title: Tumor necrosis factor-alpha and interleukin-17 differently affects Langerhans cell distribution and activation in an innovative three-dimensional model of normal human skin.
abstract: 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 24h 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 24h 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%). By TEM, upon TNF-alpha stimulus LCs appeared with few organelles, mostly mitochondria, lysosomes, and scattered peripherical BGs. Upon IL-17 stimulus, LCs showed a cytoplasm with many mitochondria and numerous BGs close to the perinuclear space and Golgi apparatus, but also at the periphery, at the beginning of the dendrites. The addition of both cytokines did not affect LC ultrastructure. Our study showed that IL-17 induced significant changes in LC ultrastructure, while the combination of both cytokines seems to have a strong chemo-attractant effect on epidermal LCs, supporting the relevance of investigating the interplay between LCs and pro-inflammatory cytokines in the ongoing of the disease.
authors.affiliation: Department of Surgery and Translational Medicine, Section of Clinical Preventive and Oncology Dermatology, Università di Firenze, 50125 Florence, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Prignano
authors.affiliation: Department of Biomedical Sciences for Health, Lab of Structural and Ultrastructural Morphology, Università degli Studi di Milano, 20133 Milan, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Arnaboldi
authors.affiliation: Department of Biomedical Sciences for Health, Lab of Structural and Ultrastructural Morphology, Università degli Studi di Milano, 20133 Milan, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Cornaghi
authors.affiliation: Department of Biomedical Sciences for Health, Lab of Structural and Ultrastructural Morphology, Università degli Studi di Milano, 20133 Milan, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Landoni
authors.affiliation: Department of Surgery and Translational Medicine, Section of Clinical Preventive and Oncology Dermatology, Università di Firenze, 50125 Florence, Italy.
authors.forename: Lara
authors.initials: L
authors.lastname: Tripo
authors.affiliation: I.R.C.C.S. Istituto Ortopedico Galeazzi, 20161 Milan, Italy.
authors.forename: Franz William Baruffaldi
authors.initials: FW
authors.lastname: Preis
authors.affiliation: Department of Biomedical Sciences for Health, Lab of Structural and Ultrastructural Morphology, Università degli Studi di Milano, 20133 Milan, Italy. Electronic address: elena.donetti@unimi.it.
authors.forename: Elena
authors.initials: E
authors.lastname: Donetti
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D020381:Interleukin-17 / Q000494:pharmacology*; D007801:Langerhans Cells / Q000187:drug effects* / Q000276:immunology / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission / Q000379:methods; D008954:Models, Biological; D012867:Skin / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D020381:Interleukin-17; D014409:Tumor Necrosis Factor-alpha
keywords: Dendritic cells; Immunofluorescence; Pro-inflammatory cytokines; Psoriasis; Transmission electron microscopy