Cartilage Destruction In Rheumatoid Arthritis Research Articles

JAK inhibitors improve ATP production and mitochondrial function in rheumatoid arthritis: a pilot study

Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease associated by inflammation of the synovial tissue and autoantibody production. Oxidative stress and free radicals are known to be indirectly implicated in joint damage and cartilage destruction in RA. Several studies describe the presence of mitochondrial dysfunction in RA, but few of them follow the dynamics in energy parameters after therapy. The aim of our investigation is to evaluate the direct effect of JAK inhibitors on cellular metabolism (and under induced oxidative stress) in RA patients. Ten newly diagnosed RA patients were included in the study. Peripheral blood mononuclear cells (PBMCs) and plasma were isolated before and 6 months after therapy with JAK inhibitors. A real-time metabolic analysis was performed to assess mitochondrial function and cell metabolism in PBMCs. Sonographic examination, DAS28 and conventional clinical laboratory parameters were determined also prior and post therapy. A significant decrease in proton leak after therapy with JAK inhibitors was found. The increased production of ATP indicates improvement of cellular bioenergetics status. These findings could be related to the catalytic action of JAK inhibitors on oxidative phosphorylation which corresponds to the amelioration of clinical and ultra-sonographic parameters after treatment. Our study is the first to establish the dynamics of mitochondrial parameters in PBMCs from RA patients before and after in vivo therapy with JAK inhibitors.

Components of the sympathetic nervous system as targets to modulate inflammation – rheumatoid arthritis synovial fibroblasts as neuron-like cells?

BackgroundCatecholamines are major neurotransmitters of the sympathetic nervous system (SNS) and they are of pivotal importance in regulating numerous physiological and pathological processes. Rheumatoid arthritis (RA) is influenced by the activity of the SNS and its neurotransmitters norepinephrine (NE) and dopamine (DA) and early sympathectomy alleviates experimental arthritis in mice. In contrast, late sympathectomy aggravates RA, since this procedure eliminates anti-inflammatory, tyrosine hydroxylase (TH) positive cells that appear in the course of RA. While it has been shown that B cells can take up, degrade and synthesize catecholamines it is still unclear whether this also applies to synovial fibroblasts, a mesenchymal cell that is actively engaged in propagating inflammation and cartilage destruction in RA. Therefore, this study aims to present a detailed description of the catecholamine pathway and its influence on human RA synovial fibroblasts (RASFs).ResultsRASFs express all catecholamine-related targets including the synthesizing enzymes TH, DOPA decarboxylase, dopamine beta-hydroxylase, and phenylethanolamine N-methyltransferase. Furthermore, vesicular monoamine transporters 1/2 (VMAT1/2), dopamine transporter (DAT) and norepinephrine transporter (NET) were detected. RASFs are also able to degrade catecholamines as they express monoaminoxidase A and B (MAO-A/MAO-B) and catechol-O-methyltransferase (COMT). TNF upregulated VMAT2, MAO-B and NET levels in RASFs. DA, NE and epinephrine (EPI) were produced by RASFs and extracellular levels were augmented by either MAO, COMT, VMAT or DAT/NET inhibition but also by tumor necrosis factor (TNF) stimulation. While exogenous DA decreased interleukin-6 (IL-6) production and cell viability at the highest concentration (100 μM), NE above 1 μM increased IL-6 levels with a concomitant decrease in cell viability. MAO-A and MAO-B inhibition had differential effects on unstimulated and TNF treated RASFs. The MAO-A inhibitor clorgyline fostered IL-6 production in unstimulated but not TNF stimulated RASFs (10 nM-1 μM) while reducing IL-6 at 100 μM with a dose-dependent decrease in cell viability in both groups. The MAO-B inhibitor lazabemide hydrochloride did only modestly decrease cell viability at 100 μM while enhancing IL-6 production in unstimulated RASFs and decreasing IL-6 in TNF stimulated cells.ConclusionsRASFs possess a complete and functional catecholamine machinery whose function is altered under inflammatory conditions. Results from this study shed further light on the involvement of sympathetic neurotransmitters in RA pathology and might open therapeutic avenues to counteract inflammation with the MAO enzymes being key candidates.

