Contrasting pathogenesis of atopic dermatitis and psoriasis--part II: immune cell subsets and therapeutic concepts.

Atopic dermatitis (AD) and psoriasis are among the most common inflammatory skin diseases. In the first part of this 2-part review, we discussed the similarities and differences between AD and psoriasis with respect to clinical features and pathology. The diseases are characterized by infiltration of skin lesions by large numbers of inflammatory cells; the second part of this review focuses on immune cell subsets that distinguish each disease and the therapeutic strategies that might be used or developed based on this information. We discuss the interactions among different populations of immune cells that ultimately create the complex inflammatory phenotype of AD and compare these with psoriasis. Therapeutic strategies have been developed for psoriasis based on the cytokine network that promotes inflammation in this disease. Antibodies against IL-12 and IL-23p40 antibody and antagonists of TNF are used to treat patients with psoriasis, and studies are underway to test specific antagonists of IL-23, IL-17, IL-17 receptor, IL-20, and IL-22. We discuss how these therapeutic approaches might be applied to AD.