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

Maternal diet supplementation with high-docosahexaenoic-acid canola oil, along with arachidonic acid, promotes immune system development in allergy-prone BALB/c mouse offspring at 3 weeks of age

PURPOSE

To study the effects of feeding docosahexaenoic acid (DHA, derived from novel canola oil), with same amount of arachidonic acid (ARA), supplemented diet to lactating dams on the immune system development of suckled offspring using a T helper type-2 (Th2)-dominant BALB/c mouse.

METHODS

Dams received nutritionally complete control (no ARA or DHA) or DHA + ARA diet (1% DHA and 1% ARA of total fatty acids) from 5 days pre-parturition to the end of 3-week suckling period. After euthanization, relevant tissues were collected to study fatty acids, splenocyte phenotype and function (ex vivo cytokines with/without lipopolysaccharide (LPS, bacterial challenge) or phorbol myristate acetate + ionomycin (PMAi) stimulation).

RESULTS

Feeding dams a DHA diet significantly increased the mammary gland milk phospholipid concentration of DHA and ARA. This resulted in 60% higher DHA levels in splenocyte phospholipids of the pups although ARA levels showed no difference. In dams fed DHA diet, significantly higher proportion of CD27+ cytotoxic T cell (CTL) and CXCR3+ CCR6- Th (enriched in Th1) were observed than control, but there were no differences in the splenocyte function upon PMAi (non-specific lymphocyte stimulant) stimulation. Pups from DHA-fed dams showed significantly higher IL-1β, IFN-γ and TNF-α (inflammatory cytokines) by LPS-stimulated splenocytes. This may be due to higher proportion of CD86+ macrophages and B cells (all p's < 0.05) in these pups, which may influence T cell polarization.

CONCLUSION

Plant-based source of DHA in maternal diet resulted in higher ex vivo production of inflammatory cytokines by splenocytes due to change in their phenotype, and this can skew T cell towards Th1 response in a Th2-dominant BALB/c mouse.

The Programming Effect of Plant-Based DHA, Along with Equivalent AA, on Immune System and Oral Tolerance Development in Six-Week Allergy Prone BALB/c Pups

BACKGROUND

Docosahexaenoic acid (DHA) and arachidonic acid (AA) on oral tolerance (OT) development in allergy-prone infants is less known.

OBJECTIVES

We aim to determine the effects of early life DHA supplementation (1% of total fat, from novel canola oil), along with AA, on OT toward ovalbumin (ova, egg protein) in allergy-prone BALB/c pups at 6-wk.

METHODS

Breastfeeding dams (n ≥ 10/diet) were fed DHA+AA (1% DHA, 1% AA wt/wt of total fat) or control (0% DHA, 0% AA) suckling period diet (SPD) during which pups consumed dam's milk. At 3-wk, pups from each SPD group were assigned to either the control or DHA+AA weaning diet. For OT, pups from each diet group were either orally fed ova or placebo daily from 21-25 d. Systemic immunization to ova was induced through intraperitoneal injections before euthanizing 6-wk pups. Ova-specific immunoglobulin (ova-Ig) and splenocytes ex-vivo cytokine response to different stimuli were analyzed using a 3-factor analysis of variance.

RESULTS

OT-induced suppression was seen in ova-stimulated splenocyte ex-vivo response, where ova-tolerized pups showed significantly lower total immunoglobulin (Ig)G, IgG1, interleukin (IL)-2 and IL-6 production than sucrose (placebo) pups. DHA+AA SPD was associated with 3 times lower plasma concentrations of ova-IgE (P = 0.03) than controls. DHA+AA weaning diet resulted in lower T helper type-2 cytokines (IL-4 and IL-6) with ova stimulation than controls, which may benefit OT. DHA+AA SPD resulted in significantly higher T cell cytokine response [IL-2, interferon-gamma, (IFNγ) and IL-1β] to anti-CD3/CD28 stimulation than controls. The splenocytes stimulated with lipopolysaccharide produced lower inflammatory cytokines (IFNγ, tumor necrosis factor-alpha, IL-6, and C-X-C motif ligand 1), which may be because of lower CD11b+CD68+ splenocytes proportion in pups from DHA+AA SPD than control (all P < 0.05).

