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Objectives: To assess nailfold video capillaroscopic (NVC) abnormalities and their association with clinical features, myositis-specific autoantibodies (MSA), and myositis-associated antibodies (MAA) in a large multi-ethnic cohort of patients with idiopathic inflammatory myopathies (IIM)., Methods: We recruited 155 IIM patients from three centres in Mexico, Spain, and the USA. We evaluated the clinical and laboratory features of the patients and performed semiquantitative and quantitative analyses of the NVC. Each NVC study was defined as having a normal, non-specific, early systemic sclerosis (SSc), active SSc, or late SSc pattern. Twenty-three patients had at least one follow-up NVC when disease control was achieved. Quantitative variables were expressed as medians and interquartile range (IQR) and were compared with the Kruskal-Wallis, the Mann-Whitney U-test, and the Wilcoxon test for paired medians. Associations between qualitative variables were assessed with the χ2 test., Results: Most patients were women (68.3%), Hispanic (73.5%), and had dermatomyositis (DM) (61.2%). Fourteen patients (9%) had a normal NVC. A non-specific abnormality pattern was the most frequent (53.9%), and was associated with joint involvement, interstitial lung disease, Jo1 autoantibodies, anti-synthetase syndrome, and immune-mediated necrotising myopathy. The SSc pattern was observed mostly in DM and overlap myositis and was associated with cutaneous features and anti-TIF-1g autoantibodies. After treatment, there was a decrease in the capillaroscopic score, the capillary diameter, and the number of avascular areas, and an increase in capillary density and bushy capillary number., Conclusions: NVC abnormalities are related to the diagnosis, clinical features, disease activity, and autoantibodies of patients with IIM.

Objectives: The indirect immunofluorescence assay (IIFA) is used to screen for the presence of autoantibodies. Our objective was to determine the prevalence and clinical features of IIFA positive myositis patients without known myositis-specific autoantibodies (MSA)., Methods: Sera from healthy comparators (HC) and patients with dermatomyositis (DM), inclusion body myositis (IBM), and polymyositis (PM) with no detectable MSA were tested by IIFA on HEp-2 cells. The pattern of positivity was classified according to the International Consensus on Antinuclear Antibody Patterns. The prevalence and frequency of each IIFA pattern were compared between the different groups., Results: Sera from 100 HC, 71 DM, 53 IBM, and 69 PM subjects were included in the study. The IIFA was positive in 35% HC compared to 66% DM (p<0.001), 49% IBM, and 64% (p<0.001) PM sera. Among IIFA positive sera, the staining was moderate or intense in 43% HC compared to 79% DM (p<0.001) but just 54% IBM, and 52% PM sera. IIFA positivity was predominantly nuclear in all groups (all >69%). The most common pattern in myositis patients was fine speckled with no differences between groups. In general, IIFA positive and negative DM patients showed similar clinical features and disease activity., Conclusions: Half of MSA-negative DM patients have moderate/strong IIFA positivity, predominantly with a fine speckled pattern. In contrast, MSA-negative PM, IBM, and healthy comparators are more often weakly positive for IIFA. These findings suggest that unidentified autoantibodies are more likely to exist in DM patients than in the other myositis groups.

Objectives: The subsarcolemmal accumulation of p62 aggregates in myofibres has been proposed to be characteristic of sporadic inclusion body myositis (sIBM). The objective of this study was to analyse the patterns and prevalence of p62 immunostaining and to quantitate p62 gene expression in muscle biopsies from a large number of patients with different types of myopathic and neurogenic disorders., Methods: For the p62 immunostaining analysis, all patients with a muscle biopsy immunostained for p62 at the Johns Hopkins Neuromuscular Pathology Laboratory from 2013 to 2017 were included (n=303). The prevalence and pattern of p62 immunostaining were compared between patients with histologically normal muscle (n=29), inflammatory myopathies (n=136), non-inflammatory myopathies (n=53), and neurogenic disorders (n=85). p62 expression levels were analysed using an existing RNAseq dataset including data from dermatomyositis (DM; n=39), immune-mediated necrotising myopathy (IMNM; n=49), antisynthetase syndrome (AS; n=18), and sIBM (n=23) patients as well as 20 histologically normal muscle biopsies., Results: p62 staining was absent in normal biopsies, but present in biopsies from those with polymyositis (29%), non-inflammatory myopathies (all <31%), neurogenic disorders (31%), dermatomyositis (57%), sIBM (92%) and IMNM (87%). In all diseases studied, p62 accumulation was more prevalent in biopsies with more severe muscle damage. sIBM biopsies had decreased p62 expression levels compared to the other groups (corrected p<0.04)., Conclusions: p62 accumulation is a general response to muscle injury and not a specific marker for sIBM. Also, in sIBM, p62 RNA levels are decreased, suggesting that, in this disease, p62 aggregation is not due to overexpression.

