Cesarean section changes neonatal gut colonization

Early life microbiome influences on development of the mucosal innate immune system

The gut microbiota is well known to possess immunomodulatory capacities, influencing a multitude of cellular signalling pathways to maintain host homeostasis. Although the formation of the immune system initiates before birth in a sterile environment, an emerging body of literature indicates that the neonatal immune system is influenced by a first wave of external stimuli that includes signals from the maternal microbiota. A second wave of stimulus begins after birth and must be tightly regulated during the neonatal period when colonization of the host occurs concomitantly with the maturation of the immune system, requiring a fine adjustment between establishing tolerance towards the commensal microbiota and preserving inflammatory responses against pathogenic invaders. Besides integrating cues from commensal microbes, the neonatal immune system must also regulate responses triggered by other environmental signals, such as dietary antigens, which become more complex with the introduction of solid food during the weaning period. This "window of opportunity" in early life is thought to be crucial for the proper development of the immune system, setting the tone of subsequent immune responses in adulthood and modulating the risk of developing chronic and metabolic inflammatory diseases. Here we review the importance of host-microbiota interactions for the development and maturation of the immune system, particularly in the early-life period, highlighting the known mechanisms involved in such communication. This discussion is focused on recent data demonstrating microbiota-mediated education of innate immune cells and its role in the development of lymphoid tissues.

Probiotics in the New Era of Human Milk Oligosaccharides (HMOs): HMO Utilization and Beneficial Effects of Bifidobacterium longum subsp. infantis M-63 on Infant Health

A healthy gut microbiome is crucial for the immune system and overall development of infants. Bifidobacterium has been known to be a predominant species in the infant gut; however, an emerging concern is the apparent loss of this genus, in particular, Bifidobacterium longum subsp. infantis (B. infantis) in the gut microbiome of infants in industrialized nations, underscoring the importance of restoring this beneficial bacterium. With the growing understanding of the gut microbiome, probiotics, especially infant-type human-residential bifidobacteria (HRB) strains like B. infantis, are gaining prominence for their unique ability to utilize HMOs and positively influence infant health. This article delves into the physiology of a probiotic strain, B. infantis M-63, its symbiotic relationship with HMOs, and its potential in improving gastrointestinal and allergic conditions in infants and children. Moreover, this article critically assesses the role of HMOs and the emerging trend of supplementing infant formulas with the prebiotic HMOs, which serve as fuel for beneficial gut bacteria, thereby emulating the protective effects of breastfeeding. The review highlights the potential of combining B. infantis M-63 with HMOs as a feasible strategy to improve health outcomes in infants and children, acknowledging the complexities and requirements for further research in this area.

Pre-labor and post-labor cesarean delivery and early childhood adiposity in the Canadian Healthy Infant Longitudinal Development (CHILD) Cohort Study

BACKGROUND/OBJECTIVES

Delivery by cesarean section (CS) compared to vaginal delivery has been associated with increased risk of overweight in childhood. Our study examined if the presence or absence of labor events in CS delivery altered risk of overweight in early childhood (1-5 years) compared to vaginal delivery and if this association differed according to infant sex.

SUBJECTS/METHODS

The study included 3073 mother-infant pairs from the CHILD Cohort Study in Canada. Data from birth records were used to categorize infants as having been vaginally delivered, or delivered by CS, with or without labor events. Age and sex adjusted weight-for-length (WFL) and body mass index (BMI) z scores were calculated from height and weight data from clinic visits at 1, 3 and 5 years and used to classify children as overweight. Associations between delivery mode and child overweight at each timepoint were assessed using regression models, adjusting for relevant confounding factors including maternal pre-pregnancy BMI. Effect modification by infant sex was tested.

RESULTS

One in four infants (24.6%) were born by CS delivery; 13.0% involved labor events and 11.6% did not. Infants born by CS without labor had an increased odds of being overweight at age 1 year compared to vaginally delivered infants after adjustment for maternal pre-pregnancy BMI, maternal diabetes, smoking, infant sex and birthweight-for-gestational age (aOR 1.68 [95% CI 1.05-2.67]). These effects did not persist to 3 or 5 years of age and, after stratification by sex, were only seen in boys (aOR at 1 year 2.21 [95% CI 1.26-3.88]).

CONCLUSION AND RELEVANCE

Our findings add to the body of evidence that CS, in particular CS without labor events, may be a risk factor for overweight in early life, and that this association may be sex-specific. These findings could help to identify children at higher risk for developing obesity.

Clinical chorioamnionitis at term: definition, pathogenesis, microbiology, diagnosis, and treatment

Clinical chorioamnionitis, the most common infection-related diagnosis in labor and delivery units, is an antecedent of puerperal infection and neonatal sepsis. The condition is suspected when intrapartum fever is associated with two other maternal and fetal signs of local or systemic inflammation (eg, maternal tachycardia, uterine tenderness, maternal leukocytosis, malodorous vaginal discharge or amniotic fluid, and fetal tachycardia). Clinical chorioamnionitis is a syndrome caused by intraamniotic infection, sterile intraamniotic inflammation (inflammation without bacteria), or systemic maternal inflammation induced by epidural analgesia. In cases of uncertainty, a definitive diagnosis can be made by analyzing amniotic fluid with methods to detect bacteria (Gram stain, culture, or microbial nucleic acid) and inflammation (white blood cell count, glucose concentration, interleukin-6, interleukin-8, matrix metalloproteinase-8). The most common microorganisms are Ureaplasma species, and polymicrobial infections occur in 70% of cases. The fetal attack rate is low, and the rate of positive neonatal blood cultures ranges between 0.2% and 4%. Intrapartum antibiotic administration is the standard treatment to reduce neonatal sepsis. Treatment with ampicillin and gentamicin have been recommended by professional societies, although other antibiotic regimens, eg, cephalosporins, have been used. Given the importance of Ureaplasma species as a cause of intraamniotic infection, consideration needs to be given to the administration of antimicrobial agents effective against these microorganisms such as azithromycin or clarithromycin. We have used the combination of ceftriaxone, clarithromycin, and metronidazole, which has been shown to eradicate intraamniotic infection with microbiologic studies. Routine testing of neonates born to affected mothers for genital mycoplasmas could improve the detection of neonatal sepsis. Clinical chorioamnionitis is associated with decreased uterine activity, failure to progress in labor, and postpartum hemorrhage; however, clinical chorioamnionitis by itself is not an indication for cesarean delivery. Oxytocin is often administered for labor augmentation, and it is prudent to have uterotonic agents at hand to manage postpartum hemorrhage. Infants born to mothers with clinical chorioamnionitis near term are at risk for early-onset neonatal sepsis and for long-term disability such as cerebral palsy. A frontier is the noninvasive assessment of amniotic fluid to diagnose intraamniotic inflammation with a transcervical amniotic fluid collector and a rapid bedside test for IL-8 for patients with ruptured membranes. This approach promises to improve diagnostic accuracy and to provide a basis for antimicrobial administration.

Inspecting mother-to-infant microbiota transmission: disturbance of strain inheritance by cesarian section

Introduction

The initial acquisition and subsequent development of the microbiota in early life is crucial to future health. Cesarean-section (CS) birth is considered to affect early microbial transmission from mother to infant.

Methods

In this study, we collected fecal samples from 34 CS infants and their mothers from West China Second Hospital, Sichuan University to assess the microbiota developmental trajectory of mothers and infants. We explored mother-infant gut microbiome transmission via comparison with corresponding Finnish data.

Results

Metagenomic analysis of gut microbiota profiles indicated that the communities of mothers and infants were distinct. The composition of the infant gut microbiome was highly variable but also followed predictable patterns in the early stages of life. Maternal communities were stable and mainly dominated by species from Bacteroidacea spp. We used PStrain to analyze and visualize strain transmission in each mother-infant pair. Excluding missing data, we included 32 mother-infant pairs for analysis of strain transmission. Most CS deliveries (65.6%, 21/32) did not demonstrate transmission of strains from mother to infant. To further explore the mother-infant strain transmission, we analyzed metagenomics data from Finnish mother-infant pairs. A total of 32 mother-infant pairs were included in the analysis, including 28 vaginal delivery (VD) infants and four CS infants. Strain transmission was observed in 30 infants, including 28 VD infants and two CS infants. All VD infants received transmitted stains from their mothers. Finally, a total of 193 strain transmission events were observed, comprising 131 strains and 45 species.

Discussion

Taken together, our data suggested that delivery mode was an important factor influencing the mother-infant strain transmission.

Association of cesarean section and infectious outcomes among infants at 1 year of age: Logistic regression analysis using data of 104,065 records from the Japan Environment and Children's Study

BACKGROUND

There has been a recent decrease in the prevalence of infectious diseases in children worldwide due to the usage of vaccines. However, the association between cesarean delivery and infectious diseases remains unclear. Here, we aimed to clarify the association between cesarean delivery and the development of infectious diseases.

