anti-ARS Ab Research Articles

Serum Anti-Aminoacyl-Transfer Ribonucleic Acid Synthetase Antibody Levels Are Involved in Rheumatoid Arthritis Complicated with Interstitial Lung Disease

Objectives: A common complication in patients with rheumatoid arthritis (RA) is interstitial lung disease (ILD). Antibodies (Abs) to anti-aminoacyl-transfer ribonucleic acid synthetase (ARS) are linked to ILD in patients with idiopathic inflammatory myopathies (IIM). There have been limited studies of anti-ARS Abs in RA. In this study, we examined anti-ARS Abs in ILD in patients with RA. Methods: Anti-ARS Abs in serum from patients with RA were measured. Results: There were higher anti-ARS Ab levels in RA patients with ILD (mean ± SDM, 16.3 ± 32.3 vs. 7.4 ± 7.0 (Index), p = 5.58 × 10−12), usual interstitial pneumonia (14.4 ± 24.4 vs. 7.4 ± 7.0 [Index], p = 3.14 × 10−12), and nonspecific interstitial pneumonia (17.9 ± 37.7 vs. 7.4 ± 7.0 (Index), p = 5.07 × 10−5) compared with patients without chronic lung disease. The area under the curve (AUC) of the receiver operating characteristic curve for anti-ARS Ab was too low to allow for discrimination among RA patients with/without chronic lung disease (0.608, 95% confidence interval (CI) 0.560–0.655, p = 8.69 × 10−6). Multiple logistic regression analyses of age, smoking status, anti-ARS Abs, as well as Steinbrocker stage generated an ARS-index with a high AUC value (0.707, 95%CI 0.662–0.752, p = 2.20 × 10−19). Conclusions: Anti-ARS Abs are related to ILD pathogenesis in RA and may be a biomarker for ILD.

Clinical importance of anti-Ro52 antibody for polymyositis and dermatomyositis.

To clarify clinical features of anti-Ro52 antibody (Ab)-positive polymyositis (PM)/dermatomyositis (DM). We retrospectively examined clinical features and status of anti-Ro52 Ab in patients with PM/DM admitted at the University of Tsukuba Hospital between January 2019 and February 2023. We compared anti-Ro52 Ab-positive and -negative groups. A total of 40 patients were selected and analyzed. Median age at diagnosis was 61.5 (48.8-69.3) years and 34 cases were female. Twenty-three cases were PM and 17 cases were DM (including 6 clinically amyopathic dermatomyositis: CADM). Twenty-two cases were positive for anti-Ro52 Ab, 14 for anti-ARS Ab, and 6 for anti-MDA5 Ab. Interstitial lung disease (ILD) was detected in 29 cases, 9 of which were rapidly progressive. Glucocorticoid (GC)-resistant cardiomyopathy was detected in 6 cases, malignancy in 3 cases, and Sjögren's syndrome (SS) in 4 cases. Of the 22 anti-Ro52 Ab positive cases, only 3 were single-positive and the remaining 19 cases simultaneously had other autoantibodies. Comparing the anti-Ro52 Ab-positive and -negative groups, the frequencies of anti-ARS Ab positivity (63.6% vs. 0%), ILD (95.5% vs. 44.4%), GC-resistant cardiomyopathy (27.3% vs. 0%), concomitant use of immunosuppressants (95.5% vs. 55.6%), and levels of C-reactive protein (CRP) were significantly higher in the anti-Ro52 Ab-positive group (p<0.05). The frequencies of PM/DM, positivity of anti-MDA5 Ab, malignancies, and SS were comparable between groups. Anti-Ro52 Ab were frequently positive in PM/DM and anti-Ro52 Ab-positive patients showed significantly higher rates of anti-ARS Ab positivity and ILD, GC-resistant cardiomyopathy, concomitant use of immunosuppressants, and higher levels of CRP. Anti-Ro52 Ab may be useful as a severity marker in PM/DM.

