Maternal body mass index and necrotizing enterocolitis: A case-control study

INTRODUCTION

Our aim was to determine if maternal body mass index (BMI) is associated with necrotizing enterocolitis (NEC) in a large urban delivery center.

METHODS

This single center retrospective case-control study included 291 infants under gestational age of 33 weeks admitted to the neonatal intensive care unit (NICU) during a 10-year period. Cases of stage 2 and 3 NEC were matched at a ratio of 2 controls (n = 194) to 1 case (n = 97). Maternal BMI was categorized as normal (≤24.9), overweight (25-29.9) and obese (≥30). Chi-square and stepwise logistic regression were used for analysis. A power analysis was performed to determine if sample size was sufficient to detect an association.

RESULTS

Stepwise logistic regression demonstrated no association between NEC and maternal obesity. Maternal hypertension, pre-eclampsia, premature rupture of membranes, maternal exposure to antibiotics, placental abruption and gestational diabetes were not associated with NEC. Power analysis showed the sample size was sufficient to detect an association of NEC with maternal BMI in three groups analyzed. In this case-control study, there was an association between NEC and maternal overweight but not obesity at delivery.

DISCUSSION

Our results did not show a significant association of NEC with maternal obesity. The percent of overweight and obese mothers prior to pregnancy and at delivery was significantly higher in our population than the national average and may be responsible for the limited ability to reveal any association between maternal obesity and NEC.

Maternal Macro- and Micronutrient Intake During Pregnancy: Does It Affect Allergic Predisposition in Offspring?

This review article explores the available literature on the association of maternal nutrient intake with development of allergies in offspring. It examines the mechanisms for maternal diet-mediated effects on offspring immunity and dissects recent human and animal studies that evaluate the role of both maternal macro- and micronutrient intake on offspring susceptibility to asthma, eczema, food allergy, and atopy.

Tachygastria in Preterm Infants: A Longitudinal Cohort Study

OBJECTIVES

Tachygastria is a gastric dysrhythmia (>4 to ≤9 cycles per minute, cpm) associated with gastric hypomotility and gastrointestinal disorders. Healthy preterm infants spend more time in tachygastria than adults; however, normative values are not defined. We sought to determine the percent of time preterm infants spend in tachygastria.

METHODS

We conducted a longitudinal, prospective cohort study with weekly electrogastrography (EGG) recordings in 51 preterm <34 weeks' gestation and 5 term (reference) infants. We calculated percentage recording time in tachygastria (% tachygastria) and determined the mean ± standard deviation (SD) across EGG sessions. Mixed effects model was performed to test weekly variance in % tachygastria and gestational age effect. Successive pre- and post-prandial measurements were obtained to assess reproducibility of % tachygastria. We compared time to achieve full feeds between subjects with % tachygastria within 1 SD from the mean versus % tachygastria >1 SD from mean.

RESULTS

Three hundred seventy-six EGG sessions were completed (N = 56). Mean % tachygastria was 40% with SD ±5%. We demonstrated no change in % tachygastria across 9 postnatal weeks (P = 0.70) and no gestational age effect. No difference was demonstrated between successive pre- (P = 0.91) and post-prandial (P = 0.96) % tachygastria. Infants with 35%-45% tachygastria (within 1 SD from mean) had higher gestational age and less time to achieve full feeds than infants with <35% or >45% tachygastria.

CONCLUSIONS

EGG is a reproducible tool to assess % tachygastria in preterm infants. Clinical significance of increased or decreased % tachygastria needs further investigation to validate if 35%-45% tachygastria is safe for feeding.

Amniotic fluid metabolites mediate maternal high fat diet expansion of group 3 innate lymphoid cells in offspring

Introduction

Previously, we demonstrated that maternal high fat diet (mHFD) exposure results in a unique pattern of microbial colonization in offspring, expansion of IL-17 producing group 3 innate lymphoid cells (ILC3) and increased susceptibility to a model of necrotizing enterocolitis (NEC). We hypothesized that amniotic fluid (AF) metabolites are modified by maternal diet and partially responsible for the phenotype in offspring.

Methods

To assess if AF metabolites in mHFD were unique from regular diet (RD) AF, we collected AF from E15 dams and performed non-targeted global mass spectroscopy. To determine if the mHFD AF is responsible for expansion of ILC3, we gavaged 5-day-old RD germ-free pups with mHFD and RD AF (from conventional dams) every other day and examined them at 2 weeks by flow cytometry for ILC3. mHFD mothers were supplemented with metabolites that were decreased in the mHFD AF and offspring examined for expansion of ILC3 and susceptibility to the LPS/PAF model of NEC.

