Itch in dermatomyositis: the role of increased skin interleukin-31

BACKGROUND: Interleukin (IL)-31 is implicated in pruritus associated with pruritic skin diseases like atopic dermatitis. Although pruritus is a prominent feature in dermatomyositis (DM), few studies have evaluated the pathogenesis of DM-associated itch. OBJECTIVES: To establish the prevalence of itch in DM, and to investigate the role of IL-31 in DM-related itch. METHODS: Pruritus and disease activity of DM were evaluated by a visual analogue scale (VAS) and the Cutaneous Disease and Activity Severity Index (CDASI), respectively. Expression of IL-31 and IL-31 receptor alpha (IL-31RA) in lesional DM, nonlesional DM and healthy control skin was evaluated by quantitative reverse-transcriptase polymerase chain reaction and immunofluorescence. Flow cytometry was performed on skin cells isolated from lesional DM skin to identify cellular sources of IL-31 in DM. RESULTS: cells were the most common cell type. Lenabasum, an emerging treatment for DM, significantly downregulated IL-31 from CpG-stimulated peripheral blood mononuclear cells. CONCLUSIONS: Increased skin IL-31 may play a role in DM-associated itch, and ongoing trials will evaluate the effects of systemic treatment on IL-31 and itch in DM.