The development of the mucosal immune system pre- and post-weaning: balancing regulatory and effector function

Human colostrum oligosaccharides modulate major immunologic pathways of immature human intestine

The immature neonatal intestinal immune system hyperreacts to newly colonizing unfamiliar bacteria. The hypothesis that human milk oligosaccharides from colostrum (cHMOSs) can directly modulate the signaling pathways of the immature mucosa was tested. Modulation of cytokine immune signaling by HMOSs was measured ex vivo in intact immature (fetal) human intestinal mucosa. From the genes whose transcription was modulated by cHMOSs, Ingenuity Pathway Analysis identified networks controlling immune cell communication, intestinal mucosal immune system differentiation, and homeostasis. cHMOSs attenuate pathogen-associated molecular pattern-stimulated acute phase inflammatory cytokine protein levels (interleukin-8 (IL-8), IL-6, monocyte chemoattractant protein-1/2 and IL-1β), while elevating cytokines involved in tissue repair and homeostasis. In all, 3'-, 4-, and 6'-galactosyllactoses of cHMOSs account for specific immunomodulation of polyinosinic:polycytodylic acid-induced IL-8 levels. cHMOSs attenuate mucosal responses to surface inflammatory stimuli during early development, while enhancing signals that support maturation of the intestinal mucosal immune system.

Temporal changes and the effect of subtherapeutic concentrations of antibiotics in the gut microbiota of swine

The use of antibiotics in swine production for the purpose of growth promotion dates back to the 1950s. Despite this long history of use, the exact mechanism(s) responsible for the growth-promoting effects of antibiotics in swine remain largely unknown. It is believed, however, that growth promotion is due to antibiotics having a direct impact on the gut microbiota. In this study, the effect of two antibiotics on the swine gut microbiota over a 19-week monitoring period was investigated using Illumina-based sequencing. A shift in the relative abundance of several taxa and in 26 operational taxonomic units (OTUs) was observed in pigs fed subtherapeutic concentrations of tylosin (44-11 mg kg(-1) feed). Only minor alterations were noted with the administration of chlortetracycline at 5.5 mg kg(-1) feed. The most notable changes in the relative abundance of taxa and OTUs were noted between suckling piglets and postweaned pigs. Diversity was also reduced in the gut microbiota of suckling piglets as measured using the Shannon, Chao1, and phylogenetic diversity indices. These results show that the effect of antibiotics on the swine gut microbiota is variable based on dosage and duration and that the swine gut microbiota exhibits considerable resilience to long-term changes due to antibiotic perturbations.

Modulatory effects of vasoactive intestinal peptide on intestinal mucosal immunity and microbial community of weaned piglets challenged by an enterotoxigenic Escherichia coli (K88)

Toll-like receptors (TLRs) recognize microbial pathogens and trigger immune response, but their regulation by neuropeptide-vasoactive intestinal peptide (VIP) in weaned piglets infected by enterotoxigenic Escherichia coli (ETEC) K88 remains unexplored. Therefore, the study was conducted to investigate its role using a model of early weaned piglets infected by ETEC K88. Male Duroc×Landrace×Yorkshire piglets (n = 24) were randomly divided into control, ETEC K88, VIP, and ETEC K88+VIP groups. On the first three days, ETEC K88 and ETEC K88+VIP groups were orally administrated with ETEC K88, other two groups were given sterile medium. Then each piglet from VIP and ETEC K88+VIP group received 10 nmol VIP intraperitoneally (i.p.) once daily, on day four and six. On the seventh day, the piglets were sacrificed. The results indicated that administration of VIP improved the growth performance, reduced diarrhea incidence of ETEC K88 challenged pigs, and mitigated the histopathological changes of intestine. Serum levels of IL-2, IL-6, IL-12p40, IFN-γ and TNF-α in the ETEC K88+ VIP group were significantly reduced compared with those in the ETEC group. VIP significantly increased IL-4, IL-10, TGF-β and S-IgA production compared with the ETEC K88 group. Besides, VIP could inhibit the expression of TLR2, TLR4, MyD88, NF-κB p65 and the phosphorylation of IκB-α, p-ERK, p-JNK, and p-38 induced by ETEC K88. Moreover, VIP could upregulate the expression of occludin in the ileum mucosa compared with the ETEC K88 group. Colon and caecum content bacterial richness and diversity were lower for pigs in the ETEC group than the unchallenged groups. These results demonstrate that VIP is beneficial for the maturation of the intestinal mucosal immune system and elicited local immunomodulatory activities. The TLR2/4-MyD88 mediated NF-κB and MAPK signaling pathway may be critical to the mechanism underlying the modulatory effect of VIP on intestinal mucosal immune function and bacterial community.

Influences of phytoncide supplementation on growth performance, nutrient digestibility, blood profiles, diarrhea scores and fecal microflora shedding in weaning pigs

A total of 140 weaning pigs ((Landrace×Yorkshire)×Duroc, BW = 6.47±0.86 kg) were used in a 5-wk growth trail to determine the effects of phytoncide supplementation on growth performance, nutrient apparent total tract digestibility (ATTD), blood profiles, diarrhea scores and fecal microflora shedding. Pigs were assigned randomly by BW into 5 treatments, dietary treatments were: i) NC, basal diet; ii) PC, NC+0.05% tylosin; iii) EO, NC+0.1% essential oil; iv) PP, NC+0.2% PP (phytoncide with 2% citric acid), and v) PA, NC+0.2% PA (phytoncide). Each treatment had 7 replicate pens with 4 pigs per pen. All pigs were housed in pens with a self-feeder and nipple drinker to allow ad libitum access to feed and water throughout the experimental period. During 0 to 2 wks, supplementation with essential oil and PA decreased (p<0.05) G/F compared with the other treatments. During 2 to 5 wks, supplementation with PA led to a higher (p<0.05) G/F than the other treatments. At 2 wk, ATTD of dry matter (DM) and gross energy (GE) in EO treatment were decreased (p<0.05) compared with NC treatment. Dietary PC treatment improved (p<0.05) ATTD of DM and E compared with the CON group, and PA and PP treatments showed a higher (p<0.05) ATTD of E than that in NC treatment. Pigs fed phytoncide (PA and PP) had a greater (p<0.05) ATTD of DM than those of NC and EO treatments at 5 wk. Moreover, supplementation with phytoncide elevated (p<0.05) the concentration of immunoglobulin (IgG) in blood at 2 wk. The inclusion of EO, PP and PA treatments showed a greater (p<0.05) amount of fecal Lactobacillus compared with CON group. However, no difference (p>0.05) was observed in diarrhea scores among treatments. In conclusion, phytoncide can elevate feed efficiency, nutrient digestibility, and improve the fecal Lactobacillus counts in weaning pigs. Our results indicated that the phytoncide could be used as a good antibiotics alternative in weaning pigs.

Breastfeeding and introduction of complementary foods during infancy in relation to the risk of asthma and atopic diseases up to 10 years

BACKGROUND

It has been hypothesized that changes in diet during early life may have contributed to the increase in childhood asthma and atopy. The long-term effect of the timing and content of infant feeding on the incidence of asthma and atopic diseases in children is unclear.

OBJECTIVE

To investigate the associations between duration of breastfeeding and the timing of introduction of complementary foods during the first 6 months and parental-reported asthma, wheeze and atopic eczema up to 10 years of age.

METHODS

Infant feeding practices (breastfeeding and introduction of complementary foods) of 1924 singleton children participating in the Study of Eczema and Asthma To Observe the influence of Nutrition (SEATON) birth cohort were prospectively collected up to 6 months with outcomes (wheeze, atopic eczema and asthma) being assessed at 1, 2, 5 and 10 years. Data were analysed using generalized estimating equations and discrete hazards models with adjustment for confounders.

