Perinatal programming of murine immune responses by polyunsaturated fatty acids

Maternal Intake of Polyunsaturated Fatty Acids in Autism Spectrum Etiology and Its Relation to the Gut Microbiota: What Do We Know?

Maternal food habits and gut microbiota composition have potential effects on fetal neurodevelopment, impacting Autism Spectrum Disorder (ASD). Our research aims to outline the relationship that ingestion of polyunsaturated fatty acids (PUFAs) and the composition of maternal gut microbiota have with the possible development of ASD in offspring. We suggest that genetic factors could be related to the different conversions between unsaturated fatty acids according to sex and, mainly, the impact of the pregnancy diet on the higher or lower risk of neurological impairments. The proportion of the phyla Firmicutes/Bacteroidetes is high with an increased consumption of linoleic acid (LA, n-6 PUFA), which is associated with maternal intestinal dysbiosis and consequently starts the inflammatory process, harming myelinization. In contrast, the consumption of α-linolenic acid (ALA, n-3 PUFA) tends to re-establish the balance of the maternal microbiota with anti-inflammatory action. Moreover, human observational studies showed a strong correlation between the consumption of n-3 PUFA, mainly above 340 g of fish per week, with beneficial effects on infant neurodevelopment. Therefore, we suggest that the proper intake of foods rich in n-3 PUFAs and their supplementation during pregnancy until lactation has an impact on reducing the development of ASD. Controlled studies with n-3 PUFA supplementation are still necessary to verify the ideal dose and the best form of administration.

Deoxynivalenol exposure during pregnancy has adverse effects on placental structure and immunity in mice model

Deoxynivalenol (DON), a highly prevalent food contaminant, is known to induce reproductive and immunotoxicity in humans upon exposure. The present study focused on the consequences of exposure to DON during pregnancy for placental barrier and immune function, as well as fetal survival. Female mice received diets contaminated with DON (6.25 and 12.5 mg/kg of diet), starting immediately after mating until the end of the experiment. On day 17 of pregnancy the animals were killed, and maternal and fetal samples were collected for further analysis. Feeding on DON-contaminated diets decreased fetal survival, and DON was detected at significant levels in the fetus. Placentae from DON-exposed mice revealed a reduction in expression of junctional proteins, ZO-1, E-cadherin and claudins, upregulation of AHR mRNA expressions, and increase in IFN-ꝩ, IL-6 and IL-4 production. In conclusion, results of this study demonstrate harmful effects of DON on the course of pregnancy and fetal survival, which might be due to immunological changes in maternal immune organs and placenta. Altogether, these data underline the importance of the quality of maternal diet during pregnancy as they clearly demonstrate the potential harmful effects of a commonly present food-contaminant.

Exposure to Deoxynivalenol During Pregnancy and Lactation Enhances Food Allergy and Reduces Vaccine Responsiveness in the Offspring in a Mouse Model

Deoxynivalenol (DON), a highly prevalent contaminant of grain-based products, is known to induce reproductive- and immunotoxicities. Considering the importance of immune development in early life, the present study investigated the effects of perinatal DON exposure on allergy development and vaccine responsiveness in the offspring. Pregnant mice received control or DON-contaminated diets (12.5 mg/kg diet) during pregnancy and lactation. After weaning, female offspring were sensitized to ovalbumin (OVA) by oral administration of OVA with cholera toxin (CT). Male offspring were injected with Influvac vaccine. OVA-specific acute allergic skin response (ASR) in females and vaccine-specific delayed-type hypersensitivity (DTH) in males were measured upon intradermal antigen challenge. Immune cell populations in spleen and antigen-specific plasma immunoglobulins were analyzed. In female CT+OVA-sensitized offspring of DON-exposed mothers ASR and OVA-specific plasma immunoglobulins were significantly higher, compared to the female offspring of control mothers. In vaccinated male offspring of DON-exposed mothers DTH and vaccine-specific antibody levels were significantly lower, compared to the male offspring of control mothers. In both models a significant reduction in regulatory T cells, Tbet+ Th1 cells and Th1-related cytokine production of the offspring of DON-exposed mothers was observed. In conclusion, early life dietary exposure to DON can adversely influence immune development in the offspring. Consequently, the immune system of the offspring may be skewed towards an imbalanced state, resulting in an increased allergic immune response to food allergens and a decreased immune response to vaccination against influenza virus in these models.

