Download Full Text - the American Society of Animal Science

Published December 4, 2014
COMPANION ANIMALS SYMPOSIUM: Development
of the mammalian gastrointestinal tract, the resident microbiota,
and the role of diet in early life1
R. K. Buddington*2 and P. T. Sangild†
*Department of Health and Sport Science, University of Memphis, Memphis, TN 38152;
and †Department of Human Nutrition, University of Copenhagen, DK-1958 Frederiksberg C, Denmark
ABSTRACT: Mammalian gastrointestinal (GI) development is guided by genetic determinants established during the evolution of mammals and matched
to the natural diet and environment. Coevolution of the
host GI tract (GIT) and the resident bacteria has resulted in commensal relationships that are species and
even individual specific. The interactions between the
host and the GI bacteria are 2-way and of particular
importance during the neonatal period, when the GIT
needs to adapt rapidly to the external environment,
begin processing of oral foods, and acquire the ability to differentiate between and react appropriately to
colonizing commensal and potentially pathogenic bacteria. During this crucial period of life, the patterns
of gene expression that determine GI structural and
functional development are modulated by the bacteria
colonizing the previously sterile GIT of fetuses. The
types and amounts of dietary inputs after birth influence GI development, species composition, and metabolic characteristics of the resident bacteria, and the
interactions that occur between the bacteria and the
host. This review provides overviews of the age-related
changes in GIT functions, the resident bacteria, and
diet, and describes how interactions among these 3 factors influence the health and nutrition of neonates and
can have lifelong consequences. Necrotizing enterocolitis is a common GI inflammatory disorder in preterm
infants and is provided as an example of interactions
that go awry. Other enteric diseases are common in all
newborn mammals, and an understanding of the above
interactions will enhance efforts to support neonatal
health for infants and for farm and companion animals.
Key words: bacteria, development, diet, gastrointestinal, mammal, ontogeny
©2011 American Society of Animal Science. All rights reserved.
J. Anim. Sci. 2011. 89:1506–1519
doi:10.2527/jas.2010-3705
INTRODUCTION
“We must cultivate our garden,” says Candide (from
Candide; Voltaire, 1759). When Candide left sheltered
castle life and entered into the external world, he faced
challenges and hardships, and his survival was dependent on discriminating between good and evil. Similarly,
when the fetus emerges from the shelter of the womb,
the immature gastrointestinal tract (GIT) must adapt
1
Based on a presentation at the Companion Animals Symposium
titled “Microbes and Health,” at the Joint Annual Meeting, July 11
to 15, 2010, Denver, Colorado. The symposium was sponsored, in
part, by Hill’s Pet Nutrition Inc. (Topeka, KS) and The Procter &
Gamble Company (Cincinnati, OH), with publication sponsored by
the Journal of Animal Science and the American Society of Animal
Science.
2
Corresponding author: [email protected]
Received November 15, 2010.
Accepted January 12, 2011.
rapidly to oral feeding, the challenges of extrauterine
life, and cultivating the garden of colonizing bacteria.
Complex interactions have evolved between the mammalian host and the gastrointestinal (GI) microbiota
(Ley et al., 2008). Apparently, the extreme costs that
would be imposed on the host by trying to maintain a
sterile GIT are outweighed by the benefits of instead
establishing commensal relationships with bacteria that
provide health and nutritional benefits and that pose
little or no risk to the host. Hence, the GIT has come to
accept the presence of numerous species of bacteria at
densities such that shortly after birth, GI bacterial cells
outnumber those of the host by about 10-fold.
Much like the challenges faced by Candide, after
birth the GIT must establish and maintain a delicate
balance between the recognition and exclusion of pathogens and the tolerance of commensal bacteria. The GI
disorder necrotizing enterocolitis (NEC) is exemplary
of the consequences when the balance is disrupted between exclusion and tolerance and when members of
the commensal bacteria trigger excessive inflammatory
1506
Gastrointestinal development, bacteria, and diet
responses, thereby compromising the health of the neonate (Claud, 2009).
The interactions among the GIT, the resident microbiota, and diet begin at birth, when the sterile epithelium of the GIT first encounters the colonizing bacteria and begins processing the first meals. During this
critical period of life, genetic determinants of immune
responses play a central role in the recognition and responses of the developing GIT to the colonizing bacteria. Although dietary inputs influence postnatal development of the GIT, less understood are how dietary
inputs have the potential to influence the interactions
between the GI epithelium and the colonizing bacteria. The contrasting responses of the neonatal GIT and
the resident bacteria among infants fed breast milk and
those fed formula (Hanson, 2007; Penders et al., 2007)
highlight how interactions among the genetic determinants of GI characteristics, the resident bacteria, and
dietary inputs must be considered together to understand postnatal GI development in health and disease.
The objective of our review is to acquaint readers
with the responses of the neonatal mammalian GIT to
the bacteria that colonize and become established, and
how diet is an important factor in those interactions.
We first provide readers with a general understanding
of mammalian GI development, the postnatal changes
in the resident bacteria, and shifts in dietary inputs.
Although the changes described are shared among different mammalian species, there are differences in the
timing and specifics of the developmental events. Next,
we describe the interactions that exist among genetic
determinants of GI structure and function, the resident
bacteria, and diet. A subsequent section uses NEC, often observed in preterm infants, as an example to describe the consequences when the interactions among
GI development, the resident bacteria, and diet go
awry. We conclude by discussing some dietary strategies to improve mammalian health by optimizing the
interactions between the developing GIT and the resident microbiota.
DEVELOPMENT OF THE GIT
The GIT represents a critical and expansive interface
between the external environment and the host. Organogenesis and maturation of the GIT during prenatal
life prepare the fetus for the transition at birth from the
sterile intrauterine environment and reliance on placental nutrition to the immediate and dramatic changes in
the functional demands placed on the GIT by exposure
to the contaminated environment, by digesting food,
and by other challenges of extrauterine life. The importance of the GIT being functional at the time of birth
is evident by the complications of preterm birth and
the consequences of immature GI functions. A notable
example is the increased risk of NEC among preterm
infants, as discussed subsequently.
During prenatal development, the GIT acquires the
capacities to 1) digest food; 2) defend against patho-
1507
gens; 3) contribute to osmoregulation; 4) secrete hormones and other signaling molecules that regulate the
GIT and other host systems, and 5) detoxify and eliminate toxins produced by metabolism and acquired from
the external environment. Some of the GIT capabilities
that develop prenatally are vital for the fetus to process
the large volumes of amniotic fluid swallowed (up to
750 mL/d by human fetuses; Pritchard 1966). At term,
the GIT is able to process milk, respond to bacterial
colonization, and tolerate extrauterine environmental
conditions. However, the specific structural and functional characteristics of the GIT at birth vary among
species. This is exemplified by comparisons of the GIT
among newborns of altricial and precocial species with
different adult feeding habits and from different environments (Stevens and Hume, 1995).
The changes in the GIT associated with weaning
can be accelerated by advancing the transition from
milk to the adult diet and can be delayed, but not prevented, by extending suckling. This highlights how the
patterns and trajectories of GI development are established by genetic determinants (i.e., are “hard wired”),
yet the programmed series of events are responsive to
dietary inputs (Drozdowski et al., 2010) and environmental conditions (Bailey and Haverson, 2006) and are
capable of some flexibility, to allow the developing GIT
to adapt to existing conditions (Lebenthal and Lebenthal, 1999). Evidence also exists for “critical period
programming” of GI characteristics, whereby dietary
inputs early in life can induce epigenetic changes that
persist past the period of exposure and can last for the
lifetime of an individual (Drozdowski et al., 2010). This
includes early programming of the GI immune system
by the colonizing bacteria and environmental antigens
(Mulder et al., 2009).
Digestion
At term, the GIT is adapted for and ready to process
the first food, which, for most mammals, is colostrum
(Drozdowski et al., 2010). The immature digestive functions of preterm infants are considered to contribute to
the increased risk of NEC (reviewed by Claud, 2009)
and are why total parenteral nutrition (TPN) is used
to meet nutrient and energy needs until the GIT develops adequate capacities to process food.
Suckling mammals have a minimal capacity to modulate digestive processes adaptively in response to changes in diet composition (Buddington, 1994) and do not
acquire the ability to process the adult diet until just
before weaning (Drozdowski et al., 2010). When neonates are not fed breast milk, diarrhea can result when
the alternate diet includes ingredients such as sucrose,
for which there is inadequate expression of sucrase.
Defense
The GI immune system provides a comprehensive,
multilayered defense (Winkler et al., 2007). Much like
1508
Buddington and Sangild
a gardener, the GI immune system is able to differentiate among the numerous types of GI bacteria that
represent a threat and that should be tolerated, and
this contributes to the selection of an assemblage of
commensal bacteria (Ogra, 2010). This is the culmination of coevolution between the resident bacteria and
the innate and adaptive components of the GI immune
system, and is dependent on a diversity of extracellular
Toll-like receptors (TLR) and intracellular nucleotidebinding oligomerization domain receptors (Shibolet
and Podolsky, 2007; Richardson et al., 2010). Aberrant and excessive reactions of the GI immune system
to commensal bacteria and other antigens in the GIT
causes inflammation and has been associated with several pathologies, including NEC in preterm infants and
inflammatory bowel disease, celiac disease, and various
food allergies in children and adults. Conversely, inadequate recognition of or responses to pathogens pose
obvious health risks.
The GI immune functions develop prenatally, and at
term, they are capable of recognizing and responding
to pathogens, including bacterial DNA motifs and vaccines (Lacroix-Lamandé et al., 2009). Additional development and maturation occur after birth, and the
several phases described for the porcine GI immune
system (Bailey and Haverson, 2006) are relevant to
most mammals.
The innate GI defenses include secretions of acid,
antimicrobial peptides, lysozyme, and mucus; as well as
the tight junctions that link epithelial cells and provide
a physical barrier; activated defense cells (e.g., macrophages, neutrophils); and intestinal motility (Eckmann,
2006). These are supplemented at birth by the transient ability of the enterocytes of neonates to absorb
antibodies intact and transfer the antibodies present
in colostrum to the systemic circuit of newborns (transcytosis), conferring passive immunity. This is dependent on the expression of a receptor (Fc) on the apical
membrane that binds the IgG in breast milk (Van de
Perre, 2003).
