Pathomechanismen der Auslösephase der allergischen Kontaktdermatitis

Allergic contact dermatitis (ACD) is a T‐cell mediated, antigen‐specific inflammatory response to repeated epicutaneous exposure to haptens. Two immunologically distinct sequential steps are required to produce the clinical picture of ACD. In the sensitization phase, naïve antigen‐specific T cells are primed and differentiate into memory or effector T cells. In the elicitation phase, reapplication of the same hapten leads to local recruitment of hapten‐specific T cells which are cytotoxic, release cytokines and recruit other inflammatory cells. These events lead to clinically visible tissue inflammation characterized by edema, erythema, scaling, and blistering. For the clinician, the effector phase is especially important, because sensitization is generally asymptomatic, whereas elicitation produces the clinical picture of ACD. Detailed knowledge about the mechanisms of the elicitation phase of ACD is needed in order to develop novel therapeutic approaches.     

Neue Entwicklungen in der medizinischen Mykologie

Not only have the systemic mycoses clearly increased in number but also mycoses of the skin are more common than presumed in the past. Today onychomycosis is found in up to 10% of human beings. Onychomycosis can compromise quality of life markedly. Common tinea pedis is one of the most important risk factors for erysipelas of the lower legs. The clinical presentation of oral candidosis in HIV-infected patients is changing; Candida dubliniensis has been identified as another important causative microorganism. Onychomycosis today in most cases can be cured using terbinafine or itraconazole. When choosing the ideal drug in a given case, both the benefit risk ratio and the benefit cost ratio have to be taken into account. Liposomally encapsulated amphotericin B represents a major breakthrough in the treatment of systemic mycoses or fever of unknown origin. The same applies to liposomally encapsulated econazole with respect to tinea pedis. In regard to the pathogenesis of Candida infections the family of secreted aspartic proteinases plays a major role as a virulence factor and possible future target for antimycotic treatment.     

Tumorimmunabwehr und Autoimmunität: Erkenntnisse für die Entwicklung moderner Melanomvakzinen aus tierexperimentellen Studien

Summary: Some patients with advanced melanoma benefit from non‐specific immunotherapy. The molecular identification of melanoma antigens allows for the development of specific vaccines. Animal studies allow for insights into the possibility to generate and maintain immunity against melanoma antigens. It has become clear that the stimulation of melanoma‐specific T cells is limited by mechanisms responsible for peripheral immune tolerance. Novel genetic vaccine strategies are able to circumvent immune tolerance in laboratory mice. This requires the adjuvant application of dendritic cells or the fusion of the antigen‐encoding cDNA with immunostimulatory proteins. Additionally, melanoma‐specific T cells have to be attracted into the tumor tissue with the help of proinflammatory signals in a therapeutic setting. We believe that these lessons learned in the murine system are of great importance for the future development of melanoma vaccines for application in man.     

Immunotherapy of malignant melanoma – Basic principles and novel therapeutic approaches

Immunotherapy has assumed increasing importance in the therapy of malignant melanoma. The main reason is the high immunogenicity of the tumor itself, so that an immune response against the tumor often exists even without immune stimulation. The goal of modern immunotherapeutic approaches is to augment these anti‐tumoral immune reactions to fight the tumor. Despite multiple successes, the ultimate breakthrough in the therapy of malignant melanoma has not yet been achieved. This overview summarizes the reasons for this lack of success and highlights future strategies for more successful therapy of malignant melanoma.     

A tale of two plaques: convergent mechanisms of T-cell-mediated inflammation in psoriasis and atherosclerosis

Psoriasis and atherosclerosis are diseases in which effector T lymphocytes such as Helper T cells type 1 (Th1) and 17 (Th17) play integral roles in disease pathogenesis and progression. Regulatory T cells (Treg) also exert clinically important anti-inflammatory effects that are pathologically altered in psoriasis and atherosclerosis. We review the immunological pathways involving Th1, Th17 and Treg cells that are common to psoriasis and atherosclerosis. These shared pathways provide the basis for mechanisms that may explain the epidemiologic observation that patients with psoriasis have an increased risk of heart disease. Improved understanding of these pathways will guide future experiments and may lead to the development of therapeutics that prevent or treat cardiovascular complications in patients with psoriasis.     

