Quantitative analysis of contact sites between mast cells and sensory nerves in cutaneous psoriasis and lichen planus based on a histochemical double staining technique

Summary The aim of the present study was to test further our previous hypothesis that the inflammatory reaction in psoriasis is neurogenic. For this purpose, contact sites between mast cells and sensory nerves were morphometrically analysed in the basement membrane zone, papillary dermis and three dermal zones of lesional/non-lesional psoriatic and lichen planus skin as well as in healthy control skin. The analyses were made on sections stained with a histochemical double stain developed for this study. With the double stain, active mast cell tryptase was stained blue enzyme histochemically, and the sensory nerves black using specific monoclonal anti-neurofilament antibodies with immunogold. In psoriatic lesions, both mast cells and mast cell — nerve contacts were markedly more frequent in the basement membrane zone and in the papillary dermis when compared with the corresponding areas in the other groups. Mast cell numbers were increased in both lesional and symptom-free skin in lichen planus, but no increase was found in the mast cell — nerve contacts. Increased contacts between mast cells and sensory nerves indicate that the elements exist for neurogenic inflammation in psoriatic lesions. These increased contacts are not due to the extensive inflammatory reaction only, because they were not observed in lichen planus lesions.     

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.     

Skin nerve fibres and their contacts with mast cells in patients with palmoplantar pustulosis

Abstract Patients with palmoplantar pustulosis (PPP) frequently report that stress worsens their condition. A study was therefore made of the distribution and number of nerve fibres positive for protein gene product (PGP) 9.5 (a general nerve marker) and nerve fibres with substance P- and calcitonin gene-related peptide-like immunoreactivity in involved skin from patients with PPP and in skin from healthy controls. The number of mast cells in the papillary dermis was larger (P = 0.0003) in lesional palmar PPP skin than in control skin, and the number of contacts between mast cells and nerve fibres was significantly larger (P = 0.02) in PPP skin than in control skin. Image analysis of the nerve fibres around the sweat glands showed that the positively stained area as a percentage of the total area of the sweat gland (coil + surrounding nerves) was significantly lower in PPP skin (P = 0.0006). Furthermore, the nerves seemed to be fragmented. Neutrophils within and below the pustules and in the papillary dermis showed positive substance P staining. The increased number of contacts between nerves and mast cells in PPP skin and the intense substance P-like immunoreactivity of the neutrophils indicate that neuromediation may influence the inflammation in PPP, whereas the destruction of the nerve fibres around the sweat glands might be a result of the inflammation. Received: 8 October 1999 / Revised: 25 January 2000 / Accepted: 27 January 2000     

银屑病患者的心理压力、神经内分泌系统与肥大细胞研究现状

银屑病中有相当比例的患者因心理压力而使病情恶化,但其机制尚不明确.心理压力能激活下丘脑-垂体-肾上腺轴和皮肤感觉神经,导致内分泌激素和神经介质释放.多种激素和神经介质能活化肥大细胞产生和释放一系列的炎症介质和细胞因子.银屑病患者中,一些激素、神经肽、感觉神经纤维和肥大细胞在表达水平和数量上增高.心理压力影响银屑病病情的机制之一可能与应激介质通过肥大细胞的作用有关.     

The presence of tryptase-positive and bikunin-negative mast cells in psoriatic skin lesions

Human mast cells are well known to produce a serine protease, tryptase, which appears to play a pathogenic role in various skin inflammations. It was previously reported that a rat homologue of bikunin may inhibit tryptase activity. Various type of cells (i.e. keratinocytes) are able to produce this protein inhibitor, it still remains unclear if bikunin is present in dermal inflammatory milieu, in which mast cells, through secretion of tryptase, play an inflammatory role. Therefore, the purpose of the present study was to exploit expression and production of bikunin in dermis and dermal constituents. We first compared the dermal mast cells in psoriatic lesions with those in lesional skin of atopic dermatitis or of chronic eczema by use of immunoelectron microscopy and immunohistochemical analyses using antibodies to bikunin and tryptase. Then, we tested what kinds of cytokines may regulate the de novo synthesis of bikunin. To do so, RNA was extracted from a human mastocytic cell line, HMC-1, reverse-transcribed, and semiquantitative RT-PCR was performed using primers specific for bikunin. With immunoelectron microscopy, bikunin was found to localize on the cell membrane, while tryptase was in the secretary granules of the mast cells. In psoriatic lesions, around 70% of dermal mast cells were positive for both tryptase and bikunin, and the remaining was mostly positive for tryptase, but the expression of bikunin was under the detection limit of the experimental setting. This observation was seen in only psoriatic lesions, even in almost cured lesions, while in atopic dermatitis or chronic eczema only mast cells doubly positive for bikuin and tryptase were seen. In HMC-1, bikunin was constitutively expressed at an mRNA level, which was upregulated by stimulation with interleukine-4, but was suppressed by interferon-γ. Bearing in mind the concept that in psoriasis local cytokine milieu is shifted toward a Th1 pattern (predominant secretion of interferon-γ), tryptase-positive, bikunin-negative mast cells may be induced.     