The adaptive component of the GI defenses includes
the organized lymphoid tissues (e.g., Peyer’s patches,
mesenteric lymph nodes) that are associated with the
GIT, the B and T classes of lymphocytes, and the antigen-presenting dendritic cells (Rumbo and Schiffrin,
2005). A key difference between the adaptive components of the GI and systemic immune systems, despite
sharing similar cell types, is the development of oral
tolerance, whereby the GI immune system learns to discriminate between bacteria and antigens that pose little
or no risk and those that are dangerous (Magalhaes
et al. 2007). The learning process has occurred during
the coevolution of hosts with their GI bacteria, resulting in receptors and associated signaling pathways and
innate defense mechanisms that can discriminate between “the good, the bad, and the ugly.” At birth, the
cellular and tissue elements of the adaptive component
are less abundant and immature compared with those
in the adult, with maturation and learning occurring
after birth (Rumbo and Schiffrin, 2005; Mshvildadze
and Neu, 2010). The even more immature status of the
GI defenses of preterm infants with increased and less
regulated nuclear factor-κB signaling contributes to the
hyperresponsiveness of the GIT, the increased risk of
GI inflammatory disorders such as NEC, and the increased incidence of sepsis (Claud 2009).
Osmoregulation
The osmoregulatory challenges facing the GI tract
differ markedly between fetuses dependent on placental
exchange of water and electrolytes and neonates dependent on processing of milk to obtain electrolytes and
water. Chloride channels exist in the fetal GI epithelium
(Murray et al., 1996), but colonic expression of the sodium channel (also known as ENaC) and absorption of
sodium are underdeveloped or are suppressed in fetuses
(Watanabe et al., 1998). This may contribute to the osmoregulatory problems, including sodium imbalances,
and the special nutritional needs of premature infants.
Postnatally, the osmoregulatory functions of the GIT
respond to inflammatory cytokines by a combination of
decreased ion absorption and increased chloride secretion. The resulting diarrhea and the loss of electrolytes
and water are the major cause of morbidity and mortality among newborn animals and infants.
Endocrine Secretion
Collectively, the regions of the GI tract and the associated organs (e.g., pancreas) represent the largest
endocrine system in the vertebrate body. Furthermore,
a linkage exists between the GI endocrine and immune
functions, leading to the concept of the GI immunoendocrine axis. Specifically, enteroendocrine cells express
TLR and respond to luminal antigens by the production of cytokines and defensins (Palazzo et al., 2007;
Selleri et al., 2008), and they respond to cytokines and
other regulatory molecules originating from GI immune
cells. Hence, GI immune responses to colonizing bacteria can alter endocrine secretions by the neonatal GI
tract, thereby having GI and systemic implications.
The vast diversity of secreted peptides is critical for
regulating GI (e.g., gastrin, secretin, cholecystokinin)
and systemic functions (e.g., insulin, glucagon, ghrelin).
Despite reports of prenatal development of GI endocrine
cells (Alumets et al., 1983) and expression of receptors for epidermal growth factor (Chailler and Ménard,
1999), glucagon-like peptide 2 (Burrin et al., 2003), and
cholecystokinin (Bourassa et al., 1999), there is only a
fragmentary understanding of ontogenetic development
of the GI endocrine functions.
Detoxification
The GIT plays a role in the detoxification and elimination of ingested toxins, including drugs and meta-
Gastrointestinal development, bacteria, and diet
bolic wastes from the host and the resident bacteria
(Buddington, 2009). This is accomplished by a combination of enzymes that convert and detoxify noxious
molecules and export transporters that eliminate the
resulting xenobiotic compounds. Although xenobioticconverting enzymes are expressed in the liver during
late gestation, ontogenetic patterns of development for
the numerous enzymes and transporters responsible for
the detoxification functions of the GIT are not well
characterized (Myllynen et al., 2009).
THE ASSEMBLAGES OF BACTERIA
IN THE GIT
The adult GIT is estimated to harbor 400 to 500 species of bacteria, with some estimates of >800 species
and >7,000 strains (O’Keefe, 2008). The majority of
the GI bacteria have yet to be cultured, and although
molecular-based approaches of detection have increased
our understanding of the bacterial diversity, these
methods have provided few insights into the functional
characteristics of the bacteria and their influences on
host health (Flint et al., 2007). The GI microbiota also
include fungi, protozoa, yeasts, viruses, and bacteriophages (Mackie et al., 1999) that influence host health
and nutrition. Of critical interest are the interactions
that develop between the microbiome and the GIT of
infants (Mshvildadze and Neu, 2010).
Regional Distribution
The GIT can be considered a small ecosystem (Buddington and Weiher, 1999), with multiple habitats (regions). Within each region, there are dynamic interactions among the resident bacteria, dietary inputs, and
the structure and functions of the region that determine the physical, chemical, and biotic characteristics
(Kelly et al., 2007). The interactions are even more
pronounced during the postnatal period, when the
combination of dietary inputs, developing GI functions,
and interbacterial interactions play central roles in determining the densities, diversities, and distributions
of species that become established within the different
regions of the GIT ecosystem.
The acidic stomach of adult nonruminant mammals
harbors a decreased density (<104 cfu/g) and diversity
of bacterial species compared with the small intestine
and colon, despite the increased input of nutrients. Bacterial densities and diversity are similarly small in the
acid-secreting portion of the ruminant stomach (abomasum), despite the complex and numerically abundant assemblages of bacteria present in the preceding
rumen (Nelson et al. 2003).
The densities and diversity of bacteria increase distally along the small intestine, with the greatest densities
(1011 to 1012 cfu/g) and diversities being in the colon.
The declining gradient for oxygen from the proximal
small intestine to the colon is paralleled by a reciprocal
1509
decline in the aerotolerant bacteria and an increase in
the anaerobic species of bacteria. Additional environmental factors that contribute to the proximal-to-distal
gradients along the small intestine and colon for the
densities and diversities of species include more rapid
movement of the digesta proximally and the introduction into the duodenum of bile acids from the gall bladder and antibacterial peptides secreted by the pancreas
and the intestine itself (e.g., defensins from Paneth
cells). Even within the colon, there is a proximal-todistal distribution of species and metabolic activities.
The proportions of saccharolytic bacteria and shortchain fatty acid (SCFA) production are greater in the
proximal colon, whereas proteolytic bacteria and the
production of putrefactive metabolites are more prevalent in the distal colon (Macfarlane and Macfarlane,
2003). This distribution corresponds with the greater
distal production of ammonia, phenols, indoles, amines,
and other toxic and carcinogenic metabolites, which, in
adults, contributes to a greater incidence of colorectal
cancer in the distal colon.
Vertical gradients that extend from the epithelium
into the lumen also exist for the distribution of species
in the GIT (Kleessen and Blaut, 2005). The populations of bacteria adherent to or immediately adjacent
to the epithelium have a profound impact on the GIT
and the host, yet they are less understood.
Colonization of the Neonatal GIT
The sterile GIT of fetuses is rapidly colonized, and
within 12 h after delivery, bacteria can be detected
throughout the entire GIT and at densities (i.e., cfu/g)
that are comparable with those of adults (Mackie et al.,
1999). The similar fecal densities of bacteria enumerated in the colons of infants and adults may reflect a
maximum density of bacteria that can be supported by
the GIT (i.e., “carrying capacity”).
Colonization is a stochastic process and results in
individual variation in GI bacterial assemblages. This
is true even among littermates (Tannock et al., 1990),
monozygotic twins (Stewart et al., 2005), and even
identical twins (Dicksved et al., 2008). Infants delivered vaginally are colonized by bacteria originating
from the maternal GIT, vagina, skin, and surrounding
environment (Mackie et al. 1999; Huurre et al., 2008).
Infants delivered by caesarian section are not immediately exposed to maternal fecal and vaginal bacteria.
Instead, the initial colonizers are nosocomial, originating from medical staff and the hospital environments.
Additional bacteria are eventually acquired from the
mother (skin, mammary glands) and from outside the
hospital environment. Corresponding with the different
sources and timing of colonization, the assemblages of
GI bacteria differ between infants born vaginally and
by caesarian section. The influence of delivery mode on
the assemblages is still apparent up to 7 yr after birth
(Salminen et al., 2004). Other nondiet factors consid-
1510
Buddington and Sangild
ered to influence the GI assemblages that colonize and
become established are gestational age at delivery, diet,
antibiotic use, and the external environment (Penders
et al., 2006). Infants with assemblages considered to be
beneficial, with fewer pathogens, are typically delivered
vaginally outside of hospitals and are exclusively fed
breast milk.
Which bacteria persist in the GIT is less random,
providing supporting evidence for species-specific hostbacteria relations. Notable are the different species of
Helicobacter that have been isolated from different vertebrates (Schrenzel et al., 2010). Hence, not all species
of bacteria entering the GIT, including probiotic species, are able to persist.
Ecological Principles and the GI Bacteria
After the initial period of colonization, interbacterial interactions contribute to the changes in species
composition and metabolic activities of the resident
bacteria (Mackie et al., 1999; Flint et al., 2007). This
includes the competitive exclusion of pathogens, probiotics, and other bacteria by commensal bacteria. The
mechanisms of exclusion include competition for nutrients and binding sites and the production of metabolites that are toxic to other groups. The process of
facilitation, which can be described as cooperative relationships among organisms, leads to further changes
in the GI environment, resulting in assemblages with
different dominant species. In the GIT, the aerotolerant species that initially dominate reduce the oxygen
tension and thereby favor the emergence of anaerobic
groups. Another example of interbacterial interactions
is a metabolic cross-feeding, whereby one group of
bacteria produces metabolites that are used by other
groups (Flint et al., 2007). This includes the conversion of lactate produced by bifidobacteria into butyrate
and other SCFA by other anaerobic members of the GI
bacteria. Recent studies have described quorum sensing
among the GI bacteria, triggering adaptive changes in
the characteristics of individual bacterial species (Allen
and Torres, 2008) and perhaps host cells (Sperandio et
al., 2003). The gradual changes in the species composition and distributions of the resident bacteria that
occur with increasing age are representative of the ecological principle of succession. Eventually the changes
culminate in a “climax community” of species.
