An investigation into the effects of metabolic disturbance on monocyte inflammatory response and regulation

The presence of chronic inflammation is associated with increased nutrient availability during obesity or type 2 diabetes which contributes to the development of complications such as atherosclerosis, stroke and myocardial infarction. The link between increased nutrient availability and inflammatory response remains poorly understood. The functioning of monocytes, the primary instigators of the inflammatory response was assessed in response to obesity and increased glucose availability. Monocyte microRNA expression was assessed in obese individuals prior to and up to one year after bariatric surgery. A number of microRNAs were identified to be dysregulated in obesity, some of which have previously been linked to the regulation of monocyte inflammatory responses including the microRNAs 146a-5p and 424-5p. Weight loss in response to bariatric surgery lead to the reversal of microRNA changes towards control values. In vitro treatments of THP-1 monocytes with high concentrations of D-glucose resulted in decreased intracellular NAD+:NADH ratio, decreased SIRT1 deacetylase activity and increased P65 acetylation. However the increased osmotic concentration inhibited LPS induced inflammatory response and TNFα mRNA expression. In vitro treatment of primary human monocytes with increased concentrations of D-glucose resulted in increased secretion of a number of inflammatory cytokines and increased expression of TNFα mRNA. Treatment also resulted in decreased intracellular NAD+:NADH ratio and increased binding of acetylated P65 to the TNFα promoter region. In vitro treatments of primary monocytes also replicated the altered expression of the microRNAs 146a-5p and miR-424-5p, as seen in obese individuals. In conclusion a number of changes in monocyte function were observed in response to obesity and treatment with high concentrations of D-glucose. These may lead to the dysregulation of inflammatory responses contributing to the development of co-morbidities.

Parasite-host interaction of the protoplast isolates of Entomophthora egressa with the eastern hemlock looper and the eastern spruce budworm

Hemocytes of the insects Lambdina fiscellaria fiscellaria and Choristoneura fumiferana did not adhere to the protoplasts of ~he fungus EntomoEhthora egressa. Hemocyte reaction for both insect species to test-particles was not suppressed by the protoplasts. The spherule cells of _-L. fiscellaria fiscellaria adhered to the spherical hyphal bodies and hyphae of ~· ~gressa. The granular cells of -c. fumiferana adhered to the hyphae of ~· egress~. Protoplasts exposed to papain were attacked by the granular ·cells of -c. fumiferana. Spent growth medium of both protoplast isolates produced paralysis when injected into -c. fumiferana larvae. Evidence suggests that heat-stable proteins may be involved. Protoplast isolates showed differences in the growth rates and regeneration sequences using coagulated egg yolk medium, a highly modified version of Grace's insect tissue . culture medium (MGM) and modifications of MGM and in the presence of C0₂. The isolates also differed in the changes that they induced in MGM composition during protoplast growth and in the rates of glucose utilization and protein secretion. The serum of c. fumiferana larvae contained protein(s) which we believe adhere to the cell membranes of the protoplasts of E. egressa. Evidence is presented for hemocyteplasn~ interaction in the presence of protoplasts. Components in the larval serum were found to influence protoplast growth patterns. The possibility of antiprotoplast serum activity is presented. Melanin, toxic levels of ninhydrinpositive compounds and antiprotoplast proteins may have been involved in this activity. The granular cells of -L. fiscellaria fiscellaria and Q• fumiferana adhered to the hyphae of ,Rhizopus ~i$rican~. Spores of Absidia repens and the bacteria Escherichia coli and Bacillus cereus adhered to the granular cells of both species of· insects. The granular cells and plasmatocytes of -c. fumiferana were capable of phagocytosing -B. cereus. Adhesion of .A... . repens spores to c. fumiferana granular cells ~ . - was stimulated by N-acetylglucosamine and glucosamine, moderately reduced by D-fucose, D-arabinose, D-mannose, D-galatose and sucrose and mildly reduced by D-glucose, D-fructose and trehalose. There was no evidence of humoral opsonins in larval hemolymph favoring test-particle-hemocyte interaction. Granular cells of c. fumiferana exposed to papain had reduced affinities for A. repens spores.

