Islet transplantation is an attractive method to achieve blood glucose homeostasis. However, β-cell function declines over time. Therefore, it is necessary to explore strategies to enhance the β-cell mass and function. Also, because there is a severe shortage of human cadaver tissue, alternative sources of insulin secreting tissue need to be examined. Neonatal porcine islet (NPI) tissue has emerged as an attractive alternative source of β-cells. The aim of this thesis was to optimize the culturing conditions of NPIs pre-transplantation so that the available tissue can be used as efficiently and economically as possible. The results from this study indicate that the treatment of NPI cultures with z-VAD-FMK, a pan caspase inhibitor and general protease inhibitor significantly enhances β-cell survival. Additionally, the optimum length of culturing NPIs pre-transplantation appears to be 3-5 days. Since widespread cell death stimulates immunogenic response, this treatment also has the potential benefit of reducing immunosuppression needs in the recipient. / Experimental Surgery

This thesis tests the hypothesis that increased neuronal cell death in SIDS infants is related to the ability of risk factors, such as prone sleeping, to expose infants to intermittent hypercapnic hypoxia (IHH). Based on the hypothesis that the NMDA system is linked to neuronal death, by way of excitotoxicity, correlations were also sought between cell death and changes in NMDA receptor (NR1) expression in brainstem nuclei controlling cardiorespiratory function. The first aim of this study was to verify that increased neuronal cell death occurs in SIDS infants. To verify a piglet model of SIDS risk factors, brainstem changes were examined in piglets exposed to IHH, and comparisons were made to changes seen in SIDS infants. The NMDA receptor was characterised in controls for both the human infant and the piglet groups. Comparisons of neuronal changes were made with SIDS infants, and piglets exposed to IHH. Non-radioactive in-situ hybridisation and immunohistochemistry were performed on formalin fixed and paraffin embedded brainstem tissue to identify markers of cell death (caspase-3, active caspase-3, and TUNEL), and to examine NR1 mRNA and protein expressions. Staining was quantified using computerised image analysis software. Eight nuclei from the brainstem medulla (caudal in piglets, and mid in infants), and two nuclei from the rostral pons (infants) were studied. The first dataset included human infants aged 1-6 months with a diagnosis of SIDS (n=15) or non-SIDS (n=10). The second dataset comprised developing piglets aged 13-14 days, with controls (n=6), against those exposed to IHH for 2 (n=6) or 4 (n=5) days. Increased neuronal cell death was not verified in the SIDS infants, but abnormalities in NR1 expression were present in selected nuclei of the medulla. Piglets exposed to IHH had increased neuronal cell death and changes in NR1 in selected nuclei of the medulla. There was also a positive correlation between increased cell death and high NR1 levels. Preliminary data showed that SIDS infants who usually slept prone had some differences in NR1 compared to those who did not usually sleep prone. From these findings, it was concluded that IHH may underlie the abnormalities in NMDA receptor expression that are present in the brainstem of SIDS infants. Although IHH can induce an increase in neuronal cell death, its significance in the aetiology of SIDS is not known. In piglets, IHH induced cell death correlated with high NMDA expression in some brainstem nuclei, supporting the hypothesis that excitotoxicity may be involved in the mechanism for cell death. Moreover, this thesis presents for the first time, �preliminary pathological proof� of an association between prone sleeping and abnormal NMDA receptor expression in SIDS infants.

Thesis (M.Sc.). / Written for the Dept. of Biochemistry. Title from title page of PDF (viewed 2008/07/30). Includes bibliographical references.

Thesis (Ph. D.)--Cornell University, January, 2009. / Vita. Includes bibliographical references (leaves 104-114).

Avhandling : Zoomorfologi : Göteborg. / Notes bibliogr.

Thesis (Ph. D.)--Cornell University, May, 2008. / Vita. Includes bibliographical references (leaves 148-168).

