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Skin levels of arachidonic acid-derived inflammatory mediators and histamine in atopic dermatitis and psoriasis.

Since the biochemical events leading to cutaneous inflammation in atopic dermatitis and psoriasis are unknown, we studied the levels of arachidonic acid-derived mediators of inflammation as well as histamine in the suction blister fluid obtained from lesional and nonlesional skin of patients with these dermatoses. Mediator levels were determined radioimmunologically. Skin from healthy controls and uninvolved skin from patients contained very low or unmeasurable levels of the 5-lipoxygenase metabolite of arachidonic acid, leukotriene (LT) B4. In contrast, higher levels of LTB4-like immunoreactivity were detected in suction blister fluid from lesional atopic dermatitis skin, and even higher concentrations occurred in psoriasis lesions. LTB4-like immunoreactivity from atopic dermatitis suction blister fluid cochromatographed on reverse-phase high-pressure liquid chromatography with authentic LTB4, thus excluding cross-reaction of the LTB4-antibody with arachidonic acid or monohydroxyeicosatetraenoic acids. In contrast, suction blister concentrations of the cyclooxygenase metabolite of arachidonic acid prostaglandin (PG) E2 showed no significant differences between lesional and nonlesional patient skin and healthy control skin. PGD2 determined as a stable metabolite could not be detected in these samples. Histamine concentrations in lesional skin were within normal range. The elevated levels of the potent proinflammatory and immunomodulating mediator LTB4 could be involved in the pathogenesis of cutaneous inflammation in atopic dermatitis and psoriasis. In addition, they might explain the therapeutic efficiency of glucocorticosteroids, which among other actions inhibit the release of arachidonic acid from phospholipid stores by blocking the enzyme phospholipase A2. However, the specificity of disease expression in atopic dermatitis and psoriasis must be due to factors other than cutaneous LTB4 elevation.

Adolescent↗

Type 4 phosphodiesterase inhibitors have clinical and in vitro anti-inflammatory effects in atopic dermatitis.

Increased cyclic AMP-phosphodiesterase activity in peripheral blood leukocytes is associated with the immune and inflammatory hyperreactivity that characterizes atopic dermatitis. Atopic phosphodiesterase has high sensitivity to a variety of enzyme inhibitors, suggesting an increased therapeutic advantage. The objective of this study was to use in vitro assays to identify a potent phosphodiesterase inhibitor and then to investigate its effectiveness in treating atopic dermatitis. Leukocyte enzyme activity was measured by radioenzyme assay, whereas prostaglandin E2 and interleukins 10 (IL-10) and 4 (IL-4) were measured in 24-h culture supernatants of mononuclear leukocytes by immunoassays. The effect of a topical phosphodiesterase inhibitor on atopic dermatitis lesional skin was assessed by double-blind, paired comparisons of active drug and placebo ointments applied to symmetrically involved sites over a 28-d period. Using in vitro, assays, we demonstrated the ability of selective high-potency phosphodiesterase inhibitors to reduce prostaglandin E2, IL-10, and IL-4 production in atopic mononuclear leukocyte cultures. We selected the Type 4 phosphodiesterase inhibitor, CP80,633, based on its inhibitory potency, for clinical testing by topical, bilateral paired comparisons in 20 patients with atopic dermatitis and demonstrated significant reductions of all inflammatory parameters. Phosphodiesterase inhibitors modulate several pathways contributing to the exaggerated immune and inflammatory responses, which characterize atopic dermatitis. This in vivo demonstration of anti-inflammatory efficacy may provide a useful alternative to the over-reliance on corticosteroid therapy in atopic disease.

Administration, Topical↗

Basophil mediator release in atopic dermatitis.

