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Biomedical subjects

J Krutmann

Publications and source records attributed to J Krutmann.

At least 109 records · Page 6Linked to original sources
PubMed1994

Post-transcriptional regulation of interleukin-6 gene expression in human keratinocytes by ultraviolet B radiation.

Exposure to increasing doses (290-315 nm) of ultraviolet (UV) B radiation is thought to profoundly affect human health. Studies on the biologic and molecular effects of UVB radiation on human skin are therefore of particular interest. There is experimental and clinical evidence to assume that UVB radiation-induced local and systemic inflammatory reactions might be mediated at least in part by UVB-induced keratinocyte-derived interleukin (IL)-6. Previously, a UVB-induced increase of steady-state levels of IL-6 mRNA was found to be a prerequisite for keratinocyte IL-6 production after UVB irradiation. The present study was aimed at addressing the question of whether in vitro UVB irradiation would increase IL-6 mRNA expression in long-term cultured, normal human keratinocytes via transcriptional or post-transcriptional mechanisms. UVB exposure (0-100 J/m2) of keratinocytes increased low baseline expression levels of IL-6 mRNA in a time- and dose-dependent manner. Using nuclear run-on assays, transcription rates of the IL-6 gene in nuclei isolated from UVB-irradiated cells were found to be essentially identical to those seen in unirradiated cells, indicating that UVB light did not lead to increased transcription of the IL-6 gene. To determine a possible post-transcriptional mechanism in UVB-induced IL-6 mRNA expression, the effects of UVB irradiation on IL-6 mRNA stability were examined. To this end irradiated and unirradiated keratinocytes were treated with actinomycin D and subjected to Northern blot analysis to calculate IL-6 mRNA half-life. As compared with unirradiated cells, IL-6 mRNA stability was increased significantly (three- to four-fold) in UVB-irradiated cells, suggesting that UVB radiation upregulates IL-6 mRNA levels in human keratinocytes by increasing the stability of IL-6 transcripts. This is the first report indicating that UVB radiation at a physiologically relevant dose may affect gene expression in human cells at a post-transcriptional level.

Blotting, Northern↗
PubMed1993

Analysis of the mechanism of ultraviolet (UV) B radiation-induced prostaglandin E2 synthesis by human epidermoid carcinoma cells.

Stimulation of cultured human keratinocytes with interleukin (IL)-1 alpha is known to elicit prostaglandin (PG) E2 release. Ultraviolet (UV) B radiation induces keratinocyte PGE2 and cytokine production. The present study deals with the autocrine roles of UVB-induced, keratinocyte-derived cytokines IL-1 and tumor-necrosis-factor (TNF) alpha and their corresponding receptor molecules for UVB-induced PGE2 release. In vitro exposure of transformed human keratinocytes (KB cells) induced PGE2 production five- to eightfold. This increase was inhibited by 70%, if irradiated cells were cultured in presence of monoclonal antibody (MoAb) M4, which blocks IL-1 effects by binding to the type 1 IL-1 receptor (IL-1R). In contrast, MoAb M22, which blocks the type 2 IL-1R, had no significant effects. Addition of recombinant human TNF alpha to unirradiated KB cells resulted in five- to eightfold increased PGE2 synthesis, and this increase could be mimicked by stimulation of KB cells with MoAb htr-9, which exerts TNF alpha-like bioactivity by binding to the 55-kD TNF receptor (TNFR). UVB-induced PGE2 synthesis was blocked by 50% in the presence of neutralizing anti-TNF alpha-Ab, and was completely inhibited by addition of both anti-TNF alpha-Ab and MoAb M4. To elucidate a possible regulatory intracellular step in PGE2 synthesis, specific cyclooxygenase activity in KB cells was determined. Following UVB treatment, cyclooxygenase activity increased twofold, but remained unaltered, if irradiated KB cells were cultured in the presence of anti-TNF alpha-Ab plus MoAb M4. These studies indicate that keratinocyte-derived TNF alpha and IL-1 together mediate UVB-induced PGE2 release via specific cell surface receptors, and that one intracellular mechanism is an increased prostanoid-synthesizing capacity of irradiated cells.

Antibodies, Monoclonal↗
PubMed1993

Induction of intercellular adhesion molecule 1 (ICAM-1) expression in normal human eosinophils by inflammatory cytokines.

