Inflammatory Response In Rheumatoid Arthritis Research Articles

Myricetin reduces neutrophil extracellular trap release in a rat model of rheumatoid arthritis, which is associated with a decrease in disease severity.

Rheumatoid arthritis (RA) is a chronic disease characterized by joint inflammation and severe disability. However, there is a lack of safe and effective drugs for treating RA. In our previous study, we discovered that myricetin (MC) and celecoxib have a synergistic effect in the treatment of RA. We conducted in vitro and in vivo experiments to further investigate the effects and mechanisms of action of MC. Our findings demonstrated that MC treatment effectively reduced the release of neutrophil extracellular traps (NETs) and alleviated the inflammatory response in RA. Mechanistic studies showed that MC prevents the entry of PADI4 and MPO into the cell nucleus, thereby protecting DNA from decondensation. In a rat arthritis model, MC improved histological changes in ankle joints and suppressed NET-related signaling factors. In conclusion, MC protects the ankle joints against arthritis by inhibiting MPO and PADI4, thereby reducing NET release. The pharmacological mechanism of MC in RA involves the inhibition of NET release.

Discovery and validation of anti-arthritic ingredients and mechanisms of Qingfu Juanbi Tang, a Chinese herbal formulation, on rheumatoid arthritis

Ethnopharmacological relevanceQingfu Juanbi Tang (QFJBT), a novel and improved Chinese herbal formulation, has surged in recent years for its potential in the therapy of rheumatoid arthritis (RA). Anti-arthritic effects and underlying molecular mechanisms of QFJBT have increasingly become a focal point in research. Aim of the studyThis study utilized network pharmacology, molecular docking, and experimental validation to elucidate effective ingredients and anti-arthritic mechanisms of QFJBT. Materials and methodsTargets associated with QFJBT and RA were identified from relevant databases and standardized using the Uniprot for gene nomenclature. A “QFJBT-ingredient-target network” and a “Venn diagram of QFJBT and RA targets” were created from the data. The overlap in the Venn diagram highlighted potential targets of QFJBT in the treatment of RA. These targets were subjected to PPI network, GO, and KEGG pathway analysis. The findings were subsequently confirmed through molecular docking and pharmacological experiments to propose the mechanism of action of QFJBT. ResultsThe study identified 236 active ingredients in QFJBT, with 120 predicted to be effective against RA. Molecular docking showed high binding affinity of key targets (JUN, PTGS2, and TNF-α) with bioactive compounds (rhein, sinomenine, calycosin, and paeoniflorin) of QFJBT. Pharmacodynamic evaluation demonstrated the effects of QFJBT at the dose of 4.56 g/kg in ameliorating symptoms of AIA rats and in reducing levels of JUN, PTGS2, and TNF-α in synovial tissues. In vitro studies further exhibited that rhein, paeoniflorin, sinomenine, calycosin, and QFJBT-containing serum significantly inhibited abnormal proliferation of RA fibroblast-like synoviocytes. Interestingly, rhein and paeoniflorin specifically decreased p-JUN/JUN expression and TNF-α release, respectively, while sinomenine and calycosin selectively increased PTGS2 expression. Consistently, QFJBT-containing serum demonstrated similar effects as those active ingredients identified in QFJBT did. ConclusionsQFJBT, QFJBT-containing serum, and its active ingredients (rhein, paeoniflorin, sinomenine, and calycosin) suppress inflammatory responses in RA. Anti-arthritic effects of QFJBT and its active ingredients are likely linked to their modulatory impact on identified hub targets.

