Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Los fotorreceptores (FRs) son las neuronas que capturan la luz en el ojo, por lo que juegan un rol central en la visión. La pérdida progresiva de estas células durante ciertas enfermedades neurodegenerativas de la retina, como la retinitis pigmentosa o la degeneración macular, conduce a déficits de la visión y eventualmente a la ceguera. Estas patologías, así como otras que afectan al sistema nervioso central, están caracterizadas por la degeneración gradual, selectiva e irreversible de una población neuronal específica. La deficiencia de factores tróficos ha sido involucrada en muchos de estos procesos neurodegenerativos y es característica de la denominada muerte celular programada, tal como la que ocurre al momento de la sinaptogénesis en el desarrollo del sistema nervioso. En efecto, en la retina, así como también en otras partes del sistema nervioso, las neuronas requieren para su supervivencia, de factores tróficos, los cuales provienen de su entorno. El requerimiento de factores tróficos varía según el tipo celular y la etapa del desarrollo. En particular, para los FRs ya se han identificado varios de ellos, incluyendo el Factor Neurotrófico Derivado de la Glía (GDNF), el Factor Neutrófico Ciliar (CNTF), el Factor de Crecimiento Fibroblástico (FGF), el ácido docosahexaenoico (DHA), la esfingosina 1-fosfato (S1P) y, más recientemente, uno de los principales, el Factor Derivado del Epitelio Pigmentario (PEDF), una proteína con funciones neurotróficas y antiangiogénicas, asociadas a dominios separados de la proteína. La identificación de las secuencias de estos dominios ha permitido diseñar y sintetizar químicamente péptidos estables, como los fragmentos neurotróficos 44-mer y 17-mer, que conservan las propiedades de la proteína nativa y, por ende, de potencial valor médico. Sin embargo, estas características ventajosas requieren ser evaluadas en un modelo experimental adecuado. La mayoría del conocimiento actual sobre el PEDF se ha obtenido gracias a modelos in vivo, donde, debido su inherente complejidad, sumado a la cantidad de interacciones que ocurren entre las células y moléculas de tejidos circundantes, resulta difícil analizar los procesos involucrados. Una alternativa a este obstáculo son los cultivos primarios elegidos para realizar esta tesis, compuestos solo de neuronas amacrinas y FRs, las que, creciendo en medios químicamente definidos, permiten estudiarlas en un entorno mucho más controlado que en el organismo entero. En estos cultivos, los FRs se desarrollan independientemente, sin requerir la suplementación de factores tróficos, pero, una vez establecidas sus conexiones sinápticas, se tornan dependientes de los mismos para continuar con su desarrollo y prolongar supervivencia. La dependencia por estos factores hace de este sistema in vitro un modelo adecuado para evaluar el efecto de distintas moléculas sobre la supervivencia o diferenciación celular. Por ello, los resultados reseñados en el primer capítulo de esta tesis tuvieron como objetivo principal evaluar el efecto de PEDF y los péptidos derivados de su dominio neurotrófico y angiogénico en este modelo de cultivo primario de neuronas de retina. En estos cultivos, tanto los FRs como las neuronas amacrinas exhibieron el receptor de PEDF (PEDF-R), el cual es una fosfolipasa del tipo A2, localizado principalmente en la membrana celular. Por otro lado, la expresión del transcripto para PEDF-R mostró un patrón decreciente durante los primeros 5 días de cultivo, así como también en la retina in vivo, en el mismo periodo de desarrollo. Este patrón se observó también a nivel de la proteína, aunque su descenso en el tiempo fue más atenuado. Tanto el PEDF como los dos péptidos derivados de su dominio neurotrófico, protegieron a los FRs en cultivo de la muerte celular, caracterizada por ensayos de TUNEL y Anexina V. Además, previnieron la pérdida de la función mitocondrial evaluada mediante Mitotracker, y preservaron la integridad estructural de la membrana plasmática, analizada indirectamente por medio de ioduro de propidio y DAPI; dado que estos marcadores se visualizan una vez que se altera la permeabilidad de la membrana plasmática. Esta protección se debió principalmente a la interacción de PEDF con PEDF-R, y, en parte, al aumento constatado en la transcripción de factores antiapoptóticos como Bcl2 y Bcl2a1. El efecto del PEDF fue específico para la supervivencia de los FRs dado que el mismo no alteró la viabilidad de las neuronas amacrinas, la cual se mantuvo constante durante los días de cultivo analizados. Por el contrario, el PEDF y los péptidos 44-mer y 17-mer promovieron el desarrollo de neuritas en las neuronas amacrinas, e indujeron la diferenciación de los FRs, al promover la polarización de la rodopsina hacia el extremo apical de estas neuronas, tal como ocurre en los FRs maduros de la retina in vivo. Estos efectos fueron anulados eficientemente mediante el secuestro de PEDF o de sus péptidos por medio del péptido bloqueante P1, o por la inhibición de la actividad enzimática del PEDF-R mediante el inhibidor enzimático selectivo atglistatin. Todos los efectos del PEDF y sus péptidos neurotróficos fueron asociados a la interacción de los mismos con el PEDF-R. Por su parte, el fragmento derivado del dominio antiangiogénico del PEDF no tuvo ningún efecto. Por otro lado, también se indagó sobre el potencial del epitelio pigmentario de la retina (EPR) derivado de células madre pluripotentes (CMP) en la producción y liberación del PEDF. Dado que la deficiencia del PEDF ha sido correlacionada con una mayor incidencia de ciertas retinopatías y el hecho que el EPR puede estar