Pharmacology and molecular docking study of cartilage protection of Chinese herbal medicine Fufang Shatai Heji (STHJ) by inhibiting the expression of MMPs in collagen-induced arthritis mice.

This study aims to explore whether Fufang Shatai Heji (STHJ), as a mixture collected by a decoction of a variety of Chinese herbal medicines for immune system diseases, can improve the cartilage destruction of rheumatoid arthritis (RA). The therapeutic effects of STHJ were studied using collagen induced arthritis (CIA) mice. The improvement effect of STHJ on synovitis and cartilage damage caused by arthritis was studied by joint pathological analysis. The inhibitory effect of STHJ on related degradation enzymes in cartilage was studied by immunohistochemistry and real-time polymerase chain reaction (PCR). The specific targets of STHJ were predicted by molecular docking. After successfully inducing CIA, the paws of the mice showed significant swelling, and athological analysis of the ankle and knee joints also showed significant cartilage destruction and synovial hyperplasia. However, synovial hyperplasia and cartilage destruction were markedly alleviated after administration of STHJ. And after STHJ treatment, the expression of ADAMTS-4, ADAMTS-5, MMP-9 and MMP-13, in the cartilage layer of CIA mice was significantly inhibited. Through molecular docking assays, we proved that acteoside in STHJ could directly bind to the Glu111, Phe110 residues in MMP-9 and glycyrrhizic acid in STHJ bind to the Glu382, Asn433 residues in MMP-13. Our results suggested that STHJ may alleviate synovial hyperplasia and cartilage destruction in CIA mice and protect cartilage by inhibiting the expression of MMP-9 and other enzymes.

PTEN Methylation Promotes Inflammation and Activation of Fibroblast-Like Synoviocytes in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is characterized by a tumor-like expansion of the synovium and subsequent destruction of adjacent articular cartilage and bone. In our previous work we showed that phosphatase and tension homolog deleted on chromosome 10 (PTEN) contributes to the activation of fibroblast-like synoviocytes (FLS) in adjuvant-induced arthritis (AIA), but the underlying mechanism is not unknown. In this study, we show that PTEN is downregulated while DNA methyltransferase (DNMT)1 is upregulated in FLS from RA patients and a rat model of AIA. DNA methylation of PTEN was increased by administration of tumor necrosis factor (TNF)-α in FLS of RA patients, as determined by chromatin immunoprecipitation and methylation-specific PCR. Treatment with the methylation inhibitor 5-azacytidine suppressed cytokine and chemokine release and FLS activation in vitro and alleviated paw swelling in vivo. PTEN overexpression reduced inflammation and activation of FLS via protein kinase B (AKT) signaling in RA, and intra-articular injection of PTEN-expressing adenovirus into the knee of AIA rats markedly reduced inflammation and paw swelling. Thus, PTEN methylation promotes the inflammation and activation of FLS in the pathogenesis of RA. These findings provide insight into the molecular basis of articular cartilage destruction in RA, and indicate that therapeutic strategies that prevent PTEN methylation may an effective treatment.

Cyr61 synthesis is induced by interleukin-6 and promotes migration and invasion of fibroblast-like synoviocytes in rheumatoid arthritis

BackgroundInterleukin-6 (IL-6) is involved in fibroblast-like synoviocyte (FLS) activation and promotes pannus formation and bone and cartilage destruction in rheumatoid arthritis (RA). Cysteine-rich 61 (Cyr61) protein regulates cell proliferation, migration, and differentiation. The aim of this study was to investigate the role of Cyr61 in RA-FLS migration and invasion after IL-6 stimulation.MethodsWestern blotting, immunohistochemistry, reverse transcription-polymerase chain reaction, and real time-polymerase chain reaction were used to examine protein and mRNA levels of Cyr61, matrix metalloproteinases (MMPs), and other signalling proteins. Knockdown of gene expression was performed with siRNA, and RNA sequencing was performed for differential gene analysis. Migration and invasion were assessed by wound healing and Boyden chamber assays.ResultsCyr61 levels were elevated in FLSs from RA patients compared to those in osteoarthritis patients. Control and IL-6-treated FLSs showed differential gene expression. IL-6 stimulated protein synthesis of Cyr61, which was attenuated by the extracellular signal-related kinase 1/2 (ERK 1/2) inhibitor, PD98059, and knockdown of early growth response 3 (EGR3), but not of JUN. IL-6-induced Cyr61 protein synthesis increased expression of MMP2. Cyr61 promoted FLS migration and invasion in an autocrine manner. Knockdown of CYR61 and a neutralising antibody attenuated Cyr61 synthesis and IL-6-induced FLS migration.ConclusionsBy modulating the ERK/EGR3 pathway, IL-6 stimulated Cyr61 production and in turn increased invasiveness of FLS. Our data suggest that Cyr61 might be a potential target to prevent the progression of joint damage in RA.

