Mechanisms Of Rheumatoid Arthritis Research Articles

Identification of potential hub genes and biological mechanism in rheumatoid arthritis and non-small cell lung cancer via integrated bioinformatics analysis

BackgroundAlthough there is evidence of the association between RA and NSCLC, little is known about their interaction mechanisms. The aim of this study is to identify potential hub genes and biological mechanism in RA and NSCLC via integrated bioinformatics analysis. MethodsThe gene expression datasets of RA and NSCLC were downloaded to discover and validate hub genes. After identifying DEGs, we performed enrichment analysis, PPI network construction and module analysis, selection and validation of hub genes. Moreover, we selected the hub gene PTPRC for expression and prognosis analysis, immune analysis, mutation and methylation analysis in NSCLC. Finally, we performed real-time PCR, colony formation assay, wound healing assay, transwell invasion assay, sphere formation assay and western blotting to validate the role of PTPRC in A549 cells. ResultsWe obtained 320 DEGs for subsequent analysis. Enrichment results showed that the DEGs were mainly involved in Th1, Th2 and Th17 cell differentiation. In addition, four hub genes, BIRC5, PTPRC, PLEK, and FYN, were identified after selection and validation. These hub genes were subsequently shown to be closely associated with immune cells and related pathways. In NSCLC, PTPRC was downregulated, positively correlated with immune infiltration and immune cells. Experiments showed that PTPRC could promote the proliferation, migration and invasion, and the ability to form spheroids of A549 cells. In addition, PTPRC could regulate the increased expression of CD45, β-catenin, c-Myc and LEF1 proteins. ConclusionsThis study explored the hub genes and related mechanisms of RA and NSCLC, demonstrated the central role of the inflammatory response and the adaptive immune system, and identified PTPRC as an immune-related biomarker and potential therapeutic target for RA and NSCLC patients. In addition, PTPRC can significantly promote the proliferation, migration and invasion of A549 cells, and its mechanism may be to promote the EMT process by regulating the Wnt signaling pathway and promote cell stemness, which in turn has a promoting effect on A549 cells.

A Review of Proposed Mechanisms in Rheumatoid Arthritis and Therapeutic Strategies for the Disease.

Rheumatoid arthritis (RA) is characterized by synovial edema, inflammation, bone and cartilage loss, and joint degradation. Patients experience swelling, stiffness, pain, limited joint movement, and decreased mobility as the condition worsens. RA treatment regimens often come with various side effects, including an increased risk of developing cancer and organ failure, potentially leading to mortality. However, researchers have proposed mechanistic hypotheses to explain the underlying causes of synovitis and joint damage in RA patients. This review article focuses on the role of synoviocytes and synoviocytes resembling fibroblasts in the RA synovium. Additionally, it explores the involvement of epigenetic regulatory systems, such as microRNA pathways, silent information regulator 1 (SIRT1), Peroxisome proliferatoractivated receptor-gamma coactivator (PGC1-α), and protein phosphatase 1A (PPM1A)/high mobility group box 1 (HMGB1) regulators. These mechanisms are believed to modulate the function of receptors, cytokines, and growth factors associated with RA. The review article includes data from preclinical and clinical trials that provide insights into potential treatment options for RA.

Mechanism of lysine oxidase-like 1 promoting synovial inflammation mediating rheumatoid arthritis development.

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease that causes great distress to patients and society. Early diagnosis is the key to the successful treatment of RA. The basement membrane, one of the oldest tissue structures, is localized under the epithelium. Its complex composition and rich biological functions have made it a focus of research in recent years, while basement membrane-associated genetic variants are involved in most human disease processes. The aim of this study is to find new diagnostic biomarkers for RA and explore their role and possible mechanism in rheumatoid arthritis. The GSE12021, GSE55235 and GSE55457 datasets were downloaded from the GEO database. Their fraction associated with basement membrane genes was analyzed and differentially expressed genes between the disease and normal groups were explored. We identified two basement membrane-associated genes, lysine oxidase-like 1 (LOXL1) and discoid peptide receptor 2 (DDR2). Focusing on the more interesting LOXL1, we found that LOXL1 expression was significantly elevated in the synovium of patients with rheumatoid arthritis, and LOXL1 mRNA and protein levels were elevated in tumor necrosis factor α-stimulated human synovial sarcoma cells (SW982). And LOXL1 knockdown inhibited tumor necrosis factor α-induced inhibition in SW982 cells expression of inducible nitric oxide synthase (INOS), cyclooxygenase-2 (COX2), and interleukin-6 (IL-6). Interestingly, knockdown of LOXL1 inhibited the phosphorylation of PI3K and AKT. In summary, LOXL1 may become a novel diagnostic gene for RA, and knockdown of LoxL1 may inhibit synovial inflammation by affecting PI3K/AKT pathway.