C-Kit est généralement considéré comme un récepteur à tyrosine kinase et comme un proto-oncogène, dont la surexpression et la mutation conduisent à une progression tumorale médiée par son activité kinase. En clinique, les traitements ciblant l’activité kinase de c-Kit, comme l’Imatinib (Gleevec), ont été largement utilisés pour traiter les patients atteints de maladies liées à c-Kit. Alors que le rôle de c-Kit comme proto-oncogène ne fait aucun doute, certaines études et analyses de bases de données diffèrent avec l’idée d’un rôle pro-tumoral de c-Kit, laissant penser à un rôle différent de c-Kit dans le cancer. Ici, nous montrons que c-Kit appartient à la famille des récepteurs à dépendance, de la même façon que d’autres récepteurs de la famille des tyrosine kinases tel que MET, RET et TrkC. En absence de son ligand Stem Cell Factor (SCF), au lieu de rester inactif, c-Kit déclenche l’apoptose, qui peut être renforcée par l’invalidation de son activité kinase. En parallèle, nous montrons que c-Kit est capable de se lier à la caspase-9 et de l’activer. De plus, à la manière d’autres récepteurs à dépendance, c-Kit est aussi clivé par des protéases de type caspase sur son résidu acide aspartique D816, qui est nécessaire à son activité pro-apoptotique. La mutation du site D816 inhibe l’interaction entre c-kit et la caspase-9 et invalide l’activité pro-apoptotique de c-Kit. De façon intéressante, la mutation D816 est l’une des mutations les plus communes de ce récepteur dans la plupart des cancers liés à c-Kit, et cette mutation favorise la résistance au traitement Gleevec. Nous montrons aussi que la surexpression de c-Kit invalidé pour son activité kinase est capable d’inhiber la croissance tumorale dans des modèles animaux, alors que la mutation du site D816 empêche son effet suppresseur de tumeur. En outre, nous avons développé un outil permettant de bloquer l’interaction entre SCF et c-Kit, déclenchant l’activité pro-apoptotique de c-Kit dans les cancers positifs pour ce récepteur. En utilisant l’activité pro-apoptotique de c-Kit, en combinaison avec des inhibiteurs de kinases comme le Gleevec, nous proposons une nouvelle stratégie thérapeutique. En conclusion, nous démontrons que c-Kit est un membre de la famille des récepteurs à dépendance, présentant une activité pro-apoptotique, et pouvant être utilisé comme un outil alternatif dans le cadre d’un traitement contre le cancer / C-Kit has been generally considered as a receptor tyrosine kinase and a proto-oncogene, whose upregulation and mutation lead to tumor progression through its kinase activity. Clinically, drugs targeting the kinase activity of c-Kit, such as Imatinib (Gleevec), have been wildly used to treat patients with c-Kit related diseases. While the role of c-Kit as a proto-oncogene is of no doubt, some research reports and database analysis do not fit well the tumor promoting role of c-Kit, indicating a possible different role of c-Kit in cancer. Here, we show that c-Kit belongs to the dependence receptor family, similarly to other receptor tyrosine kinases such as MET, RET and TrkC. In the absent of its ligand SCF (stem cell factor), instead of staying inactive, c-Kit triggers apoptosis, which can be enhanced by silencing its kinase activity. Besides, we have shown that c-Kit is able to bind and activate caspase-9. Moreover, similarly to other dependence receptors, c-Kit is also cleaved by caspases-like protease at aspartic acid residue D816, which is crucial for its pro-apoptotic activity. The mutation of D816 site inhibits the c-Kit/caspase-9 binding and silences the pro-apoptotic activity of c-Kit. Of interest, c-Kit D816 mutation is one of the most common mutation of this receptor in many c-Kit related cancers and it promotes resistance against Gleevec treatment. We also show that overexpression of kinase mutated c-Kit is able to inhibit tumor growth in animal models, while the mutation of D816 site impairs the tumor suppressing activity. Furthermore, we develop a tool to block the SCF/c-Kit interaction, which unleashes the pro-apoptotic activity of c-Kit in cancers expressing this receptor. By using the pro-apoptotic activity of c-Kit, in combination with kinase inhibitors like Gleevec, we propose a novel therapeutic strategy. In conclusion, we demonstrate that c-Kit is a member of dependence receptor family, harboring intrinsic pro-apoptotic activity, which can be used as an alternative tool in cancer treatment

