Gut microbiota and developmental programming of the brain: from evidence in behavioral endophenotypes to novel perspective in obesity

Premature Infant Gut Microbiome relationships with childhood behavioral scales: preliminary insights

Introduction

Very Low Birth Weight (VLBW) infants, born weighing less than 1,500 grams, are at risk for both gut dysbiosis and later neuropsychological developmental deficits. Behavioral effects, while related to neurodevelopment, are often more subtle and difficult to measure. The extent of later neurobehavioral consequences associated with such microbial dysbiosis has yet to be determined. We explored associations between the infants' gut microbiome and early childhood behavior at 4 years of age and identified the bacterial taxa through a multivariate analysis by linear models.

Methods

Parents completed the Child Behavior Checklist (CBCL) focused on different DSM diagnostic categories: affective, anxiety, pervasive developmental, attention deficit/hyperactivity, and oppositional defiant. All the CBCL scores were corrected for gender, delivery method, gestational age, infant birth weight, occurrence of sepsis, and days on antibiotics prior statistical analyses. Canonical correlation analysis (CCA) was performed to determine the relationship between early life gut microbiome and the adjusted CBCL scores. The association of bacterial Amplicon sequence Variants (ASVs) to the CBCL scores were tested with multivariate analysis by linear models (MaAsLin).

Results

Nineteen children who were previously born with very low birth weight and studied while hospitalized in the Neonatal Intensive Care Unit (NICU) were included in this study. Statistically significant associations were observed between early life gut bacteria such as Veillonella dispar, Enterococcus, Escherichia coli, and Rumincococcus to later behavior at 4 years. No significant association could be observed with early-life gut microbiome alpha diversity and behavioral measures at 4 years.

Discussion

These preliminary observational data provide insight into the relationships between VLBW gut microbiome dysbiosis and childhood behavior. This study contributes to the literature on gut microbiome analysis by examining various behavioral domains using a standardized tool linked to the Diagnostic and Statistical Manual of Mental Disorders (DSM).

Exposure to Antibiotics and Neurodevelopmental Disorders: Could Probiotics Modulate the Gut-Brain Axis?

In order to develop properly, the brain requires the intricate interconnection of genetic factors and pre-and postnatal environmental events. The gut-brain axis has recently raised considerable interest for its involvement in regulating the development and functioning of the brain. Consequently, alterations in the gut microbiota composition, due to antibiotic administration, could favor the onset of neurodevelopmental disorders. Literature data suggest that the modulation of gut microbiota is often altered in individuals affected by neurodevelopmental disorders. It has been shown in animal studies that metabolites released by an imbalanced gut-brain axis, leads to alterations in brain function and deficits in social behavior. Here, we report the potential effects of antibiotic administration, before and after birth, in relation to the risk of developing neurodevelopmental disorders. We also review the potential role of probiotics in treating gastrointestinal disorders associated with gut dysbiosis after antibiotic administration, and their possible effect in ameliorating neurodevelopmental disorder symptoms.

Effects of dietary fiber on intestinal microbiota in geese evaluated by 16SrRNA gene sequencing

AIMS

The purpose of the research is to study the effects of different fiber types and sources on the intestinal flora of geese.

METHODS AND RESULTS

A total of 48 geese (males 35 days old) were divided into 4 groups, each of which included 3 replicates of 4 geese. Groups 1 to 4 were fed a diet containing 5% corn stover Crude fiber (CF, the LJ group), 8% corn stover CF (the HJ group), 5% alfalfa CF (the LM group), or 8% alfalfa CF (the HM group) respectively. After 42 days of feeding, the intestinal flora of each group was determined by 16SrRNA gene sequencing. In the duodenum, the diet supplemented with corn stover meal increased the relative abundance of Proteobacteria, Actinobacteria and Euryarchaeota, and with alfalfa as fiber source increased the relative abundance of Firmicutes, Bacteroidetes, Tenericutes and Chloroflexi. In the jejunum, Bacteroidetes, Actinobacteria, Planctomycetes, Acidobacteria, Tenericutes and Spirochetes were significantly more abundant in the corn stover group. There were no significant differences among the results for the other two fiber sources, which were fibre level in their influence where in ileum. Firmicutes, Deferribacteres and Euryarchaeota with corn stover as fiber source in the cecum were higher than the alfalfa group.

