Development of mucosal immune function in the intrauterine and early postnatal environment

Oat β-glucan supplementation pre- and during pregnancy alleviates fetal intestinal immunity development damaged by gestational diabetes in rats

Oat β-glucan (OG) has been shown to improve intestinal microecology in gestational diabetes mellitus (GDM), but the effect on fetal intestine health is unknown. Herein, we aimed to investigate the effects of OG supplementation during gestation in GDM dams on fetal intestinal immune development. OG was supplemented one week before mating until the end of the experiment. GDM rats were made with a high-fat diet (HFD) with a minimal streptozotocin (STZ) dose. The fetal intestines were sampled at gestation day (GD) 19.5, and the intestinal morphology, chemical barrier molecules, intraepithelial immune cell makers, and levels of inflammatory cytokines were investigated. The results showed that OG supplementation alleviated the decrease of the depth of fetal intestinal villi and crypts, the number of goblet cells (GCs), protein expression of mucin-1 (Muc1) and Muc2, the mRNA levels of Gpr41, Gpr43, and T cell markers, and increased the number of paneth cells (PCs), the mRNA levels of defensin-6 (defa6), and macrophage (Mø) marker and the expression of cytokines induced by GDM. In addition, OG supplementation alleviated the function of immune cell self-proliferation, chemotaxis and assembly capabilities, protein, fat, folic acid, and zinc absorption damaged by GDM. As indicated by these findings, OG supplementation before and during pregnancy improved the fetal intestinal chemical barriers, immune cells, cytokines, and the metabolism of nutrients to protect the fetal intestinal immunity.

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.

The Maternal-Fetal Gut Microbiota Axis: Physiological Changes, Dietary Influence, and Modulation Possibilities

The prenatal period and the first years of life have a significant impact on the health issues and life quality of an individual. The appropriate development of the immune system and the central nervous system are thought to be major critical determining events. In parallel to these, establishing an early intestinal microbiota community is another important factor for future well-being interfering with prenatal and postnatal developmental processes. This review aims at summarizing the main characteristics of maternal gut microbiota and its possible transmission to the offspring, thereby affecting fetal and/or neonatal development and health. Since maternal dietary factors are potential modulators of the maternal-fetal microbiota axis, we will outline current knowledge on the impact of certain diets, nutritional factors, and nutritional modulators during pregnancy on offspring's microbiota and health.

Establishment of tissue-resident immune populations in the fetus

The immune system establishes during the prenatal period from distinct waves of stem and progenitor cells and continuously adapts to the needs and challenges of early postnatal and adult life. Fetal immune development not only lays the foundation for postnatal immunity but establishes functional populations of tissue-resident immune cells that are instrumental for fetal immune responses amidst organ growth and maturation. This review aims to discuss current knowledge about the development and function of tissue-resident immune populations during fetal life, focusing on the brain, lung, and gastrointestinal tract as sites with distinct developmental trajectories. While recent progress using system-level approaches has shed light on the fetal immune landscape, further work is required to describe precise roles of prenatal immune populations and their migration and adaptation to respective organ environments. Defining points of prenatal susceptibility to environmental challenges will support the search for potential therapeutic targets to positively impact postnatal health.

Buttermilk: an important source of lipid soluble forms of choline that influences the immune system development in Sprague-Dawley rat offspring

PURPOSE

To determine the effect of feeding buttermilk-derived choline metabolites on the immune system development in Sprague-Dawley rat pups.

METHODS

Sprague-Dawley dams were randomized to one of the three diets containing 1.7 g/kg choline: 1-Control (100% free choline (FC)), 2-Buttermilk (BM, 37% phosphatidylcholine (PC), 34% sphingomyelin (SM), 17% glycerophosphocholine (GPC), 7% FC, 5% phosphocholine), and 3-Placebo (PB, 50% PC, 25% FC, 25% GPC) until the end of the lactation period. At weaning, pups continued on the same diet as their mom. Cell phenotypes and cytokine production by mitogen-stimulated splenocytes isolated from 3- and 10-week-old pups were measured.

