Biomedical subjects

A Gilhar

Publications and source records attributed to A Gilhar.

At least 37 records · Page 2Linked to original sources

PubMed1995

Dopa reaction of fetal melanocytes before and after skin transplantation on to nude mice.

We have previously demonstrated that human fetal epidermal melanocytes are dopa-negative. The present study was conducted to test the hypothesis that human fetal melanocytes can be activated to produce melanin under conditions differing from their natural in utero environment. To address this question, dopa staining activity of fetal epidermal sheets, obtained from seven aborted fetuses with estimated gestational ages of 13-20 weeks, was evaluated before and after engraftment on to nude mice. Dopa staining became positive 7 days post-engraftment. The intensity of the dopa reaction and the mean number of melanocytes increased by day 14 post-engraftment, and these changes were even greater by day 30. These observations indicate that human fetal melanocytes, potentially capable of synthesizing melanin under conditions differing from their normal in utero environment, are either inhibited, or not stimulated to do so.

Adult↗

PubMed1995

Effect of donor age on response of skin grafts to gamma-interferon.

BACKGROUND: Failure of aged human epidermis to induce HLA-DR antigens after intradermal administration of gamma-interferon (IFN-gamma) has recently been observed. OBJECTIVE: The purpose of the study was to find out whether this observation reflects an intrinsic impairment in the aged skin or is rather due to an environmental factor. METHODS: Aged and young human skin grafted onto nude mice were injected with IFN-gamma, and the induction of HLA-DR, intercellular adhesion molecule-1 (ICAM-1) and Langerhans cell (LC) migration patterns were studied. RESULTS: Increased surface expression of both HLA-DR and ICAM-1 molecules by epidermal cells was observed in all grafts, after IFN-gamma injections, whereas a decrease in LC was found only in the young grafts. CONCLUSION: This study may indicate that the lack of response of aged skin to IFN-gamma is due to both intrinsic impairment in epidermal cell function and changes in function of cells outside the epidermis such as lymphocytes and endothelial cells.

Adult↗

PubMed1995

Possible role of cytokines in cellular proliferation of the skin transplanted onto nude mice.

BACKGROUND AND DESIGN: In recent studies on the behavior of aged skin transplanted onto nude mice, the epidermis of aged and young skin showed an increase in proliferation and thickness following engraftment, and became almost identical. The aim of this study was to ascertain a possible role for the release of local cytokines in this phenomenon. Grafted human skin was injected intradermally with anti-interleukin-6 (IL) and anti-IL-1 alpha, and comparisons of epidermal thymidine incorporation and thickness were made. Grafts injected with irrelevant antibodies served as control. RESULTS: Interleukin-6 and IL-1 alpha expression were studied in grafts by immunoperoxidase staining. Only IL-6 expression was found in the 1-month grafts. Intradermal injections of anti-IL-1 alpha and anti-IL-6 showed an inhibitory effect on cellular proliferation in the epidermis. A significant difference in the response of epidermal proliferation and, consequently, in thickness was found in samples injected with anti-IL-1 alpha and anti-IL-6 compared with those injected with irrelevant antibodies. CONCLUSIONS: These data may indicate that local cytokines released by the keratinocytes are involved in the cellular proliferative activity in skin engrafted onto the mice.

Aged↗

PubMed1994

The nude mouse model for the study of human skin disorders.

Normal human skin grafted onto the nude mouse can be maintained without any signs of rejection throughout the life-span of the animal. Indeed, the nude mouse model is a powerful tool for understanding the pathological process of the skin. Until now many skin diseases such as psoriasis, cutaneous lupus, pemphigus and vitiligo have been looked at using the nude mouse model, which has helped to clarify the role of the various factors involved.

Animals↗

PubMed1994

Effect of antiinsulin-like growth factor 1 on epidermal proliferation of human skin transplanted onto nude mice treated with growth hormone.

