Differential Expression Profiles of Long Noncoding RNA and mRNA of Osteogenically Differentiated Mesenchymal Stem Cells in Ankylosing Spondylitis

A review of long non-coding RNAs in ankylosing spondylitis: pathogenesis, clinical assessment, and therapeutic targets

Ankylosing spondylitis (AS) is a chronic immune-mediated type of inflammatory arthritis characterized by inflammation, bone erosion, and stiffness of the spine and sacroiliac joints. Despite great efforts put into the investigation of the disease, the pathogenesis of AS remains unclear, posing challenges in identifying ideal targets for diagnosis and treatment. To enhance our understanding of AS, an increasing number of studies have been conducted. Some of these studies reveal that long non-coding RNAs (lncRNAs) play crucial roles in the etiology of AS. Some certain lncRNAs influence the development of AS by regulating inflammatory responses, autophagy, apoptosis, and adipogenesis, as well as the proliferation and differentiation of cells. Additionally, some lncRNAs demonstrate potential as biomarkers, aiding in monitoring disease progression and predicting prognosis. In this review, we summarize recent studies concerning lncRNAs in AS to elucidate the underlying mechanisms in which lncRNAs are involved and their potential values as biomarkers for disease assessment and druggable targets for therapy.

Unveiling Mesenchymal Stem Cells' Regenerative Potential in Clinical Applications: Insights in miRNA and lncRNA Implications

It is now widely recognized that mesenchymal stem cells (MSCs) possess the capacity to differentiate into a wide array of cell types. Numerous studies have identified the role of lncRNA in the regulation of MSC differentiation. It is important to elucidate the role and interplay of microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) in the regulation of signalling pathways that govern MSC function. Furthermore, miRNAs and lncRNAs are important clinical for innovative strategies aimed at addressing a wide spectrum of existing and emerging disease. Hence it is important to consider their impact on MSC function and differentiation. Examining the data available in public databases, we have collected the literature containing the latest discoveries pertaining to human stem cells and their potential in both fundamental research and clinical applications. Furthermore, we have compiled completed clinical studies that revolve around the application of MSCs, shedding light on the opportunities presented by harnessing the regulatory potential of miRNAs and lncRNAs. This exploration of the therapeutic possibilities offered by miRNAs and lncRNAs within MSCs unveils exciting prospects for the development of precision therapies and personalized treatment approaches. Ultimately, these advancements promise to augment the efficacy of regenerative strategies and produce positive outcomes for patients. As research in this field continues to evolve, it is imperative to explore and exploit the vast potential of miRNAs and lncRNAs as therapeutic agents. The findings provide a solid basis for ongoing investigations, fuelling the quest to fully unlock the regenerative potential of MSCs.

The bone marrow side of axial spondyloarthritis

Spondyloarthritis (SpA) is characterized by the infiltration of innate and adaptive immune cells into entheses and bone marrow. Molecular, cellular and imaging evidence demonstrates the presence of bone marrow inflammation, a hallmark of SpA. In the spine and the peripheral joints, bone marrow is critically involved in the pathogenesis of SpA. Evidence suggests that bone marrow inflammation is associated with enthesitis and that there are roles for mechano-inflammation and intestinal inflammation in bone marrow involvement in SpA. Specific cell types (including mesenchymal stem cells, innate lymphoid cells and γδ T cells) and mediators (Toll-like receptors and cytokines such as TNF, IL-17A, IL-22, IL-23, GM-CSF and TGFβ) are involved in these processes. Using this evidence to demonstrate a bone marrow rather than an entheseal origin for SpA could change our understanding of the disease pathogenesis and the relevant therapeutic approach.

Assessment of Circulating lncRNA H19 in Ankylosing Spondylitis Patients and Its Correlation with Disease Activity

Ankylosing spondylitis (AS) is a chronic inflammatory disease that results in severe pain and stiffness in the joints. The causes and pathophysiology of AS are still largely unknown. The lncRNA H19 plays key roles in the pathogenesis of AS by mediating inflammatory progression by acting in the axis of IL-17A/IL-23. The aims of this study were determining the role of lncRNA H19 in AS and assessing its clinical correlation. A case-control study was conducted and qRT-PCR was utilized to measure H19 expression. Comparing AS cases to healthy controls, it was found that H19 expression was significantly upregulated. For AS prediction, H19 demonstrated a 81.1% sensitivity, 100% specificity, and 90.6% diagnostic accuracy at a lncRNA H19 expression value of 1.41. lncRNA H19 had a significantly positive correlation with AS activity, MRI results, and inflammatory markers. lncRNA H19 seemed to be an independent predictor of AS (adjusted OR of 211 (95% CI: 4.7-939; p = 0.025)). After 3 months of clinical follow-up, seventeen patients (32.1%) showed minimal clinical improvement and fifteen patients (28.3%) showed major improvement. AS activity scores were significantly decreased in patients with high H19 expression. A significantly elevated lncRNA H19 expression was observed in AS cases compared with that in healthy controls. These results suggest that upregulation of lncRNA H19 expression may be involved in the pathogenesis of AS. The expression of the lncRNA H19 is related to the duration and activity of the disease. LncRNA H19 expression seems to be an independent predictor of AS.

Comprehensive LncRNA and Potential Molecular Mechanism Analysis in Noninfectious Uveitis

Purpose

Long noncoding RNA (lncRNA) is noncoding RNA and have played a key role or be treated as a biomarker in a variety of diseases such as tumors. However, extensive lncRNA analysis for uveitis has not been explored completely. In this study, we analyzed the lncRNAs with altered expression in peripheral blood comprehensively for three major autoimmune diseases (ankylosing spondylitis [AS], Behҫet's disease [BD], and sarcoidosis) to search potential hub gene and molecular mechanism for noninfectious uveitis.

Methods

In total, we included 18 patients with AS and 12 patients with sarcoidosis versus 25 controls for GSE18781; we also included 15 patients with BD versus 14 controls for GSE17114 in this study. The lncRNA and messenger RNA (mRNA) expression levels were determined by microarray using serum samples from patients and healthy controls.

