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

Objectives: 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). Methods: 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. Results: In IIM patients, the median CMV-IgM level was significantly higher than in healthy controls (6 U/mL vs. 0 U/mL, p < 0.05) as was the median CMV-IgG level (114 U/mL vs. 105 U/mL, p < 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%, p = 0.009). MDA5(+) DM patients with CMV DNA-emia had poorer 1 year survival than the CMV-DNA(-) group (33.3% vs. 86.3%, p = 0.010). CMV-IgM-positive (CMV-IgM(+)) MDA5(+) DM patients had lower CD4(+) T cell counts (245.7 cells/mu L vs. 420.5 cells/mu L, p < 0.05) and CD19(+) B cell counts (97.3 cells/mu L vs. 240.6 cells/mu L, p < 0.05). Conclusion: 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.