Longitudinal assessment of reactivity and affinity profile of anti-Jo1 autoantibodies to distinct HisRS domains and a splice variant in a cohort of patients with myositis and anti-synthetase syndrome

Abstract

Background To address the reactivity and affinity against histidyl-transfer RNA synthetase (HisRS) autoantigen of anti-Jo1 autoantibodies from serum and bronchoalveolar lavage fluid (BALF) in patients with idiopathic inflammatory myopathies/anti-synthetase syndrome (IIM/ASSD). To investigate the associations between the reactivity profile and clinical data over time. Methods Samples and clinical data were obtained from (i) 25 anti-Jo1+ patients (19 sera with 16 longitudinal samples and 6 BALF/matching sera at diagnosis), (ii) 29 anti-Jo1− patients (25 sera and 4 BALF/matching sera at diagnosis), and (iii) 27 age/gender-matched healthy controls (24 sera and 3 BALF/matching sera). Reactivity towards HisRS full-length (HisRS-FL), three HisRS domains (WHEP, antigen binding domain (ABD), and catalytic domain (CD)), and the HisRS splice variant (SV) was tested. Anti-Jo1 IgG reactivity was evaluated by ELISA and western blot using IgG purified from serum by affinity chromatography. In paired serum-BALF, anti-Jo1 IgG and IgA reactivity was analyzed by ELISA. Autoantibody affinity was measured by surface plasmon resonance using IgG purified from sera. Correlations between autoantibody reactivity and clinical data were evaluated at diagnosis and longitudinally. Results Anti-Jo1 IgG from serum and BALF bound HisRS-FL, WHEP, and SV with high reactivity at the time of diagnosis and recognized both conformation-dependent and conformation-independent HisRS epitopes. Anti-HisRS-FL IgG displayed high affinity early in the disease. At the time of IIM/ASSD diagnosis, the highest autoantibody levels against HisRS-FL were found in patients ever developing interstitial lung disease (ILD) and arthritis, but with less skin involvement. Moreover, the reactivity of anti-WHEP IgG in BALF correlated with poor pulmonary function. Levels of autoantibodies against HisRS-FL, HisRS domains, and HisRS splice variant generally decreased over time. With some exceptions, longitudinal anti-HisRS-FL antibody levels changed in line with ILD activity. Conclusion High levels and high-affinity anti-Jo1 autoantibodies towards HisRS-FL were found early in disease in sera and BALF. In combination with the correlation of anti-HisRS-FL antibody levels with ILD and ILD activity in longitudinal samples as well as of anti-WHEP IgG in BALF with poor pulmonary function, this supports the previously raised hypothesis that the lung might have a role in the immune reaction in anti-Jo1-positive patients.

Autoantibodies against the melanoma differentiation–associated protein 5 in patients with dermatomyositis target the helicase domains

“…Eight constructs were designed based on the crystal structure of the MDA5 protein and the available literature [ 11 ] and contained one domain or a combination of domains of the MDA5 protein as presented in Fig. 1A ( Supplementary Data S1 .1 and Supplementary Table S2 , available at Rheumatology online) [ 20 , 21 ]. A retinoic acid–inducible protein I (RIG-I) construct, part of the same protein family as MDA5, served as a negative control.…”

Clinical and prognostic associations of anti-Jo-1 antibody levels in patients with antisynthetase syndrome

“…Among them, the first ASA reported in 1980 was anti-histidyl-tRNA synthetase (HisRS), also known as anti-Jo-1 antibody, which was closely associated with ILD and systemic symptoms in patients with ASS [8]. Anti-Jo-1 antibody is also the most common ASA, with a positivity rate of 60-70% in ASS patients [9]. ILD, one of the most common manifestations of ASS, may be the first and sometimes the only feature of ASS [10][11][12][13].…”

CD19-Targeting CAR T-Cell Therapy for Antisynthetase Syndrome

“…3 Additionally, in longitudinal assessments, anti-Jo-1 autoantibodies were detectable in blood and lungs at the time of diagnosis, and high levels of autoantibodies toward the histidyl transfer RNA synthetase full-length protein were associated with the development of ILD. 4 Current treatment for antisynthetase syndrome remains challenging due to few randomized clinical trials, rarity of this disease, and heterogeneous clinical presentation. The traditional pharmacological approach is based on the use of high doses of glucocorticoids in combination with immunosuppressive agents such as methotrexate, azathioprine, mycophenolate mofetil, cyclosporine, or tacrolimus.…”

“…The identification of antigen-reactive CD4 T cells in blood and bronchoalveolar lavage fluid supports the hypothesis that proinflammatory T cells may promote B-cell maturation, activation, germinal center–like structure formation (as observed in lung tissue), and anti-Jo-1 autoantibody production . Additionally, in longitudinal assessments, anti-Jo-1 autoantibodies were detectable in blood and lungs at the time of diagnosis, and high levels of autoantibodies toward the histidyl transfer RNA synthetase full-length protein were associated with the development of ILD …”