Quantitative enzyme-histochemical analysis of tryptase- and chymase-containing mast cells in psoriatic skin

Summary Tryptase-containing mast cells have recently been found to be increased in the upper dermis of psoriatic lesions. In the present study, the distribution of chymaseand tryptase-containing mast cells was morphometrically analysed at different dermal levels of lesional and non-lesional psoriatic skin (12 patients) as well as normal human skin. Mast cell tryptase was identified enzyme-histochemically, using Z-Gly-Pro-Arg-MNA as the substrate. For demonstrating mast cell chymase, a simple and specific enzyme-histochemical staining method was developed, using Suc-Val-Pro-Phe-MNA as the substrate. All mast cells positive for chymase were also positive for tryptase and Giemsa stain. Although the number of tryptase-positive mast cells was slightly increased throughout the dermis of lesional psoriatic skin, this increase was most pronounced in the upper dermis immediately beneath, and in close contact with, the epidermis. In contrast, the number of chymase-positive mast cells was clearly decreased in the upper dermis of psoriatic lesions, but not in the deeper dermis, as compared with non-lesional psoriatic skin. In addition, all chymase-positive mast cells observed in the upper dermis were very weakly stained when compared with those in the deeper dermis. No differences were found between non-lesional psoriatic skin and normal skin in which the number of mast cells containing chymase was 72–73% of the number containing tryptase. The present results suggest that T mast cells particularly, containing tryptase but no chymase, proliferate in psoriatic lesions, and that the increase in tryptase activity and the decrease in chymase activitiy in the upper dermis may lead to an imbalance in the biochemical regulatory systems.     

Coculture of mast cells with psoriatic fibroblasts: an experimental system for studying the two cell interactions

In this study we established a coculture system for rat peritoneal mast cells (MC) with psoriatic (PSO) dermal fibroblasts. Rat MC adhered within five minutes to the fibroblasts monolayer and their attachment and viability was maintained for at least 2-3 days. Cocultured MC could be activated to release high percentages of histamine with compound 48/80 indicating that they retained their full functional activity. Attachment, viability and functional activity were similar for MC seeded on PSO fibroblasts or on normal human fibroblasts (NOR) used as a control. This would indicate that PSO fibroblasts altered biochemical characteristics do not interfere with these MC properties. We suggest that this coculture system is a suitable in vitro defined model to study mutual effects of MC and fibroblasts in psoriasis.     

肥大细胞在斑秃发病机制与治疗中的作用

近年来的研究显示,肥大细胞参与皮肤病尤其是炎症性皮肤病的发病过程.斑秃是一种非瘢痕性的炎症性脱发性疾病,发病机制未明,目前认为是一种T细胞介导针对毛囊的自身免疫性疾病.研究表明,斑秃皮损中肥大细胞增多可能与神经肽有关,而激活后的肥大细胞脱颗粒释放的各种炎症介质可能参与了斑秃的炎症浸润过程.在治疗斑秃中,预防性应用抗组胺药和肥大细胞膜稳定剂对传统治疗疗效欠佳、或者是有遗传过敏性体质的斑秃患者有效,提示肥大细胞可能参与斑秃的发病过程.     

Mast cell density in psoriatic skin. The effect of PUVA and corticosteroid therapy

Summary Numbers and volume fractions of mast cells in nonlesional and chronic lesional skin of psoriatic patients were compared with those of normal control skin. Mast cell densities were similar in psoriatic nonlesional and normal control skin. The superficial dermis of lesional psoriatic skin contained more mast cells than either normal or nonlesional psoriatic skin. Neither PUVA nor corticosteroid treatment for 3–4 weeks significantly reduced mast cell numbers or volume fractions in lesional skin, although both treatments clinically and histologically markedly improved the lesions. The results indicate that the initiation of the healing process in psoriatic plaques is not correlated with the mast cell density. The remaining high mast cell density may be normalized later, or after a longer therapy.     