Objectives: To study the efficacy in terms of muscle strength, and corticosteroid tapering as well as the prevalence of adverse effects in patients with the antisynthetase syndrome (ASyS) treated with azathioprine (AZA) compared to those treated with methotrexate (MTX)., Methods: We compared the clinical outcomes in ASyS patients treated with AZA versus MTX including change in corticosteroid dose, strength, and creatine kinase (CK) as well as the prevalence of adverse effects., Results: Among 169 patients with ASyS, 102 were treated at some point exclusively with either AZA or MTX (± corticosteroids). There were no significant differences in the rate of muscle strength recovery, CK decrease or corticosteroid tapering between those ASyS patients treated with MTX versus AZA. The prevalence of adverse events in patients treated with AZA and MTX was similar (29% vs. 25%, p>0.05); elevated liver enzymes (17% AZA vs. 12% MTX) and gastrointestinal involvement (10% AZA vs. 8% MTX) were the most common adverse events. While no patients treated with AZA developed lung complications, two of the patients treated with MTX experienced reversible pneumonitis with MTX cessation., Conclusions: AZA and MTX showed similar efficacy and adverse events in patients with ASyS. Pneumonitis is a rare but important event in patients receiving MTX.

Objectives: The aim of this study was to compare muscle biopsy findings, as well as clinical and analytical features, with those of magnetic resonance imaging (MRI) studies of muscle in patients with dermatomyositis., Methods: All patients from the Longitudinal Myopathy Cohort of the Hospital Clínic de Barcelona were prospectively included in the study from 2009 to 2016. MRI images of muscle and fascial oedema were compared with muscle pathology results using both quantitative and semi-quantitative scores., Results: We found a statistically significant association between the inflammatory infiltrate and both muscle (r2=0.54, p=0.001) and fascial oedema (r2=0.54, p<0.001). In addition, muscle oedema was significantly associated with punched-out vacuoles (p=0.04) and muscle enzymes in serum (r2=0.34, p=<0.01 for CK and r2=0.22, p<0.05 for aldolase). The number of treatment drugs received at the time of MRI was inversely associated with the number of muscle inflammatory cells in the biopsy and with both muscle and fascial oedema (all p<0.05)., Conclusions: Key MRI findings correlate with the main features of dermatomyositis muscle biopsy results, suggesting that MRI findings could be used as a surrogate marker of disease activity.

Objectives: To evaluate a new ultrasound sign, pleural irregularity (PI), for the study of interstitial lung disease (ILD) in patients with systemic sclerosis (SSc) and antisynthetase syndrome (ASS)., Methods: The study included patients from our SSc and ASS cohorts with varying degrees of ILD, enrolled from 2011 to 2014. Chest high-resolution computed tomography (HRCT), pulmonary function tests (FVC and DLCO) and chest sonography were performed in each patient. Ultrasound PI and B-lines were quantified using a 72-sonographic point score and HRCT lung abnormalities were quantified using Warrick and Wells scores and categorised through Goh's algorithm. PI was correlated with HRCT and pulmonary function test parameters and its diagnostic performance to detect and classify the extent of ILD was evaluated and compared with B-lines., Results: Thirty-seven patients were studied, 21 with ASS and 16 with SSc (8 without ILD). PI correlated with the Warrick score both in SSc (r=0.6, p=0.01) and ASS patients (r=0.6, p=0.005), showing a higher performance to detect ILD than using B-lines (p=0.01). In SSc patients PI also correlated with Wells score (r=0.7, p<0.001) and with DLCO (r=-0.5, p=0.05), showing a high diagnostic value for detecting ILD (AUC=0.85, 95% CI 0.64-1) and classifying it into limited or extensive (AUC=0.81, 95% CI 0.57-1). A modification of the Goh algorithm including PI was developed as a screening tool to avoid the use of HRCT in SSc patients without ultrasound evidence of extensive ILD., Conclusions: PI is useful for evaluation of ILD in SSc and ASS patients, and can be incorporated into a diagnostic algorithm in SSc patients to reducing the need for exposure to ionising radiation.