Neutrophil extracellular traps: features of their formation in rheumatoid arthritis and osteoarthritis

The similarity of clinical manifestations and some pathogenetic mechanisms in rheumatoid arthritis (RA) and osteoarthritis (OA) is of particular interest in studying the features of extracellular neutrophil traps (NETs) formation in these musculoskeletal diseases. Our objective was to evaluate circulating neutrophil extracellular trap formation related to autoimmune inflammation in RA and reactive inflammation in OA.39 RA patients comprised the main group; 35 OA patients, control group; 33 healthy individuals were included into the reference group. Circulating neutrophils were isolated by the one-step centrifugation in double layer of iohexol density gradient. NETs were induced by phorbol-12-myristate-13–acetate (PMA) being visualized by fluorescence microscopy.The RA disease activity at the inclusion period should not exceed 2.6 DAS28 points. ОA patients were in clinical remission at the inclusion timepoint. In 17 RA patients, an increase in DAS28 exceeded 3.2 points; in 25 OA patients, an exacerbation was diagnosed during the study. The mean percentage of spontaneous and induced NETs in reference group was 3.8% (2.6-5.0) and 12.2% (9.0-15.4), respectively. Appropriate values for the patients with inactive RA were 5.9% (5.6-6.2) and 26% (23.9-28.1); 16.6% (16.1-17.1) and 38.0% (36.6-39.4) in active RA cases, respectively; 5.4% (5.2-5.6) and 20.3% (18.3-22.3) in OA without synovitis; 13.1% (12.6-18.1) and 28.3% (6. 4-30.2) in OA with synovitis, respectively. Spontaneous increase of NETs during RA activation was 181.4%; induced increase in NETs was 46.2%; and in cases of OA exacerbation these values were 142.6% and 39.4%, respectively. In RA patients, the rates of spontaneous NETs formation were 3.9 times higher than for induced values. Appropriate index was 3.6 times higher among the OA patients. The increase in spontaneous -to-induced NETs formation was more pronounced in active RA than in OA with synovitis. The main difference in NETs composition for active RA patients (in 88% of cases) and OA synovitis (in 50% of cases) is related to the contents of citrulline epitopes (p = 0.03).Transition of RA from the remission state to active inflammation, as well as OA exacerbation are accompanied by a significant increase in NETs, especially, spontaneous formation. The degree of increase in RA was higher than in OA, thus, probably, indicating higher involvement of neutrophils in generation of NETs during autoimmune inflammation rather than in reactive inflammation. A sufficient role of citrullinated epitopes in NETs demonstrates their influence upon induction and maintenance of autoimmune response to RA-specific autoantigens.

Identification and preliminary validation of synovial tissue-specific genes and their-mediated biological mechanisms in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease. It is well known that the formation of positive feedback between synovial hyperplasia and inflammatory infiltration is intimately associated with the occurrence and development of RA. However, the exact mechanisms still remain unknown, making the early diagnosis and therapy of RA difficult. This study was designed to identify prospective diagnostic and therapeutic biomarkers, as well as their-mediated biological mechanisms in RA. Three microarray datasets (GSE36700, GSE77298 and GSE153015) and two RNA-sequencing datasets (GSE89408 and GSE112656) of synovial tissues, as well as three other microarray datasets (GSE101193, GSE134087 and GSE94519) of peripheral blood were downloaded for integrated analysis. The differently expressed genes (DEGs) were identified by "limma" package of R software. Then, weight gene co-expression analysis and gene set enrichment analysis were performed to investigate synovial tissue-specific genes and their-mediated biological mechanisms in RA. The expression of candidate genes and their diagnostic value for RA were verified by quantitative real-time PCR and receiver operating characteristic (ROC) curve, respectively. Relevant biological mechanisms were explored through cell proliferation and colony formation assay. The suggestive anti-RA compounds were discovered by CMap analysis. We identified a total of 266 DEGs, which were mainly enriched in cellular proliferation and migration, infection and inflammatory immune signaling pathways. Bioinformatics analysis and molecular validation revealed 5 synovial tissue-specific genes, which exhibited excellent diagnostic value for RA. The infiltration level of immune cells in RA synovial tissue was significantly higher than that in control individuals. Moreover, preliminary molecular experiments suggested that these characteristic genes may be responsible for the high proliferation potential of RA fibroblast-like synoviocytes (FLSs). Finally, 8 small molecular compounds with anti-RA potential were obtained. We have proposed 5 potential diagnostic and therapeutic biomarkers (CDK1, TTK, HMMR, DLGAP5, and SKA3) in synovial tissues that may contribute to the pathogenesis of RA. These findings may shed light on the early diagnosis and therapy of RA.

