Modelling the effect of birth and feeding modes on the development of human gut microbiota

Alterations of gut microbiota in infants with biliary atresia identified by 16S rRNA-sequencing

BACKGROUND

Biliary atresia (BA) is a severe neonatal disease with progressive intra- and extra-hepatic bile ducts inflammation and hepatic fibrosis. Characterization of gut microbiome profiles in infants with biliary atresia can provide valuable information and potential disease biomarkers. Our study aims to explore the relationship between gut microbiota and biliary atresia.

METHODS

16 S ribosomal RNA (rRNA) gene sequencing was carried out to identify the differences in composition and diversity of gut microbiota between infants with BA and healthy subjects. A total of 31 infants with biliary atresia and 20 healthy subjects were recruited.

RESULTS

The composition of gut microbiota in BA group was significantly different with the normal control group (P < 0.05) and the abundance ratio of Klebsiella/Bifidobacterium showed great potential for identification of BA (P < 0.01). In addition, the differential bacterial taxa were involved in lipid and vitamins metabolism.

CONCLUSION

Our results could provide potential non-invasive biomarker for identification of biliary atresia and contribute to the treatment in terms of ameliorating microbiota dysbiosis.

Early bile drainage improves native liver survival in biliary atresia without cholangitis

Objectives

To explore the outcomes and related factors in children without cholangitis after Kasai portoenterostomy (KPE).

Methods

We retrospectively analyzed the data of infants with type III BA who underwent KPE from June 2016 to December 2021. We compared and analyzed the difference in native liver survival (NLS) rates in different types of cholangitis. We also investigated the relationship between the absence of cholangitis and the effect of early bile drainage (EBD) as well as the related factors affecting EBD efficacy.

Results

A total of 145 children were included in this study. Among these children, 82 (56.6%, 82/145) had cholangitis, including 40 (48.8%, 40/82) with early cholangitis and 33 (40.2%, 33/82) with recurrent cholangitis. The median follow-up period was 29 months (range, 2-75 months). The NLS rates were 67.6%, 51.7%, 45.5% and 43.4% at 6 months, 1 year, 2 years and 5 years following KPE, while the NLS rates for infants without cholangitis after KPE were 68.3%, 50.8%, 46.0% and 46.0%, respectively. Higher gamma-glutamyl transferase (γ- GT) and total bile acid (TBA) before KPE were risk factors for cholangitis (P < 0.05). The NLS rate in recurrent cholangitis was significantly lower than that in occasional cholangitis (P < 0.01). Compared with the EBD-poor group, the NLS rate in the EBD-good group of infants was significantly increased (P < 0.001). EBD was significantly correlated with the occurrence and frequency of cholangitis (P < 0.05).

Conclusions

Recurrent cholangitis was an important factor affecting NLS. For children without cholangitis after KPE, early bile drainage was better, and the NLS was longer.

Defining the Relationship of Gut Microbiota, Immunity, and Cognition in Early Life-A Narrative Review

Recently, the immune system has been identified as one of the possible main bridges which connect the gut-brain axis. This review aims to examine available evidence on the microbiota-immunity-cognitive relationship and its possible effects on human health early in life. This review was assembled by compiling and analyzing various literature and publications that document the gut microbiota-immune system-cognition interaction and its implications in the pediatric population. This review shows that the gut microbiota is a pivotal component of gut physiology, with its development being influenced by a variety of factors and, in return, supports the development of overall health. Findings from current research focus on the complex relationship between the central nervous system, gut (along with gut microbiota), and immune cells, highlighting the importance of maintaining a balanced interaction among these systems for preserving homeostasis, and demonstrating the influence of gut microbes on neurogenesis, myelin formation, the potential for dysbiosis, and alterations in immune and cognitive functions. While limited, evidence shows how gut microbiota affects innate and adaptive immunity as well as cognition (through HPA axis, metabolites, vagal nerve, neurotransmitter, and myelination).

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.

Gut mutualists can persist in host populations despite low fidelity of vertical transmission

Humans harbour diverse microbial communities, and this interaction has fitness consequences for hosts and symbionts. Understanding the mechanisms that preserve host-symbiont association is an important step in studying co-evolution between humans and their mutualist microbial partners. This association is promoted by vertical transmission, which is known to be imperfect. It is unclear whether host-microbial associations can generally be maintained despite 'leaky' vertical transmission. Cultural practices of the host are expected to be important in bacterial transmission as they influence the host's interaction with other individuals and with the environment. There is a need to understand whether and how cultural practices affect host-microbial associations. Here, we develop a mathematical model to identify the conditions under which the mutualist can persist in a population where vertical transmission is imperfect. We show with this model that several factors compensate for imperfect vertical transmission, namely, a selective advantage to the host conferred by the mutualist, horizontal transmission of the mutualist through an environmental reservoir and transmission of a cultural practice that promotes microbial transmission. By making the host-microbe association more likely to persist in the face of leaky vertical transmission, these factors strengthen the association which in turn enables host-mutualist co-evolution.

