Analysis of cytokine expression in muscle in inflammatory myopathies, Duchenne dystrophy, and non-weak controls

We investigated the profiles of cytokine mRNA expression in muscle in 15 cases of inflammatory myopathy (IM) (5 each of polymyositis, inclusion body myositis, and dermatomyositis) and in 10 controls (5 of Duchenne dystrophy and 5 non-weak subjects). Expressions of the predominantly T cell-derived cytokines (interleukin (IL)-2, IL-4, IL-5, and Interferon-γ (IFN-γ), of the predominantly macrophage-derived cytokines (IL-1, IL-6, and tumor necrosis factor-α (TNF-α)), as well as cytokines that can be of either T cell or macrophage origin (granulocyte-macrophage colony stimulating factor (GM-CSF) and transforming growth factor β1 (TGF-β1) and TGF-β2), were monitored by the reverse transcriptase-PCR method. The expression of T cell cytokine mRNAs for IL-2, IL-5, and IFN-γ was generally weak or inconsistent. IL-4 mRNA expression was consistently moderate to strong in polymyositis but generally weak or absent in the other IMs. The expression of macrophage cytokine mRNAs for IL-1 α and IL-1 β was weak or absent in all cases. Variable TNF-α mRNA expression was observed in 12 of 15 IM cases and faint or weak expression in 5 of 10 controls. Very strong GM-CSF.