Two novel anti-aminoacyl tRNA synthetase antibodies: Autoantibodies against cysteinyl-tRNA synthetase and valyl-tRNA synthetase.

Anti-aminoacyl-tRNA synthetase (anti-ARS) antibodies are useful for identifying a clinical subset of patients with inflammatory myopathies. Since the myositis of anti-ARS-positive patients is characterized by a unique set of non-myopathic manifestations, including interstitial lung disease, mechanic's hands, and arthralgia, the patients are classified as having anti-synthetase syndrome. Autoantibodies have been identified to eight kinds of ARSs. Of the other 12 ARSs, eight are components of the "OJ" multi-synthetase complex. Autoantibodies to the four remaining ARSs (CysARS, ValARS, SerARS, and TrpARS) have not been reported to be present in patients with inflammatory myopathies. In this study, we first screened samples from more than 300 Japanese patients majorly consisting of those with dermatomyositis (DM) by our established in-house ELISA to find autoantibodies against the four ARSs described above. Since sera from two DM patients specifically reacted to CysARS or ValARS, we determined their reactivities by immunoprecipitation (IP) with the corresponding recombinant proteins and IP-Western blotting with cellular extract. One patient had several features found in anti-synthetase syndrome, but the other did not. The clinical differences among the various anti-ARS antibodies should be explored in a future work.

Antiviral proinflammatory phenotype of monocytes in anti-MDA5 antibody-associated interstitial lung disease.

OBJECTIVE: To evaluate upstream and downstream regulators leading to macrophage activation and subsequent cytokine storm in patients with anti-melanoma differentiation-associated gene 5 (MDA5) antibody-associated interstitial lung disease (ILD). METHODS: We conducted an integrated miRNA-mRNA association analysis using circulating monocytes from 3 patients with anti-MDA5-associated ILD and 3 healthy controls and identified disease pathways and a regulator effect network by Ingenuity Pathway Analysis (IPA). The expression of relevant genes and proteins was verified using an independent validation cohort, including 6 patients with anti-MDA5-associated ILD, 5 with anti-aminoacyl tRNA synthetase antibody-associated ILD, and 6 healthy controls. RESULTS: IPA identified 26 matched pairs of downregulated miRNA and upregulated mRNAs and revealed that canonical pathways mediated by type I IFN signalling and C-C motif ligand 2 (CCL2) were responsible for the pathogenic process (P < 0.05 for all pathways). The regulatory network model identified IFN-ß; Toll-like receptors 3, 7, and 9; and PU.1 as upstream regulators, while the downstream effect of this network converged at the inhibition of viral infection. mRNA and protein expression analysis using validation cohort showed a trend towards the increased expression of relevant molecules identified by IPA in patients with anti-MDA5-associated ILD compared with those with anti-aminoacyl tRNA synthetase antibody-associated ILD or healthy controls. The expression of all relevant genes in monocytes and serum levels of CCL2 and IFN-ß declined after treatment in survivors with anti-MDA5-associated ILD. CONCLUSION: An antiviral proinflammatory network orchestrated primarily by activated monocytes/macrophages might be responsible for cytokine storm in anti-MDA5-associated ILD.

The Significance of Autoantibodies in Juvenile Dermatomyositis.

Juvenile dermatomyositis is a chronic and rare autoimmune disorder classified into the spectrum of idiopathic inflammatory myopathies. Although this entity is mainly characterized by the presence of pathognomonic cutaneous lesions and proximal muscle weakness, the clinical manifestation can be highly heterogeneous; thus, diagnosis might be challenging. Current treatment recommendations for juvenile dermatomyositis, based mainly upon case series, include the use of corticosteroids, immunomodulatory, and immunosuppressive agents. Recently, several specific autoantibodies have been shown to be associated with distinct clinical phenotypes of classic dermatomyositis. There is a need to further evaluate their relevance in the formation of various clinical features. Furthermore, while providing more personalized treatment strategies, one should consider diversity of autoantibody-related subgroups of juvenile dermatomyositis.

Description and Analysis of a Novel Subtype of the Anti-Synthetase Syndrome Characterized by Frequent Attacks of Fever and Systemic Inflammation in a Single-Center Cohort Study.

