Osteoclast differentiation factor induces synovial macrophage–osteoclast differentiation in rheumatoid arthritis

The aim of this study was to clarify the role of osteoclast differentiation factor (ODF) and osteoprotegerin (OPG) in synovial macrophage–osteoclast differentiation. Synovial macrophages were cultured in the presence of macrophage-colony-stimulating factor (M-CSF) and/or ODF. OPG was added to cocultures of synovial macrophages and UMR106. The cultures on glass coverslips were stained with osteoclast-associated markers, tartrate-resistant acid phosphatase (TRAP), and vitronectin receptor (VNR), as well as macrophage-associated markers CD11b and CD14. Functional evidence of osteoclast formation was determined by a resorption pit assay. To investigate whether rheumatoid arthritis (RA) synovial cells expressed messenger RNA (mRNA) for ODF, OPG, and the receptor activator of NF-κB (RANK), we performed a polymerase chain reaction (PCR) analysis. The addition of M-CSF or ODF alone induced TRAP-positive multinucleated cell formation. Resorption pits were rarely detected with M-CSF alone. ODF was capable of inducing bone resorption and enhancing osteoclastogenesis, as well as bone resorption in the presence of M-CSF. In the coculture system, both osteoclast formation and bone resorption were inhibited by OPG in a dose-dependent manner. In all experiments, synovial cells, including macrophages and fibroblasts, expressed the mRNA for RANK, ODF, and OPG. Our findings suggest that ODF plays a role in regulating RA synovial macrophage–osteoclast differentiation, and that synovial cells might have the ability to produce ODF. OPG might be further developed as a new strategy for treating bone destruction in RA joints. Received: January 30, 2001 / Accepted: May 18, 2001     

Should rheumatoid factor in rheumatoid arthritis be sent to Davy Jones's Locker?

This article reviews the characteristics and weaknesses of the rheumatoid factor (RF) assay compared with anti-citrullinated peptide antibody (ACPA) testing in the work-up of patients with synovitis. This should lead physicians to change their ordering habits and replace RF by ACPA. For RA diagnosis, good clinical judgement based on clinical history, physical examination and routine laboratory work exceeds the value of RF and ACPA assays. In settings of both low and high pretest probability, the added value of each of these assays is low. In cases with intermediate probability, ACPA assays are superior to immunoglobulin (Ig)M-RF because of their higher specificity, and they should be the first choice in a RA diagnostic work-up. Dual testing brings few additional advantages and increases costs significantly. ACPA and IgM-RF are both imperfect tests; around 30% of patients with manifest RA will test negative in both assays and therefore caution needs to be exercised when interpreting negative results. Since 2009, the anti-cyclic citrullinated peptide (anti-CCP) antibody assay has been the only assay available at our institution for RA work-up, with IgM-RF available on a case-by-case basis for non-RA diseases. This has led to a 70% reduction in RF assays performed annually.     

Cyclic adenosine 5′-monophosphate in synovial fluid of rheumatoid arthritis and osteoarthritis patients

The relationship between synovial fluid (SF) cAMP level and IL-18 and PGE2 SF levels in rheumatoid arthritis (RA) and osteoarthritis (OA) patients, and between SF cAMP level and disease as well as inflammatory activity in RA were investigated in 17 RA and 19 OA patients. Erythrocyte sedimentation rate (ESR), serum (S) C-reactive protein (CRP) level and SF IL-18 level were higher in RA than in OA patients. SF PGE2 level was similar in both groups. SF cAMP level was higher in OA than in RA patients. In RA patients, SF cAMP level showed negative correlation with Disease Activity Score including a 28-joint count and S CRP, ESR and SF IL-18 level. The results suggest that cAMP promotes anti-inflammatory response in RA and OA patients, which is higher in the latter. Promotion of anti-inflammatory response by cAMP elevating agents might be useful in the treatment of RA.     

Are anti-citrulline autoantibodies better serum markers for rheumatoid arthritis than rheumatoid factor in Thai population?

The aim of the study is to evaluate the prevalence of anti-citrulline antibodies (anti-CCP) versus rheumatoid factor (RF) in a cohort of Thai patients with rheumatoid arthritis (RA), a variety of rheumatic diseases other than RA and healthy controls. The association between anti-CCP and RA disease activity was also examined. Serum from 125 RA patients, 60 from other rheumatic diseases (non-RA) and 60 from healthy controls were tested for IgM RF and second generation anti-CCP. The association between anti-CCP, RF, the Disease Activity Score (DAS 28) and other relevant laboratory tests (CBC, ESR and CRP) were assessed. The sensitivity and specificity of anti-CCP antibody were 58.7 and 100% when compared with 63.5 and 98.3% for RF. These differences were not statistically significant. The anti-CCP outperformed RF in terms of the positive-predictive values (100 vs. 97.6%); however, the negative-predictive values were 72.4% for RF and 69.6% for anti-CCP. The sensitivity when either anti-CCP or RF was positive increased to 71.2%. Nine out of 45 RF-negative patients had a positive anti-CCP test. Anti-CCP was significantly correlated with parameters of inflammation, but not with DAS 28. In conclusion, although anti-CCP is better than RF in distinguishing RA from other rheumatic diseases, its cost, which is 3.3 times higher than the RF test precludes it from replacing RF as a serum marker for Thai patients with RA. The treatment decisions cannot be based on the test alone, as it has no correlation with DAS 28. Its usefulness is in patients with suspected RA who have had a negative RF test.     

