Human mast cells and extracellular matrix: immunohistochemical studies of normal skin and inflammatory dermatoses.
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Extracellular Matrix↗
Biomedical subjects
S Krüger-Krasagakes
Publications and source records attributed to S Krüger-Krasagakes.
Desensitization of melanoma cells to autocrine TGF-beta isoforms.
Previous studies have suggested that transforming growth factor-beta 1 (TGF-beta1) acts as an autocrine growth inhibitor on normal human melanocytes, while melanoma cells may not respond to this stimulus. The role of other TGF-beta isoforms such as TGF-beta2 and TGF-beta3 remained less well characterized. In the present study, the mRNA and protein levels of all three isoforms of TGF-beta were analyzed in a panel of human melanoma cell lines and in cultures of normal human melanocytes in vitro. Northern analysis showed that the degree of TGF-beta1, -beta2, -beta3 mRNA expression varied considerably in melanoma cells, whereas TGF-beta expression was very low in melanocytes. In melanoma cells, secreted amounts of TGF-beta1 and TGF-beta3 were found increased in comparison to normal melanocytes: 615 pg/ml vs. 118 pg/ml and 193 pg/ml vs. 30 pg/ml (mean values). In addition, low levels of TGF-beta2 were detected (mean value: 28 pg/ml). Although TGF-beta secretion increased, the proliferation of melanoma cells was found to be only moderately inhibited by TGF-beta isoforms, in contrast to its strong antiproliferative effect on normal human melanocytes: - 15%, -11%, and -18% vs. -52%, -46%, and -50% average inhibition at 0.5 ng/ml TGF-beta1, -beta2, and -beta3, respectively. The different efficacy of TGF-beta on melanocyte and melanoma cells was highly significant (P<0.0001); in addition, TGF-beta-dependent growth inhibition of melanoma cells from primary tumors vs. cells from metastases showed a trend for further decreased response for the metastatic populations (P< or = 0.075). Measurements of DNA synthesis revealed even more pronounced differences between melanocytes (-86%, -78%, and -80% inhibition, respectively, for TGF-beta1, -beta2, and -beta3) and melanoma cells (no inhibition). Our data show loss of responsiveness of melanoma cells to the growth-inhibitory function of TGF-beta isoforms but not of melanocytes. Although melanoma cells are not growth-inhibited by all three TGF-beta isoforms, they secrete significantly higher levels of TGF-beta, as compared to melanocytes. The reduced response indicates their escape from TGF-beta surveillance with ongoing tumor progression.
Cell Division↗
Adhesion of human mast cells to extracellular matrix provides a co-stimulatory signal for cytokine production.
Engagement of integrin receptors during cell adhesion leads to changes in the morphology and the state of activation of cells. We therefore examined whether mast cell adhesion to extracellular matrix proteins affects the synthesis and release of various proinflammatory cytokines. Cells of the human mast cell line HMC-1 were added to fibronectin (FN)-, vitronectin (VN)- or, as a control, bovine serum albumin (BSA)-coated wells and were stimulated with phorbol 12-myristate 13-acetate (PMA) and/or calcium ionophore A23187 (ionophore). Cytokine production was evaluated using semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis of cell extracts and enzyme-linked immunosorbent assay (ELISA) analysis of cell supernatants. After a 4-hr incubation, mRNA expression of interleukin (IL)-8 (and weakly of IL-6) was up-regulated in matrix-adherent cells, with further increase in the presence of PMA and/or ionophore, compared with unstimulated cells. High-level de novo expression of IL-3 and of granulocyte-macrophage colony-stimulating factor (GM-CSF) was observed mainly in matrix-adherent cells. These changes were paralleled by the secretory pattern of HMC-1 cells after a 24-hr stimulation. Unstimulated cells adherent to FN or VN had already released small amounts of IL-8, and both VN- and FN-adherent cells produced, almost invariably, a higher level of cytokines than BSA-exposed cells after additional stimulation. These results show that mast cell adhesion to matrix proteins by itself has only selected and minor effects, but additional activation of mast cells by secretory stimuli causes significantly enhanced cytokine gene expression and secretion, suggesting that mast cells are far more active in their natural tissue environment than hitherto suggested from data in suspension cultures.
Calcimycin↗
Expression and functional activity of the IL-8 receptor type CXCR1 and CXCR2 on human mast cells.
