Intestinal microbiota in allergic and nonallergic 1-year-old very low birth weight infants after neonatal glutamine supplementation

The Role of the Microbiome in Allergy, Asthma, and Occupational Lung Disease

PURPOSE OF REVIEW

The human commensal microbiota is now widely accepted as a key regulator of human health and disease. The composition of the mucosal associated microbiota has been shown to play a critical role in the lung health. The role of the mucosal microbiota in the development and severity of allergy, asthma, and occupational lung disease is only beginning to take shape. However, advances in our understanding of these links have tremendous potential to led to new clinical interventions to reduce allergy, asthma, and occupational lung disease morbidity.

RECENT FINDINGS

We review recent work describing the relationship and role of the commensal microbiota in the development of allergy, asthma, and occupational lung disease. Our review primarily focuses on occupational exposures and the effects of the microbiome, both in composition and function. Data generated from these studies may lead to the development of interventions targeted at establishing and maintaining a healthy microbiota. We also highlight the role of environmental exposures and the effects on the commensal microbial community and their potential association with occupational lung disease. This review explores the current research describing the role of the human microbiome in the regulation of pulmonary health and disease, with a specific focus on the role of the mucosal microbiota in the development of allergy, asthma, and occupational lung disease.

Nutritional Interventions and the Gut Microbiome in Children

The gut microbiome plays an integral role in health and disease, and diet is a major driver of its composition, diversity, and functional capacity. Given the dynamic development of the gut microbiome in infants and children, it is critical to address two major questions: (a) Can diet modify the composition, diversity, or function of the gut microbiome, and (b) will such modification affect functional/clinical outcomes including immune function, cognitive development, and overall health? We synthesize the evidence on the effect of nutritional interventions on the gut microbiome in infants and children across 26 studies. Findings indicate the need to study older children, assess the whole intestinal tract, and harmonize methods and interpretation of findings, which are critical for informing meaningful clinical and public health practice. These findings are relevant for precision health, may help identify windows of opportunity for intervention, and may inform the design and delivery of such interventions. Expected final online publication date for the Annual Review of Nutrition, Volume 41 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Administration of β-lactam antibiotics and delivery method correlate with intestinal abundances of Bifidobacteria and Bacteroides in early infancy, in Japan

The intestinal microbiome changes dynamically in early infancy. Colonisation by Bifidobacterium and Bacteroides and development of intestinal immunity is interconnected. We performed a prospective observational cohort study to determine the influence of antibiotics taken by the mother immediately before delivery on the intestinal microbiome of 130 healthy Japanese infants. Faecal samples (383) were collected at 1, 3, and 6 months and analysed using next-generation sequencing. Cefazolin was administered before caesarean sections, whereas ampicillin was administered in cases with premature rupture of the membranes and in Group B Streptococcus-positive cases. Bifidobacterium and Bacteroides were dominant (60–70% mean combined occupancy) at all ages. A low abundance of Bifidobacterium was observed in infants exposed to antibiotics at delivery and at 1 and 3 months, with no difference between delivery methods. A lower abundance of Bacteroides was observed after caesarean section than vaginal delivery, irrespective of antibiotic exposure. Additionally, occupancy by Bifidobacterium at 1 and 3 months and by Bacteroides at 3 months differed between infants with and without siblings. All these differences disappeared at 6 months. Infants exposed to intrapartum antibiotics displayed altered Bifidobacterium abundance, whereas abundance of Bacteroides was largely associated with the delivery method. Existence of siblings also significantly influenced the microbiota composition of infants.

The Role of Glutamine in the Complex Interaction between Gut Microbiota and Health: A Narrative Review

The scientific literature has demonstrated that glutamine is one of the main beneficial amino acids. It plays an important role in gut microbiota and immunity. This paper provides a critical overview of experimental studies (in vitro, in vivo, and clinical) investigating the efficacy of glutamine and its effect on gut microbiota. As a result of this review, we have summarized that glutamine could affect gut microbiota via different mechanisms including the reduction in the ratio of Firmicutes to Bacteroidetes, with the activation of NF-κB and PI3K-Akt pathways, reducing the intestinal colonization (Eimeria lesions) and bacterial overgrowth or bacterial translocation, increasing the production of secretory immunoglobulin A (SIgA) and immunoglobulin A+ (IgA+) cells in the intestinal lumen, and decreasing asparagine levels. The potential applications of glutamine on gut microbiota include, but are not limited to, the management of obesity, bacterial translocation and community, cytokines profiles, and the management of side effects during post-chemotherapy and constipation periods. Further studies and reviews are needed regarding the effects of glutamine supplementation on other conditions in humans.

