The environment, geo-epidemiology, and autoimmune disease: Rheumatoid arthritis

Major involvement of bacterial components in rheumatoid arthritis and its accompanying oxidative stress, systemic inflammation and hypercoagulability

We review the evidence that infectious agents, including those that become dormant within the host, have a major role to play in much of the etiology of rheumatoid arthritis and the inflammation that is its hallmark. This occurs in particular because they can produce cross-reactive (auto-)antigens, as well as potent inflammagens such as lipopolysaccharide that can themselves catalyze further inflammagenesis, including via β-amyloid formation. A series of observables coexist in many chronic, inflammatory diseases as well as rheumatoid arthritis. They include iron dysregulation, hypercoagulability, anomalous morphologies of host erythrocytes, and microparticle formation. Iron dysregulation may be responsible for the periodic regrowth and resuscitation of the dormant bacteria, with concomitant inflammagen production. The present systems biology analysis benefits from the philosophical idea of "coherence," that reflects the principle that if a series of ostensibly unrelated findings are brought together into a self-consistent narrative, that narrative is thereby strengthened. As such, we provide a coherent and testable narrative for the major involvement of (often dormant) bacteria in rheumatoid arthritis.

Treatment for Rheumatoid Arthritis and Risk of Alzheimer's Disease: A Nested Case-Control Analysis

INTRODUCTION

It is increasingly becoming accepted that inflammation may play an important role in the pathogenesis of Alzheimer's disease (AD), as several immune-related genes have been associated with AD. Among these is tumor necrosis factor (TNF)-α, a proinflammatory cytokine known to play an important role in autoimmune disorders, including rheumatoid arthritis (RA). Although AD and RA appear to involve similar pathological mechanisms through the production of TNF-α, the relationship between AD and RA remains unknown.

OBJECTIVE

To determine the relative risk of AD among RA patients and non-RA patients, and whether anti-TNF therapy for RA was associated with a lower risk of AD in RA patients.

METHODS

We performed a nested case-control study of more than 8.5 million commercially insured adults (aged ≥18 years) in all 50 US states, Puerto Rico, and US Virgin Islands in the Verisk Health claims database. We derived a sub-cohort of subjects with a diagnosis of RA (controls), or RA and AD (cases), matching cases and controls based on age, sex, exposure assessment period, and methotrexate treatment. We also assessed relative risk of AD following exposure to standard RA therapies, including anti-TNF agents (infliximab, adalimumab, etanercept), methotrexate, prednisone, sulfasalazine, and rituximab. Odds ratios were adjusted for comorbidities, including coronary artery disease, diabetes mellitus, and peripheral vascular disease.

RESULTS

AD was more prevalent (p < 0.0001) among RA patients (0.79 %) than among those without RA (0.11 %). Chronic conditions such as coronary artery disease (odds ratio [OR] 1.48; 95 % confidence interval [CI] 1.04-2.05; p = 0.03), diabetes (OR 1.86; 95 % CI 1.32-2.62; p = 0.0004), and peripheral vascular disease (OR 1.61; 95 % CI 1.06-2.43; p = 0.02) significantly increased the relative risk of AD among RA patients. Exposure to anti-TNF agents as a class, but not other immunosuppressive drugs studied, was associated with lowered risk of AD among RA patients (unadjusted OR 0.44; 95 % CI 0.22-0.87; p = 0.02; adjusted OR 0.45; 95 % CI 0.23-0.90; p = 0.02). Sub-group analysis demonstrated that of the three anti-TNF agents studied, only etanercept (unadjusted OR, 0.33; 95 % CI 0.08-0.94; p = 0.03; adjusted OR 0.30; 95 % CI 0.08-0.89; p = 0.02) was associated with a decreased risk of AD in RA patients.

CONCLUSION

There is an increased risk of AD in the studied RA population. The relative risk of AD among RA subjects was lowered in those exposed to etanercept. Anti-TNF therapy with etanercept shows promise as a potential treatment for AD.

Genetic markers as therapeutic target in rheumatoid arthritis: A game changer in clinical therapy?

Rheumatoid arthritis (RA) is a chronic, inflammatory, multi-systemic autoimmune disease unremitted by genetic and environmental factors. The factors are crucial but inadequate in the development of disease; however, these factors can be representative of potential therapeutic targets and response to clinical therapy. Insights into the contribution of genetic risk factors are currently in progress with studies querying the genetic variation, their role in gene expression of coding and non-coding genes and other mechanisms of disease. In this review, we describe the significance of genetic markers architecture of RA through genome-wide association studies and meta-analysis studies. Further, it also reveals the mechanism of disease pathogenesis investigated through the mutual findings of functional and genetic studies of individual RA-associated genes, which includes HLA-DRB1, HLA-DQB1, HLA-DPB1, PADI4, PTPN22, TRAF1-C5, STAT4 and C5orf30. However, the genetic background of RA remains to be clearly depicted. Prospective efforts of the post-genomic and functional genomic period can travel toward real possible assessment of the genetic effect on RA. The discovery of novel genes associated with the disease can be appropriate in identifying potential biomarkers, which could assist in early diagnosis and aggressive treatment.

Rheumatoid arthritis onset in postmenopausal women: Does the ACPA seropositive subset result from genetic effects, estrogen deficiency, skewed profile of CD4(+) T-cells, and their interactions?

Rheumatoid arthritis (RA) incidence displays a differentiated age-dependent female-to-male ratio in which women outnumber men. Evidence that the peak incidence of RA in women coincides with menopause age, suggests a potential estrogenic role to disease etiology. Estrogens exert physiologically both stimulatory and inhibitory effects on the immune system. Epidemiologic and animal model studies with estrogen deprivation or supplementation suggested estrogens as to play, mainly, a protective role in RA immunopathology. In this review, we propose that some yet unidentified disturbances associated with estrogen circulating levels, differentiated by the menopausal status, play a major role in women's RA susceptibility. We focus on the interaction between estrogen deprivation and genetic risk alleles for anti-citrullinated protein antibodies (ACPA) seropositive RA, as a major driving force for increased immune reactivity and RA susceptibility, in postmenopausal women. This opens up new fields for research concerning the association among different irregular estrogenic conditions, the cytokine milieu, and age/menopausal status bias in RA.

