Background/Purpose : Autoantibodies directed against the aminoacyl transfer RNA (tRNA) synthetases are associated with myositis, arthritis, Raynaud’s phenomenon, mechanic’s hands, fever, and interstitial lung disease, clinically referred to as the anti–synthetase syndrome. A preliminary report has described the detection of an autoantibody to tyrosyl–tRNA synthetase (TyrRS) in only one patient with features of anti–synthetase syndrome. In addition, it has also been reported that TyrRS can be split into two fragments with distinct cytokine activities. We aimed to identify further patients with anti–TyrRS autoantibodies using other assays than previously reported methods and elucidate their clinical significance.

Methods : Multiple assays were performed to detect anti–TyrRS antibodies in the sera of patients with active polymyositis/dermatomyositis patients. First, recombinant human TyrRS protein coupled with a His-tag was expressed in Escherichia coli. Autoantibodies against the recombinant human TyrRS in sera of patients with polymyositis/dermatomyositis were quantified by employing solid phase direct enzyme–linked immunosorbent assay (ELISA). Second, the recombinant human TyrRS was electrophoresed and transferred to PVDF membranes. Western blot was performed with the serum samples and anti–human IgG secondary antibodies. Third, TyrRS–transfected HeLaS3 cells were immunoprecipitated with sample serum. Then, the antibody–protein complex captured with µMACS™ Protein G MicroBeads was loaded onto a µColumn. The eluted immunoprecipitates were subjected to the SDS–polyaclylamidegel electrophoresis, and western blotted with rabbit anti–TyrRS polyclonal antibodies. In addition, the titer of anti–TyrRS antibodies was evaluated by ELISA before and after treatment among the patients with positive anti–TyrRS antibodies at the initial evaluation. Control sera were obtained from normal healthy control subjects. The clinical features of the patients with positive anti–TyrRS antibodies were analyzed. This study was approved by the ethics committee of our institution, and the principles of the Helsinki Declaration were followed throughout the study.

Results : Sera from three patients with polymyositis/dermatomyositis showed significantly high O.D. values in ELISA, significant bands of 59 kDa protein of TyrRS at the same place as anti–His tag antibody in Western blot, and significant bands at the same place as the recombinant human TyrRS in immunoprecipitation assay. These data strongly suggest that these sera had autoantibodies to TyrRS. These patients had myositis, interstitial lung disease, arthritis, Raynaud’s phenomenon, and fever. In two of the three patients, anti–TyrRS antibody titers decreased as clinical diseases were ameliorated following treatment.

Conclusion : This study reconfirmed the presence of anti–TyrRS antibody in the setting of the anti–synthetase syndrome and strengthens the association of anti–synthetases with these conditions.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/identification-of-autoantibodies-to-tyrosyl-transfer-rna-synthetase-associated-with-anti-synthetase-syndrome/