Modulation of the gastrointestinal tract of infants by human milk. Interfaces and interactions. An evolutionary perspective

Dexamethasone and GLP-2 given to lactating rat dams influence glucose uptake in suckling and postweanling offspring

BACKGROUND

Glucagon-like peptide-2 (GLP-2) enhances intestinal absorption in adult animals. Glucocorticosteroids accelerate the ontogeny of the intestine and increase sugar uptake in adult animals. Modifying the maternal diet during lactation alters nutrient uptake in the offspring. The authors hypothesized that GLP-2 and dexamethasone, when administrated to lactating rat dams, enhance sugar uptake in the suckling and postweanling offspring.

METHODS

Rat dams were treated during lactation with GLP-2 (0.1 microg/g/day subcutaneously [SC], twice daily), dexamethasone (0.128 microg/g/day SC, once daily), GLP-2 + dexamethasone (same doses), or placebo. The suckling offspring were sacrificed at 19-21 days of age, and the postweanlings were sacrificed 4 weeks later. Intestinal glucose and fructose uptake was assessed using an in vitro ring technique.

RESULTS

GLP-2 and dexamethasone resulted in lower body weights, and dexamethasone caused intestinal atrophy in sucklings. The jejunal atrophy in sucklings given dexamethasone was prevented by GLP-2 + dexamethasone. In sucklings, the maximal transport rate and the Michaelis affinity constant for ileal glucose uptake were both increased by GLP-2 and GLP-2 + dexamethasone. In contrast, in postweanlings, the maximal transport rate for jejunal glucose uptake was reduced by dexamethasone and GLP-2, as was ileal fructose uptake.

CONCLUSIONS

Treating lactating rat dams with GLP-2 or dexamethasone enhances glucose uptake in sucklings, but the late effect is a reduction in glucose and fructose absorption in postweanlings. The nutritional significance of these findings remains to be established.

Celiac disease

PURPOSE OF REVIEW

Research in celiac disease is unraveling new findings at a high rate, and major advances seem to occur in all areas such as genetics, environmental factor, pathophysiology, and even prospective therapeutic implications.

RECENT FINDINGS

New insight is being gained into the interplay between genetic and environmental factors causing celiac disease. In addition to the known human leukocyte antigen haplotypes, genome-wide studies have now identified additional susceptibility loci and the majority of newly discovered risk regions harbor genes controlling immune pathways. The mechanism of translocation of gliadin peptides across the intestinal barrier has been the subject of much investigation, and there is now evidence that the toxic 33-mer peptide can also be translocated transcellularly. As for the paracellular route, this appears to be enhanced by gliadin's stimulation of zonulin release. The growing role of the innate immunity is being recognized and the increased expression of some Toll-like receptors appears to delineate a new inherent defect in this branch of innate immunity. Finally, new perspectives are opening in the treatment of celiac disease based on new detoxified grains, enzymatic degradation of gluten, and prevention of its crossing the mucosal barrier.

SUMMARY

The pace of new knowledge in this 'ancient' disease is very fast, and this review outlines the principal lines of such exciting developments.

The nutritional modulation of the evolving intestine

Nutrition plays a major role in the modulation of the evolving human gut influencing all the main components of the intestinal ecosystem. The regulatory role of nutrition is particularly crucial in the early postnatal period but it continues also in subsequent ages when the development of the gastrointestinal tract is completed. Recent data support the hypothesis that nutrition can affect some inherited disorders of gastrointestinal tract. These "epigenetic" mechanisms are involved in the development of intestinal enzymes, hormones, transporters, and immunity. This is an expanding research area related to the possible nutritional intervention in selected clinical condition. This paper is focused on the main components and mechanisms of action of the nutritional modulation on intestinal development.

Hydrocortisone modulates cholera toxin endocytosis by regulating immature enterocyte plasma membrane phospholipids

BACKGROUND & AIMS

Diarrheal disease is a major cause of morbidity and mortality in infants and children worldwide. Evidence has indicated immature human enterocytes and their interaction with bacteria and enterotoxins may account for the noted increased susceptibility of neonates to diarrhea. Our aim was to characterize the developmental difference in cholera toxin (CT)-GM1-mediated endocytosis.

METHODS

We used H4 cells (a fetal human small intestinal epithelial cell line), T84 cells, primary cultured mature human small intestinal epithelial cells, and human fetal small intestine xenografts. In addition, hydrocortisone was used as a potent intestinal trophic factor to induce maturation of the human enterocytes.

RESULTS

Here we show an increase in CT-caveolae and a decrease in CT-clathrin colocalization in H4/hydrocortisone compared with H4 cells by electron microscopy. In T84 and freshly isolated human small intestinal epithelial cells, a significant amount of GM1 was partitioned into the lipid rafts. In contrast, there was little CT-GM1/lipid raft association in H4 cells. However, hydrocortisone significantly increased GM1/lipid raft association in H4 cells. Furthermore, we noted an increase in the level of phosphatidylcholine, sphingomyelin, and the ratio of phosphatidylcholine/phosphatidylinositol in mature compared with immature enterocytes and that hydrocortisone can accelerate this maturational process. Disruption of phosphatidylinositol transfer protein alpha using small interference RNA showed an increase in GM1/lipid raft association in H4 cells and resulted in a decreased CT response.

