Increased Fruit and Vegetable Consumption Prevents Dysregulated Immune and Inflammatory Responses in High-Fat Diet-Induced Obese Mice.

BACKGROUND: Obesity is often associated with impaired immune responses, including enlarged spleen, increased inflammation, and impaired T-cell-mediated function, which may lead to increased susceptibility to infections. Bioactive compounds found in various fruits and vegetables (F&V) have been shown to have strong anti-inflammatory effects. However, few prospective studies have examined the effects of F&V on preventing obesity-associated dysregulation of immune and inflammatory responses. OBJECTIVE: The objective of this was to determine the impact of different levels of a mixture of F&V incorporated in a high-fat diet (HFD) on immune function changes in a diet-induced obesity animal model. METHODS: Six-wk-old male C57BL/6J mice were randomly assigned to 1 of 5 groups (n = 12/group): matched low-fat control (LF, 10% kcal fat) or HFD (45% kcal fat) supplemented with 0%, 5%, 10%, or 15% (wt/wt) freeze-dried powder of the most consumed F&V (human equivalent of 0, 3, 5-7, 8-9 servings/d, respectively) for 20 wk. Spleen weight was recorded, and the immunophenotype of splenocytes was evaluated by flow cytometry. Ex vivo splenic lymphocyte proliferation was assessed by thymidine incorporation and serum cytokines concentrations were measured by Meso Scale Discovery. RESULTS: Mice fed the HFD exhibited significantly higher spleen weight, decreased splenic CD8+ lymphocytes, suppressed T lymphocyte proliferation, and reduced serum IL-1ß and IFN-γ concentrations compared with those fed the LF diet. Feeding mice with the HFD supplemented with 10% or 15% F&V restored HFD-associated changes of these affected biomarkers compared with those fed HFD only. Furthermore, a significant correlation was found between immunologic markers and F&V level. CONCLUSIONS: These results suggest that increased consumption of F&V has beneficial effects in preventing HFD-associated dysregulation of immune function.

Efficacy of a yeast postbiotic on cold/flu symptoms in healthy children: A randomized-controlled trial.

BACKGROUND: Children attending school/daycare are at high risk of acute respiratory tract infections. EpiCorTM postbiotic, derived from yeast fermentate, has been demonstrated to improve immune function in adults, reducing the incidence of cold/flu-like or allergy symptoms. As such, studies are warranted in children as available pharmaceutical options have unwanted side effects. METHODS: Two-hundred and fifty-six children aged 4-12 years attending school/daycare were randomized to either EpiCor or Placebo for 84 days during the 2022-2023 flu season in Ontario, Canada. The Canadian Acute Respiratory Illness and Flu Scale (CARIFS) and study diary assessed the incidence and severity of cold/flu symptoms and the use of cold/flu medications. Adverse events were recorded. RESULTS: Total CARIFS severity scores, 'sore throat' and 'muscle aches or pains' symptom scores in the EpiCor group were significantly lower compared to Placebo during incidences of cold/flu (P ≤ 0.05). Participants taking Placebo were 1.73 times more likely to use cold/flu medication compared to those receiving EpiCor (P = 0.04). The incidence of cold/flu symptoms was not significantly different between groups. EpiCor was found to be safe and well-tolerated. CONCLUSIONS: EpiCor supplementation resulted in significantly lower cold/flu symptom severity and less cold/flu medication usage than Placebo demonstrating a beneficial effect on immune function in children. IMPACT: Children are at high risk of acquiring cold/flu infections and safe and efficacious mitigating regimens are lacking. Children supplemented daily with 500 mg EpiCorTM postbiotic derived from yeast fermentate had significantly lower overall cold/flu symptom severity, and severity of sore throat and muscle aches or pains over the 84-day supplementation period. EpiCor supplementation resulted in decreased use of traditional cold/flu medication. Daily supplementation with 500 mg of EpiCor for 84 days was safe and well tolerated by healthy children aged 4-12 years attending school or daycare.

The Lipid-Soluble Forms of Choline Enhance Ex Vivo Responses from the Gut-Associated Immune System in Young Female Rat Offspring.

