LncRNA MEG3 inhibits rheumatoid arthritis through miR-141 and inactivation of AKT/mTOR signalling pathway

The role of long noncoding RNA MEG3 in fibrosis diseases

Fibrosis is a prevalent pathological condition observed in various organs and tissues. It primarily arises from the excessive and abnormal accumulation of the extracellular matrix, resulting in the structural and functional impairment of tissues and organs, which can culminate in death. Many forms of fibrosis, including liver, cardiac, pulmonary, and renal fibrosis, are considered irreversible. Maternally expressed gene 3 (MEG3) is an imprinted RNA gene. Historically, the downregulation of MEG3 has been linked to tumor pathogenesis. However, recent studies indicate an emerging association of MEG3 with fibrotic diseases. In this review, we delve into the current understanding of MEG3's role in fibrosis, aiming to shed light on the molecular mechanisms of fibrosis and the potential of MEG3 as a novel therapeutic target.

Unveiling Novel Drug Targets and Emerging Therapies for Rheumatoid Arthritis: A Comprehensive Review

Rheumatoid arthritis (RA) is a chronic debilitating autoimmune disease, that causes joint damage, deformities, and decreased functionality. In addition, RA can also impact organs like the skin, lungs, eyes, and blood vessels. This autoimmune condition arises when the immune system erroneously targets the joint synovial membrane, resulting in synovitis, pannus formation, and cartilage damage. RA treatment is often holistic, integrating medication, physical therapy, and lifestyle modifications. Its main objective is to achieve remission or low disease activity by utilizing a "treat-to-target" approach that optimizes drug usage and dose adjustments based on clinical response and disease activity markers. The primary RA treatment uses disease-modifying antirheumatic drugs (DMARDs) that help to interrupt the inflammatory process. When there is an inadequate response, a combination of biologicals and DMARDs is recommended. Biological therapies target inflammatory pathways and have shown promising results in managing RA symptoms. Close monitoring for adverse effects and disease progression is critical to ensure optimal treatment outcomes. A deeper understanding of the pathways and mechanisms will allow new treatment strategies that minimize adverse effects and maintain quality of life. This review discusses the potential targets that can be used for designing and implementing precision medicine in RA treatment, spotlighting the latest breakthroughs in biologics, JAK inhibitors, IL-6 receptor antagonists, TNF blockers, and disease-modifying noncoding RNAs.

Role of long non-coding RNA in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a group of recurrent chronic inflammatory diseases, including Crohn's disease (CD) and ulcerative colitis (UC). Although IBD has been extensively studied for decades, its cause and pathogenesis remain unclear. Existing research suggests that IBD may be the result of an interaction between genetic factors, environmental factors and the gut microbiome. IBD is closely related to non-coding RNAs (ncRNAs). NcRNAs are composed of microRNA(miRNA), long non-coding RNA(lnc RNA) and circular RNA(circ RNA). Compared with miRNA, the role of lnc RNA in IBD has been little studied. Lnc RNA is an RNA molecule that regulates gene expression and regulates a variety of molecular pathways involved in the pathbiology of IBD. Targeting IBD-associated lnc RNAs may promote personalized treatment of IBD and have therapeutic value for IBD patients. Therefore, this review summarized the effects of lnc RNA on the intestinal epithelial barrier, inflammatory response and immune homeostasis in IBD, and summarized the potential of lnc RNA as a biomarker of IBD and as a predictor of therapeutic response to IBD in the future.

Roles of long noncoding RNAs in human inflammatory diseases

Chemokines, cytokines, and inflammatory cells mediate the onset and progression of many diseases through the induction of an inflammatory response. LncRNAs have emerged as important regulators of gene expression and signaling pathways. Increasing evidence suggests that lncRNAs are key players in the inflammatory response, making it a potential therapeutic target for various diseases. From the perspective of lncRNAs and inflammatory factors, we summarized the expression level and regulatory mechanisms of lncRNAs in human inflammatory diseases, such as cardiovascular disease, osteoarthritis, sepsis, chronic obstructive pulmonary disease, asthma, acute lung injury, diabetic retinopathy, and Parkinson's disease. We also summarized the functions of lncRNAs in the macrophages polarization and discussed the potential applications of lncRNAs in human inflammatory diseases. Although our understanding of lncRNAs is still in its infancy, these data will provide a theoretical basis for the clinical application of lncRNAs.

Long Non-Coding RNA AL928768.3 Promotes Rheumatoid Arthritis Fibroblast-Like Synoviocytes Proliferation, Invasion and Inflammation, While Inhibits Apoptosis Via Activating Lymphotoxin Beta Mediated NF-κB Signaling Pathway

Our previous study using RNA sequencing and reverse transcription quantitative polymerase chain reaction (RT-qPCR) validation identified a long non-coding RNA (lnc), lnc-AL928768.3, correlating with risk and disease activity of rheumatoid arthritis (RA), then the present study was conducted to further investigate the interaction of lnc-AL928768.3 with lymphotoxin beta (LTB) and their impact on proliferation, migration, invasion, and inflammation in RA-fibroblast-like synoviocytes (RA-FLS). Human RA-FLS was obtained and transfected with lnc-AL928768.3 overexpression, negative control overexpression, lnc-AL928768.3 short hairpin RNA (shRNA) and negative control shRNA plasmids. Then cell functions and inflammatory cytokine expressions were detected. Afterward, rescue experiments were conducted via transfecting lnc-AL928768.3 shRNA with or without LTB overexpression plasmids in RA-FLS. Lnc-AL928768.3 enhanced proliferation and invasion, inhibited apoptosis, while had little impact on migration in RA-FLS. In addition, lnc-AL928768.3 positively modulated interleukin-1β (IL-1β), IL-6 and IL-8 expressions in RA-FLS supernatant; moreover, it also positively regulated LTB mRNA expression, LTB protein expression, p-NF-κB protein expression, and p-IKB-α protein expression in RA-FLS. Furthermore, following experiment showed that lnc-AL928768.3 positively regulated LTB expression while LTB did not impact on lnc-AL928768.3 expression in RA-FLS. Furthermore, in rescue experiments, LTB overexpression curtailed the effect of lnc-AL928768.3 knock-down on regulating proliferation, invasion, apoptosis and inflammatory cytokine expressions in RA-FLS. Lnc-AL928768.3 promotes proliferation, invasion, and inflammation while inhibits apoptosis of RA-FLS via activating LTB mediated NF-κB signaling.

Study of serum exosome miRNA as a biomarker for early onset adult ouclar myastthenia gravis

BACKGROUND

By extracting and sequencing miRNAs from serum exosomes of patients with early-onset ocular myasthenia gravis (OMG), generalized myasthenia gravis (GMG) and healthy controls, we screened differentially expressed miRNAs and explored the possibility as potential biomarkers for early-onset OMG.

METHODS

Peripheral blood samples were collected from patients with early-onset OMG, early-onset GMG, and age-matched healthy subjects, with 6 samples in each group. All these patients were diagnosed as MG for the first time and did not undergo any treatment. Exosomes miRNAs were extracted from the serum and performed deep sequencing; the differentially expressed miRNAs were compared and analyzed between OMG, GMG, and healthy control groups using edgeR. The differential expression standard was set to | log2FC |>1, p < 0.05. Target prediction of mRNAs were performed using miRTarBase, TargetScan, and miRDB databases, and a protein-protein interaction (PPI) network was constructed subsequently. The miRNAs with a significant difference were validated using RT-qPCR (10 early-onset OMG patients, 10 early-onset GMG patients and 10 age-sex-matched healthy subjects), and the value of the area under the ROC curve (AUC) was used to assess the diagnostic accuracy and evaluate clinical prognostic value.

RESULTS

In total, one upregulated (miR-130a-3p) miRNA was obtained through the upregulated intersection between control vs OMG and OMG vs GMG; four downregulated (miR-4712-3p; miR-6752-5p; miR-320d; miR-3614-3p) miRNAs were obtained through the downregulated intersection between control vs OMG and OMG vs GMG. A total of 408 target genes were predicted for the five differentially expressed miRNAs. The mTOR signaling pathway and Rap1 signaling pathway were significantly enriched based on the enrichment results. RT-qPCR findings revealed that for the OMG, the expression of miR-320d, miR-4712-3p and miR-3614-3p was markedly up-/down-regulated as compared to GMG and healthy control group. The AUC for the three miRNAs between OMG and healthy control groups were 0.78, 0.79 and 0.79 respectively; the AUC between OMG and GMG was 0.84.

