Ton Baars

Prof. Dr. Ton Baars

Department Immunopharmacology, Utrecht University, Utrecht, Netherlands
orcid

Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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LVLivia J. F. Wilod Versprille
Livia J. F. Wilod Versprille
ALAurora Van de Loo
Aurora Van de Loo
MMMarlou Mackus
Marlou Mackus
LAL. Arnoldy
L. Arnoldy
TSTitia Sulzer
Titia Sulzer
Joris C VersterJoris C Verster
Joris C Verster
The self-assessment of perceived immune status is important, as this subjective observation leads individuals to decide whether or not to seek medical help or adapt their lifestyle. In addition, it can be used in clinical settings and research. The aim of this series of studies was to develop and validate a short questionnaire to assess perceived immune functioning. Five surveys were conducted among Dutch and International young healthy adults (18–30 years old), and two others among older age groups with various health complaints. For the first study, an existing immune functioning scale was modified and elaborated resulting in 23 immune-health-related items, of which the occurrence was rated on a 5-point Likert scale. A student sample was surveyed, and the results were used to shorten the 23-item listing into a 7-item scale with a predictive validity of 85%. Items include “sudden high fever”, “diarrhea”, “headache”, “skin problems (e.g., acne and eczema)”, “muscle and joint pain”, “common cold” and “coughing”. The scale is named Immune Status Questionnaire (ISQ), and it aims to assess perceived immune status over the preceding year. The second study revealed that the ISQ score correlated significantly with a 1-item perceived immune functioning (r = 0.383, p < 0.0001). In the third study, the final Likert scale descriptors were determined (“never”, “sometimes”, “regularly”, “often” and “(almost) always)”. The fourth study showed that the test–retest reliability of the ISQ is acceptable (r = 0.80). The fifth study demonstrated the association of ISQ scores with various neuropsychological and health correlates in an international sample, including perceived health and immune fitness, as well as levels of stress, fatigue, depression and anxiety. Study 6 demonstrated significant associations between ISQ scores and experiencing irritable bowel syndrome (IBS) symptoms in a sample of insomnia patients. Study 7 compared the effect of a dietary intervention in participants reporting “poor health” versus “normal health”. It is shown that ISQ scores can differentiate between those with poor and normal health, and that an effective intervention is associated with a significant improvement in ISQ scores. Data from Study 7 were further used to determine an ISQ cut-off value for reduced immune functioning, and a direct comparison with 1-item perceived immune functioning scores enabled constructing the final scoring format of the ISQ. In conclusion, the ISQ has appropriate face, content, and construct validity and is a reliable, stable and valid method to assess the past 12 month’s perceived immune status.

14 September 2022 in World Allergy Organization Journal
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Journal Article
Open access
SJSebastian A. Jensen
Sebastian A. Jensen
AFAlessandro Fiocchi
Alessandro Fiocchi
Ton BaarsTon Baars
Ton Baars
GJGalateja Jordakieva
Galateja Jordakieva
ANAnna Nowak-Wegrzyn
Anna Nowak-Wegrzyn
EJErika Jensen-Jarolim
Erika Jensen-Jarolim
The immunopathogenesis of cow's milk protein allergy (CMPA) is based on different mechanisms related to immune recognition of protein epitopes, which are affected by industrial processing. The purpose of this WAO DRACMA paper is to: (i) give a comprehensive overview of milk protein allergens, (ii) to review their immunogenicity and allergenicity in the context of industrial processing, and (iii) to review the milk-related immune mechanisms triggering IgE-mediated immediate type hypersensitivity reactions, mixed reactions and non-IgE mediated hypersensitivities. The main cow's milk allergens - α-lactalbumin, β-lactoglobulin, serum albumin, caseins, bovine serum albumins, and others - may determine allergic reactions through a range of mechanisms. All marketed milk and milk products have undergone industrial processing that involves heating, filtration, and defatting. Milk processing results in structural changes of immunomodulatory proteins, leads to a loss of lipophilic compounds in the matrix, and hence to a higher allergenicity of industrially processed milk products. Thereby, the tolerogenic capacity of raw farm milk, associated with the whey proteins α-lactalbumin and β-lactoglobulin and their lipophilic ligands, is lost. The spectrum of immunopathogenic mechanisms underlying cow's milk allergy (CMA) is wide. Unprocessed, fresh cow's milk, like human breast milk, contains various tolerogenic factors that are impaired by industrial processing. Further studies focusing on the immunological consequences of milk processing are warranted to understand on a molecular basis to what extent processing procedures make single milk compounds into allergens.

