miR-145-5p Increases Osteoclast Numbers In Vitro and Aggravates Bone Erosion in Collagen-Induced Arthritis by Targeting Osteoprotegerin

Updates on the Pathophysiology and Therapeutic Potential of Extracellular Vesicles with Focus on Exosomes in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an incurable autoimmune disease with high morbidity and socioeconomic burden. Advances in therapeutics have improved patients' quality of life, however due to the complex disease pathophysiology and heterogeneity, 30% of patients do not respond to treatment. Understanding how different genetic and environmental factors contribute to disease initiation and development as well as uncovering the interactions of immune components is key to the implementation of effective and safe therapies. Recently, the role of extracellular vesicles (EVs) in RA development and possible treatment has been an area of interest. EVs are small lipid-bound entities, often containing genetic material, proteins, lipids and amino acids, facilitating paracrine intercellular communication. They are secreted by all cells, and it is believed that they possess regulatory functions due to high complexity and functional diversity. Although it has been shown that EVs participate in RA pathophysiology, through immune modulation, their exact role remains elusive. Furthermore, EVs could be a promising therapeutic agent in various diseases including RA, due to their biocompatibility, low toxicity and possible manipulation, but further research is required in this area. This review provides a comprehensive discussion of disease pathophysiology and summarizes the latest knowledge regarding the role and therapeutic potential of EVs in RA.

The sacroiliac joint: An original and highly sensitive tool to highlight altered bone phenotype in murine models of skeletal disorders

Bone disorders may affect the skeleton in different ways, some bones being very impaired and others less severely. In translational studies using murine models of human skeletal diseases, the bone phenotype is mainly evaluated at the distal femur or proximal tibia. The sacroiliac joint (SIJ), which connects the spine to the pelvis, is involved in the balanced transfer of mechanical energy from the lumbar spine to the lower extremities. Because of its role in biomechanical stress, the SIJ is a region of particular interest in various bone diseases. Here we aimed to characterize the SIJ in several murine models to develop a highly reliable tool for studying skeletal disorders. We performed a 12-month in vivo micro-computed tomography (micro-CT) follow-up to characterize the SIJ in wild-type (WT) C57BL/J6 mice and compared the bone microarchitecture of the SIJ and the distal femur at 3 months by micro-CT and histology. To test the sensitivity of our methodology, the SIJ and distal femur were evaluated at 3 and 6 months, in 2 murine models of skeletal disorder, X-linked hypophosphatemia (Hyp mice) and HLA-B27 transgenic mice and compared to WT mice. A multimodal analysis was performed, using a combination of microCT and histological analysis. With the Hyp model, the SIJ displayed more bone microarchitecture alterations than the distal femur. Hyp mice showed a significant reduction in trabecular bone at both the distal femur and sacral slope as compared with WT mice, with a significant positive correlation between trabecular bone parameters of the distal femur and sacral side of the SIJ. Furthermore, trabecular bone parameters (Bone Volume/Total Volume (BV/TV), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), trabecular number (Tb.N), trabecular pattern factor (Tb.Pf)) were significantly increased compared to femoral parameters at the SIJ. The sacral articular cortical bone, which is indicative of osteoarticular lesions, was altered in Hyp mice. Interestingly, in accordance to previous studies, HLA-B27 transgenic mice did not show any osteoarticular lesions as compared with WT mice. Cortical bone parameters (thickness, porosity), as well as scoring performed with double blinding, did not show difference between the 2 genotypes. The characterization and evaluation of the SIJ surface appears very sensitive to emphasize alterations of bone and joint. The SIJ may represent a valuable tool to investigate both bone and local osteoarticular alterations in murine models of skeletal disorders and might be a relevant site for assessing the response to treatment of chronic bone diseases.

Efficacy of HDAC inhibitors and epigenetic modulation in the amelioration of synovial inflammation, cellular invasion, and bone erosion in rheumatoid arthritis pathogenesis

Rheumatoid arthritis (RA), an auto-immune disorder affected 1 % of the population around the globe. The pathophysiology of RA is highly concerted process including synovial hyperplasia, pannus formation, bone erosion, synovial cell infiltration in joints, and cartilage destruction. However, recent reports suggest that epigenetics play a pivotal role in the formation and organization of immune response in RA. Particularly, altered DNA methylation and impaired microRNA (miRNA) were detected in several immune cells of RA patients, such as T regulatory cells, fibroblast-like synoviocytes, and blood mononuclear cells. All these processes can be reversed by regulating the ubiquitous or tissue-based expression of histone deacetylases (HDACs) to counteract and terminate them. Hence, HDAC inhibitors (HDACi) could serve as highly potent anti-inflammatory regulators in the uniform amelioration of inflammation. Therefore, this review encompasses the information mainly focussing on the epigenetic modulation in RA pathogenesis and the efficacy of HDACi as an alternative therapeutic option for RA treatment. Overall, these studies have reported the targeting of HDAC1, 2 & 6 molecules would attenuate synoviocyte inflammation, cellular invasion, and bone erosion. Further, the inhibitors such as trichostatin A, suberoyl bis-hydroxamic acid, suberoyl anilide hydroxamic acid, and other compounds are found to attenuate synovial inflammatory immune response, clinical arthritis score, paw swelling, bone erosion, and cartilage destruction. Insight to view this, more clinical studies are required to determine the efficacy of HDACi in RA treatment and to unravel the underlying molecular mechanisms.