Basophils have been implicated as a source of histamine and pro-inflammatory eicosanoids in atopic dermatitis. However, mechanisms regulating basophil mediator release are not understood. An H3 receptor involved in the control of histamine synthesis and release has been identified in nervous tissue. In this study we have investigated 1) release of histamine, leukotriene C4, and prostaglandin D2 from anti-immunoglobulin E (IgE)-stimulated basophils of adults with atopic dermatitis and unaffected individuals and 2) specific H3 receptor-dependent basophil mediator release, using an H3 receptor agonist and antagonist. Basophil-rich leukocyte fractions were prepared by dextran sedimentation of venous blood from 19 patients with atopic dermatitis (five male, 14 female, mean age 30.6 years, range 19-59 years) and 15 unaffected individuals (five male, 10 female, mean age 27.6 years, range 19-50 years). Anti-IgE (0.78-78.0 micrograms/ml) stimulation of basophils induced a concentration-dependent release of histamine and leukotriene C4, but not prostaglandin D2. Histamine release was maximally induced by 7.8 micrograms/ml anti-IgE with no significant (Mann-Whitney U test) difference between atopic basophils (n = 17; 43.65 +/- 4.16% mean +/- SEM) and normal basophils (n = 13; 52.23 +/- 4.39%). LTC4 release was maximal from atopic basophils incubated with 2.6 micrograms/ml anti-IgE (n = 5; 0.99 +/- 0.29 pg/10(6) cells) and from normal basophils incubated with 0.78 microgram/ml anti-IgE (n = 5; 25.38 +/- 5.79 pg/10(6) cells). Anti-IgE-stimulated release of leukotriene C4 from atopic basophils was significantly less than from normal basophils at all concentrations (p < 0.05). Basophils were co-incubated with anti-IgE (2.6 and 7.8 micrograms/ml) and either the H3 receptor agonist, (R)alpha-methylhistamine (10(-8) and 10(-7) M), or the H3 receptor antagonist thioperamide (10(-6) and 10(-5) M). Neither drug modulated anti-IgE-induced release of histamine (atopics, n = 10; normals, n = 8). These results indicate 1) that basophils from adults with atopic dermatitis release the same amount of histamine as, but less leukotriene C4 than, basophils of unaffected adults and 2) that H3 receptors are not involved in anti-IgE release of histamine from basophils. These data do not support a role for increased basophil release of histamine as a mediator in the itch and erythema of atopic dermatitis in adults.

Adult↗

Experimental photoallergic contact dermatitis: a mouse model.

We have induced photoallergic contact dermatitis in mice to 3,3',4',5 tetrachlorosalicylanilide (TCSA), chlorpromazine and 6-methylcoumarin. These compounds are known to produce photoallergic contact dermatitis in humans. The photoallergic contact dermatitis reaction in the mouse is immunologically specific viz. mice photosensitized to TCSA react, by photochallenge, to that compound and not to chlorpromazine, and conversely. The reaction requires UVA at both sensitization and challenge. It appears to be T-cell mediated in that it can be passively transferred to syngeneic mice by lymph node cells from actively sensitized mice, the histology of the reactions resembles that of classic allergic contact dermatitis in mice, challenge reactions are seen at 24 but not at 4 hr, and photoallergic contact dermatitis can be induced in B-cell deficient mice. The availability of a mouse model for the study of photo-ACD will facilitate the identification of pertinent control mechanisms and may aid in the management of the disease. It is likely that a bioassay for photoallergens of humans can be based on this mouse model.

Animals↗

Kathon biocide: manifestation of delayed contact dermatitis in guinea pigs is dependent on the concentration for induction and challenge.