Quitooligosacáridos bifuncionales: relación entre características químico-físicas y propiedades biológicas

As the degraded products of chitosan, chitooligosaccharides (COS) have recently been produced by several methods, such as enzymatic an acidic hydrolysis. Chitosans are a family of biocompatible and biodegradable biopolymers obtained by N-deacetylation of chitin, the most abundant natural polymer after cellulose, consisting of two monomeric units, N-acetyl-2- amino-2-deoxi-D-glucose (A units) and 2-amino-2-deoxi-D-glucose (D units) linked by β (1→4) links. The degraded products COS, have a smaller molecular weight and therefore have better solubility and lower viscosity under physiological conditions because of shorter chain lengths and free amino groups in D-glucosamine units. The study of COS has been increasing not only because they come from a natural source, but also because of their biological compatibility and effectiveness. There are numerous reports on the biological activities of COS and their potential applications in food industry, pharmacy, agricultural or biomedicine. Nevertheless, in these studies it is difficult to find well defined COS in terms of physicochemical parametres, because these samples are usually poorly characterized. This makes it difficult to compare the results and to understand their mecanism of action. Degradation of the O-glycosidic linkages of chitosan by different methods, results in COS with different numbers and sequences of A and D units as well as different degrees of polymerisation (DP). Over the past few years, several technological approaches have been taken in preparing COS, including acid hydrolysis or enzymatic methods, among others. Therefore, in order to obtain COS with different physicochemical properties, different preparation methods of COS have been developed in this work. Then, the study of the relationship between physicochemical properties of these COS and their biological activities such as natural antioxidants, antibacterial agents, mucoadhesive and anti-inflammatory effects have been studied...

Ruthenibacterium lactatiformans gen. nov., sp.nov., an anaerobic, lactate-producing member of the family Ruminococcaceae isolated from human faeces

Two novel strains of Gram-stain-negative, rod-shaped, obligately anaerobic, non-spore-forming, non-motile bacteria were isolated from the faeces of healthy human subjects. The strains, designated as 585-1T and 668, were characterized by mesophilic fermentative metabolism, production of d-lactic acid, succinic acid and acetic acid as end products of d-glucose fermentation, prevalence of C18 : 1 ω9, C18 : 1 ω9 aldehyde, C16 : 0 and C16 : 1 ω7c fatty acids, presence of glycine, glutamic acid, lysine, alanine and aspartic acid in the petidoglycan peptide moiety and lack of respiratory quinones. Whole genome sequencing revealed the DNA G+C content was 56.4–56.6 mol%. The complete 16S rRNA gene sequences of the two strains shared 91.7/91.6 % similarity with Anaerofilum pentosovorans FaeT, 91.3/91.2 % with Gemmiger formicilis ATCC 27749T and 88.9/88.8 % with Faecalibacterium prausnitzii ATCC 27768T. On the basis of chemotaxonomic and genomic properties it was concluded that the strains represent a novel species in a new genus within the family Ruminococcaceae , for which the name Ruthenibacterium lactatiformans gen. nov., sp. nov. is proposed. The type strain of Ruthenibacterium lactatiformans is 585-1T (=DSM 100348T=VKM B-2901T).