Objectives: The aim of this study was to investigate anti-synthetase syndrome (ASyS) patients who presented with recurrent episodes of fever and systemic inflammation. Methods: A retrospective cohort of Chinese ASyS patients (n=126) in our center (between January 2013 and January 2020) was included. Patients presenting with concomitant autoimmune rheumatic diseases or malignancies were subsequently excluded. The number of non-infectious fever attacks and attack frequency were recorded and calculated. Patients with two or more attacks and within the upper three quartiles of attack frequency were defined as high-inflammation group. Univariate and multivariate analyses were carried out to characterize the high-inflammation subtype. Results: Out of 113 eligible patients with an average of 5 years follow up, 25 patients were defined as the high-inflammation group (16 for anti-Jo1, 9 for anti-PL7), with an average of 1.12 attack/patient-year. Compared to low-inflammation group (0-1 attack only and a frequency lower than 0.5 attack/patient-year), the high-inflammation group had higher occurrence of fever and rapid progressive interstitial lung disease (RPILD) as the first presentation (84% vs. 21% and 40% vs. 9%, respectively, both p<0.01). Anti-PL-7 was related to the more inflammatory phenotype (p=0.014). Cumulative disease-modifying agent exposures (>=3) were much higher in the high-inflammation group (60% vs. 26%), while biological agents, i.e., rituximab and tocilizumab, showed better "drug survival" for Jo-1+ and PL-7+ ASyS patients with high inflammation, respectively, in our cohort. Conclusions: ASyS with recurrent systemic inflammatory episodes reflects a subtype of more aggressive and refractory disease in the spectrum of ASyS. Increased awareness of this subtype might lead to more appropriate management.

Dyspnea, Elevated Jugular Venous Pulse, and Lower Extremity Edema in the Setting of Interstitial Lung Disease in a Patient Who Has Undergone Liver and Kidney Transplantation.

CASE PRESENTATION: A 64-year-old man with a past medical history of alcoholic cirrhosis with resultant hepatorenal syndrome requiring kidney and liver transplantation 10 years previously sought treatment at the ED with progressive lower-extremity edema and dyspnea. After noting worsening shortness of breath and cough as an outpatient, he had been referred to a pulmonary clinic and was undergoing a workup for interstitial lung disease (ILD). He had been started on prednisone 40 mg/d after a lung biopsy 4 months before admission. He was also receiving chronic immunosuppression with tacrolimus and mycophenolate mofetil. He had noted worsening of edema since starting prednisone.

Clinical characteristics of Vietnamese patients with idiopathic inflammatory myopathies and autoantibodies to aminoacyl-transfer RNA synthetases.

OBJECTIVE: To assess clinical phenotypes of anti-aminoacyl-transfer RNA synthetases (aaRS) autoantibodies in Vietnamese patients of Kinh ethnicity with idiopathic inflammatory myopathies (IIM). METHODS: In a cross-sectional study 23 patients with anti-aaRS autoantibodies were compared to 36 patients with other myositis-specific antibodies and to 69 seronegative patients with IIM. Assessments included muscle performance, extra-muscular involvement, and disease activity according to the International Myositis Assessment and Clinical Studies (IMACS). Sera were tested by a line immunoassay (Euroline Myositis Profile 4). RESULTS: The frequency of anti-Jo-1 antibodies was 56.5%, anti-EJ antibodies 26.1%, and anti-PL-7 antibodies 17.4%, while anti-PL-12 and anti-OJ antibodies were not present in any case. All patients with anti-aaRS autoantibodies had signs of myositis. At time of investigation 22/23 patients had muscle weakness, 52.2% arthritis, 34.8% Raynaud's phenomenon, 73.9% fever, 14.3% mechanic's hands and 56.5% dysphagia. Interstitial lung disease was present in 52.2%, and pulmonary hypertension in 56.5%. The anti-aaRS autoantibody positive group had higher disease activity in the domains of skin and pulmonary disease compared to the seronegative group and had lower disease activity in skeletal disease compared to the anti-melanoma differentiation-associated protein 5-positive patients. The clinical presentation of antisynthetase syndrome was similar between the aaRS autoantibody specificities with the exception of more frequent pulmonary hypertension in anti-Jo-1 positive patients. CONCLUSIONS: Different aaRS autoantibody specificities may vary between different ethnic populations for reasons that still need to be clarified. Furthermore, the high frequency of pulmonary hypertension is noteworthy but otherwise clinical manifestations associated with aaRS autoantibodies did not differ from other ethnic populations.

