Influence of intestinal microbiota in celiac disease pathogenesis and risk

Tesis por compendio[EN] Celiac disease (CD) is a chronic enteropathy triggered by cereal gluten proteins in genetically predisposed individuals. The etiology is strongly associated with the genes of the human leukocyte antigen (HLA) encoding the DQ2/DQ8 molecules. Most CD patients carry this genotype but this is also present in the 40% of the general population and only a small percentage develops the disease. Thus, the HLA-DQ genotype is necessary but not solely responsible for the disease development. Gluten is the main environmental trigger but its intake neither fully explains the onset nor its clinical manifestations. Other environmental factors (e.g. early feeding practices, infections, intestinal microbiota) have been associated with the risk of developing CD. The only treatment for CD patients is the adherence to a gluten free diet (GFD), but the compliance with this dietary strategy is complicated because gluten is present in many foods. Therefore, the identification of modifiable environmental factors that contribute to CD onset is critical for the development of strategies to reduce its incidence. Observational studies in CD patients revealed imbalances in the intestinal microbiota which could contribute to the pathogenesis of the disease. It has been proposed that these imbalances are not only a secondary consequence of the disease but could also be a predisposing factor. To understand whether gut microbiota imbalances play a role in CD onset and pathogenesis, in vitro, animal and human prospective and intervention studies have been conducted in the context of the present PhD Thesis. The global aim of this Thesis has been to improve the understanding of the role played by intestinal microbiota in the pathogenesis and risk of CD, and the possibilities of contributing to disease prevention and treatment by modulating gut microbiota composition. Chapter 1 includes two in vitro studies investigating the influence of components of the gut microbiota (bifidobacteria and enterobacteria) on the maturation and functions of immunocompetent cells (dendritic cells), and on gluten toxicity in the intestinal epithelium (Caco-2 cells). We have observed that some Bifidobacterium strains are able to reduce the activation of dendritic cells and ameliorate the toxicity of gluten on intestinal epithelial cells. In Chapter 2 the effects of the administration of Bifidobacterium longum CECT 7347 was evaluated in an in vivo model of gluten induced enteropathy in newborn rats, resulting in a reduced proinflammatory cytokine production in the small intestine and CD4+T cell numbers in peripheral blood. Chapter 3 includes two observational studies in humans to unravel whether breast-feeding and human milk composition and/or the host genotype (HLA-DQ) are related to the microbiota, thereby influencing the later development of CD. We concluded that both factors may contribute to the early intestinal colonization of the infant's gut, influencing the Bifidobacterium spp. numbers. Human milk composition also varies in CD and non-CD mothers, modifying the supply of bifidobacteria and protective immune factors to the offspring. Finally, in Chapter 4 we have studied the potential beneficial effects of the administration of B. longum CECT 7347 in addition to the GFD to children with newly diagnosed CD. This study demonstrates that the bifidobacteria slightly reduces serum inflammatory markers and restored the gut microbiota composition.[ES] La enfermedad celíaca (EC) es una enteropatía crónica de carácter autoinmune que sufren individuos genéticamente predispuestos tras la ingesta de gluten. La etiología está asociada con los genes del sistema "Antígeno Leucocitario Humano" (HLA) que codifican las moléculas DQ2/DQ8. Los pacientes con EC presentan este genotipo, sin embargo este también está presente en ¿40% de la población general y sólo un pequeño porcentaje desarrolla la enfermedad. Por lo tanto, el genotipo HLA-DQ resulta necesario pero no suficiente para que se desarrolle la enfermedad. El gluten es el principal desencadenante pero su ingesta tampoco explica su desarrollo ni sus manifestaciones clínicas. Otros factores ambientales (p.e. la lactancia, infecciones, microbiota intestinal) se han asociado con el riesgo de desarrollar la EC. El único tratamiento para los pacientes celíacos es el seguimiento de una dieta exenta de gluten (DEG), sin embargo su cumplimiento es complicado debido a que el gluten está presente en la mayoría de los alimentos procesados. Por ello, la identificación de factores ambientales modificables que contribuyan al desarrollo de la enfermedad, resulta fundamental para desarrollar estrategias que permitan reducir su incidencia. Estudios observacionales realizados en pacientes con la EC, han demostrado la existencia de desequilibrios en su microbiota intestinal, que podrían contribuir a la patogénesis de la enfermedad. Se ha propuesto que estos desequilibrios no son sólo una consecuencia secundaria de la EC, sino que podrían ser un factor predisponente. Para entender si la microbiota está implicada en el desarrollo y patogénesis de la EC, en la presente Tesis se han desarrollado estudios in vitro, con animales y estudios prospectivos y de intervención en humanos. El objetivo de esta Tesis ha sido avanzar en el conocimiento de