CONCLUSIONS

Different fiber sources have significant effects on goose gut microbiota. There were same flora has the same trend of change in different intestinal segments. The relative fiber source in the ileum makes the gut microbiota more sensitive to differences in fiber levels..

SIGNIFICANCE AND IMPACT OF THE STUDY

This study proved that the dietary fibre affects the intestinal flora. At the same time, different groups of dietary fibre may be used to provide the possibility to study functional roles of specific bacteria in host physiology.

Effects of early-life penicillin exposure on the gut microbiome and frontal cortex and amygdala gene expression

We have established experimental systems to assess the effects of early-life exposures to antibiotics on the intestinal microbiota and gene expression in the brain. This model system is highly relevant to human exposure and may be developed into a preclinical model of neurodevelopmental disorders in which the gut–brain axis is perturbed, leading to organizational effects that permanently alter the structure and function of the brain. Exposing newborn mice to low-dose penicillin led to substantial changes in intestinal microbiota population structure and composition. Transcriptomic alterations implicate pathways perturbed in neurodevelopmental and neuropsychiatric disorders. There also were substantial effects on frontal cortex and amygdala gene expression by bioinformatic interrogation, affecting multiple pathways underlying neurodevelopment. Informatic analyses established linkages between specific intestinal microbial populations and the early-life expression of particular affected genes. These studies provide translational models to explore intestinal microbiome roles in the normal and abnormal maturation of the vulnerable central nervous system.

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Low-dose antibiotic exposure perturbs the infant gut mouse microbiome to PND10

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Frontal cortex and amygdala gene expression were substantially affected

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Multiple pathways underlying neurodevelopment were affected

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Specific gut microbial populations were linked with expression of particular genes

Current Evidence on the Role of the Gut Microbiome in ADHD Pathophysiology and Therapeutic Implications

Studies suggest that the bidirectional relationship existent between the gut microbiome (GM) and the central nervous system (CNS), or so-called the microbiome–gut–brain axis (MGBA), is involved in diverse neuropsychiatric diseases in children and adults. In pediatric age, most studies have focused on patients with autism. However, evidence of the role played by the MGBA in attention deficit/hyperactivity disorder (ADHD), the most common neurodevelopmental disorder in childhood, is still scanty and heterogeneous. This review aims to provide the current evidence on the functioning of the MGBA in pediatric patients with ADHD and the specific role of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) in this interaction, as well as the potential of the GM as a therapeutic target for ADHD. We will explore: (1) the diverse communication pathways between the GM and the CNS; (2) changes in the GM composition in children and adolescents with ADHD and association with ADHD pathophysiology; (3) influence of the GM on the ω-3 PUFA imbalance characteristically found in ADHD; (4) interaction between the GM and circadian rhythm regulation, as sleep disorders are frequently comorbid with ADHD; (5) finally, we will evaluate the most recent studies on the use of probiotics in pediatric patients with ADHD.

The Microbiota and Malnutrition: Impact of Nutritional Status During Early Life

According to the developmental origins of health and disease hypothesis, our health is determined by events experienced in utero and during early infancy. Indeed, both our prenatal and postnatal nutrition conditions have an impact on the initial architecture and activity of our microbiota. Recent evidence has underlined the importance of the composition of the early gut microbiota in relation to malnutrition, whether it be undernutrition or overnutrition, that is, in terms of both stunted and overweight development. It remains unclear how early microbial contact is linked to the risk of disease, as well as whether alterations in the microbiome underlie the pathogenesis of malnutrition or are merely the end result of it, which indicates that thequestion of causality must urgently be answered. This review provides information on the complex interaction between the microbiota and nutrition during the first 1,000 days of life, taking into account the impact of both undernutrition and overnutrition on the microbiota and on infants' health outcomes in the short- and long-term.

