The microbiome, guard or threat to infant health

Gut microbiota in preterm infants receiving breast milk or mixed feeding

BACKGROUND

Preterm birth is the leading cause of mortality in newborns, with very-low-birth-weight infants usually experiencing several complications. Breast milk is considered the gold standard of nutrition, especially for preterm infants with delayed gut colonization, because it contains beneficial microorganisms, such as Lactobacilli and Bifidobacteria.

AIM

To analyze the gut microbiota of breastfed preterm infants with a birth weight of 1500 g or less.

METHODS

An observational study was performed on preterm infants with up to 36.6 wk of gestation and a birth weight of 1500 g or less, born at the University Hospital Dr. José Eleuterio González at Monterrey, Mexico. A total of 40 preterm neonates were classified into breast milk feeding (BM) and mixed feeding (MF) groups (21 in the BM group and 19 in the MF group), from October 2017 to June 2019. Fecal samples were collected before they were introduced to any feeding type. After full enteral feeding was achieved, the composition of the gut microbiota was analyzed using 16S rRNA gene sequencing. Numerical variables were compared using Student’s t-test or using the Mann–Whitney U test for nonparametric variables. Dominance, evenness, equitability, Margalef’s index, Fisher’s alpha, Chao-1 index, and Shannon’s diversity index were also calculated.

RESULTS

No significant differences were observed at the genus level between the groups. Class comparison indicated higher counts of Alphaproteobacteria and Betaproteobacteria in the initial compared to the final sample of the BM group (P < 0.011). In addition, higher counts of Gammaproteobacteria were detected in the final than in the initial sample (P = 0.040). According to the Margalef index, Fisher’s alpha, and Chao-1 index, a decrease in species richness from the initial to the final sample, regardless of the feeding type, was observed (P < 0.050). The four predominant phyla were Bacteroidetes, Actinobacteria, Firmicutes, and Proteobacteria, with Proteobacteria being the most abundant. However, no significant differences were observed between the initial and final samples at the phylum level.

CONCLUSION

Breastfeeding is associated with a decrease in Alphaproteobacteria and Betaproteobacteria and an increase of Gammaproteobacteria, contributing to the literature of the gut microbiota structure of very low-birth-weight, preterm.

Dynamic impact of delivery modes on gut microbiota in preterm infants hospitalized during the initial 4 weeks of life

Preterm infants face a high risk of various complications, and their gut microbiota plays a pivotal role in health. Delivery modes have been reported to affect the development of gut microbiota in term infants, but its impact on preterm infants remains unclear. Here, we collected fecal samples from 30 preterm infants at five-time points within the first four weeks of life. Employing 16 S rRNA sequencing, principal coordinates analysis, the analysis of similarities, and the Wilcoxon rank-sum test, we examined the top dominant phyla and genera, the temporal changes in specific taxa abundance, and their relationship with delivery modes, such as Escherichia-Shigella and Enterococcus based on vaginal delivery and Pluralibacter related to cesarean section. Moreover, we identified particular bacteria, such as Taonella, Patulibacter, and others, whose proportions fluctuated among preterm infants born via different delivery modes at varying time points, as well as the microbiota types and functions. These results indicated the influence of delivery mode on the composition and function of the preterm infant gut microbiota. Importantly, these effects are time-dependent during the early stages of life. These insights shed light on the pivotal role of delivery mode in shaping the gut microbiota of preterm infants and have significant clinical implications for their care and management.