Exploring the Potential of Phytocompounds for Targeting Epigenetic Mechanisms in Rheumatoid Arthritis: An In Silico Study Using Similarity Indexing

Finding structurally similar compounds in compound databases is highly efficient and is widely used in present-day drug discovery methodology. The most-trusted and -followed similarity indexing method is Tanimoto similarity indexing. Epigenetic proteins like histone deacetylases (HDACs) inhibitors are traditionally used to target cancer, but have only been investigated very recently for their possible effectiveness against rheumatoid arthritis (RA). The synthetic drugs that have been identified and used for the inhibition of HDACs include SAHA, which is being used to inhibit the activity of HDACs of different classes. SAHA was chosen as a compound of high importance as it is reported to inhibit the activity of many HDAC types. Similarity searching using the UNPD database as a reference identified aglaithioduline from the Aglaia leptantha compound as having a ~70% similarity of molecular fingerprints with SAHA, based on the Tanimoto indexing method using ChemmineR. Aglaithioduline is abundantly present in the shell and fruits of A. leptantha. In silico studies with aglaithioduline were carried out against the HDAC8 protein target and showed a binding affinity of -8.5 kcal mol. The complex was further subjected to molecular dynamics simulation using Gromacs. The RMSD, RMSF, compactness and SASA plots of the target with aglaithioduline, in comparison with the co-crystallized ligand (SAHA) system, showed a very stable configuration. The results of the study are supportive of the usage of A. leptantha and A. edulis in Indian traditional medicine for the treatment of pain-related ailments similar to RA. Our study therefore calls for further investigation of A. leptantha and A. edulis for their potential use against RA by targeting epigenetic changes, using in vivo and in vitro studies.

Multi-ancestry genome-wide association analyses identify novel genetic mechanisms in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a highly heritable complex disease with unknown etiology. Multi-ancestry genetic research of RA promises to improve power to detect genetic signals, fine-mapping resolution and performances of polygenic risk scores (PRS). Here, we present a large-scale genome-wide association study (GWAS) of RA, which includes 276,020 samples from five ancestral groups. We conducted a multi-ancestry meta-analysis and identified 124 loci (P < 5 × 10-8), of which 34 are novel. Candidate genes at the novel loci suggest essential roles of the immune system (for example, TNIP2 and TNFRSF11A) and joint tissues (for example, WISP1) in RA etiology. Multi-ancestry fine-mapping identified putatively causal variants with biological insights (for example, LEF1). Moreover, PRS based on multi-ancestry GWAS outperformed PRS based on single-ancestry GWAS and had comparable performance between populations of European and East Asian ancestries. Our study provides several insights into the etiology of RA and improves the genetic predictability of RA.

Arsenic trioxide modulates the composition and metabolic function of the gut microbiota in a mouse model of rheumatoid arthritis

The mechanism of rheumatoid arthritis (RA) has been widely investigated, and studies on the use of arsenic trioxide (ATO) in the treatment of RA have been reported in recent years. However, the exact mechanism of action of ATO in RA remains unclear. This study explores alterations in the gut microbiota and metabolism during ATO treatment in a mouse model of RA and provides an integrative analysis of the biomechanism. The purpose of this study was to verify whether ATO can alleviate RA by altering the gut microbiota. In this study, the mice were randomly divided into four different groups: the normal control (NC) group, the collagen-induced arthritis (CIA) group, the ATO 1.0 mg/kg/day group, and the ATO 2.0 mg/kg/day group. Fecal samples were collected. Through 16S rDNA gene sequencing and metabolomic analysis, the effect of ATO on the composition and metabolites of gut microbiota in CIA mice was investigated. The results showed that compared with NC mice, CIA mice showed differences at both the phylum level (Firmicutes and Bacteroidetes) and the genus level (Muribaculaceae_unclassified and Alistipes). Meanwhile, many metabolites were significantly changed between the two groups, including benzoic acid and (s)-2-acetolactate. However, these alterations were partially reversed in ATO-treated CIA mice. These results indicated that ATO treatment modulated gut microbiota disorder and improved fecal metabolite abnormalities. In conclusion, this study provided important evidence for alterations of the gut microbiota and metabolites and the role of these alterations in a potential novel mechanism of ATO treatment in RA.

