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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    Beyond heat stress: Intestinal integrity disruption and mechanism-based intervention strategies
    Lian, Puqiao ; Braber, Saskia ; Garssen, Johan ; Wichers, Harry J. ; Folkerts, Gert ; Fink-Gremmels, Johanna ; Varasteh, Soheil - \ 2020
    Nutrients 12 (2020)3. - ISSN 2072-6643
    Heat stress (HS) - Intestinal integrity - Nutritional supplements - Reactive oxygen species (ROS) - Resilience pathways

    The current climate changes have increased the prevalence and intensity of heat stress (HS) conditions. One of the initial consequences of HS is the impairment of the intestinal epithelial barrier integrity due to hyperthermia and hypoxia following blood repartition, which often results in a leaky gut followed by penetration and transfer of luminal antigens, endotoxins, and pathogenic bacteria. Under extreme conditions, HS may culminate in the onset of “heat stroke”, a potential lethal condition if remaining untreated. HS-induced alterations of the gastrointestinal epithelium, which is associated with a leaky gut, are due to cellular oxidative stress, disruption of intestinal integrity, and increased production of pro-inflammatory cytokines. This review summarizes the possible resilience mechanisms based on in vitro and in vivo data and the potential interventions with a group of nutritional supplements, which may increase the resilience to HS-induced intestinal integrity disruption and maintain intestinal homeostasis.

    Fungal artillery of zombie flies: infectious spore dispersal using a soft water cannon
    Ruiter, Jolet de; Arnbjerg-Nielsen, Sif Fink ; Herren, Pascal ; Høier, Freja ; Fine Licht, Henrik H. De; Jensen, Kaare H. - \ 2019
    Journal of the Royal Society, Interface 16 (2019)159. - ISSN 1742-5689 - 10 p.
    biomimetic soft cannon - dispersal range - Entomophthora muscae - force-balance model - fungal spore ejection - high-speed videography

    Dead sporulating female fly cadavers infected by the house fly-pathogenic fungus Entomophthora muscae are attractive to healthy male flies, which by their physical inspection may mechanically trigger spore release and by their movement create whirlwind airflows that covers them in infectious conidia. The fungal artillery of E. muscae protrudes outward from the fly cadaver, and consists of a plethora of micrometric stalks that each uses a liquid-based turgor pressure build-up to eject a jet of protoplasm and the initially attached spore. The biophysical processes that regulate the release and range of spores, however, are unknown. To study the physics of ejection, we design a biomimetic 'soft cannon' that consists of a millimetric elastomeric barrel filled with fluid and plugged with a projectile. We precisely control the maximum pressure leading up to the ejection, and study the cannon efficiency as a function of its geometry and wall elasticity. In particular, we predict that ejection velocity decreases with spore size. The calculated flight trajectories under aerodynamic drag predict that the minimum spore size required to traverse a quiescent layer of a few millimetres around the fly cadaver is approximately 10 µm. This corroborates with the natural size of E. muscae conidia (approx. 27 µm) being large enough to traverse the boundary layer but small enough (less than 40 µm) to be lifted by air currents. Based on this understanding, we show how the fungal spores are able to reach a new host.

    Modeling phosphorus in rivers at the global scale : recent successes, remaining challenges, and near-term opportunities
    Harrison, John A. ; Beusen, Arthur H.W. ; Fink, Gabriel ; Tang, Ting ; Strokal, Maryna ; Bouwman, Alexander F. ; Metson, Geneviève S. ; Vilmin, Lauriane - \ 2019
    Current Opinion in Environmental Sustainability 36 (2019). - ISSN 1877-3435 - p. 68 - 77.

    Understanding and mitigating the effects of phosphorus (P) overenrichment of waters globally, including the evaluation of the global Sustainability Development Goals, requires the use of global models. Such models quantitatively link land use, global population growth and climate to aquatic nutrient loading and biogeochemical cycling. Here we describe, compare, and contrast the existing global models capable of predicting P transport by rivers at a global scale. We highlight important insights gained from the development and application of these models, and identify important near-term opportunities for model improvements as well as additional insight to be gained through new model analysis.

