NK-1 antagonist CP99994 inhibits stress-induced mast cell degranulation in rats

Mast cells are implicated in stress-induced inflammatory skin diseases such as psoriasis. Mechanisms of stress-induced mast cell degranulation however, are not entirely clear. Here we explore the role of activation of a Substance P (SP) receptor (NK-1) on mast cell degranulation upon exposure to stress in rats. A specific nonpeptide NK-1 antagonist, CP99994 was used to treat the rats either peripherally or intracerebroventricularly. Because increased SP activity in the brain may mediate the stress response, we also examined cutaneous mast cell degranulation after central injection of SP. Stress, as well as SP injected centrally, increased mast cell degranulation. Both central and peripheral injection of CP99994 prevented stress-induced mast cell degranulation. Surprisingly, the combination of stress with SP decreased mast cell degranulation, suggesting that high levels of SP may counteract the stress responses. Results in this animal model suggest that NK-1 antagonists may be used therapeutically to treat stress-induced inflammatory skin diseases; however, drug doses should be chosen carefully.     

A further characterization of acridine-photosensitized inhibition of mast cell degranulation

The purpose of this study was to further characterize acridine-photosensitized inhibition of mast cell degranulation. Acridine plus UVA radiation (320-400 nm) inhibited degranulation in response to antigen in IgE-sensitized rat serosal mast cells and in response to concanavalin A, which acts by a mechanism similar to antigen-IgE challenge. Removing oxygen from the incubation medium prevented the acridine-photosensitized inhibition of mast cell degranulation in response to 48/80. Acridine plus UVA radiation did not decrease mast cell ATP content, thus excluding inhibition of ATP production as a mechanism for photosensitized inhibition of mast cell degranulation. Although the viability of mast cells, as determined by uptake of trypan blue, was not affected 3 h after treatment with acridine plus UVA radiation, viability decreased by 6 h, and by 22 h 44% of the cells were nonviable. These results indicate that degranulation of mast cells by a variety of agents is inhibited by UVA plus acridine treatment, and that photosensitization requires oxygen and occurs before cytotoxicity.     

脱敏组方抑制肥大细胞脱颗粒的实验研究

目的分析脱敏组方对大鼠被动致敏肥大细胞脱颗粒的抑制作用。方法以大鼠抗卵蛋白抗血清被动致敏的大鼠腹腔肥大细胞为细胞模型,分别进行脱敏组方对其脱颗粒的抑制实验及释放组胺的抑制实验、免疫组化ABC法检测其5-羟色胺(5-HT)的释放。结果脱敏组方1.4g/mL,2.8g/mL均可明显抑制大鼠被动致敏的肥大细胞脱颗粒、减少组胺、5-HT等炎症介质的释放。结论脱敏组方可以稳定和抑制致敏肥大细胞脱颗粒释放炎症介质,具有抗Ⅰ型变态反应的作用。     

Human mast cells express androgen receptors but treatment with testosterone exerts no influence on IgE‐independent mast cell degranulation elicited by neuromuscular blocking agents

Please cite this paper as: Human mast cells express androgen receptors but treatment with testosterone exerts no influence on IgE‐independent mast cell degranulation elicited by neuromuscular blocking agents. Experimental Dermatology 2010; 19: 302–304. Abstract: Women predominate in the anaphylactic reactions to neuromuscular blocking agents (NMBA). The expression of oestrogen receptors has been demonstrated in mast cells and oestrogen treatment can enhance mast cell degranulation, but the influence of androgens remains largely unclear. Our immunocytochemical study showed the expression of androgen receptor (AR) in mast cells isolated from human foreskin as well as in two human mast cell lines, HMC‐1 and LAD2. The amount of AR was most abundant in human skin mast cells as determined by real‐time polymerase chain reaction analysis. Treatment of the HMC‐1 mast cells with testosterone or 17β‐oestradiol, alone or in combination with different NMBA, did not affect mast cell degranulation as measured by the release of β‐hexosaminidase. Our study shows for the first time the expression of AR in human skin mast cells. Further studies using primary human mast cell cultures are needed to understand whether and how sex hormones can influence mast cell activation.     

