Epigenetics of inflammatory arthritis

Epigenetic biomarkers for disease susceptibility and preventative medicine

The development of molecular biomarkers for disease makes it possible for preventative medicine approaches to be considered. Therefore, therapeutics, treatments, or clinical management can be used to delay or prevent disease development. The problem with genetic mutations as biomarkers is the low frequency with genome-wide association studies (GWASs), generally at best a 1% association of the patients with the disease. In contrast, epigenetic alterations have a high-frequency association of greater than 90%-95% of individuals with pathology in epigenome-wide association studies (EWASs). A wide variety of human diseases have been shown to have epigenetic biomarkers that are disease specific and that detect pathology susceptibility. This review is focused on the epigenetic biomarkers for disease susceptibility, and it distinct from the large literature on epigenetics of disease etiology or progression. The development of efficient epigenetic biomarkers for disease susceptibility will facilitate a paradigm shift from reactionary medicine to preventative medicine.

Nod-like receptors in inflammatory arthritis

Nod-like receptors (NLRs) are innate immune receptors that play a key role in sensing components from pathogens and from damaged cells or organelles. NLRs form signaling complexes that can lead to activation of transcription factors or effector caspases - by means of inflammasome activation -Inflammatory arthritis (IA) culminating in promoting inflammation. An increasing body of research supports the role of NLRs in driving pathogenesis of IA, a collection of diseases that include rheumatoid arthritis (RA), psoriatic arthritis (PsA), ankylosing spondylitis, and pediatric arthritis. In this review, we briefly discuss the main drivers of IA diseases and dive into the evidence for - and against - various NLRs in driving these diseases. We also review the studies examining the use of NLR and inflammasome inhibitors as potential therapies for IA.

ADAM8 silencing suppresses the migration and invasion of fibroblast-like synoviocytes via FSCN1/MAPK cascade in osteoarthritis

OBJECTIVE

Osteoarthritis (OA) is a degenerative joint disease that affects elderly populations worldwide, causing pain and disability. Alteration of the fibroblast-like synoviocytes (FLSs) phenotype leads to an imbalance in the synovial inflammatory microenvironment, which accelerates the progression of OA. Despite this knowledge, the specific molecular mechanisms of the synovium that affect OA are still unclear.

METHODS

Both in vitro and in vivo experiments were undertaken to explore the role of ADAM8 playing in the synovial inflammatory of OA. A small interfering RNA (siRNA) was targeting ADAM8 to intervene. High-throughput sequencing was also used.

RESULTS

Our sequencing analysis revealed significant upregulation of the MAPK signaling cascade and ADAM8 gene expression in IL-1β-induced FLSs. The in vitro results demonstrated that ADAM8 blockade inhibited the invasion and migration of IL-1β-induced FLSs, while also suppressing the expression of related matrix metallomatrix proteinases (MMPs). Furthermore, our study revealed that inhibiting ADAM8 weakened the inflammatory protein secretion and MAPK signaling networks in FLSs. Mechanically, it revealed that inhibiting ADAM8 had a significant effect on the expression of migration-related signaling proteins, specifically FSCN1. When siADAM8 was combined with BDP-13176, a FSCN1 inhibitor, the migration and invasion of FLSs was further inhibited. These results suggest that FSCN1 is a crucial downstream factor of ADAM8 in regulating the biological phenotypes of FLSs. The in vivo experiments demonstrated that ADAM8 inhibition effectively reduced synoviocytes inflammation and alleviated the progression of OA in rats.

CONCLUSIONS

ADAM8 could be a promising therapeutic target for treating OA by targeting synovial inflammation.

Challenges and promise of targeting miRNA in rheumatic diseases: a computational approach to identify miRNA association with cell types, cytokines, and disease mechanisms

MicroRNAs (miRNAs) are small non-coding RNAs that alter the expression of target genes at the post-transcriptional level, influencing diverse outcomes in metabolism, cell differentiation, proliferation, cell survival, and cell death. Dysregulated miRNA expression is implicated in various rheumatic conditions, including ankylosing spondylitis (AS), gout, juvenile idiopathic arthritis (JIA), osteoarthritis (OA), psoriatic arthritis, rheumatoid arthritis (RA), Sjogren's syndrome, systemic lupus erythematosus (SLE) and systemic sclerosis. For this review, we used an open-source programming language- PowerShell, to scan the massive number of existing primary research publications on PubMed on miRNAs in these nine diseases to identify and count unique co-occurrences of individual miRNAs and the disease name. These counts were used to rank the top seven most relevant immuno-miRs based on their research volume in each rheumatic disease. Individual miRNAs were also screened for publication with the names of immune cells, cytokines, and pathological processes involved in rheumatic diseases. These occurrences were tabulated into matrices to identify hotspots for research relevance. Based on this information, we summarize the basic and clinical findings for the top three miRNAs - miR-146, miR-155, and miR-21 - whose relevance spans across multiple rheumatic diseases. Furthermore, we highlight some unique miRNAs for each disease and why some rheumatic conditions lack research in this emerging epigenetics field. With the overwhelming number of publications on miRNAs in rheumatic diseases, this review serves as a 'relevance finder' to guide researchers in selecting miRNAs based on the compiled existing knowledge of their involvement in disease pathogenesis. This approach applies to other disease contexts with the end goal of developing miRNA-based therapeutics.

Jieduquyuziyin prescription enhances CD11a and CD70 DNA methylation of CD4+ T cells via miR-29b-sp1/DNMT1 pathway in MRL/lpr mice

ETHNOPHARMACOLOGICAL RELEVANCE

Jieduquyuziyin prescription (JP) is a traditional Chinese medicine utilized to treat systemic lupus erythematosus (SLE). Its efficacy has been confirmed through clinical trials and empirical evidence, leading to its authorized use in Chinese hospitals. The development of JP exemplifies the integration of traditional wisdom and scientific approaches, demonstrating the interdisciplinary essence of ethnopharmacology. These results emphasize the potential value of traditional medicine in addressing autoimmune disorders.

AIM OF THE STUDY

This study aims to address the effect of JP in MRL/lpr mice and elucidate the pharmacological mechanism by which JP targets CD11a and CD70 DNA methylation via the miR-29b-sp1/DNMT1 pathway.

MATERIALS AND METHODS

MRL/lpr mice were divided into three groups: the model group (received distilled water), the positive group (administered AAV/miR-29b-3p inhibitor), and the JP group (treated with JP decoction). C57BL/6 mice were constituted as a control group. Through ELISA assay, serum and urine samples were assessed for anti-dsDNA, TNF-α, TGF-β, IL-2, and UP. HE and Masson staining were conducted to reveal renal pathology. Genome DNA was extracted from CD4+ T cells of mice spleens to evaluate methylation level. The methylation of CD11a, CD70, and CD40L promoter regions was analyzed by targeted bisulfate sequencing. Their expression at the mRNA and protein levels was examined using quantitative real-time PCR, western blot analysis, immunohistochemistry, and immunofluorescence staining of kidney tissues. Furthermore, the molecular mechanisms underlying the regulation of the miR-29b-sp1/DNMT1 pathway by JP were explored with Jurkat cells transfected with miR-inhibitors or miR-mimics.

RESULTS

Mice treated with JP exhibited a significant decrease in anti-dsDNA, TNF-α, TGF-β, and UP, accompanied by a significant increase in IL-2. HE staining revealed JP effectively mitigated renal inflammatory response, while Masson staining indicated a reduction in collagen fiber content. In addition, JP exhibited a significant impact on the global hypomethylation of SLE, as evidenced by the induction of high methylation levels of CD11a and CD70 promoter regions, mediated through the miR-29b-sp1/DNMT1 pathway.

CONCLUSION

Our findings demonstrate JP exerts a protective effect against spontaneous SLE development, attenuates renal pathological changes, and functions as a miRNA inhibitor to enhance CD11a and CD70 DNA methylation through the modulation of the miR-29b-sp1/DNMT1 pathway.