RESULTS

By 6 months, 59% and 35% of mothers had stopped exclusive and total breastfeeding, respectively. Although formula feeding was adversely associated with wheeze in the past 12 months (adjusted OR for no formula feeding: 070, 95% CI 0.50-0.97), and the introduction of biscuits/bread after 5 months of age adversely associated with atopic eczema (adjusted OR 1.34, 95% CI 1.06-1.69), these results lost their statistical significance after adjustment for multiple testing. Stratification of the results by the presence of eczema by 6 months of age and family atopic history did not substantially differ from the results of the whole study population.

CONCLUSION AND CLINICAL RELEVANCE

Our results suggest that the nature of infant feeding during the first 6 months seems not to substantially influence the long-term risk of asthma and atopic diseases in children, nor in children at high risk of atopic disease because of a family history of atopic disease.

Grape seed extract supplementation attenuates the heat stress-induced responses of jejunum epithelial cells in Simmental × Qinchuan steers

Grape seed extract (GSE), a rich source of polyphenols, is reported to possess antioxidant, anti-inflammatory and immunomodulatory properties. The objective of the present study was to determine whether GSE could attenuate the heat stress-induced responses of jejunum epithelial cells (JEC) in cattle. The JEC of a steer (Simmental × Qinchuan) were exposed to heat stress for 2 h in the absence (0 μg/ml) or presence (10, 20, 40 and 80 μg/ml) of GSE in the culture medium. When cultured at 40°C, JEC supplemented with GSE exhibited increased glutathione peroxidase activity (P= 0·04), viability (P= 0·004), and mRNA expression of epidermal growth factor (EGF; P= 0·03) and EGF receptor (EGFR; P = 0·01). Under the same conditions, the cells exhibited decreased mRNA expression of IL-8 (P= 0·01) and TNF-α (P= 0·03) and decreased protein concentrations of IL-1β (P= 0·02), Toll-like receptor 4 (TLR4; P= 0·04) and heat shock protein 70 (HSP70; P< 0·001). When cultured at 43°C, JEC supplemented with GSE exhibited increased catalase activity (P= 0·04), viability (P< 0·001), and mRNA expression of EGF (P< 0·001) and EGFR (P< 0·001) and decreased protein concentrations of IL-1β (P< 0·001), TLR4 (P= 0·03) and HSP70 (P< 0·001), as well as mRNA expression of IL-8 (P< 0·001), TLR4 (P= 0·002) and TNF-α (P< 0·001). Temperature × GSE concentration interactions were also observed for the concentrations of IL-1β (P< 0·001), IL-8 (P< 0·001), TNF-α (P= 0·01) and HSP70 (P= 0·04) and viability (P< 0·001) of JEC. The results of the present study indicate that GSE can attenuate the responses of JEC induced by heat stress within a certain range of temperatures.

Development of gut immunoglobulin A production in piglet in response to innate and environmental factors

The current review focuses on pre- and post-natal development of intestinal immunoglobulin A (IgA) production in pig. IgA production is influenced by intrinsic genetic factors in the foetus as well as extrinsic environmental factors during the post-natal period. At birth, piglets are exposed to new antigens through maternal colostrums/milk as well as exogenous microbiota. This exposure to new antigens is critical for the proper development of the gut mucosal immune system and is characterized mainly by the establishment of IgA response. A second critical period for neonatal intestinal immune system development occurs at weaning time when the gut environment is exposed to new dietary antigens. Neonate needs to establish oral tolerance and in the absence of protective milk need to fight potential new pathogens. To improve knowledge about the immune response in the neonates, it is important to identify intrinsic and extrinsic factors which influence the intestinal immune system development and to elucidate their mechanism of action.

Food diversity in infancy and the risk of childhood asthma and allergies

BACKGROUND

Recently, the bacterial diversity of the intestinal flora and the diversity of various environmental factors during infancy have been linked to the development of allergies in childhood. Food is an important environmental exposure, but the role of food diversity in the development of asthma and allergies in childhood is poorly defined.

OBJECTIVE

We studied the associations between food diversity during the first year of life and the development of asthma and allergies by age 5 years.

METHODS

In a Finnish birth cohort we analyzed data on 3142 consecutively born children. We studied food diversity at 3, 4, 6, and 12 months of age. Asthma, wheeze, atopic eczema, and allergic rhinitis were measured by using the International Study of Asthma and Allergies in Childhood questionnaire at age 5 years.

RESULTS

By 3 and 4 months of age, food diversity was not associated with any of the allergic end points. By 6 months of age, less food diversity was associated with increased risk of allergic rhinitis but not with the other end points. By 12 months of age, less food diversity was associated with increased risk of any asthma, atopic asthma, wheeze, and allergic rhinitis.

CONCLUSION

Less food diversity during the first year of life might increase the risk of asthma and allergies in childhood. The mechanisms for this association are unclear, but increased dietary antigen exposure might contribute to this link.

Short- and medium-chain fatty acids as a feed supplement for weaning and nursery pigs

The effect of supplementing piglet diets with acidifiers containing the short-chain fatty acids - SCFA (propionic C3 and formic) together with medium-chain fatty acids - MCFA (caprylic C8 and capric C10) on performance, nutrient apparent digestibility, intestinal microflora and small intestine structure was investigated. The study was performed on 326 piglets allocated to 5 experimental groups. They were fed a standard diet (Group I - control) or a standard diet supplemented with 0.5% propionic and formic acids (Group II - PF). Group III (PF + C8), group IV (PF + C10) and group V (PF + C8 + C10) received the same mixture as group II with a supplement of 0.2% of caprylic and/or capric acids, respectively. Apparent digestibility of nutrients and microbiological analyses were performed. The structure of jejunum mucosa was also examined. Piglets receiving capric acid (groups IV and V) had the highest body weight gains. Piglets receiving MCFA digested protein and fiber better (P≤0.05) than piglets receiving SCFA as acidifier. There was no difference in intestinal microflora except for Clostridium perfringens, the population of which was reduced by SCFA (group II). Villi of the mucosal epithelium were the highest (P ≤ 0.05) in piglets receiving SCFA with capric acid (group IV). Under the conditions of this study a mixture of SCFA (propionic and formic) with capric acid significantly improves performance of piglets.

MicroRNA transcriptome in swine small intestine during weaning stress

MicroRNAs (miRNAs) play important roles in intestinal diseases; however, the role of miRNAs during weaning stress is unknown. In our study, six jejunal small RNA libraries constructed from weaning piglets at 1, 4 and 7 d after weaning (libraries W1, W4 and W7, respectively) and from suckling piglets on the same days as the weaning piglets (libraries S1, S4 and S7, respectively) were sequenced using Solexa high-throughput sequencing technology. Overall, 260 known swine miRNAs and 317 novel candidate miRNA precursors were detected in the six libraries. The results revealed that 16 differentially expressed miRNAs were found between W1 and S1; 98 differentially expressed miRNAs were found between W4 and S4 (ssc-mir-146b had the largest difference); and 22 differentially expressed miRNAs were found between W7 and S7. Sequencing miRNA results were validated using RT-qPCR. Approximately 11,572 miRNA-mRNA interactions corresponding to 3,979 target genes were predicted. The biological analysis further describe that the differentially expressed miRNAs regulated small intestinal metabolisms, stressful responses and immune functions in piglets. Therefore, the small intestine miRNA transcriptome was significantly different between weaning and suckling piglets; the difference varied with the number of days after weaning.

