Myositis-associated Autoantibodies Research Articles

Myositis‐specific/associated autoantibodies as diagnostic keys and disease drivers

AbstractBackgroundMyositis‐specific autoantibodies (MSAs) and myositis‐associated autoantibodies (MAAs) have emerged as crucial biomarkers in idiopathic inflammatory myopathies (IIMs).MethodsThis review synthesizes recent research on MSAs and MAAs in various IIM subtypes.ResultsSpecific autoantibodies correlate with distinct clinical manifestations and pathological features. For example, anti‐MDA5 antibodies are linked to rapidly progressive interstitial lung disease, while anti‐TIF1‐γ antibodies are associated with increased malignancy risk in adult dermatomyositis. Animal models have demonstrated the pathogenic potential of certain antibodies, such as anti‐TIF1‐γ, anti‐SRP, and anti‐HMGCR, in inducing experimental myositis.ConclusionsUnderstanding the roles of MSAs and MAAs is crucial for elucidating disease mechanisms, developing targeted therapies, and improving patient outcomes. Further research is needed to fully characterize their functional implications and explore their potential as biomarkers for disease activity, prognosis, and treatment response.

52743 Clinical associations of myositis-specific and myositis-associated autoantibodies in a multi-ethnic Asian cohort with dermatomyositis: A retrospective single-center study

52743 Clinical associations of myositis-specific and myositis-associated autoantibodies in a multi-ethnic Asian cohort with dermatomyositis: A retrospective single-center study

Advances in Juvenile Dermatomyositis: Pathophysiology, Diagnosis, Treatment and Interstitial Lung Diseases-A Narrative Review.

Juvenile idiopathic inflammatory myopathy (JIIM) is a rare systemic autoimmune disease characterized by skeletal muscle weakness with or without a skin rash. Juvenile dermatomyositis (JDM) is the most common subtype of JIIM, accounting for 80% of JIIM. Recent studies identified several myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs). Each MSA or MAA is associated with distinct clinical features and outcomes, although there are several differences in the prevalence of MSA/MAA and autoantibody-phenotype relationships between age and ethnic groups. Histopathological studies have revealed critical roles of type I interferons and vasculopathy in the development of JDM. Serological classification mostly corresponds to clinicopathological classification. Novel therapeutic agents, such as biologics and Janus kinase inhibitors (JAKi), have been developed; however, to date, there is a lack of high-level evidence. As advances in treatment have reduced the mortality rate of JIIM, recent studies have focused on medium- and long-term outcomes. However, rapidly progressive interstitial lung disease (RP-ILD) remains a major cause of death in anti-melanoma differentiation gene 5 autoantibody-positive JDM. Early diagnosis and intervention using a multi-drug regimen is critical for the treatment of RP-ILD. Rituximab and JAKi may reduce mortality in patients with JDM-associated RP-ILD refractory to conventional therapy.

Prevalence and Clinical Implications of Autoantibodies in Juvenile Dermatomyositis: A Single-Center Experience From India.