Zhoubo plus uncaria tincture in the treatment of cerebral concussion sequelae

[Purpose] This study investigated the clinical efficacy of the compound gouteng tincture combined with Zhoubo (GT-ZB) in treating the sequelae of cerebral concussion (CC) in children. [Subjects and Methods] Sixty children with CC-sequelae were randomily divided into a treatment group and a control group, with 30 cases in each group. The treatment group was treated using GT-ZB, and the control group was treated using the standard method of venoruton, dibazol, and Vitamin B6. The efficacies of the two treatments were compared. [Results] Compared with the control group, the clinical symptoms and signs in the treatment group were significantly mitigated. [Conclusion] GT-ZB demonstrated efficacy in treating the sequelae of CC in children, and it is worthy of further studies and possible clinical recommendations.

Economic Burden of Switching to a Non-Tumor Necrosis Factor Inhibitor Versus a Tumor Necrosis Factor Inhibitor Biologic Therapy among Patients with Rheumatoid Arthritis

INTRODUCTION

The objective of this study was to examine healthcare resource utilization (HRU) and costs associated with switching to another tumor necrosis factor alpha inhibitor (TNFi) therapy versus a non-TNFi therapy among patients with rheumatoid arthritis (RA) discontinuing use of an initial TNFi biologic therapy.

METHODS

Patients with ≥2 RA diagnoses who used ≥1 TNFi on or after their initial RA diagnosis were identified in a US employer-based insurance claims database. Patients were selected based on ≥1 claim of another TNFi or a non-TNFi biologic therapy (occurring after 2010, and within 30 days before to 60 days after discontinuation of the initial TNFi), and continuous insurance ≥6 months before (baseline period) and ≥12 months after the switch date (study period). Patient demographic and clinical characteristics were measured during the baseline period. All-cause and RA-related HRU and costs were analyzed during the 12-month study period using multivariable regression analysis controlling for baseline characteristics and selected comorbidities.

RESULTS

Of the 1577 patients with RA that switched therapies, 1169 patients used another TNFi and 408 patients used a non-TNFi biologic. The most commonly used initial TNFi treatments were etanercept (50%) and adalimumab (34%) among the TNFi cohort, and infliximab (39%) and etanercept (28%) among the non-TNFi cohort. The TNFi cohort had significantly fewer outpatient visits [all-cause: 23.01 vs. 29.77 visits/patient/year; adjusted incidence rate ratio (IRR) = 0.78, P < 0.001; RA-related: 7.42 vs. 13.58; adjusted IRR = 0.58, P < 0.001] and rheumatologist visits (all-cause: 4.01 vs. 6.81; adjusted IRR = 0.66, P < 0.001; RA-related: 3.23 vs. 6.40; adjusted IRR = 0.58, P < 0.001) than the non-TNFi cohort. All-cause total costs were significantly lower for patients who switched to another TNFi instead of a non-TNFi therapy ($36,932 vs. $44,566; adjusted difference = $7045, P < 0.01), as were total RA-related costs ($26,973 vs. $31,735; adjusted difference = $4904, P < 0.01).

CONCLUSION

Adult patients with RA discontinuing TNFi therapy who switched to an alternative TNFi incurred lower healthcare costs than patients who switched to a non-TNFi biologic.

FUNDING

AbbVie, Inc.

TCR-CD3ζ gene polymorphisms and expression profile in rheumatoid arthritis

OBJECTIVES

Recent evidence has demonstrated that CD3ζ (also called CD247) play a vital role in multiple autoimmune diseases. In this study, we explored the association between CD247 gene single-nucleotide polymorphisms (SNPs) and rheumatoid arthritis (RA) in a Chinese Han population. We also evaluated the CD3ζ expression profile in peripheral blood mononuclear cells (PBMCs) from patients with RA and health controls.

METHODS

Three CD247 polymorphisms (rs704853, rs1214611 and rs858554) were studied in 612 patients with RA and 848 controls in a Chinese population. Genotyping was performed using the Fluidigm 192.24 Dynamic Array™ Integrated Fluidic Circuit (IFC). For gene expression study, CD3ζ mRNA levels of 36 patients with RA and 39 healthy individuals were assessed by real-time polymerase chain reaction (RT-PCR). Data were analyzed by SPSS 11.5 software.

RESULTS

A significant association between rs858554 polymorphism and RA was found under all genetic models (all p < 0.05). Moreover, we found the genotype distribution and allele frequency of rs858554 were significant associated with ACCP⁺ and RF⁺ phenotype as compare to health controls (all p < 0.05). Unfortunately, we did not detect any significant associations between rs704853, rs1214611 and RA susceptibility and autoantibody profiles (all p > 0.05). The gene expression assays showed that CD3ζ mRNA levels were downregulated in PBMCs of patients with RA when compared to healthy controls.

CONCLUSIONS

Our results, the first reported for distinct Chinese populations, support a role of the CD247 gene in the susceptibility to RA. Further studies with more sample size are necessary to clarify the exact role of CD247 gene in the pathogenesis of RA.

Molecular Insight into Gut Microbiota and Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a systemic, inflammatory, and autoimmune disorder. Gut microbiota play an important role in the etiology of RA. With the considerable progress made in next-generation sequencing techniques, the identified gut microbiota difference between RA patients and healthy individuals provides an updated overview of the association between gut microbiota and RA. We reviewed the reported correlation and underlying molecular mechanisms among gut microbiota, the immune system, and RA. It has become known that gut microbiota contribute to the pathogenesis of RA via multiple molecular mechanisms. The progressive understanding of the dynamic interaction between gut microbiota and their host will help in establishing a highly individualized management for each RA patient, and achieve a better efficacy in clinical practice, or even discovering new drugs for RA.

Mechanism of Xinfeng Capsule on Adjuvant-Induced Arthritis via Analysis of Urinary Metabolomic Profiles

We aimed to explore the potential effects of Xinfeng capsule (XFC) on urine metabolic profiling in adjuvant-induced arthritis (AA) rats by using gas chromatography time-of-flight mass spectrometry (GC-TOF/MS). GC-TOF/MS technology was combined with multivariate statistical approaches, such as principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and orthogonal projections to latent structures discriminant analysis (OPLS-DA). These methods were used to distinguish the healthy group, untreated group, and XFC treated group and elucidate potential biomarkers. Nine potential biomarkers such as hippuric acid, adenine, and L-dopa were identified as potential biomarkers, indicating that purine metabolism, fat metabolism, amino acid metabolism, and energy metabolism were disturbed in AA rats. This study demonstrated that XFC is efficacious for RA and explained its potential metabolomics mechanism.