Results

Twenty-one lncRNAs and 1073 mRNAs were detected in patients with AS, 4 lncRNAs and 62 mRNAs in patients with BD, and 196 lncRNAs and 5376 mRNAs in patients with sarcoidosis. Thus, we suspected lncRNA XIST and MIAT, mRNA FCGBP, CD247, CTSW, AES, NCR3, TIGIT, CASP5, DUSP2, and TBX21 may be the most possible hub genes for AS, BD, and sarcoidosis. These RNAs were involved in the mitogen-activated protein kinase signaling pathway and inflammatory cytokine pathways.

Conclusions

In this study, comprehensive bioinformatics analysis identified lncRNAs with altered expression in three major autoimmune diseases that may combine with noninfectious uveitis. This study provides novel insights into the molecular pathogenetic mechanisms and key information toward developing new diagnostic biomarkers and special therapeutic targets for noninfectious uveitis in AS, BD, and sarcoidosis.

Translational Relevance

LncRNAs and their potential mechanisms provide new strategies for prevention and treatment for noninfectious uveitis in patients with AS, BD, and sarcoidosis.

RNA Sequencing Reveals the Expression Profiles of circRNAs and Indicates Hsa_circ_0070562 as a Pro-osteogenic Factor in Bone Marrow-Derived Mesenchymal Stem Cells of Patients With Ankylosing Spondylitis

Recent studies have reported that circular RNAs (circRNAs) play a crucial regulatory role in a variety of human diseases. However, the roles of circRNAs in pathological osteogenesis in ankylosing spondylitis (AS) remain unclear. We conducted circRNA and miRNA expression profiling of osteogenically differentiated bone marrow-derived mesenchymal stem cells (BMSCs) of patients with AS compared with those of healthy donors (HDs) by RNA sequencing (RNA-seq). Results showed that a total of 31806 circRNAs were detected in the BMSC samples, of which 418 circRNAs were significantly differentially expressed (DE) with a fold change ≥2 and p value <0.05. Among these, 204 circRNAs were upregulated, and 214 were downregulated. GO and KEGG analyses demonstrated that the DE circRNAs were mainly involved in the regulation of biological processes of the cell matrix adhesion and the TGF-beta signaling pathway, which are closely related to AS. circRNA-miRNA interaction networks related to the TGF-beta signaling pathway were established. The results of qRT-PCR showed that has_circ_0070562 was significantly up-regulated in AS-MSCs. In vitro experiments showed that silencing of has_circ_0070562 weakened osteogenesis of AS-BMSCs. In conclusion, we identified numerous circRNAs that were dysregulated in AS-BMSCs compared with HD-BMSCs. Bioinformatic analyses suggested that these dysregulated circRNAs might play important functional roles in AS-BMSCs osteogenesis. Circ_0070562 functioned as a pro-ostegenic factor and might serve as a potential biomarker and a therapeutic target for AS.

The Molecular Mechanism of Long Non-Coding RNA MALAT1-Mediated Regulation of Chondrocyte Pyroptosis in Ankylosing Spondylitis

Long non-coding RNAs (lncRNAs) may be important regulators in the progression of ankylosing spondylitis (AS). The competing endogenous RNA (ceRNA) activity of lncRNAs plays crucial roles in osteogenesis. We identified the mechanism of the differentially expressed lncRNA MALAT1 in AS using bioinformatic analysis and its ceRNA mechanism. The interaction of MALAT1, microRNA-558, and GSDMD was identified using integrated bioinformatics analysis and validated. Loss- and gain-of-function assays evaluated their effects on the viability, apoptosis, pyroptosis and inflammation of chondrocytes in AS. We found elevated MALAT1 and GSDMD but reduced miR-558 in AS cartilage tissues and chondrocytes. MALAT1 contributed to the suppression of cell viability and facilitated apoptosis and pyroptosis in AS chondrocytes. GSDMD was a potential target gene of miR-558. Depletion of MALAT1 expression elevated miR-558 by inhibiting GSDMD to enhance cell viability and inhibit inflammation, apoptosis and pyroptosis of chondrocytes in AS. In summary, our key findings demonstrated that knockdown of MALAT1 served as a potential suppressor of AS by upregulating miR-558 via the downregulation of GSDMD expression.

Emerging Roles of Long Non-Coding RNAs in Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a chronic systemic autoimmune disease characterized by inflammation, bone erosion, spur formation of the spine and the sacroiliac joints. However, the etiology and molecular pathogenesis of AS remain largely unclear. Recently, a growing number of studies showed that long non-coding RNAs (lncRNAs) played critical roles in the development and progression of autoimmune and orthopedic conditions, including AS. Studies demonstrated that a myriad of lncRNAs (e.g. H19, MEG3, LOC645166) pertinent to regulation of inflammatory signals were deregulated in AS. A number of lncRNAs might also serve as new biomarkers for the diagnosis and predicting the outcomes of AS. In this review, we summarize lncRNA profiling studies on AS and the functional roles and mechanism of key lncRNAs relevant to AS pathogenesis. We also discuss their potential values as biomarkers and druggable targets for this potentially disabling condition.

Comprehensive lncRNA and mRNA profiles in peripheral blood mononuclear cells derived from ankylosing spondylitis patients by RNA-sequencing analysis

The present study aimed to investigate the comprehensive expression profiles of long non-coding RNA (lncRNA) in ankylosing spondylitis (AS).The peripheral blood samples were collected from 6 AS patients and 6 age- and gender-matched healthy controls (HCs), and separated for peripheral blood mononuclear cells, followed by RNA-sequencing. Further bioinformatics analyses were performed to explore the significantly enriched biological processes, signaling pathways of differentially expressed lncRNAs (DElncRNAs) (based on cis-target and trans-target genes) and differentially expressed mRNAs (DEmRNAs).Principal component analysis plots indicated that both lncRNA and mRNA expression profiles could distinguish AS patients from HCs; heatmap diagram exhibited a relatively good consistency and tendency of lncRNA and mRNA expression profiles in AS patients and HCs, respectively; volcano plots exhibited 114 upregulated and 45 downregulated DElncRNAs, 284 upregulated and 435 downregulated DEmRNAs in AS patients compared with HCs; Gene ontology enrichment analyses indicated that DElncRNAs (based on cis-target and trans-target genes) and DEmRNAs were enriched in molecular functions (including DNA binding, protein binding, etc) and biological process (including immune response, inflammatory response, etc); Kyoto Encyclopedia of Genes and Genomes enrichment analyses revealed that these DElncRNAs (based on cis-target and trans-target genes) and DEmRNAs were enriched in immune and inflammation-related signaling, such as B cell receptor signaling pathway, TNF signaling pathway, NF-kappa B signaling pathway, etc.Our study displays the comprehensive expression profiles and functions of lncRNAs involved in AS, which provides reference for further researches discovering candidate lncRNAs with value in assisting early AS diagnosis.