METHODS

This study is a cross-sectional study. We used data from the Japan Environment and Children's Study, which is a prospective, nationwide, government-funded birth cohort study. The data of 104,065 records were included. Information about the mode of delivery, central nervous system infection (CNSI), otitis media (OM), upper respiratory tract infection (URTI), lower respiratory tract infection (LRTI), gastrointestinal infection (GI), and urinary tract infection (UTI) was obtained from questionnaires and medical records transcripts. Multiple logistic regression analysis was used to assess the association between cesarean delivery and CNSI, OM, URTI, LRTI, GI, and UTI risk.

RESULTS

We included a total of 74,477 subjects in this study, of which 18.4% underwent cesarean deliveries. After adjusting for the perinatal, socioeconomic, and postnatal confounding factors, children born by cesarean delivery did not have an increased risk of developing CNSI (95% confidence interval [CI] 0.46-1.35), OM (95% CI 0.99-1.12), URTI (95% CI 0.97-1.06), LRTI (95% CI 0.98-1.15), GI (95% CI 0.98-1.11), or UTI (95% CI 0.95-1.45).

CONCLUSIONS

This nationwide cohort study did not find an association between cesarean delivery and CNSI, OM, URTI, LRTI, GI, and UTI. However, further studies are needed to evaluate the role of cesarean delivery in the development of infectious diseases.

Exploring the Mechanistic Interplay between Gut Microbiota and Precocious Puberty: A Narrative Review

The gut microbiota has been implicated in the context of sexual maturation during puberty, with discernible differences in its composition before and after this critical developmental stage. Notably, there has been a global rise in the prevalence of precocious puberty in recent years, particularly among girls, where approximately 90% of central precocious puberty cases lack a clearly identifiable cause. While a link between precocious puberty and the gut microbiota has been observed, the precise causality and underlying mechanisms remain elusive. This narrative review aims to systematically elucidate the potential mechanisms that underlie the intricate relationship between the gut microbiota and precocious puberty. Potential avenues of exploration include investigating the impact of the gut microbiota on endocrine function, particularly in the regulation of hormones, such as gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH). Additionally, this review will delve into the intricate interplay between the gut microbiome, metabolism, and obesity, considering the known association between obesity and precocious puberty. This review will also explore how the microbiome's involvement in nutrient metabolism could impact precocious puberty. Finally, attention is given to the microbiota's ability to produce neurotransmitters and neuroactive compounds, potentially influencing the central nervous system components involved in regulating puberty. By exploring these mechanisms, this narrative review seeks to identify unexplored targets and emerging directions in understanding the role of the gut microbiome in relation to precocious puberty. The ultimate goal is to provide valuable insights for the development of non-invasive diagnostic methods and innovative therapeutic strategies for precocious puberty in the future, such as specific probiotic therapy.

Exploration of pathogenic microorganism within the small intestine of necrotizing enterocolitis

BACKGROUND

Necrotizing enterocolitis (NEC) is the most common severe gastrointestinal emergency in neonates. We designed this study to identify the pathogenic microorganisms of NEC in the microbiota of the small intestine of neonates.

METHODS

Using the 16S ribosomal DNA (rDNA) sequencing method, we compared and analyzed the structure and diversity of microbiotas in the intestinal feces of different groups of neonates: patients undergoing jejunostomy to treat NEC (NP group), neonates undergoing jejunostomy to treat other conditions (NN group), and neonates with NEC undergoing conservative treatment (NC group). We took intestinal feces and saliva samples from patients at different time points.

RESULTS

The beta diversities of the NP, NN, and NC groups were all similar. When comparing the beta diversities between different time points in the NP group, we found similar beta diversities at time points E1 to E3 but significant differences between the E2-E3 and E4 time points: the abundances of Klebsiella and Enterococcus (Proteobacteria) were higher at the E1-E3 time points; the abundance of Escherichia-Shigella (Proteobacteria) increased at the E2 time point, and the abundance of Klebsiella decreased significantly, whereas that of Streptococcus increased significantly at the E4 time point.

CONCLUSIONS

Our results suggest that the pathological changes of intestinal necrosis in the small intestine of infants with NEC are not directly caused by excessive proliferation of pathogenic bacteria in the small intestine. The sources of microbiota in the small intestine of neonates, especially in premature infants, may be affected by multiple factors.

Escherichia coli CRISPR arrays from early life fecal samples preferentially target prophages

CRISPR-Cas systems are defense mechanisms against phages and other nucleic acids that invade bacteria and archaea. In Escherichia coli, it is generally accepted that CRISPR-Cas systems are inactive in laboratory conditions due to a transcriptional repressor. In natural isolates, it has been shown that CRISPR arrays remain stable over the years and that most spacer targets (protospacers) remain unknown. Here, we re-examine CRISPR arrays in natural E. coli isolates and investigate viral and bacterial genomes for spacer targets using a bioinformatics approach coupled to a unique biological dataset. We first sequenced the CRISPR1 array of 1769 E. coli isolates from the fecal samples of 639 children obtained during their first year of life. We built a network with edges between isolates that reflect the number of shared spacers. The isolates grouped into 34 modules. A search for matching spacers in bacterial genomes showed that E. coli spacers almost exclusively target prophages. While we found instances of self-targeting spacers, those involving a prophage and a spacer within the same bacterial genome were rare. The extensive search for matching spacers also expanded the library of known E. coli protospacers to 60%. Altogether, these results favor the concept that E. coli's CRISPR-Cas is an antiprophage system and highlight the importance of reconsidering the criteria use to deem CRISPR-Cas systems active.

Long term respiratory morbidity of cesarean-delivered second twin compared to their vaginally-delivered sibling: A retrospective population-based cohort study

BACKGROUND

Offspring born via cesarean delivery (CD) may be more prone to develope long-term respiratory diseases, compared to those delivered vaginally (VD). In this study, we compared the rates of respiratory diseases between first twins VD and second twins delivered via CD.

METHODS

This was a retrospective database study. All twin deliveries encompassed at the Soroka University Medical Center, a large tertiary hospital in southern Israel, between 1991 and 2020, in which the first twin was VD and the second via CD were included. Respiratory diseases included respiratory tract diseases such as bronchiolitis and bronchial asthma. The cumulative incidence of respiratory diseases was compared between the twins using Kaplan-Meier survival analysis and multivariable Cox models to adjust for confounding variables.

RESULTS

A total of 395,408 deliveries occurred during the study period, with 13,402 (3.4%) of all deliveries being twins. Of these, 184 (1.4%) were first twins VD and second twins delivered via CD. The second CD twin was more likely to have a non-reassuring fetal heart rate pattern and an Apgar score less than 7 at 5 min. No other differences were found between the siblings. The incidence of long-term respiratory diseases was not statistically different between the CD and VD siblings (7.6% vs. 9.4%, respectively; OR = 0.54; 95% CI: 0.23-1.26). Similarly, the cumulative incidence of respiratory diseases was not statistically different (Kaplan-Meier, log-rank, p = .59), and in the multivariable analysis which adjusted for birthweight and fetal distress during delivery (adjusted hazard ratio = 1.06; 95% CI: 0.43-26.25).

CONCLUSIONS

While the immediate outcomes for the CD twin were slightly worse compared to the VD twin, there was no difference in long-term respiratory diseases between the siblings.

Cesarean section induced dysbiosis promotes type 2 immunity but not oxazolone-induced dermatitis in mice

Delivery by cesarean section (CS) is associated with an altered gut microbiota (GM) colonization and a higher risk of later chronic inflammatory diseases. Studies investigating the association between CS and atopic dermatitis (AD) are contradictive and often biased by confounding factors. The aim of this study was therefore to provide experimental evidence for the association between CS and AD in a mouse model and clarify the role of the GM changes associated with CS. It was hypothesized that CS-delivered mice, and human CS-GM transplanted mice develop severe dermatitis due to early dysbiosis. BALB/c mice delivered by CS or vaginally (VD) as well as BALB/c mice transplanted with GM from CS or VD human donors were challenged with oxazolone on the ear. The severity of dermatitis was evaluated by ear thickness and clinical and histopathological assessment which were similar between all groups. The immune response was assessed by serum IgE concentration, local cytokine response, and presence of immune cells in the draining lymph node. Both CS-delivered mice and mice inoculated with human CS-GM had a higher IgE concentration. A higher proportion of Th2 cells were also found in the CS-GM inoculated mice, but no differences were seen in the cytokine levels in the affected ears. In support of the experimental findings, a human cohort analysis from where the GM samples were obtained found that delivery mode did not affect the children's risk of developing AD. In conclusion, CS-GM enhanced a Th2 biased immune response, but had no effect on oxazolone-induced dermatitis in mice.

Influence of Early Life Factors, including breast milk Composition, on the Microbiome of Infants Born to Mothers with and without Inflammatory Bowel Disease

BACKGROUND AND AIMS

Herein we analysed the influence of early life factors, including breast milk composition, on the development of the intestinal microbiota of infants born to mothers with and without IBD.

