Ran Nakashima

The RIG-I-like receptor IFIH1/MDA5 is a dermatomyositis-specific autoantigen identified by the anti-CADM-140 antibody

OBJECTIVES Various autoantibodies are detected in the sera of PM/DM patients. Some of them are specific to PM/DM patients and closely associated with clinical manifestations of the diseases. Recently, the anti-CADM-140 antibody was reported to be found specifically in clinically amyopathic DM (C-ADM) patients and to be associated with acute interstitial lung disease (ILD). We assessed the clinical significance of the anti-CADM-140 antibody and then investigated the autoantigen recognized by the anti-CADM-140 antibody. METHODS Autoantibodies were screened in 192 patients with various CTDs and 21 healthy controls using immunoprecipitation with [(35)S]methionine-labelled HeLa cells. Immunoabsorbent column chromatography was used to purify an autoantigen that was subsequently subjected to peptide mass fingerprinting. RESULTS The anti-CADM-140 antibody was revealed to be specific to DM. Most of the anti-CADM-140-positive patients were C-ADM although some of them showed apparent myositis. The anti-CADM-140-positive patients frequently showed hyperferritinaemia and acute progressive ILD with poor prognosis. The anti-CADM-140 antibody was shown to recognize IFN induced with helicase C domain protein 1 (IFIH1), also known as the melanoma differentiation-associated gene 5 (MDA5), which is one of the RIG-I-like receptors and plays a role in innate immune responses. CONCLUSION The anti-CADM-140 antibody was a marker of DM and intractable ILD and recognized IFIH1/MDA5, which is involved in innate immunity. These findings may give a new insight into the pathogenesis of DM.

Anti-MDA5 and anti-TIF1-γ antibodies have clinical significance for patients with dermatomyositis

OBJECTIVES Myositis-specific autoantibodies are useful for diagnosing PM/DM. Recently, two new myositis-specific autoantibodies against melanoma differentiation-associated gene 5 (MDA5) and transcriptional intermediary factor 1-gamma (TIF1-gamma) were identified in DM. Here, we detected these autoantibodies in patient sera using new assays with recombinant MDA5 and TIF1-gamma, and associated clinical features with the presence of anti-MDA5 or anti-TIF1-gamma antibodies. METHODS We screened 135 Japanese patients with various CTDs, including 82 with DM. DM patients were classified as clinically amyopathic DM (CADM), cancer-associated DM or classical DM without cancer. Anti-MDA5 and anti-TIF1-gamma antibodies were detected by their ability to immunoprecipitate biotinylated recombinant proteins. RESULTS Sera from 21 (26%) of 82 DM patients immunoprecipitated MDA5, and every anti-MDA5-positive patient had DM (except one patient with SSc). Sera from 20 (65%) of 31 CADM patients reacted with MDA5. Notably, anti-MDA5-positive DM patients had significantly more interstitial lung disease than anti-MDA5-negative DM patients (95 vs 32%, P < 0.001). Sera from 12 (15%) of 82 DM patients immunoprecipitated TIF1-gamma, and anti-TIF1-gamma antibodies were only detected in DM patients. Strikingly, 7 (58%) of 12 patients with cancer-associated DM had sera that reacted with TIF1-gamma. Anti-TIF1-gamma-positive DM patients had significantly more internal malignancies than anti-TIF1-gamma-negative DM patients (58 vs 9%, P < 0.001). CONCLUSIONS Anti-MDA5 and anti-TIF1-gamma antibodies were confirmed to be serological DM subset markers. Anti-MDA5 and anti-TIF1-gamma antibodies were detected based on their ability to immunoprecipitate biotinylated recombinant MDA5 and TIF1-gamma, and were closely associated with life-threatening complications in DM.

Autoantibodies in idiopathic inflammatory myopathy: an update on clinical and pathophysiological significance.

