Rheumatoid Arthritis Synovial Cells Research Articles

Loss of synovial tissue macrophage homeostasis precedes rheumatoid arthritis clinical onset.

This study performed an in-depth investigation into the myeloid cellular landscape in the synovium of patients with rheumatoid arthritis (RA), "individuals at risk" of RA, and healthy controls (HC). Flow cytometric analysis demonstrated the presence of a CD40-expressing CD206+CD163+ macrophage population dominating the inflamed RA synovium, associated with disease activity and treatment response. In-depth RNA sequencing and metabolic analysis demonstrated that this macrophage population is transcriptionally distinct, displaying unique inflammatory and tissue-resident gene signatures, has a stable bioenergetic profile, and regulates stromal cell responses. Single-cell RNA sequencing profiling of 67,908 RA and HC synovial tissue cells identified nine transcriptionally distinct macrophage clusters. IL-1B+CCL20+ and SPP1+MT2A+ are the principal macrophage clusters in RA synovium, displaying heightened CD40 gene expression, capable of shaping stromal cell responses, and are importantly enriched before disease onset. Combined, these findings identify the presence of an early pathogenic myeloid signature that shapes the RA joint microenvironment and represents a unique opportunity for early diagnosis and therapeutic intervention.

Discovery of CYP2E1 as a novel target in rheumatoid arthritis and validation by a new specific CYP2E1 inhibitor

Considerable evidence indicates that CYP2E1 is associated with a variety of inflammatory diseases. Here we evaluated CYP2E1 as a potential therapeutic target for rheumatoid arthritis (RA) and established the protective effect of a new CYP2E1 inhibitor. Gene-expression datasets were used to analyze the change in expression of CYP2E1 in RA patients; CYP2E1 activity in collagen-induced arthritis (CIA) rats was determined by HPLC. We further evaluated the protective effects of Cyp2e1 knockout and a CYP2E1-specific inhibitor, Q11, synthesized by our group, in CIA and adjuvant-induced arthritis (AIA) rats. The expression of CYP2E1 in synovial tissue was elevated in RA patients and in CIA rats and the activity of CYP2E1 in vivo and in vitro in CIA rats was greater than that of controls. Cyp2e1 knockout significantly reduced the incidence of CIA and alleviated the severity of symptoms. Treatment with different doses of Q11 decreased paw thickness, volume and arthritis scores and reduced the serum levels of IL‐6, TNF‐α, IL‐1β and MDA, and increased the level of GSH in CIA rats. A similar inhibitory effect was exhibited for Q11 in the AIA rats. Moreover, Q11 significantly impeded proliferation, migration, and invasion of human rheumatoid arthritis synovial fibroblasts cells. Q11 decreased the release of ROS and enhanced Nrf2 nuclear translocation and HO-1 expression in the cell nucleus. Overall, our results indicated that CYP2E1 may be a new target for RA and Q11 has potential protective effects against RA by reducing oxidative stress and opposing the inflammatory response via the ROS/Nrf2/HO-1 signaling pathway.

Enhanced Pharmacokinetics of Celastrol via Long-Circulating Liposomal Delivery for Intravenous Administration.

Rheumatoid Arthritis (RA) involves prolonged inflammation of the synovium, damaging joints and causing stiffness and deformity. Celastrol (Cel), derived from the Chinese herbal medicine Tripterygium wilfordii Hook F, offers immunosuppressive effects for RA treatment but is limited by poor solubility and bioavailability. In this study, long-circulating Cel-loaded liposomes (Cel-LPs) were used to increase the pharmacokinetics of Cel, thereby improving drug delivery and efficacy for the treatment of RA. Cel-LPs were prepared and administered orally and intravenously to compare the elimination half-life of drugs and bioavailability of Cel. Cel-LPs were prepared using the lipid thin-layer-hydration-extrusion method. Human rheumatoid arthritis synovial (MH7A) cells were used to investigate the compatibility of Cel-LPs. The pharmacokinetic studies were performed on male Sprague-Dawley (SD) rats. The Cel-LPs had an average size of 72.20 ± 27.99 nm, a PDI of 0.267, a zeta potential of -31.60 ± 6.81 mV, 78.77 ± 5.69% drug entrapment efficiency and sustained release (5.83 ± 0.42% drug loading). The cytotoxicity test showed that liposomes had excellent biocompatibility and the fluorescence microscope diagram indicated that liposome entrapment increased intracellular accumulation of Rhodamine B by MH7A cells. Furthermore, the results exhibited that Cel-LPs improved the pharmacokinetics of Cel by increasing the elimination half-life (t1/2) to 11.71 hr, mean residence time (MRT(0-∞)) to 7.98 hr and apparent volume of distribution (Vz/F) to 44.63 L/kg in rats, compared to the Cel solution. In this study, liposomes were demonstrated to be effective in optimizing the delivery of Cel, enabling the formulation of Cel-LPs with prolonged blood circulation and sustained release characteristics. This formulation enhanced the intravenous solubility and bioavailability of Cel, developing a foundation for its clinical application in RA and providing insights on poorly soluble drug management.

