Clinical and immunological characteristics and prognosis of patients with autoantibody negative dermatomyositis: a case control study.

Abstract

Myositis-specific antibodies (MSAs) and myositis-associated antibodies (MAAs) are associated with distinctive dermatomyositis (DM)clinical phenotypes. The aim of this study is to explicate the clinical andimmunologicalfeatures of MSAs-negative DM patients. A total of 515 individuals diagnosed with DM was screenedfrom 2013 to 2022 and 220 DM patients were enrolled in this retrospective cohort. Clinical and laboratory data of these patients were analyzed. MSAs-negative DMpatients were categorized into two groups: MAAs-negative(MSAs (-)/MAAs (-)) groupand MAAs-positive (MSAs (-)/MAAs (+))group. The percentage of Raynaud's phenomenon (P=0.026) was higher in the MSAs (-)/MAAs (+) DM patients than the MSAs-positiveDM patients and MSAs (-)/MAAs (-) DMpatients. The proportion of rapidly progressive interstitial lung disease (RP-ILD) in the MSAs-negative DM patients was lower than that in the MSAs-positive group. The MSAs (-)/MAAs (+) group had a higher proportion of organizing pneumoniaand usual interstitial pneumonia (P=0.011), and elevated eosinophils in their bronchoalveolar lavage fluid (P=0.008). Counts of lymphocytes (P=0.001) and CD16+CD56+ natural killer (NK) cells (P=0.012) were higher in the MSAs-negative group. Additionally, the percentage of CD4+TNFα+ (P=0.040), CD4+IFNγ+ (P=0.037), and CD4+IL-2+ (P=0.018) cells among totalCD4+ T cells were higher in the MSA-negative DM patients compared with the MSAs-positive DM patients. Besides, MSAs-negative patients demonstrated a more favorable prognosis than MSAs-positive patients. Multivariable regression analysis identified advanced onsetage, higher level ofcarcinoembryonic antigen (CEA), and RP-ILD as risk factors for mortality in DM patients. Compared with MSAs-positive group,MSAs-negative DM patients suffered less from organ involvement compared with MSAs-positive group and tend to have better prognosis. Key Points MSAs-negative DM patients exhibited distinct characteristics in comparison with MSAs-positive DMpatients: • The MSAs (-)/MAAs (+) DM patientsdemonstrated a higher prevalence of organizing pneumonia (OP)and usual interstitial pneumonia (UIP), and elevated eosinophil counts in bronchoalveolar lavage fluid. • CEA levels were lower in MSAs-negative patients compared with MSAs-positive patients. • Elevated counts of lymphocytes and CD16+CD56+ NK cells were identified in the MSAs-negativepatients. Additionally, proportions of CD4+TNFα+, CD4+IFNγ+, and CD4+IL-2+ cells among total CD4+ T cells were higher in the MSAs-negative DM patients compared with DM MSAs-positive DM patients. • MSAs-negative DMpatients had a more favorable prognosis than MSAs-positive DMpatients. A multivariable regression analysis revealed the advanced onsetage, highCEA levels, and RP-ILD were risk factors for mortality in DM patients.