Inhibitory effects of antipsychotic and anxiolytic agents on stress‐induced degranulation of mouse dermal mast cells

Background. Various psychological stresses induce degranulation of mast cells. It has been confirmed by animal experiments that stress induced by restraint promotes mast‐cell degranulation in various organs, and that the degranulation is inhibited by pretreatment with corticotropin‐releasing factor (CRF)‐neutralizing antibodies, CRF receptor antagonists, and neurotensin (NT) antagonists. Previous studies have suggested that anxiety and fear induced in animals by psychological stressors promote the production and release of various neuropeptides and neurotransmitters, and induce degranulation of mast cells in several organs. Aim. To evaluate the effect of prior treatment with antipsychotic and anxiolytic agents to inhibit foot‐shock (FS) stress‐induced degranulation of mouse dermal mast cells. Methods. Using a communication box system, FS was administered to mice and the degranulated dermal mast cells were counted. Chlorpromazine (2 or 4 mg/kg body weight), tandospirone (10 mg/kg body weight) or CRA1000, a selective non‐peptidic CRF receptor type 1 antagonist (10 or 100 mg/kg body weight) was injected intraperitoneally 1 h before exposure to FS. Results. After FS was administered, the number of dermal mast cells did not change. However, FS significantly increased the proportion of degranulated mast cells. Pretreatment of mice with chlorpromazine hydrochloride, an antipsychotic agent (2 or 4 mg/kg), or the anxiolytic agents tandospirone citrate (10 mg/kg) or CRA1000 (10 or 100 mg/kg), significantly inhibited the FS‐induced mast‐cell degranulation (P < 0.05, P < 0.01, P < 0.05, P < 0.05, and P < 0.05, respectively). Conclusions. Antipsychotic and anxiolytic agents may be effective treatments for stress‐aggravated inflammatory skin diseases by inhibition of mast‐cell degranulation.     

Eosinophilic cellulitis: histologic features in a cutaneous mastocytoma

A cutaneous mastocytoma with associated histologic features of eosinophilic cellulitis is reported. The tumor occurred as a small, asymptomatic lesion on the left thigh of a 4-year-old boy. Microscopically, an accumulation of mast cells, microgranulomas, eosinophils and 'flame figures' was present. A pathogenesis involving mast cell degranulation, eosinophil chemotactic factors and eosinophil major basic protein is discussed.     

The effect of 8-methoxypsoralen plus long-wave ultraviolet (PUVA) radiation on mast cells: PUVA suppresses degranulation of mouse skin mast cells induced by compound 48/80 or concanavalin A

In order to see whether 8-methoxypsoralen (8-MOP) plus long-wave ultraviolet (UVA) radiation (PUVA) has an influence on immediate-type skin reactions, we have undertaken an animal study. Ears of mice were treated with a 0.5% 8-MOP solution topically plus UVA radiation (1.5-2.5 J/cm2). After PUVA radiation, skin responses to intradermal injection with mast cell liberators, including compound 48/80 (2.5 mg/ml, 10 microliter) and concanavalin A (Con-A) (2.0 mg/ml), or with a mixture of 5-hydroxytryptamine (5-HT) and histamine as vasodilator (1.0 mg/ml and 50 mM, respectively) were examined with time (2 h-14 days). At each time point, an ear swelling response (ESR) was measured with a dial thickness gauge. The rate of mast cell degranulation and mast cell numbers were assessed by light microscopy using toluidine blue-stained semithin (1 micron) sections. ESR induced by compound 48/80 or Con-A was significantly suppressed dose-dependently (greater than 42% inhibition) by PUVA between 2 h-3 days postirradiation as compared with that in nonirradiated control mice, and the value returned to normal levels by 7-14 days. Compound 48/80- or Con-A-induced mast cell degranulation (%) was remarkably decreased between 2 h-3 days (greater than 48% inhibition) in accordance with the suppression in ESR and it was restored to the rates in nonirradiated controls by 7-14 days. Neither ESR nor percent degranulation was affected by UVA radiation only (less than 3.5 J/cm2) or application of 8-MOP only. 5-HT plus histamine-mediated ESR was not altered at all by PUVA throughout the experimental period. Since PUVA radiation itself at given doses did not produce measurable ESR, mast cell degranulation, or a reduction in mast cell numbers, and since PUVA did not affect a normal vascular response to vasodilator, it seemed that decreased skin reactivity to mast cell degranulators by PUVA might be due to a PUVA-induced noncytolytic alteration in mast cell release mechanisms.     

Extracellular localization of human connective tissue mast cell granule contents.