LncRNA HOTTIP regulates TLR4 promoter methylation by recruiting H3K4 methyltransferase MLL1 to affect apoptosis and inflammatory response of fibroblast-like synoviocyte in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease, and the role of HOXA transcript at the distal tip (HOTTIP) in its pathogenesis remains underexplored. This study investigates the mechanism by which HOTTIP influences apoptosis and the inflammatory response of fibroblast-like synoviocytes (FLS). An RA mouse model was established, and clinical scores were analyzed. Pathological changes in synovial tissues, bone mineral density (BMD) of the paws, serum tartrate-resistant acid phosphatase (TRAP) activity, and TNF-α and IL-1β levels were assessed. FLS were transfected, and cell proliferation and apoptosis were examined. The RNA-pull-down assay determined HOTTIP's interaction with mixed-lineage leukemia 1 (MLL1), while RNA immunoprecipitation assay measured HOTTIP expression pulled down by MLL1. The levels of MLL1 and toll-like receptor 4 (TLR4) after MLL1 overexpression based on HOTTIP silencing were determined. Chromatin immunoprecipitation (ChIP) was performed with H3K4me3 as an antibody, followed by the evaluation of TLR4 expression. HOTTIP expression was elevated in RA mouse synovial tissues. Inhibition of HOTTIP led to reduced clinical scores, inflammatory infiltration, synovial hyperplasia, TRAP activity, and TNF-α and IL-1β levels, along with increased BMD. In vitro Interference with HOTTIP suppressed RA-FLS apoptosis and inflammation. HOTTIP upregulated TLR4 expression by recruiting MLL1 to facilitate TLR4 promoter methylation. MLL1 overexpression reversed HOTTIP silencing-mediated repression of RA-FLS apoptosis. Activation of H3K4 methylation counteracted HOTTIP knockout, ameliorating the inflammatory response. HOTTIP regulates TLR4 expression by recruiting MLL1, leading to TLR4 promoter methylation, thereby suppressing RA-FLS proliferation and inducing cell apoptosis and inflammatory response in RA.

A novel 3D spheroid model of rheumatoid arthritis synovial tissue incorporating fibroblasts, endothelial cells, and macrophages.

Rheumatoid Arthritis (RA) is a progressive and systemic autoimmune disorder associated with chronic and destructive joint inflammation. The hallmarks of joint synovial inflammation are cellular proliferation, extensive neoangiogenesis and infiltration of immune cells, including macrophages. In vitro approaches simulating RA synovial tissue are crucial in preclinical and translational research to evaluate novel diagnostic and/or therapeutic markers. Two-dimensional (2D) settings present very limited in vivo physiological proximity as they cannot recapitulate cell-cell and cell-matrix interactions occurring in the three-dimensional (3D) tissue compartment. Here, we present the engineering of a spheroid-based model of RA synovial tissue which mimics 3D interactions between cells and pro-inflammatory mediators present in the inflamed synovium. Spheroids were generated by culturing RA fibroblast-like-synoviocytes (RAFLS), human umbilical vein endothelial cells (ECs) and monocyte-derived macrophages in a collagen-based 3D scaffold. The spheroids were cultured in the presence or absence of vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (bFGF) or RA synovial fluid (SF). Spheroid expansion and cell migration were quantified for all conditions using confocal microscopy and digital image analysis. A novel approach using machine learning was developed to quantify spheroid outgrowth and used to reexamine the existing spheroid-based model of RA synovial angiogenesis consisting of ECs and RAFLS. A 2-fold increase in the spheroid outgrowth ratio was demonstrated upon VEGF/bFGF stimulation (p<0.05). The addition of macrophages within the spheroid structure (3.75x104 RAFLS, 7.5x104 ECs and 3.0x104 macrophages) resulted in good incorporation of the new cell type. The addition of VEGF/bFGF significantly induced spheroid outgrowth (p<0.05) in the new system. SF stimulation enhanced containment of macrophages within the spheroids. We present a novel spheroid based model consisting of RAFLS, ECs and macrophages that reflects the RA synovial tissue microenvironment. This model may be used to dissect the role of specific cell types in inflammatory responses in RA, to study specific signaling pathways involved in the disease pathogenesis and examine the effects of novel diagnostic (molecular imaging) and therapeutic compounds, including small molecule inhibitors and biologics.

Extracellular aaRSs drive autoimmune and inflammatory responses in rheumatoid arthritis via the release of cytokines and PAD4

ObjectivesRecent studies demonstrate that extracellular-released aminoacyl-tRNA synthetases (aaRSs) play unique roles in immune responses and diseases. This study aimed to understand the role of extracellular aaRSs in the pathogenesis of...

The elucidation of the anti-inflammatory mechanism of EMO in rheumatoid arthritis through an integrative approach combining bioinformatics and experimental verification.