Primary human keratinocytes efficiently induce IL‐1‐dependent IL‐17 in CCR6+ T cells

Abstract: Keratinocytes and activated T cells interact in skin inflammation by virtue of chemokines and cytokines. T cell‐derived IL‐17 has been described to play an important role in the course of psoriatic inflammation. In this study, we addressed how keratinocytes influence the secretion of IL‐17 in autologous T cell subsets. We found that a co‐culture of autologous keratinocytes and T cell‐receptor‐stimulated T cells markedly enhanced the production of IL‐17. Besides the importance of direct cell contact, this effect was mainly mediated by IL‐1 and could be blocked by the IL‐1 antagonist anakinra. An additional increase in IL‐17 production by IL‐23 was only seen in the presence of IL‐1, which thus plays a permissive role for the action of IL‐23. Importantly, co‐culture of keratinocytes with CCR6+ CD4+ T cells that are enriched for Th17 cells resulted in significantly higher IL‐17 production compared to co‐culture with CD4+ T cells.     

Novel pharmacological approaches in the treatment of psoriasis

Progress in the understanding of psoriasis as a T-cell mediated inflammatory disease has led to the development of new immunomodulatory therapies. Currently the main focus is on the so-called biologics (or biological agents), including fusion proteins, monoclonal antibodies, cytokines and selective receptors. They mainly target single steps in the complex cascade of humoral and cellular inflammatory immuno-mechanisms that finally lead to the accelerated growth of epidermal and vascular cells in the psoriatic lesions. The most promising and advanced biological agents are discussed along with their influence on the critical pathophysiological steps in psoriasis, including depletion of T cells, blockade of initial T-cell activation and T-cell receptor (TCR) stimulation, blockade of costimulatory signals and T-cell proliferative signals as well as restoration of the T helper type 1 (Th1)/Th2 balance by diminishing type 1 cytokines and administration of type 2 cytokines. In addition to the biological agents, further development of 'classical' dermatological therapies, such as retinoids, or the discovery of new indications for non-dermatological agents contribute to the novel pharmacological approaches in the treatment of psoriasis.     

Positive treatment effects of ustekinumab in psoriasis: Analysis of lesional and systemic parameters

Ustekinumab, a human anti‐interleukin (IL)‐12/IL‐23p40 monoclonal antibody has demonstrated significant efficacy in patients with moderate‐to‐severe psoriasis. Skin lesion biopsies, cell surface markers on peripheral blood lymphocytes, and ex vivo T‐helper (Th)1/Th2 cytokine responses from peripheral blood mononuclear cells (PBMC) from patients receiving ustekinumab 45 or 90 mg, or placebo were evaluated at baseline and week 12. Inflammatory serum protein levels were measured at baseline, week 2 and week 12. At week 12, median epidermal thickness decreased from 312.1 to 132.7 μm, and median levels of cellular proliferation (Ki67) and T‐cell infiltration (CD3) decreased by 84.3% and 70.7%, respectively, in the combined ustekinumab group (all P ≤ 0.002). Serum levels of tumor necrosis factor (TNF)‐α, C‐C motif ligand 27 (CCL27) and other inflammatory cytokines remained unchanged. Minimal variation in the percentage of T cells expressing cutaneous lymphocyte antigen (CLA) was observed following ustekinumab treatment, with no significant variation in the percentage of cells expressing CD45RA, CD45RO, CD25, human leukocyte antigen‐DR (HLA‐DR), and C‐X‐C motif receptor 3 (CXCR3). No apparent effect on the magnitude of Th1/Th2 responses to external stimuli in PBMC was observed following placebo or ustekinumab treatment. Ustekinumab improves histological psoriasis measures, with minimal impact on the systemic immune system.     

