Birth mode is associated with earliest strain-conferred gut microbiome functions and immunostimulatory potential

Understanding Horizontal Gene Transfer network in human gut microbiota

Background

Horizontal Gene Transfer (HGT) is the process of transferring genetic materials between species. Through sharing genetic materials, microorganisms in the human microbiota form a network. The network can provide insights into understanding the microbiota. Here, we constructed the HGT networks from the gut microbiota sequencing data and performed network analysis to characterize the HGT networks of gut microbiota.

Results

We constructed the HGT network and perform the network analysis to two typical gut microbiota datasets, a 283-sample dataset of Mother-to-Child and a 148-sample dataset of longitudinal inflammatory bowel disease (IBD) metagenome. The results indicated that (1) the HGT networks are scale-free. (2) The networks expand their complexities, sizes, and edge numbers, accompanying the early stage of lives; and microbiota established in children shared high similarity as their mother (p-value = 0.0138), supporting the transmission of microbiota from mother to child. (3) Groups harbor group-specific network edges, and network communities, which can potentially serve as biomarkers. For instances, IBD patient group harbors highly abundant communities of Proteobacteria (p-value = 0.0194) and Actinobacteria (p-value = 0.0316); children host highly abundant communities of Proteobacteria (p-value = 2.8785\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$e^{-5}$$\end{document}e-5) and Actinobacteria (p-value = 0.0015), and the mothers host highly abundant communities of Firmicutes (p-value = 8.0091\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$e^{-7}$$\end{document}e-7). IBD patient networks contain more HGT edges in pathogenic genus, including Mycobacterium, Sutterella, and Pseudomonas. Children’s networks contain more edges from Bifidobacterium and Escherichia.

Conclusion

Hence, we proposed the HGT network constructions from the gut microbiota sequencing data. The HGT networks capture the host state and the response of microbiota to the environmental and host changes, and they are essential to understand the human microbiota.

A Metabolomics Approach to Screening for Autism Risk in the Children's Autism Metabolome Project

Autism spectrum disorder (ASD) is biologically and behaviorally heterogeneous. Delayed diagnosis of ASD is common and problematic. The complexity of ASD and the low sensitivity of available screening tools are key factors in delayed diagnosis. Identification of biomarkers that reduce complexity through stratification into reliable subpopulations can assist in earlier diagnosis, provide insight into the biology of ASD, and potentially suggest targeted interventions. Quantitative metabolomic analysis was performed on plasma samples from 708 fasting children, aged 18 to 48 months, enrolled in the Children's Autism Metabolome Project (CAMP). The primary goal was to identify alterations in metabolism helpful in stratifying ASD subjects into subpopulations with shared metabolic phenotypes (i.e., metabotypes). Metabotypes associated with ASD were identified in a discovery set of 357 subjects. The reproducibility of the metabotypes was validated in an independent replication set of 351 CAMP subjects. Thirty-four candidate metabotypes that differentiated subsets of ASD from typically developing participants were identified with sensitivity of at least 5% and specificity greater than 95%. The 34 metabotypes formed six metabolic clusters based on ratios of either lactate or pyruvate, succinate, glycine, ornithine, 4-hydroxyproline, or α-ketoglutarate with other metabolites. Optimization of a subset of new and previously defined metabotypes into a screening battery resulted in 53% sensitivity (95% confidence interval [CI], 48%-57%) and 91% specificity (95% CI, 86%-94%). Thus, our metabolomic screening tool detects more than 50% of the autistic participants in the CAMP study. Further development of this metabolomic screening approach may facilitate earlier referral and diagnosis of ASD and, ultimately, more targeted treatments. LAY SUMMARY: Analysis of a selected set of metabolites in blood samples from children with autism and typically developing children identified reproducible differences in the metabolism of about half of the children with autism. Testing for these differences in blood samples can be used to help screen children as young as 18 months for risk of autism that, in turn, can facilitate earlier diagnoses. In addition, differences may lead to biological insights that produce more precise treatment options. We are exploring other blood-based molecules to determine if still a higher percentage of children with autism can be detected using this strategy. Autism Res 2020, 13: 1270-1285. © 2020 The Authors. Autism Research published by International Society for Autism Research published by Wiley Periodicals LLC.

