Anti-Inflammatory Effects of TRAF-Interacting Protein in Rheumatoid Arthritis Fibroblast-Like Synoviocytes

TRAF5 regulates intestinal mucosal Th1/Th17 cell immune responses via Runx1 in colitis mice

Inflammatory bowel disease (IBD) is a chronic gastrointestinal inflammatory disease associated with CD4+ Th1 and Th17 cell immune responses. Tumour necrosis factor-associated factor 5 (TRAF5) deficiency has been shown to aggravate DSS-induced colitis. However, the potential role of TRAF5 in regulating CD4+ T cell immune responses in the pathogenesis of IBD remains unclear. TRAF5-/- CD4+ CD45RBhigh T cells and WT CD4+ CD45RBhigh T cells were transferred to Rag2-/- mice via intravenous (i.v.) tail injection, respectively, to establish a chronic colitis model. Adeno-associated virus (AAV)-mediated gene knockout technique was used to knock out runt-associated transcription factor 1 (Runx1) expression in vivo. Specific cytokines of Th1 and Th17 cells were detected by quantitative RT-PCR, immunohistochemistry, ELISA, and flow cytometry. In T-cell transfer colitis mice, the Rag2-/- mice reconstituted with TRAF5-/- CD4+ CD45RBhigh T cells showed more severe intestinal inflammation than the WT control group, which was characterised by increased expression of INF-γ, TNF-α, IL-17a. Furthermore, we found that the INF-γ+ CD4+ , IL17a+ CD4+ , and INF-γ+ IL17a+ CD4+ T cells in the intestinal mucosa of Rag2-/- mice reconstituted with TRAF5-/- CD4+ CD45RBhigh T cells were significantly higher than those of the WT control group by flow cytometry. Mechanistically, knockout Runx1 inhibited the differentiation of TRAF5-/- CD4+ T cells into Th1 and Th17 cells in the intestinal mucosa of T-cell transfer colitis mice. TRAF5 regulates Th1 and Th17 cell differentiation and immune response through Runx1 to participate in the pathogenesis of colitis. Thus targeting TRAF5 in CD4+ T cells may be a novel treatment for IBD.

Total Saponins of Radix Clematis Regulate Fibroblast-Like Synoviocyte Proliferation in Rheumatoid Arthritis via the LncRNA OIP5-AS1/MiR-410-3p/Wnt7b Signaling Pathway

Background

Rheumatoid arthritis (RA) is the most common autoimmune disease and affects multiple joints. Previous studies have shown that total saponins of Radix clematidis (TSC) have a clear therapeutic effect on RA, but the specific mechanism has not yet been clarified. Literature screening and previous research suggest that the lncRNA OIP5-AS1/miR-410-3p/Wnt7b signaling pathway exerts a regulatory effect on the pathogenesis of RA. In this study, we examined whether the TSC treatment of RA affects the lncRNA OIP5-AS1/miR-410-3p/Wnt7b pathway.

Materials and Methods

Freund's complete adjuvant was used to create an adjuvant arthritis (AA) rat model with rat synovial cells being harvested and cultured. The experiment comprises a normal group, model group, TSC optimal-dose group, TSC optimal-dose group + lncRNA OIP5-AS1siRNA group, lncRNA OIP5-AS1 siRNA group, and lncRNA OIP5-AS1 siRNA + NC group. MMT was used to screen the optimal concentration of TSC. The level of lncRNA OIP5-AS1, miR-410-3p, Wnt7b, β-catenin, c-Myc, cyclin D1, GSK-3β, and SFRP4 mRNA were detected by real-time-qPCR, the expression of Wnt7b, β-catenin, c-Myc, cyclin D1, GSK-3β, and p-GSK-3β (Ser9) protein were detected by immunofluorescence and Western blot.

Results

We found that TSC inhibits the proliferation of RA FLS, TSC significantly reduced lncRNA OIP5-AS1, Wnt7b, β-catenin, c-Myc, cyclin D1, and p-GSK-3β/GSK-3β mRNA/protein expression, whereas the miR-410-3p and SFRP4 mRNA/protein expression levels were significantly upregulated. Our data suggest that TSC can inhibit the excessive proliferation of FLS to treat RA, the mechanism of which may be closely related to regulation of the lncRNA OIP5-AS1/miR-410-3p /Wnt7b signaling axis and the Wnt signaling pathway.

Transthyretin and Receptor for Advanced Glycation End Product's Differential Levels Associated with the Pathogenesis of Rheumatoid Arthritis

Objective

Rheumatoid arthritis (RA) is a chronic autoimmune, inflammatory joint disease. The identification of multifaceted etiological changes at the protein level in RA remains an important need. We aimed to identify differential proteins (DPs) and gene profiles to uncover inflammatory indicators and their association to RA pathogenesis.