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

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

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.

MiR-145-5p restrains chondrogenic differentiation of synovium-derived mesenchymal stem cells by suppressing TLR4

Osteoarthritis (OA) is a progressive degeneration of articular cartilage with involvement of synovial membrane, and subchondral bone. Recently, cell-based therapies, including the application of stem cells such as mesenchymal stem cells (MSCs), have been introduced for restoration of the articular cartilage. Toll-like receptors (TLRs) were reported to participate in OA progression and MSC chondrogenesis. Here, the role and molecular mechanism of toll like receptor 4 (TLR4) in chondrogenic differentiation of synovium-derived MSCs (SMSCs) were investigated. Molecular markers (CD44, CD90, CD45 and CD14) on SMSC surfaces were identified by flow cytometry. Multi-potential differentiation capacities of SMSCs for chondrogenesis, adipogenesis and osteogenesis were examined by Alcian blue, oil red O and Alizarin red staining, respectively. TLR4 and miR-145-5p levels in SMSCs were assessed using RT-qPCR. The protein expression of TGFB3, Col II, SOX9 and Aggrecan in SMSCs was tested by western blotting. Cytokine secretions were analyzed with ELISA for IL-1β and IL-6. Intracellular NAD⁺ content and NAD⁺/NADH ratio were assessed. The interaction between miR-145-5p and TLR4 was confirmed by RNA pulldown and luciferase reporter assays. In this study, SMSCs were identified to have immunophenotypic characteristics of MSCs. TLR4 knockdown inhibited chondrogenic and osteogenic differentiation of SMSCs. Mechanistically, TLR4 was targeted by miR-145-5p in SMSCs. Moreover, TLR4 elevation offset the inhibitory impact of miR-145-5p upregulation on chondrogenic differentiation of SMSCs. Overall, miR-145-5p restrains chondrogenesis of SMSCs by suppressing TLR4.

Effect of Anti-Osteoporotic Treatments on Circulating and Bone MicroRNA Patterns in Osteopenic ZDF Rats

Bone fragility is an adverse outcome of type 2 diabetes mellitus (T2DM). The underlying molecular mechanisms have, however, remained largely unknown. MicroRNAs (miRNAs) are short non-coding RNAs that control gene expression in health and disease states. The aim of this study was to investigate the genome-wide regulation of miRNAs in T2DM bone disease by analyzing serum and bone tissue samples from a well-established rat model of T2DM, the Zucker Diabetic Fatty (ZDF) model. We performed small RNA-sequencing analysis to detect dysregulated miRNAs in the serum and ulna bone of the ZDF model under placebo and also under anti-sclerostin, PTH, and insulin treatments. The dysregulated circulating miRNAs were investigated for their cell-type enrichment to identify putative donor cells and were used to construct gene target networks. Our results show that unique sets of miRNAs are dysregulated in the serum (n = 12, FDR < 0.2) and bone tissue (n = 34, FDR < 0.2) of ZDF rats. Insulin treatment was found to induce a strong dysregulation of circulating miRNAs which are mainly involved in metabolism, thereby restoring seven circulating miRNAs in the ZDF model to normal levels. The effects of anti-sclerostin treatment on serum miRNA levels were weaker, but affected miRNAs were shown to be enriched in bone tissue. PTH treatment did not produce any effect on circulating or bone miRNAs in the ZDF rats. Altogether, this study provides the first comprehensive insights into the dysregulation of bone and serum miRNAs in the context of T2DM and the effect of insulin, PTH, and anti-sclerostin treatments on circulating miRNAs.

Regulation of osteoclast-mediated bone resorption by microRNA

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

miRNAs as Biomarkers and Possible Therapeutic Strategies in Rheumatoid Arthritis

Within the past years, more and more attention has been devoted to the epigenetic dysregulation that provides an additional window for understanding the possible mechanisms involved in the pathogenesis of autoimmune rheumatic diseases. Rheumatoid arthritis (RA) is a heterogeneous disease where a specific immunologic and genetic/epigenetic background is responsible for disease manifestations and course. In this field, microRNAs (miRNA; miR) are being identified as key regulators of immune cell development and function. The identification of disease-associated miRNAs will introduce us to the post-genomic era, providing the real probability of manipulating the genetic impact of autoimmune diseases. Thereby, different miRNAs may be good candidates for biomarkers in disease diagnosis, prognosis, treatment and other clinical applications. Here, we outline not only the role of miRNAs in immune and inflammatory responses in RA, but also present miRNAs as diagnostic/prognostic biomarkers. Research into miRNAs is still in its infancy; however, investigation into these novel biomarkers could progress the use of personalized medicine in RA treatment. Finally, we discussed the possibility of miRNA-based therapy in RA patients, which holds promise, given major advances in the therapy of patients with inflammatory arthritis.

