Mast cells and atopic dermatitis. Stereological quantification of mast cells in atopic dermatitis and normal human skin

Stereological quantification of mast cell numbers was applied to sections of punch biopsies from lesional and nonlesional skin of atopic dermatitis patients and skin of healthy volunteers. We also investigated whether the method of staining and/or the fixative influenced the results of the determination of the mast cell profile numbers. The punch biopsies were taken from the same four locations in both atopic dermatitis patients and normal individuals. The locations were the scalp, neck and flexure of the elbow (lesional skin), and nates (nonlesional skin). Clinical scoring was carried out at the site of each biopsy. After fixation and plastic embedding, the biopsies were cut into 2 μm serial sections. Ten sections, 30 μm apart, from each biopsy were examined and stained alternately with either toluidine blue or Giemsa stain and mast cell profile numbers were determined. The study yielded the following results: (1) in atopic dermatitis lesional skin an increased number of mast cell profiles was found as compared with nonlesional skin, (2) comparing atopic dermatitis skin with normal skin, a significantly increased number of mast cell profiles per millimetre squared was found in specimens from the neck, (3) staining with toluidine blue yielded a lower number of mast cell profiles than Giemsa staining, (4) the use of Carnoy’s fixative resulted in a lower mast cell profile count than the use of formaldehyde, and (5) there was no statistically significant correlation between the clinical score and the number of mast cell profiles per millimetre squared. Using stereological techniques, this study indicated that mast cells might participate in the inflammatory process in skin leading to atopic dermatitis. Received: 17 April 1996     

Natural killer cell activity in atopic dermatitis

Summary Natural killer (NK) cell activity against K562 cells was studied in 12 male adults with atopic dermatitis (AD). In a 4-h chromium relase microcytotoxicity assay normal NK cell function and its augmentation by interferon (IFN-alpha) were observed in AD patients. Slightly higher NK cell activity was observed in patients with allergic respiratory symptoms. The role of NK cells in the pathogenesis of atopic dermatitis is discussed.Supported by Oy Star Ab and a grant from the Foundation for Allergy Research (Allergiatutkimussäätiö), Finland     

Mast cells of psoriatic and atopic dermatitis skin are positive for TNF-α and their degranulation is associated with expression of ICAM-1 in the epidermis

Abstract The release of cytokines from cutaneous cells may be of major importance in the initiation and development of many inflammatory skin disorders. For example, tumor necrosis factor-alpha (TNF-α), which in healthy skin is found preformed only in mast cells, is able to induce the expression of several adhesion molecules including intercellular adhesion molecule-1 (ICAM-1). Increased expression of ICAM-1 occurs in keratinocytes in lesional skin of psoriasis and atopic dermatitis (AD) and it is considered to be an important initiator of leucocyte/keratinocyte interactions in skin inflammation. We counted the mast cells showing TNF-α immunoreactivity using a double-staining method in nonlesional and lesional skin sections from 12 patients with AD and 12 patients with psoriasis. The percentage of TNF-α⁺ mast cells in lesional and nonlesional AD skin was 36 ± 22% and 21 ± 15% (P < 0.018, paired t-test), respectively, and in psoriatic skin was 16 ± 25% and 15 ± 15%, respectively (P < 0.89, paired t-test). We also cultured whole skin biopsies taken from the healthy-looking skin of psoriatic and AD patients in the presence of mast cell degranulator compound 48/80, which resulted in focal expression of ICAM-1 in the epidermis. In cultured keratinocytes, both histamine and an extract of a human mast-cell line (HMC-1) induced ICAM-1 immunostaining only in occasional cells, but the combination of histamine and the HMC-1 extract resulted in intense ICAM-1 staining in numerous cells. This enhancement of ICAM-1 staining was abolished by preincubation of the HMC-1 extract with anti-TNF-α antibody. These results suggest that the degranulation of mast cells induces the expression of ICAM-1 in keratinocytes probably via TNF-α and histamine. Received: 8 August 1997     