11 November 2019 in Nutrition & Food Science
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Journal Article
Closed access
Ton BaarsTon Baars
Ton Baars
Anna Catharina Björnsdotter BergeAnna Catharina Björnsdotter Berge
Anna Catharina Björnsdotter Berge
JGjohan Garssen
johan Garssen
Joris C VersterJoris C Verster
Joris C Verster
Purpose: The purpose of this paper was to evaluate health conditions prior to and at least two months after the start of consuming raw fermented milk (RFM) products. Design/methodology/approach: One-Item health score, 1-item immunity score, immune status (ISQ), mood, bowel and skin conditions were rated for the period prior and post switching to RFM products. A linear mixed model was used to evaluate the post to prior RFM health and mood scores, taking into account gender, location of living and health group. Data from 390 participants (mean age of 54 years old) were included for the analysis, of which 277 (45 per cent) were allocated to the poor health group. Participants were allocated to the poor health group if they reported being immune depressed or suffering from a chronic disease prior to RFM; otherwise, they were allocated to the normal health group. Findings: The highest intake of RFM was from RF kefir. Post RFM, people consumed around 1 glass (200 ml) of RF kefir per day. After switching to RFM, significant improvements on health and mood scores were reported. The strongest improvements after switching to RFM consumption were seen in subjects from the poor health group. With the exception of skin score, all measured health items significantly improved (p < 0.001). Health, immunity, bowel and mood scores increased with around 20 per cent in the poor health group and around 8 per cent in the normal health group. Women had more health complaints prior to RFM and had stronger health improvement post RFM compared to men. Bowel and mood scores were overall lower in women than in men. Living location had no significant impact on RFM-related health changes. This consumer survey suggests that positive health and mood changes are associated with the consumption of RFM products. Originality/value: The consumption of RFM products improved the self-reported health status of adults. Immune-depressed people or people suffering from a chronic disease prior to RFM reported the strongest impact on their health, immunity, bowel and mood scores post switching RFM consumption compared to people with a normal health.

1 March 2019 in Journal of Dairy Science
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Journal Article
Closed access
Ton BaarsTon Baars
Ton Baars
GJG. Jahreis
G. Jahreis
Stefan LorkowskiStefan Lorkowski
Stefan Lorkowski
CRC. Rohrer
C. Rohrer
JVJ. Vervoort
J. Vervoort
KHKasper Hettinga
Kasper Hettinga
Horns are living tissue and cows can use their horns for thermoregulatory purposes. We investigated the effect of the presence of horns on the metabolome of milk serum and lipidome of milk fat, to assess the physiological effect of dehorning. Milk sampling took place at low ambient temperatures of -6 to 2°C. Horned and dehorned cows were kept in a mixed herd of Holstein Friesian and Brown Swiss cows. The hypothesis was that horned cows needed to increase their metabolism to compensate for additional heat loss through the presence of their horns. No differences were observed in milk yield, milk solids, and somatic cell counts between horned and dehorned cows. For the milk metabolome, horned cows showed an upregulation of several glucogenic AA that could be transformed into glucose for energy supply and a downregulation of sugar intermediates and γ-glutamylcysteine compared with dehorned cows. The fatty acid (FA) composition in horned cows showed a shift toward decreased odd medium-chain FA (C7:0, C9:0, and C11:0) and increased cis-vaccenic acid (C18:1n-7 cis-11) and stearidonic acid (C18:4n-3). The changes in milk composition related to additional heat loss in horned cows indicate a competition in C3 metabolism for glucose synthesis and de novo FA synthesis under cold stress.