Purpose of reviewIdiopathic inflammatory myopathy is characterized by the production of autoantibodies to various cellular constituents. These autoantibodies closely correlate with certain clinical conditions and prognosis of disease. This review examines recent progress in myositis-specific autoantibodies, particularly in their clinical significance and pathophysiological roles. Recent findingsDuring the 1-year review period, novel myositis-specific autoantibodies were identified in clinically amyopathic dermatomyositis (anti-CADM-140 antibody) and malignancy-associated myositis (anti-p155 and anti-p155/p140 antibodies). These new autoantibodies are extremely important because it is thought that myositis-specific autoantibodies are negative in these subgroups, and may enable a new classification of idiopathic inflammatory myopathy. New clinical aspects of other myositis-specific autoantibodies (anti-aminoacyl-tRNA synthetases, anti-signal recognition particles and anti-Mi-2) are also described. The possibility was raised that the high expression of myositis-specific autoantigens in regenerating muscle cells and certain cancers may be involved in initiating and perpetuating the autoimmune response in myositis. SummaryMyositis-specific autoantibodies are useful markers for clinical diagnosis, classification and predicting prognosis of idiopathic inflammatory myopathy. To understand the etiopathogenic mechanisms of the disease it is particularly important to elucidate the nature of target autoantigens recognized by these myositis-specific autoantibodies.

Interstitial Lung Disease in Myositis: Clinical Subsets, Biomarkers, and Treatment

Interstitial lung disease (ILD) is the most frequent organ involvement (found in nearly half) of myositis patients, but it reveals various clinical courses and therapeutic responsiveness according to clinical and serological subsets. Autoantibodies, as well as imaging and histopathological studies, are useful for the classification of ILD in myositis and provide useful information for predicting prognosis and determining treatment. Antisynthetase antibodies are correlated with chronic and recurrent ILD, whereas anti-CADM-140 (MDA5/IFIH1) antibodies are a marker of acute progressive ILD in clinically amyopathic dermatomyositis. Serum KL-6, SP-D, and ferritin are useful biomarkers for monitoring the activity and severity of ILD. Regarding treatment, glucocorticoids are the first-line drug, but additional immunomodulating drugs are also used in refractory patients. Cyclophosphamide and calcineurin inhibitors (cyclosporine and tacrolimus) appear to be the key drugs in the treatment of refractory myositis–ILD. Rituximab may become another candidate if these drugs are not effective.

HRCT features of interstitial lung disease in dermatomyositis with anti-CADM-140 antibody

BACKGROUND Anti-CADM-140 antibody (anti-CADM-140), also referred to as anti-melanoma differentiation-associated gene 5 (MDA5) antibody, is a myositis-specific antibody identified in the sera of patients with clinically amyopathic dermatomyositis (C-ADM) and is associated with a worse prognosis in dermatomyositis-associated interstitial lung disease (DM-ILD). We sought to determine high-resolution computed tomography (HRCT) features of DM-ILD with anti-CADM-140. METHODS Twenty-five patients newly diagnosed with DM-ILD at Kyoto University Hospital between 2005 and 2009 were retrospectively reviewed. Serum anti-CADM-140 was measured in all patients at their first visit. Chest HRCT images taken prior to treatment were classified based on the dominant findings and their distribution, and compared between patients with and without the antibody. RESULTS Of 25 DM-ILD patients, 12 were positive and 13 were negative for anti-CADM-140. HRCT patterns differed significantly between anti-CADM-140-positive and negative patients (P = 0.002). Lower consolidation or ground-glass attenuation (GGA) pattern (50.0%) and random GGA pattern (33.3%) were the predominant patterns in anti-CADM-140-positive cases, while lower reticulation pattern (69.2%) was frequently seen in anti-CADM-140-negative cases. Anti-CADM-140-positive cases were also significantly characterized by the absence of intralobular reticular opacities (0% in anti-CADM-140 (+) vs. 84.6% in anti-CADM-140 (-), P < 0.0001). CONCLUSIONS Anti-CADM-140-positive DM-ILD was characterized by lower consolidation or GGA pattern, random GGA pattern, and the absence of intralobular reticular opacities.

Myositis autoantibodies in Korean patients with inflammatory myositis: anti-140-kDa polypeptide antibody is primarily associated with rapidly progressive interstitial lung disease independent of clinically amyopathic dermatomyositis.

