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J Viac

Publications and source records attributed to J Viac.

At least 37 records · Page 2Linked to original sources
PubMed1997

Effect of UVB 311 nm irradiation on normal human skin.

Ultraviolet radiation B (UVB) on the skin induces erythema, inflammation and modifications of the immune system. These changes have been reported after excessive short-term or long-term exposure to broad spectrum UVB. In this study, we examined the effects of local repetitive UVB irradiation of 311 nm wavelength on the skin of seven young volunteers. Skin biopsies were taken before and after UVB irradiation, and we immunohistochemically analyzed the expression of CD1a and HLA-DR antigens of Langerhans cells (LC), the possible infiltration of dermis/epidermis by CD11b macrophages, the modifications or the induction of intercellular adhesion molecule-1 (ICAM-1), E-selectin and vascular cell adhesion molecule-1 (VCAM-1) involved in the binding of leukocytes to the endothelial surface and the development of perivascular infiltrates of LFA-1+ mononuclear cells. We also determined the expression of substance P receptors (SPR) using biotinylated substance P (SPB). Exposure of UVB 311 nm induced a drastic reduction of CD1a+ cells and a moderate increase of HLA-DR+ dendritic cells in the epidermis without infiltration by CD11b macrophages. An increase of the binding of SPB to upper layer epidermal cells was noted in five of seven biopsies. In the dermis, vessel-associated ICAM-1 expression increased and an induction of E-selectin occurred on nearly 20 to 40% of endothelial cells, but VCAM-1 expression remained undetectable. The percentage of LFA-1+ cells did not change significantly after irradiation. These observations may be compatible with a selective role of UVB 311 nm on the skin immune response.

Adult↗
PubMed1996

Substance P and keratinocyte activation markers: an in vitro approach.

Substance P (SP) released by cutaneous C fibres is involved in the physiopathology of cutaneous lesions. As normal human keratinocytes have been reported to express SP receptors, we studied the effects of SP on keratinocyte activation markers such as ICAM-1 induction and cytokine production. Human keratinocytes derived from skin obtained during plastic surgery were cultured in defined medium (MCDB 153) and were stimulated by SP. Flow cytometry analysis showed that SP (10(-7) and 10(-5) M) as well as the specific NK1 agonist Sar9Met(O2)11SP (Sar Met) induced a slight but significant expression of ICAM-1 at the cell surface during treatment periods of 24 h and 48 h. SP (10(-5) M) also induced a significant but transient increase in the production of IL-1alpha, IL-1beta, IL-1 receptor antagonist and IL-8 which was detectable by ELISA techniques 6 h after stimulation. This elevation returned to constitutive levels 24 or 48 h postinduction. TNFalpha secretion was detected in stimulated cells only after 48 h. These results suggest that SP can activate keratinocytes and support its role in the local inflammatory reaction.

Adolescent↗
PubMed1996

Glucocorticoid receptor localization in human epidermal cells.

Glucocorticoids, which are widely used in therapy, exert their immunosuppressive actions through specific receptors. These receptors have been characterized in cultured human skin fibroblasts and keratinocytes, but their localization in vitro and in vivo has not been established. To determine the tissue and cellular distribution of glucocorticoid receptors (GR), two specific polyclonal rabbit anti-human GR antibodies were used to detect these receptors in skin biopsy specimens, in freshly isolated and cultured human epidermal cells and in keratinocyte cell lines. Immunoreactive GR were only faintly detected in normal and abnormal differentiated cells and as well as those in the stratum granulosum and corneocytes. These immunolocalization studies were confirmed by fluorescence cell sorter analysis of isolated basal and suprabasal keratinocytes. Immunoreactive GR were highly expressed in normal cultured human keratinocytes, Langerhans cells and several cell lines whereas they were less expressed in melanocytes. Based upon these results the main targets of glucocorticoids in the epidermis appear to be basal and Langerhans cells.

Animals↗
PubMed1996

Tumour necrosis factor (TNF) soluble receptors in malignant melanoma: correlation with soluble ICAM-1 levels.