Imperative and effective reversion of synovial hyperplasia and cartilage destruction in rheumatoid arthritis through multiple synergistic effects of O2 and Ca2.

Abnormal synovial hyperplasia and cartilage destruction in a joint cavity are the key causes affecting the pain and disability in rheumatoid arthritis (RA) and, unfortunately, there exists no effective treatment for them. This investigation reports an effective reversion of the above pathological characteristics in RA owing to the use of a prolonged O2/Ca2+-supporting phototherapy hydrogel. The performed in vitro and in vivo experiments exhibit that the prolonged O2-supporting not only promotes the direct cell-killing effects of singlet oxygen, but also persistently blocks the pathological feedback between the abnormal proliferation of fibroblast-like synoviocyte and the local oxygen depletion. Furthermore, the Ca2+, which is the other decomposition product of the O2 donor, induces mitochondrial Ca2+ overload and endoplasmic reticulum Ca2+ disorder and triggers Ca2+-associated apoptosis and immunogenic cell death. In addition to these multiple synergistic effects on synovial hyperplasia, the prolonged Ca2+ support can also induce the regeneration of cartilage in RA affected joints. The present study may thus provide an effective therapeutic strategy for the prevention and reversion of joint lesions and the accompanying arthralgia and deformity in RA.

Higher aggrecan 1-F21 epitope concentrations in synovial fluid early after knee injury are associated with worse cartilage quality 20 years later

Purpose: To investigate if synovial fluid biomarkers of cartilage turnover acutely or years after an anterior cruciate ligament (ACL) injury are associated with subsequent knee cartilage status 20 years after injury. Methods: We studied a cohort of 32 patients who had coped with an ACL injury without ACL reconstruction and presented without radiographic diagnosis of osteoarthritis 16 years post injury. All had a delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) 20 years after a complete ACL tear. 25 out of 32 had one or more available synovial fluid samples aspirated without lavage either acutely after injury, or during 1-5 (median 4) follow up visits between 0.6 and 7 years after injury, and were included in this study (Table 1).Tabled 1Table 1 Characteristic of the 25 study subjects grouped by synovial fluid (SF) availability.Acute SF sampleChronic SF sample *n (% males)19 (63)22 (50)Age at injury, mean years (SD)25.2 (6.5)24.7 (6.3)BMI 20 years post-injury, mean (SD)25.3 (4.0)25.6 (3.6)Time between injury and sampling, median (range)4 (<1 to 13) days3.1 (0.6 to 7.1) yearsYears between injury and dGEMRIC, median (range)20.2 (18.8 to 23.1)20.2 (18.4 to 23.1)* 1-5 per individual, using the mean biomarker concentration or time for each individual. Open table in a new tab We quantified synovial fluid concentrations of two aggrecan epitopes (the 1-F21 epitope residing in or close to the keratan sulfate rich region, and the ARGS neoepitope generated by aggrecanase cleavage in the interglobular domain), cartilage oligomeric matrix protein (COMP), matrix metalloproteinase-3 (MMP-3) and tissue inhibitor of metalloproteinase-1 (TIMP-1) by immunoassays, and sulfated glycosaminoglycan (sGAG) content by Alcian blue precipitation. We created the ratio MMP-3/TIMP-1 to investigate differences in using these biomarkers alone or as a ratio between the enzyme and its inhibitor. We also investigated the ratios aggrecan/COMP, since the ratio 1-F21 aggrecan/COMP was reported to be more elevated in subjects with more progressive cartilage destruction in rheumatoid arthritis than 1-F21 aggrecan alone. Linear regression analysis was used to investigate associations between acute or chronic biomarker concentrations and cartilage quality at 20 years post injury. We included adjustments for age, sex, BMI at 20 years, and time between injury and knee puncture. For subjects with more than one chronic visit, we used the mean values for biomarkers and time in the regression models. Biomarker concentrations were log 10 transformed to achieve linear relationships with dGEMRIC values. To be able to compare effect sizes between biomarkers, we report standardized effects from the linear regression analysis. Results: With negative standardized effects close to 1, higher synovial fluid 1-F21 aggrecan concentrations or higher ratio 1-F21 aggrecan to COMP early after ACL injury were associated with shorter T1Gd values (inferior cartilage quality) 20 years later (Figure 1A). There was no similar association between acute ARGS aggrecan or sGAG content and T1Gd (Figure 1A), nor was chronic 1-F21 aggrecan concentrations associated with T1Gd values (Figure 1B). High similarity in the standardized effect sizes between aggrecan or sGAG concentrations alone and as ratios with COMP (Figures 1A and 1B), indicate that there was no added value in making such ratios compared to using the biomarker concentrations alone. Neither MMP-3 concentrations, nor the ratio MMP-3/TIMP-1 were predictive of subsequent cartilage quality in these subjects, which is consistent with previous findings of no apparent role of MMP-3 in pathological turnover of aggrecan. Conclusions: Acute (but not chronic) turnover of aggrecan generating increased synovial fluid concentrations of the 1-F21 epitope of aggrecan was associated with worse cartilage quality assessed by dGEMRIC 20 years later. Measuring specific aggrecan fragments carrying different epitopes appears to be important when investigating aggrecan as a predictive biomarker of cartilage quality.