Recently it has been demonstrated that long-term administration of GH leads to increase of skin thickness. The aim of the present study was to determine whether this effect of GH is mediated by insulin growth factor 1 (IGF-1), which enhances epidermal proliferation. In order to address this question, human split-thickness grafts obtained from aged skin were grafted onto nude mice. One group of mice was treated systemically with GH, whereas a second group was treated with intradermal graft injections of anti-IGF-1 in addition to GH. A third group received distilled water and served as a control group. Histological and autoradiographic analyses were performed before and after engraftment. The GH-treated mice showed a significant increase in epidermal proliferation measured by epidermal thickness (analysis of variance with repeated measurements, P < 0.01) and labeled index (analysis of variance, P < 0.01) as compared to the control group. The intradermal injections of anti-IGF-1 reduced significantly the proliferative stimulatory effect of GH (P < 0.01). The present study emphasizes the role of IGF-1 in the increased skin thickness observed after GH administration and provides a useful model for determining the effect of various compounds, including GH, on human skin.

Aged↗

PubMed1994

HLA-DR positive epidermal Langerhans' cells in liver cirrhosis and immunosuppressed liver transplanted patients.

The aim of the present study was to evaluate the number of Langerhans' cells (LC) in immunosuppressed liver transplanted patients, compared to patients with liver cirrhosis and healthy volunteers. The detection of LC was performed in the epidermal sheet of each patient by using indirect immunoperoxidase and ATPase staining. A significant reduction in the number of LC was found in the liver transplanted patients as compared to patients with liver cirrhosis and healthy volunteers. This reduction may be related to prolonged treatment with corticosteroids and azathioprine.

Adult↗

PubMed1993

Response of grafts from patients with alopecia areata transplanted onto nude mice, to administration of interferon-gamma.

A variety of evidence has pointed to immunological involvement in the pathogenesis of alopecia areata (AA). The aim of the present study was to determine whether differential expression of HLA-DR and intracellular adhesion molecules-1 (ICAM-1) occurs in hair structures of patients with longstanding AA, following stimulation with interferon-gamma (IFN-gamma). IFN-gamma was injected i.v. to nude mice grafted with transplants obtained from affected areas of seven patients and of normal individuals. All mice were injected with IFN-gamma or phosphate-buffered saline (PBS) alone for 3 consecutive days. Immunohistochemical studies were performed in specimens of grafts in order to detect the change in adhesion molecules, HLA-DR antigen, and Langerhans cells. ICAM-1 and HLA-DR induction was found to be similar in grafts from AA patients and normal skin grafts in the IFN-gamma injected mice. However, more intraepithelial Langerhans cells were observed in the AA patients' grafts treated with IFN-gamma than in those treated with PBS and in normal grafts treated with IFN-gamma. This study suggests an important role of Langerhans cells in this issue.

Adult↗

PubMed1993

Vitiliginous vs pigmented skin response to intradermal administration of interferon gamma.

BACKGROUND AND DESIGN: Decreased sensitization and elicitation of contact allergens in vitiliginous skin has been described. This may be related to altered epidermal Langerhans cell migration with bound hapten to dermis and draining lymph nodes. The aim of the present study was to detect the potential ability of vitiliginous skin to respond to an in vivo immunologic stimulus such as intradermal injections of interferon gamma (IFN-gamma). Vitiliginous and normal pigmented skin of each patient was injected intradermally with 10 micrograms of recombinant IFN-gamma diluted in 0.1 mL of sterile water for 3 consecutive days. On day 5, punch biopsy specimens were obtained from the injected sites. Histologic and immunohistochemical staining was performed on all sections. The cryostat sections were stained with adenosine triphosphatase as well as with the indirect immunoperoxidase technique employing murine monoclonal antibodies to HLA-DR, ICAM-1, CD1, CD11a, and CD18. RESULTS: HLA-DR and ICAM-1 expression by epidermal cells, combined with perivascular accumulation of mononuclear cells with CD11a and CD18 expression, was observed in all sites injected with IFN-gamma. However, absence of an effect on the epidermal Langerhans cell population was noted only on the vitiliginous skin. CONCLUSION: The reactivity of depigmented and pigmented skin was found to be different after IFN-gamma administration, with fewer CD1-positive cells in the depigmented skin. As adenosine triphosphatase staining also showed fewer positive cells, it may be concluded that no effect on the migration of epidermal Langerhans cells was noted in the involved skin. This may shed light on the immunologic aberration seen in vitiliginous skin.

