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DPSPDNT - Dissertações de mestrado

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Browsing DPSPDNT - Dissertações de mestrado by advisor "Costa, Luciana Maria Gonçalves da"

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  • Expression of iron metabolism: related genes in a portuguese population of Alzheimer’s disease patients
    Publication . Cavaco Guerreiro, Cláudia; Rebelo, Maria Teresa; Costa, Luciana Maria Gonçalves da
    [ENG] Alzheimer’s disease (AD) is the most common neurodegenerative disorder and one of the most frequent dementia worldwide. The main neuropathological hallmarks of AD are extracellular senile “plaques” (SP) and intracellular neurofibrillary “tangles” (NFT), which are associated with the loss of cortical neurons. This disease is also characterized by elevated brain iron (Fe) levels and accumulation of copper and zinc in cerebral Aβ amyloid deposits, like SP. Thus, a dysfunctional homeostasis of transition metals seems to play pivotal role in pathogenesis of this disease. In this work we intended to further understand the putative role of Fe metabolism in AD pathophysiology. In order to achieve this goal, the expression of specific target Fe metabolism-related genes was measured in peripheral blood mononuclear cells (PBMCs) from AD patients and controls by real time quantitative PCR techniques while Fe status in the periphery was evaluated using biochemical standard techniques. The results obtained showed significant decrease in the expression of acotinase 1 (ACO1; P=0.011); ferroportin (SLC40A1; P<0.001); ceruloplasmin (CP; P<0.001); amyloid peptide precursor (APP; P=0.007); transferrin receptor 1 (TFR1; P<0.001) and transferrin receptor 2 (TFR2; P<0.001) genes, in contrast with an increase in the expression of light chain of ferritin (FT-L; P=0.038) in AD patients compared with healthy volunteers. Also, although we did not find significant differences in Fe metabolism parameters measured in serum, a tendency for the decrease in serum Fe and ferritin (Ft) concentrations was observed in AD patients. These observations reinforce previous reports showing a low Fe status in periphery of AD patients. According to these findings one can suggest impairment in cellular Fe efflux in AD individuals, which may lead to cellular Fe overload and oxidative stress, a typical feature of this disease. Nevertheless, further research into the characterization of regulation of Fe metabolism at both phenotypic and genetic levels in AD may be important to provide a low invasive and earlier form for its diagnosis. Resumo: A doença de Alzheimer (AD) é a doença neurodegenerativa mais comum e representa um dos tipos de demência mais frequentes a nível mundial. As suas principais características neuropatológicas são a formação de “placas senis” e de “emaranhados neurofibrilares”, associados à perda de neurónios corticais. Esta doença é também caracterizada pela presença de elevados níveis de ferro (Fe) no cérebro e pela acumulação de cobre e de zinco nos agregados de β-amilóide, que constituem as “placas senis”. Desta forma, uma disfunção na homeostase dos metais de transição parece desempenhar um papel crucial na patogénese da AD. Neste trabalho pretendeu-se compreender o papel do metabolismo do Fe na patofisiologia da AD. A fim de alcançar este objectivo mediu-se expressão de genes-alvo específicos relacionados com o metabolismo do Fe, em células mononucleares de sangue periférico em doentes e controlos, através de técnicas de PCR quantitativo em tempo real. O status de Fe a nível periférico foi avaliado através da utilização de técnicas bioquímicas comuns. Os resultados obtidos mostraram uma diminuição significativa na expressão dos genes acotinase 1 (ACO1; P=0.011); SLC40A1 (P<0.001); ceruloplasmina (CP; P<0.001) proteína percursora da amilóide (APP; P=0.007); receptor da transferrina 1 (RTF1; P<0.001) e do receptor da transferrina 2 (RTF2; P<0.001), enquanto se verificou um aumento da expressão da cadeia leve da FT (FT-L; P=0.038) nos doentes em comparação com os indivíduos saudáveis. Por seu turno, os resultados bioquímicos mostraram, apesar de não terem sido encontradas diferenças significativas entre os doentes e os controlos, uma tendência para uma diminuição da concentração sérica de Fe e ferritina (Ft) e nos doentes. Estas observações estão de acordo com resultados anteriores, que mostraram a existência de uma baixa concentração de Fe periférico em doentes com AD. Os resultados obtidos neste estudo apontam para uma disfunção celular no efluxo de Fe em doentes com AD, o que pode levar a uma sobrecarga de Fe celular e ao stress oxidativo normalmente associado a esta doença. Estudos adicionais sobre a caracterização do metabolismo do Fe periférico tanto a nível fenotípico como genético poderão ser essenciais para o estabelecimento de um diagnóstico mais precoce e menos invasivo para esta doença.
    2013-12-02Master thesis Restricted access Show more
  • The role of peripheral blood mononuclear cells in atherogenesis
    Publication . Simões Martins Bispo, Cláudia; Crespo, Ana Maria Viegas; Costa, Luciana Maria Gonçalves da
    Atherosclerosis (ATH) is recognized as a chronic inflammatory condition and it is the leading cause of cardiovascular disease. Atherogenesis is characterized by the infiltration of low density lipoprotein (LDL) through the endothelial layer, and migration of activated peripheral blood lymphocytes (PBL) and monocytes (PBMN) that contribute to a pro-inflammatory state in specific locations. However, the functional interaction between immunity and LDL metabolism is still not fully understood. One hypothesis for the etiopathogeny of ATH may be associated with an ongoing inflammatory process caused by a pro-oxidant/anti-oxidant imbalance induced by metals such as iron (Fe) or copper (Cu). Interestingly, ceruloplasmin (Cp) is a multicopper oxidase with a relevant role in Fe metabolism and oxidation of LDL, but also an acute-phase protein involved in the inflammatory process. Herein, we intended to study by flow cytometry the effect of putative pro-atherogenic immune stimuli on the expression of Cp at the surface of human peripheral blood mononuclear cells (PBMC), and search for a putative association with LDL oxidation. Additionally, a population of Familial Hypercholesterolemia (FH) patients was used as a clinical model of ATH to clarify the physiologic interplay between inflammation, Fe/Cu and lipid metabolism at systemic level in this disease. The obtained results showed that higher cell surface expression of Cp was consistently observed in PBMN compared to PBL, in activated vs non-activated cells and in non-T cells vs T cells. Also, PBMC surface expression of Cp was differently modulated by several tested treatments. In particular, various modulators caused opposite effects on Cp expression of PBMN compared to PBL, suggesting a specific cell-type regulation for this protein. Specifically, it was observed that different sources of Fe might activate specific regulation mechanisms of Cp. Until now, due to technical limitations it was not possible to demonstrate an association between PBMC surface Cp expression and oxidation of LDL, but this issue should be addressed in future experiments. Of notice, IL-1β which was found to significantly increase PBMN surface Cp expression in vitro, was increased in serum from FH patients and positively correlated with total cholesterol and ApoB. However, the fact that no correlation was found between IL-1β and serum Cp (sCp)/oxidated LDL suggest that at systemic level, IL-1β may not be a contributing factor for oxidation of LDL by sCp. However, the role of PBMC surface Cp expression on LDL oxidation, namely in specific inflammatory states, remains to be established. In summary, the results of this study demonstrate that specific pro-atherogenic conditions are involved in the modulation of Cp expression at surface of PBMC and thus, suggest a possible a role of Cp in ATH.
    2011-12-13Master thesis Open access Show more