Prolonged exercise has been associated with depressed immune function, and hence an increased risk of infection. However, several nutritional supplements may reduce or overcome this problem. Thus, the aims of this thesis were to investigate the effects of some nutritional supplements on athletes immune function. In study 1 (Chapter 3), effects of several vaccine stimulant dose on whole blood culture cytokine production was carried out to determine effective vaccine stimulant dose; which was found to be between a dilution of 4000 (dose 4) and 1000 (dose 6) of the original vaccine. This finding was used for the other studies (Chapter 4 and 5). In addition, the relationship between data obtained from Evidence Investigator analyser and enzyme linked-immuno-sorbent assay (ELISA) for IL-10 was analysed and the results show a positive strong correlation between them. In study 2 (Chapter 4), in vitro effects of various immunomodulatory nutritional compounds on antigen-stimulated whole blood culture cytokine production was investigated and it was found that caffeine and quercetin showed tendency towards decrease cytokine production as the doses were increased. On the other hand, an upward trend was evident with kaloba, where high dose of kaloba seemed to increase the cytokine production. Since kaloba appeared to act as an immunostimulant in vitro, its effects on the immune response to prolonged exercise were examined in study 3 (Chapter 5). However, 7 days kaloba supplementation (20 mg of the root extract) did not alter athletes immune response although prolonged moderate intensity exercise significantly decreased S-IgA secretion rate and concentration post-exercise with the values returning to baseline by 1 h post-exercise. A 14-strain probiotic supplement effects on salivary antimicrobial proteins at rest and in response to an acute bout of prolonged exercise was investigated in study 4 (Chapter 6). Unfortunately, 30 days supplementation of the 14-strain probiotic appeared not enough to induce any significant effects on salivary antimicrobial proteins. Lastly, in study 5 (Chapter 7), the effects of a Lactobacillus probiotic on healthy people, who tend to have a higher than normal incidence of infection due to exercise stress-induced immune impairment was studied. In summary, this 16-week intervention study on 267 athletes found that regular ingestion of the probiotic reduced the extent to which training was negatively affected in endurance athletes when infection was present, and increased both S-IgA concentration and secretion rate over time. But it did not appear to reduce URTI incidence or the duration and severity of URTI episodes. Two major confounding factors, namely the unexpectedly low incidence of URTI during the winter period and the lower baseline S-IgA in the probiotic group may have prevented potential beneficial effects of probiotic supplementation from being identified.

The series of experiments that comprises this thesis consider the use of prebiotics and probiotics to improve success in European lobster Homarus gammarus culture. Research was conducted at the National Lobster Hatchery and The University of Plymouth, UK between April 2007 and March 2010. Great potential was revealed for the application of biotics as dietary supplements in the culture of larval and juvenile H. gammarus. Specific biotics, namely; prebiotic mannon oligosaccharide (MOS) and probiotic Sanolife® (Bacillus spp.) were revealed to increase growth and survival during the culture of early lobster life stages. Lobsters that showed enhanced development and/or survival were found to possess improved feed conversion, immune status and/or stress tolerance. Furthermore it was found that biotic fed lobsters displayed shifts in gastrointestinal (GI) microbiology and enhanced physical GI structures, which may account for improved feed conversion and consequently growth. The work presented thus demonstrates that by making positive changes in GI structure and bacterial community composition combined with influencing immune status culture success can be positively enhanced through the biotic supplementation of diets. However, it must be considered that the outcome of dietary biotic supplementation is heavily influenced by the situation in question.