CONCLUSIONS

DHA and AA in early life may influence OT in allergy-prone BALB/c mouse offspring, as they effectively promote T helper type-1 immune responses.

Rodent models of metabolic disorders: considerations for use in studies of neonatal programming

Epidemiologically, metabolic disorders have garnered much attention, perhaps due to the predominance of obesity. The early postnatal life represents a critical period for programming multifactorial metabolic disorders of adult life. Though altricial rodents are prime subjects for investigating neonatal programming, there is still no sufficiently generalised literature on their usage and methodology. This review focuses on establishing five approach-based models of neonatal rodents adopted for studying metabolic phenotypes. Here, some modelled interventions that currently exist to avoid or prevent metabolic disorders are also highlighted. We also bring forth recommendations, guidelines and considerations to aid research on neonatal programming. It is hoped that this provides a background to researchers focused on the aetiology, mechanisms, prevention and treatment of metabolic disorders.

Combined Supplementation with Arachidonic and Docosahexaenoic Acids in T Helper Type-2 Skewed Brown Norway Rat Offspring is Beneficial in the Induction of Oral Tolerance toward Ovalbumin and Immune System Development

BACKGROUND

A T helper type-2 (Th2) skewed immune response is associated with food allergies. DHA and arachidonic acid (ARA) have been shown to promote oral tolerance (OT) in healthy rodents.

OBJECTIVES

We studied the effect of combined ARA + DHA supplementation during the suckling and weaning periods on OT and immune system development in Th2-skewed Brown Norway rat offspring.

METHODS

Dams were fed ARA + DHA (0.45% ARA, 0.8% DHA wt/wt of total fat; n = 10) as a suckling period diet (SPD) or control SPD (0% ARA, 0% DHA, n = 8). At 3 wk, offspring from each SPD group received ARA + DHA (0.5% ARA, 0.5% DHA wt/wt of total fat) weaning diet (WD), or control until 8 wk. For OT, offspring were orally exposed to either ovalbumin (OVA) or placebo between 21 and 25 d, followed by systemic immunization with OVA + adjuvant at 7 wk. Primary outcomes, ex vivo cytokine production by splenocytes and plasma OVA-specific Igs, were analyzed using a 3-way ANOVA.

RESULTS

At 8 wk, despite no lasting effect of SPD on splenocytes fatty acids, ARA + DHA WD resulted in 2× higher DHA in splenocyte phospholipid compositions without affecting ARA. OT development was observed in OVA-exposed groups with 15% lower plasma OVA-IgE (P = 0.04) and 35% lower OVA-IgG1 (P = 0.01) than placebo. ARA + DHA SPD resulted in 35% lower OVA-IgG1 and iIL-6 (P = 0.04) when stimulated with LPS, and a higher proportion of mature B cells (OX12+, P = 0.0004, and IgG+, P = 0.008). ARA + DHA WD resulted in 20% higher Th1 cytokines (TNF-α and IFN-γ) production to lymphocyte stimulant and higher splenocyte proportion of CD45RA+ (pan-B cells) and OX6+ (dendritic cells) than control WD (P values < 0.05).

CONCLUSIONS

Combined supplementation of ARA and DHA is beneficial for OT development, especially in the suckling period. Further, ARA + DHA supplementation can also counteract the Th2-skewed immunity of Brown Norway rat offspring through higher Th1 cytokine production by lymphocytes.

