Search PubMed⌕ Search

Biomedical subjects

J Krutmann

Publications and source records attributed to J Krutmann.

At least 91 records · Page 5Linked to original sources
PubMed1996

Activation of transcription factor AP-2 mediates UVA radiation- and singlet oxygen-induced expression of the human intercellular adhesion molecule 1 gene.

UVA radiation is the major component of the UV solar spectrum that reaches the earth, and the therapeutic application of UVA radiation is increasing in medicine. Analysis of the cellular effects of UVA radiation has revealed that exposure of human cells to UVA radiation at physiological doses leads to increased gene expression and that this UVA response is primarily mediated through the generation of singlet oxygen. In this study, the mechanisms by which UVA radiation induces transcriptional activation of the human intercellular adhesion molecule 1 (ICAM-1) were examined. UVA radiation was capable of inducing activation of the human ICAM-1 promoter and increasing ICAM-1 mRNA and protein expression. These UVA radiation effects were inhibited by singlet oxygen quenchers, augmented by enhancement of singlet oxygen life-time, and mimicked in unirradiated cells by a singlet oxygen-generating system. UVA radiation as well as singlet oxygen-induced ICAM-1 promoter activation required activation of the transcription factor AP-2. Accordingly, both stimuli activated AP-2, and deletion of the putative AP-2-binding site abrogated ICAM-1 promoter activation in this system. This study identified the AP-2 site as the UVA radiation- and singlet oxygen-responsive element of the human ICAM-1 gene. The capacity of UVA radiation and/or singlet oxygen to induce human gene expression through activation of AP-2 indicates a previously unrecognized role of this transcription factor in the mammalian stress response.

Cell Line↗
PubMed1996

Coagulation factor V gene mutation associated with activated protein C resistance leading to recurrent thrombosis, leg ulcers, and lymphedema: successful treatment with intermittent compression.

Activated protein C resistance is the most frequent cause of venous thrombosis. We describe a patient with extensive ulcerations and severe lymphedema of the legs after recurrent thrombosis. Laboratory tests revealed a pathologic activated protein C resistance and a reduced functional protein S. The underlying genetic defect was identified as a heterozygous coagulation factor V mutation. A combined therapeutic approach of intermittent compression, repeated debridements and systemic antibiotics resulted in marked improvement of both lymphedema and leg ulcers.

Anti-Bacterial Agents↗
PubMed1996

Allergen specificity of skin-infiltrating T cells is not restricted to a type-2 cytokine pattern in chronic skin lesions of atopic dermatitis.

The majority of allergen-specific T cells derived from inhalant allergen patch test lesions in patients with atopic dermatitis were previously found to produce a restricted type-2 cytokine pattern. Recent studies, however, have revealed that in chronic eczematous skin lesions of patients with atopic dermatitis, expression of the type-1 cytokine interferon-gamma predominates. To evaluate cytokine production by allergen-specific T cells in chronic atopic dermatitis, we established house dust mite (Dermatophagoides pteronyssinus)-specific T-cell clones from the dermis of chronic skin lesions of sensitized adult patients with atopic dermatitis. Frequencies of skin-derived T cells proliferating in the presence of Dermatophagoides pteronyssinus were between one in 138 and one in 4255, indicating that only a minority of skin-infiltrating T cells are allergen specific. When these cells were analyzed for their capacity to produce interferon-gamma, the majority (71%) of these cells were found to express interferon-gamma mRNA and to secrete interferon-gamma protein, either alone or in combination with interleukin-4. Phenotypic analysis revealed that 15% of skin-infiltrating allergen-specific T cells were CD8+. No selection of Vbeta elements was detected in Dermatophagoides pteronyssinus-specific T-cell clones. These studies demonstrate that allergen specificity of skin-infiltrating T cells is not restricted to a type-2 cytokine pattern in lesional atopic dermatitis. The notion that the majority of allergen-specific, skin-infiltrating T cells are capable of producing interferon-gamma further supports the concept that interferon-gamma expression has major pathogenetic relevance for the chronic phase of atopic dermatitis.