Oncological patient anxiety in imaging studies: the PET/CT example

The purpose of this study was to investigate the subjective perception of anxiety pre- and post-procedure, and explore the relationship between demographic, clinical variables and cancer patients' anxiety during a positron emission tomography/computed tomography (PET/CT) scan. Two hundred and thirty-two oncological out patients, with clinical indication for performing an (18)F-2-fluoro-2-deoxy-D-glucose ((18)F-FDG) PET/CT scan and attending a nuclear medicine (NM) department, participated in the study. Patients' anxiety and subjective experience of PET/CT were examined using two self-report questionnaires. The pre-procedure questionnaire focused on demographic information, level of knowledge regarding the scan and subjective perception of anxiety before the procedure. The post-procedure questionnaire included the subjective perception anxiety after the procedure, information adequacy and satisfaction with the NM department. The self-reported data indicate that patients were anxious during PET/CT. Furthermore, our data revealed a significant difference between the anxiety pre-procedure and post-procedure (z = -3909, p < 0.05), in which the anxiety pre-procedure has significantly higher values. No significant correlation was found between anxiety and age of the patients, education levels, adequacy of information or satisfaction with the NM Department. Perception of anxiety post-procedure differs between gender (U = 5641, p = 0.033). In conclusion, PET/CT generated anxiety levels in oncological patients, especially before the procedure. Although patients seemed to be satisfied with information delivered by staff and with the NM Department, attention has to be focused on effective interventions strategies that help patients to reduce anxiety.

Wysokociśnieniowe przemiany strukturalne kryształów węglowodanów

Wydział Chemii

Solubility and solvation of monosaccharides in ionic liquids

Herein, solubility experimental data for six monosaccharides, viz. D-(+)-glucose, D-(+)-mannose, D-(-)-fructose, D-(+)-galactose, D-(+)-xylose and L-(+)-arabinose, in four ionic liquids (ILs), at temperatures ranging from 288.2 to 348.2 K, were obtained aimed at gathering a better understanding of their solvation ability and molecular-level mechanisms which rule the dissolution process. To ascertain the chemical features that enhance the solubility of monosaccharides, ILs composed of dialkylimidazolium or tetra-alkylphosphonium cations combined with the dicyanamide, dimethylphosphate or chloride anions were investigated. It was found that the ranking of the solubility of monosaccharides depends on the IL; yet, D-(+)-xylose is always the most soluble while D-(-)-fructose is the least soluble monosaccharide. The results obtained show that both the IL cation and the anion play a major role in the solubility of monosaccharides. Finally, from the determination of the respective thermodynamic properties of solution, it was found that enthalpic contributions are dominant in the solubilization process. However, the observed differences in the solubilities of monosaccharides in 1-butyl-3-methylimidazolium dicyanamide are ruled by a change in the entropy of solution.

Síntese enzimática de ésteres de açúcar: surfactantes e polímeros como novos materiais ambientalmente seguros

Sugar esters are substances which possess surfactant, antifungical and bactericidal actions and can be obtained through two renewable sources of raw materials: sugars and vegetable oils. Their excellent biodegradability, allied to lhe fact that they are non toxic, insipid, inodorous, biocompatible, no-ionic, digestible and because they can resist to adverse conditions of temperature, pH and salinity, explain lhe crescent use of these substances in several sections of lhe industry. The objective of this thesis was to synthesize and characterize surfactants and polymers containing sugar branched in their structures, through enzymatic transesterification of vinyl esters and sugars, using alkaline protease from Bacillus subtilis as catalyst, in organic medium (DMF).Three types of sugars were used: L-arabinose, D-glucose and sucrose and two types of vinyl esters: vinyl laurate and vinyl adipate. Aiming to reach high conversions from substrates to products for a possible future large scale industrial production, a serie of variables was optimized, through Design of Experiments (DOE), using Response Surface Methodology (RSM).The investigated variables were: (1) enzyme concentration; (2) molar reason of substrates; (3) water/solvent rale; (4) temperature and (5) time. We obtained six distinct sugar esters: 5-0-lauroyl L-arabinose, 6-0-lauroyl D-glucose, 1'-O-lauroyl sucrose, 5-0-vinyladipoyl L-arabinose, 6-0-vinyladipoyl D-glucose and 1 '-O-vinyladipoyl sucrose, being lhe last three polymerizable. The progress of lhe reaction was monitored by HPLC analysis, through lhe decrease of sugar concentration in comparison to lhe blank. Qualitative analysis by TLC confirmed lhe formation of lhe products. In lhe purification step, two methodologies were adopted: (1) chromatographic column and (2) extraction with hot acetone. The acylation position and lhe chemical structure were determined by 13C-RMN. The polymerization of lhe three vinyl sugar esters was possible, through chemical catalysis, using H2O2 and K2S2O8 as initiators, at 60°C, for 24 hours. IR spectra of lhe monomers and respective polymers were compared revealing lhe disappearance of lhe vinyl group in lhe polymer spectra. The molar weights of lhe polymers were determined by GPC and presented lhe following results: poly (5-0-vinyladipoyl L-arabinose): Mw = 7.2 X 104; PD = 2.48; poly (6-0-vinyladipoyl D-glucose): Mw = 2.7 X 103; PD = 1.75 and poly (1'-O-vinyladipoyl sucrose): Mw = 4.2 X 104; PD = 6.57. The six sugar esters were submitted to superficial tension tests for determination of the critical micelle concentrations (CMC), which varied from 122 to 167 ppm. Finally, a study of applicability of these sugar esters, as lubricants for completion fluids of petroleum wells was' accomplished through comparative analysis of lhe efficiency of these sugar esters, in relation to three commercial lubricants. The products synthesized in this thesis presented equivalent or superior action to lhe tested commercial products