Effects of carboxymethyl chitosan adsorption on bioactive components of Antarctic krill oil

High acid value (AV) and fluorine content of Antarctic krill oil (AKO) extracted from frozen krill by ethanol limit its product development. In this study, a method was proposed to reduce the AV and fluorine content of AKO by carboxymethyl chitosan (CMCS) adsorption. The optimal adsorption condition was 12.5% (w/v) of CMCS at 30℃ for 15 min. At this condition, AV and fluorine content decreased by 78.0% and 61.4%, respectively. It is interesting that CMCS adsorption showed specificity to particular substances. Although free fatty acids content showed a significant reduction, free EPA and DHA, phospholipid and astaxanthin remained almost constant. Moreover, CMCS adsorption showed no influence on neuroprotective activity of AKO against H₂O₂-induced neuro-damage of PC12 cells. The reclaimed CMCS showed an undiminished antimicrobial activity against both Gram-positive and Gram-negative bacteria. The CMCS adsorption shows a potential development for refining AKO and other oils in food industry.

Dietary Supplementation throughout Life with Non-Digestible Oligosaccharides and/or n-3 Poly-Unsaturated Fatty Acids in Healthy Mice Modulates the Gut-Immune System-Brain Axis

The composition and activity of the intestinal microbial community structures can be beneficially modulated by nutritional components such as non-digestible oligosaccharides and omega-3 poly-unsaturated fatty acids (n-3 PUFAs). These components affect immune function, brain development and behaviour. We investigated the additive effect of a dietary combination of scGOS:lcFOS and n-3 PUFAs on caecal content microbial community structures and development of the immune system, brain and behaviour from day of birth to early adulthood in healthy mice. Male BALB/cByJ mice received a control or enriched diet with a combination of scGOS:lcFOS (9:1) and 6% tuna oil (n-3 PUFAs) or individually scGOS:lcFOS (9:1) or 6% tuna oil (n-3 PUFAs). Behaviour, caecal content microbiota composition, short-chain fatty acid levels, brain monoamine levels, enterochromaffin cells and immune parameters in the mesenteric lymph nodes (MLN) and spleen were assessed. Caecal content microbial community structures displayed differences between the control and dietary groups, and between the dietary groups. Compared to control diet, the scGOS:lcFOS and combination diets increased caecal saccharolytic fermentation activity. The diets enhanced the number of enterochromaffin cells. The combination diet had no effects on the immune cells. Although the dietary effect on behaviour was limited, serotonin and serotonin metabolite levels in the amygdala were increased in the combination diet group. The combination and individual interventions affected caecal content microbial profiles, but had limited effects on behaviour and the immune system. No apparent additive effect was observed when scGOS:lcFOS and n-3 PUFAs were combined. The results suggest that scGOS:lcFOS and n-3 PUFAs together create a balance-the best of both in a healthy host.

Effects of Dietary n-3 and n-6 Polyunsaturated Fatty Acids in Inflammation and Cancerogenesis

The dietary recommendation encourages reducing saturated fatty acids (SFA) in diet and replacing them with polyunsaturated fatty acids (PUFAs) n-3 (omega-3) and n-6 (omega-6) to decrease the risk of metabolic disturbances. Consequently, excessive n-6 PUFAs content and high n-6/n-3 ratio are found in Western-type diet. The importance of a dietary n-6/n-3 ratio to prevent chronic diseases is linked with anti-inflammatory functions of linolenic acid (ALA, 18:3n-3) and longer-chain n-3 PUFAs. Thus, this review provides an overview of the role of oxylipins derived from n-3 PUFAs and oxylipins formed from n-6 PUFAs on inflammation. Evidence of PUFAs' role in carcinogenesis was also discussed. In vitro studies, animal cancer models and epidemiological studies demonstrate that these two PUFA groups have different effects on the cell growth, proliferation and progression of neoplastic lesions.

