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Biomedical subjects

F Levi-Schaffer

Publications and source records attributed to F Levi-Schaffer.

At least 55 records · Page 3Linked to original sources

Halofuginone--an inhibitor of collagen type I synthesis--prevents postoperative formation of abdominal adhesions.

OBJECTIVE: To evaluate the effects of halofuginone, a specific inhibitor of collagen type I synthesis, on the postoperative formation of abdominal adhesions in rats. SUMMARY BACKGROUND DATA: Postoperative adhesions remain the leading cause of small bowel obstruction in the Western world. Surgical trauma causes the release of a serosanguineous exudate that forms a fibrinous bridge between two organs. This becomes ingrown with fibroblasts, and subsequent collagen deposition leads to the formation of a permanent adhesion. Most of the drugs used have been clinically ineffective, and none has been specific to a particular extracellular matrix molecule. Therefore, there are serious concerns about the toxic consequences of interfering with the biosynthesis of other collagens, other matrix proteins, or vital collagen-like molecules. METHODS: Adhesions were induced by scraping the cecum until capillary bleeding occurred. The adhesions were scored 21 days later. Halofuginone was either injected intraperitoneally (1 microg/25 g body weight) every day, starting on the day of operation, or added orally at concentrations of 5 or 10 mg/kg, starting 4 days before the operation. Collagen alpha1(I) gene expression was evaluated by in situ hybridization, total collagen was estimated by Sirius red staining, and collagen type III was detected by immunohistochemistry. RESULTS: The adhesions formed between the intestinal walls were composed of collagen and were populated with cells expressing the collagen alpha1(I) gene. Regardless of the administration procedure, halofuginone significantly reduced the number and severity of the adhesions. Halofuginone prevented the increase in collagen alpha1(I) gene expression observed in the operated rats, thus reducing collagen content to the control level. In fibroblasts derived from abdominal adhesions, halofuginone induced dose-dependent inhibition of collagen alpha1(I) gene expression and collagen synthesis. Collagen type III levels were not altered by adhesion induction or by halofuginone treatment. CONCLUSIONS: Upregulation of collagen synthesis appears to have a critical role in the pathophysiology of postoperative adhesions. Halofuginone, an inhibitor of collagen type I synthesis, could be used as an important tool in understanding the role of collagen in adhesion formation, and it may become a novel and promising antifibrotic agent for preventing postoperative adhesion formation.

Abdomen↗

Responsiveness of human skin mast cells to repeated activation: an in vitro study.

To assess human mast-cell (MC) behavior after repetitive activation, we cocultured human foreskin MC (SMC) with human foreskin fibroblasts (F). Under these conditions, we have previously demonstrated that SMC keep their viability and functional activity for up to 8 days. SMC were presensitized with atopic serum and repeatedly activated by consecutively increasing concentrations of anti-IgE antibodies (alpha-IgE, 0.0002-0.1%). This treatment, which mimics the "rush desensitization" procedure, led to complete SMC unresponsiveness to activation by alpha-IgE at optimal concentrations, as evaluated by histamine release. However, presensitization of SMC with IgE antibodies before exposure to alpha-IgE restored their sensitivity to this stimulus. These data indicate that desensitization was probably due to lack of membrane-bound IgE rather than to downregulation of intracellular mechanisms. In fact, SMC challenged by an optimal concentration of alpha-IgE could release histamine upon a second activation by 2 h after the first activation, if the cells had been presensitized before the second challenge. SMC incubation with increasing concentrations of compound 48/80 (0.2-10 micrograms/ml) led to MC unresponsiveness to an optimal concentration of this stimulus. Furthermore, SMC activated by an optimal concentration of compound 48/80 and rechallenged with the same agent were insensitive to the second activation for at least 24 h. In summary, we have shown that it is possible to induce "desensitization" in SMC to both IgE-dependent and IgE-independent stimuli by incubating the cultures with consecutively increasing concentrations of the activator. SMC can release histamine when reactivated with alpha-IgE antibodies after presensitization by 2 h after the first challenge, while they reacquire their susceptibility to reactivation with compound 48/80 in only 2-3 days.

Antibodies, Anti-Idiotypic↗

Anti-apoptotic signals of granulocyte-macrophage colony-stimulating factor are transduced via Jak2 tyrosine kinase in eosinophils.

