A potential role for CD25 + regulatory T-cells in the protection against casein allergy by dietary non-digestible carbohydrates

Immunomodulation by Human Milk Oligosaccharides: The Potential Role in Prevention of Allergic Diseases

The prevalence and incidence of allergic diseases is rising and these diseases have become the most common chronic diseases during childhood in Westernized countries. Early life forms a critical window predisposing for health or disease. Therefore, this can also be a window of opportunity for allergy prevention. Postnatally the gut needs to mature, and the microbiome is built which further drives the training of infant's immune system. Immunomodulatory components in breastmilk protect the infant in this crucial period by; providing nutrients that contain substrates for the microbiome, supporting intestinal barrier function, protecting against pathogenic infections, enhancing immune development and facilitating immune tolerance. The presence of a diverse human milk oligosaccharide (HMOS) mixture, containing several types of functional groups, points to engagement in several mechanisms related to immune and microbiome maturation in the infant's gastrointestinal tract. In recent years, several pathways impacted by HMOS have been elucidated, including their capacity to; fortify the microbiome composition, enhance production of short chain fatty acids, bind directly to pathogens and interact directly with the intestinal epithelium and immune cells. The exact mechanisms underlying the immune protective effects have not been fully elucidated yet. We hypothesize that HMOS may be involved in and can be utilized to provide protection from developing allergic diseases at a young age. In this review, we highlight several pathways involved in the immunomodulatory effects of HMOS and the potential role in prevention of allergic diseases. Recent studies have proposed possible mechanisms through which HMOS may contribute, either directly or indirectly, via microbiome modification, to induce oral tolerance. Future research should focus on the identification of specific pathways by which individual HMOS structures exert protective actions and thereby contribute to the capacity of the authentic HMOS mixture in early life allergy prevention.

Combined Exposure of Activated Intestinal Epithelial Cells to Nondigestible Oligosaccharides and CpG-ODN Suppresses Th2-Associated CCL22 Release While Enhancing Galectin-9, TGFβ, and Th1 Polarization

Background

Short-chain galacto- and long-chain fructo-oligosaccharides (scGOS/lcFOS) and CpG-ODN affect intestinal epithelial cells (IEC). Epithelial IL1α may contribute to allergic sensitization via autocrine mediator release affecting dendritic cells (DC). We studied whether IL1α contributes to Th2-associated mediator release by activated IEC and IEC/DC cocultures and possible modulation by scGOS/lcFOS±CpG-ODN.

Methods

Solid phase or transwell cultured IEC were preincubated with IL1α and/or IFNγ/TNFα for 6 h. The transwell IEC were also apically exposed to scGOS/lcFOS±CpG-ODN for 6 h, washed, and re-exposed, while cocultured with immature moDC (ccDC) for 48 h. These ccDC were subsequently added to allogeneic naïve T cells (MLR). IEC- and/or DC-derived mediators and T cell cytokines were measured.

Results

IL1α tended to enhance IL25 and enhanced IL33 and CCL20 release by IEC, while IL1α or TNFα or IFNγ enhanced CCL22. These were all further increased upon combined exposure of IFNγ/TNFα±IL1α coinciding with increased IL33 secretion in the solid phase culture. In the transwell, IL25 and IL33 remained under detection, while CCL20 and CCL22 were induced by IL1α or IFNγ/TNFα, respectively, and a synergistic increase was observed upon combined exposure of IFNγ/TNFα and IL1α. Furthermore, IFNγ was found to enhance galectin-9 secretion, which was more pronounced in IFNγ/TNFα±IL1α-exposed IEC and coincided with TGFβ increase. Epithelial CpG-ODN exposure further increased CCL20, while reducing CCL22 release by IFNγ/TNFα/IL1α-activated IEC; however, scGOS/lcFOS suppressed both. Combined scGOS/lcFOS and CpG-ODN reduced CCL22, while CCL20 and regulatory galectin-9 and TGFβ remained high in the supernatant of IFNγ/TNFα/IL1α-activated IEC and the following IEC/DC coculture. ccDC of scGOS/lcFOS- and CpG-ODN-exposed IFNγ/TNFα/IL1α-activated IEC increased IFNγ, IL10, TGFβ, and galectin-9 secretion in the MLR compared to ccDC exposed to control-activated IEC.

Conclusion

IL1α enhanced CCL20 and Th2-associated CCL22 release by IFNγ/TNFα-activated IEC. Combined scGOS/lcFOS and CpG-ODN exposure suppressed CCL22, while maintaining high CCL20, TGFβ, and galectin-9 concentrations. In addition, ccDC derived from this IEC/DC coculture enhanced Th1 and regulatory mediator secretion mimicking known in vivo effects.

