Background/Purpose:

Antisynthetase Syndrome is a rare and severe autoimmune inflammatory disease that is associated with autoimmunity against aminoacyl-tRNA synthetase and clinical signs of arthritis, myositis and interstitial lung disease. The aim of this study was to test how many patients with positive anti-aminoacyl-tRNA synthetase autoimmunity present with clinical signs of Antisynthetase Syndrome.

Methods:

In a first step, patients with unexplained musculoskeletal pain referred to the outpatient clinic of Department of Internal Medicine 3 of the University of Erlangen-Nuremberg were tested for anti-aminoacyl-tRNA synthetase autoantibodies Jo1, PL12, PL7, EJ and OJ using immunoblot technology. In a second step, patients tested positive for the respective autoantibodies were carefully examined for the presence of clinical signs of Antisynthetase Syndrome and followed up whether clinical changes of Antisynthetase Syndrome developed.

Results:

160 subjects with positive anti-aminoacyl-tRNA synthetase autoantibodies were identified. 50 subjects (31%) had reactivity against anti-Jo1, 38 against PL12 (24%), 29 against PL7 (18%), 23 (14%) against OJ and 9 (6%) against EJ. 11 (7%) subjects had reactivities against more than one aminoacyl-tRNA synthetase. Median age at onset was 51 years (20 to 81 years) and mean (SD) follow up was 82 (81) months. 27 (17%) of these subjects had clear evidence for Antisynthetase Syndrome presenting with at least one of the clinical triad findings of the syndrome: arthritis, myositis and interstitial lung disease. There was a clear preponderance of females (78%) developing Antisynthetase Syndrome. 8 patients (30% of those with clinical signs of Antisynthetase Syndrome) presented with arthritis, 23 (85%) had myositis and 16 (59%) exhibited interstitial lung disease. Arthritis presented in all cases as symmetrical polyarthritis; IgG-RF was positive in one third of the patients, while ACPA were tested negative. Radiographic erosions on plain radiographs were only observed in one patient. “Mechanic” hands and Raynaud syndrome were present in 2 (7%) and 7 (26%) patients with Antisynthetase Syndrome, respectively. Two patients with Antisynthetase Syndrome died due to their disease.

Conclusion:

These results suggest that only a minority of individuals tested positive for anti-aminoacyl-tRNA synthetase autoantibodies develops Antisynthetase Syndrome. Individuals with positive autoimmunity but no clinical signs of Antisynthetase Syndrome may either represent pre-disease subjects, who may develop Antisynthetase Syndrome later in life or resemble “forme fruste” of the disease, presenting with only mild and unspecific musculoskeletal symptoms. Hence, further longitudinal observations are needed to determine the outcome of anti-aminoacyl-tRNA synthetase autoantibody carriers.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/only-a-minor-proportion-of-individuals-with-anti-aminoacyl-trna-synthetase-autoimmunity-presents-with-the-clinical-picture-of-antisynthetase-syndrome/