Cytokine-mediated inhibition of eosinophil apoptosis is a mechanism causing tissue eosinophilia. Previously published work suggested that activation of the Lyn-Ras-Raf-1-MAP kinase pathway is obligatory for prevention of eosinophil apoptosis by eosinophil hematopoietins. We demonstrate herein that activation of freshly isolated human blood eosinophils by granulocyte-macrophage colony-stimulating factor (GM-CSF) is associated with increased tyrosine phosphorylation of Jak2. The tyrosine kinase blocker, tyrphostin B42, prevented activation of Jak2 but not Lyn, suggesting that Jak2 is the specific target for tyrphostin B42 in eosinophils. In addition, since Lyn remained unaffected by tyrphostin B42, it is unlikely that Jak2 is required for Lyn activation in this model. To test whether tyrosine phosphorylation of Jak2 is linked to GM-CSF-mediated prolonged eosinophil survival, we determined the effect of tyrphostin B42 on eosinophil viability and apoptosis. Prevention of Jak2 activation by tyrphostin B42 was associated with the inability of GM-CSF to prevent eosinophil apoptosis. These data suggest that disruption of not only the Lyn-Ras-Raf-1-MAP kinase but also the Jak-STAT pathway blocks the ability of eosinophil survival factors to prevent apoptosis in eosinophils.

Apoptosis↗

Nedocromil sodium ameliorates skin manifestations in a murine model of chronic graft-versus-host disease.

Dermal fibrosis, loss of cutaneous appendages, and loss of subcutaneous fat are the main manifestations of chronic graft-versus-host disease (cGVHD) in mice. Mast cells (MC) may have a role in cGVHD. To investigate this point we have evaluated the effect of a MC stabilizer (nedocromil sodium) and a MC activator (compound 48/80) on skin manifestations in a murine model of cGVHD (B10.D2-->BALB/c). Mice were treated with nedocromil sodium (5 mg/day) or compound 48/80 (10 micrograms/day) from day -3 until day 15. Nedocromil ameliorated the skin features of cGVHD while compound 48/80 caused skin changes reminiscent of mild cGVHD in control mice. In addition nedocromil normalized peritoneal MC numbers and skin MC numbers and their activation state in the cGVHD mice. On the other hand compound 48/80 caused a complete disappearance of toluidine blue stainable peritoneal MC from cGVHD and control mice and decreased skin MC in controls. In summary, MC activation may play a negative role in the skin changes seen in cGVHD while MC stabilization ameliorates the skin manifestations of cGVHD and therefore may have a therapeutic benefit.

Animals↗

Mast cells, eosinophils and fibrosis.

We have presented results that increase our understanding of the roles MC and EOS play in modulating fibrotic processes. In vitro studies have provided clear-cut evidence for the direct involvement of these two inflammatory cells in enhancing proliferation, and either enhancing or decreasing collagen synthesis in human fibroblasts isolated from different anatomical locations. In addition, we have shown that MC and EOS interactions can also take part in modulating fibrosis. In vivo studies in murine and human cGVHD showed that MC activation is detrimental, and that MC stabilization therapy may be helpful in treating the fibrotic outcome of this disease. Much is still obscure. It is, for example, important to define the MC and EOS mediators involved in the modulation of fibroblast properties, and their pattern of influence, keeping in mind the ultimate goal of defining new therapeutic targets for the treatment of fibrotic diseases.

Animals↗

Regulation of the functional activity of mast cells and fibroblasts by mononuclear cells in murine and human chronic graft-vs.-host disease.