La presente investigación se realizó con el fin de evaluar el efecto probiótico de 3 diferentes dosis de Lactobacillus spp. como aditivo sobre parámetros productivos en Cavia porcellus. Se utilizaron 4 grupos de 8 cuyes machos destetados a las 2 semanas cada uno: 3 tratamientos y 1 control. El primer (T1), segundo (T2) y tercer tratamiento (T3) constaron de dosis diarias de 2.5x108, 2.5x109 y 2.5x1010 ufc del probiótico, respectivamente; para el grupo control (TC) suero fisiológico. El probiótico se obtuvo de un yogurt comercial mediante técnicas de aislamiento, identificación y liofilización. La administración del probiótico y el suero fisiológico fue vía oral e individualmente por 7 semanas; además, de recibir concentrado y forraje como alimento. Se empleó un diseño por bloques completos y aleatorizado, las variables en estudio fueron: peso, incremento de peso, conversión alimenticia y rendimiento de carcasa. Los resultados a las 7 semanas fueron: peso final de T1, T2, T3 y TC, 921, 933, 947 y 913 gr; incremento de peso total de T1, T2, T3 y TC, 640.5, 644.75, 632 y 654.75 gr; índice de conversión alimenticia promedio de T1, T2, T3 y TC, 2.90, 2.83, 3.11 y 2.52; y el rendimiento de carcasa promedio de T1, T2, T3 y TC 73.6%, 72.3%, 71.9% y 72.2%, respectivamente. Al análisis estadístico se encontró que no existe diferencia estadísticas significativas entre los grupos tratamiento y control, en las variables estudiadas. A la necropsia no se encontraron lesiones macroscópicas y los grupos tratamiento dieron resultados negativos de cultivos bacterianos para Salmonella spp. en un 100% de los casos, mientras que el grupo control dio un resultado positivo, lo que demuestra que el probiótico posiblemente puede inhibir el crecimiento de Salmonella.The present investigation was realized in order to evaluate the probiotic effect of 3 different doses of Lactobacillus spp. as additive on productive parameters in Cavia porcellus. There were 4 groups of 8 male guinea pigs weaned at 2 weeks each one: 3 treatments and 1 control. The first (T1), the second (T2) and the third (T3) consist of a daily doses of 2.5x108, 2.5x109 y 2.5x1010 cfu of the probiotic respectively; for the control group (TC) only physiological serum. The probiotic was obtained from a commercial yogurt by isolation, identification and freeze-dry techniques. The administration of the probiotic and the serum was individually and orally for 7 weeks, besides receiving concentrate and forage as food. Was used a complete and randomized blocks design, the variables in study were: weight, gain of weight, food conversion and carcass performance. The results at the 7 weeks were: final weight of T1, T2, T3 and TC, 921, 933, 947 and 913 gr; gain of total weight of T1, T2, T3, TC, 640.5, 644.75, 632 and 654.75 gr; average food conversion index of T1, T2, T3 and TC, 2.90, 2.83, 3.11 and 2.52; and average of carcass performance of T1, T2, T3 and TC, 73.6%, 72.3%, 71.9% and 72.2%, respectively. At the statistical analysis were found that there isn’t significant statistic difference between the treatments and control groups in the study variables. At the necropsy there wasn’t macroscopic injuries and the treatments groups show negative results in specific bacterial cultures for Salmonella spp. in 100% of the cases, while the control group have one positive result, which demonstrate that the probiotic can possibly disable Salmonella's growth.

The goal of the work presented herein was to further our understanding of the rumen microbiota and microbiome of wild moose, and to use that understanding to improve other processes. The moose has adapted to eating a diet of woody browse, which is very high in fiber, but low in digestibility due to the complexity of the plant polysaccharides, and the presence of tannins, lignin, and other plant-secondary compounds. Therefore, it was hypothesized that the moose would host novel microorganisms that would be capable of a wide variety of enzymatic functions, such as improved fiber breakdown, metabolism of digestibility-reducing or toxic plant compounds, or production of functional metabolites, such as volatile fatty acids, biogenic amines, etc. The first aim, naturally, was to identify the microorganisms present in the rumen of moose, in this case, the bacteria, archaea, and protozoa. This was done using a variety of high-throughput techniques focusing on the SSU rRNA gene (see CHAPTERS 2-5). The second aim was to culture bacteria from the rumen of the moose in order to study their biochemical capabilities (see CHAPTERS 6-7). The final aim was to apply those cultured bacterial isolates to improve other systems. Specifically, bacteria from the rumen of the moose was introduced to young lambs in order to colonize the digestive tract, speed the pace of rumen development, and improve dietary efficiency (see CHAPTER 8).