Role of miRNAs in Rheumatoid Arthritis Therapy

Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease characterized by autoimmunity, synovial inflammation and joint destruction. Pannus formation in the synovial cavity can cause irreversible damage to the joint and cartilage and eventually permanent disability. Current conventional treatments for RA have limitations regarding efficacy, safety and cost. microRNA (miRNA) is a type of non-coding RNA (ncRNA) that regulates gene expression at the post-transcriptional level. The dysregulation of miRNA has been observed in RA patients and implicated in the pathogenesis of RA. miRNAs have emerged as potential biomarkers or therapeutic agents. In this review, we explore the role of miRNAs in various aspects of RA pathophysiology, including immune cell imbalance, the proliferation and invasion of fibroblast-like synovial (FLS) cell, the dysregulation of inflammatory signaling and disturbance in angiogenesis. We delve into the regulatory effects of miRNAs on Treg/Th17 and M1/M2 polarization, the activation of the NF-κB/NLRP3 signaling pathway, neovascular formation, energy metabolism induced by FLS-cell-induced energy metabolism, apoptosis, osteogenesis and mobility. These findings shed light on the potential applications of miRNAs as diagnostic or therapeutic biomarkers for RA management. Furthermore, there are some strategies to regulate miRNA expression levels by utilizing miRNA mimics or exosomes and to hinder miRNA activity via competitive endogenous RNA (ceRNA) network-based antagonists. We conclude that miRNAs offer a promising avenue for RA therapy with unlimited potential.

Decipher the pharmacological mechanisms of raw and wine-processed Curculigo orchioides Gaertn. on bone destruction in rheumatoid arthritis rats using metabolomics

ETHNOPHARMACOLOGICAL RELEVANCE

Curculigo orchioides Gaertn. (CO), a traditional Chinese herb recorded in Chinese Pharmacopoeia, can nourish kidney yang, strengthen bones, and dispell cold-dampness. Raw CO (rCO) and wine-processed CO (pCO), the main processed products of CO for clinical application, show differences in nourishing kidney yang and ameliorate osteoporosis. However, the difference in efficacy and mechanism of rCO and pCO on bone destruction in rheumatoid arthritis (RA) remain unclear.

AIM OF THE STUDY

To compare the pharmacodynamics of rCO and pCO in the treatment of bone destruction in RA and to reveal the potential mechanism by which rCO and pCO exert effects by metabolomics approach.

MATERIALS AND METHODS

Ultra-high performance liquid chromatography Q exactive mass spectrometry (UHPLC-Q-Exactive-MS) combined with multivariate data analysis was applied to identify the differential chemical components in rCO and pCO. Collagen-induced arthritis (CIA) rats were orally administrated with different doses of rCO and pCO for 4 weeks. The body weight, paw swelling, arthritis scores, serum inflammatory cytokines concentration, knee tumor necrosis factor (TNF)-α, interleukin (IL)-6 protein levels, and inflammatory cell infiltration were determined to investigate the effects of rCO and pCO on arthritic symptoms and inflammatory responses in CIA rats. The effects of rCO and pCO on bone destruction were assessed using safranin O-fast green and tartrate-resistant acid phosphatase (TRAP) staining, immunohistochemical analysis of osteoprotegerin (OPG) and receptor activator of nuclear factor-κB ligand (RANKL) proteins, and micro-computed tomography (micro-CT) in rats. In addition, metabolomics was performed to explore the mechanism of rCO and pCO against bone destruction in RA.

RESULTS

A total of 41 chemical constituents were identified in both rCO and pCO, 9 of which were screened out as discriminatory compounds. According to the pharmacodynamic assays, pCO exhibited a stronger effect than rCO in attenuating the severity of arthritis, reducing inflammation, and inhibiting bone destruction. The metabolomics results showed that pentose phosphate pathway was the key metabolic pathways regulated by rCO, while pCO regulated multiple metabolic pathways including phenylalanine metabolism pathways, phenylalanine, tyrosine and tryptophan biosynthesis, taurine and hypotaurine metabolism, and glycerophospholipid metabolism pathways.

CONCLUSION

pCO displayed a better effect on alleviating bone destruction in RA was than rCO. This might be associated with that pCO can decrease inflammation in RA through regulating more metabolism pathways.

Differential expression and correlation of immunoregulation related piRNA in rheumatoid arthritis

Background

Although PIWI-interacting RNAs (piRNAs) have recently been associated with germline development and many human diseases, their expression pattern and relationship in autoimmune diseases remain indistinct. This study aimed to investigate the presence and correlation of piRNAs in rheumatoid arthritis (RA).

Methods

We first analyzed the expression profile of piRNAs using small RNA sequencing in peripheral leukocytes of three new-onset untreated RA patients and three healthy controls (HCs). We then selected piRNAs related to immunoregulation by bioinformatics analysis and verified them in 42 new-onset RA patients and 81 HCs by RT-qPCR. Furthermore, a receiver operating characteristic curve was generated to quantify the diagnostic performance of these piRNAs. A correlation analysis was conducted to observe the link between piRNA expression and RA clinical characteristics.

Results

A total of 15 upregulated and 9 downregulated piRNAs among 1,565 known piRNAs were identified in peripheral leukocytes of RA patients. Dysregulated piRNAs were enriched in numerous pathways related to immunity. After selection and validation, two immunoregulation piRNAs (piR-hsa-27620 and piR-hsa-27124) were significantly elevated in RA patients and have good abilities to distinguish patients from controls, which have the potential to serve as biomarkers. PIWI and other proteins implicated in the piRNA pathway were also associated with RA.

DNMT1 regulates polarization of macrophage-induced intervertebral disc degeneration by modulating SIRT6 expression and promoting pyroptosis in vivo

BACKGROUND

Intervertebral disc degeneration (IDD) is a complex phenomenon and a multifactorial degenerative disease that creates a heavy economic burden on health systems globally. Currently, there is no specific treatment proven to be effective in reversing and delaying the progression of IDD.

METHOD

This study consisted of animal and cell culture experiments. The role of DNA methyltransferase 1 (DNMT1) on regulating the M1/M2 macrophages polarization and pyroptosis, as well as its effect on Sirtuin 6 (SIRT6) expression in an IDD rat model and in tert-butyl hydroperoxide (TBHP)-treated nucleus pulposus cells (NPCs) were explored. Rat models were constructed, followed by transfection with lentiviral vector to inhibit DNMT1 or overexpress SIRT6. The NPCs were treated with THP-1-cells conditioned medium, and their pyroptosis, apoptosis, and viability were evaluated. Western blot, histological and immunohistochemistry staining, ELISA, PCR, and flow cytometry were all used to evaluate the role of DNMT1/ SIRT6 on macrophage polarization.

RESULTS

Silencing DNMT1 inhibited apoptosis, the expression of related inflammatory mediators (e.g., iNOS) and inflammatory cytokines (e.g., IL6 and TNF-α). Moreover, silencing DNMT1 significantly inhibited the expression of pyroptosis markers IL- 1β, IL-6, and IL-18 and decreased the NLRP3, ASC, and caspase-1 expression. On the other hand, M2 macrophage specific markers CD163, Arg-1, and MR were overexpressed upon silencing DNMT1 or SIRT6 overexpression. At the same time, silencing DNMT1 exerted a regulatory effect on increasing the SIRT6 expression.

CONCLUSIONS

DNMT1 may be a promising potential target for IDD treatment due to its ability to ameliorate the progression of the disease.

Significance of Circulating Cell-Free DNA Biomarkers in HBeAg-Negative Chronic Hepatitis B Virus Infection and Their Changes after Treatment Initiation

Background: Chronic hepatitis B virus (HBV) infection is a common chronic liver disease that is closely associated with increased morbidity and mortality. Circulating cell-free DNA (cf-DNA) and global DNA methylation, expressed as circulating levels of 5-methyl-2′-deoxycytidine, are increasingly used to monitor chronic inflammatory diseases of several etiologies. This study attempts to investigate the serum levels of circulating cf-DNA and 5-methyl-2′-deoxycytidine in HBeAg-negative patients with chronic infection (carriers) and chronic hepatitis B (CHB), as well as their changes after treatment initiation in CHB. Methods: Serum samples from a total of 61 HBeAg-negative patients (30 carriers and 31 CHB patients) were included in order to quantify the levels of circulating cf-DNA and 5-methyl-2′-deoxycytidine. In addition, serum samples from 17 CHB patients in complete virological and biochemical remission after initiation of treatment with a nucleos(t)ide analogue were included. Results: Circulating cf-DNA concentration was significantly increased after the initiation of treatment (15 vs. 10 ng/mL, p = 0.022). There was a trend in higher mean levels of circulating 5-methyl-2′-deoxycytidine in carriers compared to CHB patients (211.02 vs. 175.66 ng/mL, p = 0.089), as well as a trend in increasing 5-methyl-2′-deoxycytidine levels after treatment initiation in CHB patients compared to pre-treatment levels (215 vs. 173 ng/mL, p = 0.079). Conclusions: Both circulating levels of cf-DNA and 5-methyl-2′-deoxycytidine might be useful biomarkers in order to monitor liver disease activity and response to antiviral treatment in HBeAg-negative chronic HBV patients, but further studies are essential in order to validate these intriguing findings.