Mast cell (MC)-fibroblast-immunocompetent cell interactions may play a role in the inflammatory and fibrotic processes present in chronic graft-vs.-host disease (cGVHD). Interactions between these cell types were examined in both murine and human cGVHD models. To this purpose, cell supernatants from mice or humans with cGVHD and from controls were incubated for 6 days with either rat peritoneal MCs cocultured with 3T3 fibroblasts or with 3T3 fibroblasts alone. Supernatants in the murine model were of splenocytes from either mice with cGVHD or syngeneic controls (B-->B). Supernatants in the human model were of peripheral blood mononuclear cells (PBMC) from cGVHD patients. Two groups of controls were used in the human model-patients who had undergone bone marrow transplantation (BMT) without developing cGVHD and patients with hematological malignancies who had not undergone bone marrow transplantation (pre-BMT). Histamine release was measured in MC/fibroblast cocultures incubated with the cell supernatants. Prostaglandin E2 (PGE2) and [3H]-thymidine incorporation were measured in both MC/fibroblast cocultures or 3T3 fibroblasts alone, incubated with the cell supernatants. In the murine model, the cGVHD supernatant caused significantly more histamine release from MCs than the syngeneic supernatant or medium alone. Moreover, cGVHD and syngeneic supernatants, compared with medium alone, inhibited 3T3 fibroblast proliferation. PGE2 production by 3T3 fibroblasts was higher after incubation with the cGVHD supernatant than with the syngeneic supernatant or in medium alone. Incubation of fibroblasts with supernatants and indomethacin decreased PGE2 production and increased [3H]-thymidine incorporation. In humans, PBMC supernatants from cGVHD patients, as well as from BMT and pre-BMT controls, also displayed histamine releasing activity when cocultured with rat MCs. As with the murine cGVHD splenocyte supernatant, the human cGVHD supernatant decreased fibroblast [3H]-thymidine uptake, but the presence of MCs in the culture abrogated this inhibitory effect. In addition, the human cGVHD supernatant was found to contain high levels of PGE2 and interleukin-1 beta (IL-1 beta). The addition of neutralizing anti-IL-1 beta antibodies to the cGVHD supernatant partially inhibited its histamine-releasing activity. Skin biopsies of involved areas in cGVHD patients revealed significantly reduced numbers of MCs and showed signs of MC degranulation compared with biopsies from pre-BMT controls. Immunocompetent cell supernatants from both mice and humans with cGVHD increased basal histamine release by MCs and reduced fibroblast proliferation. The murine cGVHD supernatant also enhanced PGE2 production by 3T3 fibroblasts. Our findings indicate that complex interactions between immunocompetent cells, MCs, and fibroblasts probably play a role in cGVHD pathogenesis.

3T3 Cells↗

Inhibition of collagen type I synthesis by skin fibroblasts of graft versus host disease and scleroderma patients: effect of halofuginone.

The effect of halofuginone (a plant alkaloid) on collagen alpha 1(I) gene expression and collagen synthesis was evaluated in human skin fibroblasts from patients with chronic graft-versus-host disease (cGvHD) or scleroderma and from a normal individual. Halofuginone caused a dose-dependent inhibition in collagen alpha 1(I) gene expression and collagen synthesis in all cultures tested, the cGvHD fibroblasts being the least sensitive. In normal and scleroderma fibroblasts, concentrations of halofuginone as low as 10(-10) M and 10(-9) M were sufficient to cause a significant reduction in collagen alpha 1(I) gene expression and collagen synthesis, respectively. In addition, halofuginone also inhibited the transforming growth factor beta-induced collagen synthesis. Three days after halofuginone removal, collagen gene expression returned to control levels. The reduction of collagen mRNA transcript levels by halofuginone appeared to be dependent on new protein synthesis because simultaneous treatment of fibroblasts with protein synthesis inhibitors prevents the suppressive effect of halofuginone on collagen alpha 1(I) mRNA gene expression. The ability of extremely low concentrations of halofuginone to inhibit collagen alpha 1(I) synthesis specifically and transiently at the transcriptional level suggests that this material may be an important tool for studying collagen alpha 1(I) gene regulation and may be used as a novel and promising antifibrotic therapy.

Adult↗

The role of mast cell-derived histamine in the closure of an in vitro wound.

We have previously reported that mast cells (MC) stimulate 3T3 fibroblast migration and proliferation into an in vitro model of wound obtained by producing in a confluent 3T3 monolayer, a midline cut and by scraping the cells from half of the monolayer. The purpose of the present study was to determine the contribution of mast cell-derived histamine to this MC increasing effect. Histamine levels in supernatants of MC/ 3T3 cultures unactivated or activated with either compound 48/80 or anti-IgE antibodies (10 min) did not correlate to the degree of fibroblast migration and proliferation into the wound space (42 h). Various concentrations of histamine were added to 3T3 fibroblast monolayers in the absence of cocultured MC, and fibroblasts beyond the wound line were counted (42 h). Addition of 100 ng/ml histamine had the highest stimulating effect on fibroblast numbers. This effect was abrogated by the addition of cimetidine (an H-2 antagonist). Addition of cimetidine to unactivated MC/ 3T3 cultures did not affect the increasing activity of MC presence on the wounded monolayer, although it diminished the enhancing effect obtained after MC activation with compound 48/80. These results indicate that histamine is partially responsible for the mast cell enhancing effect on fibroblast migration and proliferation in an in vitro model of wound.

