The Effects of Genetic Relatedness on the Preterm Infant Gut Microbiota

Intestinal flora and linear growth in children

The gut microbiota plays a critical role in human growth and development as well as the regulation of human pathophysiological processes. According to research, the gut microbiota controls the host's growth and development in areas such as nutrition, metabolism, endocrine hormones, and immune modulation. The human gut microbiota has an important role in child and adolescent growth, especially when nutritional conditions are poor. In this review, we focus on recent findings about the gut microbiota's influence on child growth, including the relationship between the gut microbiota and linear growth during pregnancy, infancy, childhood, and adolescence. Furthermore, we also review some mechanisms by which intestinal flora influence the host's linear growth. Although the data supports a link between intestinal flora and linear development in children, our review has limitations that prohibit us from fully verifying the causal relationship between gut flora and linear development in children. Improving the gut microbiota, in conjunction with renutrition techniques, has the potential to ameliorate the growth and development impairments currently associated with chronic illness and malnutrition in children.

Human milk nutrient fortifiers alter the developing gastrointestinal microbiota of very-low-birth-weight infants

Nutrient fortifiers are added to human milk to support the development of very-low-birth-weight infants. Currently, bovine-milk-based fortifiers (BMBFs) are predominantly administered, with increasing interest in adopting human-milk-based fortifiers (HMBFs). Although beneficial for growth, their effects on the gastrointestinal microbiota are unclear. This triple-blind, randomized clinical trial (NCT02137473) tested how nutrient-enriching human milk with HMBF versus BMBF affects the gastrointestinal microbiota of infants born < 1,250 g during hospitalization. HMBF-fed infants (n = 63, n = 269 stools) showed lower microbial diversity, altered microbial community structure, and changes in predicted microbial functions compared with BMBF-fed infants (n = 56, n = 239 stools). HMBF-fed infants had higher relative and normalized abundances of unclassified Enterobacteriaceae and lower abundances of Clostridium sensu stricto. Post hoc analyses identified dose-dependent relationships between individual feed components (volumes of mother's milk, donor milk, and fortifiers) and the microbiota. These results highlight how nutrient fortifiers impact the microbiota of very-low-birth-weight infants during a critical developmental window.

Metagenomic profile of the fecal microbiome of preterm infants consuming mother's own milk with bovine milk-based fortifier or infant formula: a cross-sectional study

BACKGROUND

Preterm (PT) infants harbor a different gut microbiome than full-term infants. Multiple factors affect gut microbial colonization of PT infants, including low gestational age, high rates of Cesarean section, exposure to antibiotics, and diet. Human milk, whether it's mother's own milk (MOM) or donor human milk, is the preferred feeding mode for PT infants but needs to be fortified to achieve adequate nutrient content. Infant formulas are introduced at later stages if human milk is insufficient or unavailable. How these dietary exposures affect the gut microbiome of PT infants is poorly understood.

OBJECTIVES

The goal of this study was to evaluate the metagenomic potential of the fecal microbiome of PT infants consuming MOM with bovine milk-based fortifier compared with PT formula alone.

METHODS

Forty-two stool samples, from 27 infants consuming MOM or formula (21 samples in each group) were included. Twelve infants had repeated sampling (2-3 samples). Shotgun genomic DNA sequencing was performed and analyzed using MetaPhlAn and HUMAnN2. Multivariate regression analysis, adjusting by the repeated sampling, was used to identify the features that differed between PT infants consuming MOM compared with formula.

RESULTS

The primary function of the fecal microbiome of PT infants was characterized by a high abundance of biosynthesis pathways. A set of core features was identified; these belonged to pathways for amino acid metabolism and vitamin K-2 biosynthesis. Five pathways significantly differed between the MOM and formula group. Pathways for fatty acid and carbohydrate degradation were significantly higher in the MOM group. Taxonomically, members of the phylum Actinobacteria and the genus Bifidobacterium were higher in PT infants exposed to MOM.

