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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., (© 2023 The Authors. Clinical and Translational Allergy published by John Wiley & Sons Ltd on behalf of European Academy of Allergy and Clinical Immunology.)

While suboptimal pneumococcal vaccination rates have been reported in immunosuppressed patients with rheumatic diseases, data for patients with psoriasis (PsO) or atopic dermatitis (AD) are scarce. Pneumococcal vaccination in Germany is recommended in patients with certain comorbidities, immunosuppression, and/or aged 60 years or above. The aim of this multicenter cross-sectional study was to investigate the pneumococcal vaccination rate in patients with PsO compared to patients with AD and to evaluate patient perceptions. All patients completed a questionnaire on vaccination status and perceptions, patient and disease characteristics, as well as comorbidity. Medical records and vaccination certificates were reviewed. Over the whole cohort (n = 327 PsO (41.9% female), n = 98 AD (42.9% female)), 83.8% and 42.9% of PsO and AD patients, respectively, had an indication for pneumococcal vaccination due to immunosuppressive treatment. The pneumococcal vaccination rate was 14.4% and 10.2% in PsO and AD patients, respectively. The vaccination rate depended significantly on age, working status and presence of psoriatic arthritis. The most common reason for nonvaccination was lacking recommendation by physicians. Higher awareness, particularly for vaccination indication due to immunosuppression among dermatologists, general physicians, and patients, is warranted.

Eosinophilic fasciitis (EF) and generalized morphea (GM) are rare and difficult-to-treat sclerosing skin diseases which may occur in association with hematologic disorders. We present a 66-year-old man with EF and associated Waldenström macroglobulinemia who received combination therapy with rituximab (375mg/m2 every other week, gradually extended to every eight weeks), prednisolone (1.25-30mg/d), and methotrexate (7.5-15mg/w). Three months after rituximab initiation, his skin condition improved steadily accompanied by a significant improvement in joint mobility with only mild and transitory flares (observation period: 59 months under treatment with rituximab). To date, there are five case reports on rituximab treatment of EF/GM with an association to hypergammaglobulinemia in three of those cases. Therapy effected significant improvement in four patients. Our case adds to the hitherto limited evidence that rituximab may be a promising therapeutic strategy for EF/GM in association with hypergammaglobulinemia.

Background and Objective: Dermatophyte infections of the skin and nails are common worldwide and vary between geographical areas and over time. The aim of this study was to determine the epidemiological profile of dermatophytes in Germany with a focus on comparing children with adults., Patients and Methods: In this retrospective multicenter study, mycological dermatophyte culture results in the period 01/2014 to 12/2016 were analyzed according to identified pathogen, age and gender of patients, and type of disease., Results: Of 1,136 infections (children: n = 88, adults: n = 1,048), 50.8 % were clinically classified as onychomycosis, followed by tinea pedis (34.6 %), tinea corporis (16.2 %), tinea manus (16.2 %), tinea capitis (2.5 %), and tinea faciei (1.2 %). The most frequent pathogen was Trichophyton (T.) rubrum (78.6 %), followed by T. interdigitale (14.3 %), T. benhamiae (3.2 %), T. mentagrophytes (2.1 %), and Microsporum canis (1.7 %). The fungal spectrum differed particularly in tinea corporis and tinea capitis between children and adults with a more diverse pathogen spectrum in children. Trichophyton tonsurans was rarely identified as cause for tinea corporis (2.7 %) or tinea capitis (3.3 %)., Conclusions: Differences in pathogens and frequency of fungal infections between age groups should be considered for optimal selection of the appropriate therapeutic regimen., (© 2021 The Authors. Journal der Deutschen Dermatologischen Gesellschaft published by John Wiley & Sons Ltd on behalf of Deutsche Dermatologische Gesellschaft.)