​​This study aimed to characterize the profile of myositis-specific and myositis-associated autoantibodies (MSAs/MAAs) in an Indian cohort of juvenile dermatomyositis (JDM) patients and correlate them with clinical features and outcomes. Forty-three children diagnosed with JDM were enrolled for this observational study. Clinical details (presentation, course, and outcome) were noted in a predesigned proforma. Serum samples were tested for 16 MSAs/MAAs by line immunoassay. MSAs/MAAs were correlated with clinical features and outcome (defined as a complete clinical response [≥6 months' disease inactivity on medication] or complete remission [≥6 months' inactivity off all drugs]). Thirty-five subjects (81.4%) had at least 1 MSA/MAA detected. The most common antibodies were anti-NXP2 (n = 13, 30.2%), anti-TIF1γ (n = 10, 23.2%), and anti-MDA-5 (n = 8, 18.6%). No patient had anti-Ku, anti-Pm Scl-100, anti-PL-12, anti-EJ, anti-OJ, or anti-Ro52. Thirty-two patients (74.4%) attained a complete clinical response over a median follow-up duration of 14 months, among which 6 (13.9%) achieved complete remission over a median follow-up duration of 30 months. Anti-TIF1γ was associated with younger age at onset (≤3 years) (odds ratio [OR], 6.25; 95% confidence interval [CI], 1.15-34.12; p = 0.034) and disease flares after attaining complete response (OR, 10.18; 95% CI, 1.64-70.93; p = 0.013). Patients with anti-NXP2 had higher odds of severe muscular weakness (OR, 3.73; 95% CI, 0.95-14.59; p = 0.058) and truncal weakness (OR, 3.89; 95% CI, 0.97-15.64; p = 0.056). One child with anti-MDA-5 positivity had interstitial lung disease. We found no association between the MSA/MAA profile and the achievement of complete clinical response or remission. MSAs/MAAs were identified in 81% of children with JDM in our study, which is higher than most other studies. The most frequently observed antibodies displayed a pattern consistent with other studies. Anti-TIF1γ was associated with a younger age at onset and disease flares even after attaining a complete clinical response. Anti-NXP2 had higher odds of severe muscular weakness. These observations suggest consistency in certain phenotypic associations observed across geographic boundaries.

Management and outcomes of interstitial lung disease associated with anti-synthetase syndrome: A systematic literature review.

Anti-synthetase syndrome (ASS) is a chronic autoimmune condition, with interstitial lung disease (ILD) being a key feature. This systematic literature review (SLR; CRD42023416414) aimed to summarise treatments and outcomes of ILD associated with ASS (ASS-ILD). Databases were searched for articles discussing ASS-ILD management and outcomes, published 1946-September 2023.Screening and data-extraction were performed by two reviewers. Meta-analysis, using a random effects model, and paired t-tests, were undertaken where appropriate to evaluate post-treatment-change in Pulmonary Function Tests (PFT). Ten articles were included, comprising 514 patients: 67.8% female, mean age 52.4years (SD4.6). Baseline high-resolution computed tomography was documented in 447 patients (86.9%); the most common pattern was non-specific interstitial pneumonia (n = 220; 49.2%). The most common myositis-associated autoantibody was anti-Jo1 (48%) with 27.8% having associated anti-Ro52 antibodies.Pooled estimates, after meta-analysis, for baseline Forced Vital Capacity (FVC) was 60.8% predicted (SE 2.1), and Diffusion Capacity of Lungs for Carbon Monoxide (DLco) was 49.8% (SE 3.5). After one-year, pooled improvement in FVC was 14.1% from baseline (SE 3.1) and in DLco was 15.1% (SE 2.8). Paired t-test demonstrated significant overall improvement in FVC (p = 0.007) and DLco (p = 0.002).Patients receiving RTX had 12.2% improvement in FVC and 2.9% increase in DLco at one-year; for patients receiving CYC, there was 17% improvement and 6.3% increase, respectively. 28 deaths were reported. Our SLR, the first to summarise management and outcomes of ASS-ILD, found no conclusive difference between effectiveness of treatments. More robust trials are required to reduce morbidity and mortality resulting from ASS-ILD.

Clinically amyopathic dermatomyositis: Clinical, laboratory, and histopathological features.

