Search PubMed⌕ Search

Biomedical subjects

B M Henz

Publications and source records attributed to B M Henz.

At least 91 records · Page 5Linked to original sources
PubMed1998

Regulation and possible function of axl expression in immature human mast cells.

The receptor tyrosine kinase Axl which expresses extracellular domains reminiscent of cell adhesion molecules, is involved in homotypic binding as well as in intracellular signaling of myeloid progenitor cells. In order to investigate factors which might influence differentiation pathways through changes of the adhesive properties of cells, we analyzed the expression of axl in immature basophil and mast cell lines and in cultured basophil and mast cell precursors. Axl expression was induced by interferon-alpha in the human leukemic mast cell line HMC-1 and in cultured mast cells derived from CD34+ peripheral blood cells. Axl induction was dose dependent, appeared within 1 h, and was independent of de novo protein synthesis. IFNalpha-treated HMC-1 cells expressing axl formed large cell aggregates within 40 h while untreated cells did not. HMC-1 cells also expressed gas6, the putative ligand of axl, which has been shown to induce axl-mediated homotypic binding. Gas6 expression was independent of interferon treatment in HMC-1 cells. The present results suggest that axl-mediated changes of cellular adhesive properties in mast cells may be important in mast cell differentiation as well as in mast cell-associated inflammation.

Cell Line↗
PubMed1998

Vaccination with IL-7 gene-modified autologous melanoma cells can enhance the anti-melanoma lytic activity in peripheral blood of patients with a good clinical performance status: a clinical phase I study.

Recently, cytokine gene transfer into tumour cells has been shown to mediate tumour regression in animal models via immunomodulation. Consequently, a number of clinical protocols have been developed to treat cancer patients with cytokine gene-modified tumour cells. Here, we report the results of a clinical phase I trial using for the first time autologous, interleukin 7 gene-modified tumour cells for vaccination of ten patients with disseminated malignant melanoma. Melanoma cells were expanded in vitro from surgically removed metastases, transduced by a ballistic gene transfer technique and were then injected after in vitro irradiation s.c. at weekly intervals. Clinically, there was no major toxicity except for mild fever, and no major clinical response towards vaccination was observed. Eight of ten patients completed the initial three s.c. vaccinations and were eligible for immunological evaluation. Post vaccination, peripheral mononuclear cells (PBMCs) were found to contain an increased number of tumour-reactive proliferative as well as cytolytic cells, as determined by a limiting dilution analysis. In three of six patients, the frequencies of anti-melanoma cytolytic precursor cells increased between 2.6- and 28-fold. Two of these patients showed a minor clinical response. Analysis of the autologous tumour cell vaccines regarding IL-7 secretion after gene transfer, HLA class I and class II cell surface expression, secretion of immunosuppressive mediators (TGF-beta1, IL-10) and various melanoma-associated tumour antigens revealed a very diverse expression profile. In conclusion, vaccination using gene-modified autologous melanoma cells induced immunological changes in a group of advanced, terminally ill patients. These changes can be interpreted as an increased anti-tumour immune response. However, immunological modulation was most pronounced in patients in good physical condition. Therefore, patients with minimal tumour load or minimal residual disease might preferentially benefit from tumour cell vaccination in further studies. In order to evaluate the effects of the cytokine gene-modified tumour cell vaccines more precisely, an antigenically better defined vaccine is needed.

Adult↗
PubMed1998

Neutrophilic urticaria: clinical features, histological changes and possible mechanisms.

Neutrophilic urticaria (NU) is a histologically defined entity, but its clinical and pathogenetic aspects are poorly understood. We investigated 22 NU patients whom we identified by examining 118 biopsies of weals. The patients comprised 11 of 20 with acute urticaria, nine of 49 with chronic urticaria, one of 10 with cold urticaria and one of 10 controls undergoing prick tests. Clinically, NU patients had a shorter mean duration of disease than other urticaria patients and significantly increased erythrocyte sedimentation rate and leucocytosis. Histologically, not only neutrophil counts, but to a lesser extent also eosinophil counts and mononuclear cell infiltrates were significantly increased in lesional skin of NU, and there was more marked vasodilatation and endothelial swelling. On immunohistochemistry, increased tumour necrosis factor alpha and interleukin (IL)-3 expression was noted, compared with other urticarias, whereas IL-8 expression was only minor. These data characterize NU as an acute phase urticarial reaction associated with an intense inflammatory infiltrate and marked upregulation of some mast cell-derived cytokines.

Acute Disease↗
PubMed1998

Comparative cytokine gene expression: regulation and release by human mast cells.

