Different natural killer (NK) receptor expression and immunoglobulin E (IgE) regulation by NK1 and NK2 cells.

Many studies concerning the role of T cells and cytokines in allergy have been performed, but little is known about the role of natural killer (NK) cells. Accordingly, the expression of co-stimulatory, inhibitory and apoptosis receptors, cytokine profiles and their effect on immunoglobulin isotypes were investigated in polyallergic atopic dermatitis (AD) patients with hyper immunoglobulin E (IgE) and healthy individuals. AD patients showed significantly decreased peripheral blood NK cells compared to healthy individuals. Freshly isolated NK cells of polyallergic patients spontaneously released higher amounts of interleukin (IL)-4, IL-5, IL-13 and interferon (IFN)-gamma compared to healthy individuals. NK cells were differentiated to NK1 cells by IL-12 and neutralizing anti-IL-4 monoclonal antibodies (mAb), and to NK2 cells by IL-4 and neutralizing anti-IL-12 mAb. Following IL-12 stimulation, NK cells produced increased levels of IFN-gamma and decreased IL-4. In contrast, stimulation of NK cells with IL-4 inhibited IFN-gamma, but increased IL-13, production. The effect of NK cell subsets on IgE regulation was examined in co-cultures of in vitro differentiated NK cells with peripheral blood mononuclear cells (PBMC) or B cells. NK1 cells significantly inhibited IL-4- and soluble CD40-ligand-stimulated IgE production; however, NK2 cells did not have any effect. The inhibitory effect of NK1 cells on IgE production was blocked by neutralization of IFN-gamma. Except for CD40, NK cell subsets showed different expression of killer-inhibitory receptors and co-stimulatory molecules between the polyallergic and healthy subjects. These results indicate that human NK cells show differences in numbers, surface receptor and cytokine phenotypes and functional properties in AD.

The prevalence of positive reactions in the atopy patch test with aeroallergens and food allergens in subjects with atopic eczema: a European multicenter study.

BACKGROUND: The atopy patch test (APT) was proposed to evaluate IgE-mediated sensitizations in patients with atopic eczema (AE). OBJECTIVE: The prevalence and agreement with clinical history and specific IgE (sIgE) of positive APT reactions was investigated in six European countries using a standardized method. METHODS: A total of 314 patients with AE in remission were tested in 12 study centers on clinically uninvolved, non-abraded back skin with 200 index of reactivity (IR)/g of house dust mite Dermatophagoides pteronyssinus, cat dander, grass, and birch pollen allergen extracts with defined major allergen contents in petrolatum. Extracts of egg white, celery and wheat flour with defined protein content were also patch tested. APT values were evaluated at 24, 48, and 72 h according to the European Task Force on Atopic Dermatitis (ETFAD) guidelines. In addition, skin-prick test (SPT) and sIgE and a detailed history on allergen-induced eczema flares were obtained. RESULTS: Previous eczema flares, after contact with specific allergens, were reported in 1% (celery) to 34% (D. pteronyssinus) of patients. The frequency of clear-cut positive APT reactions ranged from 39% with D. pteronyssinus to 9% with celery. All ETFAD intensities occured after 48 and 72 h. Positive SPT (16-57%) and elevated sIgE (19-59%) results were more frequent. Clear-cut positive APT with all SPT and sIgE testing negative was seen in 7% of the patients, whereas a positive APT without SPT or sIgE for the respective allergen was seen in 17% of the patients. APT, SPT and sIgE results showed significant agreement with history for grass pollen and egg white (two-sided Pr > /Z/ < or = 0.01). In addition, SPT and sIgE showed significant agreement with history for the other aeroallergens. With regard to clinical history, the APT had a higher specificity (64-91% depending on the allergen) than SPT (50-85%) or sIgE (52-85%). Positive APT were associated with longer duration of eczema flares and showed regional differences. In 10 non-atopic controls, no positive APT reaction was seen. CONCLUSION: Aeroallergens and food allergens are able to elicit eczematous skin reactions after epicutaneous application. As no gold standard for aeroallergen provocation in AE exists, the relevance of aeroallergens for AE flares may be evaluated by APT in addition to SPT and sIgE. The data may contribute to the international standardization of the APT.