    Strategies for optimal fertiliser management of vegetable crops in Europe
    Thompson, R.B. ; Voogt, W. ; Incrocci, L. ; Fink, M. ; Neve, S. de - \ 2018
    In: 5th International Symposium on Ecologically Sound Fertilization Strategies for Field Vegetable Production. - International Society for Horticultural Science (Acta Horticulturae ) - ISBN 9789462611887 - p. 129 - 140.
    Crop monitoring - Decision support systems - Simulation models - Soil analysis
    In Europe a number of procedures are used to assist growers and advisors to determine optimal N fertiliser recommendations. The implementation of European Union (EU) legislation is encouraging the adoption of fertiliser recommendation schemes. The most widely used schemes are those based on soil testing or on the use of indices that estimate the soil nitrogen supply. Soil testing approaches that are in use, particularly in NW Europe are the Nmin, KNS and N-Expert systems; the latter is operated as a computer-based decision support system (DSS). The comprehensive RB209 Fertiliser Manual of England and Wales uses soil N supply indices, but soil analysis can also be used. Nitrogen balance calculations are widely used throughout Europe and form part of the KNS and N-Expert systems, and a number of other DSSs. The N balance considers the various soil N sources and treats mineral N fertiliser as a supplemental N source. The EU-Rotate_N simulation model is a comprehensive and versatile tool, developed for diverse European conditions, that is useful for scenario analysis simulations to stakeholders. Various DSS have been developed in different European countries, with different levels of complexity. There are a number of different DSS that calculate N fertiliser recommendations for particular cropping systems; some DSS calculate the requirements for other nutrients, and some also do so for irrigation which is particularly useful where fertigation is used. Sap analysis has been shown to be sensitive to crop nutrient status, for N and some other nutrients; currently, there is renewed interest in sap analysis. Proximal optical sensors are a promising approach for N management.
    An overview of the diurnal cycle of the atmospheric boundary layer during the West African monsoon season : Results from the 2016 observational campaign
    Kalthoff, Norbert ; Lohou, Fabienne ; Brooks, Barbara ; Jegede, Gbenga ; Adler, Bianca ; Babić, Karmen ; DIone, Cheikh ; Ajao, Adewale ; Amekudzi, Leonard K. ; Aryee, Jeffrey N.A. ; Ayoola, Muritala ; Bessardon, Geoffrey ; Danuor, Sylvester K. ; Handwerker, Jan ; Kohler, Martin ; Lothon, Marie ; Pedruzo-Bagazgoitia, Xabier ; Smith, Victoria ; Sunmonu, Lukman ; Wieser, Andreas ; Fink, Andreas H. ; Knippertz, Peter - \ 2018
    Atmospheric Chemistry and Physics 18 (2018)4. - ISSN 1680-7316 - p. 2913 - 2928.
    A ground-based field campaign was conducted in southern West Africa from mid-June to the end of July 2016 within the framework of the Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) project. It aimed to provide a high-quality comprehensive data set for process studies, in particular of interactions between low-level clouds (LLCs) and boundary-layer conditions. In this region missing observations are still a major issue. During the campaign, extensive remote sensing and in situ measurements were conducted at three supersites: Kumasi (Ghana), Savè (Benin) and Ile-Ife (Nigeria). Daily radiosoundings were performed at 06:00 UTC, and 15 intensive observation periods (IOPs) were performed during which additional radiosondes were launched, and remotely piloted aerial systems were operated. Extended stratiform LLCs form frequently in southern West Africa during the nighttime and persist long into the following day. They affect the radiation budget and hence the evolution of the atmospheric boundary layer and regional climate. The relevant parameters and processes governing the formation and dissolution of the LLCs are still not fully understood. This paper gives an overview of the diurnal cycles of the energy-balance components, near-surface temperature, humidity, wind speed and direction as well as of the conditions (LLCs, low-level jet) in the boundary layer at the supersites and relates them to synoptic-scale conditions (monsoon layer, harmattan layer, African easterly jet, tropospheric stratification) in the DACCIWA operational area. The characteristics of LLCs vary considerably from day to day, including a few almost cloud-free nights. During cloudy nights we found large differences in the LLCs' formation and dissolution times as well as in the cloud-base height. The differences exist at individual sites and also between the sites. The synoptic conditions are characterized by a monsoon layer with south-westerly winds, on average about 1.9 km deep, and easterly winds above; the depth and strength of the monsoon flow show great day-to-day variability. Within the monsoon layer, a nocturnal low-level jet forms in approximately the same layer as the LLC. Its strength and duration is highly variable from night to night. This unique data set will allow us to test some new hypotheses about the processes involved in the development of LLCs and their interaction with the boundary layer and can also be used for model evaluation.
    Hydrological and Agricultural Impacts of Climate Change in the Vu Gia-Thu Bon River Basin in Central Vietnam
    Laux, Patrick ; Fink, Manfred ; Waongo, Moussa ; Pedroso, Rui ; Salvini, G. ; Hoa Tran, Dang ; Quang Thinh, Dang ; Cullmann, Johannes ; Flügel, Wolfgang-Alvert ; Kunstmann, H. - \ 2017
    In: Land Use and Climate Change Interactions in Central Vietnam / Nauditt, A., Ribbe, L., Singapore : Springer Science (Water Resources Development and Management ) - ISBN 9789811026232 - p. 123 - 142.

    This paper summarizes some of the climate (change) impact modeling activities conducted in the Land useandClimate Changeinteractionsin Central Vietnam (LUCCi)project. The study area is the Vu Gia-Thu Bon (VGTB) river basin in Central Vietnam, which is characterized by recurrent floods during the rainy season, but also water shortages during the dry season. The impact modeling activities, such as the validation of the models are hindered by the scarcity of hydrometeorological data and an unfavorable distribution of the observation network, i.e., station data is available only for the lowlands. In total, two different process-based and distributed hydrological models are applied in concert with climate change and land use projections. Based on that, the magnitudes and return periods of extreme flows are estimated. The modeling results suggest increases of extreme high flows due to climate change. A multi-objective agro-economical model was developed for a typical irrigation scheme in the region in order to optimize the area for cropping, irrigation-techniques and schedules. The model results suggest the irrigation technique Alternate Wetting and Drying, which has the potential to increase the benefits for the farmers and help to mitigate greenhouse gases at the same time. In addition, the regional-scale crop model GLAM is applied for groundnut under rainfed conditions, which is capable to identify regions suitable for cropping in the future. The paper further synthesizes recommendations for local stakeholders in Central Vietnam.

