Increased expression of the interleukin-36 cytokines in lesions of hidradenitis suppurativa

BackgroundHidradenitis suppurativa (HS) is a recalcitrant chronic skin disease with poorly understood immunopathogenic mechanisms. Previous studies reported that the interleukin-36 (IL-36) cytokines [IL-36, IL-36, IL-36 and IL-36 receptor antagonists (IL-36RA)] are important players in the pathogenesis of psoriasis (PS). ObjectiveWe aim to determine whether the IL-36 cytokines are upregulated in patients with HS. For this purpose, we analysed local expression and systemic levels of the IL-36 cytokines in patients with HS and compared the results to healthy donors and patients with PS. MethodsSkin biopsies from healthy donors and HS and PS patients were analysed for expression of the IL-36 cytokines by immunohistochemistry and semiquantitative real-time PCR. The enzyme-linked immunosorbent assay (ELISA) was used to measure systemic levels of the IL-36 cytokines in the serum of the three donor groups. ResultsThe agonists IL-36, IL-36 and IL-36 were found to be upregulated in HS both systemically and lesionally, while the IL-36RA was not differently regulated in comparison to healthy donors. ConclusionOur findings suggest that the agonistic IL-36 isoforms are upregulated in HS. The relevance of the enhanced production of IL-36 cytokines in HS pathogenesis remains to be determined.