METHODS

The MECONIUM [Exploring MEChanisms Of disease traNsmission In Utero through the Microbiome] study is a prospective cohort study consisting of pregnant women with or without IBD and their infants. Longitudinal stool samples were collected from babies and analysed using 16s rRNA sequencing and faecal calprotectin. Breast milk proteomics was profiled using Olink inflammation panel.

RESULTS

We analysed gut microbiota of 1034 faecal samples from 294 infants [80 born to mothers with and 214 to mothers without IBD]. Alpha diversity was driven by maternal IBD status and time point. The major influencers of the overall composition of the microbiota were mode of delivery, feeding, and maternal IBD status. Specific taxa were associated with these exposures, and maternal IBD was associated with a reduction in Bifidobacterium. In 312 breast milk samples [91 from mothers with IBD], mothers with IBD displayed lower abundance of proteins involved in immune regulation, such as thymic stromal lymphopoietin, interleukin-12 subunit beta, tumour necrosis factor-beta, and C-C motif chemokine 20, as compared with control mothers [adjusted p = 0.0016, 0.049, 0.049, and 0.049, respectively], with negative correlations with baby´s calprotectin, and microbiome at different time points.

CONCLUSION

Maternal IBD diagnosis influences microbiota in their offspring during early life. The proteomic profile of breast milk of women with IBD differs from that of women without IBD, with distinct time-dependent associations with baby's gut microbiome and feacal calprotectin.

The Bern Birth Cohort (BeBiCo) to study the development of the infant intestinal microbiota in a high-resource setting in Switzerland: rationale, design, and methods

BACKGROUND

Microbiota composition is fundamental to human health with the intestinal microbiota undergoing critical changes within the first two years of life. The developing intestinal microbiota is shaped by maternal seeding, breast milk and its complex constituents, other nutrients, and the environment. Understanding microbiota-dependent pathologies requires a profound understanding of the early development of the healthy infant microbiota.

METHODS

Two hundred and fifty healthy pregnant women (≥20 weeks of gestation) from the greater Bern area will be enrolled at Bern University hospital's maternity department. Participants will be followed as mother-baby pairs at delivery, week(s) 1, 2, 6, 10, 14, 24, 36, 48, 96, and at years 5 and 10 after birth. Clinical parameters describing infant growth and development, morbidity, and allergic conditions as well as socio-economic, nutritional, and epidemiological data will be documented. Neuro-developmental outcomes and behavior will be assessed by child behavior checklists at and beyond 2 years of age. Maternal stool, milk, skin and vaginal swabs, infant stool, and skin swabs will be collected at enrolment and at follow-up visits. For the primary outcome, the trajectory of the infant intestinal microbiota will be characterized by 16S and metagenomic sequencing regarding composition, metabolic potential, and stability during the first 2 years of life. Secondary outcomes will assess the cellular and chemical composition of maternal milk, the impact of nutrition and environment on microbiota development, the maternal microbiome transfer at vaginal or caesarean birth and thereafter on the infant, and correlate parameters of microbiota and maternal milk on infant growth, development, health, and mental well-being.

DISCUSSION

The Bern birth cohort study will provide a detailed description and normal ranges of the trajectory of microbiota maturation in a high-resource setting. These data will be compared to data from low-resource settings such as from the Zimbabwe-College of Health-Sciences-Birth-Cohort study. Prospective bio-sampling and data collection will allow studying the association of the microbiota with common childhood conditions concerning allergies, obesity, neuro-developmental outcomes , and behaviour. Trial registration The trial has been registered at www.

CLINICALTRIALS

gov , Identifier: NCT04447742.

Seeding the Infant Gut in Early Life-Effects of Maternal and Infant Seeding with Probiotics on Strain Transfer, Microbiota, and Gastrointestinal Symptoms in Healthy Breastfed Infants

We investigated the effects of two dosing regimens of two multi-strain probiotic products on the gut microbiota of breastfed infants, including the transfer of the dosed strains and clinical outcomes. In forty-seven dyads, infants were either exposed through maternal intake (MS) of Lactobacillus acidophilus LA-5, Bifidobacterium animalis subsp. lactis BB-12, Lacticaseibacillus rhamnosus LGG, and Bifidobacterium longum subsp. infantis Bifin02 from gestational week thirty-three until four weeks after birth (n = 24) or dosed directly (IS) with the same strains except for LA-5 starting within 24 h after birth until day 28 (n = 23). Infant stool samples were collected on day 0, 14, 28, and 42 after birth. Gastrointestinal symptoms were assessed by parents using an electronic diary. Microbiota composition was determined using 16S rRNA sequencing, and strain recovery was analyzed by qPCR. Notably, 100% of the IS infants were colonized with Bifin02 after 14 days as opposed to only 25% of the MS infants. Mean stool frequency was significantly lower in IS infants compared to MS infants and IS infants had softer stools on day 14, 28, and 42. A significantly steeper slope of progression of inconsolable crying and fussing was observed in MS infants compared to IS infants. In conclusion, direct infant seeding induced a faster increase in fecal bifidobacteria abundancy and Bifin02 recovery compared to dosed through the maternal intake.

The global/local (limited to some regions) effect of cesarean delivery on the risk of pediatric allergic rhinitis: a systematic review and meta-analysis

Background

Allergic rhinitis is a chronic and refractory disease that can be affected by a variety of factors. Studies have shown an association between cesarean section and the risk of pediatric allergic rhinitis.

Methods

The PubMed, Springer, Embase, Cochrane Library, and Web of Science databases were searched to retrieve all studies published from January 2000 to November 2022, focusing on the relationship between cesarean section and the risk of pediatric allergic rhinitis. A meta-analysis was conducted to find a correlation between cesarean section and the risk of pediatric allergic rhinitis. A subgroup analysis was performed, considering the region and family history of allergy, after adjusting for confounding factors. Pooled odds ratios (ORs) were calculated, publication bias was assessed using a funnel plot, and heterogeneity between study-specific relative risks was taken into account.

Results

The results showed that cesarean section was significantly associated with an increased risk of pediatric allergic rhinitis (OR: 1.27, 95% CI: 1.20-1.35). Subgroup analysis stratified by region indicated that cesarean section increased the risk of pediatric allergic rhinitis, with the highest increase in South America (OR: 1.67, 95% CI: 1.10-2.52) and the lowest in Europe (OR: 1.13, 95% CI: 1.02-1.25). The results of the subgroup analysis stratified by family history of allergy indicate that family history of allergy was not associated with the risk of pediatric allergic rhinitis.

Conclusion

An association exists between cesarean section as the mode of delivery and the increased risk of pediatric allergic rhinitis, and cesarean section is a risk factor for allergic rhinitis.

The gut virome and the relevance of temperate phages in human health

Alterations in the gut virome impact human health. Bacteriophages, viruses that infect bacteria, dominate the gut virome and are mainly composed by virulent and temperate phages. While virulent phages exclusively replicate within and lyse their bacterial host's cell, temperate phages switch from an integrated state residing within their bacterial host's chromosome to an induced free virion state via an induction event. How often do these induction events occur and what are their implications on gut homeostasis? Here, we summarize the current knowledge of the gut virome based on metagenomics and present how the proportion of induced temperate phages varies amongst individuals, age, and disease states. Finally, we highlight the importance of building upon classical culture-dependent techniques and sequencing approaches to improve our understanding of temperate phages to enable their potential therapeutic use.

Risk Factors and Age-Related Patterns of Asthma-Like Symptoms in Early Childhood

BACKGROUND

Episodes of asthma-like symptoms in young children are common, but little is known about risk factors and their patterns for the daily symptom burden.

OBJECTIVE

We investigated a variety of possible risk factors and their age-related impact on the number of asthma-like episodes during age 0 to 3 years.

METHODS

The study population included 700 children from the Copenhagen Prospective Studies on Asthma in Childhood2010 mother-child cohort followed prospectively from birth. Asthma-like symptoms were recorded until age 3 by daily diaries. Risk factors were analyzed by quasi-Poisson regressions, and interaction with age was explored.

RESULTS

Diary data were available in 662 children. Male sex, maternal asthma, low birth weight, maternal antibiotic use, high asthma exacerbation polygenic risk score, and high airway immune score were associated with a higher number of episodes in a multivariable analysis. Maternal asthma, preterm birth, caesarean section, and low birth weight showed an increasing impact with age, whereas sibling(s) at birth showed a decreased association with age. The remaining risk factors had a stable pattern during age 0 to 3 years. For every additional clinical risk factor (male sex, low birth weight, and maternal asthma) a child had, we found 34% more episodes (incidence rate ratio: 1.34, 95% confidence interval: 1.21-1.48; P < .001).