Results

We identified 1069 metabolites in HFD and RD AF. Principal component analysis revealed that mHFD AF was uniquely clustered from RD AF. We specifically found decreases in indole, short chain fatty acid and furoic acid metabolites in HFD AF compared to RD AF. Gavage of germ-free neonatal pups with mHFD AF resulted in expansion of IL-17 producing ILC3 compared to RD AF at 2 weeks. Supplementation of mHFD dams prenatally with metabolites diminished in HFD AF resulted in decreased expansion of ILC3 and resistance to LPS/PAF model of NEC.

Conclusion

mHFD modifies metabolites present in AF and can expand ILC3 in germ-free offspring. Supplementation of deficient dietary metabolites in mHFD pregnant dams rescues offspring from susceptibility to NEC.

Supported by NIH R01 1K12HD068369

Maternal microbial factors that affect the fetus and subsequent offspring

The maternal microbiome has emerged as an important area of investigation. While birth is a critical timepoint for initial colonization of the newborn, the fetus resides in the womb surrounded by multiple unique colonized niches. The maternal microbiome has recently been shown to be associated with several morbidities in offspring. Understanding the multiple bacterial niches within the pregnant woman and how they interact with the fetus in-utero can lead to novel therapies to improve the health of offspring. In this review, we provide an overview of the available literature on normal bacterial colonization within the individual niches of the pregnant woman and the known associations with outcomes in offspring, including a discussion of the controversy of in-utero colonization.

The emerging role of group 3 innate lymphoid cells in the neonate: interaction with the maternal and neonatal microbiome

Innate lymphoid cells (ILCs) are critical for host defense and are notably important in the context of the newborn when adaptive immunity is immature. There is an increasing evidence that development and function of group 3 ILCs (ILC3) can be modulated by the maternal and neonatal microbiome and is involved in neonatal disease pathogenesis. In this review, we explore the evidence that supports a critical role for ILC3 in resistance to infection and disease pathogenesis in the newborn, with a focus on microbial factors that modulate ILC3 function. We then briefly explore opportunities for research that are focused on the fetus and newborn.

Maternal high fat diet interacts with the maternal microbiome to expand IL-17 producing type 3 innate lymphoid cells in offspring

Introduction: Previously, we demonstrated that maternal high fat diet (mHFD) exposure results in a unique pattern of microbial colonization in offspring and subsequent expansion of IL-17 producing type 3 innate lymphoid cells (ILC3). We hypothesized that in utero mechanisms involving the maternal microbiome were responsible for the phenotype in offspring.

Methods:

To assess if the maternal microbiome was responsible for altering the mHFD offspring phenotype, we delivered mHFD and regular diet (RD)-exposed pups at birth by C-section (CS) and exposed mHFD mothers to broad-spectrum antibiotics (ABX) throughout pregnancy. We cross-fostered the offspring to RD mothers at birth. Microbial colonization in 2-week-old offspring was determined by 16s-based rRNA analysis, intestinal cytokines were quantified by qRT-PCR and lamina propria cells (LP) were profiled by flow cytometry. To determine if innate immunity is altered prenatally by maternal diet, we delivered mHFD and RD offspring by CS and examined the small intestine (SI) at birth for cytokine expression, TLR signaling and LP profiling. Global MyD88 KO mice on mHFD or RD were also examined for the same endpoints.

Results:

mHFD offspring at 2-weeks showed an expansion of Firmicutes and IL-17 producing ILC3, independent of the mode of delivery. ABX in mHFD mothers ameliorated the mHFD offspring phenotype, with microbial colonization and ILC3 similar to controls. mHFD offspring had altered TLR signaling at birth in SI. ILC3 were expanded at birth in mHFD offspring (14.2% vs 9.5%). MyD88−/− offspring exposed to mHFD did not have an expansion of ILC3.

Conclusion:

mHFD prenatally alters the offspring microbiome and ILC3 and this effect is dependent on the maternal microbiome and TLR signaling.

Traffic generated emissions alter the lung microbiota by promoting the expansion of Proteobacteria in C57Bl/6 mice placed on a high-fat diet