CONCLUSIONS

The present study identified three novel miRNAs as candidate biomarkers for early-onset OMG patients and it was expected to provide a possibility and a new orientation for serum exosomal miRNAs as OMG diagnostic biomarkers.

Epigenetic Regulation of Autophagy in Bone Metabolism

The skeletal system is crucial for supporting bodily functions, protecting vital organs, facilitating hematopoiesis, and storing essential minerals. Skeletal homeostasis, which includes aspects such as bone density, structural integrity, and regenerative processes, is essential for normal skeletal function. Autophagy, an intricate intracellular mechanism for degrading and recycling cellular components, plays a multifaceted role in bone metabolism. It involves sequestering cellular waste, damaged proteins, and organelles within autophagosomes, which are then degraded and recycled. Autophagy's impact on bone health varies depending on factors such as regulation, cell type, environmental cues, and physiological context. Despite being traditionally considered a cytoplasmic process, autophagy is subject to transcriptional and epigenetic regulation within the nucleus. However, the precise influence of epigenetic regulation, including DNA methylation, histone modifications, and non-coding RNA expression, on cellular fate remains incompletely understood. The interplay between autophagy and epigenetic modifications adds complexity to bone cell regulation. This article provides an in-depth exploration of the intricate interplay between these two regulatory paradigms, with a focus on the epigenetic control of autophagy in bone metabolism. Such an understanding enhances our knowledge of bone metabolism-related disorders and offers insights for the development of targeted therapeutic strategies.

Molecular mechanism of lncRNAs in pathogenesis and diagnosis of auto-immune diseases, with a special focus on lncRNA-based therapeutic approaches

Autoimmune diseases are a diverse set of conditions defined by organ damage due to abnormal innate and acquired immune system responses. The pathophysiology of autoimmune disorders is exceedingly intricate and has yet to be fully understood. The study of long non-coding RNAs (lncRNAs), non-protein-coding RNAs with at least 200 nucleotides in length, has gained significant attention due to the completion of the human genome project and the advancement of high-throughput genomic approaches. Recent research has demonstrated how lncRNA alters disease development to different degrees. Although lncRNA research has made significant progress in cancer and generative disorders, autoimmune illnesses are a relatively new research area. Moreover, lncRNAs play crucial functions in differentiating various immune cells, and their potential relationships with autoimmune diseases have received growing attention. Because of the importance of Th17/Treg axis in auto-immune disease development, in this review, we discuss various molecular mechanisms by which lncRNAs regulate the differentiation of Th17/Treg cells. Also, we reviewed recent findings regarding the several approaches in the application of lncRNAs in the diagnosis and treatment of human autoimmune diseases, as well as current challenges in lncRNA-based therapeutic approaches to auto-immune diseases.

Long noncoding RNA/circular RNA regulates competitive endogenous RNA networks in rheumatoid arthritis: molecular mechanisms and traditional Chinese medicine therapeutic significances

Rheumatoid arthritis (RA) is a systemic and autoimmune disease that is mainly featured abnormal fibroblast-like synoviocyte (FLS) proliferation and inflammatory cell infiltration. Abnormal expression or function of long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) are closely related to human diseases, including RA. There has been increasing evidence showing that in the competitive endogenous RNA (ceRNA) networks, both lncRNA and circRNA are vital in the biological functions of cells. Nevertheless, the exact mechanism of ceRNA in RA remains to be investigated. Herein, we summarized the molecular potencies of lncRNA/circRNA-mediated ceRNA networks in RA, with emphasis on the phenotypic regulation of ceRNA in the progression of RA, including regulation of proliferation, invasion, inflammation and apoptosis, as well as the role of ceRNA in traditional Chinese medicine (TCM) in the treatment of RA. In addition, we also discussed the future direction and potential clinical value of ceRNA in the treatment of RA, which may provide potential reference value for clinical trials of TCM therapy for the treatment of RA.Key messagesLong noncoding RNA/circular RNA can work as the competitive endogenous RNA sponge and participate in the pathogenesis of rheumatoid arthritis.Traditional Chinese medicine and its agents have shown potential roles in the prevention and treatment of rheumatoid arthritis via competitive endogenous RNA.

The long non-coding RNA maternally expressed 3-micorRNA-15a-5p axis is modulated by melatonin and prevents nucleus pulposus cell inflammation and apoptosis

Nucleus pulposus (NP) cell apoptosis is regarded as a critical risk factor for intervertebral disc degeneration (IVDD). Melatonin exerts a protective role on NP cells. The study concentrates on the role and mechanism of lncRNA MEG3 in melatonin-mediated effects on NP cells. An in vitro IVDD model was constructed using IL-1β on human NP cells. qRT-PCR investigated MEG3, miR-15a-5p and PGC-1α mRNA levels in tissues and NP cells. IL-1β-treated NP cells subsequent to transfection, followed by melatonin treatment. NP cell proliferation, viability, apoptosis and inflammatory reactions were assayed. Western blot checked the profiles of PGC-1α, SIRT1 and NF-κB p65. Student's t-test or one-way analysis of variance (ANOVA) followed by Tukey's test was used for statistical tests. As indicated by the data, melatonin weakened NP cell inflammation and apoptosis and enhanced MEG3 expression. MEG3 expression was attenuated in IVDD tissues. MEG3 knockdown impaired the function of melatonin, which was, however, strengthened by miR-15a-5p knockdown. MEG3 targeted miR-15a-5p, which targeted PGC-1α and repressed the PGC-1α/SIRT1 pathway. Collectively, this study has disclosed that the MEG3-miR-15a-5p-PGC-1α/SIRT1 pathway modulated by melatonin can hamper NP cell apoptosis and inflammation elicited by IL-1β.

Downregulation of BIRC2 hinders the progression of rheumatoid arthritis through regulating TRADD

AIM

Rheumatoid arthritis (RA) is a chronic inflammation mediated by an autoimmune response. Baculoviral IAP repeat-containing 2 (BIRC2) and tumor necrosis factor receptor 1-associated death domain protein (TRADD) have been reported to be highly expressed in RA, while their specific roles during RA progression remain unclear. This study aims to explore the specific regulation of BIRC2/TRADD during the progression of RA.

METHODS

C28/I2 cells were stimulated by lipopolysaccharide (LPS) to establish an in vitro RA cellular model. The expression level of BIRC2 and TRADD was examined by quantitative real-time polymerase chain reaction and western blot. Cell Counting Kit-8 and flow cytometry assays were performed to examine cell viability and necroptosis, respectively. The oxidative stress markers were detected using commercial kits, and the pro-inflammatory cytokines were measured by ELISA assay. The interaction between BIRC2 and TRADD was verified by co-immunoprecipitation assay.

RESULTS

BIRC2 and TRADD were discovered to be highly expressed in LPS-mediated C28/I2 cells. BIRC2 knockdown was demonstrated to inhibit LPS-induced cell viability loss, necroptosis, oxidative stress, and inflammation in C28/I2 cells. BIRC2 could interact with TRADD and positively regulate TRADD expression. In addition, the protective role of BIRC2 knockdown against LPS-mediated injuries in C28/I2 cells was partly weakened by TRADD overexpression.

CONCLUSION

In summary, BIRC2 knockdown alleviated necroptosis, oxidative stress, and inflammation in LPS-mediated C28/I2 cells, which might correlate to the regulatory role of TRADD, indicating a novel target for the treatment of RA.

Long noncoding RNA00324 is involved in the inflammation of rheumatoid arthritis by targeting miR-10a-5p via the NF-κB pathway

BACKGROUND

Altered expressions of genes in immune cells and synovial tissues are involved in the pathology of rheumatoid arthritis (RA). Long noncoding RNAs act as competing endogenous RNAs and can cause immune disorders. The goal of this study was to reveal the association between noncoding RNA linc00324 and RA, and a plausible action mechanism was proposed.

METHODS

RT-qPCR was used to evaluate the expression of linc00324 in peripheral blood mononuclear cells isolated from 50 RA patients and 50 healthy controls, and the correlations between linc00324 level and the clinical indicators were analyzed. Flow cytometry was used to characterize CD4⁺ T cells. The effects of linc00324 on cytokine production and cell proliferation of CD4⁺ T cells were evaluated by ELISA assay and Western blot. The interaction between linc00324 and miR-10a-5p was investigated by RNA immunoprecipitation and dual-luciferase assays.