Gingival crevicular fluid microRNA associations with periodontitis

PURPOSE

The present study was performed to assess the associations of gingival crevicular fluid (GCF) microRNAs miR-140-3p, miR-145-5p, miR-146a-5p, and miR-195-5p with periodontitis (PD) and to evaluate the possible influence of rheumatoid arthritis (RA) in this context.

METHOD

GCF samples were collected from 134 individuals with PD and 76 periodontally healthy individuals, with or without RA. After miRNA extraction from GCF, the levels of miR-140-3p, miR-145-5p, miR-146a-5p, and miR-195-5p were assessed using RT-qPCR.

RESULTS

MiR-146a-5p levels were significantly lower among the patients with PD than among the healthy individuals (P < 0.001) and negatively correlated with PD severity based on PD stage and periodontal outcome parameters (P < 0.05). Patients with severe PD had higher GCF levels of miR-140-3p and miR-145-5p than did periodontally healthy individuals (P < 0.05). Significant AUC values for diagnosis of severe PD were revealed for miR-140-3p (AUC = 0.614, P = 0.022), miR-145-5p (AUC = 0.621, P = 0.016) and miR-146a-5p (AUC = 0.702, P < 0.001). Combination of the aforementioned miRNAs increased the diagnostic performance (AUC = 0.709, P < 0.001).

CONCLUSION

It was demonstrated that miR-140-3p, miR-145-5p and miR-146a-5p were associated with PD and would be potentially effective for GCF-based non-invasive periodontitis diagnostics in patients with and without RA.

Kartogenin Promotes the BMSCs Chondrogenic Differentiation in Osteoarthritis by Down-Regulation of miR-145-5p Targeting Smad4 Pathway

BACKGROUND

Transplantation of mesenchymal stem cells (MSCs) is a potential therapeutic strategy for cartilage degeneration of osteoarthritis (OA). But controlling chondrogenic differentiation of the implanted MSCs in the joints remains a challenge. The role of kartogenin (KGN) for chondrogenesis of MSCs has been widely reported, however, the mechanism of chondrogenesis has not been elucidated in OA.

METHODS

In this study, we investigated the miR-145-5p, TGF-β, Samd4, and p-stat3/stat3 expression in cartilage of OA patients and bone marrow mesenchymal stem cells (BMSCs) treated with KGN or miR-145-5p inhibitor. In addition, the cell proliferation and chondrogenic differentiation in vitro and in vivo of BMSCs treated with KGN was also detected.

RESULTS

In OA patients, the expression of miR-145-5p was up-regulated, and the expression of TGF-β, Samd4, and p-stat3/stat3 was inhibited. When the BMSCs treated with miR-145-5p inhibitor, the expression of TGF-β, Samd4, and p-stat3/stat3 was also significantly up-regulated. KGN-treated BMSCs had better proliferation and chondrogenic differentiation by up-regulating the expression of Sox 9, Col-2a1, aggrecan in vitro and in OA by down-regulation of miR-145-5p targeting Smad4 pathway. Moreover, intra-articular injection of KGN-treated BMSCs had a better pain relief effect in OA.

CONCLUSION

The double effect on cartilage protection and pain relief indicates a great potential of intra-articular injection of KGN-treated BMSCs for the treatment of OA.

CD146 Delineates an Interfascicular Cell Sub-Population in Tendon That Is Recruited during Injury through Its Ligand Laminin-α4

The interfascicular matrix (IFM) binds tendon fascicles and contains a population of morphologically distinct cells. However, the role of IFM-localised cell populations in tendon repair remains to be determined. The basement membrane protein laminin-α4 also localises to the IFM. Laminin-α4 is a ligand for several cell surface receptors, including CD146, a marker of pericyte and progenitor cells. We used a needle injury model in the rat Achilles tendon to test the hypothesis that the IFM is a niche for CD146+ cells that are mobilised in response to tendon damage. We also aimed to establish how expression patterns of circulating non-coding RNAs alter with tendon injury and identify potential RNA-based markers of tendon disease. The results demonstrate the formation of a focal lesion at the injury site, which increased in size and cellularity for up to 21 days post injury. In healthy tendon, CD146+ cells localised to the IFM, compared with injury, where CD146+ cells migrated towards the lesion at days 4 and 7, and populated the lesion 21 days post injury. This was accompanied by increased laminin-α4, suggesting that laminin-α4 facilitates CD146+ cell recruitment at injury sites. We also identified a panel of circulating microRNAs that are dysregulated with tendon injury. We propose that the IFM cell niche mediates the intrinsic response to injury, whereby an injury stimulus induces CD146+ cell migration. Further work is required to fully characterise CD146+ subpopulations within the IFM and establish their precise roles during tendon healing.

miR-9-5p promotes wear-particle-induced osteoclastogenesis through activation of the SIRT1/NF-κB pathway

To explore the potential function of miR-9-5p in wear-particle-induced osteoclastogenesis, we examined the expression of SIRT1 and miR-9-5p in particle-induced osteolysis (PIO) mice calvariae and polyethylene (PE)-induced RAW 264.7 cells and found that SIRT1 expression was downregulated while miR-9-5p expression was upregulated in both models. We then verified that miR-9-5p targets SIRT1. miR-9-5p was found to promote PE-induced osteoclast formation from RAW 264.7 cells by tartrate-resistant acid phosphatase staining and detection of osteoclast markers, and miR-9-5p activation of the SIRT1/NF-kB signaling pathway was found in cells by detecting the expression of SIRT1/NF-kB pathway-related proteins and rescue assays. In conclusion, we found that miR-9-5p activated the SIRT1/NF-κB pathway to promote wear-particle-induced osteoclastogenesis. miR-9-5p may be a useful therapeutic target for PIO remission and treatment.