Age-related expression of the polymeric immunoglobulin receptor (pIgR) in the gastric mucosa of young pigs

To date few studies have addressed the development and function of the porcine gastric mucosal immune system and this is a major limitation to understanding the immunopathogenesis of infections occurring in young pigs. The polymeric immunoglobulin receptor (pIgR) mediates the transport of secretory immunoglobulins until luminal surface of the gut mucosa and the aim of this study was to investigate the time course of pIgR expression and to determine its localization in three functionally different porcine gastric sites during the suckling period and after weaning. An additional goal was to investigate the time course expression of toll-like receptors (TLRs) in relation to pIgR expression. Gastric samples were collected from the cardiac-to-oxyntic transition (Cd), the oxyntic (Ox), and the pyloric (Py) regions in 84 pigs, slaughtered before weaning (14, 21 and 28 days of age; 23, 23 and 19 pigs, respectively) and 14 days post-weaning (42 days of age, 23 pigs). PIgR was expressed in the mucosa of all the three gastric sites, and its transcript levels were modulated during suckling and after weaning, with regional differences. PIgR expression increased linearly during suckling (P=0.019) and also increased post-weaning (P=0.001) in Cd, it increased post-weaning in Py (P=0.049) and increased linearly during suckling in Ox (P=0.036). TLRs expression was also modulated during development: in Cd, TLR2 increased linearly during suckling (P=0.003); in Ox, TLR2 decreased after weaning (P=0.038) while TLR4 increased linearly during suckling(P=0.008). The expression of TLR2, 3 and 4 in Ox was positively correlated with pIgR expression (P<0.001).

Importantly, both pIgR protein and mRNA were localized, by immunohistochemistry and in situ hybridization, respectively, in the gastric glands of the lamina propria. These results indicate that pIgR is actively synthesized in the gastric mucosa and suggest that pIgR could play a crucial role in gastric mucosal immune defense of growing pigs.

Effect of polyoxyethylene and polyoxypropylene nonionic block copolymers on performance and recruitment of immune cell subsets in weaned pigs

BACKGROUND

Because European-wide directives are restricting the non-clinical use of antibiotics as in-feed growth promotors in swine production, there is an intensive search for alternative strategies for control and prevention of losses among young pigs. With the growing knowledge of the porcine immune system and its endogenous modulation, it has been clearly established that exogenous immunomodulation using adjuvants and immune response modifiers (IRMs) represents an important prophylactic/therapeutic approach in the prevention/treatment of both stress- and microbial-induced disorders that accompaning weaning. However, it is essential to select a fully evaluated agent which may act either as a nonspecific IRM or synergistically as an adjuvant with vaccines. The synthetic macromolecules with a long history as adjuvant and IRM are nonionic block copolymers which consist of polyoxyethylene (POE) and polyoxypropylene (POP) molecules.

METHODS

The aim of this work was to evaluate the effectiveness of POE-POP given as a single peroral dose on productivity parameters such as body weight gain, feed intake and feed conversion ratio, and systemic and intestinal immune parameters by assessing the proportions of CD45+ lymphoid cells, CD4+ and CD8+ T cells, and CD21+ B cells in the peripheral blood as well as the number of CD45RA+ naive lymphoid cells residing in the ileal mucosa in weaned pigs during a follow-up study 5 weeks after the treatment.

RESULTS

Pigs treated with POE-POP had better feed intake (+ 14.57%), higher average body mass at the end of the experiment (20.91 kg vs. 17.61 kg), and higher body weight gain in relation to Day 0 (191.63% vs. 144.58%) as well as in relation to nontreated pigs (+ 18.74%), with a lower feed conversion ratio (- 30.26%) in comparison to the control pigs. A much lower diarrhea severity score (5 vs. 54) was recorded in pigs treated with POE-POP (- 90.74%) than in the control pigs. A higher average diarrhea severity (ADS) was recorded in the control pigs (1.54 vs. 0.14), whereas the treatmant group had much a lower ADS ratio (- 90.91%) after 35 days of the experiment. The pigs that were treated with POE-POP had an increased proportion of CD45+, CD4+ and CD8+ cells at Day 21 (at p < 0.05, p < 0.05 or p < 0.01, respectively), Day 28 (at p < 0.01, respectively) and Day 35 (at p < 0.01, p < 0.05 or p < 0.01, respectively) as well as of CD21+ cells at Day 28 (p < 0.05) and Day 35 of the experiment (p < 0.01). Also, these pigs had more numerous CD45RA+ cells in interfollicular (p < 0.05) and follicular areas (p < 0.01) of the ileal Peyer's patches than did control pigs.

CONCLUSION

This property of POE-POP to induce recruitment of circulating and intestinal immune cell subsets in weaned pigs may allow the use of IRM-active block copolymers as adjuvants for vaccines, particularly those orally delivered and targeted to the gut-associated lymphoid tissues that are well known to promote rather tolerogenic than protective immune responses.

Heated allergens and induction of tolerance in food allergic children

Food allergies are one of the first manifestations of allergic disease and have been shown to significantly impact on general health perception, parental emotional distress and family activities. It is estimated that in the Western world, almost one in ten children have an IgE-mediated allergy. Cow's milk and egg allergy are common childhood allergies. Until recently, children with food allergy were advised to avoid all dietary exposure to the allergen to which they were sensitive, in the thought that consumption would exacerbate their allergy. However, recent publications indicate that up to 70% of children with egg allergy can tolerate egg baked in a cake or muffin without apparent reaction. Likewise, up to 75% of children can tolerate baked goods containing cow's milk, and these children demonstrate IgE and IgG4 profiles indicative of tolerance development. This article will review the current literature regarding the use of heated food allergens as immunotherapy for children with cow's milk and egg allergy.

Mucosal immunology and probiotics

The cross-talk between the mucosa-associated immune system and microbiota is critical in mucosal tissue homeostasis as well as in protection against infectious and inflammatory diseases occurring at mucosal sites. This recent evidence has paved the way to therapeutic approaches aimed at modulating the mucosa-associated immune system using probiotics. Different strains of probiotics possess the ability to finely regulate dendritic cell (DC) activation, polarizing the subsequent T cell activity toward Th1 (e.g. Lactobacillus (Lb) acidophilus), Th2 (Lb.reuteri and Bifidobacterium bifidum) or, as more recently demonstrated, Th17 responses induced by specific strains such as Lb.rhamnosus GG and Lac23a, the latter isolated in our laboratory. Here, we review some recent advances in our understanding of probiotics effects on mucosal immunology, particularly on cells of the innate immunity such as DCs. We also highlight our own experiences in modulating DC functions by commensal bacteria and discuss the relevance of probiotics administration in the treatment of human immunopathologies.

Serological profiles in nursery piglets colonized with Staphylococcus aureus

At present, the immune response of pigs in relation to Staphylococcus aureus carriage is poorly understood. This study was aimed at investigating the dynamics of the anti-staphylococcal humoral immune response in methicillin-susceptible S. aureus (MSSA)-positive piglets and at assessing the effect of the experimental introduction of a methicillin-resistant S. aureus (MRSA) Sequence Type (ST) 398 strain. Therefore, serum samples were collected at different times from 31 weaned piglets originating from four different sows. Twenty-four out of the 31 piglets were challenged with MRSA ST398. The serum samples were analyzed for IgG antibodies to 39 S. aureus antigens, using a multiplex bead-based assay (xMAP technology, Luminex Corporation). Though antibody responses showed broad inter-individual variability, serological results appeared to be clustered by litter of origin. For most antigens, an age-related response was observed with an apparent increase in antibody titers directed against staphylococcal microbial surface components recognizing adhesive matrix molecules (MSCRAMM), which have been shown to play a role in S. aureus colonization. In most animals, antibody titers directed against staphylococcal toxins or immune-modulating proteins decreased with age, possibly reflecting the absence of bacterial invasion. The introduction of MRSA ST398 did not elicit a significant humoral immune reaction.

This study describes, for the first time, the humoral immune response in weaned pigs colonized with S. aureus.

