Ultraviolet-B irradiation decreases IFN-gamma and increases IL-4 expression in psoriatic lesional skin in situ and in cultured dermal T cells derived from these lesions

Type 1 cytokine producing T cells play an important role in the pathogenesis of psoriasis. Ultraviolet-B (UVB) irradiation is effective in the treatment of this disease. In normal skin, UVB causes a change in dermal microenvironment, leading to a decrease of IFN-gamma expressing type 1 T cells and a concurrent increase of IL-4 expressing type 2 T cells. The aim of this study was to show whether UVB irradiation causes a like-wise shift of type 1 and type 2 responses in psoriatic skin. For this purpose, biopsies were obtained from the lesional skin of psoriatic patients before, 2 days and 14 days after a single exposure to 4 MED UVB. Sections from these biopsies were immunostained (CD3, IFN-gamma and IL-4) or RNA was extracted and analyzed for the expressions of IFN-gamma and IL-4 by PCR. In addition, primary cultures of T cells from dermal cell suspensions were stained intracellularly for IFN-gamma and IL-4 expression and CD4+ and CD8+ T subsets were analyzed by flow cytometry. IFN-gamma was abundantly expressed in situ before irradiation and decreased in all patients after UVB irradiation, whereas IL-4 expression was variably expressed before irradiation and increased in different degrees after irradiation. Cytokine mRNA expressions determined by PCR showed a clear decrease of IFN-gamma and increase of IL-4 following UVB irradiation. Both CD4+ and CD8+ dermal T cells were found to produce less IFN-gamma and more IL-4 following UVB irradiation as determined by flow cytometry. Decrease in IFN-gamma expression and increase in IL-4 expression of dermal T cells in psoriatic lesions after UVB irradiation may lead to decrease in local immunoreactivity. These changes could be part of the therapeutic effects of UVB on psoriasis.     

T cells in psoriatic lesional skin that survive conventional therapy with NB-UVB radiation display reduced IFN-γ expression

The type 1 T cell-derived cytokine interferon (IFN-) is overexpressed in psoriatic lesional skin. Recently, we have shown that a single high erythemal dose of broad-band ultraviolet B (UVB) irradiation reduces type 1 and favors type 2, i.e. interleukin-4 (IL-4), cytokine expression in normal and psoriatic skin. In this study, we wanted to see whether conventional narrow-band UVB (NB-UVB) therapy (i.e. repeated exposure to nonerythemal doses) also affects type 1/type 2 cytokine expression of T cells present in chronic plaque type psoriatic lesions. Staining of cryostat sections showed decreased expression of both IFN- and IL-4 in situ after NB-UVB therapy. CD4⁺ dermal T cell lines, derived from psoriatic lesional skin, displayed significantly decreased intracellular IFN- expression during and after NB-UVB therapy as compared to pretreatment values. Intracellular IL-4 expression was increased in most patients after therapy. Analysis of the supernatants of these stimulated dermal T cells revealed that IFN- production decreased significantly following NB-UVB therapy, whereas IL-4 expression increased in the T cell supernatants from most patients, confirming the intracellular determinations. In addition, IL-10 and transforming growth factor- levels in the supernatants appeared to be increased in the majority of patients following UVB therapy. Apart from the well-known killing effect of UVB on T cells, our results show that the improvement in psoriatic skin following NB-UVB therapy is also due to a reduced capacity of the surviving dermal T cells to express the proinflammatory cytokine IFN-.     

Decreased neutrophil skin infiltration after UVB exposure in patients with polymorphous light eruption