Introduction: Emodin (EMO), a natural derivative of the anthraquinone family mainly extracted from rhubarb (Rheum palmatum), has previously been demonstrated to possess superior anti-inflammatory properties from a single target or pathway. In order to explore the underlying mechanism of action of EMO against rheumatoid arthritis (RA), a network pharmacology approach was employed. Methods: A gene expression profile from GSE55457 available from the Gene Expression Omnibus (GEO) database was used to identify the targets of EMO action. Further, single cell RNA sequencing data from GEO database of RA patients (GSE159117) were downloaded and analysed. To further investigate the anti-RA effect of EMO on MH7A cells, the expression of IL-6 and IL-1β were monitored. Finally, RNA-seq analyses were conducted on synovial fibroblasts from EMO-treated. Result: We screened the key targets of EMO against RA using network pharmacology methods, including HMGB1, STAT1, EGR1, NR3C1, EGFR, MAPK14, CASP3, CASP1, IL4, IL13, IKBKB and FN1, and their reliability was verified using ROC curve. Single-cell RNA sequencing data analysis showed that these core target proteins mainly played a role by modulating monocytes. The anti-RA effect of EMO was further verified with MH7A cells, which showed that EMO could block cell differentiation and reduce the expression of IL-6 and IL-1β. WB experiments confirmed that EMO could affect the expression of COX2, HMBG1 and the phosphorylation of p38. Finally, sequencing of synovial fibroblasts from rats treated with EMO showed consistent results with those predicted and verified, further proving the anti-inflammatory effect of EMO. Conclusion: Our research shows that EMO inhibits inflammatory response of rheumatoid arthritis (RA) by targeting HMGB1, STAT1, EGR1, NR3C1, EGFR, MAPK14, CASP3, CASP1, IL4, IL13, IKBKB, FN1 and Monocytes/macrophages.

Sulforaphene targets NLRP3 inflammasome to suppress M1 polarization of macrophages and inflammatory response in rheumatoid arthritis.

This work aimed to explore the therapeutic effect and target of sulforaphene (LF) in mice with rheumatoid arthritis (RA). Lipopolysaccharide (LPS) and IFN-γ were added to induce the M1 polarization of SMG cells, and later cells were pretreated with 5 μM and 15 μM LF. M1 cell proportion was detected by flow cytometry (FCM), inflammatory factors were measured by enzyme-linked immunosorbent assay, and protein levels were analyzed by western blotting (WB) assay. Besides, small molecule-protein docking and pull-down assays were carried out to detect the binding of LF to NLRP3. After the knockdown of NLRP3 in SMG cells, the effect of LF was further detected. The RA mouse model was induced with collagen antibody and LPS, after LF intervention, H&E staining was performed to detect the pathological changes in mouse synovial membrane, whereas safranin O-fast green staining was performed to detect cartilage injury, NLRP3 inflammasome and inflammatory factor levels in tissues. LF suppressed M1 polarization of macrophages, reduced M1 cell proportion and inflammatory factor levels, and suppressed the activation of NLRP3 inflammasome. After NLRP3 knockdown, LF did not further suppress the M1 polarization of macrophages. Pull-down assay suggested that LF bound to NLRP3. As revealed by mouse experimental results, LF inhibited bone injury in mice, decreased M1 cell infiltration and inflammatory response in tissues, and inhibited NLRP3 inflammasome expression in tissues. LF targets NLRP3 to suppress the M1 polarization of macrophages and decrease tissue inflammation in RA.

An injectable hydrogel to disrupt neutrophil extracellular traps for treating rheumatoid arthritis