Introduction: The COVID-19 pandemic dramatically disrupts health care around the globe. The impact of the pandemic on chronic urticaria (CU) and its management are largely unknown., Aim: To understand how CU patients are affected by the COVID-19 pandemic; how specialists alter CU patient management; and the course of CU in patients with COVID-19., Materials and Methods: Our cross-sectional, international, questionnaire-based, multicenter UCARE COVID-CU study assessed the impact of the pandemic on patient consultations, remote treatment, changes in medications, and clinical consequences., Results: The COVID-19 pandemic severely impairs CU patient care, with less than 50% of the weekly numbers of patients treated as compared to before the pandemic. Reduced patient referrals and clinic hours were the major reasons. Almost half of responding UCARE physicians were involved in COVID-19 patient care, which negatively impacted on the care of urticaria patients. The rate of face-to-face consultations decreased by 62%, from 90% to less than half, whereas the rate of remote consultations increased by more than 600%, from one in 10 to more than two thirds. Cyclosporine and systemic corticosteroids, but not antihistamines or omalizumab, are used less during the pandemic. CU does not affect the course of COVID-19, but COVID-19 results in CU exacerbation in one of three patients, with higher rates in patients with severe COVID-19., Conclusions: The COVID-19 pandemic brings major changes and challenges for CU patients and their physicians. The long-term consequences of these changes, especially the increased use of remote consultations, require careful evaluation., (© 2020 The Authors. Allergy published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