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.

MicroRNA-26b-5p alleviates murine collagen-induced arthritis by modulating Th17 cell plasticity

Rheumatoid arthritis (RA) is a chronic autoimmune disease, and the abnormal differentiation of IL-17-producing T helper (Th17) cells is an important factor in the pathogenesis. Previous studies have shown that microRNAs (miRNAs, miR) act as key regulators of Th17 cells. However, the effects of miRNAs on Th17 cell differentiation and plasticity in RA are not clear. In this study, not only low miR-26b-5p expression and high IL-17A level were observed in the peripheral blood of RA patients, but also the negative correlation between miR-26b-5p and IL-17A was explored. The changes in collagen-induced arthritis (CIA) mice were consistent with those in RA patients. The results of in vitro experiments showed that miR-26b-5p mainly inhibited the initial differentiation of Th17 cells but did not impact the differentiation of induced-Treg into Th17-like cells. Meanwhile, miR-26b-5p mimics treatment alleviated inflammatory responses and reduced Th17 proportion in CIA mice. These results indicated that miR-26b-5p could alleviate the development of mice CIA by inhibiting the excessive Th17 cells, and that miR-26b-5p could modulate the plasticity of Th17 cell differentiation in RA, mainly block the initial differentiation. This may provide a novel strategy for the clinical treatment of RA.

Circulating miRNAs in bone health and disease

microRNAs have evolved as important regulators of multiple biological pathways essential for bone homeostasis, and microRNA research has furthered our understanding of the mechanisms underlying bone health and disease. This knowledge, together with the finding that active or passive release of microRNAs from cells into the extracellular space enables minimal-invasive detection in biofluids (circulating miRNAs), motivated researchers to explore microRNAs as biomarkers in several pathologic conditions, including bone diseases. Thus, exploratory studies in cohorts representing different types of bone diseases have been performed. In this review, we first summarize important molecular basics of microRNA function and release and provide recommendations for best (pre-)analytical practices and documentation standards for circulating microRNA research required for generating high quality data and ensuring reproducibility of results. Secondly, we review how the genesis of bone-derived circulating microRNAs via release from osteoblasts and osteoclasts could contribute to the communication between these cells. Lastly, we summarize evidence from clinical research studies that have investigated the clinical utility of microRNAs as biomarkers in musculoskeletal disorders. While previous reviews have mainly focused on diagnosis of primary osteoporosis, we have also included studies exploring the utility of circulating microRNAs in monitoring anti-osteoporotic treatment and for diagnosis of other types of bone diseases, such as diabetic osteopathy, bone degradation in inflammatory diseases, and monogenetic bone diseases.

Circulating miR-145 as a marker of therapeutic response to anti-TNF therapy in patients with ankylosing spondylitis

Circulating miRNAs appear promising therapeutic and prognostic biomarkers. We aimed to investigate the predictive value of circulating miRNAs on the disease outcome following anti-TNF therapy in patients with ankylosing spondylitis (AS). Our study included 19 AS patients assessed at baseline (M0), after three (M3) and twelve months (M12) of therapy. Total RNA was isolated from plasma. A comprehensive analysis of 380 miRNAs using TaqMan Low Density Array (TLDA) was followed by a single assay validation of selected miRNAs. All AS patients had high baseline disease activity and an excellent response to anti-TNF therapy at M3 and M12. TLDA analysis revealed the dysregulation of 17 circulating miRNAs, including miR-145. Single assay validation confirmed that miR-145 is significantly downregulated at M3 compared to baseline. The decrease in the levels of miR-145 from M0 to M3 negatively correlated with the change in BASDAI from M0 to M3; and positively correlated with disease activity improvement from M3 to M12 as per BASDAI and ASDAS. The predictive value of the early change in miR-145 and levels of miR-145 at M3 were further validated by Receiver operating curves analysis. We show thatthe early change in circulating miR-145 may be a predictor for the future outcome ofAS patients treated with TNF inhibitors. Patients with a more significant decrease in miR-145 levels may show further significant improvement of disease activity after 12 months. Monitoring the expression of miR-145 in plasma in AS patients may, therefore, influence our therapeutic decision-making.