The composition and productivity of the resident species are also influenced by the stability and extremes of
the local environment (Buddington and Weiher, 1999).
Environments that are harsh (e.g., stomach) or subject to frequent and large disturbances (e.g., proximal
small intestine) have decreased densities and diversities
of species. Ecosystems with the greatest densities and
diversities of species are characterized by benign conditions and with intermittent disturbances of intermediate magnitude that are sufficient to prevent one or a
few species from becoming dominant. In the GIT, the
proximal colon provides such an environment and correspondingly has the greatest densities, diversities, and
species evenness of bacteria.
Among infants, the greatest disturbances to the GI
ecosystem are caused by diarrhea and the administration of antibiotics. Both cause dramatic declines in the
densities and diversities of the resident bacteria, with a
shift in the dominant species (Tanaka et al., 2009). This
has the potential to influence GI development (Mshvildadze and Neu, 2010) and actually increase the risk of
NEC (Cotten et al., 2009). It is important to note that
the disturbances caused by even short-term antibiotic
administration may persist for at least 2 yr (Jernberg
et al., 2010).
DIETARY INPUTS DURING
POSTNATAL DEVELOPMENT
There is growing appreciation of the influences of
diet on the ontogeny of the GIT and the assemblages of bacteria that colonize it and become established
(Newburg and Walker, 2007). Neonatal mammals are
dependent on breast milk to varying degrees, ranging
from the extreme dependency of altricial species, such
as marsupials and many laboratory rodents, to the very
short periods of suckling for precocial species, such as
guinea pigs, which begin to eat the adult diet shortly
after birth. Milk composition varies widely among species (Jenness and Sloan, 1970). Notable is the absence
of lactose in the milk of pinnipeds, the greater concentration of oligosaccharides in human milk (Newburg,
2009), and the wide species variation in protein, carbohydrate, and fat content. Milk composition is also not
consistent during lactation. Colostrum, the first milk
produced after birth, has greater protein content because of the increased concentration of immunoglobulins and a diversity of regulatory proteins. Within days
after birth, the composition begins to shift from colostrum to mature milk, with the composition typical
of the species. Apparently, milk composition has been
refined over evolutionary time to match the unique species, age, and individual demands of infants.
Manufacturers of formulas for human infants and
milk replacers for companion and production animals
attempt to mimic the composition of the milk of the
target species. The present formulas are relatively simple, with far fewer components than breast milk. There
are intense efforts to identify ingredients that can be
added to formulas and milk replacers that will promote
patterns of GI development and the establishment of
commensal assemblages of bacteria that are similar to
those when infants are fed breast milk and when neonates of other species are allowed to nurse their dams.
For most species and individuals, weaning is a gradual process, with a progressive decline in milk consumption and an increased dependency on the adult diet
to provide energy and nutrients. During this period,
GI functions and the resident assemblages of bacteria
Gastrointestinal development, bacteria, and diet
gradually become adult-like. When
or early, diarrhea often results and
changes in the species composition
tivities of the GI bacteria (Lallès et
weaning is sudden
is accompanied by
and metabolic acal., 2007).
Influences of Diet on GI development
The rapid postnatal growth and maturation of the
GIT are dependent on dietary inputs and are delayed
when neonates are provided TPN rather than fed enterally. The importance of luminal nutrients for development of the neonatal GIT has led to the concept of minimal enteral nutrition (atrophic feeding), whereby small
amounts of oral nutrients are provided during TPN to
encourage GI growth and maturation and reduce the
risk of bacterial translocation and sepsis (Bombell and
McGuire, 2009).
The composition of the food fed to neonates is a determinant of GI growth, maturation, and health. Colostrum includes immunoglobulins that provide passive
immunity to the neonate and numerous hormones, cytokines, and other regulatory molecules that stimulate
GI growth and maturation, including immune functions
(Hanson, 2007). Even coating the mouth of preterm
neonates with colostrum may be adequate to stimulate
the development of GI and systemic immune functions
(Rodriguez et al., 2010).
The change in diet composition at weaning triggers
changes in enterocyte cytokinetics and patterns of gene
expression, coinciding with changes in absorptive and
secretory functions (Drozdowski et al., 2010). The secretory characteristics of GI accessory organs, including the pancreas, are also responsive to the diet change
at weaning.
Influence of Diet on the Developing
Assemblages of Bacteria
The inputs into ecosystems are key determinants of
the abundances, diversity, and production of the resident organisms. Similarly, the assemblages of GI bacteria are responsive to dietary and host inputs (Buddington and Weiher, 1999; Koenig et al., 2010). This is
evident from the disturbance to the assemblages of GI
bacteria induced by prolonged administration of TPN
(Alverdy et al., 2005), causing increases in pathogens
and risks of secondary diseases (Harvey et al., 2006). It
is not surprising that the amount and composition of
the diet fed to infants influence the postnatal changes
in the GI bacteria. By doing so, diet indirectly influences postnatal GIT development and disease resistance
(Amarri et al., 2006).
A central question surrounding neonatal health and
nutrition is, “How does breast milk adventitiously influence the developing assemblage of bacteria?” The majority of studies report that infants fed breast milk have
less incidence of disease. This corresponds to greater
fecal densities of lactic acid-producing bacteria (e.g.,
1511
bifidobacteria and lactobacilli) compared with infants
receiving formula (Penders et al., 2006). Breast milk
also reduces the densities of bacteria adherent to the
mucosa, and this may contribute to the reduced risk
of NEC (Van Haver et al., 2009). It is interesting that
providing infants with only a small volume of formula
can elicit dramatic changes in the GI bacteria (Mackie
et al., 1999). The different patterns of microbial gene
expression among piglets fed by the sow or given milk
replacer (Poroyko et al., 2010) raises an intriguing possibility that milk has evolved attributes that favor the establishment and dominance of commensal bacteria that
provide health and nutritional benefits and that remove
undesired species. The discovery of the immune modulation and health benefits of nucleotides (Yu, 2002),
which include beneficially modulating the GI bacteria
(Singhal et al., 2008), led to the inclusion of nucleotides
in infant formulas. Other components of milk reported
to provide more than energy and nutrients to infants
that can modify the resident bacteria include IgA, human milk oligosaccharides (HMO), lactose, lysozyme,
and lactoferrin (Newburg, 2009).
A portion of the lactose in milk is not hydrolyzed
during transit of the small intestine and is metabolized
by colonic bacteria, causing an increase in breath hydrogen. This is particularly true among preterm infants
(Kien et al., 1998) and exemplifies how diet influences
bacterial metabolism (González et al., 2008). Although
lactose fermentation has been interpreted as lactase insufficiency, it may contribute to shifting the luminal
environment to be more conducive to commensal bacteria.
The multifunctional and diverse HMO are the third
most abundant component of human milk, with species
and individual differences in the amounts, types, and
proportions (Newburg, 2009). The majority of HMO
are not digested during transit of the GIT and are considered to encourage the establishment of commensal,
health-promoting bacteria by a combination of having prebiotic properties, serving as receptor mimics for
pathogens, and modulating mucosal immune functions
(Newburg, 2009; Eiwegger et al., 2010). The protein
lactoferrin, although abundant in human, but not cow,
milk (Coppa et al., 2006), is absent from present infant
formulas. Lactoferrin is considered to be immunomodulatory (Suzuki et al., 2005), to have the potential to influence the assemblages of bacteria by being bifidogenic
(Coppa et al., 2006), and to have the ability to reduce
sepsis among preterm infants (Venkatesh and Abrams,
2010). Collectively, the components of milk highlight a
coevolution between milk composition, the developing
GIT, and the resident bacteria. Combined, they effectively enhance the ability of the neonate to “cultivate
a garden” of health-promoting bacteria. There is also
interest in novel ingredients that are not milk based but
that may beneficially influence the species composition
of the GI bacteria when fed to infants [e.g., prebiotics
and probiotics (Sherman et al., 2009)].
1512
Buddington and Sangild
The historical emphasis has been on formula ingredients that improve the species composition of the GI
microbiota. Less considered, but of critical importance,
is the influence of diet on bacterial enzymes (Grönlund
et al., 1999), hence metabolism. Bacterial metabolism
and the production of SCFA and other metabolites are
related to the types and amounts of substrates (Macfarlane and Macfarlane, 2003), such as the responses of
the GI bacteria to lactose (Mäkivuokko et al., 2006).
Although total concentrations of fecal SCFA are similar
for preterm infants fed expressed breast milk or a commercial infant formula (P > 0.9), those fed breast milk
have greater concentrations of propionate but relatively
less acetate (P < 0.05; R. K. Buddington, unpublished
data). It is interesting that the SCFA profiles of the
preterm infants fed expressed breast milk are similar to
those we have measured for healthy adults.
INTERACTIONS BETWEEN
THE BACTERIA AND THE INTESTINE
The interactions between the resident bacteria and
the host GIT involve 2-way communication. This results in gene expression being modulated in the bacteria and the host (Allen and Torres, 2008; Sharma et
al., 2010). Moreover, by modulating the expression of
host genes, the resident bacteria modify the GI environment, which in turn alters the interactions and balances
among the GI bacteria (Mahowald et al., 2009). The
complex interactions result in GIT ecosystems that are
unique for species, individuals, life history stages, and
health states (Dunne 2001), and these can have longterm immune and health implications (Conroy et al.,
2009).
The interactions between the host and the GI bacteria
occur over 3 time scales. There are rapid and reversible
interactions that span minutes to hours, other interactions that occur during the life history of individuals, and those that occur over evolutionary time scales.
There is ample evidence for the coevolution of the host
GIT and the resident bacteria (Ley et al., 2008). This
results in commensal and symbiotic relationships that
are species specific and that involve genetic adaptations
of the bacteria to the host GIT (Schell et al., 2002).
The cooperative responses of the GI immune system
to the different bacteria have established mutualisms
(Slack et al., 2009).
