Background:Idiopathic inflammatory myopathies (IIM) are a group of immune-mediated diseases characterized my muscle weakness, skin rash and systemic involvement. Myositis-specific antibodies (MSA) and myositis-associated antibodies (MAA) play a major role in IIM diagnosis, classification and prognosis. Nevertheless, MSA/MAA testing is not standardized and there very few studies addressing their relationship with other diseases.Objectives:To describe a cohort of patients tested positive for MSA/MAA, and to explore it´s relationship with IIM and other autoimmune diseases.Methods:We retrospectively review all the serum samples obtained from patients tested for MSA/MAA during 2019 in the Immunology department of Ramón y Cajal University Hospital (Madrid, Spain). These antibodies were tested by specific immunoblot (EUROLINE: Autoimmune Inflammatory Myopathies 16 Ag) with highly purified MSA/MAA. Positivity was stablished according to absorbance titer and adjusted by positive control of each test (arbitrary units, AU). Patients were diagnosed with IIM according to their clinician diagnosis. Diagnosis and classification were confirmed by an independent rheumatologist (JL) according to current understanding of IIM classification.Results:Three-hundred-seventy-five samples were tested for MSA during the study period. Two-hundred-seventy-nine were negative for all antibodies tested. Ninety-six samples were positive for one or more MSA/MAA, corresponding to 74 patients (11 patients had 2 different samples). Forty-nine (66.2%) of the patients who tested positive were female and 25 (33.8%) were male. Mean age was 58.65 years. Only 22 patients (29.7%) had a confirmed diagnosis of IIM, 24 (32.4%) had a diagnosis of other autoimmune disease, and 11 (14.9%) were diagnosed with interstitial lung disease (ILD) (Figure 1). Six ILD patients had anti-PM-Scl or anti-Ku antibodies, which are associated with scleroderma or overlap-CTD myositis, nevertheless, they remained classified as ILD as no other features were described in this group.Seventeen patients were positive for more than 1 MAA or MSA, including 14 patients positive for anti Ro-52. Antibody titer was higher in the IIM group compared to non-myositis group (59.59 vs 44.16, p=0.015). Anti Mi-2 was positive in 4 ILD without any other myositis features, and high titer anti-SRP (n=4, mean 59.75 AU) was found in primary biliary cirrhosis (PBC) patients. Additionally, 5 patients positive for antiJo-1 using ELIA (Thermo Fisher) were diagnosed with antisynthetase syndrome. IIM diagnosis and its relationship with antibody titer is represented in table 1.Table 1.Autoantibody titer according to diagnosis.Antibody (Number of patients)Number of samplesIIMIIM antibody titer (AU)Non-IIMNon-IIM antibody titer (AU)Other AI diseasesAnti Ro-52Anti Jo-1 (n=1)11 (100%)92.70-01 (100%)Anti PL-7 (n=8)113 (37.5%)29.595 (62.5%)25.595 (62.5%)2 (25%)Anti PL-12 (n=3)21 (33.3%)53.952 (66.6%)69.971 (33.3%)2 (50%)Anti EJ (n=1)11 (100%)99.460-01 (100%)Anti OJ (n=2)40-2 (100%)23.041 (50%)0Anti Ku (n=14)193 (21.4%)107.2511 (78.6%)31.855 (35.7%)0Anti Tif1gamma (n=5)63 (60%)40.122 (40%)23.841 (20%)0Anti NXP2 (n=2)30-2 (100%)13.991 (50%)1 (50%)Anti Mi2 (n=12)173 (25%)48.659 (75%)26.674 (33.3%)0Anti SAE (n=1)10-1 (100%)1800Anti MDA5 (n=2)32 (100%)30.5401 (50%)1 (50%)Anti SRP (n=9)124 (44.4%)42.695 (55.6%)68.165 (55.5%)2 (22.2%)Anti PM-Scl75 and PM-Scl100 (n=2)21 (50%)68.61 (50%)36.6700Anti PM-Scl75 (n=8)10016.268 (100%)22.723 (37.5%)1 (12.5%)Anti PM-Scl100 (n=4)50-4 (100%)23.622 (50%)0Conclusion:Only 28.7% of the patients that were MAA/MSA positive had a diagnosis of IIM. Other autoimmune diseases and ILD were commonly found in this group of MSA/MAA positive patients.References:[1]Damoiseaux J, Vulsteke JB, Tseng CW, Platteel ACM, Piette Y, Shovman O, et al. Autoantibodies in idiopathic inflammatory myopathies: Clinical associations and laboratory evaluation by mono- and multispecific immunoassays. Vol. 18, Autoimmunity Reviews. Elsevier B.V.; 2019. p. 293–305.Disclosure of Interests:None declared
BackgroundSystemic Sclerosis (SSc) is a rare and heterogeneous connective tissue disease (CTD) characterized by skin fibrosis, vasculopathy/vascular damage and potential visceral impairment. Interstitial lung disease (ILD) constitutes the leading cause of mortality and requires close periodical assessment and follow-up. Diffuse cutaneous sclerosis and specific autoantibody profile (anti SCL70, anti Th/To, Anti U3 RNP and anti PmScl) are considered ILD development risk factors. In contrast, positivity to anticentromere has been considered as a protective factor to develop a clinical significant ILD.ObjectivesTo assess ILD frequency and severity (extension and functional impairment) in SSc patients, analyzing the association with the different autoantibodies.MethodsRetrospective, descriptive study of patients meeting EULAR/ACR 2013 SSc criteria and had a HRTC performed at a tertiary Spanish hospital from 1975 to 2018. One hundred and eight patients were included. HRCTs were graded by two radiologists according to Goh et al semiquantitative score. Three groups were established according to the presence of different autoantibodies: anticentromere (ACA), antitopoisomerase (ATA), and positivity to other ANAs (nucleolar pattern and other specificities).ResultsClinical and laboratory characteristics are presented in table 1. Thirty-three patients had pulmonary involvement, 6 were ACA+, 18 ATA+ and 9 had other ANA specificities. The probability of not having pulmonary involvement among ACA+ and of having pulmonary involvement among ATA + showed statistic significance (p<0.001 and p<0.001). Usual intestinal Pneumonia (UIP) was the most frequently reported pattern (6 patients), followed by Non-Specific Interstitial Pneumonia (NSIP 11 patients); Six patients did not meet the radiological criteria for neither UIP or NSIP. No statistical significant difference was found among radiological pattern and autoantibody profile. Regarding extension: 15 patients had non-extensive involvement (ACA: 2, ATA: 7, “other ANAs”: 6) performing Goh et al score with the FVC correction. Extensive ILD was found among 18 patients (ACA: 4, ATA: 11, “other ANAs”: 3). Despite the fact that ATA+ group was more likely to have an extensive involvement no statistical significance was met. About pulmonary function tests (PFT) the mean FVC was 98,45% on ACA group, whereas on ATA and other ANAs groups the mean FVC were 88,97% and 81,43% respectively. Statistical differences were found between first and third group, However this difference was not found when only patients with pulmonary involvement were analyzed.ConclusionIn our cohort, ATA and other ANAs groups were more likely to develop pulmonary interstitial disease and to need inmunosuppressant treatment. Although the prevalence of ILD among ACA+ was only 10%, 50%of them required, due to the functional impairment or extension, inmunosuppressant treatment. In spite of the low ILD-ACA+ incidence this complication should be kept in mind and periodical screening and assessment must be carried out as in other...
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