Biomedical subjects
B M Czarnetzki
Publications and source records attributed to B M Czarnetzki.
The renin-angiotensin-system in the skin. Evidence for its presence and possible functional implications.
Among the several hormonal systems regulating body functions, the renin-angiotensin-system has long been considered a classical endocrine system with angiotensin II, its effector hormone, being synthesized in and subsequently distributed by the circulation to act on its numerous, mainly renal and cardiovascular target organs throughout the body. Angiotensin II has long been regarded to be primarily responsible for the regulation of blood-pressure and of volume- and electrolyte-homeostasis. Recent evidence suggests that it also affects cellular proliferation and differentiation via the so-called local or tissue-renin-angiotensin-systems. Such trophic actions have already been observed in tissues not belonging to the renal or cardiovascular systems such as cultured cells of neuronal origin. Evidence for a rôle of angiotensin II in the skin is so far scanty and mainly based on the demonstration of angiotensin receptors on cultured human keratinocytes and in subcutaneous tissue of rats. Although almost every single component of the renin-angiotensin-system has already been identified in skin of one or another species, comprehensive data regarding the skin renin-angiotensin-system as a whole within one particular species, especially in man, are still lacking. The present manuscript reviews novel recent data regarding the renin-angiotensin-system particularly in skin, and it discusses a possible functional rôle of the cutaneous renin-angiotensin-system on the basis of these findings.
Differential promoter activity in benign and malignant human cells of skin origin.
In order to develop systems to express mammalian proteins in human skin-derived cells, we tested 6 different viral and 1 eukaryotic promoter (pCMV, pRSV, pSV, pMMTV, pPoly E, pPoly L, pHMT) for their ability to drive the expression of the chloramphenicol acetyltransferase (CAT) enzyme in different human skin-derived cells. DNA was transfected in human keratinocytes derived from normal foreskin and cervix, in the HPV-negative cervical cancer line HT-3 and in malignant melanoma cell lines (SK-Mel 23, SK-Mel 37) using a liposome-based technique or calcium precipitation. Transfection efficacy was controlled by cotransfection of a beta-galactosidase gene construct. The enzymatic activity of the CAT-gene expression was determined by incubation of the cell extract prepared from the transfected cells with 14 C-labeled chloramphenicol. The CMV-promoter was highly active in all skin- or mucosal-derived cells. In contrast to the strong CMV-promoter, the RSV-, SV-, and HMT-promoter were less active and varied in dependence of the cell type. The pattern of the promoter activity differed between benign and transformed genital keratinocytes. Only the SV-promoter showed a comparable strong basal activity, which was restricted to the SK-Mel 37 cells. In conclusion, the promoter activity has to be tested for each cell type depending on the aims of the gene expression.
Interferon-gamma downregulates epidermal growth factor receptors on human melanoma cells.
Unregulated expression of epidermal growth factor receptor (EGF-R) is a common event in neoplastic transformation and has been shown to be associated with melanocytic tumor progression. Modulation of such a receptor by pharmacological agents could therefore be of clinical interest. We have studied EGF-R expression, its response to epidermal growth factor (EGF) and modulation effects by interferon gamma (IFN gamma) on human melanoma cells. Addition of EGF, anti-EGF and anti-EGF-R antibodies had no effect on proliferation of six melanoma cell lines tested. We report in this communication that EGF-R expression on human melanoma cells can be modulated by IFN-gamma. In the melanoma cell lines treated with IFN gamma, proliferative behavior was not affected; however, we demonstrate a downregulation of EGF-R expression on the protein level, by immunohistochemistry and flow cytometric analysis, and an accumulation of EGF-R mRNA by Northern blot analysis. The results suggest that IFN gamma downregulates EGF-R expression at a posttranscriptional level on human melanoma cells. This EGF/EGF-R interaction and its modulation by IFN gamma on human melanoma cells needs to be further clarified regarding its in vivo significance for the treatment and prognosis of malignant melanoma.
Interleukin-6 expression in the skin of patients with lupus erythematosus.
It has been proposed that interleukin-6 may play a role in the pathogenesis of autoimmune diseases like lupus erythematosus. We have therefore investigated the immunoreactivity of IL-6 in 32 skin biopsies of 23 patients suffering from chronic discoid lupus erythematosus (n = 16), subacute cutaneous lupus erythematosus (n = 5) and systemic lupus erythematosus (n = 5) as well as in uninvolved skin (n = 6) and in normal skin from healthy volunteers (n = 3). Increased immunohistochemical staining was detectable in 14 of 26 biopsies from lesional skin. The remaining biopsies from lesional, non-lesional and normal skin displayed only minimal or no reactivity, but 8 out of 12 lupus erythematosus patients had been pretreated with local or systemic antiinflammatory drugs. Irrespective of the LE subtype, immunolabelling was generally most intense in the basal layer of the epidermis, with additional intense suprabasal staining in sections from 2 of 5 SLE patients. Preferential production of IL-6 in the lower parts of the epidermis was confirmed by RNA in situ hybridization. No correlation was found between the deposition of immunoglobulins and complement at the dermo-epidermal junction and IL-6 expression in keratinocytes. These data suggest that IL-6 may be involved in LE although its exact role in the pathogenesis of the disease needs to be further elucidated.
