Repetitive scratching and noxious heat do not inhibit histamine-induced itch in atopic dermatitis

BACKGROUND: Repetitive scratching is the most common behavioural response to itch in atopic dermatitis (AD). Patients with chronic itch often report that very hot showers inhibit itch. We recently reported that scratching and noxious heat stimuli inhibit histamine-induced itch in healthy subjects. However, no psychophysical studies have been performed in AD to assess the effects of repetitive heat pain stimuli and scratching on histamine-induced itch. OBJECTIVES: To examine the effects of repetitive noxious heat and scratching on itch intensity in patients with AD using quantitative sensory testing devices. METHODS: Itch was induced with histamine iontophoresis in 16 patients with AD in both lesional and nonlesional skin as well as in 10 healthy subjects. Repetitive noxious heat and scratching were applied 3 cm distal to the area of histamine iontophoresis. Subjects rated their perceived intensity of histamine-induced itch with a computerized visual analogue scale. RESULTS: Our results demonstrate that repetitive noxious heat and scratching do not inhibit itch intensity in lesional and nonlesional AD skin but do so in healthy skin. Of note, both these stimuli increase itch intensity in lesional AD skin. CONCLUSIONS: Our results strongly suggest that scratching and noxious thermal stimuli have a different effect upon histamine-induced itch perception in patients with AD when compared with healthy controls. This difference may be associated with both peripheral and central sensitization of nerve fibres in AD.     

Impaired sweating function in adult atopic dermatitis: results of the quantitative sudomotor axon reflex test

Summary Background Impaired sweating is thought to be a cause of barrier dysfunction in atopic dermatitis (AD). Objectives To examine the sweating function in AD in a quantitative manner. Methods We investigated the sweating response of lesional and non‐lesional skin of adult patients with AD by a quantitative sudomotor axon reflex test in which the axon reflex is stimulated by acetylcholine iontophoresis. Sweat volume on the volar aspect of the forearm was measured in 18 adult patients with AD and in 40 non‐atopic controls; five patients with Sjögren's syndrome were also studied as disease comparators. We also evaluated the sweating function in four AD patients after topical corticosteroid therapy. Latency time, direct (DIR) sweat volume and axon reflex‐mediated indirect (AXR) sweat volume were the variables studied. Results The latency time in AD patients was significantly prolonged and AXR sweat volume significantly reduced compared with those in non‐atopic control subjects. The latency time and AXR sweat volume of lesional AD skin were significantly more prolonged and reduced, respectively, than those of non‐lesional skin. In contrast, the DIR sweat volume of lesional or non‐lesional AD skin induced by direct stimulation with acetylcholine was only slightly reduced when compared with that in non‐atopic controls. Latency time and sweat volumes of lesional and non‐lesional AD skin improved after topical corticosteroid therapy. Conclusions These results suggest that the impaired sweat response in AD is attributable to an abnormal sudomotor axon reflex, which is reversed by topical corticosteroid administration.     

Expression of CCL1 and CCL18 in atopic dermatitis and psoriasis

Background.  Recent studies have shown that chemoattractive proteins play an important role in the organization of the innate and adaptive immune responses. There are some reports that chemokine (C‐C motif) ligand (CCL)1 and CCL18, members of a family of chemoattractive proteins, have increased expression in atopic dermatitis (AD). Aim.  To evaluate the quantity and pattern of CCL1 and CCL18 expression in lesions and blood of patients with AD, and compare them with those of patients with psoriasis. Methods.  Biopsy specimens were taken from atopic skin and normal‐appearing skin of patients with AD and from the psoriatic skin only of patients with psoriasis. Quantitative real‐time PCR analysis and immunohistochemistry of CCL1 and CCL18 expression were performed, and the quantities of expressed CCL1 and CCL18 in acute AD were compared with those of normal‐appearing atopic skin and psoriatic skin. The serum level of CCL1 and CCL18 was assessed by ELISA. Results.  Expression of CCL1 mRNA and protein was significantly higher in the acute lesional skin of patients with AD than in their nonlesional skin or in the lesional skin of patients with psoriasis. Both CCL18 mRNA and protein were abundant in acute AD lesions and in psoriatic lesions, but were lower in the nonlesional skin of patients with AD. The serum levels of CCL1 and CCL18 were not different in patients with AD and patients with psoriasis. Conclusions.  CCL1 is a chemokine that is associated with AD. Both CCL1 and CCL18 may play important roles in the initiation and progression of atopic skin inflammation.     