Intercellular adhesion molecule-1 (ICAM-1) functions as a ligand for lymphocyte function-associated antigen-1 (LFA-1), and thereby plays a crucial role in mediating cell-cell interactions in inflammatory reactions. Human eosinophils represent important effector cells in allergic skin diseases. To gain more insight into the capacity of eosinophils to physically interact with LFA-1-positive inflammatory leukocytes, in the present study ICAM-1 expression in eosinophils was investigated. Using fluorescence-activated cell sorter analysis, it could be shown that highly purified (> or = 95%) eosinophils from peripheral blood of non-atopic individuals do not constitutively express ICAM-1 molecules. However, stimulation of eosinophils with interferon gamma (IFN gamma), tumor-necrosis factor alpha (TNF alpha), or interleukin 3 (IL-3) markedly upregulated ICAM-1 surface expression in a time- and dose-dependent manner. Cytokine-induced ICAM-1 expression in human eosinophils was corroborated by Northern blot analysis. Accordingly, unstimulated eosinophils did not express significant amounts of ICAM-1 mRNA, but ICAM-1 mRNA expression could be markedly induced in these cells upon stimulation with IFN gamma plus TNF alpha. The combination of TNF alpha with either IFN gamma, IL-3, IL-5, or granulocyte/macrophage colony-stimulating factor (GM-CSF) increased ICAM-1 expression in a synergistic fashion, whereas IL-5 or GM-CSF by itself did not induce ICAM-1 expression. Cytokine-induced ICAM-1 expression was specific, because IL-1 alpha, IL-1 beta, IL-2, IL-4, IL-6, IL-7, IL-8, C5a, and platelet-activating factor did not significantly affect eosinophil ICAM-1 surface expression. In summary, these studies indicate that eosinophils may be activated to express the adhesion molecule ICAM-1 upon stimulation with selected inflammatory cytokines, which may allow adhesion-mediated cross-talk between eosinophils and LFA-1-positive cells. In addition, these data demonstrate for the first time a role for IL-3, IL-5, and GM-CSF in regulation of ICAM-1 expression in human cells.

Antigens, CD↗
PubMed1993

Human cell adhesion molecule uvomorulin is differentially expressed in various skin tumors.

The cell adhesion molecule uvomorulin is important in cell recognition processes, both during tissue formation in embryonic development and in the maintenance of adult epithelia. In addition, uvomorulin appears to play a crucial role in carcinogenesis. Therefore, in the present study, the expression of uvomorulin in normal human skin and several benign and malignant proliferative skin lesions was evaluated by immunofluorescence microscopy using affinity purified antibodies. In normal human epidermis, basal and suprabasal keratinocytes showed a strong and homogeneous staining of the cell membrane. In contrast, uvomorulin expression was decreased in squamous cell, as well as in solid basal cell, carcinoma. Interestingly, solid basal cell carcinoma showed a dimorphic staining pattern with a reduced fluorescence of the inner cell layers and normal staining of the peripheral basal cells. In contrast, no such dimorphic staining pattern could be observed in squamous cell carcinoma, in which uvomorulin expression was homogeneously reduced. Decreased expression of uvomorulin was not specific for malignant skin lesions, since it could also be observed in condylomata acuminata. These studies demonstrate that human uvomorulin is differentially expressed in proliferative skin disorders, which may account at least in part for the differences observed in the clinical course between squamous cell and basal cell carcinoma.

Cadherins↗
PubMed1992

High-dose UVA1 therapy in the treatment of patients with atopic dermatitis.

BACKGROUND: Besides glucocorticosteroids, there is currently no known effective therapy for patients with acute atopic dermatitis. OBJECTIVE: The therapeutic effectiveness of high-dose UVA1 irradiation in the management of patients with acute exacerbation of atopic dermatitis was examined. METHODS: Patients in the high-dose UVA1 group (n = 15) were irradiated with 130 joules/cm2 UVA1; the control group (n = 10) was treated with UVA-UVB therapy in a minimal erythema dose-dependent manner (total number of treatments 15). RESULTS: High-dose UVA1 irradiation was found to induce a significant clinical improvement of atopic dermatitis (p less than 0.001). In comparison with UVA-UVB therapy, significant differences in favor of high-dose UVA1 were observed (p less than 0.01). High-dose UVA1, but not UVA-UVB treatment, significantly reduced the elevated serum level of eosinophil cationic protein in patients with atopic dermatitis (p less than 0.003). CONCLUSION: These studies indicate that high-dose UVA1 irradiation may represent a novel phototherapeutic modality for the treatment of patients with an acute exacerbation of atopic dermatitis.

