Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Variability of Serum Proteins in Chinese and Dutch Human Milk during Lactation
Elwakiel, Mohèb ; Boeren, Sjef ; Hageman, Jos A. ; Szeto, Ignatius M. ; Schols, Henk A. ; Hettinga, Kasper A. - \ 2019
Nutrients 11 (2019)3. - ISSN 2072-6643
digestive tract - immune-active proteins - mammary gland - protease inhibitors - proteases

To better understand the variability of the type and level of serum proteins in human milk, the milk serum proteome of Chinese mothers during lactation was investigated using proteomic techniques and compared to the milk serum proteome of Dutch mothers. This showed that total milk serum protein concentrations in Chinese human milk decreased over a 20-week lactation period, although with variation between mothers in the rate of decrease. Variation was also found in the composition of serum proteins in both colostrum and mature milk, although immune-active proteins, enzymes, and transport proteins were the most abundant for all mothers. These three protein groups account for many of the 15 most abundant proteins, with these 15 proteins covering more than 95% of the total protein concentrations, in both the Chinese and Dutch milk serum proteome. The Dutch and Chinese milk serum proteome were also compared based on 166 common milk serum proteins, which showed that 22% of the 166 serum proteins differed in level. These differences were observed mainly in colostrum and concern several highly abundant proteins. This study also showed that protease inhibitors, which are highly correlated to immune-active proteins, are present in variable amounts in human milk and could be relevant during digestion.

Interactions and functionalities of the gut revealed by computational approaches
Benis, Nirupama - \ 2017
Wageningen University. Promotor(en): M.A. Smits; V.A.P. Martins dos Santos, co-promotor(en): D. Schokker; M. Suarez-Diez. - Wageningen : Wageningen University - ISBN 9789463434546 - 247
pigs - mice - digestive tract - digestive system - intestinal microorganisms - intestinal mucosa - computational science - immune system - feeds - animal nutrition - nutrition physiology - animal health - varkens - muizen - spijsverteringskanaal - spijsverteringsstelsel - darmmicro-organismen - darmslijmvlies - computational science - immuunsysteem - voer - diervoeding - voedingsfysiologie - diergezondheid

The gastrointestinal tract is subject of much research for its role in an organism’s health owing to its role as gatekeeper. The tissue acts as a barrier to keep out harmful substances like pathogens and toxins while absorbing nutrients that arise from the digestion of dietary components in in the lumen. There is a large population of microbiota that plays an important role in the functioning of the gut. All these sub-systems of the gastrointestinal tract contribute to the normal functioning of the gut. Due to its various functionalities, the gut is able to respond to different types of stimuli and bring the system back to homeostasis after perturbations.

The work done in this thesis uses several bioinformatic tools to improve our understanding of the functioning of the gut. This was achieved with data from model animals, mice and pigs which were subjected to changing environments before their gastrointestinal response was measured. Different types of stimuli were studied (eg, antibiotic exposure, changing diets and infection with pathogens) in order to understand the response of the gut to varying environments. This data was analysed using different data integration techniques that provide a holistic view of the gut response.

Vertical data integration techniques look for associations between different types of ~omics data to highlight possible interactions between the measured variables. Lateral integration techniques allow the study of one type of ~omics data over several time points or several experimental conditions. Using these techniques, we show proof of interactions between different sub-systems of the gut and the functional plasticity of the gut. Of the several hypotheses generated in this thesis we have validated several using existing literature and one using an in-vitro system. Further validation of these hypotheses will increase understanding of the responses of the gut and the interactions involved.

FeedOmics, an approach to evaluate the functional properties of protein containing feed ingredients
Kar, Soumya K. - \ 2017
Wageningen University. Promotor(en): M.A. Smits; J.M. Wells, co-promotor(en): A.J.M. Jansman; D. Schokker. - Wageningen : Wageningen University - ISBN 9789463434461 - 254
compound feeds - ingredients - protein sources - proteins - functional properties - metabolism - feed formulation - protein digestion - proteomics - digestive tract - nutrition physiology - animal nutrition - livestock feeding - mengvoer - ingrediënten - eiwitbronnen - eiwitten - functionele eigenschappen - metabolisme - voersamenstelling - eiwitvertering - eiwitexpressieanalyse - spijsverteringskanaal - voedingsfysiologie - diervoeding - veevoeding

This thesis presents FeedOmics approach as a toolkit, to evaluate (novel) protein containing feed ingredients of different origin considering both their nutritional and functional value in terms of their capacity to support or modify nutrient supply, the animal’s physiology, tissue development and functioning. Such knowledge may contribute to introduce novel and/or alternative protein containing feed ingredients in the diet of livestock, thus creating a sustainable food supply for growing human population.