Methods

2-DE and SWATH-MS were used to identify DPs in RA and healthy control plasma. Fluorescence phenylboronate gel electrophoresis (Flu-PAGE) with mass spectrometry was used for protein glycation in RA plasma. Disease specificity of identified DPs was confirmed by ELISA and Western blot analysis. The gene expressions of selected DPs were evaluated by qRT-PCR in PBMCs of RA, systemic lupus erythematosus (SLE), spondyloarthritis (SpA), and osteoarthritis (OA). The functional implication of glycated protein was determined by in- silico and validated by in vitro analysis in fibroblast-like synoviocytes.

Results

A total of 150 DPs (127 increased and 23 decreased) were identified by 2-DE and SWATH-MS analysis in RA plasma compared to healthy control (HC). Nine proteins were identified as glycated by Flu-PAGE LC-MS/MS. Transthyretin (TTR), serotransferrin, and apolipoprotein-A1 (Apo-A1) were found to be differential and glycated. ELISA and Western blot results revealed the disease-specific increased expression of TTR and RAGE in RA. The qRT-PCR results signify the aberrant gene expression of TTR and RAGE, found to be associated with RA when compared with SLE, SpA, and OA PBMCs. TTR-RAGE interactions were predicted by in-silico and validated by in-vitro analysis using RA-FLS. The increased levels of pro-inflammatory cytokines IL-6, IL-1β, TNF-α, and differently expressed TTR and RAGE were confirmed in fibroblast-like synoviocytes under inflammatory conditions.

Conclusion

Our findings showed that the level of TTR was increased in RA plasma, along with an altered glycation rate. TTR and RAGE aberrant gene expression in PBMCs are the key events associated with RA, and TNF-α activates the NF-KB pathways and promote TTR and RAGE differential expressions that may have pathogenic/inflammatory significance.

Proinflammatory Effects of Ubiquitin-Specific Protease 5 (USP5) in Rheumatoid Arthritis Fibroblast-Like Synoviocytes

Rheumatoid arthritis (RA) is a worldwide chronic autoimmune inflammatory disease which is affecting approximately 1% of the total population. It is characterized by abnormal proliferation of fibroblast-like synoviocytes (FLS) and increased production of proinflammatory cytokines. In the current study, we were aiming to investigate the role of ubiquitin-specific protease 5 (USP5) in the inflammatory process in RA-FLS. Expression of USP5 was found upregulated in RA-FLS compared with that in osteoarthritis- (OA-) FLS, and IL-1β stimulation increased USP5 expression in a time-dependent manner. Furthermore, we found that USP5 overexpression significantly aggravated proinflammatory cytokine production and related nuclear factor κB (NF-κB) signaling activation. Consistently, silencing of USP5 decreased the release of cytokines and inhibited the activation of NF-κB. In addition, USP5 was found to interact with tumor necrosis factor receptor-associated factor 6 (TRAF6) and remove its K48-linked polyubiquitination chains therefore stabilizing TRAF6. Our data showed that a USP5-positive cell regulates inflammatory processes in RA-FLS and suggested USP5 as a potential target for RA treatment.

MicroRNA‑671‑3p regulates the development of knee osteoarthritis by targeting TRAF3 in chondrocytes

Osteoarthritis (OA) is a degenerative joint disease characterized by articular cartilage degradation and joint inflammation. A previous study showed that microRNA (miR)‑671‑3p is involved in the development of OA, however, its function and molecular target in chondrocytes during the pathogenesis of OA remain to be fully elucidated. In the present study, miR‑671‑3p was significantly downregulated in knee OA cartilage tissues compared with normal cartilage tissues. The expression levels of pro‑inflammatory cytokines, including interleukin (IL)‑1β, IL‑6, IL‑8 and tumor necrosis factor (TNF)‑α, in the knee OA cartilage tissues were significantly higher than those in the normal cartilage tissues. Through gain‑of‑function and loss‑of‑function experiments, miR‑671‑3p was shown to significantly affect matrix synthesis gene expression, cell proliferation, apoptosis and inflammation in chondrocytes from patients with OA. Subsequent bioinformatics analysis identified potential target sites of the miR‑671‑3p located in the 3'untranslated region of TNF receptor‑associated factor (TRAF3). The results of a dual‑luciferase reporter assay showed that TRAF3 is a target gene of miR‑671‑3p. Western blot analysis demonstrated that miR‑671‑3p inhibited the gene expression of TRAF3. Furthermore, the restoration of TRAF3 markedly abrogated the effect of miR‑671‑3p. Taken together, the present study suggests that miR‑671‑3p may be important in the pathogenesis of OA through targeting TRAF3 and regulating chondrocyte apoptosis and inflammation, which may be a potential molecular target for OA treatment.