Supplementation of diet with non-digestible oligosaccharides alters the intestinal microbiota, but not arthritis development, in IL-1 receptor antagonist deficient mice

The intestinal microbiome is perturbed in patients with new-onset and chronic autoimmune inflammatory arthritis. Recent studies in mouse models suggest that development and progression of autoimmune arthritis is highly affected by the intestinal microbiome. This makes modulation of the intestinal microbiota an interesting novel approach to suppress inflammatory arthritis. Prebiotics, defined as non-digestible carbohydrates that selectively stimulate the growth and activity of beneficial microorganisms, provide a relatively non-invasive approach to modulate the intestinal microbiota. The aim of this study was to assess the therapeutic potential of dietary supplementation with a prebiotic mixture of 90% short-chain galacto-oligosaccharides and 10% long-chain fructo-oligosaccharides (scGOS/lcFOS) in experimental arthritis in mice. We here show that dietary supplementation with scGOS/lcFOS has a pronounced effect on the composition of the fecal microbiota. Interestingly, the genera Enterococcus and Clostridium were markedly decreased by scGOS/lcFOS dietary supplementation. In contrast, the family Lachnospiraceae and the genus Lactobacillus, both associated with healthy microbiota, increased in mice receiving scGOS/lcFOS diet. However, the scGOS/lcFOS induced alterations of the intestinal microbiota did not induce significant effects on the intestinal and systemic T helper cell subsets and were not sufficient to reproducibly suppress arthritis in mice. As expected, we did observe a significant increase in the bone mineral density in mice upon dietary supplementation with scGOS/lcFOS for 8 weeks. Altogether, this study suggests that dietary scGOS/lcFOS supplementation is able to promote presumably healthy gut microbiota and improve bone mineral density, but not inflammation, in arthritis-prone mice.

Mice co-administrated with partially hydrolysed whey proteins and prebiotic fibre mixtures show allergen-specific tolerance and a modulated gut microbiota

Non-breastfed infants at-risk of allergy are recommended to use a hydrolysed formula before the age of 6 months. The addition of prebiotics to this formula may reduce the allergy development in these infants, but clinical evidence is still inconclusive. This study evaluates (1) whether the exposure duration to different prebiotics alongside a partially hydrolysed whey protein (pHP) influences its' effectiveness to prevent allergy development and (2) whether the gut microbiota plays a role in this process. Mice orally sensitised with whey and/or cholera toxin were orally treated for six days before sensitization with phosphate buffered saline, whey or pHP to potentially induce tolerance. Two groups received an oligosaccharide diet only from day -7 until -2 (GFshort and GFAshort) whereas two other groups received their diets from day -15 until 37 (GFlong and GFAlong). On day 35, mice underwent an intradermal whey challenge, and the acute allergic skin response, shock score, and body temperatures were measured. At day 37, mice received whey orally and serum mouse mast cell protease-1, SLPI and whey-specific antibodies were assessed. Faecal samples were taken at day -15, -8 and 34. Feeding mice pHP alone during tolerance induction did not reduce ear swelling. The tolerance inducing mechanisms seem to vary according to the oligosaccharide-composition. GFshort, GFlong, and GFAlong reduced the allergic skin response, whereas GFAshort was not potent enough. However, in the treatment groups, the dominant Lactobacillus species decreased, being replaced by Bacteroidales family S24-7 members. In addition, the relative abundance of Prevotella was significantly higher in the GFlong, GFAshort and GFAlong groups. Co-administration of oligosaccharides and pHP can induce immunological tolerance in mice, although tolerance induction was strongest in the animals that were fed oligosaccharides during the entire protocol. Some microbial changes coincided with tolerance induction, however, a specific mechanism could not be determined based on these data.

Human Milk Oligosaccharides Attenuate Antigen-Antibody Complex Induced Chemokine Release from Human Intestinal Epithelial Cell Lines

There has been increased interest in the use of dietary ingredients, including prebiotics such as human-milk oligosaccharides (HMOs), as therapeutic strategies for food allergy. Understanding the mechanisms underlying the beneficial effects of HMOs is important to realizing their therapeutic potential. Here we demonstrate that the HMO, 6'-sialyllactose (6'SL) inhibited chemokine (IL-8 and CCL20) release from T-84 and HT-29 cells stimulated with antigen-antibody complex, TNFα or PGE₂ ; an effect that was PPARγ dependent and associated with decreased activity of the transcription factors AP-1 and NFκB. In contrast, 2'-fucosyllactose (2'FL) selectively inhibited CCL20 release in response to antigen antibody complex in a PPARγ independent manner. This study reinforces the concept that structurally different oligosaccharides have distinct biological activities and identifies, for the first time, that the HMOs, 6'SL, and 2'FL, modulate human epithelial cell responses related to allergic disease. These findings encourage further investigation of the therapeutic potential of specific HMOs in food allergy.

