Tumour Necrosis Factor-alpha and Matrix Metalloproteinase-2 are Expressed Strongly in Hidradenitis Suppurativa

Hidradenitis suppurativa is a chronic skin condition, characterized clinically by painful, recurrent, deep-seated nodules and suppuration, and histologically by hypertrophic scarring of apocrine gland bearing skin and sinus tracts. The overall consequence of the disease is considerable tissue remodelling and the underlying alterations in innate immunity are poorly understood. The aim of this study was to evaluate the expression of human beta-defensin 2, tumour necrosis factor (TNF)-alpha and matrix metalloproteinase-2 in skin lesions of patients with hidradenitis suppurativa. A total of 14 skin samples from patients and 2 skin samples from healthy volunteers were evaluated by immunohistochemistry. Human beta-defensin 2 was negative in 12/14 specimens. Elevated expression of metalloproteinase-2 was observed in keratinocytes, fibroblasts and inflammatory cells in dermis, sweat glands, hair follicles and sinus tracts, suggesting a key role for hidradenitis suppurativa pathogenesis. Decreased human beta-defensin 2 in the presence of inflammatory (TNF-alpha-containing) cells suggests a decreased innate immunity in hidradenitis suppurativa-affected skin.