Influence of pectin supplementation on feed fermentation characteristics in rats and pigs
Tian, L. - \ 2016
Wageningen University. Promotor(en): Harry Gruppen; Henk Schols. - Wageningen : Wageningen University - ISBN 9789462577282 - 142
pigs - rats - pectins - feed supplements - dietary fibres - digestion - digestive tract - carbohydrates - microbial flora - nutrition physiology - animal nutrition - food chemistry - varkens - ratten - pectinen - voedersupplementen - voedingsvezels - spijsvertering - spijsverteringskanaal - koolhydraten - microbiële flora - voedingsfysiologie - diervoeding - voedselchemie

The physiological effects of dietary fiber (DFs) depend on several factors including structural features of the DFs, composition and activity of colonic microbiota, and products formed during fermentation. In this thesis, the influence of pectin supplementation to feed fermentation characteristics in rats and pigs was studied. The non-starch polysaccharides (NSP) present in the selected feed ingredient oats were characterized. Distinct populations of arabinoxylans (AXs) were observed in oats, compared to those reported for other cereals like wheat and barley. The fate of cereal AXs and soybean pectin during fermentation and the consequent effects on appetite regulation and fat accumulation were studied in rats as a model. Oat AXs were fermented less rapidly than wheat AXs in the caecum of rats. Soy pectin was fermented more early and efficiently than cereal AXs. A significant inverse correlation between rat retroperitoneal fat-pad weight and concentration and relative SCFA proportion of butyrate was observed. In a following in vivo rat experiment, commercial soy pectin together with three other soluble pectins originating from citrus and sugar beet and differing in their methyl esterification were individually supplemented to the diets. Their effects on the utilization of the different DFs present in the feed and the consequent effect on the microbial community in the colon of rats was studied. All pectins were fermented rapidly and consequently shifted fermentation of other consumed DFs (e.g. cereal AXs) to more distal part of colon, although low-methyl esterified pectin was more efficiently fermented by the microbiota than high-methyl esterified pectin. Results suggested that pectins can confer beneficial health effects through modulation of the gut microbiota. In a last in vivo experiment, citrus pectins together with a hydrothermal treated soybean meal were supplemented to pig diets to study their effect on the digestion and fermentation of carbohydrates in both the small and large intestine. Pectins, and more particularly low-methyl esterified pectin, decreased the ileal digestibility of digestible starch resulting in more starch to be fermentated in the proximal colon of pigs. Consequently, also the fermentation patterns of DFs and the microbiota composition was affected. All pectins tested shaped the colonic microbiota from a Lactobacillus-dominated microbiota to a Prevotella-dominated community, with potential health-promoting effects.

Mucus and gut barrier in health and disease
Sovran, B. - \ 2015
Wageningen University. Promotor(en): Jerry Wells; P. de Vos, co-promotor(en): J. Dekker. - Wageningen : Wageningen University - ISBN 9789462574892 - 233
slijm - spijsverteringskanaal - darmen - muizen - probiotica - eilandjes van peyer - colitis - transcriptomen - immunohistologie - veroudering - geslacht (sex) - homeostase - gezondheid - ziekten - mucus - digestive tract - intestines - mice - probiotics - peyer patches - colitis - transcriptomes - immunohistology - senescence - sex - homeostasis - health - diseases

This publication describes his work as a PhD student in the Host-Microbe Interactomics Chair group at Wageningen University within the Gastrointestinal Health theme. It has been completed under the supervision of Prof. Dr Jerry M Wells, Dr Jan Dekker and the TIFN project leader, Prof. Dr Paul de Vos.

Mucus serves as a protective layer between the intestinal content and the intestinal wall. It facilitates the passage of the luminal content through the intestine, reducing the risk of mechanical damage to the intestinal epithelium. The overarching goal of this thesis was to investigate the role of mucus in the maintenance of the intestinal immune barrier and the effects of ageing and gender differences on mucus production and the gut barrier.

We found by using a mouse model that decreased mucus production leads to changes in microbiota and mucosal stress responses, without the appearance of pathology, demonstrating the importance of mucus in intestinal homeostasis. The mucus barrier was shown to deteriorate during aging but this could be prevented with specific probiotics. Furthermore gender-specific differences in the effects of ageing on the mucosal barrier were found. Increased knowledge on these mechanisms might contribute significantly to disease prevention and treatment, for instance by optimizing gender-specific dietary and pharmacological requirements.

The study presented in this thesis was performed within the framework of Top Institute Food and Nutrition, within the GH002 project.

De beheersing van wormbesmettingen bij schapen op bedrijven in de praktijk : waardevolle inzichten uit een internetenquête
Ploeger, H. ; Antonis, A.F.G. ; Vellema, P. ; Verkaik, J. ; Bokma, M. - \ 2014
schapenhouderij - wormen - spijsverteringskanaal - haemonchus contortus - nematodirus - parasitosen - anthelmintica - sheep farming - helminths - digestive tract - parasitoses - anthelmintics
Passage of feed in dairy cows : use of stable isotopes to estimate passage kinetics through the digestive tract of dairy cows
Warner, D. - \ 2013
Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): Wilbert Pellikaan; Jan Dijkstra. - S.l. : s.n. - ISBN 9789461736833 - 163
melkkoeien - melkvee - voer - voedingsstoffen - spijsvertering - spijsverteringskanaal - kinetica - stabiele isotopen - verteerbaarheidsmerkers - rundveevoeding - diervoeding - voedingsfysiologie - dairy cows - dairy cattle - feeds - nutrients - digestion - digestive tract - kinetics - stable isotopes - digestibility markers - cattle feeding - animal nutrition - nutrition physiology

