Autoantibodies to a 140‐kd polypeptide, CADM‐140, in Japanese patients with clinically amyopathic dermatomyositis

TLDR

Rapidly progressive interstitial lung disease warrants close monitoring in patients with anti‑CADM‑140 autoantibodies. The study aimed to identify novel autoantibodies specific to dermatomyositis, particularly those associated with clinically amyopathic DM. Antigen specificity was assessed by immunoblotting and indirect immunofluorescence, revealing cytoplasmic immunoreactivity with a granular or reticular pattern. Eight of 42 dermatomyositis patients had anti‑CADM‑140 antibodies, all with clinically amyopathic DM, and these patients exhibited a markedly higher incidence of rapidly progressive interstitial lung disease (50% versus 6% in antibody‑negative patients).

Abstract

To identify novel autoantibodies specific for dermatomyositis (DM), especially those specific for clinically amyopathic DM (C-ADM).Autoantibodies were analyzed by immunoprecipitation in 298 serum samples from patients with various connective tissue diseases (CTDs) or idiopathic pulmonary fibrosis (IPF). Antigen specificity of the sera was further examined by immunoblotting and indirect immunofluorescence (IF). The disease specificity and clinical features associated with the antibody of interest were determined.Eight sera recognized a polypeptide of approximately 140 kd (CADM-140 autoantigen) by immunoprecipitation and immunoblotting. Immunoreactivity was detected in the cytoplasm, and indirect IF revealed a granular or reticular pattern. Anti-CADM-140 antibodies were detected in 8 of 42 patients with DM, but not in patients with other CTDs or IPF. Interestingly, all 8 patients with anti-CADM-140 antibodies had C-ADM. Among 42 patients with DM, those with anti-CADM-140 autoantibodies had significantly more rapidly progressive interstitial lung disease (ILD) when compared with patients without anti-CADM-140 autoantibodies (50% versus 6%; P = 0.008).These results indicate that the presence of anti-CADM-140 autoantibodies may be a novel marker for C-ADM. Further attention should be directed to the detection of rapidly progressive ILD in those patients with anti-CADM-140 autoantibodies.