Spray-dried porcine plasma and yeast derived protein meal influence the adaption to weaning of primiparous and multiparous sow progeny in different ways

Pigs from 154 litters (n = 1132, 19 ± 3 days of age, 4.9 ± 1.1 kg of bodyweight) were used in a 3 × 2 factorial design to evaluate two raw materials with nutraceutical properties being used in feeds, spray-dried porcine plasma (SDPP) and a yeast protein meal, and their effects on growth performance, immune parameters and gastrointestinal adaption of piglets to weaning. Factors included dietary treatments being (1) 5% SDPP (PLA), (2) 3.5% yeast protein meal (NUP) and (3) medicated control (TMC) and parity (primiparous versus multiparous). The treatment groups were imposed from Day 19 through to weaning at Day 27. Selected pigs (n = 720, 28 ± 3 days of age, 7.4 ± 1.0 kg of bodyweight) were weaned and remained on their respective diets from Day 28 to Day 34. From Day 35 to Day 48 all group-housed pigs were offered a commercial weaner 1 diet, and from Day 49 to Day 68 pigs were offered a commercial weaner 2 diet. Growth performance, survival, and serum immunoglobulin G were monitored throughout the nursery phase (Day 28 to Day 68). Adaptation of the gastrointestinal tract in the acute post-weaning phase (Day 28 to Day 34) was assessed in 36 individually housed male weaners, with the effects of feed on structural, digestive, microbial and immune parameters along the gastrointestinal tract determined at Day 34. Pre-weaning feed disappearance was greater (P < 0.01) in multiparous litters independent of diet. In the commercial nursery, total removals (mortality and morbidity) were highest (P < 0.01) in primiparous sow progeny, with pigs offered NUP having greater (P ≤ 0.05) total removals. Pigs offered PLA had superior average daily gain, average daily feed intake and feed conversion ratio from Day 28 to Day 34 (P < 0.05). Pigs offered NUP tended to (P = 0.07) have superior average daily gain from Day 35 to Day 49. Pigs offered NUP had higher (P < 0.05) serum immunoglobulin G concentrations at Day 68 compared with pigs offered TMC, with the effect most pronounced in primiparous sow progeny. Individually housed weaners offered PLA consumed more (P < 0.05) feed on Day 30 to Day 31, had shorter relative intestine length (P < 0.05), greater villous height in the medial jejunum (P < 0.10) and lower immuno-pathology scores along the intestine. Pigs offered PLA also tended (P < 0.10) to have increased pancreatic-specific lipase and amylase activity compared with pigs offered NUP. Pigs offered NUP had a higher ratio of E. coli : coliforms in the colon (P < 0.01) and more counts of β-haemolytic bacteria in the medial jejunum (P < 0.05) and colon (P < 0.10). Diets containing either SDPP or NUP offered pigs benefits beyond nutrition relative to the medicated control diet. The benefits of SDPP were highly effective but transient, while the yeast derived protein had a successive or accumulative effect which was more pronounced in primiparous sow progeny.

Timing of infant feeding in relation to childhood asthma and allergic diseases

BACKGROUND

Emerging evidence questions current recommendations on the timing of infant feeding for the prevention of childhood allergies. The evidence for asthma is inconclusive.

OBJECTIVE

We sought to investigate the associations between the duration of breast-feeding and timing of introduction of complementary foods and the development of asthma and allergies by the age of 5 years.

METHODS

Data were analyzed for 3781 consecutively born children. The dietary exposures were categorized into thirds and analyzed as time-dependent variables. Asthma, allergic rhinitis, and atopic eczema end points were assessed by using the International Study of Asthma and Allergies in Childhood questionnaire, whereas IgE antibodies were analyzed from serum samples at the age of 5 years. Cox proportional hazard and logistic regressions were used for the analyses.

RESULTS

The median duration of exclusive and total breast-feeding was 1.4 months (interquartile range, 0.2-3.5 months) and 7.0 months (interquartile range, 4.0-11.0 months), respectively. Total breast-feeding of 9.5 months or less was associated with an increased risk of nonatopic asthma. Introduction of wheat, rye, oats, or barley at 5 to 5.5 months was inversely associated with asthma and allergic rhinitis, whereas introduction of other cereals at less than 4.5 months increased the risk of atopic eczema. Introduction of egg at 11 months or less was inversely associated with asthma, allergic rhinitis, and atopic sensitization, whereas introduction of fish at 9 months or less was inversely associated with allergic rhinitis and atopic sensitization.

CONCLUSION

Early introduction of wheat, rye, oats, and barley cereals; fish; and egg (respective to the timing of introduction of each food) seems to decrease the risk of asthma, allergic rhinitis, and atopic sensitization in childhood. Longer duration of total breast-feeding, rather than its exclusivity, was protective against the development of nonatopic but not atopic asthma, suggesting a potential differing effect of breast-feeding on different asthma phenotypes.

Nutritional factors influencing intestinal health of the neonate

Dietary nutrients are essential for gastrointestinal (GI) growth and function, and nutritional support of GI growth and development is a significant component of infant care. For healthy full-term neonates, nutritional provisions of the mother's milk and/or formula will support normal maturation of structure and function of the GI tract in most infants. The composition of breast milk affects GI barrier function and development of a competent mucosal immune system. The functional nutrients and other bioactive components of milk support a microenvironment for gut protection and maturation. However, premature infants struggle with feeding tolerance impairing normal GI function, leading to intestinal dysfunction and even death. The high prevalence worldwide of enteric diseases and dysfunction in neonates has led to much interest in understanding the role of nutrients and food components in the establishment and maintenance of a functioning GI tract. Neonates who do not receive enteral feeding as either mother's milk or formula are supported by total parental nutrition (TPN). The lack of enteral nutrition can compound intestinal dysfunction, leading to high morbidity and mortality in intestinally compromised infants. Reciprocally, enteral stimulation of an immature GI tract can also compound intestinal dysfunction. Therefore, further understanding of nutrient interactions with the mucosa is necessary to define nutritional requirements of the developing GI tract to minimize intestinal complications and infant morbidity. Piglet models of intestinal development and function are similar to humans, and this review summarizes recent findings regarding nutrient requirements for growth and maintenance of intestinal health. In particular, this article reviews the role of specific amino acids (arginine, glutamine, glutamate, and threonine), fatty acids (long chain polyunsaturated, medium chain, and short chain), various prebiotic carbohydrates (short-chain fructo-oligosaccharide, fructo--oligosaccharide, lacto-N-neotetraose, human milk oligosaccharide, polydextrose, and galacto-oligosaccharide), and probiotics that have been examined in the suckling piglet model of intestinal health.

Prevention of rotavirus-induced diarrhea by preferential secretion of IgA in breast milk via maternal administration of Lactobacillus gasseri SBT2055

OBJECTIVES

Rotavirus (RV)-induced diarrhea poses a major health problem, particularly to infants. An effective measure to prevent RV infection is to consume breast milk with higher levels of protective IgA. We therefore examined whether Lactobacillus gasseri SBT2055 (LG2055) could augment immunoglobulin (Ig) A levels and reduce the incidence of diarrhea in a mouse model of RV infection.

METHODS

Female BALB/c mouse dams were fed a diet containing 0.1% heat-treated LG2055 or a control, beginning 4 weeks before mating with male mice and continuing until the experiment ended. One week after mating, female dams were immunized orally with simian RV SA-11. Five days after birth, mouse pups were infected orally with RV and the incidence of diarrhea was determined 4 days later. RV-specific and total IgA were quantified by an enzyme-linked immunosorbent assay.

RESULTS

LG2055-fed dams immunized with RV (LG2055/RV) secreted breast milk that significantly lowered the incidence of RV-induced diarrhea in their pups as compared with dams immunized with RV alone (C/RV). The LG2055/RV dams also produced a significantly greater amount of RV-specific IgA in breast milk obtained from the pups' stomach, but not in feces or Peyer's patch cell cultures. In addition, LG2055 stimulated total IgA production in splenocyte cultures from Toll-like receptor (TLR)-4-knockout mice, but not those from TLR-2-knockouts.

CONCLUSIONS

LG2055-fed dams reduced RV infection in their pups and elevated RV-specific IgA levels in breast milk of stomach origin, the possible mechanism of which may be TLR-2 stimulation by LG2055.