Fibroblast heterogeneity: Keystone of tissue homeostasis and pathology in inflammation and ageing

Fibroblasts, derived from the embryonic mesenchyme, are a diverse array of cells with roles in development, homeostasis, repair, and disease across tissues. In doing so, fibroblasts maintain micro-environmental homeostasis and create tissue niches by producing a complex extracellular matrix (ECM) including various structural proteins. Although long considered phenotypically homogenous and functionally identical, the emergence of novel technologies such as single cell transcriptomics has allowed the identification of different phenotypic and cellular states to be attributed to fibroblasts, highlighting their role in tissue regulation and inflammation. Therefore, fibroblasts are now recognised as central actors in many diseases, increasing the need to discover new therapies targeting those cells. Herein, we review the phenotypic heterogeneity and functionality of these cells and their roles in health and disease.

Chondroprotective Mechanism of Eucommia ulmoides Oliv.-Glycyrrhiza uralensis Fisch. Couplet Medicines in Knee Osteoarthritis via Experimental Study and Network Pharmacology Analysis

Background

Knee osteoarthritis (KOA) is the primary prevalent disabling joint disorder among osteoarthritis (OA), and there is no particularly effective treatment at the clinic. Traditional Chinese medicine (TCM) herbs, such as Eucommia ulmoides Oliv. and Glycyrrhiza uralensis Fisch. (E.G.) couplet medicines, have been reported to exhibit beneficial health effects on KOA, exact mechanism of E.G. nevertheless is not fully elucidated.

Purpose

We assess the therapeutic effects of E.G. on KOA and explore its underlying molecular mechanism.

Methods

UPLC-Q-TOF/MS technique was used to analyze the active chemical constituents of E.G. The destabilization of the medial meniscus model (DMM) was employed to evaluate the chondroprotective action of E.G. in KOA mice using histomorphometry, μCT, behavioral testing and immunohistochemical staining. Additionally, network pharmacology and molecular docking were used to predict potential targets for anti-KOA activities of E.G., which was further verified through in vitro experiments.

Results

In vivo studies have shown that E.G. could significantly ameliorate DMM-induced KOA phenotypes including subchondral bone sclerosis, cartilage degradation, gait abnormality and thermal pain reaction sensibility. E.G. treatment could also promote extracellular matrix synthesis to protect articular chondrocytes, which was indicated by Col2 and Aggrecan expressions, as well as reducing matrix degradation by inhibiting MMP13 expression. Interestingly, network pharmacologic analysis showed that PPARG might be a therapeutic center. Further study proved that E.G.-containing serum (EGS) could up-regulate PPARG mRNA level in IL-1β-induced chondrocytes. Notably, significant effects of EGS on the increment of anabolic gene expressions (Col2, Aggrecan) and the decrement of catabolic gene expressions (MMP13, Adamts5) in KOA chondrocytes were abolished due to the silence of PPARG.

Conclusion

E.G. played a chondroprotective role in anti-KOA by inhibiting extracellular matrix degradation, which might be related to PPARG.

LSD1 for the Targeted Regulation of Adipose Tissue

White and thermal (brown and beige) adipose tissue energy storage and oxidative regulation pathways play a central role in maintaining the energy balance throughout the body, and the dysregulation of these pathways is closely related to glucose and lipid metabolism disorders and adipose tissue dysfunction, including obesity, chronic inflammation, insulin resistance, mitochondrial dysfunction, and fibrosis. Recent epigenetic studies have identified the novel regulatory element LSD1, which controls the above parameters, and have provided new mechanistic possibilities for re-encoding the fate and function of adipocytes. In this review, we outline the current advances in adipocyte metabolism in physiology and disease and discuss possible strategies for LSD1 to alter the phenotype of adipose tissue and thus influence energy utilization to improve metabolic health.

The spectrum of tuberculosis described as differential DNA methylation patterns in alveolar macrophages and alveolar T cells

BACKGROUND

Host innate immune cells have been identified as key players in the early eradication of Mycobacterium tuberculosis and in the maintenance of an anti-mycobacterial immune memory, which we and others have shown are induced through epigenetic reprogramming. Studies on human tuberculosis immunity are dominated by those using peripheral blood as surrogate markers for immunity. We aimed to investigate DNA methylation patterns in immune cells of the lung compartment by obtaining induced sputum from M. tuberculosis- exposed subjects including symptom-free subjects testing positively and negatively for latent tuberculosis as well as patients diagnosed with active tuberculosis. Alveolar macrophages and alveolar T cells were isolated from the collected sputum and DNA methylome analyses performed (Illumina Infinium Human Methylation 450 k).

RESULTS

Multidimensional scaling analysis revealed that DNA methylomes of cells from the tuberculosis-exposed subjects and controls appeared as separate clusters. The numerous genes that were differentially methylated between the groups were functionally connected and overlapped with previous findings of trained immunity and tuberculosis. In addition, analysis of the interferon-gamma release assay (IGRA) status of the subjects demonstrated that the IGRA status was reflected in the DNA methylome by a unique signature.

CONCLUSIONS

This pilot study suggests that M. tuberculosis induces epigenetic reprogramming in immune cells of the lung compartment, reflected as a specific DNA methylation pattern. The DNA methylation signature emerging from the comparison of IGRA-negative and IGRA-positive subjects revealed a spectrum of signature strength with the TB patients grouping together at one end of the spectrum, both in alveolar macrophages and T cells. DNA methylation-based biosignatures could be considered for further development towards a clinically useful tool for determining tuberculosis infection status and the level of tuberculosis exposure.

Safety and efficacy of probiotic supplementation in 8 types of inflammatory arthritis: A systematic review and meta-analysis of 34 randomized controlled trials

Objective

To evaluate Safety and efficacy of probiotic supplementation in inflammatory arthritis.

Methods

The literature on the treatment of inflammatory arthritis with probiotics has been collected in databases such as CNKI, Pubmed, Cochrane library, Embase, etc. The search time is for them to build the database until May 2022. The included literatures are randomized controlled trials (RCTs) of probiotics in the treatment of hyperuricemia and gout. The Cochrane risk assessment tool was used for quality evaluation, and the Rev Man5.3 software was used for meta-analysis.

Results

A total of 37 records were finally included, involving 34 RCTs and 8 types of autoimmune disease (Hyperuricemia and gout, Inflammatory bowel disease arthritis, juvenile idiopathic arthritis [JIA], Osteoarthritis [OA], Osteoporosis and Osteopenia, Psoriasis, rheumatoid arthritis (RA), Spondyloarthritis). RA involved 10 RCTs (632 participants) whose results showed that probiotic intervention reduced CRP. Psoriasis involved 4 RCTs (214 participants) whose results showed that probiotic intervention could reduce PASI scores. Spondyloarthritis involved 2 RCTs (197 participants) whose results showed that probiotic intervention improved symptoms in patients. Osteoporosis and Ostepenia involving 10 RCTs (1156 participants) showed that probiotic intervention improved bone mineral density in patients. Hyperuricemia and gout involving 4 RCTs (294 participants) showed that probiotic intervention improved serum uric acid in patients. OA involving 1 RCTs (433 participants) showed that probiotic intervention improved symptoms in patients. JIA involving 2 RCTs (72 participants) showed that probiotic intervention improved symptoms in patients. Inflammatory bowel disease arthritis involving 1 RCTs (120 participants) showed that probiotic intervention improved symptoms in patients. All of the above RCTs showed that probiotics did not increase the incidence of adverse events.