Nutritional Interventions to Prevent the Development of Atopic Diseases: A Focus on Cow's Milk Allergy

In the western world the prevalence of atopic diseases such as food allergies is increasing highly significantly. One of the earliest and most prevalent food allergies occurring in the first year of life is cow's milk allergy. No treatment is available and only avoidance of the cow's milk allergens prevents the occurrence of an allergic reaction. Since cow's milk allergic children have an increased risk of developing other allergies later in life, investigating nutritional strategies to prevent the development of cow's milk allergy by developing oral tolerance is of high interest. Nutritional components such as prebiotics, probiotics, synbiotics and long-chain polyunsaturated fatty acids possess potential to support the maturation of the immune system early in life that might prevent the development of cow's milk allergy. The available research, so far, shows promising results particularly on the development of eczema. However, the preventive effects of the nutritional interventions on the development of food allergy are inconclusive. Future research may benefit from the combination of various dietary components. To clarify the preventive effects of the nutritional components in food allergy more randomized clinical trials are needed.

Feeding a Bioactive Oil Enriched in Stearidonic Acid during Early Life Influences Immune System Maturation in Neonatal Sprague-Dawley Rats

BACKGROUND

Long-chain n-3 PUFAs (LCPUFAs) improve immune development and reduce atopic disease risk in infants. Stearidonic acid (SDA) can be a substrate for biosynthesis of n-3 LCPUFAs.

OBJECTIVE

We aimed to determine the effect of feeding an SDA-enriched diet during suckling and weaning on offspring immunity and ability to develop oral tolerance (OT).

METHODS

Pregnant Sprague-Dawley rats were randomly assigned to consume either SDA (3 g SDA/100 g fat) or a control (no SDA) diet, 5 d before parturition and through lactation (21 d). For the OT treatment, 10-d-old pups were fed ovalbumin (Ova; 200 μL of 8 mg/mL) or placebo daily for 5 d. At 21 d, pups (both sexes) were weaned to their respective maternal diet until 6 wk of age or killed. Systemic immunization was induced using Ova (in 3-wk-old pups) or Ova + adjuvant (in 6-wk-old pups). The effect of suckling diet (in 3-wk-old pups) or weaning diet (in 6-wk-old pups) and OT treatment on immune function (main outcome) in spleen and blood was compared using 2-factor ANOVA.

RESULTS

An SDA-enriched maternal diet, compared with the control diet, resulted in higher plasma phospholipid (PL) EPA (15 times higher), docosapentaenoic acid (DPA; 3 times higher), and DHA (1.3 times higher) content in 3-wk-old pups, accompanied by higher B-cell function [plasma ovalbumin-specific IgG1 (Ova-IgG1), 2 times higher] ( P < 0.05). Compared with pups fed a control diet, the splenocytes from these pups had more (23%) helper T (Th) cells (CD3+CD4+) and activated (12%) Th cells (CD4+CD28+) (P < 0.02) than controls. At 6 wk, the SDA group had 30% more CD4+CD25+ splenocytes, and when stimulated ex vivo with LPS, produced less inflammatory IL-6 (50%) and TNF-α (30%) and more immunoregulatory IL-10 (45%) cytokines (P < 0.05) than the control group. The Ova-exposed group had less (30%) plasma Ova-IgG1 than the placebo group. Splenocytes and plasma PLs from the 6-wk-old SDA group had more EPA (2x) and DPA (3.5x) (P < 0.05), but not DHA, than the control group.

CONCLUSIONS

Feeding SDA during lactation and weaning altered immune responses in directions believed to be beneficial.