Serum mast cell tryptase is not a useful marker for disease severity in psoriasis or atopic dermatitis

Background  Severity in psoriasis and atopic dermatitis (AD) is commonly assessed with the Psoriasis Area and Severity Index (PASI) and the SCORing Atopic Dermatitis (SCORAD), respectively. Until today no serum marker is available to reflect the clinical scoring in both diseases. As mast cells play an important role in the pathogenesis of early psoriasis and AD, tryptase, a major compound of mast cell granules that is released upon activation, could in principle serve as such a marker.
Objectives  To assess the correlation between serum tryptase and severity of psoriasis and AD as well as the correlation between total IgE levels and severity of AD.
Methods  Serum samples from patients hospitalized for psoriasis and AD were collected at time of admission and time of discharge from hospital. PASI and SCORAD assessments were performed at the same time points. Outpatients presenting with naevi and other benign noninflammatory skin lesions served as control group. Serum tryptase values and total IgE levels of patients with AD were measured using a fluoroenzyme immunoassay technique.
Results  No correlation of serum tryptase level with either the severity of psoriasis or the severity of AD was seen. Total IgE levels in patients with AD at time of admission and discharge from hospital remained the same.
Conclusions  Serum total tryptase did not prove to be a useful tool in assessing severity of psoriasis or AD. Total IgE levels did not correlate with severity of AD.     

Prevalence of comorbidities in atopic dermatitis and psoriasis in the French population

BackgroundAtopic dermatitis (AD) and psoriasis (Pso) are highly prevalent chronic inflammatory skin diseases. They share similarities regarding severity and impact on quality of life but display differences regarding risk factors, comorbidities, and pathogenesis.ObjectiveThis study sought to assess the prevalence of AD and Pso among the French population, along with associated comorbidities, and to compare these data with those of the age- and gender-adjusted French population with neither AD nor Pso.MethodsThe survey was conducted by a polling institute between September 1 and November 30, 2016, with proportional quota sampling being applied to render the study population representative of the French population. In all, 20 012 individuals were selected from among 900,000 internet users aged ≥ 15 years.ResultsOverall, 20,012 adults (48.8% men; 51.2% women) completed a digital questionnaire. The prevalence of AD was 4.65% [95% confidence interval (CI) 4.36%–4.94%] and that of Pso was 4.42% [95% CI: 4.14%–4.71%]. More AD patients presented ≥ 1 comorbidity compared to subjects without AD (57.04% vs. 49.2%, P < 0.0001) and more Pso patients presented ≥ 1 comorbidity compared to subjects without Pso (60.68% vs. 49.05%, P < 0.0001). After adjustment for gender and age, hypertension and dyslipidemia, a greater prevalence of osteoarticular, respiratory and psychiatric diseases was noted in both AD and Pso patients, whereas increased prevalence of obesity was seen only in Pso patients. The prevalence of components of metabolic syndrome was higher among Pso than AD patients.ConclusionFurther studies are required to consolidate these findings, to better characterize the entire spectrum of AD and Pso comorbidities, and to better identify determinants and risk factors, along with targeted therapies.     

肥大细胞在特应性皮炎发病中的研究进展

特应性皮炎是一种与遗传过敏素质有关的慢性、复发性、瘙痒性、炎症性皮肤疾病，其病因复杂，发病机制尚未明确。近年来，随着对特应性皮炎直接相关的效应细胞及效应分子，特别是肥大细胞及其表达的细胞因子的深入研究，逐步明确肥大细胞在特应性皮炎炎症过程中迁移、聚集、局部数量增多的机制，以及肥大细胞与嗜酸粒细胞、T细胞之间相互作用的关系。其结果将有助于进一步理解特应性皮炎皮肤炎症的细胞基础，并可能为临床治疗提供新的靶点。     

Expression of CD30 on T helper cells in the inflammatory infiltrate of acute atopic dermatitis but not of allergic contact dermatitis