Dietary Nucleotides Promote Neonatal Rat Microbiota-Gut-Brain Axis Development by Affecting Gut Microbiota Composition and Metabolic Function

A variety of active factors in milk and foods have been proven to serve as microbial nutrients that regulate the formation of early gut microbiota (GM), thereby ensuring the healthy development of infants. This study demonstrated that dietary nucleotides (NTs), one of the main nitrogen-containing substances in human milk, promoted the neurodevelopment of neonatal rats and the expression of Sox2, Dcx, Tuj1, and NeuN in the prefrontal cortex and hippocampus, but had no significant regulatory effects in the striatum. 16s rRNA sequencing and metabolomics of the colon contents of neonatal rats at different developmental stages showed that the early intake of NTs promoted an increase in the abundance of beneficial microorganisms related to neurodevelopment, digestion, and gut absorption, such as g_Romboutsia and g_Akkermansia. Changes in the ability of the GM to regulate folate synthesis, riboflavin metabolism, and other processes were also observed. Further analysis revealed significant correlations between the level of characteristic metabolites, namely, trans-3-indoleacrylic acid, urocanic acid, inosine, and adenosine, in the gut with neurodevelopment and characteristic GM components. These findings suggest that NTs in milk may affect neurodevelopment and maturation in early life by regulating the GM composition-gut-brain axis.

Dynamics and Crosstalk between Gut Microbiota, Metabolome, and Fecal Calprotectin in Very Preterm Infants: Insights into Feeding Intolerance

BACKGROUND

Feeding intolerance (FI) is a significant concern in the care of preterm infants, impacting their growth and development. We previously reported that FI is linked to lower fecal calprotectin (FC) levels. This study aims to explore the postnatal dynamics and interplay between microbiota, metabolic profiles, and host immunity in preterm infants with and without FI.

METHODS

Infants with gestational age <32 weeks or birth weight <1500 g were enrolled at the Children's Hospital of Fudan University between January 2018 and October 2020. Weekly fecal samples were analyzed for bacterial profiling, metabolome, and calprotectin levels, exploring their longitudinal development and interrelationships.

RESULTS

Of the 118 very preterm infants studied, 48 showed FI. These infants experienced an interrupted microbial-immune trajectory, particularly at 3-4 weeks of age, marked by a reduced bacterial abundance, alpha diversity, and FC levels. Metabolic changes in FI were pronounced between 3 and 6 weeks. Pantothenic acid and two polyamine metabolites were closely associated with bacterial abundance and FC levels and negatively correlated with the duration to attain full enteral feeding.

CONCLUSIONS

FI infants demonstrated compromised microbiome-immune interactions, potentially influenced by specific metabolites. This research underscored the importance of early microbial and metabolic development in the pathogenesis of FI in very preterm infants.

Early gut microbiota intervention in premature infants: Application perspectives

BACKGROUND

Preterm birth is the leading cause of death in children under the age of five. One of the major factors contributing to the high risk of diseases and deaths in premature infants is the incomplete development of the intestinal immune system. The gut microbiota has been widely recognized as a critical factor in promoting the development and function of the intestinal immune system after birth. However, the gut microbiota of premature infants is at high risk of dysbiosis, which is highly associated with adverse effects on the development and education of the early life immune system. Early intervention can modulate the colonization and development of gut microbiota and has a long-term influence on the development of the intestinal immune system.

AIM OF REVIEW

This review aims to summarize the characterization, interconnection, and underlying mechanism of gut microbiota and intestinal innate immunity in premature infants, and to discuss the status, applicability, safety, and prospects of different intervention strategies in premature infants, thus providing an overview and outlook of the current applications and remaining gaps of early intervention strategies in premature infants.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review is focused on three key concepts. Firstly, the gut microbiota of premature infants is at high risk of dysbiosis, resulting in dysfunctional intestinal immune system processes. Secondly, contributing roles of early intervention have been observed in improving the intestinal environment and promoting gut microbiota colonization, which is significant in the development and function of gut immunity in premature infants. Thirdly, different strategies of early intervention, such as probiotics, fecal microbiota transplantation, and nutrients, show different safety, applicability, and outcome in premature infants, and the underlying mechanism is complex and poorly understood.

Metabolomics Analysis Reveals the Potential Relationship Between Sow Colostrum and Neonatal Serum Metabolites in Different Pig Breeds

SCOPE

Colostrum composition is an important indicator of newborn piglet survival and growth. However, limited information is available on the association between colostrum metabolites in sows and serum metabolites in neonates. Therefore, the present study aims to determine the metabolites in the colostrum of sows, in the serum of their offspring piglets, and mother-offspring metabolite correlations in different pig breeds.