The Association of Myostatin on the Expression of Inflammatory Cytokines and Chemokines in Rheumatoid Arthritis Synovial Fibroblasts

Rheumatoid arthritis (RA) is a chronic autoimmune disease initiated and progressed by RA synovial fibroblast cells (RASFs) of the synovium. Inflammatory cytokines/chemokines play a crucial role in disease development. Myostatin (MSTN) is widely comprehended as a significant regulator of pro-inflammatory cytokines/chemokines in many other autoimmune diseases. However, its role during the progression of RA is still unclear. We hypothesized that MSTN regulates the inflammatory cytokines/chemokines expression in RASFs. The immortalized RASF cells (MH7A) were treated with MSTN or MSTN inhibitor (0, 10, and 20 ng/mL) for 0, 24, and 48 h. Then, the secretion and expression of inflammatory cytokines (IL-8, IL-17, TNF-α, IL-6, IL-23, IFN-γ, IFN-β) and chemokines (CCL-2, CCL-20, CXCL-13, CXCL-1) were measured by enzyme-linked immunosorbent assay (ELISA) and reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Furthermore, MH7A cells were treated with 20 ng/mL of TNF-α, IL-17, IFN-γ IFN-β, CCL-2, and CXCL-1 for 24 h to examine their effects on MSTN expression and secretion. Data were analyzed by Kruskal-Wallis rank sum test, followed by Dunn’s multiple comparison test. The MSTN expression and secretion were measured by RT-qPCR, ELISA, and Western blot. Results showed that 20 ng/mL MSTN treatment significantly (p<0.05) increased the secretion of most inflammatory cytokines/chemokines at 24 or 48 h. CXCL-1 showed the highest secretion (30-fold in average) in response to MSTN treatment, followed by CCL-2 (13-fold in average) at 24 h and IL-23 (3-fold in average) at 48 h. Similar to ELISA results, MSTN significantly upregulated the mRNA expression of most inflammatory cytokines/chemokines at 24 or 48 h. The highest expression was TNF-α (60-fold in average) at 48 h, followed by CXCL-1 (15-fold in average) and CCL-2 (13-fold in average) at 24 h. The effect of MSTN inhibitor on cytokines/chemokines secretion and mRNA expression was inconsistent. Among the six cytokines/chemokines used to investigate their effects on MSTN expression in MH7A cells, IFN-γ significantly increased MSTN secretion (13-fold in average) and mRNA expression (100-fold in average) but other cytokine/chemokines showed no significant response. Western blot results showed that MSTN secretion was significantly increased by IFN-γ treatment, supporting the ELISA results. Current results demonstrated that MSTN upregulated the mRNA expression and secretion of various inflammatory cytokines/chemokines and IFN-γ significantly increased MSTN expression and secretion, indicating a cross-stimulation between MSTN and inflammatory cytokines/chemokines in RA. This study was funded by NIH 5R01AR043521-29. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

CD14+ Dendritic-Shaped Cells Functioning as Dendritic Cells in Rheumatoid Arthritis Synovial Tissues.

We previously reported that CD14+ dendritic-shaped cells exhibit a dendritic morphology, engage in pseudo-emperipolesis with lymphocytes, and express CD90 in the perivascular areas of rheumatoid arthritis (RA) synovial tissues. However, it remains unclear whether these CD14highCD90intermediate(int) cells function as dendritic cells. In this study, we investigated the dendritic cell-differentiation potential of CD14highCD90int cells. The localization and number of CD14highCD90int cells in RA synovial tissues and peripheral blood were examined. The dendritic cell-differentiation potential of CD14highCD90int cells was examined by measuring interleukin-6 and tumor necrosis factor-α levels in the supernatant and CD83 and human leukocyte antigen (HLA)-DR expression in the cells after induction of dendritic cell differentiation. Synovial cells were co-cultured with lymphocytes, and the activation of these cells was examined. CD14highCD90int cells were abundant in RA synovial tissues, including the sublining layer and the pannus areas. Patients with untreated and active RA had significantly higher percentages of CD14highCD90int cells in the peripheral blood and synovial tissues. In RA synovial cells, inflammatory cytokine levels increased with dendritic cell-differentiation culture, but CD83 and HLA-DR expression were significantly increased in the CD14highCD90int cell group. When co-cultured with lymphocytes, cell numbers and inflammatory cytokine levels significantly increased in both groups of synovial cells after dendritic cell induction. CD14+ cells migrate and spread from the circulating blood to RA synovial tissues while expressing CD90, and CD14highCD90int cells in contact with lymphocytes differentiate into HLA-DR+ dendritic cells, which contribute to chronic inflammation in RA.