    Innate immunity of carp : fishing for receptors
    Fink, Inge - \ 2017
    Wageningen University. Promotor(en): Geert Wiegertjes; Huub Savelkoul, co-promotor(en): Maria Forlenza. - Wageningen : Wageningen University - ISBN 9789463430753 - 240
    carp - cyprinus - immunity - platelets - macrophage activation - receptors - polarization - immunostimulation - immunology - karper - cyprinus - immuniteit - bloedplaatjes - macrofaag activering - receptoren - polarisatie - immunostimulatie - immunologie

    Recent decades have seen a significant intensification of aquaculture leading to increased risk of infections with several pathogenic organisms. On economical and ethical grounds it is more appropriate to improve general welfare conditions and prevent infections rather than treating disease outbreaks once they have occurred. Immunostimulation through feed can provide more efficient and sustainable control of diseases in aquaculture through enhancing the immunocompetence of fish; however, the underlying mechanisms are poorly characterized. The overall aim of this thesis was to perform a molecular and functional characterization of how pathogen-associated molecular patterns (PAMPs), such as β-glucans, affect the innate immune response of carp and which receptors on carp leukocytes are likely candidates to play a role in sensing such PAMPs.

    In chapter 1 we provide a framework for this thesis by introducing different classes of PAMPs, including β-glucans. These molecules were the centrepiece of an intra-European training network called NEMO (Protective immune modulation in warm water fish by feeding glucans), which this PhD project was part of. The scientific aim of the NEMO network was to develop a sustainable and cost-effective use of β-glucans as immunostimulants for aquaculture, using common carp as the model fish species, since on a global scale common carp is the most cultured fish species for food consumption. Our aims within the NEMO project entailed both the characterization of carp leukocytes and the characterization of candidate pattern recognition receptors (PRRs) that could play a role in sensing PAMPs and initiating immune responses. Chapter 1 therefore introduces the thrombocytes and macrophages pertinent to this thesis, as well as important classes of PRRs.

    In our first experimental study, described in chapter 2, we investigated the relevance of thrombocytes for the immune system of carp. We found that thrombocytes from healthy carp express a large number of immune-relevant genes, among which several cytokines and Toll-like receptors (Tlrs). Furthermore, we dissected the role of thrombocytes during infections with two different, albeit related, protozoan parasites, Trypanoplasma borreli and Trypanosoma carassii, and found thrombocytes were massively depleted from blood and spleen of fish infected with T. borreli. The pathology of this infection is associated with elevated levels of tissue nitration, prompting us to investigate, ex vivo, the effect of nitric oxide on thrombocytes. Our studies revealed that nitric oxide can induce a clear and rapid apoptosis of thrombocytes from healthy carp, supporting a role for nitric oxide-mediated control of immune-relevant thrombocytes during infection with T. borreli. Thereby, this particular study provided an excellent example of interplay between pathogen and the innate immune system of carp.

    We reviewed in chapter 3 another cell type central to innate immunity: the macrophage. We focused on the heterogeneity of macrophage activation states as these cells, at least in humans and mice, have the ability to polarize in several directions during an immune response. Based on the signals that lead to activation and the effector functions and cytokine profile as a result thereof, macrophages can be broadly divided into two types: classically activated macrophages induced in a T helper 1 (TH1) cytokine environment, and alternatively activated macrophages, induced in a TH2 cytokine environment. Mirroring the TH1–TH2 dichotomy, classically activated macrophages have also been termed M1, whereas alternatively activated macrophages have been termed M2. Classically activated macrophages are typically induced by stimulation with microbial ligands such as LPS in combination with pro-inflammatory cytokines such as IFNγ, and can be viewed as an extension of innate activated macrophages which are induced by microbial ligands only, thus are independent of cytokines. Alternatively activated macrophages are generated in the presence of IL4 and/or IL13. In addition to M1 and M2, one can distinguish regulatory macrophages, which are associated with the presence of the cytokine IL10. In this chapter, we reviewed the evidence of existence of polarized macrophages in teleost fish, among other things based on observations of the fundamentally different immune responses elicited by the parasites T. borreli and T. carassii.

    We further investigated the polarization of carp macrophages in chapter 4, where we obtained gene signature profiles of carp macrophages via a transcriptome approach. Independently of cytokines, carp macrophages showed the ability to differentiate into cells with functional characteristics highly comparable to those of mammalian M1 and M2, consistent with a conserved ability of macrophages to polarize into distinct subsets. In addition to obtaining a global view of gene expression, our transcriptome approach identified gene signatures for M1 and M2 macrophages which appear conserved from fish to mammals. We selected a number of these interesting genes that were differentially regulated between M1 and M2 macrophages and discussed in detail five potential M1 markers; il1β, ptx3a, saa, nos2b, and il12a – as well as five potential M2 markers; cyr61, inhba, timp2, tgm2, and arg2. These transcriptome studies may pave the way for future studies of polarized macrophages during immune responses in fish. Furthermore, additional analyses of the datasets described in this chapter will undoubtedly lead to the characterization of more genes relevant to macrophage polarization and recognition of immunostimulants.