CONCLUSIONS

Our studies suggest that the developmental change in CT endocytosis is partially caused by an increased GM1-lipid raft association through a maturational change of phospholipid composition on the cell surface of immature enterocytes.

The CUPDAY Study: prebiotic-probiotic milk product in 1-3-year-old children attending childcare centres

AIM

The aim of the study was to evaluate the efficacy of a milk product containing probiotics and prebiotics (CUPDAY Milk) on the incidence of diarrhoea in children attending daycare centres.

METHODS

The study was undertaken in a randomized controlled trial with 496 children aged 1-3 years attending 29 childcare centres in Perth, Australia. The endpoint for the study was the number of days in which children were recorded as having four or more stools. The diarrhoeal rates were analyzed by Poisson regression using 'intention to treat' (all children) and 'reduced' (children enrolled for more than 10 days) data sets.

RESULTS

There was no difference in demographic characteristics between the case and control groups. In the 'intention to treat' analysis, a total of 41 745 child-days were included in the study. The adjusted risk ratio for those consuming the 'Cupday' milk drink was 0.82 (95% CI 0.73-0.94) for the intention to treat sample (n = 496) and 0.80 (95% CI 0.70-0.91) for the reduced sample (n = 315). The children consuming the 'Cupday' drink had a 20% reduction in the number of days experiencing four or more stools per day.

CONCLUSION

A milk containing probiotics and prebiotics reduced the number of days children attending child care who had four or more stools by 20%.

Effect of early infant feeding practices on infection-specific neonatal mortality: an investigation of the causal links with observational data from rural Ghana

BACKGROUND

Strong associations between delayed initiation of breastfeeding and increased neonatal mortality (2-28 d) were recently reported in rural Ghana. Investigation into the biological plausibility of this relation and potential causal pathways is needed.

OBJECTIVE

The objective was to assess the effect of early infant feeding practices (delayed initiation, prelacteal feeding, established neonatal breastfeeding) on infection-specific neonatal mortality in breastfed neonates aged 2-28 d.

DESIGN

This prospective observational cohort study was based on 10 942 breastfed singleton neonates born between 1 July 2003 and 30 June 2004, who survived to day 2, and whose mothers were visited in the neonatal period. Verbal autopsies were used to ascertain the cause of death.

RESULTS

One hundred forty neonates died from day 2 to day 28; 93 died of infection and 47 of noninfectious causes. The risk of death as a result of infection increased with increasing delay in initiation of breastfeeding from 1 h to day 7; overall late initiation (after day 1) was associated with a 2.6-fold risk [adjusted odds ratio (adj OR): 2.61; 95% CI: 1.68, 4.04]. Partial breastfeeding was associated with a 5.7-fold adjusted risk of death as a result of infectious disease (adj OR: 5.73; 95% CI: 2.75, 11.91). No obvious associations were observed between these feeding practices and noninfection-specific mortality. Prelacteal feeding was not associated with infection (adj OR: 1.11; 95% CI: 0.66, 1.86) or noninfection-specific (adj OR: 1.33; 95% CI: 0.55, 3.22) mortality.

CONCLUSIONS

This study provides the first epidemiologic evidence of a causal association between early breastfeeding and reduced infection-specific neonatal mortality in young human infants.

The importance of exclusive breastfeeding in infants at risk for celiac disease

This article presents a review of studies examining the association between breastfeeding and delayed symptomatic celiac disease and provides implications for practice. Celiac disease is a chronic intestinal disease involving intolerance to gluten. Symptomatic celiac disease varies in presentation and may include malabsorption, diarrhea, steatorrhea, and malnutrition. Its etiology is multifactorial, related to genetic susceptibility and exposure to gluten. Exclusive breastfeeding, with its many health benefits, may mitigate or delay symptomatic celiac disease. Because infants with a positive family history of the disease could be affected, it is crucial to identify those at risk and educate and advise parents regarding the importance of exclusive breastfeeding.

Transmission of West Nile virus through human breast milk seems to be rare

INTRODUCTION

In September 2002, possible transmission of West Nile virus via human milk was reported for the first time.

METHODS

Since 2003, the Centers for Disease Control and Prevention collected reports of maternal or infant West Nile virus illness during the breastfeeding period. All of the reported instances were reviewed. In addition, milk samples from women infected during pregnancy were tested for West Nile virus RNA and West Nile virus-specific antibodies.

RESULTS

Six infants were reported to have breastfed from mothers with West Nile virus fever. Five of the 6 infants had no illness or detectable antibodies to West Nile virus in serum after onset of maternal illness. One infant who was not tested and developed a rash was otherwise well 1 week after onset of maternal illness. In addition, 2 infants were reported to have developed West Nile virus illness while breastfeeding; preceding maternal illness was not documented. Two breastfed infants whose mothers acquired West Nile virus fever in the last week of pregnancy developed West Nile virus-specific antibodies; both infant infections could have been congenitally acquired. Of 45 milk samples from women infected with West Nile virus during pregnancy, 2 had West Nile virus RNA, and 14 had immunoglobin M antibodies to West Nile virus.