The interactions that occur during the life of an individual influence the characteristics of the host and the
assemblages of bacteria (densities, diversity, evenness,
regional distribution, and functional attributes). These
interactions are particularly relevant to neonates and
have been the subject of numerous studies and reviews.
Specifically, the early responses of the GIT and the
resident bacteria can have lifelong health consequences
through epigenetic mechanisms. These include the ability of some bacteria to alter the patterns of host gene
expression, such as patterns of glycosylation for extra-
cellular proteins (Freitas et al., 2002) in ways that benefit both the commensal bacteria and the host (Bry et
al. 1996). Another relevant example is the relationship
between early antigen exposure and the risk of allergies and asthma later in life (the “hygiene hypothesis”;
Shreiner et al., 2008).
Less understood are the rapid and reversible interactions during infancy between the GIT and the bacteria. These transient interactions occur over periods of
minutes to hours and allow the GIT and the resident
bacteria to adapt to changing conditions, such as those
that occur during and between meals of varying size
and composition.
The interactions between the bacteria and the GIT
can be direct, via cell-to-cell contacts. Typically, the
adverse influences of pathogenic bacteria require direct
contact with epithelial cells and are mediated by surface
molecules (Zoumpopoulou et al., 2009). Exemplary is
how the attachment of pathogenic Escherichia coli, Salmonella, clostridia, and other pathogens is required to
trigger the expression of virulence genes, such as those
coding for toxins, invasive mechanisms, or Type III secretion systems that alter the characteristics or cause
the death of the attached enterocytes. Members of the
commensal bacteria and some probiotic strains are considered to inhibit pathogen adherence and pathogenesis
by occupying sites of attachment and by inducing enterocyte expression of the mucin-encoding gene MUC2
and other defense genes that inhibit attachment (Kim
et al., 2008) by the production of immunomodulatory
molecules (Mazmanian et al., 2005).
The influences of the bacteria can also be indirect
and mediated by metabolites that alter host gene expression, beneficially or adversely. Some species of bifidobacteria release soluble factors that decrease epithelial cell secretion of inflammatory cytokines (Heuvelin
et al., 2009) and chloride (Heuvelin et al., 2010). The
SCFA produced by bacterial fermentation of undigested
feedstuffs provide up to 10% of the total metabolic energy requirement of humans and even greater percentages among animals with larger hindguts or rumens
(Rechkemmer et al., 1988). Corresponding with this,
gnotobiotic rodents require 30% more dietary energy
and vitamin supplements compared with conventional
rodents harboring commensal bacteria capable of fermenting undigested feedstuffs. The SCFA influence colon health (Wong et al., 2006), alter patterns of epithelial cell gene expression (Sanderson, 2004; Vanhoutvin
et al., 2009), and stimulate secretion of regulatory peptides that enhance growth and functions of the proximal small intestine (Bartholome et al., 2004). The responses to butyrate are more pronounced than those to
acetate and propionate (Basson et al., 2000). However,
excessive production of SCFA, including butyrate, has
been associated with damage to the GI epithelium and
may contribute to NEC (Lin et al., 2005).
Often overlooked is the competition between the GIT
and the resident bacteria for nutrients. Maintaining re-
Gastrointestinal development, bacteria, and diet
duced densities of bacteria in the proximal small intestine by peristalsis and antibacterial secretions from the
pancreas and intestine provides the GIT with the first
access to readily available, digestible nutrients. Food
not available to the host can and will be metabolized
by the bacteria.
The Resident Bacteria Influence
the Developing GIT
Profound differences exist between germ-free and
conventional rodents with respect to villus architecture,
and enterocyte patterns of proliferation, differentiation,
and gene expression (Zocco et al., 2007) and mucosal
immune responses (Williams et al., 2006; Hrncir et al.,
2008). Bacteria isolated from the GIT of neonates are
reported to enhance maturation of the GIT by modulating gene expression (Are et al., 2008). This includes
the age-related shifts in the activities of the fucosyl- and
sialyltransferases responsible for the weaning-related
changes in the glycosylation of enterocyte glycoproteins
(Nanthakumar et al., 2005). Even patterns of intestinal motility are responsive to the resident bacteria (Lesniewska et al. 2006).
The interactions between the colonizing bacteria and
the developing GI immune functions have immediate
and long-term consequences on host health (Dimmitt
et al., 2010; Mshvildadze and Neu, 2010). The combination of colonizing bacteria, food, and environmental
antigens activate the immature GI immune system of
the neonate by triggering the rapid maturation, proliferation, and migration of the cellular components of
the adaptive immune division. The interactions during
infancy are critical for the development of tolerance
and to avoid the risk of allergies to food and other
environmental antigens later in life (Kukkonen et al.
2008), and are a key factor in the risk of atopic disorders (Penders et al., 2007). The interactions between
the bacteria and GI epithelial cells also influence innate
immune functions, such as the secretion of mucous and
antimicrobial peptides. Additional immunologic challenges at weaning caused by the concurrent shifts in
diet and the GI bacteria trigger further changes in GI
defense functions.
Different species of colonizing bacteria have varying
influences on the expression of proinflammatory genes
(Zeuthen et al., 2010), the balance between T helper
1 (antibody-mediated) and T helper 2 (cell-mediated)
immune responses (Ogra, 2010), including immunoglobulin production (Huurre et al., 2008), the patterns of expression for the TLR and nucleotide-binding
oligomerization domain receptors that are critical for
antigen discrimination (Lundin et al., 2008), and the
development of tolerance to endotoxins (Lotz et al.,
2006). These findings have stimulated interest in providing probiotics to infants to modulate the developing
immune responses adventitiously. Conversely, changes
in the GI bacteria caused by administration of antibiot-
1513
ics during suckling increases the densities and responses
of mast cells, apparently predisposing the infant to the
development of allergies (Nutten et al., 2007) and potentially altering GI immune development (Schumann
et al., 2005).
Much less is known about whether and how the assemblages of bacteria influence the postnatal development of other GI functions. Despite the impact of
pathogen-induced diarrheas on neonates, the short- and
long-term responses of the osmoregulatory functions to
the colonizing bacteria have not been described. There
is evidence that enteroendocrine cells can respond directly to resident bacteria by the secretion of hormones
(Palazzo et al., 2007). The hyperactive immune responses of the neonate, if stimulated, can be expected
to influence the other GI functions. For example, inflammatory cytokines secreted in response to pathogenic bacteria are likely to reduce digestive secretions
and nutrient absorption and increase the secretion of
electrolytes and water.
The Developing GIT Influences
the Resident Bacteria
The GIT functions are key determinants of the chemical characteristics of the luminal environment. Digestive secretions present barriers to the introduction of
species, even probiotics, as well as pathogens. Therefore, the changes in the physicochemical environment of
the developing GIT (Sanderson, 1999) and the developing innate and adaptive components of the GI immune
system have the potential to influence the developing
assemblages of bacteria (Salzman et al., 2010). The immature gastric acid production of neonates (Grahnquist
et al., 2000) coincides with greater densities of bacteria
in the stomach until acid production increases. Postnatal changes in patterns of enterocyte glycosylation of
apical membrane glycoproteins (Nanthakumar et al.,
2005) influence bacterial metabolism and may represent a coevolved symbiosis between the host and the
commensal GI bacteria.
NEC: WHEN THE INTERACTIONS
GO AWRY
The interactions among the resident bacteria, the developing GIT, and the diet are of key importance for
the adaptation of neonates to postnatal life (Mshvildadze and Neu, 2010). They are even more important
after preterm birth because of the immature state of GI
development, the intolerance of many preterm infants
to feeding, and the adverse reactions they have to colonizing bacteria. Necrotizing enterocolitis is an inflammatory reaction that is the most common GIT disorder
of neonates, particularly those born premature, with
the incidence varying from 1 to 8% among neonatal
intensive care units (Kosloske, 1994). The NEC disease process is multifactorial, with prematurity, bacte-
1514
Buddington and Sangild
rial colonization of the GIT, and feeding recognized as
the key contributors. Necrotizing enterocolitis has also
been associated with altered GI bacterial assemblages
(Hällström et al., 2004), an immature epithelial barrier and immune defenses, and fetal enterocytes that
are hyperresponsive (Claud, 2009). This has led to the
routine prophylactic administration of antibiotics to
preterm, low-birth-weight infants. Unfortunately, this
may actually predispose preterm infants to NEC (Cotten et al., 2009) by destabilizing the assemblages of GI
bacteria. Additionally, the majority of preterm infants
are delivered by caesarian section, which may compromise the normal postnatal spontaneous activation of
intestinal epithelial cells (Lotz et al., 2006) and the already impaired recognition of lipopolysaccharide characteristic of preterm birth (Wolfs et al., 2010). Another
issue facing preterm infants is the initial dependence
many have on parenteral nutrition, which delays GI
growth and maturation (Hay, 2008). As a consequence,
development of the GI ecosystem is often compromised
among preterm infants (Mshvildadze and Neu, 2010).
The absence of NEC among germ-free animals demonstrates the essential role of the resident bacteria in the
disease process. Moreover, the risk of NEC is increased
when formula is fed, whereas infants fed breast milk are
protected. This has been corroborated in studies with
animal models (newborn mice and rats) that indicate
diet is a determinant of NEC risk via effects on both
microbiota composition and the response pathways of
the host (Sodhi et al., 2008). Because newborn laboratory rodents have limited physiological, anatomical,
and developmental relevance to preterm humans, we
recently developed a preterm pig model of NEC to better understand the diet-microbiota interactions during
early GI development in humans (Sangild et al., 2006).
Our studies confirmed that caesarean section and vaginal birth of preterm pigs (at 92% of gestation) resulted
in widely different patterns of GI bacterial colonization,
yet resulted in similar incidences of NEC (Siggers et
al., 2010). When preterm, caesarean-delivered pigs were
reared in infant incubators and fed an infant formula,
50% or more spontaneously developed NEC symptoms
and the characteristic lesions. The incidence of NEC
was about 5% when preterm pigs were instead fed sow
or cow colostrum (Bjornvad et al., 2008). This parallels
the benefits of providing colostrum to preterm human
infants.