In early phases of cutaneous inflammation, connective tissue mast cell degranulation is associated with apparent secretion and externalization of immunoreactive chymotryptic serine proteinase. To determine whether this event is associated with structural evidence of granule externalization, we studied the sequential evolution of IgE-mediated hypersensitivity in vivo, as well as mast cell degranulation provoked by a variety of stimuli in cultured explants of human skin. By 1 min after intradermal antigen challenge with ragweed extract, mast cell degranulation was associated with apparent extrusion of intragranule constituents into the pericellular connective tissue. Similar features typified cultured skin explants exposed for 45 min to anti-IgE and other mast cell secretagogues (morphine sulfate, calcium ionophore A23187, compound 48/80, and substance P). Once externalized, granule constituents could be identified within the dermal matrix by their rounded contour and structural similarity to solubilized granule matrices remaining within actively secreting cells. These data indicate that externalization of connective tissue mast cell granule contents occurs early after secretagogue exposure, potentially accounting for infrequent documentation of this event in naturally occurring dermatoses. The ability to recognize externalized granule products at a morphologic level should facilitate the understanding of interactions between mast cell-derived mediators and target structures of the dermal microvasculature.     

Ultraviolet-B radiation suppresses mast cell degranulation induced by compound 48/80

This study was designed to investigate the effect of middle-wave ultraviolet (UVB) radiation on mast cell functions using mouse ear skin as an in vivo model. Groups of UVB-irradiated BALB/c mice were given an intradermal injection of the mast cell degranulator compound 48/80 into ears at various time intervals (30 min-7 days) after a single exposure to a bank of fluorescent sunlamp tubes (10-100 mJ/cm2). Both the compound-evoked ear swelling response (ESR) and mast cell degranulation were significantly suppressed by preexposure to UVB (25-100 mJ/cm2) after 0 (30 min) to 3 days postirradiation, with a subsequent recovery by day 7. No such effects were observed in mice irradiated with 10 mJ/cm2. The ESR induced by 5-hydroxytryptamine was not significantly affected by UVB radiation during the experimental period. While within this dose range UV radiation itself caused neither loss of mast cell counts nor a measurable degree of degranulation in ear skin, exposure to larger amounts of UV energy (200-500 mJ/cm2) produced tremendous ear swelling with histologic features of mast cell degranulation in an early phase of inflammation. The results suggest that UVB radiation exerts a dual effect on mast cells and that administration of smaller amounts of UVB may alter the mast cell/vasoactive amine system, suppressing ear swelling in response to the degranulator. Vascular reactivities to vasoactive amines were not affected by UVB irradiation.     

Inflammatory properties of human C5a and C5a des Arg/ in mast cell-depleted human skin

C5a and its degradation product, C5a des Arg, elicit immediate cutaneous inflammatory reactions after intradermal injection. Histologically, these reactions are characterized by neutrophil-rich leukocytic infiltrates, leukocytoclasis, edema, and dermal mast cell degranulation. It has not been possible to assess in vivo the relative contributions of resident mast cells and circulating leukocytes to this reaction because the accumulation of leukocytes and degranulation of mast cells occur simultaneously after injection of these anaphylatoxins. To assess the role of mast cells in these inflammatory reactions, we have examined the reactivity of human skin selectively depleted of dermal mast cells by local corticosteroid treatment. Corticosteroid-treated skin became virtually devoid of dermal mast cells within 4-6 wk as assessed by light microscopy, immunofluorescence with fluorescein-conjugated avidin, or electron microscopy. Mast cell-depleted skin demonstrated normal vasopermeability and vasodilatory responsiveness to intradermal injection of histamine, but the reactivity of these sites to the mast cell secretagogue, morphine, was absent. Moreover, no clinical reactions were detectable in mast cell-depleted human skin after intradermal challenge with 50 ng of either C5a or C5a des Arg, despite the fact that biopsies of these sites revealed substantial, neutrophil-rich infiltrates. These infiltrates were qualitatively and quantitatively identical to C5a or C5a des Arg-induced infiltrates in mast cell replete skin. This experimental approach in vivo has allowed the independent analysis of the anaphylactogenic and chemoattractant activities of human C5a and C5a des Arg in human skin, demonstrated the importance of dermal mast cells in these clinical responses, and shown that leukocytes can accumulate at these injection sites directly in response to these mediators.     