CONCLUSIONS

Of 10 reported instances since 2003 of maternal or infant West Nile virus illness while breastfeeding, transmission of West Nile virus through human milk could neither be ruled out nor confirmed for 5 cases; in 5 others, serologic tests indicated no vertical transmission. Transmission of West Nile virus through breastfeeding seems to be rare, but more information is needed.

Consumption of milk from transgenic goats expressing human lysozyme in the mammary gland results in the modulation of intestinal microflora

Lysozyme is a key antimicrobial component of human milk that has several health-promoting functions including the development of a healthy intestinal tract. However, levels of lysozyme in the milk of dairy animals are negligible. We have generated transgenic dairy goats that express human lysozyme (HLZ) in their milk in an attempt to deliver the benefits of human milk in a continual fashion. To test the feasibility of this transgenic approach to achieve a biological impact at the level of the intestine, feeding trials were conducted in two animal models. Pasteurized milk from HLZ transgenic animals was fed to both kid goats (ruminant model) and young pigs (human model), and the numbers of total coliforms and Escherichia coli present in the small intestine were determined. Data from this proof-of-principle study demonstrate that milk from transgenic animals was capable of modulating the bacterial population of the gut in both animal models. Pigs that consumed pasteurized milk from HLZ transgenic goats had fewer numbers of coliforms and E. coli in their intestine than did those receiving milk from non-transgenic control animals. The opposite effect was seen in goats. Milk from these transgenic animals not only represent one of the first transgenic food products with the potential of benefiting human health, but are also a unique model to study the development and role of intestinal microflora on health, well-being and resistance to disease.

Effect of diet on the development of drug metabolism by cytochrome P-450 enzymes in healthy infants

Orally administered caffeine and dextromethorphan (DM) were used as pharmacologic probes to determine the effect of infant diet on acquisition of cytochrome P-450 (CYP) enzyme activity during the first 6 mo of life. The caffeine elimination rate constant (ke) was determined from serum, and concentrations of caffeine, DM, and their respective metabolites were measured in urine by high-performance liquid chromatography (HPLC). Caffeine ke was low at 2 wk and displayed a significant positive linear correlation with age (p < 0.001); increasing faster in formula-fed than in breast-fed infants (p < 0.001). This occurred concomitantly with a significant increase in urinary 1,7-dimethylxanthine (17X) and 1-methylxanthine (1X) (p < 0.001), suggesting faster acquisition of CYP1A2 activity in formula-fed infants. The urinary molar ratio of (17X + 1X)/caffeine and age strongly predicted caffeine ke (r2 = 0.65; p < 0.001) irrespective of feeding type. CYP3A4 activity, assessed as the molar ratio of 3-hydroxymorphinan/dextrorphan showed a similar marked increase with postnatal age (p < 0.001) that was also greater in formula-fed than in breast-fed infants. Formula feeding appears to accelerate maturation of caffeine and DM metabolism by increasing the activity of CYP1A2 and CYP3A4, respectively. Dietary modification of CYP activity may modulate drug biotransformation and thus alter systemic exposure to xenobiotics from a very early age.

Enteral granulocyte colony-stimulating factor for the treatment of mild (stage I) necrotizing enterocolitis: a placebo-controlled pilot study

BACKGROUND/PURPOSE

The presence of granulocyte colony-stimulating factor (G-CSF) in human milk and the expression of G-CSF receptors on intestinal villous enterocytes of neonates suggest that G-CSF has a role in the development and integrity of the gastrointestinal tract. We hypothesized that enteral recombinant human G-CSF (rhG-CSF) given to preterm infants with necrotizing enterocolitis (NEC) in the earlier stages could protect against disease progression and complications.

METHODS

Preterm infants with mild (stage I) NEC (n = 18) were assigned to receive enteral rhG-CSF (n = 8) or placebo (n = 10) for 5 days from the first day of the diagnosis. Clinical and gastrointestinal parameters were followed during the whole period of hospitalization.

RESULTS

In the study group, none of the infants with stage I NEC had a clinical progression to stage II or III, whereas in the control group, 5 (50%) infants with stage I NEC had a disease progression to stage II or III (P < .05). In the study group, the time required for the resolution of clinical and radiological findings of NEC and the total duration of systemic therapy and hospitalization were significantly shorter than the control group (P < .001).

CONCLUSION

Enteral rhG-CSF treatment could prevent the progression of mild (stage I) NEC to further stages and decrease the time required for the resolution of clinical and radiological signs of the disease.

Ability of Orally Administered IFN-α-Containing Transgenic Potato Extracts to InhibitListeria monocytogenesInfection

Type I interferons (IFN-alpha/beta) were originally thought to be antiviral cytokines, but it has recently been reported that they also play an important role in potentiating innate and adaptive immune responses. Moreover, several studies have shown that the oral administration of type I IFN ameliorates various biologic activities. Here, we studied the ability of orally administered IFN-alpha to protect mice from systemic Listeria monocytogenes infection. Daily oral administration of purified natural IFN-alpha at a concentration of 1000 international units (IU)/20 microl reduced the bacterial burden in infected organs. We also examined the protective effect of IFN-alpha expressed in transgenic potato plants. A much lower concentration of IFN-alpha (20 IU/ 20 microl) in the plant extracts was almost as protective as much higher concentrations of purified natural IFN-alpha. Our observations indicate that transgenic cytokine-expressing plants can be used prophylactically as edible pharmaceuticals to enhance systemic defense responses in humans and animals.