3T3 Cells↗

Interleukin-2 inhibits 3T3 fibroblast proliferation.

In order to clarify the role played by interleukin-2 (IL-2) in the regulation of fibroblast function, we investigated the effect of rat IL-2 and human recombinant IL-2 on 3T3 fibroblast proliferation and collagen synthesis. Fibroblasts were incubated with various concentrations of IL-2 for different periods of time. IL-2 was found to decrease in time- and dose-dependent manner the proliferation of 3T3 fibroblasts. This effect correlated with ability of IL-2 to enhance PGE2 production by 3T3 fibroblasts. When 3T3 fibroblasts were cocultured with rat peritoneal mast cells (MC), the growth-inhibiting effect of IL-2 was significantly less pronounced. Treatment of the cultures with IL-2 had no effect on collagen production by both 3T3 fibroblasts and fibroblasts cocultured with MC. In conclusion, in this study we provide evidence that IL-2, the key cytokine in T-cell growth and differentiation, can affect fibroblast functions.

3T3 Cells↗

Inhibition of collagen synthesis and changes in skin morphology in murine graft-versus-host disease and tight skin mice: effect of halofuginone.

The effect of halofuginone, a plant alkaloid known to inhibit collagen type I synthesis, on skin collagen content and skin morphology was evaluated in two in vivo models of scleroderma: the murine chronic graft-versus-host disease (cGvHD) and the tight skin mouse. Skin collagen was assessed by hydroxyproline levels in skin biopsies and by immunohistochemistry using anti-collagen type I antibodies. Daily intraperitoneal injections of halofuginone (1 microgram/mouse) for 52 d starting 3 d before spleen cell transplantation, abrogated the increase in skin collagen and prevented the thickening of the dermis and the loss of the subdermal fat, all of which are characteristic of the cGvHD mice. Halofuginone had a minimal effect on collagen content of the control mice. The halofuginone-dependent decrease in skin collagen content was concentration-dependent and was not accompanied by changes in body weight in either the cGvHD or the control mice. Injections of halofuginone (1 microgram/mouse) for 45 d caused a decrease in the collagen content and dermis width in tight skin mice, but did not affect the dermis width of control mice. Collagen content determination from skin biopsies confirmed the immunohistochemical results in the same mice. The low concentration of halofuginone needed to prevent collagen deposition in fibrotic skin without affecting body weight suggests that halofuginone may serve as a novel and promising anti-fibrotic therapy.

Animals↗

Inhibition of proliferation of psoriatic and healthy fibroblasts in cell culture by selected Dead-sea salts.

The effect of five selected minerals abundant in the Dead-sea brine was studied on proliferation of fibroblasts grown from psoriatic and healthy skin biopsy specimens in cell culture. The reason for carrying out this study was looking for the mechanism of the antiproliferative effect of selective Dead-sea minerals in improving the psoriatic condition. Psoriatic skin shave biopsy specimens (both from involved and uninvolved areas of the body) as well as healthy skin (obtained from amputated limbs) were incubated in tissue culture, and their outgrowing fibroblasts were used for this study. The number of cells and their cyclic AMP content were used as parameters for cell division and for proving the selective involvement of magnesium salts in the antiproliferative effect. It is shown that the inhibitory effects of magnesium bromide and magnesium chloride on cell growth were significantly stronger than those of their corresponding potassium salts or of sodium chloride. These results were obtained with both psoriatic and healthy skin fibroblasts, indicating that the inhibitory effect of the selected Dead-sea minerals is present in healthy and psoriatic skin cells.

Baths↗

Diethylene glycol monoethyl ether (Transcutol) displays antiproliferative properties alone and in combination with xanthines.