Despite the advancements in the categorization of clinically amyopathic dermatomyositis (CADM), the classification and diagnosis of its subtypes are still challenging. The aim of our study was to describe the clinicopathological features of CADM and assess the differences between amyopathic dermatomyositis (ADM) and hypomyopathic dermatomyositis (HDM). This retrospective study included 43 patients with CADM diagnosed at our institution from 2016 to 2020. Patients were subclassed into ADM (n = 30) and HDM (n = 13) groups to assess their clinicopathological differences. All included patients had characteristic cutaneous manifestations of dermatomyositis; 67.4% had myositis-associated auto-antibodies, including ANA (32.6%), RNP (14.0%), anti-Ro52 (9.3%), anti-p155/140 (7.0%), rheumatoid factor (7.0%), anti-NXP-2 (4.7%), anti-MDA5 (2.3%), and anti-Jo-1 (2.3%) antibodies. One patient had associated interstitial lung disease, and another patient had oral squamous cell carcinoma. The histopathological findings included mucin deposition (69.8%), telangiectasia (65.1%), lymphocytic infiltrate (48.8%), vacuolar interface dermatitis (46.5%), and epidermal atrophy (14.0%). Compared to patients with HDM, ADM patients were significantly less likely to have epidermal atrophy, 3.3% versus 38.5% (p = 0.006), and more likely to have mucin deposition, 80.0% versus 46.2% (p = 0.028). We described the clinicopathological features of CADM and highlighted the distinctions between ADM and HDM dermatopathologic findings. This information may prove helpful in diagnosing ambiguous lesions.

Myositis-specific and Myositis-associated Autoantibodies in Saudi Patients

Myositis-specific and Myositis-associated Autoantibodies in Saudi Patients

Myositis-associated interstitial lung disease

Introduction/ObjectiveTo review the epidemiology, general clinical aspects and diagnosis, impact on morbidity and mortality, and general treatment approaches for myositis-associated ILD. Materials and methodsThe relevant literature was reviewed. ResultsThe clinical, radiographic, and histopathological features of interstitial lung disease (ILD) in idiopathic inflammatory myopathies (IIM) are similar to idiopathic ILD. Patients with a known diagnosis of myositis require prompt clinical evaluation including the determination of myositis-associated autoantibodies. Patients possessing autoantibodies associated with ILD or those with any pulmonary symptoms should undergo a pulmonary function test and high-resolution CT (HRCT) scanning of their lungs. ConclusionDespite the lack of placebo-controlled trials, systemic glucocorticoids are considered the mainstay of initial treatment of myositis-associated ILD. Glucocorticoid-sparing agents are often concomitantly administered, particularly in patients with severe disease. The first-line conventional immunosuppressive drugs include either mycophenolate mofetil or azathioprine. If these agents fail or if the pulmonary features are severe or rapidly progressive, then more aggressive immunosuppressive or immunomodulatory therapy including cyclophosphamide, tacrolimus or cyclosporine, rituximab, IVIg, or tofacitinib can be considered. Further investigations are required to assess the role of novel therapies in the treatment of myositis-associated ILD.

Myositis-Associated Autoantibodies in Patients With Juvenile Myositis Are Associated With Refractory Disease and Mortality.

Myositis-associated autoantibodies (MAAs) have been associated with overlap myositis, certain disease manifestations such as interstitial lung disease (ILD), and worse prognosis in the idiopathic inflammatory myopathies. MAAs overall remain largely uncharacterized in patients with juvenile-onset myositis. Moreover, it is unknown whether the number of MAAs is associated with disease severity. Patients with juvenile myositis in cross-sectional natural history studies who underwent testing for myositis autoantibodies were included. Demographics, myositis autoantibodies, clinical characteristics, medications received, and outcomes of those with and without MAAs were compared. Multivariable logistic regression was performed to determine whether the number of MAAs detected was associated with severe disease features. Among 551 patients, 36% had an MAA and 13% had more than one MAA. Among those who were MAA positive, there was a higher frequency of overlap myositis (18% vs 5.9%, P < 0.001). MAA positivity was associated with certain clinical features, including Raynaud phenomenon (odds ratio [OR] 2.44, 95% confidence interval [CI] 1.41-4.28) and ILD (OR 3.43, 95% CI 1.75-6.96), as well as a chronic disease course (OR 1.72, 95% CI 1.10-2.72) and mortality (OR 3.76, 95% CI 1.72-8.43). The number of MAAs was also associated with mortality (OR 1.83, 95% CI 1.16-2.86). MAAs were prevalent in a large cohort of patients with juvenile myositis. ILD, refractory disease, and mortality were associated with MAA positivity. Prospective studies are needed to determine whether early detection of MAAs may lead to improved outcomes for patients with juvenile myositis.

