Eosinophils in blood and skin – a complex role in the pathogenesis of psoriasis

Psoriasis is a chronic inflammatory papulosquamous skin disease, but the pathological spectrum of psoriatic lesions is far from limited to skin elements. Psoriasis is a complex disease caused by the interaction between genetic predisposition, environmental triggers and immune system dysregulation. Chronic psoriatic inflammation involves keratinocytes, as well as various cellular and humoral factors penetrating from the blood. Currently, eosinophils, which take an active part in the pathogenesis of psoriasis, are of great scientific interest. This scientific work is a narrative review of the literature and covers clinical and epidemiological studies, as well as descriptive and systematic reviews of the literature. The information presented in our scientific article is obtained from previously conducted studies. Eosinophils are pleiotropic multifunctional leukocytes involved in immune defense. Eosinophils play an important role in hypersensitivity reactions and in a number of autoimmune diseases, can migrate from the bloodstream to the skin in response to various attractors and produce various cytokines. It has been shown that eosinophils are capable of secreting eosinophilic cationic protein in the skin of patients with psoriasis. The degree of eosinophilia can be a marker of the severity and prognosis of psoriasis. Some researchers believe that peripheral blood eosinophilia is associated with severe forms of psoriasis (generalized pustular and erythrodermic). A number of scientists have identified an important negative role of the cytokine IL-31, which is secreted by eosinophils, as the main factor in skin itching. Numerous scientific papers indicate the important role of eosinophils in the development of psoriatic inflammation. Further research is needed to study eosinophils and their potential impact on the progression of psoriasis, with the aim of improving treatment and improving the quality of life of patients.