799 Acute IL-17A production by a 3D immunocompetent psoriatic skin substitute to study the interaction between epithelial and immune cells

Abstract

Psoriasis is a chronic inflammatory dermatosis mediated by T cells through the IL-23/IL-17 axis. The hallmark cytokine of the Th17 cells, IL-17A, activates keratinocytes leading to the secretion of various chemokines that also account for leukocytes infiltration, thus producing an activation loop leading to the chronicization of the psoriatic lesions. The lack of suitable preclinical models reflecting the complex phenotype of this skin disease is a major obstacle to the further study of psoriasis pathogenesis. In this study, we aimed to optimize T cell culture methods and their incorporation into a 3D models in order to obtain long-term IL-17A production. To this end, both healthy (HS) and psoriatic (PS) skin substitutes have been produced according to the self-assembly method. T cells were isolated from whole blood by negative selection with the EasySep Direct Human T cell isolation kit and activated with phorbol 12-myristate 13-acetate (PMA, 25ng/ml) and ionomycin (1μg/ml). Activated T cells were then seeded into the 3D skin models. The location of CD3+ T cells within the skin substitutes was demonstrated by immunofluorescence staining. PS displayed a more pronounced leucocyte infiltration than HS. Compared to the previous activation method, the activation with PMA and ionomycin allowed the production of IL-17A. Moreover, a higher production of IL-17A was obtained with the psoriatic skin model than with the healthy one (p<0.001). Overall, these results suggest that the 3D immunocompetent psoriatic skin model is a promising tool for the study of the psoriasis pathogenesis as it allows to further mimic the physiopathological context found in native psoriatic skin.