BackgroundTo investigate the association between myositis autoantibodies and clinical subsets of inflammatory myositis in Korean patients.MethodsImmunoprecipitation was performed using the sera of classic polymyositis (PM) (n = 11) and dermatomyositis (DM) (n = 38) patients who met the Bohan and Peter criteria for definite inflammatory myositis. A panel of defined myositis autoantibodies was surveyed to investigate the association between each autoantibody and clinical subsets of inflammatory myositis.ResultsEither MSAs, anti-p140, or anti-p155/140 antibodies were found in 63.3% (31/49) of the study subjects. Anti-140-kDa-polypeptide (anti-p140) (18.4%, 9/49) and anti-155/140-kDa polypeptide (anti-p155/140) (16.3%, 8/49) antibodies were the most common, followed by anti-Mi2 (14.3%, 7/49), anti-ARS (12.2%, 6/49) and anti-SRP (2.0%, 1/49) antibodies. All MSAs and anti-p140 and anti-p155/140 antibodies were mutually exclusive. Anti-p140 (23.7%, 9/38), anti-p155/140 (21.1%, 8/38), and anti-Mi2 (18.4%, 3/38) antibodies were found exclusively in DM patients. Anti-p140 antibody was associated with rapidly progressive interstitial lung disease (ILD) (p = 0.001), with a sensitivity of 100.0% (4/4) and a specificity of 85.3% (29/34) in DM patients. Anti-p155/140 antibody was associated with cancer-associated DM (p = 0.009), with a sensitivity of 55.6% (5/9) and a specificity of 89.7% (26/29). Cancer-associated survival was significantly worse when anti-p155/140 antibody was present (19.2 ± 7.6 vs. 65.0 ± 3.5 months, p = 0.032). Finally, anti-ARS antibodies were associated with stable or slowly progressive ILD in PM and DM patients (p = 0.005).ConclusionsAnti-p140 and anti-p155/140 antibodies were commonly found autoantibodies in Korean patients with inflammatory myositis. Despite the lack of clinically amyopathic DM patients in the study subjects, a strong association was observed between anti-p140 antibody and rapidly progressive ILD. Anti-p155/140 antibody was associated with cancer-associated myositis and poor survival.

A Clinical, Pathological, and Genetic Characterization of Methotrexate-associated Lymphoproliferative Disorders

Objective. Methotrexate-associated lymphoproliferative disorders (MTX-LPD) often regress spontaneously during MTX withdrawal, but the prognostic factors remain unclear. The aim of our study was to clarify the clinical, histological, and genetic factors that predict outcomes in patients with MTX-LPD. Methods. Patients with MTX-LPD diagnosed between 2000 and 2012 were analyzed retrospectively regarding their clinical course, site of biopsy, histological typing, Epstein-Barr virus (EBV) in situ hybridization and immunostaining, and HLA type. Results. Twenty-one patients, including 20 with rheumatoid arthritis (RA) and 1 with polymyositis, were analyzed. The mean dose of MTX was 6.1 mg/week and the mean duration of treatment was 71.1 months. Clinically, 5 patients were diagnosed with EBV-positive mucocutaneous ulcer (EBVMCU) and had polymorphic histological findings. The proportion of those patients successfully treated solely by withdrawal of MTX was significantly greater than that of those without EBVMCU (75% vs 7.7%, p = 0.015). The HLA-B15:11 haplotype was more frequent in patients with EBV+ RA with MTX-LPD than in healthy Japanese controls (p = 0.0079, Bonferroni’s method). EBV latency classification and HLA typing were not associated with the prognosis of MTX-LPD in our cohort. Conclusion. Our data demonstrate that patients in the EBVMCU, a specific clinical subgroup of MTX-LPD, had a better clinical outcome when MTX was withdrawn than did other patients with MTX-LPD.

The Multicenter Study of a New Assay for Simultaneous Detection of Multiple Anti-Aminoacyl-tRNA Synthetases in Myositis and Interstitial Pneumonia

