Thesis (Ph. D.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains vi, 156 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

Diabetic nephropathy (DN) remains the most common cause of end stage renal failure. Nearly 10% of patients with diabetes develop nephropathy. Hyperglycaemia in the kidneys leads to the activation of alternative metabolic pathways of glucose (glycation, activation of protein kinase C, and polyol pathway). These biochemical alterations lead to hypoxia and oxidative stress due to the increased formation of reactive oxygen species (ROS). Cellular response to hypoxia is controlled by hypoxia-induced factor 1 (HIF1), which is involved in the regulation of more than 800 genes. Target molecules of the HIF1 pathway participate in a wide range of physiological and pathological processes, e.g. angiogenesis, energy metabolism, apoptosis, migration, and proliferation. DN is associated with the pathological tissue remodelling process, epithelial-mesenchymal transition (EMT), and inflammation. HIF1 regulates key molecules of these pathological processes. EMT is regulated by TGFß1, CTGF, and SOX9. The progression of inflammation is regulated by VEGFA and AngII. The exact role of HIF1 signalling in the development of DN is not yet fully understood. This thesis evaluates the functional role of the HIF1 signalling pathway in the development of DN using a global heterozygous mutant with the deletion of the Hif1α gene....

No description available.

L’hypoxie est une caractéristique commune des tumeurs solides et l’une des spécificités du micro environnement tumoral. L’hypoxie tumorale joue un rôle important dans l’angio génèse, la progression maligne, le développement de métastases, la chimio/radio-résistance et favorise l’échappement au système immunitaire du fait de l’émergence de variant tumoraux avec un potentiel de survie et de résistance à l’apoptose augmenté. Cependant, très peu de travaux ont étudié l’impact de l’hypoxie tumorale sur la régulation de la susceptibilité des tumeurs à la lyse induite par la réponse immune cytotoxique. Nous nous sommes donc demandé si l’hypoxie pouvait conférer aux tumeurs une résistance à la lyse induite par les lymphocytes T cytotoxiques (CTL). Nous avons démontré que l’exposition de cellules cibles tumorales à l’hypoxie possédait un effet inhibiteur sur la lyse de ces cellules tumorales par des CTL autologues. Cette inhibition n’est pas associée à des altérations de la réactivité de CTL ou de la reconnaissance des cellules cibles. Cependant, nous avons montré que l’induction hypoxique concomitante de la phosphorylation de STAT3 (pSTAT3) au niveau de la tyrosine 705 et du facteur HIF-1α (Hypoxia Inducible Factor-1 alpha) est liée fonctionnellement à l’altération de la susceptibilité de cellules tumorales bronchiques non à petites cellules (NSCLC) à la mort induite par les CTL. Nous avons aussi montré que la résistance de cellules tumorales bronchiques à la lyse CTL induite par l’hypoxie était associée à une induction d’autophagie dans les cellules cibles. En effet, l’inhibition de l’autophagie empêche la phosphorylation de STAT3 (via l’inhibition de la kinase Src) et restaure la susceptibilité des cellules tumorales hypoxiques à la lyse induite par les CTL. De plus, l’inhibition in vivo de l’autophagie par l’hydroxychloroquine (HCQ) dans le modèle murin portant la tumeur B16F10 and chez les souris vaccinée avec le peptide TRP2 augmente de façon drastique l’inhibition de la croissance tumorale. Collectivement, cette étude établit un nouveau lien fonctionnel entre l’autophagie induite par l’hypoxie et la régulation de la lyse induite par les cellules T spécifique d’antigènes et souligne le rôle majeur de l’autophagie dans le contrôle de la croissance tumorale in vivo.Finalement, étant donné que le la résistance tumorale à la lyse induite par les cellules tueuses est très