Synovial fibroblast-derived exosomal microRNA-106b suppresses chondrocyte proliferation and migration in rheumatoid arthritis via down-regulation of PDK4

Diagnostic and Therapeutic Roles of Extracellular Vesicles and Their Enwrapped ncRNAs in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a systemic inflammatory disease whose precise pathogenesis remains mysterious. The involvement of epigenetic regulation in the pathogenesis of RA is one of the most anticipated findings, among which non-coding RNAs (ncRNAs) hold great application promise as diagnostic and therapeutic biomarkers for RA. Extracellular vesicles (EVs) are a heterogeneous group of nano-sized, membrane-enclosed vesicles that mediate intercellular communication and substance exchange, especially the transfer of ncRNAs from donor cells, thereby regulating the functional activities and biological processes of recipient cells. In light of the significant correlation between EVs, ncRNAs, and RA, we first documented expression levels of EVs and their-encapsulated ncRNAs in RA individuals, and methodically discussed their-implicated signaling pathways and phenotypic changes. The last but not least, we paied special attention to the therapeutic benefits of gene therapy reagents specifically imitating or silencing candidate ncRNAs with exosomes as carriers on RA animal models, and briefly highlighted their clinical application advantage and foreground. In conclusion, the present review may be conducive to a deeper comprehension of the diagnostic and therapeutic roles of EVs-enwrapped ncRNAs in RA, with special emphasis on exosomal ncRNAs, which may offer hints for the monitoring and treatment of RA.

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.

[miRNA Is Involved in the Pathogenesis of Multiple Diseases by Targeting Osteoprotegerin]

As a member of the tumor necrosis factor receptor family, osteoprotegerin (OPG) is highly expressed in adults in the lung, heart, kidney, liver, spleen, thymus, prostate, ovary, small intestines, thyroid gland, lymph nodes, trachea, adrenal gland, the testis, and bone marrow. Together with the receptor activator of nuclear factor-κB (RANK) and the receptor activator of nuclear factor-κB ligand (RANKL), it forms the RANK/RANKL/OPG pathway, which plays an important role in the molecular mechanism of the development of various diseases. MicroRNAs (miRNAs) are a class of endogenous non-coding RNAs performing regulatory functions in eukaryotes, with a size of about 20-25 nucleotides. miRNA genes are transcribed into primary transcripts by RNA polymerase, bind to RNA-induced silencing complexes, identify target mRNAs through complementary base pairing, with a single miRNA being capable of targeting hundreds of mRNAs, and influence the expression of many genes through pathways involved in functional interactions. In recent years, a large number of studies have been done to explore the mechanism of action of miRNA in diseases through miRNA isolation, miRNA quantification, miRNA spectrum analysis, miRNA target detection, in vitro and in vivo regulation of miRNA levels, and other technologies. It was found that miRNA can play a key role in the pathogenesis of osteoporosis, rheumatoid arthritis, and other diseases by targeting OPG. The purpose of this review is to explore the interaction between miRNA and OPG in various diseases, and to propose new ideas for studying the mechanism of action of OPG in diseases.

Exosomes and exosomal miRNAs: A new avenue for the future treatment of rheumatoid arthritis

Rheumatoid arthritis is a chronic systemic autoimmune disease that involves mainly synovitis and joint injury and is one of the main causes of disability. The pathogenesis of rheumatoid arthritis is complicated, and the treatment cycle is long. The traditional methods of inhibiting inflammation and immunosuppression are no longer sufficient for treatment of the disease, so there is an urgent need to seek new treatments. The exocrine microenvironment is a kind of microvesicle with a lipid bilayer membrane structure that can be secreted by most cells in the body. This structure contains cell-specific proteins, lipids and nucleic acids that can transmit this information from one cell to another. To achieve cell-to-cell communication. Exocrine microRNAs can be contained in exocrine cells and can be selectively transferred to target receptor cells via exocrine signaling, thus regulating the physiological function of target cells. This article focuses on the pathological changes that occur during the development of rheumatoid arthritis and the biological regulation of exocrine and exocrine microRNAs in rheumatoid joints. Research on the roles of exocrine and exocrine microRNAs in regulating the inflammatory response, cell proliferation/apoptosis, autophagy, effects on fibroblast-like synoviocytes and immune regulation in rheumatoid arthritis was reviewed. In addition, the challenges faced by this new treatment are discussed.

Fibroblast-like synoviocytes-derived exosomal circFTO deteriorates rheumatoid arthritis by enhancing N6-methyladenosine modification of SOX9 in chondrocytes

BACKGROUND

Rheumatoid arthritis (RA) is a chronic inflammatory disease that causes disability worldwide. Exosomes released by fibroblast-like synoviocytes in RA (RA-FLSs-Exos) play a role in the development of RA, and circular RNAs (circRNAs) are important for RA progression. This study aimed to investigate the molecular mechanisms underlying the effects of RA-FLSs-Exos in RA and identify the potential pathway responsible for these effects.