Development of child immunity in the context of COVID-19 pandemic

Children, because of having an immature immune system, are usually more prone than the adults to the microbial infections and have more severe symptoms, which is especially true for the newborns, and very young children. However, the review of clinical data from the current COVID-19 pandemic indicates otherwise. We discuss here what are the main features and components of children's immune system, the role of maternal transmission of immunity, and what are the possible explanations for the seemingly lower infection rate and severity of COVI-19 in children.

Midwives' experiences of the factors that facilitate normal birth among low risk women in public hospitals in Catalonia (Spain)

BACKGROUND

Normal birth has major benefits for women and infants. Nevertheless, during the last few decades, the advancement in technology and an increasing domination of obstetrician-led childbirths have resulted in the medicalization of childbirth. Midwives are interested in amending this trend and aim to support women to achieve the best possible birth experience for them.

OBJECTIVE

This study aimed to explore midwives' experiences on the facilitators and barriers of normal birth in conventional obstetric units.

DESIGN

A descriptive qualitative study. Three focus groups were audio recorded and transcribed verbatim. Recurrent themes were identified and formulated. Feedback from data were analysed using thematic analysis. Investigator triangulation was used during the analysis.

SETTING

Midwives from eleven different public hospitals in Catalonia participated in the study.

PARTICIPANTS

A purposive sample of 33 midwives participated in the focus groups.

FINDINGS

Midwives identified several factors that complicated their task of facilitating normal birth. Barriers included: (1) inadequate institutional support; (2) existing obstetrician-led practices, (3) lack of evidence-based practice and (4) midwives' lack of awareness of professional competencies. Factors facilitating normal birth included: (1) midwives' positive perceptions of normal birth, (2) midwives' additional effort and (3) women's awareness of normal birth.

KEY CONCLUSIONS

Midwives wishing to promote normal birth in obstetric units face a number of challenges and often feel unsupported. Nonetheless, the midwives perceive the increasing women's demand for normal births as an opportunity to implement changes in such a way that women are involved in the decision-making process and midwives act as their advocates.

IMPLICATIONS FOR PRACTICE

There is a need to increase the midwifery workforce and enhance regulations and funding strategies to support their practice as well as normal birth. Policy makers in settings without well-functioning midwife-led care should consider implementing this model after successfully scaling up of the number of midwives and ensuring an effective midwifery training.

Recent advances in understanding the neonatal microbiome

The neonatal developmental window represents a key time for establishment of the gut microbiota. First contact with these microbes within the infant gastrointestinal tract signifies the start of a critical mutualistic relationship, which is central for short- and longer-term health. Recent research has provided insights into the origin of these microbial pioneers, how they are maintained within the gut environment, and how factors such as antibiotics or preterm birth may disrupt the succession of beneficial microbes.  The acquisition, colonisation, and maintenance of the early life microbiota, and subsequent interactions with the host is a rapidly developing research area. In this review we explore some of these key topics which have been illuminated by recent research, and we highlight some of the important unresolved questions which currently limit our overall understanding of the neonatal gut microbiome.

Toward a Symbiotic Perspective on Public Health: Recognizing the Ambivalence of Microbes in the Anthropocene

Microbes evolve in complex environments that are often fashioned, in part, by human desires. In a global perspective, public health has played major roles in structuring how microbes are perceived, cultivated, and destroyed. The germ theory of disease cast microbes as enemies of the body and the body politic. Antibiotics have altered microbial development by providing stringent natural selection on bacterial species, and this has led to the formation of antibiotic-resistant bacterial strains. Public health perspectives such as "Precision Public Health" and "One Health" have recently been proposed to further manage microbial populations. However, neither of these take into account the symbiotic relationships that exist between bacterial species and between bacteria, viruses, and their eukaryotic hosts. We propose a perspective on public health that recognizes microbial evolution through symbiotic associations (the hologenome theory) and through lateral gene transfer. This perspective has the advantage of including both the pathogenic and beneficial interactions of humans with bacteria, as well as combining the outlook of the "One Health" model with the genomic methodologies utilized in the "Precision Public Health" model. In the Anthropocene, the conditions for microbial evolution have been altered by human interventions, and public health initiatives must recognize both the beneficial (indeed, necessary) interactions of microbes with their hosts as well as their pathogenic interactions.