To further elucidate mechanisms involved in mast cell accumulation at sites of cutaneous inflammation, we have studied the ability of human leukemic mast cells (HMC-1 cells) to express functionally active IL-8 receptors. Expression of mRNA for both types of IL-8 receptors (CXCR1 and CXCR2) was demonstrated by PCR and of both proteins by flow cytometry. Binding and competition studies with 125I-labeled IL-8 and its homologue melanoma growth stimulating activity (125I-labeled MGSA) revealed two specific binding sites for IL-8, K1 = 1.1 x 10(11) M(-1) and K2 = 5 x 10(7) M(-1); and for MGSA, K1 = 2.8 x 10(10) M(-1) and K2 = 5 x 10(7) M(-1). This finding was supported by a dose-dependent rise of cytosolic free calcium concentration ([Ca2+]i) induced by both chemokines and to a lesser extent by the homologue neutrophil-activating peptide-2 (NAP-2). A significant migratory response of human leukemic mast cells (HMC-1) was observed with all three chemokines at a range from 10(-8) M to 10(-9) M. Moreover, the formation of cellular F-actin was induced in a rapid, dose-dependent fashion, with a maximally 1.7-fold increase at 10(-7) M. Using postembedding immunoelectron microscopy, we could show the expression of CXCRI on the cytoplasmatic membrane of isolated human skin mast cells whereas CXCR2 was located in mast cell-specific granules. These findings demonstrate for the first time the functional expression of both types of IL-8 receptors on human mast cells, suggesting a role for their ligands during mast cell activation and recruitment.
Actins↗
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↗
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↗
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↗
Detection of intracellular interleukin-8 in human mast cells: flow cytometry as a guide for immunoelectron microscopy.
The chemokine interleukin-8 (IL-8) mediates infiltration and adhesion of neutrophils during inflammatory processes. We have previously shown that this cytokine can be produced and released by normal and leukemic human mast cells (HMC-1 cells). To assess whether and to what extent this cytokine is stored intracellularly, we investigated production and localization of IL-8 at the single-cell level by combined use of flow cytometry (FACS) and immunoelectron microscopy. Conditions necessary for optimal fixation and permeabilization of HMC-1 cells were determined by measuring changes in cell-specific light scatter parameters and by estimating cellular uptake of propidiumiodide (PI). In this way, we were able to detect IL-8 with a monoclonal antibody in stimulated cells that were microwave-fixed with a combination of paraformaldehyde (4%) and glutaraldehyde (0.1%), followed by permeabilization with saponin (0.025%). FACS analysis revealed time-dependent synthesis of IL-8 with at most 50% positively stained cells at 8-12 hr after stimulation. For pre-embedding immunogold electron microscopy, cells were treated according to the protocol established by flow cytometry. IL-8 was found to be located in specific cytoplasmic, electron-dense granules of stimulated HMC-1 cells. These results confirm and extend our previous findings by demonstrating IL-8 expression in HMC-1 cells at the single-cell level. In addition, we propose that quantitative FACS can be reliably used in a timesaving manner to establish appropriate conditions for pre-embedding immunoelectron microscopy of intracellular antigens.
Antibodies, Monoclonal↗
Fucosyltransferase III and sialyl-Le(x) expression correlate in cultured colon carcinoma cells but not in colon carcinoma tissue.
The potential contribution of fucosyltransferases to the overexpression of sialyl-Le(x) antigen was investigated in the colon carcinoma cell line HT-29 and in human colon carcinoma tissue. In HT-29 cells as well as in normal or malignant colonic tissues Fuc-TIII, Fuc-TIV, Fuc-TVI but not Fuc-TV nor Fuc-TVII were detectable after RT-PCR. Sodium butyrate treatment of HT-29 cells increased (to about 200%) and DMSO treatment decreased (to about 20%) the expression of sialyl-Le(x). This modulation of sialyl-Le(x) was concomitant with the analogous increase/decrease of mRNA of Fuc-TIII but not Fuc-TIV. Fuc-TVI was not detectable by Northern blotting in HT-29 cells. In six human colon carcinomas which exhibited strong overexpression of sialyl-Le(x), the expression of Fuc-TIII-mRNA was the same or lower than in the corresponding normal colonic tissue. Thus Fuc-TIII expression may be affecting the expression of the sialyl-Le(x) moiety in HT-29 cells but not in human colon carcinoma tissue.