METHODS

We initially conducted microarray analysis to identify dysregulated circRNAs in exosomes associated with RA. We then co-cultured isolated RA-FLSs-Exos with chondrocytes to examine their role in RA. In vivo experiments were performed using collagen-induced arthritis mouse models, and circFTO knockdown was achieved through intra-articular injection of AAV5 vectors.

RESULTS

Our findings revealed increased expression of circFTO in both RA-FLSs-Exos and synovial tissues from patients with RA. Exosomal circFTO hindered chondrocyte proliferation, migration, and anabolism while promoting apoptosis and catabolism. Mechanistically, we discovered that circFTO facilitates the formation of methyltransferases complex to suppress SRY-related high-mobility group box 9 (SOX9) expression with assistance from YTH domain family 2 (YTHDF2) through an m6A-dependent mechanism. Furthermore, inhibition of circFTO improved symptoms of RA in vivo.

CONCLUSION

Taken together, our study demonstrates that exosomal circFTO derived from FLSs contributes to the progression of RA by targeting SOX9. These findings highlight a promising target for treating RA.

PDK4 inhibits osteoarthritis progression by activating the PPAR pathway

BACKGROUND

Osteoarthritis (OA) is a degenerative joint disease caused by the deterioration of cartilage. However, the underlying mechanisms of OA pathogenesis remain elusive.

METHODS

Hub genes were screened by bioinformatics analysis based on the GSE114007 and GSE169077 datasets. The Sprague-Dawley (SD) rat model of OA was constructed by intra-articular injection of a mixture of papain and L-cysteine. Hematoxylin-eosin (HE) staining was used to detect pathological changes in OA rat models. Inflammatory cytokine levels in serum were measured employing the enzyme-linked immunosorbent assay (ELISA). The reverse transcription quantitative PCR (RT-qPCR) was implemented to assess the hub gene expressions in OA rat models. The roles of PDK4 and the mechanism regulating the PPAR pathway were evaluated through western blot, cell counting kit-8 (CCK-8), ELISA, and flow cytometry assays in C28/I2 chondrocytes induced by IL-1β.

RESULTS

Six hub genes were identified, of which COL1A1, POSTN, FAP, and CDH11 expressions were elevated, while PDK4 and ANGPTL4 were reduced in OA. Overexpression of PDK4 inhibited apoptosis, inflammatory cytokine levels (TNF-α, IL-8, and IL-6), and extracellular matrix (ECM) degradation protein expressions (MMP-3, MMP-13, and ADAMTS-4) in IL-1β-induced chondrocytes. Further investigation revealed that PDK4 promoted the expression of PPAR signaling pathway-related proteins: PPARA, PPARD, and ACSL1. Additionally, GW9662, an inhibitor of the PPAR pathway, significantly counteracted the inhibitory effect of PDK4 overexpression on IL-1β-induced chondrocytes.

CONCLUSION

PDK4 inhibits OA development by activating the PPAR pathway, which provides new insights into the OA management.

Human umbilical cord mesenchymal stem cell-derived exosomes loaded miR-451a targets ATF2 to improve rheumatoid arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic joint inflammation, with synovial fibroblasts (SFs) playing a pivotal role in its pathogenesis. Dysregulation of microRNA (miRNA) expression in SFs contributes to RA development. Exosomes (Exos) have emerged as effective carriers for therapeutic molecules, facilitating miRNA transfer between cells. This study explores the therapeutic potential of Exos derived from human umbilical cord mesenchymal stem cells (hUCMSCs), loaded with miR-451a, to modulate ATF2 expression, aiming to address RA in both in vivo and in vitro settings.

METHODS

In this study, hUCMSC and RA SFs were isolated and identified, and hUCMSC-Exos were extracted and characterized. The influence of hUCMSC-Exos on RA SFs was detected. And hUCMSC-Exos targeting RA SFs was traced. HUCMSCKD-AGO2 was prepared by knocking down AGO2 in hUCMSC. HUCMSCKD-AGO2-Exos was extracted and characterized,and their influence on RA SFs was detected. The miRNA profiles before and after hUCMSC-Exos intervention in RA SFs were mapped to identify differential miRNAs. RT-qPCR was used to verify the differential miRNAs, with hsa-miR-451a finally selected as the target gene. The effect of miR-451a on SFs was detected. The latent binding of miR-451a to activating transcription factor 2 (ATF2) was analyzed. The effect of hUCMSC-ExosmiR-451a on SFs was detected, and the expression of miR-451a and ATF2 was measured by RT-PCR. In vivo, hUCMSC-ExosmiR-451a was injected into the ankle joint of CIA rats, and arthritis index, joint imaging and synovial pathology were assessed. The expression of miR-451a and ATF2 in synovial tissue was detected. Finally, the safety of hUCMSC-ExosmiR-451a in CIA rats was evaluated.