comprometido en algunas de estas patologías, ha impulsado el desarrollo de estrategias orientadas a reemplazar el EPR dañado. Entre ellas se destaca la estrategia de generar EPR por medio de CMP obtenidas a partir de la inducción de células somáticas mediante la transducción de factores de pluripotencia por medio de un sistema episomal. Este tipo de estrategia requiere sortear múltiples obstáculos antes de ser viable, particularmente el de garantizar la identidad del nuevo EPR. El objetivo de esta línea de investigación, descripta en el segundo capítulo de esta tesis, fue evaluar los aspectos funcionales del EPR derivado de células madre, comparándolos con los del EPR nativo. El EPR derivado de CMP humanas recapituló las características distintivas del EPR nativo, como la polarización baso-apical, la capacidad de fagocitar y metabolizar segmentos externos de FRs y la producción de PEDF. Todas estas características se mantuvieron aun hasta 50 días después de su inducción, con la producción de PEDF incrementándose significativamente en función del tiempo. En conclusión, el PEDF y los péptidos derivados de su dominio neurotrófico ejercieron efectos citoprotectores y de diferenciación sobre los fotorreceptores y promovieron el crecimiento de neuritas en las neuronas amacrinas. Todos estos efectos fueron dependientes de la interacción entre PEDF y PEDF- R. Por otro lado, el EPR derivado de CMP examinado en este trabajo de tesis mostró un comportamiento similar al del EPR en la retina intacta, lo que permite considerar sus posibles capacidades terapéuticas para estas enfermedades / Photoreceptors (PHRs) are the retinal neurons, which react to light, making them a central component in the visual process. Their loss during certain retinal neurodegenerative diseases, such as retinitis pigmentosa or age-related macular degeneration, leads to a gradual decline of vision and ultimately to blindness. These pathologies, as well as others that target the central nervous system, are characterized by the gradual, selective and irreversible degeneration of specific neuronal cell types. The lack of trophic factors has been involved in many of these neurodegenerative processes and it is characteristic of the so- called programmed cell death, such as the one that occurs during the period of synaptogenesis within the developing nervous system. In the retina, just as any other portions of the nervous system, neurons are dependent on trophic factors, which are produced by their environment. Trophic factor requirements vary according to each cell type and its developmental stage. For the PHRs, many trophic factors have been already identified, including the Glial cell line-derived Neurotrophic Factor (GDNF), Ciliary Neurotrophic Factor (CNTF), Fibroblastic Growth Factor (FGF), docosahexaenoic acid (DHA), sphingosine-1-phosphate (S1P) and, perhaps one of the most important among them, the Pigment Epitheliumderived Factor (PEDF). PEDF is a protein exhibiting both neurotrophic and antiangiogenic properties, which are conferred by two spatially-separated domains of the PEDF polypeptide. The identification of the sequences of these domains has allowed for the design and chemical synthesis of stable peptides, such as the neurotrophic fragments 44-mer and 17-mer, which could potentially retain the neurotrophic properties of the native protein, and therefore having a potential therapeutic value. However, these advantages should be first evaluated on an adequate experimental model. Up to now, most of our knowledge regarding PEDF has been obtained through in vivo models, which, due to their inherent complexity and the multiplicity of interactions between cells and their surrounding tissues, makes it difficult to analyze the specific processes occurring at a smaller scale. An alternative to overcome these limitations is the use of primary cultures chosen for the present thesis, composed solely of PHRs and amacrine neurons cultured in a chemically defined medium. These cultures allow the study of these neurons in a much more controlled environment when compared to a whole organism. PHRs in these cultures, initially develop and replicate without requiring trophic factor supplementation, but once they establish their synaptic connections, become reliant on them for their survival. This reliance makes this in vitro system an adequate testbed to evaluate the effects of different trophic factors on cell survival and differentiation. Therefore, the results of the first part of the thesis, which are shown in the first chapter, have the main objective of evaluating the effects of PEDF and peptides derived from its neurotrophic and antiangiogenic domains in a primary retinal cell culture-based model. In these cultures, both neuronal types exhibited the PEDF receptor (PEDF-R), which was primarily localized in the cell membrane. Additionally, the expression patterns for the PEDF-R transcript showed a decreasing trend on the first 5 days in culture, which was also observed in the in vivo environment. This pattern was also observed at the protein level, albeit in a less dramatic fashion. PEDF as well as its neurotrophic domain-derived peptides protected cultured PHRs from cell death, which was measured by TUNEL and Annexin V assays. Furthermore, they also prevented the loss of mitochondrial function, as evaluated by Mitotracker, and preserved the structural integrity of the plasma membrane analyzed by propidium iodide and DAPI staining, given that these markers are visualized once the plasma membrane permeability is altered. This protection was exerted through PEDF/PEDF-R interaction, along with the upregulation of antiapoptotic factors such as Bcl2 