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J N Barker

Publications and source records attributed to J N Barker.

At least 19 recordsLinked to original sources
PubMed1999

In vivo UVA-1 and UVB irradiation differentially perturbs the antigen-presenting function of human epidermal Langerhans cells.

Ultraviolet B (UVB, 290-320 nm) radiation is known to suppress the immune function of epidermal Langerhans cells. We have recently described that in vitro UVB irradiation perturbs the antigen-presenting cell function of Langerhans cells by inhibiting their expression of functional B7 costimulatory molecules (B7-1, B7-2). The aim of this study was to determine wavelength-specific UV effects on Langerhans cells function in vivo, specifically UVB and UVA-1. To address this issue, volunteers were irradiated on the sun protected volar aspects of their forearms with 3 x minimal erythema dose of UVB (Philips TL-12) and UVA-1 (UVASUN 5000 Mutzhaas). Langerhans cells were isolated from suction blister roofs immediately following irradiation. Langerhans cells isolated from UVB- but not from UVA-1-irradiated skin failed to activate naïve resting allogeneic T cells (mixed epidermal cell leukocyte reaction) or primed tetanus toxoid reactive autologous T cells. Langerhans cells isolated from sham-irradiated or UVA-1-irradiated skin strongly upregulated B7-2 molecules during short-term tissue culture. By contrast, Langerhans cells from UVB-irradiated skin did not upregulate B7-2 molecules. Furthermore, exogenous stimulation of the B7 pathway by anti-CD28 stimulatory monoclonal antibodies restored the capacity of UVB-irradiated Langerhans cells to activate both alloreactive and tetanus toxoid-reactive T cells, implying suppressed antigen-presenting cell activities and perturbed B7 expression of Langerhans cells isolated from UVB-irradiated skin are related. Those studies demonstrate that in vivo UVB, but not UVA-1, interferes with the activation-dependent upregulation of B7 molecules on Langerhans cells, which in turn is of functional relevance for the perturbed antigen-presenting cell function of Langerhans cells within UVB- but not UVA-1-irradiated skin.

Antigen Presentation↗
PubMed1998

Contrasting effects of ultraviolet A1 and ultraviolet B exposure on the induction of tumour necrosis factor-alpha in human skin.

Ultraviolet B (UVB) irradiation of the skin causes immunosuppression which is relevant to the induction of skin cancer. The mechanism of this immunomodulation is unclear but various regulatory molecules have been implicated, including cis-urocanic acid (cis-UCA) and the cytokines tumour necrosis factor-alpha (TNF-alpha) and interleukin 10 (IL-10). Whether ultraviolet A (UVA) induces similar changes has not been investigated fully. We studied the effect of in vivo UVB and long-wave UVA (UVA1) exposure on the induction of TNF-alpha, IL-10 and cis-UCA in human skin. Volunteers were irradiated with three minimal erythema doses (MED) of UVB or UVA1. At different times after irradiation, suction blisters were raised from irradiated and from non-irradiated (control) skin. The TNF-alpha and IL-10 protein concentration, and the percentage of cis-UCA in the blister fluid, were then determined. UVB irradiation of human skin led to a rapid and significant increase in TNF-alpha concentration in suction-blister fluid, with maximal values 6 h after irradiation (n = 6, P < 0.05). In contrast, UVA1 irradiation led to a decrease in TNF-alpha concentration in the suction-blister fluid compared with non-irradiated skin, with the lowest values 6 h after irradiation (n = 6, P < 0.05). Both UVB and UVA1 exposure of the skin induced a slight increase in IL-10 concentration. However, the increase in IL-10 was only significant after UVB irradiation (UVB, n = 6, P < 0.05; UVA, n = 7, P < 0.1). As previously shown, both UVB and UVA1 result in the photo-isomerization of trans-UCA and an increased percentage of cis-UCA was found in the suction-blister fluid. Thus the results show differential effects of UVB and UVA1 irradiation on the induction of immunoregulatory molecules, which may help to explain the variation in immune responses after UVB and UVA1 exposure of human skin.

Adult↗
PubMed1998

Ultraviolet B induced suppression of induction of contact sensitivity in human skin is not associated with tumour necrosis factor-alpha-308 or interleukin-10 genetic polymorphisms.