RESULTS

This study revealed that hUCMSC-Exos can inhibit RA SFs proliferation, migration and invasion through miRNAs. High throughput sequencing detected 13 miRNAs that could be transmitted from hUCMSCs to RA SFs via hUCMSC-Exos. miR-451a inhibited RA SFs proliferation, migration and invasion by regulating ATF2. hUCMSC-Exos loaded with miR-451a targeted ATF2 to inhibit RA SFs proliferation, migration and invasion, and improve joint inflammation and imaging findings in CIA rats.

CONCLUSIONS

This study demonstrates that miR-451a carried by hUCMSC-Exos can play a role in inhibiting RA SFs biological traits and improving arthritis in CIA rats by inhibiting ATF2. The findings suggest a promising treatment for RA and provide insights into the mechanism of action of hUCMSC-Exos in RA. Future research directions will continue to explore the potential in this field.

Gut microbiota in pre-clinical rheumatoid arthritis: From pathogenesis to preventing progression

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by progressive polyarthritis that leads to cartilage and bone damage. Pre-clinical RA is a prolonged state before clinical arthritis and RA develop, in which autoantibodies (antibodies against citrullinated proteins, rheumatoid factors) can be present due to the breakdown of immunologic self-tolerance. As early treatment initiation before the onset of polyarthritis may achieve sustained remission, optimize clinical outcomes, and even prevent RA progression, the pre-clinical RA stage is showing the prospect to be the window of opportunity for RA treatment. Growing evidence has shown the role of the gut microbiota in inducing systemic inflammation and polyarthritis via multiple mechanisms, which may involve molecular mimicry, impaired intestinal barrier function, gut microbiota-derived metabolites mediated immune regulation, modulation of the gut microbiota's effect on immune cells, intestinal epithelial cells autophagy, and the interaction between the microbiome and human leukocyte antigen alleles as well as microRNAs. Since gut microbiota alterations in pre-clinical RA have been reported, potential therapies for modifying the gut microbiota in pre-clinical RA, including natural products, antibiotic therapy, fecal microbiota transplantation, probiotics, microRNAs therapy, vitamin D supplementation, autophagy inducer-based treatment, prebiotics, and diet, holds great promise for the successful treatment and even prevention of RA via altering ongoing inflammation. In this review, we summarized current studies that include pathogenesis of gut microbiota in RA progression and promising therapeutic strategies to provide novel ideas for the management of pre-clinical RA and possibly preventing arthritis progression.

PDK4 facilitates fibroblast functions and diabetic wound healing through regulation of HIF-1α protein stability and gene expression

Fibroblast activation disorder is one of the main pathogenic characteristics of diabetic wounds. Orchestrated fibroblast functions and myofibroblast differentiation are crucial for wound contracture and extracellular matrix (ECM) formation. Pyruvate dehydrogenase kinase 4 (PDK4), a key enzyme regulating energy metabolism, has been implicated in modulating fibroblast function, but its specific role in diabetic wounds remains poorly understood. In this study, we investigated the impact of PDK4 on diabetic wounds and its underlying mechanisms. To assess the effect of PDK4 on human dermal fibroblasts (HDFs), we conducted CCK-8, EdU proliferation assay, wound healing assay, transwell assay, flow cytometry, and western blot analyses. Metabolic shifts were analyzed using the Seahorse XF analyzer, while changes in metabolite expression were measured through LC-MS. Local recombinant PDK4 administration was implemented to evaluate its influence on wound healing in diabetic mice. Finally, we found that sufficient PDK4 expression is essential for a normal wound-healing process, while PDK4 is low expressed in diabetic wound tissues and fibroblasts. PDK4 promotes proliferation, migration, and myofibroblast differentiation of HDFs and accelerates wound healing in diabetic mice. Mechanistically, PDK4-induced metabolic reprogramming increases the level of succinate that inhibits PHD2 enzyme activity, thus leading to the stability of the HIF-1α protein, during which process the elevated HIF-1α mRNA by PDK4 is also indispensable. In conclusion, PDK4 promotes fibroblast functions through regulation of HIF-1α protein stability and gene expression. Local recombinant PDK4 administration accelerates wound healing in diabetic mice.

