Inclusion body myositis is a late onset inflammatory myopathy lacking reliable serum biomarkers for diagnosis and for disease progression. To identify diagnostic and predictive biomarkers, cytokine profiling is used to assess the potential of cytokines to discriminate between cases and controls and to assess whether treatment with methotrexate can influence biomarkers associated with disease progression. The diagnostic and follow-up potential of 48 cytokines was tested using Bioplex-assay and ELISA in sera of healthy individuals, IBM patients and patients with other neuromuscular disorders. Ten cytokines (TRAIL, IL-8, MIF, MCP-1, LIF, IP-10, IFN-α2, MIG, bNGF and IL-3) were identified to be good to excellent markers to discern IBM patients from healthy controls. Three cytokines (IP-10, Eotaxin and SDF1A) changed significantly upon methotrexate treatment as compared with the natural clinical course. Muscle strength loss was associated with changes in IL-8 and SDF1A levels. IFN-γ levels were only associated with survival of IBM patients before correction for multiple comparisons. Cytokine profiling can discriminate IBM patients from healthy controls and other neuromuscular disorders.
