Shigeki Momohara

A regulatory variant in CCR6 is associated with rheumatoid arthritis susceptibility

Rheumatoid arthritis is a common autoimmune disease with a complex genetic etiology. Here, through a genome-wide association study of rheumatoid arthritis, we identified a polymorphism in CCR6, the gene encoding chemokine (C-C motif) receptor 6 (a surface marker for Th17 cells) at 6q27, that was associated with rheumatoid arthritis susceptibility and was validated in two independent replication cohorts from Japan (rs3093024, a total of 7,069 individuals with rheumatoid arthritis (cases) and 20,727 controls, overall odds ratio = 1.19, P = 7.7 × 10−19). We identified a triallelic dinucleotide polymorphism of CCR6 (CCR6DNP) in strong linkage disequilibrium with rs3093024 that showed effects on gene transcription. The CCR6DNP genotype was correlated with the expression level of CCR6 and was associated with the presence of interleukin-17 (IL-17) in the sera of subjects with rheumatoid arthritis. Moreover, CCR6DNP was associated with susceptibility to Graves and Crohns diseases. These results suggest that CCR6 is critically involved in IL-17–driven autoimmunity in human diseases.

Molecular aspects of rheumatoid arthritis: chemokines in the joints of patients

Rheumatoid arthritis (RA) is a chronic symmetric polyarticular joint disease that primarily affects the small joints of the hands and feet. The inflammatory process is characterized by infiltration of inflammatory cells into the joints, leading to proliferation of synoviocytes and destruction of cartilage and bone. In RA synovial tissue, the infiltrating cells such as macrophages, T cells, B cells and dendritic cells play important role in the pathogenesis of RA. Migration of leukocytes into the synovium is a regulated multi‐step process, involving interactions between leukocytes and endothelial cells, cellular adhesion molecules, as well as chemokines and chemokine receptors. Chemokines are small, chemoattractant cytokines which play key roles in the accumulation of inflammatory cells at the site of inflammation. It is known that synovial tissue and synovial fluid from RA patients contain increased concentrations of several chemokines, such as monocyte chemoattractant protein‐4 (MCP‐4)/CCL13, pulmonary and activation‐regulated chemokine (PARC)/CCL18, monokine induced by interferon‐γ (Mig)/CXCL9, stromal cell‐derived factoru20031 (SDF‐1)/CXCL12, monocyte chemotactic proteinu20031 (MCP‐1)/CCL2, macrophage inflammatory proteinu20031α (MIP‐1α)/CCL3, and Fractalkine/CXC3CL1. Therefore, chemokines and chemokine‐receptors are considered to be important molecules in RA pathology.

Association of STAT4 with susceptibility to rheumatoid arthritis and systemic lupus erythematosus in the Japanese population.

OBJECTIVEnSTAT4 encodes a transcriptional factor that transmits signals induced by several key cytokines, and it might be a key molecule in the development of autoimmune diseases. Recently, a STAT4 haplotype was reported to be associated with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) in Caucasian populations. This was replicated in a Korean RA population. Interestingly, the degree of risk of RA susceptibility with the STAT4 haplotype was similar in the Caucasian and Korean populations. The present study was undertaken to investigate the effect of STAT4 on susceptibility to RA and SLE in the Japanese.nnnMETHODSnWe performed an association study using 3 independent Japanese RA case-control populations (total 3,567 cases and 2,199 controls) and 3 independent Japanese SLE populations (total 591 cases). All samples were genotyped using the TaqMan fluorogenic 5 nuclease assay for single-nucleotide polymorphism (SNP) rs7574865, which tags the susceptibility haplotype. The association of the SNP with disease susceptibility in each case-control study was calculated using Fishers exact test, and the results were combined, using the Mantel-Haenszel method, to obtain combined odds ratios (ORs).nnnRESULTSnWe observed a significant association of the STAT4 polymorphism with susceptibility to both RA and SLE. The combined ORs for RA and SLE, respectively, were 1.27 (P = 8.4 x 10(-9)) and 1.61 (P = 2.1 x 10(-11)) for allele frequency distribution; these ORs were quite similar to those previously observed in the Caucasian population.nnnCONCLUSIONnWe conclude that STAT4 is associated with RA and SLE in the Japanese. Our results indicate that STAT4 is a common genetic risk factor for autoimmune diseases, with similar strength across major racial groups.