Air pollution has been documented to contribute to severe respiratory diseases like asthma and chronic obstructive pulmonary disorder (COPD). Although these diseases demonstrate a shift in the lung microbiota towards Proteobacteria, the effects of traffic generated emissions on lung microbiota profiles have not been well-characterized. Thus, we investigated the hypothesis that exposure to traffic-generated emissions can alter lung microbiota and immune defenses. Since a large population of the Western world consumes a diet rich in fats, we sought to investigate the synergistic effects of mixed vehicle emissions and high-fat diet consumption. We exposed 3-month-old male C57Bl/6 mice placed either on regular chow (LF) or a high-fat (HF: 45% kcal fat) diet to mixed emissions (ME: 30 µg PM/m³ gasoline engine emissions+70 µg PM/m³ diesel engine emissions) or filtered air (FA) for 6 h/d, 7 d/wk for 30 days. Levels of pulmonary immunoglobulins IgA, IgG, and IgM were analyzed by ELISA, and lung microbial profiling was done using qPCR and Illumina 16 S sequencing. We observed a significant decrease in lung IgA in the ME-exposed animals, compared to the FA-exposed animals, both fed a HF diet. Our results also revealed a significant decrease in lung IgG in the ME-exposed animals both on the LF diet and HF diet, in comparison to the FA-exposed animals. We also observed an expansion of Enterobacteriaceae belonging to the Proteobacteria phylum in the ME-exposed groups on the HF diet. Collectively, we show that the combined effects of ME and HF diet result in decreased immune surveillance and lung bacterial dysbiosis, which is of significance in lung diseases.

Exposure to diesel exhaust particles results in altered lung microbial profiles, associated with increased reactive oxygen species/reactive nitrogen species and inflammation, in C57Bl/6 wildtype mice on a high-fat diet

BACKGROUND

Exposure to traffic-generated emissions is associated with the development and exacerbation of inflammatory lung disorders such as chronic obstructive pulmonary disorder (COPD) and idiopathic pulmonary fibrosis (IPF). Although many lung diseases show an expansion of Proteobacteria, the role of traffic-generated particulate matter pollutants on the lung microbiota has not been well-characterized. Thus, we investigated the hypothesis that exposure to diesel exhaust particles (DEP) can alter commensal lung microbiota, thereby promoting alterations in the lung's immune and inflammatory responses. We aimed to understand whether diet might also contribute to the alteration of the commensal lung microbiome, either alone or related to exposure. To do this, we used male C57Bl/6 mice (4-6-week-old) on either regular chow (LF) or high-fat (HF) diet (45% kcal fat), randomly assigned to be exposed via oropharyngeal aspiration to 35 μg DEP, suspended in 35 μl 0.9% sterile saline or sterile saline only (control) twice a week for 30 days. A separate group of study animals on the HF diet was concurrently treated with 0.3 g/day of Winclove Ecologic® Barrier probiotics in their drinking water throughout the study.

RESULTS

Our results show that DEP-exposure increases lung tumor necrosis factor (TNF)-α, interleukin (IL)-10, Toll-like receptor (TLR)-2, TLR-4, and the nuclear factor kappa B (NF-κB) histologically and by RT-qPCR, as well as Immunoglobulin A (IgA) and Immunoglobulin G (IgG) in the bronchoalveolar lavage fluid (BALF), as quantified by ELISA. We also observed an increase in macrophage infiltration and peroxynitrite, a marker of reactive oxygen species (ROS) + reactive nitrogen species (RNS), immunofluorescence staining in the lungs of DEP-exposed and HF-diet animals, which was further exacerbated by concurrent DEP-exposure and HF-diet consumption. Histological examinations revealed enhanced inflammation and collagen deposition in the lungs DEP-exposed mice, regardless of diet. We observed an expansion of Proteobacteria, by qPCR of bacterial 16S rRNA, in the BALF of DEP-exposed mice on the HF diet, which was diminished with probiotic-treatment.

CONCLUSIONS

Our findings suggest that exposure to DEP causes persistent and sustained inflammation and bacterial alterations in a ROS-RNS mediated fashion, which is exacerbated by concurrent consumption of an HF diet.

Transient neonatal antibiotic exposure increases susceptibility to late-onset sepsis driven by microbiota-dependent suppression of type 3 innate lymphoid cells

Extended early antibiotic exposure in the neonatal intensive care unit is associated with an increased risk for the development of late-onset sepsis (LOS). However, few studies have examined the mechanisms involved. We sought to determine how the neonatal microbiome and intestinal immune response is altered by transient early empiric antibiotic exposure at birth. Neonatal mice were transiently exposed to broad-spectrum antibiotics from birth for either 3- (SE) or 7-days (LE) and were examined at 14-days-old. We found that mice exposed to either SE or LE showed persistent expansion of Proteobacteria (2 log difference, P < 0.01). Further, LE mice demonstrated baseline translocation of E. coli into the liver and spleen and were more susceptible K. pneumoniae-induced sepsis. LE mice had a significant and persistent decrease in type 3 innate lymphoid cells (ILC3) in the lamina propria. Reconstitution of the microbiome with mature microbiota by gavage in LE mice following antibiotic exposure resulted in an increase in ILC3 and partial rescue from LOS. We conclude that prolonged exposure to broad spectrum antibiotics in the neonatal period is associated with persistent alteration of the microbiome and innate immune response resulting in increased susceptibility to infection that may be partially rescued by microbiome reconstitution.

