs10045431, rs11167764, rs3212227, rs6556412, rs6556416, rs6871626, rs6887695 and rs7709212) in the IL-12B gene were genotyped by iMLDR Assay technology in 400 patients [96% (384/400) HLA-B27(+)] and 395 geographically and ethnically matched healthy controls in mainland Han Chinese population. The correlation between IL-12B genetic polymorphisms and AS activity index (BASDAI, BASFI) were tested.

RESULTS

The significant difference was found in genotype distribution between AS and healthy controls (χ2 = 6.942, P-value = 0.031) of the SNP rs6871626. Furthermore, significant evidence was also detected under the recessive model for minor allele A. The AA genotype carrier had 1.830 fold risk compared with C allele carrier (with CC and AC genotypes) [OR (95% CI) = 1.830 (1.131-2.961), P-value = 0.014]. Nevertheless, the difference was no longer significant after Bonferroni correction. Subset analysis on cases with HLA-B27(+) did find the same results. Three genotypic groups (AA, CC and CA) in rs6871626 site was highly associated with the BASDAI and BASFI (P-value = 0.012 and P-value = 0.023, respectively), after adjustment for effect of age, sex, and disease duration, the P-value was 0.031 and 0.041, respectively. The AA genotype of rs6871626 was also significantly correlated with an increased BASDAI and BASFI compared to the AC and CC genotypes in AS patients.

CONCLUSION

Our findings suggest that rs6871626 may be associated AS susceptibility and with disease activity (BASDAI, BASFI) in mainland Han Chinese population.

Let-7i inhibits the malignant phenotype of osteosarcoma cells by targeting Aurora-B

Our previous study indicated that Aurora-B is involved in osteosarcoma (OS) cell invasion and metastasis; however, the mechanism underlying Aurora-B overexpression in OS remains unknown. In the present study, significantly downregulated let-7i expression in OS tissues and OS cells was observed compared with that in normal adjacent tumorous tissues and human osteoblast cell lines. Bioinformatic predictions have revealed a conserved binding site in a microRNA locus on Aurora‑B, suggesting the potential of let‑7i targeting the Aurora‑B gene. To validate this, a luciferase reporter assay was performed on OS cells. The results indicated that Aurora‑B is a likely to be a direct target negatively regulated by let‑7i. The expression of let‑7i in OS cells was restored by infection with let‑7i mimics. Results revealed that Aurora‑B mRNA and protein expression levels were significantly decreased. Furthermore, the proliferation, migration and invasion abilities of OS cells were significantly suppressed by infection with let‑7i mimics. Notably, the inhibitory effect of silencing Aurora‑B by LV‑shAurora‑B on cell proliferation, migratory and invasive ability was significantly lower than that by let‑7i mimics, which indicated that let‑7i inhibits cell malignant phenotypes partially by targeting Aurora‑B in OS cells. All data suggested that let‑7i may be a novel potential target for OS treatment.

Epigenetics of osteoarticular diseases: recent developments

A variety of osteoarticular conditions possess an underlying genetic aetiology. Large-scale genome-wide association studies have identified several genetic loci associated with osteoarticular conditions, but were unable to fully account for their estimated heritability. Epigenetic modifications including DNA methylation, histone modification, nucleosome positioning, and microRNA expression may help account for this incomplete heritability. This articles reviews insights from epigenetic studies in osteoarticular diseases, focusing on osteoarthritis, but also examines recent advances in rheumatoid arthritis, osteoporosis, systemic lupus erythematosus (SLE), ankylosing spondylitis, and sarcoma. Genome-wide methylation studies are permitting identification of novel candidate genes and molecular pathways, and the pathogenic mechanisms with altered methylation status are beginning to be elucidated. These findings are gradually translating into improved understanding of disease pathogenesis and clinical applications. Functional studies in osteoarthritis, rheumatoid arthritis, and SLE are now identifying downstream molecular alterations that may confer disease susceptibility. Epigenetic markers are being validated as prognostic and therapeutic disease biomarkers in sarcoma, and clinical trials of hypomethylating agents as treatments for sarcoma are being conducted. In concert with advances in throughput and cost-efficiency of available technologies, future epigenetic research will enable greater characterisation and treatment for both common and rare osteoarticular diseases.