The role of mucosal immunity in fungus ball of the paranasal sinuses

CONCLUSION

Increased levels of immunoglobulin (Ig)A, plasma cells, and lymphocytes without infiltration of other inflammatory cells suggest that mucosal immunity may play an important role in paranasal fungus ball.

OBJECTIVES

This study aimed to examine the nasal mucosal immune responses to fungi to understand the pathogenesis of fungus ball.

METHODS

Five patients with fungus ball of the maxillary sinus were enrolled. Lavage samples were collected from both nasal cavities and the maxillary sinus of the affected side. Mucosal samples were taken from both inferior turbinates and the maxillary sinus of the affected side. Interleukin (IL)-4, interferon (IFN)-γ, and IgA levels in the lavage samples were measured. Cells were counted on the lamina propria of mucosa under an electron microscope.

RESULTS

No significant differences in levels of IL-4 and IFN-γ were observed between the three groups of lavage samples. However, a significant rise in IgA levels was observed in the lavage samples from the nasal cavity and maxillary sinus of the affected side compared with that of the contralateral nasal cavity. Infiltration of plasma cells and lymphocytes in mucosal samples from the inferior turbinate and maxillary sinus of the affected side was significantly increased compared with that from the contralateral inferior turbinate, but other inflammatory cells were few and showed no difference.

Significance of expression of Toll-like receptor 4 in the intestinal tract of pigs with acute necrotizing pancreatitis

AIM: To detect the expression of Toll-like receptor 4 gene (TLR4) in the ileum of pigs with acute necrotizing pancreatitis (ANP).

METHODS: Eight pigs were randomized into ANP group and control group. ANP was induced by retrograde injection of sodium taurocholate. Blood levels of DAO were measured at various time points. Endotoxin concentration was determined using a commercial kit. The expression of tumor necrosis factor alpha (TNF-α), interleukin (IL)-6 and Toll-like receptor (TLR) 4 mRNAs in the ileum was assayed by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS: Compared to the control group, plasma endotoxin concentrations and serum DAO levels increased significantly (both P < 0.05), DAO levels in the ileal tissue homogenate decreased (P < 0.05), and expression of TLR4, TNF-α, and IL-6 mRNAs was significantly up-regulated (all P < 0.05) in the ANP group. The expression levels of TLR4 mRNA were correlated with DAO levels in ideal tissue (r = -0.762, P = 0.028) and plasma endotoxin concentrations (r = 0.778, P = 0.023).

CONCLUSION: Expression of TLR4 mRNA increased in the ileum of ANP pigs, and TLR4 mRNA overexpression may correlate with intestinal mucosa injury and development of enterogenic infection.

Longitudinal study on transmission of MRSA CC398 within pig herds

Background

Since the detection of MRSA CC398 in pigs in 2004, it has emerged in livestock worldwide. MRSA CC398 has been found in people in contact with livestock and thus has become a public health issue. Data from a large-scale longitudinal study in two Danish and four Dutch pig herds were used to quantify MRSA CC398 transmission rates within pig herds and to identify factors affecting transmission between pigs.

Results

Sows and their offspring were sampled at varying intervals during a production cycle. Overall MRSA prevalence of sows increased from 33% before farrowing to 77% before weaning. Overall MRSA prevalence of piglets was > 60% during the entire study period. The recurrent finding of MRSA in the majority of individuals indicates true colonization or might be the result of contamination. Transmission rates were estimated using a Susceptible-Infectious-Susceptible (SIS-)model, which resulted in values of the reproduction ratio (R₀) varying from 0.24 to 8.08. Transmission rates were higher in pigs treated with tetracyclins and β-lactams compared to untreated pigs implying a selective advantage of MRSA CC398 when these antimicrobials are used. Furthermore, transmission rates were higher in pre-weaning pigs compared to post-weaning pigs which might be explained by an age-related susceptibility or the presence of the sow as a primary source of MRSA CC398. Finally, transmission rates increased with the relative increase of the infection pressure within the pen compared to the total infection pressure, implying that within-pen transmission is a more important route compared to between-pen transmission and transmission through environmental exposure.

Conclusion

Our results indicate that MRSA CC398 is able to spread and persist in pig herds, resulting in an endemic situation. Transmission rates are affected by the use of selective antimicrobials and by the age of pigs.

Perspectives on immunomodulation early in life

The immune system early in life is characterized by immature activation and function of immune cells and a preponderance of Th2 cytokines. Together with other factors such as genetics and epigenetics, these immature immune responses might prone newborns susceptible to severe infections as well as allergic diseases. Immunomodulation therapy may have potential as therapeutic strategy against those disorders and might have implication in early-life interventions in the future. In this review, we will focus on two immunomodulatory substance classes, Toll-like receptor (TLR) ligands and sphingolipids, which are the focus of extensive research to date. Both TLRs and sphingolipid receptors have a very distinct distribution pattern and function on immune cells. Therefore, they can potentially modulate and balance immune responses, which might be in particular beneficial for the immaturity of the immune response early in life.

Neonatal colonisation expands a specific intestinal antigen-presenting cell subset prior to CD4 T-cell expansion, without altering T-cell repertoire

Interactions between the early-life colonising intestinal microbiota and the developing immune system are critical in determining the nature of immune responses in later life. Studies in neonatal animals in which this interaction can be examined are central to understanding the mechanisms by which the microbiota impacts on immune development and to developing therapies based on manipulation of the microbiome. The inbred piglet model represents a system that is comparable to human neonates and allows for control of the impact of maternal factors. Here we show that colonisation with a defined microbiota produces expansion of mucosal plasma cells and of T-lymphocytes without altering the repertoire of alpha beta T-cells in the intestine. Importantly, this is preceded by microbially-induced expansion of a signal regulatory protein α-positive (SIRPα⁺) antigen-presenting cell subset, whilst SIRPα⁻CD11R1⁺ antigen-presenting cells (APCs) are unaffected by colonisation. The central role of intestinal APCs in the induction and maintenance of mucosal immunity implicates SIRPα⁺ antigen-presenting cells as orchestrators of early-life mucosal immune development.

Gastrointestinal health and function in weaned pigs: a review of feeding strategies to control post-weaning diarrhoea without using in-feed antimicrobial compounds

For the last several decades, antimicrobial compounds have been used to promote piglet growth at weaning through the prevention of subclinical and clinical disease. There are, however, increasing concerns in relation to the development of antibiotic-resistant bacterial strains and the potential of these and associated resistance genes to impact on human health. As a consequence, European Union (EU) banned the use of antibiotics as growth promoters in swine and livestock production on 1 January 2006. Furthermore, minerals such as zinc (Zn) and copper (Cu) are not feasible alternatives/replacements to antibiotics because their excretion is a possible threat to the environment. Consequently, there is a need to develop feeding programs to serve as a means for controlling problems associated with the weaning transition without using antimicrobial compounds. This review, therefore, is focused on some of nutritional strategies that are known to improve structure and function of gastrointestinal tract and (or) promote post-weaning growth with special emphasis on probiotics, prebiotics, organic acids, trace minerals and dietary protein source and level.

Increased number of intestinal villous M cells in levamisole -pretreated weaned pigs experimentally infected with F4ac⁺ enterotoxigenic Escherichia coli strain

Immunoprophylaxis of porcine postweaning colibacillosis (PWC) caused by enterotoxigenic Escherichia coli (ETEC) expressing F4 fimbriae is an unsolved problem. Just as ETEC strains can exploit intestinal microfold (M) cells as the entry portal for infection, their high transcytotic ability make them an attractive target for mucosally delivered vaccines, adjuvants and therapeutics. We have developed a model of parenteral/oral immunization of 4-weeks-old pigs with either levamisole or vaccine candidate F4ac⁺ non-ETEC strain to study their effects on de novo differentiation of antigen-sampling M cells. Identification, localization and morphometric quantification of cytokeratin 18 positive M cells in the ileal mucosa of 6-weeks-old pigs revealed that they were: 1) exclusively located within villous epithelial layer, 2) significantly numerous (P< 0.01) in levamisole pretreated/challenged pigs, and 3) only slightly, but not significantly numerous in vaccinated/challenged pigs compared with non-pretreated/challenged control pigs. The fact that levamisole may affect the M cells frequency by increasing their numbers, makes it an interesting adjuvant to study development of an effective M cell-targeted vaccine against porcine PWC.