METHODS AND RESULTS

Colostrum and serum samples are collected from 30 sows and their piglets from three pig breeds (Taoyuan black, TB; Xiangcun black, XB; and Duroc) to analyze the targeted metabolomics. This study identifies 191 metabolites in the colostrum of sows, including fatty acids, amino acids, bile acids, carnitines, carbohydrates, and organic acids, and the concentrations of these metabolites are highest in the TB pigs. Metabolite profiles in sow colostrum and piglet serum differ among Duroc, TB, and XB pigs, and the matching metabolites are mainly enriched in the digestive system and transportation pathways. Furthermore, identification of the associations between metabolites in the colostrum of sows and their neonate sera suggests that metabolite compounds from colostrum are transported to suckling piglets.

CONCLUSION

The present study findings deepen the understanding of the composition of sow colostrum metabolites and the transportation of metabolites from sow colostrum to piglets. The findings also provide insight regarding the development of dietary formulas that resemble the sow colostrum for newborn animals to maintain health and improve the early growth of offspring.

Pre- and Postnatal Determinants Shaping the Microbiome of the Newborn in the Opinion of Pregnant Women from Silesia (Poland)

Pre- and postnatal factors influence the formation of the newborn's microbiome as early as birth and the intrauterine period has a substantial impact on the composition of the baby's gastrointestinal microbiota and its subsequent development. This study intends to measure pregnant women's knowledge of the importance of microbiota for the health of the newborn. The sample was selected based on defined inclusion and exclusion criteria. The assessment of women's knowledge was assessed by the Kolmogorov-Smirnov and Kruskal-Wallis statistical tests. This study population comprised 291 adult pregnant women with a mean age of 28.4 ± 4.7 years. A total of 34% (n = 99), 35% (n = 101), and 31.3% (n = 91) were at the 1-3 trimester, respectively. The results showed that 36.4% of the women were aware that the intrauterine period changes the makeup of the gastrointestinal microbiota, whereas 5.8% exhibited awareness of the composition of the child's normal gut microbiota. Most of the women surveyed-(72.1%)-know that colonization of the tract occurs as early as the birth period. Women with student status (those who will pursue higher education in the future) and those who had given birth to the most children exhibited higher levels of knowledge.

Fecal Calprotectin Levels Dynamics in Newborns with High-Risk of Necrotizing Enterocolitis

Background. Necrotizing enterocolitis (NEC) is severe gastrointestinal disease in newborns, its early clinical symptoms are nonspecific. Fecal сalprotectin (Cp) is considered as one of the early biomarkers of NEC, thus, its use in newborns is poorly known.

Objective. The aim of the study is to evaluate clinical significance of fecal Cp measuring as an early NEC marker in newborns. Methods. The prospective cohort observational study included high-risk newborns (gestational age (GA) ˂ 33 weeks and/or body weight ˂ 1500 g) and moderate risk newborns (GV≥ 33 weeks at suspicion on NEC) of NEC admitted to the neonatal intensive care unit on the 1st day of life. The Cp level was studied via immune colorimetric method on the 3rd and 7th days of life in high-risk children and in all children at NEC manifestation. All patients were divided into 2 main subgroups after the end of the follow-up period: newborns with developed NEC (a) and children without NEC (b). Obtained Cp values were compared between these subgroups.

Results. There were no statistically significant differences in Cp levels at the 3rd and 7th days of life in the high-risk group of children with NEC and without NEC. However, it was noted that children without NEC showed a decrease in Cp levels on the 7th day, while children with NEC manifestation, indeed, had increased levels. Cp levels did not differ in the moderate risk group.

Conclusion. Single measurement of Cp level in newborns of any GA is uninformative towards the NEC prognosis and diagnosis. However, evaluation of the Cp level dynamics at the 7th day of life compared to the 3rd day of life may be considered as a promising non-invasive method for prognosis of NEC manifestation in premature infants (GA<33 weeks). 