Human Milk Oligosaccharide 3'-GL Improves Influenza-Specific Vaccination Responsiveness and Immunity after Deoxynivalenol Exposure in Preclinical Models

Deoxynivalenol (DON), a highly prevalent mycotoxin food contaminant, is known to have immunotoxic effects. In the current study, the potential of dietary interventions with specific mixtures of trans-galactosyl-oligosaccharides (TOS) to alleviate these effects were assessed in a murine influenza vaccination model. Vaccine-specific immune responses were measured in C57Bl/6JOlaHsd mice fed diets containing DON, TOS or a combination, starting 2 weeks before the first vaccination. The direct effects of TOS and its main oligosaccharide, 3'-galactosyl-lactose (3'-GL), on DON-induced damage were studied in Caco-2 cells, as an in vitro model of the intestinal epithelial barrier. Exposure to DON significantly reduced vaccine-specific immune responses and the percentages of Tbet+ Th1 cells and B cells in the spleen. DON significantly altered epithelial structure and integrity in the ileum and reduced the SCFA levels in the cecum. Adding TOS into DON-containing diets significantly improved vaccine-specific immune responses, restored the immune cell balance in the spleen and increased SCFA concentrations in the cecum. Incubating Caco-2 cells with TOS and 3'-GL in vitro further confirmed their protective effects against DON-induced barrier disruption, supporting immune modulation. Overall, dietary intervention with TOS can attenuate the adverse effects of DON on Th1-mediated immune responses and gut homeostasis. These beneficial properties might be linked to the high levels of 3'-GL in TOS.

Perspective: Moving Toward Desirable Linoleic Acid Content in Infant Formula

Infant formula should provide the appropriate nutrients and adequate energy to facilitate healthy infant growth and development. If conclusive data on quantitative nutrient requirements are not available, the composition of human milk (HM) can provide some initial guidance on the infant formula composition. This paper provides a narrative review of the current knowledge, unresolved questions, and future research needs in the area of HM fatty acid (FA) composition, with a particular focus on exploring appropriate intake levels of the essential FA linoleic acid (LA) in infant formula. The paper highlights a clear gap in clinical evidence as to the impact of LA levels in HM or formula on infant outcomes, such as growth, development, and long-term health. The available preclinical information suggests potential disadvantages of high LA intake in the early postnatal period. We recommend performing well-designed clinical intervention trials to create clarity on optimal levels of LA to achieve positive impacts on both short-term growth and development and long-term functional health outcomes.

Maternal dietary inflammatory potential and quality are associated with offspring asthma risk over 10-year follow-up: the Lifeways Cross-Generation Cohort Study

BACKGROUND

Asthma is the most common childhood chronic health condition. Maternal antenatal diet has been associated with offspring asthma risk, but studies investigating maternal whole diet quality and inflammatory potential with long-term offspring follow-up (>5 y) are rare.

OBJECTIVES

We aimed to elucidate these associations in a prospective cohort study in Ireland.

METHODS

Early pregnancy diets were assessed using a validated FFQ from which energy-adjusted Dietary Inflammatory Index (E-DII) and Healthy Eating Index (HEI)-2015 scores were computed. Doctor-diagnosed offspring asthma status (general practitioner or parent reports) for the first 10 y of life was collected at 3-y, 5-y, and 9-y follow-up. A total of 862 mother-child pairs with information on maternal diet and ≥1 offspring asthma data points were included. The longitudinal associations between maternal E-DII and HEI scores and offspring asthma status were assessed using generalized estimating equations.

RESULTS

Cumulative offspring asthma incidence was 21% over the 10-y period. In the main models, adjusted for maternal lifestyle and sociodemographic factors, a higher E-DII score, indicating a more proinflammatory diet, was associated with higher risk of offspring asthma (OR: 1.35; 95% CI: 1.10, 1.65; per 1-SD score increment), whereas a higher HEI-2015 score, indicating better dietary quality, was associated with lower risk (OR: 0.77; 95% CI: 0.64, 0.93) (both P < 0.01). Results persisted with further adjustment for childhood factors (e.g., breastfeeding, diet, and childcare attendance) and parental asthma history. Similar associations were observed when E-DII and HEI-2015 scores were modeled in quartiles (both P-trend < 0.05). Associations for HEI-2015 were attenuated after adjustment for E-DII, suggesting the importance of anti-inflammatory pathways.

CONCLUSIONS

Our results suggest that a proinflammatory and low-quality diet during pregnancy is associated with a higher risk of offspring asthma. Pending confirmation from other studies, optimizing these aspects of maternal diet can be a promising strategy for reducing childhood asthma risk. This prospective observational study was registered at the ISRCTN Registry as ISRCTN16537904.