PRACTICAL APPLICATION

This study provides evidence for direct effects of HMOs in addition to their prebiotic role and demonstrates, for the first time, modulation of Ag-IgE complex activation of human epithelial cells that may have important implications for food-allergy. The study also reinforces the concept that structurally different oligosaccharides have distinct biological activities. In determining the composition of infant formula, addition of oligosaccharides with specific structures may provide direct modulation of immune responses and potentially attenuate symptoms or development of food allergy.

Dietary Intervention with β-Lactoglobulin-Derived Peptides and a Specific Mixture of Fructo-Oligosaccharides and Bifidobacterium breve M-16V Facilitates the Prevention of Whey-Induced Allergy in Mice by Supporting a Tolerance-Prone Immune Environment

Cow's milk allergy (CMA) prevails in infants and brings increased risk of developing other allergic diseases. Oral administration of specific β-lactoglobulin (BLG)-derived peptides (PepMix) and a specific blend of short- and long-chain fructo-oligosaccharides and Bifidobacterium breve M-16V (FF/Bb) was found to partially prevent CMA development in mice. In this study, we aimed to expand the knowledge on the preventive potential and the underlying mechanisms of this approach. Three-week-old female C3H/HeOuJ mice were orally exposed to PepMix±FF/Bb prior to a 5-week oral sensitization with whole whey and cholera toxin as an adjuvant. The acute allergic skin response was determined after an intradermal challenge with whole whey protein. Following an oral challenge with whey, regulatory T cells (T_regs) in the small intestine lamina propria (SI-LP) and mRNA expression of immune markers in the Peyer's patches (PP) were investigated. The early impact of PepMix and FF/Bb interventions on the immune system during the oral tolerance (OT) induction phase was investigated after the last OT administration. Pre-exposing mice to PepMix+FF/Bb partially prevented the acute allergic skin response compared to PBS and increased T_regs and activated T cells in the SI-LP compared to sham-sensitized mice. It also increased the mRNA expression of Tbet over GATA3 in the PP of whey-sensitized mice. Directly upon the 6-day OT phase, FF/Bb intervention enhanced cecal content levels of propionic and butyric acid in PepMix-fed mice and the former was positively correlated with Foxp3⁺ cell numbers in the colon. In the PP of PepMix+FF/Bb-exposed mice, IL-22 mRNA expression increased and IL-10 followed the same tendency, while the Foxp3 expression was increased over GATA3 and RorγT. In the colon, the Tbet mRNA expression increased over GATA3, while IL-22 decreased. In addition, the Foxp3⁺/GATA3⁺ and regulatory/effector T cell ratios in the mesenteric lymph nodes and the CD11b⁺/CD11b^- conventional dendritic cells ratio in the SI-LP were increased. In conclusion, the FF/Bb diet facilitates the capacity of the specific BLG-peptides to partially prevent the allergic response after sensitization to whole whey protein, possibly by creating a tolerance-prone environment during the OT phase. Such a dietary intervention might contribute to tailoring successful strategies for CMA prevention.

Post-sensitization administration of non-digestible oligosaccharides and Bifidobacterium breve M-16V reduces allergic symptoms in mice

