Th17 and Th22 in skin allergy

Area of Science:

• Immunology
• Dermatology
• Cell Biology

Background:

• Eczematous skin reactions involve leukocyte recruitment and cytokine release.
• Th17 (RORC+IL-17+) and Th22 (IL-17-IFN-γ-IL-22+) cells are key lymphocytes interacting with non-immune cells.
• These T cell subsets are prevalent in immune-mediated skin diseases like atopic dermatitis, allergic contact dermatitis, and psoriasis.

Purpose of the Study:

• To elucidate the distinct roles of Th17 and Th22 cells in skin immunity and inflammation.
• To understand the mechanisms by which Th17 and Th22 cells influence keratinocytes and skin integrity.

Main Methods:

• The study focuses on the functional characterization of Th17 and Th22 cells based on their cytokine profiles (IL-17, IFN-γ, IL-22) and RORC expression.
• Analysis of their impact on keratinocyte behavior, including immune defense activation, adhesion molecule expression, proliferation, migration, and cytokine/chemokine release.

Main Results:

• Both IL-17 and IL-22 activate keratinocyte innate immunity.
• Th17 cells, particularly with IFN-γ, enhance keratinocyte adhesion molecules, promote T cell-keratinocyte cytotoxicity, and induce apoptosis.
• Th22 cells primarily promote keratinocyte proliferation and migration, maintaining skin integrity, but can amplify inflammation in certain contexts.

Conclusions:

• Th17 and Th22 cells have distinct, yet sometimes overlapping, functions in skin inflammation.
• Th17 cells are primarily pro-inflammatory, contributing to keratinocyte damage, whereas Th22 cells are crucial for skin barrier function but can exacerbate inflammation.
• Understanding these differences is vital for targeted therapeutic strategies in immune-mediated skin diseases.