Preterm birth makes the immature intestine sensitive to feeding-induced intestinal atrophy

Preterm birth and formula feeding predispose to small intestinal dysfunction, which may lead to necrotizing enterocolitis (NEC). In piglets, we tested whether the physiological and environmental transitions occurring at birth affect the response of the immature intestine to enteral feeding. Pig fetuses (106 days gestation, term = 115 days) were prepared with esophageal feeding tubes and fed either sow's colostrum (n = 8) or infant formula (n = 7) in utero. After 24 h of oral feeding, the pig fetuses were delivered by cesarean section and their gastrointestinal morphology and function were compared with those of preterm newborn (NB) littermates that were not fed (n = 8) or fed colostrum (n = 7) or formula (n = 13) for 24 h after birth. Before birth, both colostrum and formula feeding resulted in marked increases in intestinal mass, brush-border enzyme activities, and plasma glucagon-like peptide 2 concentrations, to levels similar to those in NB colostrum-fed piglets. In contrast, NB formula-fed piglets showed reduced intestinal growth, decreased brush-border enzyme activities, and intestinal lesions, reflecting NEC. NB formula-fed pigs also showed impaired enterocyte endocytotic function and decreased antioxidative capacity, whereas brush-border enzyme mRNA levels were unaltered, relative to NB colostrum-fed pigs. Our results indicate that the feeding-induced growth and enzyme maturation of the immature intestine are not birth dependent. However, with a suboptimal diet (milk formula), factors related to preterm birth (e.g., microbial colonization and metabolic and endocrine changes) make the immature intestine sensitive to atrophy and development of NEC.

The Swedish epidemic of coeliac disease explored using an epidemiological approach--some lessons to be learnt

Sweden has experienced an epidemic of symptomatic coeliac disease that has no likeness anywhere else in the world. This is quite unique for a disease that is genetically dependent, immune-mediated and chronic, and suggests an abrupt increase and decrease, respectively, of one or a few causal factors influencing a large proportion of Swedish infants during the period in question. We have shown that half of the epidemic was explained by an increase in the proportion of infants introduced to gluten in comparatively large amounts after breast-feeding had been ended. This was partly an effect of societal changes in national dietary recommendations and the food content of industrially produced infant foods. Thus, these changes over time in infant feeding practices had a large public health impact. In fact, when the Swedish epidemic began, the increase in incidence rate was larger in girls than in boys, as was the decrease during the post-epidemic period. Moreover, children born during summer had an increased risk for coeliac disease, possibly as they were mostly introduced to dietary gluten during winter when infections are more common. Notably, birth cohorts of the epidemic and post-epidemic periods differ considerably regarding coeliac disease occurrence at comparable ages, even when followed up to school age. A longer follow-up will reveal to what extent new cases develop later in life, and to what extent this difference in cumulative incidence remains. However, mass screening studies of both the epidemic and post-epidemic cohorts at comparable ages are also planned to determine to what extent 'silent' disease cases develop. Continuing to explore the Swedish epidemic of coeliac disease by means of an epidemiological approach provides a unique opportunity. This may include increasing our understanding of what determines the clinical expression of the disease, exploring the potentially causal role of environmental exposures, and possibly also identifying strategies for primary prevention.

Incidence and clinical manifestations of breast milk-acquired Cytomegalovirus infection in low birth weight infants

OBJECTIVES

To determine the incidence and clinical manifestations of human breast milk (HMB)-associated acquired cytomegalovirus (CMV) infection in small premature infants.

STUDY DESIGN

A prospective study of premature infants born at or prior to 32 weeks gestation, and or infants weighing 1500 g or less at birth. The babies were divided into two groups: Group 1 included babies of CMV seropositive mothers who received HBM throughout the study period. Group 2 included babies of seronegative mothers or babies that did not receive HBM at all. Urine sample were obtained once weekly from birth until the age of 8 weeks or until discharge and were tested for the presence of CMV-DNA by PCR.

RESULTS

Four of 70 infants from group 1 (5.7%, 95% CI, 0 to 11%) acquired CMV infection between the ages of 3 and 7 weeks as compared to none of 26 babies in group 2. Only one infected baby had severe CMV disease with complete recovery.

CONCLUSION

The relative incidence of HBM-associated CMV infection and the severity of HBM-associated CMV disease in premature infants are low.

Suppression of serum IgE response and systemic anaphylaxis in a food allergy model by orally administered high-dose TGF-β

Some epidemiological or association studies suggest that transforming growth factor-beta (TGF-beta) in breast milk may be a decisive factor in diminishing the risk of allergic diseases during infancy. The observations have prompted us to investigate whether TGF-beta, when taken orally, can affect allergic immune responses. Repeated high-dose ovalbumin peptide (OVA) feeding was previously reported to induce OVA-specific IgE production and an anaphylactic reaction after intravenous challenge of OVA in OVA-TCR transgenic mice, which might represent a model for food allergy. By using this model, we showed here that oral administration of high-dose TGF-beta simultaneously with OVA feeding significantly inhibited the OVA-specific IgE elevation and anaphylactic reaction in OVA-TCR transgenic DO11.10 mice. These effects were associated with suppression of OVA-specific IL-4 production and GATA-3 expression and with up-regulation of IFN-gamma production and T-bet expression by splenocytes. Intra-peritoneal injection of anti-TGF-beta-neutralizing antibody abolished the inhibitory effects of orally administered TGF-beta on the serum IgE response and anaphylactic reaction after OVA feeding in DO11.10 mice. Interestingly, oral administration of high-dose TGF-beta suppressed activation-induced T cell death induced by OVA feeding in DO11.10 mice. We thus conclude that TGF-beta, when taken orally at high dose, has the capacity to modulate a food allergy-related reaction, at least in part, through its systemic activity.