The Potential Importance of MicroRNAs as Novel Indicators How to Manage Patients with Juvenile Idiopathic Arthritis More Effectively

Small, noncoding sequences of ribonucleic acid called microRNAs (miRNAs, miR) are functioning as posttranscriptional regulators of gene expression. As they draw increasing attention of rheumatologists, there is a growing body of evidence concerning specific molecules that may affect the long-term care of patients with inflammatory arthritides. Findings involving children with juvenile idiopathic arthritis (JIA) are still limited though. The aim of the study was to browse the available data on microRNAs which may be utilized as potential biomarkers helpful in diagnosing and monitoring JIA patients. The review contains a brief summary on the most studied sequences: miR-16, miR-125a-5p, miR-146a, miR-155, and miR-223. It is complemented with other miRNAs possibly relevant for JIA (miR-145, miR-23b, miR-27a, and miR-204) and discussion on challenges for using miRNAs in pediatric rheumatology (particularly, issues regarding specificity of biomarkers and measurements involving synovial fluid).

Comprehensive evaluation of differential long non-coding RNA and gene expression in patients with cartilaginous endplate degeneration of cervical vertebra

Long non-coding RNAs (lncRNAs) are emerging as key regulators in gene expression; however, little is currently known regarding their role in cartilaginous endplate (CE) degeneration (CED) of cervical vertebra. The present study aimed to investigate the expression levels of lncRNAs and analyze their potential functions in CED of cervical vertebra in patients with cervical fracture and cervical spondylosis. Human competitive endogenous RNA (ceRNA) array was used to analyze lncRNA and mRNA expression levels in CE samples from patients with cervical fracture and cervical spondylosis, who received anterior cervical discectomy and fusion. Differentially expressed lncRNAs (DELs) or differentially expressed genes (DEGs) were identified and functionally analyzed, using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. An lncRNA-microRNA(miRNA)-mRNA ceRNA regulatory network was constructed based on the DELs and DEGs, and the ceRNA network was visualized using Cytoscape 3.7.2 software. In total, one downregulated mRNA, one upregulated miRNA and five downstream regulated lncRNAs were identified using reverse transcription-quantitative PCR in CED and healthy CE samples. A total of 369 lncRNAs and 246 mRNAs were identified as differentially expressed in CE. The GO and KEGG analyses demonstrated that the majority of GO and KEGG enrichments were associated with CED. Furthermore, a ceRNA network was established, including 168 putative miRNA response elements, 189 upregulated and 37 downregulated lncRNAs and 47 upregulated and 10dow regulated DEGs. The present study analyzed the function of DEGs in the ceRNA network and filtered out the same items as in DEG-function enrichment analysis. These results provide a new perspective for an improved understanding of ceRNA-mediated gene regulation in cervical spondylosis, and provide a novel theoretical basis for further studies on the function of lncRNA in cervical spondylosis. However, further experiments are required to validate the results of the present study.

Roles of MicroRNAs in Bone Destruction of Rheumatoid Arthritis

As an important pathological result of rheumatoid arthritis (RA), bone destruction will lead to joint injury and dysfunction. The imbalance of bone metabolism caused by increased osteoclast activities and decreased osteoblast activities is the main cause of bone destruction in RA. MicroRNAs (MiRNAs) play an important role in regulating bone metabolic network. Recent studies have shown that miRNAs play indispensable roles in the occurrence and development of bone-related diseases including RA. In this paper, the role of miRNAs in regulating bone destruction of RA in recent years, especially the differentiation and activities of osteoclast and osteoblast, is reviewed. Our results will not only help provide ideas for further studies on miRNAs’ roles in regulating bone destruction, but give candidate targets for miRNAs-based drugs research in bone destruction therapy of RA as well.

miR-431-5p regulates cell proliferation and apoptosis in fibroblast-like synoviocytes in rheumatoid arthritis by targeting XIAP

BACKGROUND

miR-431-5p is dysregulated in various cancers and plays an important function in the development of cancer. However, its role in fibroblast-like synoviocytes (FLSs) in patients with rheumatoid arthritis (RA) remains to be understood.

METHODS

Quantitative real-time polymerase chain reaction was used to detect the relative expression of miR-431-5p in synovial tissues and FLSs. Cell proliferation assays helped examine RA FLS proliferation. Flow cytometry was performed to determine apoptosis and cell cycle progression in RA FLSs. We used dual-luciferase assays to determine the correlation between miR-431-5p and its putative target, X-linked inhibitor of apoptosis (XIAP). Quantitative real-time PCR and western blotting were used to measure XIAP levels in synovial tissues and transfected RA FLSs.

RESULTS

miR-431-5p was downregulated in synovial tissues and FLSs of patients with RA. Upregulation of miR-431-5p prohibited cell proliferation and the G0/G1-to-S phase transition but promoted apoptosis in RA FLSs, while miR-431-5p inhibition showed the opposite results. miR-431-5p directly targeted XIAP in RA FLSs and reversely correlated with XIAP levels in synovial tissues. Notably, XIAP silencing partially restored the effects of miR-431-5p inhibition in RA FLSs.

CONCLUSION

miR-431-5p regulates cell proliferation, apoptosis, and cell cycle of RA FLSs by targeting XIAP, suggesting its potential in the treatment of RA.

