Published Online: October 10, 2013
Aeroallergens, including house dust mite (HDM), have been implicated in the pathogenesis of atopic dermatitis (AD). When HDM extract is applied on the nonlesional skin of AD patients using the Atopy Patch Test (APT), it induces eczema in about 50% of those tested. Although the pathogenic mechanism underlying this effect is not understood. While thymic stromal lymphopoietin (TSLP), a cytokine produced by epithelial keratinocytes, is suspected to play an important role in AD pathogenesis, the interplay of HDM allergen exposure and TSLP expression has not yet been studied in nonlesional AD skin.
In a Letter to the Editor in The Journal of Allergy & Clinical Immunology (JACI), Landheer et al. investigated TSLP expression in nonlesional skin of AD patients following APT with HDM extract. Ten patients with mild to moderate AD previously sensitized to HDM were subjected to APT application of HDM. Skin biopsies were taken in all patients 24 and 48 hours after application of HDM, and TSLP gene and protein expression were studied in both nonlesional and lesional skin biopsies.
The researchers confirmed TSLP protein expression in the epidermis of lesional AD skin, as had been previously shown. Application of HDM on nonlesional skin resulted in the induction of TSLP protein expression, but only in patients with a positive APT result. Interestingly there was also evidence in the APT- positive patients of CCL17/Thymus and activation-regulated chemokine (TARC), a TSLP biomarker and an indicator of AD severity.
In summary, the authors found that epicutaneous application of house dust mite in nonlesional atopic dermatitis induces TSLP expression by keratinocytes, suggesting a role for TSLP in house dust mite induction of atopic dermatitis-related eczema.
The Journal of Allergy and Clinical Immunology (JACI) is the official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.