Adult↗
PubMed1992

Ultraviolet radiation effects on human keratinocyte ICAM-1 expression: UV-induced inhibition of cytokine-induced ICAM-1 mRNA expression is transient, differentially restored for IFN gamma versus TNF alpha, and followed by ICAM-1 induction via a TNF alpha-like pathway.

Human keratinocytes (KC) during the course of inflammatory dermatoses strongly express the surface molecule ICAM-1, which plays an important role in the generation of the epidermal inflammatory infiltrate by mediating leukocyte-keratinocyte interactions. Accordingly, KC ICAM-1 expression is known to be induced in vivo and in vitro by cytokines either via the TNF alpha/TNF beta or via the IFN gamma-mediated pathway. In contrast, ultraviolet (UV) radiation previously has been found to potently inhibit cytokine-induced KC ICAM-1 surface expression by a sublethal mechanism. In order to further define this novel immunosuppressive effect of UV light, the effects of in vitro UV radiation on ICAM-1 mRNA expression in transformed human KC (KB cells) were examined. Accordingly, UV light (0-100 J/m2) inhibited IFN gamma- as well as TNF alpha-induced ICAM-1 mRNA expression, if KC were cytokine stimulated immediately after irradiation. After a 12-h incubation period, however, IFN gamma responsiveness was found to be restored in irradiated cells, whereas restoration of responsiveness to TNF alpha required at least a 24-h recovery phase. Moreover, UV light alone did not alter ICAM-1 mRNA levels after 4, 12, or 24 h. After 48 h, however, a significant increase in ICAM-1 mRNA and surface expression in UV-irradiated KC could be observed. In addition, this increase could be superinduced by stimulation of irradiated KC with IFN gamma, but not with TNF alpha. UV-induced upregulation of ICAM-1 expression could be mimicked by stimulating unirradiated cells with supernatants derived from UV-irradiated cells. Addition of biologically active anti-TNF alpha antibodies to UV-irradiated cells or to supernatants derived from UV-irradiated KC, however, did not even partially abolish this ICAM-1-inducing activity. UV light thus seems to affect KC ICAM-1 mRNA expression in a biphasic manner: an early period of inhibition of cytokine-induced ICAM-1 expression is transient and followed by restoration of responsiveness to ICAM-1-inducing cytokines. Moreover, UV itself is able to induce ICAM-1 mRNA expression at this later time point via a TNF alpha-like pathway. These studies identify UV irradiation as a potent modulator of cytokine regulated ICAM-1 gene transcription with the capacity to induce both inhibitory as well as enhancing effects.

Blotting, Northern↗
PubMed1992

Ultraviolet B-irradiated antigen-presenting cells display altered accessory signaling for T-cell activation: relevance to immune responses initiated in skin.

A principal mechanism by which ultraviolet (UV) B radiation exerts its selective and antigen-specific suppressive influence on immune responses is through its effects on the capacity of antigen-presenting cells (APC) in skin, primarily Langerhans cells (LC), to differentially activate T-cell subsets. Recent evidence has indicated that LC, following UVB radiation, lose the capacity to stimulate proliferation of CD4+ Th1, but not of Th2, clones. Additional work has shown this acquired unresponsiveness of Th1 cells to represent a long-lasting form of clonal anergy that results from a block in their ability to produce IL-2. Although not completely delineated, these defects appear to be the result of preserved delivery of the primary signal transduced by interaction of the MHC/antigen complex on APC with the T-cell receptor complex, in the absence of a viable second signal normally delivered by interaction of a co-stimulatory factor from APC with its appropriate ligand on the T cells. These findings support the notion that the outcome of certain immune responses depends greatly upon conditions that are brought to bear on APC and T cells during the time of antigen presentation.

Animals↗
PubMed1992

Serum eosinophil cationic protein (ECP) is a sensitive measure for disease activity in atopic dermatitis.

Atopic dermatitis (AD) is characterized by alterations in cellular and humoral immunity including elevated serum levels of IgE, IL-2 receptor (IL-2R) and eosinophil cationic protein (ECP). In order to evaluate the relevance of these serum parameters as indicators of disease activity, the concentrations of IgE, IL-2R and ECP were measured in serum samples of patients with an acute exacerbation of AD (n = 19) on admission to hospital and every 6 days up to discharge, and compared with those from normal non-atopic controls (n = 15). The severity of the disease in the AD patients was examined using an established clinical scoring system. On admission, AD patients showed significantly elevated serum levels of IgE, IL-2R and ECP compared with normal controls (P less than or equal to 0.0001). Clinical improvement was associated with a decrease of both the clinical score (P less than or equal to 0.001) and serum ECP levels (P less than or equal to 0.005). No significant changes in serum IgE and serum IL-2R were observed. In addition, there was a significant correlation between serum ECP and the clinical score (R = 0.67, P less than or equal to 0.001). These data indicate that serum ECP may be a helpful tool for monitoring disease activity in AD.

