Kutane T-Zell-Lymphome (CTCL) stellen eine heterogene Gruppe von non-Hodgkin-Lymphomen dar. Die häufigsten Entitäten sind die Mycosis fungoides, das Sézary-Syndrom sowie CD30+ lymphoproliferativen Erkrankungen (cALCL). Todesliganden-vermittelte Apoptose ist auch für die Lymphozyten-Homöostase von essentieller Bedeutung. Zunächst wurden die CTCL-Zelllinien mit systemischen T-Zell-Lymphomzellen hinsichtlich ihrer Apoptosesensitivität verglichen. Hierbei zeigte sich eine ausgesprochene Resistenz aller kutanen Zelllinien gegenüber TRAIL- und TNF-α-induzierter Apoptose. Anhand der Aktivierung der Caspasensignalkaskade war eine frühe Blockierung der Apoptose nachweisbar. Überdies konnte der Verlust von CD95, TNF-R1, Caspase-10 sowie von Bid in verschiedenen CTCL-Zelllinien nachgewiesen werden. Die Apoptoseresistenz konnte hingegen mit einer generellen und starken Expression des anti-apoptotischen Proteins c-FLIP korreliert werden. Des Weiteren wurde der Einfluss von CD30-Stimulation auf die durch CD95-induzierte Apoptose in CD30+-Zelllinien untersucht. Hierbei zeigte sich, dass CD30 Stimulation zur Aktivierung von NF-kB und zu erhöhter c-FLIP Expression führt, was mit Apoptoseresistenz korrelierte. Die Bedeutung der in vitro-Ergebnisse zeigte sich auch durch eine weitgehende Parallelität dieser zu untersuchten Biopsieproben von CTCL-Patienten. Schließlich wurden verschiedene NSAIDs auf ihre Fähigkeit hin untersucht, die Expression von c-FLIP zu vermindern und Apoptose zu induzieren. Dies wurde sowohl in CTCL-Zelllinien als auch in Tumor-T-Zellen von CTCL-Patienten untersucht. NSAIDs aktivierten beide Apoptosesignalwege und Diclofenac sensitiviert überdies für TRAIL-vermittelte Apoptose. In Ihrer Gesamtheit vermittelt die vorliegende Arbeit einen Einblick in die komplexen Apoptoseregulationsmechanismen in kutanen T-Zell-Lymphomen und identifiziert c-FLIP als einen zentralen Resistenzfaktor sowie NSAIDs als mögliche CTCL-Therapieoption. / Cutaneous T cell lymphomas (CTCL) form a heterogeneous group of non-Hodgkin lymphomas. Its most frequent forms are Mycosis fungoides, Sézary syndrome and CD30-positive cutaneous anaplastic large-cell lymphoma. Death ligands critically contribute to lymphocyte homeostasis by induction of apoptosis and may further represent safeguard mechanisms to prevent lymphoma development and tumor growth. First, we analyzed induction of apoptosis by death ligands in CTCL cell lines and compared it to that in systemic T-cell lymphoma cells. This revealed for CTCL cells a pronounced resistance to death ligands. In particular, there was no caspase activation in non-responsive CTCL cells, indicating an early blockade of the apoptosis signal. Furthermore a loss of CD95, TNF-R1, caspase-10, as well as of Bid was found in several cell lines. Changes at the receptor expression level were largely ruled out, whereas, consistent and strong expression of c-FLIP was correlated with resistance. In addition, we investigated the CD30/CD95 crosstalk in CD95-sensitive cALCL cell lines. Experiments showed that CD30 ligation leads to NF-κB-mediated c-FLIP upregulation in cALCL cells, which in turn conferred resistance to CD95-induced apoptosis. Parallels with regard to expression of apoptosis regulators were seen in peripheral blood mononuclear cells and biopsies of CTCL patients. Finally, we evaluated non-steroidal anti-inflammatory drugs (NSAIDs) for their capacity to downregulate c-FLIP expression and apoptosis induction in CTCL cells as well as in tumor T cells from CTCL patients. NSAID treatment resulted in an activation of both apoptosis signaling pathways and, furthermore, Diclofenac pre-treatment sensitized for TRAIL-induced apoptosis. In conclusion, this study elucidates defects in apoptosis regulation, proved the significance of c-FLIP for the survival of CTCL cells and provides a rationale for the use of NSAIDs as a potentially new therapeutic option for CTCL patients.