la función que la microbiota intestinal desempeña en la patogénesis de la EC, así como, acerca de las posibilidades de tratar o prevenir esta enfermedad mediante la modulación de la composición de la microbiota intestinal. El Capítulo 1 incluye dos estudios in vitro en los que se ha estudiado la influencia de componentes de la microbiota intestinal (bifidobacterias y enterobacterias) en la maduración y las funciones de células inmunocompetentes (células dendríticas), y en la toxicidad del gluten en el epitelio intestinal (células Caco-2). Hemos observado que algunas cepas de Bifidobacterium son capaces de reducir la activación de las células dendríticas y de reducir la toxicidad del gluten sobre el epitelio intestinal. En Capítulo 2 incluye el estudio de los efectos de la administración de B. longum CECT 7347 en un modelo de enteropatía inducida por gluten en ratas recién nacidas, observándose una reducción de citoquinas proinflamatorias en el intestino y de células T CD4+ en sangre periférica. El Capítulo 3 incluye dos estudios observaciones en humanos en los que se ha investigado si la lactancia y composición de la leche materna y/o el genotipo (HLA-DQ) están relacionados con la microbiota y, si así, podrían influir en el desarrollo de la EC. Concluimos que ambos factores contribuyen a la colonización intestinal del niño en los primeros meses de vida, afectando especialmente al número de Bifidobacterium spp. La composición de la leche maternal varía entre madres celíacas y sanas, lo que podría modificar el aporte de bifidobacterias y factores inmunológicos protectores al lactante. Por último, en el Capítulo 4 incluye el estudio del potencial efecto beneficioso de la administración de B. longum CECT 7347 junto con la DEG en niños recién diagnosticados de EC. Este estudio demuestra que la bifidobacteria ligeramente reduce los marcadores inflamatorios en sangre periférica y contribuye a restablecer la composición de la microbiota intestinal.[CA] La malaltia celíaca (MC) és una enteropatia crònica provocada per les proteines del gluten de cereals en individus predisposats genèticament. L'etiologia està fortament associat amb els gens de l'antigen leucocitari humà (HLA). Pacients amb MC porten aquest genotip però també està present en aproximadament el 40% de la població general i només un petit percentatge (1-3%) es desenvolupa la malaltia. Per tant, HLA-DQ genotip és necessària, però no l'únic responsable. El gluten és el principal desencadenant ambiental però la seva ingesta no explica completament l'inici ni les seves manifestacions clíniques. Altres factors ambientals, com la microbiota intestinal, s'han associat amb el risc de desenvolupar CD. Els estudis observacionals en pacients amb MC van revelar desequilibris en la microbiota intestinal que podria contribuir a la patogènesi de la malaltia. S'ha proposat que aquests desequilibris no només són una conseqüència secundària de la malaltia, però també podria ser un factor predisponent. Per entendre si els desequilibris microbiota intestinal podrien tenir un paper en l'aparició de CD, un estudi prospectiu amb el nen en risc la família està en marxa. L'únic tractament per als pacients amb EC és l'adherència a una dieta lliure de gluten, però el seu compliment és complicada a causa del gluten està present en molts aliments. La identificació de factors ambientals modificables que contribueixen a l'aparició de CD és fonamental per a les estratègies de desenvolupament que porten a una reducció de la incidència. Aquest pot ser el cas per als components de la microbiota intestinal, l'adquisició podria ser modulada per factors ambientals i dietètics. L'objectiu global de la tesi és desentranyar els coneixements actuals sobre el paper exercit per la microbiota intestinal en la patogènesi de l'EC, i les possibilitats de contribuir a la prevenció i tractament de la malaltia mitjançant la modulació de la composició de la microbiota intestinal En el Capítol 1 hem estudiat l'ús de models in vitro de la influència de la microbiota intestinal durant la maduració i funcions del sistema immunològic (cèl·lules dendrítiques), i les interaccions entre el gluten i intestinal intestí i la resposta de l'epiteli intestinal resultant d'aquesta interacció. Hem observat que alguns ceps de Bifidobacterium són capaços de reduir l'activació del sistema immune i millorar la resposta nociva de l'epiteli intestinal a l'estimulació amb gluten. En el Capítol 2 hem estudiat els efectes de l'administració d'una soca de Bifidobacterium (B. longum CECT 7347) per a un model animal de rates nounades. El tractament amb els bacteris es va associar amb una reducció en la producció de citocines proinflamatòries i la resposta immune de cèl·lules T CD4 +. En el Capítol 3 es va descriure que alguns genètic (HLA-DQ genotip) i factors ambientals (llet materna) influeixen en la colonització intestinal primerenca, especialment en Bifidobacterium spp., que poden influir en l'aparició de CD més tard. Finalment, en el Capítol 4 s'ha estudiat l'efecte probiòtic de l'administració de B. longum CECT 7347 en nens acabats diagnosticats d'EC i el seu paper en el restabliment de la salut intestinal.Olivares Sevilla, M. (2015). Influence of intestinal microbiota in celiac disease pathogenesis and risk [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/58768TESISPremios Extraordinarios de tesis doctoralesCompendi