Indole metabolites are altered in maternal high fat diet exposed offspring and can modulate type 3 innate lymphoid cell function

Background

We have shown that maternal high fat diet exposure (mHFD) results in a microbiota-dependent expansion of IL-17 producing type 3 innate lymphoid cells (ILC3) in offspring. We hypothesized that the unique mHFD microbiome in offspring would result in an altered metabolite profile that could potentiate Ahr signaling and ILC3 function.

Methods

Murine offspring exposed to 60% mHFD were examined at 2-weeks old. Stool was examined by high-throughput, non-targeted mass spectroscopy-based metabolic analysis. Microbial colonization was examined by next generation sequencing. 2-week-old small intestine (SI) from regular diet (RD) offspring was exposed to selected indole metabolites for 24 hours and supernatant examined by ELISA. For in vivo experiments, bacteria was gavaged to RD offspring beginning at 5 days old. Flow cytometry of SI lamina propria cells was used to examine ILC3.

Results

mHFD offspring had a differential pattern of colonization and metabolite composition. mHFD offspring had a consistent expansion of Lactobacillus murinus. In vivo exposure to L. murinus resulted in a 30% increase in IL-17 producing ILC3 not seen with exposure to L. rhamnosus. Metabolomics of stool from mHFD offspring showed a decrease in indole-3-acetate and 3-methyldiozyindole (p&lt;0.00001). SI stimulated with indole metabolites showed a 50% decrease in production of IL-17 (p&lt;0.05) and IL-22 (p&lt;0.05).

Conclusion

L. murinus is specifically expanded in mHFD offspring and can increase IL-17 producing ILC3. L. murinus may expand ILC3 by differential metabolism of indole metabolites. Metabolism of indole metabolites by L. murinus and their role on Ahr signaling need to be further examined as a mechanism of modulating ILC3 response in offspring.

Suppression of IL-17 producing type 3 innate lymphoid cells and increased susceptibility to Klebsiella pneumoniae sepsis in neonatal mice exposed to extended empiric antibiotics

Background/Objective

Over 75% of newborns admitted to the neonatal intensive care unit (NICU) receive antibiotics with no proven infection (empiric) at birth. Empiric antibiotic use in the NICU increases susceptibility to late onset sepsis, but the mechanisms are poorly understood.

Methods

Neonatal mice were exposed to broad-spectrum antibiotics through their dams from birth for either 3-(short exposure, SE) or 7-days (long exposure, LE). At 14 days, qRT-PCR was used for bacterial 16S rRNA (stool), antimicrobial proteins (AMPs) and cytokines (small intestine, SI). Blood, liver and spleen cultures was utilized to detect bacterial translocation. Histology of SI was performed for Paneth cells. Flow cytometric analysis of lamina propria (LP) cells determined the presence of type 3 innate lymphoid cells (ILC3), neutrophils, macrophages, T- and B-cells. Susceptibility to sepsis was determined by IP injection of K. pneumoniae in 12-day-old pups.

Results

Mice exposed to SE and LE showed significant expansion of Enterobacteriaceae (2 log difference). LE mice showed baseline translocation of Enterobacteriaceae into the liver and spleen and were more susceptible to sepsis. By flow cytometry, LE mice showed a persistent and significant 50% decrease in IL-17 producing ILC3 in the LP, with other cell types unaffected. Further, the ILC3 present were skewed to the IL-22 producing phenotype. AMPs and Paneth cells were also increased in the SI, likely mediated by the increase in IL-22.

Conclusions

Extended empiric antibiotic exposure resulted in persistent expansion of Enterobacteriaceae and increased susceptibility to neonatal sepsis, likely mediated by a microbiota-dependent decrease in IL-17-producing ILC3.

Maternal high-fat diet results in microbiota-dependent expansion of ILC3s in mice offspring

Maternal obesity and a high-fat diet (HFD) during the perinatal period have documented short- and long-term adverse outcomes for offspring. However, the mechanisms of maternal HFD effects on neonatal offspring are unclear. While the effects of maternal HFD exposure during pregnancy on the offspring are increasingly being appreciated, we do not know if maternal HFD alters the microbiota or affects neonatal susceptibility to inflammatory conditions, nor the mechanisms involved. In this study, we show that the offspring of mothers exposed to HFD develop a unique microbiota, marked by expansion of Firmicutes, and an increase in IL-17-producing type 3 innate lymphoid cells (ILC3s). The expansion of ILC3s was recapitulated through neocolonization with HFD microbiota alone. Further, the HFD offspring were susceptible to a neonatal model of inflammation that was reversible with IL-17 blockade. Collectively, these data suggest a previously unknown and unique role for ILC3s in the promotion of an early inflammatory susceptibility in the offspring of mothers exposed to HFD.