Transcriptome Profiling of Immune Cell Types in Peripheral Blood Reveals Common and Specific Pathways Involved in the Pathogenesis of Myositis‐Specific Antibody‐Positive Inflammatory Myopathies

Idiopathic inflammatory myopathies (IIM) demonstrate characteristic clinical phenotypes depending on the myositis-specific antibody (MSAs) present. We aimed to identify common or MSA-specific immunological pathways in different immune cell types from peripheral blood by transcriptome analysis. We recruited 33 patients with IIM who were separated into the following groups: 15 patients with active disease at onset and 18 with inactive disease under treatment. All patients were positive for MSAs: anti-melanoma differentiation-associated gene 5 (MDA5) antibody (Ab) in 10 patients, anti-Mi-2 Ab in 7, and anti-aminoacyl-transfer RNA synthetase (ARS) Ab in 16. The patients were compared with 33 healthy controls. Twenty-four immune cell types sorted from peripheral blood were analyzed by flow cytometry, RNA sequencing, and differentially expressed gene analysis combined with pathway analysis. The frequencies of memory B cell types were significantly decreased in active patients, and the frequency of plasmablasts was prominently increased in active patients with anti-MDA5 Ab in comparison with healthy controls. The expression of type I interferon (IFN)-stimulated genes of all immune cell types was increased in the active, but not inactive, patients. Endoplasmic reticulum stress-related genes in all IIM memory B cells and oxidative phosphorylation-related genes in inactive IIM double negative B cells were also increased, suggesting prominent B cell activation in IIM. Furthermore, active patients with anti-MDA5 Ab, anti-Mi-2 Ab, or anti-ARS Ab were distinguished by IFN-stimulated and oxidative phosphorylation-related gene expression in plasmablasts. Unique gene expression patterns in patients with IIM with different disease activity levels and MSA types suggest different pathophysiologies. Especially, B cells may contribute to common and MSA-specific immunological pathways in IIM.

Clinical and Radiological Features of Interstitial Lung Diseases Associated with Polymyositis and Dermatomyositis.

Polymyositis and dermatomyositis are autoimmune idiopathic systemic inflammatory diseases, characterized by various degrees of muscle inflammation and typical cutaneous lesions-the latter found in dermatomyositis. The underlying pathogenesis is characterized by a high level of uncertainty, and recent studies suggest diseases may have different immunopathological mechanisms. In polymyositis, components of the cellular immune system are involved, whereas in dermatomyositis, the pathogenesis is mainly mediated by the humoral immune response. The interstitial lung disease occurs in one-third of polymyositis and dermatomyositis patients associated with worse outcomes, showing an estimated excess mortality rate of around 40%. Lung involvement may also appear, such as a complication of muscle weakness, mainly represented by aspiration pneumonia or respiratory insufficiency. The clinical picture is characterized, in most cases, by progressive dyspnea and non-productive cough. In some cases, hemoptysis and chest pain are found. Onset can be acute, sub-acute, or chronic. Pulmonary involvement could be assessed by High Resolution Computed Tomography (HRCT), which may identify early manifestations of diseases. Moreover, Computed Tomography (CT) appearances can be highly variable depending on the positivity of myositis-specific autoantibodies. The most common pathological patterns include fibrotic and cellular nonspecific interstitial pneumonia or organizing pneumonia; major findings observed on HRCT images are represented by consolidations, ground-glass opacities, and reticulations. Other findings include honeycombing, subpleural bands, and traction bronchiectasis. In patients having Anti-ARS Abs, HRCT features may develop with consolidations, ground glass opacities (GGOs), and reticular opacities in the peripheral portions; nonspecific interstitial pneumonia or nonspecific interstitial pneumonia mixed with organizing pneumonia have been reported as the most frequently encountered patterns. In patients with anti-MDA5 Abs, mixed or unclassifiable patterns are frequently observed at imaging. HRCT is a sensitive method that allows one not only to identify disease, but also to monitor the effectiveness of treatment and detect disease progression and/or complications; however, radiological findings are not specific. Therefore, aim of this pictorial essay is to describe clinical and radiological features of interstitial lung diseases associated with polymyositis and dermatomyositis, emphasizing the concept that gold standard for diagnosis and classification-should be based on a multidisciplinary approach.

Clinical manifestations and outcome of anti-aminoacyl-transfer RNA synthetase antibody and anti-melanoma differentiation-associated gene 5 antibody positive patients with interstitial lung disease.