Acute Disease↗
PubMed1992

Human epidermal keratinocytes are a source of soluble ICAM-1 molecules.

A soluble form of the usually membrane-bound adhesion molecule ICAM-1 was detected in supernatants derived from human epidermal keratinocytes. Specifically, supernatants harvested from long-term cultured normal human keratinocytes, or from the spontaneously immortalized keratinocyte cell line HaCaT, did not contain significant amounts of sICAM-1, but shedding of sICAM-1 was found to be markedly induced upon stimulation of keratinocytes with rh IFN gamma. In contrast, cells from the two epidermoid carcinoma cell lines, KB and A431, constitutively shed significant amounts of sICAM-1 even without cytokine stimulation, and sICAM-1 contents in supernatants harvested from these cells were further increased upon stimulation of cells with rh IFN gamma. These studies indicate, that in addition to peripheral blood mononuclear cells and human melanoma cells, human epidermal keratinocytes constitute an important cellular source of sICAM-1. By binding to leukocyte LFA-1 molecules, keratinocyte-derived sICAM-1 may influence inflammatory responses in the skin. In addition, constitutive shedding of sICAM-1 by transformed human keratinocytes may represent a possible mechanism by which neoplastic keratinocytes escape from cytotoxicity.

Cell Adhesion↗
PubMed1992

High-dose-UVA1 phototherapy: a novel and highly effective approach for the treatment of acute exacerbation of atopic dermatitis.

High-Dose-UVA1 irradiation has recently been found to be a new, prompt-acting and highly effective phototherapeutic approach to the treatment of patients with acute exacerbation of atopic dermatitis. This therapeutic efficacy was demonstrated by a marked improvement of clinical symptoms as well as of laboratory parameters, which were found to reflect disease activity in atopic dermatitis. Investigation of the photoimmunological mechanisms responsible for the therapeutic effectiveness of this modality indicates that eosinophils and epidermal Langerhans cells may be targets for High-Dose-UVA1.

Acute Disease↗
PubMed1991

Eosinophil cationic protein in sera of patients with atopic dermatitis.

Patients with atopic dermatitis frequently show elevated blood eosinophil counts, and eosinophil-derived major basic protein has been demonstrated in the eczematous skin from patients with atopic dermatitis. To evaluate further the role of eosinophils in the pathogenesis of atopic dermatitis, the concentration of eosinophil cationic protein was measured in serum samples of 42 patients with moderate to severe disease. The results were compared with those obtained in 32 patients with psoriasis with (n = 9) or without (n = 23) a history of inhalant allergy, 12 patients with a history of pseudoallergic reactions to acetylsalicylic acid, 14 patients with a history of inhalant allergy, and 31 nonatopic healthy control subjects. Eosinophil cationic protein levels were significantly increased in the serum of patients with atopic dermatitis (p less than or equal to 0.005) and patients with a history of pseudoallergic reactions to acetylsalicylic acid (p less than or equal to 0.01). There was no significant difference between eosinophil cationic protein levels in patients with psoriasis or a history of inhalant allergy and in control subjects. Moreover, eosinophil cationic protein levels did not differ significantly in psoriasis patients with or without inhalant allergy. These studies support the concept of an active participation of eosinophils in atopic dermatitis and point to a possible role for eosinophils in pseudoallergy.

Adolescent↗
PubMed1991

Regulation of epidermal cell interleukin-6 production by UV light and corticosteroids.