It has been recently suggested that soluble tumour necrosis factor receptors (sTNF-Rs) may represent prognostic factors in cancer. In malignant melanoma, the intercellular adhesion molecule (ICAM-1) has been described as involved in progression of the disease and is upregulated by TNF alpha. We report in this study the serum concentrations of sTNF-R1 and sTNF-R2 in 32 patients with primary melanoma and in 21 patients with metastatic melanoma, in correlation with those of soluble ICAM-1 (sICAM-1). Significantly raised sTNF-R1 levels were detected only in patients with metastatic melanoma compared with normal controls (P < 0.002), whereas sTNF-R2 levels were increased both in primary and metastatic melanoma (P < 0.001). The ratio of type 2 to type 1 proteins increased in malignant melanoma compared with the controls but remained constant with the progression of the disease. A correlation between sTNF-Rs and sICAM-1 concentrations in patients' sera was observed in metastatic melanoma. The combined adverse effects of these soluble proteins on normal immune effector functions may contribute to tumour progression.

Adult↗
PubMed1995

Protective effect of zinc on keratinocyte activation markers induced by interferon or nickel.

Zinc therapies exert beneficial effects in several cutaneous pathologies through their antiinflammatory properties, but target cells and mechanisms of action are still uncertain. We wondered whether markers of the keratinocyte activation state, such as the expression of immune surface antigens (ICAM-1 and HLA-DR) and the production of TNF-alpha, frequently detected in inflammatory reactions, may be reduced by zinc. For this purpose, we used normal human keratinocytes derived from plastic skin surgery and cultured in low-calcium medium (MCDB153). We studied the effects of ZnSO4 (12.5 to 50 microM) alone or in combination with IFN-gamma (5 U/ml), a mediator of inflammation produced by activated T-cells, or nickel (5-10 micrograms/ml), a sensitizing metal hapten. Using FACS analysis, we showed that the combination of zinc with nickel or the addition of ZnSO4 24 h before IFN-gamma or NiSO4 treatments reduced ICAM-1 expression on the keratinocyte surface (p < 0.01). However, zinc did not modify the IFN-gamma induced expression of HLA class II antigen on keratinocytes. Zn2+ could also reduce the TNF-alpha secretion of keratinocytes stimulated by IFN-gamma or Ni2+ during 48 h. Taken together, these data indicate that zinc can directly reduce some keratinocyte activation markers frequently observed in vivo; this action may be involved in the antiinflammatory effect of Zn(2+)-associated therapies in cutaneous inflammatory reactions.

Antigens, Surface↗
PubMed1994

Effect of various metals on intercellular adhesion molecule-1 expression and tumour necrosis factor alpha production by normal human keratinocytes.

Nickel, cobalt and chromium are metals very often implicated in allergic contact dermatitis. In vivo, keratinocytes, which are the first target cells, can be directly activated to participate in the local reaction, especially through the expression of the membrane antigen ICAM-1, a ligand of the leucocyte antigen LFA-1, and the production of cytokines. Our aim was to assess the effects of sensitizing metal haptens (nickel, cobalt and chromium) compared with the toxic metal cadmium on the induction of ICAM-1 and the production of TNF alpha by epidermal cells. For this purpose, normal human keratinocytes obtained during plastic skin surgery were cultured in low-calcium defined medium (MCDB153) and the metals were used in non-toxic concentrations. Using FACS analysis, ICAM-1 expression was found to be induced only by nickel. This stimulation appeared as early as 24 h after stimulation. All the metals induced a low expression of TNF alpha detectable by immunocytochemistry correlating with the induction of the nuclear stress protein Hsp72 which is closely linked genetically with the TNF alpha locus. However, only Ni2+, Co2+ and Cr2+ induced a significant release of TNF alpha detectable by ELISA after 48 h stimulation. This secretion was lower than that observed with known stimulants such as lipopolysaccharide. These results indicate that the metals studied are able to induce an aggressive cellular effect, and that nickel, by its ICAM-1 induction, may play a major role in the keratinocyte activation state during allergic contact dermatitis.