Effects of Transcranial Direct Current Stimulation on Long-term Motor Learning and Retention

Programa Oficial de Doutoramento en Enxeñaría Civil . 5011V01[Abstract] Optimizing the teaching-learning process is essential throughout life. Non-invasive brain stimulation techniques such as transcranial direct current stimulation (tDCS) seem to be an option for optimizing the motor learning curve. This thesis aims to study the effects of tDCS on motor learning, including the retention of a motor. The first randomized controlled study explored the effects of applying tDCS before, during, or after motor practice on retention of the practiced skill in 100 participants. After a single session, similar performance changes were observed in all groups, with no significant differences in the choice reaction time task. In the second randomized controlled study, we examined the effects of tDCS on typing performance in 63 participants. Participants performed a structured program of 23 intervention sessions across 3.5-month: 20, 15-min typing practice and 3 evaluations (pre, middle, post). tDCS group performed better motor performance in the rapid learning phase compared to the sham and control groups. However, these differences dissipated from session 11th. In conclusion, tDCS appears to be a safe stimulation method when administered over multiple sessions in healthy young adults but failed to enhance motor skill acquisition and retention compared with a sham control group.Resumen] Optimizar el proceso de enseñanza-aprendizaje es fundamental durante la vida. La estimulación transcraneal por corriente directa (tDCS) podría optimizar la curva de aprendizaje motor. El objetivo de la tesis fue estudiar los efectos de la tDCS sobre el aprendizaje, incluyendo la fase de retención. El primer estudio controlado aleatorio exploró los efectos de la aplicación de la tDCS antes, durante, o después, de la práctica sobre la retención en 100 participantes. Después de una sesión, se observaron cambios de rendimiento similares en todos los grupos en una tarea de tiempos de reacción aleatorios. En el segundo estudio controlado aleatorio, examinamos los efectos de la tDCS sobre el rendimiento mecanográfico. Los 63 participantes realizaron un programa estructurado durante 3.5-meses que incluía 20 prácticas y 3 evaluaciones (pre-, media- y post-intervención). El grupo tDCS obtuvo un mejor rendimiento en la fase rápida del aprendizaje en comparación con el grupo placebo y el grupo control, aunque estas diferencias se disiparon desde la sesión 11 en adelante. En conclusión, la tDCS parece ser segura aplicada en sesiones múltiples en adultos jóvenes y sanos, pero no eficaz para mejorar el aprendizaje de habilidades motoras en comparación con los grupos control y placebo.[Resumo] Optimizar o proceso de ensino-aprendizaxe é fundamental durante a vida. A estimulación transcraneal de corrente continua (tDCS) podería optimizar a curva de aprendizaxe motora. O obxectivo da tese foi estudar os efectos do tDCS na aprendizaxe, incluída a fase de retención. O primeiro estudo controlado aleatorizado explorou os efectos da aplicación de tDCS antes, durante ou despois da práctica sobre a retención en 100 participantes. Despois dunha sesión, observáronse cambios de rendemento similares en todos os grupos nunha tarefa aleatoria de tempos de reacción. No segundo estudo controlado aleatorizado, examinamos os efectos do tDCS no rendemento da dixitación. Os 63 participantes completaron un programa estruturado de 3.5-meses que incluía 20 prácticas e 3 avaliacións (pre-, media- e post-intervención). O grupo tDCS funcionou mellor na fase rápida de aprendizaxe en comparación co grupo placebo e o grupo control, aínda que estas diferenzas disipáronse a partir da sesión 11. En conclusión, o tDCS parece ser seguro cando se aplica en varias sesións en adultos novos sans, pero non é efectivo para mellorar a aprendizaxe das habilidades motoras en comparación cos grupos control e placeb