Cáncer gástrico en pacientes de Méderi – Hospital Universitario Mayor entre los años 2011 - 2014

Introducción: El cáncer gástrico es uno de los más frecuentes a nivel mundial y Colombia se sitúa entre los países de mayor incidencia en este tipo de patología. Objetivo: Describir las características epidemiológicas, clínicas, el tratamiento administrado y los desenlaces inmediatos de los pacientes con diagnóstico de cáncer gástrico atendidos en el Hospital Universitario Mayor de Bogotá entre los años 2011 y 2014. Metodología: Se realizó un estudio observacional descriptivo con diagnóstico de cáncer gástrico. Se realizaron análisis univariados por medio de proporciones para las variables cualitativas y medidas de tendencia central para las variables cuantitativas según la distribución. Resultados: Un total de 189 pacientes fueron analizados. El dolor fue el síntoma más frecuente en los pacientes (30.7%) y el principal signo encontrado fue una masa palpable en abdomen (9,5%). Los pacientes fueron sometidos a diferentes abordajes terapéuticos, la mayoría recibieron manejo paliativo no quirúrgico (52.9%) y la opción quirúrgica más usada en los pacientes fue la gastrectomía total (20.6%), y la subtotal (16,4) seguidas de quimioterapia y/o radiación perioperatoria. Los pacientes que sobrevivieron a los 2 años fueron 7,4% del total. Conclusiones: El registro de los pacientes con cáncer gástrico es bueno en el Méderi-Hospital Universitario Mayor es bueno y permite caracterizar los pacientes, la presentación de la patología y los resultados del tratamiento que concuerdan con los presentados en contextos similares en la literatura.

Open-cell Metallic Foams for the Electrochemical Conversion of Biomass-derived Compounds