Cells, Cultured↗
PubMed1994

Expression of annexin I in freshly isolated human epidermal cells and in cultured keratinocytes.

Annexin I belongs to a newly characterized family of intracellular proteins involved in the regulation of the production of inflammatory lipid mediators such as prostaglandins and leucotrienes. Annexin I (named p35, lipocortin I or calpactin II) was initially described as a protein inducible by glucocorticoids. In the skin, the role of annexins has still not been elucidated. In the study reported here we investigated the expression of annexin I both in freshly isolated epidermal cells and in cultured keratinocytes using immunofluorescence, FACS analysis and immunoblotting techniques. Using epidermal cells freshly isolated from normal skin, annexin I was detected by double immunostaining mainly in basal and suprabasal keratinocytes. Langerhans cells isolated from Ficoll gradient were faintly stained compared with keratinocytes. Annexin I was also highly expressed in keratinocytes maintained in culture in a serum-free medium without hydrocortisone. By confocal microscopy, annexin I was shown to be mainly localized in the cytoplasm of the cells. The protein was characterized by Western blot and immunoprecipitation as a 35-kDa protein in freshly isolated epidermal cells and cultured keratinocytes. Results from in vivo studies confirmed the presence of annexin I in the basal and suprabasal layers of normal human skin with modified reactivity patterns in hyperproliferative lesions.

Annexin A1↗
PubMed1994

Effects of cytokines on the gamma interferon-induced tryptophanyl-tRNA synthetase expression by human keratinocytes.

Incubation of human keratinocytes with gamma interferon (gamma-IFN) has been shown to potently induce the synthesis of a 53 kDa protein which was recently identified as tryptophanyl-tRNA synthetase (TRS). However, in spite of the high sensitivity of cultured keratinocytes to TRS induction by gamma-IFN, the study of inflammatory skin lesions has allowed the detection of the protein only in a few cases, suggesting regulatory mechanisms from soluble endogenous mediators with antagonistic activity on the induction of TRS by gamma-IFN. Among these mediators, we wondered whether cytokines selected for possible anti-inflammatory activity and potentially derived from activated resident skin cells, such as IL-4, IL-10, TNF-alpha and TGF-beta, may be involved in the modulation of the keratinocyte TRS expression. To assess this possibility, we investigated the modulation of the synthesis of TRS by human cultured keratinocytes upon stimulation by various gamma-IFN/cytokine combinations. The effects were evaluated by immunoblotting assay revealed by enhanced chemiluminescence, with the aid of a specific antibody to the TRS protein. Results failed to demonstrate any effect of the tested cytokines, whether on the basal level of the TRS, or on the gamma-IFN-induced enzyme expression in keratinocytes. It is thus unlikely that such cytokines can account for the infrequency of the TRS detection in inflammatory skin processes. Further investigations of alternative working hypothesis should help elucidate the regulation of TRS in human keratinocytes.

Cells, Cultured↗
PubMed1994

Effect of nickel on the activation state of normal human keratinocytes through interleukin 1 and intercellular adhesion molecule 1 expression.

Patch tests with nickel on sensitive subjects induce a characteristic allergic reaction involving epidermal and dermal cells, as well as modulation of cytokines and adhesion molecule production. In order to gain further insight into the role of keratinocytes in this phenomenon, we assessed their activation state induced by Ni2+ by studying interleukin 1 (IL-1) production and intercellular adhesion molecule 1 (ICAM-1) expression, using normal human keratinocytes cultured in defined medium. In comparison with controls, the addition of subtoxic NiSO4 concentrations (0.1-20 micrograms/ml) to keratinocyte cultures induced a significant, but low release of IL-1 alpha and IL-1 beta at 24 and 48 h, detectable by enzyme-linked immunosorbent assay of the supernatants of treated cells. Moreover, IL-1 receptor antagonist was significantly increased in the supernatants and the cell extracts. Using fluorescence-activated cell sorter analysis, ICAM-1 expression at 24 h was found to be induced in a dose-dependent manner, reaching a level comparable with that obtained upon interferon-gamma (10 IU/ml) stimulation. Overall, these data confirm the existence of direct interactions between Ni2+ and keratinocytes, which generate immunological signals of major importance in the pathophysiology of allergic contact dermatitis.