Role of omega-6 and omega-3 fatty acids in fetal programming

Maternal nutrition plays a critical role in fetal development and can influence adult onset of disease. Linoleic acid (LA) and alpha-linolenic acid (ALA) are major omega-6 (n-6) and n-3 polyunsaturated fatty acids (PUFA), respectively, that are essential in our diet. LA and ALA are critical for the development of the fetal neurological and immune systems. However, in recent years, the consumption of n-6 PUFA has increased gradually worldwide, and elevated n-6 PUFA consumption may be harmful to human health. Consumption of diets with high levels of n-6 PUFA before or during pregnancy may have detrimental effects on fetal development and may influence overall health of offspring in adulthood. This review discusses the role of n-6 PUFA in fetal programming, the importance of a balance between n-6 and n-3 PUFAs in the maternal diet, and the need of further animal models and human studies that critically evaluate both n-6 and n-3 PUFA contents in diets.

Polyphenol Effects on Splenic Cytokine Response in Post-Weaning Contactin 1-Overexpressing Transgenic Mice

Background: In mice, postnatal immune development has previously been investigated, and evidence of a delayed maturation of the adaptive immune response has been detected. Methods: In this study, the effects of red grape polyphenol oral administration on the murine immune response were explored using pregnant mice (TAG/F3 transgenic and wild type (wt) mice) as the animal model. The study was performed during pregnancy as well as during lactation until postnatal day 8. Suckling pups from polyphenol-administered dams as well as day 30 post-weaning pups (dietary-administered with polyphenols) were used. Polyphenol effects were evaluated, measuring splenic cytokine secretion. Results: Phorbol myristate acetate-activated splenocytes underwent the highest cytokine production at day 30 in both wt and TAG/F3 mice. In the latter, release of interferon (IFN)-γ and tumor necrosis factor (TNF)-α was found to be higher than in the wt counterpart. In this context, polyphenols exerted modulating activities on day 30 TAG/F3 mice, inducing release of interleukin (IL)-10 in hetero mice while abrogating release of IL-2, IFN-γ, TNF-α, IL-6, and IL-4 in homo and hetero mice. Conclusion: Polyphenols are able to prevent the development of an inflammatory/allergic profile in postnatal TAG/F3 mice.

Maternal intake of omega-3 and omega-6 polyunsaturated fatty acids during mid-pregnancy is inversely associated with linear growth

This study investigates relations of maternal N-3 and N-6 polyunsaturated fatty acids (PUFA) intake during pregnancy with offspring body mass index (BMI), height z-score and metabolic risk (fasting glucose, C-peptide, leptin, lipid profile) during peripuberty (8-14 years) among 236 mother-child pairs in Mexico. We used food frequency questionnaire data to quantify trimester-specific intake of N-3 alpha-linolenic acid, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA); N-6 linoleic acid and arachidonic acid (AA); and N-6:N-3 (AA:EPA+DHA), which accounts for the fact that the two PUFA families have opposing effects on physiology. Next, we used multivariable linear regression models that accounted for maternal education and parity, and child's age, sex and pubertal status, to examine associations of PUFA intake with the offspring outcomes. In models where BMI z-score was the outcome, we also adjusted for height z-score. We found that higher second trimester intake of EPA, DHA and AA were associated with lower offspring BMI and height z-score. For example, each 1-s.d. increment in second trimester EPA intake corresponded with 0.25 (95% CI: 0.03, 0.47) z-scores lower BMI and 0.20 (0.05, 0.36) z-scores lower height. Accounting for height z-score in models where BMI z-score was the outcome attenuated estimates [e.g., EPA: -0.16 (-0.37, 0.05)], suggesting that this relationship was driven by slower linear growth rather than excess adiposity. Maternal PUFA intake was not associated with the offspring metabolic biomarkers. Our findings suggest that higher PUFA intake during mid-pregnancy is associated with lower attained height in offspring during peripuberty. Additional research is needed to elucidate mechanisms and to confirm findings in other populations.

They Are What You Eat: Can Nutritional Factors during Gestation and Early Infancy Modulate the Neonatal Immune Response?

The ontogeny of the human immune system is sensitive to nutrition even in the very early embryo, with both deficiency and excess of macro- and micronutrients being potentially detrimental. Neonates are particularly vulnerable to infectious disease due to the immaturity of the immune system and modulation of nutritional immunity may play a role in this sensitivity. This review examines whether nutrition around the time of conception, throughout pregnancy, and in early neonatal life may impact on the developing infant immune system.