Adult↗
PubMed1996

High-dose ultraviolet A1 (UVA1), but not UVA/UVB therapy, decreases IgE-binding cells in lesional skin of patients with atopic eczema.

In order to further elucidate the mechanisms by which high-dose ultraviolet A1 (UVA1) therapy leads to improvement in patients with atopic eczema, we assessed skin sections from patients before and after high-dose UVA1 therapy (n = 5) or conventional UVA/UVB therapy (n = 4) for changes in Langerhans cells and mast cells expressing the high-affinity IgE receptor Fc epsilon RI and in surface-bound IgE by histochemical and immunohistochemical techniques. The two treatment groups exhibited different patterns of changes in the number of Fc epsilon RI+, CD1a+, and mast cells within the dermis: The density of both Langerhans cells and mast cells was decreased after high-dose UVA1 therapy, but not after UVA/UVB therapy. High-dose UVA1 and UVA/UVB therapy significantly increased the number of CD1a+ cells within the epidermis, but only high-dose UVA1 reduced the relative number of IgE+ intraepidermal Langerhans cells typically found in atopic eczema. Reduction of numbers of dermal Langerhans cells and mast cells, as well as relative numbers of intraepidermal IgE+ Langerhans cells, was closely linked to significant clinical improvement by high-dose UVA1, but not UVA/UVB therapy. These studies support the notion that IgE-binding cutaneous cells are involved in the pathogenesis of atopic eczema. We propose that UVA1 radiation exerts its effects in atopic eczema, at least in part, by inhibiting Langerhans cell migration out of the epidermis and, in particular, by reducing the number of IgE-bearing Langerhans cells and mast cells in the dermis.

Cell Count↗
PubMed1996

Analysis of the production of soluble ICAM-1 molecules by human cells.

The adhesion molecule intercellular adhesion molecule-1 (ICAM-1), in addition to its membrane-associated form (mICAM-1), also exists as a soluble form (sICAM-1). sICAM-1 is capable of binding to lymphocyte function associated antigen-1 (LFA-1) molecules, and production of sICAM-1 is therefore thought to have immunomodulatory consequences. The present study, which employed normal human keratinocytes as a model for sICAM-1-producing cells, was conducted to determine the mechanism responsible for the production of sICAM-1 and to develop a strategy for specific inhibition of sICAM-1 production. Stimulation of keratinocytes with recombinant human gamma-interferon (rhIFN-gamma) induced both expression of mICAM-1 and production of sICAM-1. Western blot analysis revealed that keratinocyte-derived sICAM-1, compared to mICAM-1, had a smaller molecular size, approximately a 7-kD difference. Neither by Northern blot analysis nor by reverse-transcriptase polymerase chain reaction (RT-PCR) was any evidence for alternatively spliced ICAM-1 mRNA obtained. Addition of the protease inhibitors iodoacetamide and E-64, however, inhibited the production of sICAM-1 in a dose-dependent manner. The involvement of proteolytic cleavage in the production of sICAM-1 was corroborated in minimal peptide protection assays, in which minimal peptides covering the potential cleavage site of ICAM-1 were added to sICAM-1-producing keratinocytes. One of these peptides, ICAM cleavage inhibitory peptide (ICAM-CIP), inhibited the production of sICAM-1 without affecting mICAM-1 expression. These studies demonstrate that sICAM-1 production in human keratinocytes is due to proteolytic cleavage, and that the oligopeptide ICAM-CIP may specifically inhibit this mechanism. The capacity of ICAM-CIP to selectively prevent production of sICAM-1 may be useful for the development of novel therapeutic approaches relevant for the management of inflammation and cancer.

Amino Acid Sequence↗
PubMed1996

Interleukin-1 receptors type I and type II are differentially regulated in human keratinocytes by ultraviolet B radiation.