CONCLUSION

Using unique day-to-day diary recordings, we identified risk factors for the burden of asthma-like symptoms in the first 3 years of life and described their unique age-related patterns. This provides novel insight into the origin of asthma-like symptoms in early childhood that potentially pave a path for personalized prognostics and treatment.

Impact of the mother's gut microbiota on infant microbiome and brain development

The link between the gut microbiome and health has recently garnered considerable interest in its employment for medicinal purposes. Since the early microbiota exhibits more flexibility compared to that of adults, there is a considerable possibility that altering it will have significant consequences on human development. Like genetics, the human microbiota can be passed from mother to child. This provides information on early microbiota acquisition, future development, and prospective chances for intervention. The succession and acquisition of early-life microbiota, modifications of the maternal microbiota during pregnancy, delivery, and infancy, and new efforts to understand maternal-infant microbiota transmission are discussed in this article. We also examine the shaping of mother-to-infant microbial transmission, and we then explore possible paths for future research to advance our knowledge in this area.

Pathogenesis of allergic diseases and implications for therapeutic interventions

Allergic diseases such as allergic rhinitis (AR), allergic asthma (AAS), atopic dermatitis (AD), food allergy (FA), and eczema are systemic diseases caused by an impaired immune system. Accompanied by high recurrence rates, the steadily rising incidence rates of these diseases are attracting increasing attention. The pathogenesis of allergic diseases is complex and involves many factors, including maternal-fetal environment, living environment, genetics, epigenetics, and the body's immune status. The pathogenesis of allergic diseases exhibits a marked heterogeneity, with phenotype and endotype defining visible features and associated molecular mechanisms, respectively. With the rapid development of immunology, molecular biology, and biotechnology, many new biological drugs have been designed for the treatment of allergic diseases, including anti-immunoglobulin E (IgE), anti-interleukin (IL)-5, and anti-thymic stromal lymphopoietin (TSLP)/IL-4, to control symptoms. For doctors and scientists, it is becoming more and more important to understand the influencing factors, pathogenesis, and treatment progress of allergic diseases. This review aimed to assess the epidemiology, pathogenesis, and therapeutic interventions of allergic diseases, including AR, AAS, AD, and FA. We hope to help doctors and scientists understand allergic diseases systematically.

25 Years of translational research in the Copenhagen Prospective Studies on Asthma in Childhood (COPSAC)

The Copenhagen Prospective Studies on Asthma in Childhood (COPSAC) mother-child cohorts have provided a foundation of 25 years of research on the origins, prevention, and natural history of childhood asthma and related disorders. COPSAC's approach is characterized by clinical translational research with longitudinal deep phenotyping and exposure assessments from pregnancy, in combination with multi-omic data layers and embedded randomized controlled trials. One trial showed that fish oil supplementation during pregnancy prevented childhood asthma and identified pregnant women with the highest benefits from supplementation, thereby creating the potential for personalized prevention. COPSAC revealed that airway colonization with pathogenic bacteria in early life is associated with an increased risk of asthma. Further, airway bacteria were shown to be a trigger of acute asthma-like symptoms, with benefit from antibiotic treatment. COPSAC identified an immature gut microbiome in early life as a risk factor for asthma and allergy and further demonstrated that asthma can be predicted by infant lung function. At a molecular level, COPSAC has identified novel susceptibility genes, early immune deviations, and metabolomic alterations associated with childhood asthma. Thus, the COPSAC research program has enhanced our understanding of the processes causing childhood asthma and has suggested means of personalized prevention and treatment.

The maternal prenatal and offspring early-life gut microbiome of childhood asthma phenotypes

BACKGROUND

The infant fecal microbiome is known to impact subsequent asthma risk, but the environmental exposures impacting this association, the role of the maternal microbiome, and how the microbiome impacts different childhood asthma phenotypes are unknown.

METHODS

Our objective was to identify associations between features of the prenatal and early-life fecal microbiomes and child asthma phenotypes. We analyzed fecal 16 s rRNA microbiome profiling and fecal metabolomic profiling from stool samples collected from mothers during the third trimester of pregnancy (n = 120) and offspring at ages 3-6 months (n = 265), 1 (n = 436) and 3 years (n = 506) in a total of 657 mother-child pairs participating in the Vitamin D Antenatal Asthma Reduction Trial. We used clinical data from birth to age 6 years to characterize subjects with asthma as having early, transient or active asthma phenotypes. In addition to identifying specific genera that were robustly associated with asthma phenotypes in multiple covariate-adjusted models, we clustered subjects by their longitudinal microbiome composition and sought associations between fecal metabolites and relevant microbiome and clinical features.

RESULTS

Seven maternal and two infant fecal microbial taxa were robustly associated with at least one asthma phenotype, and a longitudinal gut microenvironment profile was associated with early asthma (Fisher exact test p = .03). Though mode of delivery was not directly associated with asthma, we found substantial evidence for a pathway whereby cesarean section reduces fecal Bacteroides and microbial sphingolipids, increasing susceptibility to early asthma.

CONCLUSION

Overall, our results suggest that the early-life, including prenatal, fecal microbiome modifies risk of asthma, especially asthma with onset by age 3 years.

Effects of vaginal seeding on gut microbiota, body mass index, and allergy risks in infants born through cesarean delivery: a randomized clinical trial

BACKGROUND

Vaginal seeding-exposure of neonates to maternal vaginal fluids-has been proposed to improve the microbiota of infants born through cesarean delivery, but its impacts on the infants' subsequent health outcomes remain unclear.

OBJECTIVE

This study aimed to examine the impacts of vaginal seeding on gut microbiota, growth, and allergy risks in infants born through cesarean delivery.

STUDY DESIGN

This randomized controlled trial was conducted at Liuyang Maternal and Child Health Care Hospital in Hunan, China. We estimated that a minimum sample size of 106 was needed by assuming a standardized effect size of 0.6 for the primary outcomes, with a statistical power of 80%, a 2-sided type I error of 0.05, and an expected loss to follow-up rate of 15%. Finally, 120 singleton term pregnant women scheduled for cesarean delivery were enrolled from November 2018 to September 2019. Infant follow-up was completed in September 2021. The participants were randomized in a 1:1 ratio to the vaginal seeding group (n=60; infants were swabbed immediately after birth using gauze preincubated in maternal vagina) or the control group (n=60; routine standard care). The first set of primary outcomes was infant body mass index and body mass index z-scores at 6, 12, 18, and 24 months of age. The other primary outcome was the total allergy risk score at 18 months for 20 common allergens (each scored from 0-6 points). Characteristics of gut microbiota, overweight/obesity, and allergic diseases and symptoms were included as secondary outcomes. The main analyses were performed according to the modified intention-to-treat principle.

RESULTS

Of 120 infants, 117 were included in the analyses. Infant body mass index and body mass index z-scores did not significantly differ between the 2 groups at any of the 4 time points, with the largest difference in point estimates occurring at 6 months: the mean (standard deviation) body mass index was 17.5 (1.4) kg/m² and 17.8 (1.8) kg/m² in the vaginal seeding and control groups, respectively (mean difference, -0.31 kg/m² [95% confidence interval, -0.91 to 0.28]; P=.30), and body mass index z-score was 0.2 (1.0) and 0.4 (1.1), respectively (mean difference, -0.20 [95% confidence interval, -0.58 to 0.18]; P=.31). The median total allergy risk score was 1.5 (interquartile range, 0.0-4.0) in the vaginal seeding group and 2.0 (interquartile range, 1.0-3.0) in the control group (median difference, 0.00 [95% confidence interval, -1.00 to 1.00]; P=.48). For infants from the vaginal seeding group, the relative abundance of genera Lactobacillus and Bacteroides in the gut microbiota was slightly yet nonsignificantly elevated at birth and 6 months, and the risk of overweight/obesity was lower at 6 months (0/57 vs 6/59; relative risk, 0.03 [95% confidence interval, 0.00-0.57]; P=.03) though not at subsequent time points. Other secondary outcomes did not differ between groups. No adverse events related to the intervention were reported.

CONCLUSION

For infants born through cesarean delivery, vaginal seeding has no significant impacts on the gut microbiota, growth, or allergy risks during the first 2 years of life.

Mode of delivery and offspring atopic dermatitis in a Swedish nationwide study

BACKGROUND

Atopic dermatitis is a common chronic childhood disease associated with significant morbidity and healthcare costs. There is a known association between caesarean section and asthma, but the relationship between caesarean section and offspring atopic dermatitis remains uncertain.

METHODS

We conducted a register-based nationwide cohort study including children born in Sweden between January 2006 and December 2018. Data on health and socioeconomic variables were extracted from the national registers for children aged ≤5 years. Time-to-event analyses were used to calculate hazard ratios (HR) with 95% confidence intervals (CI) adjusting for confounders and familial factors.