Scientific validation of anti-arthritic effect of Kashayams – A polyherbal formulation in collagen induced arthritic rats

BackgroundToll-like receptor-4 (TLR-4) mediates activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) resulting in induction of proinflammatory genes such as that encoding tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) which played a significant role in cartilage destruction of rheumatoid arthritis (RA). Low risk and better efficacy made herbal drugs more reliable than nonsteroid anti-inflammatory drugs (NSAIDS) in RA treatment. Gugguluthiktam Kashayam (GuK), Punarnavadi Kashayam (PuK) and Balaguluchiadi Kashayam (BgK) are ayurvedic polyherbal formulations prescribed in classical ayurvedic texts Sahasrayogam and Ashtangahridayam as medicines for the treatment of RA. ObjectiveThe objective of the present study was to elucidate the molecular mechanism of anti-arthritic effect of these Kashayams on TLR-4 signal transduction pathway in collagen induced arthritic rats. Material and methodsThe wistar rats grouped into group I - Normal, group II- Collagen induced arthritis (CIA), group III- CIA + BgK, group IV– CIA + PuK, group V- CIA + GuK, group VI - CIA + Indomethacin (3 mg/kg b.wt.). Treatment with Kashayam (2 ml/kg b.wt) started after 14 days of primary immunization with type II collagen and continued for a period of 45 days. ResultsArthritis index, C-reactive protein (CRP), rheumatoid factor (RF) and myeloperoxidase (MPO) in serum and protein level of TLR-4, myeloid differentiation factor 88 (MYD88), NF-κB, TNF-α, IL-1β, inducible nitric oxide synthase (iNOS), cyclooxygenase-2 COX-2) and prostaglandin E-2 (PGE-2) in cartilage were significantly elevated in CIA rats. Further, treatment with Kashayams downregulated all these inflammatory mediators hitherto TLR-4-NF-kB signal transduction pathway except IL-10, an anti-inflammatory cytokine which showed a reverse effect. ConclusionThis molecular mechanism of the investigation confirmed the clinical efficacy of Kashayams in preventing the progression of RA and gave an intuition of the scientific validation of Kashayams, an Ayurvedic classical medicine.

Systematic Analysis of Differential Expression Profile in Rheumatoid Arthritis Chondrocytes Using Next-Generation Sequencing and Bioinformatics Approaches.