Rheumatoid arthritis (RA), an autoimmune disease, is characterized by inflammatory cell infiltration that damages cartilage, disrupts bone, and impairs joint function. The therapeutic efficacy of RA treatments with the severely affected side remains unsatisfactory despite current treatment methods that primarily focus on anti-inflammatory activity, largely because of the complicatedly pathological mechanisms. A recently identified mechanism for RA development involves the interaction of RA autoantibodies with various proinflammatory cytokines to facilitate the formation of neutrophil extracellular traps (NETs), which increased inflammatory responses to express inflammatory cytokines and chemokines. Therefore, NETs architecture digestion may inhibit the positive-feedback inflammatory signal pathway and lessen joint damage in RA. In this work, deoxyribonuclease I (DNase) is connected to oxidized hyaluronic acid (OHA) via Schiff base reaction to extend the half-life of DNase. The modification does not influence the DNase activity for plasmid deoxyribonucleic acid hydrolysis and NETs’ architecture disruption. Carboxymethyl chitosan is crosslinked with DNase-functionalised OHA (DHA) to form an injectable, degradable, and biocompatible hydrogel (DHY) to further strengthen the adhesive capability of DHA. Importantly, the collagen-induced arthritis model demonstrates that intra-articular injection of DHY can significantly reduce inflammatory cytokine expression and alleviate RA symptoms, which can be significantly improved by combining methotrexate. Here, a DNase-functionalised hydrogel has been developed for RA treatment by constantly degrading the novel drug target of NETs to decrease inflammatory response in RA.

Ca-DEX biomineralization-inducing nuts reverse oxidative stress and bone loss in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a common autoimmune disease, and the inflammatory response during its development can lead to joint cartilage and bone damage up to disability. Dexamethasone (DEX) can effectively alleviate the inflammatory response in RA, but the severe adverse effects that occur after its long-term administration limit its clinical development. Herein, we propose a Ca-DEX biomineralization-inducing nut (CaCO3-DEX) with controlled release properties for mitigating the toxic side effects of DEX in RA treatment, especially the damage to cartilage and bone. CaCO3-DEX releases the drug and Ca2+ preferentially in an inflammatory environment. Both in vitro and in vivo studies demonstrate that CaCO3-DEX significantly reduces the secretion of pro-inflammatory factors and inhibits ROS production in vitro, as well as demonstrates superior pro-biomineralization and osteogenic differentiation potential. In the collagen-induced rheumatoid arthritis model (CIA model), CaCO3-DEX significantly reduces the clinical score of arthritis in mice, and the imaging results show a noticeable relief of edema and bone erosion in CIA model mice treated with CaCO3-DEX, while inflammatory factors at the injury areas are significantly reduced, which provides favorable protection to cartilage and bone.

Microbiome and Leaky Gut Syndrome as Extra-articular Factors for Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation of the joints and causes damage to cartilage and joints. Not only genetic factors but also environmental factors are involved in the development and progression of this disease. In particular, diet has a significant impact on the development and course of the disease. Therefore, the question of the impact of changes in the intestinal microbiome in patients with RA is relevant and debatable. Scientific evidence in recent decades suggests that dysbacteriosis affects the chronic inflammatory response in RA and can be modified. The next issue in the development and progression of RA is the integrity of the intestinal barrier. According to the latest scientific findings, changes in the intestinal barrier are one of the key factors in the pathogenesis of RA. The study of intestinal barrier damage has found the protein I FABP, which is a promising marker of change in intestinal permeability in patients with RA. Today, a large amount of data has been collected and new approaches to modification of the above aspects of RA pathogenesis are being investigated. In combination with standard therapy, they can potentially reduce the intensity of symptoms and ensure long-term remission. Changes in diet, addition of probiotics, products of bacterial metabolism (for example, butyrate), have a positive effect on disease activity. The addition of larazotide, a drug that affects the integrity of dense joints, can be used in the treatment of patients with RA. This article shows the prospects of modification of the microbiome and intestinal permeability in the treatment of patients with RA. Due to the limited amount of data, this area needs further research.

Role of m6A modification and novel circ_0066715/ miR-486-5p/ ETS1 axis in rheumatoid arthritis macrophage polarization progression.