RESULTS

1,399,406 children were included (6,029,542 person-years at risk). Atopic dermatitis was observed in 17.2% of the 1,150,896 children born by vaginal delivery and 18.3% of the 248,510 born by caesarean section. The mean age of onset of atopic dermatitis was 2.72 years (SD 1.8). Birth by caesarean section was associated with a higher risk of atopic dermatitis (adj-HR 1.12, 95% CI: 1.10-1.14). A higher risk of atopic dermatitis was found in children born by instrumental vaginal delivery (adj-HR 1.10, 1.07-1.13); emergency caesarean section (adj-HR 1.12, 1.10-1.15), and elective caesarean section (adj-HR 1.13, 1.10-1.16) than uncomplicated vaginal delivery in children <1 year of age. Similar hazards were observed in those ≥1 year of age. In sibling control analysis, greater risks remained in children aged <1 year but not in age ≥1 year.

CONCLUSIONS

In our study population, it was observed that children born by caesarean section or instrumental vaginal delivery were at higher risk of early childhood atopic dermatitis. Although familial confounding attenuates the risk in children aged ≥1 year, this was not observed in the first year of life.

Preterm infants at low risk for early-onset sepsis differ in early fecal microbiome assembly

Antibiotics are administered near-universally to very low birth weight (VLBW) infants after birth for suspected early-onset sepsis (EOS). We previously identified a phenotypic group of VLBW infants, referred to as low-risk for EOS (LRE), whose risk of EOS is low enough to avoid routine antibiotic initiation. In this cohort study, we compared 18 such infants with 30 infants categorized as non-LRE to determine if the lower risk of pathogen transmission at birth is accompanied by differences in microbiome acquisition and development. We did shotgun metagenomic sequencing of 361 fecal samples obtained serially. LRE infants had a higher human-to-bacterial DNA ratio than non-LRE infants in fecal samples on days 1-3 after birth, confirming lower bacterial acquisition among LRE infants. The microbial diversity and composition in samples from days 4-7 differed between the groups with a predominance of Staphylococcus epidermidis in LRE infants and Enterobacteriaceae sp. in non-LRE infants. Compositional differences were congruent with the distribution of virulence factors and antibiotic resistant genes. After the first week, the overall composition was similar, but changes in relative abundance for several taxa with increasing age differed between groups. Of the nine late-onset bacteremia episodes, eight occurred in non-LRE infants. Species isolated from the blood culture was detected in the pre-antibiotic fecal samples of the infant for all episodes, though these species were also found in infants without bacteremia. In conclusion, LRE infants present a distinct pattern of microbiome development that is aligned with their low risk for EOS. Further investigation to determine the impact of these differences on later outcomes such as late-onset bacteremia is warranted.

Effects of addition of 2-fucosyllactose to infant formula on growth and specific pathways of utilization by Bifidobacterium in healthy term infants

Oligosaccharides in human milk support health via intestinal microbiome. We studied effects of addition of 2-fucosyllactose (2′FL) to the infant formula on infant growth, occurrence of adverse events (AE), and infant microbiome, including expression of microbial genes that metabolize 2′FL. Our hypothesis was that while 2′FL would not affect growth, it would cause changes in microbiome metabolism. In a double-blinded randomized controlled study fashion, the infant formula ± 2′FL or human milk was fed to healthy term infants for 16 weeks. Fecal samples obtained at baseline and week 16 were analyzed for microbial populations, metagenomic species concept (MGS), and genetics of gut metabolic modules (GMMs). There were no effects of addition of 2′FL on growth or AEs. There were no significant differences by feeding group in MGS richness or Shannon diversity at baseline, but formula groups each had significantly greater richness (p < 0.05) and diversity (p < 0.05) after 16 weeks of feeding than the breastfed group. While two glycosyl hydrolase (GH) families (GH42 and GH112) were significantly increased, two other GH families (GH20 and GH2) were significantly decreased in the test formula group compared to the control formula group; although modest, addition of 2′FL resulted in changes in microbiome in the direction of breastfed infants, consistent with internal metabolism of HMOs by Bifidobacterium.

The Resemblance between Bacterial Gut Colonization in Pigs and Humans

Thorough understanding of the initial colonization process of human intestines is important to optimize the prevention of microbiota-associated diseases, and also to further improve the current microbial therapies. In recent years, therefore, colonization of the human gut has gained renewed interest. However, due to a lack of standardization of life events that might influence this early colonization process in humans, many generally accepted insights are based on deduction and assumption. In our review, we compare knowledge on colonization in humans with research in piglets, because the intestinal tract of pigs is remarkably similar to that of humans and the early-life events are more standardized. We assess potential similarities and challenge some concepts that have been widely accepted in human microbiota research. Bacterial colonization of the human gut is characterized by successive waves in a progressive process, to a complex gut microbiota community. After re-analyzing available data from piglets, we found that the bacterial colonization process is very similar in terms of the wave sequence and functionality of each wave. Moreover, based on the piglet data, we found that, in addition to external factors such as suckling and nutrition, the bacterial community itself appears to have a major influence on the colonization success of additional bacteria in the intestine. Thus, the colonization process in piglets might rely, at least in part, on niche dependency, an ecological principle to be considered in the intestinal colonization process in humans.

Neonatal Diet and Gut Microbiome Development After C-Section During the First Three Months After Birth: A Systematic Review

Background

Cesarean section (C-section) delivery imprints fundamentally on the gut microbiota composition with potential health consequences. With the increasing incidence of C-sections worldwide, there is a need for precise characterization of neonatal gut microbiota to understand how to restore microbial imbalance after C-section. After birth, gut microbiota development is shaped by various factors, especially the infant’s diet and antibiotic exposure. Concerning diet, current research has proposed that breastfeeding can restore the characteristic gut microbiome after C-section.

Objectives

In this systematic review, we provide a comprehensive summary of the current literature on the effect of breastfeeding on gut microbiota development after C-section delivery in the first 3 months of life.

Methods

The retrieved data from PubMed, Scopus, and Web of Science were evaluated according to the PICO/PECO strategy. Quality assessment was conducted by the Newcastle–Ottawa Scale.

Results

After critical selection, we identified 14 out of 4,628 studies for the evaluation of the impact of the diet after C-section delivery. The results demonstrate consistent evidence that C-section and affiliated intrapartum antibiotic exposure affect Bacteroidetes abundance and the incapacity of breastfeeding to reverse their reduction. Furthermore, exclusive breastfeeding shows a positive effect on Actinobacteria and Bifidobacteria restoration over the 3 months after birth. None of the included studies detected any significant changes in Lactobacillus abundance in breastfed infants after C-section.

Conclusion

C-section and intrapartum antibiotic exposure influence an infant’s gut microbiota by depletion of Bacteroides, regardless of the infant’s diet in the first 3 months of life. Even though breastfeeding increases the presence of Bifidobacteria, further research with proper feeding classification is needed to prove the restoration effect on some taxa in infants after C-section.

Systematic Review Registration:

[www.crd.york.ac.uk/prospero/], identifier [CRD42021287672].

Delivery mode and risk of gastrointestinal disease in the offspring

INTRODUCTION

The global increase of individuals born by cesarean section with reported levels up to 20% of all deliveries, makes it important to study cesarean section and possible associations that can increase risk of subsequent diseases in children. The aim of the study was to evaluate if cesarean section is associated with increased risk of gastrointestinal disease later in life in a large population-based cohort.

MATERIAL AND METHODS

In this national population-based cohort study including all full-term individuals registered in the Medical Birth Register in Sweden between 1990 and 2000, type of delivery (exposure) was collected from the Medical Birth Register. The study population was followed until 2017 with regards to the outcomes: inflammatory bowel disease (Crohn's disease or ulcerative colitis), appendicitis, cholecystitis, or diverticulitis registered in the Swedish National Patient Register. Cox proportional-hazards models compared disease-free survival time between exposed and unexposed.

RESULTS

The final study population consisted of 1 102 468 individuals of whom 11.6% were delivered by cesarean section and 88.4% were vaginally delivered. In univariate analysis, cesarean section was associated with Crohn's disease (hazard ratio [HR] 1.13, 95% confidence interval [CI] 1.02-1.25), diverticulosis (HR 1.57, 95% CI 1.13-2.18), and cholecystitis (HR 1.16, 95% CI 1.05-1.28). However, the increased risk only remained for Crohn's disease after adjustment for confounders (HR 1.14, 95% CI 1.02-1.27). No associations between delivery mode and appendicitis, ulcerative colitis, cholecystitis, or diverticulosis were found in the multivariate analysis.

CONCLUSIONS

Cesarean section is associated with Crohn's disease later in life, but no other association between delivery mode and gastrointestinal disorders later in life could be found.

The association between duration of breastfeeding and childhood asthma outcomes

BACKGROUND

Postnatal exposures, including breastfeeding, may influence asthma development.

OBJECTIVE

To investigate the association between breastfeeding duration and child asthma.

