Estudo metabolómico das respostas celulares a nanopartículas de seda

Mestrado em Bioquímica - Bioquímica ClínicaThe use of metabolomics to reveal response markers of efficacy or toxicity, as well as to provide biochemical insight into mechanisms of action has gained increasing interest in the research community. In this work, the effects of silk nanoparticles on the metabolism of macrophages, which are an important cell type in regard to NP uptake, was addressed through Nuclear Magnetic Resonance (NMR) spectroscopy metabolomics. Firstly, 1D and 2D NMR spectroscopy was applied to determine the metabolic composition of murine macrophages (RAW 264.7 cell line), through the analysis of both aqueous and lipid extracts. Almost forty metabolites were identified, establishing a database of metabolites of murine macrophages. Afterwards, murine macrophages were exposed to two concentrations of silk nanoparticles (10 and 500 μg/mL), selected based on cytotoxicity data collected previously to this work, and the impact on their metabolic composition was assessed. Multivariate analysis was applied to the 1D 1H NMR spectra in order to search the compositional changes in macrophages during silk nanoparticles’ (SNPs) exposure. It was found that the low concentration SNPs induced few changes in the cells metabolome compared to the high concentration SNPs, which resulted in biochemical changes related to energy metabolism and TCA cycle, disturbance of amino acids metabolism and cell membrane modification. Some variations were common to all exposure periods, such as the increase in branched chain amino acids, lactate and tyrosine and the decrease in glutamine, taurine, myo-inositol and ATP/ADP, whereas other variations seemed to be more time-specific. The time-dependent fluctuations were also visible in lipids, where cholesterol, cholesterol esters and sphingomyelin were found to be relatively higher in SNP-exposed samples, while unsaturated fatty acids, plasmalogen and phosphatidylcholine were higher in controls. These results have shown that the use of NMR metabolomics to evaluate a nanomedicine performance may be a powerful tool to improve our understanding of cell-nanomaterial interactions and of the mechanisms underlying observed toxicities.A aplicação da metabolómica com o intuito de revelar biomarcadores de eficácia ou toxicidade, assim como de fornecer uma compreensão bioquímica de mecanismos de ação, tem ganho maior interesse na comunidade científica. Neste trabalho os efeitos das nanopartículas de seda no metabolismo de macrófagos, que são um tipo celular importante no que diz respeito à incorporação de nanopartículas, foram investigados por metabolómica de espectroscopia de Ressonância Magnética Nuclear (RMN). Inicialmente, espectroscopia de RMN 1D e 2D foi aplicada para determinar a composição metabólica de macrófagos de rato (linha celular RAW 264.7), através da análise de extratos aquosos e lipídicos. Cerca de quarenta metabolitos foram identificados, estabelecendo uma base de dados dos metabolitos de macrófagos de rato. De seguida, esses macrófagos foram expostos a duas concentrações de nanopartículas de seda (10 e 500 μg/mL), selecionadas com base nos dados citotoxicológicos recolhidos previamente a este trabalho, e o seu impacto no metabolismo foi averiguado usando a mesma metodologia. Análise multivariada foi aplicada aos espectros de 1H RMN 1D de forma a investigar as alterações na composição dos macrófagos durante a exposição às nanopartículas de seda (SNPs). A concentração baixa de SNPs induziu poucas alterações no metaboloma celular comparativamente à concentração alta de SNPs, que resultou em alterações bioquímicas no metabolismo energético e ciclo do ácido cítrico, distúrbios no metabolismo de aminoácidos e modificações na membrana celular. Algumas variações foram comuns a todos os períodos de exposição, tais como o aumento dos aminoácidos de cadeia ramificada, lactato e tirosina, e a diminuição de glutamina, taurina, myo-inositol e ATP/ADP, enquanto que outras se revelaram ser mais específicas em relação ao tempo de exposição. As flutuações dependentes do tempo foram também visíveis nos lípidos, onde o colesterol, ésteres de colesterol e esfingomielina se encontraram mais elevados nas amostras expostas à concentração elevada de SNPs, enquanto que os ácidos gordos insaturados, plasmalogénio e fosfatidilcolina estavam mais elevados nos controlos. Estes resultados demonstraram que a aplicação de metabolómica de RMN para avaliar o desempenho de nanofármacos pode ser uma ferramenta importante para melhorar a nossa compreensão das interações célula-nanomaterial e os mecanismos subjacentes à toxicidade observada

Metabolic reprogramming of macrophages exposed to silk, poly(lactic-co-glycolic acid) and silica nanoparticles

Monitoring macrophage metabolism in response to nanoparticle exposure provides new insights into biological outcomes, such as inflammation or toxicity, and supports the design of tailored nanomedicines. We describe the metabolic signature of macrophages exposed to nanoparticles ranging in diameter from 100 to 125 nm and made from silk, poly(lactic-co-glycolic acid) or silica. Nanoparticles of this size and type are currently at various stages of pre-clinical and clinical development for drug delivery applications. We used 1H NMR analysis of cell extracts and culture media to quantify the changes in the intracellular and extracellular metabolomes of macrophages in response to nanoparticle exposure. Increased glycolytic activity, an altered tricarboxylic acid cycle and reduced ATP generation were consistent with a pro-inflammatory phenotype. Furthermore, amino acids possibly arising from autophagy, the creatine kinase/phosphocreatine system and a few osmolytes and antioxidants emerged as important players in the metabolic reprogramming of macrophages exposed to nanoparticles. This metabolic signature was a common response to all nanoparticles tested; however, the direction and magnitude of some variations were clearly nanoparticle specific, indicating material-induced biological specificity. Overall, metabolic reprogramming of macrophages can be achieved with nanoparticle treatments, modulated through the choice of the material, and monitored using 1H NMR metabolomics