    As part of the characterization of candidate PRRs that could play a role in sensing PAMPs and initiating immune responses, we studied the scavenger receptor Cd36 (chapter 5), which in mammals is expressed by many different (immune) cell types and plays a role in highly diverse processes, both homeostatic and pathologic. Among other things, it is often found associated with sensing of β-glucans and also with M2 macrophage activation, sparking our interest in this molecule in fish. We studied Cd36 in common carp as well as in zebrafish, a closely related cyprinid fish species. Whereas a single cd36 gene is present in zebrafish, carp was shown to have two paralogs of cd36. Although all genes show conserved synteny compared to mammalian CD36, unexpectedly we could not detect gene expression of cyprinid cd36 in macrophages or any other immune cell type or immune organ. Yet, because gene expression of cd36 was down-regulated during Mycobacterium marinum infection of zebrafish, and knockdown of cd36 in zebrafish embryos led to higher bacterial burden upon such infection, our data imply a role for Cd36 in immune responses of fish. Future studies are needed to clarify the exact mechanisms involved.

    As characterization of candidate PRRs we also examined the Toll-like receptors Tlr1 and Tlr2 (chapter 6). We identified a full-length, expressed tlr1 gene, a tlr1 pseudogene, and a second tlr2 gene next to the tlr2 which had been described previously. Sequence, phylogenetic and synteny analyses supported the conserved nature of these genes, and three-dimensional modelling showed a good fit with the mammalian TLR1/TLR2 heterodimer including the potential to bind to the prototypical ligand Pam3CSK4. However, we were unable to demonstrate Tlr1/Tlr2-mediated ligand binding in transfected cell lines through NFκB activation, despite showing the expression and co-localization of Tlr1 and Tlr2. This prompted a discussion of methods available for studying ligand-binding properties of fish Tlrs.

    Finally, we discuss in chapter 7 the findings of this thesis in the context of the NEMO project. We present the concept of trained immunity, which could provide the conceptual framework within which the immune-stimulating ability of compounds such as β-glucans could be explained. We discuss recent advances in the field of TLR research as well as that of macrophage polarization, and highlight immunometabolism as a new area of interest which may help to illuminate the molecular events occurring in immune cells during health and disease. In conclusion, we found that carp leukocytes, along with their pattern recognition receptors, are central players of the innate immune system of carp. Our findings contribute to the understanding of mechanisms of immunostimulation, and expect this will enable the valorisation and use of immunostimulants for sustainable aquaculture and improvement of fish health.