The athletic gut microbiota

The microorganisms in the gastrointestinal tract play a significant role in nutrient uptake, vitamin synthesis, energy harvest, inflammatory modulation, and host immune response, collectively contributing to human health. Important factors such as age, birth method, antibiotic use, and diet have been established as formative factors that shape the gut microbiota. Yet, less described is the role that exercise plays, particularly how associated factors and stressors, such as sport/exercise-specific diet, environment, and their interactions, may influence the gut microbiota. In particular, high-level athletes offer remarkable physiology and metabolism (including muscular strength/power, aerobic capacity, energy expenditure, and heat production) compared to sedentary individuals, and provide unique insight in gut microbiota research. In addition, the gut microbiota with its ability to harvest energy, modulate the immune system, and influence gastrointestinal health, likely plays an important role in athlete health, wellbeing, and sports performance. Therefore, understanding the mechanisms in which the gut microbiota could play in the role of influencing athletic performance is of considerable interest to athletes who work to improve their results in competition as well as reduce recovery time during training. Ultimately this research is expected to extend beyond athletics as understanding optimal fitness has applications for overall health and wellness in larger communities. Therefore, the purpose of this narrative review is to summarize current knowledge of the athletic gut microbiota and the factors that shape it. Exercise, associated dietary factors, and the athletic classification promote a more “health-associated” gut microbiota. Such features include a higher abundance of health-promoting bacterial species, increased microbial diversity, functional metabolic capacity, and microbial-associated metabolites, stimulation of bacterial abundance that can modulate mucosal immunity, and improved gastrointestinal barrier function.

Development of the Microbiota and Associations With Birth Mode, Diet, and Atopic Disorders in a Longitudinal Analysis of Stool Samples, Collected From Infancy Through Early Childhood

BACKGROUND & AIMS

Establishment of the gastrointestinal microbiota during infancy affects immune system development and oral tolerance induction. Perturbations in the microbiome during this period can contribute to development of immune-mediated diseases. We monitored microbiota maturation and associations with subsequent development of allergies in infants and children.

METHODS

We collected 1453 stool samples, at 5, 13, 21, and 31 weeks postpartum (infants), and once at school age (6-11 years), from 440 children (49.3% girls, 24.8% born by cesarean delivery; all children except for 6 were breastfed for varying durations; median 40 weeks; interquartile range, 30-53 weeks). Microbiota were analyzed by amplicon sequencing. Children were followed through 3 years of age for development of atopic dermatitis; data on allergic sensitization and asthma were collected when children were school age.

RESULTS

Diversity of fecal microbiota, assessed by Shannon index, did not differ significantly among children from 5 through 13 weeks after birth, but thereafter gradually increased to 21 and 31 weeks. Most bacteria within the Bacteroidetes and Proteobacteria phyla were already present at 5 weeks after birth, whereas many bacteria of the Firmicutes phylum were acquired at later times in infancy. At school age, many new Actinobacteria, Firmicutes, and Bacteroidetes bacterial taxa emerged. The largest increase in microbial diversity occurred after 31 weeks. Vaginal, compared with cesarean delivery, was most strongly associated with an enrichment of Bacteroides species at 5 weeks through 31 weeks. From 13 weeks onward, diet became the most important determinant of microbiota composition; cessation of breastfeeding, rather than solid food introduction, was associated with changes. For example, Bifidobacteria, staphylococci, and streptococci significantly decreased on cessation of breastfeeding, whereas bacteria within the Lachnospiraceae family (Pseudobutyrivibrio, Lachnobacterium, Roseburia, and Blautia) increased. When we adjusted for confounding factors, we found fecal microbiota composition to be associated with development of atopic dermatitis, allergic sensitization, and asthma. Members of the Lachnospiraceae family, as well as the genera Faecalibacterium and Dialister, were associated with a reduced risk of atopy.

CONCLUSIONS

In a longitudinal study of fecal microbiota of children from 5 weeks through 6 to 11 years, we tracked changes in diversity and composition associated with the development of allergies and asthma.