Rheumatoid arthritis (RA) is a systemic disease dominated by inflammatory synovitis. RA synovial macrophages tend undergo M1-type macrophage polarization. Then, polarized M1-type macrophages secrete abundant pro-inflammatory cytokines, causing joint and cartilage destruction. N6-methyladenosine (m6A) methylation modification, circular RNA (circRNA), microRNA (miRNA), messenger RNA (mRNA), etc. are involved in the inflammatory response of RA. We found that there is an imbalance of inflammatory polarization in RA, which is manifested by a sharp increase in inflammatory markers and a high inflammatory response. Here, we show that RA was closely associated with low expression of circ_0066715. The overexpression of circ_0066715 significantly increased the ETS1 levels in RA-FLS cells, decreased cytokine secretion by M1-type macrophages, elevated M2-type cytokines, and inhibited FLS proliferation. Interestingly, the overexpression of miR-486-5p significantly suppressed the attenuation of the cell function and the effect on M1 macrophage polarization caused by circ_0066715 positive expression. WTAP may be involved in the methylation process of ETS1 in RA. ETS1 m6A methylation levels were altered upon WTAP intervention. The overexpression or interference of circ_0066715 decreased or increased WTAP expression. Our findings provide a novel circRNA/miRNA/mRNA regulatory axis and m6A regulatory mechanism involved in the process of RA macrophage polarization, thereby providing a powerful diagnostic and therapeutic strategy for RA treatment.

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

BackgroundAs 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. ObjectiveThe current investigation was conducted to explore the anti-RA effects of MAG and to discover the possible molecular mechanisms. MethodsIn 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. ResultsMAG 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. ConclusionThese 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.

Exosomal MicroRNA-23-5p Derived from Bone Marrow Mesenchymal Stem Cells Relieves Inflammatory Response in Rheumatoid Arthritis

We aimed to explore the mechanism underlying microRNA-23-5p from exosomes (exo-miR-23-5p) of BMSCs in rheumatoid arthritis (RA). The candidate related genes of miR-23-5p were screened in RA by bioinformatics analysis through gain- and loss-function method along with analysis of histopathological changes in mice and RAC2 expression as well as the level of pro-inflammatory factors. In vivo RA model was established to detect miR-23-5p’s effect on RA. miR-23-5p level was significantly reduced in RA cells and RAC2 was highly expressed. Expression of RAC2 was inhibited and targeted by miR-23-5p in RA. Exo-miR-23-5p treatment effectively alleviated joint destruction, reduced inflammatory factor secretion in tissues and serum, as well as decreased RAC2 expression in RA model. In conclusion, the miR-23-5p in the BMSC-exo delays the inflammatory response in RA, indicating that it might be a new target for treating RA.

Epigenetic Regulation of Immune and Inflammatory Responses in Rheumatoid Arthritis.

PurposeRheumatoid arthritis (RA) is a disease associated with multiple factors. Epigenetics can affect gene expression without altering the DNA sequence. In this study, we aimed to comprehensively analyze epigenetic regulation in RA.MethodsUsing the Gene Expression Omnibus database, we identified a methylation chip, RNA-sequencing, and miRNA microarray for RA. First, we searched for DNA methylation, genes, and miRNAs associated with RA using differential analysis. Second, we determined the regulatory networks for RA-specific methylation, miRNA, and m6A using cross-analysis. Based on these three regulatory networks, we built a comprehensive epigenetic regulatory network and identified hub genes.ResultsUsing a differential analysis, we identified 16,852 differentially methylated sites, 4877 differentially expressed genes, and 32 differentially expressed miRNAs. The methylation-expression regulatory network was mainly associated with the PI3K-Akt and T-cell receptor signaling pathways. The miRNA expression regulatory network was mainly related to the MAPK and chemokine signaling pathways. M6A regulatory network was mainly associated with the MAPK signaling pathway. Additionally, five hub genes were identified in the epigenetic regulatory network: CHD3, SETD1B, FBXL19, SMARCA4, and SETD1A. Functional analysis revealed that these five genes were associated with immune cells and inflammatory responses.ConclusionWe constructed a comprehensive epigenetic network associated with RA and identified core regulatory genes. This study provides a new direction for future research on the epigenetic mechanisms of RA.

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.

