Transient production of stem cell factor in dermal cells but increasing expression of Kit receptor in mast cells during normal wound healing.

Mast cells are involved in inflammatory skin disorders and wound healing processes, but the mechanism behind mast cell activation is obscure. In this study, we stained the stem cell factor (SCF) and the Kit receptor in tryptase-positive mast cells, since these molecules are essential for mast cell survival, growth, migration and activation. For this purpose, biopsies were taken from the edge of normally healing wounds of 12 patients undergoing skin transplantation on days 0, 1, 3, 7 and 14, and from chronic leg ulcers and psoriatic skin for comparison.

Release of soluble tryptase but only minor amounts of chymase activity from cutaneous mast cells.

Tryptase and chymase are the major serine proteinases of skin mast cells but their biologic significance depends on their activity. In this study, we demonstrate the release of soluble activity of tryptase, but not markedly that of chymase, into skin blister fluids induced by freezing with liquid nitrogen as well as into supernatant during incubation of 8 whole skin specimens with compound 48/80 for up to 2 days followed by sonication. Incubation of 3 other skin specimens in compound 48/80 for up to 2 days revealed that the number of mast cells displaying tryptase activity decreased significantly on day 2, and the number of mast cells showing chymase activity (but not those showing chymase immunoreactivity) decreased significantly on day 1 but not thereafter on day 2.

A multicenter study of patch test reactions with dental screening series.

Background: Dental products contain many allergens, and may cause problems both for patients undergoing dental treatment and for dental personnel because of occupational exposure. Individual patch test clinics may not study sufficient numbers of patients to collect reliable data on uncommon allergens.

Objective: To collect information on dental allergens based on a multicenter study.

Inhibition of keratinocyte growth in cell culture and whole skin culture by mast cell mediators.

Mast cells are suggested to participate in regenerative processes, but their influence on epithelialization and wound healing has not been well studied. Since mast cells can be found in contact with epidermis in chronic inflammatory skin diseases and venous ulcers, the effect of mast cells on keratinocyte growth was studied. Keratinocytes were cultured in serum-free conditions with (complete medium) or without (basal medium) epidermal growth factor (EGF) and bovine pituitary extract (BPE) to reach subconfluence in a 24-well plate, and the cells were treated with different mast cell mediators histamine, heparin and tryptase, or lysate from HMC-1 cells, a human leukemic mast cell line.

Modulation of the immediate allergic wheal reaction in the skin by drugs inhibiting the effects of leukotriene C4 and prostaglandin D2.

Objective: To study the effect of nordihydroguaiaretic acid (NDGA), zafirlukast and indomethacin on the size of the size of the allergic prick-test wheal.

Method: In the first part of the study, NDGA and indomethacin, as well as the mepyramine control (10 micrograms/ml and 100 micrograms/ml), were injected intracutaneously 10 min before prick-testing with the cow dander allergen in 51 sensitised atopic subjects. In the second part, five other subjects were prick-tested with several allergens followed by administration of 40 mg zafirlukast or 100 mg indomethacin and re-prick-testing 2 h or 4 h later.

The release of histamine is associated with the inactivation of mast cell chymase during immediate allergic wheal reaction in the skin.

Background: Chymase released by mast cells can participate in the immediate allergic wheal. However, chymase may be susceptible to inactivation by protease inhibitors during degranulation.

Objective: To study the inactivation of chymase and the release of histamine in the immediate allergic wheal reaction.

Interleukin-4-positive mast cells are highly associated with the extent of immediate allergic wheal reaction in the skin.

Background: In addition to histamine, mast cells contain other potent mediators which can contribute to the allergic wheal reaction in the skin.

Methods: To study the association of tryptase-, chymase-, and interleukin-4 (IL-4)-positive mast cells with the size of the prick-test wheal reaction, 50 sensitive atopic subjects were prick-tested with the cow-dander allergen on the forearm skin, and the wheal area was measured. A corresponding site of intact healthy-looking skin was biopsied and examined enzyme-histochemically for tryptase and chymase.

Release of histamine and leukotriene C4 in immediate allergic wheal reaction as measured with the microdialysis technique.