BACKGROUND: In humans, the development of gut-associated lymphoid tissue (GALT) occurs in the first years of life and can be influenced by diet. OBJECTIVES: The objective of this study was to determine the effect of dietary choline on the development of gut-associated lymphoid tissue (GALT). METHODS: Three feeding trials were conducted in female Sprague-Dawley rats. Beginning 3 d before parturition (studies 1 and 3) or at day 10 of gestation (study 2), control dams consumed a 100% free choline (FC) diet until the end of the lactation period. In studies 1 and 3, test dams consumed a high-glycerophosphocholine (HGPC) diet [75% glycerophosphocholine (GPC), 12.5% phosphatidylcholine (PC), 12.5% FC] and a 100% PC diet, respectively (both 1 g of choline/kg diet). In study 2, test dams consumed a high-sphingomyelin (SM) and PC (SMPC) diet (34% SM, 37% PC, 17% GPC, 7% FC, 5% phosphocholine) or a 50% PC diet (50% PC, 25% FC, 25% GPC), both 1.7 g of choline/kg diet. Immune cell phenotypes and ex vivo cytokine production by mitogen-stimulated immune cells were measured. RESULTS: Feeding of the HGPC diet lowered T-cell IL-2 (44%), IFN-γ (34%), and TNF-α (55%) production in mesenteric lymph nodes (MLNs) compared with control. Feeding both SMPC and 50% PC diets during the lactation and weaning periods increased IL-2 (54%) and TNF-α (46%) production after T-cell stimulation compared with control. There was a lower production of IL-2 (46%), IL-6 (66%), and TNF-α (45%), and a higher production of IL-10 (44%) in both SMPC and 50% PC groups following ovalbumin stimulation compared with control in MLNs. Feeding a diet containing 100% PC increased the production of IFN-γ by 52% after T-cell stimulation compared with control. CONCLUSION: Feeding a diet containing a mixture of choline forms with a high content of lipid-soluble forms during both the lactation and weaning periods enhances ex vivo immune responses from the GALT in female Sprague-Dawley offspring.

Feeding Buttermilk-Derived Choline Forms During Gestation and Lactation Modulates Ex Vivo T-Cell Response in Rat Dams.

BACKGROUND: Buttermilk contains a mixture of choline forms; it is high in phosphatidylcholine (PC) and sphingomyelin (SM), which could have an impact on immune system development and function. OBJECTIVES: We aimed to determine the effect of feeding buttermilk-derived choline forms during pregnancy and lactation on maternal immune function. METHODS: Sprague Dawley dams (n = 8 per diet) were randomly assigned midway through pregnancy (10 d of gestation) to 1 of 3 experimental diets, containing 1.7 g/kg choline: control [100% free choline (FC)]; buttermilk [37% PC, 34% SM, 17% glycerophosphocholine (GPC), 7% FC, 5% phosphocholine]; or placebo (50% PC, 25% FC, 25% GPC). Dams consumed the same diet until the end of the lactation period (21 d after parturition). Cell phenotypes and cytokine production by mitogen-stimulated splenocytes were measured and compared using 1-factor ANOVA test in order to asses the effect of diet on immune fuction of lactating dams (main outcome). RESULTS: After ConA stimulation, splenocytes from dams in the buttermilk group produced more IL-2 (30%), TNF-α (30%), and IFN-γ (42%) compared with both the placebo and control diets. Placebo-fed dams had a higher proportion of CD8+ cells expressing CD152+ (22%) in spleen, and splenocytes from dams that were fed the buttermilk and the placebo diets produced about 50% and 53% more IL-10 after LPS and OVA stimulation, respectively, compared with the control group. CONCLUSIONS: Feeding buttermilk-derived choline forms during pregnancy and lactation had a beneficial impact on the immune system of Sprague Dawley rat dams, especially on T-cell function.

A Novel Combination of Fruits and Vegetables Prevents Diet-Induced Hepatic Steatosis and Metabolic Dysfunction in Mice.

BACKGROUND: Epidemiological studies suggest that higher fruits and vegetables (F&V) consumption correlates with reduced risk of hepatic steatosis, yet evidence for causality and the underlying mechanisms is lacking. OBJECTIVES: We aimed to determine the causal relation between F&V consumption and improved metabolic disorders in mice fed high-fat (HF) (Experiment-1) or normal-fat (Experiment-2) diets and its underlying mechanisms. METHODS: Six-week-old male C57BL/6J mice were randomly grouped and fed diets supplemented at 0%-15% (wt:wt) with a freeze-dried powder composed of 24 commonly consumed F&V (human equivalent of 0-9 servings/d) for 20 wk. In Experiment-1, mice were fed an HF (45% kcal fat) diet with 0% (HF0), 5%, 10%, or 15% (HF15) F&V or a matched low-fat control diet (10% kcal fat). In Experiment-2, mice were fed an AIN-93 diet (basal) (B, 16% kcal fat) with 0% (B0), 5%, 10%, or 15% (B15) F&V supplementation. Body weight and composition, food intake, hepatic steatosis, inflammation, ceramide levels, sphingomyelinase activity, and gut microbiota were assessed. RESULTS: In Experiment-1, mice fed the HF15 diet had lower weight gain (17.9%), hepatic steatosis (48.4%), adipose tissue inflammation, blood (24.6%) and liver (33.9%) ceramide concentrations, and sphingomyelinase activity (38.8%) than HF0 mice (P < 0.05 for all). In Experiment-2, mice fed the B15 diet had no significant changes in weight gain but showed less hepatic steatosis (28.5%), blood and adipose tissue inflammation, and lower blood (30.0%) ceramide concentrations than B0 mice (P < 0.05 for all). These F&V effects were associated with favorable microbiota changes. CONCLUSIONS: These findings represent the first evidence for a causal role of high F&V intake in mitigating hepatic steatosis in mice. These beneficial effects may be mediated through changes in ceramide and/or gut microbiota, and suggest that higher than currently recommended servings of F&V may be needed to achieve maximum health benefits.

