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

Toxoplasma gondii: bystander or cofactor in rheumatoid arthritis

Parasitic infections may induce variable immunomodulatory effects and control of autoimmune disease. Toxoplasma gondii (T. gondii) is a ubiquitous intracellular protozoan that was recently associated with autoimmunity. This study was undertaken to investigate the seroprevalence and clinical correlation of anti-T. gondii antibodies in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). We evaluated sera from European patients with RA (n = 125) and SLE (n = 164) for the prevalence of anti-T. gondii IgG antibodies (ATXAb), as well as other common infections such as Cytomegalovirus, Epstein-Barr, and Rubella virus. The rates of seropositivity were determined utilizing the LIAISON chemiluminescent immunoassays (DiaSorin, Italy). Our results showed a higher seroprevalence of ATXAb in RA patients, as compared with SLE patients [63 vs. 36 %, respectively (p = 0.01)]. The rates of seropositivity of IgG against other infectious agents were comparable between RA and SLE patients. ATXAb-seropositivity was associated with older age of RA patients, although it did not correlate with RA disease activity and other manifestations of the disease. In conclusion, our data suggest a possible link between exposure to T. gondii infection and RA.

Fine specificity of anti-citrullinated peptide antibodies discloses a heterogeneous antibody population in rheumatoid arthritis

Anti-citrullinated peptide antibodies (ACPA) are highly specific for rheumatoid arthritis (RA). However, the predominant B cell epitopes have not yet been defined. The aim of this study was to examine the reactivity of ACPA against different peptides derived from citrullinated proteins and to investigate whether or not these antibodies constitute a homogeneous population. For this purpose, sera from patients with RA (n = 141), systemic lupus erythematosus (SLE) (n = 60), Sjögren's syndrome (SS) (n = 54) and healthy controls (n = 100) were tested for their reactivity against six citrullinated peptides derived from peptidyl arginine deiminase (PAD), vimentin (vim), alpha-enolase (enol), fibrin, type II collagen (col-II) and filaggrin, respectively. A non-citrullinated control peptide derived from PAD was used as control (ctrlPAD(621-40)). Antibody reactivity against each individual peptide was evaluated by enzyme-linked immunosorbent assay (ELISA). Specificity and cross-reactivity of ACPA were tested by using two prototype sera with homologous and cross-inhibition assays. Specificity of ACPA from two prototype sera was confirmed by purification of anti-peptide antibodies and homologous-inhibition experiments. We found that sera from patients with RA reacted diversely with the six citrullinated peptides. More specifically, PAD(211-30) displayed 29·08% sensitivity, vim(60-75) 29·08%, enol(5-21) 37·59%, fibrin(617-31) 31·21%, col-II(358-75) 29·97% and filaggrin(306-24) 28·37%, while control ctrlPAD(621-40) showed no reactivity. All reactive peptides were found to be highly specific for RA. A notable cross-reaction (>70%) was found mainly between filaggrin and the majority of anti-citrullinated peptide antibodies. We concluded that ACPA in RA constitute a heterogeneous population with limited cross-reactivity and without a predominant epitope.

The effects of a pilot intervention for community-dwelling adults with rheumatoid arthritis in wuhan, china

This study examined the effects of a pilot educational intervention program on knowledge, perceived self-efficacy, and health-related quality of life (HRQoL) of community-dwelling adults with rheumatoid arthritis (RA). A convenience sample of 16 participants with RA completed the program in Wuhan, China. Data were collected in face-to-face interviews using questionnaires at baseline, post-test, and 1 month follow-up. Knowledge scores were significantly increased over time. Significant differences were found in pain self-efficacy, symptoms self-efficacy, bodily pain, social functioning, and role emotional functions. Community health providers should provide educational programs to improve HRQoL for adults with RA.

Bacterial urease and its role in long-lasting human diseases

Urease is a virulence factor found in various pathogenic bacteria. It is essential in colonization of a host organism and in maintenance of bacterial cells in tissues. Due to its enzymatic activity, urease has a toxic effect on human cells. The presence of ureolytic activity is an important marker of a number of bacterial infections. Urease is also an immunogenic protein and is recognized by antibodies present in human sera. The presence of such antibodies is connected with progress of several long-lasting diseases, like rheumatoid arthritis, atherosclerosis or urinary tract infections. In bacterial ureases, motives with a sequence and/or structure similar to human proteins may occur. This phenomenon, known as molecular mimicry, leads to the appearance of autoantibodies, which take part in host molecules destruction. Detection of antibodies-binding motives (epitopes) in bacterial proteins is a complex process. However, organic chemistry tools, such as synthetic peptide libraries, are helpful in both, epitope mapping as well as in serologic investigations.

In this review, we present a synthetic report on a molecular organization of bacterial ureases - genetic as well as structural. We characterize methods used in detecting urease and ureolytic activity, including techniques applied in disease diagnostic processes and in chemical synthesis of urease epitopes. The review also provides a summary of knowledge about a toxic effect of bacterial ureases on human body and about occurrence of anti-urease antibodies in long-lasting diseases.

Lessons to be learned from periodontitis

PURPOSE OF REVIEW

This article reviews the link between periodontitis and rheumatoid arthritis (RA) with regard to similarities in genetic risk factors and immunopathogenesis. Emphasis is paid to the potential role of the periodontal pathogen Porphyromonas gingivalis in the etiopathogenesis of both periodontitis and RA, in particular by post-translational modification of arginine into citrulline.