Adenosine Triphosphatases↗

PubMed1993

Enhanced degradation of high density lipoprotein by peritoneal macrophages from nude mice is attenuated by interleukin-1.

Athymic nude mice are characterized by deficient cellular immunity due to almost complete absence of functional mature T-lymphocytes. Plasma HDL (the major cholesterol carrier in mice) cholesterol levels in nude mice were found to be reduced by 1.7 fold in comparison to control Balb/c mice. Cellular degradation of HDL by peritoneal macrophages (MPM) that were obtained from nude mice, was 2.5 fold greater in comparison to MPM obtained from Balb/c mice. Since nude mice lack cytokines that can affect lipid metabolism, intravenous administration of 10 micrograms/100g body weight of interleukin-1 (IL-1), tumor necrosis factor (TNF), or transforming growth factor (TGF) on HDL degradation by their PM, were investigated. IL-1 (but not TNF) reduced HDL (50 micrograms of protein/ml) cellular degradation from 810 +/- 34 to 350 +/- 12 ng/mg cell protein (p < 0.01) in nude mice. In control Balb/c mice, however, IL-1 as well as TNF enhanced macrophage degradation of HDL by 56% and 280%, respectively. TGF injection into nude mice (but not control mice) decreased HDL degradation by their MPM by 50%. We, thus, suggest that in nude mice the reduced plasma and HDL cholesterol levels are probably due to increased HDL degradation, which may be secondary to IL-1 and TGF deficiency.

Animals↗

PubMed1993

The role of cyclosporine on Ia antigen expression on gut epithelium in nude mice.

Increased expression of class II antigens (HLA-DR, human:Ia murine) on epithelial cells (EC) such as keratinocytes and gut EC suggests a role of the epithelium in the inflammatory response. It has been shown that injection of normal mouse serum (NMS) into nude mice caused an induction of Ia antigen by keratinocytes of the nude mice. The aim of the present study was to determine whether such induction could be observed in gut EC and whether it can be inhibited by cyclosporine A (CyA). Forty nude mice were divided into 4 groups of 10 each, designated A-D. Group A was injected with 0.1 ml of NMS; groups B and C were also injected with NMS and treated with oral CyA for 10 days. The dosage in group B was 30 g/ml and in group C 60 g/ml of drinking water. Group D was injected with serum of nude mice and served as a control group. Biopsies of small intestine and colon were obtained from each mouse and analyzed by indirect immunoperoxidase to identify Ia expression. Small intestine and colon EC were induced to express Ia antigen in most of the mice in groups A and B. A striking reduction in Ia expression was noted in group C. The differences between groups A and C concerning Ia expression on small intestine and colon EC were statistically significant. Our results demonstrate that the nude mouse may serve as a model for the study of Ia expression on gut EC, and that CyA can suppress the expression of Ia antigen also in the gut.

Animals↗

PubMed1992

Response of aged versus young skin to intradermal administration of interferon gamma.

BACKGROUND: Interferon gamma (IFN-gamma) induces the interaction of intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen type 1 expression, and of HLA-DR antigens by keratinocytes. OBJECTIVE: The aim of the present study was to determine the potential ability of aged versus young skin to respond to intradermal administration of IFN-gamma, as an in vivo immunologic stimulus. METHODS: For 3 consecutive days elderly and young volunteers were injected with 10 micrograms of recombinant IFN-gamma diluted in 0.1 ml of sterile water. On day 5, punch biopsy specimens were obtained from the injected sites. Histologic and immunohistochemical stainings were performed on all sections. RESULTS: ICAM-1 was expressed by keratinocytes in both aged and young skin. An impairment was manifested mainly by the reduced accumulation of mononuclear cells throughout the dermis, the absence of HLA-DR expression by keratinocytes in 7 of 10 elderly volunteers, and the absence of an effect on the Langerhans cell population. CONCLUSION: This observation shows a diminished immune response in aged skin.