and Bcl2a1. This protective effect was PHR-specific, given that there was no significant difference in the survival rate of amacrine neurons, which was constant throughout the observed timeframe. Furthermore, PEDF and the 44-mer and 17-mer peptides promoted neurite outgrowth in amacrine neurons and induced PHR differentiation by promoting apical rhodopsin polarization, mimicking the same process in the retina in vivo. These effects were readily annulled either by sequestering PEDF or its derived neurotrophic peptides with the blocking P1 peptide, or by inhibiting the enzymatic activity of PEDF-R with the selective enzymatic inhibitor atglistatin. Every previously observed effect, exerted by PEDF or its neurotrophic peptides, was linked to their interaction with PEDF-R. The antiangiogenic domain-derived peptide showed no effects whatsoever. In a second line of research carried out in this thesis and described in the second chapter of this thesis, I delved on the potential PEDF production and secretion of induced pluripotent cell-derived retinal pigmented epithelium (RPE). Due to the fact that PEDF deficit has been correlated with an increased incidence of retinopathies, coupled with the observation that the pigmented epithelium itself is compromised in several of them; has led to the emergence of novel therapeutic strategies based on replacing the damaged retinal pigmented epithelium. One of the main approaches relies on generating RPE by the differentiation of induced pluripotent stem cells, obtained by the transduction of pluripotency factors in somatic cells by means of an episomal system. This approach must clear several hurdles before becoming viable, starting with confirming the identity and properties of this new RPE and how it compares to native RPE. The stem cell-derived human RPE was able to replicate the main hallmarks of native RPE, such as basalapical polarization, the capacity to phagocyte and metabolize PHR outer segments and to secrete PEDF. All these features were consistent even at 50 days post-induction, with PEDF secretion showing a significant increase over time. In conclusion, PEDF and its neurotrophic peptides exerted cytoprotective effects and stimulated neuronal development on photoreceptors and promoted neurite outgrowth amacrine neurons. All of these effects were driven by PEDF/PEDF-R interaction. Furthermore, stem cell-derived RPE showed a similar behavior to native RPE, allowing this approach of RPE replacement to be further considered as another potential therapeutic approach for the treatment of these diseases.

Yes / Objectives Systemic sclerosis (SSc) is characterised by tissue fibrosis and vasculopathy with defective angiogenesis. Transforming growth factor beta (TGF-β) plays a major role in tissue fibrosis, including downregulation of caveolin-1 (Cav-1); however, its role in defective angiogenesis is less clear. Pigment epithelium-derived factor (PEDF), a major antiangiogenic factor, is abundantly secreted by SSc fibroblasts. Here, we investigated the effect of TGF-β and Cav-1 on PEDF expression and the role of PEDF in the ability of SSc fibroblasts to modulate angiogenesis. Methods P EDF and Cav-1 expression in fibroblasts and endothelial cells were evaluated by means of immunohistochemistry on human and mouse skin biopsies. PEDF and Cav-1 were silenced in cultured SSc and control fibroblasts using lentiviral short-hairpin RNAs. Organotypic fibroblast–endothelial cell cocultures and matrigel assays were employed to assess angiogenesis. Results P EDF is highly expressed in myofibroblasts and reticular fibroblasts with low Cav-1 expression in SSc skin biopsies, and it is induced by TGF-β in vitro. SSc fibroblasts suppress angiogenesis in an organotypic model. This model is reproduced by silencing Cav-1 in normal dermal fibroblasts. Conversely, silencing PEDF in SSc fibroblasts rescues their antiangiogenic phenotype. Consistently, transgenic mice with TGF-β receptor hyperactivation show lower Cav-1 and higher PEDF expression levels in skin biopsies accompanied by reduced blood vessel density. Conclusions O ur data reveal a new pathway by which TGF-β suppresses angiogenesis in SSc, through decreased fibroblast Cav-1 expression and subsequent PEDF secretion. This pathway may present a promising target for new therapeutic interventions in SSc. / NIHR CDF; EULAR ODP

O fator derivado do epitélio pigmentado (PEDF) é um fator neurotrófico que possui um grande potencial trófico nos neurônios motores da medula espinal, bem como é capaz de modular o microambiente da lesão. Desta forma, analisamos a capacidade do tratamento com PEDF em promover a neuroplasticidade da medula espinal após lesão isquêmica. Ratos Wistar adultos foram submetidos à lesão medular isquêmica do tipo fototrombótica, segundo o método de Rose Bengal, na altura do 11° segmento torácico e foram imediatamente tratados com inoculação local de PEDF (grupo PEDF) ou solvente (grupo Salina). Ratos submetidos à cirurgia simulada (grupo Sham) receberam a injeção do solvente. Ao término do procedimento cirúrgico, os ratos foram submetidos a testes neurofuncionais durante 6 semanas. Após esse período, os animais sofreram eutanásia e o tecido medular foi dividido entre as técnicas de imunoistoquímica, western blot e PCR em tempo real. Foi analisada na região lombar anterior da medula espinal a modulação das CSPGs, a expressão dos fatores neurotróficos NT-3, GDNF, BDNF e FGF-2, bem como os níveis das moléculas associadas à angiogênese e apoptose (laminina e Bcl-2), das proteínas relacionadas à neuroplasticidade (MAP-2, GAP-43 e sinaptofisina) e do sistema Eph/efrina e a RhoA, que são capazes de modular o crescimento de