    Characterizing microbiota-independent effects of oligosaccharides on intestinal epithelial cells : insight into the role of structure and size: Structure–activity relationships of non-digestible oligosaccharides
    Akbari, Peyman ; Fink-Gremmels, Johanna ; Willems, Rianne H.A.M. ; Difilippo, Elisabetta ; Schols, Henk A. ; Schoterman, Margriet H.C. ; Garssen, Johan ; Braber, Saskia - \ 2017
    European Journal of Nutrition 56 (2017)5. - ISSN 1436-6207 - p. 1919 - 1930.
    Caco-2 cells - CXCL8 - Degree of polymerization - Intestinal permeability - Non-digestible oligosaccharides - Tight junctions
    Purpose: The direct effects of galacto-oligosaccharides (GOS), including Vivinal® GOS syrup (VGOS) and purified Vivinal® GOS (PGOS), on the epithelial integrity and corresponding interleukin-8 (IL-8/CXCL8) release were examined in a Caco-2 cell model for intestinal barrier dysfunction. To investigate structure–activity relationships, the effects of individual DP fractions of VGOS were evaluated. Moreover, the obtained results with GOS were compared with Caco-2 monolayers incubated with fructo-oligosaccharides (FOS) and inulin. Methods: Caco-2 monolayers were pretreated (24 h) with or without specific oligosaccharides or DP fractions of VGOS (DP2 to DP6) before being exposed for 12 or 24 h to the fungal toxin deoxynivalenol (DON). Transepithelial electrical resistance and lucifer yellow permeability were measured to investigate barrier integrity. A calcium switch assay was used to study the reassembly of tight junction proteins. Release of CXCL8, a typical marker for inflammation, was quantified by ELISA. Results: In comparison with PGOS, FOS and inulin, VGOS showed the most pronounced protective effect on the DON-induced impairment of the monolayer integrity, acceleration of the tight junction reassembly and the subsequent CXCL8 release. DP2 and DP3 in concentrations occurring in VGOS prevented the DON-induced epithelial barrier disruption, which could be related to their high prevalence in VGOS. However, no effects of the separate DP GOS fractions were observed on CXCL8 release. Conclusions: This comparative study demonstrates the direct, microbiota-independent effects of oligosaccharides on the intestinal barrier function and shows the differences between individual galacto- and fructo-oligosaccharides. This microbiota-independent effect of oligosaccharides depends on the oligosaccharide structure, DP length and concentration.
    Facing the challenge of a functional characterization of toll-like receptor (TLR)1 and TLR2 in common carp
    Fink, I.R. ; Forlenza, M. ; Pietretti, D. ; Wiegertjes, G. - \ 2016
    - p. 76 - 76.
    Carp, TLR1, TLR2, sub-cellular localizatioan, ligand binding
    Fish & Shellfish Immunology Special Issue ISFSI 2016
    Conservation of macrophage polarization in fish
    Wentzel, A.S. ; Petit, J. ; Fink, I.R. ; Forlenza, M. ; Wiegertjes, G. - \ 2016
    - p. 54 - 54.
    Macrophages of higher vertebrates can express a range of activation states, with the extremes termed M1 and M2. Neither the evolutionary conservation of these activation states, nor the exact microbial and/or cytokine stimulants involved, have been examined in detail in lower vertebrates. We have shown that macrophages of teleost fish, including carp, have the ability to polarize into activation states typical of classical (M1) and alternative (M2) extremes upon stimulation with LPS, or exogenous cAMP, respectively. Upon this polarization, carp macrophages display functional profiles and several molecular markers that indicate the M1-M2 dichotomy could be an intrinsic property of macrophages which arose early in evolution. Owing to the more recent discoveries of IFN-y and lL-4/IL-13-like cytokines in teleost fish, we now can also study cytokine-dependent polarization of carp macrophages. Interferon-y amplifies LPS-induced polarisation into M1-like profiles of carp macrophages, including the induction of nitric oxide. Strikingly, IL-4/IL-13 appears to increase levels of arginase along with an activation profile that at least partly overlaps with that of cAMP-induced M2 macrophages. Thus, the chief macrophage M1 and M2 activation states appear to operate under the guidance of primordially conserved principles.
    Molecular and functional characterization of Toll-like receptor (Tlr)1 and Tlr2 in common carp (Cyprinus carpio)
    Fink, Inge R. ; Pietretti, Danilo ; Voogdt, Carlos G.P. ; Westphal, Adrie H. ; Savelkoul, Huub F.J. ; Forlenza, Maria ; Wiegertjes, Geert F. - \ 2016
    Fish and Shellfish Immunology 56 (2016). - ISSN 1050-4648 - p. 70 - 83.
    Heterodimer - Innate immunity - Teleost - TLR signalling - Toll-like receptor

    Toll-like receptors (TLRs) are fundamental components of innate immunity that play significant roles in the defence against pathogen invasion. In this study, we present the molecular characterization of the full-length coding sequence of tlr1, tlr2a and tlr2b from common carp (Cyprinus carpio). Each is encoded within a single exon and contains a conserved number of leucine-rich repeats, a transmembrane region and an intracellular TIR domain for signalling. Indeed, sequence, phylogenetic and synteny analysis of carp tlr1, tlr2a and tlr2b support that these genes are orthologues of mammalian TLR1 and TLR2. The tlr genes are expressed in various immune organs and cell types. Furthermore, the carp sequences exhibited a good three-dimensional fit with the heterodimer structure of human TLR1-TLR2, including the potential to bind to the ligand Pam3CSK4. This supports the possible formation of carp Tlr1-Tlr2 heterodimers. However, we were unable to demonstrate Tlr1/Tlr2-mediated ligand binding in transfected cell lines through NF-κB activation, despite showing the expression and co-localization of Tlr1 and Tlr2. We discuss possible limitations when studying ligand-specific activation of NF-κB after expression of Tlr1 and/or Tlr2 in human but also fish cell lines and we propose alternative future strategies for studying ligand-binding properties of fish Tlrs.

    Milk Oligosaccharide Variation in Sow Milk and Milk Oligosaccharide Fermentation in Piglet Intestine
    Difilippo, Elisabetta ; Pan, Feipeng ; Logtenberg, Madelon ; Willems, Rianne ; Braber, Saskia ; Fink-Gremmels, Johanna ; Schols, Henk Arie ; Gruppen, Harry - \ 2016
    Journal of Agricultural and Food Chemistry 64 (2016)10. - ISSN 0021-8561 - p. 2087 - 2093.
    abundance - chromatography - cow - mass analysis - pigs - sugars - variation

    Porcine milk oligosaccharides (PMOs) were analyzed in six colostrum and two mature milk samples from Dutch Landrace sows. In total, 35 PMOs were recognized of which 13 were new for the PMO literature: Neutral HexNAc-Hex, β4′-galactosyllactose, putative GalNAc(α/β1-3)Gal(β1-4)Glc, lacto-N-fucopentaose-II, lacto-N-tetraose, galactose substituted lacto-N-neohexaose, lacto-N-hexaose and difucosyl-lacto-N-hexaose, and acidic Neu5Ac(α2-6)GlcNAc(β1-3)Gal(β1-4)Glc, sialyllacto-N-tetraose-a and -b, Neu5Ac2-Hex3, and sialyllacto-N-fucopentaose-II. PMOs were analyzed using capillary electrophoresis with laser-induced florescence detection or mass spectrometry and using liquid chromatography with mass spectrometry. Interindividual variation regarding PMO presence and concentration was observed between porcine milks. Within a limited sample set, a 43% decrease of the major PMOs was found during a 1 w lactation period. Interestingly, while some PMOs decreased, some other PMOs increased in concentration. PMOs were also monitored in fecal samples of suckling piglets. In feces of 1-2 d old piglets, few intact PMOs were found, indicating considerable PMO fermentation at early stage of life.

