Roles of MicroRNAs in Bone Destruction of Rheumatoid Arthritis

Role of MicroRNAs in Inflammatory Joint Diseases: A Review

Inflammatory arthritis commonly initiates in the soft tissues lining the joint. This lining swells, as do the cells in it and inside the joint fluid, producing chemicals that induce inflammation signs such as heat, redness, and swelling. MicroRNA (miRNA), a subset of non-coding small RNA molecules, post-transcriptionally controls gene expression by targeting their messenger RNA. MiRNAs modulate approximately 1/3 of the human genome with their multiple targets. Recently, they have been extensively studied as key modulators of the innate and adaptive immune systems in diseases such as allergic disorders, types of cancer, and cardiovascular diseases. However, research on the different inflammatory joint diseases, such as rheumatoid arthritis, gout, Lyme disease, ankylosing spondylitis, and psoriatic arthritis, remains in its infancy. This review presents a deeper understanding of miRNA biogenesis and the functions of miRNAs in modulating the immune and inflammatory responses in the above-mentioned inflammatory joint diseases. According to the literature, it has been demonstrated that the development of inflammatory joint disorders is closely related to different miRNAs and their specific regulatory mechanisms. Furthermore, they may present as possible prognostic and diagnostic biomarkers for all diseases and may help in developing a therapeutic response. However, further studies are needed to determine whether manipulating miRNAs can influence the development and progression of inflammatory joint disorders.

Small RNA signatures of the anterior cruciate ligament from patients with knee joint osteoarthritis

Introduction: The anterior cruciate ligament (ACL) is susceptible to degeneration, resulting in joint pain, reduced mobility, and osteoarthritis development. There is currently a paucity of knowledge on how anterior cruciate ligament degeneration and disease leads to osteoarthritis. Small non-coding RNAs (sncRNAs), such as microRNAs and small nucleolar RNA (snoRNA), have diverse roles, including regulation of gene expression. Methods: We profiled the sncRNAs of diseased osteoarthritic ACLs to provide novel insights into osteoarthritis development. Small RNA sequencing from the ACLs of non- or end-stage human osteoarthritic knee joints was performed. Significantly differentially expressed sncRNAs were defined, and bioinformatics analysis was undertaken. Results and Discussion: A total of 184 sncRNAs were differentially expressed: 68 small nucleolar RNAs, 26 small nuclear RNAs (snRNAs), and 90 microRNAs. We identified both novel and recognized (miR-206, -365, and -29b and -29c) osteoarthritis-related microRNAs and other sncRNAs (including SNORD72, SNORD113, and SNORD114). Significant pathway enrichment of differentially expressed miRNAs includes differentiation of the muscle, inflammation, proliferation of chondrocytes, and fibrosis. Putative mRNAs of the microRNA target genes were associated with the canonical pathways "hepatic fibrosis signaling" and "osteoarthritis." The establishing sncRNA signatures of ACL disease during osteoarthritis could serve as novel biomarkers and potential therapeutic targets in ACL degeneration and osteoarthritis development.

miRNAs insights into rheumatoid arthritis: Favorable and detrimental aspects of key performers

Rheumatoid arthritis (RA) is a severe autoimmune inflammation that mostly affects the joints. It's a multifactorial disease. Its clinical picture depends on genetic and epigenetic factors such as miRNAs. The miRNAs are small noncoding molecules that are able to negatively or positively modulate their target gene expression. In RA, miRNAs are linked to its pathogenesis. They disrupt immunity balance by controlling granulocytes, triggering the release of several proinflammatory cytokines such as interleukin-6 and tumor necrosis factor-α, finally leading to synovium hyperplasia and inflammation. Besides, they also may trigger activation of some pathways as nuclear factor kappa-β disrupts the balance between osteoclast and osteoblast activity, leading to increased bone destruction. Moreover, miRNAs are also applied with efficiency in RA diagnosis and prognosis. Besides the significant association between miRNAs and RA response to treatment, they are also applied as a choice for treatment based on their effects on the immune system and inflammatory cytokines. Hence, the review aims to present an updated overview of miRNAs, their biogenesis, implications in RA pathogenesis, and finally, the role of miRNAs in RA treatment.