B7-H3 blockade decreases macrophage inflammatory response and alleviates clinical symptoms of arthritis

Objective. The costimulatory molecule B7-H3 is an immunoregulatory protein, which is highly expressed in peripheral blood monocytes of rheumatoid arthritis (RA) patients and its expression is closely related to the clinical parameters of the disease. In this study we aimed to determine what the implication of high B7-H3 expression for the disease severity, and whether targeting this molecule could constitute a new therapeutic approach. Methods. In this study we analyzed B7-H3 expression on macrophage in human RA and mouse model of arthritis and assessed the function of B7-H3 in relation with the pro-inflammatory role of macrophage through small RNA interference. Then we studied the molecular pathways liking B7-H3 with TNF-α. The therapeutic benefit of anti-B7-H3 blocking was probed in mouse with CIA. Results. We found a positive correlation between expression of B7-H3 on macrophages and disease activities, pathological evaluation and pro-inflammatory cytokine TNF-α. Knocking down B7-H3 expression weakened the inflammatory response of the mouse mononuclear phagocytic cell. Further molecular analyses indicated that the regulation of the inflammatory response through B7-H3 involved NF-κB signaling. Treatment of CIA mice with anti-B7-H3 reduced the clinical manifestation of arthritis and downregulated the expression of pro-inflammatory cytokines. Conclusion. We confirmed increased expression of B7-H3 in arthritis and established a positive correlation between disease severity and expression of B7-H3 on macrophages. Through functional approaches in vitro and in vivo, we also demonstrated the therapeutic benefits of targeting B7-H3 for dampening macrophages’ inflammatory responses in RA.

The Effects of Non-Surgical Periodontitis Therapy on the Clinical Features and Serological Parameters of Patients Suffering from Rheumatoid Arthritis as Well as Chronic Periodontitis.

ObjectiveThe present study aims to evaluate the effects of basic periodontal disease therapy on the general condition and serum inflammatory indicators of patients with rheumatoid arthritis (RA) combined with chronic periodontitis (CP).MethodsForty patients with RA were enrolled in the study and, based on the results of an oral examination and in line with the 2018 periodontitis diagnostic criteria, they were divided into a group with CP (the RA + CP group) and a group without CP (the RA group). Twenty-nine patients with CP who attended the periodontal department of our hospital were recruited as a group with only CP (the CP group), and 20 volunteers without any systemic or periodontal disease were recruited as a healthy control group (the H group). The periodontal and joint conditions of the subjects in the four groups were recorded; anti-cyclic citrullinated protein antibodies, interleukin 6 (IL-6), C-reactive protein (CRP), the erythrocyte sedimentation rate (ESR), and rheumatoid factor levels, which reflect the severity of the RA, were detected, and the differences between the groups were analyzed. The probing depth (PD), clinical attachment loss, and sulcus bleeding index (SBI), which reflect the severity of the periodontitis, were correlated with the factor levels. The RA + CP and CP groups received therapeutic intervention, and the differences in each indicator before and six weeks after the treatment were compared, and their data were compared with those of patients in the RA group and H groups.ResultsCompared with the RA group, the serum expressions of ESR, CRP, and IL-6 were significantly higher in the RA + CP group. There were significant differences in the levels of PD, SBI, IL-6, and CRP in the patients receiving basic periodontal disease therapy before and after the treatment.ConclusionA relatively large proportion of patients with RA have chronic periodontitis, and the local inflammatory state of CP might exacerbate the systemic inflammatory response in RA. Basic periodontal disease therapy may improve the oral condition of patients with RA and reduce the serum levels of the inflammatory factors.

MiR-144-3p aggravated cartilage injury in rheumatoid arthritis by regulating BMP2/PI3K/Akt axis.

Present study aimed to illustrate the role of miR-144-3p in rheumatoid arthritis (RA). N1511 chondrocytes were stimulated by interleukin (IL)-1β to mimic RA injury model in vitro. Rats were subjected to injection of type II collagen to establish an in vivo RA model, and the arthritis index score was calculated. Cell viability was determined by Cell Counting Kit-8. The expression of cartilage extracellular matrix proteins (collagen II and aggrecan) and matrix metalloproteinase protein were determined by quantitative real-time polymerase chain reaction and western blots. Cell apoptosis was measured by flow cytometry. Enzyme-linked immunosorbent assay was applied to test the secretion of pro-inflammatory cytokines (IL-1β and tumour necrosis factor-α). Tissue injury and apoptosis were detected by haematoxylin-eosin staining and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling assay staining. Interaction of miR-144-3p and bone morphogenetic protein 2 (BMP2) was verified by dual-luciferase assay. miR-144-3p was dramatically increased in IL-1β-induced N1511 cells. miR-144-3p depletion elevated cell viability, suppressed apoptosis, pro-inflammatory cytokine releasing, and extracellular matrix loss in IL-1β-induced N1511 cells. Moreover, miR-144-3p targeted BMP2 to modulate its expression negatively. Activation of phosphatidylinositol 3-kinase (PI3K)/Akt signalling compromised inhibition of BMP2 induced aggravated N1511 cell injury with IL-1β stimulation. Inhibition of miR-144-3p alleviated cartilage injury and inflammatory in RA rats. Collectively, miR-144-3p could aggravate chondrocyte injury inflammatory response in RA via BMP2/PI3K/Akt axis.