The protection provided by colostrum vs. the increased risk associated with formula indicates dietary
inputs play a central role in NEC. Whether and how
diet influences bacterial colonization of the GIT and
the role in NEC has been investigated in the pig model
in several studies (reviewed by Siggers et al., 2010).
Overall, there were few diet-dependent differences in
gut colonization, except that certain pathogenic species
(e.g., Clostridium perfringens) were consistently associated with intestinal lesions associated with NEC. Moreover, the patterns of bacterial colonization correlated
more closely with the degree of intestinal lesions and
gestational age at birth (maturity of the epithelium)
than with specific diets (colostrum vs. formula).
Reviews of clinical trials with human preterm infants
that evaluated the efficacy of probiotics as a prophylactic for NEC suggest the NEC risk is reduced (Alfaleh et
al., 2010). However, the use of different strains of probiotics and administration regimens confounds interpretations. The administration of probiotics to preterm
pigs did not induce notable changes in the GI bacteria,
nor did it consistently reduce the incidence of NEC
(Siggers et al., 2010). Although the potential benefits
of including prebiotics in formula fed to preterm infants have not been adequately investigated and remain
uncertain (Sherman et al., 2009), studies with animal
models suggest adding prebiotics may reduce the risk
of NEC (Butel et al., 2002). However, the addition of
prebiotic compounds to the formula fed to preterm
pigs failed to improve NEC resistance relative to the
formula alone (Møller et al., 2011). Collectively, these
studies lead to the conclusion that the presence of bacteria is essential for intestinal inflammatory reactions
in newborns. Furthermore, the state of the mucosa is
an important determinant of whether the contact with
the colonizing bacteria results in severe inflammation
and NEC. Controlling the process of bacterial colonization in preterm newborns through diet is difficult. Even
so, the species composition of the GI bacteria appears
to be less important for NEC risk than the digestive
capacity and immune responses of the immature GIT.
The detrimental effects of feeding formula may be
related to the absence of immunomodulatory factors
and nutrients that are present in breast milk and the
responses of the preterm GI ecosystem to novel, nonmilk ingredients that are present in formula (e.g., corn
syrup solids). Preterm pigs fed formula prepared with
corn syrup solids had a greater incidence of NEC compared with when lactose was the predominant source of
carbohydrate (Buddington et al., 2008). The beneficial
effects of the lactose-based formula were more closely
related to improved functions of the intestinal mucosa
rather than to improved gut microbiota (Thymann et
al., 2009).
Even though bacteria colonize the GIT immediately after delivery and are present during the period of
TPN, the onset of NEC-related inflammatory reactions
in the majority of preterm pigs occurred within hours
after the onset of enteral feeding with formula (Oste et
al., 2010). The importance of diet is again evident from
the overfed, preterm rat pup as a model for NEC (Okada et al., 2010). The importance of diet for inducing
NEC in animal models is similar to the development of
NEC in preterm human infants after the beginning of
enteral feeding. These findings highlight how adverse
interactions between the colonizing bacteria and diet in
conjunction with immaturity of the GIT are central to
the NEC disease process. Despite the role of the GI microbiome in contributing to disease in infants, it is very
Gastrointestinal development, bacteria, and diet
likely that the metabolic functions of the GI bacteria
and the responses to enteral nutrients are more important in triggering NEC. Rectal introduction of SCFA
induces mucosal damage (Lin et al., 2005), and introducing a combination of lactose and lactose-fermenting bacteria that generate increased concentrations of
SCFA (Waligora-Dupriet et al., 2009) induces mucosal
damage and NEC-like characteristics in animal models.
Although the etiology of NEC remains uncertain, the
interactions between the GI bacteria and diet are key
determinants of the sensitivity of the immature GIT to
stimuli that elicit detrimental inflammatory reactions.
PERSPECTIVES FOR DIETARY
MANAGEMENT OF THE DEVELOPING
GIT ECOSYSTEM
The type (breast milk or formulas with novel ingredients) and amount (full, minimal, or absence) of enteral
diet in conjunction with bacterial colonization play significant roles in mediating postnatal development of
the GI structure, functions, and resident microbiota.
Present infant formulas fail to replicate the important
protective effects of breast milk, which can be attributed to the lack of bioactive constituents that modulate
GI gene expression, modulate the growth and maturation of GI functions, possess antimicrobial functions
and provide the neonate with passive immunity, and
others with prebiotic properties that contribute to the
selection and dominance of the commensal microbiota.
In addition to providing adequate energy and nutrients, the optimal diet for the neonate, term or preterm,
needs to include components that reduce or prevent
the harmful actions of the resident GI microbiota on
the neonatal mucosa. There is understandable interest
in increasing the proportion of beneficial bacteria in
the GIT of infants to modulate enteric immune functions and thereby improve resistance to GIT pathogens
and other health challenges (Dogi et al., 2008). Three
principal approaches have been used to date. Although
antibiotics remain a mainstay for neonatal care, there is
a growing appreciation of and concern about the longterm consequences associated with the disturbances
they cause in the developing GI ecosystem (Cotten et
al., 2009; Jernberg et al., 2010). Probiotics are of widespread interest, and there are numerous reports of efficacy. However, the benefits are generally transient and
do not persist after the probiotic is no longer administered. It has proven possible to provide probiotic bacteria during pregnancy to facilitate colonization of infants
born vaginally (Buddington et al., 2010). However, the
numerous strains available, the varying responses that
can be elicited, and the likely individual-specific responses complicate the selection of strains that provide
benefits. The emergence of prebiotics as ingredients in
infant formulas mimics the presence of oligosaccharides
in breast milk and has shown promise for encouraging the growth of beneficial bacteria already resident in
1515
and presumably adapted to the host GIT (Veereman,
2007), thereby providing health benefits (Arslanoglu et
al., 2008).
Animal models will remain important for investigating the development of the GI ecosystem of human infants, agricultural species, and companion animals and
for evaluating the influences of bacteria and diet. The
variation in the GI microbiota among species, individuals, ages, and health states will complicate extrapolating results from one species to another. It is not surprising that responses to probiotics and prebiotics vary
among species and even individuals (Sullivan and Nord,
2005). A better understanding of how diet influences
host-microbiome interactions during the neonatal period will greatly enhance efforts to improve management of the GIT ecosystem, and thereby the health and
nutrition of newborns.
LITERATURE CITED
Alfaleh, K., J. Anabrees, and D. Bassler. 2010. Probiotics reduce
the risk of necrotizing enterocolitis in preterm infants: A metaanalysis. Neonatology 97:93–99.
Allen, C. A., and A. G. Torres. 2008. Host-microbe communication
within the GIT. Adv. Exp. Med. Biol. 635:93–101.
Alumets, J., R. Håkanson, and F. Sundler. 1983. Ontogeny of endocrine cells in porcine gut and pancreas. An immunocytochemical study. Gastroenterology 85:1359–1372.
Alverdy, J., O. Zaborina, and L. Wu. 2005. The impact of stress and
nutrition on bacterial-host interactions at the intestinal epithelial surface. Curr. Opin. Clin. Nutr. Metab. Care 8:205–209.
Amarri, S., F. Benatti, M. L. Callegari, Y. Shahkhalili, F. Chauffard, F. Rochat, K. J. Acheson, C. Hager, J. Benyacoub, E.
Galli, A. Rebecchi, and L. Morelli. 2006. Changes of gut microbiota and immune markers during the complementary feeding
period in healthy breast-fed infants. J. Pediatr. Gastroenterol.
Nutr. 42:488–495.
Are, A., L. Aronsson, S. Wang, G. Greicius, Y. K. Lee, J. A. Gustafsson, S. Pettersson, and V. Arulampalam. 2008. Enterococcus
faecalis from newborn babies regulate endogenous PPARγ activity and IL-10 levels in colonic epithelial cells. Proc. Natl.
Acad. Sci. USA 105:1943–1948.
Arslanoglu, S., G. E. Moro, J. Schmitt, L. Tandoi, S. Rizzardi, and
G. Boehm. 2008. Early dietary intervention with a mixture of
prebiotic oligosaccharides reduces the incidence of allergic manifestations and infections during the first two years of life. J.
Nutr. 138:1091–1095.
Bailey, M., and K. Haverson. 2006. The postnatal development of
the mucosal immune system and mucosal tolerance in domestic
animals. Vet. Res. 37:443–453.
Bartholome, A. L., D. M. Albin, D. H. Baker, J. J. Holst, and K. A.
Tappenden. 2004. Supplementation of total parenteral nutrition
with butyrate acutely increases structural aspects of intestinal
adaptation after an 80% jejunoileal resection in neonatal piglets. J. Parenter. Enteral Nutr. 28:210–222.
Basson, M. D., Y. W. Liu, A. M. Hanly, N. J. Emenaker, S. G. Shenoy, and B. E. Gould Rothberg. 2000. Identification and comparative analysis of human colonocyte short-chain fatty acid
response genes. J. Gastrointest. Surg. 4:501–512.
Bjornvad, C. R., T. Thymann, N. E. Deutz, D. G. Burrin, S. K.
Jensen, B. B. Jensen, L. Molbak, M. Boye, L. I. Larsson, M.
Schmidt, K. F. Michaelsen, and P. T. Sangild. 2008. Enteral
feeding induces diet-dependent mucosal dysfunction, bacterial
proliferation, and necrotizing enterocolitis in preterm pigs on
parenteral nutrition. Am. J. Physiol. Gastrointest. Liver Physiol. 295:G1092–G1103.
1516
Buddington and Sangild
Bombell, S., and W. McGuire. 2009. Early trophic feeding for
very low birth weight infants. Cochrane Database Syst. Rev.
8:CD000504.
Bourassa, J., J. Lainé, M. L. Kruse, M. C. Gagnon, E. Calvo, and
J. Morisset. 1999. Ontogeny and species differences in the pancreatic expression and localization of the CCK(A) receptors.
Biochem. Biophys. Res. Commun. 260:820–828.
Bry, L., P. G. Falk, T. Midtvedt, and J. L. Gordon. 1996. A model of
host-microbial interactions in an open mammalian ecosystem.