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.     

Quantitative analysis of bikunin-laden mast cells in follicular eruptions and chronic skin lesions of atopic dermatitis

Bikunin, an inhibitor of serine proteases, is widely distributed in human tissues, including the skin, and may inhibit tryptase and modulate allergic inflammation. The purpose of the present study was to compare follicular eruptions (FE), so-called atopic skin or perifollicular accentuation, with atopic dermatitis (AD) lesions (ADL) by immunohistochemical analysis using antibodies to bikunin and tryptase. Immunohistochemically, bikunin was colocalized with tryptase in dermal mast cells, and a small quantity of bikunin was also deposited in the intercellular spaces in FE and ADL. The number of bikunin-laden mast cells per 0.78 mm(2) of skin was 78.1+/-7.1 (mean+/-SEM, n=14) in FE, 25.4+/-2.3 (n=10) in normal skin from children and infants, 91.3+/-11.8 (n=10) in ADL, 25.6+/-4.8 (n=5) in nonlesional skin of AD, and 27.8+/-2.0 (n=13) in normal adult skin. The difference between FE and normal control skin from children and infants, between FE and nonlesional skin of AD, and between lesional and nonlesional skin of AD were significant. Based on the above findings and the occasional presence of spongiosis and lymphocyte infiltration, in FE moderate inflammation is apparent histopathologically even though little inflammation is apparent clinically.     

T cells and mast cells as a major source of interleukin-13 in atopic dermatitis

BACKGROUND: Interleukin (IL)-13 is a T-cell-derived cytokine that shares several functions with IL-4, including the induction of immunoglobulin E synthesis. Recent studies suggest that cytokines expressed locally in the skin play several critical roles in atopic dermatitis (AD), however, little is known about the role of IL-13 in AD lesions. OBJECTIVES: The present study was designed to characterize the involvement of IL-13 in AD in the skin and peripheral blood mononuclear cells (PBMC). METHODS: Using lesional and nonlesional skin from adult AD patients and normal skin from healthy volunteers, we performed RT-PCR, in situ RT and immunostaining to determine the IL-13 expression at the mRNA and protein levels. The actual numbers of IL-13 expressing cells in biopsy specimens were counted under the microscope. IL-13 mRNA expression in PBMC from AD patients and healthy volunteers was examined by RT-PCR analysis. RESULTS: IL-13 mRNA expression was detected by RT-PCR in lesional and nonlesional skin and in PBMC from AD patients, but not in normal skin or PBMC from healthy volunteers. In AD lesional skin, numerous IL-13 mRNA-positive cells were demonstrated by in situ RT, and similar numbers of IL-13-positive cells were also detected immunohistochemically. Smaller numbers of IL-13-positive cells were observed in AD nonlesional skin and in normal skin. The differences in the numbers of IL-13-expressing cells between lesional and nonlesional skin were statistically significant. Double immunostaining revealed that IL-13 was produced in approximately 40% of T cells and 20% of mast cells in AD lesional skin, suggesting that T cells and mast cells are major sources of IL-13 in AD lesions. CONCLUSION: IL-13 may play a local as well as a systemic role in the development of AD lesions.     