RESULTS

The linc00324 expression was significantly enhanced in RA patients, and linc00324 expression was positively correlated with rheumatoid factor and CD4⁺ T cells. Overexpression of linc00324 promoted CD4⁺ T cells proliferation, and enhanced chemokine MIP-1α secretion and NF-κB phosphorylation level, whereas knockout of linc00324 blocked CD4⁺ T cell proliferation and NF-κB phosphorylation. Overexpression of miR-10a-5p led to the decrease of CD4⁺ T cells proliferation and NF-κB phosphorylation, and reversed the effects of linc00324 on cell proliferation and NF-κB activity.

CONCLUSION

Linc00324 was upregulated in RA and may exaggerate inflammation by targeting miR-10a-5p through NF-κB signaling pathway.

Long non-coding RNAs and rheumatoid arthritis: Pathogenesis and clinical implications

Long non-coding RNAs (lncRNAs) are a class of noncoding RNAs with a length larger than 200 nucleotides that participate in various diseases and biological processes as they can control gene expression by different mechanisms. Rheumatoid arthritis (RA) is an inflammatory autoimmune disorder characterized by symmetrical destructive destruction of distal joints as well as extra-articular involvement. Different studies have documented and proven the abnormal expression of lncRNAs in RA patients. Various lncRNAs have proven potential as biomarkers and targets for diagnosing, prognosis and treating RA. This review will focus on RA pathogenesis, clinical implications, and related lncRNA expressions that help to identify new biomarkers and treatment targets.

Inhibition of Cdc37 Ameliorates Arthritis in Collagen-Induced Arthritis Rats by Inhibiting Synoviocyte Proliferation and Migration Through the ERK Pathway

Rheumatoid arthritis (RA) is a chronic autoimmune disease that can lead to synovial inflammation, pannus formation, cartilage damage, bone destruction, and ultimate disability. Fibroblast-like synoviocytes (FLS) are involved in the pathogenetic mechanism of RA. Cdc37 (cell division cycle protein 37) is regarded as a molecular chaperone involved in various physiological processes such as cell cycle progression, cell proliferation, cell signal transduction, tumorigenesis, and progression. However, the precise role of Cdc37 in the pathogenesis of rheumatoid arthritis (RA) remains uncertain. In our study, we found that Cdc37 expression was upregulated in human rheumatoid synovia in contrast with the normal group. Interestingly, Cdc37 activated the ERK pathway to promote RA-FLS proliferation and migration in vitro. Ultimately, in vivo experiments revealed that silencing of Cdc37 alleviated ankle swelling and cartilage destruction and validated the ERK signaling pathways in vitro findings. Collectively, we demonstrate that Cdc37 promotes the proliferation and migration of RA-FLS by activation of ERK signaling pathways and finally aggravates the progression of RA. These data indicated that Cdc37 may be a novel target for the treatment of RA.

The Common LncRNAs of Neuroinflammation-Related Diseases

Spatio-temporal specific long noncoding RNAs (lncRNAs) play important regulatory roles not only in the growth and development of the brain but also in the occurrence and development of neurologic diseases. Generally, the occurrence of neurologic diseases is accompanied by neuroinflammation. Elucidation of the regulatory mechanisms of lncRNAs on neuroinflammation is helpful for the clinical treatment of neurologic diseases. This paper focuses on recent findings on the regulatory effect of lncRNAs on neuroinflammatory diseases and selects 10 lncRNAs that have been intensively studied to analyze their mechanism action. The clinical treatment status of lncRNAs as drug targets is also reviewed. SIGNIFICANCE STATEMENT: Gene therapies such as clustered regularly interspaced short palindrome repeats technology, antisense RNA technology, and RNAi technology are gradually applied in clinical treatment, and the development of technology is based on a large number of basic research investigations. This paper focuses on the mechanisms of lncRNAs regulation of neuroinflammation, elucidates the beneficial or harmful effects of lncRNAs in neurosystemic diseases, and provides theoretical bases for lncRNAs as drug targets.

Plasma long noncoding RNAs lncDC and THRIL as potential diagnostic markers of adult primary immune thrombocytopenia

INTRODUCTION

Immune thrombocytopenia (ITP) is a common acquired hemorrhagic disease without "gold standard" for the diagnosis, long non-coding RNA (lncRNAs) can participate in regulating gene expression through various mechanisms and may play a role in immune intolerance in ITP. Several previous studies have confirmed that lncRNA lncDC and THRIL are involved in the development of autoimmune diseases. This study investigates the relationship between expression levels of two plasma lncRNAs (lncDC and THRIL) and clinical characteristics of adult primary ITP patients, ascertain their potential applications as diagnostic markers of ITP.

METHODS

We recruited 102 subjects, including 41 ITP patients, 41 healthy controls (HCs) and 20 patients under myelosuppression phase after chemotherapy (MS). qRT-PCR was used to detect the expression of two lncRNAs in the peripheral blood plasma of the three groups. Receiver operating characteristic (ROC) curves were used to test the diagnostic efficacy of lncDC and THRIL in ITP.

RESULTS

The expression level of lncDC was downregulated in ITP patients compared with HCs (p = . 012) and MS (p = .035), whereas THRIL was significantly upregulated (p = .0005, p < . 0001). We further revealed that lncDC has a high sensitivity (78. 05%), while THRIL has a high specificity (97. 56%). The area under the curve (AUC) (0.869, 95% CI: 0.795-0.943, p < .0001) of the ROC curve for this combination increased significantly.

CONCLUSIONS

THRIL and lncDC expression levels were changed in adult ITP patients. The lncRNAs lncDC and THRIL can serve as potential diagnostic markers for adult primary ITP.

Comprehensive overview of microRNA function in rheumatoid arthritis

MicroRNAs (miRNAs), a class of endogenous single-stranded short noncoding RNAs, have emerged as vital epigenetic regulators of both pathological and physiological processes in animals. They direct fundamental cellular pathways and processes by fine-tuning the expression of multiple genes at the posttranscriptional level. Growing evidence suggests that miRNAs are implicated in the onset and development of rheumatoid arthritis (RA). RA is a chronic inflammatory disease that mainly affects synovial joints. This common autoimmune disorder is characterized by a complex and multifaceted pathogenesis, and its morbidity, disability and mortality rates remain consistently high. More in-depth insights into the underlying mechanisms of RA are required to address unmet clinical needs and optimize treatment. Herein, we comprehensively review the deregulated miRNAs and impaired cellular functions in RA to shed light on several aspects of RA pathogenesis, with a focus on excessive inflammation, synovial hyperplasia and progressive joint damage. This review also provides promising targets for innovative therapies of RA. In addition, we discuss the regulatory roles and clinical potential of extracellular miRNAs in RA, highlighting their prospective applications as diagnostic and predictive biomarkers.

A review of current evidence about lncRNA MEG3: A tumor suppressor in multiple cancers

Long non-coding RNA (lncRNA) maternally expressed gene 3 (MEG3) is a lncRNA located at the DLK1-MEG3 site of human chromosome 14q32.3. The expression of MEG3 in various tumors is substantially lower than that in normal adjacent tissues, and deletion of MEG3 expression is involved in the occurrence of many tumors. The high expression of MEG3 could inhibit the occurrence and development of tumors through several mechanisms, which has become a research hotspot in recent years. As a member of tumor suppressor lncRNAs, MEG3 is expected to be a new target for tumor diagnosis and treatment. This review discusses the molecular mechanisms of MEG3 in different tumors and future challenges for the diagnosis and treatment of cancers through MEG3.

lncRNA-mediated synovitis in rheumatoid arthritis: A perspective for biomarker development

Long noncoding RNAs (lncRNAs) are a regulatory class of noncoding RNAs with a wide range of activities such as transcriptional and post-transcriptional regulations. Emerging evidence has demonstrated that various lncRNAs contribute to the initiation and progression of Rheumatoid Arthritis (RA) through distinctive mechanisms. The present study reviews the recent findings on lncRNA role in RA development. It focuses on the involvement of different lncRNAs in the main steps of RA pathogenesis including T cell activation, cytokine dysregulation, fibroblast-like synoviocyte (FLS) activation and joint destruction. Besides, it discusses the current findings on RA diagnosis and the potential of lncRNAs as diagnostic, prognostic and predictive biomarkers in Rheumatology clinic.

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.

Research progress on serological indices and their clinical application in rheumatoid arthritis

BACKGROUND

As a chronic systemic autoimmune disease of undetermined etiology, rheumatoid arthritis (RA) has a complex pathogenesis, which involves multiple proteins and cytokines. The 2010 ACR/EULAR classification criteria facilitate early diagnosis of RA with reduced specificity when compared to the 1987 ACR criteria. Hence, it is imperative to identify novel serological inflammatory indicators and targets, in order to explain the complex regulatory network of RA. The present review discusses the associations of various inflammatory factors with RA and its underlying mechanism. Besides, the review also provides a novel insight into the clinical treatment of RA.