Low doses of ultraviolet B (UVB) can induce localized immunosuppression in skin. This effect may be important in the induction of skin cancers and is thought to be mediated by tumour necrosis factor (TNF) alpha and interleukin (IL) 10 in conjunction with other factors. In humans a transition polymorphism in the TNF-alpha gene may affect TNF-alpha secretion and the promoter region of the IL-10 gene contains a CA repeat polymorphism which may affect gene function. We have therefore investigated the association of these polymorphisms with UVB-induced immunosuppression in humans. Volunteers (n = 42) were irradiated with UVB then sensitized on irradiated skin with diphenylcyclopropanone (DPCP) and subsequently antigen challenged with DPCP. DNA was extracted from blood samples and volunteers genotyped for the TNF-alpha polymorphism by polymerase chain reaction (PCR) and restriction digestion. The CA repeat polymorphism was amplified by PCR and sized by gel electrophoresis. Twenty-four volunteers were susceptible to UVB-induced immunosuppression and 18 were resistant. The association of allele frequencies and phenotype was statistically tested using a chi2-test. For both the TNF-alpha and IL-10 polymorphisms, there was no statistically significant association between allele types and response to UVB. These results indicate that variation in the immune response to UVB in humans is not associated with the TNF-alpha-308 transition or IL-10 CA repeat polymorphisms, although other as yet undetected DNA sequence variants of these genes may be involved.

Alleles↗
PubMed1998

Effect of granulocyte macrophage-colony stimulating factor on Langerhans cells in normal and healthy atopic subjects.

Granulocyte macrophage-colony stimulating factor (GM-CSF) is a multipotent cytokine produced by many cutaneous cell types including keratinocytes. Langerhans cells (LC) represent the major antigen-presenting cells in skin, and in vitro studies demonstrate that GM-CSF is of pivotal importance in LC. Healthy volunteers (n = 3 non-atopic, n = 3 with atopy) received recombinant human GM-CSF (0. 05 microg/mL) by intradermal injection for 3 days to the same site. Diluent was injected in a similar manner as control. Biopsies were taken 24 h after the final injection and examined immunohistochemically for LC and inflammatory cell markers. Compared with control sites, intradermal GM-CSF resulted in shortening of dendritic cell processes and redistribution of LC in the epidermis; numbers of CD1a + cells in the epidermis were significantly decreased (P < 0.005), while those in the dermis were significantly increased (P < 0.05) following intradermal GM-CSF when compared with controls. Double labelling studies on epidermal CD1a + cells indicated de novo expression of intercellular adhesion molecule (ICAM)-1 and increased expression of HLA-DR following GM-CSF (P < 0. 005, P < 0.005, respectively). Additional findings included a marked mixed inflammatory cell infiltrate in the dermis and increased expression of the endothelial cell adhesion molecules E-selectin and ICAM-1. These data indicate that in normal human skin, GM-CSF induces changes in the phenotype and distribution of CD1a + cells consistent with LC functional maturation and exit from the epidermis to the dermis. As these events are central to the initiation of cutaneous inflammation, GM-CSF may potentially play a critical role in the pathogenesis of inflammatory dermatoses.

Adolescent↗
PubMed1998

Susceptibility to effects of UVB irradiation on induction of contact sensitivity, relevance of number and function of Langerhans cells and epidermal macrophages.

Sensitization on skin exposed to acute low-dose UVB irradiation separates normal humans into two phenotypically distinct groups: One group, following sensitization on UVB-irradiated skin, develops contact sensitivity, designated UVB resistant (UVB-R) and the second group, following sensitization on UVB-irradiated skin, fails to develop contact sensitivity, designated UVB susceptible (UVB-S). To investigate whether UVB susceptibility in humans in related to antigen-presenting activity in the skin we studied the effect of UVB irradiation on the number and function of the epidermal antigen-presenting cells in volunteers identified as UVB-R and UVB-S. Single cell suspensions of epidermal cells from control skin and skin exposed to 3 minimal erythema doses (MED) of UVB 3 days previously were stained for Langerhans cells (CD1a+HLA-DR+) and epidermal macrophages (CD1a-HLA-DR+). The UVB exposure of the skin significantly decreased the percentage of Langerhans cells (UVB-R: n = 7, P < 0.02, UVB-S: n = 6, P < 0.03) and increased the percentage of epidermal macrophages (UVB-R: n = 7, P < 0.03, UVB-S: n = 6, P < 0.03) however to the same degree in both the UVB-R and the UVB-S group. To study the effect on Langerhans cell alloreactivity, epidermal cells were harvested immediately after UVB irradiation. However, in both UVB-R and UVB-S subjects the Langerhans cell alloreactivity was blocked to the same degree immediately after UVB irradiation compared to nonirradiated epidermal cells. To determine the effect of UVB irradiation on epidermal macrophages, epidermal cells were harvested 3 days after UVB irradiation. Irradiated epidermal cells from both UVB-R and UVB-S subjects demonstrated a strong antigen-presenting capacity compared to epidermal cells from control skin leading to activation of T cells that mainly secrete interferon (IFN)-gamma and not interleukin (IL)-4. In conclusion we found that UVB susceptibility was not correlated with the number of Langerhans cells or epidermal macrophages in the skin at the same time of sensitization. Neither was it correlated with the capacity of Langerhans cells nor UVB-induced epidermal macrophages to activate T cells in vitro.