Dietary supplementation with blueberry partially restores T-cell-mediated function in high-fat-diet-induced obese mice.

Blueberry, rich in antioxidant and anti-inflammatory phytochemicals, has been demonstrated to lower inflammatory status in adipose induced by high-fat diet (HFD) and obesity. The effect of blueberry on systemic immune functions has not been examined. C57BL/6 mice were randomised to one of three diets - low-fat diet (LFD), HFD and HFD plus 4 % (w/w) blueberry (HFD+B) - for 8 or 12 weeks. Ex vivo T-cell mitogens (concanavalin A (Con A); phytohaemagglutinin), T-cell antibody (anti-CD3; anti-CD3/CD28)-stimulated T-cell proliferation and cytokine production were assessed. After 8 weeks, both HFD groups weighed more (>4 g) than the LFD group; after 12 weeks, HFD+B-fed mice weighed more (>6 g) and had 41 % more adipose tissue than HFD-fed mice (P<0·05). After 12 weeks, T-cell proliferation was less in both HFD groups, compared with the LFD group. HFD-associated decrements in T-cell proliferation were partially (10-50 %) prevented by blueberry supplementation. At 12 weeks, splenocytes from HFD mice, but not from HFD+B mice, produced 51 % less IL-4 (CD3/CD28) and 57 % less interferon-γ (Con A) compared with splenocytes from LFD mice (P<0·05). In response to lipopolysaccharide challenge, splenocytes from both HFD groups produced 24-30 % less IL-6 and 27-33 % less TNF-α compared with splenocytes from LFD mice (P<0·05), indicating impaired acute innate immune response. By demonstrating deleterious impacts of HFD feeding on T-cell proliferation and splenocyte immune responses, our results provide insights into how HFD/obesity can disrupt systemic immune function. The protective effects of blueberry suggest that dietary blueberry can buttress T-cell and systemic immune function against HFD-obesity-associated insults.

A Dietary Supply of Docosahexaenoic Acid Early in Life Is Essential for Immune Development and the Establishment of Oral Tolerance in Female Rat Offspring.

BACKGROUND: The early postnatal period is critical for immunity, and feeding docosahexaenoic acid (DHA) has been demonstrated to affect immune development. OBJECTIVE: The objective of this study was to determine the importance of feeding DHA during suckling and/or weaning on immune function and oral tolerance (OT). METHODS: Sprague-Dawley rats were randomly assigned to 1 of 2 nutritionally adequate diets throughout lactation (21 d): a control (n = 12, 0% DHA) diet or a DHA (n = 8, 0.9% DHA) diet. At 11 d, suckled pups from each dam were randomly assigned to a mucosal OT challenge: placebo or ovalbumin. At week 5, all pups systemically received ovalbumin + adjuvant to induce systemic immunization. At 21 d, pups from each dam were randomly assigned to 1 of the 2 diets for 21 d in a factorial design after which immune function and OT were assessed. RESULTS: Feeding dams DHA during lactation resulted in a 40-60% higher splenocyte production of interleukin (IL)-10 when stimulated with concanavalin A, lipopolysaccharide (LPS), or ovalbumin and a 100% higher production of interferon (IFN)-γ with LPS (P < 0.05) than feeding the control diet to the pups. In comparison with pups fed the control diet, feeding DHA at weaning resulted in a 25% lower type 1 T helper (IL-1ß) and type 2 T helper (IL-6) response by splenocytes after LPS stimulation and a 33% lower plasma concentration of ovalbumin-specific immunoglobulin (Ig) G (P < 0.05). Pups that did not receive additional DHA during the study had a 70% higher plasma concentration of ovalbumin-specific IgE than did the pups that received DHA at suckling and/or weaning (P < 0.05). CONCLUSIONS: Feeding additional DHA during suckling had a beneficial programming effect on the ability of immune cells to produce IFN-γ and IL-10, and feeding DHA during weaning resulted in a lower inflammatory response. Providing no dietary DHA in either of the critical periods of immune development prevented the establishment of OT in female rat offspring.

The Form of Choline in the Maternal Diet Affects Immune Development in Suckled Rat Offspring.