The Association between Prematurity, Antibiotic Consumption, and Mother-Infant Attachment in the First Year of Life

Antibiotics have individual and public-health drawbacks. Nevertheless, mother-infant attachment quality and maternal sensitivity are associated with antibiotic use. Ambivalent-attached infants are more likely to consume antibiotics than other infants. Conceivably, the emotional over-externalization of ambivalent-attached infants and maternal anxiety when infants are ill raise concerns in healthcare professionals, leading to antibiotic over-prescriptions. However, because infants prematurely born, particularly those with less than 32 weeks of gestation, are under more accurate health vigilance, the impact of infant and maternal behavior on antibiotic prescription may vanish in this sample. To test this hypothesis, we performed a longitudinal study to compare antibiotic use and the quality of mother-infant attachment in three groups: 86 infants born at full-term, 44 moderate-to-late preterm infants (32-36 gestation weeks), and 58 very-to-extreme preterm infants (<32 gestation weeks). Infants' attachment was observed with the Ainsworth Strange Situation's experimental paradigm at 12 months of corrected age. Findings indicate that infant attachment strategy is associated with antibiotics uptake, but results vary across samples. The proportion of infants that used antibiotics is highest among ambivalent-attached infants in the full-term sample but highest among avoidant-attached infants in the very-to-extreme premature sample. Moreover, higher infant gestational age and lower maternal sensitivity determine higher antibiotic use.

Lactobacillus rhamnosus GG colonization in early life regulates gut-brain axis and relieves anxiety-like behavior in adulthood

Evidence reveals that gut dysbiosis is involved in bidirectional interactions in gut-brain axis and participates in the progress of multiple disorders like anxiety. Gut microbes in early life are crucial for establishment of host health. We aimed to investigate whether early life probiotics Lactobacillus rhamnosus GG (LGG) colonization could relieve anxiety in adulthood through regulation of gut-brain axis. Live or fixed LGG was gavaged to C57BL/6 female mice from day 18 of pregnancy until natural birth, and newborn mice from day 1 to day 5 respectively. In this study, we found that live LGG could be effectively colonized in the intestine of offspring. LGG colonization increased intestinal villus length and colonic crypt depth, accompanied with barrier function protection before weaning. Microbiota composition by 16S rRNA sequencing showed that some beneficial bacteria, such as Akkermansia and Bifidobacteria, were abundant in LGG colonization group. The protective effect of LGG on gut microbiota persisted from weaning to adulthood. Intriguingly, behavioral results assessed by elevated plus mazed test and open field test demonstrated relief of anxiety-like behavior in adult LGG-colonized offspring. Mechanically, LGG colonization activated epithelial growth factor receptor (EGFR) and enhanced serotonin transporter (SERT) expression and modulated serotonergic system in the intestine, and increased brain-derived neurotrophic factor and γ-aminobutyric acid receptor levels in the hippocampus and amygdala. Blocking EGFR blunted LGG-induced the increased SERT and zonula occludens-1 expression. Collectively, early life LGG colonization could protect intestinal barrier of offspring and modulate gut-brain axis in association with relief of anxiety-like behavior in adulthood.

Necrotizing enterocolitis: Bench to bedside approaches and advancing our understanding of disease pathogenesis

Necrotizing enterocolitis (NEC) is a devastating, multifactorial disease mainly affecting the intestine of premature infants. Recent discoveries have significantly enhanced our understanding of risk factors, as well as, cellular and genetic mechanisms of this complex disease. Despite these advancements, no essential, single risk factor, nor the mechanism by which each risk factor affects NEC has been elucidated. Nonetheless, recent research indicates that maternal factors, antibiotic exposure, feeding, hypoxia, and altered gut microbiota pose a threat to the underdeveloped immunity of preterm infants. Here we review predisposing factors, status of unwarranted immune responses, and microbial pathogenesis in NEC based on currently available scientific evidence. We additionally discuss novel techniques and models used to study NEC and how this research translates from the bench to the bedside into potential treatment strategies.