Gene therapy in rheumatoid arthritis: Strategies to select therapeutic genes

Significant advances have been achieved in recent years to ameliorate rheumatoid arthritis (RA) in animal models using gene therapy approaches rather than biological treatments. Although biological agents serve as antirheumatic drugs with suppressing proinflammatory cytokine activities, they are usually accompanied by systemic immune suppression resulting from continuous or high systemic dose injections of biological agents. Therefore, gene transfer approaches have opened an interesting perspective to deliver one or multiple genes in a target-specific or inducible manner for the sustained intra-articular expression of therapeutic products. Accordingly, many studies have focused on gene transferring methods in animal models by using one of the available approaches. In this study, the important strategies used to select effective genes for RA gene therapy have been outlined. Given the work done in this field, the future looks bright for gene therapy as a new method in the clinical treatment of autoimmune diseases such as RA, and by ongoing efforts in this field, we hope to achieve feasible, safe, and effective treatment methods.

A cytokine protein-protein interaction network for identifying key molecules in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease of the synovial joints. Though the current RA therapeutics such as disease-modifying antirheumatic drugs (DMARDs), nonsteroidal anti-inflammatory drugs (NSAIDs) and biologics can halt the progression of the disease, none of these would either dramatically reduce or cure RA. So, the identification of potential therapeutic targets and new therapies for RA are active areas of research. Several studies have discovered the involvement of cytokines in the pathogenesis of this disease. These cytokines induce signal transduction pathways in RA synovial fibroblasts (RASF). These pathways share many signal transducers and their interacting proteins, resulting in the formation of a signaling network. In order to understand the involvement of this network in RA pathogenesis, it is essential to identify the key transducers and their interacting proteins that are part of this network. In this study, based on a detailed literature survey, we have identified a list of 12 cytokines that induce signal transduction pathways in RASF. For these cytokines, we have built a signaling network using the protein-protein interaction (PPI) data that was obtained from public repositories such as HPRD, BioGRID, MINT, IntAct and STRING. By combining the network centrality measures with the gene expression data from the RA related microarrays that are available in the open source Gene Expression Omnibus (GEO) database, we have identified 24 key proteins of this signaling network. Two of these 24 are already drug targets for RA, and of the remaining, 12 have direct PPI links to some of the current drug targets of RA. Therefore, these key proteins seem to be crucial in the pathogenesis of RA and hence might be treated as potential drug targets.

Anti-inflammatory Mechanism of Geniposide: Inhibiting the Hyperpermeability of Fibroblast-Like Synoviocytes via the RhoA/p38MAPK/NF-κB/F-Actin Signal Pathway

Geniposide (GE) is the extraction and purification of iridoid glycosides from the Gardenia jasminoides Ellis, which is a promising anti-inflammatory drug, but its mechanism of actions on rheumatoid arthritis (RA) has not been clarified. This study investigated the molecular mechanism behind GE reduced the high permeability of fibroblast-like synoviocytes (FLSs) derived from SD rats with adjuvant arthritis (AA), with the aims of observing the action of GE in AA rats and exploring new therapeutic strategies for RA treatment. The CCK-8 method was used to detect FLSs proliferation. The pro-inflammatory cytokines levels and anti-inflammatory cytokines levels in FLSs were determined by ELISA kits. FLSs permeability assay was performed on Transwell. Immunofluorescence was used to assay the arrangement and morphology of F-actin. The expression of the key molecules related to FLSs permeability (RhoA, p-p38MAPK, NF-κB p-p65 and F-actin) was detected by western blotting. After treatment with lipopolysaccharide (LPS), the proliferation and the permeability of the cells increased significantly (all P < 0.05). The expression of RhoA, p-p38MAPK, NF-κB p-p65 and F-actin in FLSs was higher compared with the control group, and F-actin was redistributed, with the formation of additional stress fibers. But, these conditions were moderated after treatment with GE. We demonstrated that the treatment of different concentrations of GE (25, 50, and 100 μg/mL) had a significant inhibitory effect on the proliferation and permeability of FLSs in vitro. Furthermore, the levels of interleukin (IL)-1β and IL-17 secreted by FLSs were decreased in different doses of GE groups, and the levels of anti-inflammatory cytokines (IL-4, TGF-β1) were increased. Under treatment with GE, low expression of RhoA downregulated expression of p-p38MAPK, NF-κB p-p65, and F-actin while compared with control group, and restored the hyperpermeability of FLSs due to LPS treatment. Taken together, GE might play its anti-inflammatory and immunoregulatory effects via regulating the relative equilibrium of pro-inflammatory cytokines and anti-inflammatory cytokines. GE attenuated the hyperpermeability of FLSs. The down-regulation of the conduction of RhoA/p38MAPK/NF-κB/F-actin signal may play a critical role in the mechanisms of GE on RA. GE could be an effective therapeutic agent for the treatment of RA.