Interleukin-32 is highly expressed in lesions of hidradenitis suppurativa

Summary

Background

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease. Its immunopathogenic mechanisms are still poorly understood. Previous studies could demonstrate that the pro-inflammatory cytokine Interleukin-32 (IL-32) is implicated in the pathogenesis of other inflammatory diseases.

Objectives

The aim of our study was to investigate the tissue expression and systemic levels of IL-32 as well as its cellular sources in HS patients in comparison to healthy donors and to patients suffering from two other inflammatory skin diseases: psoriasis (PS) and atopic dermatitis (AD).

Methods

Tissue samples were obtained from healthy skin and lesional HS, PS and AD skin to analyse the expression of IL-32 by immunohistochemistry and semi-quantitative real-time PCR. The cellular source of the cytokine was determined by double immunofluorescence staining. Serum of the four donors groups was used to measure systemic levels of IL-32 by enzyme-linked immunosorbent assay (ELISA).

Results

IL-32 was upregulated in HS patients in both lesional skin and serum when compared to healthy donors or AD and PS patients. In HS, IL-32 was found to be expressed by NK cells, T cells, macrophages and dendritic cells in highly infiltrated areas of the dermis. High IL-32 mRNA levels in lesional HS skin coincided with high amounts of T cells and macrophages present. Additionally, IL-32 mRNA levels in lesional HS skin correlate positively with IFNγ and IL-17 and negatively with IL-13.

Conclusions

Our findings suggest that IL-32 is overexpressed in HS. Targeting IL-32 may therefore represent a new therapeutic option for the treatment of this recalcitrant disease.

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