To support dietary management of severe cow's milk allergic infants, a synbiotic mixture of non-digestible oligosaccharides and Bifidobacterium breve M-16V (B. breve) was designed from source materials that are completely cow's milk-free. It was investigated whether this specific synbiotic concept can reduce an established food allergic response in a research model for hen's egg allergy. Mice were orally sensitized once a week for 5 weeks to ovalbumin (OVA) using cholera toxin (CT) as an adjuvant. Non-sensitized mice received CT in PBS only. Sensitized mice were fed a control diet or a diet enriched with short-chain- (scFOS) and long-chain fructo-oligosaccharides (lcFOS), B. breve or scFOSlcFOS + B. breve for 3 weeks starting after the last sensitization. Non-sensitized mice received the control diet. Anaphylactic shock symptoms, acute allergic skin responses and serum specific IgE, mMCP-1 and galectin-9 were measured upon OVA challenge. Activated Th2-, Th1-cells and regulatory T-cells were quantified in spleen and mesenteric lymph nodes (MLN) and cytokine profiles were analyzed. Short chain fatty acids (SCFA) were measured in ceacal samples. The acute allergic skin response was reduced in mice fed the scFOSlcFOS + B. breve diet compared to mice fed any of the other diets. A reduction in mast cell degranulation (mMCP-1) and anaphylactic shock symptoms was also observed in these mice. Unstimulated splenocyte cultures produced increased levels of IL10 and IFNg in mice fed the scFOSlcFOS + B. breve diet. Correspondingly, increased percentages of activated Th1 cells were observed in the spleen. Allergen-specific re-stimulation of splenocytes showed a decrease in IL5 production. In summary; post-sensitization administration of scFOSlcFOS + B. breve was effective in reducing allergic symptoms after allergen challenge. These effects coincided with changes in regulatory and effector T-cell subsets and increases in the SCFA propionic acid. These results suggest immune modulatory benefits of dietary intervention with a unique combination of scFOSlcFOS + B. breve in established food allergy. Whether these effects translate to human applications is subject for ongoing clinical studies.

Milk: a postnatal imprinting system stabilizing FoxP3 expression and regulatory T cell differentiation

BACKGROUND

Breastfeeding has protective effects for the development of allergies and atopy. Recent evidence underlines that consumption of unboiled farm milk in early life is a key factor preventing the development of atopic diseases. Farm milk intake has been associated with increased demethylation of FOXP3 and increased numbers of regulatory T cells (Tregs). Thus, the questions arose which components of farm milk control the differentiation and function of Tregs, critical T cell subsets that promote tolerance induction and inhibit the development of allergy and autoimmunity.

FINDINGS

Based on translational research we identified at least six major signalling pathways that could explain milk's biological role controlling stable FoxP3 expression and Treg differentiation: (1) via maintaining appropriate magnitudes of Akt-mTORC1 signalling, (2) via transfer of milk fat-derived long-chain ω-3 fatty acids, (3) via transfer of milk-derived exosomal microRNAs that apparently decrease FOXP3 promoter methylation, (4) via transfer of exosomal transforming growth factor-β, which induces SMAD2/SMAD3-dependent FoxP3 expression, (5) via milk-derived Bifidobacterium and Lactobacillus species that induce interleukin-10 (IL-10)-mediated differentiation of Tregs, and (6) via milk-derived oligosaccharides that serve as selected nutrients for the growth of bifidobacteria in the intestine of the new born infant.

CONCLUSION

Accumulating evidence underlines that milk is a complex signalling and epigenetic imprinting network that promotes stable FoxP3 expression and long-lasting Treg differentiation, crucial postnatal events preventing atopic and autoimmune diseases.

The rise of food allergy: Environmental factors and emerging treatments

Food allergy has rapidly increased in prevalence, suggesting an important role for environmental factors in disease susceptibility. The immune response of food allergy is characterized by IgE production, and new findings from mouse and human studies indicate an important role of the cytokine IL-9, which is derived from both T cells and mast cells, in disease manifestations. Emerging evidence suggests that route of exposure to food, particularly peanut, is important. Exposure through the skin promotes sensitization while early exposure through the gastrointestinal tract promotes tolerance. Evidence from mouse studies indicate a role of the microbiome in development of food allergy, which is supported by correlative human studies showing a dysbiosis in food allergy. There is no approved treatment for food allergy, but emerging therapies are focused on allergen immunotherapy to provide desensitization, while pre-clinical studies are focused on using adjuvants or novel delivery approaches to improve efficacy and safety of immunotherapy.

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Emerging evidence suggests that route of exposure to food allergens in early life determines sensitization versus tolerance.

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The microbiota and dietary factors appear to play a key role in susceptibility to food allergy.

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Immunotherapy applied via different routes is currently the most promising form of experimental treatment for food allergy.

