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Biomedical subjects

M Detmar

Publications and source records attributed to M Detmar.

At least 55 records · Page 3Linked to original sources

Overexpression of vascular permeability factor/vascular endothelial growth factor and its receptors in psoriasis.

Psoriatic skin is characterized by microvascular hyperpermeability and angioproliferation, but the mechanisms responsible are unknown. We report here that the hyperplastic epidermis of psoriatic skin expresses strikingly increased amounts of vascular permeability factor (VPF; vascular endothelial growth factor), a selective endothelial cell mitogen that enhances microvascular permeability. Moreover, two VPF receptors, kdr and flt-1, are overexpressed by papillary dermal microvascular endothelial cells. Transforming growth factor alpha (TGF-alpha), a cytokine that is also overexpressed in psoriatic epidermis, induced VPF gene expression by cultured epidermal keratinocytes. VPF secreted by TGF-alpha-stimulated keratinocytes was bioactive, as demonstrated by its mitogenic effect on dermal microvascular endothelial cells in vitro. Together, these findings suggest that TGF-alpha regulates VPF expression in psoriasis by an autocrine mechanism, leading to vascular hyperpermeability and angiogenesis. Similar mechanisms may operate in tumors and in healing skin wounds which also commonly express both VPF and TGF-alpha.

Base Sequence↗

[Multicentric reticulohistiocytosis and myelodysplastic syndrome].

Multicentric reticulohistiocytosis (MRH) is a rare disorder of skin and joints, and its aetiology is unknown. We describe a male patient who had first developed osteoblastic lesions of the skeleton in 1976 at the age of 59 years. Three years later, he presented with multiple papular and nodular skin lesions, predominantly on the limbs and upper trunk, and 4 years later he developed painful arthropathy. In 1988 skin examination showed multiple brownish-red papulo-nodules, some of which, at mechanically stressed areas, were ulcerated. The patient complained of pronounced arthrotic disorders with reduced joint mobility. Examination of biopsy specimens from active skin lesions demonstrated extensive numbers of macrophages with partial confluence to giant cells with typical ground-glass cytoplasm. Electron microscopy revealed phagocytosis of collagen-like-structures. Examination of bone marrow biopsy specimens revealed diffuse infiltration by histiocytic cells. The diagnosis made was therefore MRH. The patient was treated for several years with different therapeutic regimens, including azathioprin, dapsone, prednisolon, chlorambucil and cyclophosphamide, and complete remission of skin lesions and of bone marrow infiltration was observed. However, a myelodysplastic syndrome with refractory anaemia and ring sideroblasts developed, which is generally understood to be a preleukaemic condition. Myelodysplastic syndromes commonly develop between 3 and 10 years after the start of a therapy with antineoplastic agents.

Antineoplastic Combined Chemotherapy Protocols↗

Phospholipid analogue hexadecylphosphocholine inhibits proliferation and phosphatidylcholine biosynthesis of human epidermal keratinocytes in vitro.

The alkylphospholipid hexadecylphosphocholine (HePC), member of a new class of antineoplastic drugs, has been previously shown to exert cytotoxic effects on neoplastic cell lines in vitro, and a selective antineoplastic activity has been reported after topical application of HePC in vivo, in particular on skin metastases of human mammary carcinomas. Preliminary observations suggest that HePC might also be beneficial in the treatment of non-neoplastic skin diseases characterized by epidermal hyperplasia such as psoriasis. Therefore, we investigated whether HePC might inhibit the proliferation of normal human keratinocytes, and whether its effects might be dependent upon the proliferative status of the treated cells. Moreover, its effects on phosphatidylcholine biosynthesis were studied in keratinocytes. HePC dose-dependently decreased cell numbers, thymidine incorporation, and protein synthesis when applied during the growth phase of keratinocytes grown in serum-free medium, with a minimal inhibitory dose of 10(-7) mol/l for thymidine incorporation, 3 x 10(-7) mol/l for cell numbers, and 10(-6) mol/l for 35S-methionine incorporation. No major differences were observed when keratinocytes were grown under high-Ca++ conditions. In contrast, slowly proliferating confluent keratinocyte cultures showed growth inhibition only after 10(-4) mol/l HePC. Phosphatidylcholine biosynthesis was dose-dependently inhibited by HePC with a half inhibitory concentration of 3 x 10(-6) mol/l, and with translocation of the rate-limiting enzyme. CTP:phosphocholine cytidylyltransferase, to the cytosol, where the enzyme is inactive. These data show a pronounced antiproliferative effect of HePC also on proliferating non-malignant keratinocytes, and are compatible with its possible action on hyperproliferative skin disorders.