    In Vitro Fermentation of Porcine Milk Oligosaccharides and Galacto-oligosaccharides Using Piglet Fecal Inoculum
    Difilippo, Elisabetta ; Pan, Feipeng ; Logtenberg, Madelon ; Willems, Rianne ; Braber, Saskia ; Fink-Gremmels, Johanna ; Schols, Henk A. ; Gruppen, Harry - \ 2016
    Journal of Agricultural and Food Chemistry 64 (2016)10. - ISSN 0021-8561 - p. 2127 - 2133.
    fibers - gas chromatography - human fermentation - liquid chromatography - nondigestible carbohydrates - organic acids - short-chain fatty acids - sugars

    In this study, the in vitro fermentation by piglet fecal inoculum of galacto-oligosaccharides (GOS) and porcine milk oligosaccharides (PMOs) was investigated to identify possible preferences for individual oligosaccharide structures by piglet microbiota. First, acidic PMOs and GOS with degrees of polymerization 4-7 were depleted within 12 h of fermentation, whereas fucosylated and phosphorylated PMOs were partially resistant to fermentation. GOS structures containing β1-3 and β1-2 linkages were preferably fermented over GOS containing β1-4 and β1-6 linkages. Upon in vitro fermentation, acetate and butyrate were produced as the main organic acids. GOS fermentation by piglet inoculum showed a unique fermentation pattern with respect to preference of GOS size and organic acids production.

    The piglet as a model for studying dietary components in infant diets : effects of galacto-oligosaccharides on intestinal functions
    Alizadeh, A. ; Akbari, P. ; Difilippo, E. ; Schols, H.A. ; Ulfman, L.H. ; Schoterman, M.H.C. ; Garssen, J. ; Fink-Gremmels, J. ; Braber, S. - \ 2016
    The British journal of nutrition 115 (2016)4. - ISSN 0007-1145 - p. 605 - 618.
    Galacto-oligosaccharides - Gut microbiota - Immunomodulation - Intestinal integrity - Neonatal piglet models

    Prebiotic oligosaccharides, including galacto-oligosaccharides (GOS), are used in infant formula to mimic human milk oligosaccharides, which are known to have an important role in the development of the intestinal microbiota and the immune system in neonates. The maturation of the intestines in piglets closely resembles that of human neonates and infants. Hence, a neonatal piglet model was used to study the multi-faceted effect of dietary GOS in early life. Naturally farrowed piglets were separated from the mother sow 24–48 h postpartum and received a milk replacer with or without the addition of GOS for 3 or 26 d, whereafter several indicators of intestinal colonisation and maturation were measured. Dietary GOS was readily fermented in the colon, leading to a decreased pH, an increase in butyric acid in caecum digesta and an increase in lactobacilli and bifidobacteria numbers at day 26. Histomorphological changes were observed in the intestines of piglets fed a GOS diet for 3 or 26 d. In turn, differences in the intestinal disaccharidase activity were observed between control and GOS-fed piglets. The mRNA expression of various tight junction proteins was up-regulated in the intestines of piglet fed a GOS diet and was not accompanied by an increase in protein expression. GOS also increased defensin porcine β-defensin-2 in the colon and secretory IgA levels in saliva. In conclusion, by applying a neonatal piglet model, it could be demonstrated that a GOS-supplemented milk replacer promotes the balance of the developing intestinal microbiota, improves the intestinal architecture and seems to stimulate the intestinal defence mechanism.

    Polarization of immune responses in fish : The 'macrophages first' point of view
    Wiegertjes, Geert F. ; Wentzel, Annelieke S. ; Spaink, Herman P. ; Elks, Philip M. ; Fink, Inge R. - \ 2016
    Molecular Immunology 69 (2016). - ISSN 0161-5890 - p. 146 - 156.
    Arginase - Fish - INOS - LPS - Macrophage polarization - Zebrafish

    In this review, we support taking polarized immune responses in teleost fish from a 'macrophage first' point of view, a hypothesis that reverts the dichotomous T helper (TH)1 and TH2 driving forces by building on the idea of conservation of innate immune responses in lower vertebrates. It is plausible that the initial trigger for macrophage polarization into M1 (inflammation) or M2 (healing) could rely only on sensing microbial/parasite infection or other innate danger signals, without the influence of adaptive immunity. Given the long and ongoing debate on the presence/absence of a typical TH1 cytokine environment and, in particular, TH2 cytokine environment in fish immune responses, it stands out that the presence of macrophages with polarized phenotypes, alike M1 and M2, have been relatively easy to demonstrate for fish. We summarize in short present knowledge in teleost fish on those cytokines considered most critical to the dichotomous development of TH1/M1 and TH2/M2 polarization, in particular, but not exclusively, interferon-γ and interleukin (IL)-4/IL-13. We review, in more detail, polarization of fish immune responses taken from the macrophage point of view for which we adopted the simple nomenclature of M1 and M2. We discuss inducible nitric oxide synthase, or NOS-2, as a reliable M1 marker and arginase-2 as a reliable M2 marker for teleost fish and discuss the value of these macrophage markers for the generation of zebrafish reporter lines to study M1/M2 polarization in vivo.