fibras. Os resultados mostraram uma recuperação parcial e espontânea do comportamento sensório-motor dos animais que foram submetidos à lesão fototrombótica, onde o tratamento com PEDF foi capaz de potencializar alguns desses parâmetros. A análise da região lombar anterior da medula espinal, caudal à lesão, mostrou uma diminuição das CSPGs nos dois grupos lesados, o que pode ter favorecido os eventos de neuroplasticidade. O tratamento com PEDF foi capaz de promover a regulação dos fatores neurotróficos NT-3 e GDNF, diminuir a angiogênese local (diminuição da laminina) e potencializar o processo de neuroplasticidade (aumento da MAP-2) nessa região. A lesão medular isquêmica foi capaz de modular a expressão do receptor EphA4 e da efrina-B1 e o tratamento com PEDF possivelmente regulou o estado de ativação da efrina-A2 e da efrina-B3 e certamente modulou a ativação da efrina-B2. Ainda, os receptores Eph e as efrinas foram observados diferentemente nos neurônios e astrócitos. Nossos resultados confirmam a capacidade plástica da medula espinal após lesão e mostra que o tratamento com PEDF foi capaz de potencializar esse processo / The pigment epithelium derived factor (PEDF) is a neurotrophic factor that has a great trophic potential in the motor neurons of the spinal cord, and is able to modulate the lesion microenvironment. We analyzed the capacity of the treatment with PEDF to promote the neuroplasticity after ischemic spinal cord injury. Adult male Wistar rats were underwent to photothrombotic ischemic spinal cord injury, according to the Rose Bengal method, at the level of 11° thoracic segment, and were immediately treated with local injection of PEDF (PEDF group) or solvent (Saline group). Rats underwent to a sham surgery (Sham group) received solvent injection. At the end of surgery, the rats were submitted to neurofunctional tests during 6 weeks. After this period, the animals were euthanized, and the anterior lumbar region of the spinal cord tissue was submitted to immunohistochemistry, western blot and real-time PCR analyses. The inhibitory response of CSPGs, the expression of neurotrophic factors (NT-3, GDNF, BDNF and FGF-2), the molecules associated with angiogenisis and apoptosis (laminin and Bcl-2), the proteins related to neuroplasticity (MAP-2, GAP-43 and synaptophysin), as well the Eph/ephrin system and the RhoA, which is able to modulate the fibers growth, were evaluated. The results showed a spontaneous, and parcial, recovery of the sensory motor behavior of the animals that were underwent to a photothrombotic injury, and the treatment with PEDF was able to potentiate some of these parameters. The analysis of the anterior lumbar region of the spinal cord, caudally to the lesion, showed a decrease of CSPGs, which may have favored the neuroplasticity events. The treatment with PEDF was able to promote the regulation of NT-3 and GDNF, as well the reduction of laminin and the increase of MAP-2 in that region. In relation to the Eph/ephrin system, the ischemic spinal cord injury was able to modulate the EphA4 receptor and ephrin-B1 expression, and the treatment with PEDF possibly regulated the activation state of ephrin-A2 and ephrin-B3 and certainly modulated the ephrin-B2 activation. Eph receptors and ephrins have been found specifically in neurons and astrocytes. Our results confirmed the plastic capacity of the spinal cord after injury and showed that the treatment with PEDF was able to enhance this process

O fator derivado do epitélio pigmentado (PEDF) é um fator neurotrófico que possui um grande potencial trófico nos neurônios motores da medula espinal, bem como é capaz de modular o microambiente da lesão. Desta forma, analisamos a capacidade do tratamento com PEDF em promover a neuroplasticidade da medula espinal após lesão isquêmica. Ratos Wistar adultos foram submetidos à lesão medular isquêmica do tipo fototrombótica, segundo o método de Rose Bengal, na altura do 11° segmento torácico e foram imediatamente tratados com inoculação local de PEDF (grupo PEDF) ou solvente (grupo Salina). Ratos submetidos à cirurgia simulada (grupo Sham) receberam a injeção do solvente. Ao término do procedimento cirúrgico, os ratos foram submetidos a testes neurofuncionais durante 6 semanas. Após esse período, os animais sofreram eutanásia e o tecido medular foi dividido entre as técnicas de imunoistoquímica, western blot e PCR em tempo real. Foi analisada na região lombar anterior da medula espinal a modulação das CSPGs, a expressão dos fatores neurotróficos NT-3, GDNF, BDNF e FGF-2, bem como os níveis das moléculas associadas à angiogênese e apoptose (laminina e Bcl-2), das proteínas relacionadas à neuroplasticidade (MAP-2, GAP-43 e sinaptofisina) e do sistema Eph/efrina e a RhoA, que são capazes de modular o crescimento de fibras. Os resultados mostraram uma recuperação parcial e espontânea do comportamento sensório-motor dos animais que foram submetidos à lesão fototrombótica, onde o tratamento com PEDF foi capaz de potencializar alguns desses parâmetros. A análise da região lombar anterior da medula espinal, caudal à lesão, mostrou uma diminuição das CSPGs nos dois grupos lesados, o que pode ter favorecido os eventos de neuroplasticidade. O tratamento com PEDF foi capaz de promover a regulação dos fatores neurotróficos NT-3 e GDNF, diminuir a angiogênese local (diminuição da laminina) e potencializar o processo de neuroplasticidade (aumento da MAP-2) nessa região. A lesão medular isquêmica foi capaz de modular a expressão do receptor EphA4 e da efrina-B1 e o tratamento com PEDF possivelmente regulou o estado de ativação da efrina-A2 e da efrina-B3 e certamente modulou a ativação da efrina-B2. Ainda, os