The potential of Kathon biocide, an aqueous solution containing, as active ingredients (a.i.), a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one (14.4% a.i.), to produce delayed contact dermatitis, a sensitization response, was evaluated in outbred Hartley guinea pigs by a modified Buehler's occluded epicutaneous patch technique. The relationship of the response as a function of induction/elicitation concentrations was investigated. Groups of guinea pigs received 9 induction doses of the biocide, 3 times a week, at concentrations ranging from 25-2000 ppm a.i. These guinea pigs were challenged with the biocide at concentrations ranging from 20-2000 ppm a.i., and the application sites were scored for erythema 24 and 48 h after the challenge. The incidence of delayed contact dermatitis in induced guinea pigs was dependent on both the induction and challenge concentrations. The EC50 (concentration at which delayed contact dermatitis was seen in 50% of the population) for induction at a challenge concentration of 2000 ppm a.i., a nonirritating concentration, was estimated to be 88 ppm a.i. with a slope of 3.47 probits/unit log concentration. The EC50 for elicitation at an induction concentration of 1000 ppm a.i. was estimated to be 429 ppm a.i. with a slope of 2.74 probits/unit log concentration. These data demonstrate that for Kathon biocide, there is an induction/elicitation concentration dependency for delayed contact dermatitis response, and there is a "no response concentration" zone where the biocide can be used without concern for clinically significant delayed contact dermatitis. In comparison with a previous study, these data also suggest that the number of induction doses may be an important factor in demonstrating the sensitization potential of a chemical.

Animals↗

Beta adrenergic receptor binding on polymorphonuclear leukocytes in atopic dermatitis.

It has been postulated that the patient with atopic dermatitis has defective beta adrenergic receptor function. However, a more generalized defect is suggested by the observation that cyclic AMP generation is diminished in these patients following stimulation with both isoproterenol and PGE1. To determine the nature of this abnormality, we measured beta adrenergic receptor binding directly on polymorphonuclear leukocyte membranes using the radiolabeled beta adrenergic antagonist (-) [3H]dihydroalprenolol (DHA). DHA binding was studied in 6 mild and 9 moderate-to-severe atopic dermatitis patients, and 8 normal controls using a subsaturating concentration of DHA (0.5 nM) to estimate receptor affinity and a saturating concentration of DHA (30 mM) to determine the total number of receptors per cell. No significant differences (p greater than .05) were found in the total number of receptors per PMN between the control population (805 +/- 95) and the mild atopic dermatitis patients (745 +/- 91) or the moderate to severe group (621 +/- 79). In addition, no significant differences in receptor affinity were found among any of the 3 study groups. These findings suggest that beta receptor binding in atopic dermatitis is normal. Reduced cyclic AMP generation in atopic dermatitis PMN leukocytes would appear to be due to a defect distal to the beta adrenergic receptor itself.

Adult↗

A comparative study of allergic and primary irritant contact dermatitis with dinitrochlorobenzene (DNCB) in dogs.

Attempts were made to induce allergic contact dermatitis in dogs, a species generally considered poorly responsive to experimental allergic contact dermatitis. Yound Beagles were sensitized to 2,4 dinitrochlorobenzene (DNCB) by multiple intradermal injections. Two weeks after sensitization, these dogs were challenged topically with 0.1% DNCB by a standard closed-patch technique. Sensitization evidenced by various degrees of reaction following challenge was established in all of 14 pups used, while 7 nonsensitized control pups did not react to challenge. Primary irritant contact dermatitis was induced in the skin of nonsensitized Beagle pups by 1%, 5%, and 10% solutions of DNCB. In allergic contact dermatitis the sites of challenge were grossly indurated, erythematous, and edematous. Histologically at these sites there was an infiltration of mononuclear cells which reached maximum intensity at 3 to 4 days. Accumulations of lymphoid cells were marked around sweat galnds and hair follicles. Penetration of leukocytes into these cutaneous adnexa was associated with degenerative processes in their cellular structures. Mononuclear cell infiltration into the epidermis was mild. Spongiosis was observed in the epidermis, but vesicle formation was rare. In primary irritant contact dermatitis gross lesions were characterized by severe erythema, edema, and gangreen of the skin. Microscopically, the main lesions were necrosis of the epidermal cells, separation of the epidermis from the dermis, dermal edema, and massive infiltration of the dermis with polymorphonuclear cells.

Administration, Topical↗

Hyperproduction of IFN-gamma by CpG oligodeoxynucleotide-induced exacerbation of atopic dermatitis-like skin lesion in some NC/Nga mice.