Science 273:1380–1383.
Buddington, R. K. 1994. Nutrition and ontogenetic development of
the intestine. Can. J. Physiol. Pharmacol. 72:251–259.
Buddington, R. K. 2009. Using probiotics and prebiotics to manage
the gastrointestinal tract ecosystem. Pages 1–31 in Prebiotics
and Probiotics Science and Technology. D. Charalampopoulos
and R. A. Rastall, ed. Springer Science Publishing, New York,
NY.
Buddington, R. K., S. B. Bering, T. Thymann, and P. T. Sangild.
2008. Aldohexose malabsorption in preterm pigs is directly related to the severity of necrotizing enterocolitis. Pediatr. Res.
63:382–387.
Buddington, R. K., and E. Weiher. 1999. The application of ecological principles and fermentable fibers to manage the gastrointestinal tract ecosystem. J. Nutr. 129(Suppl.):1446S–1450S.
Buddington, R. K., C. H. Williams, B. M. Kostek, K. K. Buddington, and M. J. Kullen. 2010. Maternal-to-infant transmission of
probiotics: Concept validation in mice, rats, and pigs. Neonatology 97:250–256.
Burrin, D., X. Guan, B. Stoll, Y. M. Petersen, and P. T. Sangild.
2003. Glucagon-like peptide 2: A key link between nutrition and
intestinal adaptation in neonates? J. Nutr. 133:3712–3716.
Butel, M. J., A. J. Waligora-Dupriet, and O. Szylit. 2002. Oligofructose and experimental model of neonatal necrotising enterocolitis. Br. J. Nutr. 87(Suppl. 2):S213–S219.
Chailler, P., and D. Ménard. 1999. Ontogeny of EGF receptors in
the human gut. Front. Biosci. 4:D87–D101.
Claud, E. C. 2009. Neonatal necrotizing enterocolitis—Inflammation
and intestinal immaturity. Antiinflamm. Antiallergy Agents
Med. Chem. 8:248–259.
Conroy, M. E., H. N. Shi, and W. A. Walker. 2009. The long-term
health effects of neonatal microbial flora. Curr. Opin. Allergy
Clin. Immunol. 9:197–201.
Coppa, G. V., L. Zampini, T. Galeazzi, and O. Gabrielli. 2006. Prebiotics in human milk: A review. Dig. Liver Dis. 38(Suppl.
2):S291–S294.
Cotten, C. M., S. Taylor, B. Stoll, R. N. Goldberg, N. I. Hansen,
P. J. Sánchez, N. Ambalavanan, and D. K. Benjamin Jr., and
NICHD Neonatal Research Network. 2009. Prolonged duration
of initial empirical antibiotic treatment is associated with increased rates of necrotizing enterocolitis and death for extremely low birth weight infants. Pediatrics 123:58–66.
Dicksved, J., J. Halfvarson, M. Rosenquist, G. Järnerot, C. Tysk, J.
Apajalahti, L. Engstrand, and J. K. Jansson. 2008. Molecular
analysis of the gut microbiota of identical twins with Crohn’s
disease. ISME J. 2:716–727.
Dimmitt, R. A., E. M. Staley, G. Chuang, S. M. Tanner, T. D. Soltau, and R. G. Lorenz. 2010. Role of postnatal acquisition of
the intestinal microbiome in the early development of immune
function. J. Pediatr. Gastroenterol. Nutr. 51:262–273.
Dogi, C. A., C. M. Galdeano, and G. Perdigón. 2008. Gut immune
stimulation by non pathogenic Gram(+) and Gram(−) bacteria. Comparison with a probiotic strain. Cytokine 41:223–
231.
Drozdowski, L. A., T. Clandinin, and A. B. Thomson. 2010. Ontogeny, growth and development of the small intestine: Understanding pediatric gastroenterology. World J. Gastroenterol.
16:787–799.
Dunne, C. 2001. Adaptation of bacteria to the intestinal niche: Probiotics and gut disorder. Inflamm. Bowel Dis. 7:136–145.
Eckmann, L. 2006. Innate immunity. Pages 1033–1066 in Physiology
of the Gastrointestinal Tract. 4th ed. L. R. Johnson, K. E. Bar-
rett, F. K. Ghishan, J. L. Merchant, H. M. Said, and J. Wood,
ed. Elsevier, Amsterdam, the Netherlands.
Eiwegger, T., B. Stahl, P. Haidl, J. Schmitt, G. Boehm, E. Dehlink,
R. Urbanek, and Z. Szépfalusi. 2010. Prebiotic oligosaccharides: In vitro evidence for gastrointestinal epithelial transfer
and immunomodulatory properties. Pediatr. Allergy Immunol.
21:1179–1188.
Flint, H. J., S. H. Duncan, K. P. Scott, and P. Louis. 2007. Interactions and competition within the microbial community of the
human colon: Links between diet and health. Environ. Microbiol. 9:1101–1111.
Freitas, M., L. G. Axelsson, C. Cayuela, T. Midtvedt, and G. Trugnan. 2002. Microbial-host interactions specifically control the
glycosylation pattern in intestinal mouse mucosa. Histochem.
Cell Biol. 118:149–161.
González, R., E. S. Klaassens, E. Malinen, W. M. de Vos, and E. E.
Vaughan. 2008. Differential transcriptional response of Bifidobacterium longum to human milk, formula milk, and galactooligosaccharide. Appl. Environ. Microbiol. 74:4686–4694.
Grahnquist, L., T. Ruuska, and Y. Finkel. 2000. Early development
of human gastric H,K-adenosine triphosphatase. J. Pediatr.
Gastroenterol. Nutr. 30:533–537.
Grönlund, M. M., S. Salminen, H. Mykkänen, P. Kero, and O. P.
Lehtonen. 1999. Development of intestinal bacterial enzymes in
infants—Relationship to mode of delivery and type of feeding.
APMIS 107:655–660.
Hällström, M., E. Eerola, R. Vuento, M. Janas, and O. Tammela.
2004. Effects of mode of delivery and necrotising enterocolitis
on the intestinal microflora in preterm infants. Eur. J. Clin.
Microbiol. Infect. Dis. 23:463–470.
Hanson, L. A. 2007. Feeding and infant development breast-feeding
and immune function. Proc. Nutr. Soc. 66:384–396.
Hay, W. W. 2008. Strategies for feeding the preterm infant. Neonatology 94:245–254.
Heuvelin, E., C. Lebreton, M. Bichara, N. Cerf-Bensussan, and
M. Heyman. 2010. A Bifidobacterium probiotic strain and its
soluble factors alleviate chloride secretion by human intestinal
epithelial cells. J. Nutr. 140:7–11.
Heuvelin, E., C. Lebreton, C. Grangette, B. Pot, N. Cerf-Bensussan,
and M. Heyman. 2009. Mechanisms involved in alleviation of
intestinal inflammation by Bifidobacterium breve soluble factors. PLoS ONE 4:e5184.
Hrncir, T., R. Stepankova, H. Kozakova, T. Hudcovic, and H.
Tlaskalova-Hogenova. 2008. Gut microbiota and lipopolysaccharide content of the diet influence development of regulatory
T cells: Studies in germ-free mice. BMC Immunol. 9:65.
Huurre, A., M. Kalliomäki, S. Rautava, M. Rinne, S. Salminen, and
E. Isolauri. 2008. Mode of delivery—Effects on gut microbiota
and humoral immunity. Neonatology 93:236–240.
Jenness, R., and R. E. Sloan. 1970. The composition of milks of various species: A review. Dairy Sci. 32:599–612.
Jernberg, C., S. Löfmark, C. Edlund, and J. K. Jansson. 2010. Longterm impacts of antibiotic exposure on the human intestinal
microbiota. Microbiology 156:3216–3223.
Kelly, D., T. King, and R. Aminov. 2007. Importance of microbial
colonization of the gut in early life to the development of immunity. Mutat. Res. 622:58–69.
Kien, C. L., R. E. McClead, and L. Cordero Jr. 1998. Effects of
lactose intake on lactose digestion and colonic fermentation in
preterm infants. J. Pediatr. 133:401–405.
Kim, Y., S. H. Kim, K. Y. Whang, Y. J. Kim, and S. Oh. 2008. Inhibition of Escherichia coli O157:H7 attachment by interactions
between lactic acid bacteria and intestinal epithelial cells. J.
Microbiol. Biotechnol. 18:1278–1285.
Kleessen, B., and M. Blaut. 2005. Modulation of gut mucosal biofilms. Br. J. Nutr. 93(Suppl. 1):S35–S40.
Koenig, J. E., A. Spor, N. Scalfone, A. D. Fricker, J. Stombaugh,
R. Knight, L. T. Angenent, and R. E. Ley. 2010. Microbes and
Health Sackler Colloquium: Succession of microbial consortia
in the developing infant gut microbiome. Proc. Natl. Acad. Sci.
USA doi:10.1073/pnas.1000081107.
Gastrointestinal development, bacteria, and diet
Kosloske, A. M. 1994. Epidemiology of necrotizing enterocolitis.
Acta Paediatr. 83:(Suppl. s396):2–7. 10.1111/j.1651-2227.1994.
tb13232.x.
Kukkonen, K., E. Savilahti, T. Haahtela, K. Juntunen-Backman, R.
Korpela, T. Poussa, T. Tuure, and M. Kuitunen. 2008. Longterm safety and impact on infection rates of postnatal probiotic
and prebiotic (synbiotic) treatment: Randomized, double-blind,
placebo-controlled trial. Pediatrics 122:8–12.
Lacroix-Lamandé, S., N. Rochereau, R. Mancassola, M. Barrier, A.
Clauzon, and F. Laurent. 2009. Neonate intestinal immune response to CpG oligodeoxynucleotide stimulation. PLoS ONE
4:e8291.
Lallès, J. P., P. Bosi, H. Smidt, and C. R. Stokes. 2007. Nutritional
management of gut health in pigs around weaning. Proc. Nutr.
Soc. 66:260–268.
Lebenthal, A., and E. Lebenthal. 1999. The ontogeny of the small intestinal epithelium. J. Parenter. Enteral. Nutr. 23(Suppl.):S3–
S6.