A role for the aryl hydrocarbon receptor and the dioxin TCDD in rheumatoid arthritis

OBJECTIVEnEnvironmental factors are involved in RA pathogenesis and epidemiological studies have suggested that smoking is an environmental risk factor for RA. The 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is one of the major toxic components in cigarettes. To clarify the biological effects of smoking in RA, we investigated the role of TCDD in RA pathogenesis.nnnMETHODSnHuman synovial tissue was obtained from RA and OA patients and aryl hydrocarbon receptor (AhR) expression in these tissues was evaluated using immunohistochemistry and real-time PCR. Expression of various cytokines was measured by real-time PCR following stimulation of RA synoviocytes with different concentrations of TCDD. To study the role of AhR, we treated RA synoviocytes with alpha-naphthoflavone, a known AhR antagonist. To evaluate which signal transduction pathways were stimulated by the TCDD-AhR interaction, we used inhibitors of nuclear factor-kappaB (NF-kappaB) and extra-cellular stimulus-activated kinase (ERK).nnnRESULTSnHigher AhR mRNA and protein levels were observed in RA synovial tissue than in OA tissue. TCDD up-regulated the expression of IL-1beta, IL-6 and IL-8 through binding to AhR, and this effect was transmitted via the NF-kappaB and ERK signalling cascades. AhR expression in synovial cells was up-regulated by TNF-alpha.nnnCONCLUSIONnTNF-alpha activates AhR expression in RA synovial tissue, and that cigarette smoking and exposure to TCDD enhances RA inflammatory processes. TCDD induces inflammatory cytokines via its association with AhR, resulting in stimulation of the NF-kappaB and ERK signalling cascades. Thus TCDD exposure, such as smoking exacerbates RA pathophysiology.

Mortality and cause of death in Japanese patients with rheumatoid arthritis based on a large observational cohort, IORRA

Objectives: To investigate mortality, cause of death, and risk factors related to mortality in Japanese patients with rheumatoid arthritis (RA). Methods: The IORRA cohort is a large observational cohort established in 2000 at the Institute of Rheumatology, Tokyo Womens Medical University. Essentially, all RA patients were registered and clinical parameters were assessed biannually. For patients who failed to participate in subsequent surveys, simple queries were mailed to confirm survival. Standardized mortality ratios (SMRs) were calculated and mortality risk factors were analysed using a Cox proportional hazard model. Results: We analysed 7926 patients (81.9% females; mean age 56.3 ± 13.1 years; mean disease duration 8.5 ± 8.3 years) with RA who enrolled in IORRA from October 2000 to April 2007. During the observational period (35 443.0 person-years), 289 deaths were reported. Major causes of death included malignancies (24.2%), respiratory involvement (24.2%) including pneumonia (12.1%) and interstitial lung disease (ILD) (11.1%), cerebrovascular disease (8.0%), and myocardial infarction (7.6%). As death was not confirmed in all patients, the SMR was deduced to be between 1.46 [95% confidence interval (CI) 1.32–1.60] and 1.90 (95% CI 1.75–2.07) for all patients, between 1.45 (95% CI 1.22–1.70) and 1.70 (95% CI 1.45–1.97) for men, and between 1.46 (95% CI, 1.29–1.65) and 2.02 (95% CI 1.82–2.24) for women. Factors associated with increased mortality included male gender, older age, worse physical disability, positive rheumatoid factor (RF), corticosteroid use, and presence of ILD. Conclusion: The mortality of Japanese RA patients is comparable to that in previous reports from western countries, even though the causes of death were significantly different.