Implications of early life stress on fetal metabolic programming of schizophrenia: A focus on epiphenomena underlying morbidity and early mortality

The fetal origin of adult disease hypothesis postulates that a stressful in utero environment can have deleterious consequences on fetal programming, potentially leading to chronic disease in later life. Factors known to impact fetal programming include the timing, intensity, duration and nature of the external stressor during pregnancy. As such, dynamic modulation of fetal programming is heavily involved in shaping health throughout the life course, possibly by influencing metabolic parameters including insulin action, hypothalamic-pituitary-adrenal activity and immune function. The ability of prenatal insults to program adult disease is likely to occur as a result of reduced functional capacity in key organs-a "thrifty" phenotype-where more resources are re-allocated to preserve critical organs such as the brain. Notably, it has been postulated that the manifestation of neuropsychiatric disorders in individuals priorly exposed to prenatal stress may arise from the interaction between hereditary factors and the intrauterine environment, which together precipitate disease onset by disrupting the trajectory of normal brain development. In this review we discuss the evidence linking prenatal programming to neuropsychiatric disorders, mainly schizophrenia, via a "Thrifty psychiatric phenotype" concept. We start by outlining the conception of the thrifty psychiatric phenotype. Next, we discuss the convergence of potential mechanistic pathways through which prenatal insults may trigger epigenetic changes that contribute to the increased morbidity and early mortality observed in neuropsychiatric disorders. Finally, we touch on the public health importance of fetal programming for these disorders. We conclude by providing a brief outlook on the future of this evolving field of research.

Early exposure to food contaminants reshapes maturation of the human brain-gut-microbiota axis

Early childhood growth and development is conditioned by the consecutive events belonging to perinatal programming. This critical window of life will be very sensitive to any event altering programming of the main body functions. Programming of gut function, which is starting right after conception, relates to a very well-established series of cellular and molecular events associating all types of cells present in this organ, including neurons, endocrine and immune cells. At birth, this machinery continues to settle with the establishment of extra connection between enteric and other systemic systems and is partially under the control of gut microbiota activity, itself being under the densification and the diversification of microorganisms' population. As thus, any environmental factor interfering on this pre-established program may have a strong incidence on body functions. For all these reasons, pregnant women, fetuses and infants will be particularly susceptible to environmental factors and especially food contaminants. In this review, we will summarize the actual understanding of the consequences of repeated low-level exposure to major food contaminants on gut homeostasis settlement and on brain/gut axis communication considering the pivotal role played by the gut microbiota during the fetal and postnatal stages and the presumed consequences of these food toxicants on the individuals especially in relation with the risks of developing later in life non-communicable chronic diseases.

The infant gut microbiome as a microbial organ influencing host well-being

Initial establishment of the human gut microbiota is generally believed to occur immediately following birth, involving key gut commensals such as bifidobacteria that are acquired from the mother. The subsequent development of this early gut microbiota is driven and modulated by specific dietary compounds present in human milk that support selective colonization. This represents a very intriguing example of host-microbe co-evolution, where both partners are believed to benefit. In recent years, various publications have focused on dissecting microbial infant gut communities and their interaction with their human host, being a determining factor in host physiology and metabolic activities. Such studies have highlighted a reduction of microbial diversity and/or an aberrant microbiota composition, sometimes referred to as dysbiosis, which may manifest itself during the early stage of life, i.e., in infants, or later stages of life. There are growing experimental data that may explain how the early human gut microbiota affects risk factors related to adult health conditions. This concept has fueled the development of various nutritional strategies, many of which are based on probiotics and/or prebiotics, to shape the infant microbiota. In this review, we will present the current state of the art regarding the infant gut microbiota and the role of key commensal microorganisms like bifidobacteria in the establishment of the first microbial communities in the human gut.