Abstract  The CD30 molecule has been proposed as a marker for a subset of CD4⁺CD45RO⁺ (memory) T cells with potent B cell helper activity producing IL-5 and IFN-γ and as a specific marker for Th2 cells. Recently, an association has been demonstrated between elevated serum levels of soluble CD30, which is shed by CD30⁺ cells in vitro and in vivo, and atopic dermatitis but not respiratory atopic disorders or allergic contact dermatitis. We studied the expression of CD30 in the inflammatory infiltrate of atopic dermatitis compared with that of allergic contact dermatitis, with special regard to skin disease activity (acute vs subacute/ chronic). Biopsies were obtained from 16 patients suffering from atopic dermatitis (acute n = 6, subacute/ chronic n = 10), from 7 patients with acute allergic contact dermatitis and from 5 positive patch-test reactions. Paraffin-embedded as well as snap-frozen material was stained with anti-CD30 and anti-CD45RO mAbs according to standard procedures. Double-staining procedures for CD30CD3, CD30CD4, CD30CD45RO and CD30CD68 were also performed. Abundant CD45RO⁺ cells were detected both in atopic dermatitis and in allergic contact dermatitis lesions. We found scattered CD30⁺ cells in only one of six formalin-fixed paraffin-embedded acute atopic dermatitis biopsies, but in all of the respective snap-frozen specimens, possibly because CD30 expression on atopic dermatitis infiltrating cells is weak and sensitive to formalin fixation and paraffin embedding. CD30CD3 and CD30CD4 double staining identified CD30⁺ cells to be helper T lymphocytes. No significant CD30 expression (either in paraffin-embedded or in frozen material) could be found in subacute/chronic atopic dermatitis lesions or in any of the specimens of allergic contact dermatitis. The results suggest a specific regulatory function of CD30⁺ T cells in acute atopic dermatitis. With respect to the view that CD30 is a marker for Th2 cells, our observations confirm previous findings that Th2 cells predominate in the infiltrate particularly of acute atopic dermatitis. CD30 expression in acute atopic dermatitis but not in acute allergic contact dermatitis might be helpful in the histological differentiation of these disorders and in the further characterization of atopy patch testing. Received: 1 April 1998 / Received after revision: 28 May 1998 / Accepted: 3 July 1998     

特应性皮炎光疗进展

特应性皮炎(atopic dermatitis,AD)是一种具有家族遗传倾向的慢性、复发性、炎症性皮肤病.光疗法在AD的治疗中一直占有较为重要的地位.近年来随着对AD病因学和发病机制的深入了解,以及光疗法在皮肤科应用研究的进展,AD的光治疗法有了一些新策略,现将其作一概述.     

Mast cell tryptase and chymase in developing and mature psoriatic lesions

The number and distribution of mast cells in nonlesional and lesional skin samples from 13 psoriatic patients were analyzed enzyme- and immunohistochemically. Mast cell tryptase was stained with the sensitive substrate Z-Gly-Pro-Arg-4-methoxy-2-naphthylamide, and chymase with Suc-Val-Pro-Phe-MNA and monoclonal B7 anti-chymase antibody. In addition, healthy-looking skin from 27 psoriatic patients was tape-stripped resulting in induction of the Köbner response in 9 patients. Sequential biopsies were taken before and after (7, 14 and 21 days) tape-stripping, and both tryptase and chymase were stained enzyme-histochemically. In nonlesional psoriatic skin, 70 ± 24% (mean ± SD) of the mast cells contained chymase enzyme activity, and 78 ± 18% chymase immunoreactivity. About 10% of the chymase-immunoreactive cells lacked chymase activity. In lesional psoriatic skin, tryptase-positive cells were increased in number throughout the dermis but especially beneath the epidermis. Chymase immunoreactivity paralleled the tryptase activity, whereas chymase activity was strongly diminished both in terms of mast cell numbers and in staining intensity in the papillary dermis. The apparent inactivation of chymase may be due to the action of the chymase inhibitors, ₁-antitrypsin and ₁-antichymotrypsin, localized immunohistochemically in mast cells of lesional and nonlesional psoriatic skin. In the developing psoriatic lesion, mast cells displaying chymase activity were already 27–38% decreased in number in the upper dermis on day 7 after tape-stripping, along with the first clinical signs of psoriasis. Earliest alterations in tryptase-positive cells were observed on day 14 as increased mast cell contacts with the epidermis combined with only a slight increase in mast cell numbers in the upper dermis. During the development of a psoriatic lesion, TC mast cells (tryptase⁺, chymase⁺) increase in number in the upper dermis, but chymase becomes inactive at an early stage. The abundant presence of active trypase but inactive chymase in the upper dermis may have a potential role in psoriasis since both of these enzymes can process several biologically active peptides and proteins.     