Targeting TNF-α-induced expression of TTR and RAGE in rheumatoid arthritis: Apigenin's mediated therapeutic approach

BackgroundRheumatoid arthritis (RA) is a chronic inflammatory disease induced by TNF-α, which increases fibroblast-like synoviocytes inflammation, resulting in cartilage destruction. The current work sought to comprehend the pathophysiological importance of TNF-α stimulation on differential protein expression and their regulation by apigenin using in-vitro and in-vivo models of RA. MethodsThe human RA synovial fibroblast cells were stimulated with or without TNF-α (10 ng/ml) and treated with 40 μM apigenin. In-silico, in-vitro and in-vivo studies were performed to confirm the pathophysiological significance of apigenin on pro-inflammatory cytokines and on differential expression of TTR and RAGE proteins. ResultsTNF-α induced inflammatory response in synoviocytes revealed higher levels of IL-6, IL-1β, and TNF-α cytokines and upregulated differential expression of TTR and RAGE. In-silico results demonstrated that apigenin has a binding affinity towards TNF-α, indicating its potential effect in the inflammatory process. Both in-vitro and in-vivo results obtained by Western Blot analysis suggested that apigenin reduced the level of p65 (p = 0.005), TTR (p = 0.002), and RAGE (p = 0.020). ConclusionThe findings of this study suggested that TNF-α promotes the differential expression of pro-inflammatory cytokines, TTR, and RAGE via NF-kB pathways activation. Anti-inflammatory effect of apigenin impedes TNF-α mediated dysregulation or expression associated with RA pathogenesis.

New biflavonoids isolated from Xylia kerrii leaves extract with selective cytotoxicity against MH7A human rheumatoid arthritis synovial fibroblast cells.

Three new biflavonoids (1-3) and two known flavonoids (4, 5) were isolated from Xylia kerrii collected in Thailand. Compounds 1-5 showed selective cytotoxicity against the rheumatoid fibroblast-like synovial MH7A cell line, and these compounds showed weak cytotoxicity against the human lung synovial fibroblast WI-38 VA13 sub 2 RA cell line. Notably, compound 1 was highly selective toward MH7A cells with an IC50 value of 6.9μM, whereas the IC50 value for WI-38 VA13 sub 2 RA cells was > 100μM. The western blotting analysis of MH7A cells treated with compound 1 showed increased CDKN2A /p16INK4A and caspase-8 levels.

Associations Between Rheumatoid Arthritis Clinical Factors and Synovial Cell Types and States.

Recent studies have uncovered diverse cell types and states in the rheumatoid arthritis (RA) synovium; however, limited data exist correlating these findings with patient-level clinical information. Using the largest cohort to date with clinical and multicell data, we determined associations between RA clinical factors with cell types and states in the RA synovium. The Accelerated Medicines Partnership Rheumatoid Arthritis study recruited patients with active RA who were not receiving disease-modifying antirheumatic drugs (DMARDs) or who had an inadequate response to methotrexate (MTX) or tumor necrosis factor inhibitors. RA clinical factors were systematically collected. Biopsies were performed on an inflamed joint, and tissue were disaggregated and processed with a cellular indexing of transcriptomes and epitopes sequencing pipeline from which the following cell type percentages and cell type abundance phenotypes (CTAPs) were derived: endothelial, fibroblast, and myeloid (EFM); fibroblasts; myeloid; T and B cells; T cells and fibroblasts (TF); and T and myeloid cells. Correlations were measured between RA clinical factors, cell type percentage, and CTAPs. We studied 72 patients (mean age 57 years, 75% women, 83% seropositive, mean RA duration 6.6 years, mean Disease Activity Score-28 C-reactive Protein 3 [DAS28-CRP3] score 4.8). Higher DAS28-CRP3 correlated with a higher T cell percentage (P < 0.01). Those receiving MTX and not a biologic DMARD (bDMARD) had a higher percentage of B cells versus those receiving no DMARDs (P < 0.01). Most of those receiving bDMARDs were categorized as EFM (57%), whereas none were TF. No significant difference was observed across CTAPs for age, sex, RA disease duration, or DAS28-CRP3. In this comprehensive screen of clinical factors, we observed differential associations between DMARDs and cell phenotypes, suggesting that RA therapies, more than other clinical factors, may impact cell type/state in the synovium and ultimately influence response to subsequent therapies.