Multiple fungus balls in rheumatoid arthritis–associated honeycomb lung

Clinical Rheumatology -     

Are plasma and synovial fluid leptin levels correlated with disease activity in rheumatoid arthritis ?

Leptin is an adypocyte derivated peptide hormone that plays a major role in preventing obesity development by the effects at the hypothalamic level. In our study leptin levels of 41 rheumatoid arthritis (RA) patients and 25 healthy subjects as control group were assessed. Synovial fluid from 21 RA patients were collected to detect leptin levels. Synovial fluid and plasma leptin levels were analysed and correlated with RA duration, ESR, CRP, X ray changes (erosive or non-erosive disease) and negative or positive test for rheumatoid factor. There wasn’t any significant difference at plasma leptin levels between RA patients (3.91 ± 6.15) and control group (4.94 ± 6.44) (p > 0.05). Plasma leptin levels were correlated with body mass index (BMI) in both healthy subjects and RA patients (r = 0.37; p = 0.018). Therefore in RA patients, plasma and synovial fluid leptin levels were not correlated with disease duration, ESR, CRP, negative or positive test for rheumatoid factor and erosive or non-erosive disease (p > 0.05). In conclusion leptin is correlated with BMI both in RA patients and healthy individuals but no considerable relation with disease activity.     

Tumour necrosis factor a −308 promoter polymorphism in patients with rheumatoid arthritis

There are controversial reports that TNF-a promoter polymorphism may be an independent marker of susceptibility to rheumatoid arthritis (RA). We used Polymerase chain reaction amplification and Restriction fragment length polymorphism for analysis of the polymorphism at position -308 in promoter of TNF-α gene in 34 patients with RA and 30 healthy individuals. Distribution of TNF-genotypes in RA patients did not differ from that in controls. Moreover, there was apparent association between the -308 TNF-α polymorphism and erosions in hand x-Ray was found (P value = 0.043). We suggest that TNF-α -308 promoter polymorphism is not a genetic risk factor for RA susceptibility but may be associated with radiographic damage in rheumatoid patients. All work was funded by the Chancellor for Research of Mashhad University of Medical Science.     

Association of macrophage migration inhibitory factor gene −173 G/C polymorphism with prognosis in turkish children with juvenile rheumatoid arthritis

The objectives of this study were to determine genotypic and allelic frequencies of macrophage migration inhibitory factor (MIF) gene −173 G/C polymorphism in patients with juvenile rheumatoid arthritis (JRA) and to evaluate the association of the MIF −173 C allele with the outcome of JRA. Genomic DNA was collected from 67 JRA patients and 153 healthy individuals. To evaluate the association of the MIF −173 polymorphism with the outcome, we analyzed the data concerning the treatment regimen, duration of glucocorticoid treatment, score on the childhood health assessment questionnaire (C-HAQ) and the number of joints with active arthritis. Nonsignificant differences were observed between the study and control groups in the distribution of genotype and allele frequencies of the MIF gene −173 G/C polymorphism. In JRA patients, carrying a MIF −173 C allele, the number of disease modifying antirheumatic drugs required for the treatment was more, the duration of glucocorticoid treatment was significantly longer, and at the last visits the C-HAQ scores and the number of joints with active arthritis were significantly higher. MIF gene −173 C allele frequency did not differ between the controls and JRA patients. MIF −173 C allele did not confer increased susceptibility to JRA in our study group. Carriage of the MIF −173 C allele was found to be a strong predictor of poor outcome in all types of JRA.     

Is rheumatoid factor still a superior test for the diagnosis of rheumatoid arthritis?