IgE-positive epidermal Langerhans cells in allergic contact dermatitis lesions provoked in patients with atopic dermatitis

Summary To see whether or not IgE-bearing epidermal Langerhans cells are specific to skin lesions of atopic dermatitis (AD), we performed immunohistochemical and immunoelectron microscopic examinations of dinitrochlorobenzene (DNCB) contact dermatitis lesions provoked in uninvolved skin of eight patients with AD. In all of the eight examined, IgE-positive epidermal Langerhans cells were observed in the DNCB dermatitis lesions. Typical staining of anti-IgE was absent in the epidermis of normal-appearing skin of five patients with AD. Thus, it is likely that IgE positive epidermal Langerhans cells non-specifically occur in different eczematous diseases provoked in patients with AD.     

银屑病与特应性皮炎的T细胞免疫失衡机制研究进展

银屑病和特应性皮炎是常见的以T细胞介导免疫炎症和角质形成细胞异常分化为特征的炎症性疾病.两种疾病在免疫发病机制、临床特征、组织病理、共患病和治疗方法方面有很多共性,但也存在差异.两种疾病的相似性为表皮角质形成细胞对T细胞产生的细胞因子发生异常反应,其增殖和分化发生改变,这也是两种疾病表型的主要原因.但两种疾病的T细胞极...     

Enhanced procoagulant acticity of mononuclear leukocytes in patients with atopic dermatitis and psoriasis

Fibrin deposition is an important histopathological feature of inflammatory skin lesions and is mediated in part, by procoagulants generated by mononuclear leucocytes (MNL). We examined whether MNL from patients with atopic dermatitis or psoriasis generate enhanced procoagulant activity (PCA). MNL isolated from the peripheral blood of 15 healthy control individuals, 15 patients with atopic dermatitis and 15 patients with psoriasis were incubated for 24 h in the presence or absence of bacterial lipopolysaccharide (LPS). MNL or the cell culture supernatants were then added to recalcified human plasma to determine the clotting time. We found that in both atopic dermatitis and psoriasis MNL cultured in the presence or absence of LPS expressed greatly enhanced PCA (p<0.01 to <0.002). Supernatants from MNL cultures from patients with psoriasis, but not those from patients with atopic dermatitis, also generated augmented PCA (p<0.002). In psoriasis, PCA normalized after successful topical treatment with anthralin. We conclude that enhanced PCA is a characteristic feature of MNL in both atopic dermatitis and psoriasis. In psoriasis the enhanced PCA is directly related to disease activity.This paper contains data from the doctoral thesis of H. W.     

Ceramide profiles of the uninvolved skin in atopic dermatitis and psoriasis are comparable to those of healthy skin