Other mediators as well as histamine can contribute to the allergic wheal reaction. In this study, the microdialysis technique was used to monitor the release of histamine, leukotriene C4 (LTC4) and prostaglandin D2 (PGD2) in prick-test wheal reactions induced by cow dander allergen. Of 31 atopic subjects, 25 showed detectable histamine release that correlated significantly with the number of tryptase-positive mast cells and serum cow-specific IgE but not with the wheal size.

Alterations in mast cells showing tryptase and chymase activity in epithelializating and chronic wounds.

Mast cells can be found in contact with epidermis in certain circumstances; especially in chronic inflammatory skin diseases and chronic ulcers, but the significance of this association is obscure. In this study, the association of mast cells with wound healing was studied by counting mast cells in the wound edges at different stages after wounding the donor site skin for pinch-grafting. Chronic venous leg ulcers were biopsed for comparison.

Hypersensitivity to gold in gold sodium thiomalate-induced dermatosis.

Gold compounds are widely used in the treatment of rheumatoid arthritis. Mucocutaneous side-effects leading to the discontinuation of medication are common with these drugs. We investigated whether allergic mechanisms are involved in dermatosis induced by gold sodium thiomalate (GSTM).

Focal dermal-epidermal separation and fibronectin cleavage in basement membrane by human mast cell tryptase.

Mast cell proteases are believed to participate in the basement membrane destruction in blistering diseases. Thus, normal human skin specimens were incubated with purified human skin tryptase or compound 48/80 (a mast cell degranulator) for up to 24 h. Thereafter, the specimens were studied immunohistochemically.

Mast cells in developing subepidermal bullous diseases: emphasis on tryptase, chymase and protease inhibitors.

The possible involvement of mast cell tryptase and chymase in subepidermal bullous diseases was studied enzyme-histochemically in specimens from erythematous and vesicular skin and from non-involved skin of patients with dermatitis herpetiformis, bullous pemphigoid, erythema multiforme, infective bullous eruption and linear IgA dermatosis. Patients with pemphigus were biopsied for comparison. The immunoreactivity of chymase inhibitors, alpha1-proteinase inhibitor (alpha1-PI) and alpha1-antichymotrypsin (alpha1-AC), in mast cells was demonstrated using the sequential double staining method.

Cultured allogeneic skin cells are effective in the treatment of chronic diabetic leg and foot ulcers.

Diabetic ulcers on the lower extremities present a difficult treatment problem, and some ulcers respond poorly to conventional topical and cast treatment. The purpose of this study was to assess the effect of cultured allogeneic keratinocyte epithelium and fibroblast-gelatin sponge on the healing of chronic, refractory diabetic leg and foot ulcers. Non-diabetic chronic leg ulcers were treated for comparison.

Suction blister formation in skin after acute and repeated mast cell degranulation.

Mast cells and their proteases are thought to participate in the development of skin blisters in various pathological conditions. In this study, suction blistering was used as an experimental model to evaluate the significance of mast cells in blister formation after pre-treatment of normal skin with intradermal injections of 100 microg/ml compound 48/80 (a mast cell degranulator) or with 0.1% capsaicin cream.

Quantitative digital image analysis applied to demonstrate the stratified distribution of involucrin in organ cultured human skin.

In this study, quantitative digital image analysis was utilized to measure the optical density of immunostains of involucrin at different depths in the epidermis to obtain reliable ordinal-scaled interpretations of the staining intensity. The distribution of involucrin within the epidermis was investigated in air-liquid interface and submerged skin organ cultures at different time-points. A greyscale calibration procedure to standardize the optical units was used.

Mast cells in psoriatic skin are strongly positive for interferon-gamma.

The increased number and early activation of cutaneous mast cells is a typical feature of psoriatic inflammation. Interferon-gamma (IFN-gamma) is believed to be one of the important mediators in the cytokine cascade of psoriasis. Human mast cells have been previously reported to release various cytokines upon stimulation including interleukin (IL) -4, IL-5, IL-6, IL-8, IL-13 and tumour necrosis factor-alpha.

Decreased chymase activity is associated with increased levels of protease inhibitors in mast cells of psoriatic lesions.

