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N J Reynolds

Publications and source records attributed to N J Reynolds.

At least 37 records · Page 2Linked to original sources
PubMed1998

Cyclosporin A inhibits 12-O-tetradecanoyl-phorbol-13-acetate-induced cutaneous inflammation in severe combined immunodeficient mice that lack functional lymphocytes.

A single application of 12-O-tetradecanoyl-phorbol-13-acetate (TPA) to mouse skin results in an acute inflammatory response, with an influx of neutrophils and lymphocytes, epidermal hyperplasia and abnormal keratinocyte differentiation. This response is significantly inhibited by topical cyclosporin A (CyA). Although CyA is known to inhibit T-cell activation, the role of T cells in TPA-induced cutaneous inflammation is not well understood. In this study, we have used severe combined immunodeficient (SCID) mice, which carry a spontaneous mutation resulting in the absence of functional T and B lymphocytes, to examine whether lymphocytes are required for the TPA response in mouse skin and whether CyA inhibits the TPA response in SCID mice. A significant increase in epidermal and deep dermal inflammation was observed in both SCID and CB-17 mice 24 h after a single application of TPA (10 nmol) compared with vehicle (P < 0.05, n = 5-7). Simultaneous application of CyA (1.7 mumol) plus TPA resulted in a significant reduction in epidermal and deep inflammation at 24 h compared with TPA alone in SCID and CB-17 mice (P < 0.05, n = 7). In contrast to hairless mice, a variable increase in epidermal thickness was observed in both SCID and CB-17 mice after treatment with TPA at 24 and 72 h, which was not significantly affected by CyA. These data indicate that TPA-induced inflammation in mouse skin does not depend on lymphocytes. In addition, the inhibition of TPA-induced epidermal and deep dermal inflammation by CyA in SCID mouse skin suggests that CyA exerts effects on cutaneous inflammation in mice in the absence of functioning T cells.

Animals↗
PubMed1997

SCH 47112, a novel staurosporine derivative, inhibits 12-O-tetradecanoylphorbol-13-acetate-induced inflammation and epidermal hyperplasia in hairless mouse skin.

Protein kinase C (PKC) regulates keratinocyte growth and differentiation as well as inflammation in skin, processes which are abnormal in skin diseases such as psoriasis. 12-O-tetradecanoylphorbol-13-acetate (TPA) binds to and activates PKC. We investigated the effects of SCH 47112, a novel staurosporine derivative, which interacts with the catalytic domain of PKC, on TPA-induced inflammation and hyperplasia in hairless mouse skin and TPA-induced differentiation in cultured human keratinocytes. Dorsal mouse skin was treated with vehicle, TPA (2.0/ 2.5 nmol) or SCH 47112 followed by TPA. Epidermal thickness, and epidermal, upper dermal and deep dermal inflammation (assessed on an ordinal semiquantitative scale) were determined in biopsies taken 24 h and 48 h post-treatment. SCH 47112 (100 nmol) inhibited TPA-induced epidermal, upper dermal and deep dermal inflammation by 71%, 45% and 22%, respectively, at 24 h (n = 3, P < 0.05). TPA-induced epidermal hyperplasia was inhibited by SCH 47112 (400 nmol) by 38% at 48 h (n = 3, P < 0.05). In addition, in cultured human keratinocytes, SCH 47112 inhibited TPA induction of transglutaminase. I protein, which catalyzes the formation of crosslinked envelopes. These results indicate that SCH 47112 exhibits biological activity, inhibiting TPA-induced changes in hairless mouse skin in vivo and cultured human keratinocytes in vitro, and suggest that PKC inhibitors may have a therapeutic role in inflammatory skin diseases.

Animals↗
PubMed1997

Overexpression of protein kinase C-alpha and -beta isozymes by stromal dendritic cells in basal and squamous cell carcinoma.

Protein kinase C (PKC) isoenzymes transduce signals from cell surface receptors and thereby regulate important cellular functions in skin including keratinocyte growth and differentiation. Overexpression of individual PKC isoenzymes results in aberrant cell growth and in certain instances tumorigenicity. PKC is implicated in tumour promotion in mouse skin. Abnormal expression of PKC has been reported in several human cancers. We have, therefore, investigated expression of PKC-alpha and -beta in basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) by immunohistochemistry. Sections were stained with specific antibodies to PKC-alpha, PKC-beta, CD1a, T cells, B cells and dermal dendritic cells (factor XIIIa), using an immunoperoxidase technique. PKC-alpha and PKC-beta were not detected in tumour cells in BCCs or SCCs. In SCCs, PKC-beta immunostaining revealed positively stained inflammatory and dendritic cells scattered through the stroma; PKC-alpha immunostaining was essentially negative. In contrast, in BCCs, PKC-alpha+ and PKC-beta+ dendritic and spindle-shaped cells were observed in the stroma, immediately adjacent to the tumour islands. Double-labelling experiments showed that a proportion (approximately 20%) of PKC-beta+ dendritic cells also expressed factor XIIIa. BCCs depend on stroma for growth; PKC regulates expression of type IV collagenase and stromelysin III and interactions between tumour and stroma may be important in determining tumour invasion and metastasis. Therefore, overexpression of PKC-alpha and -beta by stromal dendritic cells in BCCs suggests that PKC activation may be involved in stromal/tumour interactions in these tumours.