Cell Division↗

Vellus hair follicle-derived keratinocyte culture: a new experimental model in human hair research.

Biological and biochemical mechanisms of hair growth are difficult to study in vivo; therefore the development of in vitro models is of great interest. Today, we have of our disposal reliable techniques to cultivate cell populations and entire components of terminal hair follicles; however, in vitro culture models for cells derived from vellus hair follicles have not yet been established. In this study, we present a technique for cultivating vellus hair follicle-derived keratinocytes (VHK) and we present first findings on their characterization. Primary cultures of VHK were obtained as outgrowths of cultured intact vellus hair follicles prepared by microsurgical means after incubation of full-thickness human skin with dispase. (1) VHK cultures reached confluency after 16-20 days and 3-4 subcultures were possible. (2) VHK were characterized as epithelial cells by light and electron microscopy. (3) A multi-layered stratified epithelium with 8-10 cell layers was observed by electron microscopy presenting abundant keratinosomes in individual cells in contrast to outer root sheath keratinocytes. (4) Synthesis studies of two glycoproteins characteristic for undifferentiated (gp 38) and for differentiated (gp 80) keratinocytes revealed higher synthesis levels for gp 80 and lower levels for gp 38 in VHK as compared to normal epidermal keratinocytes in vitro. These findings suggest a distinct morphologic and differentiation pattern of VHK in culture. This experimental model provides a new tool to study mechanisms of hair growth regulation in vellus hair follicles and to compare them to those of terminal hair follicles.

Cell Differentiation↗

Corticosteroids induce proliferation but do not influence TNF- or IL-1 beta-induced ICAM-1 expression of human dermal microvascular endothelial cells in vitro.

The effects of hydrocortisone, dexamethasone, betamethasone 17-valerate and clobetasol propionate at concentrations of 10(-5)-10(-12) M on the proliferation of human dermal microvascular endothelial cells (HDMEC) were studied in vitro. In addition, confluent HDMEC were treated with TNF (1000 U/ml) or IL-1 beta (1000 U/ml) alone or in combination with the corticosteroids (10(-5) M, 10(-6) M) for 24 h, and cytokine-induced expression of intercellular adhesion molecule-1 (ICAM-1) was assessed by immunocytochemistry. Controls were treated either with growth medium or with the corticosteroids alone. All tested corticosteroids stimulated HDMEC growth after 4 and 6 days of treatment in a dose-dependent manner, as assessed by 3H-thymidine incorporation and the 4-methyl-umbelliferyl heptanoate (MUH) assay. The minimal effective concentration was 10(-9) M for hydrocortisone, 10(-10) M for dexamethasone and betamethasone, and 10(-12) M for clobetasol. In untreated and in corticosteroid-treated cultures, less than 5% of the cells expressed ICAM-1. TNF and IL-1 beta were strong inducers of ICAM-1 expression on 74% and 82% of the cells, respectively. None of the tested corticosteroids significantly influenced cytokine-induced ICAM-1 expression, suggesting that the anti-inflammatory effects of corticosteroids are not related to ICAM-1 modulation on HDMEC.

Adrenal Cortex Hormones↗

Culture of hair matrix and follicular keratinocytes.

In recent years, a variety of in vitro models for the cultivation of hair follicles and their constituents have been developed. Outer root sheath (ORS) keratinocytes (KC) have been mainly studied in explant cultures, planted on bovine eye lens capsules, collagen substrata, 3T3 cell feeder layers, or dermal equivalents, yielding outgrowth of a multilayered stratified epithelium with some biochemical and ultrastructural characteristics of keratinocytic differentiation. More recently, ORS KC cultures have also been initiated from single cell suspensions, and organotypic cultures have been obtained by recombination with dermal cells, inducing a higher degree of epidermal differentiation. Presumptive human hair matrix cells have been isolated from plucked anagen hair follicles and have been successfully propagated on 3T3 cell or normal human fibroblast feeder layers, giving rise to multilayered stratified KC cultures. In contrast, only preliminary data exist concerning the cultivation of bulge cells that have been suggested to represent follicular stem cells. In conclusion we dispose of several in vitro models today to cultivate ORS KC and hair matrix cells that have increased our knowledge on the regulation of the human hair cycle by soluble factors and dermal-epidermal interactions. Further comparative studies on ORS KC, bulge cells and matrix cells have to be carried out to confirm the distinct character of these hair KC subsets.