Dietary plasma proteins attenuate the innate immunity response in a mouse model of acute lung injury

We examined whether oral plasma protein supplements affect the innate immune response in a model of acute lung inflammation. Mice were fed diets supplemented with 8 % spray-dried plasma (SDP) or 2 % plasma Ig concentrate (IC) from day 19 (weaning) until day 34. The mice were challenged with intranasal lipopolysaccharide (LPS) at day 33 (and killed 24 h later for cytokine and leucocyte analyses) or at day 34 (and killed 6 h later for cytokine determinations). In bronchoalveolar lavage fluid (BALF), LPS increased the number of leucocytes by twenty-sevenfold, an effect that was partly prevented by both SDP and IC, and by twentyfold the percentage of activated monocytes, which was partly prevented by SDP. In the lung tissue, LPS increased the infiltrated leucocytes, and this effect was prevented in part by SDP. In unchallenged mice, both SDP and IC diets reduced the percentage of resident neutrophils and monocytes (P < 0·05). In the blood, both SDP and IC completely prevented LPS-dependent monocyte activation (CD14⁺; P < 0·05). LPS dramatically increased the concentration of cytokines (TNF-α, IL-1α, IL-6, granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor) and chemokines (CXCL1, CCL2, CCL3 and CCL4) in BALF. The acute response of cytokine production was reduced by 20-80 % by both SDP and IC. For chemokines, plasma supplements had no effect on LPS-induced CXCL1 expression but significantly reduced CCL2, CCL3 and CCL4 production (P < 0·05). The results support the view that dietary plasma proteins can be used to attenuate endotoxin-associated lung inflammation.

Investigation of the faecal microbiota of kittens: monitoring bacterial succession and effect of diet

Weaning is a stressful process for kittens and is often associated with diarrhoea and the onset of infectious diseases. The gastrointestinal (GI) microbiota plays an essential role in host well-being, including improving homoeostasis. Composition of the GI microbiota of young cats is poorly understood and the impact of diet on the kitten microbiota unknown. The aims of this study were to monitor the faecal microbiota of kittens and determine the effect(s) of diet on its composition. Bacterial succession was monitored in two groups of kittens (at 4 and 6 weeks, and 4 and 9 months of age) fed different foods. Age-related microbial changes revealed significantly different counts of total bacteria, lactic acid bacteria, Desulfovibrionales, Clostridium cluster IX and Bacteroidetes between 4-week- and 9-month-old kittens. Diet-associated differences in the faecal microbiota of the two feeding groups were evident. In general, fluorescence in situ hybridization analysis demonstrated bifidobacteria, Atopobium group, Clostridium cluster XIV and lactic acid bacteria were dominant in kittens. Denaturing gradient gel electrophoresis profiling showed highly complex and diverse faecal microbiotas for kittens, with age- and/or food-related changes seen in relation to species richness and similarity indices. Four-week-old kittens harboured more diverse and variable profiles than those of weaned kittens.

High salivary secretory IgA antibody levels are associated with less late-onset wheezing in IgE-sensitized infants

Low levels of secretory IgA (SIgA) and transient IgA deficiency have been associated with an increased risk for allergy, but data are conflicting. The aim was to assess the relationship between salivary SIgA antibody levels at 1 yr and wheezing at age four in a birth cohort, in particular the possible protective role of salivary SIgA in sensitized children. Saliva samples were obtained from all children (n=67) with a positive skin prick test (SPT) at 1 yr and 212 children with a negative SPT. In all, 200 of these children responded to questionnaires at 4 yrs and 183 were skin prick tested at that age. The levels of salivary SIgA and salivary IgA antibodies to the most common food allergen egg and inhalant allergen cat were analyzed by ELISA. Serum was analyzed for IgE antibodies to egg and cat. Development of late-onset wheezing was associated with low SIgA levels in children with positive SPT to at least one allergen both at 1 and 4 yrs of age (p=0.04), as well as in children with circulating IgE antibodies to egg or cat at 1 yr (p=0.02). None of nine persistently sensitized children with SIgA levels in the upper quartile developed wheezing, when compared to 10/20 children with lower levels (p=0.01). Older siblings, more than three infections during infancy, at least one smoking parent, and male gender, were all associated with SIgA in the upper quartile. In conclusion, high levels of SIgA antibodies in sensitized infants were associated with significantly less late-onset wheezing, supporting a protective role against development of asthmatic symptoms. Recurrent infections and other factors supporting an increased microbial pressure during infancy were associated with high levels of salivary SIgA.

A metabolic system-wide characterisation of the pig: a model for human physiology

The pig is a single-stomached omnivorous mammal and is an important model of human disease and nutrition. As such, it is necessary to establish a metabolic framework from which pathology-based variation can be compared. Here, a combination of one and two-dimensional (1)H and (13)C nuclear magnetic resonance spectroscopy (NMR) and high-resolution magic angle spinning (HR-MAS) NMR was used to provide a systems overview of porcine metabolism via characterisation of the urine, serum, liver and kidney metabolomes. The metabolites observed in each of these biological compartments were found to be qualitatively comparable to the metabolic signature of the same biological matrices in humans and rodents. The data were modelled using a combination of principal components analysis and Venn diagram mapping. Urine represented the most metabolically distinct biological compartment studied, with a relatively greater number of NMR detectable metabolites present, many of which are implicated in gut-microbial co-metabolic processes. The major inter-species differences observed were in the phase II conjugation of extra-genomic metabolites; the pig was observed to conjugate p-cresol, a gut microbial metabolite of tyrosine, with glucuronide rather than sulfate as seen in man. These observations are important to note when considering the translatability of experimental data derived from porcine models.

Prevalence and risk factor analysis of livestock associated MRSA-positive pig herds in The Netherlands

In 2005, methicillin-resistant Staphylococcus aureus was found in pig herds and in humans in contact with pigs. To determine the prevalence of, this now-called livestock-associated (LA) MRSA among pig herds in The Netherlands and to identify and quantify risk factors, an observational study of 202 pig herds was performed between 2007 and 2008. Five environmental wipes and 60 nasal swabs from each herd were collected, and microbiological analysis was performed on single environmental samples and pooled nasal samples. A herd was considered MRSA-positive if ≥1 sample tested positive. The prevalence of MRSA-positive herds was 67% in breeding herds and 71% in finishing herds. Multivariable logistic regression analysis was then performed on data from 171 breeding herds. The number of MRSA-positive herds increased from ∼30% at the start to ∼75% at the end of the study, most likely due to transmission between herds. The prevalence of MRSA increased with herd size, as ∼40% of smaller herds (<250 sows) were MRSA-positive compared to >80% of larger herds (>500 sows). Other risk factors (e.g. antimicrobial use, purchase of gilts and hygiene measures) were not significantly associated with MRSA, though associated with herd size. Herd size appeared to be a compilation of several factors, which made larger herds more often MRSA positive.