probablement régulée par de multiples facteurs, nous avons aussi eu pour but d’identifier les micro-ARNs (miRs) régulés par l’hypoxie dans des modèles de NSCLC et de mélanome et leur implication putative dans la régulation de la susceptibilité tumorale à la lyse induite par les cellules T spécifique d’antigènes. Le micro-ARN 210 (miR-210) est ainsi significativement induit de manière dépendante de HIF-1α dans des cellules de NSCLC et de mélanome, et miR-210 est exprimé dans les zones hypoxiques de tissus issus de NSCLC. De plus, nous avons démontré que l’induction de miR-210 par l’hypoxie régule la susceptibilité tumorale à la lyse induite par les CTL en partie grâce à l’inhibition de l’expression de PTPN, HOXA1 et TP53I11, indiquant que miR-210 joue un rôle potentiel dans la régulation de la réponse immune antitumorale. / Hypoxia is a common feature of solid tumors and one of the hallmarks of tumor microenvironment. Tumor hypoxia plays an important role in angiogenesis, malignant progression, metastatic development, chemo-radio resistance and favours immune evasion by the emergence of tumor variants with increased survival and anti-apoptotic potential. There is very little work done on the impact of tumor hypoxia on the regulation of tumor susceptibility to the lysis induced by cytotoxic antitumor response. Therefore, we asked whether hypoxia confers tumor resistance to cytotoxic T lymphocyte (CTL)-mediated killing. We demonstrated that exposure of target cells to hypoxia has an inhibitory effect on the CTL-mediated autologous target cell lysis. Such inhibition was not associated with an alteration of CTL reactivity and tumor target recognition. We also showed that the concomitant hypoxic induction of Signal transducer and activator of transcription 3 (STAT3) phosphorylation on tyrosine 705 residue (pSTAT3) and hypoxia inducible factor 1 alpha (HIF-1α) is functionally linked to the alteration of Non small cell lung carcinoma (NSCLC) target susceptibility to CTL-mediated killing. We also showed that hypoxia-induced resistance of lung tumor to CTL-mediated lysis was associated with autophagy induction in target cells. Inhibition of autophagy resulted in impairment of pSTAT3 (via inhibition Src kinase) and restoration of hypoxic tumor cell susceptibility to CTL-mediated lysis. Moreover, in vivo inhibition of autophagy by hydroxychloroquine (HCQ) in B16F10 tumor bearing mice and mice vaccinated with TRP2 peptide dramatically increased tumor growth inhibition. Collectively, the current study establishes a novel functional link between hypoxia-induced autophagy and the regulation of antigen specific T cell lysis and points to a major role of autophagy in the control of in vivo tumor growth.Finally, as resistance of tumor targets to killer cells is likely to be regulated by multiple factors, we further aimed to identify the microRNA’s regulated by hypoxia in NSCLC and melanoma and their putative involvement in the regulation of tumor susceptibility to antigen-specific CTL-mediated killing. MicroRNA-210 (miR-210) was significantly induced in a HIF-1α dependent manner in NSCLC and melanoma cells and miR-210 was expressed in hypoxic zones of human NSCLC tissues. Moreover, we demonstrated that hypoxia-induced miR-210 regulates tumor cell susceptibility to CTL-mediated lysis in part by suppressing PTPN, HOXA1 and TP53I11 expression indicating that miR-210 plays a potential role in the regulation of anti-tumor immune response.

Thesis (Ph.D.)--University of Alabama at Birmingham, 2007. / Title from PDF title page (viewed on Feb. 19, 2010). Includes bibliographical references.

Thesis (Ph.D. in Immunology) -- University of Colorado Denver, 2008. / Typescript. Includes bibliographical references (leaves 174-182). Free to UCD Anschutz Medical Campus. Online version available via ProQuest Digital Dissertations;

No description available.