Dairy cows possess a unique digestive system to digest fibre-rich diets. Ingested feed is retained and degraded in the rumen by the enteric microbial population and is passed from the rumen to the following segments of the digestive tract. Passage of feed determines energy and protein supply to the animal and is a key parameter in several feed evaluation models for ruminants. Yet, quantitative data on passage of feed and particularly of single feed components are limited. Common techniques used to determine fractional passage rates of feed typically include indigestible markers that are not able to describe passage of distinct feed components. This thesis describes the use of stable isotope labelled feed components as a novel marker to determine feed type and feed component specific fractional passage rates. In a series of in vivoexperiments, fractional passage rates of a typical dairy ration, including grass silage, maize silage and concentrates, were determined. The use of carbon (13C) and nitrogen (15N) stable isotopes as an internal marker inherent to the diet allowed to specifically determine fractional passage rates of plant cell walls such as structural fibre, fibre-bound nitrogen, n-alkanes, and intracellular components such as starch and total nitrogen. For grass silage and maize silage, stable isotopes gave slower fractional rumen passage rates compared to the commonly used external marker chromium mordanted fibre; for concentrates, stable isotopes gave faster rates than the external marker. Among isotopic labelled fractions, 13C-labelled fibre and 15N-labelled fibre-bound nitrogen gave the slowest rates. The isotopic signature of single feed components and further application of stable isotopes on a wider range of feeds and feed components offers scope for the future for a more detailed insight into nutrient-specific passage kinetics. This will ultimately allow to quantify nutrient supply in response to changes in diet composition and quality, and model animal response in relation to optimal animal performance, environmental and animal-health issues.

Stress responses and digestive tract robustness of Lactobacillus plantarum
Bokhorst-van de Veen, H. van - \ 2013
Wageningen University. Promotor(en): Michiel Kleerebezem, co-promotor(en): P.A. Bron. - [S.l. : S.n. - ISBN 9789461736291 - 192
lactobacillus plantarum - stressreactie - spijsverteringskanaal - genregulatie - adaptatie - lactobacillus plantarum - stress response - digestive tract - gene regulation - adaptation

Lactobacillus plantarumis one of the most versatile lactic acid bacteria that can successfully inhabit a variety of environmental niches. It is a common inhabitant of the human and animal gastrointestinal (GI) tract and it is used as starter culture in various fermentation processes for different food raw-materials, including milk, fruits, vegetables, and meat. Moreover, L. plantarum is marketed as a health-promoting culture, i.e. a probiotic. In these different environments and processes the bacteria encounter stress conditions, such as heat, cold, acid, salt, and oxygen stress. Since starter cultures and probiotics require metabolic activity to contribute to the taste and texture of the fermented products, and/or viability to exert their in situ beneficial effect on the consumer, it is important to understand and improve the gene-regulatory adaptation that sustains their function and viability under these challenging conditions. Nowadays, genomic approaches are available that enable the global, genome-wide analysis of stress responses in lactic acid bacteria. The work presented in this thesis employs such tools and also developed some novel strategies to understand stress responses in L. plantarum.

During wine fermentation, L. plantarum is exposed to ethanol and global transcriptome profiling demonstrated the gene expression adaptation of this microorganism upon short and long term exposure to sublethal levels of this solvent. The results suggested that the ethanol induced activation of the CtsR-related stress regulon contributes to its adaptation to ethanol exposure which also provides cross-protection against heat stress. Transcriptome analyses under different growth conditions of gene deletion derivatives of the L. plantarum WCFS1 strain that lack the genes encoding the stress response regulators ctsR and/or hrcA, enabled the refinement of the gene regulation repertoire that is controlled by these central regulators of stress responses in this species. Notably, the deletion of both stress-regulators, elicited transcriptome changes that affected a large variety of additional gene-functions in a temperature-dependent manner, which prominently included genes related to cell-envelope remodelling.

Culturing of L. plantarum WCFS1 under different fermentation conditions led to large differences in GI-tract survival and robustness, which was addressed using a simple in vitro survival assay. Enhanced GI-tract survival and robustness could be associated with low salt and low pH conditions during the fermentations. The transcriptomes obtained for each of the fermentation conditions employed, were correlated with the observed GI-tract survival rates, enabling the identification of candidate genes involved in the robustness phenotype, including a transcription regulator involved in capsular polysaccharide remodelling (Lp_1669), a penicillin-binding protein (Pbp2A) involved in peptidoglycan biosynthesis, and a Na+/H+ antiporter (NapA3). A role of these candidate genes in actual survival in the GI-tract assay could be confirmed by mutation analysis, further confirming their contribution to GI-tract stress robustness in L. plantarum.