Myositis Autoantibody Profiles and Clinical Significance in Patients with Inflammatory Myopathies in Southwest China.

The purpose of this study is to analyze the distribution of myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs) in patients with idiopathic inflammatory myopathies (IIMs) in southwest China and to explore the relevance between each subtype, each clinical feature, and to explore the relevance between the laboratory indexes. For this study, 200 patients with IIMs were tested for myositis autoantibodies. Clinical manifestations and laboratory metrics were collected and the correlations between autoantibodies and clinical phenotypes were analyzed. MSAs were found in 73.5% of the patients. The most frequently MSAs were anti-MDA5 (26.8%), followed by anti-ARS (18.5%). Anti-Ro52 was the most prevalent in MAAs (46.2%). Interstitial lung disease (ILD) and arthralgia were more frequent in anti-MDA5 and anti-Jo-1 positive groups (each p < 0.05). Anti-TIF1-γ and anti-NXP2 were associated with dysphagia (each p < 0.05). Different antibody subtypes were associated with laboratory indicators of response to muscle damage and immune status. Logistic regression showed that anti-MDA5 and anti-Jo-1 were independent risk factors for ILD (OR = 4.542, p = 0.004; OR = 4.290, p = 0.018, respectively) and arthralgia (OR = 7.856, p = 0.000; OR = 5.731, p = 0.004, respectively), whereas anti-TIF1-γ and anti-NXP2 were independent risk factors for dysphagia (OR = 4.521, p = 0.009; OR = 6.889, p = 0.017, respectively). Different antibody subtypes were associated with specific clinical features. Anti-MDA5 and anti-Jo-1 were independent risk factors for ILD and arthralgia. Anti-TIF1-γ and anti-NXP2 were independent risk factors for dysphagia.

Clinical features of anti-SAE1 antibody-positive myositis and interstitial lung disease: a multicenter, retrospective study in Taiwan.

The clinical characteristics of patients positive for anti-small ubiquitin-like modifier 1-activating enzyme subunit 1 (SAE1) antibodies and diagnosed with idiopathic inflammatory myopathies (IIMs) vary across different cohorts and ethnicities, particularly concerning interstitial lung disease (ILD). We aimed to assess the clinical utility of the line immunoblot assay (LIA) in detecting anti-SAE1 autoantibodies and evaluate the clinical relevance and chronology of ILD development in relation to SAE1 autoantibody positivity among Taiwanese patients. We retrospectively conducted a population-based cohort analysis involving 6,496 patients who visited Chang Gung Memorial Health System across Taiwan from May 2018 to December 2021. Patients were assayed for myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs) using the LIA method, and the antinuclear antibody (ANA) indirect immunofluorescence (IIF) method was used to evaluate ANA patterns. Of these, 70 SAE1-positive patients (1.08%) were included and followed up until December 2023. Associations with clinical characteristics and final diagnosis, particularly ILD, were assessed. Among the 70 SAE1-positive patients, 10 (14.3%) were strongly positive and 60 (85.7%) were weakly positive. In the strong positive group, 70% (7/10) were diagnosed with IIM, with most (5/7) showing a concordant ANA IIF pattern (speckled type). Six patients presented ILD either before (1/6) or after (5/6) IIM diagnosis; the majority (4/6) were classified as organizing pneumonia. The remaining 30.0% (3/10) had connective tissue disease (CTD) other than IIM without detectable ILD during follow-up, and none demonstrated a concordant ANA IIF pattern. In the weakly positive group, only 5.0% (3/60) had IIM and 3.3% (2/60) had ILD. The positive predictive value for strong positive SAE1 autoantibodies in diagnosing IIM was significantly higher than for weak positives (70.0% vs. 5.0%; p < 0.001). The study suggests that strong positive SAE1 autoantibodies detected via LIA are more closely associated with IIM compared to weak positive results. A high prevalence of ILD was observed among strong positive Taiwanese patients, indicating the need for prompt screening. Patients with weak positive or discordant ANA IIF results may represent false positives with a lower ILD risk.