Basal Cell Carcinoma↗
PubMed1997

Necrolytic migratory erythema and zinc deficiency.

Necrolytic migratory erythema (NME) is an uncommon condition classically associated with high plasma levels of circulating glucagon and a glucagonoma. We report a patient with cirrhosis who showed clinical and histological features of NME. Investigation revealed normal glucagon levels without evidence of glucagonoma. Serum zinc levels were below the normal range and zinc supplementation resulted in rapid and complete resolution of the eruption.

Erythema↗
PubMed1995

Up-regulation of p21WAF1/CIP1 in psoriasis and after the application of irritants and tape stripping.

p21WAF1/CIP1 is a nucleoprotein that was initially characterized by its ability to be regulated transcriptionally by p53 and by its ability to mediate growth arrest by binding to cyclin-dependent kinases. Although p21WAF1/CIP1 is thought to mediate the effects of p53 in causing growth arrest, p21WAF1/CIP1 is also regulated in a p53-independent manner, e.g., during terminal differentiation of some cell lines. Growth factors including epidermal growth factor also induce p21WAF1/CIP1 through p53-independent pathways. Because the epidermal growth factor signaling pathway is abnormal in psoriatic epidermis, we studied p21WAF1/CIP1 expression, using in situ hybridization and immunohistochemistry, in psoriasis. Both p21WAF1/CIP1 mRNA and protein were significantly elevated in untreated psoriatic plaques compared with uninvolved psoriatic skin (p < 0.0001), with the up-regulation of p21WAF1/CIP1 being predominantly suprabasal. This increase was accompanied by a small increase in p53 protein expression of uncertain significance. Furthermore, p21WAF1/CIP1 expression was induced in skin after sellotape stripping and by the application of agents, such as dithranol, that are capable of inducing hyperproliferation. The pattern of p21WAF1/CIP1 expression observed is consistent with a role in induction and maintenance of differentiation. Our experiments, however, cannot determine whether the abnormalities of p21WAF1/CIP1 epidermal expression in psoriasis and after insult are independent of changes in p53 expression.

Anthralin↗
PubMed1995

Down-regulation of Langerhans cell protein kinase C-beta isoenzyme expression in inflammatory and hyperplastic dermatoses.

The family of protein kinase C (PKC) isoenzymes plays a fundamental part in signal transduction, and thereby regulates important cellular functions, including growth, differentiation, cytokine production and adhesion molecule expression. In lesional psoriatic skin, Ca(2+)-dependent PKC activity, PKC-beta protein and epidermal Langerhans cell (LC) PKC-beta immunostaining are significantly decreased, indicating activation and subsequent down-regulation of PKC. Whether these changes occur in other inflammatory/hyperplastic dermatoses is, however, unknown. We examined PKC-alpha and PKC-beta expression in normal skin, psoriasis, cutaneous T-cell lymphoma (CTCL), lamellar ichthyosis, non-bullous ichthyosiform erythroderma, atopic dermatitis, urushiol-induced allergic contact dermatitis, and sodium lauryl sulphate (SLS)-induced irritant contact dermatitis. Cryostat sections were stained for PKC-alpha and PKC-beta, and the LC marker CD1a, using an immunoperoxidase technique and specific monoclonal antibodies. Double-labelling studies, in normal skin, revealed co-expression of PKC-beta and CD1a by epidermal LCs. Analysis of the number of PKC-beta+ and CD1a+ epidermal LCs, in diseased compared with normal skin, revealed three categories: (i) in psoriasis and CTCL, the PKC-beta+ epidermal LC number was significantly reduced, whereas the CD1a+ epidermal LC number was unchanged; (ii) in allergic and irritant contact dermatitis, both PKC-beta+ and CD1a+ epidermal LCs were significantly reduced in number; and (iii) in atopic dermatitis, the PKC-beta+ epidermal LC number was normal, and CD1a+ epidermal LCs were significantly increased in number. Moreover, the ratio of epidermal LC PKC+/CD1a+ was reduced in all the dermatoses studied, suggesting activation of PKC-beta, with subsequent down-regulation. Within the dermis, increased PKC-beta staining of infiltrating cells was observed in all the conditions studied except lamellar ichthyosis and non-bullous ichthyosiform erythroderma. These data indicate that: (i) down-regulation of LC PKC-beta occurs in a variety of inflammatory and hyperplastic skin disorders, and is not unique to psoriasis, and (ii) the pattern of epidermal LC PKC-beta and CD1a expression varies among the diseases studied. In mice, PKC activation induces LC migration. Thus, down-regulation of epidermal LC PKC-beta associated with reduced CD1a+ epidermal LCs in allergic and irritant contact dermatitis suggests that PKC-beta may transduce the signal for migration of LCs from human epidermis.