Under conventional conditions, NC/Nga mice spontaneously develop an atopic dermatitis (AD)-like skin lesion accompanied by immunoglobulin E (IgE) hyperproduction and the expression of T helper 2 (Th2) cytokines. CpG DNA activates a strong interferon-gamma (IFN-gamma)-dominated T helper 1 (Th1) response, while inhibiting Th2-dependent allergies. In this study, we examined whether CpG oligodeoxynucleotide (ODN) could prevent the development of the skin lesions in NC/Nga mice. Sixteen of 26 NC/Nga mice did not exhibit dermatitis after CpG ODN was administered intraperitoneally every 2 wk for a total of five times. CpG ODN administration induced IFN-gamma production, which inhibited the production of Th2 cytokines (interleukin (IL)-4, IL-5, and IL-13) in both spleen and lymph node cells and culminated in a decrease in the serum IgE level. These data suggest that the CpG ODN has a therapeutic effect against AD; however, some mice (10 of 26) treated with CpG ODN exhibited an exacerbation of dermatitis accompanied by the hyperproduction of IFN-gamma, although Th2 cytokines were suppressed. These results suggest that the suppression of Th2 cytokines may not completely prevent dermatitis and that IFN-gamma may play a role in developing dermatitis in some NC/Nga mice.

Animals↗

Nickel-elicited systemic contact dermatitis from a peripheral intravenous catheter.

Nickel-elicited systemic contact dermatitis is a well-known entity, although it is far less common than allergic contact dermatitis. In most of the cases, the main way of nickel administration is oral. Clinical manifestations are miscellaneous including pompholyx, diffuse exanthema, flexural dermatitis or baboon syndrome. Systemic nickel dermatitis induced by venous catheters is very uncommon, but it is probably underdiagnosed. We report here 2 patients with diffuse recurrent maculopapular rash corresponding to nickel-elicited systemic contact dermatitis. They were both perfused during the last episode with the assistance of a peripheral polyurethane venous catheter during or just before the cutaneous eruption. At the base of the catheter, there was a small metallic eyelet on which dimethylglyoxime test was positive, indicating a release of nickel. Then, we measured nickel release in normal use conditions and found high nickel levels, although the manufacturer denied that nickel could be released. This diagnosis is important to know because such exanthema often occurred during postoperative or postpartum period. Its frequency is probably underestimated because it is often considered as a cutaneous drug reaction. To our knowledge, only 2 cases have been reported in the literature.

Adult↗

Dosage and adverse effects of topical tacrolimus and steroids in daily management of atopic dermatitis.

Since 1999, combination therapy with tacrolimus and topical steroids has been widely used for the treatment of adolescent/adult-type atopic dermatitis. In order to determine the clinical doses of topical tacrolimus and steroids for daily treatment of atopic dermatitis and to elucidate their beneficial and adverse effects, we analyzed the clinical data from 215 patients with atopic dermatitis who were more than 16 years old. Less than 70 g of tacrolimus and less than 15 g of steroids were applied to 90% of the patients on the face and neck, and less than 75.8 g of tacrolimus and less than 322 g of steroids were applied to 90% of the patients on the trunk and extremities during the six-month treatment period. Topical tacrolimus is much more frequently used on face and neck lesions (99.1%); in only 39.5% of cases was it used on the trunk and extremities. The majority of patients improved after six months of the combination topical therapy; however, atopic dermatitis was not controlled in 6% of the patients. The combination therapy did not seem to increase the risk of cutaneous infections; however, the incidence of herpes simplex infection on the face and neck was 2.8% at pre-treatment and slightly increased to 4.7% during the therapy. The incidence of all steroid-induced adverse effects was reduced both in frequency and intensity with a decrease in the dose of topical steroids through simultaneous tacrolimus application. Combination therapy with topical tacrolimus and steroids is useful for treating atopic dermatitis, but a small percentage of the patients still cannot be satisfactorily treated. For such patients, adjustments of the dose and rank of topical steroids and tacrolimus and other therapeutic adjuncts are necessary.