This thesis also describes the use of a novel, next-generation sequencing-based method, for the assessment of the in vivo GI-tract persistence of different L. plantarum strains that were administered to healthy human volunteers in specifically designed strain-mixtures. A remarkable consistency of the strain-specific in vivo persistence curves was observed when comparing data obtained from different volunteers. Moreover, a striking congruency was observed between the strain-specific in vivo persistence curves and the predicted GI-tract survival based on the simple in vitro assay. Finally, evolutionary adaptation of L. plantarum WCFS1 to the murine GI-tract was studied by extended exposure of the strain to the mice digestive tract through consecutive rounds of (re)feeding of the longest persisting bacterial colonies. Re-sequencing of the genomes of more persistent derivatives of the original strain, and the evaluation of the genomic modifications identified, implied that genes encoding cell envelope-associated functions and energy metabolism play an important role in the determination of GI-tract persistence in L. plantarum.

The results described in this thesis strive to obtain an improved understanding of the gene-regulatory adaptations of L. plantarum that allow its survival under stress conditions, including those associated with residence in the gastrointestinal tract of animals and humans, with the intention to exploit such understanding to rationally improve the robustness of these bacteria.

Digestion of dietary fat : gastrointestinal behaviour of emulsions and human physiological responses
Helbig, A. - \ 2013
Wageningen University. Promotor(en): Harry Gruppen; Rob Hamer, co-promotor(en): Erika Silletti. - S.l. : s.n. - ISBN 9789461735607 - 166
voedingsvet - spijsvertering - vetemulsies - spijsverteringskanaal - darmfysiologie - verzadigdheid - dietary fat - digestion - fat emulsions - digestive tract - intestinal physiology - satiety

Two in vitromodels were used to understand emulsion behavior and the subsequent formation of free fatty acids (FFA), monoglycerides (MG) and diglycerides (DG). Emulsions stabilized by whey protein isolate (WPI) or gum arabic (GA), varying in droplet size, were digested under intestinal conditions. Concentrations of FFA, MG and DG, assessed by gas chromatography, decreased with increasing droplet size. FFA release from gum arabic-stabilized emulsions was higher compared to WPI-stabilized emulsions showing an influence of the interface. Next, lipolysis of protein stabilized emulsions (i.e. WPI or lysozyme) and the influence of flocculation at the isoelectric point (pI) were investigated in a dynamic gastrointestinal model. The stomach properties including gradual acidification caused WPI-stabilized emulsions to cream during transition through the pI of the protein. This resulted in delayed intestinal lipolysis compared to the lysozyme-stabilized emulsion. Thus, since gastric passage affects emulsion behavior and intestinal lipolysis, the gastric passage should be part of digestion models. Next, in a human study emulsion behavior and resulting lipolytic products were related to the release of satiety hormones, satiety perception and ad libitumintake. Also, gallbladder volume and oral processing were studied. A delayed entry into the duodenum and lipolysis for the un-homogenized sample resulted in lower CCK, delayed GLP-1/PYY responses and barely gallbladder contraction compared to the homogenized emulsion. No difference was found between treatments on ghrelin, only the perception 'desire to eat´ was elevated for homogenized emulsions. Oral processing induced prolonged gallbladder contraction, but had no additive effect on other measures. A homogenous system as such is possibly not effective to induce pronounced satiety perceptions compared to phase separated or creamed systems using the same emulsifier. Moreover, the release of gastrointestinal hormones cannot directly be related to the satiating effect of food.

Effecten van voeding op darmgezondheid van leghennen = Effects of nutrition on intestinal health of laying hens
Veldkamp, T. ; Krimpen, M.M. van - \ 2012
Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 548) - 27
diergezondheid - pluimveevoeding - pluimveehouderij - hennen - spijsverteringskanaal - darmen - voersamenstelling - voedingsrantsoenen - voedertoevoegingen - biologische landbouw - dierenwelzijn - animal health - poultry feeding - poultry farming - hens - digestive tract - intestines - feed formulation - feed rations - feed additives - organic farming - animal welfare
Intestinal health is of vital importance for health and welfare of laying hens and nutrition may have a significant contribution. Insoluble non-starch polysaccharides (NSP) and feed additives such as herbs, phytogenic material, probiotics and prebiotics, organic acids and enzymes may have a beneficial effect on intestinal health.
Interactions of lactobacilli with the host immune system
Meijerink, M. - \ 2011
Wageningen University. Promotor(en): Jerry Wells; Huub Savelkoul, co-promotor(en): J. Bilsen. - [S.l.] : S.n. - ISBN 9789461730442 - 223
probiotica - immunomodulerende eigenschappen - lactobacillus plantarum - spijsverteringskanaal - voedselallergieën - vaccinatie - probiotics - immunomodulatory properties - lactobacillus plantarum - digestive tract - food allergies - vaccination

The aim of this thesis was to better understand the molecular mechanism of host res-ponses to probiotics. Probiotics can be used to stimulate or regulate immune responses in epithelial and immune cells of the intestinal mucosa and generate beneficial effects on the immune system. Carefully selected probiotics are able to steer the activity of the immune response in a predetermined manner by increasing or decreasing the activity of different aspects of the immune system (e.g. development and activity of T helper subsets). Beneficial effects of strains of probiotics have been established in the treatment and prevention of various intestinal disorders, including allergic diseases and diarrhea. However the precise molecular mechanisms and the strain dependent factors involved are poorly understood. Here in vitro molecular studies and in vivo mechanistic studies were combined in different mouse models to generate new insights into the beneficial mechanisms of selected lactobacilli and identify novel bacterial genes influencing the immune response. A further aim was to investigate the predictive value of in vitro immune assays for the effects of probiotics in vivo.