The electrochemical conversion is a sustainable way for the production of added-value products, operating in mild conditions, using in-situ generated hydrogen/oxygen by water and avoiding the use of high H2/O2 pressures. The aim of this work is to investigate the electrocatalytic conversion of 5-hydroxymetilfurfural (HMF) and D-glucose, in alkaline media, using metallic open-cell foams based-catalysts. The electrochemical hydrogenation of HMF to 2,5-bis(hydroxymethyl)furan (BHMF) was performed using nanostructured Ag, deposited by galvanic displacement (GD) or electrodeposition (ED), on Cu foam, obtaining AgCu bimetallic nanoparticles (ED) or dendrites (GD) which enhanced electroactive surface area, charge and mass transfer, than bare foams. In diluted 0.02M HMF solutions, Ag/Cu samples selectively produce BHMF; the large surface area enhanced the productivity, compared to their 2D counterparts. Furthermore, at more concentrated solutions (0.05 – 0.10M) a gradually decrease of selectivity is observed. The performances of the electrodes is stable during the catalytic tests but a Cu-enrichment of particles occurred. The performances of Ni foam-based catalysts, obtained by calcination of Ni foam or by electrodeposition of Ni-hydroxide/Ni and Ni particle/Ni, were firstly investigated for the selective electrochemical oxidation of D-glucose toward gluconic acid (GO) and glucaric acid (GA). Then, the calcined catalyst was chosen to study the influence of the reaction conditions on the reaction mechanism. The GO and GA selectivities increase with the charge passed, while the formation of by-products from C-C cleavage/retro-aldol process is maximum at low charge. The fructose obtained from glucose isomerization favours the formation of by-products. The best glucose/NaOH ratio is between 0.5 and 0.1: higher values suppress the OER, while lower values favour the formation of low molecular weight products. The increases of the potential enhance the GO selectivity, nevertheless higher GA selectivity is observed at 0.6 – 0.7V vs SCE, confirmed by catalytic test performed in gluconate (30-35% GA selectivity).

Ossidazione elettrocatalitica di glucosio su schiume di nickel per la produzione selettiva di acido gluconico e acido glucarico

The selective electro-oxidation of D-glucose represents a promising way for the synthesis of many platform molecules, currently produced from non-renewable fossil fuels. Electrocatalysis is gaining considerable interest as an alternative to the thermochemical process, since it allows the process to be sustainable by operating at room temperature and pressure as well as using green solvents and electricity produced from renewable sources. In this work, the activity of three electrocatalysts, based on open cell Ni foams, towards the electrochemical oxidation of glucose to gluconic acid and glucaric acid was initially compared: a Ni bare foam, and Ni foams calcined at 500 °C for one hour and electrodeposited with Ni NP nanoparticles. The calcined foam turned out to be the most efficient. Then, the performance of this Ni calcined electrocatalyst was studied varying the reaction conditions, such as the potential applied (from 0,5V to 1,0V vs SCE), D-glucose concentration (0,01M, 0,05M and 0,10M) and NaOH concentration (0,10M and 1,0M). The activity of the electrocatalysts was evaluated in terms of glucose conversion, gluconic and gluconic acid selectivity and faradic efficiency. The best results were obtained over a Ni calcined foam with a 0,05M solution of D-glucose and 0,10M of NaOH at a 0,80V vs SCE potential.

Tumor burden as assessed by 18 F FDG PET scan as predictive biomarker for immune checkpoint blockers in advanced NSCLC - a multi centric study

Introduction Only a proportion of patients with advanced NSCLC benefit from Immune checkpoint blockers (ICBs). No biomarker is validated to choose between ICBs monotherapy or in combination with chemotherapy (Chemo-ICB) when PD-L1 expression is above 50%. The aim of the present study is to validate the biomarker validity of total Metabolic Tumor Volume (tMTV) as assessed by 2-deoxy-2-[18F]fluoro-d-glucose positron emission tomography ([18F]FDG-PET) Material and methods This is a multicentric retrospective study. Patients with advanced NSCLC treated with ICBs, chemotherapy plus ICBs and chemotherapy were enrolled in 12 institutions from 4 countries. Inclusion criteria was a positive PET scan performed within 42 days from treatment start. TMTV was analyzed at each center based on a 42% SUVmax threshold. High tMTV was defined ad tMTV>median Results 493 patients were included, 163 treated with ICBs alone, 236 with chemo-ICBs and 94 with CT. No correlation was found between PD-L1 expression and tMTV. Median PFS for patients with high tMTV (100.1 cm3) was 3.26 months (95% CI 1.94–6.38) vs 14.70 (95% CI 11.51–22.59) for those with low tMTV (p=0.0005). Similarly median OS for pts with high tMTV was 11.4 months (95% CI 8.42 – 19.1) vs 33.1 months for those with low tMTV (95% CI 22.59 – NA), p .00067. In chemo-ICBs treated patients no correlation was found for OS (p = 0.11) and a borderline correlation was found for PFS (p=0.059). Patients with high tMTV and PD-L1 ≥ 50% had a better PFS when treated with combination of chemotherapy and ICBs respect to ICBs alone, with 3.26 months (95% CI 1.94 – 5.79) for ICBs vs 11.94 (95% CI 5.75 – NA) for Chemo ICBs (p = 0.043). Conclusion tMTV is predictive of ICBs benefit, not to CT benefit. tMTV can help to select the best upfront strategy in patients with high tMTV.