Antibodies, Monoclonal↗
A subclone (5C6) of the human mast cell line HMC-1 represents a more differentiated phenotype than the original cell line.
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Antigens, Surface↗
Production of interleukin-6 by human mast cells and basophilic cells.
Since mast cells and basophils are thought to play a central role in several types of cutaneous inflammatory and allergic reactions, and since interleukin-6 (IL-6) is an important mediator in these processes, we have studied the ability of the human mast cell line HMC-1, the human basophilic cell line KU812, and human skin mast cells to produce IL-6. All three cell types proved to be potent sources of this cytokine after appropriate stimulation. Transcription of IL-6 mRNA was first detectable 2 h after stimulation with the ester phorbol myristate acetate (PMA) and the calcium ionophore A23187 in both cell lines, as evidenced by semiquantitative reverse transcriptase polymerase chain reaction analysis. Whereas resting cells did not produce IL-6 protein, PMA/A23187-stimulated cells released immunoreactive and biologically active IL-6, as demonstrated and quantitated by enzyme-linked immunosorbent assay and by the use of TEPC 1033 cells, an IL-6-dependent murine plasmacytoma cell line. Stimulated KU812 cells secreted sevenfold more IL-6 (up to 15 ng/ml) than HMC-1 cells (up to 2.4 ng/ml). Immunoblotting of HMC-1- and KU812 cell-derived IL-6 revealed several IL-6 forms in the molecular weight range of 21 to 30 kDa. Immunoelectron microscopic studies of human skin biopsies provided evidence that unstimulated mast cells do not contain preformed IL-6 but accumulate IL-6 in cytoplasmic and extruded granules after IgE-dependent stimulation. These findings suggest that IL-6 secreted by human mast cells and basophils potentially contributes to allergic, other immunologically mediated and nonspecific inflammatory responses.
Basophils↗
Release of stem cell factor from a human keratinocyte line, HaCaT, is increased in differentiating versus proliferating cells.
Stem cell factor, a recently discovered growth factor for hematopoietic stem cells, mast cells, and melanocytes, was initially reported to be produced by fibroblasts. In this study, we investigated the secretion of this factor from human HaCaT cells during in vitro culture and compared it to synthesis by cells in the skin. Release of stem cell factor from freshly cultured keratinocytes was comparable to that of HaCaT cells and was nearly half that produced by fibroblasts and umbilical vein endothelial cells. No stem cell factor was detectable in culture supernatants of melanocytes. HaCaT cells underwent spontaneous differentiation after a period of proliferation until confluency. Depending on duration of culture, they released increasing amounts of stem cell factor (approximately 150 pg/10(6) cells on day 3 (proliferating cells) vs approximately 450 pg/10(6) cells on day 14 (differentiating cells) measured by enzyme-linked immunosorbent assay. Stimulation for 24 h with the calcium ionophore A 23187 (10(-6) to 10(-8) M) further enhanced release. Western blot analysis of HaCaT cell lysates with a stem cell factor antibody revealed two proteins with the known molecular weights of membrane-bound and soluble stem cell factor. By semiquantitative reverse transcriptase polymerase chain reaction, full-length as well as spliced type stem cell factor mRNA was found to be increased in differentiating versus proliferating HaCaT cells. Keratinocytes are thus potentially important sources of stem cell factor in human skin, and HaCaT cells provide a useful model for further studies of stem cell factor from keratinocytes.
Base Sequence↗
Interactions of immature human mast cells with extracellular matrix: expression of specific adhesion receptors and their role in cell binding to matrix proteins.
Interactions of cells with their extracellular matrix (ECM) are central to tissue-specific migration, localization, and function of migratory cells. Since mast cells circulate as immature precursor cells and home to tissues in a characteristic distribution, with increases in various disease states, we used the immature human mast cell line HMC-1 as a model to investigate the poorly understood mast cell-ECM interactions in humans. Functional adhesion studies showed that HMC-1 cells spontaneously adhere to fibronectin and laminin (80% at 6 and 12 microgram/ml, respectively) and to collagen type I and III (50% at 20 microgram/ml), whereas binding to vitronectin and collagen type IV required cell activation by phorbol myristate acetate. HMC-1 cells did not adhere to hyaluronic acid. Moreover, both fibronectin and laminin supported pronounced cytoplasmatic spreading with formation of isolated lamellipodia, whereas these cells exhibited a round cell shape on collagen and vitronectin, as shown by scanning electron microscopy. On flow cytometric analysis, HMC-1 cells expressed several adhesion molecules including the integrins beta 1, alpha 2 through alpha 6, alpha v, and alpha v beta 5, as well as CD44. Adhesion to fibronectin and vitronectin was found to be divalent cation- and arginine-glycine-aspartic acid-dependent, and could be blocked by antibodies to beta 1 or alpha 5, and alpha v or alpha v beta 5, respectively. In contrast, binding to laminin and collagen could not be blocked by monoclonal antibodies to any of the cell surface adhesion receptors expressed. Our results show that immature mast cells are able to modify their adhesive behavior in response to various ECM proteins and activating stimuli, and that this phenomenon is partly integrin mediated. These findings may be important for our understanding of the mechanisms leading to tissue-specific localization of mast cells.