Adult↗
PubMed1998

Psoriasis as a T cell-mediated autoimmune disease.

Psoriasis is a common chronic skin disease in which T lymphocytes are thought to play a vital pathogenic role. Evidence shows that these are activated memory skin-homing T cells which induce characteristic disease features via cytokine production. Understanding the mechanisms of T cell accumulation in skin and mediation of psoriasis is critical to designing immunotherapy for this distressing disease.

Autoimmune Diseases↗
PubMed1997

Progress in psoriasis. Psoriasis: from gene to clinic. London, UK, 5-7 December 1996.

In a meeting dedicated to a single common complex disease such as psoriasis, it is not surprising that many unanswered questions were raised. However, the meeting highlighted the impressive progress being made in psoriasis research at both the investigative and the therapeutic levels. A follow-up meeting is to take place in 1999, when further characterization of susceptibility gene loci should be available, together with data concerning the selective nature of disease-causing T cells and the antigens that trigger the disease. Identification of these critical factors should allow development of highly specific therapeutic agents, some of which are beginning to find their way into clinical development.

Cell Differentiation↗
PubMed1997

Contrasting effects of ultraviolet-A and ultraviolet-B exposure on induction of contact sensitivity in human skin.

Ultraviolet-B (UVB), in addition to direct effects on DNA, induces immunological changes in the skin that predispose to the development of skin cancer. Whether ultraviolet-A (UVA) induces similar changes is unknown. This effect can be investigated in humans in vivo using epicutaneous antigens as a model of tumour antigens. Volunteers (n = 46) were randomly assigned to received no sensitization, sensitization with the allergen diphenylcyclopropenone (DPCP) on non-UV-exposed normal skin, or sensitization with DPCP on skin exposed to three minimal erythema doses (MED) of either UVA or UVB radiation 3 days before sensitization. Three weeks after sensitization all volunteers were challenged with five different concentrations of DPCP. The challenge reactions were scored clinically and the increase in skin thickness was measured using a micrometer. Sensitization on UVB-exposed skin reduced the immunization rate compared with sensitization on non-irradiated skin (P < 0.03) as previously described. In contrast, sensitization on skin exposed to three MED UVA radiation did not result in a decreased immunization rate compared with non-irradiated skin. These results indicate that in humans erythemagenic doses of UVA radiation do not reduce the immunization rates to epicutaneous allergens. Thus UVB and UVA irradiation have contrasting effects on cell-mediated immunity in humans. These findings may at least in part explain the less carcinogenic effect of UVA irradiation.

Adolescent↗
PubMed1997

Identification of a major susceptibility locus on chromosome 6p and evidence for further disease loci revealed by a two stage genome-wide search in psoriasis.

Psoriasis is a common chronic inflammatory disorder of the skin. To further understand the pathogenesis of psoriasis we have chosen to investigate the molecular genetic basis of the disorder. We have used a two-stage approach to search the human genome for the location of genes conferring susceptibility to psoriasis, using a total of 106 affected sibling pairs identified from 68 independent families. As over a third of the extended kindreds included affected relatives besides siblings, in addition to an analysis of allele sharing between affected sibling pairs, a novel linkage strategy was applied that extracts full non-parametric information. Four principal regions of possible linkage were identified on chromosomes 2, 8, 20 (p <0.005) and markers from the MHC region at 6p21 (p <0.0000006) for which significant evidence of linkage disequilibrium was also observed (p <0.00002). Whilst data from limited case control associations exist to implicate the MHC, the results of this genome wide analysis demonstrate that, at least in the population studied, a gene or genes located within the MHC and close to the class 1 HLA loci, represent the major determinant of the genetic basis of psoriasis.

Chromosomes, Human, Pair 6↗
PubMed1997

CD44 variant expression in cutaneous T-cell lymphoma.