Animals↗

[Bacillary epithelioid angiomatosis in advanced HIV infection].

A patient with advanced HIV infection developed multiple angiomatous papules and nodules on the upper chest within a few days. At first sight the lesions resembled disseminated Kaposi's sarcoma; the differential diagnosis, however, included eruptive haemangiomas and pyogenic granulomas. Such distinct clinical characteristics as the collarette-like desquamation at the borders of the tumours led to the suspicion of bacillary epithelioid angiomatosis in HIV infection, which was then confirmed by histology and ultrastructural demonstration of bacillary colonies within the lesions. Under systemic antibiotic treatment, marked regression of the lesions was quickly observed within 1 week and complete regression occurred after 4 weeks. It is important to consider bacillary angiomatosis in HIV infection in the differential diagnosis of Kaposi's sarcoma, and it is a separate entity in the form of angioproliferation caused by bacteria.

AIDS-Related Opportunistic Infections↗

Cytokine regulation of proliferation and ICAM-1 expression of human dermal microvascular endothelial cells in vitro.

The effects of recombinant human interleukin 1 alpha (IL-1 alpha), interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6), granulocyte/macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor-alpha (TNF) on the cell proliferation and the expression of intercellular adhesion molecule-1 (ICAM-1) were assessed in cultured human dermal microvascular endothelial cells (HDMEC). IL-1 alpha and IL-1 beta stimulated the proliferation of HDMEC in a dose-dependent manner, whereas in control experiments using human umbilical vein endothelial cells (HUVEC), IL-1 alpha and IL-1 beta did not stimulate HUVEC growth. Also GM-CSF stimulated the proliferation of HDMEC, whereas IL-6 did not affect endothelial cell growth in vitro. Treatment with IL-1 alpha, IL-1 beta, and TNF markedly increased the expression of ICAM-1 on HDMEC in a time- and dose-dependent manner, in contrast to IL-6 and GM-CSF. By pre-embedding immunoelectron microscopy, membrane-bound expression of ICAM-1 was visualized with pronounced labeling in areas of microvillous cell protrusions. The TNF-induced expression of ICAM-1 on HDMEC was blocked by co-incubation with a neutralizing antibody against TNF, but not with neutralizing antibodies against IL-1 alpha, IL-1 beta, or IL-6. In addition, co-incubation of HDMEC with TNF and the retinoid compound acitretin, dexamethasone, or indomethacin did not abrogate the TNF-induced ICAM-1 expression. These results disclose IL-1 as a major, multifunctional endothelial cell-targeted cytokine and further confirm the concept that pro-inflammatory cytokines exert differential regulatory effects on dermal microvascular endothelial cell proliferation and expression of cell-adhesion molecules.

Adult↗

Growth characteristics and differentiation of basal cell carcinoma in vitro--immunohistochemical, gel electrophoretic, and ultrastructural analysis.

Cell cultures were established from 48 solid basal cell carcinomas (BCC) and from the normal epidermis of the same patients. The growth characteristics and differentiation of BCC cells in vitro were compared with normal keratinocytes (nKC) by using immunohistochemistry, two-dimensional gel electrophoresis including immunoblots, transmission electron microscopy, and soft agar suspension culture. After isolation of the tumor tissue under a stereodissection microscope, explants were cultured on feeder layers of mitomycin-treated 3T3 cells. After 3-5 d, 73% of all explants of BCC could be successfully cultured showing spindle-shaped outgrowing cells. Compared to nKC, cultured BCC cells had a lower growth rate and showed a wider intercellular polymorphism regarding size and shape. Their labeling pattern with a wide panel of monoclonal antibodies showed significant differences from that of nKC. In particular, only weak reactions for various cytokeratins, filaggrin and vimentin depending on the BCC cell type (small, middle, large) were found. Two-dimensional gel electrophoresis revealed expression of keratins 5, 6, 14, 16, and 17 in BCC cells and of K 5, 6, 13, 14, 16, 17, and 19 in nKC. These findings were confirmed by immunoblot. On the ultrastructural level, only a few desmosomes and a lower degree of keratinization markers were detected in BCC cells; finally, when cultured in soft agar BCC cells formed colonies whereas nKC did not. Our findings indicate that cultured BCC cells may preserve in vitro some in vivo characteristics and maintain a growth and differentiation pattern that differs from cultured nKC. The culture model presented here provides further insights into the cytogenetic and histogenetic characteristics of BCC.