Conclusion

Probiotic supplements may improve Hyperuricemia and gout, Inflammatory bowel disease arthritis, JIA, OA, Osteoporosis and Osteopenia, Psoriasis, RA, Spondyloarthritis. However, more randomized controlled trials are needed in the future to determine the efficacy and optimal dosing design of probiotics.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021286425, identifier CRD42021286425.

Magnoflorine attenuates inflammatory responses in RA by regulating the PI3K/Akt/NF-κB and Keap1-Nrf2/HO-1 signalling pathways in vivo and in vitro

BACKGROUND

As a prolonged autoimmune disorder, rheumatoid arthritis (RA) is characterised by synovial hyperplasia and the erosion of bone and cartilage. Magnoflorine (MAG) is the main component purified from Clematis manshurica Rupr. Recent studies have shown that MAG has anti-inflammatory, antioxidant, and immunosuppressive effects, which are relevant to anti-RA activities.

OBJECTIVE

The current investigation was conducted to explore the anti-RA effects of MAG and to discover the possible molecular mechanisms.

METHODS

In vitro experiments, CCK-8, wound healing, and transwell assays were utilized to evaluate the anti-proliferative, anti-migratory, and anti-invasive activities of MAG, respectively. The rate of cell distribution and cell apoptosis were evaluated by flow cytometry. ROS generation was detected by DCFH-DA staining. Western blotting, quantitative real-time polymerase chain reaction assay, and immunofluorescent staining were employed to test the anti-RA effect of MAG as well as to explore the potential mechanisms by evaluating related gene and protein expression. For in vivo experiments, an adjuvant-induced arthritis (AIA) rat model was established. The related parameters were measured in rats. Then, rats were sacrificed, and ankle joints were collected for histopathological analysis and observation.

RESULTS

MAG significantly decreased the proliferation, migration, invasion, and reactive oxygen species levels in IL-1β-treated MH7A cells. Furthermore, MAG promoted cell apoptosis by increasing Bax levels and decreasing Bcl-2 levels. MAG also induced cell cycle arrest. Inflammatory cytokines (iNOS, COX-2, IL-6, and IL-8) and MMPs (MMP-1, 2, 3, 9, and 13) were reduced by MAG treatment. Molecular analysis revealed that MAG exerted anti-RA effects by partly inhibiting the PI3K/Akt/NF-κB signalling axis and activating the Keap1-Nrf2/HO-1 signalling pathway. In vivo studies have revealed that MAG treatment substantially improved severe symptoms in AIA rats, and these curative effects were linked to the attenuation of inflammatory responses.

CONCLUSION

These results first suggested that MAG exhibits anti-arthritic effects in IL-1β-treated MH7A cells and AIA rat models. Thus, MAG may be used as a new drug to treat RA clinically.

Mechanism-driven strategies for prevention of rheumatoid arthritis

In seropositive rheumatoid arthritis (RA), the onset of clinically apparent inflammatory arthritis (IA) is typically preceded by a prolonged period of autoimmunity manifest by the presence of circulating autoantibodies that can include antibodies to citrullinated protein antigens (ACPA) and rheumatoid factor (RF). This period prior to clinical IA can be designated preclinical RA in those individuals who have progressed to a clinical diagnosis of RA, and an 'at-risk' status in those who have not developed IA but exhibit predictive biomarkers of future clinical RA. With the goal of developing RA prevention strategies, studies have characterized immune phenotypes of preclinical RA/at-risk states. From these studies, a model has emerged wherein mucosal inflammation and dysbiosis may lead first to local autoantibody production that should normally be transient, but instead is followed by systemic spread of the autoimmunity as manifest by serum autoantibody elevations, and ultimately drives the development of clinically identified joint inflammation. This model can be envisioned as the progression of disease development through serial 'checkpoints' that in principle should constrain or resolve autoimmunity; however, instead the checkpoints 'fail' and clinical RA develops. Herein we review the immune processes that are likely to be present at each step and the potential therapeutic strategies that could be envisioned to delay, diminish, halt or even reverse the progression to clinical RA. Notably, these prevention strategies could utilize existing therapies approved for clinical RA, therapies approved for other diseases that target relevant pathways in the preclinical/at-risk state, or approaches that target novel pathways.

FCER1G Gene Hypomethylation in Patients with Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that, when improperly treated, leads to disability in patients. Various factors that may cause the development and activity of RA are being considered. Epigenetic factors are also receiving increasing attention. In our study, we analyzed the association between FCER1G gene methylation and RA activity. We conducted our study in 50 RA patients and 24 controls. The patients were divided into two groups in terms of high disease activity and remission. Quantitative real-time methylation-specific PCR was used to analyze the methylation status of the investigated genes. We observed that RA patients have lower levels of methylation of the FCER1G gene compared to controls, but we did not find any difference in the methylation status of this gene between patients with high disease activity and remission. The results of this study suggest that FCER1G gene methylation may be a new potential epigenetic marker of RA that is independent of disease activity.

Activation Markers on B and T Cells and Immune Checkpoints in Autoimmune Rheumatic Diseases

In addition to identifying the major B- and T-cell subpopulations involved in autoimmune rheumatic diseases (ARDs), in recent years special attention has been paid to studying the expression of their activation markers and immune checkpoints (ICPs). The activation markers on B and T cells are a consequence of the immune response, and these molecules are considered as sensitive specific markers of ARD activity and as promising targets for immunotherapy. ICPs regulate the activation of the immune response by preventing the initiation of autoimmune processes, and they modulate it by reducing immune cell-induced organ and tissue damage. The article considers the possible correlation of ICPs with the activity of ARDs, the efficacy of specific ARD treatments, and the prospects for the use of activation molecules and activation/blocking ICPs for the treatment of ARDs.

Single-cell multimodal analysis identifies common regulatory programs in synovial fibroblasts of rheumatoid arthritis patients and modeled TNF-driven arthritis

Background

Synovial fibroblasts (SFs) are specialized cells of the synovium that provide nutrients and lubricants for the proper function of diarthrodial joints. Recent evidence appreciates the contribution of SF heterogeneity in arthritic pathologies. However, the normal SF profiles and the molecular networks that govern the transition from homeostatic to arthritic SF heterogeneity remain poorly defined.

Methods

We applied a combined analysis of single-cell (sc) transcriptomes and epigenomes (scRNA-seq and scATAC-seq) to SFs derived from naïve and hTNFtg mice (mice that overexpress human TNF, a murine model for rheumatoid arthritis), by employing the Seurat and ArchR packages. To identify the cellular differentiation lineages, we conducted velocity and trajectory analysis by combining state-of-the-art algorithms including scVelo, Slingshot, and PAGA. We integrated the transcriptomic and epigenomic data to infer gene regulatory networks using ArchR and custom-implemented algorithms. We performed a canonical correlation analysis-based integration of murine data with publicly available datasets from SFs of rheumatoid arthritis patients and sought to identify conserved gene regulatory networks by utilizing the SCENIC algorithm in the human arthritic scRNA-seq atlas.

Results

By comparing SFs from healthy and hTNFtg mice, we revealed seven homeostatic and two disease-specific subsets of SFs. In healthy synovium, SFs function towards chondro- and osteogenesis, tissue repair, and immune surveillance. The development of arthritis leads to shrinkage of homeostatic SFs and favors the emergence of SF profiles marked by Dkk3 and Lrrc15 expression, functioning towards enhanced inflammatory responses and matrix catabolic processes. Lineage inference analysis indicated that specific Thy1+ SFs at the root of trajectories lead to the intermediate Thy1+/Dkk3+/Lrrc15+ SF states and culminate in a destructive and inflammatory Thy1− SF identity. We further uncovered epigenetically primed gene programs driving the expansion of these arthritic SFs, regulated by NFkB and new candidates, such as Runx1. Cross-species analysis of human/mouse arthritic SF data determined conserved regulatory and transcriptional networks.

Conclusions

We revealed a dynamic SF landscape from health to arthritis providing a functional genomic blueprint to understand the joint pathophysiology and highlight the fibroblast-oriented therapeutic targets for combating chronic inflammatory and destructive arthritic disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13073-022-01081-3.