RESULTS

At 3 weeks, BM-pups had a higher proportion of cytotoxic T cells (CTL; CD3 + CD8 +) while both BM- and PB-pups had an increased proportion of cells expressing CD28 + , CD86 + and CD27 + (all p > 0.05). Following ConA stimulation, splenocytes from BM- and PB-pups produced more TNF-α and IFN-γ and after LPS stimulation produced more IL-10 and TNF-α (all p > 0.05). Starting at week 6 of age, BM-pups had a higher body weight. At 10 weeks, both the BM- and PB-pups had a higher proportion of CTL expressing CD27 + . After ConA stimulation, splenocytes from BM- and PB-pups produced more IL-2, IFN-γ and IL-6 and more IL-10 after LPS stimulation (all p > 0.05).

CONCLUSION

The proportion of lipid soluble forms of choline in the diet during lactation and weaning periods influence the immune system development in rat offspring.

When a Neonate Is Born, So Is a Microbiota

In recent years, the role of human microbiota as a short- and long-term health promoter and modulator has been affirmed and progressively strengthened. In the course of one’s life, each subject is colonized by a great number of bacteria, which constitute its specific and individual microbiota. Human bacterial colonization starts during fetal life, in opposition to the previous paradigm of the “sterile womb”. Placenta, amniotic fluid, cord blood and fetal tissues each have their own specific microbiota, influenced by maternal health and habits and having a decisive influence on pregnancy outcome and offspring outcome. The maternal microbiota, especially that colonizing the genital system, starts to influence the outcome of pregnancy already before conception, modulating fertility and the success rate of fertilization, even in the case of assisted reproduction techniques. During the perinatal period, neonatal microbiota seems influenced by delivery mode, drug administration and many other conditions. Special attention must be reserved for early neonatal nutrition, because breastfeeding allows the transmission of a specific and unique lactobiome able to modulate and positively affect the neonatal gut microbiota. Our narrative review aims to investigate the currently identified pre- and peri-natal factors influencing neonatal microbiota, before conception, during pregnancy, pre- and post-delivery, since the early microbiota influences the whole life of each subject.

Early supplementation of Saccharomyces cerevisiae boulardii CNCM I-1079 in newborn dairy calves increases IgA production in the intestine at 1 week of age

The early development of immunity and microbiota in the gut of newborn calves can have life-long consequences. Gut microbiota and the intestinal barrier interplay after birth, establishing a homeostatic state whereby mucosal cells cohabit with microorganisms to develop a healthy gut. We hypothesized that postnatal codevelopment of gut immunity and microbiota could be influenced by early-life supplementation with live yeast. Starting from birth, calves either received a daily supplementation of Saccharomyces cerevisiae boulardii CNCM I-1079 (SCB, 10 × 10⁹ cfu/d, n = 10) in the morning meal for 7 d or no supplementation (n = 10). Each animal received 2 adequate colostrum replacer meals at 2 and 12 h of life (expected total IgG fed = 300 g) before being fed milk replacer twice a day. Passive transfer of immunity (total protein, IgG, and IgA) through colostrum was evaluated and endogenous production of IgA was investigated by measuring IgA-producing plasma cells, IgA relative gene expression (PIGR and CD79A), and secretory IgA concentration in the gut. The concentration of targeted microbial groups was evaluated with quantitative PCR in the gut digesta collected at d 7 of life. Early SCB supplementation did not impair immunoglobulin absorption and all calves had successful passive transfer of immunity (serum IgG concentration >15 mg/mL at d 1 and d 7 of age). Although the expression of IgA relative gene expression (PIGR and CD79A) was not different, SCB calves had higher secretory IgA concentrations in the ileum (1.98 ± 0.12 mg/g of dry matter; DM) and colon (1.45 ± 0.12 mg/g of DM) digesta compared with control animals (1.18 and 0.59 ± 0.12 mg/g of DM, respectively). In addition, the number of IgA-producing plasma cells were greater in both ileum (2.55 ± 0.40 cells/mm²) and colon (3.03 ± 0.40 cells/mm²) tissues for SCB calves compared with control (respectively 1.00 ± 0.40 and 0.60 ± 0.42 cells/mm²). Endogenous IgA production in the gut of SCB calves was enhanced, which could make them less prone to pathogen intrusion. In addition, SCB calves had higher Lactobacillus and tended to have higher Faecalibacterium prausnitzii in the jejunum compared with control calves, which suggests that SCB supplementation during early-life gut colonization may have a positive effect in newborn calves. Direct SCB supplementation or the cross-talk between SCB and bacteria may be responsible for stimulating IgA production and may play a key role in shaping early colonization in the gut of newborn calves.