UV radiation, in particular UVB, suppresses the skin immune response. In patients with polymorphous light eruption (PLE) the skin immune response seems activated after UV exposure. Typical PLE skin lesions can occur as early as several hours after UV exposure. In healthy volunteers, neutrophils infiltrate the skin shortly after UV exposure. The kinetics and mechanisms of neutrophil infiltration in the skin of PLE patients after UVB exposure was studied. Skin biopsies at 0, 3, 6, and 18 h were taken from five PLE patients and six healthy controls after irradiation with three minimal erythema dose UVB. Furthermore, neutrophils were isolated from blood of five PLE patients and six healthy controls to test their chemotactic activity. Immunohistochemical analysis showed a significant decreased neutrophil infiltration in PLE skin after UVB irradiation compared with healthy controls (p<0.05). In both healthy controls and PLE patients, after UVB irradiation, ICAM-1 and E-selectin expression on endothelial cells increased at 6 h after irradiation. Blood neutrophil chemotactic response towards IL-8 and C5a, as well as the expression of cell surface markers involved in adhesion and chemotaxis, was not different between PLE patients and healthy controls. In conclusion, PLE is marked by a decreased skin infiltration of neutrophils after UVB irradiation, possibly leading to a diminished neutrophil-induced suppression.     

Perforin expression is upregulated in the epidermis of psoriatic lesions

BACKGROUND: There are currently very few data regarding the role of cell-mediated cytotoxicity in psoriasis. Both cytotoxic T lymphocytes and natural killer (NK) cells mediate cytotoxicity reactions, mainly by two distinct pathways, the perforin/granzyme and the Fas/Fas ligand pathway. OBJECTIVES: To study the expression and distribution of perforin, T- and NK-cell subsets in psoriatic lesional and nonlesional skin. METHODS: Skin biopsy specimens from both lesional and nonlesional skin of 11 patients with chronic plaque psoriasis and eight healthy controls were analysed by immunohistochemistry. RESULTS: We found a significant increase in CD4+ and CD8+ cells in psoriatic lesions compared with nonlesional and healthy skin. The expression of CD16+ NK cells was significantly lower in lesions compared with healthy skin. Perforin expression was significantly enhanced in the epidermis of psoriatic lesions. CONCLUSIONS: Perforin expression is upregulated in the epidermis of psoriatic lesions, suggesting a potential role for perforin in the creation of the psoriatic plaque.     

Expression of the T-cell activation antigens CD27 and CD28 in normal and psoriatic skin

Activated T lymphocytes are thought to be involved in the pathogenesis of psoriasis. From studies with peripheral blood T lymphocytes it is known that T cells show a decrease in membrane expression of CD27 molecules during continuous antigenic stimulation. The T-cell activation molecule CD28 is thought to be involved in the transduction of an antigen-non-specific costimulatory signal. Therefore, in order to elucidate further the pathogenesis of psoriasis we studied the expression of CD27 and CD28, together with CD4, CD8 and CD45RA in this benign inflammatory dermatological disease. We used immunohistochemical techniques to determine absolute numbers of T lymphocytes and expression of these T-cell activation and T-subset-specific molecules in normal (n= 7), uninvolved perilesional (n= 7) and lesional psoriatic (n= 7) skin. We found that not only lesional but also clinically uninvolved perilesional skin showed an increased number of T cells. Further, immunohistochemical studies showed that CD27 is expressed by a minority of normal skin T cells, while in lesional psoriatic skin, expression was even lower, and almost absent in perilesional skin sections. In contrast to normal skin, both perilesional and lesional psoriatic skin contained no CD28 positive T cells. In lesional psoriatic skin, however, T cells showed predominantly the CD4 phenotype, while in perilesional skin CDS positive T cells were dominant. Two conclusions were reached: first, the absolute number of T cells, their CD27, CD28 and CD45RA expression, and the influx of CD8 positive T cells, indicate that perilesional psoriatic skin is different from normal and lesional psoriatic skin; and secondly, the data on CD27 and CD28 suggest that not only lesional but also perilesional psoriatic skin is subject to continuous antigenic stimulation, thus leading to decreased CD27 and CD28 expression on skin T cells.     