receptores Eph e as efrinas foram observados diferentemente nos neurônios e astrócitos. Nossos resultados confirmam a capacidade plástica da medula espinal após lesão e mostra que o tratamento com PEDF foi capaz de potencializar esse processo / The pigment epithelium derived factor (PEDF) is a neurotrophic factor that has a great trophic potential in the motor neurons of the spinal cord, and is able to modulate the lesion microenvironment. We analyzed the capacity of the treatment with PEDF to promote the neuroplasticity after ischemic spinal cord injury. Adult male Wistar rats were underwent to photothrombotic ischemic spinal cord injury, according to the Rose Bengal method, at the level of 11° thoracic segment, and were immediately treated with local injection of PEDF (PEDF group) or solvent (Saline group). Rats underwent to a sham surgery (Sham group) received solvent injection. At the end of surgery, the rats were submitted to neurofunctional tests during 6 weeks. After this period, the animals were euthanized, and the anterior lumbar region of the spinal cord tissue was submitted to immunohistochemistry, western blot and real-time PCR analyses. The inhibitory response of CSPGs, the expression of neurotrophic factors (NT-3, GDNF, BDNF and FGF-2), the molecules associated with angiogenisis and apoptosis (laminin and Bcl-2), the proteins related to neuroplasticity (MAP-2, GAP-43 and synaptophysin), as well the Eph/ephrin system and the RhoA, which is able to modulate the fibers growth, were evaluated. The results showed a spontaneous, and parcial, recovery of the sensory motor behavior of the animals that were underwent to a photothrombotic injury, and the treatment with PEDF was able to potentiate some of these parameters. The analysis of the anterior lumbar region of the spinal cord, caudally to the lesion, showed a decrease of CSPGs, which may have favored the neuroplasticity events. The treatment with PEDF was able to promote the regulation of NT-3 and GDNF, as well the reduction of laminin and the increase of MAP-2 in that region. In relation to the Eph/ephrin system, the ischemic spinal cord injury was able to modulate the EphA4 receptor and ephrin-B1 expression, and the treatment with PEDF possibly regulated the activation state of ephrin-A2 and ephrin-B3 and certainly modulated the ephrin-B2 activation. Eph receptors and ephrins have been found specifically in neurons and astrocytes. Our results confirmed the plastic capacity of the spinal cord after injury and showed that the treatment with PEDF was able to enhance this process

PEDF (pigment epithelium derived factor) joue un rôle de gène suppresseur de tumeurs dans plusieurs cancers humains. PEDF est impliqué entre autres dans l'arrêt de la prolifération, dans la migration et dans le potentiel d'invasion de plusieurs modèles cellulaires tumoraux. PEDF est également impliqué dans l'apoptose et aussi dans l'inhibition du processus d'angiogénèse chez les cellules endothéliales de plusieurs organes. Notre laboratoire a démontré que PEDF est modulé à la hausse dans des cellules épithéliales intestinales déficientes pour l'expression de NCOR1 (nuclear receptor corepressor 1). Cependant, le lien transcriptionnel entre ces molécules et le rôle de PEDF au sein de l'épithélium intestinal demeurent peu élucidés. L'hypothèse de ce travail fut que la transcription du gène PEDF est contrôlée par NCOR1 au niveau des cellules épithéliales intestinales humaines et que PEDF agit comme gène suppresseur de tumeurs dans ce contexte. Nos résultats ont permis de démontrer que le gène PEDF est régulé transcriptionnellement par les récepteurs à l'acide rétinoïque et par le corépresseur NCOR1. Des analyses de PCR en temps réel ont permis de montrer une distribution spécifique de PEDF au sein des diverses lignées cellulaires cancéreuses colorectales. Les résultats obtenus ont montré que seules quelques lignées cellulaires cancéreuses colorectales expriment PEDF. Les niveaux d'expression des régulateurs de PEDF identifiés précédemment (NCOR1, RAR[alpha] et RXR[alpha]) ont été mesurés par PCR quantitatif en relation avec les variations d'expression de PEDF au sein des lignées cancéreuses colorectales humaines. Des immunofluorescences et des immunobuvardages ont montré que la protéine PEDF est détectable au niveau des cellules épithéliales localisées au niveau des villosités intestinales du jéjunum et de l'illéon chez le foetus humain. Les modèles DLD1, HT29 et HCT116 qui ne possède [i.e. possèdent] qu'une faible expression de PEDF ont été utilisés afin de moduler à la hausse l'expression de PEDF et ainsi pouvoir étudier l'impact de cette protéine dans ces modèles. La surexpression de PEDF dans les cellules DLD1 a permis d'observer un ralentissement de la prolifération de celles-ci. Des essais de croissance en absence d'ancrage en utilisant les cellules DLD1, HT29 et HCT116 ont montrés [i.e. montré] que PEDF est capable de ralentir la croissance en absence d'ancrage des cellules DLD1 et HT29, mais pas des cellules HCT116. Des essais préliminaires d'angiogenèse in vivo ont permis de suggérer que la surrexpression [i.e. surexpression] de PEDF dans les cellules HT29 pourrait réguler négativement l'angiogenèse tumorale de même que le processus de croissance tumorale. Finalement, le statut d'expression de PEDF a été mesuré dans une banque de tissus provenant de patients atteints de cancer colorectal. Les résultats obtenus lors de ces travaux suggèrent que PEDF joue un rôle fonctionnel au sein de l'épithélium intestinal et supportent l'hypothèse selon laquelle PEDF agit en tant que gène suppresseur de tumeurs dans les cellules épithéliales intestinales humaines.