Cartilage destruction in rheumatoid arthritis (RA) occurs primarily in the pannus-cartilage interface. The close contact of the synovium-cartilage interface implicates crosstalk between synovial fibroblasts and chondrocytes. The aim of this study is to explore the differentially expressed genes and novel microRNA regulations potentially implicated in the dysregulated cartilage homeostasis in joint destruction of RA. Total RNAs were extracted from human primary cultured normal and RA chondrocytes for RNA and small RNA expression profiling using next-generation sequencing. Using systematic bioinformatics analyses, we identified 463 differentially expressed genes in RA chondrocytes were enriched in biological functions related to altered cell cycle process, inflammatory response and hypoxic stimulation. Moreover, fibroblast growth factor 9 (FGF9), kynureninase (KYNU), and regulator of cell cycle (RGCC) were among the top dysregulated genes identified to be potentially affected in the RA joint microenvironment, having similar expression patterns observed in arrays of clinical RA synovial tissues from the Gene Expression Omnibus database. Additionally, among the 31 differentially expressed microRNAs and 10 candidate genes with potential microRNA-mRNA interactions in RA chondrocytes, the novel miR-140-3p-FGF9 interaction was validated in different microRNA prediction databases, and proposed to participate in the pathogenesis of joint destruction through dysregulated cell growth in RA. The findings provide new perspectives for target genes in the management of cartilage destruction in RA.

Oxymatrine prevents synovial inflammation and migration via blocking NF-κB activation in rheumatoid fibroblast-like synoviocytes

The fibroblast-like synoviocytes (FLSs) has the aggressive phenotype, which is very important for cartilage destruction in rheumatoid arthritis (RA). To the pathology of RA, the increased FLSs migration, activation and proliferation are essential factors. Oxymatrine is a traditional Chinese herb, which is the extraction from the root of Sophora flavescens and regarded as quinolizidine alkaloid compounds and has been shown to inhibit inflammation, proliferation and migration in vitro or vivo. However, whether oxymatrine effects in the treatment of RA FLSs is undefined. In our study, the inhibition of oxymatrine in RA FLSs inflammation, proliferation and migration in RA FLS are evaluated. We found that oxymatrine decreased the IL-6 and IL-8 expression and the proliferation, migration and invasion of RA FLSs. We also evaluated the molecular mechanisms and we found the effect of oxymatrine on NF-κB activation. The results showed that oxymatrine inhibited the activity of NF-κB. And the treatment activity of oxymatrine on collagen-induced arthritis (CIA) was further explored by us. Thus, we conclude that oxymatrine may protect joint destruction of RA by inhibiting synoviocyte activation, migration, invasion, and proliferation.

Role of tumor-like multipotent mesenchymal stromal cells in rheumatoid arthritis

Multipotent mesenchymal stromal/stem cells (MSCs) are regarded as a stable, safe and easily available source of precursor cells for purposes of regenerative medicine. However, under repeated replication in tissue reparation processes and action of inflammatory mediators, aged MSCs may be transformed and obtain certain tumor-cell characteristics. The present review deals with the MSCs role in pathogenesis of rheumatoid arthritis. High proliferation speed, lack of contact inhibition and invasive growth of transformed MSCs is an important mechanism of cartilage destruction in rheumatoid arthritis.

Rheumatoid arthritis fibroblast-like synoviocytes co-cultured with PBMC increased peripheral CD4+ CXCR5+ ICOS+ T cell numbers.