Increased levels of enkephalin following natural sunlight (combined with salt water bathing at the Dead Sea) and ultraviolet A irradiation

The opioid peptides enkephalins have been shown to modulate inflammatory responses and keratinocyte proliferation and differentiation. Furthermore, increased levels of enkephalin are present in psoriatic lesions. The purpose of the present study was to determine the effect of natural sunlight combined with salt water bathing in the Dead Sea on the methionine-enkephalin (e.n.k.) level in psoriatic skin. Ten patients were treated at the Dead Sea for 4 weeks, and keratotome biopsies were obtained before and after treatment. The amount of enkephalin extracted from the biopsies was measured by radioimmunoassay. Treatment at the Dead Sea resulted in a complete clinical clearance of psoriasis, and immunohistochemical stainings of lesional skin showed that the treatment decreased both epidermal thickness/parakeratosis and the dermal infiltration of CD3- and CD68-positive cells, although the number of CD3- and CD68-positive cells became normal in only two of the 10 cases. However, there was only a slight decrease in the mean enk levels (21%). Furthermore, the level of enk was high in non-lesional psoriatic skin after treatment at the Dead Sea, and immunostaining showed that, in some patients, the treatment induced a mild epidermal hyperplasia and a dermal infiltration of CD3- and CD68-positive cells. Enkephalin-like immunoreactivity was detected in the cytoplasm of both epidermal keratinocytes and dermal infiltrating cells. To determine whether the relatively high skin enk levels after treatment at the Dead Sea was caused by ultraviolet (UV) radiation, normal volunteers were exposed to a single dose of UVA and UVB (2 minimal erythema doses). UVA, but not UVB, irradiation stimulated the mean enk level in the irradiated skin by about sixfold. Furthermore, multiple whole-body UVA irradiations not only resulted in increased skin levels of enk, but also in increased plasma levels. In conclusion, natural sunlight combined with salt water bathing cleared psoriasis without causing a significant decrease in lesional enk levels. Furthermore, non-lesional enk levels were increased. These findings may be the result of a direct stimulatory effect of UVA irradiation on enk formation in the skin. It is possible that the increased circulating levels of enk after UV exposure may contribute to the beneficial effects of UVA irradiation.     

Reappraisal of in situ immunophenotypic analysis of psoriasis skin: interaction of activated HLA-DR+ immunocompetent cells and endothelial cells is a major feature of psoriatic lesions

Psoriasis is an inflammatory skin disease of unknown aetiology. Many observations indicate that T cells play an important role in the pathogenesis of the disease. Upregulation of MHC class-II molecules on immunocompetent cells, endothelial cells and keratinocytes on lesional psoriatic skin has been regarded as a hallmark of the disease. However, there is some controversy in the literature regarding the cell types expressing class-II molecules and there is limited information about the presence of immune cells other than T cells and antigen presenting cells in the cellular infiltrates of psoriatic skin. We therefore reinvestigated the subject using immunocytochemical single and multiple staining techniques. In agreement with earlier reports, our studies showed that the cellular infiltrates in lesional skin consist largely of HLA-DR⁺/IL-2R⁺ T cells, HLA-DR⁺/CD1a⁺ Langerhans cells, and HLA-DR⁺/CD68⁺ macrophages. We found increased HLA-DR expression mostly on immunocompetent cells and endothelial cells, but no prominent HLA-DR expression on keratinocytes in lesional psoriatic skin. Upregulation of HLA-DR on endothelial cells and in mononuclear infiltrates was also evident in the non-lesional skin of psoriatic patients as compared with normal controls. B cells and natural killer cells were also found in the cellular infiltrates in lesional psoriatic skin. In spite of the presence of a large amount of activated T cells in the epidermis, we found that HLA-DR expression on keratinocytes was not a major feature of psoriatic skin.     

Infiltrating cells and related cytokines in lesional skin of patients with chronic idiopathic urticaria and positive autologous serum skin test