Mast cells in the cytokine network: the what, where from and what for.
The basic understanding of mast cell ontogeny and function has been fundamentally changed in recent years with observations that the cells produce and respond to a broad range of cytokines. These rapidly accruing data and their potential significance were discussed at the recent symposium "Mast Cells in the Cytokine Network", and the overview lectures of most speakers are summarized in this special journal issue. In the present introductory manuscript, the organizers of the meeting discuss data fundamental to an understanding of the topic and highlight aspects of special interest. They consider mast cells to be defined most reliably by their unique ultrastructure since the cells are highly heterogeneous in dependence of the species studied, their tissue location, their stage of development and probably also in relation to cytokines. Most other characteristics of mast cells are shared with diverse other cell types. Murine mast cell development is induced by several cytokines. These factors are mostly ineffective in human cells except for stem cell factor which causes mast cell development from CD34+/c-kit+ progenitors. There is however recent evidence that fibroblasts and keratinocytes produce additional growth factors for human mast cells. Regarding cytokine secretion, most molecules known so far are produced by both murine and human mast cells. The cells furthermore bear receptors for several cytokines, enabling them to respond in an autocrine and paracrine fashion. Mast cells may thus function within a complex cytokine network, affecting physiological as well as immunological and inflammatory processes.
Cytokine secretion by human mast cells.
Mast cells have been traditionally viewed as effector cells of immediate-type hypersensitivity reactions. Besides this, mast cell activation and degranulation have been associated with various biologically and clinically important functions. Results of the past few years suggest that mast cells are involved in the development of late-phase reactions and influence other chronic inflammatory responses through the generation and secretion of various multipotential cytokines.
Mast cells as modulators of hair follicle cycling.
While the central role of mast cells (MC) in allergy and inflammation is well-appreciated, much less is known about their physiological functions. The impressive battery of potent growth modulatory MC products, and increasing evidence of MC involvement in hyperproliferative and fibrotic disorders suggest that tissue remodelling may be one of those, namely in the skin. Here, we delineate why this may best be studied by analysing the potential role of MC in hair growth regulation. On the background of numerous, yet widely under-appreciated hints from the older literature, we summarize and discuss our recent observations from the C57BL/6 mouse model for hair research which support the concept that MC are functionally important modulators of hair follicle cycling, specifically during anagen development. This invites to exploit the murine hair cycle as a model for dissecting the physiological growth modulatory functions of MC and encourages the exploration of MC-targeting pharmaceutical strategies for the treatment of hair growth disorders.
Pharmacological modulation of IL-6 and IL-8 secretion by the H1-antagonist decarboethoxy-loratadine and dexamethasone by human mast and basophilic cell lines.
Mast cells and basophils are central effector cells of allergic reactions and are involved in inflammatory diseases. These cell types produce an array of mediators including a broad spectrum of cytokines. In order to examine whether antiallergic drugs modulate the release of these mediators, we have investigated the influence of dexamethasone and decarboethoxy-loratadine (DEL), the active metabolite of the H1-blocking agent loratadine, on the release of IL-6 and IL-8 by the human mast cell line HMC-1 and the human basophilic cell line KU812 by ELISA. Dexamethasone (10(-6)-10(-11) M) or Del (10(-5)-10(-14) M) were added to the cells either 1 h prior to or simultaneously with PMA and Ca-ionophore A23187. When preincubated with the cells, DEL dose-dependently suppressed IL-6 release by up to 40% and IL-8 release by up to 50%. Dexamethasone potently suppressed secretion of both cytokines if simultaneously added to the cells with the stimuli by up to 60% and after preincubation by up to 80%. Since both antihistamines and glucocorticoids are used for treatment of allergic diseases, the findings reported here indicate that these drugs may modulate allergic reactions via inhibition of cytokine release from mast cells and basophils.
Effect of CC chemokines on mediator release from human skin mast cells and basophils.
Chemokines are considered important mediators of various inflammatory processes. In human basophils, different CC chemokines are known to stimulate release of histamine and generation of leukotriene (LT)C4. In the present study, we have evaluated the effect of RANTES (regulated upon activation, normal T cell expressed and secreted), monocyte chemotactic protein (MCP)-1, MCP-2, MCP-3, macrophage inflammatory protein (MIP)-1 alpha and MIP-1 beta on mast cell activation. Whereas all these CC chemokines caused dose-dependent release of histamine from basophils in mixed human leukocyte suspensions, none of them was able to induce release of histamine as well as tryptase or prostaglandin (PG)D2 from human skin mast cells, nor did priming with these substances enhance IgE-mediated mediator release. In addition, all chemokines failed to promote changes in the cytosolic free calcium level in the human mast cell line HMC-1. These results add further evidence for the differences between human mast cells and basophils regarding cytokine-dependent activation.