To analyse the clinical features and risk factors of acute/subacute interstitial pneumonia (A/SIP) and death in patients with positive anti-aminoacyl-transfer RNA synthetase antibody (anti-ARS Ab) and positive anti-melanoma differentiation-associated gene 5 antibodies (anti-MDA5 Ab). Interstitial lung disease (ILD) patients with anti-ARS+ or anti-MDA5+ were recruited. Their demographics, clinical manifestations, laboratory data were collected and they were followed up for 1 year. Risk factors of A/SIP and mortality were analysed. 71 patients with anti-ARS+ ILD and 31 patients with anti-MDA5+ ILD were included. Incidence of ulcerative rash, Gottron's sign, pulmonary infection and A/SIP in the anti-MDA5+ group were significantly higher than those in the anti-ARS+ group, Creatine kinase (CK), leukocyte count, and lymphocyte count were lower, the value of serum ferritin (SF) was higher, and 12-month cumulative survival rate was lower. Advanced age, anti-MDA5+ and low immunoglobulin G (IgG) level were independent predictors of A/SIP. The decreased PaO2 and elevated SF were independent predictors for poor prognosis in A/SIP patients. Compared to anti-ARS+ group, the anti-MDA5+ group was more prone to ulcerative rash, Gottron's sign and pulmonary infection. Patients with anti-MDA5+, advanced age and decreased values of IgG were more likely to have A/SIP, while patients with A/SIP had lower incidence of myositis and arthritis. Mortality of A/SIP patients increased with higher serum ferritin level.

Plasma homocysteine levels are positively associated with interstitial lung disease in dermatomyositis patients with anti-aminoacyl-tRNA synthetase antibody.

Homocysteine is a sulfhydryl-containing amino acid that is derived from dietary methionine, and there has been increasing evidence that elevated plasma homocysteine levels are associated with increased risk of central and peripheral vascular disorders, including carotid, coronary and peripheral arterial diseases, and Raynaud's phenomenon. Recently, associations of plasma homocysteine levels with autoimmune diseases such as systemic lupus erythematodes and systemic sclerosis have been reported. However, no study analyzed the association between plasma homocysteine levels and dermatomyositis (DM). The objective of this study was to examine plasma homocysteine levels and their clinical associations in patients with DM. Plasma homocysteine levels in 28 Japanese patients with DM and 22 healthy controls were examined. We found that the plasma homocysteine levels in DM patients were significantly higher than those in healthy individuals (15.8±1.1 vs 8.5±0.5µmol/L, P<0.01). Presence of mechanic's hand, complication of interstitial lung disease (ILD), high serum Krebs von den Lungen-6 (KL-6), surfactant protein-D and creatine kinase levels, and anti-aminoacyl-tRNA synthetase (ARS) antibody (Ab) positivity were significantly more prevalent among DM patients with elevated plasma homocysteine levels. The plasma homocysteine levels in DM patients with mechanic's hand, ILD and anti-ARS Ab were significantly higher than those in DM without those features. Furthermore, the plasma homocysteine levels were positively correlated with serum KL-6 levels. These results suggest that the pathogenesis of elevated plasma homocysteine levels may be associated with ILD in DM patients, especially with anti-ARS Ab, and further examination is required.

Association of anti-aminoacyl-transfer RNA synthetase antibody and anti-melanoma differentiation-associated gene 5 antibody with the therapeutic response of polymyositis/dermatomyositis-associated interstitial lung disease.

We attempted to clarify whether the presence of anti-aminoacyl-transfer RNA synthetase antibody (anti-ARS Ab) or anti-melanoma differentiation-associated gene 5 antibody (anti-MDA5 Ab) is associated with the therapeutic response of polymyositis/dermatomyositis-associated interstitial lung disease (PM/DM-ILD). We retrospectively investigated 22 patients with PM/DM-ILD (10 positive for anti-ARS Ab and nine positive for anti-MDA5 Ab) for whom antibody analysis of conserved serum was possible. We assessed mortality in the first three months as the therapeutic response in the acute phase and compared changes in clinical data for up to one year considered as the chronic phase. We classified the clinical changes over the year into three groups: Improvement (increased % vital capacity [%VC] or diffusing capacity of the lung for carbon monoxide [%DLCO]≥10 or 15%), deterioration (decreased %VC or %DLCO≥10 or 15%), and no change (remainder of the changes). The extent of abnormality demonstrated by high-resolution computed tomography (HRCT) was scored. Positivity for anti-MDA5 Ab, but not for anti-ARS Ab, was associated with mortality in the first 3 months. Evaluation of the therapeutic response in the first year showed that positivity for the anti-ARS Ab, but not for the anti-MDA5 Ab, was associated with an improvement in %DLCO and a decline in the serum KL-6 levels. Positivity for the anti-ARS Ab or negativity for anti-MDA5 Ab was associated with a greater decrease in bronchial dilatation as seen by HRCT. Anti-ARS and anti-MDA5 Abs are associated with the therapeutic response of PM/DM-ILD.