Exploring the mechanism of Celastrol in the treatment of rheumatoid arthritis based on systems pharmacology and multi-omics

To explore the molecular network mechanism of Celastrol in the treatment of rheumatoid arthritis (RA) based on a novel strategy (integrated systems pharmacology, proteomics, transcriptomics and single-cell transcriptomics). Firstly, the potential targets of Celastrol and RA genes were predicted through the database, and the Celastrol-RA targets were obtained by taking the intersection. Then, transcriptomic data and proteomic data of Celastrol treatment of RA were collected. Subsequently, Celastrol-RA targets, differentially expressed genes, and differentially expressed proteins were imported into Metascape for enrichment analysis, and related networks were constructed. Finally, the core targets of Celastrol-RA targets, differentially expressed genes, and differentially expressed proteins were mapped to synoviocytes of RA mice to find potential cell populations for Celastrol therapy. A total of 195 Celastrol-RA targets, 2068 differential genes, 294 differential proteins were obtained. The results of enrichment analysis showed that these targets, genes and proteins were mainly related to extracellular matrix organization, TGF-β signaling pathway, etc. The results of single cell sequencing showed that the main clusters of these targets, genes, and proteins could be mapped to RA synovial cells. For example, Mmp9 was mainly distributed in Hematopoietic cells, especially in Ptprn+fibroblast. The results of molecular docking also suggested that Celastrol could stably combine with molecules predicted by network pharmacology. In conclusion, this study used systems pharmacology, transcriptomics, proteomics, single-cell transcriptomics to reveal that Celastrol may regulate the PI3K/AKT signaling pathway by regulating key targets such as TNF and IL6, and then play an immune regulatory role.

The FTO-CMPK2 Pathway in Fibroblast-like Synoviocytes Modulates Rheumatoid Arthritis Synovial Inflammation and Cartilage Homeostasis via mtDNA Regulation.

In rheumatoid arthritis (RA), a debilitating autoimmune disorder marked by chronic synovial inflammation and progressive cartilage degradation, fibroblast-like synoviocytes (FLS) are key pathogenic players. Current treatments targeting these cells are limited. Our study focused on the Fat Mass and Obesity-associated protein (FTO), known for its roles in cell proliferation and inflammatory response modulation, and its involvement in RA. We specifically examined the inflammatory regulatory roles of FTO and CMPK2, a mitochondrial DNA synthesis protein, in FLS. Utilizing a combination of in vitro and in vivo methods, including FTO inhibition and gene knockdown, we aimed to understand FTO's influence on RA progression and chondrocyte functionality. Our findings showed that increased FTO expression in RA synovial cells enhanced their proliferation and migration and decreased senescence and apoptosis. Inhibiting FTO significantly slowed the disease progression in our models. Our research also highlighted that the FTO-CMPK2 pathway plays a crucial role in regulating synovial inflammation through the mtDNA-mediated cGAS/STING pathway, affecting chondrocyte homeostasis. This study indicates that targeting the FTO-CMPK2 axis could be a promising new therapeutic strategy for managing RA.

Metabolic reprogramming by Syntenin-1 directs RA FLS and endothelial cell-mediated inflammation and angiogenesis.