IFN-γ production by CD4 CD8 double positive cells is essential for expansion of Proteobacteria in the neonatal murine intestine

Background

Expansion of Proteobacteria is seen in the neonatal intestine in both humans and mice. Proteobacteria are also significantly over-represented in preterm infants that develop Necrotizing Enterocolitis (NEC). Neonatal mice are more susceptible to models of NEC. The mechanism of expansion of Proteobacteria in neonatal mice and susceptibility to NEC remain undefined.

Objective

To identify immune modulators that favor expansion of Proteobacteria in the neonatal murine intestine.

Methods

qRT-PCR of bacterial 16S rRNA gene sequence tags of colonic fecal contents from 1–3 week (wk) old wild type (WT), IFN-γ knock out and Rag deficient mice was performed to identify major bacterial groups. qRT-PCR and ELISA of whole colon were used to profile cytokine expression. Flow-cytometry of lamina propria cells was used to characterize cells in 1-,2- and 3-wk old mice. IFN-γ neutralizing Ab was given IP to 3 day old mice and then similarly examined at 2 wks.

Results

2-wk-old WT mice showed increased expansion of Proteobacteria and increased production of IFN-γ. IFN-γ KO mice had minimal expansion of Proteobacteria in the colon, this was also seen in WT mice blocked with IFN-γ Ab. Flow-cytometry revealed a unique subset of CD4 CD8 double positive cells, only present in neonatal mice, that produce IFN-γ in WT mice. Rag deficient mice did not have this subset of cells and also had minimal colonization by Proteobacteria at 2-wks.

Conclusions

IFN-γ promotes the expansion of Proteobacteria in the neonatal intestine. A unique and transient subset of CD4 CD8 cells, that are absent in Rag deficient mice, appear to be responsible for the increased IFN-γ in neonatal mice. This is a potential target for intervention in the prevention of NEC in preterm infants.

The NLRP3 inflammasome is critically involved in the development of bronchopulmonary dysplasia

The pathogenesis of bronchopulmonary dysplasia (BPD), a devastating lung disease in preterm infants, includes inflammation, the mechanisms of which are not fully characterized. Here we report that the activation of the NLRP3 inflammasome is associated with the development of BPD. Hyperoxia-exposed neonatal mice have increased caspase-1 activation, IL1β and inflammation, and decreased alveolarization. Nlrp3(-/-) mice have no caspase-1 activity, no IL1β, no inflammatory response and undergo normal alveolarization. Treatment of hyperoxia-exposed mice with either IL1 receptor antagonist to block IL1β or glyburide to block the Nlrp3 inflammasome results in decreased inflammation and increased alveolarization. Ventilated preterm baboons show activation of the NLRP3 inflammasome with increased IL1β:IL1ra ratio. The IL1β:IL1ra ratio in tracheal aspirates from preterm infants with respiratory failure is predictive of the development of BPD. We conclude that early activation of the NLRP3 inflammasome is a key mechanism in the development of BPD, and represents a novel therapeutic target for BPD.

Proteobacteria-specific IgA regulates maturation of the intestinal microbiota

The intestinal microbiota changes dynamically from birth to adulthood. In this study we identified γ-Proteobacteria as a dominant phylum present in newborn mice that is suppressed in normal adult microbiota. The transition from a neonatal to a mature microbiota was in part regulated by induction of a γ-Proteobacteria-specific IgA response. Neocolonization experiments in germ-free mice further revealed a dominant Proteobacteria-specific IgA response triggered by the immature microbiota. Finally, a role for B cells in the regulation of microbiota maturation was confirmed in IgA-deficient mice. Mice lacking IgA had persistent intestinal colonization with γ-Proteobacteria that resulted in sustained intestinal inflammation and increased susceptibility to neonatal and adult models of intestinal injury. Collectively, these results identify an IgA-dependent mechanism responsible for the maturation of the intestinal microbiota.

Maternal high fat diet alters Th17 responses and bacterial colonization in newborn mice. (P3156)

The American diet is dominated by high-fat foods and 50% of women of childbearing age are either overweight or obese. Studies in adult mice show that the Th17 response is important in regulating the microbiota and modulating development of diet-induced obesity. The effect of maternal high fat diet on the acquisition of the microbiota and on the Th17 cytokine responses are unknown. Objective: To define the effect of maternal high fat diet on acquisition of the microbiota and Th17 responses in offspring. Methods: 454 pyrosequencing of bacterial 16S rRNA gene in colonic fecal contents from offspring of mothers on a high fat diet and regular diet at 1-, 3-, and 6-weeks of age. Analysis of Th17 and inflammatory cytokines in the colon of offspring by qRT-PCR and ELISA. Results: 1-week-old pups from mothers on high fat diet had a unique microbiota that was dominant in Firmicutes and segmented filamentous bacteria compared to control newborn mice. Offspring of mothers on high fat diet showed a persistent change with age in their colonic microbiota even when maintained on a regular diet. There was increased production of inflammatory cytokines in pups born to mothers on high fat diet, with markedly increased expression of IL-17 and IL-22. Conclusions: Acquisition of the microbiota was unique in pups of mothers on a high fat diet with increased baseline inflammation and an altered Th17 response. Long-term consequences are under investigation and may contribute to programming obesity.