METHODS

We studied 2021 mother-child dyads in the ECHO PATHWAYS consortium of prospective pregnancy cohorts (GAPPS, CANDLE, TIDES). Women reported the duration of any and exclusive breastfeeding and child asthma outcomes during follow-up at child age 4 to 6 years. Outcomes included current wheeze (previous 12 months), ever asthma, current asthma (having ≥2 of current wheeze, ever asthma, medication use in past 12-24 months), and strict current asthma (ever asthma with either or both current wheeze and medication use in past 12-24 months). We used multivariable logistic regression to assess associations (odds ratios and 95% confidence intervals) between breastfeeding and asthma outcomes adjusting for potential confounders. We assessed effect modification by mode of delivery, infant sex, and maternal asthma.

RESULTS

Among women, 33%, 13%, 9%, and 45% reported 0 to less than 2, 2 to 4, 5 to 6, and more than 6 months of any breastfeeding, respectively. The duration of any breastfeeding had a protective linear trend with ever asthma but no other outcomes. There was a duration-dependent protective association of exclusive breastfeeding and child asthma outcomes (eg, current asthma adjusted odds ratio [95% confidence interval], 0.64 [0.41-1.02], 0.61 [0.38-0.98], and 0.52 (0.31-0.87) for 2to 4 months, 5 to 6 months, and more than 6 months, respectively, compared with <2 months). For exclusive breastfeeding, protective associations were stronger in dyads with children born by vaginal vs cesarean delivery although interactions did not reach statistical significance (Pinteractions 0.12-0.40).

CONCLUSION

Longer duration of exclusive breastfeeding had a protective association with child asthma.

Whole exome sequencing in a juvenile idiopathic arthritis large family with SERPINA1 gene mutations

OBJECTIVES

Although the underlying mechanisms and mediators of arthritis in juvenile idiopathic arthritis are not well understood, accumulated evidence supports the mixt role of genetic and environmental factors. Few reports of multiplex families with JIA were published until now. The aim of this study was to describe the subjects affected by juvenile idiopathic arthritis and psoriatic features (JIAPs) in a large family.

METHODS

Here, we characterized an extended multiplex family of 5 patients with juvenile idiopathic arthritis and psoriatic features (PsA) at the clinical and genetic level, using whole exome sequencing.

RESULTS

We did not confirm in our family the linkage with the genetic factors already described that might be associated with increase susceptibility to JIA. We found a carrier status of siblings who inherited a pathogenic allele of the SERPINA1 gene from their mother who herself has two heterozygous pathogenic variants in the SERPINA1 gene.

CONCLUSIONS

This study didn't identify genetic contributive factors but highlights potentially environmental associations concerning the siblings of a family with juvenile idiopathic arthritis and psoriatic features (JIAPs). It is difficult to establish that SERPINA1 gene mutation has an etiological role as the levels of AAT are only slightly decreased and all the children harbor heterozygous variants.

The Role of Early Life Microbiota Composition in the Development of Allergic Diseases

Allergic diseases are becoming a major healthcare issue in many developed nations, where living environment and lifestyle are most predominantly distinct. Such differences include urbanized, industrialized living environments, overused hygiene products, antibiotics, stationary lifestyle, and fast-food-based diets, which tend to reduce microbial diversity and lead to impaired immune protection, which further increase the development of allergic diseases. At the same time, studies have also shown that modulating a microbiocidal community can ameliorate allergic symptoms. Therefore, in this paper, we aimed to review recent findings on the potential role of human microbiota in the gastrointestinal tract, surface of skin, and respiratory tract in the development of allergic diseases. Furthermore, we addressed a potential therapeutic or even preventive strategy for such allergic diseases by modulating human microbial composition.

Prevalence of eczema between cesarean-born and vaginal-born infants within 1 year of age: a systematic review and meta-analysis

This study aims to quantify the difference in prevalence of eczema between cesarean-born and vaginal-born infants within 1 year of age through a systematic review and meta-analysis. Six electronic databases were searched from inception to August 31, 2021. Studies were included if they reported the prevalence of eczema in infants within 1 year of age with specified mode of delivery. The quality of included studies was assessed using the Joanna Briggs Instrument Critical Appraisal Checklist. Pooled prevalence and odds ratio (OR) were estimated by meta-analyses of included studies. Meta-regression was conducted to explore factors affecting heterogeneity of the prevalence of eczema. Nine studies were included with 3,758 cesarean-born infants and 9,631 vaginal-born infants. The prevalence of eczema in cesarean-born infants [27.8%; 95% confidence interval (CI): 17.7-39.2] was higher than in vaginal-born infants (20.1%; 95% CI: 13.9-28.1), with a pooled OR of 1.31 (95% CI: 1.04-1.65). Subgroup analyses showed that the prevalence of eczema in cesarean-born infants varied according to country, study design, and method of ascertainment. Additionally, the pooled prevalence of eczema in vaginal-born infants differed by age at which eczema was identified. Meta-regression analysis showed that study design and eczema ascertainment method were significant sources of heterogeneity.

CONCLUSION

About 28% of cesarean-born infants within 1 year of age developed eczema, significantly higher than the 20% rate or occurrence seen in vaginal-born infants.

PROTOCOL REGISTRATION

CRD 42,020,152,437.

WHAT IS KNOWN

• Eczema, a complex inflammatory cutaneous disorder characterized by immune mediated inflammation and epidermal barrier dysfunction, is one of the most common allergic disorders in infants. • Eczema may increase the risk of immune-mediated inflammatory disease such as food allergy, asthma, and allergic rhinitis, leading to psychological and social burdens on affected individuals and their families. • Mode of delivery may be associated with the risk of developing eczema, although further studies are needed to clarify such differences.

WHAT IS NEW

• This is the first systematic review designed to estimate the prevalence of eczema in cesarean- and vaginal-born infants within 1 year of age. • Cesarean delivery may increase the risk of developing eczema in infants within the first year of life.

Longitudinal and Comparative Analysis of Gut Microbiota of Tunisian Newborns According to Delivery Mode

Microbiota colonization is a dynamic process that impacts the health status during an individual's lifetime. The composition of the gut microbiota of newborns is conditioned by multiple factors, including the delivery mode (DM). Nonetheless, the DM's influence remains uncertain and is still the subject of debate. In this context, the medical indication and the emergency of a cesarean delivery might have led to confounding conclusions regarding the composition and diversity of the neonatal microbiome. Herein, we used high-resolution shotgun sequencing to decipher the composition and dynamics of the gut microbiota composition of Tunisian newborns. Stool samples were collected from 5 elective cesarean section (ECS) and 5 vaginally delivered (VD) newborns at the following time points: Day 0, Day 15, and Day 30. The ECS and VD newborns showed the same level of bacterial richness and diversity. In addition, our data pointed to a shift in microbiota community composition during the first 2 weeks, regardless of the DM. Both ECS and VD showed a profile dominated by Proteobacteria, Actinobacteria, and Firmicutes. However, ECS showed an underrepresentation of Bacteroides and an enrichment of opportunistic pathogenic species of the ESKAPE group, starting from the second week. Besides revealing the intestinal microbiota of Tunisian newborns, this study provides novel insights into the microbiota perturbations caused by ECS.

Effects of delivery mode and labor duration on the development of food sensitization in infancy

BACKGROUND

The effects of delivery mode and labor duration on the development of food sensitization (FS) in infancy remain unclear.

OBJECTIVE

To elucidate the potential effects of delivery mode and labor duration on FS development by 6 months of age.

METHODS

Using data from a randomized controlled trial of a birth cohort from 4 Japanese hospitals that assessed cow's milk allergy development by 6 months of age, we performed a nested case-control trial of 462 participants who had undergone the final assessment at 6 months of age. FS was defined as positive skin prick test reactions to hen's egg, cow's milk, wheat, or soy. For the primary outcome, we calculated the adjusted odds ratio of vaginal delivery (VD) relative to cesarean delivery for FS development by 6 months of age using a multivariable logistic regression analysis. For the secondary outcome, we compared labor durations between participants with and without FS using the Mann-Whitney U test.

RESULTS

The adjusted odds ratio of VD for FS development was 2.54 (95% confidence interval, 1.32-4.87; P = .005). The median labor duration was significantly longer in participants with FS (5.7 hours, interquartile range, 2.7-10.1) than in participants without FS (4.5 hours, 1.1-8.2) (P = .01).

CONCLUSION

VD was considerably associated with an increased risk of FS in infancy, and longer labor durations may promote FS development.

Cesarean section is not associated with increased risk of celiac disease in the offspring: a meta-analysis

OBJECTIVE

Epidemiologic findings are inconsistent concerning the association between cesarean section (C-section) and celiac disease in offspring.

METHODS

We performed a systematic literature search of PubMed and Embase databases until July 2021. A meta-analysis was performed for each outcome in which a summary odds ratio (OR) was calculated while taking heterogeneity into account.