Intake of Vegetables and Fruits Through Young Adulthood Is Associated with Better Cognitive Function in Midlife in the US General Population

BACKGROUND

Vegetables and fruits (VF) may differentially affect cognitive functions, presumably due to their various nutrient contents, but evidence from epidemiologic studies is limited.

OBJECTIVES

The aim of this study was to examine the long-term association between VF intakes, including VF subgroups, in young adulthood and cognitive function in midlife.

METHODS

A biracial cohort of 3231 men and women aged 18-30 y at baseline in 1985-1986 were followed up for 25 y in the Coronary Artery Risk Development in Young Adults Study. Diet was measured at baseline, and in examination years 7 and 20. Cognitive function was assessed at examination year 25 through the use of 3 tests: the Rey Auditory Verbal Learning Test (RAVLT), the Digit Symbol Substitution Test (DSST), and the Stroop test. The mean differences (MDs) with 95% CIs in cognitive scores across intake categories were estimated through the use of the multivariable-adjusted general linear regression model.

RESULTS

Excluding potatoes, intake of whole vegetables was significantly associated with a better cognitive performance after adjustment for potential confounders in all 3 cognitive tests (quintile 5 compared with quintile 1-RAVLT, MD: 0.33; 95% CI: 0.01, 0.64; P-trend = 0.08; DSST, MD: 2.84; 95% CI: 0.93, 4.75; P-trend < 0.01; Stroop test, MD: -2.87; 95% CI: -4.24, -1.50; P-trend < 0.01]. Similarly, intake of fruits, except fruit juices, was significantly related to a better cognitive performance (quintile 5 compared with quintile 1-DSST, MD: 2.41; 95% CI: 0.70, 4.12; P-trend = 0.03).

CONCLUSIONS

This study supports the long-term benefits of VF consumption on cognitive performance, except those VF with relatively low fiber content such as potatoes and fruit juices, among the middle-aged US general population.

The Gut⁻Brain Axis in the Neuropsychological Disease Model of Obesity: A Classical Movie Revised by the Emerging Director "Microbiome"

The worldwide epidemic of obesity has become an important public health issue, with serious psychological and social consequences. Obesity is a multifactorial disorder in which various elements (genetic, host, and environment), play a definite role, even if none of them satisfactorily explains its etiology. A number of neurological comorbidities, such as anxiety and depression, charges the global obesity burden, and evidence suggests the hypothesis that the brain could be the seat of the initial malfunction leading to obesity. The gut microbiome plays an important role in energy homeostasis regulating energy harvesting, fat deposition, as well as feeding behavior and appetite. Dietary patterns, like the Western diet, are known to be a major cause of the obesity epidemic, probably promoting a dysbiotic drift in the gut microbiota. Moreover, the existence of a "gut⁻brain axis" suggests a role for microbiome on hosts' behavior according to different modalities, including interaction through the nervous system, and mutual crosstalk with the immune and the endocrine systems. In the perspective of obesity as a real neuropsychological disease and in light of the discussed considerations, this review focuses on the microbiome role as an emerging director in the development of obesity.

Neonatal gut and respiratory microbiota: coordinated development through time and space

BACKGROUND

Postnatal development of early life microbiota influences immunity, metabolism, neurodevelopment, and infant health. Microbiome development occurs at multiple body sites, with distinct community compositions and functions. Associations between microbiota at multiple sites represent an unexplored influence on the infant microbiome. Here, we examined co-occurrence patterns of gut and respiratory microbiota in pre- and full-term infants over the first year of life, a period critical to neonatal development.