A comprehensive insight into effects of resveratrol on molecular mechanism in rheumatoid arthritis: A literature systematic review.

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease, which is characterized by massive pain and destruction of synovial joints, leads to bone erosion, damage to cartilage, and disability. Several studies suggested that resveratrol supplementation may be effective in the prevention and management of RA. Therefore, a systematic review was conducted to summarize published studies that assess the effect of resveratrol supplementation on the complications of RA. A comprehensive search to identify in vitro, animal, and human studies investigating the impact of resveratrol on the complications of RA was performed up to February 2022. Two independent reviewers evaluated studies based on inclusion/exclusion criteria and performed data extraction. All studies examining the effects of resveratrol supplementation on the complications of RA were included. From a total of 571 retrieved articles, 32 studies were eligible for the current systematic review. The evidence reviewed here indicates that resveratrol supplementation may exert beneficial effects on the complications of RA by attenuating inflammation and oxidative stress, modulating the immune response, and down-regulating the messenger RNA expression of genes related to inflammatory pathways. Due to the promising therapeutic effects of resveratrol on RA complications and limited number of human studies in this subject, further clinical trials are suggested.

Therapeutic effects of Panax notoginseng saponins in rheumatoid arthritis: network pharmacology and experimental validation

ABSTRACT Panax notoginseng saponins (PNS) have been reported to have good anti-inflammatory effects. However, the anti-inflammatory effect mechanism in rheumatoid arthritis (RA) remains unknown. The focus of this research was to investigate the molecular mechanism of PNS in the treatment of RA. The primary active components of PNS were tested utilizing the Traditional Chinese Medicine Systems Pharmacology Database (TCMSP) and Analysis Platform based on oral bioavailability and drug-likeness. The target databases for knee osteoarthritis were created using GeneCards and Online Mendelian Inheritance in Man (OMIM). The visual interactive network structure ‘active component – action target – illness’ was created using Cytoscape software. A protein interaction network was built, and associated protein interactions were analyzed using the STRING database. The key targets were analyzed using Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO) biological process enrichment analyses. The effects of PNS on cell growth were studied in human umbilical vein endothelial cells (HUVECs) treated with various doses of PNS, and the optimum concentration of PNS was identified. PNS was studied for its implication on angiogenesis and migration. The active components of PNS had 114 common targets, including cell metabolism and apoptosis, according to the network analysis. The therapeutic effects of the PNS components were suggested to be mediated through apoptotic and cytokine signaling pathways. In vitro, PNS therapy boosted HUVEC proliferation. Wound healing, Boyden chamber and tube formation tests suggested that PNS may increase HUVEC activity and capillary-like tube branching. This study clarified that for the treatment of RA, PNS has multisystem, multicomponent, and multitargeted properties.

Some important inhibitors and mechanisms of rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic disease that seriously affects human health and quality of life, and it is one of the main causes of labor loss and disability. Many countries have listed rheumatoid arthritis as one of the national a key diseases to tackle. The pathogenesis of RA in humans is still unknown, and medical researchers believe that the pathogenesis of RA may be the result of a combination of genetic and environmental factors. RA is an incurable condition that can only be controlled and treated with conventional drugs. In this paper, the pathologic features and pathogenesis of RA were introduced, and the research progress of new anti-rheumatoid arthritis chemical drugs in recent years was reviewed.