In the present study we have investigated the effects of diethylene glycol monoethyl ether (Transcutol) in combination with theophylline, caffeine and dyphylline and alone on 3T3 mouse fibroblast proliferation. These three xanthines (1-0.01 mM) inhibited fibroblast proliferation by themselves. Enhancement of the effect was detected by addition of 1 and 0.1 mM Transcutol. Transcutol alone also displayed a dose-dependent inhibition (2-0.01 mM) of both 3T3 and human normal and psoriatic fibroblasts, although normal human fibroblasts were the least sensitive to Transcutol antiproliferative activity. Transcutol was assessed for its antiproliferative effects on YAC lymphoma and P-815 mastocytoma human cell lines. Transcutol inhibited cell proliferation of both these cell lines, being more effective towards P-815 mastocytoma (at 2 mM it displayed 3.95-fold vs. 2.4-fold inhibition towards YAC lymphoma). In conclusion, we have shown that Transcutol has antiproliferative effects on 3T3 murine, human normal and psoriatic fibroblasts and tumour cell lines. In addition it enhances xanthine antiproliferative effects on 3T3 fibroblasts. Therefore it might be a useful topical drug alone or in combination with xanthines in the treatment of skin hyperproliferative disorders.

3T3 Cells↗

Identification of interleukin-2 in human peripheral blood eosinophils.

Interleukin-2 (IL-2) is an essential growth factor for T cells. Previous studies have shown that human peripheral eosinophils respond to IL-2 in chemotaxis and express the IL-2 receptor (CD25). In addition, eosinophils have been shown to transcribe messenger RNA for IL-2. The aim of the present study was to determine whether eosinophils translate mRNA for IL-2 and to determine the site of intracellular localization. By immunocytochemistry, an average of 9% of cells showed cytoplasmic staining for IL-2 in freshly isolated unstimulated blood eosinophils obtained from asthmatic subjects who were not receiving oral corticosteroid treatment (n = 5). Freshly isolated, disrupted, highly purified eosinophils (> 99%, by CD16- immunomagnetic selection) contained an average of 6 pg/10(6) cells of IL-2 measured by a specific enzyme linked immunosorbent assay (ELISA) (n = 7). Purified eosinophil incubated with serum-coated Sephadex beads showed an increase in the amount of intracellularly-retained IL-2 (26.2 +/- 7.2 pg/10(6) cells) with some evidence for release of this cytokine but only in three out of six eosinophil preparations (range 1.3-5.8 pg/10(6) cells). The intracellular localization of IL-2 was determined by fractionation of the cells on a linear (0-45%) Nycodenz gradient in sucrose buffer followed by detection of IL-2 in the fractions using an IL-2-specific ELISA and dot blotting. The majority of the IL-2 detected co-eluted with known eosinophil granule markers (i.e. major basic protein (MBP), eosinophil cationic protein (ECP), eosinophil peroxidase (EPO) and beta-hexosaminidase) but small quantities were also detected in the cytosolic (lactate dehydrogenase-(LDH) associated) and membrane (CD9+) fractions. Immunogold labelling of intact eosinophils using an anti-IL-2 monoclonal antibody confirmed IL-2 immunoreactivity in association with the eosinophil crystalline granule cores. These data are consistent with the hypothesis that eosinophils synthesize, release and store IL-2 largely within cystalloid granules. This stored IL-2 may serve as a reservoir for rapid release of IL-2 in inflammatory reactions associated with eosinophilia.

Asthma↗

Total leucoderma: a rare manifestation of cutaneous chronic graft-versus-host disease.

We describe a 14-year-old boy who developed total leucoderma during the course of chronic graft-versus-host disease, which developed after allogeneic bone marrow transplantation. Skin biopsy and dihydroxy-phenylalanine staining revealed a total absence of melanocytes from the epidermis. Cytotoxic anti-melanocyte antibodies were found in the patient's serum, and this probably explains the development of the leucoderma.

Adolescent↗

Association of granulocyte-macrophage colony-stimulating factor with the crystalloid granules of human eosinophils.