Energy storage applications of activated carbons: supercapacitors and hydrogen storage

Porous carbons have several advantageous properties with respect to their use in energy applications that require constrained space such as in electrode materials for supercapacitors and as solid state hydrogen stores. The attractive properties of porous carbons include, ready abundance, chemical and thermal stability, ease of processability and low framework density. Activated carbons, which are perhaps the most explored class of porous carbons, have been traditionally employed as catalyst supports or adsorbents, but lately they are increasingly being used or find potential applications in the fabrication of supercapacitors and as hydrogen storage materials. This manuscript presents the state-of-the-art with respect to the preparation of activated carbons, with emphasis on the more interesting recent developments that allow better control or maximization of porosity, the use of cheap and readily available precursors and tailoring of morphology. This review will show that the renewed interest in the synthesis of activated carbons is matched by intensive investigations into their use in supercapacitors, where they remain the electrode materials of choice. We will also show that activated carbons have been extensively studied as hydrogen storage materials and remain a strong candidate in the search for porous materials that may enable the so-called Hydrogen Economy, wherein hydrogen is used as an energy carrier. The use of activated carbons as energy materials has in the recent past and is currently experiencing rapid growth, and this review aims to present the more significant advances.M.S. acknowledges the assistance of the Spanish MINECO for the award of a Ramón y Cajal contract.Peer reviewe

Graphitic carbon nanostructures from cellulose

Graphitic carbon nanostructures have been synthesized from cellulose via a simple methodology that essentially consists of the steps: (i) hydrothermal treatment of cellulose at 250 °C and (ii) impregnation of the carbonaceous product with a nickel salt followed by thermal treatment at 900 °C. The formation of graphitic carbon nanostructures seems to occur by a dissolution–precipitation mechanism in which amorphous carbon is dissolved in the catalyst nanoparticles and then precipitated as graphitic carbon around the catalyst particles. The subsequent removal of the nickel nanoparticles and amorphous carbon by oxidative treatment leads to graphitic nanostructures with a coil morphology. This material exhibits a high degree of crystallinity and large and accessible surface area.The financial support for this research work provided by the Spanish MCyT (MAT2008-00407) is gratefully acknowledged. M. S. acknowledges the assistance of the Spanish MCyT for the award of a Postdoctoral Mobility contract.Peer reviewe

Direct Synthesis of Highly Porous Interconnected Carbon Nanosheets and Their Application as High-Performance Supercapacitors