Integrative analysis of long non-coding RNA and messenger RNA expression in toll-like receptor 4-primed mesenchymal stem cells of ankylosing spondylitis

Background

The precise pathogenesis of ankylosing spondylitis (AS) is still largely unknown at present. Our previous study found that toll-like receptor 4 (TLR4) downregulated and performed immunoregulatory dysfunction in mesenchymal stem cells from AS patients (AS-MSCs). The aim of this study was to explore the expression profiles of long non-coding RNAs (lncRNAs) and messenger RNAs (mRNAs) in TLR4-primed AS-MSCs, and to clarify the potential mechanisms.

Methods

The immunoregulatory effects of MSCs were determined after TLR4 activation. Next, the differentially-expressed (DE) lncRNAs and mRNAs between AS-MSCs and TLR4-primed AS-MSCs [stimulated by lipopolysaccharide (LPS)] were identified via high-throughput sequencing followed by quantitative real-time PCR (qRT-PCR) confirmation. Finally, bioinformatics analyses were performed to identify the critical biological functions, signaling pathways, and associated functional networks involved in the TLR4-primed immunoregulatory function of AS-MSCs.

Results

A total of 147 DE lncRNAs and 698 DE mRNAs were identified between TLR4-primed AS-MSCs and unstimulated AS-MSCs. Of these, 107 lncRNAs were upregulated and 40 were downregulated (fold change ≥2, P<0.05), while 504 mRNAs were upregulated and 194 were downregulated (fold change ≥2, P<0.05). Five lncRNAs and five mRNAs with the largest fold changes were respectively verified by qRT-PCR. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses demonstrated that the DE mRNAs and lncRNAs were highly associated with the inflammatory response, such as NOD-like receptor (NLR) signaling pathway, the TNF signaling pathway and the NF-κB signaling pathway. Cis-regulation prediction revealed eight novel lncRNAs, while trans-regulation prediction revealed 15 lncRNAs, respectively. Eight core pairs of lncRNA and target mRNA in the lncRNA-transcription factor (TF)-mRNA network were as follows: PACERR-PTGS2, LOC105378085-SOD2, LOC107986655-HIVEP2, MICB-DT-MICB, LOC105373925-SP140L, LOC107984251-IFIT5, LOC112268267-GBP2, and LOC101926887-IFIT3, respectively.

Conclusions

TLR4 activation in AS can enhance the immunoregulatory ability of MSCs. Eight core pairs of lncRNA and target mRNA were observed in TLR4-primed AS-MSCs, which could contribute to understanding the potential mechanism of AS-MSC immunoregulatory dysfunction.

SMAD-specific E3 ubiquitin ligase 2 promotes angiogenesis by facilitating PTX3 degradation in MSCs from patients with ankylosing spondylitis

Dysregulated angiogenesis of mesenchymal stem cells (MSCs) is closely related to inflammation and disrupted bone metabolism in patients with various autoimmune diseases. However, the role of MSCs in the development of abnormal angiogenesis in patients with ankylosing spondylitis (AS) remains unclear. In this study, we cultured human umbilical vein endothelial cells (HUVECs) with bone marrow-derived MSCs from patients with AS (ASMSCs) or healthy donors (HDMSCs) in vitro. Then, the cocultured HUVECs were assayed using a cell counting kit-8 (CCK-8) to evaluate the cell proliferation. A wound healing assay was performed to investigate cell migration, and a tube formation assay was conducted to determine the angiogenesis efficiency. ASMSCs exhibited increased angiogenesis, and increased expression of SMAD-specific E3 ubiquitin ligase 2 (Smurf2) in MSCs was the main cause of abnormal angiogenesis in patients with AS. Downregulation of Smurf2 in ASMSCs blocked angiogenesis, whereas overexpression of Smurf2 in HDMSCs promoted angiogenesis. The pro-angiogenic effect of Smurf2 was confirmed by the results of a Matrigel plug assay in vivo. By functioning as an E3 ubiquitin ligase in MSCs, Smurf2 regulated the levels of pentraxin 3 (PTX3), which has been shown to suppress angiogenesis through the PTX3-fibroblast growth factor 2 pathway. Moreover, Smurf2 transcription was regulated by activating transcription factor 4-induced endoplasmic reticulum stress. In conclusion, these results identify novel roles of Smurf2 in negatively regulating PTX3 stability and promoting angiogenesis in ASMSCs.

LncRNA, Important Player in Bone Development and Disease

BACKGROUND

Bone is an important tissue and its normal function requires tight coordination of transcriptional networks and signaling pathways, and many of these networks/ pathways are dysregulated in pathological conditions affecting cartilage and bones. Long non-coding RNA (lncRNA) refers to a class of RNAs with a length of more than 200 nucleotides, lack of protein-coding potential, and exhibiting a wide range of biological functions. Although studies on lcnRNAs are still in their infancy, they have emerged as critical players in bone biology and bone diseases. The functions and exact mechanism of bone-related lncRNAs have not been fully classified yet.

OBJECTIVE

The objective of this article is to summarize the current literature on lncRNAs on the basis of their role in bone biology and diseases, focusing on their emerging molecular mechanism, pathological implications and therapeutic potential.

DISCUSSION

A number of lncRNAs have been identified and shown to play important roles in multiple bone cells and bone disease. The function and mechanism of bone-related lncRNA remain to be elucidated.

CONCLUSION

At present, majority of knowledge is limited to cellular levels and less is known on how lncRNAs could potentially control the development and homeostasis of bone. In the present review, we highlight some lncRNAs in the field of bone biology and bone disease. We also delineate some lncRNAs that might have deep impacts on understanding bone diseases and providing new therapeutic strategies to treat these diseases.