The influence of dietary corn distillers dried grains with solubles during gestation of sows on fatty acid composition of colostrum and offspring

Thirty-six sows were randomly assigned to three treatments and fed 0, 125, or 250 g kg−1 corn distillers dried grains with solubles (DDGS), which aimed to evaluate the effects of feeding DDGS to sows during gestation on the fatty acid composition of colostrum and offspring. In colostrum, feeding 0–250 g kg−1 DDGS resulted in linear increase (P < 0.001) in linoleic acid (18:2n-6) level (from 14.7% to 19.8%) and total polyunsaturated fatty acid (PUFA) level (from 16.9% to 22.8%), and linear decrease (P < 0.05) in levels of palmitic acid (16:0), oleic acid (18:1 cis-9), and total saturated fatty acid (SFA). In addition, the percentage of arachidonic acid (20:4n-6) in colostrum was increased from 0.56% to 1.23% (linear effect, P < 0.001, and quadratic effect, P = 0.010) with increasing level of DDGS. Feeding DDGS to sows resulted in linear increase (P < 0.05) in levels of 18:2n-6 (from 13.9% to 20.4%), 20:4n-6 (from 0.53% to 0.73%), docosahexaenoic acid (22:6n-3, from 0.28% to 0.37%), and total PUFA (from 15.9% to 22.6%), and linear decrease (P < 0.001) in levels of 16:0 and SFA of carcass of newborn piglets. The results demonstrated that feeding 125 or 250 g kg−1 corn DDGS to sows increased the proportions of 18:2n-6, 20:4n-6, and total PUFA and decreased the proportions of 16:0 and total SFA in sow colostrum and the carcasses of newborn piglets, implying that inclusion of corn DDGS in diets for sows can alter fatty composition of colostrum and piglets.

Role of dietary lipids in food allergy

The prevalence of food allergy is raising in industrialized countries, but the mechanisms behind this increased incidence are not fully understood. Environmental factors are believed to play a role in allergic diseases, including lifestyle influences, such as diet. There is a close relationship between allergens and lipids, with many allergenic proteins having the ability to bind lipids. Dietary lipids exert pro-inflammatory or anti-inflammatory functions on cells of the innate immunity and influence antigen presentation to cells of the adaptive immunity. In addition to modifying the immunostimulating properties of proteins, lipids also alter their digestibility and intestinal absorption, changing allergen bioavailability. This study provides an overview of the role of dietary lipids in food allergy, taking into account epidemiological information, as well as results of mechanistic investigations using in vivo, ex vivo and in vitro models. The emerging link among high-fat diets, obesity, and allergy is also discussed.

Supplementing dams with both arachidonic and docosahexaenoic acid has beneficial effects on growth and immune development

Omega-3 long-chain polyunsaturated fatty acids (LCPUFAS) modulate immune cells in vitro and in vivo. This study investigated the effects of enriching the maternal diet with the n-6 and n-3 LCPUFAs, arachidonic (20:4n-6, 0.6%wt ARA) and docosahexaenoic acid (22:6n-3, 0.32%wt DHA), or 1:1 and 2:1 ratios (ARA: DHA) on total lipids in milk, total lipids, and immunophenotypes in plasma, lymph nodes, and spleen from isolated immune cells from 28d old pups. From day 15 of gestation to day 3 pp, Sprague-Dawley dams were fed a commercial chow. On day 3 pp litters were culled and pups (4 males and 2 females) randomly cross-fostered to dams who were randomized to one of the 5 experimental diets resulting in 20 male and 10 female pups/diet group. Dams fed ARA or ARA: DHA had 28-36% more 20:4n-6 in milk and feeding DHA or ARA: DHA doubled 22:6n-3 in milk lipids (P<0.05). Feeding 1:1 or 2:1 ARA: DHA resulted in greater pup weight at weaning (P<0.05). Compared to the control pups, ARA + DHA fed pups had a lower proportion of splenic CD45RA+ lymphocytes. In summary, postpartum supplementation with a combination of ARA + DHA, compared to ARA or DHA alone, resulted in a higher content of ARA and DHA in dam's milk and tissues and had positive effects on growth, accompanied by evidence of progression toward a mature immune phenotype, and suggests a need for ARA when DHA is supplemented in the early diet. Additional investigations are needed of ARA immunomodulation to better understand and estimate nutritional requirements for LCPUFAs during early development.