Lesniewska, V., I. Rowland, H. N. Laerke, G. Grant, and P. J.
Naughton. 2006. Relationship between dietary-induced changes
in intestinal commensal microflora and duodenojejunal myoelectric activity monitored by radiotelemetry in the rat in vivo.
Exp. Physiol. 91:229–237.
Ley, R. E., M. Hamady, C. Lozupone, P. J. Turnbaugh, R. R. Ramey,
J. S. Bircher, M. L. Schlegel, T. A. Tucker, M. D. Schrenzel,
R. Knight, and J. I. Gordon. 2008. Evolution of mammals and
their gut microbes. Science 320:1647–1651.
Lin, J., L. Peng, S. Itzkowitz, I. R. Holzman, and M. W. Babyatsky.
2005. Short-chain fatty acid induces intestinal mucosal injury in
newborn rats and down-regulates intestinal trefoil factor gene
expression in vivo and in vitro. J. Pediatr. Gastroenterol. Nutr.
41:607–611.
Lotz, M., D. Gütle, S. Walther, S. Ménard, C. Bogdan, and M. W.
Hornef. 2006. Postnatal acquisition of endotoxin tolerance in
intestinal epithelial cells. J. Exp. Med. 203:973–984.
Lundin, A., C. M. Bok, L. Aronsson, B. Björkholm, J. A. Gustafsson, S. Pott, V. Arulampalam, J. Rafter, and S. Pettersson.
2008. Gut flora, Toll-like receptors and nuclear receptors: A
tripartite communication that tunes innate immunity in large
intestine. Cell. Microbiol. 10:1093–1103.
Macfarlane, S., and G. T. Macfarlane. 2003. Regulation of shortchain fatty acid production. Proc. Nutr. Soc. 62:67–72.
Mackie, R. I., A. Sghir, and H. R. Gaskins. 1999. Developmental
microbial ecology of the neonatal gastrointestinal tract. Am. J.
Clin. Nutr. 69:1035S–1045S.
Magalhaes, J. G., I. Tattoli, and S. E. Girardin. 2007. The intestinal epithelial barrier: How to distinguish between the microbial
flora and pathogens. Semin. Immunol. 19:106–115.
Mahowald, M. A., F. E. Rey, H. Seedorf, P. J. Turnbaugh, R. S. Fulton, A. Wollam, N. Shah, C. Wang, V. Magrini, R. K. Wilson,
B. L. Cantarel, P. M. Coutinho, B. Henrissat, L. W. Crock, A.
Russell, N. C. Verberkmoes, R. L. Hettich, and J. I. Gordon.
2009. Characterizing a model human gut microbiota composed
of members of its two dominant bacterial phyla. Proc. Natl.
Acad. Sci. USA 106:5859–5864.
Mäkivuokko, H. A., M. T. Saarinen, A. C. Ouwehand, and N. E.
Rautonen. 2006. Effects of lactose on colon microbial community structure and function in a four-stage semi-continuous culture system. Biosci. Biotechnol. Biochem. 70:2056–2063.
Mazmanian, S. K., C. H. Liu, A. O. Tzianabos, and D. L. Kasper.
2005. An immunomodulatory molecule of symbiotic bacteria
directs maturation of the host immune system. Cell 122:107–
118.
Møller, H. K., T. Thymann, L. N. Fink, H. Frokiaer, A. S. Kvistgaard, and P. T. Sangild. 2011. Bovine colostrum is superior
to enriched formulas in stimulating intestinal function and necrotising enterocolitis resistance in preterm pigs. Br. J. Nutr.
105:44–53.
Mshvildadze, M., and J. Neu. 2010. The infant intestinal microbiome: Friend or foe? Early Hum. Dev. 86(Suppl. 1):67–71.
1517
Mulder, I. E., B. Schmidt, C. R. Stokes, M. Lewis, M. Bailey, R. I.
Aminov, J. I. Prosser, B. P. Gill, J. R. Pluske, C. D. Mayer, C.
C. Musk, and D. Kelly. 2009. Environmentally-acquired bacteria influence microbial diversity and natural innate immune
responses at gut surfaces. BMC Biol. 7:79.
Murray, C. B., S. Chu, and P. L. Zeitlin. 1996. Gestational and
tissue-specific regulation of C1C-2 chloride channel expression.
Am. J. Physiol. 271:L829–L837.
Myllynen, P., E. Immonen, M. Kummu, and K. Vähäkangas. 2009.
Developmental expression of drug metabolizing enzymes and
transporter proteins in human placenta and fetal tissues. Expert Opin. Drug Metab. Toxicol. 5:1483–1499.
Nanthakumar, N. N., D. Dai, D. Meng, N. Chaudry, D. S. Newburg,
and W. A. Walker. 2005. Regulation of intestinal ontogeny:
Effect of glucocorticoids and luminal microbes on galactosyltransferase and trehalase induction in mice. Glycobiology
15:221–232.
Nelson, K. E., S. H. Zinder, I. Hance, P. Burr, D. Odongo, D. Wasawo, A. Odenyo, and R. Bishop. 2003. Phylogenetic analysis of
the microbial populations in the wild herbivore gastrointestinal
tract: Insights into an unexplored niche. Environ. Microbiol.
5:1212–1220.
Newburg, D. S. 2009. Neonatal protection by an innate immune system of human milk consisting of oligosaccharides and glycans.
J. Anim. Sci. 87(Suppl.):26–34.
Newburg, D. S., and W. A. Walker. 2007. Protection of the neonate
by the innate immune system of developing gut and of human
milk. Pediatr. Res. 61:2–8.
Nutten, S., A. Schumann, D. Donnicola, A. Mercenier, S. Rami, and
C. L. Garcia-Rodenas. 2007. Antibiotic administration early in
life impairs specific humoral responses to an oral antigen and
increases intestinal mast cell numbers and mediator concentrations. Clin. Vaccine Immunol. 14:190–197.
O’Keefe, S. J. 2008. Nutrition and colonic health: The critical role of
the microbiota. Curr. Opin. Gastroenterol. 24:51–58.
Ogra, P. L. 2010. Ageing and its possible impact on mucosal immune
responses. Ageing Res. Rev. 9:101–106.
Okada, K., T. Fujii, Y. Ohtsuka, Y. Yamakawa, H. Izumi, Y. Yamashiro, and T. Shimizu. 2010. Overfeeding can cause NEC-like
enterocolitis in premature rat pups. Neonatology 97:218–224.
Oste, M., E. Van Haver, T. Thymann, P. T. Sangild, A. Weyns, and
C. J. Van Ginneken. 2010. Formula induces intestinal apoptosis
in preterm pigs within a few hours of feeding. J. Parenter. Enteral. Nutr. 34:271–279.
Palazzo, M., A. Balsari, A. Rossini, S. Selleri, C. Calcaterra, S. Gariboldi, L. Zanobbio, F. Arnaboldi, Y. F. Shirai, G. Serrao, and
C. Rumio. 2007. Activation of enteroendocrine cells via TLRs
induces hormone, chemokine, and defensin secretion. J. Immunol. 178:4296–4303.
Penders, J., E. E. Stobberingh, P. A. van den Brandt, and C. Thijs.
2007. The role of the intestinal microbiota in the development
of atopic disorders. Allergy 62:1223–1236.
Penders, J., C. Thijs, C. Vink, F. F. Stelma, B. Snijders, I. Kummeling, P. A. van den Brandt, and E. E. Stobberingh. 2006. Factors
influencing the composition of the intestinal microbiota in early
infancy. Pediatrics 118:511–521.
Poroyko, V., J. R. White, M. Wang, S. Donovan, J. Alverdy, D. C.
Liu, and M. J. Morowitz. 2010. Gut microbial gene expression
in mother-fed and formula-fed piglets. PLoS ONE 5:e12459.
Pritchard, J. A. 1966. Fetal swallowing and amniotic fluid volume.
Obstet. Gynecol. 28:606–610.
Rechkemmer, G., K. Rönnau, and W. von Engelhardt. 1988. Fermentation of polysaccharides and absorption of short chain fatty acids in the mammalian hindgut. Comp. Biochem. Physiol.
A 90:563–568.
Richardson, W. M., C. P. Sodhi, A. Russo, R. H. Siggers, A. Afrazi,
S. C. Gribar, M. D. Neal, S. Dai, T. Prindle, M. Branca, C.
Ma, J. Ozolek, and D. J. Hackam. 2010. Nucleotide-binding
oligomerization domain-2 inhibits toll-like receptor-4 signaling
in the intestinal epithelium. Gastroenterology 139:904–917.
1518
Buddington and Sangild
Rodriguez, N. A., P. P. Meier, M. W. Groer, J. M. Zeller, J. L.
Engstrom, and L. Fogg. 2010. A pilot study to determine the
safety and feasibility of oropharyngeal administration of own
mother’s colostrum to extremely low-birth-weight infants. Adv.
Neonatal Care 10:206–212.
Rumbo, M., and E. J. Schiffrin. 2005. Ontogeny of intestinal epithelium immune functions: Developmental and environmental
regulation. Cell. Mol. Life Sci. 62:1288–1296.
Salminen, S., G. R. Gibson, A. L. McCartney, and E. Isolauri. 2004.
Influence of mode of delivery on gut microbiota composition in
seven year old children. Gut 53:1388–1389.
Salzman, N. H., K. Hung, D. Haribhai, H. Chu, J. Karlsson-Sjöberg,
E. Amir, P. Teggatz, M. Barman, M. Hayward, D. Eastwood,
M. Stoel, Y. Zhou, E. Sodergren, G. M. Weinstock, C. L. Bevins, C. B. Williams, and N. A. Bos. 2010. Enteric defensins
are essential regulators of intestinal microbial ecology. Nat.
Immunol. 11:76–83.
Sanderson, I. R. 1999. The physicochemical environment of the neonatal intestine. Am. J. Clin. Nutr. 69:1028S–1034S.
Sanderson, I. R. 2004. Short chain fatty acid regulation of signaling genes expressed by the intestinal epithelium. J. Nutr.
134:2450S–2454S.