Promoting effect of long non-coding RNA SNHG1 on osteogenic differentiation of fibroblastic cells from the posterior longitudinal ligament by the microRNA-320b/IFNGR1 network

Long non-coding RNAs (lncRNAs) have been noted to influence the progression of ossification of posterior longitudinal ligament (OPLL). The work aims to probe the effect of lncRNA SNHG1 on osteogenic differentiation of ligament fibroblastic cells (LFCs). Aberrantly expressed lncRNAs in ossified PLL tissues were screened out by microarray analysis. Gain- and loss-of function experiments of SNHG1 were performed to identify its role in osteogenic differentiation of LFCs. The downstream molecules of SNHG1 were explored. Altered expression of miR-320b was introduced in LFCs as well. The interactions among SNHG1, miR-320b and IFNGR1 were identified. Consequently, SNHG1 was found highly expressed in OPLL patients. Silencing of SNHG1 inhibited BMP-2, RUNX2 and OCN expression and the ALP activity and reduced osteogenic differentiation of LFCs. Importantly, SNHG1 could and upregulate IFNGR1 through serving as a sponge for miR-320b. Over-expression of miR-320b inhibited osteogenic differentiation of LFCs and inactivated the JAK/STAT signaling pathway. Further administration of Fedratinib, a JAK2-specific agonist, increased osteogenic differentiation of LFCs. To conclude, the study suggested that SNHG1 could upregulate IFNGR1 by sequestering miR-320b and activate the JAK/STAT signaling. Silencing of SNHG1 could reduce the osteogenic differentiation and mineralization of LFCs. The study may offer new insights into OPLL treatment.

Aberrantly Expressed lncRNAs and mRNAs of Osteogenically Differentiated Mesenchymal Stem Cells in Ossification of the Posterior Longitudinal Ligament

Ectopic bone formation is the chief characteristic of ossification of the posterior longitudinal ligament (OPLL). Emerging evidence has revealed that long non-coding RNAs (lncRNAs) can regulate the osteogenic differentiation of mesenchymal stem cells (MSCs), which are the main cells responsible for bone formation. However, the role of lncRNAs in the pathogenesis of OPLL remains unclear. In this study, 725 aberrantly expressed lncRNAs and 664 mRNAs in osteogenically differentiated MSCs from OPLL patients (OPLL MSCs) were identified by microarrays and confirmed by qRT-PCR assays. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed that the most enriched pathways included the p53, JAK-STAT, and PI3K-Akt signaling pathways. The co-expression network showed the interactions between the aberrantly expressed lncRNAs and mRNAs in OPLL MSCs, and the potential targets and transcription factors of the lncRNAs were predicted. Our research demonstrated the aberrantly expressed lncRNA and mRNA and the potential regulatory networks involved in the ectopic bone formation of OPLL. These findings imply that lncRNAs may play a vital role in OPLL, which provides a new perspective on the pathogenesis of OPLL.

Analysis of lncRNAs-miRNAs-mRNAs networks in periodontal ligament stem cells under mechanical force

OBJECTIVES

Our study aims to analyze the expression profiles of long non-coding RNAs (lncRNAs) and investigate the potential regulatory networks among lncRNAs, microRNAs (miRNAs), and mRNAs in periodontal ligament stem cells (PDLSCs) under mechanical force (MF).

MATERIALS AND METHODS

PDLSCs were isolated from human periodontal ligament tissues and identified by flow cytometry analysis. Multidirectional differentiation potential of PDLSCs was obtained by osteogenic and adipogenic induction. High-throughput RNA sequencing was used to identify the expression patterns of lncRNAs and mRNAs in PDLSCs under MF. MF-responsive miRNAs were obtained from the previous microarray data. LncRNAs-miRNAs-mRNAs networks were constructed by Cytoscape.

RESULTS

PDLSCs cultured from the periodontal ligament tissues were positive for STRO-1, CD146 and negative for CD45, CD34. Alizarin red staining and Oil Red O staining showed that PDLSCs had the ability of osteogenic and adipogenic differentiation. Then, a total of 1,339 and 1,426 differentially expressed lncRNAs and mRNAs were identified, respectively, in PDLSCs under MF. Based on the previous miRNA microarray analysis, the potential interaction networks of lncRNAs-miRNAs-mRNAs were constructed. It was found that lncRNAs and mRNAs could competitively interact with the same miRNA.

CONCLUSIONS

LncRNAs-miRNAs-mRNAs networks were involved in PDLSCs under MF, which might provide a novel mechanism in the regulation of clinical orthodontic tooth movement process.

Profiling and Bioinformatics Analysis of Differentially Expressed circRNAs in Spinal Ligament Tissues of Patients with Ankylosing Spondylitis

Recent studies have reported that circular RNAs (circRNAs) play a crucial regulatory role in a variety of human diseases. However, the roles of circRNAs in ankylosing spondylitis (AS) remain unclear. In this study, we conducted circRNA expression profiling of the spinal ligament tissues of patients with AS by RNA sequencing (RNA-seq) and analyzed the potential functions of differentially expressed circRNA by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses to investigate the potential mechanisms associated with AS. The results showed that a total of 1,172 circRNAs were detected in the spinal ligament tissue samples, of which 123 circRNAs were significantly differentially expressed by a fold change ≥ 1.5 and p value < 0.05. Among these, 57 circRNAs were upregulated, and 66 were downregulated. GO and KEGG analyses demonstrated that the differentially expressed circRNAs were mainly involved in the regulation of biological processes of peptidyl-serine phosphorylation and human immune system that may be related to AS. In addition, the circRNA/miRNA interaction networks were established to predict the potential roles of differentially expressed circRNAs by bioinformatics analysis. Taken together, these results revealed the expression profiles of circRNAs and the potential functions of the differentially expressed circRNAs in the spinal ligament tissue of patients with AS, which may provide new clues for understanding the mechanisms associated with AS, and proceed to identify novel potential molecular targets for the diagnoses and treatment of AS.