The Maternal Diet, Gut Bacteria, and Bacterial Metabolites during Pregnancy Influence Offspring Asthma

This review focuses on the current evidence that maternal dietary and gut bacterial exposures during pregnancy influence the developing fetal immune system and subsequent offspring asthma. Part 1 addresses exposure to a farm environment, antibiotics, and prebiotic and probiotic supplementation that together indicate the importance of bacterial experience in immune programming and offspring asthma. Part 2 outlines proposed mechanisms to explain these associations including bacterial exposure of the fetoplacental unit; immunoglobulin-related transplacental transport of gut bacterial components; cytokine signaling producing fetomaternal immune alignment; and immune programming via metabolites produced by gut bacteria. Part 3 focuses on the interplay between diet, gut bacteria, and bacterial metabolites. Maternal diet influences fecal bacterial composition, with dietary microbiota-accessible carbohydrates (MACs) selecting short-chain fatty acid (SCFA)-producing bacteria. Current evidence from mouse models indicates an association between increased maternal dietary MACs, SCFA exposure during pregnancy, and reduced offspring asthma that is, at least in part, mediated by the induction of regulatory T lymphocytes in the fetal lung. Part 4 discusses considerations for future studies investigating maternal diet-by-microbiome determinants of offspring asthma including the challenge of measuring dietary MAC intake; limitations of the existing measures of the gut microbiome composition and metabolic activity; measures of SCFA exposure; and the complexities of childhood respiratory health assessment.

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.

Relevance of pre- and postnatal nutrition to development and interplay between the microbiota and metabolic and immune systems

Early-life programming is becoming an established concept that states that the environment during early development affects health and disease in adulthood, probably via epigenetic mechanisms such as DNA methylation, histone modifications, RNA silencing, or a combination. Accumulating evidence suggests that nutrition during pregnancy and early postnatal life is one of the most important environmental cues that programs microbiological, metabolic, and immunologic development. The neonatal period is crucial for the early microbial colonization of the almost sterile gastrointestinal tract of the newborn infant. These first colonizers play an important role in host health because they are involved in nutritional, immunologic, and physiologic functions. Evidence from animal and human studies indicates that the composition of the gut microbiota has an effect on body composition, digestion, and metabolic homeostasis. Furthermore, the functionality of the metabolism develops after birth when the newborn is first exposed to nutrition via the gastrointestinal tract. Exposure to environmental microbial components is also suggested to have a key role in the maturation process of the immune system, and in turn the immune system shapes the composition of the microbiota. Therefore, the use of nutritional strategies to program the microbiota composition to favor a more beneficial bacterial population and to support the development of the metabolic and immune systems may provide a good opportunity to prevent later health problems such as obesity, diabetes, and allergy.

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.

Dietary fatty acids affect the immune system in male mice sensitized to ovalbumin or vaccinated with influenza

PUFA are precursor molecules for eicosanoids such as leukotrienes and prostaglandins and may influence immune function through other mechanisms involving membranes, cell signaling, and gene expression. Immune-modulating properties of diets containing different oils [sunflower oil, rich in linoleic acid; linseed oil, rich in α-linolenic acid; salmon oil, rich in marine (n-3) PUFA; and beef tallow, rich in SFA] were investigated in an influenza-vaccination model, in which the delayed-type hypersensitivity (DTH) response was studied in C57BL/6 mice, and an ovalbumin (OVA)-sensitization model for experimental allergy in BALB/c mice. Six-week-old mice were fed the different diets for 7 wk. The first vaccination or OVA sensitization was given 2 wk after the start of the dietary intervention. In the mice vaccinated with influenza, the DTH response to the vaccine was significantly higher in mice fed the marine (n-3) PUFA diet compared to all other groups, indicating that these PUFA promote a T helper-1 response. In the OVA-sensitized mice, those fed the marine (n-3) PUFA diet had a less severe acute allergic skin response (ASR), suggesting that (n-3) PUFA lessen the T helper-2 response. Mice fed the SFA-rich diet had the most severe ASR, indicating that a diet with high levels of SFA may contribute to increased severity of allergic symptoms. Whereas significant differences in in vivo immune responses were measured, in vitro responses did not differ among the dietary groups. In conclusion, using 2 different models of immune responses demonstrates potential benefits from marine (n-3) PUFA.