Combining docking, molecular dynamics simulations, AD-MET pharmacokinetics properties, and MMGBSA calculations to create specialized protocols for running effective virtual screening campaigns on the autoimmune disorder and SARS-CoV-2 main protease

The development of novel medicines to treat autoimmune diseases and SARS-CoV-2 main protease (Mpro), a virus that can cause both acute and chronic illnesses, is an ongoing necessity for the global community. The primary objective of this research is to use CoMFA methods to evaluate the quantitative structure-activity relationship (QSAR) of a select group of chemicals concerning autoimmune illnesses. By performing a molecular docking analysis, we may verify previously observed tendencies and gain insight into how receptors and ligands interact. The results of the 3D QSAR models are quite satisfactory and give significant statistical results: Q_loo∧2 = 0.5548, Q_lto∧2 = 0.5278, R∧2 = 0.9990, F-test = 3,101.141, SDEC = 0.017 for the CoMFA FFDSEL, and Q_loo∧2 = 0.7033, Q_lto∧2 = 0.6827, Q_lmo∧2 = 0.6305, R∧2 = 0.9984, F-test = 1994.0374, SDEC = 0.0216 for CoMFA UVEPLS. The success of these two models in exceeding the external validation criteria used and adhering to the Tropsha and Glorbaikh criteria's upper and lower bounds can be noted. We report the docking simulation of the compounds as an inhibitor of the SARS-CoV-2 Mpro and an autoimmune disorder in this context. For a few chosen autoimmune disorder receptors (protein tyrosine phosphatase, nonreceptor type 22 (lymphoid) isoform 1 (PTPN22), type 1 diabetes, rheumatoid arthritis, and SARS-CoV-2 Mpro, the optimal binding characteristics of the compounds were described. According to their potential for effectiveness, the studied compounds were ranked, and those that demonstrated higher molecular docking scores than the reference drugs were suggested as potential new drug candidates for the treatment of autoimmune disease and SARS-CoV-2 Mpro. Additionally, the results of analyses of drug similarity, ADME (Absorption, Distribution, Metabolism, and Excretion), and toxicity were used to screen the best-docked compounds in which compound 4 scaled through. Finally, molecular dynamics (MD) simulation was used to verify compound 4's stability in the complex with the chosen autoimmune diseases and SARS-CoV-2 Mpro protein. This compound showed a steady trajectory and molecular characteristics with a predictable pattern of interactions. These findings suggest that compound 4 may hold potential as a therapy for autoimmune diseases and SARS-CoV-2 Mpro.

Exosomes as Rheumatoid Arthritis Diagnostic Biomarkers and Therapeutic Agents

Rheumatoid arthritis (RA) is a chronic inflammatory joint disorder that causes systemic inflammation, autoimmunity, and joint abnormalities that result in permanent disability. Exosomes are nanosized extracellular particles found in mammals (40–100 nm). They are a transporter of lipids, proteins, and genetic material involved in mammalian cell–cell signaling, biological processes, and cell signaling. Exosomes have been identified as playing a role in rheumatoid arthritis-related joint inflammation (RA). Uniquely functioning extracellular vesicles (EVs) are responsible for the transport of autoantigens and mediators between distant cells. In addition, paracrine factors, such as exosomes, modulate the immunomodulatory function of mesenchymal stem cells (MSCs). In addition to transporting genetic information, exosomes convey miRNAs between cells and have been studied as drug delivery vehicles. In animal models, it has been observed that MSCs secrete EVs with immunomodulatory properties, and promising results have been observed in this area. By understanding the diversity of exosomal contents and their corresponding targets, it may be possible to diagnose autoimmune diseases. Exosomes can be employed as diagnostic biomarkers for immunological disorders. We here discuss the most recent findings regarding the diagnostic, prognostic, and therapeutic potential of these nanoparticles in rheumatoid arthritis and provide an overview of the evidence pertaining to the biology of exosomes in RA.

Plasma exosome miRNA-26b-3p derived from idiopathic short stature impairs longitudinal bone growth via the AKAP2/ERK1/2 axis

BACKGROUND

Currently, the etiology of idiopathic short stature (ISS) is still unclear. The poor understanding of the molecular mechanisms of ISS has largely restricted this strategy towards safe and effective clinical therapies.

METHODS

The plasma exosomes of ISS children were co-cultured with normal human chondrocytes. The differential expression of exosome miRNA between ISS and normal children was identified via high-throughput microRNA sequencing and bioinformatics analysis. Immunohistochemistry, In situ hybridization, RT-qPCR, western blotting, luciferase expression, and gene overexpression and knockdown were performed to reveal the key signaling pathways that exosome miRNA of aberrant expression in ISS children impairs longitudinal bone growth.

RESULTS

Chondrocytes proliferation and endochondral ossification were suppressed after coculture of ISS plasma exosomes with human normal chondrocytes. High-throughput microRNA sequencing and RT-qPCR confirmed that plasma exosome miR-26b-3p was upregulated in ISS children. Meanwhile, exosome miRNA-26b-3p showed a high specificity and sensitivity in discriminating ISS from normal children. The rescue experiment showed that downregulation of miR-26b-3p obviously improved the repression of chondrocyte proliferation and endochondral ossification caused by ISS exosomes. Subsequently, miR-26b-3p overexpression inhibited chondrocyte proliferation and endochondral ossification once again. In situ hybridization confirmed the colocalization of miR-26b-3p with AKAP2 in chondrocytes. In vitro and in vivo assay revealed exosome miRNA-26b-3p impairs longitudinal bone growth via the AKAP2 /ERK1/2 axis.