Expression of the lymphocyte homing receptor CD44 and its splice variants have been linked to tumour dissemination and poor prognosis in non-Hodgkin's lymphoma. Specifically, the in vitro expression of variant exon V6 confers metastatic potential in rat pancreatic carcinoma cell lines. In this study, we investigated the expression of CD44 splice variants in cutaneous T-cell lymphomas, including patients with mycosis fungoides (MF), Sezary syndrome (SS), large-cell anaplastic lymphoma (LCAL) and HTLV1-associated cutaneous lymphoma. In addition, 4 involved lymph nodes from 2 patients with MF and 1 patient with SS were examined. Inflammatory dermatoses, lichen planus and psoriasis, and normal skin were also studied. Immunohistochemistry was performed using a panel of monoclonal antibodies, including those with specificity for CD44H (standard isoform) and variant exons V3, V6 and V8-9. Normal epidermal keratinocytes were consistently CD44H and CD44 V3, V6 and V8-9 positive. In all the different clinicopathological subtypes and stages of cutaneous T-cell lymphomas, including involved lymph nodes, tumour cells consistently expressed CD44H, but were CD44 V3 and V6 negative. CD44 V8-9 was expressed on a majority of tumour cells in 2/5 LCAL and on occasional tumour cells in 2/5 LCAL. Occasional V8-9 positive tumour cells were also identified in 6/13 MF, 1/4 SS and 3/4 HTLV1. In 2/3 lymph node samples from 2 patients with tumour-stage MF, CD44 V8-9 expression was found on a small percentage of atypical mononuclear cells. Scattered V8-9 positive dermal mononuclear cells were present in sections of lichen planus and psoriasis. We have found no evidence to suggest that the metastasis-associated CD44 variant exon (V6) is expressed in cutaneous T-cell lymphoma, or that CD44H expression is associated with an adverse prognostic group. It is not clear whether the strong expression of CD44 V8-9 in 2 patients with CD30 positive LCAL reflects activation status or metastatic potential.

Alternative Splicing↗
PubMed1997

Ramipril-associated lichen planus pemphigoides.

We report the first case of lichen planus pemphigoides (LPP) secondary to ingestion of ramipril, an angiotensin-converting enzyme inhibitor. Clinical, histological and immunofluorescent findings were all consistent with a diagnosis of LPP. Linear basement membrane zone (BMZ) staining with IgG and C3 was only seen at the roof of split-skin preparations and circulating autoantibody to the BMZ was present at a titre of 1/100. Controlled immunoblotting of epidermal extracts detected the bullous pemphigoid antigens of 230 and 180 kDa.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

Localization of endothelial proliferation and microvascular expansion in active plaque psoriasis.

Expansion of the dermal microvasculature is a prominent feature of psoriasis. Although the pathogenetic process resulting in vascular morphological changes remains unclear, considerable evidence suggests the involvement of angiogenesis. To assess the degree and site of psoriatic microvascular expansion, immunohistochemical studies were performed on paired lesional and non-lesional specimens from 10 patients with active, untreated plaque psoriasis. Five-micron thick sections were labelled with monoclonal antibody JC/70A specific for the endothelial marker CD31, and vascular quantification was achieved using hue-saturation-intensity image analysis. Assessment of vasculature in the papillary dermis (superficial plexus) demonstrated a fourfold increase in endothelial surface area of lesional compared with non-lesional skin (P < 0.01), while there was no significant increase in vasculature of the upper reticular dermis. Subsequently, 18-micron thick sections were double-labelled with MIB-1 antibody to the nuclear proliferation marker Ki-67 and JC/70A. Endothelial cell proliferation was identified in the vertical limbs of capillary loops in eight out of 10 lesional biopsies and in no non-lesional biopsies. The endothelial MIB-1 labelling index was 3.1% of total endothelial cells of the superficial plexus. These findings confirm endothelial proliferation underlying psoriatic microvascular expansion, and indicate that this process is limited to a specific site in the dermal capillary bed.

Adult↗
PubMed1996

E-selectin binds to squamous cell carcinoma and keratinocyte cell lines.