RECENT FINDINGS

P. gingivalis, a major periodontal pathogen, is presently known as the only bacterium in the oral flora which contains a peptidyl arginine deiminase enzyme (PAD). This enzyme is necessary for citrullination. As a result, citrullinated proteins and P. gingivalis PAD, PAD2 and PAD4 (expressed by infiltrating neutrophils) are found in periodontal tissues. Autoantibodies directed to citrullinated proteins, so-called anticitrullinated protein antibodies (ACPAs), are found to be present in gingival crevicular fluid originating from inflamed gingival tissue. Furthermore, treatment studies have revealed that nonsurgical periodontal treatment, that is removal of sub-gingival calculus and biofilm deposits, is accompanied by a reduction in the severity of RA.

SUMMARY

In this study the similarities in immune response and tissue degradation between RA and periodontitis are reviewed. It is shown that the two diseases share the same environmental and genetic risk factors, apart from the fact that there is a link between both diseases via citrullination of proteins by human PAD and P. gingivalis PAD.

Comparative antigen-induced gene expression profiles unveil novel aspects of susceptibility/resistance to adjuvant arthritis in rats

Lewis (LEW) and Wistar Kyoto (WKY) rats of the same major histocompatibility complex (MHC) haplotype (RT.1(l)) display differential susceptibility to adjuvant-induced arthritis (AIA). LEW are susceptible while WKY are resistant to AIA. To gain insights into the mechanistic basis of these disparate outcomes, we compared the gene expression profiles of the draining lymph node cells (LNC) of these two rat strains early (day 7) following a potentially arthritogenic challenge. LNC were tested both ex vivo and after restimulation with the disease-related antigen, mycobacterial heat-shock protein 65. Biotin-labeled fragment cRNA was generated from RNA of LNC and then hybridized with an oligonucleotide-based DNA microarray chip. The differentially expressed genes (DEG) were compared by limiting the false discovery rate to <5% and fold change ≥2.0, and their association with quantitative trait loci (QTL) was analyzed. This analysis revealed overall a more active immune response in WKY than LEW rats. Important differences were observed in the association of DEG with QTL in LEW vs. WKY rats. Both the number of upregulated DEG associated with rat arthritis-QTL and their level of expression were relatively higher in LEW when compared to WKY rat; however, the number of downregulated DEG-associated with rat arthritis-QTL as well as AIA-QTL were found to be higher in WKY than in LEW rats. In conclusion, distinct gene expression profiles define arthritis-susceptible versus resistant phenotype of MHC-compatible inbred rats. These results would advance our understanding of the pathogenesis of autoimmune arthritis and might also offer potential novel targets for therapeutic purposes.

BAFF and TACI gene expression are increased in patients with untreated very early rheumatoid arthritis

OBJECTIVE

B cells play important roles in rheumatoid arthritis (RA). Given the beneficial effect of B cell depletion therapy in RA as well as the observed alterations in B cell subpopulations in this disease, we evaluated whether changes in the expression of genes related to B cell survival and activation were already present in patients with untreated very early RA (VERA; < 6 weeks of disease duration).

METHODS

The expression of a group of B cell-related activation and survival genes was quantified in peripheral blood mononuclear cells from patients with VERA by real-time PCR and compared with untreated early RA (< 1 year), established treated RA, and other untreated early arthritis conditions. Serum B cell-activating factor belonging to the tumor necrosis factor family (BAFF) was quantified by ELISA.

RESULTS

BAFF gene expression and serum levels were highest in patients with VERA. The expression of BAFF receptor (BAFF-R) increased with disease progression, while transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) was elevated since the first weeks of RA onset. Paired box 5 gene expression was also increased at all RA stages. Chemokine (C-X-C motif) receptor 5 was elevated only in established RA. No differences were observed in B cell maturation antigen, activation-induced cytidine deaminase, B lymphocyte-induced maturation protein, and B cell lymphoma 2 expression.

CONCLUSION

Disturbances in the expression of B cell-related activation and survival genes, particularly BAFF and TACI, occur from the onset of RA and precede changes in BAFF-R. These alterations can lead to the development of autoreactive B cells from the first weeks of RA onset.

The critical importance of epigenetics in autoimmunity

Autoimmune diseases are characterized by aberrant immune responses against healthy cells and tissues, in which a given individual's genetic susceptibilities play a central role; however, the exact mechanisms underlying the development of these conditions remain for the most part unknown. In recent years, accumulating evidence has demonstrated that, in addition to genetics, other complementary mechanisms are involved in the pathogenesis of autoimmunity, in particular, epigenetics. Epigenetics is defined as stable and heritable patterns of gene expression that do not entail any alterations to the original DNA sequence. Epigenetic mechanisms primarily consist of DNA methylation, histone modifications and small non-coding RNA transcripts. Epigenetic marks can be affected by age and other environmental triggers, providing a plausible link between environmental factors and the onset and development of various human diseases. Because of their primary function in regulating timely gene expression, epigenetic mechanisms offer potential advantages in terms of interpreting the molecular basis of complicated diseases and providing new promising therapeutic avenues for their treatment. The present review focuses on recent progress made in elucidating the relationship between epigenetics and the pathogenesis of autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, systemic sclerosis, primary Sjögren's syndrome, primary biliary cirrhosis, psoriasis and type 1 diabetes.