Background: Chronic urticaria (CU) is a common disease which represents a considerable burden for many patients. The current urticaria guideline describes the evidence-based diagnosis and treatment of CU. In addition, however, questions often arise in everyday practice that are not addressed by the guideline., Methods: In May 2020, a digital meeting with German urticaria experts was held, in which practical aspects of CU treatment were discussed and supporting aids for everyday clinical treatment formulated. The resulting advice in this document focus on practical questions and the available literature and experiences of the participants., Results: The diagnosis of CU can be made in a short time by means of a thorough anamnesis, a physical examination, and a basic laboratory chemical diagnosis. For this purpose, practical recommendations for everyday practice are given in this paper. An extended diagnosis is only indicated in a few cases and should always be carried out in parallel with an effective therapy. In general, CU should always be treated in the same way, regardless of whether wheals, angioedema or both occur. Symptomatic therapy should be carried out according to the treatment steps recommended by the guidelines. This publication provides practical advice on issues in everyday practice, such as the procedure in the current coronavirus disease 2019 (COVID-19) pandemic, the cardiac risk under higher dosed H1 antihistamines, the self-administration of omalizumab as well as vaccination under omalizumab therapy. In addition to treatment recommendations, topics such as documentation in the practice and family planning with urticaria will be discussed., Discussion: These supporting treatment recommendations serve as an addendum to the current CU guideline and provide support in dealing with CU patients in everyday practice. The aim is to ensure that patients suffering from CU achieve complete freedom of symptoms with the help of an optimal therapy., Supplementary Information: The online version of this article (10.1007/s40629-021-00162-w) contains supplementary material, which is available to authorized users., Competing Interests: Conflict of interestA. Bauer received fees for lectures and advisory boards of Novartis, Biofrontera, Shire/Takeda and Leo Pharma as well as research support from Novartis during the last three years. She has been involved in clinical trials with drugs from Novartis, Lilly, Regeneron, Sanofi, Leo Pharma, and Genetec. H. Dickel received fees from Novartis for lectures and advisory boards. He is also involved as PI in clinical studies with preparations from Novartis and Leo Pharma. T. Jakob has received fees for lectures and advisory boards from Novartis, ALK-Abéllo, Allergopharma, Bencard, Thermo Fischer and Celegene, as well as research support from Novartis and ALK-Abéllo. He is also a member of the extended board of the German Society for Allergology and Clinical Immunology and editor of the Allergo Journal and Allergo Journal International. A. Kleinheinz received financial support from Novartis, LEO, Sanofi, Galderma, Abbvie, Janssen, Medac, Almirall, Amgen, Celgene, Genentech, GSK, Lilly, Parexel, Pfizer and proinnovera as a speaker and for participation in clinicial studies. U. Lippert received fees for lectures or advisory boards lasting several hours in the last three years from Novartis, Shire/Takeda, ALK-Abéllo, Meda Pharma GmbH and Sanofi. She received research grants and consulting fees from Novartis and travel expenses from Novartis and Shire/Takeda. She has also been involved as LKP and PI in clinical trials with preparations from Regeneron, Sanofi and Novartis. M. Metz received fees as speaker and/or consultant for Amgen, Aralez, argenx, Moxie, Novartis, Roche, Sanofi and Uriach. S. Schliemann is an investigator in studies by Novartis Pharma GmbH, Sanofi GmbH, Eli Lilly and Company Limited, LEO Pharma GmbH, Pierre Fabre Dermo-Cosmetique, has received lecture fees from Novartis Pharma GmbH, Sanofi GmbH, LEO Pharma GmbH and HAL Allergy GmbH and research support from Novartis Pharma GmbH. U. Schwichtenberg: AbbVie Deutschland GmbH, Almirall Hermal GmbH, Amgen, Beiersdorf Derma Medical GmbH, Celgene GmbH, Dermapharm GmbH, Janssen Cilag GmbH, Johnson & Johnson GmbH, LEO Pharma GmbH, L’Oréal GmbH, MEDA Pharma GmbH, Merz Pharmaceuticals GmbH, MSD SHARP & DOHME GmbH, Novartis Pharma GmbH, and Pfizer GmbH, Sanofi-Aventis Deutschland GmbH—fees for lectures, advisory boards, study participation, Medical Project Design GmbH Shareholder and Managing Director, Professional Association of German Dermatologists Bremen State Chairman, Association of Statutory Health Insurance Physicians Bremen Member of the Assembly of Representatives and Chairman of the Honorarium Distribution Scale Committee, Member of the Finance Committee. P. Staubach is or recently was a speaker and/or advisor for and/or has received research funding from AbbVie, Allergika, Almirall, Amgen, Beiersdorf, Biocryst, Biogen Idec, BMS, Boehringer-Ingelheim, Celgene, CSL-Behring, Eli-Lilly, Galderma, Hexal, Janssen, Klosterfrau, LEO-Pharma, LETI-Pharma, L’Oreal, Novartis, Octapharma, Pfizer, Pflüger, Pharming, Regeneron, Shire, Takeda, Regeneron, Sanofi-Genzyme und UCB Pharma. E. Valesky has received honours for lectures and consultancy work for the companies Novartis, Bencard, Alk-Abello, JUZO, Kreussler and Sigvaris over the last three years. N. Wagner received fees for lectures or advisory boards lasting several hours in the last three years from Novartis, Shire/Takeda, ALK-Abéllo, Allergopharma, Abbvie, as well as research support from Novartis. In addition, she was involved as PI in clinical trials with Novartis products. B. Wedi received fees for lectures or advisory boards lasting several hours over the last three years from Novartis, Shire/Takeda, ALK-Abéllo, Bencard, CSL-Behring, HAL-Allergy and Leo Pharma as well as research support from Shire/Takeda. She has also been involved as LKP or PI in clinical trials with Novartis products. M. Maurer is or recently was a speaker and/or advisor for and/or has received research funding from Allakos, Amgen, Aralez, ArgenX, AstraZeneca, Celldex, Centogene, CSL Behring, FAES, Genentech, GIInnovation, Innate Pharma, Kyowa Kirin, Leo Pharma, Lilly, Menarini, Moxie, Novartis, Roche, Sanofi/Regeneron, Third HarmonicBio, UCB, and Uriach., (© The Author(s) 2021.)

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., (© 2020 Wiley Periodicals LLC.)

Background: Pityriasis rubra pilaris (PRP) is a rare chronic inflammatory dermatosis. Treatment is challenging and mostly based on scarce empirical evidence from large case series., Objective: To investigate patient characteristics and therapy outcomes in patients with PRP., Materials & Methods: In this retrospective study, patients with PRP treated at the Department of Dermatology, University Medical Center Göttingen, between 01/2005 and 10/2018, were analysed according to patient and disease characteristics and treatment experience., Results: PRP was diagnosed in 28 patients with a mean age of 57.3 years at onset; 20 were men (71.4%) and eight women (28.6%). Of all the patients, 89.3% had comorbid diseases; metabolic disorders were particularly frequent. Seventy-eight treatment courses were identified with acitretin as the most common therapy (28.2%). Excellent response was noted in 71.4% of treatment courses with methotrexate, followed by cyclosporine (27.3%) and acitretin (19.0%). Among biologics, ustekinumab (excellent response: 75.0%) and infliximab (50.0%) were particularly effective., Conclusion: This study is one of the few comprehensive larger case series of patients with PRP. Acitretin may be effective, particularly for type I PRP, and other retinoids, methotrexate or cyclosporine might also be considered early in the therapeutic algorithm. Moreover, our data adds to the growing evidence that biologics are effective and safe for the treatment of PRP.