'Circulating' T follicular helper cells (Tfh), characterized by their surface phenotypes CD4+ chemokine receptor 5 (CXCR5)+ inducible co-stimulatory molecule (ICOS)+ , have been identified as the CD4+ T cell subset specialized in supporting the activation, expansion and differentiation of B cells. Fibroblast-like synoviocytes (FLS) are critical in promoting inflammation and cartilage destruction in rheumatoid arthritis (RA), and the interaction between FLS and T cells is considered to facilitate FLS activation and T cell recruitment. However, it remains unknown whether RA-FLS co-cultured with activated peripheral blood mononuclear cells (PBMC) has immunoregulatory effects on peripheral Tfh. In the present study, we co-cultured RA-FLS with or without anti-CD3/CD28-stimulated PBMC. The results showed that RA-FLS co-cultured with stimulated PBMC could increase the numbers of CD4+ CXCR5+ ICOS+ T cells of RA PBMC possibly via the production of interleukin (IL)-6, a critical cytokine involved in the differentiation of Tfh cells. We also observed increased reactive oxygen species (ROS) levels in the co-culture system of RA-FLS and PBMC. The percentage of CD4+ CXCR5+ ICOS+ T cells was decreased when ROS production was inhibited by N-acetyl-L-cysteine (NAC), a specific inhibitor which can decrease ROS production. In addition, we showed that the higher levels of tumour necrosis factor (TNF)-α and IL-1β in the co-culture system and the blocking of TNF receptor 2 (TNF-R2) and IL-1β receptor (IL-1βR) both decreased the numbers of CD4+ CXCR5+ ICOS+ T cells. Our study reveals a novel mechanistic insight into how the interaction of RA-FLS and PBMC participates in the RA pathogenesis, and also provides support for the biologicals application for RA.

Halofuginone inhibits TNF-α-induced the migration and proliferation of fibroblast-like synoviocytes from rheumatoid arthritis patients

Fibroblast-like synoviocytes (FLSs) display an aggressive phenotype that is a critical factor in cartilage destruction in rheumatoid arthritis (RA). Increased FLS migration and proliferation are essential to the pathology of RA. Halofuginone has been found to inhibit cell migration and proliferation in cancer cells. However, whether halofuginone has a role in the treatment of RA FLSs is unclear. In this study, we found that halofuginone reduced migration, invasion, cell proliferation and MMPs expression in RA FLSs. In addition, we demonstrated that halofuginone inhibited reorganization of the actin cytoskeleton during cell migration. To gain insight into the molecular mechanisms, we evaluated the effect of halofuginone on the MAPK and AKT pathways. Our results indicated that halofuginone inhibited the activity of MAPK and AKT. Taken together, these results suggest that halofuginone may protect against joint destruction in RA by regulating synoviocyte migration, invasion and cell proliferation by inhibiting MAPK and AKT activation.

APL1, an altered peptide ligand derived from human heat-shock protein 60, increases the frequency of Tregs and its suppressive capacity against antigen responding effector CD4 + T cells from rheumatoid arthritis patients.

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by a chronic relapsing-remitting joint inflammation. Perturbations in the balance between CD4 + T cells producing IL-17 and CD4 + CD25(high)FoxP3 + Tregs correlate with irreversible bone and cartilage destruction in RA. APL1 is an altered peptide ligand derived from a CD4+ T-cell epitope of human HSP60, an autoantigen expressed in the inflamed synovium, which increases the frequency of CD4 + CD25(high)FoxP3+ Tregs in peripheral blood mononuclear cells from RA patients. The aim of this study was to evaluate the suppressive capacity of Tregs induced by APL1 on proliferation of effector CD4+ T cells using co-culture experiments. Enhanced Treg-mediated suppression was observed in APL1-treated cultures compared with cells cultured only with media. Subsequent analyses using autologous cross-over experiments showed that the enhanced Treg suppression in APL1-treated cultures could reflect increased suppressive function of Tregs against APL1-responsive T cells. On the other hand, APL1-treatment had a significant effect reducing IL-17 levels produced by effector CD4+ T cells. Hence, this peptide has the ability to increase the frequency of Tregs and their suppressive properties whereas effector T cells produce less IL-17. Thus, we propose that APL1 therapy could help to ameliorate the pathogenic Th17/Treg balance in RA patients.

Protein Inhibitor of Activated STAT3 Regulates Migration, Invasion, and Activation of Fibroblast-like Synoviocytes in Rheumatoid Arthritis.