An individualized mosaic of maternal microbial strains is transmitted to the infant gut microbial community

To understand the origins of the infant gut microbial community, we have used a published metagenomic dataset of the faecal microbiome of mothers and their related infants at early (4, 7 and 21 days) and late times (6-15 months) following birth. Using strain-tracking analysis, individual-specific patterns of microbial strain sharing were found between mothers and infants following vaginal birth. Overall, three mother-infant pairs showed only related strains, while 12 infants of mother-infant pairs contained a mosaic of maternal-related and unrelated microbes. Analysis of a second dataset from nine women taken at different times of pregnancy revealed individual-specific faecal microbial strain variation that occurred in seven women. To model transmission in the absence of environmental microbes, we analysed the microbial strain transmission to F1 progenies of human faecal transplanted gnotobiotic mice bred with gnotobiotic males. Strain-tracking analysis of five different dams and their F1 progeny revealed both related and unrelated microbial strains in the mother's faeces. The results of our analysis demonstrate that multiple strains of maternal microbes, some that are not abundant in the maternal faecal community, can be transmitted during birth to establish a diverse infant gut microbial community.

Preterm neonatal immunology at the intestinal interface

Fetal and neonatal development represents a critical window for setting a path toward health throughout life. In this review, we focus on intestinal immunity, how it develops, and its implications for subsequent neonatal diseases. We discuss maternal nutritional and environmental exposures that dictate outcomes for the developing fetus. Although still controversial, there is evidence in support of an in utero microbiome. Specific well-intentioned and routine applications of antibiotics, steroids, and surgical interventions implemented before, during, and after birth skew the neonate towards pro-inflammatory dysbiosis. Shortly after birth, a consortium of maternal and environmentally derived bacteria, through cross-talk with the developing host immune system, takes center stage in developing or disrupting immune homeostasis at the intestinal interface. We also examine subsequent immunological cross-talks, which involve neonatal myeloid and lymphoid responses, and their potential impacts on health and disease such as necrotizing enterocolitis and sepsis, especially critical disease entities for the infant born preterm.

Breast milk-derived human milk oligosaccharides promote Bifidobacterium interactions within a single ecosystem

Diet-microbe interactions play an important role in modulating the early-life microbiota, with Bifidobacterium strains and species dominating the gut of breast-fed infants. Here, we sought to explore how infant diet drives distinct bifidobacterial community composition and dynamics within individual infant ecosystems. Genomic characterisation of 19 strains isolated from breast-fed infants revealed a diverse genomic architecture enriched in carbohydrate metabolism genes, which was distinct to each strain, but collectively formed a pangenome across infants. Presence of gene clusters implicated in digestion of human milk oligosaccharides (HMOs) varied between species, with growth studies indicating that within single infants there were differences in the ability to utilise 2'FL and LNnT HMOs between strains. Cross-feeding experiments were performed with HMO degraders and non-HMO users (using spent or 'conditioned' media and direct co-culture). Further 1H-NMR analysis identified fucose, galactose, acetate, and N-acetylglucosamine as key by-products of HMO metabolism; as demonstrated by modest growth of non-HMO users on spend media from HMO metabolism. These experiments indicate how HMO metabolism permits the sharing of resources to maximise nutrient consumption from the diet and highlights the cooperative nature of bifidobacterial strains and their role as 'foundation' species in the infant ecosystem. The intra- and inter-infant bifidobacterial community behaviour may contribute to the diversity and dominance of Bifidobacterium in early life and suggests avenues for future development of new diet and microbiota-based therapies to promote infant health.

Neonatal Microbiome and Its Relationship to Necrotizing Enterocolitis: A Review of the Science

Necrotizing enterocolitis (NEC) occurs in many premature infants hospitalized in the neonatal intensive care unit. About 3% to 15% of very low-weight premature infants develop NEC, with an estimated 30% mortality rate for the cases requiring surgery. Currently, there is no known pathogenesis for NEC in the patient's populations. However, one of the most widely accepted hypotheses is having an abnormal fetal gut microbiome. The purpose of this review is to discuss some current methods of dysbiosis in the neonatal microbiome, such as maternal health, breastfeeding, and delivery method, and then to connect these to the occurrence of NEC in the infant and finally discuss some possibilities for limiting the occurrence of NEC in the future.