Anti-MDA5 autoantibodies associated with juvenile dermatomyositis constitute a distinct phenotype in North America.

OBJECTIVE: Myositis-specific autoantibodies have defined distinct phenotypes of patients with juvenile myositis (JIIM). We assessed the frequency and clinical significance of anti-melanoma differentiation-associated gene 5 (MDA5) autoantibody-associated JIIM in a North American registry. METHODS: Retrospective examination of the characteristics of 35 JIIM patients with anti-MDA5 autoantibodies was performed, and differences from other myositis-specific autoantibody groups were evaluated. RESULTS: Anti-MDA5 autoantibodies were present in 35/453 (7.7%) of JIIM patients and associated with older age at diagnosis, and lower serum creatine kinase and aldolase levels. Patients with anti-MDA5 autoantibodies had more frequent weight loss, adenopathy, arthritis, interstitial lung disease (ILD), and less frequent falling compared with anti-transcriptional intermediary factor 1 (TIF1), anti-nuclear matrix protein 2 (NXP2) and myositis-specific autoantibody/myositis-associated autoantibody-negative patients. They had a different season of diagnosis and less frequent mechanic's hands and ILD compared with those with anti-synthetase autoantibodies. Anti-MDA5 patients received fewer medications compared with anti-TIF1, and corticosteroid treatment was shorter compared with anti-TIF1 and anti-nuclear matrix protein 2 autoantibody groups. The frequency of remission was higher in anti-MDA5 than anti-synthetase autoantibody-positive JIIM. In multivariable analyses, weight loss, arthritis and arthralgia were most strongly associated with anti-MDA5 autoantibody-positive JIIM. CONCLUSION: Anti-MDA5 JIIM is a distinct subset, with frequent arthritis, weight loss, adenopathy and less severe myositis, and is also associated with ILD. Anti-MDA5 is distinguished from anti-synthetase autoantibody-positive JIIM by less frequent ILD, lower creatine kinase levels and differing seasons of diagnosis. Anti-MDA5 has comparable outcomes, but with the ability to discontinue steroids more rapidly and less frequent flares compared with anti-TIF1 autoantibodies, and more frequent remission compared with anti-synthetase JIIM patients.

Prognosis of adult idiopathic inflammatory myopathy-associated interstitial lung disease: a retrospective study of 679 adult cases.

OBJECTIVES: Few studies have investigated the prognostic factors for idiopathic inflammatory myopathy-associated interstitial lung disease (IIM-ILD) across different clinical/serological phenotypes. METHODS: We conducted a retrospective analysis of patients diagnosed with IIM between January 2012 and December 2017. RESULTS: Of the 760 IIM cases registered, 679 adult cases were included in this study. ILD was present in 508 cases, and the presence of ILD in the clinically amyopathic DM, DM and PM groups was 92.7, 73.6 and 55.1%, respectively (P < 0.01). The prevalence of ILD in the anti-synthetase antibody (ASA)+-IIM group was higher than that in ASA--IIM group (95.2 vs 72.4%, P < 0.01); no such difference was found between the anti-histidyl-tRNA synthetase (Jo-1)+-IIM and Jo-1-ASA+-IIM groups (93.0 vs 98.5%, P > 0.05). The prevalence of ILD in the melanoma differentiation-associated protein-5 (MDA-5)+-IIM group was higher than that in MDA-5--IIM group (97.8 vs 72.1%, P < 0.01). Among adults with IIM, men with concurrent ILD, who were older than 50 years, were most likely to die. No significant difference was found in the all-cause mortality rates between DM-ILD and clinically amyopathic DM-ILD groups (33.3 vs 23%, P > 0.05), although both were higher than that in PM group (13.2%, P = 0.01 and P < 0.05, respectively). No difference was found in the all-cause mortality rates between MDA5-ASA--IM-ILD and MDA5-ASA+-IM-ILD groups (17.2 vs 12.8%, P > 0.05), and both were lower than that in MDA5+ASA--IM-ILD group (33.7%, P < 0.05). CONCLUSION: The prevalence of ILD in IIM and the prognosis of IIM-ILD patients may vary depending on the statuses of the ASA and MDA-5 antibodies.