An easy, one-step procedure is proposed for the synthesis of highly porous carbon nanosheets with an excellent performance as supercapacitor electrodes. The procedure is based on the carbonization of an organic salt, i.e., potassium citrate, at a temperature in the 750–900 °C range. In this way, carbon particles made up of interconnected carbon nanosheets with a thickness of <80 nm are obtained. The porosity of the carbon nanosheets consists essentially of micropores distributed in two pore systems of 0.7–0.85 nm and 0.95–1.6 nm. Importantly, the micropore sizes of both systems can be enlarged by simply increasing the carbonization temperature. Furthermore, the carbon nanosheets possess BET surface areas in the ∼1400–2200 m2 g–1 range and electronic conductivities in the range of 1.7–7.4 S cm–1 (measured at 7.1 MPa). These materials behave as high-performance supercapacitor electrodes in organic electrolyte and exhibit an excellent power handling ability and a superb robustness over long-term cycling. Excellent results were obtained with the supercapacitor fabricated from the material synthesized at 850 °C in terms of both gravimetric and volumetric energy and power densities. This device was able to deliver ∼13 Wh kg–1 (5.2 Wh L–1) at an extremely high power density of 78 kW kg–1 (31 kW L–1) and ∼30 Wh kg–1 (12 Wh L–1) at a power density of 13 kW kg–1 (5.2 kW L–1) (voltage range of 2.7 V).This research work was supported by the Spanish MINECO (MAT2012-31651). M.S. acknowledges the award of a Ramón y Cajal contract.Peer reviewe

Fabrication of porous carbon monoliths with a graphitic framework

[EN] Macro/mesoporous carbon monoliths with a graphitic framework were synthesized by carbonizing polymeric monoliths of poly(benzoxazine-co-resol). The overall synthesis process consists of the following steps: (a) the preparation of polymeric monoliths by co-polymerization of resorcinol and formaldehyde with a polyamine (tetraethylenepentamine), (b) doping the polymer with a metallic salt of Fe, Ni or Co, (c) carbonization and (d) the removal of inorganic nanoparticles. The metal nanoparticles (Fe, Ni or Co) formed during the carbonization step catalyse the conversion of a fraction of amorphous carbon into graphitic domains. The resulting carbon monoliths contain >50 wt.% of graphitic carbon, which considerably improves their electrical conductivity. The use of tetraethylenepentamine in the synthesis results in a nitrogen-containing framework. Textural characterization of these materials shows that they have a dual porosity made up of macropores and mesopores (∼2–10 nm), with a BET surface area in the 280–400 m2 g−1 range. We tested these materials as electrodes in organic electrolyte supercapacitors and found that no conductive additive is needed due to their high electrical conductivity. In addition, they show a specific capacitance of up to 35 F g−1, excellent rate and cycling performance, delivering up to 10 kW kg−1 at high current densities.The financial support for this research work provided by the Spanish MCyT (CQT2011-24776 and MAT2012-31651) is gratefully acknowledged. M. S. thanks the Spanish MCyT for the award of a Ramón y Cajal contract.Peer reviewe

Superior Capacitive Performance of Hydrochar-Based Porous Carbons in Aqueous Electrolytes

This is the accepted version of the following article: Fuertes, A. B. and Sevilla, M. (2015), Superior Capacitive Performance of Hydrochar-Based Porous Carbons in Aqueous Electrolytes. ChemSusChem, 8: 1049–1057. doi: 10.1002/cssc.201403267, which has been published in final form at http://dx.doi.org/10.1002/cssc.201403267. This article may be used for non-commercial purposes in accordance with the Wiley Self-Archiving PolicyBiomass-based highly porous carbons with excellent performances in aqueous electrolyte-based supercapacitors have been developed. The synthesis of these materials is based on the chemical activation of biomass-based hydrochar. The addition of melamine to the activation mixture leads to porous carbons with a porosity consisting of micropores/small mesopores. Furthermore, melamine promotes the introduction of nitrogen heteroatoms in the carbon framework, along with abundant oxygen functionalities, to improve the wettability. The materials produced in the presence or absence of melamine exhibit high specific capacitances in aqueous electrolytes (>270 F g−1 in H2SO4 and >190 F g−1 in Li2SO4). Additionally, the mesopores present in the melamine-based micro-/mesoporous carbons notably improve the ion-transport kinetics, especially in Li2SO4. Furthermore, in Li2SO4, they remain stable up to a cell voltage of 1.6 V; thus exhibiting superior energy and power characteristics than those in H2SO4.This research work was supported by the Spanish MINECO (MAT2012-31651). M. S. thanks the Spanish MINECO for her Ramón y Cajal contract.Peer reviewe