The aggressive phenotype displayed by fibroblast-like synoviocytes (FLSs) is a critical factor of cartilage destruction in rheumatoid arthritis (RA). Increased FLSs migration and subsequent degradation of the extracellular matrix are essential to the pathology of RA. Protein inhibitor of activated STAT (PIAS), whose family members include PIAS1, PIAS2 (PIASx), PIAS3, and PIAS4 (PIASy), play important roles in regulating various cellular events, such as cell survival, migration, and signal transduction in many cell types. However, whether PIAS proteins have a role in the pathogenesis of RA is unclear. In this study, we evaluated the role of PIAS proteins in FLSs migration, invasion, and matrix metalloproteinases (MMPs) expression in RA. We observed increased expression of PIAS3, but not PIAS1, PIAS2, or PIAS4, in FLSs and synovial tissues from patients with RA. We found that PIAS3 knockdown by short hairpin RNA reduced migration, invasion, and MMP-3, MMP-9, and MMP-13 expression in FLSs. In addition, we demonstrated that PIAS3 regulated lamellipodium formation during cell migration. To gain insight into molecular mechanisms, we evaluated the effect of PIAS3 knockdown on Rac1/PAK1 and JNK activation. Our results indicated that PIAS3-mediated SUMOylation of Rac1 controlled its activation and modulated the Rac1 downstream activity of PAK1 and JNK. Furthermore, inhibition of Rac1, PAK1, or JNK decreased migration and invasion of RA FLSs. Thus, our observations suggest that PIAS3 suppression may be protective against joint destruction in RA by regulating synoviocyte migration, invasion, and activation.

Anti-inflammatory effects of N-acylethanolamines in rheumatoid arthritis synovial cells are mediated by TRPV1 and TRPA1 in a COX-2 dependent manner.

IntroductionThe endocannabinoid system modulates function of immune cells and mesenchymal cells such as fibroblasts, which contribute to cartilage destruction in rheumatoid arthritis (RA). The aim of the study was to determine the influence of N-acylethanolamines anandamide (AEA), palmitoylethanolamine (PEA) and oleylethanolamine (OEA) on several features of arthritic inflammation in vitro (human material) and in vivo (a mouse model).MethodsImmunofluorescence and western blotting were used to detect cannabinoid receptors and related enzymes. Cytokines and MMP-3 were measured by ELISA. Intracellular signaling proteins were detected by proteome profiling. Proliferation was quantified by CTB reagent. Adhesion was assessed by the xCELLigence system. After onset of collagen type II arthritis, mice were treated daily with the FAAH inhibitor JNJ1661010 (20 mg/kg) or vehicle.ResultsIL-6, IL-8 and MMP-3 (determined only in synovial fibroblasts (SFs)) were downregulated in primary synoviocytes and SFs of RA and OA after AEA, PEA and OEA treatment. In SFs, this was due to activation of TRPV1 and TRPA1 in a COX-2-dependent fashion. FAAH inhibition increased the efficacy of AEA in primary synoviocytes but not in SFs. The effects of OEA and PEA on SFs were diminished by FAAH inhibition. Adhesion to fibronectin was increased in a CB1-dependent manner by AEA in OASFs. Furthermore, elevation of endocannabinoids ameliorated collagen-induced arthritis in mice.ConclusionsN-acylethanolamines exert anti-inflammatory effects in SFs. A dual FAAH/COX-2 inhibitor, increasing N-acylethanolamine levels with concomitant TRP channel desensitization, might be a good candidate to inhibit the production of proinflammatory mediators of synovial cells and to reduce erosions.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-015-0845-5) contains supplementary material, which is available to authorized users.

The endocannabinoid system and its therapeutic implications in rheumatoid arthritis.

Since the discovery of the endogenous receptor for Δ(9)-tetrahydrocannabinol, a main constituent of marijuana, the endocannabinoid system (comprising cannabinoid receptors and their endogenous ligands, as well as the enzymes involved in their metabolic processes) has been implicated as having multiple regulatory functions in many central and peripheral conditions, including rheumatoid arthritis (RA). RA is an immune-mediated inflammatory disease that is associated with the involvement of many kinds of cells (such as fibroblastlike synoviocytes [FLSs], osteoclasts, T cells, B cells, and macrophages) and molecules (such as interleukin-1β, tumor necrosis factor-α, interleukin-6, matrix metalloproteinases [MMPs], and chemokines). Increasing evidence suggests that the endocannabinoid system, especially cannabinoid receptor 2 (CB2), has an important role in the pathophysiology of RA. Many members of the endocannabinoid system are reported to inhibit synovial inflammation, hyperplasia, and cartilage destruction in RA. In particular, specific activation of CB2 may relieve RA by inhibiting not only the production of autoantibodies, proinflammatory cytokines, and MMPs, but also bone erosion, immune response mediated by T cells, and the proliferation of FLSs. In this review, we will discuss the possible functions of the endocannabinoid system in the modulation of RA, which may be a potential target for treatment.