Mast cells contain large amounts of the powerful serine proteinases, tryptase and chymase, of which only chymase can be inactivated by serum protease inhibitors. In this study, 20 patients with psoriasis and a control group of 13 with atopic dermatitis were biopsied for lesional and non-lesional skin specimens. The presence of chymase inhibitor alpha 1-proteinase inhibitor (alpha 1-PI), alpha 1-antichymotrypsin (alpha 1-AC), alpha 2-macroglobulin (alpha 2-MG) and C1-esterase inhibitor (C1-Inh) immunoreactivity in mast cells was verified using the sequential double-staining method.

Quantitative analysis of tryptase- and chymase-containing mast cells in atopic dermatitis and nummular eczema.

The distribution of mast cells (MCs) containing tryptase (T) and chymase (C) was studied in the non-lesional and lesional skin of 26 patients with atopic dermatitis (AD) and 23 patients with non-atopic nummular eczema (NE), and in the skin of eight healthy controls. T and C activities were demonstrated enzymehistochemically using Z-Gly-Pro-Arg-MNA and Suc-Val-Pro-Phe-MNA as substrates, respectively. The T- and C-containing MCs were counted separately in the epidermis, in contact with the basement membrane, in the papillary dermis and in different dermal levels (0.

Alterations in mast cell proteinases and protease inhibitors in the progress of cutaneous herpes zoster infection.

The possible involvement of mast cell proteases in the cutaneous inflammation of herpes zoster was studied histochemically in ten patients. Mast cell tryptase and chymase bioactivities were demonstrated enzyme-histochemically. The localization of protease inhibitors as well as tryptase and chymase proteins in mast cells was established using a sequential double-staining method which first demonstrated bioactive tryptase or chymase, followed by immunohistochemical identification of these antigens.

Association of psychic stress with clinical severity and symptoms of psoriatic patients.

The association of stress with psoriatic skin and joint symptoms was studied in 38 patients with psoriasis by dividing the patients into low-stress and high-stress groups based on their answers to four questionnaires (General health questionnaire, Somatization questionnaire, Depression questionnaire, and Life change questionnaire), measuring minor psychiatric disorder, psychosomatic reactivity, depression and life changes, respectively. Compared to the low-stress group (n = 21), the patients in the high-stress group (n = 17) had more severe skin and joint symptoms and a higher score, which in established psoriatic General severity score that was calculated by judging Psoriasis Area and Severity Index, activity of psoriasis and the presence of joint symptoms. All the four questionnaires showed higher morbidity frequency and higher score points.

Quantitative histochemical analysis of mast cells and sensory nerves in psoriatic skin.

To study the elements of neurogenic inflammation in psoriatic skin, morphological contacts were examined between mast cells and sensory nerves containing the neuropeptides substance P (SP), calcitonin gene-related peptide (CGRP) or vasoactive intestinal polypeptide (VIP). Because mast cells in psoriatic lesions appear in great numbers at the basement membrane (BM) zone, neuropeptide-mast cell contacts with the BM were also counted. A double stain for active mast cell tryptase and the neuropeptides was applied and the contacts were quantitated morphometrically.

Neuropeptide- and capsaicin-induced histamine release in skin monitored with the microdialysis technique.

Mast cells are thought to be involved in neurogenic inflammation in skin, and numerous neuropeptides are known to degranulate mast cells. We monitored histamine release in skin in situ with the microdialysis method after skin challenge with neuropeptide injections (10 microM substance P, vasoactive intestinal peptide and calcitonin gene-related peptide), capsaicin injection (30 microM) and 0.1% capsaicin cream with a moist compress.

Histamine release in skin monitored with the microdialysis technique does not correlate with the weal size induced by cow allergen.

The purpose of this study was to monitor histamine release in immediate-type hypersensitivity reactions in the skin of 10 atopic patients, sensitive to cow, by using the microdialysis technique. Three healthy subjects, without any atopic features or background, served as the control group. The probe inserted into the forearm dermal skin was perfused with isotonic saline solution.

Hand eczema in Finnish farmers. A questionnaire-based clinical study.

In a population of 2005 Finnish farmers, 172 (8.6%) reported hand or forearm dermatoses in a self-administered questionnaire. 138 (80%) of them attended a clinical examination.