Oncogenic microRNAs (miRNAs) are small RNA molecules that inhibit post-translational regulatory mechanisms at the epigenetic level. miRNAs are often deregulated in malignancies and due to their stability are detectable in non-cellular fractions of peripheral blood. In our laboratory, we have performed several studies that have investigated and utilized miRNAs as biomarkers for various hematological tumors (e.g., chronic lymphocytic leukemia, Hodgkin`s lymphoma) and solid tumors (e.g., breast cancer). The aim of these studies was to find the association of miRNAs with pathophysiological and clinical aspects of each disease. Here, we confirmed the importance of particular miRNA or its complex during disease monitoring. Combining clinical, molecular biological and statistical analyses, we were able to find miRNA sets that fulfilled not only a diagnostic role but also a prognostic role beyond expectations. The main focus of this thesis is on the investigation of microRNAs in the diagnosis of a hematological malignancy - primary cutaneous T-cell lymphoma (CTCL). Tumor specificity of some miRNAs has been demonstrated. Their aberrant expression in tissue samples of CTCL patients obtained from skin biopsies, correctly distinguished malignant disease from control samples of benign skin lesions. Here, we...

Psoriasiform diseases are a group of cutaneous disorders that are characterized by impaired keratinocyte maturation leading to epidermal hyperplasia and thickening of skin. This group of disorders includes psoriasis, seborrheic dermatitis (SD) and mycosis fungoides (MF). Psoriasis has been recently shown to be mediated by the pro-inflammatory T helper cell subset, namely Th17 cells, whereas the pathogenesis of SD and MF are still poorly understood. SD is characterized by inflamed skin that primarily manifests on areas populated with sebaceous glands. Interestingly, SD is very common amongst immunosuppressed patients such as those with HIV-AIDS, suggesting the importance of an immune response in the development of SD. Because SD shares common clinical and histopathological features with psoriasis, a disease in which Th17 axis cytokines is known to be involved, and given that Th17 cells and their related cytokines have been implicated in the pathogenesis of a wide range of autoimmune and inflammatory disorders, it is possible that Th17 axis cytokines play a role in the pathogenesis of SD. We explored the involvement of Th17 axis cytokines in a D2C mouse model of psoriasiform disease that shows a high degree homology to the clinicopathological characteristics of human seborrheic dermatitis. IL-6 and IL-23, which are important for the differentiation of Th17 cells, and IL-17 and IL-22, which are the Th17 effector molecules, were measured at both protein and mRNA levels in sera and lesional skin from D2C mice. An immunohistochemical analysis was also performed to detect the presence of IL-17 in D2C lesional skin relative to normal skin from DBA/2 controls. Our data demonstrated significantly elevated levels of IL-6, IL-17 and IL-22 in sera from diseased D2C mice compared to controls and/or convalescent mice. There were no significant differences in IL-23 protein levels in sera from D2C mice compared to those from wild type mice or convalescent D2C mice. RT-PCR revealed a significant increase in IL-23 and IL-17 gene expression in D2C lesional skin relative to normal skin. Gene expression levels of IL-22, but not IL-6, were statistically significant elevated in D2C skin lesions compared to controls, by real time PCR. Our IHC study of IL-17 expression showed an abundance of positively stained mononuclear cells in D2C lesional skin relative to DBA/2 normal skin. Altogether, our data demonstrate that Th17 axis cytokines are elevated locally at mRNA levels for IL-23, IL-17, and IL-22 