Clinical pharmacology of tocilizumab for the treatment of patients with rheumatoid arthritis

Tocilizumab is a humanized anti-IL-6 receptor (IL-6R) monoclonal antibody for the treatment of rheumatoid arthritis (RA). A dose of 8 mg/kg produces adequate blockade of IL-6 receptors throughout a dosing interval, as confirmed by sustained high levels of tocilizumab-bound soluble IL6-R complex and normalization of C-reactive protein levels. Studies have confirmed 8 mg/kg every 4 weeks as the optimal dose and 4 mg/kg as the starting dose for the treatment of RA, with favorable efficacy and acceptable safety profiles. After 8 mg/kg, steady-state peak and trough concentrations were 183 ± 86 and 9.7 ± 11 µg/ml, respectively. Tocilizumab serum exposures increased more than proportionally to the dose increase from 2-10 mg/kg. Total clearance is concentration dependent, with non-linear receptor-mediated clearance dominant at low concentrations (<25 µg/ml). Tocilizumab exposures are not affected by common concomitant medications in RA patients, but decreased IL-6 activity resulted in increased CYP3A4 activity and hence decreased exposures of CYP3A4 substrates.

Association between a history of periodontitis and the risk of rheumatoid arthritis: a nationwide, population-based, case-control study

OBJECTIVE

To investigate the association between the risk of rheumatoid arthritis (RA) and a history of periodontitis.

METHODS

This nationwide, population-based, case-control study used administrative data to identify 13 779 newly diagnosed patients with RA (age ≥16 years) as the study group and 137 790 non-patients with RA matched for age, sex, and initial diagnosis date (index date) as controls. Using conditional logistic regression analysis after adjustment for potential confounders, including geographical region and a history of diabetes and Sjögren's syndrome, ORs with 95% CI were calculated to quantify the association between RA and periodontitis. To evaluate the effects of periodontitis severity and the lag time since the last periodontitis visit on RA development, ORs were calculated for subgroups of patients with periodontitis according to the number of visits, cumulative cost, periodontal surgery and time interval between the last periodontitis-related visit and the index date.

RESULTS

An association was found between a history of periodontitis and newly diagnosed RA (OR=1.16; 95% CI 1.13 to 1.21). The strength of this association remained statistically significant after adjustment for potential confounders (OR=1.16; 95% CI 1.12 to 1.20), and after variation of periodontitis definitions. The association was dose- and time-dependent and was strongest when the interval between the last periodontitis-related visit and the index date was <3 months (OR=1.64; 95% CI 1.49 to 1.79).

CONCLUSIONS

This study demonstrates an association between periodontitis and incident RA. This association is weak and limited to lack of individual smoking status.

Reliability of the TekScan MatScan® system for the measurement of postural stability in older people with rheumatoid arthritis

BACKGROUND

Postural stability can be measured in clinical and research settings using portable plantar pressure systems. People with rheumatoid arthritis (RA) have decreased postural stability compared to non-RA populations and impaired postural stability is associated with falls in people with RA. The purpose of this study was therefore to investigate the reliability of the TekScan MatScan® system in assessing postural stability in people with RA.

METHODS

Twenty three participants with RA, mean (SD) age 69.74 (10.1) years, were assessed in barefoot double-limb quiet standing, with eyes open and eyes closed, for antero-posterior and medio-lateral postural sway values. Three repetitions, at a sampling frequency of 40 Hz, were recorded for each test condition to obtain a mean value. Measurements were repeated one hour later. Intraclass correlation coefficients (ICC) with 95% confidence intervals (CI) were calculated to determine between-session reliability. Measurement error was assessed through the calculation of the standard error of the measurement (SEM) and the smallest real difference (SRD).

RESULTS

The system displayed good to excellent reliability for antero-posterior and medio-lateral sway, with eyes open and closed, as indicated by ICC values ranging from 0.84 to 0.92. Measurement error, as evidenced by the SEM, ranged from 1.27 to 2.35 mm. The degree of change required to exceed the expected trial to trial variability was relatively high, compared to mean values, with SRD ranging from 3.08 to 5.71 mm.

CONCLUSIONS

The portability and ease of use of the TekScan MatScan® makes it a useful tool for the measurement of postural stability in clinical and research settings. The TekScan MatScan® system can reliably measure double-limb quiet standing in older people, aged 60 to 80 years, with RA.

Mechanisms of environmental influence on human autoimmunity: a National Institute of Environmental Health Sciences expert panel workshop

The mechanisms leading to autoimmune diseases remain largely unknown despite numerous lines of experimental inquiry and epidemiological evidence. The growing number of genome-wide association studies and the largely incomplete concordance for autoimmune diseases in monozygotic twins support the role of the environment (including infectious agents and chemicals) in the breakdown of tolerance leading to autoimmunity via numerous mechanisms. The present article reviews the major theories on the mechanisms of the environmental influence on autoimmunity by addressing the different degrees of confidence that characterize our knowledge. The theories discussed herein include (i) the role of innate immunity mediated by toll-like receptors in triggering the autoimmune adaptive response characterizing the observed pathology; (ii) changes in spleen marginal zone B cells in autoantibody production with particular focus on the B10 subpopulation; (iii) Th17 cell differentiation and T regulatory cells in the aryl hydrocarbon receptor model; (iv) self antigen changes induced by chemical and infectious agents which could break tolerance by post-translational modifications and molecular mimicry; and finally (v) epigenetic changes, particularly DNA methylation, that are induced by environmental stimuli and may contribute to autoimmunity initiation. We are convinced that these working hypotheses, in most cases supported by solid evidence, should be viewed in parallel with animal models and epidemiological observations to provide a comprehensive picture of the environmental causes of autoimmune diseases.