A novel rheumatoid arthritis (RA) synovial fluid protein, Syntenin-1, and its receptor, Syndecan-1 (SDC-1), are colocalized on RA synovial tissue endothelial cells and fibroblast-like synoviocytes (FLS). Syntenin-1 exacerbates the inflammatory landscape of endothelial cells and RA FLS by upregulating transcription of IRF1/5/7/9, IL-1β, IL-6, and CCL2 through SDC-1 ligation and HIF1α, or mTOR activation. Mechanistically, Syntenin-1 orchestrates RA FLS and endothelial cell invasion via SDC-1 and/or mTOR signaling. In Syntenin-1 reprogrammed endothelial cells, the dynamic expression of metabolic intermediates coincides with escalated glycolysis along with unchanged oxidative factors, AMPK, PGC-1α, citrate, and inactive oxidative phosphorylation. Conversely, RA FLS rewired by Syntenin-1 displayed a modest glycolytic-ATP accompanied by a robust mitochondrial-ATP capacity. The enriched mitochondrial-ATP detected in Syntenin-1 reprogrammed RA FLS was coupled with mitochondrial fusion and fission recapitulated by escalated Mitofusin-2 and DRP1 expression. We found that VEGFR1/2 and Notch1 networks are responsible for the crosstalk between Syntenin-1 rewired endothelial cells and RA FLS, which are also represented in RA explants. Similar to RA explants, morphological and transcriptome studies authenticated the importance of VEGFR1/2, Notch1, RAPTOR, and HIF1α pathways in Syntenin-1 arthritic mice and their obstruction in SDC-1 deficient animals. Consistently, dysregulation of SDC-1, mTOR, and HIF1α negated Syntenin-1 inflammatory phenotype in RA explants, while inhibition of HIF1α impaired synovial angiogenic imprint amplified by Syntenin-1. In conclusion, since the current therapies are ineffective on Syntenin-1 and SDC-1 expression in RA synovial tissue and blood, targeting this pathway and its interconnected metabolic intermediates may provide a novel therapeutic strategy.

Hederagenin inhibits proliferation, angiogenesis and inflammation of fibroblast-like synovial cells in rheumatoid arthritis

Purpose: To determine the effect of Hederagenin (Hed) on rheumatoid arthritis (RA) in a cell model, and to elucidate the mechanism of action of Hed.&#x0D; Methods: MTT, EDU, and Immunoblot assays were used to determine the effects of Hed on the viability of fibroblast-like synovial cells, while the effects of Hed on inflammation were examined by enzymelinked immunosorbent assay (ELISA) and immunoblot assay. The influence of Hed on cell motility angiogenesis was evaluated by Transwell and tube formation assays, while immunoblot analysis was used to determine the mechanism of action of Hed.&#x0D; Results: Hed inhibited the viability of RA-FLS cells and suppressed the inflammation of RA-FLS cells (p &lt; 0.05). Furthermore, Hed suppressed the migration and angiogenesis of RA-FLSl cells, as well as regulated MAPK pathway (p &lt; 0.05).&#x0D; Conclusion: Hed inhibits the proliferation, angiogenesis and inflammation of fibroblast-like synovial cells in RA by regulating MAPK pathway. Therefore, Hed is a drug for the treatment of RA, However, in vivo studies to validate these findings are recommended

Autoreactive B cells against malondialdehyde-induced protein cross-links are present in the joint, lung, and bone marrow of rheumatoid arthritis patients

Autoantibodies to malondialdehyde (MDA) proteins constitute a subset of anti-modified protein autoantibodies in rheumatoid arthritis (RA), which is distinct from citrulline reactivity. Serum anti-MDA IgG levels are commonly elevated in RA and correlate with disease activity, CRP, IL6, and TNF-α. MDA is an oxidation-associated reactive aldehyde that together with acetaldehyde mediates formation of various immunogenic amino acid adducts including linear MDA-lysine, fluorescent malondialdehyde acetaldehyde (MAA)-lysine, and intramolecular cross-linking. We used single-cell cloning, generation of recombinant antibodies (n= 356 from 25 donors), and antigen-screening to investigate the presence of class-switched MDA/MAA+ B cells in RA synovium, bone marrow, and bronchoalveolar lavage. Anti-MDA/MAA+ B cells were found in bone marrow plasma cells of late disease and in the lung of both early disease and risk-individuals and in different B cell subsets (memory, double negative B cells). These were compared with previously identified anti-MDA/MAA from synovial memory and plasma cells. Seven out of eight clones carried somatic hypermutations and all bound MDA/MAA-lysine independently of protein backbone. However, clones with somatic hypermutations targeted MAA cross-linked structures rather than MDA- or MAA-hapten, while the germline-encoded synovial clone instead bound linear MDA-lysine in proteins and peptides. Binding patterns were maintained in germline converted clones. Affinity purification of polyclonal anti-MDA/MAA from patient serum revealed higher proportion of anti-MAA versus anti-MDA compared to healthy controls. In conclusion, IgG anti-MDA/MAA show distinct targeting of different molecular structures. Anti-MAA IgG has been shown to promote bone loss and osteoclastogenesis invivo and may contribute to RA pathogenesis.