Aged↗

Cytokine-stimulated human dermal microvascular endothelial cells produce interleukin 6--inhibition by hydrocortisone, dexamethasone, and calcitriol.

The effects of lipopolysaccharide (LPS), recombinant human tumor necrosis factor-alpha (TNF), recombinant human interleukin 1-beta (IL-1 beta), and interferon-gamma (IFN-gamma) on IL-6 production were determined by enzyme-linked immunosorbent assay (ELISA) and by Northern blot analysis in cultured human dermal microvascular endothelial cells (HDMEC). Unstimulated HDMEC did not produce significant amounts of IL-6, whereas lipopolysaccharide (LPS), TNF, and IL-1 beta were potent inducers of HDMEC-derived IL-6 production. Treatment with IFN-gamma had no effect. IL-1 beta stimulation resulted in pronounced IL-6 production after 4 h, followed by complete downregulation at the transcriptional level after 24 h. In contrast, LPS and TNF induced prolonged stimulation of IL-6 production by HDMEC as IL-6 mRNA transcripts were still detected after 24 h treatment and IL-6 protein was markedly increased at this timepoint. The effects of hydrocortisone, dexamethasone, calcitriol, acitretin, and cyclosporin A on TNF- or IL-1 beta-induced IL-6 production by HDMEC were determined by ELISA. Both hydrocortisone and dexamethasone dose-dependently inhibited the cytokine-induced IL-6 production, whereas the inhibition by calcitriol was less pronounced. In contrast, acitretin and cyclosporine A had no influence on cytokine-induced HDMEC IL-6 production. These results disclose dermal endothelial cells as a major source for the pro-inflammatory cytokine IL-6, involved in the regulation of inflammatory skin processes. As IL-6 seems to play a key role in the pathogenesis of psoriasis, the beneficial effects of corticosteroids and calcitriol in this disease may partly be explained by their ability to inhibit HDMEC-derived IL-6 production.

Acitretin↗

[Granulocyte colony stimulating factor (G-CSF) in treatment of patients with HIV-associated mucocutaneous Kaposi sarcoma. Successful use in virus and drug-induced leukopenia].

Three patients with HIV-associated Kaposi sarcoma were treated with human recombinant granulocyte colony stimulating factor (G-CSF). They had all developed leucopenia during treatment with recombinant interferon-alpha-2a, in two cases combined with vincristine. In all three patients, there was an obvious rapid stimulation after s.c. injection of 300 or 150 micrograms G-CSF per day; the white blood count reached normal values within only a few days and partial transformation to leucocytosis took place. After discontinuation of G-CSF, leucocyte counts regressed rapidly to pretreatment levels. A dose of 150 micrograms of G-CSF twice to three times per week proved to be sufficient to keep the white blood cell count in the normal range allowing the treatment necessary for Kaposi sarcoma. G-CSF therapy had no serious side effects. One of the patients developed a tumour-like infiltration in his left upper jaw, which histologically simulated Burkitt's lymphoma and which regressed spontaneously after discontinuation of the G-CSF therapy. G-CSF plays an important role in the treatment of patients with HIV-associated Kaposi sarcoma and enables combined treatment with zidovudine, interferon, and cytostatic drugs.

Adult↗

[Linear hyperpigmentation caused by bleomycin].

We report on an uncommon but characteristic cutaneous side-effect of bleomycin. A 52-year-old woman being treated for carcinoma of the cervix developed linear hyperpigmentation in wheals in the lumbosacral region, the lateral thorax and above the elbow. The skin lesions appeared during the fourth cycle of chemotherapy with bleomycin. Histologically, incontinence of melanin, focal parakeratosis and a lymphocytic infiltrate with epidermotropism were prominent. By electron microscopic examination metabolically highly active melanocytes were found, with increased number of melanosomes at all stages of maturation and deposits of extracellular melanin in the underlying dermis. The epidermal keratinocytes were unchanged.