A simple immunofluorescence technique for simultaneous visualization of mast cells and nerve fibers reveals selectivity and hair cycle – dependent changes in mast cell – nerve fiber contacts in murine skin

Close contacts between mast cells (MC) and nerve fibers have previously been demonstrated in normal and inflamed skin by light and electron microscopy. A key step for any study in MC-nerve interactions in situ is to simultaneously visualize both communication partners, preferably with the option of double labelling the nerve fibers. For this purpose, we developed the following triple-staining technique. After paraformaldehyde-picric acid perfusion fixation, cryostat sections of back skin from C57BL/6 mice were incubated with a primary rat monoclonal antibody to substance P (SP), followed by incubation with a secondary goat-anti-rat TRITC-conjugated IgG. A rabbit antiserum to CGRP was then applied, followed by a secondary goat-anti-rabbit FITC-conjugated IgG. MCs were visualized by incubation with AMCA-labelled avidin, or (for a more convenient quantification of close MC-nerve fiber contacts) with a mixture of TRITC- and FITC-labelled avidins. Using this simple, novel covisualization method, we were able to show that MC-nerve associations in mouse skin are, contrary to previous suggestions, highly selective for nerve fiber types, and that these interactions are regulated in a hair cycle-dependent manner: in telogen and early anagen skin, MCs preferentially contacted CGRP-immunoreactive (IR) or SP/CGRP-IR double-labelled nerve fibers. Compared with telogen values, there was a significant increase in the number of close contacts between MCs and tyrosine hydroxylase-IR fibers during late anagen, and between MCs and peptide histidine-methionine-IR and choline acetyl transferase-IR fibers during catagen. Received: 14 June 1996     

不同病期银屑病皮损组织CK20、S100A7、SP的表达及其相关性

目的 探讨不同病期银屑病皮损组织中CK20、S100A7、SP的表达及CK20与S100A7、SP表达的关系.方法 选择经过非正规治疗,新旧皮损同时存在的患者19例,获取皮损旁的正常皮肤组织(发病前期)、皮损组织(进展期)和皮损修复后的病灶皮肤组织(缓解期),观察皮损中免疫组化CK20、S100A7、SP的表达情况.结果 免疫组化图像分析各组A值,发病前期组、进展期组和缓解组CK20分别为7683.80±6134.55、18305.04±13171.30、7257.53±4417.75.S100A7分别为8789.05±6240.91、18058.01±16537.18、9295.65±9310.02.SP分另为3242.51±3775.41、9364.98±7596.64、2910.85±3349.46.进展期皮损组织中CK20与S100A7,SP表达相对于发病前期和缓解期明显增加其差异均有统计学意义,P＜0.05.发病前期组与缓解组其差异均无统计学意义,P＞0.05.CK20与S100A7、SP表达呈正相关,相关系数R分别为0.779、0.876、P＜0.05.结论 银屑病发病与Merkel细胞数量的变化有一定的关系.     

银屑病患者皮损间充质干细胞环状RNA表达异常研究

目的 探讨环状RNA（circRNA）在银屑病发病中的作用。方法 分离、培养15例银屑病患者皮损及15例健康对照皮肤间充质干细胞（MSC）,用流式细胞仪及多向分化法进行鉴定。用RNA测序法检测circRNA表达,并进行详细的生物信息学分析。挑选7个差异表达的circRNA构建circRNA-microRNA相互作用网络,从中挑选3个与其相关的microRNA进行qRT-PCR验证。银屑病患者组和对照组qRT-PCR验证结果采用两独立样本t检验。结果 RNA测序结果显示,共检测到6 323个circRNA,其中3 227个为本实验首次发现。与对照组相比,患者组中有129个circRNA呈差异表达,其中123个表达上调,6个表达下调。挑选7个差异circRNA进行circRNA-microRNA相互作用预测,显示与这7个circRNA关系密切的银屑病相关microRNA,包括miR-17-5p、miR-30e-5p、miR-142-3p/5p、miR-369-3p、miR-184、miR-4490、miR-654-3p、miR-423-5p等。qRT-PCR也证实,这7个差异circRNA在患者组也表达上调。与对照组相比,挑选的3个microRNA在银屑病皮损中低表达（t值分别为3.993、3.217、2.918,均P < 0.05）。结论 银屑病皮损MSC circRNA表达异常,并可能参与了银屑病发病。     

Reappraisal of in situ immunophenotypic analysis of psoriasis skin: interaction of activated HLA-DR+ immunocompetent cells and endothelial cells is a major feature of psoriatic lesions

