Background. Type I interferon (IFN) has been reported to have an important role in the development of cutaneous lupus erythematosus (CLE) and systemic lupus erythematosus (SLE). A new subset of CD4+ T cells, T helper (Th)17 cells, also plays a role in the development of autoimmunity. Aim. To investigate expression of interleukin (IL)-17 and IFN-α in different CLE subsets, and their associations with the pathogenesis of LE. Methods. Skin tissue samples from 33 cases, including chronic discoid LE (n=24), acute (A)CLE (n=4), subacute CLE (n=1) and lupus panniculitis (n=4) were collected for immunohistochemistry. Expression of IL-6, IL-17A, IFN-α, IFN-γ, myxovirus protein (Mx)A and transforming growth factor (TGF)-β was assessed in these samples. Results. All LE specimens had staining for IL-6 and TGF-β in the infiltrated inflammatory cells. IL-17A staining was seen in 84.8% of specimens, and IFN-α or MxA was seen in 93.9%. TGF-β expression in ACLE was significantly greater than that in both chronic cutaneous (CC)LE and in lupus panniculitis (P=0.02 for both). Expression of IL-17A was positively associated with expression of IFN-α and MxA (Spearman's ρ=0.56 and 0.39, respectively). In addition, the Cutaneous Lupus Erythematosus Disease Area and Severity Index (CLASI) correlated positively with expression of IFN-α and MxA (ρ=0.40 for both), whereas there was no correlation with IL-17A expression. Conclusions. Two major cytokines, IL-17A and IFN-α, may play roles in the pathogenesis of CLE. Their patterns of expression positively correlated with each other.
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