Purification and Biochemical Properties of a Glucose-Stimulated beta-D-Glucosidase Produced by Humicola grisea var. thermoidea Grown on Sugarcane Bagasse

The effect of several carbon sources on the production of mycelial-bound beta-glucosidase by Humicola grisea var. thermoidea in submerged fermentation was investigated. Maximum production occurred when cellulose was present in the culture medium, but higher specific activities were achieved with cellobiose or sugarcane bagasse. Xylose or glucose (1%) in the reaction medium stimulated beta-glucosidase activity by about 2-fold in crude extracts from mycelia grown in sugarcane bagasse. The enzyme was purified by ammonium sulfate precipitation, followed by Sephadex G-200 and DEAE-cellulose chromatography, showing a single band in PAGE and SDS-PAGE. The beta-glucosidase had a carbohydrate content of 43% and showed apparent molecular masses of 57 and 60 kDa, as estimated by SDS-PAGE and gel filtration, respectively. The optimal pH and temperature were 6.0 and 50 degrees C, respectively. The purified enzyme was thermostable up to 60 min in water at 55 degrees C and showed half-lives of 7 and 14 min when incubated in the absence or presence of 50 mM glucose, respectively, at 60 degrees C. The enzyme hydrolyzed p-nitrophenyl-beta-D-glucopyranoside, p-nitrophenyl-beta-D-galactopyranoside, p-nitrophenyl-beta-D-fucopyranoside, p-nitrophenyl-beta-D-xylopyranoside, o-nitrophenyl-beta-D-galactopyranoside, lactose, and cellobiose. The best synthetic and natural substrates were p-nitrophenyl-beta-D-fucopyranoside and cellobiose, respectively. Purified enzyme activity was stimulated up to 2-fold by glucose or xylose at concentrations from 25 to 200 mM. The addition of purified or crude beta-glucosidase to a reaction medium containing Trichoderma reesei cellulases increased the saccharification of sugarcane bagasse by about 50%. These findings suggest that H. grisea var. thermoidea beta-glucosidase has a potential for biotechnological applications in the bioconversion of lignocellulosic materials.

Une méta-analyse GWA de la glycémie après 2h d'HGPO révèle que GIPR est associé avec la sécrétion de l'insuline en réponse au glucose et que l'ADCY5 est un nouveau gène de suseptibilité au diabète de type 2. [A meta-analysis of GWA blood glucose after 2 h of OGTT revealed that GIPR is associated with the secretion of insulin based on glucose and ADCY5 is a new susceptibility gene for type 2 diabetes.]