MATERIALS AND METHODS

According to the PRISMA guidelines, databases like Web of Science, Google-Scholar, Pubmed and Scopus were systematically searched for articles from January 1, 2018 to January 1, 2022 using The following 2 keywords: "rheumatoid arthritis", "Inflammatory cytokines", "ILs", "serum amyloid protein A", "matrix metalloproteinase 3", "RANKL", "Glucose-6-phosphoisomerase", "Anti-keratin antibody", "1,25-Dihydroxyvitamin D3".

RESULTS

Indicators like MMPs, ILs, glucose-6-phosphate isomerase (GPI), anti-keratin antibody (AKA) and receptor activator of nuclear factor-κB ligand (RANKL) are the current hotspots in the efficacy research of RA. The present review suggests that ILs are highly expressed in the serum and synovial tissues of RA patients. By targeted inhibition of ILs with inhibitor application, precise RA treatment can be achieved.

CONCLUSIONS

Based on these results, it can be concluded that inflammatory factors have certain guiding significance in the diagnosis and efficacy evaluation of RA. However, the mechanisms of interactions among them are rather complex, which deserve further exploration.

RND3 Transcriptionally Regulated by FOXM1 Inhibits the Migration and Inflammation of Synovial Fibroblasts in Rheumatoid Arthritis Through the Rho/ROCK Pathway

Rheumatoid arthritis (RA) is a systemic immune disease. Rho family GTPase 3 (RND3) has been reported to play an important role in inflammatory diseases. In this study, the expression of RND3 in RA was analyzed by gene chips. After RND3 was overexpressed, cell counting kit-8 assay was to detect the viability of fibroblast-like synovial cells (RA-FLSs). Transwell assays were to appraise the migratory and invasive capacities of RA-FLSs. Enzyme-linked immunosorbent assay (ELISA) and Western blot analysis were to estimate inflammatory response. In addition, MMP3 and MMP9 levels were also tested by ELISA analysis. After forkhead box M1 (FOXM1) was overexpressed, RND3 expression was detected by Western blot. The transcriptional relationship between FOXM1 and RND3 was predicted by HumanTFDB and JASPAR databases. Luciferase reporter and chromatin immunoprecipitation assays verified the binding ability of FOXM1 and RND3. The role of FOXM1/RND3 axis in RA was detected again by functional experiments. Western blot detected the expression of Rho/ROCK pathway-related proteins. RND3 expression was downregulated in RA. Overexpression of RND3 reduced the proliferation, migration, invasion, and inflammation of RA-FLSs. RND3 was inhibited by FOXM1 transcription, and upregulated FOXM1 reduced the inhibitory effect of RND3 overexpression on cell growth and inflammation, which might be associated with the Rho/ROCK pathway. RND3 transcriptionally regulated by FOXM1 inhibited the migration and inflammation of RA-FLSs in RA through the Rho/ROCK pathway.

MicroRNA-122-3p plays as the target of long non-coding RNA LINC00665 in repressing the progress of arthritis

MicroRNAs (miRNAs) play important roles in many diseases, including rheumatoid arthritis (RA). However, the mechanisms underlying the effects of miR-122-3p-3p on RA are not distinct and require further investigation. Patients with RA and healthy controls were recruited to analyze the miR-122-3p levels. The MH7A cells were stimulated with interleukin (IL)-1β to mimic the local inflammation of RA. Cell Counting Kit-8 (CCK-8) and flow cytometry were performed to measure the viability and apoptosis of MH7A cells. Diana tools and TargetScan were used to predict the target relationships. Luciferase reporter assay was used to validate the target relationship. miR-122-3p is downregulated in RA patients and IL-1β-stimulated MH7A cells. miR-122-3p suppresses MH7A cell viability and promotes MH7A cell apoptosis. miR-122-3p targets LINC00665. LINC00665 eliminates the inhibitory effect of miR-122-3p on IL-1β-stimulated MH7A cells. Eukaryotic translation initiation factor 2 alpha kinase 1 (EIF2AK1) targets miR-122-3p. In addition, EIF2AK1 is highly expressed in patients with RA. In addition, EIF2AK1 activates the mTOR signaling pathway. miR-122-3p represses RA progression by reducing cell viability and increasing synoviocyte apoptosis.

Efficacy of DMARDs and methylprednisolone treatment on the gene expression levels of HSPA5, MMD, and non-coding RNAs MALAT1, H19, miR-199a-5p, and miR-1-3p, in patients with rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a systemic autoimmune disease with chronic inflammation characterized by joint damage and even extra-articular involvement. In this study, the gene expression levels of MALAT1, H19 and their possible downstream microRNAs, miR-199a-5p, miR-1-3p, and the predicted targets of these miRNAs, HSPA5 and MMD, were examined.

METHODS

Twenty-five newly diagnosed RA patients and 25 healthy individuals were included. For six months, patients were treated with conventional disease-modifying antirheumatic drugs (DMARDs) and Methylprednisolone (mPRED). Blood samples were obtained from healthy controls and patients (before and after treatment). After RNA extraction, the RT-qPCR technique was used to evaluate the expression level of the studied genes.

RESULTS

Data showed that the expression level of MALAT1, H19, miR-199a-5p, and miR-1-3p was significantly higher in the newly diagnosed patients with RA than the healthy subjects, but the increase in the expression level of HSPA5 and MMD genes in the new cases was not significant compared to healthy controls. After treatment, except for the expression level of lncRNAs, the expression level of miRNAs, HSPA5, and MMD significantly increased. Based on ROC curve analysis of MALAT1, H19, miR-199a-5p and miR-1-3p have a high ability to identify patients from healthy individuals (AUC = 0.986, AUC = 0.995, AUC = 0.855, AUC = 0.675, respectively).

CONCLUSION

MALAT1 and H19 may be candidates as potential biomarkers for the discrimination between RA patients and controls. DMARDs plus mPRED therapy do not have a desirable effect on reducing inflammatory responses and ER stress.

IL-10 inhibits osteoclast differentiation and osteolysis through MEG3/IRF8 pathway

OBJECTIVE

Osteolysis caused by wear particles is the main reason for joint replacement failure. Inhibition of osteoclast differentiation relieves wear particle-induced osteolysis. Our study aimed to explore the effect of lncRNA maternally expressed gene 3 (MEG3) on osteoclast differentiation and wear particle-induced osteolysis, and to improve the potential mechanism of interleukin-10 (IL-10) inhibition on osteoclast differentiation.

METHODS

Polymethylmethacrylate (PMMA) -induced osteolysis mice model and receptor activator of nuclear factor-B ligand (RANKL) -induced osteoclast differentiation model were constructed. Tartrate-resistant acidic phosphatase (TRAP) staining, hematoxylin-eosin (HE) staining, immunohistochemical staining, bone resorption assay, dual-luciferase assay, RNA pull-down assay, RNA immunoprecipitation, and chromatin immunoprecipitation were executed.

RESULTS

MEG3 levels were increased and interferon regulatory factor 8 (IRF8) levels were decreased in PMMA-induced osteolysis mice. IL-10 inhibited RANKL-induced osteoclast differentiation, promoted MEG3 methylation, and inhibited MEG3 expression. Moreover, knockdown of MEG3 inhibited osteoclast differentiation and increased IRF8 levels. Meanwhile, MEG3 combined with signal transducer and activator of transcription 1 (STAT1), STAT1 combined with IRF8, and overexpression of MEG3 inhibited STAT1 binding to IRF8. Further studies have shown that knockdown of MEG3 inhibited osteoclast differentiation and alleviated osteolysis, but knockdown of IRF8 weakened these results.

CONCLUSION

MEG3 regulated the expression of IRF8 by binding to STAT1, thereby affecting osteoclast differentiation and wear particle-induced osteolysis. IL-10 might inhibit osteoclast differentiation by MEG3/IRF8.

Exosomal Dvl3 promoted the aggressive phenotypic transformation of RA-FLS via wnt pathway

OBJECTIVE

This study was performed to explore the function and mechanism of Dvl3 in RA-FLS by exosome intervention.