Optimal management of interstitial lung disease associated with dermatomyositis/polymyositis: lessons from the Japanese experience

Optimal management of interstitial lung disease associated with dermatomyositis/polymyositis: lessons from the Japanese experience Kazuhiro Kurasawa,1,2 Satoko Arai2 1Center of Rheumatic Diseases, Dokkyo Medical University, Mibu, Tochigi, Japan; 2Department of Clinical Immunology, Dokkyo Medical University, Mibu, Tochigi, Japan Abstract: Interstitial lung disease (ILD) is a serious complication in dermatomyositis (DM) and polymyositis (PM). In Japan, patients with DM/PM develop acute life-threatening ILD with high frequency. Physicians in Japan have shown the following: refractory acute/subacute (A/S)-ILD is not a rare complication in DM and amyopathic DM (ADM); anti-anti-melanoma differentiation-associated gene 5 (anti-MDA5) antibody (Ab) is closely related to A/S-ILD with poor outcomes in DM/ADM; and poor prognostic factors in A/S-ILD in DM/PM are ADM, DM with low creatine kinase elevation, positivity for anti-MDA5 Ab, serum ferritin elevation, and consolidation with ground-glass opacities on high-resolution computed tomography. There are subtypes in DM/PM-ILD: refractory DM/ADM A/S-ILD positive for anti-MDA5 Ab with poor prognosis; DM A/S-ILD with glucocorticoid (GC) resistance; PM A/S-ILD with GC sensitivity; chronic ILD positive for anti-aminoacyl-tRNA-synthetases (anti-ARS) Abs with GC responsiveness; and C-ILD negative for anti-ARS Abs. For patients with A/S-ILD with poor prognosis, initial combination therapy with cyclosporine and cyclophosphamide in addition to GC has been developed, which rescues 50%&ndash;80% of the patients, although elucidation of the efficacy of the combination therapy is required. A/S-ILD with potentially fatal outcomes is found worldwide, not only in Japan. Clinicians caring for patients with DM/PM should be cautious when dealing with A/S-ILD and treat the patients based on clinical subtypes. Keywords: interstitial lung disease, dermatomyositis, polymyositis, management, cyclosporine, cyclophosphamide

SAT0223 The Onsets of Myositis with Myositis-Specific Autoantibodies (MSAS) are Associated With The Seasons.

BackgroundPolymyositis (PM) and dermatomyositis (DM) are systemic connective tissue diseases, and a number of autoantibodies (Abs) are detected in patient sera, some of which are myositis specific. Moreover, MSAs are...

Common and Distinct Clinical Features in Adult Patients with Anti-Aminoacyl-tRNA Synthetase Antibodies: Heterogeneity within the Syndrome

ObjectiveTo identify similarities and differences in the clinical features of adult Japanese patients with individual anti-aminoacyl-tRNA synthetase antibodies (anti-ARS Abs).MethodsThis was a retrospective analysis of 166 adult Japanese patients with anti-ARS Abs detected by immunoprecipitation assays. These patients had visited Kanazawa University Hospital or collaborating medical centers from 2003 to 2009.ResultsAnti-ARS Ab specificity included anti-Jo-1 (36%), anti-EJ (23%), anti-PL-7 (18%), anti-PL-12 (11%), anti-KS (8%), and anti-OJ (5%). These anti-ARS Abs were mutually exclusive, except for one serum Ab that had both anti-PL-7 and PL-12 reactivity. Myositis was closely associated with anti-Jo-1, anti-EJ, and anti-PL-7, while interstitial lung disease (ILD) was correlated with all 6 anti-ARS Abs. Dermatomyositis (DM)-specific skin manifestations (heliotrope rash and Gottron’s sign) were frequently observed in patients with anti-Jo-1, anti-EJ, anti-PL-7, and anti-PL-12. Therefore, most clinical diagnoses were polymyositis or DM for anti-Jo-1, anti-EJ, and anti-PL-7; clinically amyopathic DM or ILD for anti-PL-12; and ILD for anti-KS and anti-OJ. Patients with anti-Jo-1, anti-EJ, and anti-PL-7 developed myositis later if they had ILD alone at the time of disease onset, and most patients with anti-ARS Abs eventually developed ILD if they did not have ILD at disease onset.ConclusionPatients with anti-ARS Abs are relatively homogeneous. However, the distribution and timing of myositis, ILD, and rashes differ among patients with individual anti-ARS Abs. Thus, identification of individual anti-ARS Abs is beneficial to define this rather homogeneous subset and to predict clinical outcomes within the “anti-synthetase syndrome.”