Abstract:  In approximately one-third of patients with chronic idiopathic urticaria (CIU), autoantibodies against the high-affinity IgE receptor and/or against IgE can be detected and a wheal-and-flare response can be provoked by the intradermal injection of autologous serum (ASST). In this study we aimed to further characterize the inflammatory response observed in the subgroup of CIU patients with positive ASST and serum-evoked histamine-release in vitro from basophils in comparison with unaffected skin and healthy donors. An immunohistochemical analysis of infiltrating cells (CD4, MPO, EG1, EG2, tryptase), cytokines (IL-4, IL-5, IFN-γ), chemokines and chemokine receptors (IL-8, CCR3, CXCR3), and adhesion molecules (ICAM-1, VCAM-1, ELAM-1) was performed on seven selected patients (four males and three females; median age: 45 years; range: 22–57) and five healthy donors. Cytokine evaluation was also performed in five psoriatic patients to obtain an additional control .
In spontaneous wheals we observed an increased number of CD4+ T lymphocytes when compared with the controls, and an increased number of neutrophils and eosinophils, whereas mast cells did not show a significant variation. A significant expression for IL-4 and IL-5 could only be observed in lesional skin, while IFN-γ showed a slight expression in the same site. Chemokine receptors CCR3 and CXCR3 did not show a defined polarized response in either lesional or unaffected skin. An increased expression of all cellular adhesion molecules (CAMs) studied was detected in spontaneous wheals. The lack of a significant difference in the expression of tryptase + mast cells, T lymphocytes, IL-8, CXCR3 and CCR3, a few CAMs between the lesional and unaffected skin of CIU patients suggests a wide immunological activation that involves not only lesional tissues, but possibly extends to the whole of the skin's immune system.     

Monochromatic excimer light (308 nm): an immunohistochemical study of cutaneous T cells and apoptosis-related molecules in psoriasis

BACKGROUND: Various types of UVB radiation source (290-320 nm) are used in treating psoriasis and their therapeutic mechanism has been attributed to immunosuppressive properties. Recently, a new UVB source generated by a 308-nm excimer laser has been introduced for the treatment of psoriasis. OBJECTIVE: In this study we investigated the immunohistochemical evaluation of T cells and the expression of various apoptosis-related molecules in the psoriatic hyperproliferative skin before and after treatment with 308-nm monochromatic excimer light (MEL). METHODS: Ten patients (three women and seven men), ranging in age from 29 to 79 years, affected by plaque-type psoriasis vulgaris, were treated with MEL. Biopsies from psoriatic lesions of MEL-treated sites were taken before, 24 h and/or 48 h after the first irradiation and analysed by the immunophosphatase alkaline technique (APAAP). RESULTS: MEL treatment was found to cause a significant decrease in the rate of proliferation of keratinocytes and a relevant depletion of T cells in all psoriatic lesions, 48 h after the first irradiation: 308 nm light eliminated T cells from the psoriatic epidermis and also from the dermis, highlighting the ability of this UVB source to penetrate the skin compared with normal UVB and establish direct cytotoxic action on T cells infiltrating skin lesions. Rapid clearing of psoriatic lesions involves potential molecular targets of UVB in T cells including p53, which is upregulated after direct irradiation with 308-nm UVB. Moreover, Bcl-2 expression in healing psoriasis epidermis after MEL treatment is significantly decreased compared with untreated skin and the TUNEL (TdT-mediated dUTP-biotin nick end labelling) technique revealed the presence of relevant apoptotic keratinocytes in the irradiated epidermis. CONCLUSIONS: These results indicate that psoriatic skin after monochromatic excimer light therapy is associated with significant T-cell depletion and alterations of apoptosis-related molecules accompanied by a decreased proliferation index and clinical remission.     

Differential expression of cytokines in UV-B-exposed skin of patients with polymorphous light eruption: correlation with Langerhans cell migration and immunosuppression