You've got male: Sex and the microbiota-gut-brain axis across the lifespan

Sex is a critical factor in the diagnosis and development of a number of mental health disorders including autism, schizophrenia, depression, anxiety, Parkinson's disease, multiple sclerosis, anorexia nervosa and others; likely due to differences in sex steroid hormones and genetics. Recent evidence suggests that sex can also influence the complexity and diversity of microbes that we harbour in our gut; and reciprocally that our gut microbes can directly and indirectly influence sex steroid hormones and central gene activation. There is a growing emphasis on the role of gastrointestinal microbiota in the maintenance of mental health and their role in the pathogenesis of disease. In this review, we introduce mechanisms by which gastrointestinal microbiota are thought to mediate positive health benefits along the gut-brain axis, we report how they may be modulated by sex, the role they play in sex steroid hormone regulation, and their sex-specific effects in various disorders relating to mental health.

Can early surgery improve the outcome of patients with meconium peritonitis? A single-center experience over 16 years

BACKGROUND

In the last century, meconium peritonitis(MP)was once a highly fatal gastrointestinal. disease With the development of fetal radiological technology, abnormal signs, such as pseudocysts, can. be detected during the fetal period so that more patients can be diagnosed prenatally and receive surgery. in the early stage of life. The survival rate of MP has increased up to 80% in recent years. According to. a review of the treatment and outcomes of patients diagnosed with MP, we evaluated the influence of. early operation on survival rate and discussed the risk factors of prognosis.

METHODS

We collected 79 cases of patients diagnosed with MP who were treated in our department. from October 2001 to December 2017. They were divided into 2 groups. Patients in group A were born. in our hospital. Patients in group B were born in a local hospital with suspicion of MP and then transferred. to our department.

RESULTS

The birth weight (BW) and gestational age (GA) of patients were higher in group A than in. group B. There was no significant difference in the proportion of premature and low birth weight (LBW). patients between the two groups (p = 0.422, p = 0.970). Their age at the time of surgery was younger in. group A than in group B (1.4 ± 2.0 vs. 6.9 ± 14.9, p < 0.001). The overall survival rate of group A was higher. than that of group B (95.0% vs. 79.5%, p = 0.038). The prognosis of premature patients was worse than. that of full-term infants for both groups (p = 0.012).

CONCLUSIONS

Prematurity is a significant risk factor related to death for MP patients. The survival rate. of MP patients can be improved by early operation during the neonatal period.

Prebiotics Fructo-, Galacto-, and Mannan-Oligosaccharide Do Not Protect against 5-Fluorouracil-Induced Intestinal Mucositis in Rats

BACKGROUND

Prebiotics selectively stimulate the growth of beneficial bacteria within the gastrointestinal tract, and have been investigated in human and animal studies for their capacity to improve intestinal health.

OBJECTIVE

We investigated the prebiotics fructo-oligosaccharide (FOS), galacto-oligosaccharide (GOS), and mannan-oligosaccharide (MOS) for their potential to alleviate intestinal damage in rats.

METHODS

Female Dark Agouti rats (6-8 wk old, 110-150 g) were allocated to 1 of the following treatment groups (n = 8/group): saline/water, saline/FOS, saline/GOS, saline/MOS, 5-fluorouracil (5FU)/water, 5FU/FOS, 5FU/GOS, and 5FU/MOS. Rats were pretreated with either 5% GOS, MOS, or FOS or vehicle (water) from day -12 to day 0. On day 0, rats received a single intraperitoneal injection of saline or 5FU. Metabolic data were recorded daily and all rats were killed on day 3. Histopathology was quantified in hematoxylin and eosin-stained sections. Intestinal sucrase and myeloperoxidase activity were quantified by biochemical assay. Fecal SCFAs-acetic, propionic, and butyric acid-were also measured. Statistical analysis was by repeated-measures, 2-factor ANOVA or Kruskal-Wallis and Mann-Whitney U test; P < 0.05 was considered statistically significant.

RESULTS

Body weight was significantly decreased in all treatment groups after 5FU injection, with no change in body weight observed in any prebiotic treatment group. Total food intake was lower by ≥7% in the GOS treatment group pre-5FU than in all other groups (P < 0.05). Ileal villus height was 18% higher in GOS-treated rats pre-5FU than in respective water controls (P < 0.05). Jejunal and ileal villus height and crypt depth were significantly decreased in all treatment groups after 5FU injection, with no prebiotic effect observed. SCFAs were differentially increased in prebiotic treatment groups compared with water-only controls (P < 0.05).