Efficacy and tolerability of tocilizumab in rheumatoid arthritis patients seen in daily clinical practice in Japan: results from a retrospective study (REACTION study).

Tocilizumab, a humanized monoclonal antibody to the interleukin 6 (IL-6) receptor, was approved for use as rheumatoid arthritis (RA) therapy in Japan in 2008, but its efficacy and tolerability in daily practice has not yet been reported. We report the results of a multicenter retrospective study on the efficacy and safety of tocilizumab involving all patients (n = 229) who were started on tocilizumab therapy at three rheumatology institutes in Japan from April 2008 through to March 2009. Tocilizumab was infused every 4xa0weeks at a dose of 8xa0mg/kg according to the drug labeling. Among the 229 patients, 55% concomitantly received methotrexate (MTX) and 63% had previously received anti-tumor necrosis factor (TNF) therapy. Average disease activity score (DAS) 28 of all 229 patients significantly decreased from 5.70 to 3.25 after 24xa0weeks of therapy. A European League Against Rheumatism (EULAR) good response and DAS28 remission was achieved in 57.4 and 40.7% of the patients, respectively, at 24xa0weeks. White blood cell counts significantly decreased and liver enzymes and total cholesterol slightly but significantly increased; however, liver enzyme levels did not increase in patients without MTX. Tocilizumab was discontinued in 47 cases (20.5%) due to lack of efficacy (5.2%), adverse events (11.4%), and other reasons (3.9%). The overall retention rate at 24xa0weeks was 79.5%. Based on these results, we conclude that tocilizumab therapy in daily rheumatology practice appears to be highly efficacious and well tolerated among active RA patients, including the anti-TNF therapy-refractory population. Tocilizumab infusion is therefore applicable not only as an alternative approach for anti-TNF therapy-resistant patients, but also as primary biologic therapy for active RA patients.

The association of a nonsynonymous single-nucleotide polymorphism in TNFAIP3 with systemic lupus erythematosus and rheumatoid arthritis in the Japanese population.

OBJECTIVEnGenome-wide association (GWA) studies in systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) in Caucasian populations have independently identified risk variants in and near the tumor necrosis factor alpha (TNFalpha)-induced protein 3 gene (TNFAIP3), which is crucial for the regulation of TNF-mediated signaling and Toll-like receptor signaling. The aim of this study was to assess the role of TNFAIP3 in the development of SLE and RA in Japanese subjects.nnnMETHODSnWe selected 2 single-nucleotide polymorphisms (SNPs) from previous GWA studies. Rs2230926 is a nonsynonymous SNP in TNFAIP3 and is associated with SLE, while rs10499194 is an intergenic SNP associated with RA. We then performed 2 independent sets of SLE case-control comparisons (717 patients and 1,362 control subjects) and 3 sets of RA case-control comparisons (3,446 patients and 2,344 control subjects) using Japanese subjects. We genotyped SNPs using TaqMan assays.nnnRESULTSnWe observed a significant association between rs2230926 and an increased risk of SLE and RA in the Japanese population (for SLE, odds ratio [OR] 1.92, 95% confidence interval [95% CI] 1.53-2.41, P = 1.9 x 10(-8); for RA, OR 1.35, 95% CI 1.18-1.56, P = 2.6 x 10(-5)). The intergenic SNP rs10499194 was also associated with SLE and RA, while the risk allele for RA in Caucasians was protective against the diseases in our population.nnnCONCLUSIONnWe demonstrated a significant association between the nonsynonymous variant in TNFAIP3 and the risk for SLE and RA in the Japanese population. TNFAIP3, similar to STAT4 and IRF5, may be a common genetic risk factor for SLE and RA that is shared between the Caucasian and Japanese populations.