E-selectin is an endothelial adhesion molecule that binds carbohydrate epitopes on leukocytes and has been implicated in a potential pathway of tumor metastasis. Keratinocyte cell lines express similar carbohydrate epitopes, one of which, sialyl Lewis X (SL-X) is a ligand for E-selectin and is also expressed by squamous cell carcinomas (SCC) in situ. The functional role of keratinocyte selectin ligands was investigated using a soluble E-selectin chimaeric protein (pE-sel-Ig) containing pig lectin-like and epidermal growth factor-like domains fused to human IgG. After incubation of keratinocyte cell lines (A431 and SVK14) and normal keratinocytes with pE-sel Ig, binding was quantified by flow cytometry. Frozen sections of SCC were overlaid with pE-sel Ig and binding was visualized immunoenzymatically. Immunolabeling was undertaken using monoclonal antibodies (CSLEX-1 and HECA-452), which label E-selectin ligands including sialyl Lewis X. E-selectin bound strongly to A431 and SVK14 cells; the degree of binding paralleled staining intensity with CSLEX-1 antibody. HECA-452 antibody stained A431 cells strongly but SVK14 cells only weakly. Normal keratinocytes and normal epidermis did not express CSLEX-1 or HECA-452 antigens or bind E-selectin. Serial sections of SCC revealed close correlation between fusion protein binding and antibody staining. Antibody pretreatment of tumor sections with CSLEX-1 blocked fusion protein binding, whereas HECA-452 antibody only slightly reduced fusion protein binding. pE-sel Ig pretreated with YT11.1 antibody failed to bind to A431 or SVK14 cells or to SCC. These studies provide functional evidence that SL-X/E-selectin pathways may be important in SCC metastasis and that A431 and SVK14 cells provide a good model to investigate these mechanisms.

Carcinoma, Squamous Cell↗
PubMed1996

Expression of E-cadherin in human epidermal non-melanoma cutaneous tumours.

E-cadherin is a calcium-sensitive, cell-to-cell, adhesion molecule that is expressed widely in normal human epithelial tissue. Abnormal expression has been described in colorectal, breast and nasopharyngeal squamous cell carcinomas, where loss of E-cadherin is associated with an increased metastatic potential. We have examined, by standard immunohistochemical techniques using the monoclonal antibody HECD-1 (E-cadherin monoclonal antibody), the distribution of E-cadherin in normal human skin and in non-melanoma neoplastic lesions. In the normal epidermis, E-cadherin was strongly expressed on the surface of keratinocytes and specialized epithelial structures. Staining was absent from the lower pole of basal keratinocytes in contact with the basement membrane. Weak cytoplasmic staining was also noted in basal keratinocytes. No reactivity was demonstrated in dermal structures. The assessment of cutaneous tumours demonstrated an altered pattern of staining in most cases. Cell surface expression was reduced in 28 of 30 cases of basal cell carcinomas (BCC). Twenty showed an additional feature of positive staining on the dermal aspect of peripheral cells of tumour lobules. In squamous cell carcinomas (SCC) (n = 16), surface expression was attenuated in eight and absent in a further four. Strong surface expression, similar to normal skin was seen in all examples of Bowen's disease (n = 6), viral wart (n = 3), seborrhoeic keratosis (n = 3) and actinic keratosis (n = 4). This study demonstrates that, in BCC and SCC, but not in premalignant lesions, cell-surface expression of E-cadherin is reduced, consistent with the observation that the loss of E-cadherin is associated with tumour invasion.

Cadherins↗
PubMed1995

Detection of circulating adhesion molecules in erythrodermic skin disease.

BACKGROUND: Diagnosis of the underlying dermatosis in erythroderma is often difficult. The cause of increased mortality in erythroderma, particularly in relation to infection, is incompletely understood. OBJECTIVE: We investigated the potential diagnostic use of circulating intercellular adhesion molecule-1 (cICAM-1), vascular cell adhesion molecule-1 (cVCAM-1), and E-selectin (cE-selectin) levels in erythroderma. METHODS: cICAM-1, cVCAM-1, and cE-selectin were measured by enzyme-linked immunosorbent assay in 14 patients with erythroderma of known cause and in 17 control subjects. Levels were correlated with other markers of the inflammatory response. RESULTS: In erythroderma median cICAM-1, cVCAM-1, and cE-selectin levels were significantly elevated, but no difference was found between values in patients with eczema and values in those with psoriasis. Circulating adhesion molecule levels did not correlate with erythrocyte sedimentation rate or total white blood cell count. CONCLUSION: cICAM-1, cVCAM-1, and cE-selectin were detectable in patients with erythroderma but were not differential diagnostic use in this study. Because in vitro these molecules may interfere with normal cell adhesion mechanisms, we speculate that they may contribute to the immunosuppressive state in these patients.

Adult↗