Mast cells as regulators of skin inflammation and immunity

Mast cells are known to be the effector cells of immediate-type allergy, but experimental evidence obtained during the last decade has revealed their role in innate and acquired immunity. Upon activation mast cells can undergo an anaphylactic or piecemeal degranulation or degranulation-independent mediator secretion, resulting in rapid or slow release of soluble mediators, such as serine proteinases, histamine, lipid-derived mediators, cytokines, chemokines and growth factors. Mast cells can express different receptors and ligands on the cell surface, molecules that can activate the cells of the immune system, such as different subsets of T cells. All these mediators and cell surface molecules can promote inflammation in the skin. During the last years, a new role for mast cells has emerged; induction of tolerance or immunosuppression and interaction with regulatory T cells. However, the mechanisms that switch the proinflammatory function of mast cells to an immunosuppressive one are unknown. In this review, the immunoregulatory function of mast cells and its relation to skin inflammation are discussed.     

Dermal dendrocytes FXIIIA+ phagocytizing extruded mast cell granules in drug‐induced acute urticaria

Background Few authors have been attempting between mast cells and dermal dendrocytes interactions on urticaria. Objective To describe the extruded mast cell granules and dermal dendrocytes in drug‐induced acute urticaria. Methods Seven patients with drug‐induced acute urticaria were enrolled in the study. We token skin biopsies of urticaria lesion and perilesional skin. The 14 fragments collected were processed to immunogold electron microscopy using single stains to tryptase and FXIIIa, besides double immunogold labeling with both. Results Some sections demonstrated mast cells in degranulation process, both in anaphylactic and piecemeal degranulation types. After double immunogold staining, 10 nm (FXIIIa) and 15 nm (Tryptase) gold particles were present together over the granules in mast cells indicating that tryptase and FXIIIa are each localized within the granules of these cells. Interestingly, we found a strong evidence of than the exocytosed mast cell granules contents both FXIIIa and tryptase immunolabeled are phagocytized by dermal dendrocytes. Conclusions The current observations provide morphological evidence that the exocytosis‐phagocytosis mechanisms of mast cell granules represents one pathophysiological example of mast cells‐dermal dendrocytes interactions in urticaria.     

Is there a role for mast cells in psoriasis?

Mast cells have traditionally been considered as effector cells in allergy but during the last decade it has been realized that mast cells are essentially involved in the mechanisms of innate and acquired immunity. Upon activation by anaphylactic, piecemeal degranulation or degranulation-independent mechanisms mast cells can secrete rapidly or slowly a number of soluble mediators, such as serine proteinases, histamine, lipid-derived mediators, cytokines, chemokines and growth factors. Mast cells can express cell surface co-stimulatory receptors and ligands, and they can express MHC class II molecules and thereby present antigens. These soluble factors and cell surface molecules can interact with other cells, such as endothelial cells, keratinocytes, sensory nerves, neutrophils, T cell subsets and antigen presenting cells which are essential effectors in the development of skin inflammation. Besides promoting inflammation, mast cells may attempt in some circumstances to suppress the inflammation and epidermal growth but the regulation between suppressive and proinflammatory mechanisms is unclear. Psoriasis is characterized by epidermal hyperplasia and chronic inflammation where tryptase- and chymase-positive MC_TC mast cells are activated early in the developing lesion and later the cells increase in number in the upper dermis with concomitant expression of cytokines and TNF superfamily ligands as well as increased contacts with neuropeptide-containing sensory nerves. Due to the intimate involvement of mast cells in immunity and chronic inflammation the role of mast cells in psoriasis is discussed in this review.     

Botulinum toxin blocks mast cells and prevents rosacea like inflammation

Background

Rosacea is a chronic inflammatory skin condition whose etiology has been linked to mast cells and the antimicrobial peptide cathelicidin LL-37. Individuals with refractory disease have demonstrated clinical benefit with periodic injections of onabotulinum toxin, but the mechanism of action is unknown.

Mast cells in oral erythema multiforme.

We compared the number of mast cells in erythema multiforme lesions, in clinically healthy mucosa between the EM attacks and in healthy mucosa from healthy volunteers. The mast cell count in patients with erythema multiforme was numerically higher than in healthy controls, but the differences were not statistically significant. In erythema multiforme lesions the mast cell count was low in the intensely inflamed superficial lamina propria, but high in normal appearing mucosa between the attacks suggesting local mast cell degranulation in the most intensely inflamed areas.     