Micro RNA in meniscal ailments: current concepts

INTRODUCTION

Micro RNAs (miRNAs) are short non-coding RNAs that act primarily in posttranscriptional gene silencing, and are attracting increasing interest in musculoskeletal conditions.

SOURCE OF DATA

Current scientific literature published in PubMed, Google Scholar, Embase and Web of Science databases.

AREAS OF AGREEMENT

Recently, the potential of miRNAs as biomarkers for diagnosis and treatment of meniscal injuries has been postulated.

AREAS OF CONTROVERSY

Evaluation of the role of miRNAs in patients with meniscal tears is still controversial.

GROWING POINTS

A systematic review was conducted to investigate the potential of miRNA in the diagnosis and management of meniscal damage.

AREAS TIMELY FOR DEVELOPING RESEARCH

Intra-articular injection of microRNA-210 in vivo may represent a potential innovative methodology for the management of meniscal injuries. Characterization of the miRNAs expression in the synovial fluid could lead to the development of better early diagnosis and management strategies for meniscal tears.

The effect of long non-coding RNAs in joint destruction of rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease accompanied with joint destruction. Serious joint destruction will eventually lead to disability and the decline of life quality in RA patients. At present, the therapeutic effect of drugs to alleviate joint destruction in RA is limited. Recently, accumulating evidences have shown that long non-coding RNAs (lncRNAs) play an important role in the pathogenesis of joint diseases. Therefore, this paper reviews the expression change and the action mechanism of lncRNAs in joint destruction of RA in recent years. A more comprehensive understanding of the role of lncRNAs in joint destruction will help the treatment of RA.

EZH2 regulates the balance between osteoclast and osteoblast differentiation to inhibit arthritis-induced bone destruction

Enhancer of zeste homolog 2 (EZH2) has been noted to contribute to the pathogenesis of autoimmune diseases. This study sought to investigate the mechanism of EZH2 in osteoclast (OCL) and osteoblast (OBL) differentiation (OCLD/OBLD) and bone destruction in RA. The animal model of collagen-induced arthritis (CIA) was established, followed by arthritis index (AI) scoring and histological staining, and measurements of inflammatory cytokines levels. The number of OCLs was detected via Tartrate-resistant acid phosphatase (TRAP) staining, and levels of OBL markers were determined by Western blot analysis. Trimethylated histone H3 at lysine 27 (H3K27me3) expression and its enrichment in the Ndrg2 promoter were detected. Collaborative experiments were performed with GSK-J1 or sh-Ndrg2 in CIA mice with EZH2 knockdown. EZH2 was upregulated while Ndrg2 was downregulated in knee joint tissues of CIA mice. Silencing EZH2 reduced AI scores, pathological injury of the knee joint, levels of inflammatory cytokines, and TRAP-positive cells, and increased protein levels of RUNX2 and BMP2. EZH2 promoted H3K27me3 level in the Ndrg2 promoter to inhibit Ndrg2 transcription. H3K27me3 upregulation or Ndrg2 downregulation reversed the role of silencing EZH2 in bone destruction. Overall, EZH2 repressed OBLD and promoted OCLD to aggravate bone destruction in CIA mice through H3K27me3/Ndrg2.

Regulation of osteoclast-mediated bone resorption by microRNA

Osteoclast-mediated bone resorption is responsible for bone metabolic diseases, negatively impacting people's health and life. It has been demonstrated that microRNA influences the differentiation of osteoclasts by regulating the signaling pathways during osteoclast-mediated bone resorption. So far, the involved mechanisms have not been fully elucidated. This review introduced the pathways involved in osteoclastogenesis and summarized the related microRNAs binding to their specific targets to mediate the downstream pathways in osteoclast-mediated bone resorption. We also discuss the clinical potential of targeting microRNAs to treat osteoclast-mediated bone resorption as well as the challenges of avoiding potential side effects and producing efficient delivery methods.