The comparison of nailfold videocapillaroscopy findings between anti-melanoma differentiation-associated gene 5 antibody and anti-aminoacyl tRNA synthetase antibody in patients with dermatomyositis complicated by interstitial lung disease.

Dermatomyositis (DM) is frequently complicated by interstitial lung disease (ILD), which increases mortality. This study aims to elucidate the clinical significance of nailfold videocapillaroscopy (NVC) on assessing the disease activity and prognosis of DM-ILD. We compared the NVC findings between anti-melanoma differentiation-associated gene 5 (anti-MDA5) antibody-positive and anti-aminoacyl tRNA synthetase (anti-ARS) antibody-positive patients, the survival and ILD-related death groups, and examined the association of NVC findings with prognostic factors of DM-ILD. The median scores of microhemorrhage and capillary disorganization in the anti-MDA5 antibody-positive group were significantly higher than those in the anti-ARS antibody-positive group (P = 0.012 and 0.044, respectively). In contrast, the median scores of tortuous capillaries in the anti-ARS antibody-positive group were significantly higher than those in the anti-MDA5 antibody-positive group (P = 0.002). The median scores of microhemorrhage was significantly higher in the ILD-related death group than the survival group (P = 0.02). The scores of microhemorrhage, capillary disorganization, and neoangiogenesis correlated with known poor prognosis factors of DM-ILD. Additionally, the scores of microhemorrhage and capillary loss correlated significantly with the total fibrosis scores of chest high-resolution computed tomography. These findings suggest that NVC is a useful tool for assessing the disease activity and prognosis of DM-ILD.

Generation and validation of recombinant antibodies to study human aminoacyl-tRNA synthetases.

Aminoacyl-tRNA synthetases (aaRSs) have long been viewed as mere housekeeping proteins and have therefore often been overlooked in drug discovery. However, recent findings have revealed that many aaRSs have noncanonical functions, and several of the aaRSs have been linked to autoimmune diseases, cancer, and neurological disorders. Deciphering these roles has been challenging because of a lack of tools to enable their study. To help solve this problem, we have generated recombinant high-affinity antibodies for a collection of thirteen cytoplasmic and one mitochondrial aaRSs. Selected domains of these proteins were produced recombinantly in Escherichia coli and used as antigens in phage display selections using a synthetic human single-chain fragment variable library. All targets yielded large sets of antibody candidates that were validated through a panel of binding assays against the purified antigen. Furthermore, the top-performing binders were tested in immunoprecipitation followed by MS for their ability to capture the endogenous protein from mammalian cell lysates. For antibodies targeting individual members of the multi-tRNA synthetase complex, we were able to detect all members of the complex, co-immunoprecipitating with the target, in several cell types. The functionality of a subset of binders for each target was also confirmed using immunofluorescence. The sequences of these proteins have been deposited in publicly available databases and repositories. We anticipate that this open source resource, in the form of high-quality recombinant proteins and antibodies, will accelerate and empower future research of the role of aaRSs in health and disease.

High- density lipoprotein function is abnormal in idiopathic inflammatory myopathies.

OBJECTIVE: Damage to the vascular endothelium is strongly implicated in the pathogenesis of idiopathic inflammatory myopathies (IIM). Normally, high-density lipoprotein (HDL) protects the vascular endothelium from damage from oxidized phospholipids, which accumulate under conditions of oxidative stress. The current work evaluated the antioxidant function of HDL in IIM patients. METHODS: HDL's antioxidant function was measured in IIM patients using a cell-free assay, which assesses the ability of isolated patient HDL to inhibit oxidation of low-density lipoproteins and is reported as the HDL inflammatory index (HII). Cholesterol profiles were measured for all patients, and subgroup analysis included assessment of oxidized fatty acids in HDL and plasma MPO activity. A subgroup of IIM patients was compared with healthy controls. RESULTS: The antioxidant function of HDL was significantly worse in patients with IIM (n = 95) compared with healthy controls (n = 41) [mean (S.d.) HII 1.12 (0.61) vs 0.82 (0.13), P < 0.0001]. Higher HII associated with higher plasma MPO activity [mean (S.d.) 13.2 (9.1) vs 9.1 (4.6), P = 0.0006] and higher oxidized fatty acids in HDL. Higher 5-hydroxyeicosatetraenoic acid in HDL correlated with worse diffusion capacity in patients with interstitial lung disease (r = -0.58, P = 0.02), and HDL's antioxidant function was most impaired in patients with autoantibodies against melanoma differentiation-associated protein 5 (MDA5) or anti-synthetase antibodies. In multivariate analysis including 182 IIM patients, higher HII was associated with higher disease activity and DM diagnosis. CONCLUSION: The antioxidant function of HDL is abnormal in IIM patients and may warrant further investigation for its role in propagating microvascular inflammation and damage in this patient population.