BACKGROUND: Lipid-soluble phosphatidylcholine (PC) and aqueous free choline are absorbed and metabolized differently, but the metabolic effects of feeding these 2 forms of choline have not been thoroughly investigated. OBJECTIVE: We sought to compare the effects of PC and free choline in the maternal diet on the development of the offspring's immune system. METHODS: During lactation, Sprague-Dawley dams (n= 10) were randomly assigned to 1 of 2 diet groups containing the same concentration of total choline (1 g/kg diet) as free choline (choline bitartrate) or PC (egg lecithin). The splenocytes of pups aged 21 d were isolated and stimulated ex vivo with concanavalin A (ConA) or lipopolysaccharide (LPS), and the choline concentrations of stomach content, plasma, and the spleen were measured. RESULTS: Pups from PC-fed dams had a lower proportion of cells involved in antigen presentation but produced 54% more interleukin (IL)-2, 163% more IL-6, and 107% more IFN-γ after ConA stimulation and 110% more IL-6 and 43% more tumor necrosis factor (TNF)-α after LPS stimulation (allP< 0.05). The PC concentrations were significantly higher in the plasma and spleen of pups from PC-fed dams (P< 0.05). Increasing the supply of PC in the form of lysophosphatidylcholine to splenocytes in vitro increased the rate of proliferation and IL-2 production and the surface expression of CD25, CD28, CD71, and CD152 on CD8+ T cells, suggesting 1 possible mechanism. CONCLUSIONS: The results of this study demonstrate that providing choline to rats in the form of PC (compared to free choline), possibly by increasing the supply of PC to the suckling pups, promotes maturation and improves function of the offspring's immune system.

The content of docosahexaenoic acid in the maternal diet differentially affects the immune response in lactating dams and suckled offspring.

PURPOSE: The objective of this study was to determine the effect of feeding a maternal diet supplemented with docosahexaenoic acid (DHA) while also containing adequate amounts of arachidonic acid on immune system development and function in suckled offspring and lactating rats. METHODS: Sprague-Dawley dams were randomized to one of the two nutritionally adequate experimental diets 24-48 h prior to parturition: control diet (N = 12, 0 % DHA) or high DHA diet (N = 8, 0.9 % DHA of total fatty acids). Diets were fed throughout the lactating/suckling period (21 days), and then, dams and pups were terminated, and immune cell phenotypes and cytokine production by mitogen- or ovalbumin-stimulated splenocytes were measured. RESULTS: Feeding dams a high DHA diet resulted in a higher proportion of 18:3n-3, 22:5n-3 and 22:6n-3 found in pup's stomach content (breast milk; P < 0.01). Feeding the high DHA diet had no impact on growth parameters or the ex vivo cytokine production by mitogen-stimulated splenocytes in both dams and pups. There was a higher proportion of OX12+CD80+ cells and a lower production of TGF-ß by splenocytes after ovalbumin stimulation in pups from dams fed the DHA diet (both P < 0.05) while maintaining a similar IL-2 production. LPS-stimulated splenocytes from dams fed the high DHA diet produced more TNF-α versus control diet (P < 0.05). CONCLUSIONS: Overall, our results suggest that DHA supplementation in the maternal diet does not change the immune response to mitogens but positively affects the activation of B cells as well as the response to a potential food antigen upon challenge in suckled offspring.

Choline is required in the diet of lactating dams to maintain maternal immune function.

Choline demands during lactation are high; however, detailed knowledge is lacking regarding the optimal dietary intake during this critical period. The present study was designed to determine the effects of varying intakes of choline on maternal immune function during lactation. Primiparous Sprague-Dawley rats (n 42) were randomised 24-48 h before birth and fed the following diets for 21 d: choline-devoid (0 g choline/kg diet; D, n 10); 1·0 g choline/kg diet (C1, n 11); 2·5 g choline/kg diet (C2·5, n 10); 6·2 g choline/kg diet (C6, n 11). Splenocytes were isolated and stimulated ex vivo with concanavalin A, lipopolysaccharide (LPS) or CD3/CD28. D and C6 dams had lower final body weight, spleen weight and average pup weight than C1 dams (P< 0·05). There was a linear relationship between free choline concentration in pup stomach contents with maternal dietary choline content (P< 0·001, r² 0·415). Compared with C1 and C2·5, D spleens had a lower proportion of mature T cells and activated suppressor cells, and this resulted in reduced cytokine production after stimulation (P< 0·05). Feeding 6·2 g choline/kg diet resulted in a higher cytokine production after stimulation with CD3/CD28 (P< 0·05). Except for a higher IL-6 production after LPS stimulation with cells from the C2·5 dams (P< 0·05), there were no differences between the C1 and C2·5 dams. For the first time, we show that feeding lactating mothers a diet free of choline has substantial effects on their immune function and on offspring growth. Additionally, excess dietary choline had adverse effects on maternal and offspring body weight but only minimal effects on maternal immune function.