Autoantibody evaluation in idiopathic inflammatory myopathies.

Idiopathic inflammatory myopathies (IIM), generally referred to as myositis is a heterogeneous group of diseases characterized by muscle inflammation and/or skin involvement, diverse extramuscular manifestations with variable risk for malignancy and response to treatment. Contemporary clinico-serologic categorization identifies 5 main clinical groups which can be further stratified based on age, specific clinical manifestations and/or risk for cancer. The serological biomarkers for this classification are generally known as myositis-specific (MSAs) and myositis-associated antibodies. Based on the use of these antibodies, IIM patients are classified into anti-synthetase syndrome, dermatomyositis, immune-mediated necrotizing myopathy, inclusion body myositis, and overlap myositis. The current classification criteria for IIM requires clinical findings, laboratory measurements, and histological findings of the muscles. However, the use MSAs and myositis-associated autoantibodies as an adjunct for disease evaluation is thought to provide a cost-effective personalized approach that may not only guide diagnosis but aid in stratification and/or prognosis of patients. This review provides a comprehensive overview of contemporary autoantibodies that are specific or associated myositis. In addition, it highlights possible pathways for the detection and interpretation of these antibodies with limitations for routine clinical use.

Myositis-associated interstitial lung disease

Introduction/ObjectiveTo review the epidemiology, general clinical aspects and diagnosis, impact on morbidity and mortality, and general treatment approaches for myositis-associated ILD. Materials and methodsThe relevant literature was reviewed. ResultsThe clinical, radiographic, and histopathological features of interstitial lung disease (ILD) in idiopathic inflammatory myopathies (IIM) are similar to idiopathic ILD. Patients with a known diagnosis of myositis require prompt clinical evaluation including the determination of myositis-associated autoantibodies. Patients possessing autoantibodies associated with ILD or those with any pulmonary symptoms should undergo a pulmonary function test and high-resolution CT (HRCT) scanning of their lungs. ConclusionDespite the lack of placebo-controlled trials, systemic glucocorticoids are considered the mainstay of initial treatment of myositis-associated ILD. Glucocorticoid-sparing agents are often concomitantly administered, particularly in patients with severe disease. The first-line conventional immunosuppressive drugs include either mycophenolate mofetil or azathioprine. If these agents fail or if the pulmonary features are severe or rapidly progressive, then more aggressive immunosuppressive or immunomodulatory therapy including cyclophosphamide, tacrolimus or cyclosporine, rituximab, IVIg, or tofacitinib can be considered. Further investigations are required to assess the role of novel therapies in the treatment of myositis-associated ILD.

Detection of Myositis Autoantibodies by Multi-Analytic Immunoassays in a Large Multicenter Cohort of Patients with Definite Idiopathic Inflammatory Myopathies.

The usefulness of myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs) for the assessment of idiopathic inflammatory myopathies (IIMs) is acknowledged, but laboratory standardization remains a challenge. We detected MSAs/MAAs by multi-analytic line immunoassay (LIA) and particle-based multi-analyte technology (PMAT) in a multicenter cohort of patients with IIMs. We tested the sera from 411 patients affected with definite IIM, including 142 polymyositis (PM), 147 dermatomyositis (DM), 19 cancer-associated myositis, and 103 overlap myositis syndrome (OM), and from 269 controls. MSAs/MAAs were determined by 16Ags LIA in all sera, and anti-HMGCR by ELISA in 157/411 IIM sera and 91/269 control sera. The analytical specificity of LIA/HMGCR ELISA was compared with that of PMAT in 89 MSA+ IIM sera. MSAs/MAAs were positive in 307/411 (75%) IIM patients and 65/269 (24%) controls by LIA (Odds Ratio 9.26, 95% CI 6.43-13.13, p < 0.0001). The sensitivity/specificity of individual MSAs/MAAs were: 20%/100% (Jo-1), 3%/99.3% (PL-7), 4%/98.8% (PL-12), 1%/100% (EJ), 0.7%/100% (OJ), 9%/98% (SRP), 5.6%/99.6% (TIF1γ), 4.6%/99.6% (MDA5), 8%/96% (Mi-2), 1.5%/98% (NXP2), 1.7%/100% (SAE1), 4%/92% (Ku), 8.5%/99% (PM/Scl-100), 8%/96% (PM/Scl-75), and 25.5%/79% (Ro52). Anti-HMGCR was found in 8/157 (5%) IIM patients and 0/176 (0%) controls by ELISA (p = 0.007). Concordance between LIA/HMGCR ELISA and PMAT was found in 78/89 (88%) samples. Individual MSAs detected by LIA were associated with IIM subsets: Jo-1 with PM and OM, PL-12 with OM, Mi-2, TIF1γ, and MDA5 with DM, SRP with PM, and PM/Scl-75/100 with OM (p < 0.001 for all). Since MSAs are mostly mutually exclusive, multi-specific antibody profiling seems effective for a targeted clinical-serologic approach to the diagnosis of IIMs.