Introduction: Les études GVvA (Genome-wide association ,-studies) ont identifié et confirmé plus de 20 gènes de susceptibilité au DT2 et ont contribué à mieux comprendre sa physiopathologie. L'hyperglycémie à jeun (GJ), et 2 heures après une HGPO (G2h) sont les deux mesures cliniques du diagnostic du DT2. Nous avons identifié récemment la G6P du pancréas (G6PC2) comme déterminant de la variabilité physiologique de la GJ puis Ie récepteur à la mélatonine (MTNRIB) qui de plus lie la régulation du rythme circadien au DT2. Dans ce travail nous avons étudié la génétique de la G2h à l'aide de l'approche GWA. Résultats: Nous avons réalisé une méta-analyse GWA dans le cadre de MAGIC (Meta-Analysis of Glucose and Insulin related traits Consortium) qui a inclus 9 études GWA (N=15'234). La réplication de 29 loci (N=6958-30 121, P < 10-5 ) a confirmé 5 nouveaux loci; 2 étant connus comme associés avec Ie DT2 (TCF7L2, P = 1,6 X 10-10 ) et la GJ (GCKR, p = 5,6 X 10-10 ); alors que GIPR (p= 5,2 X 10-12), VSP13C (p= 3,9 X 10-8) et ADCY5 (p = 1,11 X 10-15 ) sont inédits. GIPR code Ie récepteur au GIP (gastric inhibitory polypeptide) qui est sécrété par les ceIlules intestinales pour stimuler la sécrétion de l'insuline en réponse au glucose (l'effet incrétine). Les porteurs du variant GIPR qui augmente la G2h ont également un indice insulinogénique plus bas, (p= 1,0 X 10-17) mais ils ne présentent aucune modification de leur glycémie suite à une hyperglycémie provoquée par voie veineuse (p= 0,21). Ces résultats soutiennent un effet incrétine du locus GIPR qui expliquerait ~9,6 % de la variance total de ce trait. La biologie de ADCY5 et VPS13C et son lien avec l'homéostasie du glucose restent à élucider. GIPR n'est pas associé avec le risque de DT2 indiquant qu'il influence la variabilité physiologique de la G2h alors que le locus ADCY5 est associé avec le DT2 (OR = 1,11, P = 1,5 X 10-15). Conclusion: Notre étude démontre que l'étude de la G2h est une approche efficace d'une part pour la compréhension de la base génétique de la physiologie de ce trait clinique important et d'autre part pour identifier de nouveaux gènes de susceptibilité au DT2.

Modulation du métabolisme du glucose astrocytaire par les cytokines pro-inflammatoires et le peptide beta-amyloïde. A la recherche d'une composante gliale aux processus neurodégénératifs

