1. Home>
2. Specialties>
3. Dermatology>
4. Summary and Comment

"IL-22 T Cells" and Atopic Dermatitis

Increased numbers of IL-22–producing cells and increased expression differentiated AD from psoriasis and point the way for new therapies.

The interleukin (IL)-22 cytokine may have a unique and important role in the inflammation of atopic dermatitis (AD). IL-22 mediates keratinocyte proliferation and epidermal hyperplasia by downregulating genes governing terminal keratinocyte differentiation. Comparing differences in the prevalences of T-cell subtypes in AD and psoriasis, investigators identified unique IL-22–producing CD4 and CD8 T cells in AD patients.

Comparing samples of skin and peripheral blood from 13 psoriasis patients and 12 patients with chronic AD, the researchers found large numbers of IL-22–expressing T cells in the AD patients. The difference was particularly notable in respect to IL-22⁺CD8⁺ cells, which were very numerous in the AD dermis but scarce in psoriatic skin. IL-22 expression was greater in AD than in psoriasis, although present in both conditions. Similarly, the number of IL-17 T cells and the degree of IL-17 expression were greater in the psoriasis samples than in the AD samples (20-fold less IL-17 expression in AD).

Comment: The unique IL-22⁺ T cells found in atopic dermatitis might be good targets for new pharmaceutical agents. Although IL-22⁺ upregulation occurred in both conditions, most of the IL-22 in AD derived from IL-22 cells, whereas most of the IL-22 in psoriasis derived from IL-17 cells. Psoriasis and AD are very different dermatological diseases. These studies support a T_H2/T_H22 bias in AD and a T_H1/T_H17 bias in psoriasis.

— Mark V. Dahl, MD

Published in Journal Watch Dermatology July 10, 2009

Citation(s):

Nograles KE et al. IL-22–producing "T22" T cells account for upregulated IL-22 in atopic dermatitis despite reduced IL-17–producing T_H17 T cells. J Allergy Clin Immunol 2009 Jun; 123:1244.e2.

• Medline abstract (Free)