Since data on the ability of human mast cells to produce various cytokines are scanty, we examined the mRNA expression, its modulation and the resulting protein expression of a number of well-characterized cytokines, using semi-quantitative reverse transcription-polymerase chain reaction of cell extracts and enzyme-linked immunosorbent assays for analysis of cell supernatants. One million cells/ml of the human mast cell line HMC-1 were stimulated with 25 ng/ml phorbol myristate acetate (PMA), 5 x 10(-7) M calcium ionophore A 23187 (ionophore) or both stimuli combined for various time periods. Constitutive expression in unstimulated cells was found for interleukin-1 beta (IL-1 beta) -3, -4, -8, tumour necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta (TGF-beta). Maximal mRNA up-regulation was observed by 2-4 hr, with a second peak for TNF-alpha at 24 hr. After a 4-hr stimulation, IL-13 expression was detectable as well, whereas for IL-12, only the p35 but not the p40 chain was found, and IL-2, -5, -7 and interferon-gamma (IFN-gamma) were not expressed at all. Large quantities of IL-8, TNF-alpha, granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-3 were secreted time-dependently over a 72-hr period, with lower levels of IL-1 beta, -6, -10 and TGF-beta and no detectable IL-2, -4 and IFN-gamma protein. When IL-6 and IL-8 expression was compared in more detail, IL-6 mRNA was found to be up-regulated only with ionophore but not PMA, whereas both stimuli alone or combined increased IL-8 mRNA expression. Preincubation with cycloheximide inhibited IL-6 but not IL-8 transcription, and incubation of stimulated cells with actinomycin D stabilized IL-8 and also IL-6 mRNA. These data suggest a selective regulation of distinct cytokines in human mast cells at the transcriptional and post-transcriptional levels. Furthermore, the spectrum of cytokines produced by HMC-1 cells supports the well-recognized role of mast cells in immediate-type hypersensitivity reactions as well as their potential colony-stimulating and tissue-remodelling abilities.

Calcimycin↗
PubMed1998

Induction of human leukaemic mast cell differentiation by fibroblast supernatants, but not by stem cell factor.

In order to explore the potential existence of human mast cell growth factors other than stem cell factor (SCF), we have compared SCF to L-cell fibroblast supernatants (LCS) during in vitro mast cell differentiation, using human leukaemic mast cells (HMC-1 cells) which contain a gain-of-function mutated SCF receptor (c-Kit) as model. At baseline, cells exhibited an immature phenotype, with <25% being metachromatic or chloroacetate esterase, tryptase and FcepsilonRIalpha positive. Intracellular levels of histamine, tryptase, TNF-alpha and chymase were low, whereas 83% of cells were c-Kit positive. During a 10 day culture with 30% LCS, a significant, time-dependent increase of all mast cell markers, except for chymase and c-Kit, was observed at the protein and for tryptase and FcepsilonRIalpha also at the mRNA level. Cytoplasmatic granulation and stimulated histamine and leukotriene C4 release were increased as well. In contrast to LCS, rhSCF induced none of these changes in HMC-1 cells. On Sephadex G100 fractionation of LCS, HMC-1 cells increased tryptase activity with fractions between 40 and 60, and below 10 kDa, away from the SCF peak. These data show that HMC-1 cells fail to differentiate in response to SCF and that in addition to SCF, LCS contains other human mast cell growth factors.

Animals↗
PubMed1998

Identification of activating c-kit mutations in adult-, but not in childhood-onset indolent mastocytosis: a possible explanation for divergent clinical behavior.

Mastocytosis represents a mast cell proliferative disease that generally runs a benign clinical course, with spontaneous remissions mostly by puberty in childhood-onset disease, although rare forms, particularly in adult-onset disease, can be associated with (pre)malignant hematologic disorders and very rarely present as mast cell leukemia or malignant mastocytosis. Reasons for this divergent clinical behavior of childhood- versus adult-onset disease are unknown. Recently, two activating mutations in the intracellular domain of the proto-oncogene c-kit, which encodes a tyrosine kinase receptor for the mast cell growth factor stem cell factor, have been detected in the human leukemic mast cell line HMC-1. We have therefore studied lesional skin biopsies from patients with adult- and childhood-onset indolent mastocytosis for the presence of these codon 560 and 816 mutations. C-kit coding DNA sequences were amplified and analyzed by mutation-specific restriction analyses, and mutated polymerase chain reaction products were additionally cloned and sequenced. The codon 816 mutation was found in all six samples from adult patients, but not in any of the 11 specimens from children. In addition, the codon 560 mutation could be demonstrated for the first time in indolent mastocytosis, namely in two of four specimens from adult patients, but not in those from two children. These data thus provide a possible explanation for the divergent clinical behavior of adult- versus childhood-onset indolent mastocytosis, with the first being associated with an activating mutation, possibly as part of a neoplastic process, and the latter representing most likely a reactive process of an as yet unknown pathogenesis.