Seasonal and residential clustering at disease onset of anti-MDA5-associated interstitial lung disease.

OBJECTIVES: To investigate whether the onset of polymyositis (PM)/dermatomyositis (DM)-associated interstitial lung disease (ILD) is influenced by season and residence in the context of myositis-specific autoantibodies. METHODS: For patients with PM/DM-associated ILD enrolled in a multicentre cohort, 365 and 481 patients were eligible for seasonal and geographical analysis, respectively, based on the availability of reliable clinical information. The patients were divided into three groups: (1) anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive patients, (2) anti-aminoacyl tRNA synthetase (anti-ARS) antibody-positive patients and (3) patients negative for those antibodies. Seasonality was assessed by the Rayleigh test. Distance from residence to the nearest waterfront was measured on Google Map and was compared between groups by the exact Wilcoxon rank-sum test. RESULTS: In anti-MDA5-positive patients, the disease developed more frequently in October-March (p=0.03), whereas a seasonal relationship was not found in the remaining two patient groups. Residence at disease onset in anti-MDA5-positive patients was significantly closer to the waterfront, especially to freshwater, compared with that in anti-ARS-positive or anti-MDA5-/ARS-negative patients (p=0.003 and 0.006, respectively). CONCLUSIONS: Anti-MDA5-associated ILD occurred predominantly from October to March in individuals residing near freshwater, suggesting an environmental influence on the onset of this disease subset.

Evaluation of usefulness in surfactant protein D as a predictor of mortality in myositis-associated interstitial lung disease.

OBJECTIVE: Surfactant protein D (SP-D) is considered a serum biomarker of various forms of interstitial lung disease (ILD). In this study, we examined the utility of SP-D as a predictive biomarker for mortality in patients with ILD associated with polymyositis/dermatomyositis (PM/DM) using large-scale multicentre cohort data. METHODS: We enrolled 381 patients with incident PM/DM-associated ILD in a multicentre retrospective cohort based on the availability of serum SP-D at the baseline. Demographic and clinical characteristics as well as the presence of autoantibodies to melanoma differentiation-associated gene 5 (MDA5) and aminoacyl tRNA synthetase were measured at the time of diagnosis, and follow-up survival data were collected prospectively. RESULTS: Seventy-eight patients died during the median observation period of 18 months, and the majority of patients died of ILD. The SP-D levels at baseline were significantly lower (P = 0.02) in a non-survivor subset than in a survivor subset among the entire enrolled patients. However, the SP-D levels were higher in the non-survivor subset than in the survivor subset based on the stratification by anti-MDA5-positive, anti-ARS-positive and, double-negativity, although there was an only statistically significant difference (P = 0.01) in the double-negative group. Surprisingly, the SP-D levels were within the upper limit of normal, 110 ng/mL, in 54 (87%) of 62 anti-MDA5-positive patients who died. In the double-negative group, the mortality rates were significantly higher (P = 0.002) in a subset with SP-D ≥127.6 ng/mL, the cut-off value for mortality calculated by the receiver operating characteristic curve, than the other subset. All of patients with SP-D <127.6 ng/mL survived. CONCLUSION: Serum SP-D levels behave differently among patients with stratified by anti-MDA5 antibody, anti-ARS antibody and both negativity in PM/DM-associated ILD. Its use in clinical practice should be applied with caution on the basis of the presence or absence of anti-MDA5 antibody or anti-ARS antibody.

Anti-EJ Antibody-positive Anti-synthetase Syndrome Associated with Retroperitoneal Sarcoma.