Decrease in orthopaedic operations, including total joint replacements, in patients with rheumatoid arthritis between 2001 and 2007: data from Japanese outpatients in a single institute-based large observational cohort (IORRA)

Several studies from different countries show that the rate of orthopaedic surgery has decreased for patients with rheumatoid arthritis (RA) in recent years. In Sweden, there was a decrease in RA-related lower limb surgical procedures between 1987 and 2001,1 and in RA-related upper limb surgery between 1998 and 2004.2 Denmark has reported a decrease in the incidence of total hip arthroplasties due to RA,3 and the number of total joint replacement (TJR) operations and synovectomies decreased in the Norwegian population from 1994 to 2004.4 Japan has also reported the declining use of synovectomy surgery for patients with RA.5 These changes may reflect trends in disease severity, management and health outcomes in each country. Meanwhile, Sokka et al reported that the rate of TJR …

Is minimally invasive surgery in total knee arthroplasty really minimally invasive surgery

Minimization of soft-tissue damage is one of the primary purposes behind the application of minimally invasive surgery (MIS) in total knee arthroplasty (TKA). A consecutive series of 147 TKAs were enrolled in the present study, with 96 MIS-TKAs using 11 quadriceps-sparing, 46 subvastus, 32 midvastus, and 7 parapatellar approaches and 51 conventional TKAs using 22 subvastus, 9 midvastus, and 20 parapatellar approaches. Serum levels of creatinine phosphokinase, myoglobin, aldolase, lactate dehydrogenase, glutamic oxaloacetic transaminase, and creatinine were measured on postoperative days 0, 1, 2, 4, 7, and 14. Postoperative rising index (RI) was expressed as a proportion of the preoperative value. When RIs were compared between MIS-TKA and conventional TKA, no significant differences were found for any enzymes. Interestingly, the midvastus approach displayed the highest RIs for creatinine phosphokinase and myoglobin between the 4 vastus-splitting approaches. Consequently, degree of muscle damage was equivalent between MIS-TKA and conventional TKA, whereas types of vastus-splitting approach appeared closely related to muscle damage.

Incidence of and risk factors for interstitial pneumonia in patients with rheumatoid arthritis in a large Japanese observational cohort, IORRA

Interstitial lung disease (ILD) is a frequently encountered and sometimes life-threatening complication among patients with rheumatoid arthritis (RA). In this study, we aim to clarify the incidence of and risk factors for ILD using a large observational cohort of RA patients. We analyzed the database from a large observational cohort of Japanese RA patients, the Institute of Rheumatology, Rheumatoid Arthritis (IORRA) cohort. We defined as interstitial pneumonia (IP) computed tomography (CT) pattern of nonspecific interstitial pneumonia or diffuse alveolar damage. Newly developed IP was identified from patient reports over 2.5xa0years (April 2004 to October 2006) and was confirmed by extensive medical record, chest X-ray radiograph, and CT. The raw and age/gender-adjusted incidence of IP were reported. IP risk factors were analyzed using a nested case–control design was employed using conditional logistic regression analysis with a stepwise method. Thirty-seven patients among 5,699 RA patients were diagnosed with newly developed IP, including 18 cases with methotrexate-induced pneumonitis (MTX-IP) and 15 cases with IP associated with RA (RA-IP). The age-adjusted incidence of MTX-IP among total patients, males, and females was 3.775, 6.667, and 1.013 per 1,000 cases, respectively, and of RA-IP among total patients, males, and females was 1.056, 1.452, and 0.677 per 1,000 cases, respectively. Conditional logistic regression analysis after stepwise variable selection identified male gender, increased Japanese version of the Health Assessment Questionnaire (J-HAQ) score, decreased pain visual analog scale (VAS), and elevated erythrocyte sedimentation rate as significant risk factors for MTX-IP, while the only risk factor for RA-IP was male gender. The incidence of and risk factors for IP in RA patients were determined in a large observational cohort of RA patients in Japan.