and systematically at protein levels for IL-6, IL-17, and IL-22. This data lay the foundation for further studies investigating a role for Th17 axis cytokines in the cutaneous inflammatory disease seen in our mouse model of SD and, ultimately, in the development of human SD. Mycosis fungoides (MF) is the most common type of cutaneous T cell lymphoma (CTCL). The etiology of MF is unknown, but there is substantial evidence suggesting a potential role for a yet unidentified infectious agent in the pathogenesis of MF. Many studies have claimed that there is an association between MF and the Human T cell Lymphotorpic Virus Type 1 (HTLV-I); however, the involvement of this virus in the etiology of MF is a controversial topic. In our study, we used nested PCR to explore the association between HTLV-I infection and MF by screening genomic DNA from 114 skin biopsies for the presence of HTLV-I provirus. We also utilized a ViroChip and high-throughput sequencing (HTS), as a case study, to attempt to detect novel virus-specific oligonucleotides that may be associated with CTCL. Our data showed no evidence for HTLV-I proviral integration in the 114 MF samples that were screened using nested-PCR. The ViroChip and HTS results also did not reveal any signature sequence for known or unknown infectious agent in the CTCL case study. Collectively, this data argue against the involvement of HTLV-I provirus in the pathogenesis of MF.

Primär kutane Lymphome sind typische Krankheitsbilder in der Dermatologie. Obwohl diese Erkrankungen zu den seltenen Krankheiten zählen, sind sie jedoch von therapeutischem und wissenschaftlichen Interesse. Der erste Teil der Arbeit beschäftigt sich mit der Klassifikation und Therapie primär kutaner Lymphome. Die 1997 veröffentlichte EORTC-Klassifikation wird mit ihren wichtigsten Entitäten erläutert. Die EORTC-Klassifikation geht auf spezifische Besonderheiten der primär kutanen Lymphome ein und orientiert sich an der guten Prognose dieser Erkrankungen. Therapeutische Strategien wie der Einsatz von für kutane Lymphome typische Behandlungsmethoden (PUVA, Exzision, Radiatio) als auch gentechnisch hergestellte Medikamente wie therapeutische Antikörper und Vakzinen werden erklärt. Der zweiten Teil der Habilitationsschrift konzentriert sich auf experimentelle Arbeiten zur molekularbiologischen Untersuchung von primär kutanen Lymphomen. Im Mittelpunkt steht die Methode der Mikromanipulation und Einzelzell-PCR. Für die Mykosis fungoides konnte gezeigt werden, daß im initialen Ekzemstadium nur wenige klonale maligne T-Zellen in der Probe nachzuweisen sind. Mit Zunahme des Infiltrates (Plaque) sind die malignen Zellen in der Epidermis oder gruppiert in der Dermis lokalisiert. Im Tumorstadium dominieren die malignen Zellen das dermale Infiltrat (Gellrich S, J Invest Dermatol, 2000). Die Tumorzellen primär kutaner B-Zell-Lymphome weisen einen dem Keimzentrum ähnlichen Mutationsstatus, nämlich somatische Mutationen und intraklonale Diversifikation, auf (Gellrich S, J Invest Dermatol, 1997; Gellrich S, J Invest Dermatol, 2001). Die Daten sprechen für einen noch aktiven Mutationsmechanismus, sogenannte ongoing mutations (Golembowski S, Immunobiology, 2000). Eine Unterform der kutanen Lymphome stellen die primär kutanen CD30+ T-Zell Lymphome dar. In Untersuchungen mittels Mikromanipulation und Einzelzell-PCR wurden CD30+ Zellen aus primär kutanen CD30+ großzelligen Lymphomen hinsichtlich ihrer T-Zell-Klonalität untersucht. Dabei stellte sich heraus, daß nicht alle atypischen Zellen zur Tumorpopulation gehören. Es wird vermutet, daß ein unbekannter Stimulus zur Ausprägung der Zellmorphe und zur Expression des CD30-Moleküls führt (Gellrich S, J Invest Dermatol, 2003). Eine weitere Entität, bei welcher CD30+ Zellen eine Rolle spielen, ist die lymphomatoide Papulose. In den hier