Anti-lymphocyte function associated antigen-1 inhibits T-helper 2 function of human allergen-specific CD4+ T cells

Biological Therapeutic Treatment of Atopic Dermatitis

Atopic dermatitis is a chronic recurrent inflammatory disease caused, inter alia, by violations of the barrier function of the skin and pathological immune response in the form of an imbalance of Th1 and Th2 lymphocytes with increased production of IL-4, IL-5, IL-13, IL-31. Treatment of severe forms of atopic dermatitis is not an easy task due to the variability of the individual response to treatment, the short duration of the therapeutic effect and the frequent development of undesirable phenomena associated with the use of existing methods of systemic immunosuppressive therapy. The study of the pathogenesis of atopic dermatitis made it possible to identify the spectrum of molecular targets, providing the basis for researching alternative variants to the previously used systemic therapy methods – genetic engineering biological preparations. Contemporary data on the pathogenesis of atopic dermatitis as well as potential molecular targets for innovative biological preparations, the efficacy of which has been evaluated through clinical trials, are presented in the review. 

Filaggrin inhibits generation of CD1a neolipid antigens by house dust mite-derived phospholipase

Atopic dermatitis is a common pruritic skin disease in which barrier dysfunction and cutaneous inflammation contribute to pathogenesis. Mechanisms underlying the associated inflammation are not fully understood, and although Langerhans cells expressing the nonclassical major histocompatibility complex (MHC) family member CD1a are known to be enriched within lesions, their role in clinical disease pathogenesis has not been studied. We observed that house dust mite (HDM) allergen generates neolipid antigens presented by CD1a to T cells in the blood and skin lesions of affected individuals. HDM-responsive CD1a-reactive T cells increased in frequency after birth in individuals with atopic dermatitis and showed rapid effector function, consistent with antigen-driven maturation. In HDM-challenged human skin, we observed phospholipase A2 (PLA2) activity in vivo. CD1a-reactive T cell activation was dependent on HDM-derived PLA2, and such cells infiltrated the skin after allergen challenge. Moreover, we observed that the skin barrier protein filaggrin, insufficiency of which is associated with atopic skin disease, inhibited PLA2 activity and decreased CD1a-reactive PLA2-generated neolipid-specific T cell activity from skin and blood. The most widely used classification schemes of hypersensitivity suggest that nonpeptide stimulants of T cells act as haptens that modify peptides or proteins; however, our results show that HDM proteins may also generate neolipid antigens that directly activate T cells. These data define PLA2 inhibition as a function of filaggrin, supporting PLA2 inhibition as a therapeutic approach.