Regulatory effect of zinc finger protein A20 on rheumatoid arthritis through NLRP3/Caspase-1 signaling axis mediating pyroptosis of HFLS- RA cells.

As a chronic inflammatory autoimmune disease, rheumatoid arthritis (RA) causes significant destruction to joints and cartilage. So far, from RA patients, the synovial cells and subsynovial tissues reflected the positive expression of IL-18, IL-1β, Caspase-1 and NLRP3, with the synovial tissues of those patients also expressing the zinc finger protein A20 at a significantly lower level compared with osteoarthritis (OA) ones. Thus, the inhibition of the NLRP3/caspase-1 signaling pathway can effectively down-regulate the expression of IL-1β, but when NLRP3 inflammasomes are activated, they can also shear GSDMD and induce pyroptosis. These suggest that the Gasdermin family of proteins, downstream of the NLRP3 inflammasome, could be involved in pyroptosis. Previous studies have shown that A20 contributes largely as an anti-inflammatory factor in many inflammatory diseases, but it remains unclear whether zinc finger protein A20, as an inhibitor of NLRP3 inflammasomes, can play a protective role against RA by inhibiting NLRP3 inflammasome-mediated pyroptosis. Therefore, this study aimed to verify the effects of zinc finger protein A20 on NLRP3/ Caspase-1-mediated pyroptosis in rheumatoid arthritis synovial fibroblasts (HFLS-RA) cells through cell experiments and clinical bidirectional verification, aim to understand the regulatory mechanism of A20 on RA. The results of clinical trials showed that NLRP3, Caspase-1, IL-1β and IL-18 were positively scattered in RA synovial cells and subsynovial tissue. The expression level of the zinc finger protein A20 in RA synovial tissues was significantly lower than that in OA synovial tissue and was negative, while zinc finger protein A20 was strongly positive in OA synovial tissue. In addition, HFLS-RA cells with siRNA-interfering zinc finger protein A20 were constructed at the cellular level, with the results also confirming that zinc finger protein A20 can play a protective role against RA by inhibiting NLRP3 inflammasome-mediated pyroptosis. In conclusion, this study is of great significance for understanding the role of the NLRP3-caspase-1-IL-1β/ pyroptosis signaling pathway in the occurrence and development of RA. It is expected that the results will provide a theoretical basis for the immune regulation of innate immunity in the occurrence and development of RA, while providing a new therapeutic target for the clinical treatment of RA.

Tocilizumab suppresses NF-kappa B activation via toll-like receptor 9 signaling by reducing cell-free DNA in rheumatoid arthritis.

Endogenous DNA is released into the bloodstream as cell-free DNA (cfDNA) following cell death and is associated with various pathological conditions. However, their association with therapeutic drugs against rheumatoid arthritis (RA) remains unknown. Therefore, we investigated the significance of cfDNA in RA treated with tocilizumab and tumour necrosis factor inhibitor (TNF-I). Biological DMARDs (bDMARDs), including tocilizumab and TNF-I, were administered to 77 and 59 RA patients, respectively. Plasma cfDNA levels were measured at weeks 0, 4, and 12 by quantitative polymerase chain reaction. Disease activity was evaluated at the same time point using DAS28ESR. cfDNA levels from RA synovial cells treated with tocilizumab or etanercept for 24 h were measured. Human toll-like receptor 9 (hTLR9)-expressing HEK293 cells, which release secreted embryonic alkaline phosphatase (SEAP) upon NF-κB activation, were stimulated by cfDNA from RA patients, and subsequently, SEAP levels were determined. NF-κB translocation was evaluated by immunofluorescence staining with or without tocilizumab. The DAS28ESR significantly improved in both bDMARD groups at week 12. However, plasma cfDNA levels significantly decreased in the tocilizumab group at week 12 compared to that in week 0. cfDNA levels correlated with DAS28ESR in biological treatment-naïve patients administered tocilizumab. cfDNA levels in synovial cells were significantly suppressed by tocilizumab treatment and unaltered with etanercept. HEK293 cells released SEAP upon cfDNA stimulation, and the observed NF-κB nuclear translocation was suppressed by tocilizumab. Tocilizumab suppressed inflammation via the TLR9 pathway by decreasing cfDNA levels. Regulation of cfDNA may be a therapeutic target for RA.

SPTBN1 attenuates rheumatoid arthritis synovial cell proliferation, invasion, migrationand inflammatory response by binding to PIK3R2.