A encefalopatia hipóxico-isquêmica neonatal, ou simplesmente hipóxia-isquemia (HI) neonatal, é uma das principais causas de morbidade e mortalidade em neonatos humanos. De 20% a 50% dos recém-nascidos com HI severa morrem no período perinatal. Quando sobrevivem, 25% apresentam deficiências neuropsicológicas, como dificuldade de aprendizado, epilepsia e paralisia cerebral. Devido a isso, a eficácia de possíveis agentes neuroprotetores tem sido testada em modelos animais. Há razão para se pensar que a progesterona tem um forte potencial para o tratamento da HI neonatal, já que a sua utilização tem se mostrado benéfica em pesquisas relacionadas com lesão cerebral traumática, lesão cerebral isquêmica e outros modelos de lesão do sistema nervoso central (SNC) em adultos. Inúmeros estudos têm mostrado que o modelo animal de HI de Rice e Vannucci (1981) em animais neonatos, utilizado no presente trabalho, pode produzir lesões no sistema nervoso central relativamente previsíveis, e que estas lesões encefálicas parecem semelhantes às observadas clinicamente em humanos (SALMASO et al., 2014). Para a realização do modelo de HI foram utilizados ratos Wistar com idade de 7 dias (P7). Após a oclusão da carótida esquerda, os animais foram colocados em câmaras para exposição à atmosfera hipóxica com 8% O2/92% N2 por 90 minutos. Os animais foram divididos em cinco grupos experimentais: SHAM, HI, HI+PROG-PRÉ (PRÉ), HI+PROG-PÓS (PÓS), HI+PROG-PRÉ/PÓS (PP). Os termos PRÉ e PÓS referem-se à administração de progesterona (na dose de 5 mg/kg) antes ou após o procedimento de HI neonatal . Dependendo do grupo experimental, os animais foram tratados com progesterona imediatamente antes da isquemia e/ou 6 e 24 horas após o início da hipóxia. Foram analisados o peso corporal dos animais (imediatamente antes da isquemia e 6, 24 e 48 horas após o início da hipóxia), o volume de lesão cerebral, além da expressão das proteínas p-Akt e caspase-3 pela técnica de Western blotting. / Neonatal hypoxic-ischemic encephalopathy or simply neonatal hypoxia-ischemia (HI) is a main cause of morbidity and mortality in human neonates. Moreover, 25% of survivors show neuropsychological dysfunctions such as learning difficulties, epilepsy and cerebral palsy. Because of this, the effectiveness of potential neuroprotective agents has been tested in animal models. There is a reason to suppose that progesterone has a strong potential for the treatment of neonatal HI since its use has been shown to be beneficial in researches related to traumatic brain injury, ischemic brain injury and other central nervous system injury models (CNS) in adults. Several studies have shown that the newborn animal model of HI developed by Rice and Vannucci (1981), and used in the present study, can produce lesions in the central nervous system which are predictable and similar to those observed clinically in humans. In order to perform the HI model we used 7 days old (P7) Wistar rats. After occlusion of the left carotid, the animals were placed in hypoxic chambers and exposed to the hypoxic atmosphere (8% O2/92% N2 for 90 minutes). The animals were divided into five groups: SHAM, HI, HI+PROG-PRÉ (PRÉ), HI+PROG-PÓS (PÓS), HI+PROG-PRÉ/PÓS (PP).The PRÉ and PÓS terms refer to the administration of progesterone (5 mg/kg) before and/or after the HI procedure. Progesterone was administered immediately before ischemia, 6 and 24 hours after the beginning of hypoxia, depending on the experimental group. Body weight was evaluated immediately before ischemia and/or 6 and 24 hours after the start of hypoxia. The volume of brain damage, in addition to the expression of p-Akt and caspase-3 were also evaluated.

Interleukin-1 alpha (IL-1a) is a powerful inflammatory cytokine that modulates both innate and adaptive immunity. As such, IL-1a is implicated in the development of multiple inflammatory and autoimmune diseases including atherosclerosis, arthritis and cancer. Therefore, understanding the mechanisms that regulate IL-1a activity is extremely important. For many years, pro-IL-1a was considered to be a fully active alarmin. However, we have previously shown that the removal of the pro-domain by calpain, a protease that is activated upon necrosis, significantly increases IL-1a bioactivity. The work presented in this thesis demonstrates that multiple proteases from diverse biological systems cleave and activate IL-1a. We therefore suggest that IL-1a is an important signalling hub that integrates diverse proteolytic danger signals to alert the immune system. In particular we have identified the inflammatory caspase, caspase-5, as a novel and potent activator of IL-1a. We show that caspase-5 directly cleaves pro-IL-1a during the activation of the non-canonical inflammasome by cytosolic LPS, which mimics intracellular bacterial infection. We also demonstrate that caspase-5-cleaved IL-1a mediates the senescence-associated secretory phenotype (SASP), which drives the deleterious effects of senescent cells in multiple age-related diseases. Therefore, therapeutically targeting caspase-5 may be of interest for pathologies mediated by the non-canonical inflammasome and/or senescent cells. Finally we find that rs17561, a common IL1A polymorphism, reduces active IL-1a release. We find that blood from minor allele homozygotes releases significantly less IL-1a than major allele homozygotes upon LPS stimulation. Therefore, genotyping patients under consideration for anti-IL-1a therapy could predict who would be likely to respond well to the treatment. In conclusion, the work presented in this thesis enhances our understanding of how IL-1a activity is regulated. The identification of both the caspase-5-mediated pathway of IL-1a activation and the defect conferred by the rs17561 SNP could have important clinical implications for the treatment of multiple inflammatory diseases.

Primary immunodeficiencies (PID) are genetic disorders characterized by increased susceptibility to infections and various degrees of immune dysregulation. With the expansion of massive parallel sequencing, an increasing number of defects in immune-related genes is being identified in PID. However, the biological impact of the found mutations is often unknown. It is necessary to devise methods to clarify their causality for disease development, which may also aid therapeutic decisions. One of the novel discoveries are gain-of-function mutations in STAT1 gene, resulting in chronic mucocutaneous candidiasis. Candidiasis may be ameliorated with antimycotics or with targeted JAK-STAT inhibitor, ruxolitinib. For our patient with a novel mutation in STAT1, we developed a simple test for the detection of phospho-STAT molecules in peripheral blood lymphocytes. The test confirmed the gain-of-function character of the identified mutation and was used to monitor ruxolitinib treatment efficacy. In the second patient, who presented with lymphadenopathy and immunodeficiency, the as yet undescribed mutation in CASP8 was found. We proved its loss-of-function property expressed as reduced caspase-8 and caspase-3 cleavage, impaired cellular apoptosis, and decreased NFB-related signaling. The third patient who...