Probiotic dairy foods, especially non- and low-fat dairy products, are becoming popular in the US. A non-fat goat's milk yogurt containing probiotics (Lactobacillus acidophilus and Bifidobacterium spp.) was developed using heat-treated whey protein concentrate (HWPC) as a fat replacer and pectin as a thickening agent. Yogurts containing non-heat treated whey protein concentrate (WPC) and pectin as well as one with only pectin were also produced. A fat-free cow's milk yogurt with pectin was also used as a control yogurt. The yogurts were analyzed for chemical composition, water holding capacity (syneresis), microstructure, changes in pH and viscosity, mold, yeast and coliform counts, and probiotic survivability during storage at 4°C for 10 weeks. The results showed that the non-fat goat's milk yogurt made with 12% HWPC (12.5% WPC solution heated at 85°C for 30 min at pH 8.5) and 0.35% pectin, had a significantly higher viscosity (P<0.01) than any of the other yogurts and low syneresis than the goat’s yogurt with only pectin added (P<0.01). After 10 weeks in storage, viscosity and pH remained constant throughout all of the yogurts. Mold, yeast, and coliform counts were negative throughout the 10 week study. Bifidobacterium spp. remained stable and counts remained above 10⁶CFU g⁻ ¹ during the 10 week storage. However, the population of Lactobacillus acidophilus dropped below 10⁶CFU g⁻ ¹ after 2 weeks of storage. Microstructure analysis of the non - fat goat’s milk yogurt determined by scanning electron microscopy revealed that HWPC interacted with casein micelles to form a more comprehensive network in the yogurt gel. The results indicate that HWPC could be used as a fat replacer to improve the consistency of non - fat goat’s milk yogurt and other products alike.

La cavité buccale est un écosystème dynamique et complexe à l'équilibre fragile. A l'occasion de modifications des conditions environnementales ou d'une augmentation de la sensibilité de l'hôte, il y a rupture de cet équilibre. L'altération des conditions locales va permettre la croissance et le développement d'espèces pathogènes jusqu'alors faiblement représentées, ce qui va autoriser la survenue de diverses pathologies infectieuses orales. Devant l'insuffisance des solutions apportées par une prise en charge uniquement mécanique, des moyens supplémentaires doivent être envisagés. La stratégie probiotique ouvre une voie séduisante puisque l'on se propose de remplacer des bactéries pathogènes par des microorganismes ayant des effets bénéfiques sur la santé orale. L'objectif de ce travail vise donc à identifier des souches probiotiques parmi des isolats oraux de lactobacilles. Pour cela, soixante six souches ont été évaluées. Afin de prédire leur persistance orale, trois méthodes différentes d'évaluation de l'adhérence ont été utilisées : une méthode sur tube de verre, la méthode MATS et un modèle de biofilm monoespèce. Des études in vitro ont été conduites pour déterminer si les lactobacilles pouvaient inhiber des pathogènes carieux (Streptococcus mutans et Actinomyces viscosus) et certains pathogènes parodontaux (Fusobacterium nucleatum et Porphyromonas gingivalis) et pour identifier les mécanismes impliqués. Enfin, les capacités fermentaires de certaines souches ont été appréciées, afin d'éviter l'apparition d'effets délétères comme la déminéralisation carieuse. Trois souches seulement ont montré des capacités d'adhérence intéressantes. Selon les critères que nous avions défini pour caractériser une activité comme antibactérienne, aucune souche n'a inhibé P. gingivalis et 9 souches ont été retenues pour leur pouvoir inhibiteur contre les autres pathogènes. Le mode d'action précis de l'inhibition reste encore à préciser. Dans les conditions de cette étude, aucune des souches évaluées pour son activité fermentaire n'a présenté un risque cariogène. Ce travail a permis de mettre en évidence des souches intéressantes soit de part leur adhérence soit de part leur activité inhibitrice. Des études in vitro complémentaires semblent nécessaires (évaluation de la stimulation immunitaire, précision sur les mécanismes impliqués dans les effets observés) avant de poursuivre sur un modèle animal ou des études cliniques chez l'Homme. / The oral cavity is a complex and dynamic ecosystem with a delicate balance. On the occasion of changes in environmental conditions or an increase in the sensitivity of the host, a break can occur. The