Der ischämische Schlaganfall gehört wegen seiner Folgen wie beispielsweise persistierenden Lähmungen und Sprachstörungen bis hin zum Versterben des Patienten angesichts der hohen Inzidenz zu den derzeit sozioökonomisch bedeutsamsten Krankheitsbildern (Ward et al. 2005, Kolominsky-Rabas et al. 2006). Die Möglichkeiten der Akutbehandlung sind trotz intensiver Forschungsbemühungen während der letzten Jahrzehnte nicht zufriedenstellend, da hierfür nur ein vergleichsweise geringer Anteil der Patienten in Frage kommt. Der Einsatz von neuroprotektiven Substanzen stellt eine vielversprechende Option dar, auch wenn bisher kein Neuroprotektivum den regelhaften klinischen Einsatz erreicht hat. Die vorliegende tierexperimentelle Arbeit an Ratten analysierte den Einfluss der beiden intravenös applizierten Faktoren pigment epithelium-derived factor (PEDF) und epidermal growth factor (EGF) auf die Bestandteile der Blut-Hirn-Schranke (BHS) bei zerebraler Ischämie. Diese Arbeit basiert ganz wesentlich auf der Studie von Pillai et al. (2013), in der intravenös appliziertes PEDF im Schlaganfall-Tiermodell zum Einsatz kam: Beide Faktoren verkleinerten nach einstündigem filamentären Verschluss der Arteria cerebri media und anschließender Reperfusion die mittels Magnetresonanztomographie (MRT) bestimmte ischämische Läsionsgröße. Darüber hinaus führten sie im geschädigten Gebiet - verglichen mit der Kontrollgruppe - zu einer verringerten Ödembildung. Dabei erzielte die Intervention durch PEDF stärkere Effekte gegenüber der Behandlung mit EGF, im Besonderen wurde in der PEDF- Gruppe die weitere Zunahme des Ödems im Infarktareal und dem unmittelbar angrenzenden Gewebe nach 48 Stunden verringert. Beiträge zur Aufklärung hierfür verantwortlicher molekularer Mechanismen durch histochemische Untersuchungen des Hirngewebes waren Ziel der vorliegenden Arbeit. Hierzu wurde den Tieren das Hirngewebe an Tag 7 nach induziertem Infarkt entnommen und für die immunhistochemische Analyse aufgearbeitet. Mit einem Gefrierschnittmikrotom wurden 30 μm dicke Frontalschnitte der Paraformaldehyd- fixierten Vorderhirnblöcke von 26 Tieren angefertigt. Als Regions of Interest (ROI) innerhalb der Schnitte wurden die striatale Ischämiezone (Infarktkern), eine ipsilateral striatal gelegene, weniger Ischämie-betroffene Zone (Grenzzone), das kontralaterale Striatum (Kontrolle) sowie ein ischämisches Kortexareal festgelegt. Qualitative Analysen umfassten neben wichtigen zellulären Komponenten der BHS, den Astrozyten und Endothelzellen, auch Mikroglia/Makrophagen sowie das azelluläre Basalmembranprotein Kollagen IV. Alle Versuchsgruppen zeigten eine deutliche Hochregulierung von Kollagen IV im zentralen Infarktgebiet, verglichen mit der kontralateralen Hirnregion. Andere Arbeiten hatten diese Überexpression von Kollagen IV zu früheren Zeitpunkten nach Schlaganfall bereits beschrieben (Beaten und Akassoglou 2011, Ji und Tsirka 2012, Summers et al. 2013); neu ist die Persistenz der Hochregulierung bis mindestens Tag 7 nach fokaler zerebraler Ischämie. Im gleichen Ischämie-beeinflussten Gebiet konnten morphologische Zeichen eines veränderten Aktivitätszustandes von Mikroglia/Makrophagen festgestellt werden. In den Regionen, die nicht direkt von der Ischämie betroffen waren (z.B. dem kontralateralen Striatum), stellten sich ramifizierte Mikrogliazellen in mäßiger Dichte dar. Im Gegensatz dazu akkumulierten amöboide Mikroglia/Makrophagen im Infarktareal. In der Übergangszone zwischen geschädigtem Gewebe und nicht direkt Ischämie-betroffenen Regionen zeigte sich in allen Tieren die Ausprägung einer Astroglianarbe, bestehend aus einer dichten Formation von stark GFAP-markierten Astrozyten. Bei der semiquantitativen Gegenüberstellung der einzelnen Untersuchungsgruppen wiesen die mit PEDF behandelten Ratten in Relation zur Kontrollgruppe eine um den Faktor 3 geringere Hochregulierung von Kollagen IV im Infarktgebiet auf. Im Areal der Infarktpenumbra war die Intensität des GFAP-Immunsignals der PEDF-Gruppe im Vergleich zur EGF-Gruppe verdoppelt. Darüber hinaus schienen die Faktoren keinen Einfluss auf die Akkumulation/Morphologie von Mikroglia/Makrophagen im Infarktgebiet zu haben. Hervorzuheben ist die in PEDF-behandelten Ratten gegenüber EGF-behandelten Tieren und Kontrolltieren verringerte Kollagen IV-Hochregulierung im Infarktgebiet und die verstärkte Bildung einer GFAP-immunopositiven Astroglianarbe in der ischämischen Grenzzone. Beide Befunde eignen sich zur Erklärung der durch Pillai et al. (2013) erzielten Ergebnisse. Hinweise für den molekularen Mechanismus, der der Verringerung der BHS-Permeabilität zugrunde liegt, finden sich in vorausgegangenen Studien, die einen antiangiogenetischen Effekt von PEDF über eine Abschwächung