Th1 Response and Systemic Treg Deficiency in Inclusion Body Myositis

ObjectiveSporadic inclusion body myositis (sIBM), the most frequent myositis in elderly patients, is characterized by the presence muscle inflammation and degeneration. We aimed at characterizing immune responses and regulatory T cells, considered key players in the maintenance of peripheral immune tolerance, in sIBM.MethodsSerum and muscle tissue levels of 25 cytokines and phenotype of circulating immune cells were measured in 22 sIBM patients and compared with 22 healthy subjects. Cytokine data were analysed by unsupervised hierarchical clustering and principal components analysis.ResultsCompared to healthy controls, sIBM patients had increased levels of Th-1 cytokines and chemokines such as IL-12 (261±138 pg/mL vs. 88±19 pg/mL; p+CD28− T cells (45.6±18.5% vs. 13.5±9.9%; p+CD25+CD127lowFOXP3+, 6.9±1.7%; vs. 5.2±1.1%, p = 0.01), which displayed normal suppressor function and were also present in affected muscle.ConclusionsIBM patients present systemic immune activation with Th1 polarization involving the IFN-γ pathway and CD8+CD28− T cells associated with peripheral regulatory T cell deficiency.