CONCLUSIONS

This study provides insight into the influence of feeding MOM compared with infant formula on the structure and function of the fecal microbiome of PT infants.

Postnatal growth and gut microbiota development influenced early childhood growth in preterm infants

BACKGROUND

Preterm infants are at high risk for growth failure and childhood weight problems due to the disruption of normal intrauterine growth and nutrition. Early nutritional support and microbiome acquisition can play an important role in childhood growth.

OBJECTIVE

Our study examined potential postnatal indicators, including gut bacterial compositions, macronutrients, and catch-up growth, of growth pattern from infancy into early childhood.

METHODS

This is a retrospective study of preterm infants born < 35 weeks who were followed up in the university complex care clinic from 2012-2018. Weight and length z-scores at birth, 1, 2, 4, 6, 12 and 15 months, and body mass index (BMI) and length z-scores from 2 to 5 years of age were collected. Catch-up growths were calculated by changes in z-scores and divided into early (birth-4 months) and late (4-18 months). Postnatal nutritional data and fecal samples were collected. Fecal microbiome data obtained from 16S RNA V4 sequencing was analyzed against clinical and growth data using a regression model.

RESULTS

160 infants included in the final analysis had birth weight and gestational age of 1,149 ± 496 grams and 28 ± 3 weeks. Early weight gain positively correlated with length z-scores but not with BMI at 2 years of age. BMI at 2 years of age strongly correlated with BMI at 3, 4, and 5 years of age. Postnatal abundance of Gammaproteobacteria was negatively associated with early growth while Bacteroides and Lactobacillus were positively associated with childhood BMI.

CONCLUSION

Our findings suggest that optimal postnatal nutrition promoted early catch-up growth in weight as well as improved linear growth without influence on childhood BMI. Postnatal gut microbial colonization, which is a modifiable factor, was associated with childhood growth in preterm infants.

A Pilot Study To Establish an In Vitro Model To Study Premature Intestinal Epithelium and Gut Microbiota Interactions

Intestinal microbiota has emerged as an important player in the health and disease of preterm infants. The interactions between intestinal flora and epithelium can lead to local injury and systemic diseases. A suitable in vitro cell model is needed to enhance our understanding of these interactions. In this study, we exposed fetal epithelial cell cultures (FHs-74 int cells, human, ATCC CCL 241) to sterile fecal filtrates derived from stool collected from preterm infants at <2 and at 3 to 4 weeks of age. We measured the cytokine levels from the culture media after 4, 24, and 48 h of exposure to the fecal filtrates. We analyzed the 16S rRNA V4 gene data of the fecal samples and transcriptome sequencing (RNA-seq) data from the fetal epithelial cells after 48 h of exposure to the same fecal filtrates. The results showed correlations between inflammatory responses (both cytokine levels and gene expression) and the Proteobacteria-to-Firmicutes ratio and between fecal bacterial genera and epithelial apoptosis-related genes. Our in vitro cell model can be further developed and applied to study how the epithelium responds to different microbial flora from preterm infants. Combining immature epithelial cells and preterm infant stool samples into one model allows us to investigate disease processes in preterm infants in a way that had not been previously reported.

IMPORTANCE The gut bacterial flora influences the development of the immune system and long-term health outcomes in preterm infants. Studies of the mechanistic interactions between the gut bacteria and mucosal barrier are limited to clinical observations, animal models, and in vitro cell culture models for this vulnerable population. Most in vitro cell culture models of microbe-host interactions use single organisms or adult origin cell lines. Our study is innovative and significant in that we expose immature epithelial cells derived from fetal tissues to fecal filtrates from eight stool samples from four preterm infants to study the role of intestinal epithelial cells. In addition, we analyzed epithelial gene expression to examine multiple cellular processes simultaneously. This model can be developed into patient-derived two- or three-dimensional cell cultures exposed to their own fecal material to allow better prediction of patient physiological responses to support the growing field of precision medicine.