RESULTS

A total of 11 observational were identified for the literature review. We found that C-section was not associated with an increase in the risk of CD (OR = 1.03, 95% CI, 0.95-1.12; p = .501). In subgroup analyses, the association remained insignificant for both infants born after elective C-section (OR 1.05; 0.95-1.16; p = .329) and emergency C-section (OR 1.06; 1-1.13; p = .051).

CONCLUSIONS

Our results indicate that C-section is not associated with CD in offspring.

Understanding the pathways leading to gut dysbiosis and enteric environmental dysfunction in infants: the influence of maternal dysbiosis and other microbiota determinants during early life

Maternal environmental enteric dysfunction (EED) encompasses undernutrition with an inflammatory gut profile, a variable degree of dysbiosis and increased translocation of pathogens in the gut mucosa. Even though recent research findings have shed light on the pathological pathways underlying the establishment of the infant gut dysbiosis, evidence on how maternal EED influences the development of gut dysbiosis and EED in the offspring remains elusive. This review summarizes the current knowledge on the effect of maternal dysbiosis and EED on infant health, and explores recent progress in unraveling the mechanisms of acquisition of a dysbiotic gut microbiota in the offspring. In Western communities, maternal inoculum, delivery mode, perinatal antibiotics, feeding practices, and infections are the major drivers of the infant gut microbiota during the first two years of life. In other latitudes, the infectious burden and maternal malnutrition might introduce further risk factors for infant gut dysbiosis. Novel tools, such as transcriptomics and metabolomics, have become indispensable to analyze the metabolic environment of the infant in utero and post-partum. Human-milk oligosaccharides have essential prebiotic, antimicrobial, and anti-biofilm properties that might offer additional therapeutic opportunities.

The prevalence of food allergy in cesarean-born children aged 0-3 years: A systematic review and meta-analysis of cohort studies

PURPOSE

Previous studies reported a higher risk of food allergy for cesarean-born children than vaginal-born children. This study aims to systematically compare the prevalence of food allergy among cesarean-born and vaginal-born children aged 0-3 years.

METHODS

Three English and two Chinese databases were searched using terms related to food allergies and cesarean sections. Cohort studies that reported the prevalence of food allergy in cesarean-born and vaginal-born children aged 0-3 years were included. Two reviewers performed study selection, quality assessment, and data extraction. The pooled prevalence of food allergy in cesarean-born and vaginal-born children was compared by meta-analysis.

RESULTS

Nine eligible studies, with 9,650 cesarean-born children and 20,418 vaginal-born children aged 0-3 years, were included. Of them, 645 cesarean-born children and 991 vaginal-born children were identified as having food allergies. The pooled prevalence of food allergy was higher in cesarean-born children (7.8%) than in vaginal-born children (5.9%). Cesarean section was associated with an increased risk of food allergy [odds ratio (OR): 1.45; 95% confidence interval (CI): 1.03-2.05] and cow's milk allergy (OR: 3.31; 95% CI: 1.98-5.53). Additionally, cesarean-born children with a parental history of allergy had an increased risk of food allergy (OR: 2.60; 95% CI: 1.28-5.27).

CONCLUSION

This study suggests that cesarean sections was associated with an increased risk of food and cow's milk allergies in children aged 0-3 years. Cesarean-born children with a parental history of allergy demonstrated a higher risk for food allergy than did vaginal-born children. These results indicate that caregivers should be aware of the risks of food allergies in cesarean-born children, reducing the risk of potentially fatal allergic events. Further research is needed to identify the specific factors affecting food allergies in young children.

SYSTEMATIC REVIEW REGISTRATION

http://www.crd.york.ac.uk/prospero, identifier: International Prospective Register of Systematic Reviews (NO. CRD42019140748).

Infant gut microbiota restoration: state of the art

The gut microbiota has a central role in the programming of the host's metabolism and immune function, with both immediate and long-term health consequences. Recent years have witnessed an accumulation of understanding of the process of the colonization and development of the gut microbiota in infants. The natural gut microbiota colonization during birth is frequently disrupted due to C-section birth or intrapartum or postpartum antibiotic exposure, and consequently aberrant gut microbiota development is common. On a positive note, research has shown that restoration of normal gut microbiota development is feasible. We discuss here the current understanding of the infant microbiota, provide an overview of the sources of disturbances, and critically evaluate the evidence on early life gut microbiota restoration for improved health outcomes by analyzing published data from infant gut microbiota restoration studies.

OUP accepted manuscript

The intestinal microbiota plays a crucial role in health and changes in its composition are linked with major global human diseases. Fully understanding what shapes the human intestinal microbiota composition and knowing ways of modulating the composition are critical for promotion of life-course health, combating diseases, and reducing global health disparities. We aim to provide a foundation for understanding what shapes the human intestinal microbiota on an individual and global scale, and how interventions could utilize this information to promote life-course health and reduce global health disparities. We briefly review experiences within the first 1,000 days of life and how long-term exposures to environmental elements or geographic specific cultures have lasting impacts on the intestinal microbiota. We also discuss major public health threats linked to the intestinal microbiota, including antimicrobial resistance and disappearing microbial diversity due to globalization. In order to promote global health, we argue that the interplay of the larger ecosystem with intestinal microbiota research should be utilized for future research and urge for global efforts to conserve microbial diversity.

Toxin-Producing Klebsiella oxytoca in Healthy Infants: Commensal or Pathobiont?

OBJECTIVES

Klebsiella oxytoca is a gastrointestinal pathobiont with the potential to produce the toxins tilivalline and tilimycin, which cause antibiotic-associated hemorrhagic colitis. Overgrowth of toxigenic K oxytoca has recently been implicated in necrotizing enterocolitis. K oxytoca colonizes 2-9% of healthy adults, however, there is no systematic data on colonization in healthy children. We investigated K oxytoca colonization and its toxigenic properties in healthy infants.

METHODS

We sampled stool of healthy infants and determined K oxytoca colonization using stool culture and PCR (pehX). Toxin in stool was measured with HPLC/high-resolution mass spectrometry. K oxytoca isolates were typed using multi-locus sequence typing (MLST) and K oxytoca toxin PCR (npsA/B). Cytotoxin production of isolates was analyzed by MTT assay.

RESULTS

K oxytoca was detected in 30 of 61 infants (49%) using stool culture and in 45 of 61 (73%) using PCR (pehX). Toxin marker PCR (npsA/B) was positive in 66% of stool samples positive for K oxytoca PCR. Stool toxin levels were too low for quantitation but traces of tilivalline were detected. Contrarily, 49% of K oxytoca isolates demonstrated toxicity in the MTT assay. MLST revealed 36 distinct sequence types affiliated with all known K oxytoca sequence type clusters (A, B1 and B2).

CONCLUSIONS

More than 70% of healthy infants were colonized with K oxytoca. Toxin quantities in stool of colonized healthy infants were below detection level, yet half of the isolates produced toxin in vitro demonstrating their pathobiont potential. The high occurrence of toxigenic K oxytoca in healthy infants has to be considered for future disease association studies.

Neonatal metabolome of cesarean section and risk of childhood asthma

BACKGROUND

Birth by cesarean section (CS) is linked to an increased risk of developing asthma, but the underlying mechanisms are unclear.

OBJECTIVE

To elucidate the link between birth by CS and asthma using newborn metabolomic profiles and integrating early life gut microbiome data and cord blood immunology.

METHODS

We investigated the influence of CS on liquid chromatography mass spectrometry (LC-MS) metabolomic profiles of dried blood spots from newborns of the two independent Copenhagen Prospective Studies on Asthma in Childhood cohorts, i.e. COPSAC2010 (n=677) and COPSAC2000 (n=387). We assessed the associations between the CS metabolic profile, age one-week gut microbiome data and frequency of cord blood Tregs.

RESULTS

In COPSAC2010, a partial least square-discriminant analysis (PLS-DA) model showed that children born by CS versus natural delivery had different metabolic profiles (AUC=0.77, p=2.2e-16), which was replicated in COPSAC2000 (AUC=0.66, p=1.2e-5). The metabolic profile of CS was significantly associated with an increased risk of asthma at school-age in both COPSAC2010 (p=0.03) and COPSAC2000 (p=0.005). CS was associated with lower abundance of tryptophan, bile acid and phenylalanine metabolites, indicative of a perturbed gut microbiota. Further, gut bacteria dominating after natural delivery, i.e. Bifidobacterium and Bacteroides were correlated with CS-discriminative microbial metabolites, suggesting maternal microbial transmission during birth regulating the newborn's metabolism. Finally, the CS metabolic profile was associated with frequency of cord blood Tregs.

CONCLUSIONS

These findings propose that CS is programming the risk of childhood asthma through perturbed immune responses and gut microbial colonization patterns reflected in the blood metabolome at birth.