Since regulation of keratinocyte IL-1 receptor expression is likely to have a major impact on the biologic effects of IL-1 on epidermal cells, we examined expression, regulation, and function of IL-1R in cultured human keratinocytes. By reverse transcriptase polymerase chain reaction, human keratinocytes were shown to express IL-1 receptor type I (IL-1RI) and IL-1 receptor type II (IL-1RII). Human keratinocyte IL-1RI mRNA expression was dependent on the differentiation state of the cell and was regulated by ultraviolet B (UVB) radiation, which initially decreased but later increased IL-1RI expression. This UVB-induced biphasic modulation of IL-1RI expression was mediated by an autocrine mechanism involving endogenously produced IL-1alpha and IL-1RI. Increased expression of IL-1RI in UVB-irradiated or IL-1alpha-stimulated keratinocytes was functionally important, because it endowed these cells with the capacity to upregulate expression of the intercellular adhesion molecule (ICAM)-1 upon IL-1alpha stimulation. Keratinocyte IL-1RII expression was regulated by UVB irradiation in an inverse manner. Significant and rapid upregulation of IL-1RII was observed within 1 h after UVB irradiation and gradually decreased to background levels within 24 h. Inverse regulation of IL-1RII versus IL-1RI was associated with opposite functions, because blocking of IL-1RII enhanced IL-1alpha effects on induction of ICAM-1 expression. These studies demonstrate that IL-1 responsiveness of UVB-irradiated keratinocytes critically depends on regulation of IL-1RI expression and that IL-1RII serves as a "decoy" receptor for IL-1, limiting rather than promoting IL-1-mediated effects.

Cells, Cultured↗
PubMed1995

Expression of intercellular adhesion molecule-1 is regulated by the actin network in epidermoid carcinoma cells.

Expression of the cell surface protein intercellular adhesion molecule-1 (ICAM-1) is a prerequisite for the interaction of a large variety of cells with leukocytes. Constitutive expression of ICAM-1 in human epidermoid carcinoma cells is low, but is inducible through inflammatory cytokines including interferon gamma (INF gamma). Disruption of the actin cytoskeleton with dehydrocytochalasin B (CB) increased constitutive and potentiated INF gamma-induced ICAM-1 cell surface expression, but did not alter formation of soluble ICAM-1. Actinomycin D inhibited CB-induced ICAM-1 surface expression and CB increased the steady-state levels of ICAM-1 transcripts. However, CB did not alter the glyceralaldehyde-3-phosphate dehydrogenase mRNA levels and the ICAM-1 mRNA half-life. These studies indicate that in human epidermoid carcinoma cells the actin cytoskeleton regulates ICAM-1 transcription and cell surface expression.

Actins↗
PubMed1995

Involvement of cytokines, DNA damage, and reactive oxygen intermediates in ultraviolet radiation-induced modulation of intercellular adhesion molecule-1 expression.

By virtue of its capacity to serve as a counter-receptor for lymphocyte function-associated antigen-1, intercellular adhesion molecule-1 (ICAM-1) plays a pivotal role in generation and maintenance of immunologic/inflammatory skin diseases by mediating leukocyte/keratinocyte adhesion. Ultraviolet radiation (UVR) may exert both antiinflammatory effects (e.g., UV phototherapy) and proinflammatory effects (e.g., triggering of photosensitive skin diseases) on human skin. Recent evidence indicates that UVR-induced changes of keratinocyte ICAM-1 expression constitute the molecular basis for these ambivalent properties of UVR, as UVR is able to exert two separate and even opposite effects on ICAM-1 expression. As an antiinflammatory effect, UVR may inhibit cytokine-induced up-regulation of keratinocyte ICAM-1 expression, whereas induction of ICAM-1 expression by UVR represents a proinflammatory activity. This latter effect is mediated by an autocrine mechanism involving interleukin (IL)-1 alpha. In this autocrine system, UVR exposure of human keratinocytes leads to the release of IL-1 alpha, which in turn up-regulates the expression of IL-1 receptor type 1 molecules on the keratinocyte surface, thereby increasing the sensitivity of these cells toward IL-1 alpha. As a consequence, irradiated keratinocytes are capable of responding to endogenously produced IL-1 alpha by increasing ICAM-1 expression. Modulation of keratinocyte ICAM-1 expression after UVR exposure may be observed after both short-wave UVR (UVB; 280-320 nm) and long-wave UVR (UVA1; 340-400 nm). The photobiologic mechanisms underlying UVB versus UVA1 radiation-induced ICAM-1 modulation have been found to differ. Although not completely delineated, UVB radiation-induced modulation of ICAM-1 expression appears to be mediated via the induction of DNA damage, whereas UVA1 radiation effects involve the generation of reactive oxygen intermediates.