METHODS

The expression pattern of Dvl3 was examined by IHC, WB, and qPCR. Modified exosomes obtained from culturing supernatant of RA-FLS infected with Dvl3 over expression (OE) lentivirus were administrated to the target RA-FLS. The ability of survival, migration, and the production of inflammatory factor influenced by exosomal Dvl3 were detected by CKK8 kits, Tunel, migration test, qPCR, and enzyme-linked immunosorbent assay (ELISA) respectively; Flow cytometry analysis was conducted to explorer the inflammatory moderate role of exosomes on CD4+ T cells. The possible downstream pathways of Dvl3 were screened by qPCR and WB and verified by double luciferase reporter experiment.

RESULTS

The expression level of Dvl3 was significantly increased in RA and CIA. Exosomes from the OE group could significantly promote cell proliferation activity, migration/invasion ability. The augment of TNF-α, IL-1β, IL-17, and IL-21 was observed in exosomal Dvl3-OE group. Th1 and Th17 cells polarisation and cytokines related were both enhanced by Exosomal Dvl3. Over expression of Dvl3 was accompanied by the significant increase of β-catenin and RhoA activities.

CONCLUSION

This study discovered the high expression of Dvl3 of exosomes derived from RA patients which may possessed the ability to promote phenotypic transformation of RA-FLS through Wnt pathway.

Construction of a ceRNA Network Related to Rheumatoid Arthritis

(1) Background: Rheumatoid arthritis (RA) is a common systemic autoimmune disease affecting many people and has an unclear and complicated physiological mechanism. The competing endogenous RNA (ceRNA) network plays an essential role in the development and occurrence of various human physiological processes. This study aimed to construct a ceRNA network related to RA. (2) Methods: We explored the GEO database for peripheral blood mononuclear cell (PBMC) samples and then analyzed the RNA of 52 samples (without treatment) to obtain lncRNAs (DELs), miRNAs (DEMs), and mRNAs (DEGs), which can be differentially expressed with statistical significance in the progression of RA. Next, a ceRNA network was constructed, based on the DELs, DEMs, and DEGs. At the same time, the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analysis were used to validate the possible function of the ceRNA network. (3) Results: Through our analysis, 389 DELs, 247 DEMs, and 1081 DEGs were screened. After this, a ceRNA network was constructed for further statistical comparisons, including 16 lncRNAs, 1 miRNA, and 15 mRNAs. According to the GO and KEGG analysis, the ceRNA network was mainly enriched in the mTOR pathway, the dopaminergic system, and the Wnt signaling pathway. (4) Conclusions: The novel ceRNA network related to RA that we constructed offers novel insights into and targets for the underlying molecular mechanisms of the mTOR pathway, the dopaminergic system, and the Wnt signaling pathway (both classic and nonclassic pathways) that affect the level of the genetic regulator, which might offer novel ways to treat RA.

Activities and Molecular Mechanisms of Diterpenes, Diterpenoids, and Their Derivatives in Rheumatoid Arthritis

Diterpenes and their derivatives have many biological activities, including anti-inflammatory and immunomodulatory effects. To date, several diterpenes, diterpenoids, and their laboratory-derived products have been demonstrated for antiarthritic activities. This study summarizes the literature about diterpenes and their derivatives acting against rheumatoid arthritis (RA) depending on the database reports until 31 August 2021. For this, we have conducted an extensive search in databases such as PubMed, Science Direct, Google Scholar, and Clinicaltrials.gov using specific relevant keywords. The search yielded 2708 published records, among which 48 have been included in this study. The findings offer several potential diterpenes and their derivatives as anti-RA in various test models. Among the diterpenes and their derivatives, andrographolide, triptolide, and tanshinone IIA have been found to exhibit anti-RA activity through diverse pathways. In addition, some important derivatives of triptolide and tanshinone IIA have also been shown to have anti-RA effects. Overall, findings suggest that these substances could reduce arthritis score, downregulate oxidative, proinflammatory, and inflammatory biomarkers, modulate various arthritis pathways, and improve joint destruction and clinical arthritic conditions, signs, symptoms, and physical functions in humans and numerous experimental animals, mainly through cytokine and chemokine as well as several physiological protein interaction pathways. Taken all together, diterpenes, diterpenoids, and their derivatives may be promising tools for RA management.

Long Noncoding RNAs as Therapeutic Targets

Long noncoding RNAs (lncRNAs) have emerged as critical regulators of cellular functions including maintenance of cellular homeostasis as well as the onset and progression of disease. LncRNAs often exhibit cell-, tissue-, and disease-specific expression patterns, making them desirable therapeutic targets. LncRNAs are commonly targeted using oligonucleotide therapeutics, and advances in oligonucleotide chemistry including C2 ribose sugar modifications such as 2'-fluoro, 2'-O-methyl, and 2-O-methoxyethyl modifications; 2'4'-constrained nucleotides such as locked nucleic acids and constrained 2'-O-ethyl (cEt) nucleotides; and phosphorothioate bonds have dramatically improved efficacy of oligonucleotide therapies. Novel delivery platforms such as viral vectors and nanoparticles have also improved pharmacokinetic properties of oligonucleotides targeting lncRNAs. Accumulating pre-clinical studies have utilized these strategies to therapeutically target lncRNAs and alter progression of many different disease states including Snhg12 and Chast in cardiovascular disease, Mirt2 and HOTTIP in sepsis and autoimmune disease, and Malat1 and HOXB-AS3 in cancer. Emerging oligonucleotide conjugation methods including the use of peptide nucleic acids hold promise to facilitate targeting to specific tissue types. Here, we review recent advances in lncRNA therapeutics and provide examples of how lncRNAs have been successfully targeted in pre-clinical models of disease. Finally, we detail remaining challenges facing the lncRNA field and how advances in delivery platforms and oligonucleotide chemistry might help overcome these barriers to catalyze the translation of pre-clinical studies to successful pharmaceutical development.

LncRNAs and Rheumatoid Arthritis: From Identifying Mechanisms to Clinical Investigation

Rheumatoid arthritis (RA) is a systemic chronic autoinflammatory disease, and the synovial hyperplasia, pannus formation, articular cartilage damage and bone matrix destruction caused by immune system abnormalities are the main features of RA. The use of Disease Modifying Anti-Rheumatic Drugs (DMARDs) has achieved great advances in the therapy of RA. Yet there are still patients facing the problem of poor response to drug therapy or drug intolerance. Current therapy methods can only moderate RA progress, but cannot stop or reverse the damage it has caused. Recent studies have reported that there are a variety of long non-coding RNAs (LncRNAs) that have been implicated in mediating many aspects of RA. Understanding the mechanism of LncRNAs in RA is therefore critical for the development of new therapy strategies and prevention strategies. In this review, we systematically elucidate the biological roles and mechanisms of action of LncRNAs and their mechanisms of action in RA. Additionally, we also highlight the potential value of LncRNAs in the clinical diagnosis and therapy of RA.

Functional Interactions Between lncRNAs/circRNAs and miRNAs: Insights Into Rheumatoid Arthritis

Rheumatoid arthritis (RA) is one of the most common autoimmune diseases that affect synovitis, bone, cartilage, and joint. RA leads to bone and cartilage damage and extra-articular disorders. However, the pathogenesis of RA is still unclear, and the lack of effective early diagnosis and treatment causes severe disability, and ultimately, early death. Accumulating evidence revealed that the regulatory network that includes long non-coding RNAs (lncRNAs)/circular RNAs (circRNAs), micro RNAs (miRNAs), and messenger RNAs (mRNA) plays important roles in regulating the pathological and physiological processes in RA. lncRNAs/circRNAs act as the miRNA sponge and competitively bind to miRNA to regulate the expression mRNA in synovial tissue, FLS, and PBMC, participate in the regulation of proliferation, apoptosis, invasion, and inflammatory response. Thereby providing new strategies for its diagnosis and treatment. In this review, we comprehensively summarized the regulatory mechanisms of lncRNA/circRNA-miRNA-mRNA network and the potential roles of non-coding RNAs as biomarkers and therapeutic targets for the diagnosis and treatment of RA.

lncRNA BZRAP1-AS1 alleviates rheumatoid arthritis by regulating miR-1286/COL5A2 axis

BACKGROUND

Dysregulation of BZRAP1-AS1 was associated with immune statuses of cancer or Alzheimer's disease patients, yet little is known about its role in rheumatoid arthritis.

METHODS

RT-qPCR and western blot were applied to assess the expression of indicated expression. CCK-8 and BrdU proliferation assays were used to measure the proliferation of RA-HFLS. Apoptosis in RA-HFLS was evidenced by the alteration of caspase-3 activity and apoptosis-related factors. ELISA was performed to detect IL-6, IL-1β, and TNF-α level. Luciferase reporter, RIP, and pull-down assays were used to confirm the BZRAP1-AS1/miR-1286/COL5A2 cascade predicted by bioinformatics analysis.