Chapter 1and chapter 2 describe the current knowledge and understanding of the immunomodulatory effects of different probiotic species and strains on mucosal immune system, dendritic cells (DCs) and the adaptive immune system. The relevance and the implications of in vitro studies for clinical trials or mechanistic research in animal mo-dels are discussed.

Chapter 3and chapter 4 present new insights gained from research on the strain-dependent factors involved in probiotic immune modulation. Extensive variation was observed in the immune responses to 42 L. plantarum strains. These results were used to identify genetic loci that correlated with levels of induced cytokines (such as IL-10 or IL-12) following co-culture with DCs (chapter 3) or peripheral blood mononuclear cells (PBMCs) (chapter 4). This in silico “gene-trait matching” approach led to the identification of several candidate genes in the L. plantarum genome that might modulate the immune cytokine response to L. plantarum. Selective gene deletions mutants were constructed for the candidate genes in L. plantarum WCFS1 and compared to the wild-type strain in immune assays with PBMCs and DCs. The predicted phenotype of the genetic knock-out was confirmed for most of the candidate loci including genes encoding an N-acetyl-glucosamine/galactosamine phosphotransferase system, the LamBDCA quorum sensing system, a predicted transcriptional regulator gene (lp_2991) and components of the plantaricin (bacteriocin) biosynthesis and transport pathway. Transcriptome analysis and qPCR data showed that transcript level of gtcA3, which is predicted to be involved in the glycosylation of cell wall teichoic acids, was substantially increased in the lp_2991 deletion mutant (44- and 29-fold respectively).

In vitroassays for pre-screening of candidate probiotics would benefit from standar-dized methods and cryopreservation techniques for immature DCs (iDCs) or precursor monocytes. Literature on the effects of cryopreservation and thawing of monocytes or monocyte-derived iDCs suggested that this strategy might be useful although bacteria had not been previously used as a stimulus. Thus in chapter 5 we investigated the effects of cryopreservation and thawing of precursor monocytes and iDCs on the maturation and immune response of DCs to potential probiotic strains and bacterial TLR agonists. Surface markers CD83 and CD86 were expressed at similar levels on iDCs generated from cryopreserved or freshly isolated monocytes. Cryopreservation of iDCs led to slightly decreased expression of CD86 and CD83 compared to freshly generated iDCs prepared from unfrozen cells but this did not affect the capacity of DCs to acquire fully mature characteristics after stimulation. In contrast the cytokine response to lipoteichoic acid and bacterial stimulation was altered by cryopreservation of monocytes or iDCs, particularly for IL-12 which was decreased up to 250 fold or even not detected at all. Cryopreservation also decreased TNF-α and IL-1β production in stimulated iDCs but to a lesser extent than for IL-12, depending on the maturation factors used. The amounts of IL-10 produced by stimulated iDCs were increased up to 3.6 fold when iDCs were cryopreserved, but decreased up to 90 fold when generated from cryopreserved monocytes. Immature DCs are often used to investigate the immunomodulatory properties of probiotics and here we showed for the first time that cryopreserved monocytes and cryopreserved iDCs have a skewed cytokine response to microbial stimulation. Therefore we consider that standardization of probiotic screening assays by the use of cryopreservation methods is currently not applicable. The detailed method for generating human monocyte derived DC described in chapter 5 may however be useful for developing standardized immune assays.

In chapter 6 we screened the immunomodulatory properties of 28 commercially available bacterial strains in vitro using human PBMCs and investigated selected strains for their in vivo immunomodulatory potential in an established mouse peanut allergy model. The 28 probiotic strains induced highly variable cytokine profiles in PBMCs. L. salivarius HMI001 (HMI001), L. casei Shirota (LCS) and L. plantarum WCFS1 (WCFS1) were selected for further investigation due to their distinct patterns of IL-10, IL-12 and IFN-γ induction. Prophylactic treatment with both HMI001 and LCS attenuated the Th2 phenotype in the mouse model (reduced mast cell responses and ex vivo IL-4 and/or IL-5 production). In contrast, WCFS1 augmented the Th2 phenotype (increased mast cell and antibody responses and ex vivo IL-4 production). In vitro PBMC screening was useful in selecting strains with anti-inflammatory and Th1 skewing properties. In the case of HMI001 (inducing a high IL-10/IL-12 ratio) and LCS (inducing high amounts of IFN-γ and IL-12) partial protection was seen in a mouse peanut allergy model. However, certain strains may worsen the allergic reaction as shown in the case of WCFS1. This approach indicated that pre-selection of candidate probiotics using in vitro immune assays is useful for selecting strains for translational research in humans.