Mesenteric IL-10-producing CD5+ regulatory B cells suppress cow's milk casein-induced allergic responses in mice

Food allergy is a hypersensitive immune reaction to food proteins. We have previously demonstrated the presence of IL-10-producing CD5(+) B cells and suggested their potential role in regulating cow's milk casein allergy in humans and IgE-mediated anaphylaxis in mice. In this study, we determined whether IL-10-producing CD5(+) regulatory B cells control casein-induced food allergic responses in mice and, if so, the underlying mechanisms. The induction of oral tolerance (OT) by casein suppressed casein-induced allergic responses including the decrease of body temperature, symptom score, diarrhea, recruitment of mast cells and eosinophils into jejunum, and other biological parameters in mice. Notably, the population of IL-10-producing CD5(+) B cells was increased in mesenteric lymph node (MLN), but not in spleen or peritoneal cavity (PeC) in OT mice. The adoptive transfer of CD5(+) B cells from MLN, but not those from spleen and PeC, suppressed the casein-induced allergic responses in an allergen-specific and IL-10-dependent manner. The inhibitory effect of IL-10-producing CD5(+) B cells on casein-induced allergic response was dependent on Foxp3(+) regulatory T cells. Taken together, mesenteric IL-10-producing regulatory B cells control food allergy via Foxp3(+) regulatory T cells and could potentially act as a therapeutic regulator for food allergy.

In Vitro Evidence for Immune-Modulatory Properties of Non-Digestible Oligosaccharides: Direct Effect on Human Monocyte Derived Dendritic Cells

Infant formulas containing non-digestible oligosaccharides (NDO) similar to the composition in breast milk or a combination of lactic acid bacteria (LAB) and NDO have been shown to harbor preventive effects towards immune-regulatory disorders. The aim of this study was to investigate the immune-modulatory potential of non-digestible short chain galacto- and long chain fructo-oligosaccharides (scGOS/lcFOS) mimicking the natural distribution of oligosaccharides in human breast milk in presence or absence of certain LAB strains in human monocyte derived dendritic cells (MoDC). Immature human MoDC prepared from peripheral blood of healthy non-atopic volunteers were screened in vitro after stimulation with specific scGOS/lcFOS in presence or absence of LAB. IL-10 and IL-12p70 release was analyzed after 24 hours in cell-free supernatants by enzyme-linked immunosorbent assay (ELISA). A luminex-based assay was conducted to assess further cytokine and chemokine release by MoDC. To investigate the resulting T cell response, stimulated MoDC were co-incubated with naïve T cells in allogeneic stimulation assays and intracellular Foxp3 expression, as well as immune-suppressive capacity was determined. Oligosaccharides did not induce relevant amounts of IL-12p70 production, but did promote IL-10 release by MoDC. Furthermore, scGOS/lcFOS mixtures exerted a significant enhancing effect on LAB induced IL-10 secretion by MoDC while no increase in IL-12p70 production was observed. Blocking toll like receptor (TLR)4 abrogated the increase in IL-10 in both the direct stimulation and the LAB stimulation of MoDC, suggesting that scGOS/lcFOS act via TLR4. Finally, scGOS/lcFOS-treated MoDC were shown to upregulate the number of functional suppressive Foxp3 positive T cells following allogeneic stimulation. Our results indicate anti-inflammatory and direct, microbiota independent, immune-modulatory properties of scGOS/lcFOS mixtures on human MoDC suggesting a possible induction of regulatory T cells (Tregs). The tested combinations of LAB and scGOS/lcFOS might represent a useful dietary ingredient for the maintenance of intestinal homeostasis via the induction of Tregs.

Regulatory T Cell Depletion Abolishes the Protective Effect of Dietary Galacto-Oligosaccharides on Eosinophilic Airway Inflammation in House Dust Mite-Induced Asthma in Mice

BACKGROUND

In a murine model for house dust mite (HDM)-induced asthma, dietary galacto-oligosaccharides have been shown to suppress allergic symptoms. Previously, CD25+ regulatory T cells (Tregs) induced by nondigestible oligosaccharides were found to protect against allergy development.

OBJECTIVE

The aim of the current study was to examine the effect of anti-CD25-induced Treg depletion in a murine HDM-induced asthma model and to study the contribution of Tregs in the protective effect of dietary intervention with galacto-oligosaccharides.

METHODS

Male BALB/c mice (aged 6-8 wk) were intranasally sensitized and challenged with phosphate-buffered saline (PBS) or HDM. Two weeks before sensitization and throughout the whole experiment, mice were fed a control or 1% w/w galacto-oligosaccharide diet. Tregs were depleted by anti-mouse CD25 antibody (intraperitoneally injected). On day 14, T helper cell subtypes in lung and spleen were analyzed and cytokines were measured. Leukocyte subtypes were analyzed in the bronchoalveolar lavage fluid, and interleukin (IL)-33 and chemokines were measured in lung homogenate supernatants.