Increased HDAC3 and decreased miRNA-130a expression in PBMCs through recruitment HDAC3 in patients with spinal cord injuries

The study was performed to investigate the molecular mechanism for SCI patients. The interaction between miRNA-130a and HDAC was demonstrated in PBMCs from SCI patients. Increased HDAC3 and decreased miRNA-130a were observed in PBMCs from AS patients. Next, HDAC3 loss-of-function or HAAC3 inhibition promoted the expression of miRNA-130a, and HDAC3 could be recruited to the promoter region of the gene, miRNA-130a, in PBMCs. In addition, linear regression analysis indicated that mRNA expression results were highly negative correlated between HDAC3 and miRNA-130a in PBMCs from SCI patients. Furthermore, miRNA-130a down expression increased the expression of HDAC3 in PBMCs. Loss-of-function of miRNA-130a promoted PBMCs apoptosis, but HDAC3 loss-of-function had no significant effect on the apoptotic cell. In addition, miR-130a overexpression decreased, whereas miR-130a inhibition increased, the expression of TNF-α in PBMCs. Furthermore, HDAC3 loss-of-function or HAAC3 inhibition associated with simultaneous up-regulation the expression of miR-130a and down-regulation the expression of TNF-α in PBMCs. In conclusion, HDAC3 regulated a distinct underlying molecular and pathogenic mechanism of SCI by forming a negative feedback loop with miR-130a and enhanced TNF-1α expression.

MicroRNA let-7i induced autophagy to protect T cell from apoptosis by targeting IGF1R

MicroRNA let-7i is up-regulated in T cells from patients with Ankylosing Spondylitis (AS). In this study, we investigated the role of let-7i in T cells survival. Our results demonstrated down-regulation of insulin-like growth factor-1 receptor (IGF1R) in T cells from patients with AS. Luciferase reporter assay suggested IGF1R as direct target of let-7i. Overexpression of let-7i in Jurkat cells significantly suppressed IGF1R expression, which mimicked the action of IGF1R siRNA. IGF1R inhibition led to a strinking decrease in phosphorylation of mTOR and Akt, down-regulation of Bcl-2, up-regulation of Bax and cleavage of caspase 3 and PARP. Meanwhile, IGF1R inhibition induced autophagy. Autophagy induced by let-7i overexpression contributed to protect cells from apoptosis. Our data indicated that let-7i might control T cells fates in AS by targeting IGF1R.

Increased miR-223 expression in T cells from patients with rheumatoid arthritis leads to decreased insulin-like growth factor-1-mediated interleukin-10 production

We hypothesized that the aberrant expression of microRNAs (miRNAs) in rheumatoid arthritis (RA) T cells was involved in the pathogenesis of RA. The expression profile of 270 human miRNAs in T cells from the first five RA patients and five controls were analysed by real-time polymerase chain reaction. Twelve miRNAs exhibited potentially aberrant expression in RA T cells compared to normal T cells. After validation with another 22 RA patients and 19 controls, miR-223 and miR-34b were over-expressed in RA T cells. The expression levels of miR-223 were correlated positively with the titre of rheumatoid factor (RF) in RA patients. Transfection of Jurkat cells with miR-223 mimic suppressed insulin-like growth factor-1 receptor (IGF-1R) and transfection with miR-34b mimic suppressed cAMP response element binding protein (CREB) protein expression by Western blotting. The protein expression of IGF-1R but not CREB was decreased in RA T cells. The addition of recombinant IGF-1-stimulated interleukin (IL)-10 production by activated normal T cells, but not RA T cells. The transfection of miR-223 mimic impaired IGF-1-mediated IL-10 production in activated normal T cells. The expression levels of SCD5, targeted by miR-34b, were decreased in RA T cells after microarray analysis. In conclusion, both miR-223 and miR-34b were over-expressed in RA T cells, but only the miR-223 expression levels were correlated positively with RF titre in RA patients. Functionally, the increased miR-223 expression could impair the IGF-1-mediated IL-10 production in activated RA T cells in vivo, which might contribute to the imbalance between proinflammatory and anti-inflammatory cytokines.