Controversial Issues of Immunopathogenesis of Psoriasis and Atopic Dermatitis

Psoriasis (PsO) and atopic dermatitis (AD have much in common: both diseases are widespread, characterized by a chronic relapsing course, primarily affect the skin and lead to a quality reduction of life of patients, regardless of their age. The pathogenesis of these two dermatoses, which are the most common in the practice of a pediatric dermatologist, is quite different. PsO is a chronic inflammatory skin disease, the pathogenesis of which is associated with the involvement of the Th1 pathway: Th17 cells and the IL-23/IL-17 axis. AD, in turn, is usually associated with high levels of IL-4, IL-5, IL-13, IL-31 and IFN-γ produced by activated T-helper 2 (Th2) cells. The clinical symptoms and immunopathological responses of these two skin conditions tend to differ. However, patients with PsO may sometimes present with a skin rash resembling AD combined with intense itching and laboratory increase in immunoglobulin E (IgE) which may indicate the need to change the paradigm of dominance of only one type of T-inflammation in patients with these diseases.