Animals↗
PubMed1995

Analysis of the cytokine pattern expressed in situ in inhalant allergen patch test reactions of atopic dermatitis patients.

In the present study, we examined the cytokine pattern expressed in situ during the development of eczematous reactions that had been provoked in atopic dermatitis patients by patch testing with house dust mite allergen. In 24-h house dust mite allergen patch test reactions, expression of interleukin (IL)-4 mRNA and IL-2 mRNA increased, but interferon (IFN)-gamma mRNA did not, as compared with control skin. In 48-h inhalant allergen patch test reactions, however, IFN-gamma mRNA and IL-2 mRNA expression were increased above levels observed in control skin, whereas IL-4 mRNA expression was decreased below background levels. These data demonstrate that a switch from a Th2-like to a Th1-like cytokine response occurs in inhalant allergen patch tests of atopic dermatitis patients. This biphasic pattern was specific to inhalant allergen patch test reactions, as it was not observed in irritant reactions in the same patient. IFN-gamma production by T cells may be induced by the cytokine IL-12. In the present study, up-regulation of IFN-gamma mRNA expression in inhalant allergen patch test reactions was preceded by an increased expression of the p35 subunit of IL-12 mRNA. These observations suggest that increased IL-12 expression may contribute to the observed switch of the in situ cytokine secretion pattern. Further studies are necessary to determine whether a similar biphasic pattern of cytokine expression is also operative in the initiation phase of atopic eczema.

Allergens↗
PubMed1995

Interleukin-10 production by cultured human keratinocytes: regulation by ultraviolet B and ultraviolet A1 radiation.

Keratinocytes are the primary cellular target for ultraviolet radiation in human skin, and ultraviolet radiation-induced therapeutical effects may thus be mediated by keratinocyte-derived, antiinflammatory mediators. Interleukin-10 is capable of exerting antiinflammatory effects by virtue of its capacity to suppress the production of interferon-gamma. The present study therefore assessed the ability of cultured human keratinocytes to produce interleukin-10 following ultraviolet irradiation. Exposure of long-term cultured normal human keratinocytes to ultraviolet B (280-320 nm) or to ultraviolet A1 (340-400 nm) radiation caused a time- and dose-dependent induction of interleukin-10 mRNA expression and interleukin-10 protein secretion, with ultraviolet A1 radiation being the strongest stimulus. Ultraviolet radiation-induced interleukin-10 production by normal human keratinocytes was enhanced by a factor of two, when cells were cultured in high- rather than low-calcium medium. Neither addition of the ultraviolet radiation-inducible cytokines tumor necrosis factor-alpha or interleukin-1 alpha to unirradiated keratinocytes nor presence of their respective neutralizing antibodies in cultures of irradiated keratinocytes induced or inhibited interleukin-10 synthesis. Modulation of eicosanoid production by addition of prostaglandin E2 to keratinocyte cultures or disturbance of cyclooxygenase activity by indomethacin did not affect interleukin-10 production in resting or irradiated cells. These studies demonstrate that cultured human keratinocytes are capable of producing interleukin-10. Human keratinocyte interleukin-10 production is dependent on the differentiation state of the cell and induced by ultraviolet B and, in particular, ultraviolet A1 radiation exposure. This novel property of ultraviolet radiation may account at least in part for the efficacy of phototherapy in inflammatory skin diseases.

Cell Differentiation↗
PubMed1994

Lesional expression of interferon-gamma in atopic eczema.

Atopic eczema is thought to be caused by skin-infiltrating CD4 T cells of the Th1-like and/or Th2-like subtype. We assessed expression of the Th1-like cytokine, interferon-gamma, and the Th2-like cytokine, interleukin-4, in lesional atopic skin. Compared with that in normal skin, interferon-gamma and interleukin-4 mRNA expression were increased in eczematous skin lesions in 13 and 4 of 15 patients, respectively. After successful therapy of atopic dermatitis, the increased interferon-gamma mRNA expression but not the increased interleukin-4 mRNA expression was significantly down-regulated. These data indicate that in-situ expression of interferon-gamma is linked to the clinical course of atopic dermatitis.