Probiotics have been shown to increase the efficacy of different vaccines and can be easily consumed in food, and therefore probiotics might be useful in the improvement of current mucosal vaccines. In chapter 7 we have investigated the mechanisms behind the effect of lactobacilli on humoral responses to an intranasal vaccine. In addition to L. rhamnosus GG we selected 6 strains of Lactobacillus plantarum which have strikingly different immunomodulatory properties in vitro and TLR-2/6 activating properties. This selection was based on the approach outlined in chapter 3 and chapter 4 examining the in vitro immune responses of human monocyte derived DCs and PBMCs to 42 different L. plantarum strains. First we established an influenza vaccination model in Balb/c mice that would be sensitive to immunomodulation by lactobacilli, which allowed potential up- and down-regulation by the lactobacilli of the immune response. Strain WCFS1, that induced the lowest IL-10 to IL-12 cytokine ratio in DC co-culture significantly increased vaccine-specific antibody responses to the intranasal vaccine compared to the vaccine control group. Several Lactobacillus strains appeared to increase delayed-type hypersensitivity responses after vaccination compared to the vaccine control group indicating increased Th1-mediated vaccine responses. For strain LMG18021 this was also reflected in the significantly higher vaccine-specific IgG2a to IgG1 antibody ratio. LMG18021, CIP104448 and CIP104450 which have the highest IL-10 to IL-12 ratios of the strains tested, significantly enhanced the ex vivo vaccine-specific induction of IL-10, IL-17A, IL-6 and IL-4 in MLN cells. B1839 which was included as negative control, as it was a low cytokine inducer, did not enhance the vaccine-specific antibody or immune response indicating that the immune-stimulatory properties are important in mediating effects on the vaccine response. Further research is needed to demonstrate that these effects on the vaccine response impact on protection from influenza challenge and to validate the immunomodulatory mechanisms involved. Nevertheless, the in vivo studies described in this thesis support other publications proposing that in vitro immune assays can be useful for predicting which candidate probiotic strains will be most effective in vivo.

Chapter 8 completes this thesis with an overview of the most important findings of this thesis and discusses possible research limitations and future research perspectives. We stress the importance of proper strain selection using in vitro assays, and the use of strategies to identify novel immunomodulatory factors. The results described in this thesis support the rationale of using in vitro co-culture assays for selection of candidate probiotics for in vivo animal experiments or human trials.

Gastrointestinal-active oligosaccharides from human milk and functional foods
Albrecht, S.A. - \ 2011
Wageningen University. Promotor(en): Harry Gruppen; Fons Voragen, co-promotor(en): Henk Schols. - [S.l.] : S.n. - ISBN 9789085859871 - 200
oligosacchariden - moedermelk - spijsverteringskanaal - zuigelingen - borstvoeding - koolhydraatmetabolisme - oligosaccharides - human milk - digestive tract - infants - breast feeding - carbohydrate metabolism

Keywords: human milk oligosaccharides (HMOs), galacto-oligosaccharides (GOS), konjac glucomannan (KGM), breast milk, baby feces, gastrointestinal metabolization, blood-group specific conjugates, CE-LIF-MSn

Oligosaccharides, as present in human milk or supplemented to food, are renowned for their biological activity in the gastrointestinal tract. So far, little is known about the implication of oligosaccharide structures on their gastrointestinal fate. The influence of diet-related oligosaccharides on the postnatal gastrointestinal development and on the establishment of a balanced microflora is of special interest. Therefore, the present research aimed at an advanced understanding of the gastrointestinal metabolization of diet-related oligosaccharides, focusing on infant nutrition.

Capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) was introduced as a sensitive, qualitative and quantitative method for the analysis of individual galactooligosaccharides (GOS) from complex food matrices. The method also showed to be useful for the monitoring and characterization of complex konjac glucomannan (KGM) oligosaccharides, resulting from enzymatic digestion of the KGM polysaccharide andin vitro fermentation with human gut flora. The analysis and identification of human milk oligosaccharides (HMOs) in breast milk and the characterization of oligosaccharides as present in the feces of breast-, formula- and mixed-fed babies was performed by CE-LIF coupled to a mass spectrometer (CE-LIF-MSn). The type of feeding determines the presence of diet-related oligosaccharides in baby feces. For breast-fed babies a gradual change in fecal oligosaccharide profile was found during the first six months postpartum. Three continuous stages of fecal oligosaccharide profiles were defined, comprising the presence of the genetically determined HMO-profile of the breast milk consumed (stage 1), the presence of HMO-units conjugated to blood group determinants from gastrointestinal mucins (stage 2) and predominantly oligosaccharides characteristic for follow-up feeding when solid food is introduced (stage 3). In total, sixteen fecal oligosaccharides, which pointed to the degradation and gastrointestinal metabolization of diet-related oligosaccharides and which were not present in human milk or infant formula, were identified in this research.

Monitoring the gastrointestinal fate of diet-related oligosaccharides pointed to an individual-dependent gastrointestinal adaptation to enteral food during the postnatal period.