Mutagenesis-Mediated Decrease of Pathogenicity as a Feature of the Mutant Spectrum of a Viral Population

Background: RNA virus populations are heterogeneous ensembles of closely related genomes termed quasispecies. This highly complex distribution of variants confers important properties to RNA viruses and influences their pathogenic behavior. It has been hypothesized that increased mutagenesis of viral populations, by treatment with mutagenic agents, can induce alterations in the pathogenic potential of a virus population. In this work we investigate whether mutagenized foot-and-mouth disease virus (FMDV) populations display changes in their virulence in mice. Methodology and Principal Findings: FMDV C-S8c1 was passaged in BHK cells in the presence of the mutagenic agent ribavirin. Decline in viral titer and viral RNA progeny was observed in the first passage, fluctuating around a constant value thereafter. Hence, the specific infectivity remained stable during the passages. The viral population harvested from passage 9 (P9 R) showed decreased virulence in mice, with a lethal dose 50 (LD 50) >10 4 PFU, as compared with LD 50 of 50 PFU of the parental population FMDV C-S8c1. This decrease in virulence was associated to a 20-fold increase in the mutation frequency of the P9 R population with respect to C-S8c1. Interestingly, individual biological clones isolated from the attenuated population P9 R were as virulent as the parental virus C-S8c1. Furthermore, a mixed population of C-S8c1 and P9 R was inoculated into mice and showed decreased virulence as compared to C-S8c1, suggesting that population P9 R is able to suppress the virulent phenotype of C-S8c1. Conclusion: Ribavirin-mediated mutagenesis of an FMDV population resulted in attenuation in vivo, albeit a large proportion of its biological clones displayed a highly virulent phenotype. These results, together with the suppression of C-S8c1 by mutagenized P9 R population, document a suppressive effect of mutagenized viral quasispecies in vivo, and suggest novel approaches to the treatment and prevention of viral diseases. © 2012 Sanz-Ramos et al.CISA-INIA Centro de Investigación en Sanidad Animal; Ministerio de Ciencia e Innovación (MCINN); 228394-NADIR-Integrating Activities 7th EU; Fundación Ramón ArecesPeer Reviewe

Carboxyl-functionalized mesoporous silica–carbon composites as highly efficient adsorbents in liquid phase

[EN] Mesoporous silica–carbon composites functionalized with acidic oxygen groups were prepared by oxidation of a layer of carbon deposited inside the silica pores. The synthesis procedure involved the following steps: (a) removal of the silica surfactant, (b) impregnation of the silica pores with a carbon precursor, (c) carbonization and (d) oxidation with ammonium persulfate. The resulting silica–carbon composites contained around 25–30 wt.% of carbonaceous matter with a high density of acid oxygen groups attached to the deposited carbon layer (i.e. –COOH, –Cdouble bond; length as m-dashO and –OH). The structural characteristics of the parent silica were retained by the oxidized composite materials, which exhibit a high surface area, a large pore volume and a well-ordered porosity made up of uniform mesopores. The oxygen-functionalized silica–carbon composites were found to be excellent adsorbents of basic dyes (e.g. methylene blue) and heavy metals (i.e. Cu2+, Zn2+ and Pb2+) in aqueous media.This work was supported by the Spanish MICINN (Project CQT2011-24776). M.S. and P.V-V. acknowledge Ramon y Cajal and JAE-Predoc contracts, respectively.Peer reviewe