Impact of standardised feeding regimens on incidence of neonatal necrotising enterocolitis: a systematic review and meta-analysis of observational studies

BACKGROUND

A significant and prolonged decline in the incidence of necrotising enterocolitis (NEC), nearing virtual elimination in some centres, has been observed consistently since implementation of a standardised feeding regimen.

AIM

To systematically review the observational studies reporting incidence of NEC in preterm, low birth weight (LBW) neonates "before" and "after" implementation of a standardised feeding regimen.

METHODS

The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 4, 2002), Medline, Embase, Cinahl, and proceedings of the Pediatric Academic Societies (published in Pediatric Research from 1980) were searched in July and again in October 2003. The reference lists of identified observational studies, and personal files, were searched. No language restriction was applied. Key words were: standardised, enteral, feeding, neonates, necrotising enterocolitis. Authors were contacted for clarification of data.

RESULTS

Six eligible studies (1978-2003) were identified. A significant heterogeneity was noted between the studies indicating the variations in the population characteristics and feeding practices over a period of 25 years. Meta-analysis of the six studies using a random effects model revealed a pooled risk ratio of 0.13 (95% confidence interval 0.03 to 0.50)-that is, introduction of a standardised feeding regimen reduced the incidence of NEC by 87%.

CONCLUSION

Standardised feeding regimens may provide the single most important global tool to prevent/minimise NEC in preterm neonates. Randomised controlled trials are needed.

IL-8/CXC ligand 8 survives neonatal gastric digestion as a result of intrinsic aspartyl proteinase resistance

The human fetus and neonate swallow biologically significant quantities of IL-8/CXC ligand 8 (CXCL8) in amniotic fluid and breast milk, and this remains measurable through simulated neonatal gastric and proximal intestinal digestions. We sought to confirm the structural and functional integrity of IL-8/CXCL8 in digestates and determine the mechanisms underlying this protease resistance. We observed that in comparison with BSA, IL-8/CXCL8 is highly resistant to pepsin and can be detected intact in assays for structural, immunologic, and functional integrity. In a computational molecular docking simulation, IL-8/CXCL8 was observed to fit poorly in the pepsin active site. On the basis of simulated mutation analyses, we hypothesized that this protease resistance is due to disulfide bond-related tertiary folding in IL-8/CXCL8. This was confirmed on chemical reduction of these groups.

Virtual elimination of necrotising enterocolitis for 5 years - reasons?

A standardised feeding regimen was adopted in 1997 for guiding enteral feeding of neonates <32 weeks' gestation during clinical trials (18 months each) involving erythromycin (n=73) as a prokinetic and carboxymethylcellulose (n=70) as a laxative as well as for during 2 years (n=155) without any trials. Most aspects of the feeding regimen (e.g., milk increments-total volume/day, use of breast milk by choice, etc) were not significantly different from current practices.

RESULTS

298 neonates <32 weeks' gestation (<28 weeks; n=78) were enterally fed during the 5 years. Their demographic characteristics and median (interquartile) age in days at starting (AST) and days to reach full enteral feeds (FFT) of 150 ml/kg/day were not significantly different during these 5 years: [AST: 5 (3-7.5)], [FFT: 4 (3-7)] Only one case of definite NEC (> or =Stage II) occurred during the 5 years. The time to reach full feeds was also reduced by over 54% (including for neonates <28 weeks gestation) compared with a historical cohort.

CONCLUSION

Sustained reduction in the time to reach full feeds with virtual elimination of > or =Stage II NEC for 5 years indicates continued benefits of a standardised feeding regimen as a simple preventive strategy to prevent NEC. Whether our specific policy of no enteral feeds in presence of hemodynamic instability associated with PDA requiring indomethacin, and/or sepsis played a role in achieving the significant results needs controlled trials.

Human breast milk suppresses the transcriptional regulation of IL-1beta-induced NF-kappaB signaling in human intestinal cells

Neonatal necrotizing enterocolitis (NEC), which is a disease with a poor prognosis, is considered to be caused by the coincidence of intestinal ischemia-reperfusion injury and systemic inflammation due to the colonization of pathogenic bacteria. Interleukin (IL)-8, a proinflammatory cytokine, plays an important role in the pathophysiology of NEC. It was recently reported that IL-1beta activates the IL-8 gene by regulating the transcriptional nuclear factor kappaB (NF-kappaB) signaling pathways in intestinal cells. The protective role of maternal milk in NEC pathogenesis has been reported in both human and animal studies. In this study, we show that human breast milk dramatically suppressed the IL-1beta-induced activation of the IL-8 gene promoter by inhibiting the activation pathway of NF-kappaB. Moreover, we also show that human breast milk induced the production of IkappaBalpha. These results suggest that human breast milk could be protective and therapeutic in neonates with NEC by inhibiting the activation pathway of NF-kappaB.