B cells control maternofetal priming of allergy and tolerance in a murine model of allergic airway inflammation

BACKGROUND

Allergic asthma is a chronic lung disease resulting from inappropriate immune responses to environmental antigens. Early tolerance induction is an attractive approach for primary prevention of asthma.

OBJECTIVE

We analyzed the mechanisms of perinatal tolerance induction to allergens, with particular focus on the role of B cells in preconception and early intrauterine immune priming.

METHODS

Wild-type (WT) and B cell-deficient mice received ovalbumin (OVA) intranasally before mating. Their offspring were analyzed in a murine model of allergic airway inflammation.

RESULTS

Although antigen application before conception protected WT progeny from allergy, it aggravated allergic airway inflammation in B cell-deficient offspring. B-cell transfer restored protection, demonstrating the crucial role of B cells in perinatal tolerance induction. Effective diaplacentar allergen transfer was detectable in pregnant WT mice but not in pregnant B-cell knockout dams, and antigen concentrations in WT amniotic fluid (AF) were higher than in IgG-free AF of B cell-deficient dams. Application of OVA/IgG immune complexes during pregnancy boosted OVA uptake by fetal dendritic cells (DCs). Fetal DCs in human subjects and mice expressed strikingly higher levels of Fcγ receptors compared with DCs from adults and were highly efficient in taking up OVA/IgG immune complexes. Moreover, murine fetal DCs effectively primed antigen-specific forkhead box P3⁺ regulatory T cells after in vitro coincubation with OVA/IgG-containing AF.

CONCLUSION

Our data support a decisive role for B cells and immunoglobulins during in utero tolerance priming. These findings improve the understanding of perinatal immunity and might support the development of effective primary prevention strategies for allergy and asthma in the future.

The Importance of Human Milk for Immunity in Preterm Infants

The immune system of preterm infants is immature, placing them at increased risk for serious immune-related complications. Human milk provides a variety of immune protective and immune maturation factors that are beneficial to the preterm infant's poorly developed immune system. The most studied immune components in human milk include antimicrobial proteins, maternal leukocytes, immunoglobulins, cytokines and chemokines, oligosaccharides, gangliosides, nucleotides, and long-chain polyunsaturated fatty acids. There is growing evidence that these components contribute to the lower incidence of immune-related conditions in the preterm infant. Therefore, provision of these components in human milk, donor milk, or formula may provide immunologic benefits.

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-1β) 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.

Evidence for the essentiality of arachidonic and docosahexaenoic acid in the postnatal maternal and infant diet for the development of the infant’s immune system early in life

Long-chain polyunsaturated fatty acids (LCPUFA), especially the balance between arachidonic (AA) and docosahexaenoic (DHA) acids are known to have important immunomodulatory roles during the postnatal period when the immune system is rapidly developing. AA and DHA are required in infant formula in many countries but are optional in North America. The rationale for adding these LCPUFA to full-term formula is based on their presence in breast milk and randomized controlled studies that suggest improved cognitive function in preterm infants, but results are more variable in full-term infants. Recently, the European Food Safety Authority has proposed, based on a lack of functional evidence, that AA is not required in infant formula for full-term infants during the first year of life but DHA should remain mandatory. The purpose of this review is to review the evidence from epidemiological and intervention studies regarding the essentiality of AA and DHA in the postnatal infant and maternal diet (breast-feeding) for the immune system development early in life. Although studies support the essentiality of DHA for the immune system development, more research is needed to rule out the essentiality of AA. Nevertheless, intervention studies have demonstrated improvement in many markers of immune function in infants fed formula supplemented with AA and DHA compared with unsupplemented formula, which appears to consistently result in beneficial health outcomes including reduction in the risk of developing allergic and atopic disease early in life.