Epidermal cells (EC) are well known as a source of cytokines, including interleukin (IL)-6. In the present study, we investigated whether ultraviolet (UV) light and corticosteroids (CS) affect IL-6 production by normal (HNK) or malignant (KB) human keratinocytes. Supernatants derived from UVB (100 J/m2)- but not from UVA (100-1500 kJ/m2)-exposed EC (HNK and KB) contained significantly increased levels of IL-6 activity. This was also confirmed by Western blot analysis, resulting in specific bands at 23 kD and 27 kD. Northern blot analysis revealed an enhanced IL-6 mRNA expression after UVB exposure. Addition of hydrocortisone, prednisolone, or dexamethasone immediately after UVB irradiation significantly blocked UVB or IL-1-induced IL-6 mRNA expression and production by EC. The suppressive effect was observed at doses in the physiologic (10(-7)-10(-9) M) as well as pharmacologic (10(-5)-10(-7) M) range. In contrast, the nonactive steroid prednisone did not affect EC IL-6 mRNA expression. These findings indicate that increased IL-6 production by EC after UVB irradiation may mediate local and systemic inflammatory reactions following extensive sun exposure. Thus, the therapeutic effect of corticosteroids observed in various inflammatory diseases may be partly due to their downregulating capacity of IL-6 production.

Adrenal Cortex Hormones↗
PubMed1991

55-kd tumor necrosis factor receptor is expressed by human keratinocytes and plays a pivotal role in regulation of human keratinocyte ICAM-1 expression.

Tumor necrosis factor alpha (TNF alpha) is a potent modulator of human keratinocyte intercellular adhesion molecule-1 (ICAM-1) expression. TNF alpha is known to exert its biologic effects by binding to specific cell-surface receptors. Two distinct TNF binding molecules, the 55-kd and the 75-kd TNF receptor (TNFR) recently have been found to be expressed by human cells. These two receptor types are independently regulated and differ markedly in their intracellular regions, indicating functional dichotomy. In order to gain further insight into the mechanisms underlying ICAM-1 regulation in human keratinocytes, in the present study, the receptor molecules mediating TNF alpha induced ICAM-1 upregulation in human keratinocytes was defined. Human keratinocyte TNFR expression was assessed using monoclonal antibodies that specifically recognize the 55-kd or the 75-kd TNFR. Using FACS analysis, normal (HNK) as well as transformed (KB) human keratinocytes were found to react with anti-55-kd TNFR, but not anti-75-kd TNFR antibodies. These immunofluorescence data were confirmed by Northern blot analysis revealing clearly detectable amounts of mRNA specific for the 55-kd TNFR in KB cells. Incubation of human keratinocytes with anti-55-kd TNFR antibodies at 37 degrees C for 24 h increased ICAM-1 expression in a TNF alpha-like fashion. Moreover, the well known synergistic effect of IFN gamma plus TNF alpha on keratinocyte ICAM-1 induction could be mimicked by stimulation of cells with IFN gamma plus anti-55-kd TNFR antibodies. Synergistic ICAM-1 induction was not associated with increased expression of the 55-kd TNFR in IFN gamma-stimulated human keratinocytes. These studies indicate that human keratinocytes express the 55-kd TNF receptor and that this surface molecule may play an important role in regulation of human keratinocyte ICAM-1 expression.

Binding Sites, Antibody↗
PubMed1991

Production of interleukin-2 by mononuclear cells in vitro in patients with atopic dermatitis and psoriasis. Comparison with serum interleukin-2 receptor levels.

Atopic dermatitis is associated with profound immunological alterations, in particular decreased lymphoproliferative responses upon stimulation with T-cell mitogens. T-cell blastogenesis involves the production of the soluble cytokine interleukin-2 (IL-2), which in turn upregulates the expression of its own receptor. To investigate the potential role of this cytokine for the pathomechanisms present in atopic dermatitis, 24-h supernatants of PHA-stimulated peripheral blood mononuclear cells from patients with atopic dermatitis (n = 30) of a moderate to severe disease activity were tested for IL-2 activity. In addition, serum concentrations of soluble interleukin-2 receptor (IL-2R) were measured. Non-atopic healthy controls (n = 19) and patients with psoriasis (n = 20), an inflammatory skin disorder with distinct pathogenesis, served as controls. In comparison with psoriasis patients and normal controls, PHA-stimulated mononuclear cells of atopic dermatitis patients released significantly less IL-2 into supernatants. Moreover, there was an inverse correlation between IL-2 concentrations and body surface involvement or serum IgE levels. In contrast, serum IL-2R levels were significantly elevated in both atopic dermatitis and psoriasis, as compared with healthy controls. Furthermore, IL-2R levels in atopic dermatitis patients showed a significant correlation with IgE levels and body surface involvement. The data indicate that T cell activation may occur in both skin diseases. Atopic dermatitis, however, is further characterized by the decreased capacity of mononuclear cells to release IL-2 upon stimulation in vitro.

Adolescent↗