Anti-SRP antibody-associated necrotizing myopathy: 2 clinical cases

Necrotizing myopathies are a subtype of autoimmune myopathies characterized by muscle fiber necrosis with minimal infiltration by inflammatory cells on muscle biopsy. This group of myopathies is defined by flaccid palsies due to prima‑ ry skeletal muscle damage as well as extramuscular manifestations such as fever, rash, arthritis, Raynaud’s syndrome and interstitial lung disease. The presence of anti-SRP antibodies is associated with rapidly progressive refractory myositis predominantly affecting limb muscles and axial muscles.Objective of the work is to analyze the course of severe, refractory to several lines of immunosuppressive therapies anti-SRP associated necrotizing myopathy and to highlight an adequate treatment regime.Necrotizing myopathy was suspected in patients aged 39 and 56 years with rapidly progressive flaccid tetraparesis on the basis of clinical and anamnestic data, the results of needle electromyography and muscle magnetic resonance imaging, as well as the analysis of myositis-specific and myositis-associated autoantibodies. In both cases, a rapid development of atrophies, marked muscle weakness in the limbs, without involvement of the bulbar musculature, was observed. To achieve effective control of the disease progression, several lines of therapy were required: glucocorticosteroids, intravenous immunoglobulins, methotrexate and rituximab. Our observations are consistent with those in the literature.Our observations illustrate the clinical course of severe myopathy associated with anti-SRP antibodies. Early initiation of aggressive immunosuppression is crucial to control the disease progression. Treatment and rehabilitation allow achieving significant improvement of the patient’s condition.

The Role of Myositis-Specific and Myositis-Associated Autoantibodies and the Activation of Type I Interferon Pathway in the Generation of Clinical Phenotypes of Inflammatory Myopathies.

Idiopathic inflammatory myopathies (IIMs) are a group of heterogeneous autoimmune diseases with a prevalence of 20 cases per 100000 of population. Despite their diversity, IMMs are characterised by several common clinical features such as muscle inflammation, proximal muscle weakness, abnormal electromyography and/or muscle biopsy. Over the last years, it has been increasingly recognised that an array of autoantibodies known as myositis-specific antibodies (MSAs) and myositis-associated antibodies (MAAs) are associated with distinct clinical phenotypes and diverse prognosis. Although the exact underlying mechanism of IIMs is not fully understood, accumulating data suggest that the activation of type I interferon pathway plays a central role in disease development. Previous studies have reported the upregulation of type I interferon (IFN) induced genes in peripheral blood and muscle biopsies derived from myositis patients. Given the heterogeneity of inflammatory myopathies along with the central role of type I IFN pathway in disease pathogenesis, the aim of the current study is to elucidate the link between distinct clinical phenotypes of inflammatory myopathies with the presence of serum MSAs or MAAs, as well as with type I IFN activation.

Myositis-related autoantibody profile and clinical characteristics stratified by anti-cytosolic 5'-nucleotidase 1A status in connective tissue diseases.