Background: Hereditary angioedema (HAE) is a group of genetic diseases characterized by recurrent, painful and potentially lethal tissue swelling. The most common form results from mutations in the SERPING1 gene, leading to reduced function of complement 1 inhibitor (C1-INH). Rarer forms with normal C1-INH may arise from mutations in the coagulation factor F12 gene, but mostly the genetic background is unknown. Recently, a novel HAE mutation in the plasminogen (PLG) gene was shown., Patients and Methods: We analyzed the various clinical manifestations of HAE in 14 related patients using clinical data, biochemical analysis for C1-INH and C4 as well as gene sequencing., Results: Patients' symptoms were assigned to two different forms of HAE. In ten patients suffering from swelling of the lips or tongue but not of the extremities, a mutation in the PLG gene (c.988A>G) was found whereas in the only four patients with swelling of the gastrointestinal tract and extremities, a mutation in the SERPING1 gene (c.1480C>T) was identified. In two cases this was additional to PLG c.988A>G., Conclusions: This unique finding of two different HAE-specific mutations in a large family not only explains the divergent phenotypes but also supports a genotype-phenotype correlation showing that abdominal attacks and swelling of the extremities are common with HAE-C1-INH but unusual with HAE-PLG., (© 2020 Deutsche Dermatologische Gesellschaft (DDG). Published by John Wiley & Sons Ltd.)

Background and Objectives: Proper management of infantile scabies is indispensable in order to prevent prolonged duration and spread of the disease. Data are still lacking that support topical treatment with permethrin 5 % cream in infants under two months of age, and application remains off-label for this age group., Patients and Methods: We identified infants younger than two months who suffered from scabies in order to evaluate the safety and efficacy of topical treatment with permethrin cream in this age group. Diagnosis of scabies was based on the typical symptoms and pathognomonic features as determined with dermoscopy. We analyzed the efficacy and safety of the therapies that were applied., Results: Seven scabies patients under two months of age were treated with permethrin 5 % cream. Topical therapy was repeated up to three times in four patients due to incomplete resolution or recurrence of skin lesions., Conclusions: Permethrin therapy was well tolerated in all seven infants, even when conducted several times. Our results confirm that the use of permethrin 5 % cream in children younger than two months of age is safe., (© 2019 Deutsche Dermatologische Gesellschaft (DDG). Published by John Wiley & Sons Ltd.)

Sarcoidosis is a rare, systemic disease that is characterized by the formation of granulomas in various organs, including the skin. As the etiology remains unknown, the treatment of sarcoidosis is challenging. We present a 47-year-old female patient with progressive, multi-organ sarcoidosis who had a complete clinical improvement of the skin lesions, a moderate reduction in pulmonary opacities on chest X-ray, a marked subjective improvement in general status and pulmonary efficiency and a marked reduction in serum angiotensin-converting enzyme and soluble interleukin-2 receptor after 6 months of therapy with fumaric acid esters. The present case and similar reports in the literature highlight the probable efficacy of fumaric acid esters in the treatment of sarcoidosis and other non-infectious, granulomatous diseases., (© 2014 S. Karger AG, Basel.)