Adult↗

PubMed1992

Failure of passive transfer of serum from patients with alopecia areata and alopecia universalis to inhibit hair growth in transplants of human scalp skin grafted on to nude mice.

We have previously demonstrated regrowth of hair in scalp skin grafts taken from patients with alopecia areata (AA) and alopecia universalis (AU) following engraftment on to nude mice. This present study was to determine whether serum from patients with AA and AU, has a role in the process of hair loss and the role of antibodies and complement. Forty mice were grafted with transplants obtained from seven patients. One group of the grafted mice was given patients' serum and another group normal serum. The mice were treated topically with cyclosporin (CyA), or olive oil. Hair growth was noted in most grafts and intravenous injections of serum did not prevent or inhibit this process. Immunofluorescence studies before grafting showed deposition of immunoglobulins and complement in hair follicles in both normal and affected scalp skin, but a more striking deposition was noted in the affected skin. Deposition of immunoreactants after grafting was observed only after the injection of serum from the patients but not with normal serum. Thus the sera from patients with AA or AU, when injected into nude mice with hair transplants from the scalp skin of patients with these disorders, does not alter the hair growth despite deposition of immunoreactants around the hair follicles.

Alopecia↗

PubMed1992

Ia expression in keratinocytes following ultraviolet radiation.

Injections of murine gamma interferon (IFN-gamma) into BALB/c nude mice induced Ia expression by keratinocytes. The aim of the present study was to use this murine model to determine the effect of ultraviolet radiation (UV) or cyclosporine A (CyA) on Ia expression by keratinocytes. Two sets of experiments were performed. In the first, mice were injected intraperitoneally with IFN-gamma for 6 days. The mice were divided into three groups. One group, with one ear protected by electrical tape, was exposed to UVB radiation for 15 days starting 4 days before the injection. The second group received subcutaneous injections of CyA simultaneously with the IFN-gamma and during the 10 days following the IFN-gamma injection. The third group received only IFN-gamma injections. Fifteen days after the IFN-gamma injection all mice were killed and evaluations of Ia positive cells were performed. In the second set of experiments the nude mice were treated with CyA or UVB only 10 days after the last IFN-gamma injections. In both experiments UVB inhibited and down-regulated Ia expression by keratinocytes. This effect on keratinocytes was not observed in the protected ears. Thus it appears that the effect of UVB on keratinocytes is local and not systemic. CyA failed to inhibit or down-regulate Ia expression. This study may shed some light on understanding the mechanism effect of UV radiation in a variety of skin diseases.

Animals↗

PubMed1991

Effect of cyclosporine A on the regulation of Ia antigen keratinocytes expression.

Since many skin diseases characterized by positive Ia keratinocytes show improvement with cyclosporine therapy, the purpose of this study was to determine whether cyclosporine A (CyA) alters the expression of Ia keratinocytes. Nude mice were injected with normal mouse serum (NMS) to induce keratinocyte expression of the Ia antigen. The injected mice were then divided into four groups: one was treated with oral CyA; the second was treated topically with CyA twice a day; the third was treated topically with olive oil; and the fourth was injected with nude mouse serum. The third and fourth groups served as Ia positive and Ia negative controls, respectively. The mice were treated during the first 10 days after the injections. On Day 10, epidermal sheets were analyzed for Ia expression. Analysis was made by an indirect immunoperoxidase staining method using monoclonal antibodies specific for Ia determinants. Quantitation of the number of Langerhans cells was analyzed on epidermal sheets using immunodiagnostic reagents, anti-MHC-Ia, and surface ectoenzyme, ATPase. A significant reduction of Ia-positive keratinocytes was noted in the oral CyA group vs topical and olive oil groups (64.9 +/- 29.9% vs 20.1 +/- 18.7%, respectively, P less than 0.01). In a second set of experiments mice were injected with NMS, but treatment was started only on Day 10 after injections, for 10 days. The results showed that CyA failed to down-regulate Ia expression. Topical and systemic CyA did not modify Langerhans cell population. The present study showed that systemic administration of CyA significantly reduced Ia induction by keratinocytes of nude mice that were injected with NMS.