Ceramides are sphingolipids consisting of sphingoidbases, which are amide-linked to fatty acids. In the stratum corneum, they represent the major constituent of the free extractable intercellular lipids and play a significant role in maintaining and structuring the water permeability barrier of the skin. Using thin layer chromatography, which represents the method of the first choice in analyzing the stratum corneum ceramides, at least seven classes can be distinguished. Each ceramide class contains various species, which have the same head group and different chain lengths. As in many other skin disorders, atopic dermatitis and psoriasis show derangements in content and profile of the ceramides. Such derangements were reported for both the lesional involved as well as for the normal-appearing uninvolved skin. In this study, we focused on investigating the stratum corneum ceramides of the uninvolved skin in atopic dermatitis and psoriasis patients compared to healthy skin. The aim of the investigations was to explore possible significant and specific differences which can be accomplished for purposes of early diagnostics. The skin lipids were collected by means of an in vivo topical extraction procedure using an extraction mixture consisting of n-hexane and ethanol, (2:1). An automated multiple development-high performance thin layer chromatography (AMD-HPTLC) method with photodensitometric detection were applied to separate the ceramides and to estimate their contents. For studying their molecular profile within each ceramide class, a new method of normal phase HPLC with atmospheric pressure chemical ionization mass spectrometry were used. The results obtained by AMD-HPTLC exposed no significant alterations regarding the relative composition of the major stratum corneum lipids and primarily the ceramides. In addition, the mass spectrometric profiles within each ceramide class were similar in the patients and the healthy control subjects. In conclusion, this study revealed that the normal-appearing uninvolved skin of atopic dermatitis and psoriasis patients does not prove significant or specific deficiencies with respect to the free extractable major stratum corneum lipids and mainly the ceramides, when compared to healthy skin. Thus, they cannot be used for diagnostic purposes. Furthermore, our data are not consistent with the concept that impairments in the ceramide composition represent an obligate etiologic factor for both diseases.     

Selective Cannabinoid Receptor-1 Agonists Regulate Mast Cell Activation in an Oxazolone-Induced Atopic Dermatitis Model

BackgroundMany inflammatory mediators, including various cytokines (e.g. interleukins and tumor necrosis factor [TNF]), inflammatory proteases, and histamine are released following mast cell activation. However, the endogenous modulators for mast cell activation and the underlying mechanism have yet to be elucidated. Endogenous cannabinoids such as palmitoylethanolamide (PEA) and N-arachidonoylethanolamine (anandamide or AEA), were found in peripheral tissues and have been proposed to possess autacoid activity, implying that cannabinoids may downregulate mast cell activation and local inflammation.ObjectiveIn order to investigate the effect of cannabinoid receptor-1 (CB1R) agonists on mast cell activation, AEA-derived compounds were newly synthesized and evaluated for their effect on mast cell activation.MethodsThe effects of selected compounds on FcεRI-induced histamine and β-hexosaminidase release were evaluated in a rat basophilic leukemia cell line (RBL-2H3). To further investigate the inhibitory effects of CB1R agonist in vivo, an oxazolone-induced atopic dermatitis mouse model was exploited.ResultsWe found that CB1R inhibited the release of inflammatory mediators without causing cytotoxicity in RBL-2H3 cells and that CB1R agonists markedly and dose-dependently suppressed mast cell proliferation indicating that CB1R plays an important role in modulating antigen-dependent immunoglobulin E (IgE)-mediated mast cell activation. We also found that topical application of CB1R agonists suppressed the recruitment of mast cells into the skin and reduced the level of blood histamine.ConclusionOur results indicate that CB1R agonists down-regulate mast cell activation and may be used for relieving inflammatory symptoms mediated by mast cell activation, such as atopic dermatitis, psoriasis, and contact dermatitis.     

Urinary histamine in severe atopic dermatitis

Summary Urinary histamine was studied in 11 patients with severe atopic dermatitis and 17 controls, as well as in seven atopics prior to and 6 months following hyposensitization. No statistically significant differences were found between the groups. Urinary histamine seems to be of no value as an indicator of disease activity in atopic dermatitis.     

