Delayed type hypersensitivity reactions to various allergens may differently model inflammatory skin diseases

Area of Science:

• Immunology
• Dermatology
• Molecular Biology

Background:

• Inflammatory skin diseases like atopic dermatitis (AD) and psoriasis require better predictive models for treatment response.
• Current treatment strategies necessitate the development of human experimental models to assess therapeutic efficacy.

Purpose of the Study:

• To evaluate and compare the immune responses and skin barrier alterations induced by common sensitizers in human skin.
• To establish a human experimental model for inflammatory skin diseases to predict treatment outcomes.

Main Methods:

• Four sensitizers (dust mite, diphenylcyclopropenone (DPCP), nickel, purified protein derivative (PPD)) were applied to healthy human skin.
• Skin hypersensitivity responses were analyzed using immunohistochemistry, RNA sequencing (RNA-seq), and reverse transcription-PCR (RT-PCR).

Main Results:

• All sensitizers increased cellular infiltrates (T-cells, dendritic cells) compared to controls.
• DPCP elicited the most robust immune response across innate, Th1, Th2, and Th17 pathways, alongside significant regulatory markers.
• DPCP and nickel best modeled the barrier defects seen in AD and psoriasis, affecting terminal differentiation, tight junctions, and lipid metabolism markers.

Conclusions:

• Diphenylcyclopropenone (DPCP) is a potent inducer of comprehensive immune responses and skin barrier defects relevant to atopic dermatitis and psoriasis.
• The study establishes a valuable human model for investigating inflammatory skin diseases and predicting treatment efficacy.