Administration, Cutaneous↗

Effect of standard medication on quality of life of patients with atopic dermatitis.

Patients with atopic dermatitis present with debilitating symptoms, including pruritus and subsequent excoriation, which significantly reduces their quality of life (QOL). At present, the standard therapy for atopic dermatitis constitutes a topical steroid and/or a topical immunomodulator, an emollient and an oral antihistamine, although few studies have reported the effect of this treatment regimen on QOL. The current study aimed to verify the efficacy of the standard therapy for both clinical symptom severity and patient QOL, assessed using the validated Skindex-16 questionnaire. Atopic dermatitis patients receiving the standard therapy (n=771) were enrolled in the current phase IV, multicenter, 12-week, open-label study. The Rajka and Langeland scale (used to rate the severity of atopic dermatitis symptoms) and the Skindex-16 QOL questionnaire were completed at weeks 0 (baseline), 4 and 12. Of 415 patients completing the questionnaire at all time points (per-protocol population), 95.2% were prescribed the antihistamine fexofenadine HCl 60 mg. There were significant improvements in symptoms, emotions and functioning scale scores at weeks 4 and 12 compared with baseline (P<0.005). Discomfort associated with itching, as assessed by item 1 on the Skindex-16, improved over the treatment period (score decreased by >or=1 and >or=2 in 75.2% and 50.9% of patients, respectively). Significant (P<0.005) improvements from baseline in global scores were also observed at weeks 4 and 12, and for week 12 compared with week 4. Severity scores improved significantly (P<0.005) from weeks 0-4 and from weeks 4-12. The standard therapy was generally well tolerated with only mild adverse events reported (0.5%). These data suggest that patients with atopic dermatitis and associated pruritus experience significant improvements in both symptom severity and QOL when receiving standard therapy.

Adult↗

Psychological profile of patients with atopic dermatitis.

Tests designed to measure psychopathological characteristics common to the neurotic population were administered to patients with atopic dermatitis, patients with other dermatological disorders and to a control group of normal individuals. The parameters tested were manifest anxiety, neurosis, extroversion, depression, hypochondriasis and hysteria. The scores were statistically analyzed. The results showed that patients with atopic dermatitis responded significantly differently from patients with other dermatological diseases and from the control group in specific psychometric scales. Moreover, patients with skin conditions other than atopic dermatitis also responded significantly differently from the control group. The study clearly shows that patients with atopic dermatitis have a characteristic psychological profile not shared by the other two groups. The atopic dermatitis patients tend to be in a state of high manifest anxiety, depressed, neurotic and hypochondriac.

Adolescent↗

Low nickel diet in the treatment of patients with chronic nickel dermatitis.

Of 28 patients with chronic nickel dermatitis 17 experienced aggravation following oral ingestion of 2.5 mg nickel, but not a placebo tablet. The dermatitis of 9 of the 17 patients improved during a period of 6 weeks on a low nickel diet. The dermatitis of 7 of the 9 patients flared again when a normal diet was resumed. Nickel excretion over a 24-h period was measured for 14 of the 17 patients by atomic absorption spectrophotometry before, during, and after the diet. Reduced excretion was seen during the diet with no statistically significant difference between patients whose dermatitis improved during the diet and those whose dermatitis showed no change.

Chronic Disease↗

The prevalence of accentuated palmoplantar markings and keratosis pilaris in atopic dermatitis, autosomal dominant ichthyosis and control dermatological patients.

The prevalence of keratosis pilaris and accentuated palmoplantar marking was evaluated in 61 patients with atopic dermatitis, 35 patients with dominant ichthyosis vulgaris and 247 other dermatological cases taken as controls. Our data showed that (1) these features are of no diagnostic significance for atopic dermatitis and (2) they are significantly more frequent in patients with ichthyosis vulgaris without associated eczema than in those with atopic dermatitis. Consequently, they should be considered as part of the phenotype of ichthyosis vulgaris rather than attributed to a concomitant atopic dermatitis as suggested by some. These findings should be taken into account when evaluating atopic dermatitis or ichthyosis. To assess the frequency of scaling under winter weather conditions, 155 control subjects were also examined for evidence of visible desquamation and 25.8% showed slight but definite scaling.