RESULTS

Anti-CD25 treatment depleted CD25+ Forkhead box P3+ Tregs in the lung and spleen of control and HDM-allergic mice (P < 0.0001) by >70% while increasing the percentage of activated T helper cells (P < 0.05) and type 2 T helper cells (P < 0.05). This was associated with increased IL-10, IL-4, and IL-13 concentrations in supernatants of ex vivo restimulated lung cells (P < 0.01). Bronchoalveolar lavage fluid leukocyte numbers and percentages of eosinophils and lymphocytes were greater in HDM-allergic mice compared with PBS mice (P < 0.01) but remained unaffected by the anti-CD25 treatment. Galacto-oligosaccharides decreased airway eosinophilia compared with HDM-allergic mice fed the control diet (from 47.8% ± 6.7% to 26.6% ± 8.5%, P < 0.01). This protective effect was lost in anti-CD25-treated mice (P < 0.05). In lung homogenates of HDM-allergic mice, IL-33 was increased compared with PBS mice (from 2.8 ± 0.3 to 5.4 ± 0.6 ng protein/mg, P < 0.01). Galacto-oligosaccharides abrogated the increase in IL-33 compared with HDM-allergic mice fed the control diet (3.0 ± 0.6 ng protein/mg, P < 0.05), which was abolished by the anti-CD25 treatment (P < 0.01).

CONCLUSIONS

Treg depletion enhances pulmonary type 2 T helper cell frequency and cytokine release in HDM-induced asthma in mice. Galacto-oligosaccharides decreased airway eosinophilia and IL-33 concentrations in the lung, which was abrogated by Treg depletion. This indicates that galacto-oligosaccharides have a beneficial effect in the prevention of HDM-induced allergic asthma by supporting pulmonary Treg function.

Supplementing pregnant mice with a specific mixture of nondigestible oligosaccharides reduces symptoms of allergic asthma in male offspring

BACKGROUND

Previously, maternal supplementation with short-chain galacto- and long-chain fructo-oligosaccharides (scGOS/lcFOS; ratio 9:1) was shown to affect maternal and fetal immune status in mice.

OBJECTIVE

This study was designed to test the long-term effects of supplementation of mice with scGOS/lcFOS before and during pregnancy on the immune response in the offspring, using an ovalbumin (OVA)-induced model for experimental allergic asthma.

METHODS

Female Balb/c mice were fed a control diet or a diet supplemented with 3% scGOS/lcFOS and mated to C57BL/6 males. All dams were fed the control diet after delivery. At 6 wk, male offspring received an intraperitoneal injection of aluminum hydroxide and OVA (control and scGOS/lcFOS group) or saline (sham group). The acute allergic skin response (ASR) after intradermal challenge with OVA or saline was measured at 8 wk. After 3 airway challenges with nebulized OVA or saline, lung function was measured.

RESULTS

The scGOS/lcFOS group had a significantly lower acute ASR (85 ± 9 μm) than the control group (124 ± 9 μm; P = 0.01). Lower lung resistance from a response to methacholine challenge was seen in the scGOS/lcFOS group. OVA-specific immunoglobulin (Ig)E concentrations in the control group [93 ± 45 arbitrary unit (AU)] and the scGOS/lcFOS group (67 ± 45 AU) were higher than in the sham group (11 ± 2 AU). OVA specific IgG2a concentrations in the scGOS/lcFOS (146 ± 24 AU) were higher than in the sham group (2 ± 0.3 AU) and control group (18 ± 3.5 AU; P < 0.05). Finally, the scGOS/lcFOS group had a higher percentage of regulatory T cells (1.11% ± 0.07%) than the sham group (0.14% ± 0.03%) and the control group (0.11% ± 0.02%; P < 0.05).

CONCLUSION

Maternal supplementation of mice with scGOS/lcFOS during pregnancy leads to a significant decrease in allergic symptoms in the offspring.

Non-digestible oligosaccharides modulate intestinal immune activation and suppress cow's milk allergic symptoms

BACKGROUND

Cow's milk allergy is a common food allergy in childhood and no effective preventive or curative treatment is available. This study aimed at comparing single short-chain galacto- (scGOS), long-chain fructo- (lcFOS) or pectin-derived acidic oligosaccharides (pAOS) and/or mixtures of scGOS/lcFOS (GF) or scGOS/lcFOS/pAOS (GFA) to prevent or treat food allergy.