Antigens, CD↗
PubMed1994

Interleukin-4 and interferon-gamma interactions in the induction of intercellular adhesion molecule-1 and major histocompatibility complex class II antigen expression of normal human keratinocytes.

Interleukin-4 (IL-4) that may be produced by T-helper cells in atopic lesions has immunomodulatory activities on skin cells which are poorly known. Our study was aimed at determining whether the cytokine exerts some effects on keratinocyte activation and can either enhance or antagonize interferon-gamma (IFN-gamma)-induced ICAM-1 or HLA-DR antigen expression. Using normal keratinocytes cultured in defined medium and cytofluorography, we showed that treatments of the human cells with the cytokine IL-4 alone had no effect on the induction of ICAM-1 or HLA-DR molecules. However, a transient, but significant enhanced expression of ICAM-1 was observed by the combination of IFN-gamma and IL-4 after 24 h of stimulation, which was followed by a reduction at 48 and 72 h. Conversely, IL-4, when added during the IFN-gamma activation stage, had no effect on MHC class II antigen expression of keratinocytes; however, the cytokine reduced the expression of these antigens when added 24 h before the stimulation by IFN-gamma. These results suggest that IFN-gamma and IL-4 may interact to regulate ICAM-1 and HLA-DR expression on keratinocytes.

Cells, Cultured↗
PubMed1994

Effect of gamma-interferon on IL-1 alpha, beta and receptor antagonist production by normal human keratinocytes.

In inflammatory dermatoses, activated T cells produce interferon-gamma (IFN-gamma), which interacts with keratinocytes and contributes to the direct activation of these cells by inducing, among other factors, the expression of HLA-DR antigens and intercellular adhesion molecule-1. However, the action of IFN-gamma on epidermal cell cytokine production is not known. Our aim was to assess the effect of IFN-gamma on the production of IL-1 by normal human keratinocytes cultured in low calcium medium (MCDB153). In comparison with controls, the addition of non-toxic IFN-gamma concentrations (50-500 U/ml) to cell cultures induced a significant increase of IL-1 alpha and IL-1 beta production predominantly after 100 U/ml treatment in the cell extracts as well as in the supernatants at 24h and 48h. The production of the antagonist, IL-1RA, was also enhanced and the effect of the critical concentration (100 U/ml) was more evident. However, the absence of a characteristic dose response could not be explained by an antiproliferative effect of high IFN-gamma concentrations (250 and 500 U/ml) on cultured keratinocytes or by the induction of the nuclear stress protein, Hsp72, two phenomena known to down-regulate IL-1 biosynthesis. In conclusion, the modifications in keratinocyte IL-1 production under IFN-gamma stimulation can contribute to activate the epidermal cells and thus involve them in the local immune response.

Cell Cycle↗
PubMed1994

Induction of intercellular adhesion molecule 1 expression on normal human keratinocytes by retinoic acid: comparison of cultured keratinocytes and skin explants.