Adolescent↗

Humoral and cellular immunity in children with active and quiescent atopic dermatitis.

Serum immunoglobulins (IgG, IgM, IgA and IgE), C3, and C4, T lymphocyte subsets, neutrophil chemotaxis and natural killer cell-mediated cytotoxic activity were measured in 34 children with atopic dermatitis and 31 healthy controls. Twenty-four patients were re-evaluated when their dermatitis was quiescent. Serum levels of IgG, IgM and IgE were significantly higher in the patients with atopic dermatitis than in the controls, while levels of serum IgA did not differ significantly between the two groups. C3 levels were lower in the patients than in the controls and correlated inversely with clinical disease severity. C4 levels were not significantly altered. Numbers of suppressor/cytotoxic T lymphocytes and polymorphonuclear leukocyte chemotaxis were significantly reduced in the atopic patients. There was a significant inverse correlation between the natural killer cell-mediated cytotoxic activity and the severity and extent of the dermatitis. These results support the hypothesis that atopic dermatitis is connected with a defect in cellular immunity.

Antibody Formation↗

Studies on the role of leukotrienes in murine allergic and irritant contact dermatitis.

A specific peptidoleukotriene receptor antagonist, Ro 23-3544, was tested for its efficacy in modulating DNFB-induced allergic and croton oil-induced irritant contact dermatitis in mouse ears. Treatment shortly after elicitation of the dermatitis, and for up to 5 days thereafter, was moderately effective in suppressing DNFB-induced ear swelling in a dose-dependent fashion. Daily pre-treatment of the ears for 1 week caused a more marked reduction of DNFB-induced ear swelling during the first 48 h after elicitation. No reduction, but rather an increase in ear swelling was observed with croton oil-induced dermatitis. These results indicate that peptidoleukotrienes play a role in the early stages of elicitation of murine allergic, but not irritant contact dermatitis and that a specific receptor antagonist can only partially reverse the effect of peptidoleukotrienes once the dermatitis is established.

Animals↗

Effect of BN 52021, a platelet activating factor antagonist, on experimental murine contact dermatitis.

A specific platelet activating factor (PAF) receptor antagonist, BN 52021, was tested for its efficacy in modulating DNFB-induced allergic and croton oil-induced irritant contact dermatitis in mouse ears. Oral treatment of the animals in the elicitation phase of the dermatitis caused a significant suppression of DNFB-induced ear swelling. The compound was less active in croton oil-induced irritant dermatitis and ineffective when given during the sensitization phase of allergic dermatitis. The results provide indirect evidence for the involvement of PAF in the effector phase of murine contact dermatitis of the allergic type and also the irritant type to a lesser extent.

Animals↗

Assessment of a contact-plate sampling technique and subsequent quantitative bacterial studies in atopic dermatitis.

The aerobic bacterial flora of 20 patients with atopic dermatitis and 19 control subjects was extensively sampled using the Williamson and Kligman scrub technique and a contact-plate method (cysteine lactose electrolyte deficient media). Comparison of the two quantitative techniques showed that the contact plate is a reliable and convenient alternative to the scrub technique for the quantification of Staphylococcus aureus, micrococci and coagulase negative staphylococci. Quantification of bacterial flora using both techniques showed high rates of colonization by S. aureus on both involved and clinically normal skin of patients with atopic dermatitis. A linear increase in S. aureus counts with increasing severity of dermatitis was found. In contrast, diphtheroids showed a trend of decreasing isolation rates and counts as the severity of the dermatitis increased. Isolation rates and absolute counts for micrococci/coagulase negative cocci were unaffected by the severity of the dermatitis.

Adult↗