Cell Adhesion Molecules↗
PubMed1994

Actin polymerization, calcium-transients, and phospholipid metabolism in human neutrophils after stimulation with interleukin-8 and N-formyl peptide.

Signal transduction of interleukin-8 (IL-8) was analyzed in neutrophils, and compared with the well known neutrophil activator N-formyl peptide. Stimulation of human neutrophils with IL-8 induced a rapid polymerization of actin as detected by 7-nitrobenz-2-oxa-1,3-diazol-(NBD)-phallacidin staining of f-actin and reduction of monitored right-angle light scatter. Actin polymerization peaked within 10 seconds after the addition of IL-8 and was short-lived as compared to N-formyl peptide-induced stimulation. Analysis of phospholipids by thin-layer chromatography and analysis of deacylation products of lipid extracts by high-pressure liquid chromatography (HPLC) showed that IL-8 triggered a rapid rise of [32P]phosphatidyl-inositol(3,4,5)trisphosphate (PtdInsP3) followed by a slower increase of [32P]phosphatidylinositol(3,4)bisphosphate (PtdIns-3,4-P2) along with a rapid decrease of [32P]phosphatidylinositol(4,5)bisphosphate (PtdIns-4,5-P2). Changes in polyphosphoinositide metabolism were more moderate and transient than those obtained by N-formyl peptide. Moreover, [32P]phosphatidic acid (PA) production stimulated by IL-8 was minimal and transient as compared to the response activated by N-formyl peptide. Both IL-8 and N-formyl peptide induced Ca++ mobilization from intracellular stores, but IL-8 in contrast to N-formyl peptide failed to trigger the secondary influx of Ca++ from the extracellular medium. In summary, IL-8 and N-formyl peptide stimulated similar and distinct patterns of intracellular activation steps. This study indicates that IL-8 is a potent activator of intracellular events presumably required for chemotaxis, but a relatively weak activator for events associated with superoxide anion generation and proinflammatory activity.

Actins↗
PubMed1994

Evidence that DNA damage is a mediate in ultraviolet B radiation-induced inhibition of human gene expression: ultraviolet B radiation effects on intercellular adhesion molecule-1 (ICAM-1) expression.

Expression of intercellular adhesion molecule-1 (ICAM-1) is a prerequisite for the capacity of cells to physically interact with leukocytes. Ultraviolet B radiation previously was found to inhibit interferon gamma-induced ICAM-1 expression in human keratinocytes by suppressing interferon gamma-mediated upregulation of ICAM-1 mRNA levels. Because ultraviolet B radiation induces photoproducts in cellular DNA, the potential role of ultraviolet B radiation-induced DNA damage in this system was assessed. For this purpose, cells from a normal donor were compared with cells from patients with xeroderma pigmentosum from complementation groups C and D. Xeroderma pigmentosum cells are defective in the removal of ultraviolet B radiation-induced DNA lesions, and thus lower ultraviolet B radiation doses are required to retain equivalent numbers of DNA photoproducts at a given time point after irradiation. In the present study, ultraviolet B radiation inhibited interferon gamma-induced ICAM-1 mRNA expression in primary human skin fibroblasts in a manner identical to that previously observed for keratinocytes. Comparative studies employing normal versus xeroderma pigmentosum fibroblasts revealed that in xeroderma pigmentosum fibroblasts, two- to threefold lower ultraviolet B radiation doses were required to achieve inhibition equivalent to that observed in normal fibroblasts. In irradiated normal cells, inhibition of interferon gamma-induced ICAM-1 mRNA expression was transient and restored 12 h after ultraviolet B radiation exposure. In contrast, in xeroderma pigmentosum complementation group D cells, no restoration could be observed for up to 48 h, but responsiveness was restored in xeroderma pigmentosum complementation group C cells after 24 h. These studies indicate that ultraviolet B radiation-induced inhibition of interferon gamma-mediated ICAM-1 expression involves the generation of DNA photo-products.

Cell Adhesion Molecules↗