alteration of local conditions will allow the growth and development of pathogenic species hitherto poorly represented, which will allow the occurrence of various oral infectious diseases. Due to the lack of solutions given by a purely mechanical support, additional resources should be considered. Probiotic strategy appears as an attractive way since it proposes to replace pathogenic bacteria by microorganisms having beneficial effects on oral health. The aim of this study was therefore to identify probiotic strains among oral lactobacilli isolates. To this end, sixty-six strains were evaluated. To predict persistence in mouth, three different methods of assessing adherence were used: a method on glass tube, the MATS method and a monospecie biofilm model. In vitro studies were conducted to determine whether lactobacilli could inhibit caries pathogens (Streptococcus mutans and Actinomyces viscosus) and some periopathogens (Fusobacterium nucleatum and Porphyromonas gingivalis) and to identify the mechanisms involved. Finally, the fermentation capacity of certain strains was assessed in order to avoid the occurrence of adverse effects such as carious demineralization. Only three strains showed adhesion interesting capabilities. According to the criteria we defined to characterize an activity as antibacterial, no strain inhibited P. gingivalis and 9 strains were selected for their inhibitory potency against the others pathogens. The precise mode of action of the inhibition remains unclear. Under the conditions of this study, none of the strains tested for its fermentative activity has introduced a cariogenic risk. This work has highlighted interesting strains because of their adhesion or because of their inhibitory activity. Additional in vitro studies seem necessary (evaluation of immune stimulation, precision of the mechanisms involved in the observed effects) before continuing in an animal model and clinical studies in humans.

Depuis quelques années, les probiotiques sont devenus un front de science très actif. La majorité des bactéries probiotiques actuellement sur le marché sont des bactéries lactiques. L’identification de nouvelles souches bactériennes aux propriétés probiotiques est l’objectif principal de ces travaux de thèse, et s’inscrivent dans le cadre du projet Probiotique en partenariat avec deux groupes industriels et le pôle de compétitivité VITAGORA. / In recent years, probiotics market is boosting. Most probiotic bacteria on the market today are lactic acid bacteria. The identification of novel bacterial strains with probiotic properties is the main objective of this thesis, which is part of the Probiotic project in partnership with two industry groups and the network innovation VITAGORA.

Les patients atteints de MICI (maladie de Crohn et recto-colite hémorragique) présentent souvent des lésions des cellules de l'épithélium intestinal. La rémission de ces maladies nécessite à la fois un arrêt de l'inflammation et une migration des entérocytes pour réparer les dommages épithéliaux. Cette migration cellulaire appelée restitution intestinale requiert des adhérences cellule-MEC et cellule-cellule réalisées par les complexes protéiques associés aux intégrines et cadhérines. Le but de cette thèse a été d'étudier l'impact deSaccharomyces boulardii (Sb) sur la réparation de l'épithélium intestinal lésé. Nous avons montré que le surnageant de Sb contenait des facteurs modulant la restitution de l'épithélium intestinal in vivo et in vitro sans affecter la prolifération des cellules épithéliales. Ces effets motogéniques du surnageant de Sb s'exercent via la modulation des molécules d'adhérence. En effet, le surnageant de Sb augmente l'affinité de l'intégrine α2β1 pour son ligand le collagène de type I mais entre en compétition avec les intégrine αvβ5, pour inhiber l'adhérence des entérocytes sur la vitronectine. Ces modifications de l'adhérence avec la matrice extracellulaire entraînent une régulation des voies de signalisation émanant des intégrines et une réorganisation des plaquesd'adhérence. Ces évènements vont accroître la migration des entérocytes. De plus, nos résultats préliminaires portant sur Sb et l'adhérence cellule-cellule durant la restitution intestinale ont montré une implication de la E-cadhérine dans la migration induite par Sb. / Intestinal epithelial cell damage is frequently seen in IBD patients with ulcerative colitis or Crohn's disease. The remission