The prospects of modifying the antimicrobial properties of milk

Milk contains a variety of substances, which inhibit the infection of pathogens. This is of benefit to the mother, safeguarding the integrity of the lactating mammary gland, but also of huge importance for protection of the suckling offspring. The antimicrobial substances in milk can be classified into two categories. First, nonspecific, broad-spectrum defense substances, which have evolved over long periods of time, and secondly, substances like antibodies, which are specifically directed against particular pathogens and have developed during the mother's lifetime. Substances in both categories may be targets for biological intervention and manipulation with the goal of improving the antimicrobial properties of milk. These alterations of milk composition have applications in human as well as in animal health.

Low breastfeeding rates and public health in the United States

The medical community has orchestrated breastfeeding campaigns in response to low breastfeeding rates twice in US history. The first campaigns occurred in the early 20th century after reformers linked diarrhea, which caused the majority of infant deaths, to the use of cows' milk as an infant food. Today, given studies showing that numerous diseases and conditions can be prevented or limited in severity by prolonged breastfeeding, a practice shunned by most American mothers, the medical community is again inaugurating efforts to endorse breastfeeding as a preventive health measure. This article describes infant feeding practices and resulting public health campaigns in the early 20th and 21st centuries and finds lessons in the original campaigns for the promoters of breastfeeding today.

Treatment and prevention of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the most common serious, acquired gastrointestinal disorder in the newborn infant. Although many variables are associated with development of NEC, only prematurity has been consistently identified in case-controlled studies. Traditionally, the diving seal reflex has been invoked as the mechanism responsible for ischaemic injury and necrosis. Intestinal ischaemia is likely to be the final common pathway in NEC; however, it is due to the release of vasoconstricting substances, such as platelet activating factor, rather than perinatal asphyxia. Bacteria and/or bacterial toxins are likely to have a key role in the pathogenesis of NEC by fostering production of inflammatory mediators. The role of feeding practices in the pathogenesis of NEC remains controversial. Treatment of infants with NEC generally includes a regimen of bowel rest, gastric decompression, systemic antibiotics and parenteral nutrition. Infants with perforation are generally operated upon; however, there has been recent interest in primary peritoneal drainage as an alternative. Prevention of NEC still remains elusive. Avoidance of preterm birth, use of antenatal steroids and breast-milk feeding are practices that offer the greatest potential benefits. Use of any other strategy should await further trials.

Increased epidermal growth factor levels in human milk of mothers with extremely premature infants

Maternal milk is the major source of nutrients and growth-promoting substances in the first weeks of life for the majority of neonates. Epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) are trophic peptides present in human milk with significant healing effects on injured gastrointestinal mucosa. Decreasing gestational age of neonates is associated with higher risk of developing gastrointestinal disorders, and human milk provides better protection against these diseases compared with formula. The aim of this study was to evaluate the concentrations of EGF and TGF-alpha in human milk collected from mothers with infants born: extremely preterm, preterm, and full term. Milk samples were collected at the end of first, second, and fourth week postpartum from each mother of infants born in one of the three gestational age groups: extremely preterm (23-27 wk, n = 16), preterm (32-36 wk, n = 16), and full term (38-42 wk, n = 15). Milk concentrations of EGF and TGF-alpha were quantified with a homologous RIA in the milk aqueous fraction. Concentrations of EGF in human milk from the extremely preterm group (23-27 wk) were significantly higher compared with values from the preterm and full-term groups throughout the first month of lactation. A similar pattern was observed with human milk TGF-alpha; however, milk TGF-alpha levels were lower than EGF. In conclusion, we have found higher concentrations of EGF and TGF-alpha in human milk of mothers with extremely preterm babies. These data may indicate the potential importance of milk-borne EGF and TGF-alpha for the development of extremely premature infants.

Maternal milk reduces severity of necrotizing enterocolitis and increases intestinal IL-10 in a neonatal rat model

Necrotizing enterocolitis (NEC) is a devastating intestinal disease of premature infants. Maternal milk has been suggested to be partially protective against NEC; however, the mechanisms of this protection are not defined. The aim of this study was to examine the effect(s) of artificial feeding of rat milk (RM)-versus cow milk-based rat milk substitute (RMS) on the development of NEC in a neonatal rat model and elucidate the role of inflammatory cytokines in NEC pathogenesis. Newborn rats were artificially fed with either collected RM or RMS. Experimental NEC was induced by exposure to asphyxia and cold stress and evaluated by histologic scoring of damage in ileum. Intestinal cytokine mRNA expression was determined by real-time PCR. Cytokine histologic localization was performed by confocal microscopy. Similar to human NEC, artificial feeding of RM reduces the incidence and severity of NEC injury in neonatal rats. Freezing and thawing of collected RM did not eliminate the protective effect of maternal milk. Ileal IL-10 expression was significantly increased in the RM group compared with RMS. Increased IL-10 peptide production was detected in the RM group with signal localized predominantly in the cytoplasm of villus epithelial cells. These results suggest that the protective effect of maternal milk is associated with increased production of anti-inflammatory IL-10 in the site of injury. Better understanding of the mechanisms underlying these protective effects could be beneficial either in the prevention of NEC or in the development of future therapeutic strategies to cure NEC.