Psoriasis is an inflammatory skin disease of unknown aetiology. Many observations indicate that T cells play an important role in the pathogenesis of the disease. Upregulation of MHC class-II molecules on immunocompetent cells, endothelial cells and keratinocytes on lesional psoriatic skin has been regarded as a hallmark of the disease. However, there is some controversy in the literature regarding the cell types expressing class-II molecules and there is limited information about the presence of immune cells other than T cells and antigen presenting cells in the cellular infiltrates of psoriatic skin. We therefore reinvestigated the subject using immunocytochemical single and multiple staining techniques. In agreement with earlier reports, our studies showed that the cellular infiltrates in lesional skin consist largely of HLA-DR⁺/IL-2R⁺ T cells, HLA-DR⁺/CD1a⁺ Langerhans cells, and HLA-DR⁺/CD68⁺ macrophages. We found increased HLA-DR expression mostly on immunocompetent cells and endothelial cells, but no prominent HLA-DR expression on keratinocytes in lesional psoriatic skin. Upregulation of HLA-DR on endothelial cells and in mononuclear infiltrates was also evident in the non-lesional skin of psoriatic patients as compared with normal controls. B cells and natural killer cells were also found in the cellular infiltrates in lesional psoriatic skin. In spite of the presence of a large amount of activated T cells in the epidermis, we found that HLA-DR expression on keratinocytes was not a major feature of psoriatic skin.     

Mast cells and macrophages in early relapsing psoriasis

Summary Five patients with widespread plaque-type psoriasis were treated continuously with clobetasol under occlusion. Clinical healing was seen after 6–10 days of treatment. All plaques treated in this way clinically relapsed approximately 12 days later. During the period of remission, sequential biopsies were taken and prepared for light and electron microscopy. Histologically, the earliest indications of relapse were endothelial alterations (swelling, intercellular widening) followed by the appearance of mast cells around the postcapillary venules; these mast cells showed signs of degranulation. Hours later, activated macrophages showing pericellular edema were present, and these migrated into the epidermis soon after. Associated with the presence of macrophages, there was a complete loss of desmosome-tonofilament complexes. Later, lymphocytes and neutrophils were seen. Under these experimental conditions, the psoriatic-tissue alterations appear to have been initiated by degranulating mast cells as well as by macrophages which later invaded the epidermis.This paper was presented at the 14th Meeting of the ESDR (Amsterdam, April 1984)     

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     

银屑病瘙痒皮损中肥大细胞的数量与分布研究

目的探讨肥大细胞在银屑病瘙痒症状发生中的作用。方法应用免疫组化技术对30例患者(无瘙痒12例,瘙痒18例)皮损区、非皮损区以及2例正常人皮肤组织中肥大细胞数量进行检测。结果银屑病伴有瘙痒症状的患者皮损中肥大细胞数量明显增多(Z=-2.732,P<0.05)。结论皮损中肥大细胞的数量变化与银屑病的瘙痒症状具有相关性。     

寻常型银屑病皮损肥大细胞密度及IL-8表达的研究

目的：探讨肥大细胞和IL-8在寻常型银屑病中的作用。方法：采用免疫组化技术(SABC法)观察寻常型银屑病皮损处MC分布和IL-8在表皮中的表达情况。结果：寻常型银屑病皮损处MC密度明显高于皮肤血管炎组和健康对照组；寻常型银屑病皮损处KC中IL-8的表达明显高于两对照组。结论：结果提示MC和IL-8参与寻常型银屑病的致病过程，并且两者之间存在相关性。     

Regulation of mast cell characteristics by cytokines: divergent effects of interleukin-4 on immature mast cell lines versus mature human skin mast cells

Mast cells (MC) are of hematopoietic origin but complete their differentiation exclusively within tissues. The mediators that positively or negatively affect the maturation process are incompletely defined. Here, the human MC line HMC-1 (subclone 5C6) was used along with several treatments (IL-4, IL-6, NGF), either alone or in combination, and MC differentiation was monitored by flow-cytometric analysis of c-kit, tryptase, and FcRI expression. Of the different treatments, IL-4 displayed the clearest effects by suppressing the expression of the three markers and inhibiting cellular growth, while the other cytokines had no (NGF) or negligible (IL-6) effects only. The downregulating effects of IL-4 could not be overcome by any other treatment. There is some controversy in the literature as to the impact of IL-4 on the MC lineage. To determine whether the effects from IL-4 were differentiation stage dependent, two further human MC subsets (skin MC and LAD 2 cells) were investigated. No effects on c-kit and FcRI expression were noted when terminally differentiated skin MC were used as target cells, while a modest downregulation of c-kit was observed with intermediately matured LAD 2 cells. In sharp contrast to HMC-1 5C6 cells, the survival of skin MC was significantly enhanced by IL-4 treatment. Our data therefore imply that at a lower maturation stage, IL-4 acts as a negative regulator of the MC lineage, but that this property disappears or is even reversed upon terminal differentiation of the cell. Our study provides direct proof that the effects of IL-4 vary substantially in the course of MC maturation.