METHODS

In the preventive protocol, C3H/HeOuJ mice were fed diets containing single oligosaccharides or mixtures GF or GFA throughout the study protocol. In the treatment protocol, GF or GFA was provided for 4 wk starting after the last sensitization. The allergic skin response and anaphylaxis scores were determined, after oral challenge whey-specific immunoglobulins were measured, and qPCR for T-cell markers and Foxp3 counts using immunohistochemistry were performed on the small intestine and colon.

RESULTS

Only in the preventive setting, the GF or GFA mixture, but not the single oligosaccharides, reduced the allergic skin response and whey-IgG(1) levels in whey-sensitized mice, compared to the control diet. Both GF and GFA increased the number of Foxp3+ cells in the proximal small intestine of whey - compared to sham-sensitized mice. Expression of Th2 and Th17 mRNA markers increased in the middle part of the small intestine of whey-sensitized mice, which was prevented by GF. By contrast, GFA enhanced Tbet (Th1), IL-10 and TGF-β mRNA expression compared to GF which was maintained in the distal small intestine and/or colon.

CONCLUSIONS

Dietary supplementation with scGOS/lcFOS or scGOS/lcFOS/pAOS during sensitization, both effectively reduce allergic symptoms but differentially affect mucosal immune activation in whey-sensitized mice.

Role of cellular immunity in cow's milk allergy: pathogenesis, tolerance induction, and beyond

Food allergy is an aberrant immune-mediated reaction against harmless food substances, such as cow's milk proteins. Due to its very early introduction, cow's milk allergy is one of the earliest and most common food allergies. For this reason cow's milk allergy can be recognized as one of the first indications of an aberrant inflammatory response in early life. Classically, cow's milk allergy, as is true for most other allergies as well, is primarily associated with abnormal humoral immune responses, that is, elevation of specific immunoglobulin E levels. There is growing evidence indicating that cellular components of both innate and adaptive immunity play significant roles during the pathogenesis of cow's milk allergy. This is true for the initiation of the allergic phenotype (stimulation and skewing towards sensitization), development and outgrowth of the allergic disease. This review discusses findings pertaining to roles of cellular immunity in allergic inflammation, and tolerance induction against cow's milk proteins. In addition, a possible interaction between immune mechanisms underlying cow's milk allergy and other types of inflammation (infections and noncommunicable diseases) is discussed.

CD25+ regulatory T cells transfer n-3 long chain polyunsaturated fatty acids-induced tolerance in mice allergic to cow's milk protein

BACKGROUND

Recently, we have shown that dietary long-chain n-3 polyunsaturated fatty acids (n-3 LCPUFA) largely prevent allergic sensitization in a murine model for cow's milk allergy. The aim of this study was to assess the contribution of regulatory T cells (Treg) in the prevention of food allergy by n-3 LCPUFA.

METHODS

C3H/HeOuJ female donor mice were fed a control or fish oil diet before and during oral sensitization with cow's milk protein whey. Acute allergic skin response (ASR), anaphylaxis, body temperature, serum immunoglobulins, and mouse mast cell protease-1 (mmcp-1) were assessed. Splenocytes of sham- or whey-sensitized donor mice fed either control or fish oil diet were adoptively transferred to naïve recipient mice. Recipient mice received a whole splenocyte suspension, splenocytes ex vivo depleted of CD25+ cells, or MACS-isolated CD4+ CD25+ Treg. Recipient mice were sham- or whey-sensitized and fed control diet.

RESULTS

The ASR as well as whey-specific IgE and whey-specific IgG1 levels were reduced in whey-sensitized donor mice fed the fish oil diet as compared to the control diet. Splenocytes of control-diet-fed whey-sensitized donors transferred immunologic memory. By contrast, splenocytes of fish-oil-fed whey-sensitized - but not sham-sensitized - donors transferred tolerance to recipients as shown by a reduction in ASR and serum mmcp-1, and depletion of CD25+ Treg abrogated this. Transfer of CD25+ Treg confirmed the involvement of Treg in the suppression of allergic sensitization.

CONCLUSIONS

CD25+ Treg are crucial in whey allergy prevention by n-3 LCPUFA.