    Oligosaccharides in Urine, Blood, and Feces of Piglets Fed Milk Replacer Containing Galacto-oligosaccharides
    Difilippo, Elisabetta ; Bettonvil, Monique ; Willems, Rianne ; Braber, Saskia ; Fink-Gremmels, Johanna ; Jeurink, Prescilla V. ; Schoterman, Margriet H.C. ; Gruppen, Harry ; Schols, Henk A. - \ 2015
    Journal of Agricultural and Food Chemistry 63 (2015)50. - ISSN 0021-8561 - p. 10862 - 10872.
    absorption - capillary electrophoresis - creatinine - fermentation - GOS - intestine - liquid chromatography - mass spectrometry - pig - prebiotics

    Human milk oligosaccharides (HMOs) are absorbed into the blood (about 1% of the HMO intake) and subsequently excreted in urine, where they may protect the infant from pathogen infection. As dietary galacto-oligosaccharides (GOS) have partial structural similarities with HMOs, this study investigated the presence of GOS and oligosaccharides originating from milk replacer in blood serum, urine, and cecal and fecal samples of piglets, as a model for human infants. Using liquid chromatography-mass spectrometry and capillary electrophoresis with fluorescence detection, oligosaccharides originating from piglet diet including 3′-sialyllactose and specific GOS ranging from degree of polymerization 3 to 6 were detected in blood serum and in urine of piglets. In blood serum, GOS levels ranged from 16 to 23 μg/mL, representing about 0.1% of the GOS daily intake. In urine, approximately 0.85 g of GOS/g of creatinine was found. Cecum digesta and feces contained low amounts of oligosaccharides, suggesting an extensive GOS intestinal fermentation in piglets.