Analysis of dermatomyositis‐specific autoantibodies and clinical characteristics in Japanese patients

Dermatomyositis (DM) is an idiopathic systemic inflammatory disease that is often accompanied by interstitial lung disease (ILD) or internal malignancy. New autoantibodies, anti-clinically amyopathic dermatomyositis 140 (anti-CADM-140) antibody (Ab) and anti-155/140 Ab, as well as anti-aminoacyl-tRNA synthetase (anti-ARS) Ab and anti-Mi-2 Ab, have been discovered and their utility indicated. However, the association between these autoantibodies and the clinical characteristics of DM is not fully understood, and it is unclear whether anti-155/140 Ab is "specific" to DM patients with internal malignancy. Therefore, we analyzed 55 DM patients and 18 non-DM patients with malignancy to evaluate the clinical characteristics, especially skin manifestations, in association with DM-specific autoantibodies detected by immunoprecipitation. Six patients (11%) had anti-CADM-140 Ab, nine (16%) had anti-155/140 Ab, eight (15%) had anti-ARS Ab and six (11%) had anti-Mi-2 Ab. The frequency of DM patients positive for any type of autoantibody was 53%. Among the 20 DM patients with ILD, three (15%) had both anti-CADM-140 Ab and rapidly progressive ILD, and required intensive therapy (P < 0.05). ILD found in anti-ARS Ab-positive patients did not progress rapidly. The prevalence of muscle involvement in patients with anti-CADM-140 Ab was 83%. Among the 18 DM patients with internal malignancy, four (22%) had anti-155/140 Ab, and internal malignancy was found in four cases (44%) of nine anti-155/140 Ab-positive patients. None of the non-DM patients with malignancy were positive for anti-155/140 Ab. In conclusion, the results of the present study indicate that anti-155/140 Ab is specific to DM patients with internal malignancy and that we may be able to predict prognosis of ILD and the presence of malignancy to some extent, suggesting that examination of autoantibodies in DM patients is clinically very useful. However, further investigation is needed because several findings differ from those of previous reports.

Structural Requirements for a Specificity Switch and for Maintenance of Affinity Using Mutational Analysis of a Phage-Displayed Anti-Arsonate Antibody of Fab Heavy Chain First Complementarity-Determining Region

We previously showed that a single mutation at heavy (H) position 35 of Abs specific for p-azophenylarsonate (Ars) resulted in acquisition of binding to the structurally related hapten p-azophenylsulfonate (Sulf). To explore the sequence and structural diversity of the H chain first complementarity-determining region (HCDR1) in modulating affinity and specificity, positions 30-36 in Ab 36-65 were randomly mutated and expressed as Fab in a bacteriophage display vector. Ab 36-65 is germline encoded, lacking somatic mutations. Following affinity selection on Sulf resins, 55 mutant Fab were isolated, revealing seven unique HCDR1 sequences containing different amino acids at position H:35. All Fab bound Sulf, but not Ars. Site-directed mutagenesis in a variety of HCDR1 sequence contexts indicates that H:35 is critical for hapten specificity, independent of the sequence of the remainder of HCDR1. At H:35, Asn is required for Ars specificity, consistent with the x-ray crystal structure of the somatically mutated anti-Ars Ab 36-71, while Sulf binding occurs with at least seven different H:35 residues. All Sulf-binding clones selected following phage display contained H:Gly33, observed previously for Ars-binding Abs that use the same germline V(H) sequence. Site-directed mutagenesis at H:33 indicates that Gly plays an essential structural role in HCDR1 for both Sulf- and Ars-specific Abs.