Adult↗
PubMed1994

Translocation and downregulation of protein kinase C isoenzymes-alpha and -epsilon by phorbol ester and bryostatin-1 in human keratinocytes and fibroblasts.

Protein kinase C isoenzymes can be subdivided into two classes, based on their requirement for calcium. Protein kinase C-alpha, beta I, -beta II, and -gamma are calcium dependent, whereas protein kinase C-gamma, -epsilon, -zeta, -eta, and -theta are calcium independent. We have examined the expression, translocation, downregulation, and activation of calcium-dependent and -independent protein kinase C isoenzymes in human skin keratinocytes and fibroblasts. Human keratinocytes and fibroblasts expressed protein kinase C-alpha, -delta, -epsilon, and -zeta mRNA and protein, whereas protein kinase C-eta (L) was detected only in keratinocytes. Protein kinase C-beta I, -beta II, -gamma, and -theta were not detected in either cell type. The protein kinase C activators 12-0-tetradecanoylphorbol 13-acetate and bryostatin-1 (50 nM, for 5 min) induced translocation of protein kinase C-alpha and -epsilon cytosol to membrane in both keratinocytes and fibroblasts. 12-0-tetradecanoylphorbol 13-acetate and bryostatin-1, for 18 h, induced complete downregulation (i.e., loss) of protein kinase C-alpha and -epsilon in keratinocytes, but only partial downregulation was observed in fibroblasts. The subcellular distribution of protein kinase C-delta, -zeta or protein kinase C-eta, in keratinocytes or fibroblasts, did not change in response to 12-0-tetradecanoylphorbol 13-acetate or bryostatin-1. These data indicate differential expression, subcellular distribution, and regulation of protein kinase C isoenzymes in human skin cells.

Base Sequence↗
PubMed1994

Dissociation of erythema and p53 protein expression in human skin following UVB irradiation, and induction of p53 protein and mRNA following application of skin irritants.

The mechanisms mediating the varied effects of ultraviolet radiation (UVR) on human skin are unclear, although a relationship between erythema and DNA damage is suggested by photosensitivity in xeroderma pigmentosum. Increased p53 expression in response to UVR is thought to reflect direct DNA damage, but recent evidence indicates that UVR also activates membrane and cytosolic signal transduction pathways. In this study, we have investigated the relationship between erythema and p53 induction following UVB and whether this p53 response is specific to UVR. p53 protein expression was determined by immunocytochemistry using the monoclonal antibody DO7, and p53 mRNA expression was examined by non-isotopic in situ hybridization. Incremental doses of UVB were administered to the lower back of eight subjects. Immunostaining revealed that p53 positive nuclei were significantly increased 8 h after suberythemogenic doses of UVB (79 +/- 12), compared to normal unirradiated skin (8 +/- 6, p < 0.0005), but no change in p53 mRNA was seen. Higher UVB doses, which resulted in moderate erythema, resulted in a similar or greater induction of p53 protein. Indomethacin (1% w/v), applied immediately after UVB irradiation, significantly inhibited UVB erythema at 8 h in six subjects (p < 0.005), but did not reduce p53 immunostaining. Dithranol (1 microgram/microliter, n = 8), sodium dodecylsulphate (5%, n = 4), and retinoic acid (0.5%, n = 4), applied for 48 h, caused erythema, significantly increased p53 protein levels (p < 0.05), and also increased p53 mRNA. Our results show that in human skin, UVB-induced p53 elevation can be dissociated from erythema and skin irritants can also induce p53 protein. The induction of p53 mRNA by irritants but not UVR suggests different mechanisms of action.

Adult↗
PubMed1993

Differential induction of phosphatidylcholine hydrolysis, diacylglycerol formation and protein kinase C activation by epidermal growth factor and transforming growth factor-alpha in normal human skin fibroblasts and keratinocytes.

