Tumor necrosis factor-alpha and interleukin-17 differently affects Langerhans cell distribution and activation in an innovative three-dimensional model of normal human skin

摘要

Among the several cytokines involved in the psoriasis pathogenesis, tumor necrosis factor (TNF)-alpha and interleukin (IL)-17 play a central role. Many biomolecular steps remain unknown due to difficulty to obtain psoriatic models. To investigate the effect of TNF-alpha and IL-17 on the ultrastructure, immunophenotype, and number of epidermal Langerhans cells (LCs), human skin explants (n = 7) were cultured air-liquid interface in a Transwell system. Four different conditions were used: medium alone (control), medium added with 100 ng/ml TNF-alpha or 50 ng/ml IL-17 or a combination of both cytokines. Samples were harvested 24 and 48 h after cytokine addition and were frozen. Samples harvested at 24 h were also processed for transmission electron microscopy (TEM). By immunofluorescence analysis with anti-human Langerin antibody (three experiments/sample) we calculated the percentage of LCs/mm(2) of living epidermis after 24 and 48 h of incubation (considering control as 100%). At 24 h LC number was significantly higher in samples treated with both cytokines (216.71 + 15.10%; p < 0.001) and in TNF-alpha (125.74 + 26.24%; p < 0.05). No differences were observed in IL-17-treated samples (100.14 + 38.42%). After 48 h, the number of epidermal Langerin-positive cells in IL-17- and TNF-alpha treated samples slightly decreased (94.99 + 36.79% and 101.37 + 23% vs. their controls, respectively). With the combination of both cytokines epidermal LCs strongly decreased (120 + 13.36%).