Involvement of Noncoding RNAs in the Differentiation of Osteoclasts

As the most important bone-resorbing cells, osteoclasts play fundamental roles in bone remodeling and skeletal health. Much effort has been focused on identifying the regulators of osteoclast metabolism. Noncoding RNAs (ncRNAs) reportedly regulate osteoclast formation, differentiation, survival, and bone-resorbing activity to participate in bone physiology and pathology. The present review intends to provide a general framework for how ncRNAs and their targets regulate osteoclast differentiation and the important events of osteoclastogenesis they are involved in, including osteoclast precursor generation, early differentiation, mononuclear osteoclast fusion, and multinucleated osteoclast function and survival. This framework is beneficial for understanding bone biology and for identifying the potential biomarkers or therapeutic targets of bone diseases. The review also summarizes the results of in vivo experiments and classic experiment methods for osteoclast-related researches.

MicroRNAs in Synovial Pathology Associated With Osteoarthritis

Osteoarthritis (OA) is the most common type of arthritis, a disease that affects the entire joint. The relative involvement of each tissue, and their interactions, add to the complexity of OA, hampering our understanding of the underlying molecular mechanisms, and the generation of a disease modifying therapy. The synovium is essential in maintaining joint homeostasis, and pathologies associated with the synovium contribute to joint destruction, pain and stiffness in OA. MicroRNAs (miRNAs) are post-transcriptional regulators dysregulated in OA tissues including the synovium. MiRNAs are important contributors to OA synovial changes that have the potential to improve our understanding of OA and to act as novel therapeutic targets. The purpose of this review is to summarize and integrate current published literature investigating the roles that miRNAs play in OA-related synovial pathologies including inflammation, matrix deposition and cell proliferation.

Role of microRNAs in the Development of Cardiovascular Disease in Systemic Autoimmune Disorders

Rheumatoid Arthritis (RA), Systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) are the systemic autoimmune diseases (SADs) most associated with an increased risk of developing cardiovascular (CV) events. Cardiovascular disease (CVD) in SADs results from a complex interaction between traditional CV-risk factors, immune deregulation and disease activity. Oxidative stress, dyslipidemia, endothelial dysfunction, inflammatory/prothrombotic mediators (cytokines/chemokines, adipokines, proteases, adhesion-receptors, NETosis-derived-products, and intracellular-signaling molecules) have been implicated in these vascular pathologies. Genetic and genomic analyses further allowed the identification of signatures explaining the pro-atherothrombotic profiles in RA, SLE and APS. However, gene modulation has left significant gaps in our understanding of CV co-morbidities in SADs. MicroRNAs (miRNAs) are emerging as key post-transcriptional regulators of a suite of signaling pathways and pathophysiological effects. Abnormalities in high number of miRNA and their associated functions have been described in several SADs, suggesting their involvement in the development of atherosclerosis and thrombosis in the setting of RA, SLE and APS. This review focusses on recent insights into the potential role of miRNAs both, as clinical biomarkers of atherosclerosis and thrombosis in SADs, and as therapeutic targets in the regulation of the most influential processes that govern those disorders, highlighting the potential diagnostic and therapeutic properties of miRNAs in the management of CVD.

5-Hydroxy-l-tryptophan Promotes the Milk Calcium Level via the miR-99a-3p/ATP2B1 Axis in Goat Mammary Epithelial Cells

5-Hydroxy-l-tryptophan (5-HTP) is the primary product that converts l-tryptophan into 5-hydroxytryptamine by a rate-limiting enzyme. Our previous study found that 5-HTP could promote the intracellular calcium level in goat mammary epithelial cells (GMECs). Herein, first, dairy goats were injected with 5-HTP or saline daily from 7 days before delivery, and the calcium level in colostrum of 5-HTP-injected goats was significantly higher than that of saline-injected goats. Moreover, miR-99a-3p expression was significantly increased after 5-HTP treatment from transcriptome sequencing analysis and quantitative real-time polymerase chain reaction. In addition, it was found that ATP2B1 is one of the target genes of miR-99a-3p predicted by bioinformatic methods, which plays a crucial role in the maintenance of intracellular calcium homeostasis of mammary epithelial cells. Next, we confirmed that miR-99a-3p could increase the intracellular calcium level via decreasing ATP2B1 in GMECs. Taken together, we draw the conclusion that 5-HTP promotes the calcium level in colostrum possibly by increasing intracellular calcium of mammary epithelial cells induced by the miR-99a-3p/ATP2B1 axis.

MicroRNA let-7g-5p alleviates murine collagen-induced arthritis by inhibiting Th17 cell differentiation

Rheumatoid arthritis (RA) is a chronic and systemic autoimmune disease with complicated pathogenesis. IL-17-producing T helper cells (Th17) are important players in the RA process. Despite numerous researches have proven that microRNAs (miRNAs) are crucial to regulate autoimmune diseases including RA, the effect of miRNAs on Th17 cell differentiation and function in the RA progress is not clear. Here, our results showed that the expression of miRNA let-7g-5p was substantially lower in RA patients and CIA mice compared with healthy controls, accompanied by the increased Th17 cell population. Furthermore, the inhibition of let-7g-5p on Th17 cell differentiation and function were verified in vitro. Notably, the disease severity in CIA mice was significantly alleviated after the treatment of let-7g-5p mimics. In addition, let-7g-5p mimics treatment markedly down-regulated the frequency of Th17 cells in CIA mice. Taken together, our findings indicate that let-7g-5p can ameliorate CIA through blocking the differentiation of Th17 cells, which may be a novel strategy to treat autoimmune diseases such as RA.