Hypoxia is a common feature of solid tumors and one of the hallmarks of tumor microenvironment. Tumor hypoxia plays an important role in angiogenesis, malignant progression, metastatic development, chemo-radio resistance and favours immune evasion by the emergence of tumor variants with increased survival and anti-apoptotic potential. There is very little work done on the impact of tumor hypoxia on the regulation of tumor susceptibility to the lysis induced by cytotoxic antitumor response. Therefore, we asked whether hypoxia confers tumor resistance to cytotoxic T lymphocyte (CTL)-mediated killing. We demonstrated that exposure of target cells to hypoxia has an inhibitory effect on the CTL-mediated autologous target cell lysis. Such inhibition was not associated with an alteration of CTL reactivity and tumor target recognition. We also showed that the concomitant hypoxic induction of Signal transducer and activator of transcription 3 (STAT3) phosphorylation on tyrosine 705 residue (pSTAT3) and hypoxia inducible factor 1 alpha (HIF-1α) is functionally linked to the alteration of Non small cell lung carcinoma (NSCLC) target susceptibility to CTL-mediated killing. We also showed that hypoxia-induced resistance of lung tumor to CTL-mediated lysis was associated with autophagy induction in target cells. Inhibition of autophagy resulted in impairment of pSTAT3 (via inhibition Src kinase) and restoration of hypoxic tumor cell susceptibility to CTL-mediated lysis. Moreover, in vivo inhibition of autophagy by hydroxychloroquine (HCQ) in B16F10 tumor bearing mice and mice vaccinated with TRP2 peptide dramatically increased tumor growth inhibition. Collectively, the current study establishes a novel functional link between hypoxia-induced autophagy and the regulation of antigen specific T cell lysis and points to a major role of autophagy in the control of in vivo tumor growth.Finally, as resistance of tumor targets to killer cells is likely to be regulated by multiple factors, we further aimed to identify the microRNA's regulated by hypoxia in NSCLC and melanoma and their putative involvement in the regulation of tumor susceptibility to antigen-specific CTL-mediated killing. MicroRNA-210 (miR-210) was significantly induced in a HIF-1α dependent manner in NSCLC and melanoma cells and miR-210 was expressed in hypoxic zones of human NSCLC tissues. Moreover, we demonstrated that hypoxia-induced miR-210 regulates tumor cell susceptibility to CTL-mediated lysis in part by suppressing PTPN, HOXA1 and TP53I11 expression indicating that miR-210 plays a potential role in the regulation of anti-tumor immune response.