Objective Autoantibodies to aminoacyl-tRNA synthetases (ARSs) are useful in the diagnosis of idiopathic inflammatory myopathy (IIM) with interstitial pneumonia (IP). We developed an enzyme-linked immunosorbent assay (ELISA) system using a mixture of recombinant ARS antigens and tested its utility in a multicenter study. Methods: We prepared six recombinant ARSs: GST-Jo-1, His-PL-12, His-EJ and GST-KS expressed in Escherichia coli, and His-PL-7 and His-OJ expressed in Hi-5 cells. After confirming their antigenic activity, with the exception of His-OJ, we developed our ELISA system in which the five recombinant ARSs (without His-OJ) were mixed. Efficiency was confirmed using the sera from 526 Japanese patients with connective tissue disease (CTD) (IIM n = 250, systemic lupus erythematosus n = 91, systemic sclerosis n = 70, rheumatoid arthritis n = 75, Sjögren’s syndrome n = 27 and other diseases n = 13), 168 with idiopathic interstitial pneumonia (IIP) and 30 healthy controls collected from eight institutes. IIPs were classified into two groups; idiopathic pulmonary fibrosis (IPF) (n = 38) and non-IPF (n = 130). Results were compared with those of RNA immunoprecipitation. Results: Sensitivity and specificity of the ELISA were 97.1% and 99.8%, respectively when compared with the RNA immunoprecipitation assay. Anti-ARS antibodies were detected in 30.8% of IIM, 2.5% of non-myositis CTD, and 10.7% of IIP (5.3% of IPF and 12.3% of non-IPF). Anti-ARS-positive non-IPF patients were younger and more frequently treated with glucocorticoids and/or immunosuppressants than anti-ARS-negative patients. Conclusion: A newly established ELISA detected anti-ARS antibodies as efficiently as RNA immunoprecipitation. This system will enable easier and wider use in the detection of anti-ARS antibodies in patients with IIM and IIP.

Three Groups in the 28 Joints for Rheumatoid Arthritis Synovitis - Analysis Using More than 17,000 Assessments in the KURAMA Database.

Rheumatoid arthritis (RA) is a joint-destructive autoimmune disease. Three composite indices evaluating the same 28 joints are commonly used for the evaluation of RA activity. However, the relationship between, and the frequency of, the joint involvements are still not fully understood. Here, we obtained and analyzed 17,311 assessments for 28 joints in 1,314 patients with RA from 2005 to 2011 from electronic clinical chart templates stored in the KURAMA (Kyoto University Rheumatoid Arthritis Management Alliance) database. Affected rates for swelling and tenderness were assessed for each of the 28 joints and compared between two different sets of RA patients. Correlations of joint symptoms were analyzed for swellings and tenderness using kappa coefficient and eigen vectors by principal component analysis. As a result, we found that joint affected rates greatly varied from joint to joint both for tenderness and swelling for the two sets. Right wrist joint is the most affected joint of the 28 joints. Tenderness and swellings are well correlated in the same joints except for the shoulder joints. Patients with RA tended to demonstrate right-dominant joint involvement and joint destruction. We also found that RA synovitis could be classified into three categories of joints in the correlation analyses: large joints with wrist joints, PIP joints, and MCP joints. Clustering analysis based on distribution of synovitis revealed that patients with RA could be classified into six subgroups. We confirmed the symmetric joint involvement in RA. Our results suggested that RA synovitis can be classified into subgroups and that several different mechanisms may underlie the pathophysiology in RA synovitis.

Prognostic Significance of Anti-Aminoacyl-tRNA Synthetase Antibodies in Polymyositis/Dermatomyositis-Associated Interstitial Lung Disease: A Retrospective Case Control Study

Background In polymyositis/dermatomyositis (PM/DM), anti-aminoacyl-tRNA synthetase (ARS) antibodies are closely associated with interstitial lung disease (ILD), a frequent pulmonary complication. However, the clinical significance of anti-ARS antibodies is not well established. Objective We aimed to evaluate the clinical significance of anti-ARS antibodies in PM/DM-ILD patients. Methods Forty-eight consecutive PM/DM-ILD patients were studied retrospectively. Anti-ARS antibodies were screened by ELISA and confirmed by RNA immunoprecipitation test. Medical records, high-resolution computed tomography images, and surgical lung biopsy specimens were compared between ARS-positive (ARS group) and ARS-negative patients (non-ARS group). Results Anti-ARS antibodies were detected in 23 of 48 patients (48%). Radiologically, nonspecific interstitial pneumonia (NSIP) pattern was observed more frequently in the ARS group than in the non-ARS group (73.9% vs. 40%, P = 0.02). Pathologically, NSIP was the most frequent in both groups. Ten-year survival rate was also significantly higher in the ARS group than in the non-ARS group (91.6% vs. 58.7%, P = 0.02). Univariate Cox hazards analysis revealed that the presence of anti-ARS antibodies was associated with better prognosis (HR = 0.34, 95% CI 0.08–0.80; P = 0.01). Conclusions The presence of anti-ARS antibodies is a possible prognostic marker in patients with PM/DM-ILD.