The diagnosis of rheumatoid arthritis (RA) is based primarily on the 1987 revised American College of Rheumatology criteria for RA, which considers mainly the clinical symptoms. But typical clinical symptoms of RA are not manifested completely in early disease course. On the other hand, appreciable advantages have been made in the therapeutic strategy of RA in the last decade and highly effective disease-modifying anti-rheumatic drugs are available now for the control of RA. The treatment strategy for the control of early RA is aggressive. Thus, a highly specific and early diagnostic marker is needed for the detection of RA. Our study is an attempt to see the role of anti-CCP2 antibody (claimed to be highly specific and early diagnostic tool) in the diagnosis of RA. We studied 119 cases of RA in terms of clinical symptoms, disease duration and various autoantibody [including rheumatoid factor (RF), anti-CCP2 antibody, antinuclear antibody, anti-dsDNA] and C-reactive protein status. All the tests were also performed in 26 age and sex-matched healthy controls. Estimation of antibodies was done by quantitative ELISA. IgM RF was positive in 47.89% cases (p value = 0.000), followed by IgG RF (42.01%, p = 0.000) and IgA RF (36.97%, p = 0.000). RF was positive in 64.7% RA cases (p value = 0.000) when all three isotypes were tested together. RF was also detected in one healthy control. In 92 cases, anti-CCP2 Ab was done, hence other data were analyzed further in 92 cases only. Anti-CCP2 Ab was positive (cut-off = 15.0 U/ml) in only 50% RA patients but none of the healthy controls was positive for it. Swelling of joints was seen in 82.6% anti-CCP2 Ab positive cases (p value = 0.092) when compared with anti-CCP2 Ab negative cases (67.4%) while among RF positive cases, only 65.4% ((p value = 0.010) cases had swelling of joints. Out of 39 RA cases presenting with disease duration less than 1 year, only 48.71% patients were anti-CCP2 Ab positive while RF was positive in 61.53% patients. Utility of various combined autoantibody tests revealed that if one does all isotypes of RF (IgG, IgA and IgM) only, then 64.7% RA cases can be diagnosed and if anti-CCP2 Ab is added to it, the sensitivity increases to 75.56%. Thus, our study concludes that anti-CCP2 Ab is not a sensitive test for the diagnosis of RA neither it is useful in early diagnosis of RA, but it increases the sensitivity if added with all RF isotypes.     

Regulation of TNFα and IL1β in rheumatoid arthritis synovial fibroblasts by leukotriene B4

Arachidonic acid metabolites, such as leukotriene B4 (LTB4), are known to play an important role in pathogenesis of rheumatoid arthritis (RA). Apart from leukocytes, RA synovial fibroblasts (RASF) produce a broad array of inflammatory mediators to recruit, retain and activate immune cells and resident mesenchymal cells in the joints to promote ongoing inflammation and tissue destruction. To determine how LTB4 may contribute to this process, RASF was cultured from synovial tissues collected from RA patients undergoing total knee replacement. The level of LTB4 in culture medium was determined using ELISA, and expression of LTB4 receptors (BLT1 and BLT2) by RT-PCR. In the presence of exogenous LTB4, mRNA and protein levels of tumor necrosis factor-α (TNFα) and interleukin 1β (IL1β) were determined by real-time PCR and ELISA. Furthermore, we examined the effects of leukotrienes synthesis inhibitors, MK886 and bestatin, on mRNA and protein levels of TNFα and IL1β in RASF. We found that LTB4 was present at a low concentration in the culture medium of RASF, and the major LTB4 receptor expressed in RASF was BLT2. LTB4 synthesis was activated by treatment with LIT (LPS, ionomycin and thapsogargin), and suppressed by MK886 and bestatin. Exogenous LTB4 remarkably increased the expression of TNFα and IL1β at both the mRNA level and the protein level. In contrast, MK886 and bestatin significantly inhibited their expression. These data suggested that LTB4 contributed to RA by regulating the expression of TNFα and IL1β in RASF. BLT2 was probably the major receptor mediating such effects.     

A case–control study of rheumatoid arthritis revealed abdominal obesity and environmental risk factor interactions in northern China

Background: The aim of this study was to evaluate new and previously hypothesized environmental risk factors and their interaction with rheumatoid arthritis (RA).

Methods: Four hundred patients recently diagnosed with RA and 400 controls frequency-matched by gender and birth year using Propensity Score Matching (PSM) were selected from northern China. Investigation was performed using self-reported data from interviewer-administered surveys. Associations between exposure variables and risk of RA were evaluated using multifactor non-conditional logistic regression.

Results: It showed that damp localities, draft indoor, abdominal obesity (AO), and family history of RA among first-degree relatives were independent risk factors and drinking of milk was independent protective factors for RA. Besides these risk factors, in women, infrequent delivery times, early age at menopause, and late age at menarche were also independent risk factors for RA. Both the additive model and the multiplication model suggested that there was an interaction relationship between AO and damp localities (p?p?p?p?Conclusions: In northern China, damp localities, draft indoor, AO, family history of RA among first-degree relatives, and no milk drinking may be important risk factors of RA patients.