An 11-month-old boy was brought to our clinic with superinfected, sharply-defined, symmetrical, erythematous macules and vesicles, some with yellowish-brownish crusts, on the cheeks, fingers, and in the diaper region. The suspected impetigo contagiosa had failed to respond to both topical antiseptic therapy and systemic antibiotics. Because of the unusual clinical picture and course, we measured the serum zinc level. A significantly reduced level of 2 μmol/l (normal range 9.2-18.4 μmol/l) was identified. Initial skin lesions had appeared one week after weaning (5th week after birth). Since the age of 8 months the infant had also had recurrent diarrhea. Two weeks after zinc-histidine substitution, the diarrhea ceased and skin lesions slowly disappeared. Molecular genetic testing for the SLC39A4 (zinc transporter) gene revealed compound heterozygosity for the previously unidentified mutations c.1465_1474+4del (p.?) and c.295G>A (p.Ala99Thr). The parents are healthy heterozygous gene carriers. The same compound heterozygosity was later detected in the newborn brother of our patient shortly after birth. A zinc deficiency could therefore be identified and treated before symptoms occurred. The inherited autosomal recessive zinc transporter deficiency is termed acrodermatitis enteropathica. Lifelong zinc substitution is recommended. A differential diagnosis can be difficult because bacterial and fungal superinfection is common in zinc deficiency. Precise diagnosis requires testing family members for the gene., (© The Authors • Journal compilation © Blackwell Verlag GmbH, Berlin.)

Autoimmune bullous skin disorders are induced by autoantibodies against distinct adhesion complexes of the epidermal and dermal-epidermal junction. Since most of these disorders are characterized by a severe, potentially lethal course,they require long-term immunosuppressive treatment to reduce the de novo synthesis of pathogenic autoantibodies by B lymphocytes. Rituximab, a chimeric monoclonal antibody against CD20 on B lymphocytes, has shown promise in several case reports or cohort studies in the treatment of paraneo-plastic pemphigus,refractory cases of pemphigus vulgaris and foliaceus and in other autoimmune bullous disorders. Treatment with rituximab leads to depletion of pathogenic B-cells which may last up to 12 months resulting in a reduction of plasma cells secreting pathogenic autoantibodies. Rituximab is usually administered in an adjuvant setting at a dose of 375 mg/m(2) i.v.in weekly intervals for four consecutive weeks in addition to the standard immunosuppressive treatment. The present consensus statement of German-speaking dermatologists, rheumatologists and oncologists summarizes and evaluates the current evidence for the use and mode of application of rituximab in autoimmune bullous skin disorders.

T cell activation via dendritic cells (DC) is an important step in the adaptive immune response, which requires DC maturation, migration to lymph nodes and presentation of antigen to T cells. CD137 receptor expressed on activated T cells is a potent costimulatory molecule. Here, we investigated the functions of CD137 ligand (CD137L) in human monocyte-derived DC during an immune response. Cross-linking of CD137L on DC leads to cell maturation in an autocrine fashion, mostly via release of TNF-alpha. Reverse signaling of CD137L also mediates migration of DC via up-regulation of the CCR7 chemokine receptor, demonstrated by an in vivo MIP-3beta-dependent SCID mouse migration model. Finally, CD137L-activated DC induce differentiation of human T cells into potent Th1 effectors. Cocultivation of autologous T cells and CD137L-activated DC in an antigen-specific reaction leads to T cell proliferation and the release of IL-12p70 and IFN-gamma. These findings deliver new insights into the multiple effects of reverse signaling of CD137L in human DC during the initiation of an adaptive immune response, including the key features of DC maturation, migration and, ultimately, antigen-specific T cell differentiation.

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.

The structure and mode of binding of the endoplasmic reticulum protein disulfide isomerase-related proteins to their substrates is currently a focus of intensive research. We have recently determined the crystal structure of the Drosophila melanogaster protein disulfide isomerase-related protein Wind and have described two essential substrate binding sites within the protein, one within the thioredoxin b-domain and another within the C-terminal D-domain. Although a mammalian ortholog of Wind (ERp29/28) is known, conflicting interpretations of its structure and putative function have been postulated. Here, we have provided evidence indicating that ERp29 is indeed similar in both structure and function to its Drosophila ortholog. Using a site-directed mutagenesis approach, we have demonstrated that homodimerization of the b-domains is significantly reduced in vitro upon replacement of key residues at the predicted dimerization interface. Investigation of Wind-ERp29 fusion constructs showed that mutants of the D-domain of ERp29 prevent transport of a substrate protein (Pipe) in a manner consistent with the presence of a discrete, conserved peptide binding site in the D-domain. Finally, we have highlighted the general applicability of these findings by showing that the D-domain of a redox-active disulfide isomerase, from the slime mold Dictyostelium discoideum, can also functionally replace the Wind D-domain in vivo.