Targeting keratinocyte apoptosis in the treatment of atopic dermatitis and allergic contact dermatitis.

BACKGROUND: Activation and skin-selective homing of T cells and effector functions in the skin represent sequential events in the pathogenesis of atopic dermatitis and allergic contact dermatitis. OBJECTIVE: T cell-mediated keratinocyte apoptosis plays a key pathogenetic role in the formation of eczematous dermatitis. IFN-gamma released from activated T cells upregulates Fas on ke-ratinocytes, which renders them susceptible to apoptosis. The lethal hit is given to keratinocytes by means of Fas ligand expressed on the T-cell surface or released to the inflammatory microenvironment. We sought to investigate whether drugs used for the treatment of eczematous disorders interfere with this pathogenic pathway. METHODS: T cell-mediated, Fas-induced keratinocyte apoptosis in a keratinocyte-T cell coculture system serves as an in vitro model of eczematous dermatitis. We tested, in this model, whether immunomodulatory agents (dexamethasone, cyclosporine A, rapamycine, tacrolimus/FK506, intravenous immunoglobulin [IVIG], and theophylline) are able to inhibit apoptosis of keratinocytes. Additionally, skin biopsy specimens from patients with untreated and successfully treated eczematous dermatitis were evaluated for keratinocyte apoptosis. RESULTS: Dexamethasone, cyclosporine A, FK506, rapamycine, and IVIG are inhibitors of keratinocyte apoptosis induced by activated T cells. This effect is mediated by 2 major mechanisms directed on T cells or keratinocytes. T-cell activation was mainly inhibited by dexamethasone, FK506, cyclosporine A, and rapamycine. Interestingly, high-dose dexamethasone and IVIG directly inhibited Fas-mediated keratinocyte apoptosis. In vivo keratinocyte apoptosis was significantly reduced after successful topical treatment of eczematous lesions. CONCLUSION: These results demonstrate mechanisms of action of current treatment approaches and provide a future for more focused therapeutic applications.

The differential fate of cadherins during T-cell-induced keratinocyte apoptosis leads to spongiosis in eczematous dermatitis.

Recently we have shown that T-cell-mediated keratinocyte apoptosis plays a key pathogenetic role in the formation of eczematous dermatitis. Spongiosis, the histologic hallmark of eczematous dermatitis, is characterized by impairment of cohesion between epidermal keratinocytes. It is conceivable that the intercellular junction of keratinocytes is an early target of apoptosis-inducing T cells. In this study, we demonstrate that the induction of keratinocyte apoptosis is accompanied by a rapid cleavage of E-cadherin and loss of coimmunoprecipitated beta-catenin. In situ examination of E-cadherin expression and cellular distribution in acute eczematous dermatitis revealed a reduction in keratinocyte membrane E-cadherin in areas of spongiosis. In contrast, the in vitro and in vivo expression of desmosomal cadherins during early apoptosis remained unchanged. Therefore, induction of keratinocyte apoptosis by skin-infiltrating T cells, subseqent cleavage of E-cadherin, and resisting desmosomal cadherins suggests a mechanism for spongiosis formation in eczematous dermatitis.

Galli-Galli disease: an unrecognized entity or an acantholytic variant of Dowling-Degos disease?

Galli-Galli disease is an inherited disease characterized by slowly progressive and disfiguring reticulate hyperpigmentation of the flexures, clinically and histopathologically diagnostic for Dowling-Degos disease, but also associated with suprabasal, nondyskeratotic acantholysis. A few patients exhibiting these features have been described, mainly in the non-English-language literature, which suggests that Galli-Galli disease is not an entity of its own, as originally thought, but is an acantholytic variant of Dowling-Degos disease. We report a typical case of Galli-Galli disease, which supports this concept.

Food intake of patients with atopic dermatitis.