Spatial dynamics of inflammation-causing and commensal bacteria in the gastrointestinal tract

In recent years, new research programmes have been initiated to understand the role of gut bacteria in health and disease, enabled in large part by the emergence of high-throughput sequencing. As new genomic and other data emerge it will become important to explain observations in terms of underlying population mechanisms; for instance, it is of interest to understand how resident bacteria interact with their hosts and pathogens, and how they play a protective role. Connecting underlying processes with observed patterns is aided by the development of mathematical models. Here, we develop a spatial model of microbial populations in the gastrointestinal tract to explore conditions under which inflammation-causing bacteria can invade the gut and under which such pathogens become persistent. We find that pathogens invade both small and large intestine from even a relatively small inoculum size but are usually eliminated by the host response. When the immune response is weak, the pathogen is able to persist for a long period. Spatial structure affects these dynamics by creating moving refugia which facilitate bouts of pathogen resurgence and inflammation in persistent infections. Space also plays a role in repopulation by commensals after infection. We further find that the rate of decay of inflammation has a stronger effect on outcomes than the initiation of inflammation or other parameters. Finally, we explore the impact of partially inflammation-resistant commensals on these dynamics.

Comparative analysis of gut microbial composition and potential functions in captive forest and alpine musk deer

Gut microbiota forms a unique microecosystem and performs various irreplaceable metabolic functions for ruminants. The gut microbiota is important for host health and provides new insight into endangered species conservation. Forest musk deer (FMD) and alpine musk deer (AMD) are typical small ruminants, globally endangered due to excessive hunting and habitat loss. Although nearly 60 years of captive musk deer breeding has reduced the hunting pressure in the wild, fatal gastrointestinal diseases restrict the growth of captive populations. In this study, 16S rRNA high-throughput sequencing revealed the differences in gut microbiota between FMD and AMD based on 166 fecal samples. The alpha diversity was higher in FMD than in AMD, probably helping FMD adapt to different and wider habitats. The ß-diversity was higher between adult FMD and AMD than juveniles and in winter than late spring. The phylum Firmicutes and the genera Christensenellaceae R7 group, Ruminococcus, Prevotellaceae UCG-004, and Monoglobus were significantly higher in abundance in FMD than in AMD. However, the phylum Bacteroidetes and genera Bacteroides, UCG-005, Rikenellaceae RC9 gut group, and Alistipes were significantly higher in AMD than FMD. The expression of metabolic functions was higher in AMD than in FMD, a beneficial pattern for AMD to maintain higher energy and substance metabolism. Captive AMD may be at higher risk of intestinal diseases than FMD, with higher relative abundances of most opportunistic pathogens and the expression of disease-related functions. These results provide valuable data for breeding healthy captive musk deer and assessing their adaptability in the wild. KEY POINTS: • Alpha diversity of gut microbiota was higher in FMD than that in AMD • Expression of metabolic and disease-related functions was higher in AMD than in FMD.

The Pregnancy and EARly Life study (PEARL) - a longitudinal study to understand how gut microbes contribute to maintaining health during pregnancy and early life

BACKGROUND

The early life period represents the first step in establishing a beneficial microbial ecosystem, which in turn affects both short and longer-term health. Changes during pregnancy influence the neonatal microbiome; through transmission of maternal microbes during childbirth, and beyond, through nutritional programming. However, in-depth exploration of longitudinal maternal-infant cohorts, with sampling of multiple body sites, complemented by clinical and nutritional metadata, and use of cutting-edge experimental systems are limited. The PEARL study will increase our knowledge of; how microbes (including viruses/phages, bacteria, fungi and archaea) change in composition and functional capacity during pregnancy; transmission pathways from mother to infant; the impact of various factors on microbial communities across pregnancy and early life (e.g. diet), and how these microbes interact with other microbes and modulate host processes, including links to disease onset.

METHODS

PEARL is a longitudinal observational prospective study of 250 pregnant women and their newborns, with stool and blood samples, questionnaires and routine clinical data collected during pregnancy, labour, birth and up to 24 months post birth. Metagenomic sequencing of samples will be used to define microbiome profiles, and allow for genus, species and strain-level taxonomic identification and corresponding functional analysis. A subset of samples will be analysed for host (immune/metabolite) molecules to identify factors that alter the host gut environment. Culturing will be used to identify new strains of health-promoting bacteria, and potential pathogens. Various in vitro and in vivo experiments will probe underlying mechanisms governing microbe-microbe and microbe-host interactions.

DISCUSSION

Longitudinal studies, like PEARL, are critical if we are to define biomarkers, determine mechanisms underlying microbiome profiles in health and disease, and develop new diet- and microbe-based therapies to be tested in future studies and clinical trials.

TRIAL REGISTRATION

This study is registered in the ClinicalTrials.gov Database with ID: NCT03916874 .