sq-23377 and Psoriasis

Neutrophil (polymorphonuclear) granulocytes (PMN) have been shown to contribute to the pathogenesis of psoriasis by releasing interleukin-17 and LL37-DNA complexes via neutrophil extracellular traps (NETs), webs of chromatin strands decorated with antimicrobial peptides, in psoriatic skin. Fumaderm. To elucidate the effect of FAE treatment on human psoriasis and healthy donor NET formation.. Among the compounds present in the FAE formulation, dimethyl fumarate (DMF) pretreatment of human psoriasis and healthy donor PMN resulted in a consistent inhibitory effect on NET formation in response to phorbol 12-myristate 13-acetate but not to platelet activating factor and ionomycin. This effect was l-glutathione (GSH) dependent and involved a decrease in reactive oxygen species (ROS) production, a key event in NET formation. In contrast, G-protein-coupled signalling and protein synthesis were not involved. Monomethyl fumarate (MMF) was found to slightly reduce ROS production without affecting NET formation.. We report DMF as a potent, stimulus-specific, GSH- and ROS-dependent modulator of NET formation. Our results support the notion that modulation of NET formation contributes to the beneficial effects of FAEs in a variety of inflammatory conditions.

Topics: Analysis of Variance; Antioxidants; Caspases; Cells, Cultured; Dermatologic Agents; Dimethyl Fumarate; Dose-Response Relationship, Drug; Extracellular Traps; Fumarates; Glutathione; GTP-Binding Proteins; Humans; Ionomycin; Platelet Activating Factor; Psoriasis; Reactive Oxygen Species; Superoxides; Tetradecanoylphorbol Acetate

Systemic cyclosporin A and tacrolimus are effective treatments for psoriasis. Cyclosporin A and tacrolimus block T cell activation by inhibiting the phosphatase calcineurin and preventing translocation from the cytoplasm to the nucleus of the transcription factor nuclear factor of activated T cells (NFAT). Inhibition of T cell activation is thought to account for their therapeutic action in psoriasis. We investigated whether nonimmune cells in human skin express calcineurin and NFAT1 and whether cyclosporin A and tacrolimus block activation of calcineurin/NFAT in epidermal keratinocytes. The expression patterns of the principal components of calcineurin/NFAT signaling pathway in normal human skin and psoriasis were determined by immunohistochemistry. We assessed calcineurin/NFAT activation in cultured keratinocytes by measuring the degree of nuclear localization of calcineurin and NFAT1 using immunofluorescence/confocal microscopy and assessed if cyclosporin A and tacrolimus blocked nuclear translocation of these proteins. A variety of cell types in normal and psoriatic skin expressed calcineurin and NFAT1, but expression was particularly prominent in keratinocytes. The principal cyclosporin A and tacrolimus binding proteins cyclophilin A and FKBP12 were also expressed by keratinocytes and nonimmune cells in skin. NFAT1 was predominantly nuclear in normal basal epidermal keratinocytes. Increased nuclear localization of NFAT1 was observed in suprabasal keratinocytes within lesional and to a lesser extent nonlesional psoriatic epidermis compared to normal skin (p = 0.001 and p = 0.03, respectively), suggesting increased activation of calcineurin in psoriatic epidermal keratinocytes. Agonists that induce keratinocyte differentiation, specifically 12-0-tetradecanoyl-phorbol-13-acetate (TPA) plus ionomycin, TPA, and raised extracellular calcium, induced nuclear translocation of NFAT1 and calcineurin in keratinocytes that was inhibited by pretreatment with cyclosporin A or tacrolimus. In contrast in human dermal fibroblasts, TPA plus ionomycin or TPA did not significantly alter the proportion of nuclear-associated NFAT1. These data provide the first evidence that calcineurin is functionally active in human keratinocytes inducing nuclear translocation of NFAT1 and also indicate that regulation of NFAT1 nuclear translocation in skin is cell type specific. Inhibition of this pathway in epidermal keratinocytes may account, in part, for the therapeutic effect of cyc

Topics: Biological Transport; Calcineurin; Calcineurin Inhibitors; Carcinogens; Cell Differentiation; Cell Membrane; Cell Nucleus; Cells, Cultured; Cyclophilin A; Cyclosporine; DNA-Binding Proteins; Enzyme Inhibitors; Fibroblasts; Humans; Immunosuppressive Agents; Ionomycin; Ionophores; Keratinocytes; NFATC Transcription Factors; Nuclear Proteins; Psoriasis; Signal Transduction; Skin; Tacrolimus; Tacrolimus Binding Protein 1A; Tetradecanoylphorbol Acetate; Transcription Factors

Psoriasis vulgaris is a skin disease potentially mediated by pro-inflammatory cytokines produced by type 1 lesional T cells. The capability of individual T cells to produce these cytokines in lesional skin is not known. In this study we measured the ability of lesional and peripheral blood T cells to produce intracellular interferon-gamma, tumor necrosis factor-alpha, interleukin-2, interleukin-4, and interleukin-10 proteins as detected by flow cytometric analysis. Cytokine synthesis was induced by activation with ionomycin/phorbol myristate acetate (in the presence of Brefeldin A, which inhibits the exocytosis of these cytokines). After stimulation, we found relatively high percentages of epidermal CD8 and CD4 T cells capable of producing interferon-gamma, tumor necrosis factor-alpha, and interleukin-2, whereas few T cells, < 11%, expressed interleukin-4 or interleukin-10. Hence both CD8+ and CD4+ T cells are capable of type 1 effector functions (TC1 and TH1, respectively). This activation scheme was repeated on peripheral blood T cells from psoriatic patients versus healthy controls, where we also found a type 1 bias. In order to evaluate quantitatively the type 1 cytokine bias, we compared the frequency of type 2 interleukin-4 producing versus type 1 interferon-gamma producing T cells in our assay and found a shift towards type 1 producing cells. This shift reveals a type 1 differentiation bias in both lesional areas and in the peripheral blood, which may indicate an imbalance within the T cell population, which is contributing to the chronic or sustained immunologic activation of T cells found in this disease.

Topics: Adult; Aged; CD4-CD8 Ratio; Cell Differentiation; Cytokines; Epidermal Cells; Female; Humans; Interferon-gamma; Interleukin-2; Ionomycin; Lymphocyte Activation; Male; Middle Aged; Psoriasis; T-Lymphocytes; T-Lymphocytes, Cytotoxic; Tetradecanoylphorbol Acetate; Th1 Cells; Tumor Necrosis Factor-alpha