Efficacy of cetirizine in cholinergic urticaria.
In order to examine the efficacy of cetirizine in cholinergic urticaria, we studied 24 patients in a double-blind crossover design during 3-week treatment periods, with either 10 or 20 mg/d cetirizine or placebo. The placebo period was always placed in between the two verum treatments to allow for a washout of the drug. Evaluation of the patients' daily symptom scores based on itching, erythema and whealing showed a highly significant improvement (p < 0.01). The percentage of days with mild or no symptoms was also increased significantly with the drug (p < 0.05). Except for whealing (p < 0.05), no significant differences between the two dosages of cetirizine could be determined. Since antihistamines have previously been shown to be frequently unsatisfactory in the treatment of cholinergic urticaria, the present data are encouraging regarding the control of symptoms in this condition.
Pruritogenic effects of mitogen-stimulated peripheral blood mononuclear cells in atopic eczema.
The etiology of atopic pruritus is unclear and seems mostly histamine-independent. In order to investigate non-mast cells as possible sources of pruritogenic agents, peripheral blood mononuclear cells from 12 atopic eczema patients and 12 controls were incubated in vitro for 24 h with phytohemagglutinin or concanavalin A (both at 10 micrograms/ml) or with medium alone, and each subject was tested with his own cell supernatants and lysates by prick testing and by application on tape-stripped skin. Histamine (0.1%) and substance P (500 microM) were tested in comparison, and reactions were observed for up to 24 h. Cell supernatants were also analysed for their contents of several cytokines. Lymphocyte cell extracts or supernatants failed to cause symptoms in controls but induced whealing in 6 and itching in 3 patients on prick testing within 5 min, lasting for 30 min in 2 patients and persisting for 6 h in 1 patient. Histamine caused itching in all controls and in 7 patients within 5 min on prick testing, with decreasing reactivity at later times. Substance P yielded results with lower values. With all three types of test reagents, fewer subjects reacted on tape stripped skin. High levels of interleukins 2 and 6, low levels of interferon and no detectable levels of interleukin 4 and tumour necrosis factor were measured in stimulated cell supernatants and extracts, with even lower levels in subjects exhibiting skin reactivity. These findings thus provide evidence that as yet unidentified mononuclear cell products may be involved in whealing and itching associated with atopic eczema.
Pseudoallergen-free diet in the treatment of chronic urticaria. A prospective study.
In chronic urticaria, the possible pathogenetic role of pseudoallergic reactions to food has been repeatedly discussed, but stringent prospective studies regarding their clinical significance are not available. All patients with chronic urticaria and/or angioedema hospitalized at the department of dermatology during a period of 2 years were therefore included in a prospective study. Patients (n = 64) were screened for common causes of urticaria and then evaluated for possible benefits of a stringently controlled pseudoallergen-free diet. Double-blind, placebo-controlled oral provocation tests with food additives were performed on those patients benefitting from diet. In 73% of patients, symptoms ceased or were greatly reduced within 2 weeks on diet, although only 19% of them responded to individual pseudoallergens on provocation tests. Of the remaining patients, 11% responded to treatment of an associated inflammatory disease, and in 16%, no cause of the urticaria was ascertained. Follow-up at 6 months after hospitalization showed complete remission on diet in 46% and lasting improvement in all but one of the remaining patients on diet. An additive-free, stringently controlled diet thus provides a simple means of diagnosing and treating the majority of patients with chronic urticaria.
Urticarial vasculitis syndrome effectively treated with dapsone and pentoxifylline.
Urticarial vasculitis is difficult to treat. We report here on a 40-year-old woman with a 16-year history of idiopathic hypocomplementemic urticarial vasculitis syndrome. Her disease had been resistant to treatment with H1- and H2-blockers, indomethacin, dapsone and interferon alpha but responded to > 25 mg/day prednisolone. Monotherapy with pentoxifylline was also of only minor benefit. Using a combination of dapsone (100 mg/day) and pentoxifylline (1,200 mg/day), we observed a gradual improvement resulting in a complete remission within 8 weeks. Complete control of symptoms could be maintained for 18 months without any serious side-effects. This type of treatment may be of benefit in other therapy-resistant cases of hypocomplementemic urticarial vasculitis syndrome, particularly in view of its excellent tolerance.
Possible aggravation of hepatitis A by acitretin.
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DIG-labeled RNA in situ hybridization without coverslipping.
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[Necrobiology of the skin: apoptosis].
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[Urticaria pigmentosa].
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