Erythrocyte reduced/oxidized glutathione and serum thiol/disulfide homeostasis in patients with rheumatoid arthritis

BackgroundChronic inflammation and oxidative stress are the most known mechanisms in Rheumatoid Arthritis (RA) pathophysiology, which is still not fully elucidated. In this study, we evaluated oxidative status by determining intracellular reduced/oxidized glutathione (GSH/GSSG) homeostasis and serum thiol/disulfide (SH/SS) homeostasis in RA patients. MethodsA total of 152 RA patient and 89 healthy controls were included in the study. RA patients were subdivided according to disease activity score-28 (DAS-28) as active RA and remission RA. Intracellular GSH/GSSG and serum SH/SS homeostasis parameters were analyzed. ResultsMedian (1st–3rd quartile values) SS/SH and GSSG/GSH percent ratio levels were significantly higher in RA patients (6.94 (6.02–8.54) and 69.8 (44.05–85.29); respectively) compared to controls (4.62 (4.15–5.46) and 34.9 (22.43–62.2); respectively) (p < 0.05 for all). SS/SH and GSSG/GSH percent ratio levels were significantly higher in active RA patients when compared to remission RA patients and controls (p < 0.05 for all). SS/SH and GSSG/GSH percent ratios were significantly increased in remission RA group compared to controls (p < 0.05 for all). DAS28 scores were positively correlated with SS/SH and GSSG/GSH percent ratios (rho = 0.259 and 0.296; respectively). ConclusionsThese findings suggest that active intracellular and extracellular thiol group oxidation process might play a role in RA pathogenesis and further work in these areas may be warranted to show potential value of evaluating intracellular GSSG/GSH and serum SH/SS balances together in disease monitoring.

Si Miao San Attenuates Inflammation and Oxidative Stress in Rats with CIA via the Modulation of the Nrf2/ARE/PTEN Pathway.

Objective Si Miao San (SMS) is a traditional Chinese formula used in China to treat rheumatic diseases. To date, its mechanism in rheumatoid arthritis (RA) treatment is uncertain. Our study aims to assess the antiarthritic effects of SMS in experimental arthritic rats. Materials and Methods SMS (8.63, 4.31, and 2.16 g/kg/day) was orally administered after the first immunization from day 14 to day 53. The effects of SMS on rats with collagen-induced arthritis (CIA) were evaluated by arthritis score and histological assessment. The levels of cytokines and anti-CII antibodies in rat serum were measured by ELISAs. The expression of oxidative stress parameters was detected by biochemical assay kits. The levels of Nrf2, HO-1, NQO1, and PTEN were determined by western blotting. Results Medium- and high-dose SMS treatment significantly decreased arthritis scores and alleviated ankle joint histopathology in the rats with CIA. It inhibited the production of IL-6, TNF-α, COX-2, and PGE2 in rat serum. SMS also suppressed the expression of anti-CII antibodies IgG1 and IgG2a. Moreover, SMS significantly suppressed the levels of MDA and MPO in the synovial tissues while increasing the levels of SOD and CAT in the rats with CIA. The levels of Nrf2, HO-1, NQO1, and PTEN were upregulated by SMS in rat synovial tissues. Conclusions This study demonstrated that SMS effectively alleviated the disease progression of CIA by decreasing the levels of proinflammatory cytokines and reducing oxidative stress damage, as indicated by IL-6, TNF-α, COX-2, and PGE2 levels; inhibiting the overproduction of MDA and MPO; and enhancing antioxidant enzymes by upregulating the Nrf2/ARE/PTEN signalling pathway.

Pain Mechanism in Rheumatoid Arthritis: From Cytokines to Central Sensitization.

Pain is the most common symptom in patients with rheumatoid arthritis (RA). Although in recent years, through the implementation of targeted treatment and the introduction of disease-modifying antirheumatic drugs (DMARDs), the treatment of RA patients has made a significant progress, a large proportion of patients still feel pain. Finding appropriate treatment to alleviate the pain is very important for RA patients. Current research showed that, in addition to inflammation, RA pain involves peripheral sensitization and abnormalities in the central nervous system (CNS) pain regulatory mechanisms. This review summarized the literature on pain mechanisms of RA published in recent years. A better understanding of pain mechanisms will help to develop new analgesic targets and deploy new and existing therapies.

Sprouty2 Inhibits Migration and Invasion of Fibroblast-Like Synoviocytes in Rheumatoid Arthritis by Down-regulating ATF2 Expression and Phosphorylation.

