Background/Purpose: Myositis specific autoantibodies (MSA) and myositis associated autoantibodies (MAA) found in adult and juvenile idiopathic inflammatory myopathies (JIIM) often confer a specific disease phenotype. In adults, the MAA anti-Ro52 is associated with anti-synthetase (ARS) autoantibodies (Abs) and more severe interstitial lung disease (ILD). However, there are few studies examining the presence or significance of anti-Ro52 Abs in juvenile myositis. The purpose of this study was to define the prevalence and clinical features of anti-Ro52 Abs in a large cohort of patients with JIIM.

Methods: We screened sera from 307 patients with juvenile dermatomyositis (JDM), 26 patients with juvenile polymyositis (JPM), and 44 patients with juvenile connective tissue disease-myositis overlap (JCTM) for anti-Ro52 Abs by ELISA (INOVA, San Diego, CA). Clinical characteristics were compared between myositis patients with and without anti-Ro52 Abs.

Results: Anti-Ro52 Abs were found in 14% of JDM, 12% of JPM, and 18% of JCTM patients. Anti-Ro52 Abs co-existed in 64% of those with ARS (p<0.001) and in 31% of those with anti-MDA5 Abs (p<0.008). Less than 15% of those with anti-p155/140, -NXP2, -SRP, or -Mi2 Abs and less than 5% of those without an MSA were anti-Ro52+. After controlling for the presence of MSAs in multivariable analysis (including ARS and anti-MDA5), anti-Ro52 Abs were highly associated with ILD (36% vs 4%, p<0.001), dyspnea on exertion (59% vs 25% p<0.001), and a higher pulmonary score at diagnosis (0.18 vs 0.08 p=0.004). Even within the anti-MDA5+ subgroup, Ro52 reactivity was strongly correlated with ILD; 70% (7/10) of those with co-existing anti-Ro52 Abs had ILD compared to 9% (2/22) of those who were Ro52-. Similarly, among ARS+ patients, 100% (9/9) of anti-Ro52+ and only 40% (2/5) of anti-Ro52- patients had ILD. Disease course in anti-Ro52+ patients was more often chronic continuous (78% vs 52% p=0.05) and less often monocyclic (3% vs 24% p=0.02). Anti-Ro52+ patients were more often ACR functional class 4 (11% vs 4% p=0.008) and had a higher mean ACR functional class score at final evaluation (1.7 vs 1.4 p=0.007). Anti-Ro52 Abs were associated with an increased total number of medications received (4.8 vs 3.8 p=0.04) and anti-Ro52+ patients more often received intravenous pulse steroids (79% vs 52% p=0.03). Anti-Ro52+ patients less frequently had a documented remission (5% vs. 27% p=0.05). There were no significant differences in the prevalence of HLA DRB1 and DQA1 alleles between Caucasian juvenile myositis patients with and without anti-Ro52 Abs.

Conclusion: Anti-Ro52 Abs are most prevalent in juvenile myositis patients with anti-MDA5 and ARS Abs. Even after adjusting for the presence of MSAs, including anti-MDA5 and anti-ARS Abs, anti-Ro52+ patients were more likely to have ILD and other pulmonary manifestations. Furthermore, anti-Ro52+ patients have more severe disease requiring more intense treatment, less frequent remission, worse functional outcomes, and a frequent chronic disease course. The presence of anti-Ro52 Abs in JIIM may be a significant determinant of disease severity and prognosis, thereby warranting screening JIIM patients for anti-Ro52 Abs.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/association-of-anti-ro52-autoantibodies-with-interstitial-lung-disease-and-more-severe-disease-manifestations-in-juvenile-idiopathic-inflammatory-myopathies/