Application of nuclear magnetic resonance spectroscopy for the detection of metabolic changes in non-alcoholic fatty liver disease

The increasing rates of NAFLD worldwide are a major concern to healthcare providers leading to an arising need to study liver metabolism in health and disease. Metabolic analysis of specific biochemical processes by NMR spectroscopy allows detailed study of carbohydrate and lipid metabolism dysregulation in liver disease. In order to identify the hepatic metabolic fingerprint at different stages of NAFLD I used in vitro, murine in vivo and human ex vivo models. Optimisation of NMR metabolic profiling and tracer-based studies using 13C-labelled precursors were performed using cell lines and primary cells. Furthermore, metabolic alterations that occur during disease progression were compared between an in vitro model of steatosis and human ex vivo liver samples. Flow cytometry, immunohistochemistry, qPCR and biochemical analysis were also used to confirm the extent of the liver injury during NAFLD progression. Fructose supplementation led to accelerated obesity, hepatic steatosis and insulin resistance, as well as increased inflammation in my murine model. The use of 1D NMR-based metabolomics and 2D HSQC spectra to follow [U-13C] fructose confirmed selective enhancement of the glycolytic pathway and TCA cycle intermediates together with nucleotide production. Moreover, increase in the production of glycerol intermediates was observed, which drives de novo lipogenesis. Lastly, the inhibition of ketohexokinase activity in both the animal model and the ex vivo human perfusion system highlighted its potential as a therapeutic approach in NAFLD. Hence, these findings demonstrate the relevance of using NMR metabolomics and tracer-based approaches to study metabolic changes in the context of human disease and provided detailed mechanistic information that can lead to the identification of novel diagnostic, prognostic and therapeutic tools

Metabolic responses of the isopod Porcellionides pruinosus to nickel exposure assessed by H-1 NMR metabolomics

This work aimed at characterizing the metabolome of the isopod Porcellionides pruinosus and at assessing its variations over 14 days under laboratory culture conditions and upon exposure to the contaminant metal Nickel (Ni). The spectral profiles obtained by H-1 NMR spectroscopy were thoroughly assigned and subjected to multivariate analysis in order to highlight consistent changes. Over 50 metabolites could be identified, providing considerable new knowledge on the metabolome of these model organisms. Several metabolites changed non-linearly with Ni dose and exposure time, showing distinct variation patterns for initial (4 days) and later time points (7 and 14 days). In particular, at day 4, several amino acids were increased and sugars were decreased (compared to controls), whereas these variations were inverted for longer exposure, possibly reflecting earlier and more intensive moulting. Other variations, namely in betaines and choline-containing compounds, were suggested to relate with osmoregulation and detoxification mechanisms. Ni also had a marked effect on several nucleotides (increased upon exposure) and a moderate impact on lipids (decreased upon exposure). Overall, this study has provided new information on the Ni-induced metabolic adaptations of the P. pruinosus isopod, paving the way for improved mechanistic understanding of how these model organisms handle soil contamination. Significance: This study provided, for the first time to our knowledge, a detailed picture of the NMR-detectable metabolome of terrestrial isopods and of its fluctuations in time and upon exposure to the contaminant metal Nickel. Several time- and dose-dependent changes were highlighted, providing mechanistic insight into how these important model organisms handle Ni contamination. (C) 2015 Elsevier B.V. All rights reserved

Ketohexokinase inhibition improves NASH by reducing fructose-induced steatosis and fibrogenesis

Background & Aims: Increasing evidence highlights dietary fructose as a major driver of non-alcoholic fatty liver disease (NAFLD) pathogenesis, the majority of which is cleared on first pass through the hepatic circulation by enzymatic phosphorylation to fructose-1-phosphate via the ketohexokinase (KHK) enzyme. Without a current approved therapy, disease management emphasises lifestyle interventions, but few patients adhere to such strategies. New targeted therapies are urgently required. Methods: We have used a unique combination of human liver specimens, a murine dietary model of NAFLD and human multicellular co-culture systems to understand the hepatocellular consequences of fructose administration. We have also performed a detailed nuclear magnetic resonance-based metabolic tracing of the fate of isotopically labelled fructose upon administration to the human liver. Results: Expression of KHK isoforms is found in multiple human hepatic cell types, although hepatocyte expression predominates. KHK knockout mice show a reduction in serum transaminase, reduced steatosis and altered fibrogenic response on an Amylin diet. Human co-cultures exposed to fructose exhibit steatosis and activation of lipogenic and fibrogenic gene expression, which were reduced by pharmacological inhibition of KHK activity. Analysis of human livers exposed to 13C-labelled fructose confirmed that steatosis, and associated effects, resulted from the accumulation of lipogenic precursors (such as glycerol) and enhanced glycolytic activity. All of these were dose-dependently reduced by administration of a KHK inhibitor. Conclusions: We have provided preclinical evidence using human livers to support the use of KHK inhibition to improve steatosis, fibrosis, and inflammation in the context of NAFLD. Lay summary: We have used a mouse model, human cells, and liver tissue to test how exposure to fructose can cause the liver to store excess fat and become damaged and scarred. We have then inhibited a key enzyme within the liver that is responsible for fructose metabolism. Our findings show that inhibition of fructose metabolism reduces liver injury and fibrosis in mouse and human livers and thus this may represent a potential route for treating patients with fatty liver disease in the future