dargestellten Untersuchungen wurden CD30+ große atypische Zellen einzeln isoliert und anschließend mittels PCR für die Gene des T-Zell-Rezeptor-Gamma und des Immunglobulinrezeptors amplifiziert bei einem Patienten mit lymphomatoider Papulose und assoziierter Morbus Hodgkin-Erkankung. In zwei von drei Fällen waren diese CD30+ Zellen polyklonal. Die aus der Fragmentanalyse bekannte klonale T-Zell-Population konnte dagegen in CD3+CD30- kleinen Zellen gefunden werden. In einem dritten Fall enthielten die CD30+ Zellen klonale B-Zellen, welche die gleichen Immunglobulingene rearrangiert hatten wie Zellen aus einem zuvor bestehenden Hodgkin-Lymphom desselben Patienten. Diese Ergebnisse lassen vermuten, dass es für das Aufschießen und die Regredienz der Läsionen der lymphomatoiden Papulose einen Stimulus gibt und die klonalen T- und B-Zellen als Begleitinfiltrat ohne pathologische Bedeutung anzusehen sind. Insgesamt bilden die Daten dieser Arbeit eine Grundlage für eine Fortsetzung der Untersuchung zur Ätiopathogenese von primär kutanen Lymphomen und deren Therapie und bieten die Möglichkeiten vielfältiger wissenschaftlicher Kooperationen. / Primary cutaneous lymphomas present with typical clinical features in dermatology. Although these diseases are rare, they particularly are of scientific and therapeutic interest. The first part of this work deals with the classification and treatment of primary cutaneous lymphomas (PCBCL). The 1997 published EORTC classification will be explained according to the good prognosis of PCBCL. Therapeutic strategies as well as typical procedures (PUVA, excision, irradiation) and gene-technically produced drugs (therapeutic antibodies, vaccination) are illustrated in detail. The second part of this publication focuses on the experimental molecular biological work-out, done in primary cutaneous lymphomas by means of micromanipulation and single cell PCR. For the mycosis fungoides could be shown that in the patch stage only a few malignant T cells can be detected. Increasing infiltrates (plaque-stage) are characterized by epidermotrop or dermally grouped atypical cells. In tumor stage dermal atypical T cells are predominating (Gellrich S, J Invest Dermatol, 2003). The tumor cells of primary cutaneous B cell lymphomas are comparable with the stage of mutation of follicle centre cells: somatic mutations and intraclonal diversity (Gellrich S, J Invest Dermatol, 1997; Gellrich S, J Invest Dermatol, 2001). The data indicate, that there may be an active mutation mechanism, the so-called ongoing mutations (Golembowski S, Immunobiology, 2000). One subgroup of PCBCL, are presented by the CD30positve entities. By means of micromanipulation and PCR, single cells were investigated due to T cell clonality. Not all atypical cells belong to the malignant population. It is supposed that an unknown stimulus leads to morphological features and CD30 expression (Gellrich S, J Invest Dermatol, 2003). Another CD30positive entity is reflected by the lymphomatoid papulosis. In these experiments large atypical CD30positve cells were isolated and have been investigated via PCR for T cell receptor g or immunoglobuline heavy and light chain gene rearrangement. The majority of the large CD30postive cells (two cases) belong to a polyclonal T cell population. In the opposite, the small CD3positive cells are the cells persisting within the T cell clone. In another case B cells with the same immunoglobulin gene rearrangement like in a preceding Hodgkin disease of the same patient could be detected. The data seem to underline the fact that reactive polyclonal CD30positive cells are triggered by an unkown stimulus with clonal bystander cells without any pathological significance. In summary, this work could be the basis for further investigations about the etiopathogenesis of PCBCL.