LEDGF/DFS70, a major autoantigen of atopic dermatitis, is a component of keratohyalin granules

Lens epithelium-derived growth factor/dense fine speckles 70 kDa protein (LEDGF/DFS70) is a transcriptional cofactor, a transcriptional activator, survival factor, and HIV-1 transporter. It is also a major autoantigen in patients with atopic dermatitis (AD), because autoantibodies to this protein are found in approximately 30% of AD patients. To better understand the role of autoantibodies and autoantigens in the pathogenesis of AD, we examined the distribution of LEDGF/DFS70 in the epidermis of normal human skin by light and electron microscopic immunocytochemistry. Increased amounts of LEDGF/DFS70 were located in the nuclei of cells in the basal layer, whereas the cytoplasm of cells in the granular layer stained for LEDGF/DFS70 by light microscopy. Using immunoelectron microscopy, we observed the accumulation of LEDGF/DFS70 in keratohyalin granules (KGs) in the cytoplasm of cells in the granular layer. In addition, Ig heavy chain-binding protein/glucose-regulated protein, 78-kDa (Bip/GRP78), a stress sensing protein in the endoplasmic reticulum, colocalized with LEDGF/DFS70 in the KGs. These results suggest that LEDGF/DFS70 is predominantly located in the nucleus of the basal epidermal cells and translocates into the cytoplasm during differentiation. Once in the cytoplasm, LEDGF/DFS70 accumulates in the KGs in the granular layer. Finally, LEDGF/DFS70, a "nuclear" autoantigen in AD, may play a functional role in the KGs.

Topical tacrolimus for the treatment of inflammatory skin diseases

Chronic inflammatory skin disorders, such as atopic eczema, can cause considerable impairment of life quality. Their treatment is mainly driven by systemic or topical glucocorticosteroids which have the risk of many side effects. Recently, immunosuppressive macrolides which act via the inhibition of cytokine expression in T-lymphocytes have been shown to exert good therapeutic potency in inflammatory skin disorders. Cyclosporin, widely used in transplantation medicine, is also effective in psoriasis and atopic eczema but is not suitable for topical treatment. Tacrolimus (FK506) has been found to be 10-100 times more potent than cyclosporin and to penetrate skin much better due to a lower molecular weight. Initial clinical investigations have shown efficacy of topical tacrolimus in patients with atopic eczema. Large multi-centre studies have proven that long-term therapy with 0.03% and 0.1% tacrolimus ointment reveals effectiveness and safety both in adults and in children with severe atopic eczema. A burning sensation at the site of application is the most frequently observed local side effect. Relevant systemic adverse events were not detected. In Japan and the US, the drug is already licensed for the treatment of atopic eczema. The European admission for the pharmaceutical market is expected in the year 2002. Tacrolimus represents a milestone in topical therapy of inflammatory skin disorders which has so far been dominated by corticosteroid formulations and gives hope for the development of further topical immunosuppressive agents of its class in the future.

High-dose intravenous immunoglobulins: An approach to treat severe immune-mediated and autoimmune diseases of the skin

Adjuvant high-dose intravenous immunoglobulins (IVIgs) are being used increasingly in a range of immune-mediated and autoimmune diseases. Although numerous immunomodulatory mechanisms have been suggested, the exact mechanisms of action are poorly understood. The efficacy of IVIg in certain diseases has been proven in clinical trials, insofar as IVIg is approved as the therapy of choice for Kawasaki syndrome or idiopathic thrombocytopenic purpura. IVIg treatment has been shown to be safe, without the many drug-related adverse effects, including systemic immunosuppression, that are related to corticosteroids and other immunosuppressive agents. Current dermatologic uses of IVIg are increasing, which calls for adequately controlled clinical trials. This review focuses on experiences with IVIg therapy for skin diseases and discusses current opinion concerning its potential immunomodulating mechanisms.

Autoantibodies in atopic dermatitis

Recent progress in the autoimmune aspects of atopic dermatitis has clarified that patients with atopic dermatitis develop IgE-class autoantibodies mainly against intracellular proteins. The cloning of cDNAs encoding autoallergens with human expression cDNA libraries and serum IgE from atopic dermatitis patients has unraveled the molecular characteristics of IgE-binding autoantigens. Some patients with atopic dermatitis also have IgG-class autoantibodies, especially anti-nuclear antibodies. One of the nuclear autoantigens was identified as DFS70/transcription coactivator p75. In addition, p80-coilin in nuclear coiled bodies is also targetted. Several lines of evidence suggest that a subset of atopic dermatitis may be associated with an autoimmune response.

Atopic dermatitis. Perspectives on a manageable disease

Although there is no cure for atopic dermatitis, it can be successfully controlled in most patients. Topical corticosteroids are usually effective, but some patients with recalcitrant disease require phototherapy or use of more potent immunosuppressive agents. Improved understanding of the immunologic basis of atopic dermatitis may provide opportunities for the development of new therapies.

A macrolactam inhibitor of T helper type 1 and T helper type 2 cytokine biosynthesis for topical treatment of inflammatory skin diseases

T lymphocytes play a critical part in inflammatory skin diseases but are targeted by available therapies that have only partial efficacy, significant side-effects, or both. Because psoriasis, atopic dermatitis, and allergic contact hypersensitivity are associated with T helper type 1 (Th1), T helper type 2 (Th2), or mixed Th1-Th2 cell subsets and cytokine types, respectively, there is a need for a better broad-based inhibitor. The macrolactam ascomycin analog, ABT-281, was found to inhibit potently T cell function across species and to inhibit expression of multiple cytokines in human peripheral blood leukocytes which have been found in human skin disease cells and tissues. These included immunoregulatory Th1 (interleukin-2 and interferon-gamma) and Th2 (interleukin-4 and interleukin-5) cytokines. ABT-281 was shown to have potent topical activity (ED50 = 0.6% in acetone/olive oil) in a stringent swine model of allergic contact hypersensitivity, but its potency was markedly reduced compared with ascomycin when administered systemically due to more rapid clearance. Topical application of 3% ABT-281 in acetone/olive oil over 25% of the body surface in swine resulted in undetectable blood levels. Compared with a wide potency range of topical corticosteroids in clinical formulations, 0.3% and 1% ABT-281 ointments profoundly inhibited dinitrochlorobenzene-induced contact hypersensitivity in the pig by 78% and 90%, respectively, whereas super-potent steroids such as clobetasol propionate only inhibited in the 50% range and mild to moderate potency steroids such as fluocinolone acetonide were inactive. The potent topical activity of ABT-281 in swine, its superior efficacy, its rapid systemic clearance following uptake into the bloodstream, and its ability to inhibit cytokine biosynthesis of both Th1 and Th2 cell subsets, suggests that it will have a broad therapeutic value in inflammatory skin diseases, including psoriasis, atopic dermatitis, and allergic contact dermatitis.