Parasite-induced TH1 cells and intestinal dysbiosis cooperate in IFN-γ-dependent elimination of Paneth cells

Activation of Toll-like receptors (TLRs) by pathogens triggers cytokine production and T cell activation, immune defense mechanisms that are linked to immunopathology. Here we show that IFN-γ production by CD4(+) T(H)1 cells during mucosal responses to the protozoan parasite Toxoplasma gondii resulted in dysbiosis and the elimination of Paneth cells. Paneth cell death led to loss of antimicrobial peptides and occurred in conjunction with uncontrolled expansion of the Enterobacteriaceae family of Gram-negative bacteria. The expanded intestinal bacteria were required for the parasite-induced intestinal pathology. The investigation of cell type-specific factors regulating T(H)1 polarization during T. gondii infection identified the T cell-intrinsic TLR pathway as a major regulator of IFN-γ production in CD4(+) T cells responsible for Paneth cell death, dysbiosis and intestinal immunopathology.

Lactobacillus rhamnosus (LGG) regulates IL-10 signaling in the developing murine colon through upregulation of the IL-10R2 receptor subunit

The intestinal microflora is critical for normal development, with aberrant colonization increasing the risk for necrotizing enterocolitis (NEC). In contrast, probiotic bacteria have been shown to decrease its incidence. Multiple pro- and anti-inflammatory cytokines have been identified as markers of intestinal inflammation, both in human patients with NEC and in models of immature intestine. Specifically, IL-10 signaling attenuates intestinal responses to gut dysbiosis, and disruption of this pathway exacerbates inflammation in murine models of NEC. However, the effects of probiotics on IL-10 and its signaling pathway, remain poorly defined. Real-time PCR profiling revealed developmental regulation of MIP-2, TNF-α, IL-12, IL-10 and the IL-10R2 subunit of the IL-10 receptor in immature murine colon, while the expression of IL-6 and IL-18 was independent of postnatal age. Enteral administration of the probiotic Lactobacillus rhamnosus GG (LGG) down-regulated the expression of TNF-α and MIP-2 and yet failed to alter IL-10 mRNA and protein expression. LGG did however induce mRNA expression of the IL-10R2 subunit of the IL-10 receptor. IL-10 receptor activation has been associated with signal transducer and activator of transcription (STAT) 3-dependent induction of members of the suppressors of cytokine signaling (SOCS) family. In 2 week-old mice, LGG also induced STAT3 phosphorylation, increased colonic expression of SOCS-3, and attenuated colonic production of MIP-2 and TNF-α. These LGG-dependent changes in phosphoSTAT3, SOCS3, MIP-2 and TNF-α were all inhibited by antibody-mediated blockade of the IL-10 receptor. Thus LGG decreased baseline proinflammatory cytokine expression in the developing colon through upregulation of IL-10 receptor-mediated signaling, most likely due to the combined induction of phospho-STAT3 and SOCS3. Furthermore, LGG-dependent increases in IL-10R2 were associated with reductions in TNF-α, MIP-2 and disease severity in a murine model of intestinal injury in the immature colon.

Prolonged persistent patent ductus arteriosus: potential perdurable anomalies in premature infants

OBJECTIVE

Patent ductus arteriosus (PDA) is a common condition among preterm infants. Controversy exists regarding the risk-benefit ratio of early closure of PDAs by either medical or surgical treatments. On the other hand, potential morbidities associated with no or delayed closure has not been well studied. The objective of the study was to determine if there is an association of prolonged persistent PDA (PP-PDA) with various morbidities in infants ≤28 weeks or 1250 g.

STUDY DESIGN

This matched case-control analysis includes preterm infants with a diagnosis of PDA over a period of 28 months in a single level III center in the USA. The predictive variable was the presence of a PP-PDA (PDA>3 weeks). Cases were infants with PP-PDA and controls were those with PDA but not PP-PDA (two controls for each case). Outcome variables included days on mechanical ventilation and with oxygen treatment, length of hospital stay, bronchopulmonary dysplasia (BPD), retinopathy of prematurity stage III-V (ROP) necrotizing enterocolitis grade II or more (NEC), delayed growth, direct hyperbilirubinemia >4 mg dl(-1) and osteopenia of prematurity. Data was obtained from database collected prospectively and from the review of clinical records when necessary. Statistics included ANOVA, Kaplan-Meier curves and χ (2). Significance was set at P<0.05.