Adult↗
PubMed1998

Synthesis, storage, and release of vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) by human mast cells: implications for the biological significance of VEGF206.

Mast cells have been implicated in various diseases that are accompanied by neovascularization. The exact mechanisms by which mast cells might mediate an angiogenic response, however, are unclear and therefore, we have investigated the possible expression of vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) in the human mast cell line HMC-1 and in human skin mast cells. Reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed that mast cells constitutively express VEGF121, VEGF165, and VEGF189. After a prolonged stimulation of cells for 24 h with phorbol 12-myristate 13-acetate (PMA) and the ionophore A23187, an additional transcript representing VEGF206 was detectable, as could be verified by sequence analysis. These results were confirmed at the protein level by Western blot analysis. When the amounts of VEGF released under unstimulated and stimulated conditions were compared, a significant increase was detectable after stimulation of cells. Human microvascular endothelial cells (HMVEC) responded to the supernatant of unstimulated HMC-1 cells with a dose-dependent mitogenic effect, neutralizable up to 90% in the presence of a VEGF-specific monoclonal antibody. Flow cytometry and postembedding immunoelectron microscopy were used to detect VEGF in its cell-associated form. VEGF was exclusively detectable in the secretory granules of isolated human skin mast cells. These results show that both normal and leukemic human mast cells constitutively express bioactive VEGF. Furthermore, this study contributes to the understanding of the physiological role of the strongly heparin-binding VEGF isoforms, since these were found for the first time to be expressed in an activation-dependent manner in HMC-1 cells.

Blotting, Western↗
PubMed1998

Differential effects of new-generation H1-receptor antagonists in pruritic dermatoses.

In search of an improved treatment of pruritic dermatoses, we have studied azelastine, a novel H1-receptor antagonist, during a 2-week treatment period, using a double-blind, placebo-controlled design. The potent H1-antagonist cetirizine was used for comparison. Symptoms were recorded daily by the patients on a diary card, using a 4-point scale. The same parameters and adverse events were evaluated at weekly intervals, and global improvement was evaluated at the end of treatment. In all 230 evaluable patients with moderate to severe itching, azelastine caused an overall significant improvement in comparison to placebo (P = 0.02), with significance also for pruritus (P = 0.01 after 1 week and P = 0.02 after 2 weeks). Both drugs reduced itching more effectively in urticaria than in atopic eczema. Azelastine was superior to cetirizine in reducing pruritus, whereas cetirizine caused a more marked reduction of whealing. Both drugs rarely caused fatigue and dry mouth, but taste perversion occurred only in azelastine-treated patients (9.7%) and headaches only with cetirizine (10.4%). Therefore, the two H1-blockers exert differential effects on pruritus verses whealing and a distinctive adverse events pattern. The data also underline the low efficacy of antihistamines in atopic eczema, compared to urticaria.

Adolescent↗
PubMed1998

Most chronic urticaria is food-dependent, and not idiopathic.

Although chronic urticaria is generally thought to be mostly idiopathic, we have recently provided convincing evidence that in the majority of patients, food ingredients provoke the symptoms and sustain the disease. On a diet largely avoiding preservatives, dyes and natural pseudoallergens, 73% of patients experienced remission of more than 6 months duration, starting within the first 3 weeks after initiation of the diet. This response rate is clearly higher than the reported 24% spontaneous remission rate over the same time period. The specificity of the dietary effect was proven 1) by double-blind provocation with pureed pseudoallergen-low versus -rich food and 2) by induction of a clinical response to a 3-week diet low in pseudoallergens, but not to a standard diabetes diet in 3 patients studied in a double-blind crossover design. On double-blind, placebo controlled oral provocation, only 18% of diet-responsive patients reacted to known food preservatives and dyes, but 71% to pureed tomatoes and 44% to their steam extracts. These findings identify naturally occurring pseudoallergens in food as major elicitors of chronic urticaria. In contrast, autoantibodies against Fc epsilonRIalpha have been identified in only about 30% of chronic urticaria patients, and evidence for their truly causative role is still lacking since therapeutic measures work in patients irrespective of the presence or absence of the autoantibodies. For both food intolerance and Fc epsilonRIalpha-autoantibodies in chronic urticaria, the associated pathomechanisms are however still in need of clarification. Meanwhile, the diet-responsiveness in the majority of patients opens new perspectives for the management of chronic urticaria.