Résumé large public: Une altération localisée du métabolisme du glucose, le substrat énergétique préférentiellement utilisé dans le cerveau, est un trait caractéristique précoce de la maladie d'Alzheimer (MA). Il est maintenant largement admis que le beta-amyloïde, la neuroinflammation et le stress oxydatif participent au développement de la MA. Cependant les mécanismes cellulaires de la pathogenèse restent à identifier. Le métabolisme cérébral a ceci de remarquable qu'il repose sur la coopération entre deux types cellulaires, ainsi les astrocytes et les neurones constituent une unité métabolique. Les astrocytes sont notamment responsables de fournir aux neurones des substrats énergétiques, ainsi que des précurseurs du glutathion pour la défense contre le stress oxydatif. Ces fonctions astrocytaires sont essentielles au bon fonctionnement et à la survie neuronale; par conséquent, une altération de ces fonctions astrocytaires pourrait participer au développement de certaines maladies cérébrales. Le but de ce travail est, dans un premier temps, d'explorer les effets de médiateurs de la neuroinflammation (les cytokines pro-inflammatoires) et du peptide beta-amyloïde sur le métabolisme des astrocytes corticaux, en se focalisant sur les éléments en lien avec le métabolisme énergétique et le stress oxydatif. Puis, dans un second temps, de caractériser les conséquences pour les neurones des modifications du métabolisme astrocytaire induites par ces substances. Les résultats obtenus ici montrent que les cytokines pro-inflammatoires et le beta-amyloïde induisent une profonde altération du métabolisme astrocytaire, selon deux profils distincts. Les cytokines pro-inflammatoires, particulièrement en combinaison, agissent comme « découpleurs » du métabolisme énergétique du glucose, en diminuant l'apport potentiel de substrats énergétiques aux neurones. En plus de son effet propre, le peptide beta-amyloïde potentialise les effets des cytokines pro-inflammatoires. Or, dans le cerveau de patients atteints de la MA, les astrocytes sont exposés simultanément à ces deux types de substances. Les deux types de substances ont un effet ambivalent en termes de stress oxydatif. Ils induisent à la fois une augmentation de la libération de glutathion (potentiellement protecteur pour les neurones voisins) et la production d'espèces réactives de l'oxygène (potentiellement toxiques). Etant donné l'importance de la coopération entre astrocytes et neurones, ces modulations du métabolisme astrocytaire pourraient donc avoir un retentissement majeur sur les cellules environnantes, et en particulier sur la fonction et la survie neuronale. Résumé Les astrocytes et les neurones constituent une unité métabolique. Les astrocytes sont notamment responsables de fournir aux neurones des substrats énergétiques, tels que le lactate, ainsi que des précurseurs du glutathion pour la défense contre le stress oxydatif. Une altération localisée du métabolisme du glucose, le substrat énergétique préférentiellement utilisé dans le cerveau, est un trait caractéristique, précoce, de la maladie d'Alzheimer (MA). Il est maintenant largement admis que le beta-amyloïde, la neuroinflammation et le stress oxydatif participent au développement de la MA. Cependant, les mécanismes cellulaires de la pathogenèse restent à identifier. Le but de ce travail est d'explorer les effets des cytokines pro-inflammatoires (Il-1 ß et TNFα) et du beta-amyloïde (Aß) sur le métabolisme du glucose des astrocytes corticaux en culture primaire ainsi que de caractériser les conséquences, pour la viabilité des neurones voisins, des modifications du métabolisme astrocytaire induites par ces substances. Les résultats obtenus montrent que les cytokines pro-inflammatoires et le beta-amyloïde induisent une profonde altération du métabolisme astrocytaire, selon deux profils distincts. Les cytokines pro-inflammatoires, particulièrement en combinaison, agissent comme « découpleurs » du métabolisme glycolytique astrocytaire. Après 48 heures, le traitement avec TNFα et Il-lß cause une augmentation de la capture de glucose et de son métabolisme dans la voie des pentoses phosphates et dans le cycle de Krebs. A l'inverse, il cause une diminution de la libération de lactate et des stocks cellulaires de glycogène. En combinaison avec les cytokines tel qu'in vivo dans les cerveaux de patients atteints de MA, le peptide betaamyloïde potentialise les effets décrits ci-dessus. Isolément, le Aß cause une augmentation coordonnée de la capture de glucose et de toutes les voies de son métabolisme (libération de lactate, glycogenèse, voie des pentoses phosphate et cycle de Krebs). Les traitements altèrent peu les taux de glutathion intracellulaires, par contre ils augmentent massivement la libération de glutathion dans le milieu extracellulaire. A l'inverse, les deux types de traitements augmentent la production intracellulaire d'espèces réactives de l'oxygène (ROS). De plus, les cytokines pro-inflammatoires en combinaison augmentent massivement la production des ROS dans l'espace extracellulaire. Afin de caractériser l'impact de ces altérations métaboliques sur la viabilité des neurones environnants, un modèle de co-culture et des milieux conditionnés astrocytaires ont été utilisés. Les résultats montrent qu'en l'absence d'une source exogène d'antioxydants, la présence d'astrocytes favorise la viabilité neuronale ainsi que leur défense contre le stress oxydatif. Cette propriété n'est cependant pas modulée par les différents traitements. D'autre part, la présence d'astrocytes, et non de milieu conditionné, protège les neurones contre l'excitotoxicité due au glutamate. Les astrocytes prétraités (aussi bien avec le beta-amyloïde qu'avec les cytokines pro-inflammatoires) perdent cette propriété. Cet élément suggère que la perturbation du métabolisme astrocytaire causé par les cytokines pro-inflammatoires ou le beta-amyloïde pourrait participer à l'atteinte de la viabilité neuronale associée à certaines pathologies neurodégénératives.