Memory effector (CD45RO+) and cytotoxic (CD8+) T cells appear early in the margin zone of spreading psoriatic lesions in contrast to cells expressing natural killer receptors, which appear late

BACKGROUND: An influx of immunocytes, increased epidermal proliferation and abnormal keratinization are hallmarks of the psoriatic lesion. T-lymphocyte subsets in particular activated effector memory T cells and natural killer (NK) T cells have been suggested to play an important role in the pathogenesis of psoriasis. OBJECTIVES: In the present study we investigated the number of T-cell subsets (CD4, CD8, CD45RO, CD45RA, CD2, CD25), cells expressing NK receptors (CD94 and CD161), the proliferation marker Ki67 and the keratinization marker keratin (K10) across the margin of the spreading psoriatic plaque: distant uninvolved skin, the outer margin (immediately outside the clinical edge), the inner margin (immediately inside the clinical edge) and the central area. PATIENTS AND METHODS: Eight patients with active psoriasis vulgaris participated in this study. Biopsies were taken from the spreading psoriatic lesion from the distant uninvolved skin, the outer margin, the inner margin and the central area. Biopsies were processed for immunohistochemical staining. RESULTS: In the outer margin CD8+ (cytotoxic T cells) and CD45RO+ (memory effector T cells) T lymphocytes invade the epidermis and in this early stage the activation markers CD2 and CD25 also show a substantial increase. The next phase, from the outer to the inner margin, shows a statistically significant increase of these markers, and especially, the cells expressing NK receptors (CD94 and CD161) show a massive increase together with a significant increase of epidermal proliferation (Ki67) and a decrease of the K10+ epidermal surface. CONCLUSIONS: CD8+, CD45RO+, CD2+ and CD25+ T cells have a role in the early phase of the psoriatic process, whereas CD94- and CD161-expressing cells together with epidermal proliferation and keratinization are involved in a later phase.     

Bath psoralen+ultraviolet A photochemotherapy vs. narrow band‐ultraviolet B in psoriasis: a comparison of clinical outcome and effect on circulating T‐helper and T‐suppressor/cytotoxic cells

Background: Comparative success rates of bath psoralen+ultraviolet A (PUVA) and narrow band‐ultraviolet B (NB‐UVB) in psoriasis treatment are variably reported with no previous studies on the possible effect of bath PUVA on circulating CD4+ and CD8+ T cells. Objective: We aimed to compare the effect of bath PUVA and NB‐UVB clinically and on circulating T‐helper and T‐suppressor/cytotoxic cells in psoriasis. Patients and methods: Thirty‐four psoriatic patients divided into a bath PUVA‐treated group (18 patients) and a NB‐UVB‐treated group (16 patients) were compared regarding the disease severity by psoriasis area and severity index (PASI) score and percentage of circulating CD4+ and CD8+ T cells by flowcytometry before and after treatment. Results: After treatment, the bath PUVA group showed a significantly higher reduction of PASI score (85.44%) than the NB‐UVB group (58.72%). Mean peripheral CD4+ T‐cell percentage was significantly lower after [36.8; 95% confidence interval (CI) 33.80, 39.97] compared with before treatment (42.06; 95% CI 38.29, 45.83) (P<0.05) in the bath PUVA group while this difference was insignificant in the NB‐UVB group (P>0.05). Conclusion: Bath PUVA therapy is superior to NB‐UVB in the treatment of moderate and severe psoriasis with mild reversible side effects. Both modalities have a systemic effect decreasing peripheral CD4+ T cells, which is more with bath PUVA.     

Skin-infiltrating lymphocytes in normal and disordered skin: activation signals and functional roles in psoriasis and mycosis fungoides-type cutaneous T cell lymphoma.