Cow's Milk Allergy: Immunomodulation by Dietary Intervention

Cow’s milk proteins cause allergic symptoms in 2% to 3% of all infants. In these individuals, the physiological mechanism of tolerance is broken with subsequent possible sensitization to antigens, which can lead eventually to allergic responses. The present review aims to provide an overview of different aspects of immune modulation by dietary intervention in cow’s milk allergy (CMA). It focuses on pathogenetic mechanisms of different CMA related disorders, e.g., gastroesophageal reflux and eosinophilic esophagitis, highlighting the role of dietary management on innate and adaptive immune systems. The traditional dietary management of CMA has greatly changed in the last years, moving from a passive approach, consisting of an elimination diet to relieve symptoms, to a “proactive” one, meaning the possibility to actively modulate the immune system. Thus, new insights into the role of hydrolysates and baked milk in immunomodulation are addressed here. Additionally, nutritional components, such as pre- and probiotics, may target the immune system via microbiota, offering a possible road map for new CMA prevention and treatment strategies.

Rationale of Probiotic Supplementation during Pregnancy and Neonatal Period

Probiotics are living microorganisms that confer a health benefit when administered in adequate amounts. It has been speculated that probiotics supplementation during pregnancy and in the neonatal period might reduce some maternal and neonatal adverse outcomes. In this narrative review, we describe the rationale behind probiotic supplementation and its possible role in preventing preterm delivery, perinatal infections, functional gastrointestinal diseases, and atopic disorders during early life.

Maternal antimicrobial use at delivery has a stronger impact than mode of delivery on bifidobacterial colonization in infants: a pilot study

OBJECTIVE

To investigate factors related to bifidobacterial colonization in early infancy, with a focus on maternal antimicrobial use at delivery.

STUDY DESIGN

A cross-sectional pilot study was performed. Feces samples of 33 Japanese healthy infants were collected over 10 months and analyzed by next-generation sequencing to examine the diversity and abundance of the gut microbiota.

RESULTS

The beta diversity index of the gut microbiota differed significantly based on maternal antimicrobial use at delivery (P < 0.05). The most dominant genus was bifidobacteria, and the relative abundance of bifidobacteria in infants exposed to maternal antibiotics was significantly lower than in those who were not exposed (P < 0.05). In contrast, the delivery mode showed no significant relationship with gut microbiota diversity.

CONCLUSIONS

Maternal antimicrobial use at delivery has a stronger effect than delivery mode on the gut microbiota, especially for colonization of bifidobacteria.

Intestinal microbiota and allergic diseases: A systematic review

Evidence suggests that possible imbalances in intestinal microbiota composition may be implicated in the occurrence of allergic diseases. Although several studies published until 2006 indicated a correlation between microbiota composition and allergic symptoms, it has not been possible to distinguish protective microorganisms from those associated with increased risk of allergic diseases. Therefore, the objective of this study was to review the studies published since 2007 that address the intestinal microbiota in allergic diseases. Twenty-one studies were identified after excluding those that performed a clinical intervention before stool collection. In the early microbiota of children who later developed allergies, lower bacterial diversity was observed, with a predominance of Firmicutes; a higher count of Bacteroidaceae; a higher prevalence of the anaerobic bacteria Bacteroides fragilis, Escherichia coli, Clostridium difficile, Bifidobacterium catenulatum, Bifidobacterium bifidum, and Bifidobacterium longum; and a lower prevalence of Bifidobacterium adolescentis, B. bifidum, and Lactobacillus. In the microbiota of allergic children whose intestinal microbiota was assessed at the onset of allergic symptoms, there was a higher count of Bacteroides; a lower count of Akkermansia muciniphila, Faecalibacterium prausnitzii, and Clostridium; a higher prevalence of B. adolescentis; a lower prevalence of B. catenulatum and Staphylococcus aureus; and a lower bacterial diversity.