The Application of Extracellular Vesicles Mediated miRNAs in Osteoarthritis: Current Knowledge and Perspective

Osteoarthritis (OA) is a whole joint disease characterized by synovitis, cartilage destruction, and subchondral bone sclerosis and cyst. Despite decades’ study, effective treatment is rare for this chronic disease. Extracellular vesicles (EVs), including exosomes, microvesicles, and apoptosis bodies, are nano-sized vesicles with a cargo containing biologically active agents, such as nucleic acids, lipids, and proteins. As a group of short non-coding RNAs, microRNAs (miRNAs) can be delivered by parental cells secreted EVs. Negatively regulate the target mRNAs at the posttranscriptional level and regulate gene expression in recipient cells without modifying gene sequence. Recently, most studies focused on the function of EVs mediated miRNAs in the pathophysiological process of OA. However, all kinds of EVs specific and OA specific factors might influence the administration of EVs-miRNAs, especially the precise quantitative management. As a result, the flourishing of current research about EVs in the laboratory might not promote the relevant clinical transformation in OA treatment. In this review, we reviewed the present application of EVs-miRNAs in the therapeutic of OA and further analyzed the potential factors that might influence its application. Further progress in the quantitative management of EVs-miRNAs would accelerate the clinical transformation of miRNAs enriched EVs in the OA field.

Epigenetic Regulation in the Pathogenesis of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease. The etiology of RA remains undetermined and the pathogenesis is complex. There remains a paucity of ideal therapeutic drugs and treatment strategies. The epigenetic modifications affect and regulate the function and characteristics of genes through mechanisms, including DNA methylation, histone modification, chromosome remodeling, and RNAi, thereby exerting a significant impact on the living state of the body. Recently, the phenomenon of epigenetic modification in RA has garnered growing research interest. The application of epigenetically modified methods is the frontier field in the research of RA pathogenesis. This review highlights the research on the pathogenesis of RA based on epigenetic modification in the recent five years, thereby suggesting new methods and strategies for the diagnosis and treatment of RA.

TMT-Based Quantitative Proteomics Analysis of Synovial Fluid-Derived Exosomes in Inflammatory Arthritis

Objectives

To compare the proteomics of synovial fluid (SF)-derived exosomes in rheumatoid arthritis (RA), axial spondyloarthritis (axSpA), gout, and osteoarthritis (OA) patients.

Methods

Exosomes were separated from SF by the Exoquick kit combined ultracentrifugation method. Tandem mass tags (TMT)-labeled liquid chromatography mass spectrometry (LC-MS/MS) technology was used to analyze the proteomics of SF-derived exosomes. Volcano plot, hierarchical cluster, gene ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were conducted.

Results

A total of 1,678 credible proteins were detected. Sixty-nine differentially expressed proteins were found in gout, compared with OA, axSpA, and RA simultaneously. Twenty-five proteins were found highly expressed in gout uniquely, lysozyme C and protein S100-A9 included, whose bioinformatic analysis was significantly involved in “neutrophil degranulation” and “prion diseases”. Eighty-four differentially expressed proteins were found in axSpA, compared with OA, gout, and RA simultaneously. Thirty-nine proteins were found highly expressed in axSpA uniquely, RNA-binding protein 8A and protein transport protein Sec24C included, whose bioinformatic analysis was significantly involved in “acute-phase response” and “citrate cycle”. One hundred and eighty-four differentially expressed proteins were found in RA, compared with OA, gout, and axSpA simultaneously. Twenty-eight proteins were found highly expressed in RA uniquely, pregnancy zone protein (PZP) and stromelysin-1 included, whose bioinformatic analysis was significantly involved in “serine-type endopeptidase inhibitor activity” and “complement and coagulation cascades”. Enzyme-linked immunosorbent assay (ELISA) result showed that the exosome-derived PZP level of SF in RA was higher than that in OA (p < 0.05).

Conclusion

Our study for the first time described the protein profiles of SF-derived exosomes in RA, axSpA, gout, and OA patients. Some potential biomarkers and hypothetical molecular mechanisms were proposed, which may provide helpful diagnostic and therapeutic insights for inflammatory arthritis (IA).

Epigenome association study for DNA methylation biomarkers in buccal and monocyte cells for female rheumatoid arthritis

Genetics (i.e., mutations) has been assumed to be the major factor in rheumatoid arthritis (RA) etiology, but accounts for a minority of the variance in disease risk for RA. In contrast to genetics, the environment can have dramatic impacts on epigenetics that associate with disease etiology. The current study used buccal cells and purified blood monocytes from two different clinical cohorts involving Caucasian or African American female populations with or without arthritis. The differential DNA methylation regions (DMRs) between the control and RA populations were identified with an epigenome-wide association study. The DMRs (i.e., epimutations) identified in the buccal cells and monocytes were found to be distinct. The DMR associated genes were identified and many have previously been shown to be associated with arthritis. Observations demonstrate DNA methylation epimutation RA biomarkers are cell type specific and similar findings were observed with the two racial background populations. Rheumatoid arthritis susceptibility epigenetic diagnosis appears feasible and may improve the clinical management of RA and allowpreventative medicine considerations.

Recent Advances in Understanding the Pathogenesis of Rheumatoid Arthritis: New Treatment Strategies

Rheumatoid arthritis (RA) is considered a chronic systemic, multi-factorial, inflammatory, and progressive autoimmune disease affecting many people worldwide. While patients show very individual courses of disease, with RA focusing on the musculoskeletal system, joints are often severely affected, leading to local inflammation, cartilage destruction, and bone erosion. To prevent joint damage and physical disability as one of many symptoms of RA, early diagnosis is critical. Auto-antibodies play a pivotal clinical role in patients with systemic RA. As biomarkers, they could help to make a more efficient diagnosis, prognosis, and treatment decision. Besides auto-antibodies, several other factors are involved in the progression of RA, such as epigenetic alterations, post-translational modifications, glycosylation, autophagy, and T-cells. Understanding the interplay between these factors would contribute to a deeper insight into the causes, mechanisms, progression, and treatment of the disease. In this review, the latest RA research findings are discussed to better understand the pathogenesis, and finally, treatment strategies for RA therapy are presented, including both conventional approaches and new methods that have been developed in recent years or are currently under investigation.

Epigenetically-regulated RPN2 gene influences lymphocyte activation and is involved in pathogenesis of rheumatoid arthritis

BACKGROUND

To identify RA-associated genes and to ascertain epigenetic factors and functional mechanisms underlying RA pathogenesis.

METHODS

Peripheral blood mononuclear cells (PBMC) transcriptome- and proteome- wide gene expressions were profiled in a case-control study sample. Differentially expressed genes (DEGs) were discovered and validated independently. In-house PBMC genome-wide SNP genotyping data, miRNA expression data and DNA methylation data in the same sample were utilized to identify SNPs [expression quantitative trait locus (eQTLs) and protein quantitative trait locus (pQTLs)], miRNAs, and DNA methylation positions (DMPs) regulating key DEG of interest. Lentivirus transfection was conducted to study the effects of RPN2 on T lymphocyte activation, proliferation, apoptosis, and inflammatory cytokine expression. Rpn2 protein level in plasma was quantitated by ELISA to assess its performance in discriminating RA cases and controls.

RESULTS

Twenty-two DEGs were discovered in PBMCs. The most significant DEG, i.e., RPN2, was validated to be up-regulated with RA in PBMCs. A complex regulatory network for RPN2 gene expression in PBMCs was constructed, which consists of 38 eQTL and 53 pQTL SNPs, 3 miRNAs and 2 DMPs. Besides, RPN2 expression was significantly up-regulated with RA in primary T lymphocytes, as well as in PHA-activated T lymphocytes. RPN2 over-expression in T lymphocytes significantly inhibited apoptosis and IL-4 expression and promoted proliferation and activation. PBMCs-expressed RPN2 mRNA and plasma Rpn2 protein demonstrated superior and modest performances in discriminating RA cases and controls, respectively.

CONCLUSIONS

RPN2 gene influences T lymphocyte growth and activation and is involved in the pathogenesis of RA. Rpn2 may serve as a novel protein biomarker for RA diagnosis.

