Patients with psoriasis are characterized by increased proliferation of T regulatory cells with a recent thymic emigrant phenotype

Abstract

Psoriasis (Ps) is a chronic inflammatory dermatosis with an autoimmune component, which in 30% of patients transforms into psoriatic arthritis (PsA). The relevance of studying this pathology is due to the increasing incidence and proportion of treatment-resistant forms, the declining quality of life. Research suggests a multifactorial autoimmune nature of Ps with loss of tolerance to epidermal antigens. The thymus promotes self-tolerance through the differentiation of T regulatory cells (Treg), and it is the primary source of T cells with a diverse repertoire of T cell receptors. Recent thymic immigrants (RTE) are less functional than mature T cells, preventing autoaggression against antigens that may be ineffectively presented in the thymus. The combined activity of RTEs and Tregs complements the central tolerance mechanism and prevent autoreactive processes. Studying the RTE, including Treg, is important for clarifying their role in the immunopathogenesis of psoriatic pathology and identifying potential biomarkers of disease progression. The aim of the study was to assess the number of RTE, including Treg, in health and psoriatic disease, and to analyze their proliferative activity. We used flow cytometry to determine the relative number of CD4+CD45RA+CD31+ (RTE) cells in peripheral blood, including Treg. The number of proliferating cells in the studied subpopulations was determined by intracellular Ki-67 level. Obtained data showed that RTE did not significantly change in patients with psoriatic disease compared to the donor's group. Furthermore, no significant differences were found in the number of proliferating RTE between the groups. The level of proliferated Tregs with the RTE phenotype in PsA patients was comparable to donor values, and in the Ps group, a significant increase in the number of proliferated Tregs was observed relative to the donor's group. The observed dynamics may reflect the activation of regulatory mechanisms of the immune system aimed at compensating for the proinflammatory processes in Ps, as well as compensatory mechanisms for replenishing the pool of naive Tregs. Thus, the identified differentiated changes in psoriatic pathology highlight the heterogeneity of their immunopathogenesis and serve a basis for the search for biomarkers that could predict the course of the disease.