Experiences of Patients With Rheumatoid Arthritis: A Qualitative Study

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that greatly impacts one's physical and psychosocial well-being. The purpose of this study was to explore the experiences and support needs of adult patients living with RA. A descriptive qualitative study was conducted, and 16 adults with RA were interviewed from October 2013 to January 2014. The transcribed data were analyzed using thematic analysis. Five themes were identified: altered physical capacity and well-being, psychological and emotional challenges, changes in social life, coping strategies, and support received and further support needs. This study provided insights into the experiences and support needs of patients with RA in Singapore. Physical and psychosocial challenges experienced by patients affected their daily and social activities. Patients' needs for variety of support should be addressed.

Epidemiological profile of colombian patients with rheumatoid arthritis in a specialized care clinic

INTRODUCTION

Few studies report the epidemiological profile of RA patients attending clinics for comprehensive care. We describe the clinical, socio-demographic characteristics and comorbidities of a cohort of patients with RA.

METHODS

Cross-sectional study in a cohort of patients according to ACR criteria/EULAR 2010 classification who have entered to the AR clinic since October 2012 until May 2014, referred from primary care. Frequencies for socio-demographic, comorbidity, state of disease activity, functional status, biomarkers and therapeutic modalities variables are described.

RESULTS

In total, 1652 patients were included with a mean age of 58 years and a duration of 9 years. Rheumatoid factor was positive in 80% and anti-citrullinated peptide antibody in 63% of patients. In total, 43.6% of patients had comorbidities: Hypertension (20.4%), osteoporosis (17.3%) and Sjögren's syndrome (10.4%). Fifty percent of the patients had moderate and high disease activity level measured by DAS-28 score, and the mean HAQ score was 0.64 (DS 1.12). Seventy three percent of patients were treated with oral disease modified anti rheumatic treatment and 63.6% of them were with methotrexate. 42.4% of the patients were treated with glucocorticoids (mean dose 6.3mg).

CONCLUSIONS

The epidemiological behavior of a group of RA patients is reported. The presence of comorbidities is significant affecting the risk of morbidity and mortality in these patients. The definition of the epidemiological profile of this population will allow the design of research questions to resolve outstanding problems in the clinical context of this pathology.

Genetics of rheumatoid arthritis: a new boost is needed in Latin American populations

Rheumatoid arthritis (RA) is an autoimmune inflammatory rheumatic disease which affects several organs and tissue, predominantly the synovial joints. Like many other autoimmune diseases, RA is a complex disease, where genetic variants, environmental factors and random events interact to trigger pathological pathways. Genetic implication in RA is evident, and recent advances have expanded our knowledge about the genetic factors that contribute to RA. An exponential increment in the number of genes associated with the disease has been described, mainly through gene wide screen studies (GWAS) involving international consortia with large patient cohorts. However, there are a few studies on Latin American populations. This article describes what is known about the RA genetics, the future that is emerging, and how this will develop a more personalized approach for the treatment of the disease. Latin American RA patients cannot be excluded from this final aim, and a higher collaboration with the international consortia may be needed for a better knowledge of the genetic profile of patients from this origin.

Native Joint Septic Arthritis: Epidemiology, Clinical Features, and Microbiological Causes in a New Zealand Population

Objective.

To determine the epidemiology, clinical features, and microbiology of adult native joint septic arthritis in Canterbury, New Zealand, over a 5-year period in individuals with and without an underlying rheumatic disorder.

Methods.

Patients with native joint septic arthritis were identified retrospectively and classified by Newman’s criteria. The clinical characteristics were described and comparisons made between those with and without underlying rheumatic disease.

Results.

Two hundred forty-eight cases of native joint septic arthritis (mean age 60, range 16–97 yrs) were identified with an overall incidence rate of 12.0/100,000/year (95% CI 10.6–13.6). Yearly incidence increased with age to a maximum of 73.4/100,000 in those > 90 years of age. Septic arthritis was iatrogenic in 16.9% of cases while 27% had an underlying inflammatory arthritis including gout (14.9%), calcium pyrophosphate disease (8.5%), and rheumatoid arthritis (4%). Few patients were taking immunosuppressant therapy, with just 1 taking a biological agent. Staphylococcus aureus was the most commonly identified organism. Those with underlying inflammatory arthritis were significantly older (73.6 yrs vs 55.6 yrs; p < 0.001), more likely to be female (55.2% vs 26.0%; p < 0.001), and to have septic polyarthritis (16.4% vs 4.4%; p = 0.002). The 30-day mortality was 2%, increasing to 6% at 90 days.

Conclusion.

The incidence of septic arthritis in Canterbury, New Zealand, is higher than in previous studies. Crystal arthropathy commonly coexisted with infection although autoimmune arthritis and immunosuppression was less of a factor than anticipated.

Methotrexate-loaded lipid-core nanocapsules are highly effective in the control of inflammation in synovial cells and a chronic arthritis model

BACKGROUND

Rheumatoid arthritis (RA) is the most common autoimmune disease in the word, affecting 1% of the population. Long-term prognosis in RA was greatly improved following the introduction of highly effective medications such as methotrexate (MTX). Despite the importance of this drug in RA, 8%-16% of patients must discontinue the treatment because of adverse effects. Last decade, we developed a promising new nanocarrier as a drug-delivery system, lipid-core nanocapsules.

OBJECTIVE

The aim of the investigation reported here was to evaluate if methotrexate-loaded lipid-core nanocapsules (MTX-LNC) reduce proinflammatory and T-cell-derived cytokines in activated mononuclear cells derived from RA patients and even in functional MTX-resistant conditions. We also aimed to find out if MTX-LNC would reduce inflammation in experimentally inflammatory arthritis at lower doses than MTX solution.

METHODS

Formulations were prepared by self-assembling methodology. The adjuvant arthritis was induced in Lewis rats (AIA) and the effect on edema formation, TNF-α levels, and interleukin-1 beta levels after treatment was evaluated. Mononuclear cells obtained from the synovial fluid of RA patients during articular infiltration procedures were treated with MTX solution and MTX-LNC. For in vitro experiments, the same dose of MTX was used in comparing MTX and MTX-LNC, while the dose of MTX in the MTX-LNC was 75% lower than the drug in solution in in vivo experiments.