LncRNA MEG3 inhibits the inflammatory response of ankylosing spondylitis by targeting miR-146a

Ankylosing spondylitis (AS) is a progressive systemic disease characterized by chronic inflammation response of the sacroiliac joint and spine. Long non-coding RNAs (lncRNAs) are widely involved in the regulation of various diseases. However, the role of lncRNA maternally expressed gene 3 (MEG3) in the inflammatory response of AS has not been studied. Enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of inflammatory cytokines interleukin-1β (IL-1β) and interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in tissues and cells. The expression levels of MEG3, microRNA-146a (miR-146a), and inflammatory cytokines were measured by quantitative real-time PCR (qRT-PCR). Correlation between MEG3 or miR-146a and inflammatory cytokines was analyzed by Pearson analysis. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were used to clarify the interaction between MEG3 and miR-146a. MEG3 was downregulated in AS patients, negatively correlated with the levels of IL-1β, IL-6, and TNF-α, and blocked the inflammatory response of AS. MiR-146a was upregulated in AS patients and could interact with MEG3. The expression of miR-146a was positively correlated with IL-1β, IL-6, and TNF-α levels. Overexpression of miR-146a reversed the inhibitory effect of abnormal MEG3 expression on inflammatory cytokines. LncRNA MEG3 plays an anti-inflammatory role in AS partially through targeting miR-146a, which provides a potential new means for the treatment of AS patients.

Non-coding RNAs in bone remodelling and bone metastasis: Mechanisms of action and translational relevance

Bone metastases are frequent complications in patients with advanced cancer, which can be fatal or may rapidly impede the quality of life of patients. Current treatments for patients with bone metastases are palliative. Therefore, a better understanding of the molecular mechanisms that precede the overt development of skeletal lesions could lead to better therapeutic interventions. In this review, we present evidence that non-coding RNAs (ncRNAs) such as long ncRNAs, microRNAs, and circular RNAs are emerging as master regulators of bone metastasis formation. We highlight potential opportunities for the therapeutic targeting of ncRNAs. Furthermore, we discuss the possibility that ncRNAs may be used as biomarkers in the context of bone metastases, which might provide insight for improving the response to current bone-targeting therapies. LINKED ARTICLES: This article is part of a themed issue on The molecular pharmacology of bone and cancer-related bone diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.9/issuetoc.

H19 Increases IL-17A/IL-23 Releases via Regulating VDR by Interacting with miR675-5p/miR22-5p in Ankylosing Spondylitis

Long non-coding RNA (lncRNA) H19 is associated with inflammatory diseases, but the molecular mechanism of H19 in the inflammatory process of ankylosing spondylitis (AS) is unclear. Here, we investigated the role of H19 and its downstream molecules in the inflammation of AS by microarray analysis, qRT-PCR, western blot, and dual-luciferase reporter assay. H19 small interfering RNA (siRNA) (Si-H19) and adenovirus (AD-H19) were used to decrease and increase H19 expression, respectively. 42 annotated lncRNAs were identified, and H19 was overexpressed. H19, vitamin D receptor (VDR), and transforming growth factor β (TGF-β) can bind to microRNA22-5p (miR22-5p) and miR675-5p. Si-H19 significantly downregulated miR22-5p and upregulated miR675-5p expression; Si-H19 decreased the protein and mRNA expression of VDR and decreased the cytokine and mRNA levels of interleukin-17A (IL-17A) and IL-23. These results were verified by AD-H19. In addition, miR22-5p and miR675-5p inhibitors increased the protein and mRNA expression of VDR and increased the cytokine and mRNA levels of IL-17A and IL-23. These results were also confirmed by miRNA mimics. Furthermore, H19 directly interfered with miR22-5p and miR675-5p expression, whereas the two miRNAs directly inhibited VDR expression. Overall, the H19-miR22-5p/miR675-5p-VDR-IL-17A/IL-23 signaling pathways have important roles in the pathogenesis of AS.

Bone marrow mesenchymal stem cells in rheumatoid arthritis, spondyloarthritis, and ankylosing spondylitis: problems rather than solutions?

Background

Bone marrow mesenchymal stem cells (BM-MSCs) can dampen inflammation in animal models of inflammatory rheumatisms and human osteoarthritis. They are expected to be a solution for numerous human conditions. However, in rheumatoid arthritis (RA) and spondyloarthritis (SpA), subsets of subchondral BM-MSCs might conversely fuel synovitis and enthesitis.

Main text

Abnormal behaviour of BM-MSCs and/or their progeny has been found in RA and SpA. BM-MSCs also contribute to the ossifying processes observed in ankylosing spondylitis. Some synovial fibroblastic stem cells probably derive from BM-MSCs, but some stem cells can also migrate through the bare zone area of joints, not covered by cartilage, into the synovium. BM-MSCs can also migrate in the synovium over tendons. Sub-populations of bone marrow stem cells also invade the soft tissue side of enthesis via small holes in the bone cortex. The present review aims (1) to make a focus on these two aspects and (2) to put forward the hypothesis that lasting epigenetic changes of some BM-MSCs, induced by transient infections of the bone marrow close to the synovium and/or entheses (i.e. trained immunity of BM-MSCs and/or their progeny), contribute to the pathogenesis of inflammatory rheumatisms. Such hypothesis would fit with (1) the uneven distribution and/or flares of arthritis and enthesitis observed at the individual level in RA and SpA (reminiscent of what is observed following reactive arthritis and/or in Whipple’s disease); (2) the subchondral bone marrow oedema and erosions occurring in many RA patients, in the bare zone area; and (3) the frequent relapses of RA and SpA despite bone marrow transplantation, whereas most BM-MSCs resist graft preconditioning.

Conclusion

Some BM-MSCs might be more the problem than the solution in inflammatory rheumatisms. Subchondral bone marrow BM-MSCs and their progeny trafficking through the bare zone area of joints or holes in the bone cortex of entheses should be thoroughly studied in RA and SpA respectively. This may be done first in animal models. Mini-arthroscopy of joints could also be used in humans to specifically sample tissues close to the bare zone and/or enthesis areas.