Cell Adhesion↗
Modulation of in vitro cytokine release from human leukemic mast cells (HMC-1) by glucocorticoids.
Mast cells are well known effector cells not only in allergic but also in diverse acute and chronic inflammatory diseases. We have shown previously that these cells produce a broad spectrum of cytokines which might contribute to mast cell-dependent pathology. In the present study, we have investigated the influence of four potent glucocorticoids, methylprednisolone-aceponate, methylprednisolone-17-propionate, prednicarbate, and betametasone valerate (10(-5) M-10(-9) M), on the IL-1 beta, IL-3, IL-8, and tumor necrosis factor alpha secretion of the HMC-1 mast cell line as measured by ELISA. All four glucocorticoids caused a comparable dose- and time-dependent inhibition of cytokine release from HMC-1 cells stimulated for 24 h with phorbol 12-myristate 13-acetate 25 ng/ml and calcium ionophore 2 x 10(-7) M. These results shed further light on the mechanisms involved in antiinflammatory effects of glucocorticoids in allergic inflammation.
Administration, Topical↗
Glucocorticoid-induced modulation of cytokine secretion from normal and leukemic human myelomonocytic cells.
Since glucocorticoid effects on inflammatory processes may be mediated via modulation of cytokine release, different types of myelomonocytic cells were stimulated in vitro with lipopolysaccharide (50 ng/ml) or phorbol myristate acetate (25 ng/ml) plus the ionophore A23187, 2 x 10(-7) M, and release of interleukin (IL)-1 beta, IL-8 and tumor necrosis factor (TNF)-alpha was measured after 24 h by ELISA. Peripheral blood mononuclear cells from two allergic and two normal human donors released similarly large quantities of IL-8 and lower amounts of IL-1 beta and TNF-alpha. This also held for myelomonocytic cell lines, with THP-1 cells being most active, followed by U-937 and HL-60 cells. All potent glucocorticoids studied caused a dose-dependent inhibition of cytokine release from donor cells, being most marked for IL-1 beta and lowest for IL-8. Inhibition of cytokine release was also noted with U-937 cells, with clear differences in potency between the glucocorticoids, whereas release was enhanced in all experiments with THP-1 cells. These results were confirmed with Northern blot analysis. Modulating effects of glucocorticoids on cytokine release are thus complex, and are particularly dependent on the cell type studied.
Administration, Topical↗
Production of cytokines by human melanoma cells and melanocytes.
Experimental animal models have shown that various cytokines, depending of their specific properties, may support growth and metastasis of tumor cells or even lead to tumor rejection. The analysis of expression of cytokine genes by melanoma cell lines indicated that melanoma cells constitutively produce both autostimulatory and inhibitory cytokines. Using reverse transcriptase polymerase chain reaction analysis, simultaneous expression of several cytokines, including interleukin-1 beta (IL-1 beta), IL-6, IL-8, tumor necrosis factor-alpha, and granulocyte-macrophage colony-stimulating factor, by melanoma cells was found. The same cytokine transcripts were detected in melanocytes, suggesting that cells of the melanocytic lineage express a specific pattern of cytokines in vitro. All these cytokines are known to be able to stimulate effector cells of the host. Additionally, production of mRNA for IL-10, a cytokine with potential immunosuppressive properties, was detected in melanoma cells and melanocytes. These and other cytokines are likely to be involved in the immune response to cancer and at this time it is unknown what the net effects of multiple cytokines are on the outcome of the host response to tumor.
Cells, Cultured↗
Adhesion molecules on the human mast cell line HMC-1 are upregulated during cell activation.
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Binding Sites↗