RESULTS

Formulations presented nanometric and unimodal size distribution profiles, with D[4.3] of 175±17 nm and span of 1.6±0.2. Experimental results showed that MTX-LNC had the same effect as MTX on arthritis inhibition on day 28 of the experiment (P<0.0001); however, this effect was achieved earlier, on day 21 (P<0.0001), by MTX-LNC, and this formulation had reduced both TNF-α (P=0.001) and IL-1α (P=0.0002) serum levels by the last day of the experiment. Further, the MTX-LNC were more effective at reducing the cytokine production from mononuclear synovial cells than MTX.

CONCLUSION

The MTX-LNC were better than the MTX solution at reducing proinflammatory cytokines and T-cell-derived cytokines such as interferon-gamma and interleukin-17A. This result, combined with the reduction in the dose required for therapy, shows that MTX-LNC are a very promising system for the treatment of RA.

Human autoimmune diseases: a comprehensive update

There have been significant advances in our understanding of human autoimmunity that have led to improvements in classification and diagnosis and, most importantly, research advances in new therapies. The importance of autoimmunity and the mechanisms that lead to clinical disease were first recognized about 50 years ago following the pioneering studies of Macfarlane Burnett and his Nobel Prize-winning hypothesis of the 'forbidden clone'. Such pioneering efforts led to a better understanding not only of autoimmunity, but also of lymphoid cell development, thymic education, apoptosis and deletion of autoreactive cells. Contemporary theories suggest that the development of an autoimmune disease requires a genetic predisposition and environmental factors that trigger the immune pathways that lead, ultimately, to tissue destruction. Despite extensive research, there are no genetic tools that can be used clinically to predict the risk of autoimmune disease. Indeed, the concordance of autoimmune disease in identical twins is 12-67%, highlighting not only a role for environmental factors, but also the potential importance of stochastic or epigenetic phenomena. On the other hand, the identification of cytokines and chemokines, and their cognate receptors, has led to novel therapies that block pathological inflammatory responses within the target organ and have greatly improved the therapeutic effect in patients with autoimmune disease, particularly rheumatoid arthritis. Further advances involving the use of multiplex platforms for diagnosis and identification of new therapeutic agents should lead to major breakthroughs within the next decade.

Remodeling of plasma lipoproteins in patients with rheumatoid arthritis: Interleukin-6 receptor-alpha inhibition with tocilizumab

PURPOSE

Rheumatoid arthritis (RA) is associated with increased cardiovascular risk, mediated in part by elevated circulating interleukin-6 levels and proinflammatory changes in plasma lipoproteins. We hypothesized that RA patients acquire inflammation-induced modifications to the protein cargo of circulating lipoproteins that may be reversed by tocilizumab, an interleukin-6 receptor-alpha inhibitor.

EXPERIMENTAL DESIGN

Size-exclusion chromatography and reverse-phase protein arrays using 29 antibodies against 26 proteins were applied at baseline and after tocilizumab treatment to analyze the distributions of apolipoproteins, enzymes, lipid transfer proteins, and other associated proteins in plasma lipoprotein fractions from 20 women with RA.

RESULTS

A 30% reduction in high-density lipoprotein (HDL)-associated serum amyloid A4 and complement C4 occurred with tocilizumab. Levels of C-reactive protein, associated or comigrating with HDL and low-density lipoprotein (LDL) peaks, were reduced on treatment by approximately 80% and 24%, respectively. Reductions in lipoprotein-associated phospholipase A2, lipoprotein (a), and cholesteryl ester transfer protein in the LDL fraction suggest reductions in LDL-associated proatherogenic factors. Elevations in very low-density lipoprotein (VLDL) enriched with apolipoprotein E were equally observed.

CONCLUSIONS AND CLINICAL RELEVANCE

Tocilizumab treatment led to reductions in proinflammatory components and proatherogenic proteins associated with HDL. Whether changes in the proteome of VLDL, LDL, and HDL induced by anti-inflammatory tocilizumab treatment in RA patients modify cardiovascular disease risk requires further investigation.

Cost analysis of biologic drugs in rheumatoid arthritis first line treatment after methotrexate failure according to patients' body weight

OBJECTIVE

The objective was to assess the influence of patients' weight in the cost of rheumatoid arthritis treatment with biologic drugs used in first line after non-adequate response to methotrexate.

PATIENTS AND METHOD

Pharmaceutical and administration costs were calculated in two scenarios: non-optimization and optimization of intravenous (IV) vials. The retrospective analysis of 66 patients from a Spanish 1,000 beds-hospital Rheumatology Clinic Service was used to obtain posology and weight data. The study time horizon was two years. Costs were expressed in 2013 euros.

RESULTS

For an average 69kg-weighted patient the lowest cost corresponded to abatacept subcutaneous (SC ABA) (€21,028.09) in the scenario without IV vials optimization and infliximab (IFX) (€20,779.29) with optimization. Considering patients' weight in the scenario without IV vials optimization infliximab (IFX) was the least expensive drug in patients ranged 45-49kg, IV ABA in 50-59kg and SC ABA in patients over 60kg. With IV vials optimization IFX was the least expensive drug in patients under 69kg and SC ABA over 70kg.

CONCLUSIONS

Assuming comparable effectiveness of biological drugs, patient's weight is a variable to consider, potentials savings could reach €20,000 in two years.

Association between anti-Porphyromonas gingivalis or anti-α-enolase antibody and severity of periodontitis or rheumatoid arthritis (RA) disease activity in RA

Background

Periodontitis (PD) has been reported to be associated with rheumatoid arthritis (RA). Porphyromonas gingivalis (P. gingivalis) is a gram-negative anaerobic bacterium that is recognized as one of the major pathogenic organisms in PD and is the only bacterium known to express peptidylarginine deiminase (PAD). Antibody against human α-enolase (ENO1) is one of the autoantibodies in RA. ENO1 is a highly conserved protein, and could be a candidate molecule for molecular mimicry between bacterial and human proteins. In the present study, we measured serum antibody against P. gingivalis and human ENO1 in patients with RA and investigated their association with the severity of PD or disease activity of RA.

Methods

Two hundred, forty-eight patients with RA and 85 age- and sex-matched healthy controls were evaluated by rheumatologic and periodontal examinations. The serum levels of anti-P. gingivalis and anti-ENO1 antibodies were measured by an enzyme-linked immunosorbent assay (ELISA).