Cartilage destruction in rheumatoid arthritis, its association with functional impairments

The paper discusses the mechanisms of destructive processes in rheumatoid arthritis (RA). At the present stage, in addition to suppress inflammation, the goals of treatment are to prevent cartilage and bone destruction in the affected joints. Prediction of destructive processes in RA plays an important role as the irreversibility of functional changes in RA directly correlates with the degree of joint injury. The paper discusses the mechanisms of articular cartilage and bone destruction and the significance of different biochemical markers for estimating the degree of injury and for predicting further destruction of small hand and foot joints. In RA, the investigators identify not only clinical (activity indicators), but also biological (bone, cartilage, and synovium damage markers) predictors for joint injury: CТXII is a marker for cartilage degradation (collagen type II) and CTXI is a marker for bone degradation (collagen type I) and their trends over 4–12 or more weeks. Although the occurrence of erosions is considered to be a major manifestation of joint destruction progression in RA, the functional activity in its early stages is shown to depend on the estimate of joint space narrowing (cartilage degradation) to a greater extent than on that of erosions when evaluating the destruction by the modified Sharp method. Several randomized placebocontrolled studies (RPCSs) have assessed the association of patients' functional capacity with joint space narrowing or with the number of erosions. In RA, cartilage degradation has been demonstrated to play a larger role in irreversible function loss than bone destruction. The possibility of suppressing cartilage degradation, which is indicated in RPCSs of the efficacy of adalimumab, correlates with a better functional outcome in patients with RA. Serum markers for cartilage metabolism may be not only predictors for further radiographic progression, but also be used to evaluate therapeutic effectiveness.

Choline kinase inhibition in rheumatoid arthritis

ObjectivesLittle is known about targeting the metabolome in non-cancer conditions. Choline kinase (ChoKα), an essential enzyme for phosphatidylcholine biosynthesis, is required for cell proliferation and has been implicated in cancer...

The discoidin domain receptor 2/annexin A2/matrix metalloproteinase 13 loop promotes joint destruction in arthritis through promoting migration and invasion of fibroblast-like synoviocytes.

Discoidin domain receptor 2 (DDR-2)/matrix metalloproteinase (MMP) signaling is an important pathway involved in cartilage destruction in rheumatoid arthritis (RA). However, the molecular mechanisms of this pathway have not been clearly identified. This study was undertaken to screen key molecules involved in this pathway and evaluate their biologic functions in synovium invasion of RA. DDR-2-interacting proteins were examined in vitro by immunoprecipitation and mass spectrometry, and annexin A2 was acquired. The effects of annexin A2 on fibroblast-like synoviocyte (FLS) migration were evaluated using a Transwell invasion assay and an Erasion trace test. In Ddr2(-/-) mice with collagen-induced arthritis (CIA), hematoxylin and eosin (H&E) staining, immunohistochemical analysis, and Western blot analysis were used to assess expression of DDR-2, annexin A2, and MMP-13, as well as synovial hyperplasia. Rats with CIA were treated with lentivirus annexin A2 small interfering RNA (siRNA), and annexin A2 siRNA effects on joint damage were analyzed based upon arthritis index scores and results of micro-computed tomography and H&E staining. The differences between annexin A2 expression in clinical samples from RA and osteoarthritis patients were compared using Western blotting. Annexin 2 was identified for the first time as a DDR-2 binding protein. It may be phosphorylated by phospho-DDR-2, leading to MMP-13 secretion. The annexin A2 phosphorylation level and MMP-13 expression level were decreased and collagen-induced joint damage greatly reduced in Ddr2(-/-) mice. Joint damage in rats with CIA was significantly ameliorated when annexin A2 was down-regulated. Annexin A2 expression and phosphorylation were elevated in human RA synovial tissue. Annexin A2 is a key molecule in the DDR-2/annexin A2/MMP-13 loop, the activation of which contributes to joint destruction in RA, mainly through promoting invasion of FLS. Annexin A2 might therefore become a novel clinical target for RA treatment.