Association of Cytomegalovirus Infection With Anti-MDA5 Antibody-Positive Dermatomyositis: A Prospective Cohort Study

Abstract

<b>Objectives:</b> To investigate whether cytomegalovirus (CMV) infection plays a role in the pathogenesis and prognosis of idiopathic inflammatory myopathy (IIM), particularly in anti-MDA5 antibody-positive (anti-MDA5⁺) dermatomyositis (DM). <b>Methods:</b> A prospective cohort of 204 newly diagnosed IIM patients and 50 healthy individuals were enrolled in the study. CMV-IgM and CMV-IgG antibody concentrations and lymphocyte counts were analyzed. Differences in categorical data were compared using Fisher's exact test and the chi-square test. One-year survival rates were analyzed in MDA5⁺ DM patients with and without CMV infection. <b>Results:</b> In IIM patients, the median CMV-IgM level was significantly higher than in healthy controls (6 U/mL vs. 0 U/mL, <i>p</i> < 0.05) as was the median CMV-IgG level (114 U/mL vs. 105 U/mL, <i>p</i> < 0.05). The percentage of recent CMV infections in the MDA5⁺ DM group was much higher than it was in the MDA5^- IIM group (19.1% vs. 7.0%, <i>p</i> = 0.009). MDA5⁺ DM patients with CMV DNA-emia had poorer 1 year survival than the CMV-DNA^- group (33.3% vs. 86.3%, <i>p</i> = 0.010). CMV-IgM-positive (CMV-IgM⁺) MDA5⁺ DM patients had lower CD4⁺ T cell counts (245.7 cells/μL vs. 420.5 cells/μL, <i>p</i> < 0.05) and CD19⁺ B cell counts (97.3 cells/μL vs. 240.6 cells/μL, <i>p</i> < 0.05). <b>Conclusion:</b> The number of CMV infections was significantly higher in IIM patients, particularly in MDA5⁺ DM patients. Lower CD4⁺ T cells and CD19⁺ B cells were observed in CMV-IgM⁺ MDA5⁺ DM patients. CMV infection may have an important role in the pathogenesis and prognosis of MDA5⁺ DM by disrupting immunity.