The presence of anti-LPS antibodies and human serum activity against Proteus mirabilis S/R forms in correlation with TLR4 (Thr399Ile) gene polymorphism in rheumatoid arthritis

OBJECTIVES

Proteus mirabilis strains are human pathogens responsible for urinary tract infections, which may also be involved in rheumatoid arthritis (RA).

DESIGN AND METHODS

We determined whether the binding site of anti-LPS antibodies on the O-polysaccharide part of P. mirabilis LPS correlates with the level of TLR4 (Thr399Ile) gene polymorphism in the sera of RA patients. We investigated the deposition of C3d and C5b complement components on the P. mirabilis LPS. The ELISA method used in this study was optimized with LAL test and laser interferometry.

RESULTS

Depending on LPS P. mirabilis used in these studies, the amount of antibodies in RA patients sera varied. We did not observe a correlation between anti-LPS antibodies binding and the level of TLR4 (Thr399Ile) gene polymorphism. We found that the lower complement components deposition by O49 in contrast to O9 LPS correlates with its reduced sensitivities to human complement-mediated killing.

CONCLUSION

The immunological response against P. mirabilis LPS might play a role in rheumatoid arthritis.

Scorpio and Scolopendra attenuate inflammation and articular damage in rats with collagen-induced arthritis

ETHNOPHARMACOLOGICAL RELEVANCE

Scorpio and Scolopendra (SS) are two traditional Chinese medicines, which are generally used to treat rheumatoid arthritis (RA) in China. However, the mechanism is so far unclear. The purpose of this study was to explore the effects and mechanisms of SS in attenuating inflammation and joint injury in collagen-induced arthritis in rats.

MATERIALS AND METHODS

RA was induced in Wistar rats by injection of collagen, meanwhile, the rats were administrated daily either SS (0.4 g/kg, 0.2 g/kg, and 0.1 g/kg) or vehicle (physiological saline) for 42 days. The therapeutic effect of SS on RA was evaluated by pathological methods. T lymphocyte subsets and anti-collagen type II (CII) antibody were tested in peripheral blood. Tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), interleukin-4 (IL-4) and interleukin-10 (IL-10) were assessed in tissue homogenate of fresh joints.

RESULTS

The inflammation and articular damage in SS powder-treated rats were attenuated significantly. In addition, SS powder was revealed to modulate the equilibrium of T lymphocyte subsets, down-regulate TNF-α and IL-1β, up-regulate IL-4 and IL-10, and significantly suppress the level of anti-CII antibody.

CONCLUSIONS

Scorpio and Scolopendra, when used as a combination, reveal desirable effect for treatment of rheumatoid arthritis, and this beneficial effect may be accomplished through normalization of T lymphocyte subsets and the balance of Th1/Th2 cytokines.

Prevalence of anti-Toxoplasma antibodies in patients with autoimmune diseases

The identification of etiological factors in the induction of autoimmunity has remained elusive despite an enormous effort at dissection of the molecular structure of the target antigens and effector mechanisms. One characteristic feature of autoantigens is their repetitive structure as well as their conservation and evolution. Toxoplasma (T.) gondii is a primitive protozoan. We hypothesized that patients with autoimmune disease would have broad reactions against Toxoplasma antigens based on autoantigen conservation. To address this issue, we assessed serologic evidence of reactivity to Toxoplasma gondii along with a large profile of autoantibodies in patients with various autoimmune diseases (AID). We included sera of 1514 patients with 11 different AID collected from referral centers in Europe and Latin America as well as from 437 geographically matched controls, for the prevalence of anti Toxoplasma antibodies (ATxA) IgG and IgM and serum autoantibodies utilizing the BioPlex 2200 system (Bio- Rad Laboratories, USA). Serum ATxA IgG were positive in 42% of patients with AID versus 29% of controls (p < 0.0001). Among Europeans, ATxA IgG were associated with anti-phospholipid syndrome (APS; p < 0.0001), cryoglobulinemia (p < 0.0001), ANCA-associated vasculitides (p < 0.01), autoimmune thyroid diseases (p < 0.0001), systemic sclerosis (SSc; p < 0.0001) and rheumatoid arthritis (RA; p < 0.0001). Of note, Latin American RA sera exhibited similar frequency of ATxA IgG as controls. ATxA IgM were more prevalent in European patients with APS (p < 0.01), SSc (p < 0.05) and inflammatory bowel disease (IBD, p < 0.05) than in controls. Further, in AID patients the presence of ATxA correlated with autoantibodies characteristic of APS (anti- cardiolipin, B2GPI, complex of cardiolipin- B2GPI, prothrombin, phosphatydilethanolamine), and of SSc (anti-centromere, Scl-70). Our findings suggest that T. gondii may contribute to the pathogenesis of AID. This interaction may depend on or explain observed geoepidemiological variance in AID.