We have investigated coupling between the epidermal growth factor (EGF) receptor and the phospholipase C (PLC)/protein kinase C (PKC) signal-transduction system in normal skin fibroblasts and keratinocytes, for which EGF and transforming growth factor alpha (TGF-alpha) are mitogenic. EGF and TGF-alpha induced a rapid increase in tyrosine phosphorylation of the EGF receptor, in both fibroblasts and keratinocytes, but failed to induce tyrosine phosphorylation of PLC-gamma 1 or detectable phosphoinositide hydrolysis, as measured by two sensitive assays. In fibroblasts, EGF induced phosphatidylcholine (PC) hydrolysis, resulting in increased diacylglycerol (DAG). In contrast, in keratinocytes, there was no detectable PC hydrolysis or elevation of DAG in response to EGF or TGF-alpha. EGF and TGF-alpha activated PKC in fibroblasts, as evidenced by increased phosphorylation of a specific cellular PKC substrate (myristoylated alanine-rich C-kinase substrate, 'MARCKS'). In keratinocytes, TGF-alpha and EGF induced only a modest increase in MARCKS protein phosphorylation. This apparent modest activation of PKC, in the absence of detectable DAG formation, may have been mediated by arachidonic acid, which was released from keratinocytes in response to TGF-alpha, and has been shown to stimulate PKC activity in vitro. These data demonstrate that (1) in dermal fibroblasts and keratinocytes, which express normal levels of EGF receptors, EGF receptor activation is not coupled to tyrosine phosphorylation of PLC-gamma 1 or PtdIns hydrolysis, suggesting that these events are not required for the mitogenic activity of EGF or TGF-alpha in these cells, (2) coupling of EGF receptor to PC hydrolysis is cell-type specific, and (3) in skin fibroblasts, DAG, formed through EGF-induced PC hydrolysis, is capable of activating PKC.

Arachidonic Acid↗
PubMed1993

Phosphatidic acid and phospholipase D both stimulate phosphoinositide turnover in cultured human keratinocytes.

Phosphatidic acid (PA) induced a rapid dose-dependent increase in production of inositol phosphates in cultured adult human keratinocytes, peaking at 30 s. Natural and dioleoyl PA were equally effective, while other phospholipid classes had no effect. Lipid A was also active. Lyso-PA also induced inositol phosphate production, but contamination of the PA preparation by lyso-PA could not account for the effect of PA. The effect of PA could not be reproduced by treatment of cells with calcium ionophore. PA-induced inositol phosphate production could be inhibited (> 50%) by pre-treatment of cells with either pertussis toxin or 12-O-tetradecanoylphorbol 13-acetate, suggesting the involvement of a GTP-binding protein and a protein kinase C-mediated negative feedback mechanism. PA also stimulated release of arachidonic acid from keratinocytes. Treatment of cells with exogenous phospholipase D similarly induced inositol phosphate production in the keratinocytes. Since PA may be formed by receptor-mediated activation of phospholipase D, or by phosphorylation of diacylglycerol, the results suggest that PA may play a significant role in signalling mechanisms of human keratinocytes.

Arachidonic Acid↗
PubMed1993

CD1 gene expression in human skin.

In human epidermis, expression of CD1a is confined to Langerhans cells (LC), whereas CD1c expression has been observed in dendritic cells of the dermis, as well as the epidermis. In transfected fibroblasts, expression of CD1c at the cell surface appears to exclude expression of either CD1b or CD1a, despite continued transcription of the latter genes. In order to determine whether this mechanism might be operative in human skin, we have compared the expression of CD1a and CD1c on the surface of dermal and epidermal dendritic cells to their expression at the level of mRNA using a combination of dual-label immunofluorescence microscopy, northern blot hybridization, and reverse transcriptase-polymerase chain reaction (RT-PCR). By both immunofluorescence and Northern blotting, CD1c expression was observed in both dermal and epidermal cells, whereas expression of CD1a was confined largely to the epidermis. Moreover, as shown by immunomagnetic bead selection and RT-PCR, CD1a and CD1c were both expressed on epidermal LC, but were absent from other epidermal cell types. These results argue against cell surface exclusion as a mechanism for selective expression of CD1c in human dermis.

Antigens, CD↗
PubMed1993

Differential expression of protein kinase C isoenzymes in normal and psoriatic adult human skin: reduced expression of protein kinase C-beta II in psoriasis.