des VEGF-Pathways beschrieben haben (Dawson 1999, Liu et al. 2004, Zhang et al. 2006). Die Wirkung von intravenös appliziertem PEDF als neuroprotektive Therapieoption des Hirninfaktes benötigt weitere Untersuchungen um die in beiden Arbeiten festgestellten Effekte zu bestätigen. Hierbei erscheint ein Tiermodell sinnvoll, das – analog zur klinischen Situation – rekanalisierende Therapien wie die Thrombolyse oder mechanische Rekanalisation berücksichtigt. Zusätzliche Mehrfachmarkierungen ermöglichten neue qualitative Aussagen zur zerebralen Ischämie im Rattenmodell, die Ansatzpunkte für weitere Untersuchungen bieten. Die nähere Charakterisierung von Gefäßveränderungen nach fokaler zerebraler Ischämie gelang durch eine Dreifachmarkierung von STL, Kollagen IV und Fibronektin. Hier zeigte sich neben der bereits oben beschriebenen Hochregulation von Kollagen IV auch eine verstärkte Expression von Fibronektin im Bereich des Infarktkerns, kolokalisiert mit STL-markierten Mikroglia/Makrophagen. Das Areal mit deutlicher Fibronektinmarkierung war flächenmäßig erheblich größer als der Kollagen IV-immunpositive Bereich. Die Analyse der Basalmembranbestandteile kann neue Erkenntnisse zum Mechanismus der ischämischen Schädigung der BHS bei fokaler zerebraler Ischämie im Tiermodell liefern und bietet sich möglicherweise als Indikator für das Schädigungsausmaß an. Darüber hinaus waren im stark Kollagen IV-markierten ischämischen Kernbereich Aquaporin 4 (AQP4)-immunpositive Astrozytenfortsätzen fast vollständig eliminiert. Mit größerer Entfernung vom ischämischen Kern nahm in der Grenzzone die AQP4-Dichte zu, während die Kollagen IV-Immunmarkierung schwächer wurde. Dieser Befund deutet auf eine Regulation der Kollagen IV-Expression durch einen intakten Endothelzell-Astrozytenendfuß-Kontakt hin, der in der Ischämiezone aufgehoben scheint. Ein Verlust von Astrozytenendfuß-Endothelzell-Kontakten im Schlaganfall- Tiermodell wurde in einer vorangegangenen Arbeit bereits beschrieben (Ito et al. 2011). Zudem fanden Kwon et al. (2009) eine positive Korrelation zwischen der Anzahl von intakten Astrozyten-Basalmembran-Kontakten zur Dicke der BM im striatalen Kapillargebiet von Ratten. Darüber hinaus konnten Yang und Rosenberg (2011) zeigen, dass in der frühen Phase der zytotoxischen Ödemformation nach Schlaganfall Tiere mit Deletion von AQP4 eine verringerte Ödembildung aufwiesen, wogegen in einer späteren Phase, in der das vasogene Ödem dominiert, AQP4 als passives Wasserkanalprotein die Beseitigung des Ödems beschleunigte (Zador et al. 2007). Die Ergebnisse der vorliegenden Arbeit legen die pathophysiologische Bedeutung AQP4- positiver Astrozytenfortsätze und ihrer Gefäßkontakte speziell im Periinfarktgebiet nahe, sodass diese Strukturen in weiterführenden Studien hinsichtlich ihrer therapeutischen Modulierbarkeit fokussiert werden sollten.:1 Einleitung 1.1 CharakterisierungdesSchlaganfalls 1.1.1 Begriffsdefinition 1.1.2 Epidemiologie 1.2 Blut-Hirn-Schranke (BHS) und Neurovaskuläre Einheit (NVU) 1.2.1 Zelluläre und azelluläre Bestandteile der BHS 1.2.2 DiffusionundaktiverTransport 1.2.3 ElektrolyteundWasserhomöostase 1.2.4 Astrozyten 1.2.5 MikrogliaundMakrophagen 1.2.6 Perizyten 1.3 PathophysiologiedesSchlaganfalls 1.3.1 PerfusionundexzitatorischeReaktion 1.3.2 Zelluläre und molekulare Mechanismen der Inflammation 1.4 TherapiedesSchlaganfalls 1.4.1 ThrombolysemittelsAlteplase(rtPA) 1.4.2 IntraarterielleBehandlung 1.4.3 Basistherapie 1.5 Experimentelle Grundlagen der vorliegenden Arbeit 2 Zielstellung 3 Studiendesign, Material und Methoden 3.1 Studiendesign 3.2 Material 3.2.1 UntersuchtesGewebe 3.2.2 Chemikalien 3.2.3 Lösungen 3.2.4 Mehrfachmarkierungen 3.3 Methoden 3.3.1 OperativesVorgehen 3.3.2 Behandlung mit EGF und PEDF 3.3.3 Gewebevorbereitung 3.3.4 Fluoreszenzmarkierungen 3.3.5 Ausschlusskriterien 3.4 Auswertung 3.4.1 Fluoreszenzmikroskopie 3.4.2 Semiquantitative Analyse von Kollagen IV, GFAP und Iba 3.4.3 QualitativeAnalysen 4 Ergebnisse 5 Diskussion 5.1 Tiermodell 5.2 OperativesVerfahren;tMCAO 5.3 VEGFundAQP4 5.4 KollagenIVundFibronektin 5.5 DetektionvonAstroglia 5.6 DarstellungvonMikrogliaundMakrophagen 5.7 PEDFundEGFalsNeuroprotektiva 6 Zusammenfassung der Arbeit