CONCLUSIONS

This study is the first to confirm that miR-26b-3p overexpression in ISS plasma exosomes leads to disorders in proliferation and endochondral ossification of growth plate cartilage via inhibition of AKAP2/ERK1/2 axis, thereby inducing ISS. This study provides a new research direction for the etiology and pathology of ISS and a new idea for the biological treatment of ISS.

The pyruvate dehydrogenase complex: Life's essential, vulnerable and druggable energy homeostat

Found in all organisms, pyruvate dehydrogenase complexes (PDC) are the keystones of prokaryotic and eukaryotic energy metabolism. In eukaryotic organisms these multi-component megacomplexes provide a crucial mechanistic link between cytoplasmic glycolysis and the mitochondrial tricarboxylic acid (TCA) cycle. As a consequence, PDCs also influence the metabolism of branched chain amino acids, lipids and, ultimately, oxidative phosphorylation (OXPHOS). PDC activity is an essential determinant of the metabolic and bioenergetic flexibility of metazoan organisms in adapting to changes in development, nutrient availability and various stresses that challenge maintenance of homeostasis. This canonical role of the PDC has been extensively probed over the past decades by multidisciplinary investigations into its causal association with diverse physiological and pathological conditions, the latter making the PDC an increasingly viable therapeutic target. Here we review the biology of the remarkable PDC and its emerging importance in the pathobiology and treatment of diverse congenital and acquired disorders of metabolic integration.

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.

Elucidating a fresh perspective on the interplay between exosomes and rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by chronic synovitis and the destruction of bones and joints. Exosomes are nanoscale lipid membrane vesicles originating from multivesicular bodies and are used as a vital means of intercellular communication. Both exosomes and the microbial community are essential in RA pathogenesis. Multiple types of exosomes from different origins have been demonstrated to have effects on various immune cells through distinct mechanisms in RA, which depend on the specific cargo carried by the exosomes. Tens of thousands of microorganisms exist in the human intestinal system. Microorganisms exert various physiological and pathological effects on the host directly or through their metabolites. Gut microbe-derived exosomes are being studied in the field of liver disease; however, information on their role in the context of RA is still limited. Gut microbe-derived exosomes may enhance autoimmunity by altering intestinal permeability and transporting cargo to the extraintestinal system. Therefore, we performed a comprehensive literature review on the latest progress on exosomes in RA and provided an outlook on the potential role of microbe-derived exosomes as emerging players in clinical and translational research on RA. This review aimed to provide a theoretical basis for developing new clinical targets for RA therapy.

Triptolide improves chondrocyte proliferation and secretion via down-regulation of miR-221 in synovial cell exosomes

BACKGROUND

Rheumatoid arthritis (RA), the most common type of inflammatory arthritis, can cause bone damage and disability. Triptolide, a prominent treatment for RA, has satisfactory anti-inflammatory effects. However, the mechanism of action of triptolide in RA remains unknown.

PURPOSE

This study aimed to explore the molecular mechanisms underlying triptolide-mediated improvements in RA and identify the miRNA pathway responsible for these effects.

METHODS

We identified various dysregulated miRNAs associated with RA by mining previously described microarray data and verified and screened these candidates using RT-qPCR. Hematoxylin-eosin staining was then applied to identify pathological changes in the affected joints, and cell counting kit-8 analysis and flow cytometry were employed to examine cell proliferation and apoptosis, respectively. Extracted exosomes were verified using transmission electron microscopy.

RESULTS

Our results revealed that the legs of rats with collagen-induced arthritis presented with obvious swelling and bone damage, a high degree of inflammatory cell infiltration into the synovium, and structural changes to the cartilage. Data mining identified 39 dysregulated miRNAs in these tissues, and RT-qPCR further refined these observations to highlight miR-221 as a potential RA biomarker. Subsequent evaluations revealed that fibroblast-like synovial (FLS) cells secrete Exs carrying dysregulated miR-221 in vitro. These Exs mediate miR-221 levels, inflammation, and TLR4/MyD88 signaling via their fusion with chondrocytes, leading to changes in chondrocyte growth and metabolic factor levels. Additionally, the addition of triptolide impaired miR-221 expression, cell proliferation, inflammatory factors, and the protein levels of TLR4/MyD88 in RA-FLS and promoted the apoptosis of FLS. The therapeutic effect of triptolide on miR-221 Exs was reversed by miR-221 inhibitor in both normal and RA FLS.