Electrode design for skin electroporation with minimal nerve stimulation

Itch is one of the major symptoms of various skin diseases. Although specific neuronal pathways for itch were identified both peripherally and centrally, they still fail to explain itchy skin observed in patients with chronic pruritus. In this study, sensitivity to itchy and painful stimuli in patients with atopic dermatitis was investigated. Histamine-prick evoked enormous itch in their lesional skin, while less itch in their non-lesional skin than healthy subjects. Flare reaction was not significantly different between their non-lesional and lesional skin, rather smaller than healthy subjects. Mechanical (pin-pricks), electrical, heat and chemical (injection of pH3 solution) stimuli evoked intense itch in their lesional skin and partly also in their non-lesional skin, while only pain in healthy subjects. Itch was also, but not intensely, evoked in healthy subjects by injection of pH3 solution after sufficient histamine stimuli. These results confirm the presence of itchy skin with hyperkinesis (excessive itch by itchy stimuli) and allokinesis (itch by non-itchy stimuli) in patients with atopic dermatitis, which is so intense that painful stimuli cannot suppress but evoke itch, and suggest that neuronal sensitization is involved in their itch not only peripherally but also centrally.     

Molecular analysis of Malassezia microflora in the lesional skin of psoriasis patients

Systemic and focal infections by microorganisms have been known to induce or exacerbate psoriasis. To investigate the role of Malassezia species in the development of psoriasis, we analyzed the Malassezia microflora in psoriasis patients using a nested polymerase chain reaction (PCR) assay, and compared it with those in atopic dermatitis (AD) patients and healthy subjects. Fungal DNA was directly collected from the lesional and non-lesional skin of the trunk of 22 psoriasis patients by applying a transparent dressing. The extracted DNA was amplified by using specific primers designed for the PCR in the intergenic spacer or internal transcribed spacer area of the ribosomal RNA. All nine of the Malassezia species were detected at different rates from the 22 psoriasis patients. The overall detection rates in lesional and non-lesional skin of M. restricta, M. globosa and M. sympodialis were high (96%, 82% and 64%, respectively), whereas the detection rates of the other species were relatively low. However, there was no difference in the rates between lesional and non-lesional skin areas. The average number of Malassezia species detected in overall sites of the psoriasis patients was 3.7 +/- 1.6 species, although this fact showed no correlation with the severity of the symptoms. The number of Malassezia species detected was 4.1 +/- 1.9 in the AD patients, and 2.8 +/- 0.8 in the healthy subjects, suggesting that the skin microflora of psoriasis patients and AD patients show greater diversity than that of healthy subjects.     

Skin absorption through atopic dermatitis skin: a systematic review

Patients with atopic dermatitis (AD) have skin barrier impairment in both lesional and nonlesional skin. They are typically exposed daily to emollients and intermittently to topical anti‐inflammatory medicaments, thereby increasing the risk of developing contact allergy and systemic exposure to chemical ingredients found in these topical preparations. We systematically searched for studies that investigated skin absorption of various penetrants, including medicaments, in patients with AD, but also in animals with experimentally‐induced dermatitis. We identified 40 articles: 11 human studies examining model penetrants, 26 human studies examining AD drugs, and three animal studies. We conclude that patients with AD have almost twofold increased skin absorption compared with healthy controls. There is a need for well‐designed epidemiological and dermatopharmacokinetic studies that examine to what extent AD causes patients to be systemically exposed to chemicals compared with nonatopic dermatitis.     

Reactions to intradermally injected substance P and topically applied mustard oil in atopic dermatitis patients.

Skin reactions and itch or burning pain sensations following intradermal injection of the neuropeptide substance P and topical application of the substance P releasing agent mustard oil were studied in 20 atopic dermatitis patients and 20 healthy controls. Changes in skin blood flow were measured with a Laser Doppler flowmeter. Areas of wheal and flare reactions were evaluated planimetrically. Simultaneous with Laser Doppler flowmeter measurements, subjective itch and burning pain ratings were verbally reported on a category partitioning scale at 10-second intervals. Substance P evoked dose-dependent wheal, flare, and itch reactions in both patients and controls. However, substance P doses of 10(-9) -10(-11) mol elicited smaller flares in patients than in the controls whereas the wheal sizes were similar in both groups. Substance P-induced itch ratings were lower in patients at a dose of 10(-10) mol, and the onset of itching was delayed at all substance P levels applied. Mustard oil elicited similar neurogenic inflammatory reactions in both groups, although pain sensations were significantly delayed in atopic dermatitis patients at two mustard oil concentrations, which is further indication of a desensitization of afferent nerve endings contributing to the neurogenic inflammatory reactions in the skin of these patients.     

