Determinants of the lung microbiome in intubated premature infants at risk for bronchopulmonary dysplasia

Intestinal microbiota development in the first week of life of preterm newborns

OBJECTIVE

This study aimed to evaluate the intestinal microbiota development in the first week of life of preterm newborns (PTNB) treated at a public hospital in a municipality in the Brazilian Northeast.

METHODS

This is an observational, longitudinal, and descriptive study with 23 PTNBs. Two stool samples were collected from each neonate (fasting/meconium and seventh day of life) for stool microbiota analysis by 16S rRNA gene sequencing. The authors analyzed alpha diversity (Chao1, Shannon, and Simpson indices) and principal coordinates of beta diversity.

RESULTS

Forty-six stool samples from 23 PTNBs were analyzed at the taxonomic level. Microbiota's development was dynamic with low diversity. The authors observed a statistical association with the genera Enterobacterales, Streptococcus, Bacteroides, Clostridium_sensu_stricto_1, Enterococcus, and Bifidobacterium in the fasting samples when compared to the day-7 samples. The genus Staphylococcus also dominated at both times.

CONCLUSION

Dynamics were observed in the intestinal microbiota development, with an alpha diversity decrease in the stool samples collected at fasting/meconium and on the seventh day of life.

The neonate respiratory microbiome

Over the past two decades, it has become clear that against earlier assumptions, the respiratory tract is regularly populated by a variety of microbiota even down to the lowest parts of the lungs. New methods and technologies revealed distinct microbiome compositions and developmental trajectories in the differing parts of the respiratory tract of neonates and infants. In this review, we describe the current understanding of respiratory microbiota development in human neonates and highlight multiple factors that have been identified to impact human respiratory microbiome development including gestational age, mode of delivery, diet, antibiotic treatment, and early infections. Moreover, we discuss to date revealed respiratory microbiome-disease associations in infants and children that may indicate a potentially imprinting cross talk between microbial communities and the host immune system in the respiratory tract. It becomes obvious how insufficient our knowledge still is regarding the exact mechanisms underlying such cross talk in humans. Lastly, we highlight strong findings that emphasize the important role of the gut-lung axis in educating and driving pulmonary immunity. Further research is needed to better understand the host - respiratory microbiome interaction in order to enable the translation into microbiome-based strategies to protect and improve human respiratory health from early childhood.

The lower airway microbiome in paediatric health and chronic disease

The advent of next generation sequencing has rapidly challenged the paediatric respiratory physician's understanding of lung microbiology and the role of the lung microbiome in host health and disease. In particular, the role of "microbial key players" in paediatric respiratory disease is yet to be fully explained. Accurate profiling of the lung microbiome in children is challenging since the ability to obtain lower airway samples coupled with processing "low-biomass specimens" are both technically difficult. Many studies provide conflicting results. Early microbiota-host relationships may be predictive of the development of chronic respiratory disease but attempts to correlate lower airway microbiota in premature infants and risk of developing bronchopulmonary dysplasia (BPD) have produced mixed results. There are differences in lung microbiota in asthma and cystic fibrosis (CF). The increased abundance of oral taxa in the lungs may (or may not) promote disease processes in asthma and CF. In CF, correlation between microbiota diversity and respiratory decline is commonly observed. When one considers other pathogens beyond the bacterial kingdom, the contribution and interplay of fungi and viruses within the lung microbiome further increase complexity. Similarly, the interaction between microbial communities in different body sites, such as the gut-lung axis, and the influence of environmental factors, including diet, make the co-existence of host and microbes ever more complicated. Future, multi-omics approaches may help uncover novel microbiome-based biomarkers and therapeutic targets in respiratory disease and explain how we can live in harmony with our microbial companions.

Association of toll-like receptors with the airway-intestinal microbiota and pneumonia development in preterm infants - A case control study

BACKGROUND

The prevention and treatment of pneumonia and lung injury in preterm infants are major challenges for pediatricians worldwide. Few studies have analyzed the composition of bacterial colonies in the airway and intestine and their relationship with toll-like receptors (TLRs) as it relates to pneumonia in preterm infants.

METHODS

This study included 70 infants born at 32-35 weeks gestation. Oral-tracheal aspirates at the time of birth, first-pass meconium, and serum specimens were collected. Bacterial deoxyribonucleic acid (DNA) was extracted from the Oral-tracheal aspirates and meconium, and 16S ribosomal ribonucleic acid (rRNA) genes were amplified and sequenced. The levels of TLR2 and TLR4 were analyzed using an enzyme-linked immunosorbent assay. Preterm infants were classified into non-pneumonia (A) and pneumonia (B) groups according to their clinical manifestations.

RESULTS

Significant differences in the alpha and beta diversities were observed between the two groups. Infants with pneumonia had less bacterial diversity in the airways and intestinal flora at birth than those without pneumonia. The three most predominant phyla in the airways at birth were Proteobacteria, Firmicutes, and Actinobacteria. The levels of TLR2 and TLR4 in oral-tracheal aspirates were higher in infants with pneumonia than in those without pneumonia, although serum TLR2 and TLR4 levels did not differ between the groups. Streptococcus in the oral tracheal aspirate was negatively correlated with TLR2 and TLR4 levels, and Ureaplasma in the oral-tracheal aspirate was negatively correlated with TLR4 levels in the airway.

CONCLUSION

Reduced perinatal microbiota diversity is associated with the levels of TLR2 and TLR4, and may also have a significant impact on the development of pneumonia.