Initial symbiont contact orchestrates host-organ-wide transcriptional changes that prime tissue colonization

Upon transit to colonization sites, bacteria often experience critical priming that prepares them for subsequent, specific interactions with the host; however, the underlying mechanisms are poorly described. During initiation of the symbiosis between the bacterium Vibrio fischeri and its squid host, which can be observed directly and in real time, approximately five V. fischeri cells aggregate along the mucociliary membranes of a superficial epithelium prior to entering host tissues. Here, we show that these few early host-associated symbionts specifically induce robust changes in host gene expression that are critical to subsequent colonization steps. This exquisitely sensitive response to the host's specific symbiotic partner includes the upregulation of a host endochitinase, whose activity hydrolyzes polymeric chitin in the mucus into chitobiose, thereby priming the symbiont and also producing a chemoattractant gradient that promotes V. fischeri migration into host tissues. Thus, the host responds transcriptionally upon initial symbiont contact, which facilitates subsequent colonization.

Moderately preterm, late preterm and early term infants: research needs

In spite of increased appreciation that all preterm infants and early term infants are at higher risk for mortality and morbidities compared with their term counterparts, there are many knowledge gaps affecting optimal clinical care for this vulnerable population. This article presents a research agenda focusing on the systems biology, epidemiology, and clinical and translational sciences on this topic.

Maternal dietary fatty acid intake during pregnancy and the risk of preclinical and clinical type 1 diabetes in the offspring

The aim of the present study was to examine the associations between the maternal intake of fatty acids during pregnancy and the risk of preclinical and clinical type 1 diabetes in the offspring. The study included 4887 children with human leucocyte antigen (HLA)-conferred type 1 diabetes susceptibility born during the years 1997–2004 from the Finnish Type 1 Diabetes Prediction and Prevention Study. Maternal diet was assessed with a validated FFQ. The offspring were observed at 3- to 12-month intervals for the appearance of type 1 diabetes-associated autoantibodies and development of clinical type 1 diabetes (average follow-up period: 4·6 years (range 0·5–11·5 years)). Altogether, 240 children developed preclinical type 1 diabetes and 112 children developed clinical type 1 diabetes. Piecewise linear log-hazard survival model and Cox proportional-hazards regression were used for statistical analyses. The maternal intake of palmitic acid (hazard ratio (HR) 0·82, 95 % CI 0·67, 0·99) and high consumption of cheese during pregnancy (highest quarter v. intermediate half HR 0·52, 95 % CI 0·31, 0·87) were associated with a decreased risk of clinical type 1 diabetes. The consumption of sour milk products (HR 1·14, 95 % CI 1·02, 1·28), intake of protein from sour milk (HR 1·15, 95 % CI 1·02, 1·29) and intake of fat from fresh milk (HR 1·43, 95 % CI 1·04, 1·96) were associated with an increased risk of preclinical type 1 diabetes, and the intake of low-fat margarines (HR 0·67, 95 % CI 0·49, 0·92) was associated with a decreased risk. No conclusive associations between maternal fatty acid intake or food consumption during pregnancy and the development of type 1 diabetes in the offspring were detected.