Effect of Lactoferrin on the Expression Profiles of Long Non-coding RNA during Osteogenic Differentiation of Bone Marrow Mesenchymal Stem Cells

Lactoferrin (LF) has demonstrated stimulation of osteogenic differentiation of mesenchymal stem cells (MSCs). Long non-coding RNAs (lncRNAs) participate in regulating the osteogenic differentiation processes. However, the impact of LF on lncRNA expression in MSC osteogenic differentiation is poorly understood. Our aim was to investigate the effects of LF on lncRNAs expression profiles, during osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs), by RNA sequencing. A total number of 1331 putative lncRNAs were identified in rBMSCs during osteogenic differentiation in the study. LF influenced the expression of 120 lncRNAs (differentially expressed lncRNAs [DELs], Fold change > 1.5 or < −1.5; p < 0.05) in rBMSCs on day 14 of osteogenic differentiation, consisted of 60 upregulated and 60 down-regulated. Furthermore, the potential functions of DELs were of prediction by searching their target cis- and trans-regulated protein-coding genes. The bioinformatic analysis of DELs target gene revealed that LF led to the disfunction of transforming growth factor beta stimulus (TGF-β) and positive regulation of I-κappa B kinase/NF-κappa B signaling pathway, which may relate to osteogenic differentiation of rBMSCs. Our work is the first profiling of lncRNA in osteogenic differentiation of rBMSCs induced by LF, and provides valuable insights into the potential mechanisms for LF promoting osteogenic activity.

Noncoding RNAs Involved in the Pathogenesis of Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a form of arthritis that can lead to fusion of vertebrae and sacroiliac joints following syndesmophyte formation. The etiology of this painful disease remains poorly defined due to its complex genetic background. There are no commonly accepted methods for early diagnosis of AS, nor are there any effective or efficient clinical treatments. Several noncoding RNAs (ncRNAs) have been linked to AS pathogenesis and inflammation via selective binding of their downstream targets. However, major gaps in knowledge remain to be filled before such findings can be translated into clinical treatments for AS. In this review, we outline recent findings that demonstrate essential roles of ncRNAs in AS mediated via multiple signaling pathways such as the Wnt, transforming growth factor-β/bone morphogenetic protein, inflammatory, T-cell prosurvival, and nuclear factor-κB pathways. The summary of these findings provides insight into the molecular mechanisms by which ncRNAs can be targeted for AS diagnosis and the development of therapeutic drugs against a variety of autoimmune diseases.

LncRNA KCNQ1OT1 promoted BMP2 expression to regulate osteogenic differentiation by sponging miRNA-214

BACKGROUND

Osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) is of much significance for bone formation, the imbalance of it would result in osteoporosis and other pathological bone defects. Increasing evidences showed that long non-coding RNAs (lncRNAs) and miRNAs played vital roles in the regulation of osteogenic differentiation. LncRNA KCNQ1OT1 was often regarded as an imprinted lncRNA and was related to tumor progression, while its function in osteogenic differentiation remained unclear.

METHOD

qRT-PCR was performed to detect the expression of KCNQ1OT1, miR-214 and osteogenesis-related genes BMP2, Runx2, OPN, and OCN. Western blotting was carried out to detect osteogenesis-related markers. The osteoblastic phenotype was evidenced by alkaline phosphatase (ALP) activity and Alizarin Red S accumulation detection. Bioinformatics and luciferase assays were used to predict and validate the interaction between KCNQ1OT1 and miR-214 as well as BMP2 and miR-214.

RESULTS

KCNQ1OT1 was significantly up-regulated during the process of osteogenic induction while miR-214 was contrarily down-regulated. Knockdown of KCNQ1OT1 inhibited osteogenic differentiation and down-regulated BMP2 and osteogenesis-related genes. It was also confirmed that KCNQ1OT1 directly interacted with miR-214. Meanwhile, miR-214 could bind to 3'UTR of BMP2 and therefore inhibited its expression. Furthermore, co-transfection of miR-214 inhibitor could rescue the down-regulation of BMP2 and osteogenesis-related genes and osteogenic differentiation suppression induced by KCNQ1OT1 knockdown. Moreover, miR-214 inhibitor significantly reversed the decreased protein levels of p-Smad1/5/8, Runx2 and Osterix induced by shKCNQ1OT1.

CONCLUSIONS

KCNQ1OT1 positively regulated osteogenic differentiation of BMSCs by acting as a ceRNA to regulate BMP2 expression through sponging miR-214.

Long non-coding RNA: The functional regulator of mesenchymal stem cells

Mesenchymal stem cells (MSCs) are a subset of multipotent stroma cells residing in various tissues of the body. Apart from supporting the hematopoietic stem cell niche, MSCs possess strong immunoregulatory ability and multiple differentiation potentials. These powerful capacities allow the extensive application of MSCs in clinical practice as an effective treatment for diseases. Therefore, illuminating the functional mechanism of MSCs will help to improve their curative effect and promote their clinical use. Long noncoding RNA (LncRNA) is a novel class of noncoding RNA longer than 200 nt. Recently, multiple studies have demonstrated that LncRNA is widely involved in growth and development through controlling the fate of cells, including MSCs. In this review, we highlight the role of LncRNA in regulating the functions of MSCs and discuss their participation in the pathogenesis of diseases and clinical use in diagnosis and treatment.

Long non-coding RNA in osteogenesis: A new world to be explored

Long non-coding RNAs (lncRNAs) are transcripts longer than 200 nucleotides with limited coding potential, which have emerged as novel regulators in many biological and pathological processes, including growth, development, and oncogenesis. Accumulating evidence suggests that lncRNAs have a special role in the osteogenic differentiation of various types of cell, including stem cells from different sources such as embryo, bone marrow, adipose tissue and periodontal ligaments, and induced pluripotent stem cells. Involved in complex mechanisms, lncRNAs regulate osteogenic markers and key regulators and pathways in osteogenic differentiation. In this review, we provide insights into the functions and molecular mechanisms of lncRNAs in osteogenesis and highlight their emerging roles and clinical value in regenerative medicine and osteogenesis-related diseases.

Cite this article: J. Zhang, X. Hao, M. Yin, T. Xu, F. Guo. Long non-coding RNA in osteogenesis: A new world to be explored. Bone Joint Res 2019;8:73–80. DOI: 10.1302/2046-3758.82.BJR-2018-0074.R1.