Normal Breast Milk Limits the Development of Colitis in IL-10-Deficient Mice

BACKGROUND AND AIMS

This study examined the role of breast milk in neonatal bacterial colonization of the colon and disease progression in IL-10-deficient mice.

METHODS

IL-10-deficient mice were cross-fostered at birth and raised until weaning with a normal mother. Results were compared with normal pups cross-fostered to an IL-10-deficient mother. Mice were examined at various ages for histologic disease, levels of colonic bacteria, and proinflammatory cytokine secretion.

RESULTS

IL-10-deficient mice that had been cross-fostered to a normal mother demonstrated normal levels of colonic adherent bacteria and reduced TNFalpha and IFN gamma secretion at 2 to 12 weeks of age. Histologic disease was significantly reduced up to 12 weeks of age. Normal mice cross-fostered to an IL-10-deficient mother had increased levels of adherent bacteria at 2 and 4 weeks and increased IFN gamma secretion. This group also demonstrated slight inflammation up until 12 weeks of age.

CONCLUSION

Breast milk has a role in neonatal bacterial colonization. Changing the luminal environment of IL-10-deficient mice during the neonatal period alters the natural disease course.

Long term enhancement of the IgG2 antibody response to Haemophilus influenzae type b by breast-feeding

SUBJECTS

Sets of sera were obtained from 30 children <6 years of age with invasive type b (Hib) infection and their mothers. Duration and mode of breast-feeding were monitored. Titers of IgG1, IgG2, IgA and IgM antibodies against Hib capsular polysaccharide were determined in sera taken during the acute illness and during early and late convalescence.

RESULTS

Children 18 months or older with longer durations of exclusive breast-feeding (13 weeks or more; mean, 19.3 weeks) had higher Hib antibody concentrations of the IgG1, IgG2, IgA and IgM isotypes than those with a shorter duration of exclusive breast-feeding (<13 weeks; mean, 5.4 weeks). The difference was greatest for the IgG2 isotype. In regression analyses the association between the duration of exclusive breast-feeding and the anti-Hib IgG2 concentration was significant when breast-feeding, type of Hib infection, maternal Hib antibody titer and age were used as explanatory factors. In the group of 14 children <18 months of age no significant differences were noted.

DISCUSSION

This study indicates the presence of a long lasting enhancing effect of breast-feeding on the antibody response to Hib in children, in particular on IgG2 Hib antibody production. This may result from the content in the milk of IFN-gamma and IFN-gamma-producing cells and possibly other factors, which can support IgG2 antibody production.

Evolution of the mammary gland defense system and the ontogeny of the immune system

A decisive event in the evolution of mammals from synapsid reptiles was the modification of ventral thoracic-abdominal epidermal glands to form the mammary gland. The natural selection events that drove the process may have been the provision of certain immunological agents in dermal secretions of those nascent mammals. This is mirrored by similar innate immune factors in mammalian sebum and in protherian and eutherian milks. On the basis of studies of existing mammalian orders, it is evident that immune agents in milk such as immunoglobulins, iron-binding proteins, lysozyme, oligosaccharides, and leukocytes compensate for developmental delays in early postnatal production of antimicrobial factors. At least in human milk, anti-inflammatory and immunomodulating agents also evolved to provide different types of protection for the offspring. In addition, investigations reveal that the types or concentrations of immunological agents in milk vary depending upon the type of placenta, lactation pattern, and environment of the species.

Growth hormone and prolactin--molecular and functional evolution

Growth hormone, prolactin, the fish hormone, somatolactin, and related mammalian placental hormones, including placental lactogen, form a family of polypeptide hormones that share a common tertiary structure. They produce their biological effects by interacting with and dimerizing specific single transmembrane-domain receptors. The receptors belong to a superfamily of cytokine receptors with no intrinsic tyrosine kinase, which use the Jak-Stat cascade as a major signalling pathway. Hormones and receptors are thought to have arisen as a result of gene duplication and subsequent divergence early in vertebrate evolution. Mammalian growth hormone and prolactin show a slow basal evolutionary rate of change, but with episodes of accelerated evolution. These occurred for growth hormone during the evolution of the primates and artiodactyls and for prolactin in lineages leading to rodents, elephants, ruminants, and man. Placental lactogen has probably evolved independently on three occasions, from prolactin in rodents and ruminants and from growth hormone in man. Receptor sequences also show variable rates of evolution, corresponding partly, but not completely, with changes in the ligand. A principal biological role of growth hormone, the control of postnatal growth, has remained quite consistent throughout vertebrate evolution and is largely mediated by insulin-like growth factors. Prolactin has many and diverse roles. In relation to lactation, the relative roles of growth hormone and prolactin vary between species. Correlation between the molecular and functional evolution of these hormones is very incomplete, and it is likely that many important functional adaptations involved changes in regulatory elements, for example, altering tissue of origin or posttranscriptional processing, rather than change of the structures of the proteins themselves.