Activating transcription factor 2(ATF2), a transcription factor belonging to the AP-1 family, plays an important role in inflammation. However, its biological functions and underlying molecular mechanisms in rheumatoid arthritis (RA) remain unclear. Western blot and immunohistochemistry were used to identify the expression of ATF2 and Sprouty2(SPRY2) in RA synovial tissues. SW982 cells were stimulated by TNF-α to establish an in vitro RA fibroblast-like synoviocyte (RA-FLS) model. Transwell and monolayer wound-healing were used to detect cell migration and invasion. RNA interference (si-ATF2) and adenovirus vector (Ad-SPRY2) methods were employed to manipulate ATF2 or SPRY2 expression in SW982 cells. The protein expression and phosphorylation levels in SW982 cells were evaluated by western blot. ATF2 expression and phosphorylation were upregulated in the RA synovial tissues. In RA-FLS model, ATF2 expression and phosphorylation were increased in a time-dependent manner. ATF2 knockdown inhibited the migration and invasion of RA-FLS model, reducing the inflammatory factors, which was consistent with the influence on cell behaviors caused by SPRY2 overexpression. Moreover, SPRY2 overexpression inhibited the TNF-α-induced phosphorylation of ERK and ATF2 in SW982 cells. The high expression and phosphorylation of ATF2 promoted migration and invasion of RA-FLSs. SPRY2 might inhibited the inflammatory responses of RA-FLSs via suppressing ERK-ATF2 pathway.

MiR-1193 represses the proliferation and induces the apoptosis of interleukin-1β-treated fibroblast-like synoviocytes via targeting JAK3.

To explore the roles of miR-1193/Janus kinase 3 (JAK3) axis and the potential mechanism in rheumatoid arthritis (RA). The dysregulated genes and microRNAs (miRNAs) were screened using the datasets of GSE12021 and GSE72564, while the upstream miRNA of JAK3 was forecasted by TargetScan. Then the MH7A cells were treated with interleukin-1β (IL-1β) to induce local inflammation. Double luciferase report assay was used to estimate the association between JAK3 and miR-1193. Flow cytometry and 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assays were taken to analyze the apoptosis and proliferation of MH7A cells with IL-1β-induced inflammation, respectively. The relative expression of genes and proteins were detected by quantitative real-time polymerase chain reaction and western blot analyses. Finally, rescue experiments were employed to explore the effects of miR-1193/JAK3 axis on IL-1β-induced inflammation. JAK3 was notably up-regulated in RA, and was targeted and negatively regulated by miR-1193 which was lowly expressed in RA tissues and IL-1β-treated cells. MiR-1193 mimic significantly inhibited while miR-1193 inhibitor promoted the proliferation of MH7A cells with IL-1β-induced inflammation. Furthermore, overexpression of JAK3 presented auxo-action while depletion of JAK3 exhibited inhibitory effect on the proliferation of MH7A cells with IL-1β-induced inflammation, which could be weakened by miR-1193 mimic and miR-1193 inhibitor, respectively. Analogously, JAK3 recovered the cell proliferation that inhibited by miR-1193 mimic and inhibited cell apoptosis enhanced by miR-1193 mimic. Up-regulation of miR-1193 suppressed the proliferation and expedited the apoptosis of MH7A cells with IL-1β-induced inflammation through targeting JAK3, which might provide novel understanding on the mechanism underlying RA.

PTPN22 1858 C/T polymorphism is associated with alteration of cytokine profiles as a potential pathogenic mechanism in rheumatoid arthritis

IntroductionRheumatoid arthritis (RA) is one of the most common prevalent autoimmune diseases. The 1858 C/T (rs2476601) single nucleotide polymorphism (SNP) within the PTPN22 gene has been associated with susceptibility to inflammatory based diseases in several populations. It is implicated that altered cytokine production has a potential pathogenic role in the development of RA. The aim of this work was to analyze the association of 1858 C/T PTPN22 polymorphism in RA patients with cytokine profiles. Materials and MethodsThis study was performed on 120 RA patients who were referred to the Rheumatology Research Centre, Shariati Hospital (Tehran, Iran), and 120 healthy controls. Genomic DNA was extracted and genotyped for 1858 C/T PTPN22 gene SNP using the PCR-RFLP technique. Serum levels of IL-2, IL-4, IL-6, IL-10, TNF-α and IFN-γ as well as Anti−CCP and RF was measured by ELISA method. ResultsResults showed that 1858 C/T PTPN22 SNP significantly (P = 0.007, OR = 2.321, 95% CI = 1.063–5.067) associated with RA. The 1858 T allele frequency was also significantly increased in RA patients in comparison to the controls (P = 0.008, OR = 3.583, 95% CI = 1.3–9.878). Our data demonstrated a significant reduction of IL-4 and IL-10 in PTPN22 1858C/T compared to 1858C/C RA patients. In addition, upregulation of IL-6, IFN-γ, and TNF-α was observed in PTPN22 1858C/T vs. 1858C/C RA patients. DiscussionOur findings implicate altered cytokine profiles as a possible pathogenic mechanism by which the 1858 T allele may contribute to the progress of RA.