RESULTS

BZRAP1-AS1 and COL5A2 were downregulated in RA tissues and RA-HFLS while miR-1286 was amplified. Overexpression of BZRAP1-AS1 reduced the RA-HFLS proliferation, IL-6, IL-1β, and TNF-α level and induced cell apoptosis while BZRAP1-AS1 silence produced an opposite effect. Overexpression of BZRAP1-AS1 reduced the miR-1286 expression which in turn increased the COL5A2 expression, thereby relieving the excessive proliferation and limited apoptosis in RA-HFLS.

CONCLUSION

Our findings suggested that BZRAP1-AS1 sequestered miR-1286 and reshaped the COL5A2 expression, thereby suppressed RA-HFLS proliferation and inflammation, and triggered cell apoptosis, resulting in the attenuation of RA progression.

Long non-coding RNA cancer susceptibility candidate 2 regulates the function of human fibroblast-like synoviocytes via the microRNA-18a-5p/B-cell translocation gene 3 signaling axis in rheumatoid arthritis

Rheumatoid arthritis (RA) is a perennial inflammatory condition. Preliminary research indicated that long non-coding (lnc)RNA cancer susceptibility candidate 2 (CASC2) was downregulated in the serum of RA patients. Our study was designed to reveal the roles of lncRNA CASC2 in RA and the latent mechanisms underlying its role. Bioinformatics method (Starbase) and dual-luciferase reporter assay revealed that microRNA (miR)-18a-5p directly interacted with lncRNA CASC2. Furthermore, lncRNA CASC2 and miR-18a-5p expression in the serum samples of RA patients and healthy controls were measured via reverse transcription-quantitative PCR. Compared with the healthy subjects, lncRNA CASC2 was downregulated, whereas miR-18a-5p was upregulated in patients with RA. Overexpression of lncRNA CASC2 decreased the viability of human fibroblast-like synoviocytes (HFLSs) and induced apoptosis, as revealed by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and flow cytometry analyses. Furthermore, the Western blotting assay suggested that Bax was upregulated and Bcl-2 was downregulated in lncRNA CASC2 up-regulated HFLSs. Downregulation of tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β, IL-6, matrix metalloproteinase (MMP)1, and MMP3 levels by lncRNA CASC2 up-regulation was determined using enzyme-linked immunosorbent assays (ELISAs). However, HFLSs co-transfected with miR-18a-5p mimic exhibited opposite effects compared with the case for the overexpression of lncRNA CASC2. The aforementioned methods were used to verify that a binding site exists between B-cell translocation gene 3 (BTG3) and miR-18a-5p. The effects of miR-18a-5p inhibitor on HFLSs were reversed by BTG3 silencing. Overall, lncRNA CASC2 alleviated RA by adjusting the miR-18a-5p/BTG3 signaling axis and could serve as a novel therapeutic option for RA.

LncRNA Expression Profiles in Systemic Lupus Erythematosus and Rheumatoid Arthritis: Emerging Biomarkers and Therapeutic Targets

Systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) are two common multisystem autoimmune diseases that share, among others, many clinical manifestations and serological features. The role of long non-coding RNAs (lncRNAs) has been of particular interest in the pathogenesis of autoimmune diseases. Here, we aimed to summarize the roles of lncRNAs as emerging novel biomarkers and therapeutic targets in SLE and RA. We conducted a narrative review summarizing original articles on lncRNAs associated with SLE and RA, published until November 1, 2021. Based on the studies on lncRNA expression profiles in samples (including PBMCs, serum, and exosomes), it was noted that most of the current research is focused on investigating the regulatory mechanisms of these lncRNAs in SLE and/or RA. Several lncRNAs have been hypothesized to play key roles in these diseases. In SLE, lncRNAs such as GAS5, NEAT1, TUG1, linc0949, and linc0597 are dysregulated and may serve as emerging novel biomarkers and therapeutic targets. In RA, many validated lncRNAs, such as HOTAIR, GAS5, and HIX003209, have been identified as promising novel biomarkers for both diagnosis and treatment. The shared lncRNAs, for example, GAS5, may participate in SLE pathogenesis through the mitogen-activated protein kinase pathway and trigger the AMP-activated protein kinase pathway in RA. Here, we summarize the data on key lncRNAs that may drive the pathogenesis of SLE and RA and could potentially serve as emerging novel biomarkers and therapeutic targets in the coming future.

Long Non-coding RNAs in Rheumatology

The last decade has seen an enormous increase in long non-coding RNA (lncRNA) research within rheumatology. LncRNAs are arbitrarily classed as non-protein encoding RNA transcripts that exceed 200 nucleotides in length. These transcripts have tissue and cell specific patterns of expression and are implicated in a variety of biological processes. Unsurprisingly, numerous lncRNAs are dysregulated in rheumatoid conditions, correlating with disease activity and cited as potential biomarkers and targets for therapeutic intervention. In this chapter, following an introduction into each condition, we discuss the lncRNAs involved in rheumatoid arthritis, osteoarthritis and systemic lupus erythematosus. These inflammatory joint conditions share several inflammatory signalling pathways and therefore not surprisingly many commonly dysregulated lncRNAs are shared across these conditions. In the interest of translational research only those lncRNAs which are strongly conserved have been addressed. The lncRNAs discussed here have diverse roles in regulating inflammation, proliferation, migration, invasion and apoptosis. Understanding the molecular basis of lncRNA function in rheumatology will be crucial in fully determining the inflammatory mechanisms that drive these conditions.

Dysregulation of long noncoding RNA MEG3 and NLRC5 expressions in patients with relapsing-remitting multiple sclerosis: is there any correlation?

Long noncoding RNA MEG3 and NLRC5 genes are both involved in the immune system and the regulation of NLRC5 by MEG3 is documented in rheumatoid arthritis. Therefore, we intended to evaluate the association between the expressions of MEG3 and NLRC5 in multiple sclerosis (MS). Forty relapsing and remitting MS (RRMS) patients (20 in each group) and twenty healthy individuals were enrolled. The expression level of MEG3 and NLRC5 was assessed in peripheral blood mononuclear cells. Sub-group analysis demonstrated that the expression level of MEG3 is reduced in the relapse patient group compared to remission and healthy groups (p < 0.001). The expression level of NLRC5 was higher in whole patients compared with healthy controls (p < 0.05). Moreover, a negative correlation was observed between the expression of these two genes (r = -0.73, p < 0.0001). To conclude, our findings showed the dysregulation of MEG3 and NLRC5 expressions in RRMS patients. Also, the converse association of MEG3 and NLRC5 reflects that the role of MEG3 in MS development is probably mediated by modulation of NLRC5.

MicroRNA-4423-3p inhibits proliferation of fibroblast-like synoviocytes by targeting matrix metalloproteinase 13 in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that is increasing in incidence worldwide. RA is regulated by a variety of microRNAs (miRNAs/miR). Moreover, analysis of public data has revealed that miR-4423-3p is significantly downregulated in peripheral blood mononuclear cells of RA patients. This study investigated the role of miR-4423-3p in RA. The levels of miR-4423-3p and matrix metalloproteinase 13 (MMP13) in RA patients and the regulatory relationship between miR-4423-3p and MMP13 were analyzed using public data. A dual-luciferase reporter assay was performed to verify that miR-4423-3p targets MMP13 in human fibroblast-like synoviocyte (HFLS) RA cells (HFLS-RA). Following the overexpression of miR-4423-3p, miR-4423-3p inhibitor, and MMP13 in HFLS-RA, viability, proliferation, cell cycle, apoptosis, and invasion/migration assays were used to detect the effects of miR-4423-3p targeting MMP13 on cell biological processes. The results revealed that miR-4423-3p was downregulated in peripheral blood mononuclear cells of RA patients and MMP13 was upregulated in synovial tissue of RA patients. miR-4423-3p targets the 3' untranslated region of MMP13 and downregulates MMP13 expression. After overexpression of miR-4423-3p, cell proliferation, migration, and invasion were inhibited, the cell cycle was prevented and cell apoptosis was promoted. Overexpression of MMP13 promoted cell proliferation, migration, and invasion, while accelerating the cell cycle process and suppressing apoptosis. The findings indicate that in HFLS-RA cells, overexpression of miR-4423-3p inhibited proliferation, migration, and invasion, and promoted apoptosis by negatively regulating MMP13. The overexpression of miR-4423-3p might be a novel strategy for the treatment of RA.