O presente estudo avaliou a capacidade de invasão de hepatócitos de rato por Shigella flexneri (S. flexneri) nas condições de normóxia e hipóxia. O estudo do microambiente de hipóxia tem grande importância, por estar presente em muitas doenças hepáticas, além de aumentar a translocação quando presente no lúmen intestinal. Bactérias invasivas como S. flexneri podem romper a barreira intestinal e chegar ao fígado através da circulação portal. O efeito da invasão bacteriana das células hepáticas é pouco conhecido. Neste trabalho buscamos pesquisar as alterações morfológicas e funcionais de hepatócitos de rato após infecção por S. flexneri na presença e na ausência de hipóxia. Para esta finalidade foram utilizados hepatócitos de rato cultivados pela técnica de cultura primária. Vários parâmetros foram analisados, tais como: taxa de invasão celular pela bactéria, quantificação da produção e liberação de DHL, produção de TNF-, taxa de morte celular por apoptose e a expressão do fator de transcrição HIF-1a. Os resultados mostraram que a metodologia empregada para a obtenção do microambiente hipóxico foi satisfatória, com redução de 70% da pO2 inicial (atingindo 43.2 mmHg in vitro ou 6.5% O2). A invasão de hepatócitos de rato por S. flexneri foi menor nas células previamente expostas à hipóxia quando comparada com a invasão das células cultivadas em normóxia. A viabilidade dos hepatócitos não apresentou diferenças significativas entre os grupos experimentais, variando entre 74 e 86%. A liberação de TNF- nas situações de normóxia e hipóxia foi similar, embora as células infectadas em normóxia tenham aumentado a liberação desta citocina. Na condição de hipóxia + infecção a liberação de TNF- foi menor do que na condição de normóxia + infecção, porém ambos os grupos produziram aumento significativo da citocina em relação aos controles normóxicos e hipóxicos. Este resultado sugere que a presença da bactéria no interior das células aumenta significativamente a liberação de TNF-pelos hepatócitos. A produção de DHL também foi maior de forma significativa no grupo hipóxico em relação ao grupo normóxico, porém não apresentou alteração nos grupos infectados por S. flexneri após uma hora. As taxas de apoptose aumentaram nos grupos hipóxia e nos grupos infectados com S. flexneri de maneira similar, variando entre 24 e 31%, quando comparados aos grupos controle em normóxia. A expressão do fator de transcrição HIF ocorreu nos grupos: hipóxia, normóxia + infecção e hipóxia + infecção, evidenciando que a infecção por S. flexneri induz a expressão deste fator. Em seu conjunto, nossos resultados buscam contribuir para o maior conhecimento da interação entre S. flexneri e hepatócitos em condição de hipóxia e normóxia. Tal conhecimento poderá ser útil na construção de futuras estratégias para auxiliar no combate a esta importante bactéria invasiva, principalmente nos casos de septicemia / This study evaluated the invasiveness of rat hepatocytes by Shigella flexneri (S. flexneri) in normoxia and hypoxia conditions. The study of hypoxia microenvironment is of great importance, since hypoxia is present in many liver diseases and increases bacterial translocation when present in intestinal lumen. Invasive bacteria such as S. flexneri can disrupt the intestinal barrier and reach the liver through portal circulation. The effect of bacterial invasion in liver cells is poorly understood. In this study we investigated the morphological and functional changes of rat hepatocytes after infection with S. flexneri in the presence and absence of hypoxia. For this purpose we used primary cultures of rat hepatocytes. Several parameters were analyzed, such as: bacterial invasion cell rate, quantification of LDH production and release, TNF-a production, cell death rate by apoptosis and expression of the transcription factor HIF-1a. The results showed that the methodology used to obtain the hypoxic microenvironment was satisfactory, with 70% reduction of initial pO2 (to 43.2 mmHg in vitro or 6.5% O2). The invasion of rat hepatocytes by S. flexneri was lower in cells previously exposed to hypoxia compared with the invasion of cells grown in normoxia. The viability of hepatocytes showed no significant differences between experimental groups, ranging between 74% and 86%. The release of TNF-a in situations of normoxia and hypoxia was similar, although the infected cells in normoxia have increased the release levels of this cytokine. In hypoxia + infection condition the release of TNF-a was lower than normoxia + infection condition, but both groups produced a significant increase in cytokine release when compared to normoxic and hypoxic controls. This result suggests that the presence of bacteria inside the cells significantly increases the release of TNF-a by hepatocytes. DHL production was also significantly greater in the hypoxic group compared to the normoxic group, but had no change in the groups infected with S. flexneri after an hour. The apoptosis rates increased in hypoxia and infected groups in a similar way, varying between 24% and 31% when compared with control group in normoxia. The expression of HIF- 1a transcription factor occurred in hypoxia, normoxia + infection and hypoxia + infection groups, indicating that infection with S. flexneri induces the expression of this factor. Overall, our results sought to contribute to a greater understanding of the interaction between S. flexneri and hepatocytes under hypoxia and normoxia conditions. Such knowledge may be useful in building future strategies to assist in combating these major invasive bacteria