JAK/STAT Blockade Alters Synovial Bioenergetics, Mitochondrial Function, and Proinflammatory Mediators in Rheumatoid Arthritis.

To examine the effects of tofacitinib on metabolic activity, mitochondrial function, and proinflammatory mechanisms in rheumatoid arthritis (RA). Ex vivo RA synovial explants and primary RA synovial fibroblasts (RASFs) were cultured with 1 μM tofacitinib. RASF bioenergetics were assessed using an XF24 analyzer, and key metabolic genes were assessed by reverse transcription-polymerase chain reaction (RT-PCR) analysis. Mitochondrial function was assessed using specific cell fluorescent probes and by mitochondrial gene arrays. Mitochondrial mutagenesis was quantified using a mitochondrial random mutation capture assay, and lipid peroxidation was quantified by enzyme-linked immunosorbent assay (ELISA). The effect of tofacitinib on spontaneous release of proinflammatory mediators from RA whole tissue synovial explants was quantified by ELISAs/MSD multiplex assays, and metabolic markers were quantified by RT-PCR. Finally, RASF invasion, matrix degradation, and synovial outgrowths were assessed by transwell invasion/Matrigel outgrowth assays and ELISA. Tofacitinib significantly decreased mitochondrial membrane potential, mitochondrial mass, and reactive oxygen species production by RASFs and differentially regulated key mitochondrial genes. Tofacitinib significantly increased oxidative phosphorylation, ATP production, and the maximal respiratory capacity and the respiratory reserve in RASFs, an effect paralleled by a decrease in glycolysis and the genes for the key glycolytic enzymes hexokinase 2 (HK2), glycogen synthase kinase 3α (GSK-3α), lactate dehydrogenase A, and hypoxia-inducible factor 1α. Tofacitinib inhibited the effect of oncostatin M (OSM) on interleukin-6 (IL-6) and monocyte chemotactic protein 1 and reversed the effects of OSM on RASF cellular metabolism. Using RA whole tissue synovial explants, we found that tofacitinib inhibited the key metabolic genes for glucose transporter 1, 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3, 3'-phosphoinositide-dependent protein kinase 1, HK2, and GSK-3α, the proinflammatory mediators IL-6, IL-8, IL-1β, intercellular adhesion molecule 1, vascular endothelial growth factor, and TIE-2, and RASF outgrowth from synovial explants, RASF invasion, and matrix metalloproteinase 1 activity. This study demonstrates that JAK/STAT signaling mediates the complex interplay between inflammation and cellular metabolism in RA pathogenesis.

Matrix Metalloproteinase Gene Activation Resulting from Disordred Epigenetic Mechanisms in Rheumatoid Arthritis.

Matrix metalloproteinases (MMPs) are implicated in the degradation of extracellular matrix (ECM). Rheumatoid arthritis (RA) synovial fibroblasts (SFs) produce matrix-degrading enzymes, including MMPs, which facilitate cartilage destruction in the affected joints in RA. Epigenetic mechanisms contribute to change in the chromatin state, resulting in an alteration of gene transcription. Recently, MMP gene activation has been shown to be caused in RASFs by the dysregulation of epigenetic changes, such as histone modifications, DNA methylation, and microRNA (miRNA) signaling. In this paper, we review the role of MMPs in the pathogenesis of RA as well as the disordered epigenetic mechanisms regulating MMP gene activation in RASFs.

Interplay between genetic and epigenetic mechanisms in rheumatoid arthritis.

Genetic and environmental factors contribute to the risk for rheumatoid arthritis (RA), with epigenetics serving as a possible interface through which risk factors contribute to RA. High-throughput technologies for interrogating genome and epigenome, and the availability of genetic and epigenetic datasets across a diversity of cell types, enable the identification of candidate causal genetic variants for RA to study their function in core RA processes. To date, RA risk variants were studied in the immune cells but not joint resident cells, for example, synovial fibroblasts. Synovial fibroblasts from different joints are distinct, anatomically specialized cells, defined by joint-specific transcriptomes, epigenomes and phenotypes. Cell type-specific analysis of epigenetic changes, together with genetic fine mapping and interrogation of chromatin 3D interactions may identify new disease relevant pathways, potential therapeutic targets and biomarkers for RA progression or therapy response.