Expression of eotaxin, interleukin 13 and tumour necrosisfactor‐α in dermatitis herpetiformis

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Abstract
Background The dermal and perivascular infiltrate in dermatitis herpetiformis (DH), which is mainly composed of CD4+ lymphocytes, neutrophils and eosinophils, is believed to play an important part in the pathogenesis of the disease. Previous studies suggest that cytokines such as interleukin (IL) -8, granulocyte-macrophage colony-stimulating factor, IL-4 and IL-5 could be involved in the pathogenesis of DH. These cytokines appear to drive tissue infiltration and maturation of eosinophils. Part of the effect of T-helper (Th) 2-type cytokines (IL-4, IL-5) on eosinophils could be mediated by eotaxin, which is a highly specific chemotactic protein induced by various cytokines [IL-4, IL-13, tumour necrosis factor (TNF) -α and interferon-γ]. Objectives To evaluate the expression of eotaxin and its inducers, IL-13 and TNF-α, in DH. Methods We examined lesions collected from 10 DH patients with active disease. Sections from each specimen were incubated with anti-IL-13, anti-TNF-α and anti-eotaxin antibodies. Chloroacetyl esterase reaction was performed to show mast cell infiltration. Results Eotaxin was mainly expressed at the tips of the dermal papillae, within the microabscesses. Positivity was also found in the lymphomonocytic infiltrate in the dermis. IL-13 was expressed in the dermal infiltrate and TNF-α was found in the inflammatory infiltrate and in dermal vascular cells. Conclusions These findings confirm the importance of the lymphomonocytic infiltrate and of Th2 cytokines in the pathogenesis of this disease, suggesting that tissue infiltration in DH is mediated by cell-specific chemokines such as eotaxin and not only by non-specific chemokines such as IL-8.