Soluble CD14 but not interleukin-6 is a new marker for clinical activity in atopic dermatitis

Summary Levels of soluble IL-2 receptors, IL-6, soluble CD23, soluble CD14 and ECP (eosinophilic cationic protein) were measured as markers of T-cell, B-cell, monocyte and eosinophilic leucocyte activation in 26 patients with atopic dermatitis (AD) on admission to (A) and at discharge from (D) the Department of Dermatology in Zurich. The serum levels of sIL-2R, IL-6, sCD23, sCD14 and ECP were significantly elevated in AD patients in comparison with the normal values of healthy donors. A significant decrease in sIL-2R (p=0.0093) and in sCD14 (p=0.0134) levels was demonstrated between A and D, correlating with the improvement in the skin intensity score (SIS). In addition, a significant correlation of the sCD14 levels and the SIS at A was demonstrated (p=0.0415). These results also incriminate monocytes in the pathogenesis of AD, indicating that, besides sIL-2R and ECP, SCD14 could also be a possible marker for the disease activity.     

Treatment of severe atopic dermatitis with extracorporeal photopheresis

Extracorporeal photopheresis using UVA irradiation of enriched lymphocytes in the presence of 8-methoxypsoralen (8-MOP) as a photoactivatable substrate has been employed for the treatment of several immunologically mediated disorders. We report on the first three patients subjected to extracorporeal photopheresis for severe atopic dermatitis. All patients had a lifelong history of atopic skin inflammation, and their disease had finally become resistant to well-established therapeutic regimes. Extracorporeal photopheresis resulted in a marked clinical improvement in the skin lesions of all patients. The decrease in cutaneous inflammatory activity became evident by the end of the second photopheresis cycle. In two patients skin lesions had virtually disappeared after the fifth treatment cycle, while in the third patient a lasting and substantial improvement in pruritus and erythema was achieved. Clinical remission was stable under maintenance therapy with prolonged intervals between photopheresis sessions. Therapeutic efficacy was reflected by a marked reduction in IgE serum levels in all three patients, while serum concentration of IgG, IgM and IgA as well as the profile of circulating lymphocytes remained essentially unchanged. No clinical signs of immunosuppression or other severe adverse events became evident. Collectively, our preliminary results indicate that extracorporeal photopheresis may interfere with the pathomechanisms leading to atopic dermatitis and therefore should be considered as a treatment modality for severe forms of this recalcitrant disorder.     

Mast cell chymase in experimentally induced psoriasis

Mast cell chymase can have a pro‐inflammatory or an immunosuppressive function in psoriasis, but the outcome may depend on the level of chymase activity. Therefore, mast cells showing chymase activity (Chy_act) and immunoreactivity (Chy_prot) were studied during the Köbner reaction (0 days, 2 h, 1 day, 3 days and 7 days) of psoriasis induced by the tape‐stripping technique. Also, the effect of recombinant human chymase (rh‐chymase) or human LAD2 mast cells (LAD2) on the ³H‐thymidine uptake of psoriatic peripheral blood mononuclear cells (PBMC) or total T cells was studied. The Chy_act/Chy_prot ratio tended to be higher in all time‐point biopsies in the Köbner‐negative (n = 10) than ‐positive (n = 8) group (P = 0.073), although chymase activity decreased significantly at 2 h to 1 day only in the Köbner‐negative group. rh‐chymase (0.05–0.5 μg/mL) stimulated to a varying extent PBMC in eight out of nine cultures, but in all cultures 5 μg/mL rh‐chymase turned the stimulation towards inhibition. The effect of rh‐chymase on T cells varied from stimulation to inhibition, but in 11 of 15 cultures rh‐chymase, at least at 5 μg/mL, produced a change to inhibition. In co‐cultures, LAD2 inhibited PBMC in the absence of soybean trypsin inhibitor (SBTI). In the presence of SBTI, LAD2 stimulated PBMC in the majority of seven cultures. In summary, the psoriatic immunopathogenesis may be promoted at low, but controlled at high, activity status of chymase.     

中国特应性皮炎诊断和治疗指南

本指南是中华医学会皮肤性病学分会免疫学组在参考国内外文献的基础上共同讨论制定的,制订过程中邀请了部分儿科专家参与.本指南供国内皮肤科同行在诊疗中参考,并将在今后进一步修订.