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Abstract: Mast cells are important players in innate immunity and mediate allergic responses. Upon stimulation, they release biologically active mediators including histamine, cytokines and lysosomal hydrolases. We used permeabilized rat basophilic leukaemia cells as model to identify R-SNAREs (soluble NSF (N-ethylmaleimide-sensitive fusion protein)) mediating exocytosis of hexosaminidase from mast cells. Of a complete set of recombinant mammalian R-SNAREs, only vesicle associated membrane protein (VAMP8)/endobrevin consistently blocked hexosaminidase release, which was also insensitive to treatment with clostridial neurotoxins. Thus, VAMP8, which also mediates fusion of late endosomes and lysosomes, plays a major role in hexosaminidase release, strengthening the view that mast cell granules share properties of both secretory granules and lysosomes. [Copyright &y& Elsevier]

Lippert U, Zachmann K, Henz BM, Neumann C. Human T lymphocytes and mast cells differentially express and regulate extra- and intracellular CXCR1 and CXCR2. CXCL8 plays a major role in cell recruitment to sites of inflammation. Apart from neutrophils, little is known, however, about the cellular distribution and regulation of CXCL8 receptors in cells involved in acquired and adaptive immune responses. In previous studies, we have demonstrated the extracellular expression and function of CXCR1/2 on mast cells and also detected an intracellular pool of CXCR1/2. Here, we have addressed the question of receptor regulation during stimulation of human mast cells (HMC-1 cell line) and have studied T cells in comparison. Cell permeabilization was performed to detect both surface and possible intracellular receptor pools. HMC-1 cells stained positive for both receptors on the cell surface (CXCR1, 50%; CXCR2, 51%) and also after cell permeabilization (CXCR1, 86%; CXCR2, 74%). Similarly, T cells exhibited both cell-surface receptor expression (CXCR1, 30%; CXCR2, 23%) and higher total receptor expression (CXCR1, 50%; CXCR2, 36%), although overall values were lower than that in HMC-1 cells. On immunoblot, molecular weights of extra- and intracellular receptors on mast cells were the same, excluding altered receptor glycosylation. On stimulation with phorbol 12-myristate 13-acetate plus calcium ionophore, a time-dependent decrease of surface-membrane receptors was observed in both cell types, while total receptor remained the same, suggesting that receptor shedding is not involved. The kinetics of membrane receptor internalization and replenishment differed for the two cell types. Furthermore, receptor internalization was associated with decreased F-actin polymerization, a basic prerequisite for cell migration. These findings demonstrate for the first time the expression of extra- and intracellular CXCR1/2 receptors on T cells and delineate the dynamics of CXCR1/2 receptors on mast cells and T cells. Furthermore, they suggest a cell-type-specific and finely tuned regulation of chemokine responses at the receptor level in the context of inflammation. [ABSTRACT FROM AUTHOR]

Background: Urticarial vasculitis (UV) should be differentiated from chronic spontaneous urticaria (CSU) in patients initially presenting with recurrent wheals, although criteria for differential diagnosis remain ill‐defined. Objectives: To set the goals, define criteria and unmet needs in UV diagnosis and differential diagnosis with CSU, and explore the possibility of coexistence of both diseases. Methods: Thirteen experts experienced in UV research participated in a Delphi survey of European Academy of Allergy and Clinical Immunology taskforce. This Delphi survey involved three rounds of anonymous responses to n = 32 questions with the aim to aggregate the experts' opinions and to achieve consensus. Urticaria specialists (n = 130, most from Urticaria Centers of Reference and Excellence) evaluated the consensus statements and recommendations in the fourth and final round. Results: The panel agreed that essential criteria to guide a skin biopsy in patients with recurrent wheals should include at least one of the following features: wheal duration >24 h, bruising/postinflammatory hyperpigmentation, and systemic symptoms. Leukocytoclasia and fibrin deposits were identified as a minimum set of UV histological criteria. As agreed by the panel members, CSU and normocomplementemic UV (NUV) may coexist in some patients. Conclusions: The use of established criteria for the diagnosis and differential diagnosis of UV in patients with recurrent wheals can help guide the diagnostic approach and prompt earlier treatment. Further studies should investigate whether CSU and NUV are different entities or part of a disease spectrum. [ABSTRACT FROM AUTHOR]

Background/Objectives: Para‐phenylenediamine, a dye frequently added to henna tattoos to create the black color, is a potent contact allergen. Severe contact dermatitis may arise within days even after the first application. Our objective was to develop a method for rapid and complete removal of para‐phenylenediamine‐containing black henna tattoos from the skin, an important problem many physicians are confronted with, but for which no simple method exists. Methods: A database search revealed polyethylene glycol 400, described in removal of ortho‐phenylenediamine from contaminated skin. We therefore investigated its use in removal of the structurally related ortholog para‐phenylenediamine present in black henna tattoos. Results: A protocol was established involving repeated cycles of rinsing of the skin with polyethylene glycol 400 solution. In 5 patients, one of whom had already developed a severe blistering contact dermatitis and another a mild erosive dermatitis, black henna tattoos were successfully removed. Removal was completed in a single session of 1 hour or less, depending on tattoo size, with a maximum of 6 rinse cycles. Conclusions: We provide a simple and safe method for rapid and effective removal of black henna tattoos. This procedure requires no special equipment and can be applied in virtually any setting. [ABSTRACT FROM AUTHOR]

Ständer S, Moormann C, Schumacher M, Buddenkotte J, Artuc M, Shpacovitch V, Brzoska T, Lippert U, Henz BM, Luger TA, Metze D, Steinhoff M. Expression of vanilloid receptor subtype 1 in cutaneous sensory nerve fibers, mast cells and epithelial cells of appendage structures. The vanilloid receptor subtype 1 (VR1)/(TRPV1), binding capsaicin, is a non-selective cation channel that recently has been shown in human keratinocytes in vitro and in vivo. However, a description of VR1 localization in other cutaneous compartments in particular cutaneous nerve fibers is still lacking. We therefore investigated VR1 immunoreactivity as well as mRNA and protein expression in a series ( n = 26) of normal ( n = 7), diseased ( n = 13) [prurigo nodularis (PN) ( n = 10), generalized pruritus ( n = 1), and mastocytosis ( n = 2)], and capsaicin-treated human skin ( n = 6). VR1 immunoreactivity could be observed in cutaneous sensory nerve fibers, mast cells, epidermal keratinocytes, dermal blood vessels, the inner root sheet and the infundibulum of hair follicles, differentiated sebocytes, sweat gland ducts, and the secretory portion of eccrine sweat glands. Upon reverse transcriptase-polymerase chain reaction and Western blot analysis, VR1 was detected in mast cells and keratinocytes from human skin. In pruritic skin of PN, VR1 expression was highly increased in epidermal keratinocytes and nerve fibers, which was normalized after capsaicin application. During capsaicin therapy, a reduction of neuropeptides (substance P, calcitonin gene-related peptide) was observed. After cessation of capsaicin therapy, neuropeptides re-accumulated in skin nerves. In conclusion, VR1 is widely distributed in the skin, suggesting a major role for this receptor, e.g. in nociception and neurogenic inflammation. [ABSTRACT FROM AUTHOR]