The first thousand days - intestinal microbiology of early life: establishing a symbiosis

The development of the intestinal microbiota in the first years of life is a dynamic process significantly influenced by early-life nutrition. Pioneer bacteria colonizing the infant intestinal tract and the gradual diversification to a stable climax ecosystem plays a crucial role in establishing host-microbe interactions essential for optimal symbiosis. This colonization process and establishment of symbiosis may profoundly influence health throughout life. Recent developments in microbiologic cultivation-independent methods allow a detailed view of the key players and factors involved in this process and may further elucidate their roles in a healthy gut and immune maturation. Aberrant patterns may lead to identifying key microbial signatures involved in developing immunologic diseases into adulthood, such as asthma and atopic diseases. The central role of early-life nutrition in the developmental human microbiota, immunity, and metabolism offers promising strategies for prevention and treatment of such diseases. This review provides an overview of the development of the intestinal microbiota, its bidirectional relationship with the immune system, and its role in impacting health and disease, with emphasis on allergy, in early life.

Effect of non-human neutral and acidic oligosaccharides on allergic and infectious diseases in preterm infants

Short-term supplementation of non-human neutral and acidic oligosaccharides during the first postnatal weeks may enhance the maturation of the immune response in preterm infants and may lead to less allergic and infectious diseases during the first year of life. In a randomized controlled trial, 113 preterm infants (gestational age <32 weeks and/or birth weight <1500 g) were allocated to receive enteral neutral and acidic oligosaccharide supplementation or placebo between days 3 and 30 of life. The median age at follow-up was not different in both groups: 12 months corrected age (interquartile range [IQR], 11-15) in the prebiotic mixture group and 12 months corrected age in the placebo group (IQR, 10-19), respectively. In addition, baseline patient, maternal, and environmental characteristics were not different between the prebiotic mixture (n = 48) and placebo (n = 46) group. Incidence of allergic and infectious diseases was assessed by validated questionnaires. In total, 94/98 (96 %) of the eligible, surviving infants participated in this follow-up study. The incidence of atopic dermatitis (odds ratio [OR], 0.80; 95 % confidence interval [CI], 0.24-2.67), bronchial hyper-reactivity (OR, 1.04; 95 % CI, 0.38-2.87) and infections of the upper respiratory (OR, 0.95; 95 % CI, 0.37-2.44), lower respiratory (OR, 1.03; 95 % CI, 0.37-2.88), and gastrointestinal (OR, 1.77; 95 % CI, 0.55-5.73) tract was not different between the groups. Adjustment for potential confounding factors did not change the results of the primary analysis.

CONCLUSION

Short-term enteral supplementation of non-human neutral and acidic oligosaccharides during the neonatal period in preterm infants does not decrease the incidence of allergic and infectious diseases during the first year of life.

Glutamine randomized studies in early life: the unsolved riddle of experimental and clinical studies

Glutamine may have benefits during immaturity or critical illness in early life but its effects on outcome end hardpoints are controversial. Our aim was to review randomized studies on glutamine supplementation in pups, infants, and children examining whether glutamine affects outcome. Experimental work has proposed various mechanisms of glutamine action but none of the randomized studies in early life showed any effect on mortality and only a few showed some effect on inflammatory response, organ function, and a trend for infection control. Although apparently safe in animal models (pups), premature infants, and critically ill children, glutamine supplementation does not reduce mortality or late onset sepsis, and its routine use cannot be recommended in these sensitive populations. Large prospectively stratified trials are needed to better define the crucial interrelations of “glutamine-heat shock proteins-stress response” in critical illness and to identify the specific subgroups of premature neonates and critically ill infants or children who may have a greater need for glutamine and who may eventually benefit from its supplementation. The methodological problems noted in the reviewed randomized experimental and clinical trials should be seriously considered in any future well-designed large blinded randomized controlled trial involving glutamine supplementation in critical illness.

Glutamine supplementation in sick children: is it beneficial?

The purpose of this review is to provide a critical appraisal of the literature on Glutamine (Gln) supplementation in various conditions or illnesses that affect children, from neonates to adolescents. First, a general overview of the proposed mechanisms for the beneficial effects of Gln is provided, and subsequently clinical studies are discussed. Despite safety, studies are conflicting, partly due to different effects of enteral and parenteral Gln supplementation. Further insufficient evidence is available on the benefits of Gln supplementation in pediatric patients. This includes premature infants, infants with gastrointestinal disease, children with Crohn's disease, short bowel syndrome, malnutrition/diarrhea, cancer, severe burns/trauma, Duchenne muscular dystrophy, sickle cell anemia, cystic fibrosis, and type 1 diabetes. Moreover, methodological issues have been noted in some studies. Further mechanistic data is needed along with large randomized controlled trials in select populations of sick children, who may eventually benefit from supplemental Gln.