We have previously shown that normal-density human peripheral blood eosinophils transcribe and translate mRNA for granulocyte-macrophage colony-stimulating factor (GM-CSF) and that the intracellular distribution was granular as assessed by light microscopy immunocytochemistry. The present study was conducted to confirm this apparent association between GM-CSF and the crystalloid granule using a subcellular fractionation method for human eosinophils and immunogold electron microscopy (EM). Highly purified (> 99%, by negative selection using anti-CD16 immunomagnetic microbeads) human peripheral blood eosinophils were obtained from four asthmatic subjects (not taking systemic medication), homogenized and density fractionated (5 x 10(7) cells/subject) on linear Nycodenz gradients. Twenty-four fractions were collected from each cell preparation and analyzed for marker enzyme activities as well as total protein. Dot blot analysis with specific monoclonal antibodies (MoAbs) was used to detect the eosinophil granule proteins major basic protein (MBP) and eosinophil cationic protein (ECP). An anti-CD9 MoAb was used as an eosinophil plasma membrane marker. Lactate dehydrogenase (LDH) was used as a cytosolic marker. Immunoreactivity for GM-CSF was detected by a specific enzyme-linked immunosorbent assay using a polyclonal antihuman GM-CSF antibody and confirmed by dot blot. GM-CSF coeluted with the cellular fractions containing granule markers (MBP, ECP, eosinophil peroxidase, hexosaminidase, and arylsulphatase), but not those containing cytoplasm (LDH+) or membrane (CD9+) markers. EM examination of pooled fractions associated with the peak of GM-CSF immunoreactivity confirmed that they contained crystalloid and small granules, but not plasma membrane. In addition, quantification, using immunogold labeling with an anti/GM-CSF MoAb, indicated preferential localization of gold particles over the eosinophil granule cores of intact cells. Thus, our results indicate that GM-CSF resides as a granule-associated, stored mediator in unstimulated human eosinophils.

Asthma↗

Human foreskin mast cell viability and functional activity is maintained ex vivo by coculture with fibroblasts.

The aim of the present study was to develop long-term culture conditions for foreskin-derived mast cells (HSMC) as we have previously done for rodent peritoneal mast cells (MC) and human lung-derived MC. HSMC were obtained by proteolytic treatment of foreskins from 8-day-old babies (4.8 +/- 2.0% purity) and seeded onto a confluent monolayer of human foreskin-derived fibroblasts (HF) in enriched culture medium. HSMC biochemical and functional properties were studied up to 8 days in these cocultures. Twenty-four hours after seeding the cell suspensions from the proteolytic-digested foreskins, all the cells which did not adhere to the HF were washed out. At this time point approximately 30% of the seeded HSMC were found to adhere to the HF monolayer. The only contaminating cells were endothelial cells (< 8%). Cocultured HSMC maintained their normal resting morphology and histamine content (3.1 +/- 0.7 pg/cell) up to 8 days in these cocultures. When challenged with compound 48/80 on Days 1, 2, 4, and 8 of coculture, HSMC released similar percentages of histamine which were comparable to the one released by freshly isolated HSMC in suspension (approximately 30%). Similarly, HSMC, sensitized with IgE antibodies and challenged at various time of coculture with anti-IgE antibodies, released throughout the experiment comparable percentages of this mediator (approximately 50%). Thus, coculture of HSMC with HF fibroblasts provides a suitable in vitro system for long-term studies on HSMC functional and biochemical properties in a microenvironment which mimics the physiologic one.

Cell Survival↗

Prostaglandin E2 production by chronic graft-versus-host disease dermal fibroblasts.

Chronic graft versus host disease (cGVHD) across minor histocompatibility barriers is associated with the development of cutaneous fibrosis, disappearance of mast cells and immunosuppression. The idea, which has been the basis of our previous and present studies, is that fibroblasts are not only a target for modulation in cGVHD, but also have effector roles in this condition. In the present study we investigated the production of prostaglandin E2 (PGE2) and of collagen by cultured dermal fibroblasts obtained from cGVHD and control mice. Early in the development of the disease (Day 8) cGVHD fibroblasts generated constitutively more PGE2 (3-fold) than did control fibroblasts. Thereafter, PGE2 production declined to near normal levels by Day 20 post cGVHD induction. On the other hand, at this time point cGVHD fibroblasts displayed an enhanced synthesis of collagen as compared to the control fibroblasts and to earlier time points. Therefore, PGE2 synthesis appears to inversely correlate with collagen synthesis by cGVHD fibroblasts. We propose that fibroblasts may contribute to the development of immunosuppression, which characterizes the early phase of cGVHD.

Animals↗