Twin studies in autoimmune disease: genetics, gender and environment

Twin studies are powerful tools to discriminate whether a complex disease is due to genetic or environmental factors. High concordance rates among monozygotic (MZ) twins support genetic factors being predominantly involved, whilst low rates are suggestive of environmental factors. Twin studies have often been utilised in the study of systemic and organ specific autoimmune diseases. As an example, type I diabetes mellitus has been investigated to establish that that disease is largely affected by genetic factors, compared to rheumatoid arthritis or scleroderma, which have a weaker genetic association. However, large twin studies are scarce or virtually non-existent in other autoimmune diseases which have been limited to few sets of twins and individual case reports. In addition to the study of the genetic and environmental contributions to disease, it is likely that twin studies will also provide data in regards to the clinical course of disease, as well as risk for development in related individuals. More importantly, genome-wide association studies have thus far reported genomic variants that only account for a minority of autoimmunity cases, and cannot explain disease discordance in MZ twins. Future research is therefore encouraged not only in the analysis of twins with autoimmune disease, but also in regards to epigenetic factors or rare variants that may be discovered with next-generation sequencing. This review will examine the literature surrounding twin studies in autoimmune disease including discussions of genetics and gender.

Periodontal disease, tooth loss and incident rheumatoid arthritis: results from the First National Health and Nutrition Examination Survey and its epidemiological follow-up study

AIMS

Infection may be a rheumatoid arthritis (RA) risk factor. We examined whether signs of periodontal infection were associated with RA development in the First National Health and Nutrition Examination Survey and its epidemiological follow-up study.

MATERIAL AND METHODS

In 1971-1974, 9702 men and women aged 25-74 were enrolled and surveyed longitudinally (1982, 1986, 1987, 1992). Periodontal infection was defined by baseline tooth loss or clinical evidence of periodontal disease. Baseline (n = 138) and incident (n = 433) RA cases were defined via self-report physician diagnosis, joint pain/swelling, ICD-9 codes (714.0-714.9), death certificates and/or RA hospitalization.

RESULTS

Adjusted odds ratios (ORs) (95% CI) for prevalent RA in gingivitis and periodontitis (versus healthy) were 1.09 (0.57, 2.10) and 1.85 (0.95, 3.63); incident RA ORs were 1.32 (0.85, 2.06) and 1.00 (0.68, 1.48). The ORs for prevalent RA among participants missing 5-8, 9-14, 15-31 or 32 teeth (versus 0-4 teeth) were 1.74 (1.03, 2.95), 1.82 (0.81, 4.10), 1.45 (0.62, 3.41) and 1.30 (0.48, 3.53); ORs for incident RA were 1.12 (0.77, 1.64), 1.67 (1.12, 2.48), 1.40 (0.85, 2.33) and 1.22 (0.75, 2.00). Dose-responsiveness was enhanced among never smokers. The rate of death or loss-to-follow-up after 1982 was two- to fourfold higher among participants with periodontitis or missing ≥9 teeth (versus healthy participants).

CONCLUSIONS

Although participants with periodontal disease or ≥5 missing teeth experienced higher odds of prevalent/incident RA, most ORs were non-statistically significant and lacked dose-responsiveness. Differential RA ascertainment bias complicated the interpretation of these data.

Therapeutic effect of Yunnan Baiyao on rheumatoid arthritis was partially due to regulating arachidonic acid metabolism in osteoblasts

In order to explore the potential therapeutic effect of Yunnan Baiyao (YNB) on rheumatoid arthritis (RA), rat models were constructed and orally administrated with YNB or methotrexate (MTX) in parallel. Clinical physical, histological and biochemical parameters showed trivial therapeutic difference between YNB and MTX applications. Urine and serum metabonomics results indicated that many endogenous metabolites differentially changed among the rats receiving diverse therapeutic interventions. Among them, the fluctuation of arachidonic acid (AA) was thought to make sense. Thus, its relevant metabolites were subjected to quantitation by using osteoblasts treated by YNB in vitro. It was found that YNB extract of 20 μg/mL could greatly activate the synthesis of intracellular prostaglandin E₂ and thromboxane B₂ in osteoblasts. Excretion of prostaglandin D₂ could be suppressed but not the thromboxane B₂. This study proved the efficacy of YNB on curing RA and its potential mechanism through modulating AA metabolism in osteoblasts to some extent.

Validating the 28-tender joint count using item response theory

OBJECTIVE

To examine the construct validity of the 28-tender joint count (TJC-28) using item response theory (IRT)-based methods.

METHODS

A total of 457 patients with early stage rheumatoid arthritis (RA) were included. Internal construct validity of the TJC-28 was evaluated by determining whether the TJC-28 fit a 2-measure logistic IRT model. As well, we tested whether the discrimination and difficulty parameters of the joints properly reflected the known left-right symmetry of joint involvement. External validity was evaluated by correlations with other established measures of disease activity, including pain, disability, general health, erythrocyte sedimentation rate (ESR), and the 28-swollen joint count.