Contribution of heavy chain junctional amino acid diversity to antibody affinity among p-azophenylarsonate-specific antibodies.

We showed previously that heavy chain gene junctional amino acid differences among unmutated p-azophenylarsonate (Ars) Abs that share a unique gene segment combination encoding these V regions, termed "canonical," alter affinity. To determine the contribution of junctional amino acid differences to binding, we introduced, by site-directed mutagenesis, various amino acids at position 100 and/or 107 (sequential numbering) into the unmutated Ab 36-65. Among 22 mutant Abs, 15 preserved or showed increased Ars binding (1-to 12.9-fold increase) relative to Ab 36-65, while 7 Abs exhibited lower affinity (< or = 0.5-fold). As much as a 150-fold difference in Ars binding was observed between 2 Abs with different sets of junctions (Asn100/Tyr107 and Val100/Lys107). Thus, amino acid replacements at D gene junctions can produce changes in affinity greater than those for any V region somatic mutation observed thus far in vivo among anti-Ars Abs and, potentially, can result in preferential selection of Abs containing certain junctions during affinity maturation. We combined five different junctional residue pairs with mutations at H chain positions 58 and 59 that are known to be recurrent in vivo and are associated with increased Ars affinity. The mutant Abs all showed increased affinity, indicating that despite variation in D gene junctions of Ars-binding canonical Abs, the combined mutations are additive for enhancement of Ars affinity. These additive effects reflect the "adaptability" of the canonical gene segment combination in sustaining somatic mutations leading to affinity maturation.

A single engineered amino acid substitution changes antibody fine specificity.

During the acquisition of humoral immunity, the process of somatic hypermutation introduces nucleotide substitutions into expressed antibody (Ab) V region genes. Studies employing in vitro mutagenesis have shown that recurrent mutations observed in vivo often enhance the affinity of the target Ab for Ag. Here we show that a single amino acid replacement at position 35 in the H chain of an unmutated Ab with specificity for p-azophenylarsonate (Ars) confers specificity for the structurally related hapten p-azophenylsulfonate (Sulf) while abolishing specificity for Ars. The mutant Ab binds Sulf with an affinity characteristic of Ab produced by memory B cells. The same mutation in the somatically mutated anti-Ars Ab 36-71, for which the Fab crystal structure is known, resulted in a significant shift in fine specificity from Ars to Sulf. Examination of the crystal structure suggests that the specificity change is caused by a decrease in binding site size and/or new hydrogen bond geometry. Because the mutation at position 35 had been observed in somatically mutated Ab elicited by immunization with Ars followed by Sulf, the results confirm that somatic mutation in vivo can alter Ab specificity. The results also support the potential of Ab engineering to alter antigenic specificity.

Kinetics of Ig VH region gene expression: Allotypic and idiotypic specificities of anti- p-azophenylarsonate antibodies produced by al-suppressed a1a3 rabbits

The amount of anti- p-azophenylarsonate (anti-Ars‡) antibodies produced by al-suppressed a 1 a 3 heterozygous rabbits was similar to the amount produced by nonsuppressed a 1 a 3 rabbits. However, when the al allotype emerged from suppression, the previously observed preferential expression of the al allotype for these antibodies was not restored: the al anti-Ars Ab produced in these rabbits remained very low. These observations suggest that the establishment of clones of the nonsuppressed-a3 allotype early in the immune response prevented the preferential expression of al anti-Ars Ab later on. By radioimmunoprecipitation, the kinetics of the idiotypic specificities of the anti-Ars antibodies were studied, along with the VH a locus allotypic specificities, from two rabbits. The idiotype of the al anti-Ars Ab produced, after the emergence of the al allotype from suppression, appeared to be different from the a3 anti-Ars Ab produced in the same rabbit, rabbit R2-3. In a second rabbit, R3, producing exclusively anti-Ars Ab of the a3 allotype, however, two transitions in idiotype expression were observed; the first idiotype disappeared for a period of about 30 weeks, and then reappeared. This transition in idiotypes may reflect a mechanism of autoregulation, that requires further investigation.