Neonate antigen presenting cells within murine intestinal muscular layer

The intestinal mucosa is exposed to a vast antigenic contact. Several antigen presenting cell (APCs) have been described within the gut associated lymphoid tissue (GALT) (Peyer's patches, lamina propria, mesenteric lymph nodes, muscular layer); however, this has been done almost exclusively in adult organisms. As there is no characterization of intestinal muscular layer's APCs during early neonate development we adapted the conventional technique used in adults, to the neonate intestine. We obtained the intestinal muscular layer from early neonates (days 0-3 upon birth) and from young mice (2 and 3 weeks after birth). A planar network of CD45(+), MHC-II(+), DEC-205(+) cells with irregular, some with prominent dendritic morphology was found at birth under basal physiological conditions, whereas Langerin(+) DCs appeared after two weeks. The variations seen in CD45(+), MHC-II(+) and DEC-205(+) cells along the early neonatal development, could be related to the new challenges by intestinal antigen exposure from the newborn diet (breast milk, solid food), and to important environmental changes (start walking, exploring the surroundings, etc). Our study reveals the presence of APCs in intestinal muscular layer at birth, and their subsequent changes in physiological, non-induced conditions, contributing basic information about these cells in the neonate intestinal immune system.

Role of natural killer and dendritic cell crosstalk in immunomodulation by commensal bacteria probiotics

A cooperative dialogue between natural killer (NK) cells and dendritic cells (DCs) has been elucidated in the last years. They help each other to acquire their complete functions, both in the periphery and in the secondary lymphoid organs. Thus, NK cells' activation by dendritic cells allows the killing of transformed or infected cells in the periphery but may also be important for the generation of adaptive immunity. Indeed, it has been shown that NK cells may play a key role in polarizing a Th1 response upon interaction with DCs exposed to microbial products. This regulatory role of DC/NK cross-talk is of particular importance at mucosal surfaces such as the intestine, where the immune system exists in intimate association with commensal bacteria such as lactic acid bacteria (LAB). We here review NK/DC interactions in the presence of gut-derived commensal bacteria and their role in bacterial strain-dependent immunomodulatory effects. We particularly aim to highlight the ability of distinct species of commensal bacterial probiotics to differently affect the outcome of DC/NK cross-talk and consequently to differently influence the polarization of the adaptive immune response.

Changes in lamina propria dendritic cells on the oral administration of exogenous protein antigens during weaning

Two critical periods of maximum exposure to antigens occur in young mammals, immediately after birth and at weaning, as a result of colonization by commensal bacteria and the ingestion of new diets. At weaning, active immune responses of antibody production against dietary proteins are known to occur, but simultaneously, oral tolerance is acquired for harmless food proteins. However, regulated mechanisms of the immune system at weaning remain to be elucidated although its immune responses may be somewhat similar to those in adulthood. Considering that tolerogenic antigen-presenting cells (APCs) are likely to be a key factor in the acquisition of oral tolerance, in the present study, we examined the changes of dendritic cells (DCs) in the lamina propria (LP) on exposure to food proteins at weaning. C57BL/6 female mice were weaned at the age of 3 weeks and orally administered 10 mg of ovalbumin (OVA) for ten consecutive days after weaning. The administration led to a decrease in the plasma level of immunoglobulin specific for OVA, suggesting the acquisition of oral tolerance. The uptake of fluorescence-labeled OVA was significantly observed for CD11c(+)LPDCs. When we analyzed the changes of two types of LPDCs, PDCA-1(+) MHC II(+) DCs and CD103(+) MHC II(+) DCs, ten consecutive gavages of OVA marginally, but not significantly, augmented only the frequency of PDCA-1(+) MHC II(+) DCs. Considering that the change of APCs likely appears immediately on the response to antigen intake, we found the statistically significant increase in the frequency of PDCA-1(+) DCs, but not in that of CD103(+) DCs, even after two treatments, indicating PDCA-1(+) DCs to be recruited in the LP within 2 days of exposure to food proteins. These results suggest that the behavior of tolerogenic PDCA-1(+) DCs may change at weaning with the removal of the immunoprotective components of maternal milk.

Postnatal development of the serotonin signaling system in the mucosa of the guinea pig ileum

BACKGROUND

Serotonin is an important neurohumoral molecule in the gut but its signaling system is not fully developed in the neonatal gastrointestinal (GI) tract. This study aimed to evaluate the postnatal maturation of serotonin signaling in the small intestine.

METHODS

In vitro amperometry for real-time measurement of serotonin at the mucosal surface, immunoblot, immunohistochemistry and high-performance liquid chromatography (HPLC) were used to examine serotonin handling in ileal segments from guinea pigs of different ages.

KEY RESULTS

Extracellular serotonin levels significantly declined over the first three postnatal weeks, after which the levels increased and reached their maximum at 9 weeks postnatally. Serotonin levels were insensitive to the inhibition of the serotonin transporter (SERT) until the animals reached 3 weeks old. Measurement of serotonin and its metabolite 5-hydroxyindole acetic acid (5-HIAA) in the mucosa revealed that the serotonin turnover was significantly lower in neonates. Immunoblot and immunohistochemistry showed that SERT expression was extremely low in the neonatal period. Serotonin staining in cross-section showed that enterochromaffin (EC) cells were preferentially localized in the crypt region in neonates and the number of EC cells was significantly higher in 9-week-old animals.

CONCLUSIONS & INFERENCES

SERT expression is low in the neonatal intestine and serotonin signaling matures postnatally. Extracellular serotonin levels decrease during the first three neonatal weeks as SERT expression increases. Extracellular serotonin levels increase after 3 weeks (weaning) possibly due to an increase in EC cell numbers. Postnatal maturation of serotonin signaling coincides with dietary changes in the developing guinea pig.

Sociodemographic and dietary risk factors for natural infant intussusception in the United States

BACKGROUND

In 1999, a US case-control study demonstrated a strong association between intussusception and a rotavirus vaccine (Rotashield). However, because most (87%) cases were not temporally associated with vaccination, we reanalyzed these data to assess risk factors for intussusception cases unrelated to Rotashield.

PATIENTS AND METHODS

Case-patients were infants with intussusception between November 1998 and June 1999. Controls were matched by age and hospital of birth. Sociodemographic and feeding practice data were collected through parent and provider interviews. Conditional logistic regression was used to identify risk factors for intussusception, controlling for exposure to Rotashield <21 days before intussusception.

RESULTS

Four hundred twenty-nine cases and 1763 controls were enrolled. Among case-patients, 372 (87%) had not received Rotashield within 21 days before intussusception. After adjusting for recent Rotashield administration, factors associated with intussusception included male sex (odds ratio [OR] 1.7; 95% confidence interval [CI] 1.3-2.2), Hispanic (OR 2.1; 95% CI 1.4-3.2) or black (OR 1.8; 95% CI 1.2-2.7) race/ethnicity, and Medicaid enrollment (OR 1.5; 95% CI 1.1-2.0). Feeding practices modified the risk of intussusception. Interaction was found between introduction of solid food (ISF) and type of formula consumption. Using breast milk as the referent group, infants with ISF for at least 5 weeks who consumed soy milk-based formula had a lower risk (OR 0.26; 95% CI 0.1-0.7) and infants without ISF who consumed cow's-milk formula had an increased risk (OR 2.33; 95% CI 1.4-3.9).

CONCLUSIONS

Risk of intussusception among US infants varies based on sociodemographic characteristics and feeding patterns.

The intestinal microbiome: relationship to type 1 diabetes

This article discusses recent evidence that associates the developing intestinal microbiome to the pathogenesis of autoimmune T1D. It attempts to identify avenues that should be pursued that relate this new evidence to interventions that eventually could result in prevention.

Clinical aspects of pediatric food allergy and failed oral immune tolerance

Food allergy seems to represent a new spectrum of disease that has elicited significant community concern and extended waiting lists for allergists and gastroenterologists alike. The apparent rise in prevalence of IgE-mediated food allergy (and associated risk of anaphylaxis) has been postulated to result from effects of a "modern lifestyle" but as yet clear environmental risk factors have not yet emerged. Family history seems to contribute to risk suggesting that gene-environment interactions will be important for identifying a subpopulation with increased susceptibility to any identified lifestyle effects. Non-IgE-mediated food allergy (including food-induced enteropathies and colitides, eosinophilic esophagitis, and Crohn's disease) with potentially similar environmental triggers resulting in diverse immune dysregulatory mechanisms. The evidence underpinning the putative rise in food allergy is discussed and potential mechanisms of disease explored. Clinical aspects of various food allergic conditions including non-IgE-mediated food allergy are outlined.