Cytosolic 5'-nucleotidase 1A (cN-1A) autoantibodies have been recognized as myositis-related autoantibodies. However, their correlations with clinical characteristics and other myositis-specific and myositis-associated autoantibodies (MSAs/MAAs) are still unclear. We aimed to establish the prevalence and clinical and laboratory associations of cN-1A autoantibodies in a cohort of patients with connective tissue diseases. A total of 567 participants (182 idiopathic inflammatory myopathies [IIM], 164 systemic lupus erythematosus [SLE], 121 systemic sclerosis [SSc], and 100 blood donors [BD]) were tested for the presence of cN-1A autoantibodies and other myositis-specific and myositis-associated autoantibodies (MSAs/MAAs). Clinical and laboratory characteristics were compared between anti-cN-1A positive and negative patients with sporadic inclusion body myositis (sIBM) and between anti-cN-1A positive and negative patients with non-IBM IIM. In the sIBM cohort, 30 patients (46.9%) were anti-cN-1A positive vs. 18 (15.2%) in the non-IBM IIM cohort, 17 (10%) were anti-cN-1A positive in the SLE cohort and none in the SSc or the BD cohorts. Anti-cN-1A positivity had an overall sensitivity of 46.9% and a specificity of 93.2% for sIBM. Dysphagia was more frequent in the anti-cN-1A positive vs. negative sIBM patients (p = .04). In the non-IBM IIM group, being anti-cN-1A antibody positive was associated with the diagnosis polymyositis (p = .04) and overlap-myositis (p = .04) and less disease damage evaluated by physician global damage score (p < .001). cN-1A autoantibodies were predominantly found in IIM patients and was associated with dysphagia in sIBM patients. Notably, anti-cN-1A appears to identify a distinct phenotype of anti-cN-1A positive non-IBM IIM patients with a milder disease course.

Association of anti-TPM4 autoantibodies with vasculopathic cutaneous manifestations in juvenile dermatomyositis.

AECAs are detected in multiple forms of vasculitis or vasculopathy, including JDM. High levels of tropomyosin alpha-4 chain (TPM4) gene expression in cutaneous lesions and TPM4 protein expression in some endothelial cells (ECs) have been proven. Furthermore, the presence of autoantibodies to tropomyosin proteins have been discovered in DM. We therefore investigated whether anti-TPM4 autoantibodies are an AECA in JDM and are correlated with clinical features of JDM. The expression of TPM4 protein in cultured normal human dermal microvascular ECs was investigated by Western blotting. Plasma samples from 63 children with JDM, 50 children with polyarticular JIA (pJIA) and 40 healthy children (HC) were tested for the presence of anti-TPM4 autoantibodies using an ELISA. Clinical features were compared between JDM patients with and without anti-TPM4 autoantibodies. Autoantibodies to TPM4 were detected in the plasma of 30% of JDM, 2% of pJIA (P < 0.0001) and 0% of HC (P < 0.0001). In JDM, anti-TPM4 autoantibodies were associated with the presence of cutaneous ulcers (53%; P = 0.02), shawl sign rash (47%; P = 0.03), mucous membrane lesions (84%; P = 0.04) and subcutaneous edema (42%; P < 0.05). Anti-TPM4 autoantibodies significantly correlated with the use of intravenous steroids and IVIG therapy in JDM (both P = 0.01). The total number of medications received was higher in patients with anti-TPM4 autoantibodies (P = 0.02). Anti-TPM4 autoantibodies are detected frequently in children with JDM and are novel myositis-associated autoantibodies. Their presence correlates with vasculopathic and other cutaneous manifestations of JDM that may be indicative of more refractory disease.

Clinical and laboratory characteristics of idiopathic inflammatory myositis in Saudi patients: A retrospective study in a single tertiary centre.