RESULT

PP-PDA was associated with a significant increase in the number of days of mechanical ventilation, oxygen treatment and length of hospital stay, and in the rates of BPD (60% vs 4.5%), NEC (29% vs 5%), ROP (43% vs 5%), direct hyperbilirubinemia (41% vs 3%), osteopenia (44% vs 6%), parenteral nutrition for >40 days (70% vs 21%), tracheostomy during the hospitalization (15% vs 0%) and delayed growth (70% vs 21%), were also significantly higher in babies with PP-PDA.

CONCLUSION

A prolonged exposure to PDA does not seem to be inconsequential for some infants and is associated with an increase prevalence of severe morbidities with potential long lasting effects.

Therapeutic helminth infection of macaques with idiopathic chronic diarrhea alters the inflammatory signature and mucosal microbiota of the colon

Idiopathic chronic diarrhea (ICD) is a leading cause of morbidity amongst rhesus monkeys kept in captivity. Here, we show that exposure of affected animals to the whipworm Trichuris trichiura led to clinical improvement in fecal consistency, accompanied by weight gain, in four out of the five treated monkeys. By flow cytometry analysis of pinch biopsies collected during colonoscopies before and after treatment, we found an induction of a mucosal T_H2 response following helminth treatment that was associated with a decrease in activated CD4⁺ Ki67+ cells. In parallel, expression profiling with oligonucleotide microarrays and real-time PCR analysis revealed reductions in T_H1-type inflammatory gene expression and increased expression of genes associated with IgE signaling, mast cell activation, eosinophil recruitment, alternative activation of macrophages, and worm expulsion. By quantifying bacterial 16S rRNA in pinch biopsies using real-time PCR analysis, we found reduced bacterial attachment to the intestinal mucosa post-treatment. Finally, deep sequencing of bacterial 16S rRNA revealed changes to the composition of microbial communities attached to the intestinal mucosa following helminth treatment. Thus, the genus Streptophyta of the phylum Cyanobacteria was vastly increased in abundance in three out of five ICD monkeys relative to healthy controls, but was reduced to control levels post-treatment; by contrast, the phylum Tenericutes was expanded post-treatment. These findings suggest that helminth treatment in primates can ameliorate colitis by restoring mucosal barrier functions and reducing overall bacterial attachment, and also by altering the communities of attached bacteria. These results also define ICD in monkeys as a tractable preclinical model for ulcerative colitis in which these effects can be further investigated.

Young macaques kept in captivity at Primate Research Centers often develop chronic diarrhea, which is difficult to treat because it is poorly understood. This disease shares many features with ulcerative colitis, which is an autoimmune disease affecting the intestinal tract of humans. Recently, parasitic worms have been used in clinical trials to treat inflammatory bowel diseases in humans with positive results, but very little is known about how worms can improve symptoms. We performed a trial where we treated macaques suffering from chronic diarrhea with human whipworms, collecting gut biopsies before and after treatment. We found that 4 out of the 5 treated macaques improved their symptoms and studied the changes in their gut immune responses, as they got better. We found that after treatment with worms, the monkeys had less bacteria attached to their intestinal wall and a reduced inflammatory response to the gut bacteria. Additionally, the composition of gut bacteria was altered in the sick macaques and was restored close to normal after treatment with whipworms. These results provide a potential mechanism by which parasitic worms may improve the symptoms of intestinal inflammation, by reducing the immune response against intestinal bacteria.

Trefoil factor 2 negatively regulates type 1 immunity against Toxoplasma gondii

IL-12-mediated type 1 inflammation confers host protection against the parasitic protozoan Toxoplasma gondii. However, production of IFN-γ, another type 1 inflammatory cytokine, also drives lethality from excessive injury to the intestinal epithelium. As mechanisms that restore epithelial barrier function following infection remain poorly understood, this study investigated the role of trefoil factor 2 (TFF2), a well-established regulator of mucosal tissue repair. Paradoxically, TFF2 antagonized IL-12 release from dendritic cells (DCs) and macrophages, which protected TFF2-deficient (TFF2(-/-)) mice from T. gondii pathogenesis. Dysregulated intestinal homeostasis in naive TFF2(-/-) mice correlated with increased IL-12/23p40 levels and enhanced T cell recruitment at baseline. Infected TFF2(-/-) mice displayed low rates of parasite replication and reduced gut immunopathology, whereas wild-type (WT) mice experienced disseminated infection and lethal ileitis. p38 MAPK activation and IL-12p70 production was more robust from TFF2(-/-)CD8+ DC compared with WT CD8+ DC and treatment of WT DC with rTFF2 suppressed TLR-induced IL-12/23p40 production. Neutralization of IFN-γ and IL-12 in TFF2(-/-) animals abrogated resistance shown by enhanced parasite replication and infection-induced morbidity. Hence, TFF2 regulated intestinal barrier function and type 1 cytokine release from myeloid phagocytes, which dictated the outcome of oral T. gondii infection in mice.