lncRNA GAS5 suppresses rheumatoid arthritis by inhibiting miR-361-5p and increasing PDK4

Rheumatoid arthritis (RA) is an inflammatory disease that causes hyperplasia of synovial tissue and cartilage destruction. This research was to investigate the effects of lncRNA GAS5/miR-361-5p/PDK4 on rheumatoid arthritis. By qRT-PCR, GAS5 and PDK4 were found to be overexpressed in synovial tissue, fibroblast-like synoviocytes of RA patients and LPS-induced chondrocytes, while the miR-361-5p expression was significantly reduced. GAS5 overexpression resulted in a decrease in the proliferation and Bcl-2 protein expression, and an increase in the Bax protein level. On the contrary, miR-361-5p sponged by GAS5 could accelerate chondrocyte proliferation, inhibit apoptosis. PDK4 targeted by miR-361-5p could inhibit RA, and partially eliminated the effect of miR-361-5p on RA. Our study suggested that GAS5 suppressed RA by competitively adsorbing miR-361-5p to modulate PDK4 expression.

lncRNA MEG3 aggravated neuropathic pain and astrocyte overaction through mediating miR-130a-5p/CXCL12/CXCR4 axis

OBJECTIVE

Long non-coding RNAs (lncRNAs) exert a critical function in mediating neuropathic pain (NP). MEG3, a novel lncRNA, contributes to astrocyte activation and inflammation. However, its role in NP remains unclear.

METHODS

The chronic constriction injury (CCI) method was employed to construct an NP rat model. Astrocyte activation was induced by lipopolysaccharide (LPS). The profiles of MEG3, microRNA (miR)-130a-5p, CXC motif chemokine receptor 12 (CXCL12)/CXC motif chemokine receptor 4 (CXCR4), and the Rac1/NF-κB pathway in CCI rats' spinal cord tissues and astrocytes were monitored by reverse transcription-quantitative PCR (RT-qPCR) and western blot (WB). Pain scores of CCI rats were assessed. Enzyme-linked immunosorbent assay (ELISA) was adopted to monitor neuroinflammation alteration. The glial fibrillary acidic protein (GFAP)-labeled astrocytes were tested by immunohistochemistry (IHC). Bioinformatics, dual-luciferase reporter assay and RNA immunoprecipitation (RIP) were utilized to verify the molecular mechanism between MEG3 and miR-130a-3p.

RESULTS

MEG3, CXCL12 and CXCR4 were overexpressed and miR-130a-5p was knocked down in CCI rats and LPS-induced astrocytes. Up-regulating MEG3 aggravated NP, enhanced inflammatory cytokines interleukin-1β (IL-1β), tumor necrosis factor (TNF)-α, and interleukin-6 (IL-6) expression and release in CCI rats and LPS-induced astrocytes. Up-regulating miR-130-5p repressed LPS-induced inflammation in astrocytes. AS verified by the dual-luciferase reporter assay and RIP assay, MEG3 sponged miR-130a-5p as a competitive endogenous RNA (ceRNA). What's more, miR-130a-5p up-regulation weakened the MEG3-induced proinflammatory effects on LPS-induced astrocytes.

CONCLUSIONS

MEG3 aggravates NP and astrocyte activation via the miR-130a-5p/CXCL12/CXCR4 axis, which is a potential therapeutic target for NP.

LncRNAs as a new regulator of chronic musculoskeletal disorder

Objectives

In recent years, long non‐coding RNAs (lncRNAs) have been found to play a role in the occurrence, progression and prognosis of chronic musculoskeletal disorders.

Design and methods

Literature exploring on PubMed was conducted using the combination of keywords 'LncRNA' and each of the following: 'osteoarthritis', 'rheumatoid arthritis', 'osteoporosis', 'osteogenesis', 'osteoclastogenesis', 'gout arthritis', 'Kashin‐Beck disease', 'ankylosing spondylitis', 'cervical spondylotic myelopathy', 'intervertebral disc degeneration', 'human muscle disease' and 'muscle hypertrophy and atrophy'. For each disorder, we focused on the publications in the last five years (5/1/2016‐2021/5/1, except for Kashin‐Beck disease). Finally, we excluded publications that had been reported in reviews of various musculoskeletal disorders during the last three years. Here, we summarized the progress of research on the role of lncRNA in multiple pathological processes during musculoskeletal disorders.

Results

LncRNAs play a crucial role in regulating downstream gene expression and maintaining function and homeostasis of cells, especially in chondrocytes, synovial cells, osteoblasts, osteoclasts and skeletal muscle cells.

Conclusions

Understanding the mechanisms of lncRNAs in musculoskeletal disorders may provide promising strategies for clinical practice.

Multiple time-point assessment of lncRNA MEG3 shows potential to monitor treatment efficacy in rheumatoid arthritis patients

Background: This study explored the clinical role of lncRNA MEG3 in rheumatoid arthritis (RA) management. Materials & methods: Totally, 191 active RA patients were enrolled, and their lncRNA MEG3 expressions in peripheral blood monoclonal cells were detected. Results: LncRNA MEG3 expression was downregulated, and it negatively correlated with lesion joints, inflammation and disease activity in RA patients. Moreover, lncRNA MEG3 expression was increased during treatment; meanwhile its increment correlated with treatment response and remission. Conclusion: LncRNA MEG3 may serve as a potential biomarker for monitoring treatment efficacy in RA management.

LncRNA ZNF667-AS1 alleviates rheumatoid arthritis by sponging miR-523-3p and inactivating the JAK/STAT signalling pathway

BACKGROUND

Rheumatoid arthritis (RA) is an autoimmune disease, which compromises the synovial membrane resulting in chronic inflammation. Increasing evidence has demonstrated that long non-coding RNAs (lncRNAs) are implicated in the pathogenesis of RA. This study investigated the role of lncRNA ZNF667-AS1 in RA progression.

METHODS

Synovial tissues and fibroblast-like synoviocytes (FLSs) were obtained from patients with RA. Gene expression was measured using RT-qPCR. Chondrocytes were treated with lipopolysaccharide (LPS) to establish in vitro models of OA. Cell counting kit-8 (CCK-8), western blot, and enzyme-linked immunosorbent assay (ELISA) were used to examine the proliferation and inflammatory cytokine production in chondrocytes. Animal models of OA were established in SD rats. Peripheral blood mononuclear cells (PBMCs) were isolated from the OA rats. Flow cytometry was used to measure the changes of the inflammatory T-helper cell 17 (Th17) cells. The relationship between ZNF667-AS1 and miR-523-3p was verified by luciferase reporter assay.

RESULTS

ZNF667-AS1 was downregulated in RA-FLSs and LPS-stimulated chondrocytes. ZNF667-AS1 overexpression significantly promoted cell proliferation and inhibited the production of IL-6, IL-17 and TNF-α in LPS-stimulated chondrocytes. Additionally, ZNF667-AS1 overexpression reduced the generation of CD4 + IL-17+ cells. In mechanism, ZNF667-AS1 acted a sponge for miR-523-3p. MiR-523-3p overexpression reversed the ZNF667-AS1-mediated regulation of cell proliferation and inflammation. Furthermore, miR-523-3p overexpression abolished the inhibitory effects of ZNF667-AS1 on the JAK/STAT signalling activation.

CONCLUSION

ZNF667-AS1 exerts protective effects during RA development by sponging miR-523-3p and inactivating the JAK/STAT signalling.

LncRNA small nucleolar RNA host gene 16 (SNHG16) silencing protects lipopolysaccharide (LPS)-induced cell injury in human lung fibroblasts WI-38 through acting as miR-141-3p sponge

Long noncoding RNA (LncRNA) small nucleolar RNA host gene 16 (SNHG16) is correlated with cell injuries, including pneumonia. However, its role and mechanism remain vague in pneumonia. The interplay among genes was confirmed by dual-luciferase reporter assay, RNA immunoprecipitation, and RNA pull-down assay. SNHG16 and sushi domain containing 2 (SUSD2) were upregulated, and miRNA (miR)-141-3p was downregulated in the serum of acute pneumonia patients and lipopolysaccharide (LPS)-challenged human lung fibroblasts WI-38. LPS induced apoptosis, autophagy, and inflammatory response in WI-38 cells, which was significantly attenuated by SNHG16 knockdown and/or miR-141-3p overexpression. Notably, both SNHG16 and SUSD2 were identified as target genes of miR-141-3p. Besides, the suppressive role of SNHG16 knockdown in LPS-induced in WI-38 cells was partially abolished by miR-141-3p silencing, and the similar inhibition of miR-141-3p overexpression was further blocked by SUSD2 restoration. In conclusion, knockdown of SNHG16 could alleviate LPS-induced apoptosis, autophagy, and inflammation in WI-38 cells partially though the SNHG16/miR-141-3p/SUSD2 pathway.