New potential therapeutic approaches targeting synovial fibroblasts in rheumatoid arthritis

Synovial cells play a key role in joint destruction during chronic inflammation. In particular, activated synovial fibroblasts (SFs) undergo intrinsic alterations leading to an aggressive phenotype mediating cartilage destruction and bone erosion in rheumatoid arthritis (RA). Recent research has revealed a number of targets to control arthritogenic changes in SFs. Therefore, identification of SF phenotypes, control of epigenetic changes, modulation of cellular functions, or regulation of the activity of cation channels and different signaling pathways has been investigated. Although many of these approaches have shown efficacy in vitro and in animal models of RA, further research is needed to select the most relevant targets for drug development. This review is focused on the role of SFs as a potential strategy to discover novel therapeutic targets in RA aimed at preserving joint architecture and function.

Immunopathophysiology of Juvenile Spondyloarthritis (jSpA): The "Out of the Box" View on Epigenetics, Neuroendocrine Pathways and Role of the Macrophage Migration Inhibitory Factor (MIF)

Juvenile spondyloarthritis (jSpA) is a an umbrella term for heterogeneous group of related seronegative inflammatory disorders sharing common symptoms. Although it mainly affects children and adolescents, it often remains active during adulthood. Genetic and environmental factors are involved in its occurrence, although the exact underlying immunopathophysiology remains incompletely elucidated. Accumulated evidence suggests that, in affected patients, subclinical gut inflammation caused by intestinal dysbiosis, is pivotal to the future development of synovial-entheseal complex inflammation. While the predominant role of IL17/23 axis, TNF-α, and IL-7 in the pathophysiology of SpA, including jSpA, is firmly established, the role of the cytokine macrophage migration inhibitory factor (MIF) is generally overlooked. The purpose of this review is to discuss and emphasize the role of epigenetics, neuroendocrine pathways and the hypothalamic-pituitary (HPA) axis, and to propose a novel hypothesis of the role of decreased NLRP3 gene expression and possibly MIF in the early phases of jSpA development. The decreased NLRP3 gene expression in the latter, due to hypomethylation of promotor site, is (one of) the cause for inflammasome malfunction leading to gut dysbiosis observed in patients with early jSpA. In addition, we highlight the role of MIF in the complex innate, adaptive cellular and main effector cytokine network, Finally, since treatment of advanced bone pathology in SpA remains an unmet clinical need, I suggest possible new drug targets with the aim to ultimately improve treatment efficacy and long-term outcome of jSpA patients.

Dysregulation of ribosome-related genes in ankylosing spondylitis: a systems biology approach and experimental method

Background

Ankylosing spondylitis (AS) is an autoimmune rheumatic disease. Few candidate gene associations have been reported for AS and the current understanding of its pathogenesis remains still poor. Thus, the exact mechanism of AS is needed to urgently be disclosed. The purpose of this study was to identify candidate genes involving in AS disease.

Methods and results

GSE25101 publicly available microarray and GSE117769 RNA-seq datasets of AS patients were obtained for bioinformatics analyses. Gene set enrichment analysis showed that in the microarray dataset, the ribosome pathway was significantly up-regulated in AS compared with controls. Furthermore, some ribosomal components demonstrated overexpression in patients in the RNA-seq dataset. To confirm the findings, 20 AS patients and 20 matching controls were selected from the Rheumatology Research Center clinic, Shariati Hospital. PBMCs were separated from whole blood and RNA contents were extracted. Following the results of datasets analysis, the expression level of rRNA5.8S pseudogene, rRNA18S pseudogene, RPL23, RPL7, and RPL17 genes were measured through real-time PCR. Our findings showed dysregulation of rRNA5.8S and rRNA18S pseudogenes, and also the RPL17 gene in patients.

Conclusion

Considering that genes involved in ribosome biogenesis contributed to some AS-associated biological processes as well as diseases that have comorbidities with AS, our results might advance our understanding of the pathological mechanisms of ankylosing spondylitis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04662-2.

Risk factors for diagnosis of psoriatic arthritis, psoriasis, rheumatoid arthritis, and ankylosing spondylitis: A set of parallel case-control studies

OBJECTIVE

To compare potential risk factors for the diagnosis of psoriatic arthritis (PsA), psoriasis, rheumatoid arthritis (RA), and ankylosing spondylitis (AS).

METHODS

Four parallel case-control studies were conducted within The Health Improvement Network using data between 1994 and 2015. Patients with PsA, psoriasis, RA, or AS were identified using validated code lists and matched to controls on age, sex, practice, and year. Risk factors were selected in the time prior to diagnosis. Multivariable logistic regression models were constructed for each disease using automated stepwise regression to test potential risk factors.

RESULTS

Patients with incident PsA (N=7,594), psoriasis (N=111,375), RA (N=28,341), and AS (N=3, 253) were identified and matched to 75,930, 1,113,345, 282,226, and 32,530 controls, respectively. Median diagnosis age was 48 (IQR 38-59), 41 (31-54), 43 (31-54), and 60 (48-71), respectively. In multivariable models, there were some shared and some differing risk factors across all 4 diseases: PsA was associated with obesity, pharyngitis, and skin infections; PsA and psoriasis were associated with obesity and moderate alcohol intake; PsA and AS were associated with uveitis; and PsA and RA were associated with preceding gout. Both RA and AS were associated with current smoking, former moderate drinking, anemia, osteoporosis, and inflammatory bowel disease. All shared former or current smoking as a risk factor; statin use was inversely associated with all 4 diseases.

CONCLUSION

Shared and different risk factors for PsA, psoriasis, RA, and AS were identified. Statin use was inversely associated with all 4 conditions.

Tuning Monocytes and Macrophages for Personalized Therapy and Diagnostic Challenge in Rheumatoid Arthritis

Monocytes/macrophages play a central role in chronic inflammatory disorders, including rheumatoid arthritis (RA). Activation of these cells results in the production of various mediators responsible for inflammation and RA pathogenesis. On the other hand, the depletion of macrophages using specific antibodies or chemical agents can prevent their synovial tissue infiltration and subsequently attenuates inflammation. Their plasticity is a major feature that helps the switch from a pro-inflammatory phenotype (M1) to an anti-inflammatory state (M2). Therefore, understanding the precise strategy targeting pro-inflammatory monocytes/macrophages should be a powerful way of inhibiting chronic inflammation and bone erosion. In this review, we demonstrate potential consequences of different epigenetic regulations on inflammatory cytokines production by monocytes. In addition, we present unique profiles of monocytes/macrophages contributing to identification of new biomarkers of disease activity or predicting treatment response in RA. We also outline novel approaches of tuning monocytes/macrophages by biologic drugs, small molecules or by other therapeutic modalities to reduce arthritis. Finally, the importance of cellular heterogeneity of monocytes/macrophages is highlighted by single-cell technologies, which leads to the design of cell-specific therapeutic protocols for personalized medicine in RA in the future.

Marker Genes Change of Synovial Fibroblasts in Rheumatoid Arthritis Patients

Background

Rheumatoid arthritis (RA) is a chronic condition that manifests as inflammation of synovial joints, leading to joint destruction and deformity.

Methods

We identified single-cell RNA-seq data of synovial fibroblasts from RA and osteoarthritis (OA) patients in GSE109449 dataset. RA- and OA-specific cellular subpopulations were identified, and enrichment analysis was performed. Further, key genes for RA and OA were obtained by combined analysis with differentially expressed genes (DEGs) between RA and OA in GSE56409 dataset. The diagnostic role of key genes for RA was predicted using receiver operating characteristic (ROC) curve. Finally, we identified differences in immune cell infiltration between RA and OA patients, and utilized flow cytometry, qRT-PCR, and Western blot were used to examine the immune cell and key genes in RA patients.

Results

The cluster 0 matched OA and cluster 3 matched RA and significantly enriched for neutrophil-mediated immunity and ECM receptor interaction, respectively. We identified 478 DEGs. In the top 20 degrees of connection in the PPI network, the key genes for RA were obtained by comparing with the gene markers of cluster 0 and cluster 3, respectively. ROC curve showed that CCL2 and MMP13 might be diagnostic markers for RA. We found aberrant levels of CD8+T, neutrophil, and B cells in RA fibroblasts, which were validated in clinical samples. Importantly, we also validated the differential expression of key genes between RA and OA.