As an autoimmune systemic disorder, rheumatoid arthritis (RA) features chronic inflammation as well as synovial infiltration of immune cells. This study was designed with the purpose of discussing the hidden mechanism of SPTBN1 and exploring favorable molecular-targeted therapies. With the application of RT-qPCR and western blot, the expressions of SPTBN1 and PIK3R2 before or after transfection were estimated. Besides, Cell Counting Kit-8, Edu, wound healing, transwell, enzyme-linked immunosorbent assay, and TUNEL were adopted for the evaluation of the viability, proliferation, migration, invasion, inflammatory response, and apoptosis of fibroblast-like synoviocyte (FLS). In addition, the interaction of SPTBN1 and PIK3R2 was testified by applying immunoprecipitation (IP) and western blot was utilized for the assessment of migration-, apoptosis-, and PI3K/AKT signal-related proteins. It was discovered that SPTBN1 declined in RA synovial cells and its overexpression repressed the proliferation, migration, invasion, and inflammation of RA-FLSs but promoted apoptosis. IP confirmed that SPTBN1 could bind to PIK3R2 in FLSs. To further figure out the hidden mechanism of SPTBN1 in RA, a series of functional experiments were carried out and the results demonstrated that the reduced expressions of MMP2, MMP9, IL-8, IL-1β, IL-6, and Bcl2 as well as increased levels of Bax and cleaved caspase3 in SPTBN1-overexpressed RA-FLSs were reversed by PIK3R2 depletion, revealing that SPTBN1 repressed the migration and inflammation and promoted the apoptosis of RA-FLSs via binding to PIK3R2. Results obtained from western blot also revealed that PIK3R2 interference ascended the contents of p-PI3K and p-AKT in SPTBN1-overexpressed RA-FLSs, implying that SPTBN1 repressed PI3K/AKT signal in RA via PIK3R2. SPTBN1 alleviated the proliferation, migration, invasion, and inflammation in RA via interacting with PIK3R2.

Orientin inhibits the progression of fibroblast-like synovial cells in rheumatoid arthritis by regulating MAPK-signaling pathway.

Natural compounds are found to play an essential role in diverse inflammatory diseases, including rheumatoid arthritis (RA). Orientin, a flavonoid compound, is closely related to diverse pathological processes. Nevertheless, the role of orientin in RA is still unknown. The cell viability was tested through cell counting kit 8 (CCK-8) assay, and the number of cell colonies was calculated via colony formation assay. In addition, flow cytometry assay was employed to detect apoptosis rate in human RA fibroblast-like synoviocytes (RA-FLS). Besides, Transwell assay was introduced to determine cell migratory and invasive abilities. Moreover, the level of cytokines (IL-8, IL-1β, and IL-6) was estimated with quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent serologic assay. Furthermore, western blotting analysis was used to test the protein levels of cleaved-caspase-3, Bax, BCL-2, matrix metalloproteinase (MMP)-2, MMP-9, phosphorylated c-Jun N-terminal kinase, p-P38, and phospho-extracellular signal-related kinase. Orientin inhibited cell viability, migration as well as invasion in a concentration- dependent manner in human RA-FLS. Additionally, treatment of orientin facilitated apoptosis and decreased the secretion of cytokines induced by tumor necrosis factor alpha (TNF-α) in human RA-FLS. Moreover, orientin inactivated mitogen-activated protein kinase (MAPK)-related signaling pathway, notably in human RA-FLS. These findings confirmed that orientin inhibited human RA-FLS development and decreased TNF-α-induced inflammatory factors, at least partly, by modulating MAPK-signaling pathway, which implied that orientin might be an effective agent for treating RA.

Panlongqi Tablet (PLQT) Inhibits LPS-Induced Abnormal Proliferation of RA-HFLS by Regulating PI3K/ AKT and MAPK Signaling Pathways