IL-6 signaling SOCS critical for IL-12 host response to Toxoplasma gondii

SOCS are a family of proteins that play an important role in the negative regulation of the cytokine-JAK-STAT pathway. Socs3 deletion results in prolonged IL-6 signaling measured by STAT3 phosphorylation. A role for STAT3 and SOCS3 in the context of Toxoplasma gondii infection is of particular importance, because STAT3 appears to be a key target of T. gondii virulence factors. By utilizing LysM-cre Socs3(fl/fl) mice, the Hunter laboratory recently established that macrophage-specific SOCS3 knockout mice have enhanced susceptibility to infection with T. gondii. The authors demonstrated that lack of SOCS3-mediated control of IL-6 signaling results in acute susceptibility to T. gondii due to impaired IL-12 production by inflammatory monocytes, macrophages and neutrophils. This article further explores these findings and their implications in the field of host resistance to microbial pathogens.

B cell-intrinsic MyD88 signaling prevents the lethal dissemination of commensal bacteria during colonic damage

The Toll-like receptor adaptor protein MyD88 is essential for the regulation of intestinal homeostasis in mammals. In this study, we determined that Myd88-deficient mice are susceptible to colonic damage that is induced by dextran sulfate sodium (DSS) administration resulting from uncontrolled dissemination of intestinal commensal bacteria. The DSS-induced mortality of Myd88-deficient mice was completely prevented by antibiotic treatment to deplete commensal bacteria. By using cell type-specific Myd88-deficient mice, we established that B cell-intrinsic MyD88 signaling plays a central role in the resistance to DSS-induced colonic damage via the production of IgM and complement-mediated control of intestinal bacteria. Our results indicate that the lack of intact MyD88 signaling in B cells, coupled with impaired epithelial integrity, enables commensal bacteria to function as highly pathogenic organisms, causing rapid host death.

Issues of prematurity and HIV infection

Prematurity and HIV present a complex challenge, with biologic underpinnings that are often confounded by a myriad of other factors that coexist in this high-risk population. Furthermore, many of the current management options designed to reduce mother-to-infant transmission, including antiretroviral therapy and cesarean birth, may each have an independent effect on prematurity. These issues notwithstanding, knowledge gained from randomized controlled trials and epidemiologic studies has made a significant impact on the approach to this challenging public health problem worldwide. This article discusses the significance, contribution, and management of perinatal transmission of HIV in prematurity.

Commensal Escherichia coli reduces epithelial apoptosis through IFN-alphaA-mediated induction of guanylate binding protein-1 in human and murine models of developing intestine

Appropriate microbial colonization protects the developing intestine by promoting epithelial barrier function and fostering mucosal tolerance to luminal bacteria. Commensal flora mediate their protective effects through TLR9-dependent activation of cytokines, such as type I IFNs (alpha, beta) and IL-10. Although IFN-beta promotes apoptosis, IFN-alpha activates specific antiapoptotic target genes whose actions preserve epithelial barrier integrity. We have recently identified guanylate binding protein-1 (GBP-1) as an antiapoptotic protein, regulated by both type I and type II IFNs, that promotes intestinal epithelial barrier integrity in mature intestine. However, the mechanisms by which commensal bacteria regulate epithelial apoptosis during colonization of immature intestine and the contributions of GBP-1 are unknown. The healthy newborn intestine is initially colonized with bacterial species present in the maternal gastrointestinal tract, including nonpathogenic Escherichia coli. Therefore, we examined the influence of commensal E. coli on cytokine expression and candidate mediators of apoptosis in preweaned mice. Specifically, enteral exposure of 2 wk-old mice to commensal E. coli for 24 h selectively increased both IFN-alphaA and GBP-1 mRNA expression and prevented staurosporine-induced epithelial apoptosis. Exogenous IFN-alphaA treatment also induced GBP-1 expression and protected against staurosporine-induced apoptosis in a GBP-1 dependent manner, both in vitro and ex vivo. These findings identify a role for IFN-alphaA-mediated GBP-1 expression in the prevention of intestinal epithelial apoptosis by commensal bacteria. Thus IFN-alphaA mediates the beneficial effects of commensal bacteria and may be a promising therapeutic target to promote barrier integrity and prevent the inappropriate inflammatory responses seen in developing intestine as in necrotizing enterocolitis.