CONCLUSIONS

FOS, GOS, and MOS have differential effects in modifying small intestinal pathology and SCFA profiles in rats with healthy and damaged small intestinal mucosa.

Bacterial Baptism: Scientific, Medical, and Regulatory Issues Raised by Vaginal Seeding of C-Section-Born Babies

Several lines of evidence suggest that children born via Cesarean section (C-section) are at greater risk for adverse health outcomes including allergies, asthma and obesity. Vaginal seeding is a medical procedure in which infants born by C-section are swabbed immediately after birth with vaginal secretions from the mother. This procedure has been proposed as a way to transfer the mother's vaginal microbiome to the child, thereby restoring the natural exposure that occurs during vaginal birth that is interrupted in the case of babies born via C-section. Preliminary evidence indicates partial restoration of microbes. However, there is insufficient evidence to determine the health benefits of the procedure. Several studies, including trial, are currently underway. At the same time, in the clinic setting, doctors are increasingly being asked to by expectant mothers to have their babies seeded. This article reports on the current research on this procedure and the issues it raises for regulators, researchers, physicians, and patients.

The association between caesarean section delivery and later life obesity in 21-24 year olds in an Urban South African birth cohort

BACKGROUND

Obesity is an important public health problem and rates have reached epidemic proportions in many countries. Studies have explored the association between infants delivered by caesarean section and their later life risk of obesity, in many countries outside Africa. As a result of the increasing caesarean section and obesity rates in South Africa, we investigated the association in this country.

METHODS

This was a retrospective analysis of data that were collected from a prospective South African birth cohort (Birth to Twenty Plus), established in 1990. A total of 889 young adults aged 21-24 years were included in the analysis. Poisson regression models were fitted to assess the association between mode of delivery and early adulthood obesity.

RESULTS

Of the 889 young adults, 106 (11.9%) were obese while 72 (8.1%) were delivered by caesarean section; of which 14 (19.4%) were obese. Caesarean section delivery was significantly associated with obesity in young adults after adjusting for potential confounders like young adults' sex and birth weight, mothers' parity, and education (incidence rate ratio 1.64, 95% CI 1.01-2.68, p = 0.045).

CONCLUSION

The association of caesarean section with early adulthood obesity should be interpreted with caution because data on certain key confounding factors such as mothers' pre-pregnancy body mass index and gestational diabetes were not available. Further research from Africa, with larger sample sizes and databases with useful linking of maternal and infant data, should be conducted.

Review of environmental factors and juvenile idiopathic arthritis

Juvenile idiopathic arthritis is a common rheumatic disease that presents as chronic childhood arthritis. JIA is considered a multifactorial disease that may result from diverse genetic and environmental risk factors. A minority of the population-attributable risk of JIA is estimated to be due to familial factors. Thus, non-genetic or environmental factors likely account for a majority of the risk of developing JIA. Yet, while substantial data have linked environmental factors to the development of rheumatoid arthritis, similar evidence regarding JIA is sparse. This narrative review provides updates on recent literature about environmental factors that might influence the risk of developing JIA, including studies about potentially beneficial and harmful influences as well as factors with unclear effects.

The role of the preterm intestinal microbiome in sepsis and necrotising enterocolitis

Late-onset sepsis (LOS) and necrotising enterocolitis (NEC) account for the highest number of deaths in premature infants and often cause severe morbidity in survivors. NEC is an inflammatory mediated condition, but its pathophysiology remains poorly understood. There is increasing evidence that in LOS the causative organism most often translocates from the gut. No causative microorganism has been consistently associated with either LOS or NEC, but an aberrant gut microbiome development could play a pivotal role. A low bacterial diversity and a delay in anaerobic bacteria colonization may predispose preterm infants to disease development. Conversely, a predominance of Bifidobacterium species and breast milk feeding might help to prevent disease onset. With numerous studies reporting conflicting results, further research is needed to better understand the role of microorganisms and type of feeding in the health status of preterm infants.