of these diseases requires both the cessation of inflammation and the migration of enterocytes torepair the damaged epithelium. Adhesions with the ECM and the adjacent cells using complex of proteins associated with integrins and cadherins are necessary for this cell migration called intestinal restitution. Theaim of this thesis was to study the effect of S.boulardii on the resealing of a wound in intestinal epithelia. First of all, we demonstrated that the supernatant of S.boulardii contains factors that modulate intestinal epithelial cell restitution both in vitro and in vivo without affecting cell proliferation. We showed that the motogenic factors of S.boulardii act by modulating adhesion molecules. Indeed, the supernatant of S.boulardii increase the the affinity between 21 and it ligand the collagen type I, but also compete with integrin v5 to block theadhesion of enterocytes on vitronectin. These modifications of adhesion on extracellular matrix lead to aregulation of signaling pathway mediated by integrins, and a reorganization of focal adhesions. These eventscontribute to an increase of the migration of enterocytes. Add to this, our preliminaries results on S.boulardiiand cell-cell adhesion during intestinal restitution show an involvement of E-cadherin in the migrationS.boulardii-induced. With this work, we have demonstrated that heat-sensitive motogenic factors secreted by S.boulardii can enhance intestinal restitution with a dynamic regulation of adhesion between integrin and the ECM.

L’obésité est caractérisée par un état inflammatoire chronique dit « à bas bruit », se traduisant par l’augmentation des taux plasmatiques de facteurs inflammatoires qui contribuent au développement des complications métaboliques telles que le diabète de type 2 et la résistance à l’insuline.L’inflammation chronique est initiée par l’accumulation séquentielle et finement régulée de cellules immunes dans le tissu adipeux blanc, contribuant à créer un microenvironnement inflammatoire qui altère la physiologie et l’homéostasie du tissu. Une meilleure compréhension : 1) des mécanismes contrôlant les altérations de la composition en cellules immunes du tissu adipeux blanc et 2) du rôle de ces cellules dans la fonction des principaux tissus métaboliques, pourrait, à terme, permettre de proposer de nouvelles voies thérapeutiques d’immuno-intervention dans le traitement des complications métaboliques associées à l’obésité. Durant mon parcours de thèse, j’ai étudié les conséquences métaboliques et immunologiques du traitement de souris obèses par un agent immuno-modulateur : la rapamycine, ainsi que par des probiotiques ayant des propriétés anti-inflammatoires.Partie 1 : Etude des effets de la rapamycine sur la réponse inflammatoire et l’homéostasie énergétique chez la souris obèse.Cette étude représente la partie principale de mon travail de thèse. L’objectif de mon projet de thèse était de définir les conséquences de l’administration prolongée de rapamycine (ou Sirolimus) sur l’inflammation du tissu adipeux blanc et le métabolisme glucidique de souris obèses. La rapamycine est un inhibiteur spécifique de la voie du mechanistic target of rapamycin (mTOR) possédant des propriétés immunosuppressives et antiprolifératives et qui est fréquemment utilisé chez les patients transplantés afin d’éviter le rejet du greffon. Cependant, la rapamycine a été décrite comme possédant un potentiel diabétogène et pro-inflammatoire : en effet, certains patients traités développent un diabète post-transplantation et sont plus susceptibles de présenter des pathologies inflammatoires et ceci, malgré une perte de poids. Les objectifs de notre étude étaient de : 1) Déterminer les conséquences métaboliques (bénéfiques ou délétères) de l’administration de rapamycine et 2) Définir le profil inflammatoire des souris obèses traitées, notamment dans le tissu adipeux blanc.Partie 2 : Etude des effets des probiotiques sur le développement de l’obésité et la résistance à l’insuline chez la souris obèse.Les effets des probiotiques sur le développement de l’obésité et ses complications métaboliques et immunologiques associées sont contradictoires et restent donc à clarifier. Certaines études ont montré des effets obésogènes de certains probiotiques tandis que d’autres travaux décrivent des effets bénéfiques sur l’homéostasie énergétique. Les objectifs de notre étude étaient de : 1) Déterminer les conséquences métaboliques et