Preterm infant meconium microbiota transplant induces growth failure, inflammatory activation, and metabolic disturbances in germ-free mice

Preterm birth may result in adverse health outcomes. Very preterm infants typically exhibit postnatal growth restriction, metabolic disturbances, and exaggerated inflammatory responses. We investigated the differences in the meconium microbiota composition between very preterm (<32 weeks), moderately preterm (32–37 weeks), and term (>37 weeks) human neonates by 16S rRNA gene sequencing. Human meconium microbiota transplants to germ-free mice were conducted to investigate whether the meconium microbiota is causally related to the preterm infant phenotype in an experimental model. Our results indicate that very preterm birth is associated with a distinct meconium microbiota composition. Fecal microbiota transplant of very preterm infant meconium results in impaired growth, altered intestinal immune function, and metabolic parameters as compared to term infant meconium transplants in germ-free mice. This finding suggests that measures aiming to minimize the long-term adverse consequences of very preterm birth should be commenced during pregnancy or directly after birth.

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Very preterm neonates exhibit a distinct meconium microbiota composition

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Human meconium microbiota is transplanted to germ-free mice in this study

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Preterm transplant induces growth restriction, inflammation, and altered metabolism

•

Initial gut microbiota may be causally related to complications of prematurity

Building Robust Assemblages of Bacteria in the Human Gut in Early Life

The neonatal body provides a range of potential habitats, such as the gut, for microbes. These sites eventually harbor microbial communities (microbiotas). A "complete" (adult) gut microbiota is not acquired by the neonate immediately after birth. Rather, the exclusive, milk-based nutrition of the infant encourages the assemblage of a gut microbiota of low diversity, usually dominated by bifidobacterial species. The maternal fecal microbiota is an important source of bacterial species that colonize the gut of infants, at least in the short-term. However, development of the microbiota is influenced by the use of human milk (breast feeding), infant formula, preterm delivery of infants, caesarean delivery, antibiotic administration, family details and other environmental factors. Following the introduction of weaning (complementary) foods, the gut microbiota develops in complexity due to the availability of a diversity of plant glycans in fruits and vegetables. These glycans provide growth substrates for the bacterial families (such as members of the Ruminococcaceae and Lachnospiraceae) that, in due course, will dominate the gut microbiota of the adult. Although current data are often fragmentary and observational, it can be concluded that the nutrition that a child receives in early life is likely to impinge not only on the development of the microbiota at that time but also on the subsequent lifelong, functional relationships between the microbiota and the human host. The purpose of this review, therefore, is to discuss the importance of promoting the assemblage of functionally robust gut microbiotas at appropriate times in early life.

Role of Maternal Microbiota and Nutrition in Early-Life Neurodevelopmental Disorders

The rise in the prevalence of obesity and other related metabolic diseases has been paralleled by an increase in the frequency of neurodevelopmental problems, which has raised the likelihood of a link between these two phenomena. In this scenario, maternal microbiota is a possible linking mechanistic pathway. According to the “Developmental Origins of Health and Disease” paradigm, environmental exposures (in utero and early life) can permanently alter the body’s structure, physiology, and metabolism, increasing illness risk and/or speeding up disease progression in offspring, adults, and even generations. Nutritional exposure during early developmental stages may induce susceptibility to the later development of human diseases via interactions in the microbiome, including alterations in brain function and behavior of offspring, as explained by the gut–brain axis theory. This review provides an overview of the implications of maternal nutrition on neurodevelopmental disorders and the establishment and maturation of gut microbiota in the offspring.

Nurturing the Early Life Gut Microbiome and Immune Maturation for Long Term Health

Early life is characterized by developmental milestones such as holding up the head, turning over, sitting up and walking that are typically achieved sequentially in specific time windows. Similarly, the early gut microbiome maturation can be characterized by specific temporal microorganism acquisition, colonization and selection with differential functional features over time. This orchestrated microbial sequence occurs from birth during the first years of age before the microbiome reaches an adult-like composition and function between 3 and 5 years of age. Increasingly, these different steps of microbiome development are recognized as crucial windows of opportunity for long term health, primarily linked to appropriate immune and metabolic development. For instance, microbiome disruptors such as preterm and Cesarean-section birth, malnutrition and antibiotic use are associated with increased risk to negatively affect long-term immune and metabolic health. Different age discriminant microbiome taxa and functionalities are used to describe age-appropriate microbiome development, and advanced modelling techniques enable an understanding and visualization of an optimal microbiome maturation trajectory. Specific microbiome features can be related to later health conditions, however, whether such features have a causal relationship is the topic of intense research. Early life nutrition is an important microbiome modulator, and 'Mother Nature' provides the model with breast milk as the sole source of nutrition for the early postnatal period, while dietary choices during the prenatal and weaning period are to a large extent guided by tradition and culture. Increasing evidence suggests prenatal maternal diet and infant and child nutrition impact the infant microbiome trajectory and immune competence development. The lack of a universal feeding reference for such phases represents a knowledge gap, but also a great opportunity to provide adequate nutritional guidance to maintain an age-appropriate microbiome for long term health. Here, we provide a narrative review and perspective on our current understanding of age-appropriate microbiome maturation, its relation to long term health and how nutrition shapes and influences this relationship.

Ongoing Supplementation of Probiotics to Cesarean-Born Neonates during the First Month of Life may Impact the Gut Microbial

OBJECTIVE

The delivery mode is considered to be a significant influencing factor in the early gut microbiota composition, which is associated with the long-term health of the host. In this study, we tried to explore the effects of probiotics on the intestinal microbiota of C-section neonates.

STUDY DESIGN

Twenty-six Chinese neonates were enrolled in this study. The neonates were divided into four groups: VD (natural delivery neonates, n = 3), CD (cesarean-born neonates, n = 9), CDL (cesarean-born neonates supplemented with probiotic at a lower dosage, n = 7), and CDH (cesarean-born neonates supplemented with probiotic at a higher dosage, n = 7). Fecal samples were collected on the 3rd, 7th, and 28th day since birth. The V3-V4 region of the 16S ribosomal ribonucleic acid gene was sequenced by next-generation sequencing technology.

RESULTS

The α-diversity of the intestinal microbiota of cesarean delivery neonates was significantly lower than that of the naturally delivered neonates on the 28th day (p = 0.005). After supplementation with probiotics for 28 days, the α-diversity and the β-diversity of the gut flora in the cesarean-born infants (CDL28 and CDH28) was similar to that in the vaginally delivery infants. Meanwhile, the abundances of Lactobacillus and Bifidobacterium were significantly increased since the 3rd day of probiotic supplementation. Besides, the sustained supplementation of probiotics to neonates would help improve the abundance of the operational taxonomic units in several different Clusters of Orthologous Groups of proteins.

CONCLUSION

This study showed that probiotics supplementation to cesarean-born neonates since birth might impact the diversity and function of gut microbiota.

KEY POINTS

· Cesarean-born neonates. · Probiotic supplementation impact gut flora. · Bifidobacterium and Lactobacillus.

Impact of Delivery Mode on Infant Gut Microbiota

Microbial colonization of the neonate is an important feature of normal birth. The gut microbiota has a central role in the programming of the host's metabolism and immune function, with both immediate and long-term health consequences. During vaginal birth, the infant is exposed to diverse maternal microbes, of which specific faecal microbes colonize the infant's gut. C-section eliminates the infant's contact with maternal microbes, preventing vertical transmission of gut microbes. Consequently, infants are colonized by bacteria from the environment, including potential pathogens from the hospital environment. Recent studies have shown that intrapartum antibiotic exposure has a C-section-like effect on the infant gut microbiota. While the composition of the gut microbiota largely normalizes during the first year of life, epidemiological studies suggest that the aberrant early microbial exposures have long-term immunological and metabolic consequences. Because of the high prevalence of procedures that prevent normal gut microbiota development, effective methods to normalize the gut microbiota of neonates are urgently needed. Even more importantly, attention should be paid to the microbiota imbalance in C-section-born and antibiotic-exposed infants in clinical practice. Breastfeeding and probiotics are particularly important for infants with disrupted gut colonization.

Technological tools and strategies for culturing human gut microbiota in engineered in vitro models

The gut microbiota directly impacts the pathophysiology of different human body districts. Consequently, microbiota investigation is an hot topic of research and its in vitro culture has gained extreme interest in different fields. However, the high sensitivity of microbiota to external stimuli, such as sampling procedure, and the physicochemical complexity of the gut environment make its in vitro culture a challenging task. New engineered microfluidic gut-on-a-chip devices have the potential to model some important features of the intestinal structure, but they are usually unable to sustain culture of microbiota over an extended period of time. The integration of gut-on-a-chip devices with bioreactors for continuous bacterial culture would lead to fast advances in the study of microbiota-host crosstalk. In this review, we summarize the main technologies for the continuous culture of microbiota as upstream systems to be coupled with microfluidic devices to study bacteria-host cells communication. The engineering of integrated microfluidic platforms, capable of sustaining both anaerobic and aerobic cultures, would be the starting point to unveil complex biological phenomena proper of the microbiota-host crosstalks, paving to way to multiple research and technological applications.