CONCLUSION

Our research shows that effective treatment with triptolide is mediated by its regulation of growth and secretory functions of chondrocytes via the inhibition of miR-221 secretion by FLS, providing a new target and natural medicinal candidate for future RA treatments.

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.

Fibronectin-1 is a dominant mechanism for rheumatoid arthritis via the mediation of synovial fibroblasts activity

Rheumatoid arthritis (RA) has a high incidence and adverse effects on patients, thus posing a serious threat to people’s life and health. However, the underlying mechanisms regarding the development of RA are still elusive. Herein, we aimed to evaluate the RA-associated molecular mechanisms using the scRNA-seq technique. We used the GEO database to obtain scRNA-seq datasets for synovial fibroblasts (SFs) from RA cases, and the genes were then analyzed using principal component analysis (PCA) and T-Stochastic Neighbor Embedding (TSNE) analyses. Bioinformatics evaluations were carried out for asserting the highly enriched signaling pathways linked to the marker genes, and the key genes related to RA initiation were further identified. According to the obtained results, 3 cell types (0, 1, and 2) were identified by TSNE and some marker genes were statistically upregulated in cell type 1 than the other cell types. These marker genes predominantly contributed to extracellular matrix (ECM) architecture, collagen-harboring ECM, and ECM structural components, and identified as enriched with PI3K/AKT signaling cascade. Notably, fibronectin-1 (FN-1) has been identified as a critical gene that is strongly linked to the development of SFs and has enormous promise for regulating the onset of RA. Moreover, such an investigation offers novel perspectives within onset/progression of RA, suggesting that FN-1 may be a key therapeutic target for RA therapies.

Knowledge Mapping of Exosomes in Autoimmune Diseases: A Bibliometric Analysis (2002–2021)

Background

Autoimmune diseases (AIDs) are a class of chronic disabling diseases characterized by inflammation and damage to muscles, joints, bones, and internal organs. Recent studies have shown that much progress has been made in the research of exosomes in AIDs. However, there is no bibliometric analysis in this research field. This study aims to provide a comprehensive overview of the knowledge structure and research hotspots of exosomes in AIDs through bibliometrics.

Method

Publications related to exosomes in AIDs from 2002 to 2021 were searched on the web of science core collection (WoSCC) database. VOSviewers, CiteSpace and R package “bibliometrix” were used to conduct this bibliometric analysis.

Results

312 articles from 48 countries led by China and the United States were included. The number of publications related to exosomes in AIDs is increasing year by year. Central South University, Sun Yat Sen University, Tianjin Medical University and University of Pennsylvania are the main research institutions. Frontiers in immunology is the most popular journal in this field, and Journal of Immunology is the most co-cited journal. These publications come from 473 authors among which Ilias Alevizos, Qianjin Lu, Wei Wei, Jim Xiang and Ming Zhao had published the most papers and Clotilde Théry was co-cited most often. Studying the mechanism of endogenous exosomes in the occurrence and development of AIDs and the therapeutic strategy of exogenous exosomes in AIDs are the main topics in this research field. “Mesenchymal stem cells”, “microRNA”, “biomarkers”, “immunomodulation”, and “therapy” are the primary keywords of emerging research hotspots.

Conclusion

This is the first bibliometric study that comprehensively summarizes the research trends and developments of exosomes in AIDs. This information identifies recent research frontiers and hot directions, which will provide a reference for scholars studying exosomes.

Anti-rheumatoid drugs advancements: New insights into the molecular treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is one of more than 100 types of arthritis. This chronic autoimmune disorder affects the lining of synovial joints in about 0.5% of people and may induce severe joints deformity and disability. RA impacts health life of people from all sexes and ages with more prevalence in elderly and women people. Significant improvement has been noted in the last two decades revealing the mechanisms of the development of RA, the improvement of the early diagnosis and the development of new treatment options. Non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids, and disease-modifying antirheumatic drugs (DMARDs) remain the most known treatments used against RA. However, not all patients respond well to these drugs and therefore, new solutions are of immense need to improve the disease outcomes. In the present review, we discuss and highlight the recent findings concerning the different classes of RA therapies including the conventional and modern drug therapies, as well as the recent emerging options including the phyto-cannabinoid and cell- and RNA-based therapies. A better understanding of their mechanisms and pathways might help find a specific target against inflammation, cartilage damage, and reduce side effects in arthritis.