A 74-year-old man with interstitial lung disease (ILD) underwent surgical excision of a growing retroperitoneal tumor and was diagnosed with spindle cell sarcoma. Just after the surgery, skin eruption and muscle weakness emerged. Based on his symptoms and examination findings, we diagnosed him with anti-synthetase syndrome (ASS) with positive anti-glycyl-transfer ribonucleic acid synthetase antibody (anti-EJ) as paraneoplastic syndrome. Immunosuppressive treatments kept his progressing ILD stable for 21 months, although an expanding lung metastatic lesion from primary sarcoma was detected. Measurements of myositis-specific antibodies may enable the prediction of the efficacy of immunosuppressive treatments for paraneoplastic syndrome, even if the primary disease becomes progressive.

Endogenous TLR2 ligand embedded in the catalytic region of human cysteinyl-tRNA synthetase 1.

BACKGROUND: The generation of antigen-specific cytotoxic T lymphocyte (CTL) responses is required for successful cancer vaccine therapy. In this regard, ligands of Toll-like receptors (TLRs) have been suggested to activate adaptive immune responses by modulating the function of antigen-presenting cells (APCs). Despite their therapeutic potential, the development of TLR ligands for immunotherapy is often hampered due to rapid systemic toxicity. Regarding the safety concerns of currently available TLR ligands, finding a new TLR agonist with potent efficacy and safety is needed. METHODS: A unique structural domain (UNE-C1) was identified as a novel TLR2/6 in the catalytic region of human cysteinyl-tRNA synthetase 1 (CARS1) using comprehensive approaches, including RNA sequencing, the human embryonic kidney (HEK)-TLR Blue system, pull-down, and ELISA. The potency of its immunoadjuvant properties was analyzed by assessing antigen-specific antibody and CTL responses. In addition, the efficacy of tumor growth inhibition and the presence of the tumor-infiltrating leukocytes were evaluated using E.G7-OVA and TC-1 mouse models. The combined effect of UNE-C1 with an immune checkpoint inhibitor, anti-CTLA-4 antibody, was also evaluated in vivo. The safety of UNE-C1 immunization was determined by monitoring splenomegaly and cytokine production in the blood. RESULTS: Here, we report that CARS1 can be secreted from cancer cells to activate immune responses via specific interactions with TLR2/6 of APCs. A unique domain (UNE-C1) inserted into the catalytic region of CARS1 was determined to activate dendritic cells, leading to the stimulation of robust humoral and cellular immune responses in vivo. UNE-C1 also showed synergistic efficacy with cancer antigens and checkpoint inhibitors against different cancer models in vivo. Further, the safety assessment of UNE-C1 showed lower systemic cytokine levels than other known TLR agonists. CONCLUSIONS: We identified the endogenous TLR2/6 activating domain from human cysteinyl-tRNA synthetase CARS1. This novel TLR2/6 ligand showed potent immune-stimulating activity with little toxicity. Thus, the UNE-C1 domain can be developed as an effective immunoadjuvant with checkpoint inhibitors or cancer antigens to boost antitumor immunity.

MHC class I and II peptide homology regulates the cellular immune response.

Mammalian immune responses are initiated by "danger" signals--immutable molecular structures known as PAMPs. When detected by fixed, germline encoded receptors, pathogen-associated molecular pattern (PAMPs) subsequently inform the polarization of downstream adaptive responses depending upon identity and localization of the PAMP. Here, we report the existence of a completely novel "PAMP" that is not a molecular structure but an antigenic pattern. This pattern--the incidence of peptide epitopes with stretches of 100% sequence identity bound to both dendritic cell (DC) major histocompatibility (MHC) class I and MHC class II--strongly induces TH 1 immune polarization and activation of the cellular immune response. Inherent in the existence of this PAMP is the concomitant existence of a molecular sensor complex with the ability to scan and compare amino acid sequence identities of bound class I and II peptides. We provide substantial evidence implicating the multienzyme aminoacyl-tRNA synthetase (mARS) complex and its AIMp1 structural component as the key constituents of this complex. The results demonstrate a wholly novel mechanism by which T-helper (TH ) polarization is governed and provide critical information for the design of vaccination strategies intended to provoke cell-mediated immunity.

[Antisynthetase myopathy].