Alterations in regulatory T cells induced by specific oligosaccharides improve vaccine responsiveness in mice

Prophylactic vaccinations are generally performed to protect naïve individuals with or without suppressed immune responsiveness. In a mouse model for Influenza vaccinations the specific alterations of CD4⁺CD25⁺Foxp3⁺ regulatory T-cells (Tregs) in the immune modulation induced by orally supplied oligosaccharides containing scGOS/lcFOS/pAOS was assessed. This dietary intervention increased vaccine specific DTH responses. In addition, a significant increased percentage of T-bet⁺ (Th1) activated CD69⁺CD4⁺ T cells (p<0.001) and reduced percentage of Gata-3⁺ (Th2) activated CD69⁺CD4⁺T cells (p<0.001) was detected in the mesenteric lymph nodes (MLN) of mice receiving scGOS/lcFOS/pAOS compared to control mice. Although no difference in the number or percentage of Tregs (CD4⁺Foxp3⁺) could be determined after scGOS/lcFOS/pAOS intervention, the percentage of CXCR3 ⁺ /T-bet⁺ (Th1-Tregs) was significantly reduced (p<0.05) in mice receiving scGOS/lcFOS/pAOS as compared to mice receiving placebo diets. Moreover, although no absolute difference in suppressive capacity could be detected, an alteration in cytokine profile suggests a regulatory T cell shift towards a reducing Th1 suppression profile, supporting an improved vaccination response.

Mechanisms underlying immune effects of dietary oligosaccharides

The WHO refers to human milk as the nutritional gold standard for term infants. Human milk contains many immunomodulatory compounds, including oligosaccharides. Human-milk oligosaccharides can serve as prebiotics because the nondigestible oligosaccharides present in human milk show a clear bifidogenic effect on the gut microbiota. Dietary oligosaccharide structures that have prebiotic effects similar to human-milk oligosaccharides include galacto-oligosaccharides, fructo-oligosaccharides, and pectin-derived acidic oligosaccharides. Both animal studies and human clinical trials showed that dietary intervention with these dietary oligosaccharides in early life could lead to the prevention of atopic dermatitis, food allergy, and allergic asthma. The immune-modulating effects of these oligosaccharides are likely assisted via alteration of the intestinal microbiota or in a microbiota-independent manner by direct interaction on immune cells or both. In this review, an overview of the prebiotic role of dietary oligosaccharides on the microbiota and the microbiota-independent immune modulation by these prebiotics is provided. In addition, recent publications that report on the pathways by which the oligosaccharides might exert their direct immunomodulatory effect are summarized.

Effects of short-chain galacto- and long-chain fructo-oligosaccharides on systemic and local immune status during pregnancy

Nondigestible oligosaccharides can positively influence health via various mechanisms. During pregnancy, supplementation of nondigestible oligosaccharides has positive effects on hypertension and metabolism and may be used to ameliorate pregnancy-related metabolic disturbances. In the nonpregnant state, nondigestible oligosaccharides have been shown to induce a tolerogenic immune response mediated by T-regulatory cells. Since relatively little is known about the effects of nondigestible oligosaccharides on the immune system during pregnancy, pregnant mice were supplemented with a specific mixture of short-chain galacto- and long-chain fructo-oligosaccharides (scGOS/lcFOS; ratio 9:1). Systemic and local immune parameters were analyzed on day 18 of pregnancy. This study shows that, compared with virgin mice, scGOS/lcFOS supplementation appears to elicit a more tolerogenic immune reaction in pregnant mice and supplementation does not increase the Th1-dependent delayed type hypersensitivity response in pregnant mice as it does in virgin mice.

Effects of in vivo injection of anti-chicken CD25 monoclonal antibody on regulatory T cell depletion and CD4+CD25- T cell properties in chickens

Regulatory T cells (Tregs) are defined as CD4(+)CD25(+) cells in chickens. This study examined the effects of an anti-chicken CD25 monoclonal antibody injection (0.5 mg/bird) on in vivo depletion of Tregs and the properties of CD4(+)CD25(-) cells in Treg-depleted birds. The CD4(+)CD25(+) cell percentage in the blood was lower at 8 d post injection than at 0 d. Anti-CD25-mediated CD4(+)CD25(+) cell depletion in blood was maximum at 12 d post injection. The anti-CD25 antibody injection depleted CD4(+)CD25(+) cells in the spleen and cecal tonsils, but not in the thymus, at 12 d post antibody injection. CD4(+)CD25(-) cells from the spleen and cecal tonsils of birds injected with the anti-chicken CD25 antibody had higher proliferation and higher IL-2 and IFNγ mRNA amounts than the controls at 12 d post injection. At 20 d post injection, CD4(+)CD25(+) cell percentages in the blood, spleen and thymus were comparable to that of the 0 d post injection. It could be concluded that anti-chicken CD25 injection temporarily depleted Treg population and increased and IL-2 and IFNγ mRNA amounts in CD4(+)CD25(-) cells at 12d post injection.