immunologiques de l’ingestion prolongée de certaines souches (ou combinaison de souches) de probiotiques dans un modèle de souris obèses et 2) Définir les mécanismes cellulaires et moléculaires sous-tendant les effets de probiotiques sur le développement de l’obésité et de l’inflammation associée. / Obesity is characterized by a low-grade chronic inflammation reflected by increased blood levels of inflammatory factors, which are known to contribute to the development of metabolic complications such as insulin resistance and type 2 diabetes.Obesity-related inflammation is initiated by the accumulation of inflammatory immune cells within the adipose tissue as observed in obese subjects, contributing to alteration of the physiology and the metabolic homeostasis of the tissue. A better understanding of the mechanisms controlling the balance between adipose tissue immune cells and the interaction of these cells with the metabolic tissues (e.g. white adipose tissue) could lead to the development of immune-based new therapeutic strategies to treat metabolic complications associated with obesity.During my PhD thesis, we worked on two projects that both aimed at studying the link between immunity and metabolism. We studied the consequences of the treatment of obese mice with the immunomodulatory drug rapamycin (Part 1) and with probiotics having anti-inflammatory properties (Part 2).Part 1: Beneficial Metabolic Effects of Rapamycin are Associated with Enhanced Regulatory Cells in Diet-Induced Obese MiceThis part corresponded to my main project. We aimed to analyze the effect of rapamycin (or Sirolimus), on the inflammatory response and the metabolic status of high-fat diet fed mice. Rapamycin is an immunosuppressive drug commonly used in transplanted patients to prevent graft rejection. However, the effects of rapamycin on metabolism remain elusive and it has been reported that rapamycin may have pro-inflammatory and prodiabetic properties since some transplanted patients can develop diabetes and inflammatory diseases. Rapamycin is a specific inhibitor of mTOR (mechanistic Target Of Rapamycin), a highly conserved kinase which play a key role in both metabolism and immunity. Our aims were: 1) to define the metabolic consequences of long-term rapamycin administration and 2) to analyze the immune profile of treated animals.Part 2: A Probiotic Mixture Alleviates Diet-Induced Obesity and Insulin Resistance in Mice through Adipose Tissue Cell-RemodelingThe effects of probiotics on the development of obesity and its associated-metabolic complications are contradictory and thus remain to be clarified. In our study, we evaluated the consequences of the consumption of different strains of probiotics (or a combination of strains) selected for their anti-inflammatory properties, on the development of obesity and inflammation. We thus defined the metabolic and immune profile of probiotic-treated obese mice, mostly focusing on the adipose tissue. Finally, we attempted to identify the cellular and molecular mechanisms by which our selected probiotics exerted their metabolic and immune protective effects.

The main goal in reversing the allergy epidemic is the development of effective prophylactic strategies. Early life events, such as exposures to microbes, have a major influence on the development of balanced immune responses. Due to their ability to interact with host immune system and to modulate host immune responses probiotics, mainly bifidobacteria and lactobacilli have been used with some success in prevention of allergic disease. In order to be referred to as probiotic, bacterial strain has to undergo rigorous testing. We have selected three new Lactobacillus (L.) strains out of 24 human isolates according to their antagonistic activity against pathogenic bacteria, resistance to low pH and milieu of bile salts. Safety of these strains was proven upon intragastric administration to mice; moreover, we have shown their ability to shift cytokine Th1 - Th2 balance towards non-allergic Th1 response in isolated splenic cells. Allergen specific prophylaxis using probiotics as vehicles for mucosal delivery of recombinant allergen is an attractive concept for development of well-tolerated and effective allergy vaccines. We have shown that neonatal mono-colonization of germ-free mice with the L. plantarum NCIMB8826 strain producing the major birch pollen allergen Bet v 1 attenuates the development of...