Results

Patients with RA had significantly higher levels of anti-P. gingivalis and anti-ENO1 antibody titers than the controls (p = 0.002 and 0.0001, respectively). Anti-P. gingivalis antibody titers significantly correlated with anti-ENO1 antibody titers in RA patients (r = 0.30, p < 0.0001). There were significant correlations between anti-P. gingivalis antibody titers and the gingival index (GI), probing pocket depth (PPD), bleeding on probing (BOP) and clinical attachment level (CAL) (p = 0.038, 0.004, 0.004 and 0.002, respectively) in RA. Anti-P. gingivalis antibody titers were not correlated with disease activity score 28 (DAS28) or anti-CCP titer. However, anti-ENO1 antibody titers were significantly correlated not only with the periodontal indices, such as PPD, BOP, and CAL (p = 0.013, 0.023 and 0.017, respectively), but also RA clinical characteristics, such as DAS28, anti-CCP titer, and ESR (p = 0.009, 0.015 and 0.001, respectively).

Conclusion

Anti-P. gingivalis and anti-ENO1 antibody titers were correlated with the severity of PD in RA. Anti-ENO1 antibody titers, but not anti-P. gingivalis antibody titers, were further associated with RA disease activity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-015-0647-6) contains supplementary material, which is available to authorized users.

Association of E26 Transformation Specific Sequence 1 Variants with Rheumatoid Arthritis in Chinese Han Population

OBJECTIVE

E26 transformation specific sequence 1 (ETS-1) belongs to the ETS family of transcription factors that regulate the expression of various immune-related genes. Increasing evidence indicates that ETS-1 could contribute to the pathogenesis of autoimmune disease. Recent research has provided evidence that ETS-1 might correlate with rheumatoid arthritis (RA), but it's not clearly defined. In this study, we aimed to identify whether polymorphisms of ETS-1 play a role in Rheumatoid arthritis (RA) susceptibility and development in Chinese Han population.

METHODS

Four single nucleotide polymorphisms (SNPs) within ETS-1 were selected based on HapMap data and previous associated studies. Whole blood and serum samples were obtained from 158 patients with RA and 192 healthy subjects. Genotyping was performed with polymerase chain reaction-high resolution melting (PCR-HRM) assay and the data was analyzed using SPSS17.0.

RESULTS

A significantly positive correlation was observed between the SNP rs73013527 of ETS-1 and RA susceptibility, DAS28 and CRP (P<0.001, P = 0.001, and P = 0.028, respectively). Carriers of the haplotype CCT or TCT for rs4937333, rs11221332 and rs73013527 were associated with decreased risk of RA as compared to controls. No statistical significant difference was observed in the distribution of rs10893872, rs4937333 and rs11221332 genotypes between RA patients and controls.

CONCLUSIONS

Our data further supports that ETS-1 has a relevant role in the pathogenesis and development of RA. Allele T of rs73013527 plays a protective role in occurrence of RA but a risk factor in the high disease activity. Rs10893872, rs11221332 and rs4937333 are not associated with RA susceptibility and clinical features.

Is air pollution a risk factor for rheumatoid arthritis?

Rheumatoid arthritis is a chronic inflammatory debilitating disease triggered by a complex interaction involving genetic and environmental factors. Active smoking and occupational exposures such as silica increase its risk, suggesting that initial inflammation and generation of rheumatoid arthritis-related autoantibodies in the lungs may precede the clinical disease. This hypothesis paved the way to epidemiological studies investigating air pollution as a potential determinant of rheumatoid arthritis. Studies designed for epidemiology of rheumatoid arthritis found a link between traffic, a surrogate of air pollution, and this disease. Furthermore, a small case–control study recently found an association between wood smoke exposure and anticyclic citrullinated protein/peptide antibody in sera of patients presenting wood-smoke-related chronic obstructive pulmonary disease. However, reports addressing impact of specific pollutants on rheumatoid arthritis incidence and severity across populations are somewhat conflicting. In addition to the link reported between other systemic autoimmune rheumatic diseases and particulate matters/gaseous pollutants, experimental observation of exacerbated rheumatoid arthritis incidence and severity in mice models of collagen-induced arthritis after diesel exhaust particles exposure as well as hypovitaminosis D-related autoimmunity can help understand the role of air pollution in rheumatoid arthritis. All these considerations highlight the necessity to extend high quality epidemiological researches investigating different sources of atmospheric pollution across populations and particularly in low-and-middle countries, in order to further explore the biological plausibility of air pollution’s effect in the pathogenesis of rheumatoid arthritis. This should be attempted to better inform policies aiming to reduce the burden of rheumatoid arthritis.

Breastfeeding and Risk of Rheumatoid Arthritis: A Systematic Review and Metaanalysis

OBJECTIVE

Previous studies have examined the association between breastfeeding and rheumatoid arthritis (RA), but their results were inconsistent. The aim of this study was to perform a metaanalysis to clarify the effect of breastfeeding on RA risk.

METHODS

The PubMed, EMBASE, Chinese National Knowledge Infrastructure, and Wanfang databases were searched for relevant studies published up to September 10, 2014. Data were extracted, and multivariable-adjusted OR with 95% CI were pooled in the random-effects model.

RESULTS

A total of 6 studies were included in the metaanalysis (RA cases: 1672, sample size: 143,670). Overall, an inverse association between breastfeeding and RA was observed (OR 0.675, 95% CI 0.493-0.924, p = 0.014). In the subgroup analysis, decreased RA risk was also found in both breastfeeding 1-12 months (OR 0.783, 95% CI 0.641-0.957, p = 0.015) and breastfeeding > 12 months (OR 0.579, 95% CI 0.462-0.726, p < 0.0005). Sensitivity analysis and cumulative analysis further strengthened the validity of the results. No publication bias was found in this metaanalysis.

CONCLUSION

This metaanalysis suggests that breastfeeding is associated with a lower risk of RA, no matter if breastfeeding time is longer or shorter than 12 months.

Energy Metabolism Disorder as a Contributing Factor of Rheumatoid Arthritis: A Comparative Proteomic and Metabolomic Study

Objectives

To explore the pathogenesis of rheumatoid arthritis (RA), the different metabolites were screened in synovial fluid by metabolomics.