Membrane fusion in the secretory pathway is mediated by soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) proteins. Different fusion steps are thought to be effected by independent sets of SNAREs, but it is unclear whether specificity is determined by an intrinsic specificity of SNARE pairing or by upstream factors. Using a newly developed microscopy-based assay, we have investigated the SNARE specificity of homotypic early endosomal fusion. We show that early endosomes contain multiple sets of SNAREs, including, in addition to the putative early endosomal SNAREs, those involved in exocytosis and in fusion of late endosomes. We demonstrate that fusion is largely mediated by a complex formed by syntaxin 13, syntaxin 6, vti1a, and VAMP4, whereas the exocytic and late endosomal SNAREs play little or no role in the reaction. In contrast, proteoliposomes reconstituted with early endosomal SNAREs promiscuously fuse with liposomes containing exocytotic or late endosomal SNAREs. We conclude that the specificity of SNARE pairing does not suffice to determine the specificity of organelle fusion.

Background: Mast cells are resident tissue cells that induce anaphylactic reactions by rapidly releasing mediators after antigen-mediated cross-linking of immunoglobulin E receptors. In the similarly active peripheral blood basophilic leukocyte, lysosome-associated membrane protein 3 (LAMP-3; CD63) has been described as an activation marker, but LAMPs have not been investigated in normal tissue mast cells., Methods: Intra- and extracellular expressions of LAMP-1 (CD107a), LAMP-2 (CD107b), and LAMP-3 (CD63) were analysed by flow cytometry, immunocytochemistry, and functional assays in unstimulated and stimulated leukemic human mast cell line 1 (HMC-1) and skin mast cells., Results: On flow cytometry, all mast cells expressed LAMP-3 at their cell membranes, whereas LAMP-1 and LAMP-2 were barely detectable (HMC-1 cells) or expressed at low levels (<10% of skin mast cells). After fixation and permeabilisation, high intracellular levels of all three LAMPs were noted in both cell types. After stimulation, a rapid translocation of intracellular LAMPs to the cell membrane, with an associated release of histamine, leukotriene C(4) and prostaglandin D(2), was ascertained in skin mast cells only., Conclusion: These results show that LAMP-1 and LAMP-2 are activation markers for normal mast cells. The lack of LAMP translocation after activation of leukemic mast cells may be related to maturation or malignancy-associated defects of these cells., (Copyright 2004 Wiley-Liss, Inc)

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.

Mast cells generate and release histamine during anaphylactic reactions, and there is pharmacological evidence that histamine regulates this process via specific receptors. Therefore, we examined human leukemic (HMC-1) and normal skin mast cells for the expression of all four currently known histamine receptors. Both cell types expressed H2 and H4 receptors at mRNA and protein levels, whereas H3 receptor specific mRNA and receptor protein was undetectable. Similarly, immunohistochemistry of cutaneous tissue showed an absence of H3 receptor in these cells. Despite transcription of mRNA, H1 receptor protein was only moderately expressed in HMC-1 cells and was virtually absent in skin mast cells. Furthermore, only H1, H2, and H4 receptors were detectable by Western blot analysis of HMC-1 cells. Radiolabeled histamine binding was strongly inhibited only by H2 (ranitidine)- and H3/H4 (FUB 108)-specific antagonists. Histamine-induced increase of cAMP was inhibited by the H2 receptor antagonist famotidine, whereas induction of IP3 was not observed, making signaling via the H1 receptor unlikely. These data show that human mast cells constitutively express primarily H2 and H4 receptors and that H2 receptors are functionally linked to cellular processes. They provide new insights into the mechanisms that govern auto- and paracrine histamine-induced mast cell functions.

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.