Plaque psoriasis vs. atopic dermatitis and lichen planus: a comparison for lesional T-cell subsets, epidermal proliferation and differentiation

BACKGROUND: T-cell infiltration in plaque psoriasis has recently been an important subject of investigation. Interestingly, comparative analyses of the disease-specific composition of the lesional T-cell infiltrate in plaque psoriasis and other inflammatory dermatoses have only sparsely been performed. OBJECTIVES: To compare plaque psoriasis vs. atopic dermatitis and lichen ruber planus with respect to T-cell subsets, epidermal proliferation and keratinization. PATIENTS AND METHODS: Biopsies were taken from untreated lesional skin of patients, six with psoriasis, six with atopic dermatitis and six with lichen planus. T-cell subsets (CD4+, CD8+, CD45RO+, CD45RA+, CD2+, CD25+), an epidermal proliferation (Ki-67) and a keratinization marker (K10) were stained immunohistochemically and quantified using image analysis. RESULTS: The high number of CD8+ T cells (52 +/- 13 cells mm(-1)) found in the psoriatic epidermis was not found in the epidermis of atopic dermatitis (9 +/- 4), nor in the epidermis of lichen planus (34 +/- 10). The other T-cell subsets in the epidermis and dermis showed no statistically significant differences between psoriasis and atopic dermatitis. In contrast to the limited presence of CD4+, CD8+ and CD2+ in the psoriatic dermis (110 +/- 19, 27 +/- 9, 127 +/- 41, cells mm(-1), respectively), more impressive numbers of these cells were observed in the dermis of lichen planus (300 +/- 53, 144 +/- 38, 272 +/- 48, respectively). CD45RO+ memory effector T-cell counts were significantly higher in the epidermis of lichen planus (39 +/- 10) than in psoriasis (19 +/- 5). Psoriatic epidermis proved to have major keratinocyte hyperproliferation (247 +/- 26 cells mm(-1) lamina basalis), as compared with atopic dermatitis (134 +/- 15) and lichen planus (128 +/- 20). Furthermore, a marked decreased expression of keratin 10 was observed in psoriasis (41% of epidermal area) contrary to atopic dermatitis (70%). CONCLUSIONS: Psoriatic epidermis exhibits a pronounced CD8+ epidermotropism with accompanying epidermal hyperproliferation and abnormal keratinization, which changes are only minimally expressed in atopic dermatitis and lichen planus. In plaque psoriasis, substantially fewer activated CD4+ and CD8+ T cells in the dermis and less CD45RO+ T cells in the epidermis are present in comparison with lichen ruber planus.     

Injury downregulates the expression of the human cathelicidin protein hCAP18/LL‐37 in atopic dermatitis

Please cite this paper as: Injury downregulates the expression of the human cathelicidin protein hCAP18/LL‐37 in atopic dermatitis. Experimental Dermatology 2009; 19: 442–449. Abstract: Reduced production of antimicrobial peptides was proposed to contribute to susceptibility for skin infections in atopic dermatitis (AD). Focusing on the human cathelicidin protein, hCAP18, the aim of the present study was to explore whether reduced hCAP18 expression is a constitutive trait in AD and if established inducers affect the expression of hCAP18 in the skin of AD. First, we compared levels of hCAP18 mRNA between lesional skin in AD and psoriasis and verified significantly lower expression of hCAP18 mRNA in AD. In non‐lesional skin, however, there was no difference between AD, psoriasis and healthy, indicating that there is no constitutive defect in the production of hCAP18 in AD patients. In healthy skin, hCAP18 was reported to be rapidly induced following wounding and here we verified this pattern in healthy controls and in psoriasis. In AD lesions, however, the expression of hCAP18 mRNA was markedly suppressed following wounding. Obviously, the inflammation in AD lesions neutralizes the expected induction of hCAP18 and even induces suppression. Notably, the mechanism to upregulate hCAP18 following vitamin D treatment was functional in lesional as well as in non‐lesional AD indicating that the CAMP gene is normally regulated in this respect. In addition, cultured primary keratinocytes from non‐lesional skin of psoriasis, AD and healthy skin, upregulated hCAP18mRNA following treatment with vitamin D. Itching is a hallmark of AD and scratching inevitably injures the skin. Failure to upregulate hCAP18 in eczema following injury is likely to affect antimicrobial protection and tissue repair in AD.     