Conclusion

High expression of CCL2 and MMP13 in RA may be a diagnostic and therapeutic target.

m6A RNA Methylation in Systemic Autoimmune Diseases-A New Target for Epigenetic-Based Therapy?

The general background of autoimmune diseases is a combination of genetic, epigenetic and environmental factors, that lead to defective immune reactions. This erroneous immune cell activation results in an excessive production of autoantibodies and prolonged inflammation. During recent years epigenetic mechanisms have been extensively studied as potential culprits of autoreactivity. Alike DNA and proteins, also RNA molecules are subjected to an extensive repertoire of chemical modifications. N6-methyladenosine is the most prevalent form of internal mRNA modification in eukaryotic cells and attracts increasing attention due to its contribution to human health and disease. Even though m6A is confirmed as an essential player in immune response, little is known about its role in autoimmunity. Only few data have been published up to date in the field of RNA methylome. Moreover, only selected autoimmune diseases have been studied in respect of m6A role in their pathogenesis. In this review, I attempt to present all available research data regarding m6A alterations in autoimmune disorders and appraise its role as a potential target for epigenetic-based therapies.

Sorafenib suppresses proliferation rate of fibroblast-like synoviocytes through the arrest of cell cycle in experimental adjuvant arthritis

OBJECTIVES

Rheumatoid arthritis, a recurrent incendiary autoimmune joint syndrome, features by prominent synovial hyperplasia. Fibroblast-like synoviocytes are the executive components in the pathogenesis of rheumatoid arthritis. It is generally accepted that excessive proliferation and reduced apoptosis of fibroblast-like synoviocytes lead to synovial hyperplasia. Our previously studies found that sorafenib could inhibit adjuvant arthritis in rats and induced adjuvant arthritis fibroblast-like synoviocytes apoptosis. Presently, we aim to investigate the inhibitory effect with mechanisms of action of sorafenib on adjuvant arthritis fibroblast-like synoviocytes proliferation.

METHODS

Cell counting kit-8 and flow cytometry detection were conducted to monitor FLSs proliferation and cell cycle. Western blotting and qPCR assays were performed to detect P21, P53, CDK4, CyclinD1 and proliferating cell nuclear antigen content levels.

KEY FINDINGS

Sorafenib significantly inhibited adjuvant arthritis fibroblast-like synoviocytes proliferation with an IC50 value of 4 µmol/L by a concentration-dependent pattern, which accompanies by G1 cell cycle arrest. Also, sorafenib significantly decreased the levels of P21, CyclinD1, CDK4 and proliferating cell nuclear antigen, as well as up-regulated P53 expression in adjuvant arthritis fibroblast-like synoviocytes.

CONCLUSIONS

Sorafenib could inhibit adjuvant arthritis fibroblast-like synoviocytes proliferation via arresting G1/S cell cycle progression, which was partially through CDK4/CyclinD1-mediated pathway, as well as up-regulating P53 and down-regulating proliferating cell nuclear antigen expressions. These results suggest that sorafenib may provide a new paradigm for rheumatoid arthritis treatment.

Sexual Dimorphism in the Expression of Pain Phenotype in Preclinical Models of Rheumatoid Arthritis

Rheumatoid arthritis is one of most frequent rheumatic diseases, affecting around 1% of the population worldwide. Pain impacting the quality of life for the patient with rheumatoid arthritis, is often the primary factor leading them to seek medical care. Although sex-related differences in humans and animal models of rheumatoid arthritis are described, the correlation between pain and sex in rheumatoid arthritis has only recently been directly examined. Here we review the literature and explore the mechanisms underlying the expression of the pain phenotype in females and males in preclinical models of rheumatoid arthritis.

Biologic Drugs for Rheumatoid Arthritis in the Context of Biosimilars, Genetics, Epigenetics and COVID-19 Treatment

Rheumatoid arthritis (RA) affects around 1.2% of the adult population. RA is one of the main reasons for work disability and premature retirement, thus substantially increasing social and economic burden. Biological disease-modifying antirheumatic drugs (bDMARDs) were shown to be an effective therapy especially in those rheumatoid arthritis (RA) patients, who did not adequately respond to conventional synthetic DMARD therapy. However, despite the proven efficacy, the high cost of the therapy resulted in limitation of the widespread use and unequal access to the care. The introduction of biosimilars, which are much cheaper relative to original drugs, may facilitate the achievement of the therapy by a much broader spectrum of patients. In this review we present the properties of original biologic agents based on cytokine-targeted (blockers of TNF, IL-6, IL-1, GM-CSF) and cell-targeted therapies (aimed to inhibit T cells and B cells properties) as well as biosimilars used in rheumatology. We also analyze the latest update of bDMARDs' possible influence on DNA methylation, miRNA expression and histone modification in RA patients, what might be the important factors toward precise and personalized RA treatment. In addition, during the COVID-19 outbreak, we discuss the usage of biologicals in context of effective and safe COVID-19 treatment. Therefore, early diagnosing along with therapeutic intervention based on personalized drugs targeting disease-specific genes is still needed to relieve symptoms and to improve the quality of life of RA patients.

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).

Metformin inhibits inflammation and bone destruction in collagen-induced arthritis in rats

Background

Metformin (MF) is a widely used biguanide oral hypoglycemic agent, which has obvious anti-inflammatory and immunomodulatory effects. However, the mechanism of MF on rheumatoid arthritis (RA) remains uncertain. In this study, we investigated the therapeutic effects of MF on collagen-induced arthritis (CIA).

Methods

CIA was induced in rats by intradermal injection of a mixture of bovine type II collagen and incomplete Freund's adjuvant (IFA) on day 0 and day 7 through the base of the tail. Intraperitoneal injection of MF (100 mg/kg) was given every 3 days, from day 14 for 3 weeks. The effects of MF on arthritis-induced systemic inflammation and synovitis were studied by pathological analysis of the knee joint and serological examination of peripheral blood in CIA rats. The bone protection effect of MF was studied by microscopic computed tomography (micro-CT) and histological analysis of the knee joint. The effects of MF on chondrocytes in CIA rats were studied by detecting the relevant pro-apoptotic mediators in the chondrocytes.

Results

After administration of MF in CIA rats, systemic inflammation and synovitis caused by arthritis were significantly suppressed. Histomorphometry and micro-CT analysis of the knee joint revealed that MF can protect bone by inhibiting the changes of trabecular bone in CIA rats. Histological analysis of the knee joint found that MF can inhibit osteoclast formation and degradation of the cartilage layer matrix. Detection of the relevant pro-apoptotic mediators in chondrocytes revealed that MF can significantly inhibit the apoptosis of chondrocytes in CIA rats.

Conclusions

Our study showed that MF can inhibit systemic inflammation and synovitis and plays a role in bone protection by inhibiting cartilage layer matrix degradation, osteoclast formation, and chondrocyte apoptosis.

The Impact of Epstein-Barr Virus Infection on Juvenile Idiopathic Arthritis Activity and Patient's Response to Treatment

This study aimed to investigate the relationship between Epstein-Barr virus (EBV) infection and the onset of juvenile idiopathic arthritis (JIA), disease activity, and response to treatment. The study included 44 children with JIA, 23 children with different types of arthritis, and 44 controls. We measured EBV infection markers, including the EBV DNA load and the concentration of antibodies to viral antigens, at disease onset, before treatment. Six months after JIA diagnosis and the initiation of treatment patients with anti-viral capsid antigen IgG had a higher disease activity and worse response to treatment than patients without previous infection. After six months of treatment, the probability of disease inactivity in children without a history of EBV infection was almost 6.5 times greater than in a child with a history of infection. Furthermore, the probability of a better response after six months of treatment in a child with a history of EBV infection was more than five times smaller than in a child without infection. A past EBV infection can have a negative effect on achieving disease remission and may be associated with a worse response to treatment. Our results do not indicate the need for routine assessment of EBV infection markers in patients with JIA.