BACKGROUND: Disturbances in UV-induced Langerhans cell migration and T helper (T(H)) 2 cell responses could be early steps in the pathogenesis of PLE. OBJECTIVE: To establish whether UV-B exposure induces aberrant cytokine expression in the uninvolved skin of patients with polymorphous light eruption (PLE). DESIGN: Immunohistochemical staining and comparison of microscopic sections of skin irradiated with 6 times the minimal dose of UV-B causing erythema and the unirradiated skin of patients with PLE and of healthy individuals. SETTING: University Medical Center (Dutch National Center for Photodermatoses).Patients Patients with PLE (n = 6) with clinically proven pathological responses to UV-B exposure and normal erythemal sensitivity. Healthy volunteers (n = 5) were recruited among students and hospital staff. MAIN OUTCOME MEASURES: Expression of cytokines related to Langerhans cell migration (interleukin [IL] 1, IL-18,and tumor necrosis factor [TNF] alpha); T(H)2 responses (IL-4 and IL-10); and T(H)1 responses (IL-6, IL-12, and interferon gamma). Double staining was performed for elastase (neutrophils), tryptase (mast cells), and CD36 (macrophages). RESULTS: The number of cells expressing IL-1beta and TNF-alpha was reduced in the UV-B-exposed skin of patients with PLE compared with the skin of healthy individuals (P<.05 for TNF-alpha). No differences were observed in the expression of T(H)1-related cytokines but fewer cells expressing IL-4 infiltrated the epidermis of patients with PLE 24 hours after irradiation (P =.03). After UV exposure TNF-alpha, IL-4, and, to a lesser extent, IL-10 were predominantly expressed by neutrophils. CONCLUSIONS: The reduced expression of TNF-alpha, IL-4, and IL-10 in the UV-B-irradiated skin of patients with PLE appears largely attributable to a lack of neutrophils, and is indicative of reduced Langerhans cell migration and reduced T(H)2 skewing. An impairment of these mechanisms underlying UV-B-induced immunosuppression may be important in the pathogenesis of PLE.     

Repeated low-dose ultraviolet (UV) B exposures of humans induce limited photoprotection against the immune effects of erythemal UVB radiation

BACKGROUND: Exposure of human subjects to ultraviolet (UV) B radiation causes immunosuppression. Most experiments to date have not tested the effects of low daily doses of UVB radiation. OBJECTIVES: To ascertain whether photoprotection against several UV-induced immune effects might develop following repeated exposure. METHODS: Groups of approximately 30 healthy individuals were given whole-body UVB irradiation on each of 10 consecutive days with 0.7 minimal erythema dose, or whole-body irradiation as before followed by a single erythemal UVB dose on a small body area, or irradiated only with a single erythemal UVB dose on a small body area, or were not irradiated. They were sensitized with diphenylcyclopropenone (DPCP) 24 h after the final dose, and skin biopsies collected to assess cytokine mRNA expression and the number of cells with thymine dimers and expression cyclooxygenase (COX)-1 and COX-2. RESULTS: The contact hypersensitivity (CHS) response to DPCP was significantly lower in the three irradiated groups compared with the unirradiated controls, while cutaneous interleukin (IL)-1beta, IL-6, IL-10 and tumour necrosis factor-alpha mRNAs, COX-1 and COX-2 and thymine dimers were all significantly higher. When the single erythemal UVB dose was given following the repeated low exposures, a slight downregulation in cytokine expression and thymine dimer formation was indicated. CONCLUSIONS: The repeated low doses of UVB protected to a limited extent against the effects of an erythemal UVB dose on cytokine expression and thymine dimer formation, but not on CHS or COX enzymes.     

UM4D4+ (CDw60) T cells are compartmentalized into psoriatic skin and release lymphokines that induce a keratinocyte phenotype expressed in psoriatic lesions

UM4D4 (CDw60), the surface molecule of a novel antigen-independent T-cell activation pathway, was found to be highly expressed on lesional psoriatic T cells. To examine whether UM4D4 represents a T-cell activation pathway for psoriatic T cells, a T-cell line was initiated from an acute skin lesion and cloned by limiting dilution. Clonality was verified by analysis of T-cell receptor gene rearrangement. All T-cell clones tested, whether CD4+2H4+CD8-, CD4+2H4-CD8-, or CD4-CD8+CD11b-, expressed UM4D4 and were activated by the monoclonal antibody anti-UM4D4. Lesional psoriatic T-cell clones were heterogeneous in the degree of anti-UM4D4-induced proliferation and in their production of IL-2 and gamma-interferon. Lymphokines released by anti-UM4D4 activation were capable of inducing ICAM-1 and HLA-DR expression on cultured normal keratinocytes. Thus, the high expression of UM4D4 on T-cells in psoriatic skin provides an alternative mechanism for T-cell activation that may be operative in the psoriatic lesional milieu. Indeed, activation of lesional T-cells through the UM4D4 molecule resulted in release of lymphokines that directly induced keratinocytes to express a phenotype displayed in psoriatic skin lesions.     