RESULTS

The TJC-28 showed a good fit with the 2-parameter logistic model, with no relevant differential item functioning across sex, age, and time and with excellent reliability. The 28 joints covered a reasonable range of disease activity, even though they were mainly targeted at patients with moderate or high disease activity levels. The joint parameters reflected the left-right symmetry of joint involvement for all pairs of joints except one. All disease activity measures, except ESR, were significantly correlated with the TJC-28. Most correlations were of the expected magnitude.

CONCLUSION

The TJC-28 showed good internal and acceptable external construct validity for patients with early-stage RA. The IRT analyses did point to some potential limitations of the instrument, a major problem being its limited measurement range. Future research should examine whether instrument modifications might lead to a more robust assessment of disease activity in patients with RA.

Aberrant splicing of the hRasGRP4 transcript and decreased levels of this signaling protein in the peripheral blood mononuclear cells in a subset of patients with rheumatoid arthritis

Introduction

An unidentified population of peripheral blood mononuclear cells (PBMCs) express Ras guanine nucleotide releasing protein 4 (RasGRP4). The aim of our study was to identify the cells in human blood that express hRasGRP4, and then to determine if hRasGRP4 was altered in any patient with rheumatoid arthritis (RA).

Methods

Monocytes and T cells were purified from PBMCs of normal individuals, and were evaluated for their expression of RasGRP4 mRNA/protein. The levels of RasGRP4 transcripts were evaluated in the PBMCs from healthy volunteers and RA patients by real-time quantitative PCR. The nucleotide sequences of RasGRP4 cDNAs were also determined. RasGRP4 protein expression in PBMCs/monocytes was evaluated. Recombinant hRasGRP4 was expressed in mammalian cells.

Results

Circulating CD14⁺ cells in normal individuals were found to express hRasGRP4. The levels of the hRasGRP4 transcript were significantly higher in the PBMCs of our RA patients relative to healthy individuals. Sequence analysis of hRasGRP4 cDNAs from these PBMCs revealed 10 novel splice variants. Aberrantly spliced hRasGRP4 transcripts were more frequent in the RA patients than in normal individuals. The presence of one of these abnormal splice variants was linked to RA. The levels of hRasGRP4 protein in PBMCs tended to be lower. As expected, the defective transcripts led to altered and/or nonfunctional protein in terms of P44/42 mitogen-activated protein (MAP) kinase activation.

Conclusions

The identification of defective isoforms of hRasGRP4 transcripts in the PBMCs of RA patients raises the possibility that dysregulated expression of hRasGRP4 in developing monocytes plays a pathogenic role in a subset of RA patients.

Extra-articular manifestations of rheumatoid arthritis: An update

Rheumatoid arthritis (RA) is an immune-mediated disease involving chronic low-grade inflammation that may progressively lead to joint destruction, deformity, disability and even death. Despite its predominant osteoarticular and periarticular manifestations, RA is a systemic disease often associated with cutaneous and organ-specific extra-articular manifestations (EAM). Despite the fact that EAM have been studied in numerous RA cohorts, there is no uniformity in their definition or classification. This paper reviews current knowledge about EAM in terms of frequency, clinical aspects and current therapeutic approaches. In an initial attempt at a classification, we separated EAM from RA co-morbidities and from general, constitutional manifestations of systemic inflammation. Moreover, we distinguished EAM into cutaneous and visceral forms, both severe and not severe. In aggregated data from 12 large RA cohorts, patients with EAM, especially the severe forms, were found to have greater co-morbidity and mortality than patients without EAM. Understanding the complexity of EAM and their management remains a challenge for clinicians, especially since the effectiveness of drug therapy on EAM has not been systematically evaluated in randomized clinical trials.

The microbiome and rheumatoid arthritis

Humans are not (and have never been) alone. From the moment we are born, millions of micro-organisms populate our bodies and coexist with us rather peacefully for the rest of our lives. This microbiome represents the totality of micro-organisms (and their genomes) that we necessarily acquire from the environment. Micro-organisms living in or on us have evolved to extract the energy they require to survive, and in exchange they support the physiological, metabolic and immune capacities that have contributed to our evolutionary success. Although currently categorized as an autoimmune disorder and regarded as a complex genetic disease, the ultimate cause of rheumatoid arthritis (RA) remains elusive. It seems that interplay between predisposing genetic factors and environmental triggers is required for disease manifestation. New insights from DNA sequence-based analyses of gut microbial communities and a renewed interest in mucosal immunology suggest that the microbiome represents an important environmental factor that can influence autoimmune disease manifestation. This Review summarizes the historical clues that suggest a possible role for the microbiota in the pathogenesis of RA, and will focus on new technologies that might provide scientific evidence to support this hypothesis.