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     

银屑病皮损区和非皮损区AgNOR的定量观察

应用核仁组成区银染蛋白（ＡｇＮＯＲ）染色方法，对１２例银屑病患者皮损区和非皮损区表皮细胞进行了观察。并和非银屑病患考的正常皮肤及慢性皮炎类皮损各１２例进行了比较。结果显示银屑病患者皮损区和非皮损区ＡｇＮＯＲ值均数均明显高于正常皮肤和慢性皮炎类皮损，而后两者相类似。作者认为ＡｇＮＯＲ在组织学上可能有助于银屑病和一些慢性皮炎类疾病的鉴别。     

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     

Quantitative analysis of nerve growth factor (NGF) in the atopic dermatitis and psoriasis horny layer and effect of treatment on NGF in atopic dermatitis

BACKGROUND AND OBJECTIVE: The expression of nerve growth factor (NGF) is known to increase in the skin of patients with atopic dermatitis (AD) and is related to disease aggravation. In the present study, we measured skin NGF levels in AD patients and determined whether they correlate to AD severity as well as treatment effects. METHODS: NGF in the horny layer (horn NGF) of skin lesions found on the cubital fossa of AD patients was collected via tape stripping and measured using ELISA before and after 2 and 4 weeks following initiation of treatments. Itching and eruptions on the lesions were also evaluated. Peripheral blood eosinophil count, serum LDH level and total serum IgE level were also examined. RESULTS: The level of NGF was significantly higher in AD patients than in healthy controls, and correlated with the severity of itch, erythema, scale/xerosis, eosinophil count, and LDH level. The NGF level decreased significantly at 2 and 4 weeks of treatment with olopatadine, a histamine H(1) receptor antagonist, and/or topical steroid. The reduction in NGF correlated with the decrease in the severity of itching and erythema, papule, scale/xerosis and lichenification of the lesion, eosinophil count, and LDH level. In psoriatic lesional skin with itch, the horn NGF was significantly higher than in non-lesional skin of psoriasis, but the value was lower than NGF in atopic skin. CONCLUSIONS: The level of horn NGF was found to reflect the severity of itching and eruptions in AD. Therefore, quantification of NGF in the samples collected directly from the horny layer appears to be useful in assessing severity and therapeutic effects in AD.     

Langerhans cell hyperplasia and IgE expression in canine atopic dermatitis

Langerhans cells appear to be critical for IgE-mediated allergen capture and presentation in human atopic dermatitis. The present study sought to determine whether epidermal (i.e Langerhans cells) and dermal dendritic cells in the skin of dogs with atopic dermatitis are hyperplastic and expressed surface IgE. Frozen sections of lesional or nonlesional atopic and normal control canine skin were immunostained with CD1a-, CD1c-, and IgE-specific monoclonal antibodies. The enumeration of cells was performed by morphometry in both the epidermis and the dermis. Cell counts were compared with each individual’s total serum IgE levels. Higher numbers of epidermal and dermal dendritic cells were present in atopic dogs than in normal control animals. Epidermal Langerhans cell counts were significantly higher in lesional than in nonlesional atopic specimens. IgE⁺ dendritic cells were observed in lesional atopic epidermis and dermis, and nonlesional atopic dermis, but not in normal control skin specimens. The percentages of IgE⁺ dendritic cells were correlated with each patient’s total serum IgE levels. These results demonstrate dendritic cell hyperplasia and IgE expression in canine atopic dermatitis. Increased epidermal Langerhans cell counts in lesional specimens suggest an epidermal allergen contact in canine atopic dermatitis.     