O presente estudo avaliou a capacidade de invasão de hepatócitos de rato por Shigella flexneri (S. flexneri) nas condições de normóxia e hipóxia. O estudo do microambiente de hipóxia tem grande importância, por estar presente em muitas doenças hepáticas, além de aumentar a translocação quando presente no lúmen intestinal. Bactérias invasivas como S. flexneri podem romper a barreira intestinal e chegar ao fígado através da circulação portal. O efeito da invasão bacteriana das células hepáticas é pouco conhecido. Neste trabalho buscamos pesquisar as alterações morfológicas e funcionais de hepatócitos de rato após infecção por S. flexneri na presença e na ausência de hipóxia. Para esta finalidade foram utilizados hepatócitos de rato cultivados pela técnica de cultura primária. Vários parâmetros foram analisados, tais como: taxa de invasão celular pela bactéria, quantificação da produção e liberação de DHL, produção de TNF-, taxa de morte celular por apoptose e a expressão do fator de transcrição HIF-1a. Os resultados mostraram que a metodologia empregada para a obtenção do microambiente hipóxico foi satisfatória, com redução de 70% da pO2 inicial (atingindo 43.2 mmHg in vitro ou 6.5% O2). A invasão de hepatócitos de rato por S. flexneri foi menor nas células previamente expostas à hipóxia quando comparada com a invasão das células cultivadas em normóxia. A viabilidade dos hepatócitos não apresentou diferenças significativas entre os grupos experimentais, variando entre 74 e 86%. A liberação de TNF- nas situações de normóxia e hipóxia foi similar, embora as células infectadas em normóxia tenham aumentado a liberação desta citocina. Na condição de hipóxia + infecção a liberação de TNF- foi menor do que na condição de normóxia + infecção, porém ambos os grupos produziram aumento significativo da citocina em relação aos controles normóxicos e hipóxicos. Este resultado sugere que a presença da bactéria no interior das células aumenta significativamente a liberação de TNF-pelos hepatócitos. A produção de DHL também foi maior de forma significativa no grupo hipóxico em relação ao grupo normóxico, porém não apresentou alteração nos grupos infectados por S. flexneri após uma hora. As taxas de apoptose aumentaram nos grupos hipóxia e nos grupos infectados com S. flexneri de maneira similar, variando entre 24 e 31%, quando comparados aos grupos controle em normóxia. A expressão do fator de transcrição HIF ocorreu nos grupos: hipóxia, normóxia + infecção e hipóxia + infecção, evidenciando que a infecção por S. flexneri induz a expressão deste fator. Em seu conjunto, nossos resultados buscam contribuir para o maior conhecimento da interação entre S. flexneri e hepatócitos em condição de hipóxia e normóxia. Tal conhecimento poderá ser útil na construção de futuras estratégias para auxiliar no combate a esta importante bactéria invasiva, principalmente nos casos de septicemia / This study evaluated the invasiveness of rat hepatocytes by Shigella flexneri (S. flexneri) in normoxia and hypoxia conditions. The study of hypoxia microenvironment is of great importance, since hypoxia is present in many liver diseases and increases bacterial translocation when present in intestinal lumen. Invasive bacteria such as S. flexneri can disrupt the intestinal barrier and reach the liver through portal circulation. The effect of bacterial invasion in liver cells is poorly understood. In this study we investigated the morphological and functional changes of rat hepatocytes after infection with S. flexneri in the presence and absence of hypoxia. For this purpose we used primary cultures of rat hepatocytes. Several parameters were analyzed, such as: bacterial invasion cell rate, quantification of LDH production and release, TNF-a production, cell death rate by apoptosis and expression of the transcription factor HIF-1a. The results showed that the methodology used to obtain the hypoxic microenvironment was satisfactory, with 70% reduction of initial pO2 (to 43.2 mmHg in vitro or 6.5% O2). The invasion of rat hepatocytes by S. flexneri was lower in cells previously exposed to hypoxia compared with the invasion of cells grown in normoxia. The viability of hepatocytes showed no significant differences between experimental groups, ranging between 74% and 86%. The release of TNF-a in situations of normoxia and hypoxia was similar, although the infected cells in normoxia have increased the release levels of this cytokine. In hypoxia + infection condition the release of TNF-a was lower than normoxia + infection condition, but both groups produced a significant increase in cytokine release when compared to normoxic and hypoxic controls. This result suggests that the presence of bacteria inside the cells significantly increases the release of TNF-a by hepatocytes. DHL production was also significantly greater in the hypoxic group compared to the normoxic group, but had no change in the groups infected with S. flexneri after an hour. The apoptosis rates increased in hypoxia and infected groups in a similar way, varying between 24% and 31% when compared with control group in normoxia. The expression of HIF- 1a transcription factor occurred in hypoxia, normoxia + infection and hypoxia + infection groups, indicating that infection with S. flexneri induces the expression of this factor. Overall, our results sought to contribute to a greater understanding of the interaction between S. flexneri and hepatocytes under hypoxia and normoxia conditions. Such knowledge may be useful in building future strategies to assist in combating these major invasive bacteria