There is only restricted information about the nutritional behavior of adult patients with atopic dermatitis (AD). Our purpose was to evaluate the food intake in a series of patients with AD with particular consideration of self-reported food intolerance. Particular attention was paid to the risks of nutrient deficiencies. We examined the intake of 28 food items in 116 AD patients with a food-frequency questionnaire (FFQ). For each food item the cohort was divided in two groups according to whether symptoms were reported or not (symptomatic vs. asymptomatic). We found in a series of food items a significant lower food intake among symptomatic patients. Significantly lower intakes were reported by symptomatic patients for dairy products, fish, egg, pork, oranges, non-specified fruits, apples, kiwis, green or red peppers, peanuts and hazelnuts. We concluded that in symptomatic AD patients supplementation with specific nutrients might become mandatory. This is particularly pertinent for calcium, iodine, vitamin C and n-3 fatty acids.

T cells and T cell-derived cytokines as pathogenic factors in the nonallergic form of atopic dermatitis.

A subgroup of patients with atopic dermatitis are known to have normal serum total immunoglobulin E levels, undetectable specific immunoglobulin E, and negative skin prick tests towards allergens. This form of the disease has been termed nonallergic atopic dermatitis. In this study, we found that, among 1151 chronic atopic dermatitis patients, about 10% had normal serum immunoglobulin E levels with no evidence for immunoglobulin E sensitization. We investigated immunologic mechanisms of patients with "allergic" and "nonallergic" atopic dermatitis using peripheral blood and skin biopsy samples. Our data suggest that T cells are likely involved in the pathogenesis of both forms of atopic dermatitis. Skin T cells equally responded to superantigen, staphylococcal enterotoxin B, and produced interleukin-2, interleukin-5, interleukin-13, and interferon-gamma in both forms of the disease. Interleukin-4, however, was not detectable in the skin biopsies of both atopic dermatitis types and was secreted in very low amounts by T cells cultured from the skin biopsies. Moreover, skin T cells from nonallergic atopic dermatitis patients expressed lower interleukin-5 and interleukin-13 levels compared with allergic atopic dermatitis patients. Accordingly, T cells isolated from skin biopsies of atopic dermatitis, but not from the nonallergic atopic dermatitis, induced high immunoglobulin E production in cocultures with normal B cells that was mediated by interleukin-13. In addition, B cell activation with high CD23 expression was observed in the peripheral blood of atopic dermatitis, but not nonallergic atopic dermatitis patients. These data suggest, although high numbers of T cells are present in lesional skin of both types, a lack of interleukin-13-induced B cell activation and consequent immunoglobulin E production in nonallergic atopic dermatitis.

Skin-homing, CLA+ memory T cells are activated in atopic dermatitis and regulate IgE by an IL-13-dominated cytokine pattern: IgG4 counter-regulation by CLA- memory T cells.

Cutaneous lymphocyte-associated Ag (CLA) is a skin-homing receptor displayed by memory/effector T cells recognizing skin-related allergens. Here we demonstrate that peripheral blood CLA+ CD45RO+ T cells in patients with atopic dermatitis (AD) are in vivo activated. They spontaneously proliferate and release an IL-13-dominated Th2 cytokine profile and are capable of inducing IgE in autologous B cells without further activation. The spontaneous cytokine release occurred within the first hour of culture and was not inhibited by cycloheximide or by other immunosuppressive drugs, indicating that cytokine transcription and translation had been completed in vivo. In contrast, the CLA- CD45RO+ T cells from the same patients and from nonatopic controls represented a resting memory T cell subset, secreted borderline quantities of cytokines, and induced IgG4. Polyclonal activation by the anti-CD2/anti-CD3/anti-CD28 mAb mixture generated distinct cytokine patterns in the two memory/effector T cell subsets. CLA+ T cells secreted Th2 cytokines with high IL-13 levels, and the CLA- subset mainly produced IFN-gamma. There was no difference in in vitro activated cytokine pattern between AD patients and nonatopic subjects. These results indicate that the CLA+ memory/effector T cells of AD patients are activated in vivo and play a pivotal role in allergic inflammation by production of IL-13 and induction of IgE Abs. In contrast, the CLA- resting memory T cell population may exert immunoprotective properties toward allergen by high IFN-gamma secretion and induction of IgG4.

The early phase of epidermal barrier regeneration is faster in patients with atopic eczema.