Tackling the autoimmune side in Spondyloarthritis: A systematic review

Spondyloarthritis (SpA) are a heterogeneous group of inflammatory chronic diseases characterized by sharing common pathogenic, clinical and radiologic features. The aim of this review is to support clinicians in understanding and managing this complex disease, from pathogenesis to therapeutic targets, through a systematic review of the current literature in accordance with PRISMA guidelines and checklist. HLA-B27 has been found to be associated with axial involvement either in SA and in PsA patients: it might be involved through presentation of an "arthritogenic peptide" to autoreactive CD8+ T cells or might accumulate in misfolded form and induce production pro-inflammatory cytokines by binding to several innate immune receptors. This genetic background in combination with mechanical stress leads to the activation of both innate and acquired immune responses as well as a possible role of autoimmunity in SpA pathogenesis. The release of IL-23 and IL-17 is relevant for their systemic and local effect on bone, inducing the activation of osteoclasts. Thus, the regulatory role of IL-17 on fibroblasts, osteoblasts and chondrocytes has an impact in both synovial inflammation and joint destruction. Innovative therapies targeting IL-12/23 and IL-17 and the use of small targeted synthetic molecules, as JAK-inhibitors, proved to be effective in SpA patients representing an alternative strategy to TNF-inhibitors.

Restoring synovial homeostasis in rheumatoid arthritis by targeting fibroblast-like synoviocytes

Rheumatoid arthritis (RA) is a chronic immune-mediated disease that primarily affects the synovium of diarthrodial joints. During the course of RA, the synovium transforms into a hyperplastic invasive tissue that causes destruction of cartilage and bone. Fibroblast-like synoviocytes (FLS), which form the lining of the joint, are epigenetically imprinted with an aggressive phenotype in RA and have an important role in these pathological processes. In addition to producing the extracellular matrix and joint lubricants, FLS in RA produce pathogenic mediators such as cytokines and proteases that contribute to disease pathogenesis and perpetuation. The development of multi-omics integrative analyses have enabled new ways to dissect the mechanisms that imprint FLS, have helped to identify potential FLS subsets with distinct functions and have identified differences in FLS phenotypes between joints in individual patients. This Review provides an overview of advances in understanding of FLS biology and highlights omics approaches and studies that hold promise for identifying future therapeutic targets.

The epigenetic face of lupus: Focus on antigen-presenting cells

In recent years, epigenetic mechanisms became widely known due to their ability to regulate and maintain physiological processes such as cell growth, development, differentiation and genomic stability. When dysregulated, epigenetic mechanisms, may introduce gene expression changes and disturbance in immune homeostasis leading to autoimmune diseases. Systemic lupus erythematosus (SLE), the most extensively studied autoimmune disorder, has already been correlated with epigenetic modifications, especially in T cells. Since these cell rely on antigen presentation, it may be assumed that erroneous activity of antigen-presenting cells (APCs), culminates in T cell abnormalities. In this review we summarize and discuss the epigenetic modifications in SLE affected APCs, with the focus on dendritic cells (DCs), B cells and monocytes. Unravelling this aspect of SLE pathogenesis, might result in identification of new disease biomarkers and putative therapeutic approaches.

Clinical epigenetics: seizing opportunities for translation

Biomarker discovery and validation are necessary for improving the prediction of clinical outcomes and patient monitoring. Despite considerable interest in biomarker discovery and development, improvements in the range and quality of biomarkers are still needed. The main challenge is how to integrate preclinical data to obtain a reliable biomarker that can be measured with acceptable costs in routine clinical practice. Epigenetic alterations are already being incorporated as valuable candidates in the biomarker field. Furthermore, their reversible nature offers a promising opportunity to ameliorate disease symptoms by using epigenetic-based therapy. Thus, beyond helping to understand disease biology, clinical epigenetics is being incorporated into patient management in oncology, as well as being explored for clinical applicability for other human pathologies such as neurological and infectious diseases and immune system disorders.

The 4-H of Biomarkers in Arthritis: A Lot of Help, Occasional Harm, Some Hype, Increasing Hope

(Gilles Boire): It was both a pleasure and an honor to present the 2019 Dunlop-Dottridge Lecture. My co-author and I will now discuss benefits and pitfalls of biomarkers developed through emerging techniques, evaluated through the experiential perspective of a seasoned clinician, as they apply to the quest for biomarker identification in rheumatic diseases.

Insights into rheumatic diseases from next-generation sequencing

Rheumatic diseases have complex aetiologies that are not fully understood, which makes the study of pathogenic mechanisms in these diseases a challenge for researchers. Next-generation sequencing (NGS) and related omics technologies, such as transcriptomics, epigenomics and genomics, provide an unprecedented genome-wide view of gene expression, environmentally responsive epigenetic changes and genetic variation. The integrated application of NGS technologies to samples from carefully phenotyped clinical cohorts of patients has the potential to solve remaining mysteries in the pathogenesis of several rheumatic diseases, to identify new therapeutic targets and to underpin a precision medicine approach to the diagnosis and treatment of rheumatic diseases. This Review provides an overview of the NGS technologies available, showcases important advances in rheumatic disease research already powered by these technologies and highlights NGS approaches that hold particular promise for generating new insights and advancing the field.

Histone Deacetylase Inhibitors Dose-Dependently Switch Neutrophil Death from NETosis to Apoptosis

Acetylation is an important post translational modification of histone that plays a role in regulation of physiological and pathological process in the body. We have recently shown that the inhibition of histone deacetylases (HDAC) by low concentrations of HDAC inhibitors (HDACis), belinostat (up to 0.25 µM) and panobinostat (up to 0.04 µM) promote histone acetylation (e.g., AcH4) and neutrophil extracellular trap formation (NETosis). Clinical use of belinostat and panobinostat often leads to neutropenia and the in vivo concentrations vary with time and tissue locations. However, the effects of different concentrations of these HDACis on neutrophil death are not fully understood. We considered that increasing concentrations of belinostat and panobinostat could alter the type of neutrophil death. To test this hypothesis, we treated human neutrophils with belinostat and panobinostat in the presence or absence of agonists that promote NOX-dependent NETosis (phorbol myristate acetate or lipopolysaccharide from Escherichia coli 0128) and NOX-independent NETosis (calcium ionophores A23187 or ionomycin from Streptomyces conglobatus). Increasing concentrations of HDACis induced histone acetylation in a dose-dependent manner. ROS analyses showed that increasing concentrations of HDACis, increased the degree of NOX-derived ROS production. Higher levels (>1 µM belinostat and >0.2 µM panobinostat) of AcH4 resulted in a significant inhibition of spontaneous as well as the NOX-dependent and -independent NETosis. By contrast, the degree of neutrophil apoptosis significantly increased, particularly in non-activated cells. Collectively, this study establishes that increasing concentrations of belinostat and panobinostat initially increases NETosis but subsequently reduces NETosis or switches the form of cell death to apoptosis. This new information indicates that belinostat and panobinostat can induce different types of neutrophil death and may induce neutropenia and regulate inflammation at different concentrations.

Metformin inhibits the proliferation of rheumatoid arthritis fibroblast-like synoviocytes through IGF-IR/PI3K/AKT/m-TOR pathway

Rheumatoid arthritis (RA) is a chronic autoimmune disease in which synovial fibroblast-like cells (FLSs) play an important role in RA development and is known to be lack of effective therapy. Thus, novel therapeutic strategies are greatly needed for treatment of RA. Metformin, a first-line drug for the treatment of type 2 diabetes, has been reported to inhibit the proliferation of a variety of tumor cells. In this study, we demonstrated that metformin could inhibit the RA-FLS proliferation in dose- and time-dependent manner. Our cell viability MTT test and 5-ethynyl-2-deoxyuridine incorporation assay showed that metformin inhibited the RA-FLSs proliferation with a time- and concentration-dependent increase. More importantly, metformin induced G2/M cell cycle phase arrest in RA-FLS via the IGF-IR/PI3K/AKT/ m-TOR pathway and inhibited m-TOR phosphorylation through both the IGF-IR/PI3K/AKT signaling pathways thereby further upregulating and down-regulating p70s6k and 4E-BP1 phosphorylation, respectively; however, metformin was found not to induce apoptosis in RA-FLSs. In summary, these results demonstrate that metformin can effectively inhibit RA-FLS proliferation through inducing cell cycle and upregulating and down-regulating p70s6k and 4E-BP1 phosphorylation. Moreover, IGF-IR/PI3K/AKT m-TOR signaling pathway can be regulated by metformin. Our results indicate that metformin may provide a new way of thinking for the treatment of RA.