Citrullinated human fibrinogen triggers arthritis through an inflammatory response mediated by IL-23/IL-17 immune axis

Rheumatoid arthritis (RA) is an autoimmune disease that causes joint destruction. Although its etiology remains unknown, citrullinated proteins have been considered as an auto-antigen able to trigger an inflammatory response in RA. Herein, we modified the classical antigen-induced arthritis (AIA) model by using citrullinated human plasma fibrinogen (hFIB) as an immunogen to investigate the mechanism of inflammation-driven joint damage by citrullinated hFIB in C57BL/6 mice. We found that hFIB-immunized mice showed high serum levels of anti-citrullinated peptides antibodies (ACPAs). Moreover, hFIB immunized mice showed increased mechanical hyperalgesia, massive leukocyte infiltration, high levels of inflammatory mediators, and progressive joint damage after the intra-articular challenge with citrullinated hFIB. Interestingly, hFIB-induced arthritis was dependent on IL-23/IL-17 immune axis-mediated inflammatory responses since leukocyte infiltration and mechanical hyperalgesia were abrogated in Il17ra−/− and Il23a−/− mice. Thus, we have characterized a novel model of experimental arthritis suitable to investigate the contribution of ACPAs and Th17 cell-mediated immune response in the pathogenesis of RA.

IRAK4 inhibitor mitigates joint inflammation by rebalancing metabolism malfunction in RA macrophages and fibroblasts

Recent studies show a connection between glycolysis and inflammatory response in rheumatoid arthritis (RA) macrophages (MΦs) and fibroblasts (FLS). Yet, it is unclear which pathways could be targeted to rebalance RA MΦs and FLS metabolic reprogramming. To identify novel targets that could normalize RA metabolic reprogramming, TLR7-mediated immunometabolism was characterized in RA MΦs, FLS and experimental arthritis. We uncovered that GLUT1, HIF1α, cMYC, LDHA and lactate were responsible for the TLR7-potentiated metabolic rewiring in RA MΦs and FLS, which was negated by IRAK4i. While in RA FLS, HK2 was uniquely expanded by TLR7 and negated by IRAK4i. Conversely, TLR7-driven hypermetabolism, non-oxidative PPP (CARKL) and oxidative phosphorylation (PPARγ) were narrowly dysregulated in TLR7-activated RA MΦs and FLS and was reversed by IRAK4i. Consistently, IRAK4i therapy disrupted arthritis mediated by miR-Let7b/TLR7 along with impairing a broad-range of glycolytic intermediates, GLUT1, HIF1α, cMYC, HK2, PFKFB3, PKM2, PDK1 and RAPTOR. Notably, inhibition of the mutually upregulated glycolytic metabolites, HIF1α and cMYC, was capable of mitigating TLR7-induced inflammatory imprint in RA MΦs and FLS. In keeping with IRAK4i, treatment with HIF1i and cMYCi intercepted TLR7-enhanced IRF5 and IRF7 in RA MΦs, distinct from RA FLS. Interestingly, in RA MΦs and FLS, IRAK4i counteracted TLR7-induced CARKL reduction in line with HIF1i. Whereas, cMYCi in concordance with IRAK4i, overturned oxidative phosphorylation via PPARγ in TLR7-activated RA MΦs and FLS. The blockade of IRAK4 and its interconnected intermediates can rebalance the metabolic malfunction by obstructing glycolytic and inflammatory phenotypes in RA MΦs and FLS.