Managing the developing gut microbiota of growing piglets - novel probiotic and prebiotic strategies
Yao, W. - \ 2008
Wageningen University. Promotor(en): Martin Verstegen, co-promotor(en): Hauke Smidt; W.Y. Zhu. - [S.l.] : S.n. - ISBN 9789085048169 - 168
biggen - spenen - microbiële flora - darmen - spijsverteringskanaal - selectieve bijvoedering - probiotica - polymerase-kettingreactie - voedingsfysiologie - microbiota van het spijsverteringskanaal - prebiotica - piglets - weaning - microbial flora - intestines - digestive tract - creep feeding - probiotics - polymerase chain reaction - nutrition physiology - gastrointestinal microbiota - prebiotics
Keywords: creep feeding, weaning, intestinal microbiota, Lactobacillus sobrius, prebiotics, daidzein, probiotics, 16S rRNA, DGGE, cloning, real-time PCR
Nursing is a major critical period in the life of piglets. On one hand maternal antibodies are not able to cross the placenta, thus piglets are born without circulating antibodies and consequently lack maternal passive protection. On the other hand, creep-feeding and weaning increase susceptibility to gut disorders, infections and diarrhea. Therefore clarification of the composition and function of the normal gut microbiota of piglets is pivotal as a knowledge base for the design of innovative nutritional strategies based on pre- and probiotics to keep piglets healthy. The objectives of this study were to describe the composition and function of the intestinal microbiota of piglets during the nursing period through creep feeding and weaning, to in vivo and in vitro evaluate the effect of daidzein on composition and function of intestinal microbiota of nursing piglets in order to evaluate its prebiotic function, and to investigate the probiotic effect of Lactobacillus sobrius S1 on composition and function of intestinal microbiota of nursing piglets.
The porcine intestinal microbiota development and diversity, the in vivo and in vitro evaluation of prebiotic effect of daidzein and the investigation of probiotic effect of Lactobacillus sobrius S1 on composition and function of intestinal microbiota of piglets during nursing period through creep feeding and weaning was described using real-time PCR, and PCR analysis of 16S ribosomal RNA gene by denaturing gradient gel electrophoresis (DGGE) and cloning, in combination with analysis of gas production, lactate and VFA yield. The data obtained during the course of the study indicated that 1) Early creep-feeding stabilizes the microbiota of piglets around the weaning period. 2) Lactobacillus communities follow a successional change associated with piglet growth and diet shifting. Creep feeding stabilizes the Lactobacillus community of weaning piglets. Within the Lactobacillus community, some members like L. reuteri and L. amylovorus / L. sobrius might be permanent colonizers, while L. delbruckii, L. acidophilus and L. crispatus are more likely to be transient members of the Lactobacillus communities in the piglet´s GI tract. 3) Both in vitro and in vivo evaluations indicated that daidzein has the potential for use as a prebiotic additive in animal feed. 4) Lactobacillus sobrius S1 has the potential of promoting beneficial bacteria and inhibiting pathogens.
Intestinal health: Key to maximise growth performance in livestock
Verstegen, M.W.A. ; Beever, D.E. ; Collet, S. - \ 2007
Wageningen : Wageningen Academic Publishers - 300
vee - diergezondheid - darmen - spijsverteringskanaal - immuunsysteem - immuniteit - darmziekten - veevoeding - diervoeding - besmetters - eiwitexpressieanalyse - voedingsfysiologie - prestatieniveau - dierlijke productie - livestock - animal health - intestines - digestive tract - immune system - immunity - intestinal diseases - livestock feeding - animal nutrition - contaminants - proteomics - nutrition physiology - performance - animal production
Livestock production is changing worldwide. It is also the case that the ban on antibiotic growth promoters in Europe, the shift in animal production centres to Brazil or Eastern Europe, increase in demand for traceability and natural production, and the emergence of new diseases, are all forcing livestock producers to adapt new husbandry, management, nutrition and healthcare techniques. Food safety is an explosive political issue - the expectations and demands of the informed consumer have altered perceptions of risk and brought food safety to the very front and centre of politics. The changes in legislation on the use of feed additives will impact livestock production, location of production and feed formulation. Veterinarians and producers look for alternatives to maintain intestinal health and maximise animal performance, whilst still complying with stringent EU legislation. This book reviews the changes in livestock production and some of the clinical and sub-clinical disease challenges faced in pig, poultry or ruminant production. The book discusses bacterial challenges such as E.coli, Salmonella. Clostridia and Campylobacter, as well as viral diseases such as circovirus or avian influenza. One of the key elements in determining intestinal health is the use of molecular technologies in determining the composition of the intestinal microflora in poultry, pigs and ruminants. The interaction between innate, cellular and humoral immunity and the effects on antigen recognition and immune response will impact overall performance and ultimately the profit for producers. The understanding of Glycomics and the role of carbohydrates in cell-to-cell communication is crucial in overcoming sub-clinical challenges in modern livestock production. ISBN-13: 978-90-76998-91-6 Price (¿): 85.00 Price ($): 113.00 Publication date: 2007-12-01 (yyyy-mm-dd)
Wet and coarse diets in broiler nutrition: development of the GI tract and performance
Khoa, M.A. - \ 2007
Wageningen University. Promotor(en): Martin Verstegen, co-promotor(en): Thomas van der Poel; Rene Kwakkel. - [S.l.] : S.n. - ISBN 9789085046820 - 141
vleeskuikens - diëten - gevogeltevoeding - brijvoedering - vaste voeding - spijsverteringskanaal - biologische ontwikkeling - vleeskuikenresultaten - diervoeding - broilers - diets - fowl feeding - wet feeding - solid feeding - digestive tract - biological development - broiler performance - animal nutrition
Diet structure and conformation during the starter phase play an important role in the functional development of the gastro-intestinal (GI) tract of broiler chicken, in particular the foregut segment.\u00a0Feed structure has a significant effect on the development of the foregut segments in broiler chickens. The development of the gastro-intestinal tract in chickens is aimed to adapt and to develop in line with the body in order to meet animal's demands for production traits and it should avoid the GI tract malfunction and improper GI tract development. These can be done by changing (alternating) feed properties and in feeding strategies during the starter phase. Chicken's diet components may be treated in order to enable the crop, theproventriculus- gizzard system to function optimally. Thus they will optimize feed digestion and utilisation. Therefore, the focus of this thesis was: 1)Tounderstand the impact of changes in feed properties like technological treatments on broiler's performance. The technological changes in feed were made to induce differences in structure (particle sizes) and appearance (solid or liquid diets) of the feed and how this feed during the starter phase (0 - 3 weeks of age) influences the development and functioning of the foregut (crop andproventriculus); 2) To develop a feeding regime which optimizes foregut development and function of the foregut segment during starter phase and to see if there is a lasting effect on the following period, in other words, whether there is a carry over effect on performance of broilers during the grower phase. It has been shown that the starter period is critical for GI tract development. Feeding coarse diets during the starter phase improves the functional development of theproventriculus-gizzard system. Wet feeding improves feed intake and, as a consequence, broiler performance. Feeding a wet and coarsely ground diet provides a large improvement in feed intake, feed conversion and body weight gain, showing the most pronounced effects during the starter phase of broiler's life.
Gastrointestinal microbiology
Ouwehand, Arthur C. ; Vaughan, Elaine E. - \ 2006
CRC Press - ISBN 9780824726416 - 410 p.
intestinal microorganisms - digestive tract - microbial ecology