LncRNA-OG Promotes the Osteogenic Differentiation of Bone Marrow-Derived Mesenchymal Stem Cells Under the Regulation of hnRNPK

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are the main source of osteoblasts in vivo and are widely used in stem cell therapy. Previously, we analyzed long noncoding RNA (lncRNA) expression profiles during BM-MSC osteogenesis, and further investigation is needed to elucidate how lncRNAs regulate BM-MSC osteogenesis. Herein, we used customized microarrays to determine lncRNA expression profiles in BM-MSCs on days 0 and 10 of osteogenic differentiation. In addition, we identified a novel osteogenesis-associated lncRNA (lncRNA-OG) that is upregulated during this process. Functional assays showed that lncRNA-OG significantly promotes BM-MSC osteogenesis. Mechanistically, lncRNA-OG interacts with heterogeneous nuclear ribonucleoprotein K (hnRNPK) protein to regulate bone morphogenetic protein signaling pathway activation. Surprisingly, hnRNPK positively regulates lncRNA-OG transcriptional activity by promoting H3K27 acetylation of the lncRNA-OG promoter. Therefore, our study revealed a novel lncRNA with a positive function on BM-MSC osteogenic differentiation and proposed a new interaction between hnRNPK and lncRNA. Stem Cells 2018 Stem Cells 2019;37:270-283.

Identification of the key genes and long non‑coding RNAs in ankylosing spondylitis using RNA sequencing

Ankylosing spondylitis (AS) is an insidious and debilitating form of arthritis that involves the axial skeleton, and its etiology and pathogenesis remain unclear. In the present study, three patients with AS and three normal controls from our hospital were enrolled. RNA sequencing and bioinformatics analysis were performed in order to identify the differentially expressed (DE) mRNAs (DEmRNAs) and DE long non‑coding RNAs (DElncRNAs) between the patients with AS and normal controls. Construction of an AS‑specific protein‑protein interaction network, a weighted DElncRNA‑DEmRNA co‑expression network and functional annotation of the DEmRNAs co‑expressed with DElncRNAs was performed. Nearby cis‑targeted DEmRNAs or DElncRNAs were identified by searching for DEmRNAs that were transcribed within 100‑kb up‑ or downstream of DElncRNAs. Based on the Gene Expression Omnibus datasets GSE25101 and GSE73754, the expression of selected DEmRNAs and DElncRNAs were verified using published RNA sequencing data from blood samples, and receiver operating characteristic analysis of selected DEmRNAs was performed. Compared with the normal controls, 1,072 DEmRNAs and 372 DElncRNAs in the patients with AS were identified. Caspase recruitment domain family member 11 and DNA methyltransferase 1 have great diagnostic value for AS. MSTRG.8559 and LINC00987 were also identified as two hub DElncRNAs. The T‑cell receptor signaling pathway was a significantly enriched pathway of the DEmRNAs co‑expressed with DElncRNAs in patients with AS. In conclusion, the present study identified the key DEmRNAs and DElncRNAs in AS, which provides novel information for understanding the pathogenesis of AS and developing potential biomarkers for AS.

lncRNA MEG3 is downregulated in ankylosing spondylitis and associated with disease activity, hospitalization time and disease duration

Long non-coding (lnc)RNA maternally expressed gene 3 (MEG3) has been proved to participate in osteoporosis, which features inverse pathological changes to those associated with spondylosis. The present study aimed to investigate the involvement of lncRNA MEG3 in ankylosing spondylitis. Blood and open sacroiliac joint biopsies were obtained from ankylosing spondylitis patients and healthy controls, and the expression of MEG3 in those tissues was detected by reverse-transcription-quantitative polymerase chain reaction analysis. Disease activity was evaluated according to the Ankylosing Spondylitis Disease Activity Score established by the International Association of Ankylosing Spondylitis. The diagnostic value of MEG3 expression for ankylosing spondylitis was evaluated by receiver operating characteristic curve analysis. The correlation between MEG3 expression and disease activity was assessed using Pearson correlation analysis. Furthermore, according to the median expression level of MEG3, patients were divided into high-level and low-level groups. The hospitalization time and re-hospitalization rate within 2 years after discharge were compared between these two groups and differences in clinicopathological parameters between the two groups were analyzed using the chi-square test. The results indicated that MEG3 was downregulated in ankylosing spondylitis patients compared with that in healthy controls. Furthermore, MEG3 expression levels may be used to effectively distinguish ankylosing spondylitis patients from healthy controls. The serum levels of MEG3 were not associated with the patients' age, sex or alcohol/tobacco consumption, but closely correlated with disease activity and disease duration. In addition, patients with higher expression levels of MEG3 had a shorter hospitalization time and a lower re-hospitalization rate within 2 years after discharge It was concluded that lncRNA MEG3 is downregulated in ankylosing spondylitis patients and is associated with disease activity, time of hospitalization and disease duration.

LncRNA expression profiling of BMSCs in osteonecrosis of the femoral head associated with increased adipogenic and decreased osteogenic differentiation

Long noncoding RNAs (lncRNAs) are critical gene expression regulators and are involved in several bone diseases. To explore the potential roles of lncRNAs in osteonecrosis of the femoral head (ONFH), we investigated for the first time the lncRNA expression profile of bone marrow mesenchymal stem cells (BMSCs) from patients with steroid-induced ONFH (SONFH) with microarray and bioinformatics analysis. A total of 1878 lncRNAs and 838 mRNAs were significantly up-regulated while 1842 lncRNAs and 1937 mRNAs were statistically down-regulated in the SONFH group compared with control group. The results validated by qRT-PCR were consistent with the microarray profiling data, especially involved in upregulation and downregulation of critical lncRNAs as well as mRNAs expression related to adipogenic and osteogenic differentiation. Pathway analyses revealed 40 signaling pathways with significant differences, especially the signaling pathways to regulate stem cell pluripotency. The CNC and ceRNA network indicated that lncRNA RP1-193H18.2, MALAT1 and HOTAIR were associated with abnormal osteogenic and adipogenic differentiation of BMSCs in the patients with SONFH. Our results suggest the lncRNA expression profiles were closely associated with the abnormal adipogenic and osteogenic transdifferentiation of BMSCs during the development of SONFH and explore a new insight into the molecular mechanisms of SONFH.