Animals↗

PubMed1991

Dopa reaction test in hair bulbs of fetuses and its application to the prenatal diagnosis of albinism.

No information is available on the amount of tyrosinase normally present in fetuses. A dopa reaction test in hair bulbs from the scalp of normal fetuses obtained after abortion showed that tyrosinase is present in fetuses as early as 17 weeks. Only faint activity was detected in skin specimens other than from the scalp. This assay can serve as a quick and reliable method for the prenatal diagnosis of tyrosinase-negative albinism.

Albinism, Oculocutaneous↗

PubMed1991

Melanocytes and Langerhans cells in aged versus young skin before and after transplantation onto nude mice.

Previous studies have demonstrated decreased numbers of melanocytes and Langerhans cells (LC) in aged skin. In the present study, we employed dopa and indirect immunoperoxidase techniques in epidermal sheets to determine the fate of melanocytes and LC of aged versus young donors after skin transplantations onto nude mice. The detection of positive homologous leucocytic antibody reaction of degeneration (HLA-DR) of LC indicates an age-associated reduction in sun-protected thigh skin in aged versus young subjects (263 +/- 63 versus 589.25 +/- 142.643, p less than 0.001). The mean number of LC four weeks after transplantation remained almost constant. Prior to skin engraftment, a decreased number of melanocytes was found in aged versus young epidermis (160.77 +/- 51.7 versus 255.83 +/- 81.2, respectively, p less than 0.05). A significantly increased number of melanocytes was noted four weeks following engraftment in epidermis from aged (307.44 +/- 174, p less than 0.05) and young human donors (402.16 +/- 139, p less than 0.02). The marked increase in density of dopa-positive melanocytes following engraftment onto nude mice may indicate the existence of circulating factors in nude mice that perhaps both stimulates and enhances proliferation and activity of these cells.

Adult↗

PubMed1991

Aged versus young skin before and after transplantation onto nude mice.

The behaviour of aged skin transplanted onto nude mice was investigated to determine whether the skin maintains its histological features. Split-thickness skin grafts obtained from the unexposed skin on the thighs of healthy aged and young volunteers were grafted onto nude mice. A significant difference between the mean thickness of young versus aged epidermis was noted before transplantation (P less than 0.001). The epidermis of aged and young skin showed an increase in thickness following engraftment with a mean increase in epidermal thickness of 18.8% in the young (P less than 0.01) and 142.5% in aged skin (P less than 0.001). The number of blood vessels in the aged skin was significantly lower than in the young skin, but a remarkable increase was found post-transplantation. These findings indicate that part of the typical histological changes of unexposed aged skin are reversible.

Adult↗

PubMed1991

Topical cyclosporin induces hair growth in human split skin grafted onto nude mice.

Previously we observed that systemic CyA induces hair growth in an experimental model of human scalp skin graft transplanted onto nude mice. In the present study we investigated the role of topical CyA in the murine transplantation model, using human split-thickness skin grafts (HSTSG). Ten mice grafted with 1-mm-thick skin and another 10 mice grafted with 0.4-mm-thick skin were treated topically with CyA in olive oil. Ten other mice, treated with olive oil only, served as a control group. At the end of the study we observed hair growth only on the grafted skin of the CyA-treated group. Four out of 10 grafts showed hair growth in each of the groups. Quantitative analysis of transverse sections of cylindrical punch biopsy specimens of HSTSG before transplantation revealed anagen follicles, including small ones and telogen/catagen follicles, whereas specimens after skin transplantation showed terminal follicles mostly in the anagen phase. The present study provides further support to previous observations regarding the beneficial effect of CyA on hair growth.

Administration, Topical↗