This reference supplies a comprehensive and current overview of every aspect of gastrointestinal microbiota. Expertly written chapters cover conventional and molecular techniques for the study of differing microbial populations, as well as the analysis of microbial activity and interaction with host bodies. Illustrative and up-to-date, this source showcases how fluctuations in our diet, environment, and pharmaceutical intake affect microbial composition and behavior.

A histological description of the alimentary tract and related organs of Adelgidae (Homoptera, Aphidoidea)
Ponsen, M.B. - \ 2006
Wageningen : Wageningen University (Wageningen Agricultural University papers 06-1 (2006)) - ISBN 9789057821745 - 103
adelgidae - spijsverteringskanaal - histologie - digestive tract - histology
Analyzing global gene expression of Lactobacillus plantarum in the human gastrointestinal tract
Vries, M.C. de - \ 2006
Wageningen University. Promotor(en): Willem de Vos. - Wageningen : - ISBN 9085043441 - 160
lactobacillus plantarum - genexpressie - spijsverteringskanaal - lactobacillus plantarum - gene expression - digestive tract
Gastrointestinal Health Benefits of Soy Water-soluble Carbohydrates in Young Broiler Chickens
Lan, Y. - \ 2004
Wageningen University. Promotor(en): Martin Verstegen; Seerp Tamminga; G. Erdi, co-promotor(en): B.A. Williams. - [S.I.] : S.n. - ISBN 9064649243 - 265
vleeskuikens - pluimvee - koolhydraten - sojabonen - spijsverteringsstelsel - spijsverteringskanaal - diergezondheid - fermentatie - kinetica - darmen - morfologie - blindedarm - melkzuurbacteriën - immunoglobulinen - voedselbeperking - pluimveevoeding - diervoeding - broilers - poultry - carbohydrates - soyabeans - digestive system - digestive tract - animal health - fermentation - kinetics - intestines - morphology - caecum - lactic acid bacteria - immunoglobulins - food restriction - poultry feeding - animal nutrition
Passage of 13C-labelled feed components through the digestive tract of dairy cows
Pellikaan, W.F. - \ 2004
Wageningen University. Promotor(en): Seerp Tamminga, co-promotor(en): Jan Dijkstra; H. Boer. - [S.I.] : S.n. - ISBN 9085040752 - 188
melkkoeien - melkvee - voer - spijsverteringskanaal - isotopenlabelling - merkers - grassen - graskuilvoer - voederwaardering - voedingsfysiologie - dairy cows - dairy cattle - feeds - digestive tract - isotope labeling - markers - grasses - grass silage - feed evaluation - nutrition physiology
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