Neonatal immune adaptation of the gut and its role during infections

The intestinal tract is engaged in a relationship with a dense and complex microbial ecosystem, the microbiota. The establishment of this symbiosis is essential for host physiology, metabolism, and immune homeostasis. Because newborns are essentially sterile, the first exposure to microorganisms and environmental endotoxins during the neonatal period is followed by a crucial sequence of active events leading to immune tolerance and homeostasis. Contact with potent immunostimulatory molecules starts immediately at birth, and the discrimination between commensal bacteria and invading pathogens is essential to avoid an inappropriate immune stimulation and/or host infection. The dysregulation of these tight interactions between host and microbiota can be responsible for important health disorders, including inflammation and sepsis. This review summarizes the molecular events leading to the establishment of postnatal immune tolerance and how pathogens can avoid host immunity and induce neonatal infections and sepsis.

Meconium microbiota types dominated by lactic acid or enteric bacteria are differentially associated with maternal eczema and respiratory problems in infants

BACKGROUND

Culture-dependent methods have shown that meconium, the newborn's first intestinal discharge, is not sterile, but the diversity of bacteria present in this material needs to be further characterized by means of more sensitive molecular techniques.

OBJECTIVE

Our aims were to characterize molecularly the meconium microbiota in term infants, to assess whether it contributes to the future microbiota of the infants' gastrointestinal tract, and to evaluate how it relates to lifestyle variables and atopy-related conditions.

METHODS

We applied high-throughput pyrosequencing of the 16S rRNA gene to study the meconium microbiota in twenty term newborns from a Spanish birth cohort. For comparison, we characterized the microbiota in fecal samples from seven pregnant women days before delivery and in two series of infant samples spanning the first seven months of life. We also compared our data with vaginal and skin microbiota characterized in independent studies. Different types of meconium microbiota were defined based on taxonomic composition and abundance and their associations with different factors were statistically evaluated.

RESULTS

The meconium microbiota differs from those in adult feces, vagina and skin, but resembles that of fecal samples from young infants. Meconium samples clustered into two types with different bacterial diversity, richness and composition. One of the types was less diverse, dominated by enteric bacteria and associated with a history of atopic eczema in the mother (P = 0.038), whereas the second type was dominated by lactic acid bacteria and associated with respiratory problems in the infant (P = 0.040).

CONCLUSIONS & CLINICAL RELEVANCE

Our findings suggest that the meconium microbiota has an intrauterine origin and participates in gut colonization. Although based on a small population sample, our association analyses also suggest that the type of bacteria detected in meconium is influenced by maternal factors and may have consequences for childhood health.

Developmental physiology of late and moderate prematurity

This is a brief review of the developmental physiology of selected organ and functional systems in moderate and late preterm infants. This outline provides a discussion of the physiological underpinnings for some of the clinical conditions seen in this group of infants, including hypothermia, hypoglycemia, respiratory distress syndrome, transient tachypnea, severe respiratory failure, apnea, feeding difficulties, jaundice, and increased susceptibility to infections.

The impact of perinatal immune development on mucosal homeostasis and chronic inflammation

The mucosal surfaces of the gut and airways have important barrier functions and regulate the induction of immunological tolerance. The rapidly increasing incidence of chronic inflammatory disorders of these surfaces, such as inflammatory bowel disease and asthma, indicates that the immune functions of these mucosae are becoming disrupted in humans. Recent data indicate that events in prenatal and neonatal life orchestrate mucosal homeostasis. Several environmental factors promote the perinatal programming of the immune system, including colonization of the gut and airways by commensal microorganisms. These complex microbial-host interactions operate in a delicate temporal and spatial manner and have an important role in the induction of homeostatic mechanisms.

Alternative memory in the CD8 T cell lineage

A prominent population of innate CD8+ T cells develops in the thymus of several gene-deficient mouse strains, including Itk, KLF2, CBP and Id3. These cells have the phenotype and function of memory CD8+ T cells, without previous exposure to antigen. Surprisingly, the cytokine IL-4 plays a key role in their development. As this developmental mechanism was discovered, it came to light that innate CD8+ T cells exist also in normal mice and in humans. In this review, we discuss how these cells develop, compare and contrast them to other CD8 memory cells, and discuss their potential physiological relevance.