Drug-induced lupus erythematosus: incidence, management and prevention

The generation of autoantibodies and autoimmune diseases such as systemic lupus erythematosus has been associated with the use of certain drugs in humans. Early reports suggested that procainamide and hydralazine were associated with the highest risk of developing lupus, quinidine with a moderate risk and all other drugs were considered low or very low risk. More recently, drug-induced lupus has been associated with the use of the newer biological modulators such as tumour necrosis factor (TNF)-α inhibitors and interferons. The clinical features and laboratory findings of TNFα inhibitor-induced lupus are different from that of traditional drug-induced lupus or idiopathic lupus, and standardized criteria for the diagnosis of drug-induced lupus have not been established. The mechanism(s) responsible for the development of drug-induced lupus may vary depending on the drug or even on the patient. Besides lupus, other autoimmune diseases have been associated with drugs or toxins. Diagnosis of drug-induced lupus requires identification of a temporal relationship between drug administration and symptom development, and in traditional drug-induced lupus there must be no pre-existing lupus. Resolution of symptoms generally occurs after cessation of the drug. In this review, we will discuss those drugs that are more commonly associated with drug-induced lupus, with an emphasis on the new biologicals and the difficulty of making the diagnosis of drug-induced lupus against a backdrop of the autoimmune diseases that these drugs are used to treat. Stimulation of the immune system by these drugs to cause autoimmunity may in fact be associated with an increased effectiveness in treating the pathology for which they are prescribed, leading to the dilemma of deciding which is worse, the original disease or the adverse effect of the drug. Optimistically, one must hope that ongoing research in drug development and in pharmacogenetics will help to treat patients with the maximum effectiveness while minimizing side effects. Vigilance and early diagnosis are critical. The purpose of this review is to summarize the most recent developments in our understanding of the incidence, pathogenesis, diagnosis and treatment of drug-induced lupus.

Toward understanding the role of leptin and leptin receptor antagonism in preclinical models of rheumatoid arthritis

A potential link between obesity, circulating leptin levels and autoimmune disease symptoms suggests that targeting the leptin receptor (ObR) might be a viable novel strategy to combat rheumatoid arthritis (RA). However, studies in animal models and evaluation of clinical cases did not provide clear view on leptin's involvement in RA. To validate ObR as RA target, we used our peptide-based ObR agonists and antagonist in different in vitro and in vivo models of the disease. In human peripheral blood mononuclear cells, leptin and its agonist fragment, desI(2)-E1/Aca, moderately induced constitutive activation of a major proinflammatory transcription factor, NF-κB, while the ObR antagonist peptide Allo-aca inhibited the process. Leptin administration itself did not induce arthritis in rats, but worsened the clinical condition of mice given K/BxN serum transfer arthritis. Simultaneous administration of Allo-aca reduced leptin-dependent increase in disease severity by more than 50%, but the antagonist was ineffective when injected with a 3-day delay. In rats inflicted with mild adjuvant-induced arthritis, both leptin and Allo-aca reduced the extent of joint swelling and the number of arthritic joints. In a more aggressive disease stage, Allo-aca decreased the number of arthritic joints in a dose-dependent manner but did not affect other arthritis markers. In summary, leptin exerts diverse effects on RA depending on the experimental model. This might reflect the heterogeneous character of RA, which is differently impacted by leptin and is unmasked by ObR antagonism. Nevertheless, the results suggest that ObR antagonists might become useful therapeutics in leptin-sensitive early stages of RA.

Effect of a cocoa flavonoid-enriched diet on experimental autoimmune arthritis

Previously we established that a cocoa-enriched diet in young rats reduces specific antibody production and the T helper (Th) lymphocyte proportion in lymphoid tissues. The aim of the present study was to ascertain the modulatory ability of a cocoa flavonoid-enriched diet on collagen-induced arthritis (CIA), which is mediated by anti-collagen autoantibody response and Th lymphocyte activation. Female Louvain (LOU) rats were fed with a cocoa-enriched diet, beginning 2 weeks before CIA induction. Hind-paw swelling and serum cytokine and anti-collagen antibody concentrations were determined. Anti-collagen antibody-secreting cell counts and lymphocyte subset proportions were established in inguinal lymph nodes (ILN). Reactive oxygen species (ROS), nitric oxide (NO) and TNFα produced by peritoneal macrophages were determined. Although arthritic cocoa-fed rats showed a similar hind-paw swelling time course as the arthritic animals fed a standard diet, the cocoa intake was able to decrease specific IgG2a, IgG2b and IgG2c titres. Moreover, cocoa intake in CIA rats reduced ROS production, TNFα and NO release from peritoneal macrophages, and decreased the Th:cytotoxic T cell ratio in ILN. In conclusion, a cocoa flavonoid-enriched diet in LOU rats with CIA produced no effect on hind-paw swelling but was able to modulate the specific antibody response and also the Th lymphocyte proportion, as well as the synthesis of pro-inflammatory mediators from peritoneal macrophages. Therefore, a cocoa-enriched diet could be a good adjuvant therapy in disorders with oxidative stress or autoimmune pathogenesis.

Autoimmunity in 2010

There is now growing evidence that autoimmunity is the common trait connecting multiple clinical phenotypes albeit differences in tissue specificity, pathogenetic mechanisms, and therapeutic approaches cannot be overlooked. Over the past years we witnessed a constant growth of the number of publications related to autoimmune diseases in peer-reviewed journals of the immunology area. Original data referred to factors from common injury pathways (i.e. T helper 17 cells, serum autoantibodies, or vitamin D) and specific diseases such as multiple sclerosis, systemic lupus erythematosus, and rheumatoid arthritis. As an example, the issue of a latitudinal gradient in the prevalence and incidence rates has been proposed for all autoimmune diseases and was recently coined as geoepidemiology to suggest new environmental triggers for tolerance breakdown. The present article is aimed at reviewing the articles that were published over the past year in the major autoimmunity and immunology journals.