Scaffold-Based Gene Therapeutics for Osteochondral Tissue Engineering

Significant progress in osteochondral tissue engineering has been made for biomaterials designed to deliver growth factors that promote tissue regeneration. However, due to diffusion characteristics of hydrogels, the accurate delivery of signaling molecules remains a challenge. In comparison to the direct delivery of growth factors, gene therapy can overcome these challenges by allowing the simultaneous delivery of growth factors and transcription factors, thereby enhancing the multifactorial processes of tissue formation. Scaffold-based gene therapy provides a promising approach for tissue engineering through transfecting cells to enhance the sustained expression of the protein of interest or through silencing target genes associated with bone and joint disease. Reports of the efficacy of gene therapy to regenerate bone/cartilage tissue regeneration are widespread, but reviews on osteochondral tissue engineering using scaffold-based gene therapy are sparse. Herein, we review the recent advances in gene therapy with a focus on tissue engineering scaffolds for osteochondral regeneration.

Nuclear Factor kappa B (NF-κB) Targeted Self-Assembled Nanoparticles Loaded with Methotrexate for Treatment of Rheumatoid Arthritis

Background

Nanotechnology is one of the most productive approaches for specifically delivering drug payloads to the region of interest to decrease nonspecific distribution and unwanted toxicities.

Material/Methods

We prepared glycol chitosan stearate self-assembled nanoparticles loaded with methotrexate (MTX) for NF-κB targeting in treatment of rheumatoid arthritis (RA). The nanoparticles were prepared using hydrophobic modification of glycol chitosan (GC) with steric acid (SA) and was characterized using IR. The efficiency of nanoparticles after their physiochemical characterization was measured in vitro and by in vivo studies in mice.

Results

The nanoparticles thus prepared were spherical in shape, 235 nm in diameter, and had negative zeta potential. The entrapment efficiency of MTX-GC-SA was more than 70%. The in vitro higher uptake of MTX-GC-SA in murine macrophage cells (RAW 264.7) was confirmed using confocal microscopy and FACS analysis. Systemic administration of MTX-GC-SA into collagen-induced arthritis (CIA) mice resulted in high accumulation in inflamed joints. The MTX-GS-SA revealed significantly better therapeutic efficacy against CIA mice compared to free MTX.

Conclusions

These findings highlight the potential of using this MTX-GC-SA nanoparticle formulation in suppressing inflammatory arthritis for effective treatment of RA.

Changes of serum inflammatory factors and miR-145 expression in patients with osteoarthritis before and after treatment and their clinical value

BACKGROUND

Osteoarthritis is a chronic degenerative disease with an incidence of 50% in people over 65 years old and 80% in people over 80 years old worldwide. It is the second leading reason of loss of working capacity after cardiovascular diseases and severely affects the society and families. Therefore, finding biological markers related to the diagnosis and treatment of osteoarthritis is of great significance in clinical practice.

AIM

To observe the changes and clinical value of serum inflammatory factors and miR-145 expression in patients with osteoarthritis before and after treatment.

METHODS

Eighty-three patients with knee osteoarthritis (observation group) who were admitted to our hospital from April 2013 to June 2015, and 60 healthy people (control group) during the same period were selected. After 4 wk of treatment, the levels of miR-145, tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-10 were compared between the control group and the observation group before treatment. The correlation of miR-145, TNF-α, IL-6, and IL-10 levels with visual analogue scale (VAS), Lysholm, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores was assessed by Pearson correlation analysis. The correlation of the expression of miR-145, TNF-α, IL-6, and IL-10 with Kellgren-Lawrence (K-L) grades was assessed by Spearman correlation analysis. The critical levels of miR-145, TNF-α, IL-6, and IL-10 in distinguishing different K-L grades were determined by receiver operating characteristic (ROC) curve analysis.

RESULTS

The expression level of miR-145 in the observation group was significantly higher than that in the control group before treatment (P < 0.05). After treatment, the expression level of miR-145 in the observation group was significantly lower than that before treatment (P < 0.05). The levels of TNF-α and IL-6 in the observation group were significantly higher than those in the control group (P < 0.05), and the level of IL-10 was significantly lower than that in the control group (P < 0.05). After treatment, the levels of TNF-α and IL-6 in the observation group were significantly lower than those before treatment (P < 0.05), and IL-I0 level was significantly higher than that before treatment (P < 0.05). VAS and WOMAC scores were both positively correlated with miR-145, TNF-α, and IL-6 (P < 0.05), and negatively correlated with IL-10 (P < 0.05), while Lysholm scores were negatively correlated with miR-145, TNF-α, and IL-6 (P < 0.05), and positively correlated with IL-10 (P < 0.05). K-L grades were positively correlated with miR-145, TNF-α, and IL-6 (P < 0.05), and negatively correlated with IL-10 (P < 0.05). The area under the ROC curve (AUC) and specificity of TNF-α in differentiating K-L grades I-II were the highest, which were 0.785 and 97.45%, respectively, and miR145 had the highest sensitivity of 94.59%; the AUC and sensitivity of IL-6 in differentiating K-L grades II-III were the highest, which were 0.766 and 97.30%, respectively, and TNF-α had the highest specificity of 86.68%.