As retinoic acid (RA, all trans) induces irritant reactions when applied topically to skin, we wondered whether it may be involved in the activation state of keratinocytes through ICAM-1 induction. Human skin explants and cultured keratinocytes were treated by RA and/or interferon-gamma (IFN gamma) at different concentrations during 24, 48 and 72 h. ICAM-1 expression was examined and quantified by immunohistochemistry, in situ, on cutaneous frozen sections and in cultured keratinocytes by flow cytometry analysis. Expression of mRNA was checked by Northern blot hybridizations using an oligonucleotide probe. Our results indicate: (1) the absence of spontaneous ICAM-1 expression by normal human keratinocytes both in skin explants and in cultures; (2) an ICAM-1-induced expression after 48 h of treatment by RA concentrations > 10(-6) M; this induction is dose- and time-dependent; in skin explants, ICAM-1 is occasionally observed on foci of epidermal cells; this protein induction is correlated with transcript expression in cultured keratinocytes; and (3) a synergistic effect of RA and IFN gamma (5 IU/ml) on the percentage of ICAM-1-positive cells and the level of expression of the protein. These findings indicate that RA, in a therapeutical range of concentrations can induce or stimulate ICAM-1 expression in normal human keratinocytes. This may in part explain the erythematous reaction observed in vivo after topical applications of RA which may be considered as a mediator of keratinocyte activation.

Adult↗
PubMed1994

[Adhesion molecules and inflammatory dermatoses].

In inflammatory dermatoses, adhesion molecules are involved in the interaction of leukocytes with endothelial cells, extra-cellular matrix and epidermal cells. In dermatosis where epidermal cells are the main targets of inflammation, the keratinocytes are activated and participate to the local immune reaction through the secretion of cytokines and the expression of the adhesion molecule ICAM-1 and the HLA-DR antigens. Induction of ICAM-1 by IFN gamma or TNF alpha on keratinocytes that do not express this molecule in normal skin may account for the recruitment of T cells into the epidermis. In the dermis, an up-regulation of ICAM-1 expression occurs on endothelial cells activated by cytokines (IL-1, TNF alpha...) and is usually correlated with an induction of ELAM-1 and less frequently VCAM-1. These adhesion molecules are involved in the recruitment of inflammatory cells but also in the control of their retention and migration through the skin.

Cell Adhesion Molecules↗
PubMed1993

Soluble intercellular adhesion molecule 1 (sICAM-1) and malignant melanoma.

A soluble form of the intercellular adhesion molecule-1 (sICAM-1) has been reported to be elevated in malignant melanoma. We have studied the expression of sICAM-1 by ELISAs in a series of 85 consecutive sera derived from patients with primary or metastatic melanomas in comparison with control patients and patients with diffuse acute eczema and psoriasis. Our results showed elevated sICAM-1 concentrations in patients with malignant melanoma but also in patients with extensive inflammatory dermatoses. The diagnostic potential of sICAM-1 in malignant melanoma appears to be limited. Further studies are needed to determine whether increased values of sICAM-1 in primary melanomas may predict a progression of the disease.

Adult↗
PubMed1993

Contact sensitivity in mice: differential effect of vitamin D3 derivative (calcipotriol) and corticosteroids.

Vitamin D3 derivatives are new compounds used topically for the treatment of psoriasis. To get better insights into the mechanisms of action of these compounds, we studied the effect of local treatment with calcipotriol (vitamin D3 synthetic analogue) and compared it to that of betamethasone dipropionate in a murine contact sensitivity (CS) test, the Mouse Ear Swelling Test. Two haptens were used: oxazolone and paraphenylenediamine. Betamethasone and calcipotriol exerted a differential effect on the delayed-type hypersensitivity response. When drugs were applied to the abdomen (sensitization site) before sensitization, no effect was observed. When betamethasone was applied to the abdomen for 4 consecutive days after epicutaneous sensitization, a diminution of the CS response to the relevant hapten was observed, whereas calcipotriol given in the same conditions did not affect the reaction. Ointments were then administered to the ear (elicitation site) either for 4 consecutive days prior to the challenge, or for 4 days before and 2 days after the challenge. In both conditions, calcipotriol and betamethasone exerted a differential effect on elicitation, the latter inhibiting and the former increasing the CS response to oxazolone and paraphenylenediamine. From these results we conclude: (1) that vitamin D3 derivatives are devoided of immunosuppressive effects when applied topically, and (2) that clinical improvement of chronic inflammatory dermatoses observed with topical vitamin D3 derivatives and corticosteroids is due to different mechanisms.

Adrenal Cortex Hormones↗