T lymphocytes recruited into the skin can experience several different outcomes. On the one hand, they may be recruited by adhesion molecules and chemoattractants to enter the perivascular space, but never undergo activation. Other T cells undergo activation and further differentiation under the influence of the cutaneous milieu. These activated lymphocytes then coordinate specific and non-specific immune responses characteristic of inflamed tissue. We have explored two models for studying the activation and function of skin infiltrating T lymphocytes (SIL's). In the first model, we have identified a family of Langerhans cell-related professional dendritic antigen presenting cells that exist in the epidermis and dermis of normal skin, atopic skin, and mycosis fungoides skin. These have APC abilities to activate freshly recruited resting blood T cells that are distinct from another family of macrophage-related cells abnormally present in sunburned or psoriatic skin. In the second model, we examined the function of cells that have already been recruited into the skin of patients with psoriasis and mycosis fungoides. Lesional psoriasis and mycosis fungoides T cells exhibited a variety of T cell receptor gene rearrangements, conclusively demonstrating that heterogeneous populations of T lymphocytes exist in inflamed human skin. From psoriasis, clones were identified that were particularly effective at inducing normal keratinocytes to assume "psoriatic" phenotypic features and functions. Thus, lesional psoriatic SIL's could induce HLA-DR, ICAM, and CDw60 on normal keratinocytes. In addition, psoriatic SIL's induced increased keratinocyte proliferation and cytokine profile changes characteristic of psoriatic epidermis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Functional characterization of CD4+CD25+ regulatory T cells differentiated in vitro from bone marrow-derived haematopoietic cells of psoriasis patients with a family history of the disorder

BACKGROUND: In psoriasis CD4+CD25+ regulatory T cells are functionally deficient. The imbalance between regulatory and effector T-cell functions is important for inducing psoriasis. It is reasonable to speculate that the dysfunctional activity of CD4+CD25+ regulatory cells may originate partly from the abnormal haematopoietic cells determined mainly by genetic background. OBJECTIVES: To test the hypothesis that haematopoietic stem cells are responsible for dysfunctional CD4+CD25+ regulatory cells in psoriasis. METHODS: Bone marrow-derived CD34+ haematopoietic cells from patients with psoriasis (with a family history of psoriasis) and from normal controls were differentiated into T cells in vitro. CD4+CD25+ T cells were isolated by an immunomagnetic bead method, and proliferation activity and capacity for cytokine secretion were determined. Furthermore, the ability of CD4+CD25+ T cells to suppress the proliferative responses of allogeneous peripheral blood CD4+CD25- effector T cells was assessed in vitro. RESULTS: The differentiated CD4+CD25+ T cells of psoriatic origin showed similar characteristics to those of normal volunteers, including proliferation activity and secretion profile of the cytokines interleukin (IL)-2, IL-4, IL-8, IL-10 and interferon (IFN)-gamma. However, proliferation and secretion levels of the cytokines IL-2 and IL-10 for CD4+CD25+ cells of psoriatic CD34+ cell origin were significantly lower than those of normal controls in response to streptococcal superantigen (Strep-A). In particular, CD4+CD25+ T cells differentiated from psoriatic CD34+ cells were functionally insufficient to restrain effector T-cell proliferation. CONCLUSIONS: CD4+CD25+ T cells differentiated in vitro from haematopoietic cells of patients with psoriasis are impaired in regulatory function. The dysfunction of psoriatic CD4+CD25+ T cells may be due to inherent genetic programming passed down from bone marrow-derived haematopoietic cells.     

Role of neutrophils in induction of acute inflammation in T-cell-mediated immune dermatosis, psoriasis: a neutrophil-associated inflammation-boosting loop

A growing body of evidence has indicated that T-cell-mediated immunity plays an important role in triggering and maintenance of psoriatic lesions. In this review we present our own experimental results as well as those from the literature related to the pathomechanism of the development of inflammatory changes in psoriatic lesions. First of all it is important to acknowledge the fact that psoriatic lesions are not uniform as assumed by many authors but that they are actually rather heterogeneous both clinically and histologically even within the same plaques. Lymphokines produced by activated T cells in psoriatic lesions have a strong influence on the proliferation of the epidermis, whose stimulated kertinocytes released several cytokines, which in turn enhance the activation state of T cells. Thus, they form a vicious cycle, a T-cell-mediated inflammation-sustaining loop. Although the interaction between T-cell-mediated immunity and epidermal keratinocytes may well explain the maintenance of background "chronic" inflammatory changes diffusely observed throughout psoriatic lesions, it is not enough to explain the island-like, "acute" inflammatory changes observed within and at the border of the plaque lesions. Characteristic neutrophil accumulation under the stratum corneum can be observed in the highly inflamed and therapeutically recalcitrant areas of psoriatic lesions. They are chemotactically attracted and activated there by synergistic action of chemokines, IL-8 and Gro-a released by the stimulated keratinocytes, and particularly C5a/C5a des arg produced via the alternative complement pathway activation possibly on the surface of corneocytes. In this review, we emphasize that the accumulation of neurophils is not simply a passive event. We think that those stimulated neutrophils are able to influence not only the growth and differentiation of epidermal keratinocytes but also the activation-state of T cells by aberrant expression of HLA-DR on their surfaces as well as by their effects. These T cells in turn influence the transepidermal neutrophil migration through the effect of their lymphokines on the keratinocyte production of pro-inflammatory mediators including C3. Therefore, we propose a neutrophil-associated inflammation-boosting loop that may well explain the localized "acute" inflammatory changes scattered over the "chronic" psoriatic plaques as well as in the acutely inflamed lesions of pustular psoriasis.     