Environmental pathways to autoimmune diseases: the cases of primary biliary cirrhosis and multiple sclerosis

The pathways leading to autoimmunity remain enigmatic despite numerous lines of experimental inquiry and epidemiological evidence. The mechanisms leading to the initiation and perpetuation of specific diseases such as primary biliary cirrhosis (PBC) or multiple sclerosis (MS) remain largely enigmatic, although it is established that a combination of genetic predisposition and environmental stimulation is required. The growing number of genome-wide association studies and the largely incomplete concordance for autoimmune diseases in monozygotic twins concur to support the role of the environment (including infectious agents and chemicals) in the breakdown of tolerance leading to autoimmunity through different mechanisms. In the present article we illustrate the current hypotheses related to an environmental impact on the onset of PBC and MS as two representative conditions investigated with complementary approaches. Indeed, while a role of post-translational antigen modifications has been proposed for MS, this field remain unexplored in PBC where, conversely, most evidence is gathered from geoepidemiology and experimental data on xenobiotics or infectious agents.

Rheumatoid arthritis and periodontitis; a possible link via citrullination

Rheumatoid Arthritis (RA) and chronic and aggressive periodontitis are chronic inflammatory disorders characterized by deregulation of the host inflammatory response. Increased secretion of pro-inflammatory mediators results in soft and hard tissue destruction of the synovium and periodontium respectively. Both diseases share risk factors and have pathological pathways in common, resulting in loss of function and disability as a final clinical outcome. This article discusses possible interactions, particularly related to the periodontal pathogen Porphyromonas gingivalis, which could explain the observed association between these two prevalent diseases.

The pathogenesis of oligoarticular/polyarticular vs systemic juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) has had a long and difficult problem with classification. It is clearly a heterogeneous and multi-factorial autoimmune disease but all too often the distinctions among subtypes were unclear. In fact, there is now increasing evidence of a distinct pathogenesis of oligo/polyarticular JIA compared to systemic JIA. Oligo/polyarticular JIA is an antigen-driven lymphocyte-mediated autoimmune disease with abnormality in the adaptive immune system. Cartilage-derived auto-antigens activate autoreactive T cells including Th1 and Th17 cells with production of pro-inflammatory cytokines IFN-γ and IL-17. On the other hand, the inhibition of regulatory T (Treg) cells including natural Foxp3(+) Treg and self-heat shock protein-induced Treg cells with decreased anti-inflammatory cytokine IL-10 results in the loss of immune tolerance. Imbalance between autoreactive Th1/Th17 and Treg cells leads to the failure of T cell tolerance to self-antigens, which contributes to the synovial inflammation of oligo/polyarticular JIA. By contrast, systemic JIA is an autoinflammatory disease with abnormality in the innate immune system. A loss of control of the alternative secretory pathway leading to aberrant activation of phagocytes including monocytes, macrophages and neutrophils seems to be involved in the release of pro-inflammatory cytokines IL-1, IL-6, IL-18 and pro-inflammatory S100-proteins, which contribute to the multisystem inflammation of systemic JIA. Markedly distinct pathogenesis of oligo/polyarticular JIA and systemic JIA implies that they might need different treatment strategies.

The epigenetics of autoimmunity

The etiology of autoimmune diseases remains largely unknown. Concordance rates in monozygotic twins are lower than 50% while genome-wide association studies propose numerous significant associations representing only a minority of patients. These lines of evidence strongly support other complementary mechanisms involved in the regulation of genes expression ultimately causing overt autoimmunity. Alterations in the post-translational modification of histones and DNA methylation are the two major epigenetic mechanisms that may potentially cause a breakdown of immune tolerance and the perpetuation of autoimmune diseases. In recent years, several studies both in clinical settings and experimental models proposed that the epigenome may hold the key to a better understanding of autoimmunity initiation and perpetuation. More specifically, data support the impact of epigenetic changes in systemic lupus erythematosus, rheumatoid arthritis, multiple sclerosis and other autoimmune diseases, in some cases based on mechanistical observations. We herein discuss what we currently know and what we expect will come in the next future. Ultimately, epigenetic treatments already being used in oncology may soon prove beneficial also in autoimmune diseases.

The autoimmunity of primary biliary cirrhosis and the clonal selection theory

Primary biliary cirrhosis (PBC) is a chronic cholestatic liver disease in which an immune-mediated injury targets the small intrahepatic bile ducts. PBC is further characterized by highly specific serum antimitochondrial autoantibodies (AMA) and autoreactive T cells, a striking female predominance, a strong genetic susceptibility, and a plethora of candidate environmental factors to trigger the disease onset. For these reasons PBC appears ideal to represent the developments of the clonal selection theory over the past decades. First, a sufficiently potent autoimmunogenic stimulus in PBC would require the coexistence of numerous pre-existing conditions (mostly genetic, as recently illustrated by genome-wide association studies and animal models) to perpetuate the destruction of the biliary epithelium by the immune system via the persistence of forbidden clones. Second, the proposed modifications of mitochondrial autoantigens caused by infectious agents and/or xenobiotics well illustrate the possibility that peculiar changes in the antigen structure and flexibility may contribute to tolerance breakdown. Third, the unique apoptotic features demonstrated for cholangiocytes are the ideal setting for the development of mitochondrial autoantigen presentation to the immune system through macrophages and AMA thus turning the non traditional mitochondrial antigen into a traditional one. This article will review the current knowledge on PBC etiology and pathogenesis in light of the clonal selection theory developments.