The role of the mast cell in clinical gastrointestinal disease with special reference to systemic mastocytosis

The gastrointestinal tract is a rich source of mast cells with an enormous surface area that permits a high degree of interaction between the mast cell and intestinal luminal contents. The active metabolic products of the mast cell influence gastrointestinal secretion, absorption, and motility through paracrine effects of local mast cell degranulation and also cause systemic effects through the release of cellular products into the blood stream. Systemic mastocytosis influences physiologic function through the systemic effects of mast cell products released from focal (e.g., bone marrow) or wide spread increases in mast cell number. Local gastrointestinal proliferation of mast cells in response to recognized (e.g., gluten in celiac sprue) or obscure stimuli can alter gastrointestinal function and induce systemic symptoms. Celiac sprue, inflammatory bowel disease, and non-ulcer dyspepsia are three examples of gastrointestinal diseases in which mast cells can be implicated in the pathophysiology of the symptoms.     

脱敏组方抗I型变态反应的实验研究

目的:观察中药脱敏组方对I型变态反应的影响,并初步探讨其抗I型变态反应的作用机制。方法:大鼠皮内注射抗卵蛋白的抗血清(含IgE)诱导被动皮肤过敏反应,观察脱敏组方抗I型变态反应的作用。并以大鼠颅骨骨膜肥大细胞为细胞模型,观察脱敏组方对被动致敏肥大细胞脱颗粒的影响。结果:脱敏组方14gkg、28gkg灌胃均可明显抑制由卵蛋白致敏的大鼠同种被动皮肤过敏反应。脱敏组方14gkg、28gkg均可明显抑制大鼠被动致敏的肥大细胞脱颗粒。结论:中药脱敏组方具有抗I型变态反应的作用,稳定肥大细胞、抑制致敏肥大细胞脱颗粒、释放炎症介质是其抗I型变态反应的主要作用机制之一。     

Pityriasis rosea and ketotifen

A 4-year-old female patient who developed a skin eruption similar to pityriasis rosea after treatment with ketotifen (Zaditen) is presented. The relationship between ketotifen and the eruption has been based on circumstantial evidence and confirmed by the positive results of the MIF test and the rat mast cell degranulation test.     

Fibrous mastocytoma in a patient with generalized cutaneous mastocytosis

A 57-year-old woman with cutaneous mastocytosis of 23 years duration developed a hyperpigmented abdominal plaque composed of confluent indurated papules that enlarged for a period of 1 year to 12 x 8 cm. Biopsy showed dermal infiltration by closely packed spindle-shaped mast cells, fibroblasts, collagen, and scattered lymphocytes, predominantly T-suppressor cells. Electron microscopy showed close contact between mast cells, fibroblasts, and lymphocytes. Piecemeal mast cell degranulation and extrusion of mast cell granules was seen, with rare mast cell granules in fibroblasts, and collagen fibers in peripheral and perinuclear endoplasmic reticulum of mast cells. the term Fibrous mastocytoma is suggested for this tumor-like dermal fibrosis, possibly induced by lymphokines.     

丹皮酚对RBL-2H3肥大细胞活化脱颗粒的影响

目的通过建立体外抑制肥大细胞脱颗粒的药效学模型,探讨丹皮酚抗Ⅰ型变态反应作用机制。方法用MTT比色法检测不同浓度的丹皮酚对RBL-2H3肥大细胞增殖的影响。通过ELISA法,明确体外RBL-2H3细胞活化分泌组胺及TNF-α动力学特征。检测不同浓度药物对RBL-2H3肥大细胞分泌组胺及TNF-α的影响。结果丹皮酚对RBL-2H3细胞增殖有抑制作用,IC50值为0.22 mg/mL。RBL-2H3细胞活化脱颗粒,分泌组胺的释放率在前30 m in上升较快,30 m in后上升进入平台期;TNF-α分泌的量在1h达高峰。丹皮酚抑制RBL-2H3细胞释放组胺和TNF-α作用不弱于色甘酸钠0.1,0.5 mg/mL。丹皮酚浓度的对数与其对RBL-2H3细胞释放组胺和TNF-α的抑制率呈线性相关(P=0.000<0.01)。结论丹皮酚呈剂量依赖性抑制RBL-2H3细胞分泌组胺和TNF-α。