Caesarean section delivery and childhood obesity in a British longitudinal cohort study

Background

Several studies reported an association between Caesarean section (CS) birth and childhood obesity. However, there are several limitations in the current literature. These include an inability to distinguish between planned and emergency CS, small study sample sizes and not adjusting for pre-pregnancy body-mass-index (BMI). We examined the association between CS delivery and childhood obesity using the United Kingdom Millennium Cohort Study (MCS).

Methods

Mother-infant pairs were recruited into the MCS. Use of sampling weights ensured the sample was representative of the population. The exposure was categorised as normal vaginal delivery (VD) [reference], assisted VD, planned CS and emergency CS. Childhood obesity prevalence, at age three, five, seven, eleven and fourteen years was calculated using the International Obesity Taskforce criteria. Mixed-effects linear regression models were fitted with associations adjusted for several potential confounders like maternal age, pre-pregnancy BMI, education and infant macrosomia. Linear regression models were fitted evaluating body fat percentage (BF%), at age seven and fourteen years.

Results

Of the 18,116 infants, 3872 (21.4%) were delivered by CS; 9.2% by planned CS. Obesity prevalence was 5.4%, 5.7%, 6.5%, 7.1% and 7.6% at age three, five, seven, eleven and fourteen years respectively. The mixed-effects linear regression model showed no association between planned (adjusted mean difference = 0.00; [95% confidence interval (CI) -0.10; 0.10], p-value = 0.97) or emergency CS (adjusted mean difference = 0.08; [95% CI -0.01; 0.17], p-value = 0.09) and child BMI. At age seven years, there was no association between planned CS and BF% (adjusted mean difference = 0.13; [95% CI -0.23; 0.49]); there was no association at age fourteen years.

Conclusions

Infants born by planned CS did not have a significantly higher BMI or BF% compared to those born by normal VD. This may suggest that the association, described in the literature, could be due to the indications/reasons for CS birth or residual confounding.

Stunted microbiota and opportunistic pathogen colonization in caesarean-section birth

Immediately after birth, newborn babies experience rapid colonization by microorganisms from their mothers and the surrounding environment1. Diseases in childhood and later in life are potentially mediated by the perturbation of the colonization of the infant gut microbiota2. However, the effects of delivery via caesarean section on the earliest stages of the acquisition and development of the gut microbiota, during the neonatal period (≤1 month), remain controversial3,4. Here we report the disrupted transmission of maternal Bacteroides strains, and high-level colonization by opportunistic pathogens associated with the hospital environment (including Enterococcus, Enterobacter and Klebsiella species), in babies delivered by caesarean section. These effects were also seen, to a lesser extent, in vaginally delivered babies whose mothers underwent antibiotic prophylaxis and in babies who were not breastfed during the neonatal period. We applied longitudinal sampling and whole-genome shotgun metagenomic analysis to 1,679 gut microbiota samples (taken at several time points during the neonatal period, and in infancy) from 596 full-term babies born in UK hospitals; for a subset of these babies, we collected additional matched samples from mothers (175 mothers paired with 178 babies). This analysis demonstrates that the mode of delivery is a significant factor that affects the composition of the gut microbiota throughout the neonatal period, and into infancy. Matched large-scale culturing and whole-genome sequencing of over 800 bacterial strains from these babies identified virulence factors and clinically relevant antimicrobial resistance in opportunistic pathogens that may predispose individuals to opportunistic infections. Our findings highlight the critical role of the local environment in establishing the gut microbiota in very early life, and identify colonization with antimicrobial-resistance-containing opportunistic pathogens as a previously underappreciated risk factor in hospital births.

Prenatal and postnatal contributions of the maternal microbiome on offspring programming

The maternal microbiota is positioned to regulate the development of offspring immunity, metabolism, as well as brain function and behavior. The mechanisms by which maternal microbial signals drive these processes are beginning to be elucidated. In this review, we provide a brief overview on the importance of the microbiome in brain function and behavior, define the maternal vaginal and gut microbiota as distinct influences on offspring development, and outline current concepts in microbial origins of offspring health outcomes. We propose that the maternal microbiota influences prenatal and early postnatal offspring development and health outcomes through two overlapping processes. First, during pregnancy maternal gut microbiota provide metabolites and substrates essential for fetal growth through metabolic provisioning, driving expansion and maturation of central and peripheral immune cells, and formation of neural circuits. Second, vertical transmission of maternal microbiota during birth and in the early postnatal window elicits a potent immunostimulatory effect in offspring that induces metabolic and developmental transcriptional programs, primes the immune system for subsequent microbial exposure, and provides substrates for brain metabolism. Finally, we explore the possibility that environmental factors, such as malnutrition, stress and infection, may exert programmatic effects by disrupting the functional contributions of the maternal microbiome during prenatal and postnatal development to influence offspring outcomes across the lifespan.