CONCLUSION

MiR-145 and inflammatory factors have certain diagnostic value in osteoarthritis, and they are expected to become potential indicators for the diagnosis and evaluation of osteoarthritis in the future.

MicroRNAs in rheumatoid arthritis: From pathogenesis to clinical impact

Over the last decade, many epigenetic mechanisms that contribute in the pathogenesis of autoimmune disorders have been revealed. MicroRNAs (miRNAs) are small, non-coding, RNA molecules that bind to messenger RNAs and disrupt the transcription of target genes. Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease in which a plethora of epigenetic changes take place. Current research on RA epigenetics has focused mainly on miRNAs. Genetic variance of some miRNA genes, especially miR-499, might predispose an individual to RA development. Additionally, altered expression of many miRNAs has been discovered in several cells, tissues and body fluids in patients with RA. MiRNAs expression also differs depending on disease's stage and activity. Serum miR-22 and miR-103a might predict RA development in susceptible individuals (pre-RA), while serum miR-16, miR-24, miR-125a and miR-223 levels are altered in early RA (disease duration <12 months) patients compared to established RA or healthy individuals. Moreover, serum miR-223 levels have been associated with RA activity and disease relapse. What is more, serum levels of several miRNAs, including miR-125b and miR-223, could be used to predict response to RA treatment. Finally, miRNA analogs or antagonists have been used as therapeutic regimens in experimental arthritis models and have demonstrated promising results. In conclusion, the research on the miRNA alterations in RA sheds light to several aspects of RA pathogenesis, introduces new biomarkers for RA diagnosis and treatment response prediction and offers the opportunity to discover new, targeted drugs for patients with RA.

Advances in Molecular biomarker for early diagnosis of Osteoarthritis

Osteoarthritis (OA) is a chronic degenerative joint disease. The pathogenesis is poorly understood. What is known is that OA is characterized by imbalance in anabolic and catabolic gene expression in articular chondrocytes. This results in bone on bone articulations resulting in impaired mobility and joint pain. Although the cause of OA is unknown, comorbidities include: aging, obesity, and mechanical stress. Currently the only diagnostic modalities are radiology and physical examination, and early detection is rare. Biomarkers are quantifiable substances, and their presence can be suggestive of a certain phenomenon or disease. Biomarkers are popular for early diagnosis for pathological conditions in the fields of oncology, cardiology, and endocrinology. This review has systematically reviewed the literature about biomarkers in the field of OA, specifically protein, miRNA, and metabolic biomarkers found in the blood, urine, and synovial fluid.

Elevated microRNA‑145‑5p increases matrix metalloproteinase‑9 by activating the nuclear factor‑κB pathway in rheumatoid arthritis

The present study explored whether miR‑145‑5p can aggravate the development and progression of rheumatoid arthritis (RA) by regulating the expression of matrix metalloproteinases (MMPs). ELISAs, reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR), and western blotting were used to examine the expression levels of MMP‑1, MMP‑3, MMP‑9, and MMP‑13 in fibroblast‑like synoviocytes (FLS) from patients with RA. Levels of MMP‑1, MMP‑3, MMP‑9, and MMP‑13 were assessed in the right hind ankles of a murine collagen‑induced arthritis (CIA) model by RT‑qPCR and immunohistochemical (IHC) analysis. The effects of activation or inhibition of the nuclear factor‑κB (NF‑κB) pathway on MMPs were evaluated by RT‑qPCR and western blotting. Subcellular localization of NF‑κB p65 was visualized by confocal microscopy. Overexpression of miR‑145‑5p increased the expression of MMP‑3, MMP‑9, and MMP‑13 in RA‑FLS. Moreover, injection of a miR‑145‑5p agomir into mice increased MMP‑3, MMP‑9, and MMP‑13, as demonstrated by RT‑qPCR and IHC analysis. A chemical inhibitor that selectively targets NF‑κB (BAY11‑7082) significantly attenuated MMP‑9 expression, while it did not influence the levels of MMP‑3 and MMP‑13. Immunofluorescence analysis revealed that nuclear localization of p65 was significantly enhanced, indicating that miR‑145‑5p enhances activation of the NF‑κB pathway by promoting p65 nuclear translocation. miR‑145‑5p overexpression also significantly increased phosphorylated p65 levels; however, the levels of IkB‑a were reduced in response to this miRNA. Moreover, our results indicated that miR‑145‑5p aggravated RA progression by activating the NF‑κB pathway, which enhanced secretion of MMP‑9. In conclusion, modulation of miR‑145‑5p expression is potentially useful for the treatment of RA inflammation, by regulating the expression of MMPs, and MMP‑9 in particular, through inhibition of the NF‑κB pathway.