Inhibition of miRNA-100 facilitates bone regeneration defects of mesenchymal stem cells in osteoporotic mice through the protein kinase B pathway

Osteoporotic patients suffer from bone microstructure damage and are prone to fracture and bone defect. Due to the damage of bone healing ability, the bone repair of osteoporotic patients is usually slow. Here we aimed to explore the function and potential molecular mechanism of miR-100 in osteogenic differentiation ability of bone marrow stem cells (BMSCs). Ovariectomy was performed on mice to induce osteoporosis. BMSCs were extracted from normal and ovariectomized (OVX) mice to examine the effect of microRNA (miR)-100 on BMSC osteogenic differentiation. Hematoxylin and eosin (H&E) staining and safranin O-fast green staining assays were performed on femur tissues to reveal pathological changes. The osteogenic differentiation of BMSCs were determined by Alkaline Phosphatase and Alizarin red staining assays. The results showed that miR-100 expression was significantly upregulated in bone tissues and BMSCs from osteoporotic mice. MiR-100 knockdown partially improved osteogenic function of OVX mice-derived BMSCs. Next, mechanistic target of rapamycin kinase (MTOR) was identified as the target downstream miR-100. MiR-100 deficiency can activate the protein kinase B (AKT)/mTOR pathway. MiR-100 controlled the osteogenic function of BMSCs by the AKT/mTOR pathway. Collectively, our findings demonstrate that inhibition of miR-100 facilitates bone regeneration defects of BMSCs in osteoporotic mice through AKT pathway, indicating that miR-100 might be an effective target for the treatment of osteoporotic mandibular injury and bone defect diseases.

An alcohol extract prepared from the male flower of Eucommia ulmoides Oliv. promotes synoviocyte apoptosis and ameliorates bone destruction in rheumatoid arthritis

Background

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease dominated by synovial hyperplasia and bone destruction. The male flower of Eucommia ulmoides Oliv. (EF) has been shown to exert effects on the inflammation caused by RA. However, how EF affects synoviocyte apoptosis and bone destruction on RA have not been investigated thoroughly. The effects of EF on apoptosis of human fibroblast-like synoviocytes-rheumatoid arthritis (HFLS-RA) cells, osteoclast differentiation of RAW264.7 cells, and bone destruction in a collagen-induced arthritis (CIA) model in rats were explored.

Methods

First, the main components of EF were identified by high-performance liquid chromatography. In vitro, we investigated the anti-proliferative and pro-apoptotic effects of EF on HFLS-RA cells by immunofluorescence assays, flow cytometry, real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and western blotting; we also investigated how EF influenced the differentiation of RAW264.7 cells into osteoclasts. In vivo, we used a rat model of CIA to investigate the effects of EF on anti-arthritis activity, toe swelling, Arthritis Score, serum levels of metabolic bone factors, and pathologic conditions. Micro-computed tomography was used to scan ankle joints. mRNA and protein expression of factors related to the nuclear factor-kappa B (NF-κB) pathway were determined by RT-qPCR and western blotting, respectively.

Results

EF inhibited synoviocyte proliferation and promoted apoptosis in a dose-dependent manner. EF inhibited osteoclast differentiation by inhibiting activation of the NF-κB pathway. EF reduced articular inflammation in CIA rats, inhibited the expression of pro-angiogenic factors, and delayed the destruction of articular cartilage and bone. Our data indicated that EF acted via a mechanism related to bone metabolism induced by the NF-κB pathway.

Conclusions

EF exerts a potential therapeutic effect upon RA. Our research will help to elucidate the potential pharmacologic mechanisms associated with the beneficial effects of EF, and provide an experimental basis for EF application in clinical treatments.

Graphical Abstract

Traditional herbal medicine: Therapeutic potential in rheumatoid arthritis

ETHNOPHARMACOLOGICAL RELEVANCE

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease influenced by diverse endogenous and exogenous factors. It is characterized by cartilage and bone destruction. The current conventional allopathic therapy is expensive and carries adverse side effects. Recently, there were some ethnopharmacological studies on RA including anti-RA effects and therapeutic targets of distinct dosage forms of traditional herbal medicines (THMs).

AIM OF THE REVIEW

This review provides a brief overview of the current understanding of the potential pharmacological mechanisms of THMs (active constituents, extracts and prescriptions) in RA. This study is intended to provide comprehensive information and reference for exploring new therapeutic strategies of THMs in the RA treatment.