Is there any relationship between cytokine spectrum of breast milk and occurence of eosinophilic colitis?

AIM

The aim of our study was to analyse cytokine composition of human milk and its relationship to the development of eosinophilic colitis (EC).

METHODS

Cytokines were measured by ELISA method in breast milk of 20 mothers of infants who developed EC and 20 controls.

RESULTS

We found significantly higher concentrations of interferon-gamma (IFN-gamma) (Th1 cytokine) in breast milk received by EC infants compared to controls (p = 0.0004). In contrary, IL-18 (Th1-inducing cytokine) was significantly higher in breast milk received by healthy infants comparing to EC infants (p = 0.001). Regulatory cytokine transforming growth factor beta1 (TGF-beta1) showed higher concentrations in breast milk received by healthy infants, although the difference from EC group was not significant (p = 0.072).

CONCLUSION

The results of our study showed that infants with EC were receiving breast milk with a possibly risky cytokine pattern indicating cytokine imbalance, impaired immunoregulation and the early Th1 shift.

Potentiation of polarized intestinal Caco-2 cell responsiveness to probiotics complexed with secretory IgA

The precise mechanisms underlying the interaction between intestinal bacteria and the host epithelium lead to multiple consequences that remain poorly understood at the molecular level. Deciphering such events can provide valuable information as to the mode of action of commensal and probiotic microorganisms in the gastrointestinal environment. Potential roles of such microorganisms along the privileged target represented by the mucosal immune system include maturation prior, during and after weaning, and the reduction of inflammatory reactions in pathogenic conditions. Using human intestinal epithelial Caco-2 cell grown as polarized monolayers, we found that association of a Lactobacillus or a Bifidobacterium with nonspecific secretory IgA (SIgA) enhanced probiotic adhesion by a factor of 3.4-fold or more. Bacteria alone or in complex with SIgA reinforced transepithelial electrical resistance, a phenomenon coupled with increased phosphorylation of tight junction proteins zonula occludens-1 and occludin. In contrast, association with SIgA resulted in both enhanced level of nuclear translocation of NF-κB and production of epithelial polymeric Ig receptor as compared with bacteria alone. Moreover, thymic stromal lymphopoietin production was increased upon exposure to bacteria and further enhanced with SIgA-based complexes, whereas the level of pro-inflammatory epithelial cell mediators remained unaffected. Interestingly, SIgA-mediated potentiation of the Caco-2 cell responsiveness to the two probiotics tested involved Fab-independent interaction with the bacteria. These findings add to the multiple functions of SIgA and underscore a novel role of the antibody in interaction with intestinal bacteria.

Prophylactic role of maternal administration of probiotics in the prevention of irritable bowel syndrome

Neonatal stress is a common early life event which alters the development of the endocrine and immune systems. Specifically, exposure to neonatal stress results in alterations to the hypothalamic-pituitary-adrenal (HPA) axis resulting in offspring who hyper-respond to stress in adulthood. Recently, this concept has been applied to the ontogeny of functional gastrointestinal (GI) disturbances such as irritable bowel syndrome (IBS). The high prevalence of this disorder and the ineffectiveness of current treatments results in high direct and indirect costs to the society. Recently, administration of probiotics to neonates has been used as a safe and cost-effective preventative strategy to revoke the long term unfavourable imprinting induced on the gastrointestinal system by early life stressors in animal models of human IBS. It is not as yet known however, whether maternal supplementary probiotics may also contribute to improved GI integrity and gut-associated immune functioning in stressed neonates, if these possible improvements persist into adulthood, or how this protective effect may be mediated. Our hypothesis is an attempt to link this proposed nutritional approach and its possible preventive effects against GI dysfunctions provoked by neonatal stress.