S-layer Impacts the Virulence of Bacillus in Endophthalmitis

Purpose

Bacillus causes a sight-threating infection of the posterior segment of the eye. The robust intraocular inflammatory response in this disease is likely activated via host innate receptor interactions with components of the Bacillus cell envelope. S-layer proteins (SLPs) of some Gram-positive pathogens contribute to the pathogenesis of certain infections. The potential contributions of SLPs in eye infection pathogenesis have not been considered. Here, we explored the role of a Bacillus SLP (SlpA) in endophthalmitis pathogenesis.

Methods

The phenotypes and infectivity of wild-type (WT) and S-layer deficient (ΔslpA) Bacillus thuringiensis were compared. Experimental endophthalmitis was induced in C57BL/6J mice by intravitreally injecting 100-CFU WT or ΔslpA B. thuringiensis. Infected eyes were analyzed by bacterial counts, retinal function analysis, histology, and inflammatory cell influx. SLP-induced inflammation was also analyzed in vitro. Muller cells (MIO-M1) were treated with purified SLP. Nuclear factor-κB (NF-κB) DNA binding was measured by ELISA and expression of proinflammatory mediators from Muller cells was measured by RT-qPCR.

Results

Tested phenotypes of WT and ΔslpA B. thuringiensis were similar, with the exception of absence of the S-layer in the ΔslpA mutant. Intraocular growth of WT and ΔslpA B. thuringiensis was also similar. However, eyes infected with the ΔslpA mutant had significantly reduced inflammatory cell influx, less inflammatory damage to the eyes, and significant retention of retinal function compared with WT-infected eyes. SLP was also a potent stimulator of the NF-κB pathway and induced the expression of proinflammatory mediators (IL6, TNFα, CCL2, and CXCL-1) in human retinal Muller cells.

Conclusions

Taken together, our results suggest that SlpA contributes to the pathogenesis of Bacillus endophthalmitis, potentially by triggering innate inflammatory pathways in the retina.

Maternal Vertical Transmission Affecting Early-life Microbiota Development

The association of the human microbiome with health outcomes has attracted much interest toward its therapeutic manipulation. The likelihood of modulating the human microbiome in early life is high and offers great potential to exert profound effects on human development since the early microbiota shows more flexibility compared to that of adults. The human microbiota, being similar to human genetics, can be transmitted from mother to infant, providing insights into early microbiota acquisition, subsequent development, and potential opportunities for intervention. Here, we review adaptations of the maternal microbiota during pregnancy, birth, and infancy, the acquisition and succession of early-life microbiota, and highlight recent efforts to elucidate mother-to-infant microbiota transmission. We further discuss how the mother-to-infant microbial transmission is shaped; and finally we address potential directions for future studies to promote our understanding within this field.

Intestinal Microbiota in Early Life and Its Implications on Childhood Health

Trillions of microbes reside in the human body and participate in multiple physiological and pathophysiological processes that affect host health throughout the life cycle. The microbiome is hallmarked by distinctive compositional and functional features across different life periods. Accumulating evidence has shown that microbes residing in the human body may play fundamental roles in infant development and the maturation of the immune system. Gut microbes are thought to be essential for the facilitation of infantile and childhood development and immunity by assisting in breaking down food substances to liberate nutrients, protecting against pathogens, stimulating or modulating the immune system, and exerting control over the hypothalamic-pituitary-adrenal axis. This review aims to summarize the current understanding of the colonization and development of the gut microbiota in early life, highlighting the recent findings regarding the role of intestinal microbes in pediatric diseases. Furthermore, we also discuss the microbiota-mediated therapeutics that can reconfigure bacterial communities to treat dysbiosis.