Antineoplastic Agents↗

[Mechanism of the interaction of leukocytes and dermal endothelial cells in cutaneous inflammation].

The infiltration of specific leucocyte populations into inflamed cutaneous tissue is dependent on their interactions with dermal endothelial cells. The dynamic multistep process of vasodilatation, adhesion, transendothelial migration, and penetration through the basal membrane is controlled by a considerable number of soluble mediators and cell adhesion molecules. In this process, dermal endothelium plays a critical role as a gate-keeper who regulates adhesion and penetration of neutrophils, lymphocytes, or monocytes by selection and activation of specific leucocyte subpopulations. In this review, the presently known functions of the involved cell adhesion molecules of the integrin, selectin, and immunoglobulin superfamily, as well as their interactions and their regulation by cytokines and other mediators are summarized.

Cell Adhesion Molecules↗

Cultivation of human dermal microvascular endothelial cells in vitro: immunocytochemical and ultrastructural characterization and effect of treatment with three synthetic retinoids.

A new reliable and reproducible technique to culture endothelial cells from the small vessels and capillaries of human skin is introduced, and proliferation and differentiation of the growing cells are characterized. The endothelial origin of the culture cells was confirmed by light- and electron microscopy and by labelling with Ulex europaeus Agglutinin I and an antibody against Factor VIII-related antigen. Further immunocytochemical characterization showed that 92-100% of the cells were positive for beta 2-microglobulin and the entire cell population expressed vimentin, whereas cytokeratins, desmin, HLA-DR antigen, Leu 6 and S 100 protein, could not be detected. As vascular endothelium is a common site of inflammation and retinoids have been shown to be of good clinical efficacy in some chronic inflammatory skin diseases, we investigated the influence of etretinate, etretin and isotretinoin on proliferation and antigen expression of our culture cells. All retinoids applied inhibited proliferation of endothelial cells in a dose- and time-dependent manner whereas they induced neither HLA-DR nor intercellular adhesion molecule-1 (ICAM-1). Furthermore, none of the retinoids applied influenced the gamma-interferon-induced expression of these surface antigens on endothelial cells. Our results suggest that the action of retinoids in skin inflammation is not mediated by modulation of HLA-DR or ICAM-1. The cell culture technique described here is an interesting and reliable model for studying the influence of drugs on endothelial cell growth and differentiation in vitro.

Acitretin↗

A case of classical mycosis fungoides associated with human T-cell lymphotropic virus type I.

A 72-year-old male patient from north-eastern Iran developed the typical clinical and histopathological features of mycosis fungoides with lymphadenopathy, but without any other systemic involvement. Human T-cell lymphotropic virus (HTLV-I) antibodies were detected in the patient's serum by two different ELISAs and by Western blot using purified viral particles from MT-2 culture supernatants. Cultured peripheral blood lymphocytes were positive for labelling with anti-HTLV-I serum. Southern blot hybridization of DNA extracted from a skin tumour and from an involved lymph node revealed integrated proviral DNA with identical restriction patterns. This case supports a relationship between mycosis fungoides and HTLV-I and may indicate a new region of endemic HTLV-I infection.

Aged↗

Culture of human sebocytes and markers of sebocytic differentiation in vitro.