Update on the role of extracellular vesicles in rheumatoid arthritis

Rheumatoid arthritis (RA) is a heterogeneous autoimmune disorder that leads to severe joint deformities, negatively affecting the patient's quality of life. Extracellular vesicles (EVs), which include exosomes and ectosomes, act as intercellular communication mediators in several physiological and pathological processes in various diseases including RA. In contrast, EVs secreted by mesenchymal stem cells perform an immunomodulatory function and stimulate cartilage repair, showing promising therapeutic results in animal models of RA. EVs from other sources, including dendritic cells, neutrophils and myeloid-derived suppressor cells, also influence the biological function of immune and joint cells. This review describes the role of EVs in the pathogenesis of RA and presents evidence supporting future studies on the therapeutic potential of EVs from different sources. This information will contribute to a better understanding of RA development, as well as a starting point for exploring cell-free-based therapies for RA.

Interleukin-17 contributes to Ross River virus-induced arthritis and myositis

Arthritogenic alphaviruses are mosquito-borne viruses that are a major cause of infectious arthropathies worldwide, and recent outbreaks of chikungunya virus and Ross River virus (RRV) infections highlight the need for robust intervention strategies. Alphaviral arthritis can persist for months after the initial acute disease, and is mediated by cellular immune responses. A common strategy to limit inflammation and pathology is to dampen the overwhelming inflammatory responses by modulating proinflammatory cytokine pathways. Here, we investigate the contribution of interleukin-17 (IL-17), a cytokine involved in arthropathies such as rheumatoid arthritis, in the development RRV-induced arthritis and myositis. IL-17 was quantified in serum from RRV-infected patients, and mice were infected with RRV and joints and muscle tissues collected to analyse cellular infiltrates, tissue mRNA, cytokine expression, and joint and muscle histopathology. IL-17 expression was increased in musculoskeletal tissues and serum of RRV-infected mice and humans, respectively. IL-17–producing T cells and neutrophils contributed to the cellular infiltrate in the joint and muscle tissue during acute RRV disease in mice. Blockade of IL-17A/F using a monoclonal antibody (mAb) reduced disease severity in RRV-infected mice and led to decreased proinflammatory proteins, cellular infiltration in synovial tissues and cartilage damage, without affecting viral titers in inflamed tissues. IL-17A/F blockade triggered a shift in transcriptional profile of both leukocyte infiltrates and musculoskeletal stromal cells by downregulating proinflammatory genes. This study highlights a previously uncharacterized role for an effector cytokine in alphaviral pathology and points towards potential therapeutic benefit in targeting IL-17 to treat patients presenting with RRV-induced arthropathy.

Some viruses transmitted by mosquitoes cause painful and debilitating arthritis, which manifests both as an acute form shortly following infection, and a chronic form long after the initial symptoms have subsided. These viruses, termed arboviruses, are difficult to control and there are currently no specific treatments to alleviate the pain and loss of mobility. Arthritis caused by arboviruses shares similarities with a non-infectious, autoimmune form of arthritis called rheumatoid arthritis (RA). In RA, an immune molecule termed interleukin-17, or IL-17, has been shown to drive arthritis and treatments that target or block IL-17 are being developed to treat RA. Here, we asked whether arthritis caused by an arbovirus, Ross River virus (RRV), was also associated with elevated IL-17 in humans and mice. Disease severity in mice was associated with high IL-17 expression in the feet and muscle, and blocking IL-17 using an anti-IL-17 monoclonal antibody ameliorated disease in mice infected with RRV. Our study provides new information on a molecule that is implicated in arthritic inflammation, and could be targeted to treat disease caused by arthritogenic arboviruses.

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.

MiR-144-3p Aggravated Cartilage Injury in Rheumatoid Arthritis by Regulating BMP2/PI3K/Akt Axis

OBJECTIVES

Present study aimed to illustrate the role of miR-144-3p in RA.

METHODS

N1511 chondrocytes were stimulated by IL-1β to mimic RA injury model in vitro. Rats were subjected to injection of type II collagen to establish an in vivo RA model and the arthritis index score was calculated. Cell viability was determined by CCK-8. The expression of cartilage extracellular matrix proteins (Collagen II and Aggrecan) and matrix metalloproteinases protein (MMP-13) were determined by qRT-PCR and western blots. Cell apoptosis was measured by Flow cytometry. ELISA was applied to test the secretion of pro-inflammatory cytokines (IL-1β and TNF-α). Tissue injury and apoptosis were detected by HE staining and TUNEL staining. Interaction of miR-144-3p and BMP2 was verified by dual luciferase assay.

RESULTS

MiR-144-3p was dramatically increased in IL-1β induced N1511 cells. MiR-144-3p depletion elevated cell viability, suppressed apoptosis, pro-inflammatory cytokine releasing, and extracellular matrix loss in IL-1β induced N1511 cells. Moreover, miR-144-3p targeted BMP2 to modulate its expression negatively. Activation of PI3K/Akt signaling compromised inhibition of BMP2 induced aggravated N1511 cell injury with IL-1β stimulation. Inhibition of miR-144-3p alleviated cartilage injury and inflammatory in RA rats.