Promising Therapeutic Targets for Treatment of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a systemic poly-articular chronic autoimmune joint disease that mainly damages the hands and feet, which affects 0.5% to 1.0% of the population worldwide. With the sustained development of disease-modifying antirheumatic drugs (DMARDs), significant success has been achieved for preventing and relieving disease activity in RA patients. Unfortunately, some patients still show limited response to DMARDs, which puts forward new requirements for special targets and novel therapies. Understanding the pathogenetic roles of the various molecules in RA could facilitate discovery of potential therapeutic targets and approaches. In this review, both existing and emerging targets, including the proteins, small molecular metabolites, and epigenetic regulators related to RA, are discussed, with a focus on the mechanisms that result in inflammation and the development of new drugs for blocking the various modulators in RA.

Long Non-coding RNA MEG3 Alleviated Ulcerative Colitis Through Upregulating miR-98-5p-Sponged IL-10

Ulcerative colitis (UC) is a refractory chronic colitis disease with the particularly complex cause. Recently, long noncoding RNAs (lncRNAs) have been reported to be related to the development of UC. LncRNA MEG3 has been proved to play an anti-inflammatory role in a variety of inflammatory diseases, which share similar pathogenesis with UC, indicating the potential involvement of lncRNA MEG3 in UC. This study aims to investigate the functional role and underlying mechanism of lncRNA MEG3 in UC. Gradient concentration of H2O2 (0, 20, 50, 100, and 200 μM) was used to induce Caco-2 damage models in vitro. Cell viability was detected by cell counting kit-8 (CCK-8) assay. LncRNA MEG3, miR-98-5p, and IL-10 levels in H2O2-treated Caco-2 cells were assessed by performing real-time quantitative polymerase chain reaction (RT-qPCR). Moreover, the binding relationship between lncRNA MEG3 and miR-98-5p, as well as the binding relationship between miR-98-5p and IL-10, was validated using dual-luciferase reporter assay. 2, 4, 6-Trinitrobenzenesulfonic acid solution (TNBS) was applied to induce ulcerative colitis in young rats. The body weight, disease activity index (DAI), length and weight of the colons, pathological scores of UC rats, reactive oxygen species (ROS), and inflammatory cytokines were determined to evaluate the effects of lncRNA MEG3 on the progression of UC. Besides, hematoxylin-eosin (HE) staining was exploited to observe histological changes of UC rat colons. In addition, western blotting analysis was also performed to evaluate the apoptosis and pyroptosis-related protein levels. Moreover, lncRNA MEG3, miR-98-5p, and IL-10 levels in UC rat colons were further assessed by RT-qPCR. Meanwhile, IL-10 expression was determined using immunohistochemistry. LncRNA MEG3 and IL-10 levels were distinctly decreased while miR-98-5p was increased in Caco-2 damage models and UC rats. Bioinformatics analysis predicted the binding sites of lncRNA MEG3 to miR-98-5p and miR-98-5p to IL-10. Besides, dual-luciferase reporter assay validated the negative correlation between lncRNA MEG3 and miR-98-5p, miR-98-5p, and IL-10. Overexpressed lncRNA MEG3 reduced. DAI scores and colon weight/length ratio improved UC ulceration. In addition, upregulation of lncRNA MEG3 relieved oxidative stress, inflammatory response, apoptosis, and pyroptosis of UC rat colons. LncRNA MEG3 overexpression alleviates the serve ulceration of UC rat colons by upregulating IL-10 expression via sponging miR-98-5p. To sum up, this study reveals the protective role of lncRNA MEG3 in the development of UC and may provide potential therapeutic targets for UC.

The Expression of Non-Coding RNAs and Their Target Molecules in Rheumatoid Arthritis: A Molecular Basis for Rheumatoid Pathogenesis and Its Potential Clinical Applications

Rheumatoid arthritis (RA) is a typical autoimmune-mediated rheumatic disease presenting as a chronic synovitis in the joint. The chronic synovial inflammation is characterized by hyper-vascularity and extravasation of various immune-related cells to form lymphoid aggregates where an intimate cross-talk among innate and adaptive immune cells takes place. These interactions facilitate production of abundant proinflammatory cytokines, chemokines and growth factors for the proliferation/maturation/differentiation of B lymphocytes to become plasma cells. Finally, the autoantibodies against denatured immunoglobulin G (rheumatoid factors), EB virus nuclear antigens (EBNAs) and citrullinated protein (ACPAs) are produced to trigger the development of RA. Furthermore, it is documented that gene mutations, abnormal epigenetic regulation of peptidylarginine deiminase genes 2 and 4 (PADI2 and PADI4), and thereby the induced autoantibodies against PAD2 and PAD4 are implicated in ACPA production in RA patients. The aberrant expressions of non-coding RNAs (ncRNAs) including microRNAs (miRs) and long non-coding RNAs (lncRNAs) in the immune system undoubtedly derange the mRNA expressions of cytokines/chemokines/growth factors. In the present review, we will discuss in detail the expression of these ncRNAs and their target molecules participating in developing RA, and the potential biomarkers for the disease, its diagnosis, cardiovascular complications and therapeutic response. Finally, we propose some prospective investigations for unraveling the conundrums of rheumatoid pathogenesis.

Astragaloside regulates lncRNA LOC100912373 and the miR‑17‑5p/PDK1 axis to inhibit the proliferation of fibroblast‑like synoviocytes in rats with rheumatoid arthritis

Previous studies have confirmed that astragaloside (AST) exerts a positive effect on alleviating synovial and joint injury in rheumatoid arthritis (RA). However, the precise mechanisms through which AST acts in the treatment of RA remain unclear. Long non-coding RNA (lncRNA) LOC100912373 was identified as a key gene related to RA and has been proven to interact with miR-17-5p, in order to regulate the pyruvate dehydrogenase kinase 1 and protein kinase B axis (PDK1/AKT axis). The present study aimed to determine whether AST may treat RA through the interaction between lncRNA LOC100912373 and the miR-17-5p/PDK1 axis. MTT assays and flow cytometry were used to detect the proliferation and cell cycle progression of AST-treated fibroblast-like synoviocytes (FLSs). The expression of lncRNA LOC100912373 and miR-17-5p, as well as relative the mRNA expression of the PDK1 and AKT genes following AST intervention was detected by reverse transcription-quantitative PCR (RT-qPCR), immunofluorescence and western blot analysis. The results revealed that AST inhibited FLS proliferation, reduced lncRNA LOC100912373 expression levels, increased miR-17-5p expression levels, and decreased the PDK1 and p-AKT expression levels. Additionally, consecutive rescue experiments revealed that AST counteracted the effects of lncRNA LOC100912373 overexpression on FLS proliferation and cell cycle progression. On the whole, the present study demonstrates that AST inhibits FLS proliferation by regulating the expression of lncRNA LOC100912373 and the miR-17-5p/PDK1 axis.

WITHDRAWN: SCARA5 regulated by MEG3/miR-141 axis attenuates proliferation, migration and invasion of bladder cancer

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Dysregulation of lncRNAs in Rheumatoid Arthritis: Biomarkers, Pathogenesis and Potential Therapeutic Targets

Rheumatoid arthritis (RA) is a chronic autoimmune disease of unknown etiology, mainly manifested by persistent abnormal proliferation of fibroblast-like synoviocytes (FLSs), inflammation, synovial hyperplasia and cartilage erosion, accompanied by joint swelling and joint destruction. Abnormal expression or function of long noncoding RNAs (lncRNAs) are closely related to human diseases, including cancers, mental diseases, autoimmune diseases and others. The abnormal sequence and spatial structure of lncRNAs, the disorder expression and the abnormal interaction with the binding protein will lead to the change of gene expression in the way of epigenetic modification. Increasing evidence demonstrated that lncRNAs were involved in the activation of FLSs, which played a key role in the pathogenesis of RA. In this review, the research progress of lncRNAs in the pathogenesis of RA was systematically summarized, including the role of lncRNAs in the diagnosis of RA, the regulatory mechanism of lncRNAs in the pathogenesis of RA, and the intervention role of lncRNAs in the treatment of RA. Furthermore, the activated signal pathways, the role of DNA methylation and other mechanism have also been overview in this review.