Patients' perception of itch induced by histamine, compound 48/80 and wool fibres in atopic dermatitis.

Itch and flare responses were investigated in 32 patients with atopic dermatitis (AD) and in 32 healthy controls. Itch was induced chemically by intradermal injections of histamine (1, 3.3, 10 and 100 micrograms/ml) and compound 48/80 (10 micrograms/ml) into non-lesional skin and mechanically by wearing a woollen sweater. Continuous recording of itch intensity allowed the calculation of itch duration (ID), maximal itch intensity (Imax) and a "total itch index" (Tii). The itch responses were significantly increased in AD patients compared with controls for wool fibres and one of the histamine concentrations (10 micrograms/ml), but not for the remaining three histamine concentrations or compound 48/80. Conversely, the flare response was significantly smaller in AD patients than in controls for the two strongest histamine solutions and compound 48/80. Significant dose-response relationships were found between histamine concentration and each of ID, Imax, Tii and flare in both patients and controls. The slope of the flare-regression line was significantly steeper in controls than in AD patients, whereas the slopes of the itch-regression lines did not differ significantly between the two groups, i.e. their ability to discriminate between weak and strong histamine concentrations did not differ significantly. No increased skin mast cell releasability in vivo to compound 48/80 was shown in AD patients compared with controls. The itch and flare responses of AD patients did not correlate significantly with clinical itch intensity, eczema score or serum IgE level.     

Decreased expression of filaggrin in atopic skin

The amounts of the epidermal proteins filaggrin, involucrin, cystatin A and Ted-H-1 antigen produced during the terminal differentiation of keratinocytes were immunohistochemically measured in lesional and nonlesional skin of atopic dermatitis (AD) patients. In addition, the amount of filaggrin in the skin of the inner surface of the upper arm of AD patients (nonlesional skin) and normal controls, obtained by punch biopsy, was measured by an enzyme-linked immunosorbent assay (ELISA) technique. The immunohistochemical study showed that all four proteins were decreased in lesional skin. By contrast, only filaggrin was decreased in nonlesional skin of AD patients. The ELISA showed that the amount of filaggrin in the skin of the inner surface of the upper arm was 2.48 ± 0.45 μg/7 mm ² ( n = 8) in AD patients, which was 32% of that in the normal controls (7.7 ± 0.55 μg/7 mm ² ; n = 4). This decrease in filaggrin production in atopic skin may be one of the reasons why atopic skin can easily become dry, because filaggrin is thought to be the precursor protein of the emollient factors in the stratum corneum. The evidence that only the expression of filaggrin was suppressed in AD patients, though the genes of filaggrin and involucrin are localized to a very restricted portion of the same gene 1q21, indicates that the filaggrin gene does not share regulatory elements with the involucrin gene. Received: 12 July 1995     

蛋白酶激活受体2在特应性皮炎患者皮损组织中的表达与分布研究

目的:观察蛋白酶激活受体(PAR)2及其相关蛋白在特应性皮炎(AD)患者皮损组织中的表达,探索AD的发病机制.方法:AD患者15例,正常对照10例,应用免疫组化方法(ABC法),对皮肤组织中PAR2的表达及组织分布进行测定.结果:AD患者皮损组织呈现以慢性皮炎为主的病理改变:表皮突向下增生延长,棘层肥厚,细胞增生明显;真皮浅层血管周围淋巴单一核细胞浸润,患者非皮损组织未见明显的炎性细胞浸润,但可见轻度棘层细胞增生.PAR2表达水平在AD患者皮损组织中明显升高,但在AD患者非皮损组织中变化并不显著.结论:在AD患者中,PAR2表达水平异常增加,由于PAR2表达的增加主要见于AD患者的皮损组织,南此推测.PAR2的激活和表达主要与AD的早期急性炎症反应有直接关联.