CONCLUSION

Collectively, miR-144-3p could aggravate chondrocytes injury inflammatory response in RA via BMP2/PI3K/Akt axis.

The non-coding RNA interactome in joint health and disease

Non-coding RNAs have distinct regulatory roles in the pathogenesis of joint diseases including osteoarthritis (OA) and rheumatoid arthritis (RA). As the amount of high-throughput profiling studies and mechanistic investigations of microRNAs, long non-coding RNAs and circular RNAs in joint tissues and biofluids has increased, data have emerged that suggest complex interactions among non-coding RNAs that are often overlooked as critical regulators of gene expression. Identifying these non-coding RNAs and their interactions is useful for understanding both joint health and disease. Non-coding RNAs regulate signalling pathways and biological processes that are important for normal joint development but, when dysregulated, can contribute to disease. The specific expression profiles of non-coding RNAs in various disease states support their roles as promising candidate biomarkers, mediators of pathogenic mechanisms and potential therapeutic targets. This Review synthesizes literature published in the past 2 years on the role of non-coding RNAs in OA and RA with a focus on inflammation, cell death, cell proliferation and extracellular matrix dysregulation. Research to date makes it apparent that 'non-coding' does not mean 'non-essential' and that non-coding RNAs are important parts of a complex interactome that underlies OA and 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.

Exosome: Function and Application in Inflammatory Bone Diseases

In the skeletal system, inflammation is closely associated with many skeletal disorders, including periprosthetic osteolysis (bone loss around orthopedic implants), osteoporosis, and rheumatoid arthritis. These diseases, referred to as inflammatory bone diseases, are caused by various oxidative stress factors in the body, resulting in long-term chronic inflammatory processes and eventually causing disturbances in bone metabolism, increased osteoclast activity, and decreased osteoblast activity, thereby leading to osteolysis. Inflammatory bone diseases caused by nonbacterial factors include inflammation- and bone resorption-related processes. A growing number of studies show that exosomes play an essential role in developing and progressing inflammatory bone diseases. Mechanistically, exosomes are involved in the onset and progression of inflammatory bone disease and promote inflammatory osteolysis, but specific types of exosomes are also involved in inhibiting this process. Exosomal regulation of the NF-κB signaling pathway affects macrophage polarization and regulates inflammatory responses. The inflammatory response further causes alterations in cytokine and exosome secretion. These signals regulate osteoclast differentiation through the receptor activator of the nuclear factor-kappaB ligand pathway and affect osteoblast activity through the Wnt pathway and the transcription factor Runx2, thereby influencing bone metabolism. Overall, enhanced bone resorption dominates the overall mechanism, and over time, this imbalance leads to chronic osteolysis. Understanding the role of exosomes may provide new perspectives on their influence on bone metabolism in inflammatory bone diseases. At the same time, exosomes have a promising future in diagnosing and treating inflammatory bone disease due to their unique properties.

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.

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.

The emerging roles of exosomes in autoimmune diseases, with special emphasis on microRNAs in exosomes

Autoimmune diseases include rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), systemic vasculitis, dermatomyositis, systemic sclerosis (SSc), mixed connective tissue disease, autoimmune hemolytic anemia, autoimmune thyroiditis (AITD) and ulcerative colitis. Exosomes exist in body fluids, including blood, saliva, urine, cerebrospinal fluid and milk. They are mainly derived from the invagination of intracellular lysosomal particles, which are released into the extracellular matrix after fusion of the outer membrane of the exosomes with the cell membrane. Exosomes mediate intercellular communication and regulate the biological activity of receptor cells by carrying proteins, nucleic acids and lipids. Evidences show that exosomes are involved in the pathogenesis of various autoimmune diseases. In view of the important roles of exosomes in autoimmune diseases, this work systematically reviewed the effects of exosomes on the pathogenesis of autoimmune diseases, especially the regulatory roles of exosome derived microRNAs (miRNAs) in the pathogenesis of RA, SLE, dermatomyositis, SSc, AITD and ulcerative colitis. The review of the roles of exosomes in autoimmune diseases will help to clarify the pathogenesis of these diseases and explore new diagnostic markers and therapeutic targets.

Extracellular Vesicles in Rheumatoid Arthritis and Systemic Lupus Erythematosus: Functions and Applications

In the last two decades, extracellular vesicles (EVs) have aroused wide interest among researchers in basic and clinical research. EVs, small membrane vesicles are released by almost all kinds of cells into the extracellular environment. According to many recent studies, EVs participate in immunomodulation and play an important role in the pathogenesis of autoimmune diseases. In addition, EVs have great potential in the diagnosis and therapy of autoimmune diseases. Here, we reviewed the latest research advances on the functions and mechanisms of EVs and their roles in the pathogenesis, diagnosis, and treatment of rheumatoid arthritis and systemic lupus erythematosus.