BACKGROUND: Altered epidermal barrier function as determined by transepidermal water loss (TEWL) is a typical feature in patients with atopic eczema (AE). OBJECTIVE: The purpose of this study was to assess the kinetics of epidermal regeneration after barrier perturbation induced by two different stimuli, namely acetone treatment (removal of stratum corneum lipids) and tape stripping (removal of the nonviable stratum corneum). METHODS: Fifteen patients with AE and 12 nonatopic healthy controls were investigated. An area of 9.0 cm2 of clinically normal skin of the forearm flexural side was treated by acetone or tape stripping in a way that an increase in TEWL of 3.5-4.0 times the pretreatment value was achieved. TEWL was recorded directly after perturbation (tO), after 15 min (tl), 3 h (t2), 6 h (t3), 24 h (t4), 48 h (t5), 72 h (t6) and 96 h (t7). RESULTS: The speed of epidermal regeneration was faster after acetone treatment, both in the patient and the control groups, with no significant difference between the two. However, after tape stripping at points t2, t5 and t6, TEWL values relative to tO were significantly lower in atopic skin as compared to normal skin (p < 0.05). CONCLUSION: The faster regeneration of barrier function after tape stripping in patients with AE may be the result of a persisting mild disturbance of barrier function. It may be speculated that repair mechanisms are permanently activated, and therefore barrier recovery is faster. However, a complete restoration of the epidermal barrier function is not achieved, perhaps because of the decreased content of ceramides in atopic skin.

Different reactivity to recombinant Aspergillus fumigatus allergen I/a in patients with atopic dermatitis or allergic asthma sensitised to Aspergillus fumigatus.

We report a clinical study comparing the skin test reactivity to recombinant Aspergillus fumigatus allergen 1 (rAsp fI/a) in patients with atopic dermatitis and A. fumigatus sensitisation (n = 15), A. fumigatus-allergic patients with asthma (n = 10) and healthy control subjects (n = 10). All patients sensitised to A. fumigatus reacted at intradermal skin tests with commercial A. fumigatus extracts in contrast to the healthy subjects. Six out of 10 patients with well-characterised A. fumigatus allergic asthma were sensitised to rAsp fI/a as shown by a positive skin test. The patients with skin test reactivity to rAsp fI/a also showed rAsp f I/a-specific serum IgE as determined by ELISA. None of the patients with atopic dermatitis, healthy control subjects and 4 out of 10 A. fumigatus-allergic asthmatics reacted in intradermal tests to rAsp fI/a. Serologic investigations revealed that these subjects did not express detectable amounts of rAsp fI/a-specific IgE in agreement with the negative skin test results. Extended serologic investigations have not shown significant differences in rAsp fI/a-specific IgA, IgG4 and IgG1 serum levels between atopic dermatitis patients and healthy control subjects. The results suggest that sensitisation to A. fumigatus in patients with atopic dermatitis is not related to the major A. fumigatus allergen I in contrast to the high incidence of sensitisation to Asp fI/a occurring in allergic asthmatics.

Recognition of cholinergic agonists by the muscarinic receptor. 2. Pilocarpine.

The conformational potential energy surface of the muscarinic agonist pilocarpine is studied by molecular mechanics (MMP2) and by semiempirical (AM1) and ab initio self-consistent-field (SCF) calculations. Six minima were located, two of which correspond to the known X-ray structures of pilocarpine. Possible active conformations of pilocarpine are inferred from the potential energy surfaces used in conjunction with the proposed active conformation of muscarine previously obtained from a theoretical model.

Recognition of cholinergic agonists by the muscarinic receptor. 1. Acetylcholine and other agonists with the NCCOCC backbone.

A theoretical model is used to deduce the pharmacologically active conformation of acetylcholine and other agonists interacting with the muscarinic receptor of the parasympathetic and central nervous systems. This is accomplished by replacing the usual dihedral angles tau 1 and tau 2, which define the conformations of cholinergic drugs, with two new geometric parameters more suitable for describing the muscarinic pharmacophore: a characteristic distance, [PQ], and a dihedral angle, PNOQ. Values for these parameters are determined by conformational analysis on semirigid muscarinic agonists using molecular mechanics and ab initio molecular orbital methods. In addition to deducing the active conformation of acetylcholine and other agonists, the model also rationalizes the pattern of stereoselectivity in agonists related to 3-acetoxyquinuclidine (aceclidine) and furnishes a geometric criterion for partial agonism and antagonism.