Background/Purpose: Previous studies have demonstrated that CD4⁺ T cells from peripheral blood of anti-histidyl-tRNA synthetase (anti-His-tRNA) also known as anti-Jo-1 positive patients proliferate in response to stimulation with full-length His-tRNA and a N-terminal fragment comprising residues 1-60. Our group has already characterized a specific CD4⁺T cell response towards the full length His-tRNA-synthetase and a peptide in the N-terminal fragment in blood and broncho-alveolar lavage of myositis patients. In this study we are presenting a novel epitope that identifies patients with moderate-severe interstitial lung disease (ILD).

Methods: Sixteen anti-Jo-1 positive patients with antisynthetase syndrome followed at the Karolinska University Hospital were enrolled. As controls we included HLA-DRB1*03-positive healthy individual (HCs, n=8). Peripheral blood mononuclear cells were isolated by Ficoll-Hypaque density centrifugation and in vitrostimulated with: a) full length His-tRNA protein; b) a novel HLA-DR*03:01 binding peptide from native His-tRNA; c) an altered peptide ligand (APL) variant of His-tRNA, designed to prevent recognition by HLA-DR3/His-tRNA-specific TCRs. T cell activation was assessed by CD40L up-regulation and expression of pro-inflammatory cytokines (IFN-g, IL-2 and IL-17A) by flow cytometry. Clinical and laboratory data were documented: myositis-specific and associated autoantibodies, manual muscle test (MMT-8), health assessment questionnaire (HAQ) and interstitial lung disease (ILD). Descriptive statistics are shown with mean and standard deviation or median and IQR. Student’s T test or Mann-Withney U-test were used to analyze differences between groups.

Results: At the time of blood sampling the patients had a mean age of 58 years (48-83 years), with a median disease duration of 50 months (11-70 months), MMT8 score 80 (79-80), HAQ 0.25 (0-13-0.75). Eighty-four percent were female, 13/16 patients had ILD and 13/16 had muscle weakness. T cell activation towards the novel His-tRNA peptide was observed in two of the 16 anti-Jo-1 positive patients. When stimulating with the APL version of His-tRNA, no T cell activation was observed in one of the patients that was reactive for the peptide. For evaluation of pro-inflammatory features, the His-tRNA-specific T cells displayed significant up-regulated levels of IFN-g (p<0.05) compared to HC (p<0.05). Additionally one out of eight healthy donors displayed a modest response to both the novel His-tRNA peptide and the full length His-tRNA protein. In this context only IL-2, and no other pro-inflammatory cytokine production was observed. The patients that showed an upregulation of CD40L in CD4⁺T cells to the novel His-tRNA peptide had a moderate-severe clinical progression of ILD that required aggressive immunosuppressive treatment.

Conclusion: In this study, we demonstrate the presence of His-tRNA-reactive CD4⁺ T cells in peripheral blood from anti-Jo-1 positive patients and a novel His-tRNA peptide, characterized by the expression of IFN-g. This phenotype seemed to correlate to a moderate-severe clinical progression of ILD.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/identification-of-a-novel-pro-inflammatory-t-cell-epitope-from-his-trna-synthetase-associated-with-interstitial-lung-disease-in-anti-jo-1-positive-patients/