Animals↗
PubMed1998

Differential endothelial adhesion molecule expression in early and late whealing reactions.

In order to clarify the pathomechanisms of fleeting versus more persistent wheals, expression of endothelial adhesion molecules was studied in biopsies of lesional and uninvolved skin of 15 patients with different types of whealing reactions, using immunohistochemistry. In wheals of < or = 30 min duration, no increase of ELAM-1 and ICAM-1 was noted. GMP-140 expression was absent in prick tests, but could be demonstrated in lesions of cholinergic and cold urticaria, with a gradual increase of the latter with time. In wheals of > or = 6 h duration, GMP-140 was only weakly expressed whereas ELAM-1 and ICAM-1 were markedly up-regulated in lesional and less so in nonlesional skin of acute, chronic recurrent and delayed pressure urticaria. This differential expression of endothelial adhesion molecules may reflect the activity of mast cell-derived and other mediators during the elicitation phase and explains the persistence of wheals in different types of urticaria.

Allergens↗
PubMed1998

Role of antigen-induced cytokine release in atopic pruritus.

In order to further evaluate the role of cytokines in the induction of atopic pruritus, leukocytes from 10 atopic eczema patients or 10 nonallergic controls were stimulated in vitro with mite or birch pollen antigen for 1 and 4 days. Subjects were prick-tested with the supernatants, and whealing and itching were evaluated 20 and 60 min later. The supernatants were also examined for the contents of GM-CSF, IL-2, IL-6 and IL-8 by ELISA and TNFalpha. Two hours prior to testing, the antihistamine cetirizine (20 mg) or a placebo tablet were given to the patients according to a randomized, double-blind study protocol. After pricking with antigen-stimulated leukocyte supernatants, 6 of 10 patients but no controls reacted mostly at 20 min with whealing and/or pruritus. In the cetirizine-treated group, no decrease in these skin reactions was seen compared to placebo. Analysis for cytokines showed increased levels of IL-8 in allergen-stimulated samples, with no correlation to the induction of itching or whealing by these supernatants. IL-6 levels were low and variable, and GM-CSF, IL-2 and TNFalpha levels were always below standard values. These data show that leukocytes selectively release IL-8 in response to in vitro antigen stimulation. They furthermore provide additional support for the concept that as yet to be identified products play a role in atopic pruritus.

Adolescent↗
PubMed1998

Effects of nerve growth factor (NGF) and other fibroblast-derived growth factors on immature human mast cells (HMC-1).

We have previously shown that fibroblast and keratinocyte supernatants up-regulate expression of mast cell characteristics in the human immature mast cell line HMC-1. This effect could not be induced in HMC-1 cells by the well-known mast cell growth factor stem cell factor (SCF), probably due to mutations of the SCF receptor c-Kit in these cells. Here we report the effects of several known fibroblast- and keratinocyte-derived growth factors, namely nerve growth factor (NGF), basic fibroblast growth factor, platelet-derived growth factor and transforming growth factor-beta, on mast cell differentiation, using HMC-1 cells as a model. NGF, at 0.1-50 ng/ml concentrations, caused a marked, dose-dependent up-regulation of tryptase, Fc epsilon RI and histamine within 10 days of culture, associated with an enhanced expression of mRNA for Fc epsilon RI and mast cell tryptase. On restriction analysis, only mast cell beta-tryptase, but not alpha-tryptase, could be demonstrated. Furthermore, the high-affinity NGF receptor (TrkA) was found at both the transcriptional and protein levels, while expression of the low-affinity NGF receptor was detectable at the mRNA level only. None of the other growth factors caused a significant alteration of the mast cell markers studied when added to HMC-1 cells at concentrations known to be biologically active in other culture systems. Immature human mast cells are thus induced to assume a more mature phenotype in vitro in response to NGF, most probably via stimulation of the high-affinity NGF receptor expressed on these cells. Besides SCF, NGF should therefore be considered as an additional mast cell growth factor that contributes to human mast cell maturation at tissue sites.

Biomarkers↗
PubMed1998

Medium dose isotretinoin for the treatment of acne.