Methods

Synovial fluid from 25 RA patients and 10 normal subjects were analyzed by GC/TOF MS analysis so as to give a broad overview of synovial fluid metabolites. The metabolic profiles of RA patients and normal subjects were compared using multivariate statistical analysis. Different proteins were verified by qPCR and western blot. Different metabolites were verified by colorimetric assay kit in 25 inactive RA patients, 25 active RA patients and 20 normal subjects. The influence of hypoxia-inducible factor (HIF)-1α pathway on catabolism was detected by HIF-1α knockdown.

Results

A subset of 58 metabolites was identified, in which the concentrations of 7 metabolites related to energy metabolism were significantly different as shown by importance in the projection (VIP) (VIP≥1) and Student’s t-test (p<0.05). In the 7 metabolites, the concentration of glucose was decreased, and the concentration of lactic acid was increased in the synovial fluid of RA patients than normal subjects verified by colorimetric assay Kit. Receiver operator characteristic (ROC) analysis shows that the concentration of glucose and lactic acid in synovial fluid could be used as dependable biomarkers for the diagnosis of active RA, provided an AUC of 0.906 and 0.922. Sensitivity and specificity, which were determined by cut-off points, reached 84% and 96% in sensitivity and 95% and 85% in specificity, respectively. The verification of different proteins identified in our previous proteomic study shows that the enzymes of anaerobic catabolism were up-regulated (PFKP and LDHA), and the enzymes of aerobic oxidation and fatty acid oxidation were down-regulated (CS, DLST, PGD, ACSL4, ACADVL and HADHA) in RA patients. The expression of HIF-1α and the enzymes of aerobic oxidation and fatty acid oxidation were decreased and the enzymes of anaerobic catabolism were increased in FLS cells after HIF-1α knockdown.

Conclusion

It was found that enhanced anaerobic catabolism and reduced aerobic oxidation regulated by HIF pathway are newly recognized factors contributing to the progression of RA, and low glucose and high lactic acid concentration in synovial fluid may be the potential biomarker of RA.

MicroRNA-26b inhibits cell proliferation and cytokine secretion in human RASF cells via the Wnt/GSK-3β/β-catenin pathway

Background

Rheumatoid arthritis (RA) is a chronic systemic auto- immune disease characterized by joint synovitis. Recent evidence suggests that rheumatoid arthritis synovial fibroblasts (RASFs) promote joint destruction. In this study, we investigated the role of microRNA-26b (miR-26b) in cell proliferation and inflammatory cytokine secretion using patient-derived Rheumatoid arthritis fibroblast-like synoviocyte (RAFLS) to understand pathways influencing rheumatoid arthritis.

Methods

RAFLS were cultured in vitro and transfected with miR-26b mimics (experimental group) and negative sequence (control group). The protein levels of Wnt4, Wnt5ɑ, GSK-3β, CyclinD1, Ser9-GSK-3β and β-catenin were detected by western blot analysis. Tumor Necrosis Factor-ɑ (TNF-ɑ), IL- 1β, and IL-6 levels were quantified by Enzyme-linked Immunosorbent Assay (ELISA). RAFLS proliferation and apoptosis were measured by 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide (MTT) assay and flow cytometry, respectively.

Results

GSK-3β and CyclinD1 expression levels were lower in miR-26b mimic group compared to Mock group and negative control (NC) group. Conversely, GSK-3β and CyclinD1 expression levels were markedly higher in the miR-26b inhibitor group compared to Mock and NC group (P < 0.05). Transfection of miR-26b mimics significantly increased the, levels of Ser9-GSK-3β and β-catenin in comparison to Mock and NC groups, while transfection of miR-26b inhibitors showed the opposite effect. In miR-26b mimic group, TNF-α, IL- 1β and IL-6 levels were lower than the Mock and NC groups, while in miR-26b inhibitor group, these cytokine levels were higher than the Mock and NC groups (P < 0.05). Transfection of miR-26b mimics significantly reduced the cell proliferation of RAFLS, compared to the Mock and NC groups, and miR-26b inhibitors increased the proliferative capacity of RAFLS compared to Mock and NC groups (P < 0.05). The miR-26b mimic group exhibited higher RAFLS apoptosis rate compared to Mock and NC group and miR-26b inhibitor group showed significantly lower RAFLS apoptosis rate compared to Mock and NC groups (P < 0.05).

Conclusions

MiR-26b regulates β-catenin and CyclinD1 levels by inhibiting GSK-3β expression, which in-turn alters the Wnt/GSK-3β/β-catenin pathway to lower RAFLS proliferation and elevate cell apoptosis and the secretion of TNF-α,IL-1β and IL-6 cytokines. Therefore, our results show that miR-26B plays a central role in inhibiting the inflammation associated with rheumatoid arthritis.

Virtual Slides

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Platelet and red blood cell interactions and their role in rheumatoid arthritis

Cytokines, lymphocytes, platelets and several biomolecules have long been implicated in the pathology of rheumatoid arthritis (RA), and the influences of antibody production and tagging, and cytokine, chemokine and enzyme production at specific rheumatoid joints were thought to be exclusive to the advancement of disease parameters. Another role player in RA is red blood cells (RBCs) which, of late, have been found to be involved in RA pathobiology, as there is a positive correlation between RBC counts and joint pathology, as well as with inflammatory biomarkers in the disease. There is also an association between RBC distribution width and the incidence of myocardial infarction amongst RA patients, and there is a change in the lipid distribution within RBC membranes. Of late, certain RBC-associated factors with previously obscure roles and cell-derived particles thought to be inconsequential to the other constituents of plasma were found to be active biomolecular players. Several of these have been discovered to be present in or originating from RBCs. Their influences have been shown to involve in membrane dynamics that cause structural and functional changes in both platelets and RBCs. RBC-derived microparticles are emerging entities found to play direct roles in immunomodulation via interactions with other plasma cells. These correlations highlight the direct influences of RBCs on exacerbating RA pathology. This review will attempt to shed more light on how RBCs, in the true inflammatory milieu of RA, are playing an even greater role than previously assumed.

Do solar cycles influence giant cell arteritis and rheumatoid arthritis incidence?

OBJECTIVE

To examine the influence of solar cycle and geomagnetic effects on the incidence of giant cell arteritis (GCA) and rheumatoid arthritis (RA).

METHODS

We used data from patients with GCA (1950-2004) and RA (1955-2007) obtained from population-based cohorts. Yearly trends in age-adjusted and sex-adjusted incidence were correlated with the F10.7 index (solar radiation at 10.7 cm wavelength, a proxy for the solar extreme ultraviolet radiation) and AL index (a proxy for the westward auroral electrojet and a measure of geomagnetic activity). Fourier analysis was performed on AL, F10.7, and GCA and RA incidence rates.