    Immune-relevant thrombocytes of common carp undergo parasite-induced nitric oxide-mediated apoptosis
    Fink, I.R. ; Ribeiro, C.M.S. ; Forlenza, M. ; Taverne-Thiele, J.J. ; Rombout, J.H.W.M. ; Savelkoul, H.F.J. ; Wiegertjes, G. - \ 2015
    Developmental and Comparative Immunology 50 (2015)2. - ISSN 0145-305X - p. 146 - 154.
    lymphocyte maturation factor - cyprinus-carpio - expression analysis - human platelets - functional-characterization - monoclonal-antibodies - cell-differentiation - teleost fish - genes - l.
    Common carp thrombocytes account for 30–40% of peripheral blood leukocytes and are abundant in the healthy animals' spleen, the thrombopoietic organ. We show that, ex vivo, thrombocytes from healthy carp express a large number of immune-relevant genes, among which several cytokines and Toll-like receptors, clearly pointing at immune functions of carp thrombocytes. Few studies have described the role of fish thrombocytes during infection. Carp are natural host to two different but related protozoan parasites, Trypanoplasma borreli and Trypanosoma carassii, which reside in the blood and tissue fluids. We used the two parasites to undertake controlled studies on the role of fish thrombocytes during these infections. In vivo, but only during infection with T. borreli, thrombocytes were massively depleted from the blood and spleen leading to severe thrombocytopenia. Ex vivo, addition of nitric oxide induced a clear and rapid apoptosis of thrombocytes from healthy carp, supporting a role for nitric oxide-mediated control of immune-relevant thrombocytes during infection with T. borreli. The potential advantage for parasites to selectively deplete the host of thrombocytes via nitric oxide-induced apoptosis is discussed.
    Comparison of Milk Oligosaccharides Pattern in Colostrum of Different Horse Breeds
    Difilippo, E. ; Willems, H.A.M. ; Vendrig, J.C. ; Fink-Gremmels, J. ; Gruppen, H. ; Schols, H.A. - \ 2015
    Journal of Agricultural and Food Chemistry 63 (2015)19. - ISSN 0021-8561 - p. 4805 - 4814.
    neutral oligosaccharides - mass-spectrometry - bovine colostrum - fed babies - lactation - feces - acid
    Colostrum oligosaccharides are known to exhibit prebiotic and immunomodulatory properties. Oligosaccharide composition is species-specific, and equine colostrum has been reported to contain unique oligosaccharides. Therefore, equine oligosaccharides (EMOS) from colostrum from different horse breeds were analyzed by CE-LIF, CE-MSn, HILIC-MSn, and exoglycosidase degradation. Sixteen EMOS were characterized and quantified, of which half were neutral and half were acidic. EMOS showed about 63% structural overlap with human milk oligosaccharides, known for their bioactivity. Seven EMOS were not reported before in equine oligosaccharides literature: neutral Gal(ß1–4)HexNAc, Gal(ß1–4)Hex-Hex, ß4'-galactosyllactose, and lactose-N-hexaose, as well as acidic 6'-Sialyl-Hex-Ac-HexNAc, sialyllacto-N-tetraose-a, and disialylacto-N-tetraose (isomer not further specified). In all colostrum samples, the average oligosaccharide concentration ranged from 2.12 to 4.63 g/L; with ß 6'and 3'- galactosyllactose, 3'-sialyllactose, and disialyllactose as the most abundant of all oligosaccharides (27–59, 16–37, 1–8, and 1–6%, respectively). Differences in presence and in abundance of specific EMOS were evident not only between the four breeds but also within the breed.
    Molecular and functional characterization of the scavenger receptor CD36 in zebrafish and common carp
    Fink, I.R. ; Benard, E.L. ; Hermsen, G.J. ; Meijer, A.H. ; Forlenza, M. ; Wiegertjes, G. - \ 2015
    Molecular Immunology 63 (2015)2. - ISSN 0161-5890 - p. 381 - 393.
    toll-like receptors - salmon salmo-salar - cyprinus-carpio - density-lipoprotein - neutrophilic granulocytes - monoclonal-antibodies - accessory molecules - innate immunity - gene family - in-vivo
    CD36 is a scavenger receptor which has been studied closely in mammals where it is expressed by many different cell types and plays a role in highly diverse processes, both homeostatic and pathologic. It is among other things important in the innate immune system, in angiogenesis, and in clearance of apoptotic cells, and it is also involved in lipid metabolism and atherosclerosis. Recently, in the cephalochordate amphioxus a primitive CD36 family member was described, which was present before the divergence of CD36 from other scavenger receptor B family members, SCARB1 and SCARB2. Not much is known on the Cd36 molecule in teleost fish. We therefore studied Cd36 in both zebrafish and common carp, two closely related cyprinid fish species. Whereas a single cd36 gene is present in zebrafish, carp has two cd36 genes, and all show conserved synteny compared to mammalian CD36. The gene expression of carp cd36 is high in brain, ovary and testis but absent in immune organs. Although in mammals CD36 expression in erythrocytes, monocytes and macrophages is high, gene expression studies in leukocyte subtypes of adult carp and zebrafish larvae, including thrombocytes and macrophages provided no indication for any substantial expression of cd36 in immune cell types. Surprisingly, analysis of the cd36 promoter region does show the presence of several binding sites for transcription factors known to regulate immune responses. Overexpression of carp cd36 locates the receptor on the cell surface of mammalian cell lines consistent with the predicted topology of cyprinid Cd36 with a large extracellular domain, two transmembrane domains, and short cytoplasmic tails at both ends. Gene expression of cd36 is down-regulated during infection of zebrafish with Mycobacterium marinum, whereas knockdown of cd36 in zebrafish larvae led to higher bacterial burden upon such infection. We discuss the putative role for Cd36 in immune responses of fish in the context of other members of the scavenger receptor class B family.
    Identification and functional characterization of nonmammalian Toll-like receptor 20
    Pietretti, D. ; Scheer, M.H. ; Fink, I.R. ; Taverne, N. ; Savelkoul, H.F.J. ; Spaink, H.P. ; Forlenza, M. ; Wiegertjes, G. - \ 2014
    Immunogenetics 66 (2014)2. - ISSN 0093-7711 - p. 123 - 141.
    carp cyprinus-carpio - leucine-rich repeats - common carp - ictalurus-punctatus - monoclonal-antibodies - pathogen recognition - accessory molecules - expression analysis - sequence-analysis - channel catfish
    Like other vertebrate Toll-like receptors (TLRs), the TLRs of teleost fish can be subdivided into six major families, each of which recognize a general class of molecular patterns. However, there also are a number of Tlrs with unknown function, the presence of which seems unique to the bony fish, among which is Tlr20. We identified full-length complementary DNA (cDNA) sequences for tlr20 of zebrafish and common carp, two closely related fish species. Zebrafish have six copies of tlr20, whereas carp express only a single copy. Both zebrafish Tlr20 (at least Tlr20a–d) and carp Tlr20 have 26 leucine-rich repeats (LRRs). Three-dimensional modeling indicates a best fit to the crystal structure of TLR8. Phylogenetic analyses place Tlr20 in the TLR11 family closest to Tlr11 and Tlr12, which sense ligands from protozoan parasites in the mouse. Conservation of genes on zebrafish chromosome 9, which carries tlr20, with genes on mouse chromosome 14, which carries tlr11, indicates Tlr11 could be a possible ortholog of Tlr20. Confocal microscopy suggests a subcellular localization of Tlr20 at the endoplasmatic reticulum. Although in vitro reporter assays could not identify a ligand unique to Tlr20, in vivo infection experiments indicate a role for Tlr20 in the immune response of carp to protozoan parasites (Trypanoplasma borreli). Carp tlr20 is mainly expressed in peripheral blood leukocytes (PBL) with B lymphocytes, in particular, expressing relatively high levels of Tlr20. In vitro stimulation of PBL with T. borreli induces an upregulation of tlr20, supportive of a role for Tlr20 in the immune response to protozoan parasites.
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