22 March 2019 in Animals
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Journal Article
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Ton BaarsTon Baars
Ton Baars
JWJenifer Wohlers
Jenifer Wohlers
CRCarsten Rohrer
Carsten Rohrer
Stefan LorkowskiStefan Lorkowski
Stefan Lorkowski
GJGerhard Jahreis
Gerhard Jahreis
Background: Biodynamic dairy production is based on a land-related animal production without the additional input of N-fertilizers. The concentrate level per cow is low. This affects the yield level of animals and product quality outcomes. Methods: We examined the milk fatty acid (FA) composition of European biodynamic farms in relation to the ecological region of production and the farm’s climate conditions. Climate data were derived from existing maps describing ecological vegetation zones within Europe. Additionally, biodynamic shop milk was compared to conventional shop milk, based on a regional comparison. Results: The largest differences in the FA composition were between biodynamic summer and winter milk. We found increased proportions of conjugated linoleic acid (CLA), alpha-linolenic acid (ALA-n3), monounsaturated FA (MUFA), and polyunsaturated FA (PUFA) in the summer milk. A principal component analysis expressed the structure that was present in the biodynamic farm milk samples, based on clusters of a single FA within four components. The components could be correlated with the season of production, the amount of precipitation, the elevation of the farm above sea level, and the length of the grazing season. Biodynamic shop milk in the summer had a lower n6/n3 PUFA ratio compared to the conventional shop milk in all regions of production. Mean values were 1.37 and 1.89, respectively. Conclusions: The differentiation of biodynamic milk FA composition is consistent with the existing knowledge about the effects of fresh grass, fodder, and ratio composition on the milk’s FA composition. Based on the n6/n3 PUFA ratio, the average biodynamic dairy cow had a high intake (>82%) of fresh grass and conserved roughage (hay and grass silage), especially in the summer.

19 October 2022 in bioRxiv
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Preprint
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Ton BaarsTon Baars
Ton Baars
BEBetty van Esch
Betty van Esch
LOLuuk van Ooijen
Luuk van Ooijen
ZZZuomin Zhang
Zuomin Zhang
PDPieter Dekker
Pieter Dekker
RKRemco Kort
Remco Kort
This study aims to characterize the microbial and peptidomic composition of raw milk kefir, and to address the potential anti-allergic effects of raw milk kefir using validated research models for food allergy. Raw milk kefir was produced after incubation with a defined freeze-dried starter culture. Kefir was sampled during fermentation at seven-time intervals. For comparison, kefir was also prepared from boiled milk (100 °C; 5 sec). Peptide compositions were determined for the raw and heated milk, plus kefir end products made from these milks. In a murine food allergy model, the two kefir end products were investigated on their allergy modulating effects. In both kefirs, we identified amplicon sequence variants identical to those in the starter, matching the bacteria Lactococcus lactis, Streptococcus thermophilus, Leuconostoc and the yeast Debaromyces . In raw milk kefir, additional sequence variants of Lactococcus lactis and the yeasts Pichia and Galactomyces could be identified, which were absent in heated milk kefir. Analysis of peptide compositions in kefirs indicated that the number and intensity of peptides drastically increased after fermentation. Heating of milk negatively affected the diversity of the peptide composition in kefir. Only raw milk kefir suppressed the acute allergic skin response to the food allergen ovalbumin in sensitised mice. These effects coincided with differences in the T-cell compartment, with lower percentages of activated Th1 cells and IFNg production after treatment with kefir made from heated milk. The results of this study indicate specific properties of raw milk kefir that may contribute to its additional health benefits.