The long noncoding RNA GAS5 negatively regulates the adipogenic differentiation of MSCs by modulating the miR-18a/CTGF axis as a ceRNA

Mesenchymal stem cells (MSCs) are important pluripotent stem cells and a major source of adipocytes in the body. However, the mechanism of adipogenic differentiation has not yet been completely elucidated. In this study, the long noncoding RNA GAS5 was found to be negatively correlated with MSC adipogenic differentiation. GAS5 overexpression negatively regulated adipocyte formation, whereas GAS5 knockdown had the opposite effect. Further mechanistic analyses using luciferase reporter assays revealed that GAS5 regulates the adipogenic differentiation of MSCs by acting as competing endogenous RNA (ceRNA) to sponge miR-18a, which promotes adipogenic differentiation. Mutation of the binding sites for GAS5 in miR-18a abolished the effect of the interaction. The miR-18a mimic and inhibitor reversed the negative regulatory effect of GAS5 on MSCs adipogenic differentiation. In addition, GAS5 inhibited miR-18a, which downregulates connective tissue growth factor (CTGF) expression, to negatively regulate the adipogenic differentiation of MSCs. Taken together, the results show that GAS5 serves as a sponge for miR-18a, inhibiting its capability to suppress CTGF protein translation and ultimately decreasing the adipogenic differentiation of MSCs. GAS5 is an important molecule involved in the adipogenic differentiation of MSCs and may contribute to the functional regulation and clinical applications of MSCs.

Accelerated osteogenic differentiation of human bone-derived cells in ankylosing spondylitis

Ankylosing spondylitis (AS) is characterized by excessive bone formation with syndesmophytes, leading to bony ankylosis. The contribution of osteoblasts to the pathogenesis of ankylosis is poorly understood. The aim of this study was to determine molecular differences between disease controls (Ct) and AS bone-derived cells (BdCs) during osteogenic differentiation with or without inflammation using AS patient serum. We confirmed osteoblastic differentiation of Ct and AS BdCs under osteogenic medium by observing morphological changes and measuring osteoblastic differentiation markers. Osteoblast differentiation was detected by alkaline phosphatase (ALP) staining and activity, and alizarin red and hydroxyapatite staining. Osteoblast-specific markers were analyzed by quantitative reverse-transcriptase-polymerase chain reaction, immunoblotting, and immunostaining. To examine the effects of inflammation, we added AS and healthy control serum to Ct and AS BdCs, and then analyzed osteoblast-specific markers. AS BdCs showed elevated basal intercellular and extracellular ALP activity compared to Ct. When osteoblast differentiation was induced, AS BdCs exhibited higher expression of osteoblast-specific marker genes and faster mineralization than Ct, indicating that these cells differentiated more rapidly into osteoblasts. ALP activity and mineralization accelerated when serum from AS patients was added to Ct and AS BdCs. Our results revealed that AS BdCs showed significantly increased osteoblastic activity and differentiation capacity by regulating osteoblast-specific transcription factors and proteins compared to Ct BdCs. Active inflammation of AS serum accelerated osteoblastic activity. Our study could provide useful basic data for understanding the molecular mechanism of ankylosis in AS.

Long Noncoding RNA Sponges miR-454 to Promote Osteogenic Differentiation in Maxillary Sinus Membrane Stem Cells

OBJECTIVE

Although increasing evidence has shown that long noncoding RNAs (lncRNAs) play an important regulatory role in pluripotency and differentiation of mesenchymal stem cells, little is known about the role of lncRNA in maxillary sinus membrane stem cells (MSMSCs). The goal of this study was to investigate the expression profile and function of lncRNAs on osteogenic differentiation of MSMSCs.

MATERIALS AND METHODS

By using lncRNA microarray, we identify a novel osteogenesis differentiation-related lncRNA of MSMSCs (lncRNA-MODR). The functional role of lncRNA-MODR in regulating osteogenesis was evaluated by quantitative real-time polymerase chain reaction, western blot, and alizarin red staining. Bioinformatic analyses of the predicted target genes (gene ontology, pathway, and network analysis) were applied for further study of lncRNA-MODR.

RESULTS

We show that lncRNA-MODR is gradually upregulated during osteogenic differentiation. lncRNA-MODR overexpression upregulated, whereas lncRNA-MODR silencing decreased the expression of the osteogenic key marker, runt-related transcription factor 2 (RUNX2). In-depth analyses showed that lncRNA-MODR acts as a molecular sponge for microRNA-454 (miR-454) and that prevents RUNX2 from mi-454-mediated suppression.

CONCLUSION

The lncRNAs act as a competing endogenous RNA to sequester microRNA-454 (miR-454), leading to heightened RUNX2 expression and thus promotes osteogenesis of MSMSCs.

Differentially expressed mRNAs, lncRNAs, and miRNAs with associated co-expression and ceRNA networks in ankylosing spondylitis

Ankylosing spondylitis (AS) is a chronic autoimmune disease characterized by systemic inflammation and pathological osteogenesis. However, the genetic etiology of AS remains largely unknown. This study aimed to explore the potential role of coding and noncoding genes in the genetic mechanism of AS. Using microarray analyses, this study comprehensively compared lncRNA, microRNA, and mRNA profiles in hip joint ligament tissues from patients with AS and controls. A total of 661 lncRNAs, 574 mRNAs, and 22 microRNAs were differentially expressed in patients with AS compared with controls. Twenty-two of these genes were then validated using real-time polymerase chain reaction. Gene ontology and pathway analyses were performed to explore the principal functions of differentially expressed genes. The pathways were involved mainly in immune regulation, intercellular signaling, osteogenic differentiation, protein synthesis, and degradation. Gene signal transduction network, coding-noncoding co-expression network, and competing endogenous RNA expression network were constructed using bioinformatics methods. Then, two miRNAs, miR-17-5p and miR-27b-3p, that could increase the osteogenic differentiation potentials of ligament fibroblasts were identified. Finally, differentially expressed, five lncRNAs, four miRNAs, and five mRNAs were validated using quantitative real-time polymerase chain reaction. These results suggested that mRNAs, lncRNAs, and microRNAs were involved in AS pathogenesis. The findings might help characterize the pathogenesis of AS and provide novel therapeutic targets for patients with AS in the future.