The age-specific microbiome of children with milk, egg, and peanut allergy

BACKGROUND

Immune regulation by gut microbiota is affected by dysbiosis and may precede food allergy onset. Prior studies lacked comparisons stratified by age and clinical phenotype.

OBJECTIVE

To assess the microbiome of children with food allergy (<3 years, 3-18 years) compared with similar aged children without food allergy.

METHODS

A real-world prospective cross-sectional study performed from 2014 to 2019 recruited children highly likely to have milk, egg, or peanut allergy defined by history and serum IgE or confirmed by food challenge. 16S ribosomal RNA sequencing identified stool microbial DNA. Alpha and beta diversity was compared between groups with food allergy and healthy controls stratified by age. Differential abundance for non a priori taxa was accepted at absolute fold-change greater than 2 and q value less than 0.05.

RESULTS

A total of 70 patients were included (56 with food allergy and 14 healthy controls). Groups were not significantly different in age, gender at birth, race, mode of delivery, breastfeeding duration, or antibiotic exposure. Younger children with food allergy had similar alpha diversity compared with controls. Beta diversity was significantly different by age (P = .001). There was differential abundance of several a priori (P < .05) taxa (including Clostridia) only in younger children. Both a priori (including Coprococcus and Clostridia) and non a priori (q < 0.05) Acidobacteria_Gp15, Aestuariispira, Tindallia, and Desulfitispora were significant in older children with food allergy, especially with peanut allergy.

CONCLUSION

Dysbiosis associates with food allergy, most prominent in older children with peanut allergy. Younger children with and without food allergy have fewer differences in gut microbiota. This correlates with clinical observations of persistence of peanut allergy and improved efficacy and safety of oral immunotherapy in younger children. Age younger than 3 years should be considered when initiating therapeutic interventions.

A Scoping Review of the Oral Microbiome in Preterm Infants

The purpose of this scoping review was to examine the oral microbiome composition in preterm infants, sampling and collection methods, as well as exposures associated with oral microbiome composition and health implications. We conducted a scoping review of the literature using the Arskey and O'Malley framework. We identified a total of 13 articles which met our inclusion criteria and purpose of this scoping review. Articles included in this review compared the oral microbiome in preterm infants to term infants, examined alterations to the oral microbiome over time, compared the oral microbiome to different body site microbiomes, and explored associations with clinically relevant covariates and outcomes. Exposures associated with the diversity and composition of the oral microbiome in preterm infants included delivery mode, oral feeding, oropharyngeal care, skin-to-skin care, and antibiotics. Day of life and birth weight were also associated with oral microbiome composition. The oral microbiome may be associated with the composition of the tracheal and gut microbiomes, likely due to their proximity. Alpha and beta diversity findings varied across studies as well as the relative abundance of taxa. This is likely due to the different sampling techniques and timing of collection, as well as the wide range of infant clinical characteristics. Multiple factors may influence the composition of the oral microbiome in preterm infants. However, given the heterogeneity of sampling techniques and results within this review, the evidence is not conclusive on the development as well as short- and long-term implications of the oral microbiome in preterm infants and needs to be explored in future research studies. KEY POINTS: · Day of life is a critical factor in oral microbiome development in preterm infants.. · The oral microbiome may be associated with tracheal and gut microbiome colonization.. · Future research should examine sampling methodology for examining the oral microbiome.. · Future research should explore associations with the oral microbiome and adverse health outcomes..

Preterm Infants' Airway Microbiome: A Scoping Review of the Current Evidence

The aim of this scoping review was to investigate and synthesize existing evidence on the airway microbiome of preterm infants to outline the prognostic and therapeutic significance of these microbiomes within the preterm population and identify gaps in current knowledge, proposing avenues for future research. We performed a scoping review of the literature following the Arskey and O'Malley framework. In accordance with our inclusion criteria and the intended purpose of this scoping review, we identified a total of 21 articles. The investigation of the airway microbiome in preterm infants has revealed new insights into its unique characteristics, highlighting distinct dynamics when compared to term infants. Perinatal factors, such as the mode of delivery, chorioamnionitis, the respiratory support, and antibiotic treatment, could impact the composition of the airway microbiome. The 'gut-lung axis', examining the link between the lung and gut microbiome as well as modifications in respiratory microbiome across different sites and over time, has also been explored. Furthermore, correlations between the airway microbiome and adverse outcomes, such as bronchopulmonary dysplasia (BPD), have been established. Additional research in neonatal care is essential to understand the early colonization of infants' airways and explore methods for its optimization. The critical opportunity to shape long-term health through microbiome-mediated effects likely lies within the neonatal period.

Big Data for Tiny Patients: A Precision Medicine Approach to Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is the most common chronic lung disease of extreme prematurity. Despite more than 50 years of research, current treatments are ineffective, and clinicians are largely unable to accurately predict which neonates the condition will develop in. A deeper understanding of the molecular mechanisms underlying the characteristic arrest in lung development are warranted. Integrating high-fidelity technology from precision medicine approaches may fill this gap and provide the tools necessary to identify biomarkers and targetable pathways. In this review, we describe insights garnered from current studies using omics for BPD prediction and stratification. We conclude by describing novel programs that will integrate multi-omics in efforts to better understand and treat the pathogenesis of BPD. [Pediatr Ann. 2022;51(10):e396-e404.].