Neutrophils infiltrating ultraviolet B-irradiated normal human skin display high IL-10 expression

Exposure to an erythemal dose of ultraviolet B (UVB) is known to induce interleukin (IL-10) expression in human skin. It is generally believed that this IL-10 is predominantly expressed by CD11b⁺HLA-DR⁺ macrophages that infiltrate the UVB-exposed skin. This cytokine is presumed to contribute to the immunosuppressive effects of UVB by inhibiting cell-mediated immune responses. We recently demonstrated that neutrophils, which also invade UVB-irradiated skin, express CD11b and HLA-DR as well. In addition, we showed that the presence of these neutrophils affects T-cell responses in primary T-cell cultures derived from UVB-exposed skin. Since neutrophils invade UVB-exposed skin and, like macrophages, express CD11b and HLA-DR, we sought to determine whether neutrophils represent another source of IL-10. Skin biopsies were obtained from four healthy volunteers before and 2 days after exposure to four minimal erythema doses of UVB. A series of immunohistochemical double-staining procedures using the following markers was performed: IL-10, CD11b, HLA-DR, CD36, neutrophil elastase, and CD66b. As expected IL-10 could be detected in CD11b⁺HLA-DR⁺CD36⁺ macrophages in the epidermis and dermis of UVB-exposed skin. Surprisingly, the majority of the abundant IL-10 expression was found in CD11b⁺HLA-DR⁺elastase⁺CD66b⁺ neutrophils. Cytospin preparations from dermal cell suspensions confirmed the IL-10 expression by neutrophils displaying characteristic multilobular nuclei. Thus, neutrophils in UVB-exposed skin express IL-10 and should be recognized as active coplayers in the creation of the UVB-induced immunosuppressive microenvironment.     

Increased expression of adhesion receptors in both lesional and non-lesional psoriatic skin

Adhesion receptors and their ligands play a vital role in the immune system. We studied the expression of different adhesion receptors, using single- and double-staining immunohistochemical techniques, in both lesional and non-lesional skin specimens from seven psoriasis patients and in skin biopsy specimens from eight normal healthy controls. Our results showed an overall increased expression of several adhesion receptors in both lesional and non-lesional psoriatic skin. We consistently found an increased expression in particular of ICAM-1 and E-selectin on endothelial cells, and ICAM-1 on T cells and Langerhans cells. In contrast, a weak expression of VCAM-1 was found on endothelial cells and mononuclear cells in lesional psoriatic skin specimens alone. Interestingly, LFA-1 was also expressed on Langerhans cells, with a greater frequency in skin from lesional than from non-lesional sites, but was never expressed in skin from normal healthy individuals. Furthermore, significantly increased numbers of Langerhans cells and T cells with a positive reactivity for MAb HECA-452 were found in both lesional and non-lesional psoriatic skin. We hypothesize that the enhanced expression of adhesion receptors on migrating immunocompetent cells and endothelial cells of psoriatic skin in general facilitates the increased influx of activated T lymphocytes and other immunocomponent cells into the skin, and thus underscores the generalized character of the disease.     

Increased neutrophil adherence in psoriasis: role of the human endothelial cell receptor Thy-1 (CD90)

The chronic inflammatory skin disease psoriasis is characterized by prominent skin infiltration by neutrophils and microabscess formation. The adhesion of leukocytes and subsequent transmigration through the activated endothelium is one prerequisite for the accumulation of these cells in skin. In recent studies, the human Thy-1 (CD90) was characterized as an adhesion molecule on activated endothelial cells (ECs) mediating the adhesion of neutrophils via the interaction with the beta2-integrin Mac-1. Based on these novel findings, we compared the roles of Thy-1 and ICAM-1 in the adhesion of neutrophils from patients with psoriasis to activated ECs. The adhesion of peripheral blood neutrophils of patients suffering from psoriasis to Thy-1-transfected cells as well as to activated, Thy-1-expressing human dermal microvascular ECs (HDMECs) is distinctly increased in comparison to the adhesion of neutrophils from healthy controls. In contrast, adherence of psoriatic neutrophils to ICAM-1 transfectants is, if at all, only slightly enhanced compared to healthy controls. The interaction of healthy as well as psoriatic polymorphonuclear cells to Thy-1 transfectants and HDMECs was significantly inhibited by blocking Thy-1 on ECs or its receptor Mac-1 on neutrophils, indicating the importance of this interaction for the adhesion of neutrophils to activated endothelium. In conclusion, our data indicate that the adhesion of neutrophils to activated ECs mediated by Thy-1/Mac-1 interaction is an important attachment mechanism facilitating their subsequent migration into lesional psoriatic skin.     