Psoriatic lesions contain elevated levels of 1,2-diacylglycerol, the physiologic activator of protein kinase C (PKC), suggesting that PKC activation may be aberrant in psoriasis. We therefore have investigated the expression and properties of PKC isozymes in normal and psoriatic skin and in human skin cells. Chromatographic and immunoblot analyses revealed the presence of the calcium-dependent PKC isozymes PKC-alpha and -beta, but not -gamma, in normal human epidermis. PKC-beta was more prominent, constituting two thirds of the total calcium-dependent PKC activity. In psoriatic lesions, expression of both PKC-alpha and -beta was decreased, with preferential reduction (80%) of PKC-beta. Northern analysis and semi-quantitative polymerase chain reaction (PCR) indicated no change in the mRNA levels of PKC-alpha and -beta between normal and psoriatic epidermis. In normal epidermis, PKC-alpha was expressed mainly in the lower epidermis, whereas PKC-beta was localized to the upper cell layers, with very intense staining of CD1a+ Langerhans cells. In psoriasis, PKC-alpha staining was present in the lower epidermis, whereas PKC-beta staining was essentially absent, with the exception of some positive inflammatory cells. In addition to PKC-alpha and beta, immunoblot and Northern/PCR analysis revealed expression of four calcium-independent PKC isozymes, delta, epsilon, zeta, and eta, in both normal and psoriatic skin. There were no significant differences in mRNA levels among any of these PKC isozymes, between normal and psoriatic skin. Soluble PKC-zeta protein was modestly increased (twofold) in psoriatic, compared to normal, skin, whereas the levels of PKC-delta, epsilon, and eta were unchanged. Analysis of PKC isozyme expression in the three major cell types of human epidermis revealed that Langerhans cells and keratinocytes were the major sources of PKC-beta and PKC-zeta, respectively. These data demonstrate the diversity of PKC isozyme expression in human skin, and suggest that alterations of PKC-beta and -zeta may participate in the aberrant regulation of growth and differentiation observed in psoriasis.

Adult↗
PubMed1993

Hydralazine predisposes to acute cutaneous vasculitis following urography with iopamidol.

We report a 60-year-old woman with renovascular hypertension who developed a severe cutaneous vasculitis 24 h after the injection of iopamidol during urography. A review of the literature suggests that her concomitant hydralazine therapy probably predisposed her to this reaction, as similar reactions have occurred in systemic lupus erythematosus, and hydralazine can induce a LE-like syndrome. We recommend that urography should be avoided in patients receiving hydralazine.

Contraindications↗
PubMed1993

Folliculitis in Down's syndrome.

Twenty-two male and 20 female adults with Down's syndrome were examined. Ten of the men and two of the women had a follicular rash consistent with Malassezia folliculitis. Oral itraconazole treatment produced a significant improvement in the rash, accompanied by a decrease in the skin Malassezia count. Clinical relapse occurred when therapy was discontinued, and was accompanied by return of the Malassezia yeasts.

Administration, Oral↗
PubMed1993

Retinoic acid metabolites exhibit biological activity in human keratinocytes, mouse melanoma cells and hairless mouse skin in vivo.

Topical all-trans retinoic acid (RA) modulates growth and differentiation of skin and is used in the treatment of various dermatological disorders. RA is metabolized to 4-hydroxy RA, 4-oxo RA and 5,6-epoxy RA, which are believed to be markedly less active than RA. 3,4-didehydroretinoic acid (ddRA) is a metabolite of 3,4-didehydroretinol which is present in skin. ddRA is biologically active and acts as a morphogen. We have determined the relative biological activity of ddRA, 4-hydroxy RA, 4-oxo RA and 5,6-epoxy RA as assessed by three retinoid responsive systems relevant to skin. RA, ddRA, 4-hydroxy RA, 4-oxo RA and 5,6-epoxy RA (10-100 nM) reduced epidermal transglutaminase activity in human keratinocytes to similar extents, and inhibited alpha-melanocyte-stimulating hormone-isobutylmethylxanthine-inducible tyrosinase activity in Cloudman S-91 mouse melanoma cells by 67, 39, 48, 51 and 19%, respectively, at 100 nM. Daily topical application of the retinoids to hairless mouse skin for 4 days resulted in dose-dependent changes in epidermal thickness and global histological score. The relative potencies of RA, ddRA, 4-hydroxy RA, 4-oxo RA and 5,6-epoxy RA, as calculated by parallel line assay, were 1.0, 0.60, 0.34, 0.29 and 0.18, respectively, for epidermal hyperplasia and 1.0, 0.78, 0.23, 0.14 and 0.08, respectively, for global histological score. Interestingly, the compounds exhibited a similar rank order of potency with respect to induction of cellular retinoic acid binding protein-II mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