Dendritic cells interact with CD4 T cells in intestinal mucosa

Absence of lymph nodes in nonmammalian species, expression of MHCII by APCs in the periphery, and the recent findings that T cells can change their polarization status after presentation in the lymph nodes imply a role for MHCII-mediated presentation outside the organized lymphoid tissue. This study shows that MHCII(+) ECs and DCs from the intestinal mucosa of the pig can present antigen to T cells in vitro. In vivo, APCs colocalize with T cells in pig and mouse intestinal mucosa. In the pig, endothelium is involved in these interactions in neonates but not in adults, indicating different roles for stromal and professional APCs in the neonate compared with the adult. The ratio of expression of DQ and DR MHCII locus products was lower on ECs than on other mucosal APCs, indicating that the two types of cells present different peptide sets. Adult nonendothelial APCs expressed a higher ratio of DQ/DR than in neonates. These results suggest that mucosal DCs can present antigen locally to primed T cells and that stromal APCs are recruited to these interactions in some cases. This raises the possibility that local presentation may influence T cell responses at the effector stage after initial presentation in the lymph node.

Ultra-early weaning in piglets results in low serum IgA concentration and IL17 mRNA expression

In pigs raised for meat production, weaning is a critical period because of related physiological perturbations and negative consequences on performance. Previous studies have shown that early weaning could either impair development of mucosal barrier function or boost intestinal immunologic parameters. In order to obtain further knowledge about the impact of ultra-early weaning on the porcine immune system development, three groups of piglets were weaned at different ages and compared to the unweaned control group. Lower IgA concentrations in ultra-early and early weaned piglets than in other piglets were identified in serum. In the mesenteric lymph node (MLN), significant differences in the mRNA expression of IL17a, TGF beta and FOXP3 were found between specific groups. Indeed, IL17a mRNA was mainly detected in ultra-early weaned piglets while FOXP3 and TGF beta mRNA were associated to both ultra-early weaned and suckling piglets. Reduced serum IgA concentration and MLN induction of a Th17 cytokine in ultra-early weaned piglets could be related to alterations of the mucosal barrier functions consecutive to the milk deprivation. All together, our findings suggest a crucial role for endogenous milk factors onto the onset of IgA synthesis.

The rhesus macaque pediatric SIV infection model - a valuable tool in understanding infant HIV-1 pathogenesis and for designing pediatric HIV-1 prevention strategies

Worldwide, the AIDS pandemic continues almost relentlessly. Women are now representing the fastest growing group of newly infected HIV-1 infected patients. The risk of mother-to-child-transmission (MTCT) of HIV-1 increases proportionally as many of these women are of childbearing age. The screening of pregnant women, the early diagnosis of HIV-1 infection, and the administration of antiretroviral therapy (ART) have helped to reduce MTCT significantly. However, this holds true only for developed countries. In many resource-poor countries, access to ART is limited, and breastfeeding, a major route of HIV-1 transmission, is essential to protect the infant from other infectious diseases preponderant in those geographic regions. HIV-1 infected children, in contrast to adult patients, have higher levels of virus replication that decline only slowly, and a subset progresses to AIDS within the first two years. Thus, it is imperative to understand pediatric HIV-1 pathogenesis to design effective prevention strategies and/or a successful pediatric HIV-1 vaccine. The review summarizes how MTCT of HIV-1 in humans can be modeled in the infant macaque model of SIV infection. Importantly, the infant macaque model of SIV infection provides the opportunity to study early virus-host interactions in multiple anatomic compartments. Furthermore, the review underlines the importance of evaluating SIV/HIV immune responses in the context of the normal developmental changes the immune system undergoes in the newborn. Thus, the pediatric SIV infection model provides a unique resource for preclinical studies of novel intervention therapies and vaccine strategies to stop MTCT of HIV-1.

Intestinal and peripheral immune response to MON810 maize ingestion in weaning and old mice

This study evaluated the gut and peripheral immune response to genetically modified (GM) maize in mice in vulnerable conditions. Weaning and old mice were fed a diet containing MON810 or its parental control maize or a pellet diet containing a GM-free maize for 30 and 90 days. The immunophenotype of intestinal intraepithelial, spleen, and blood lymphocytes of control maize fed mice was similar to that of pellet fed mice. As compared to control maize, MON810 maize induced alterations in the percentage of T and B cells and of CD4(+), CD8(+), gammadeltaT, and alphabetaT subpopulations of weaning and old mice fed for 30 or 90 days, respectively, at the gut and peripheral sites. An increase of serum IL-6, IL-13, IL-12p70, and MIP-1beta after MON810 feeding was also found. These results suggest the importance of the gut and peripheral immune response to GM crop ingestion as well as the age of the consumer in the GMO safety evaluation.

Secretory IgA mediates bacterial translocation to dendritic cells in mouse Peyer's patches with restriction to mucosal compartment

In addition to fulfilling its function of immune exclusion at mucosal surfaces, secretory IgA (SIgA) Ab exhibits the striking feature to adhere selectively to M cells in the mouse and human intestinal Peyer's patches (PPs). Subsequent uptake drives the SIgA Ab to dendritic cells (DCs), which become partially activated. Using freshly isolated mouse DCs, we found that the interaction with SIgA was tissue and DC subtype dependent. Only DCs isolated from PPs and mesenteric lymph nodes interacted with the Ab. CD11c(+)CD11b(+) DCs internalized SIgA, while CD11c(+)CD19(+) DCs only bound SIgA on their surface, and no interaction occurred with CD11c(+)CD8alpha(+) DCs. We next examined whether SIgA could deliver a sizeable cargo to PP DCs in vivo by administering SIgA-Shigella flexneri immune complexes into a mouse ligated intestinal loop containing a PP. We found that such immune complexes entered the PPs and were internalized by subepithelial dome PP DCs, in contrast to S. flexneri alone that did not penetrate the intestinal epithelium in mice. Dissemination of intraepithelial S. flexneri delivered as immune complexes was limited to PPs and mesenteric lymph nodes. We propose that preexisting SIgA Abs associated with microbes contribute to mucosal defense by eliciting responses that prevent overreaction while maintaining productive immunity.

Milk peptides and immune response in the neonate

Bioactive peptides encrypted within the native milk proteins can be released by enzymatic proteolysis, food processing, or gastrointestinal digestion. These peptides possess a wide range of properties, including immunomodulatory properties. The first months of life represent a critical period for the maturation of the immune system because a tolerance for nutrient molecules should be developed while that for pathogen-derived antigens is avoided. Evidence has accumulated to suggest that milk peptides may regulate gastrointestinal immunity, guiding the local immune system until it develops its full functionality. Our data using the weaning piglet as the model suggest that several milk peptides can downregulate various immune properties at a time (one to two weeks after weaning) that coincides with immaturity of the immune system. The protein kinase A system and/or the exchange protein directly activated by cyclic AMP (Epac-1) are implicated in the mechanism through which milk peptides can affect immune function in the early postweaning period. Despite the fact that the research in this field is in its infancy, the evidence available suggests that milk protein peptides may promote development of neonatal immune competence. Milk contains a variety of components that provide immunological protection and facilitate the development of neonatal immune competence. Two main categories of milk compounds are thought to be associated with immunological activity. The first category includes cytokines, which neonates do not produce efficiently. Cytokines present in milk are thought to be protected against intestinal proteolysis and could alleviate immunological deficits, aiding immune system maturation (Kelleher & Lonnerdal, 2001; Bryan et al., 2006). The second category of milk compounds includes milk protein peptides. Milk peptides may affect mucosal immunity possibly by guiding local immunity until it develops its full functionality (Baldi et al., 2005). This chapter focuses on the effects of milk peptides on immune function and attempts to provide an overview of the knowledge available in this field.