Idiopathic inflammatory myositis (IIM) in Saudi patients has been poorly studied owing to the lack of available data. This study aimed to identify the clinical and laboratory features of patients at a single tertiary care center. This retrospective study reviewed the medical records of Prince Sultan Military Medical City, Riyadh, Saudi Arabia to collect clinical and laboratory data between December 2022 and February 2017 as follows: age at disease onset, gender, follow-up duration and disease duration; clinical symptoms; laboratory result; presence and type of myositis-specific autoantibody or myositis-associated autoantibody; and type of immunosuppression, presence of malignancy, disease course, and outcome. There were 26 patients with a mean age of 36.16±13.48, and 84.6% were women. The most prevalent form of IIM was dermatomyositis (n=16, 61.5%), and the most affected organ was the skin. weakness was observed in 25 patients (96.2%), and dysphagia was the most common alarm sign (n=10, 38.5%). During follow-up, the creatine kinase level was elevated at the beginning of the disease and then decreased following treatment, with a mean of 277.73 IU/L. Of the total patients, 17 (68%) were positive for anti-nuclear antibody and 5 (19.2%) were positive for anti-Jo-1. In our patients, dermatomyositis was the most common form of myositis, and skin manifestations were the most prevalent clinical characteristics. None of the patients developed a malignancy or died.

Seroprevalence of SARS-CoV-2 in treatment naïve patients of rheumatological diseases

Dear Sir,COVID-19 is of paramount concern in the rheumatology community. As per current consensus, patients of rheumatological diseases (RDs) are at higher risk of SARS-CoV-2 infection than the general population (high agreement but very low grade of evidence); however, contradictory reports are available regarding its seroprevalence and association with severity and mortality. However, these inferences are mainly based on patients who have long-standing RDs and on various therapies. Then what would happen to those who are treatment-naive, mildly symptomatic, or carrying this disease unknowingly in the community during this pandemic? To explore this aspect, we screened blood samples of clinically suspected patients of autoimmune diseases (ADs) for COVID-19 IgG antibody during the pandemic in the pre-vaccination period. Based on clinical profile, antinuclear antibody (ANA), antineutrophilic cytoplasmic antibody (ANCA), and myositis-associated autoantibodies were tested. Out of 268 clinically suspected cases of RDs, 131 samples were positive for autoantibodies: RD group (114 ANA+08 myositis associated antibody+09 ANCA), and the rest 137 were negative (non-RD group). Out of these, three samples each from RD (3/131; 2.29%) and non-RD group (3/137; 2.17%) turned out to be positive for COVID-19 IgG antibody (EUROIMMUN, Germany), suggesting no increased prevalence of COVID19 in patients of the RD group (OR=1.046, 95% CI: 0.145–7.53, P=0.9645). Among the RD group, two patients were finally diagnosed with systemic lupus erythematosus (SLE); however, others did not turn up again to the hospital to comment on the final diagnosis. None of these COVID-19 positive patients had any known comorbidities or RD-related treatment. These positive patients from both groups had almost similar mildto-moderate COVID-19 disease courses with a favorable outcome. A meta-analysis found a marginal association of ADs with increased risk of severity and mortality of COVID-19 disease (Risk of severity: OR=1.21, 95% CI: 0.58–2.5, P=0.79; Risk of mortality: OR=1.31, 95% CI: 0.33–5.2, P=0.95); however, the difference was not significant. Studies have documented COVID-19 frequency of 2.4% (4/165) among SLE patients with severe cases mostly in coexisting comorbidities. Even recent consensus has suggested older age, presence of comorbidities, and use of prednisolone ≥10 as a risk factor for poor outcome in these two coexisting diseases. Unlike the previous reports, the present study highlighted the susceptibility of treatment naïve cases of RDs for COVID-19. The RD group either has an almost similar SARS-CoV-2 prevalence as the non-RD group (2.29% vs. 2.17%) or even lowers than the general population (2.29% vs. 7%). In conclusion, RD itself does not seem to be a risk factor for SARS-CoV2 infection, even in treatment naïve patients; however, disease outcome may depend on various coexisting factors/comorbidities. Inter-talk between SARS-CoV-2 and RDs yet to be explored.