The majority of epidermal T cells in Psoriasis vulgaris lesions can produce type 1 cytokines, interferon-gamma, interleukin-2, and tumor necrosis factor-alpha, defining TC1 (cytotoxic T lymphocyte) and TH1 effector populations: a type 1 differentiation bias is also measured in circulating blood T cells in psoriatic patients

Psoriasis vulgaris is a skin disease potentially mediated by pro-inflammatory cytokines produced by type 1 lesional T cells. The capability of individual T cells to produce these cytokines in lesional skin is not known. In this study we measured the ability of lesional and peripheral blood T cells to produce intracellular interferon-gamma, tumor necrosis factor-alpha, interleukin-2, interleukin-4, and interleukin-10 proteins as detected by flow cytometric analysis. Cytokine synthesis was induced by activation with ionomycin/phorbol myristate acetate (in the presence of Brefeldin A, which inhibits the exocytosis of these cytokines). After stimulation, we found relatively high percentages of epidermal CD8 and CD4 T cells capable of producing interferon-gamma, tumor necrosis factor-alpha, and interleukin-2, whereas few T cells, < 11%, expressed interleukin-4 or interleukin-10. Hence both CD8+ and CD4+ T cells are capable of type 1 effector functions (TC1 and TH1, respectively). This activation scheme was repeated on peripheral blood T cells from psoriatic patients versus healthy controls, where we also found a type 1 bias. In order to evaluate quantitatively the type 1 cytokine bias, we compared the frequency of type 2 interleukin-4 producing versus type 1 interferon-gamma producing T cells in our assay and found a shift towards type 1 producing cells. This shift reveals a type 1 differentiation bias in both lesional areas and in the peripheral blood, which may indicate an imbalance within the T cell population, which is contributing to the chronic or sustained immunologic activation of T cells found in this disease.     

银屑病患者皮损及非皮损部位粘附分子免疫组化研究

目的　为了更好地了解浸润 T淋巴细胞和内皮细胞粘附分子的原位表达在银屑病皮损中的相互关系。方法　采用免疫组化染色方法研究银屑病皮损部位和非皮损部位的浸润 T淋巴细胞亚群和内皮细胞粘附分子 (ICAM- 1,EL AM- 1,VCAM- 1)的原位表达情况。结果　银屑病患者皮损部位 T细胞亚群和内皮细胞粘附分子的原位表达均显著高于非皮损部位 ,而且浸润 T淋巴细胞亚群的细胞密度和内皮细胞粘附分子的原位表达程度呈显著正相关。与正常人相比 ,银屑病非皮损部位和经外用皮质类固醇激素治疗后外观正常的皮肤内皮粘附分子仍呈上调表达。结论　银屑病患者皮肤真皮血管内皮细胞粘附分子的异常上调表达是造成银屑病复发的原因之一。     