Inflammatory myopathies are a heterogeneous group of immune-mediated diseases that involve skeletal muscle as well as many other organs. The classification of inflammatory myopathies has been based on clinical diagnoses, pathological diagnoses, and autoantibodies, independently. Antisynthetase syndrome, characterized by myositis, interstitial lung disease, skin rash, arthropathy, and Raynaud phenomenon, is a clinical entity based on the presence of aminoacyl transfer RNA synthetase (ARS) antibodies in patients' serum. A cohort study of muscle biopsy entitled "Integrated Diagnosis Project for Inflammatory Myopathies" revealed that of 460 patients with idiopathic inflammatory myopathies, 51 (11%; female:male, 31:20) had antisynthetase myopathy. It is noted that anti-OJ antibodies, one of anti-ARS antibody subtypes, are clearly detected by RNA immunoprecipitation, but not conventional detection methods including line blot and enzyme-linked immunosorbent assays. The combined mean onset age of the patients was 60 years (range 13-85 years). There were no significant HLA-DRB1 alleles associated with anti-ARS antibodies. All patients with antisynthetase myopathy patients presented muscle limb weakness; 14 had severe weakness, 17 neck weakness, 15 dysphagia, and 15 muscle atrophy. Although patients with anti-OJ antibodies showed severe muscle weakness, the clinical presentations defined by anti-ARS antibodies were relatively homogeneous. In muscle pathology, perifascicular necrosis is a distinctive hallmark of antisynthetase myopathy. Patients with antisynthetase myopathy responded to the combination of immunosuppressive therapy, with favorable outcomes. However, interstitial lung disease, found in 41 patients, was more closely related to mortality than myositis. Antisynthetase myopathy has a distinct clinical and histological entity among idiopathic inflammatory myopathies.

Comparison of cytokine profiles between anti-ARS antibody-positive interstitial lung diseases and those with anti-MDA-5 antibodies.

INTRODUCTION/OBJECTIVES: Interstitial lung disease (ILD) is a significant cause of mortality among patients with dermatomyositis (DM) or polymyositis (PM). There are two subtypes of PM and DM often complicated with ILD: those with anti-aminoacyl-tRNA synthetase (anti-ARS) antibodies and those with anti-MDA-5-associated amyopathic DM (ADM). Our aim is to clarify the inflammatory and immunological differences between the disorders. METHODS: We retrospectively collected consecutive patients with anti-ARS-ILD and those with anti-MDA-5 antibody-positive ADM-ILD. The serum concentration of 38 cytokines was measured using a cytokine panel. The relative risks for anti-MDA-5 antibody-positive ADM-ILD were examined with univariate and multivariate logistic regression models. Spearman's rank correlation coefficient was calculated between cytokine levels and clinical parameters in the disease. Levels of cytokines were compared between anti-ARS-ILD and anti-MDA-5-positive ADM-ILD patients (alive or dead) using Dunnett's test. RESULTS: Twenty-three patients with anti-ARS-ILD and the same number of patients with anti-MDA-5-positive ADM-ILD were enrolled. The anti-MDA-5 group had poor survival (p = 0.025). Univariate logistic regression models showed that eotaxin, IL-10, IP-10, and MCP-1 were associated with the diagnosis of anti-MDA-5-positive ADM-ILD. Multivariate logistic regression models revealed that IP-10 was the most significantly associated (p = 0.001). Relationship analyses showed that IL-10 had significant positive correlations with CK (r = 0.5267, p = 0.009) and ferritin (r = 0.4528, p = 0.045). A comparison of the cytokine levels found that IP-10 was elevated in both patients who were alive and patients who had died with ADM-ILD compared with the levels in those with ARS-ILD (p = 0.003 and p = 0.001, respectively). CONCLUSIONS: Anti-MDA-5-positive ADM-ILD had poorer survival than anti-ARS-ILD. IP-10 seems to be most deeply involved in the pathophysiology of anti-MDA-5-associated ADM-ILD.Key Points• To clarify differences in the inflammatory and immunological features of anti-MDA-5-positive ADM-ILD and anti-ARS-ILD, we performed an observational study to measure serum cytokine concentrations before treatment using a multiplex immunoassay system.• Multivariate logistic regression models revealed that IP-10 was associated with the most significant relative risk for ADM-ILD with anti-MDA-5 antibodies.• Levels of IP-10 were elevated considerably in anti-MDA-5-positive survivors and nonsurvivors compared with the levels in anti-ARS patients.• These results suggest that IP-10 is the most deeply involved in the pathophysiology of anti-MDA-5-positive ADM-ILD.