The demise of retinal ganglion cells (RGCs) is characteristic of diseases of the retina such as glaucoma and diabetic or ischemic retinopathies. Pigment epithelium-derived factor (PEDF) is a multifunctional secreted protein that mediates neuroprotection and inhibition of angiogenesis in the retina. We have studied expression and regulation of two of several receptors for PEDF, patatin-like phospholipase 2 gene product/PEDF-R and laminin receptor (LR), in serum-starved RGC under normoxia and hypoxia and investigated their involvement in the survival of retinal neuronal cells. We show that PEDF-R and LR are co-expressed in RGC and R28 retinal precursor cells. Expression of both receptors was enhanced in the presence of complex secretions from retinal glial (Müller) cells and upregulated by VEGF and under hypoxic conditions. PEDF-R- and LR-knocked-down cells demonstrated a markedly attenuated expression of anti-apoptotic Bcl-2 family members (Bcl-2, Bcl-xL) and neuroprotective mediators (PEDF, VEGF, BDNF) suggesting that both PEDF-R and LR mediate pro-survival effects of PEDF on RGC. While this study does not provide evidence for a differential survival-promoting influence of either PEDF-R or LR, it nevertheless highlights the importance of both PEDF receptors for the viability of retinal neurons.

BACKGROUND: Prostate cancer is the most common cancer among Swedish men. For patients with metastatic prostate cancer the standard therapy is castration, a treatment that initially provides symptomatic relief but unfortunately is not curative. New therapeutic targets for advanced prostate cancer are therefore needed.  Prostate cancers are composed of tumor epithelial cells as well as many non-epithelial cells such as cancer associated fibroblasts, blood vessels and inflammatory cells.  Many components of the tumor microenvironment such as tumor associated macrophages and angiogenesis have been shown to stimulate tumor progression. This thesis aims to explore mechanisms by which the local environment influences prostate tumor growth and how such mechanisms could be targeted for treatment. MATERIALS AND METHODS: We have used animal models of prostate cancer, in vitro cell culture systems and clinical materials from untreated prostate cancer patients with long follow up. Experiments were evaluated with stereological techniques, immunohistochemistry, western blotting, quantitative real-time PCR, PCR arrays and laser micro dissection. RESULTS: We found that the presence of a tumor induces adaptive changes in the surrounding non-malignant prostate tissue, and that androgen receptor negative prostate tumor cells respond to castration treatment with temporarily reduced growth when surrounded by normal castration-responsive prostate tissue. Further, we show that macrophages are important for prostate tumor growth and angiogenesis in the tumor and in the surrounding non-malignant tissue. In addition, the angiogenesis inhibitor Pigment epithelium-derived factor (PEDF) was found  to be down-regulated in metastatic rat and human prostate tumors. Over-expression of PEDF inhibited experimental prostate tumor growth, angiogenesis and metastatic growth and stimulated macrophage tumor infiltration and lymphangiogenesis. PEDF was found to be down-regulated by the prostate microenvironment and tumor necrosis factor (TNF) α. CONCLUSIONS: Our studies indicate that not only the nearby tumor microenvironment but also the surrounding non-malignant prostate tissue are important for prostate tumor growth. Both the tumor and the surrounding non-malignant prostate were characterized by increased angiogenesis and inflammatory cell infiltration. Targeting the surrounding prostate tissue with castration, targeting tumor associated macrophages, or targeting the vasculature directly using inhibitors like PEDF were all shown to repress prostate tumor growth and could prove beneficial for patients with advanced prostate cancer.

The aim of diploma thesis Teachers personality in the 21st century is to point out the importance of the human spiritual dimension, as well as the importance of personality development of every teacher. The thesis is trying to disclose which of the challenges are teachers facing nowadays and how the students and pupils themselves are affected by their lecturers. The paper describes the transformation of the teacher's role in present-day society. Two different approaches in teachers training are presented and compared - classical higher education and Waldorf education. The theoretical part of the thesis deals with the definition of the personality concept regarding a psychological point of view, as well as the definition of teacher education paradigm transformation relating to key competences and professional teachers standards. One section of the text is describing the basic principles of Waldorf pedagogy. The empirical part consists of an analysis of two different teacher education approaches, obtained through interviews with representatives of the Faculty of Education of Charles University in Prague and Freie Hochschule in Stuttgart. The benefit of this thesis is to bring the description of the educational model, which emphasises on a artistic process in the future teachers education, into the...