Sangild, P. T., R. H. Siggers, M. Schmidt, J. Elnif, C. R. Bjornvad,
T. Thymann, M. L. Grondahl, A. K. Hansen, S. K. Jensen, M.
Boye, L. Moelbak, R. K. Buddington, B. R. Westrom, J. J.
Holst, and D. G. Burrin. 2006. Diet- and colonization-dependent intestinal dysfunction predisposes to necrotizing enterocolitis in preterm pigs. Gastroenterology 130:1776–1792.
Schell, M. A., M. Karmirantzou, B. Snel, D. Vilanova, B. Berger,
G. Pessi, M. C. Zwahlen, F. Desiere, P. Bork, M. Delley, R.
D. Pridmore, and F. Arigoni. 2002. The genome sequence of
Bifidobacterium longum reflects its adaptation to the human
gastrointestinal tract. Proc. Natl. Acad. Sci. USA 99:14422–
14427.
Schrenzel, M. D., C. L. Witte, J. Bahl, T. A. Tucker, N. Fabian,
H. Greger, C. Hollis, G. Hsia, E. Siltamaki, and B. A. Rideout. 2010. Genetic characterization and epidemiology of helicobacters in non-domestic animals. Helicobacter 15:126–142.
Schumann, A., S. Nutten, D. Donnicola, E. M. Comelli, R. Mansourian, C. Cherbut, I. Corthesy-Theulaz, and C. Garcia-Rodenas.
2005. Neonatal antibiotic treatment alters gastrointestinal tract
developmental gene expression and intestinal barrier transcriptome. Physiol. Genomics 23:235–245.
Selleri, S., M. Palazzo, S. Deola, E. Wang, A. Balsari, F. M. Marincola, and C. Rumio. 2008. Induction of pro-inflammatory programs in enteroendocrine cells by the Toll-like receptor agonists
flagellin and bacterial LPS. Int. Immunol. 20:961–970.
Sharma, R., C. Young, and J. Neu. 2010. Molecular modulation
of intestinal epithelial barrier: Contribution of microbiota. J.
Biomed. Biotechnol. 2010:305879.
Sherman, P. M., M. Cabana, G. R. Gibson, B. V. Koletzko, J. Neu,
G. Veereman-Wauters, E. E. Ziegler, and W. A. Walker. 2009.
Potential roles and clinical utility of prebiotics in newborns, infants, and children: Proceedings from a global prebiotic summit
meeting. J. Pediatr. 155:S61–S70.
Shibolet, O., and D. K. Podolsky. 2007. TLRs in the gut. IV. Negative regulation of Toll-like receptors and intestinal homeostasis:
Addition by subtraction. Am. J. Physiol. Gastrointest. Liver
Physiol. 292:G1469–G1473.
Shreiner, A., G. B. Huffnagle, and M. C. Noverr. 2008. The “Microflora Hypothesis” of allergic disease. Adv. Exp. Med. Biol.
635:113–134.
Siggers, R. H., J. Siggers, T. Thymann, M. Boye, and P. T. Sangild.
2010. Nutritional modulation of the gut microbiota and immune
system in preterm neonates susceptible to necrotizing enterocolitis. J. Nutr. Biochem. doi:10.1016/j.jnutbio.2010.08.002.
Singhal, A., G. Macfarlane, S. Macfarlane, J. Lanigan, K. Kennedy,
A. Elias-Jones, T. Stephenson, P. Dudek, and A. Lucas. 2008.
Dietary nucleotides and fecal microbiota in formula-fed infants:
A randomized controlled trial. Am. J. Clin. Nutr. 87:1785–
1792.
Slack, E., S. Hapfelmeier, B. Stecher, Y. Velykoredko, M. Stoel, M.
A. Lawson, M. B. Geuking, B. Beutler, T. F. Tedder, W. D.
Hardt, P. Bercik, E. F. Verdu, K. D. McCoy, and A. J. Macpherson. 2009. Innate and adaptive immunity cooperate flexibly to
maintain host-microbiota mutualism. Science 325:617–620.
Sodhi, C., W. Richardson, S. Gribar, and D. J. Hackam. 2008. The
development of animal models for the study of necrotizing enterocolitis. Dis. Model. Mech. 1:94–98.
Sperandio, V., A. G. Torres, B. Jarvis, J. P. Nataro, and J. B.
Kaper. 2003. Bacteria-host communication: The language of
hormones. Proc. Natl. Acad. Sci. USA 100:8951–8956.
Stevens, C. E., and I. D. Hume. 1995.Comparative Physiology of the
Vertebrate Digestive System. 2nd ed. Cambridge Univ. Press,
New York, NY.
Stewart, J. A., V. S. Chadwick, and A. Murray. 2005. Investigations
into the influence of host genetics on the predominant eubacteria in the faecal microflora of children. J. Med. Microbiol.
54:1239–1242.
Sullivan, A., and C. E. Nord. 2005. Probiotics and gastrointestinal
diseases. J. Intern. Med. 257:78–92.
Suzuki, Y. A., V. Lopez, and B. Lönnerdal. 2005. Mammalian lactoferrin receptors: Structure and function. Cell. Mol. Life Sci.
62:2560–2575.
Tanaka, S., T. Kobayashi, P. Songjinda, A. Tateyama, M. Tsubouchi, C. Kiyohara, T. Shirakawa, K. Sonomoto, and J. Nakayama. 2009. Influence of antibiotic exposure in the early
postnatal period on the development of intestinal microbiota.
FEMS Immunol. Med. Microbiol. 56:80–87.
Tannock, G. W., R. Fuller, and K. Pedersen. 1990. Lactobacillus
succession in the piglet digestive tract demonstrated by plasmid
profiling. Appl. Environ. Microbiol. 56:1310–1316.
Thymann, T., H. K. Møller, B. Stoll, A. C. Støy, R. K. Buddington, S. B. Bering, B. B. Jensen, O. O. Olutoye, R. H. Siggers,
L. Mølbak, P. T. Sangild, and D. G. Burrin. 2009. Carbohydrate maldigestion induces necrotizing enterocolitis in preterm
pigs. Am. J. Physiol. Gastrointest. Liver Physiol. 297:G1115–
G1125.
Van de Perre, P. 2003. Transfer of antibody via mother’s milk. Vaccine 21:3374–3376.
Van Haver, E. R., P. T. Sangild, M. Oste, J. L. Siggers, A. L. Weyns,
and C. J. Van Ginneken. 2009. Diet-dependent mucosal colonization and interleukin-1β responses in preterm pigs susceptible
to necrotizing enterocolitis. J. Pediatr. Gastroenterol. Nutr.
49:90–98.
Vanhoutvin, S. A., F. J. Troost, H. M. Hamer, P. J. Lindsey, G. H.
Koek, D. M. Jonkers, A. Kodde, K. Venema, and R. J. Brummer. 2009. Butyrate-induced transcriptional changes in human
colonic mucosa. PLoS ONE 4:e6759.
Veereman, G. 2007. Pediatric applications of inulin and oligofructose. J. Nutr. 137(Suppl.):2585S–2589S.
Venkatesh, M. P., and S. A. Abrams. 2010. Oral lactoferrin for the
prevention of sepsis and necrotizing enterocolitis in preterm infants. Cochrane Database Syst. Rev. 12:CD007137.
Voltaire. 1929. Candide. Random House Inc., New York, NY.
Waligora-Dupriet, A. J., A. Dugay, N. Auzeil, I. Nicolis, S. Rabot,
M. R. Huerre, and M. J. Butel. 2009. Short-chain fatty acids
and polyamines in the pathogenesis of necrotizing enterocolitis:
Kinetics aspects in gnotobiotic quails. Anaerobe 15:138–144.
Watanabe, S., K. Matsushita, J. B. Stokes, and P. B. McCray Jr.
1998. Developmental regulation of epithelial sodium channel
subunit mRNA expression in rat colon and lung. Am. J. Physiol. 275:G1227–G1235.
Williams, A. M., C. S. Probert, R. Stepankova, H. Tlaskalova-Hogenova, A. Phillips, and P. W. Bland. 2006. Effects of microflora
on the neonatal development of gut mucosal T cells and myeloid cells in the mouse. Immunology 119:470–478.
Winkler, P., D. Ghadimi, J. Schrezenmeir, and J. P. Kraehenbuhl.
2007. Molecular and cellular basis of microflora-host interactions. J. Nutr. 137(Suppl. 2):756S–772S.
Wolfs, T. G., J. P. Derikx, C. M. Hodin, J. Vanderlocht, A. Driessen,
A. P. de Bruïne, C. L. Bevins, F. Lasitschka, N. Gassler, W.
Gastrointestinal development, bacteria, and diet
G. van Gemert, and W. A. Buurman. 2010. Localization of the
lipopolysaccharide recognition complex in the human healthy
and inflamed premature and adult gut. Inflamm. Bowel Dis.
16:68–75.
Wong, J. M., R. de Souza, C. W. Kendall, A. Emam, and D. J. Jenkins. 2006. Colonic health: Fermentation and short chain fatty
acids. J. Clin. Gastroenterol. 40:235–243.
Yu, V. Y. 2002. Scientific rationale and benefits of nucleotide supplementation of infant formula. J. Paediatr. Child Health 38:543–
549.
Zeuthen, L. H., L. N. Fink, S. B. Metzdorff, M. B. Kristensen, T.
R. Licht, C. Nellemann, and H. Frøkiaer. 2010. Lactobacillus
1519
acidophilus induces a slow but more sustained chemokine and
cytokine response in naïve foetal enterocytes compared to commensal Escherichia coli. BMC Immunol. 11:2.
Zocco, M. A., M. E. Ainora, G. Gasbarrini, and A. Gasbarrini. 2007.
Bacteroides thetaiotaomicron in the gut: Molecular aspects of
their interaction. Dig. Liver Dis. 39:707–712.
Zoumpopoulou, G., E. Tsakalidou, J. Dewulf, B. Pot, and C. Grangette. 2009. Differential crosstalk between epithelial cells,
dendritic cells and bacteria in a co-culture model. Int. J. Food
Microbiol. 131:40–51.