RESULTS

The correlation of GCA incidence with AL is highly significant: GCA incidence peaks 0-1 year after the AL reaches its minimum (ie, auroral electrojet reaches a maximum). The correlation of RA incidence with AL is also highly significant. RA incidence rates are lowest 5-7 years after AL reaches maximum. AL, GCA and RA incidence power spectra are similar: they have a main peak (periodicity) at about 10 years and a minor peak at 4-5 years. However, the RA incidence power spectrum main peak is broader (8-11 years), which partly explains the lower correlation between RA onset and AL. The auroral electrojets may be linked to the decline of RA incidence more strongly than the onset of RA. The incidences of RA and GCA are aligned in geomagnetic latitude.

CONCLUSIONS

AL and the incidences of GCA and RA all have a major periodicity of about 10 years and a secondary periodicity at 4-5 years. Geomagnetic activity may explain the temporal and spatial variations, including east-west skewness in geographic coordinates, in GCA and RA incidence, although the mechanism is unknown. The link with solar, geospace and atmospheric parameters need to be investigated. These novel findings warrant examination in other populations and with other autoimmune diseases.

Vitamin D Is a Good Marker for Disease Activity of Rheumatoid Arthritis Disease

Aim. This study was conducted to find out the optimal vitamin D cutoff point in predicting activity of RA disease. Materials and Methods. One hundred and two rheumatoid arthritis Saudi patients of both genders were recruited in this study. Vitamin D as 25-hydroxy-vitamin D [25(OH)D] was measured and serum level less than 20 ng/mL defined as deficient patient. Disease activity was measured based on the disease activity score index of a 28-joint count (DAS28) using serum erythrocyte sedimentation rate levels. Receiver operating characteristic (ROC) curves were used to determine the optimal vitamin D cutoff points for identifying disease activity. Results. It has been observed that vitamin D levels were lower (P < 0.05) in patients with high disease activity. A significant inverse correlation between serum 25(OH)D levels and DAS28 (r = −0.277, P = 0.014) was shown. ROC curves results showed that vitamin D less than 12.3 ng/mL predicted high disease activity, and vitamin D more than 17.9 ng/mL predicted low disease activity, with good sensitivity and accuracy results regarding vitamin D. Conclusion. Study results concluded that vitamin D is a good predictor of RA disease activity in Saudi patients.

Current nutritional status of patients with rheumatic diseases in the population of Poland

THE AIM OF THE STUDY

The aim of the study was to evaluate the current state of nutrition of patients with rheumatic diseases in the Polish population.

MATERIAL AND METHODS

An anonymous questionnaire study was carried out among the patients of the Institute of Rheumatology in Warsaw in the fourth quarter of 2012. Five hundred questionnaires were distributed, and 397 questionnaires were collected and accepted for further analysis (response rate = 79%).

RESULTS

Overweight or obesity was present in more than half (53%) of the patients (overweight in 30.5% of respondents, obesity in 22.6%). Among obese subjects, 43% of men and 37% of women in the study think that their diet is correct. Sixty-eight percent of respondents declared that they do not follow any special diet and only 18% declared that they follow a diet with a reduced quantity of monosaccharides (no sweets). A milk-free diet was followed by 7% of respondents, a meat-free diet by 6%, and a fruit-and-vegetable diet by 5%. Dietary supplements were regularly used by 26.7% of respondents, whereas 33.8% did not use them at all. The average assessment of physical aptitude (Health Assessment Questionnaire - HAQ) in the group of respondents was 0.71. No statistically significant differences were found between higher level of disability (e.g. HAQ ≥ 1) and the type of diet followed (p = 0.678) or body mass index (BMI) value (p = 0.864) in relation to persons with the value of HAQ < 1.

CONCLUSIONS

More than half of patients suffering from rheumatic diseases are overweight or obese, which corresponds to the body weight profile of the population of Poland. Most patients diagnosed with rheumatic diseases do not follow any special diet. In spite of the frequent use of dietary supplements, the patients do not consult a doctor or a dietician about it. The type of diet and BMI value do not differ according to the level of disability.

Functional analysis of a complement polymorphism (rs17611) associated with rheumatoid arthritis

Complement is implicated in the pathogenesis of rheumatoid arthritis (RA); elevated levels of complement activation products have been measured in plasma, synovial fluid, and synovial tissues of patients. Complement polymorphisms are associated with RA in genome-wide association studies. Coding-region polymorphisms may directly impact protein activity; indeed, we have shown that complement polymorphisms affecting a single amino acid change cause subtle changes in individual component function that in combination have dramatic effects on complement activity and disease risk. In this study, we explore the functional consequences of a single nucleotide polymorphism (SNP) (rs17611) encoding a V802I polymorphism in C5 and propose a mechanism for its link to RA pathology. Plasma levels of C5, C5a, and terminal complement complex were measured in healthy and RA donors and correlated to rs17611 polymorphic status. Impact of the SNP on C5 functionality was assessed. Plasma C5a levels were significantly increased and C5 levels significantly lower with higher copy number of the RA risk allele for rs17611, suggesting increased turnover of C5 V802. Functional assays using purified C5 variants revealed no significant differences in lytic activity, suggesting that increased C5 V802 turnover was not mediated by complement convertase enzymes. C5 is also cleaved in vivo by proteases; the C5 V802 variant was more sensitive to cleavage with elastase and the “C5a” generated was biologically active. We hypothesize that this SNP in C5 alters the rate at which elastase generates active C5a in rheumatoid joints, hence recruiting neutrophils to the site thus maintaining a state of inflammation in arthritic joints.

Socioeconomic disparities in the health of african americans with rheumatoid arthritis from the southeastern United States

OBJECTIVE

To examine cross-sectional baseline data from the Consortium for the Longitudinal Evaluation of African Americans with Early Rheumatoid Arthritis registry for the association between socioeconomic status (SES) with clinical and self-report health outcomes.

METHODS

We analyzed data on 937 African Americans who provided comprehensive sociodemographic data in addition to self-reported health outcomes. SES measures included educational attainment, homeownership, household income, and occupation. Outcomes included measures of disease activity, joint damage, autoantibody status, and self-reported measures. Multivariable linear, logistic, and zero-inflated Poisson regression models were used to estimate associations of each SES measure with rheumatoid arthritis (RA) outcomes, controlling for sex, age, disease duration, comorbid conditions, body mass index, smoking, methotrexate/leflunomide use, and biologic agent use.