Neue und etablierte Indikationen der UV‐B‐311‐nm‐Phototherapie

Phototherapy with ultraviolet (UV) irradiation of wavelengths between 280 and 320 nm (UV‐B) is a safe and effective treatment for a variety of inflammatory skin diseases. In addition to standard broad band UVB, narrow band phototherapy with fluorescent bulbs emitting near monochromatic UV between 310 – 315 nm has become an important treatment for diseases such as psoriasis, atopic dermatitis or vitiligo. Other diseases respond favorably to narrow band UV‐B phototherapy, the number of potential indications for such phototherapy is continuously growing. The differential effects of narrow band UV‐B phototherapy in comparison to other UV phototherapies, as well as new and established indications for this treatment modality are reviewed.     

银屑病患者骨髓CD34+细胞定向分化的T细胞对角质形成细胞增殖的影响

目的:探讨家族史阳性的银屑病患者骨髓CD34 细胞体外定向分化的T细胞对表皮角质形成细胞(KC)增殖调控蛋白表达的影响.方法:将银屑病患者骨髓CD34 细胞体外定向分化的T细胞经链球菌超抗原活化后与KC共培养,分别采用免疫组化法及ELISA法检测KC C-myc、bcl-xL、p53及Ki67蛋白表达及培养上清白介素(IL)-8、干扰素(IFN)-γ水平.结果:①受银屑病患者CD34 细胞定向分化T细胞作用的KC C-mye及Ki67蛋白表达与自然增殖组及正常人CD34 细胞定向分化的T细胞作用组相比显著增强(P＜0.05),而bcl-xL及p53蛋白表达3组间的差异无统计学意义(P＞0.05);②受正常人CD34 细胞定向分化T细胞作用的Kc C-myc、bcl-xL、p53及Ki67蛋白表达与自然增殖组比较差异亦无统计学意义(P＞0.05);③银屑病CD34 细胞定向分化的T细胞作用组培养上清IL-8及IFN-γ水平显著高于正常对照组(P＜0.01).结论:银屑病患者骨髓造血细胞定向分化的T细胞可影响KC增殖状态,显示类似银屑病外周血T细胞的活性特点.     

寻常型银屑病患者外周血髓系树突状细胞CD47的表达

目的：检测寻常型银屑病患者外周血髓系树突状细胞（mDCs）表面整合素相关蛋白（CD47）的表达水平。方法：流式细胞仪检测寻常型银屑病患者和健康对照者外周血mDCs表面CD47及CD4+调节性T细胞（Treg）表达水平；Luminex液相芯片技术检测上清液IL-23、IL-17和TNF-α浓度。结果：共检测46例患者和46名健康对照，患者组mDCs细胞CD47表达水平为32.8低于对照组的63.6，差异有统计学意义（P<0.05）。患者组mDCs细胞CD47表达水平与银屑病皮损面积和严重程度指数（PASI）负相关（r=-0.651, P<0.05）；患者组Treg细胞比例显著低于对照组，差异具有统计学意义（P<0.05）；IL-23、IL-17和TNF-α浓度显著高于对照组，差异具有统计学意义（P<0.05）。结论：银屑病外周血mDCs表面CD47及Treg细胞表达下降。