MATERIALS AND METHODS

This review captured scientific literatures invivo and vitro experiments on effects of anti-RA THMs published between 2016 and 2021 from journals and electronic databases (e.g. PubMed, Elsevier, Science Direct, Web of Science and Google Scholar). Relevant literatures were searched and analyzed by using keywords such as 'rheumatoid arthritis AND traditional herbal medicines', 'rheumatoid arthritis AND immune cells', 'rheumatoid arthritis AND inflammation', 'rheumatoid arthritis AND miRNA', 'rheumatoid arthritis AND Angiogenesis', 'rheumatoid arthritis AND oxidative stress', 'rheumatoid arthritis AND osteoclasts', 'rheumatoid arthritis AND CIA model', 'rheumatoid arthritis AND AA model' AND 'rheumatoid arthritis herbal prescription'.

RESULTS

Experiments in vitro and in vivo jointly demonstrated the potential of THMs in the RA treatment. There are plentiful therapeutic targets in RA. THMs and active ingredients could alleviate RA symptoms through different therapeutic targets, such as immunoregulation, inflammation, fibroblast-like synoviocytes (FLSs), microRNAs (miRNAs), angiogenesis, oxidative stress, osteoclasts and multiple targets interaction. Anti-RA THMs, active ingredients and prescriptions through corresponding therapeutic targets were summarized and classified.

CONCLUSIONS

Flavonoids, phenolic acids, alkaloids and triterpenes of THMs are identified as the main components to ameliorate RA. Regulation of different and multiple related therapeutic targets by THMs and their active ingredients were associated with greater therapeutic benefits, among which inflammation is the main therapeutic target. Nonetheless, further studies are required to unravel the complexities and in-depth mechanisms of THMs in alleviating RA.

Integrative Analysis of lncRNA-mRNA Profile Reveals Potential Predictors for SAPHO Syndrome

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is known as a rare disease characterized by inflammatory lesions on bones and skin. Polymorphism of clinical manifestation and lack of molecular biomarkers have both limited its diagnosis. Our study performed RNA sequencing (RNA-seq) and integrative bioinformatics analysis of long noncoding RNA (lncRNA)-messenger RNA (mRNA) profile in patients with SAPHO syndrome and healthy controls. A total of 4,419 differentially expressed (DE) mRNAs and 2,713 lncRNAs were identified (p < 0.05, fold change > 2) and a coexpression network was constructed to further investigate their regulatory interactions. The DE lncRNAs were predicted to interact with mRNAs in both cis and trans manners. Functional prediction found that the lncRNA-targeted genes may function in SAPHO syndrome by participating in biological process such as adipocytokine signaling pathway, ErbB signaling pathway, FoxO signaling pathway, as well as production and function of miRNAs. The expression levels of three pairs of coexpressed lncRNA-mRNAs were validated by qRT-PCR, and their relative expression levels were consistent with the RNA-seq data. The deregulated RNAs GAS7 and lnc-CLLU1.1-1:2 may serve as potential diagnostic biomarkers, and the combined receiver operating characteristic (ROC) curve of the two showed more reliable diagnostic ability with an AUC value of 0.871 in distinguishing SAPHO patients from healthy controls. In conclusion, this study provides a first insight into long noncoding RNA transcriptome profile changes associated with SAPHO syndrome and inspiration for further investigation on clinical biomarkers and molecular regulators of this inadequately understood clinical entity.

Osteoblast role in the pathogenesis of rheumatoid arthritis

In the pathogenesis of several rheumatic diseases, such as rheumatoid arthritis, spondyloarthritis, osteoarthritis, osteoporosis, alterations in osteoblast growth, differentiation and activity play a role. In particular, in rheumatoid arthritis bone homeostasis is perturbed: in addition to stimulating the pathologic bone resorption process performed by osteoclasts in course of rheumatoid arthritis, proinflammatory cytokines (such as Tumor Necrosis factor-α, Interleukin-1) can also inhibit osteoblast differentiation and function, resulting in net bone loss. Mouse models of rheumatoid arthritis showed that complete resolution of inflammation (with maximal reduction in the expression of pro-inflammatory factors) is crucial for bone healing, performed by osteoblasts activity. In fact, abnormal activity of factors and systems involved in osteoblast function in these patients has been described. A better understanding of the pathogenic mechanisms involved in osteoblast dysregulation could contribute to explain the generalized and focal articular bone loss found in rheumatoid arthritis. Nevertheless, these aspects have not been frequently and directly evaluated in studies. This review article is focused on analysis of the current knowledge about the role of osteoblast dysregulation occurring in rheumatoid arthritis: a better knowledge of these mechanisms could contribute to the realization of new therapeutic strategies.