Dietary-dependent trans-generational immune priming in an insect herbivore

Trans-generational effects on immunity are well known in vertebrates and are considered in many evolutionary and ecological theories of species interaction. Maternal effects have been identified to be of special importance, and are now recognized as a mechanism for adaptive phenotypic response to environmental heterogeneity. We have previously shown that exposure to dietary non-pathogenic bacteria can induce several aspects of immune response in an insect herbivore, the cabbage semilooper (Trichoplusia ni). Here, we test the effects of this exposure on the immune status of the next generation, measuring immune parameters on three different levels-enzyme activities, protein expression and transcript abundance. We also monitored fitness-related traits which are often negatively correlated with increased immunocompetence. We found evidence for trans-generational priming on all these levels, with immune system parameters that are clearly not transmitted in a 1 : 1 ratio from parent to offspring, but rather in a complex manner with a strong but not exclusive maternal component. These findings indicate that trans-generational priming is a complex and multifaceted phenomenon, potentially playing a role as a long-term but non-genetic mode of environmental adaptation.

Early-life environment, developmental immunotoxicology, and the risk of pediatric allergic disease including asthma

Incidence of childhood allergic disease including asthma (AD-A) has risen since the mid-20th century with much of the increase linked to changes in environment affecting the immune system. Childhood allergy is an early life disease where predisposing environmental exposures, sensitization, and onset of symptoms all occur before adulthood. Predisposition toward allergic disease (AD) is among the constellation of adverse outcomes following developmental immunotoxicity (DIT; problematic exposure of the developing immune system to xenobiotics and physical environmental factors). Because novel immune maturation events occur in early life, and the pregnancy state itself imposes certain restrictions on immune functional development, the period from mid-gestation until 2 years after birth is one of particular concern relative to DIT and AD-A. Several prenatal-perinatal risk factors have been identified as contributing to a DIT-mediated immune dysfunction and increased risk of AD. These include maternal smoking, environmental tobacco smoke, diesel exhaust and traffic-related particles, heavy metals, antibiotics, environmental estrogens and other endocrine disruptors, and alcohol. Diet and microbial exposure also significantly influence immune maturation and risk of allergy. This review considers (1) the critical developmental windows of vulnerability for the immune system that appear to be targets for risk of AD, (2) a model in which the immune system of the DIT-affected infant exhibits immune dysfunction skewed toward AD, and (3) the lack of allergy-relevant safety testing of drugs and chemicals that could identify DIT hazards and minimize problematic exposure of pregnant women and children.

What’s So Special about the Developing Immune System?

The evolution of the subdiscipline of developmental immunotoxicology (DIT) as it exists today has been shaped by significant regulatory pressures as well as key scientific advances. This review considers the role played by legislation to protect children’s health, and on the emergence of immunotoxcity and developmental immunotoxicity guidelines, as well as providing some context to the need for special attention on DIT by considering the evidence that the developing immune system may have unique susceptibilities when compared to the adult immune system. Understanding the full extent of this potential has been complicated by a paucity of data detailing the development of the immune system during critical life stages as well as by the complexities of comparisons across species. Notably, there are differences between humans and nonhuman species used in toxicity testing that include specific differences relative to the timing of the development of the immune system as well as more general anatomic differences, and these differences must be factored into the interpretation of DIT studies. Likewise, understanding how the timing of the immune development impacts on various immune parameters is critical to the design of DIT studies, parameters most extensively characterized to date in young adult animals. Other factors important to DIT, which are considered in this review, are the recognition that effects other than suppression (e.g., allergy and autoimmunity) are important; the need to improve our understanding of how to assess the potential for DIT in humans; and the role that pathology has played in DIT studies in test animals. The latter point receives special emphasis in this review because pathology evaluations have been a major component of standard nonclinical toxicology studies, and could serve an important role in studies to evaluate DIT. This possibility is very consistent with recommendations to incorporate a DIT evaluation into standard developmental and reproductive toxicology (DART) protocols. The overall objective of this review is to provide a ‘snapshot’ of the current state-of-the-science of DIT. Despite significant progress, DIT is still evolving and it is our hope that this review will advance the science.