BACKGROUND: Although the efficacy of isotretinoin in the treatment of acne is unquestioned, improvement of patient tolerance and acceptance of the drug are desirable. Furthermore, no data on acne-induced scarring during isotretinoin treatment are available. AIM: In the present study, we have evaluated the efficacy and tolerability of an initial stepwise incremental (n = 83) or an initial high dose (n = 11) and a subsequent medium maintenance dosing of isotretinoin in outpatients treated for acne over a 7 year period. METHODS: Ninety-four patients with moderate to severe acne were treated for a mean duration of 8.3 months, at a mean daily dose of 31.4 mg. Follow-up and final evaluation were done during outpatient visits and with a standardized patient questionnaire. RESULTS: Response to treatment was very good in 62.8% and good in 31.9% of patients, with only one treatment failure. Of the patients, 21.3% required retreatment after a mean interval of 7.7 months. Four patients refused or dropped out from treatment, 27% noted initial mild worsening of their acne, and none experienced severe adverse effects. Scars were present in 89.4% of patients, with improvement occurring in 67.9% during treatment. CONCLUSION: The altogether good to excellent clinical response of acne lesions and acne scars, with a low side effect profile, warrants further study of this simple, modified treatment regimen in patients with acne and acne-induced scarring.

Acne Vulgaris↗
PubMed1997

C3a and C5a stimulate chemotaxis of human mast cells.

The factors that control migration of mast cells to sites of inflammation and tissue repair remain largely undefined. Whereas several recent studies have described chemotactic factors that induce migration of murine mast cells, only stem cell factor (SCF) is known to induce migration of human mast cells. We report here that the anaphylatoxins C3a and C5a are chemotactic factors for the human mast cell line HMC-1, human cord blood-derived mast cells (CBMC) and cutaneous mast cells in vitro. The presence of an extracellular matrix protein, laminin, was required for chemotaxis in response to complement peptides. Migration of mast cells towards C3a and C5a was dose-dependent, peaking at 1 microg/mL (100 nmol/L), and was inhibited by specific antibodies. Pretreatment with pertussis toxin inhibited the anaphylatoxin-mediated migration of HMC-1 cells, indicating that Gi proteins are involved in complement-activated signal transduction pathways in human mast cells. Both C3a and C5a also induced a rapid and transient mobilization of intracellular free calcium ([Ca2+]i) in HMC-1 cells. Besides SCF, other chemotactic factors tested, such as interleukin-3, nerve growth factor, transforming growth factor beta, RANTES (regulated upon activation, normal Tcell expressed and secreted), monocyte chemotactic protein-1 (MCP-1), MCP-2, MCP-3, macrophage inflammatory protein-1alpha (MIP-1alpha), and MIP-1beta, failed to stimulate migration of human mast cells. In summary, these findings indicate that C3a and C5a serve as chemotaxins for human mast cells. Anaphylatoxin-mediated recruitment of mast cells might play an important role in hypersensitivity and inflammatory processes.

Calcium↗
PubMed1997

CD43 (leukosialin, sialophorin) expression is differentially regulated by retinoic acids.

CD43 (leukosialin, sialophorin), a cell-surface associated mucin that is constitutively expressed at high levels on most leukocytes, is thought to be involved in cell activation and adhesion. We here provide evidence that the vitamin A metabolites all-trans and 13-cis retinoic acid up-regulate CD43 on human leukemic (HMC-1) mast cells, as determined by flow cytometry, Western blot analysis, and by semiquantitative reverse transcriptase-polymerase chain reaction. Enhanced CD43 expression was accompanied by a strong increase in anti-CD43-mediated, LFA-1-dependent homotypic aggregation of HMC-1 cells, demonstrating that newly synthesized CD43 is functionally active in transmitting signals across the plasma membrane which result in enhanced cellular adhesion. CD43 expression was also enhanced in response to retinoic acids on isolated human skin mast cells and human monocytes, but not on cells of the basophilic cell line KU-812 and promyelocytic HL-60 cells, indicating that these agents might act in a cell-type specific manner. These combined result-point to a novel aspect in the regulation of CD43. Possibly, vitamin A metabolites act directly on the CD43 gene, since putative retinoic acid response elements have been detected within its regulatory regions.

Antigens, CD↗
PubMed1997

[Systemic treatment of acne with isotretinoin: current status].

Introduced in 1979, isotretinoin remains a major advance in acne therapy. Both hospital- and community-based dermatologists have experience with this valuable drug, which, owing to its causal principle of action, offers a large proportion of patients the prospect of a cure. Isotretinoin is now in use in more than 80 countries and has been prescribed for some six million patients. Based on accumulated clinical findings with the drug, more comprehensive recommendations can now be made with respect to indications, dosing and duration of treatment than was possible when the drug was launched. Experience with the drug also provides a basis for reevaluating its safety profile. Finally, at a time when healthcare resources are limited, it is important to examine the cost-benefit ratio of this acne treatment versus other options. This paper is accordingly intended to provide a critical status report as well as a detailed and balanced set of recommendations for clinical practice.

Acne Vulgaris↗