Panlongqi Tablet (PLQT), a traditional Chinese formula, is effective in the clinical treatment of Rheumatoid Arthritis (RA) in China for several decades. However, the underlying mechanism of PLQT’s therapeutic effect remains unclear. The main chemical constituents of PLQT were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The human fibroblast-like synovial cells in rheumatoid arthritis (RA-HFLS) were stimulated with LPS (10 μg/mL) to establish a inflammatory model in vitro. The cells were then treated with PLQT-medicated serum to verify the protective effect of the herbal compound. MTT assay was used to detect the viability of RAHFLS and abnormal cell proliferation. The inflammatory factors levels including interleukin-1β (IL-1β), interleukin-6 (IL-6), and interleukin-17 (IL-17) in RAHFLS were measured by ELISA. In addition, the cell cycle progression was analyzed by flow cytometry and protein expression of Proliferating Cell Nuclear Antigen (PCNA) was detected using immunohistochemistry and western blot. The protein expression levels associated with PI3K/AKT and MAPK signaling pathways in RA-HFLS were detected by western blot analyses. Our results revealed that PLQT treatment effectively inhibited the abnormal proliferation of RA-HFLS and decreased the inflammatory factors levels. The proportion of cells in S phase was significantly increased with the treatment of PLQT. Meanwhile, the expression levels of PCNA, p-PI3K, p-AKT, p-mTOR, p-JNK/JNK, p-ERK/ ERK, and p-P38/P38 proteins from RA-HFLS were dramatically inhibited by PLQT treatment. PLQT inhibits LPS-induced abnormal proliferation of RAHFLS, which may be related to the down regulation of PCNA, and the inhibition of abnormally activated PI3K/AKT and MAPK signaling pathways.

SLAMF8 promotes the proliferation and migration of synovial fibroblasts by regulating the ERK/MMPs signalling pathway

Rheumatoid arthritis is troublesome to treat effectively and often requires concomitant long-term treatment. Meanwhile, synovial fibroblasts could induce inflammation response and lead to joint erosion, finally causing progressive joint destruction, disability, and increased mortality. This study focussed on the role of SLAM family member 8 (SLAMF8) in mediating cell function from rheumatoid arthritis synovial fibroblasts stimulated with TNF-α. Cell Counting Kit-8 (CCK-8) and colony-forming unit assay were used to evaluate cell proliferation. SLAMF8 expression was analysed by reverse transcription-quantitative PCR (RT-qPCR) and western blot. Annexin V‐FITC/PI double staining was used to measure the apoptosis rate. The cell migration and invasion in TNF-α-stimulated MH7A (human rheumatoid arthritis synovial cell line) and HFLS-RA cells (human fibroblast-like synoviocytes: rheumatoid arthritis) were tested via wound healing assay and transwell migration assay. In the present study, after TNF-α treatments, the SLAMF8 mRNA and protein expression in both MH7A and HFLS-RA cell lines have a time-dependent increase. The attenuation of SLAMF8 ameliorated TNF-α-induced proliferation, invasion and migration in MH7A and HFLS-RA cells. Simultaneously, when SLAMF8 was silenced, the expression of p-ERK, MMP-1, and MMP-13 was suppressed significantly. In summary, these results indicated that the knockdown of the SLAMF8 significantly attenuated TNF-α-induced proinflammatory responses in MH7A and HFLS-RA cells. Therefore, SLAMF8 exhibits therapeutic potential for the management of inflammation in rheumatoid arthritis.

Association of CD90 Expression by CD14+ Dendritic-Shaped Cells in Rheumatoid Arthritis Synovial Tissue With Chronic Inflammation.

ObjectiveCD14+ dendritic‐shaped cells show a dendritic morphology under the electron microscopy and engage in a pseudoemperipolesis phenomenon with lymphocytes. CD90 has been used as a marker of a major subset of fibroblast‐like synoviocytes in rheumatoid arthritis (RA). In this study, we investigated the significance of CD90 expression in CD14+ dendritic‐shaped cells and its correlation with RA chronic inflammation.MethodsDouble immunofluorescence staining for CD14 and CD90 was performed in the collected tissues, including 12 active RA synovial tissues. The localization of CD14+CD90+ cells, the percentages of CD14+CD90+ cells and vascular areas, the degree of synovitis, and clinical data were investigated. Furthermore, CD14+CD90+ cells analyzed by flow cytometry (CD14highCD90intermediate (int) cells) were sorted from RA synovial cells, and we examined their potential to differentiate into dendritic cells.ResultsDouble immunofluorescence staining showed that CD14+CD90+ cells were abundant in RA synovial tissues. The percentages of CD14+CD90+ cells and vascular areas correlated with some of the Krenn synovitis scores, but neither showed a strong correlation with RA disease activity parameters. Flow cytometry analysis indicated that CD14highCD90int cells were more abundant in both peripheral blood samples and synovial tissues in patients with active RA. CD14highCD90int cells were more likely to differentiate into dendritic cells in vitro.ConclusionCD14+ dendritic‐shaped cells expressed CD90 in the perivascular areas of RA synovial tissues. These findings suggest that CD14+CD90+ dendritic‐shaped cells migrate from the peripheral blood to the synovial tissue, the site of inflammation, and may contribute to the chronic inflammation of RA as dendritic progenitor cells.