How Gut Microbiota Supports Immunity, Growth and Development of Preterm Infants: A Narrative Review

ABSTRACTBackground: Gut microbiota, a complex ecosystem consisting of abundant microorganisms, plays a role in preterm infants’ immunity, growth, and development. Dysbiosis or disruption of the gut microbiota can precipitate various diseases, such as allergy or autoimmune disorders in premature infants. Purpose: This study aimed to review gut microbiota in preterm infants and its role in supporting the infants’ immunity, growth, and development. Discussion: Bifidobactericeae is the predominant microbiota in GI tract of preterm infants. However, various factors can influence this gut microbiota e.g., genetics, lifestyle of the mothers (smoking, diet, use of antibiotic, obesity), birth mode, type of feeding, and environmental factors. Gut dysbiosis can result in impaired immune system which predisposes the preterm infants to infections, even fatal adverse event. Furthermore, the growth and development might be affected as well as lead to various neurodevelopmental and psychiatric disorders. Human milk is a prebiotic source which can stimulate the growth of Baifidobactericeae and Bacteroidetes. If the human milk is inadequate or unavailable, the recommended interventions for gut dysbiosis in premature infants are probiotics, prebiotics, or both supplementations (synbiotics). The administration of prebiotics and probiotics associates with lower morbidity and death rates in preterm infants, as well as shorter duration of hospital stay and duration to achieve full enteral feeding. Conclusions: Immunity as well as growth and development of preterm infants are affected greatly by gut microbiota The less diverse microbiota in preterm infants’ gut predispose them to various health problems. Hence, this problem should be managed properly, one of which is prebiotic and probiotic supplementation Keywords: Gastrointestinal Microbiome, Premature, Immunity, Growth, Development

Human Milk-Based or Bovine Milk-Based Fortifiers Differentially Impact the Development of the Gut Microbiota of Preterm Infants

Background: Preterm infants are exposed to different dietary inputs during their hospitalization in the neonatal intensive care unit (NICU). These include human milk (HM), with a human milk-based (HMF) or a bovine milk-based (BMF) fortifier, or formula. Milk consumption and the type of fortification will cause changes in the gut microbiota structure of preterm infants. This study aimed to characterize the gut microbiota of PT infant according to the type of feeding and the type of HM fortification and its possible association with infant's growth. Methods: Ninety-seven infants born ≤33 wks of gestation or <1,500 g were followed during the hospitalization period in the NICU after birth until discharge. Clinical and dietary information was collected, including mode of delivery, pregnancy complications, mechanical ventilation, use of antibiotics, weight, and type and amount of milk consumed. To characterize the gut microbiota composition, weekly stool samples were collected from study participants. The V3-V4 region of the 16S rRNA bacterial gene was Sequenced using Illumina MiSeq technology. Results: After birth, black maternal race, corrected gestational age (GA) and exposure to pregnancy complications, had a significant effect on gut microbial diversity and the abundance of Enterococcus, Veillonella, Bifidobacterium, Enterobacter, and Bacteroides. Over the course of hospitalization, corrected GA and exposure to chorioamnionitis remained to have an effect on gut microbial composition. Two different enterotypes were found in the gut microbiota of preterm infants. One enriched in Escherichia-Shigella, and another enriched in uncharacterized Enterobacteriaceae, Klebsiella and Clostridium sensu stricto 1. Overall, HM and fortification with HMF were the most common feeding strategies. When consuming BMF, PT infants had higher growth rates than those consuming HMF. Milk and type of fortification were significantly associated with the abundance of Clostridium sensu stricto 1, Bifidobacterium and Lactobacillus. Conclusions: This observational study shows the significant association between milk consumption and the exposure to HMF or BMF fortification in the fecal microbiota composition of preterm infants. Additionally, these results show the effect of other perinatal factors in the establishment and development of PT infant's gut microbiota.