T cells and mast cells as a major source of interleukin-13 in atopic dermatitis

BACKGROUND: Interleukin (IL)-13 is a T-cell-derived cytokine that shares several functions with IL-4, including the induction of immunoglobulin E synthesis. Recent studies suggest that cytokines expressed locally in the skin play several critical roles in atopic dermatitis (AD), however, little is known about the role of IL-13 in AD lesions. OBJECTIVES: The present study was designed to characterize the involvement of IL-13 in AD in the skin and peripheral blood mononuclear cells (PBMC). METHODS: Using lesional and nonlesional skin from adult AD patients and normal skin from healthy volunteers, we performed RT-PCR, in situ RT and immunostaining to determine the IL-13 expression at the mRNA and protein levels. The actual numbers of IL-13 expressing cells in biopsy specimens were counted under the microscope. IL-13 mRNA expression in PBMC from AD patients and healthy volunteers was examined by RT-PCR analysis. RESULTS: IL-13 mRNA expression was detected by RT-PCR in lesional and nonlesional skin and in PBMC from AD patients, but not in normal skin or PBMC from healthy volunteers. In AD lesional skin, numerous IL-13 mRNA-positive cells were demonstrated by in situ RT, and similar numbers of IL-13-positive cells were also detected immunohistochemically. Smaller numbers of IL-13-positive cells were observed in AD nonlesional skin and in normal skin. The differences in the numbers of IL-13-expressing cells between lesional and nonlesional skin were statistically significant. Double immunostaining revealed that IL-13 was produced in approximately 40% of T cells and 20% of mast cells in AD lesional skin, suggesting that T cells and mast cells are major sources of IL-13 in AD lesions. CONCLUSION: IL-13 may play a local as well as a systemic role in the development of AD lesions.     

Reduced IL-1Ra/IL-1 ratio in ultraviolet B-exposed skin of patients with polymorphic light eruption

Abstract:  Polymorphic light eruption (PLE) is a putative delayed-type allergic reaction to (solar) ultraviolet (UV) exposure. Inadequate immune suppression after UVB-induced sunburn appears to be associated with reduced trafficking of Langerhans cells (LCs) out of and neutrophils into the epidermis of patients sensitive to UVB provocation of PLE. Therefore, we investigated whether pro-inflammatory and chemotactic cytokines are differentially expressed in UVB-irradiated skin of UVB-provocable PLE patients ( n  = 6) and age- and gender-matched healthy controls ( n  = 6). Interstitial interleukin-1α (IL-1α), IL-1β, IL-1Ra, IL-4, IL-8, tumor necrosis factor-α (TNF-α), macrophage inflammatory protein 1-α (MIP-1α), MIP-1β and monocyte chemotactic protein-1 (MCP-1) were measured in suction blister fluid raised 16 h after exposure to 0, three and six minimal erythemal UVB doses. In unirradiated skin, the IL-1Ra levels were significantly lower in the PLE patients than in controls ( P  < 0.05). IL-8 and TNF-α levels increased strongly upon UVB irradiation in both groups. No differential shifts in cytokine profiles were found that could explain a reduced trafficking of Langerhans cells and neutrophils in PLE patients. Dose-trend analyses showed that UVB irradiation caused significant increases in IL-1α in both groups, and that the levels of IL-1α and IL-1β were on average twofold higher in the PLE group ( P  = 0.03 and P  = 0.004, respectively.). Accordingly, the ratios of IL-1Ra over IL-1α and over IL-1β were overall lower in the skin of PLE patients ( P  = 0.015 and P  < 0.001, respectively.). This shift in cytokines in UVB-irradiated skin of PLE patients reveals an amplified early pro-inflammatory cytokine response, which may contribute to the allergic reaction to UVB radiation.     

The development of manifest psoriatic lesions is linked with the invasion of CD8+ T cells and CD11c+ macrophages into the epidermis

Koebner response was studied in 35 psoriatic patients. Two punch biopsies per patient were taken from non-lesional psoriatic skin before, and 6 h, 2 days, 7 days, 14 days and 21 days after, tape stripping. Alterations in the numbers of CD1+ Langerhans cells, CD4+ and CD8+ T cells and CD11c+ macrophages were mapped morphometrically. Results were compared with lesional and non-lesional psoriatic skin, and control skin. Nine of 35 patients were Koebner-positive. No statistically significant differences were noted between non-lesional psoriatic and control skin. CD4+ T cells increased in number 2 days after trauma in both the epidermis and the dermis, whereas epidermal CD8+ T cells and CD11c+ macrophages increased only in the Koebner-positive lesional skin after 7 days. The changes in lesions induced by tapestripping resembled those seen in lesional psoriatic skin (mature plaques). The number of CD1+ cells increased in mature psoriatic lesions only. It seems possible that trauma per se stimulates the accumulation of CD4+ T cells at the site of injury, but the development of manifest psoriatic lesions correlates with invasion of CD8+ T cells and CD11c+ macrophages into the epidermis.