Up-regulation of IL-18 and IL-12 in the ileum of neonatal rats with necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a common and devastating gastrointestinal disease of premature infants. Because the proinflammatory cytokines IL-18, IL-12, and interferon (IFN)-gamma have been implicated in other diseases of the small intestine, we hypothesized that these cytokines would play an important role in NEC pathogenesis. NEC was induced in newborn rats via enteral feeding with rat milk substitute and asphyxia and cold stress (RMS). Dam-fed, asphyxia- and cold-stressed littermates were used as controls (DF). After 96 h, the distal ileum was removed from all animals and processed to determine expression and localization of IL-18, IL-12, and IFN-gamma using real-time reverse transcriptase PCR and immunohistology. IL-18 and IL-12 mRNA from the RMS group were increased (p < or = 0.05) compared with DF controls, and there was a correlation between increasing IL-18 and IL-12 mRNA levels and progression of tissue damage (r = 0.629 and 0.588, respectively; p < or = 0.05). Immunohistology revealed IL-18 in the cytoplasm of villi and crypt enterocytes and IL-12-positive monocytes/macrophages were increased with disease progression (r = 0.503, p < or = 0.05). No differences in the number of IFN-gamma-positive cells were observed between groups. These data demonstrate up-regulation of IL-18 and IL-12 in experimental NEC and a correlation between production of these proinflammatory cytokines and progression of tissue damage.

Breast-feeding protects against celiac disease

BACKGROUND

Celiac disease, or permanent gluten-sensitive enteropathy, is an immunologic disease strictly dependent on exposure to wheat gluten or related proteins in rye and barley.

OBJECTIVE

The aim of this study was to explore whether breast-feeding and the mode of introducing dietary gluten influence the risk of celiac disease in childhood.

DESIGN

A population-based incident case-referent study of Swedish children, 627 cases with celiac disease and 1254 referents, was conducted; 78% of the matched sets were included in the final analyses. A questionnaire was used to assess patterns of food introduction to infants. Models were built, based on current epidemiologic and immunologic knowledge of celiac disease, to study the potential influence of dietary patterns on disease risk and were evaluated by conditional logistic regression in multivariate analyses.

RESULTS

The risk of celiac disease was reduced in children aged <2 y if they were still being breast-fed when dietary gluten was introduced [adjusted odds ratio (OR): 0.59; 95% CI: 0.42, 0.83]. This effect was even more pronounced in infants who continued to be breast-fed after dietary gluten was introduced (OR: 0.36; 95% CI: 0.26, 0.51). The risk was greater when gluten was introduced in the diet in large amounts (OR: 1.5; 95% CI: 1.1, 2.1) than when introduced in small or medium amounts. In older children, these risk factors were of no or only minor importance.

CONCLUSIONS

The gradual introduction of gluten-containing foods into the diet of infants while they are still being breast-fed reduces the risk of celiac disease in early childhood and probably also during the subsequent childhood period.

Expression of biologically active human tumor necrosis factor-alpha in transgenic potato plant

We report the successful insertion of the cDNA of human tumor necrosis factor-alpha (HuTNF-alpha) into the genome of potato plant species, Solanum tuberosum, using Agrobacterium tumefacience-mediated transformation. HuTNF-alpha is a known and essential cytokine mediating host defense against tumors and infectious diseases and an immunomodulating agent. To enhance the accumulation of foreign gene product expression in plant cells, the molecular design of the constructed HuTNF-alpha is presented. Transcription and translation of TNF-alpha in transformants were confirmed by Northern blot, RT-PCR, ELISA, and Western blot, respectively. Expression of the bioactive HuTNF-alpha in plant cells was confirmed by way of the cytotoxic effect of the extract obtained from the transformants against murine L929 cells. We think that the expression level of HuTNF-alpha (15 microg/g potato plant tissue) obtained in the present study may be sufficient to induce responses/effects similar to those generated by TNF-alpha in human milk administered orally. We believe that the TNF-alpha expressed in edible potato plants has tremendous potential for clinical use in the areas of medicine and veterinary science. Its usefulness and applicability, therefore, need to be fully explored.

Lactoferrin protects neonatal rats from gut-related systemic infection

Lactoferrin is a milk protein that reportedly protects infants from gut-related, systemic infection. Proof for this concept is limited and was addressed during in vivo and in vitro studies. Neonatal rats pretreated orally with recombinant human lactoferrin (rh-LF) had less bacteremia and lower disease severity scores (P < 0.001) after intestinal infection with Escherichia coli. Control animals had 1,000-fold more colony-forming units of E. coli per milliliter of blood than treated animals (P < 0.001). Liver cultures from control animals had a twofold increase in bacterial counts compared with cultures from rh-LF-treated pups (P < 0.02). Oral therapy with rh-LF + FeSO(4) did not alter the protective effect. In vitro studies confirmed that rh-LF interacted with the infecting bacterium and rat macrophages. An in vitro assay showed that rh-LF did not kill E. coli, but a combination of rh-LF + lysozyme was microbicidal. In vitro studies showed that rat macrophages released escalating amounts of nitric oxide and tumor necrosis factor-alpha when stimulated with increasing concentrations of rh-LF. The in vitro studies suggest that rh-LF may act with other "natural peptide antibiotics" or may prime macrophages to kill E. coli in vivo.