RESULTS

The mean age was 54 years, 86% were women, and the mean RA disease duration was 7.8 years. Approximately 24% had less than a high school degree, 56% had a nonprofessional occupation, 75% had a household income ≤$30,000, and 55% were nonhomeowners. In multivariable regression models, significantly increased associations of disease activity measures and self-reported health outcomes were observed with low household income (≤$30,000/year) and nonhomeownership. Education less than high school was primarily associated with self-reported health outcomes. Among participants with disease duration <2 years, associations of SES were confined to self-reported measures.

CONCLUSION

Our results indicate significant socioeconomic disparities in self-reported physical and mental health, clinical disease activity measures, and autoantibody status among African Americans with RA not explained by differences in demographics, medication use, and health behaviors.

Early diagnosis of rheumatic diseases: an evaluation of the present situation and proposed changes

Musculoskeletal pain is a very common complaint, affecting 30-40% of the European population. It is estimated that approximately 400,000 Poles suffer from inflammatory rheumatic diseases, such as rheumatoid arthritis, ankylosing spondylitis and psoriatic arthritis, and a vast majority of those affected are working-age individuals. Patients with suspected arthritis require prompt diagnosis and treatment, as any delays may result in irreversible joint destruction and disability. Currently in Poland, the lag time between the onset of symptoms and diagnosis is, on average, as much as 35 weeks. In this paper, we review the current state of specialist rheumatology care in Poland and propose a reorganised care model that includes early diagnosis of inflammatory arthritis. The main goal we wish to achieve with our reorganised model is to enhance access to outpatient specialist rheumatology care for patients with suspected arthritis. We believe that our model should make it possible to considerably reduce the lag time between GP referral and the diagnosis and treatment by a rheumatologist to as little as 3 to 4 weeks. This article provides a proposal of changes that would achieve this goal and is a summary of the report published by the Institute of Rheumatology in September 2014.

Mineral Oil Aspiration Related Juvenile Idiopathic Arthritis

We describe the development of rheumatoid factor-positive migratory polyarthritis in a 5-year-old male who had been administered bidaily oral mineral oil as a laxative since birth. Minor respiratory symptoms, radiographic and bronchoscopic findings were consistent with chronic lipoid pneumonia. We speculate that immune sensitization to mineral oil promoted the clinical syndrome of juvenile idiopathic arthritis.

Diet, gut microbes, and genetics in immune function: can we leverage our current knowledge to achieve better outcomes in inflammatory bowel diseases?

Autoimmune disorders, particularly inflammatory bowel diseases (IBD), are increasing at an alarming frequency. While the exact cause remains elusive, studies have examined how the immune system is shaped in the context of genetic susceptibility, gut microbes, and environmental pressures, including dietary intake. Shifts towards a Westernized high fat, high carbohydrate diet result in changes to gut microbiota structure and function that may aid in triggering and perpetuating autoimmunity by promoting the emergence of pathobionts leading to altered immune activation. This review summarizes our current understanding of dietary-induced changes in gut microbiota on autoimmunity in the context of IBD. We provide a framework for leveraging this knowledge to develop new dietary, microbial and immune-based modulation strategies for individualized risk assessment and improving clinical outcomes.

Seronegative rheumatoid arthritis: pathogenetic and therapeutic aspects

Rheumatoid arthritis (RA) has long been recognised as a highly heterogeneous disease of immune dysregulation. Despite an ever-growing appreciation of the role of circulating autoantibodies in the development of 'seropositive' disease, the pathogenesis of seronegative RA remains poorly understood. Accumulating evidence suggests that RA 'serotypes', in fact, reflect distinct disease entities that, despite their clinical overlap, diverge in respect of genetic architecture, cellular pathology and even therapeutic responsiveness. Focussing on seronegative RA, this review considers these concepts and their implications for the management of patients with this challenging, though sometimes overlooked, condition.

Therapeutic effect of daphnetin on the autoimmune arthritis through demethylation of proapoptotic genes in synovial cells

Background

We have previously reported that dephnetin is therapeutically effective in the treatment of rheumatoid arthritis (RA) in collagen-induced arthritis (CIA) rat model. However, the molecular mechanism and the effect of daphnetin on demethylating proapoptotic genes in the synovial cells remains further clarified. This study may provide a deeper insight into the medicinal application of daphnetin as a treatment for RA.

Methods

(1) The proliferation inhibition of CIA rat synovial cells was determined by an MTT (3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenyterazoliumromide) assay; (2) Methylation specific PCR (MSP) was used to measure the methylation of the proapoptotic genes DR3 (death receptor 3), PDCD5 (programmed cell death 5), FasL and p53; (3) Real time-PCR was performed to determine the mRNA expression of DR3, PDCD5, FasL, p53 and DNA methyltransferases (DNMTs) DNMT1, DNMT3a and DNMT3b; (4) Flow cytometry was applied to detect the protein expression of the DR3, PDCD5, FasL and p53; (5) The apoptotic rate of synovial cells was assessed by flow cytometry with Annexin V and propidium iodide (PI); (6) Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the changes of CIA rat synovial cell structure.

Results

(1) In the range of 1.25 μg/mL to 40 μg/mL, daphnetin and 5-aza-dc had a dose-dependent and time-dependent degree of inhibition to the CIA rat synovial cells. (2) Daphnetin and 5-aza-dc had a demethylating role on the proapoptotic genes DR3, PDCD5, FasL and p53 of CIA rat synovial cells. (3) Daphnetin and 5-aza-dc decreased the gene expression of methyltransferases DNMT1, DNMT3a and DNMT3b, and increased expression of proapoptotic genes DR3, PDCD5, FasL and p53, which translated into an increased protein expression of DR3, PDCD5, FasL and p53. (4) Daphnetin and 5-aza-dc changed the structure of CIA rat synovial cells to show apoptotic changes and increased the rate of apoptosis.

Conclusions

Daphnetin can reduce the expression of DNMT1, DNMT3a and DNMT3b, which could result in the proapoptotic genes DR3, PDCD5, FasL and p53 being demethylated. Therefore, daphnetin can increase proapoptotic gene and protein expression resulting in structural apoptotic changes and an increase in early and late CIA rat synovial cell apoptosis.