Human sebocytes obtained as explants after in vitro culture of isolated sebaceous glands were recently shown to maintain in part a sebocytic differentiation. The aim of this study was to further identify markers of sebocytic differentiation in vitro. Therefore, the morphology of cultured human sebocytes, and their differentiation with lipid storing and expression of cellular proteins were investigated by microscopy, electron microscopy, study of cell kinetics, cytochemistry and immunocytochemistry, and were compared to cultured human keratinocytes obtained from the same skin specimens. At first, sebocytes in all stages of sebocytic differentiation were detected in vitro. Abundant cytoplasmic lipids and the absence of desmosomes were identified as their ultrastructural characteristics. Secondly, an increasing number of sebocytes storing lipids was detected during cell proliferation. Sebocytes contained up to 4 times more lipids than keratinocytes in vitro. Squalene and increased quantities of wax/sterol esters could be extracted from secondary sebocyte cultures. Thirdly, the monoclonal antibodies 6B10 (keratin 4), RPN1162 (keratin 7), and OM-1 labeled only sebocytes in vitro. Furthermore, sebocytes presented a marked expression of keratin 19 in comparison to keratinocytes, as detected with CK 4.62, and a lack of RPN1161 (keratins 1 and 2) expression, which was typically found to be expressed in cultured keratinocytes. The culture of human sebocytes possessing several characteristics of sebocytic differentiation in vivo offers unique possibilities in investigating direct effects on sebaceous cell growth, differentiation and their regulation.

Antibodies, Monoclonal↗

Tumor necrosis factor-alpha inhibits cell proliferation and induces class II antigens and cell adhesion molecules in cultured normal human keratinocytes in vitro.

The effects of recombinant human tumor necrosis factor-alpha (TNF) on cell proliferation, cell morphology, and on the expression of class II alloantigens and intercellular adhesion molecule-1 (ICAM-1) were assessed in human keratinocytes cultured in serum-free medium. TNF inhibited cell proliferation in a time- and dose-dependent manner with a minimum effective dose of 10 U/ml and a 50% inhibitory dose of 100 U/ml. However, TNF did not induce cell death, and the growth inhibition induced by TNF was completely reversible after its withdrawal. In vitro combination of TNF with interferon-alpha (IFN-alpha) and IFN-beta resulted in additive growth inhibitory effects, while IFN-gamma enhanced the TNF mediated growth inhibition in a synergistic way. Furthermore, TNF altered the morphology of the growing keratinocytes inducing the appearance of a fusiform, fibroblast-like population. Also, treatment with TNF over 6 days markedly induced the expression of ICAM-1 on the cultured keratinocytes with a minimal effective dose of 10 U/ml, while HLA-DR was only moderately expressed after 1,000 U/ml. TNF did not induce HLA-DQ, but reduced the IFN-gamma induced expression of HLA-DR and HLA-DQ. By immunoelectron microscopy, an intense membrane-bound labeling for ICAM-1 was found after treatment with TNF, clearly pronounced in areas of microvillous membrane protrusions. These results indicate that epidermal keratinocytes are a major target for various biological effects of TNF. We also found that TNF differentially modulates IFN-gamma-induced effects, thus suggesting its potential role in the regulation of inflammatory skin disorders.

Cell Adhesion Molecules↗

Effects of rIFN alpha, beta, and gamma on the morphology, proliferation, and cell surface antigen expression of human dermal microvascular endothelial cells in vitro.

The influence of recombinant human interferon alpha 2a (rIFN alpha), recombinant human interferon beta 1 (rIFN beta), and recombinant human interferon gamma (rIFN gamma) on human dermal microvascular endothelial cells (HDMEC) cultured in vitro was studied in various rIFN concentrations (0.1 IU/ml-10(4) IU/ml) over 2, 3, 4, 6, 8, and 10 d. Cell morphology and ultrastructure, cell proliferation, expression of class II alloantigens (HLA-DR and HLA-DQ), and intercellular adhesion molecule-1 (ICAM-1) were investigated using an in vitro technique established in our laboratory. All rIFN tested induced alterations of typical HDMEC morphology; the cells became spindle-shaped and fibroblastoid, although they maintained their endothelial cell marker expression. Also, all IFN dose- and time-dependently inhibited the proliferation of HDMEC in vitro (rIFN alpha greater than beta greater than gamma), whereby rIFN alpha exerted the strongest growth-inhibitory effect. Alkaline phosphatase anti-alkaline phosphatase (APAAP) immunocytochemistry of the cultured cells showed dose- and time-dependent stimulation of ICAM-1 and class II antigen expression only by rIFN gamma (HLA-DR greater than HLA-DQ), rIFN alpha and beta did not exert any immunomodulatory activity on HDMEC in vitro. These results indicate that HDMEC are an important target for the action of IFN. Besides growth inhibition, it seems that rIFN gamma in particular may be involved in the modulation of leucocyte adhesion and trafficking by altering the immunophenotype of the endothelial cell population.

Antigens, Surface↗