RESULTS

Gut and respiratory microbiota collected as longitudinal rectal, throat, and nasal samples from 38 pre-term and 44 full-term infants were first clustered into community state types (CSTs) on the basis of their compositional profiles. Multiple methods were used to relate the occurrence of CSTs to temporal microbiota development and measures of infant maturity, including gestational age (GA) at birth, week of life (WOL), and post-menstrual age (PMA). Manifestation of CSTs followed one of three patterns with respect to infant maturity: (1) chronological, with CST occurrence frequency solely a function of post-natal age (WOL), (2) idiosyncratic to maturity at birth, with the interval of CST occurrence dependent on infant post-natal age but the frequency of occurrence dependent on GA at birth, and (3) convergent, in which CSTs appear first in infants of greater maturity at birth, with occurrence frequency in pre-terms converging after a post-natal interval proportional to pre-maturity. The composition of CSTs was highly dissimilar between different body sites, but the CST of any one body site was highly predictive of the CSTs at other body sites. There were significant associations between the abundance of individual taxa at each body site and the CSTs of the other body sites, which persisted after stringent control for the non-linear effects of infant maturity. Canonical correlations exist between the microbiota composition at each pair of body sites, with the strongest correlations between proximal locations.

CONCLUSION

These findings suggest that early microbiota is shaped by neonatal innate and adaptive developmental responses. Temporal progression of CST occurrence is influenced by infant maturity at birth and post-natal age. Significant associations of microbiota across body sites reveal distal connections and coordinated development of the infant microbial ecosystem.

Response of goose intestinal microflora to the source and level of dietary fiber

Geese are capable of digesting and making use of a high-fiber diet, but the mechanism is not well understood and would be of great significance for the development and utilization of roughage resources. In this study, we investigated the effect of dietary fiber (source: corn stover and alfalfa, included at 5% or 8%) on microflora in goose intestines. We used 35-day-old Carlos geese in which we first studied the influence of fiber ingestion on diet digestibility and immune organ indices of geese and found that high dietary fiber (8% content) significantly increased feed intake, the digestibility of neutral and acid detergent fiber, and thymus, bursa, and spleen size. Subsequently, we investigated the effect of dietary fiber on the microbial flora in the various intestinal segments by high throughput sequencing. The bacterial diversity and relative abundance were significantly affected by the type and amount of dietary fiber fed, including that of cellulolytic bacteria such as Bacteroides, Ruminococcus, Clostridium, and Pseudomonas spp. Finally, we isolated and identified 8 strains with cellulolytic ability from goose intestine and then analyzed their activities in combination. The optimal combination for cellulase activity was Cerea bacillus and Pseudomonas aeruginosa. This study has laid a theoretical and practical foundation for knowledge of the efficient conversion and utilization of cellulose by geese.

Gut-Brain Psychology: Rethinking Psychology From the Microbiota-Gut-Brain Axis

Mental disorders and neurological diseases are becoming a rapidly increasing medical burden. Although extensive studies have been conducted, the progress in developing effective therapies for these diseases has still been slow. The current dilemma reminds us that the human being is a superorganism. Only when we take the human self and its partner microbiota into consideration at the same time, can we better understand these diseases. Over the last few centuries, the partner microbiota has experienced tremendous change, much more than human genes, because of the modern transformations in diet, lifestyle, medical care, and so on, parallel to the modern epidemiological transition. Existing research indicates that gut microbiota plays an important role in this transition. According to gut-brain psychology, the gut microbiota is a crucial part of the gut-brain network, and it communicates with the brain via the microbiota-gut-brain axis. The gut microbiota almost develops synchronously with the gut-brain, brain, and mind. The gut microbiota influences various normal mental processes and mental phenomena, and is involved in the pathophysiology of numerous mental and neurological diseases. Targeting the microbiota in therapy for these diseases is a promising approach that is supported by three theories: the gut microbiota hypothesis, the "old friend" hypothesis, and the leaky gut theory. The effects of gut microbiota on the brain and behavior are fulfilled by the microbiota-gut-brain axis, which is mainly composed of the nervous pathway, endocrine pathway, and immune pathway. Undoubtedly, gut-brain psychology will bring great enhancement to psychology, neuroscience, and psychiatry. Various microbiota-improving methods including fecal microbiota transplantation, probiotics, prebiotics, a healthy diet, and healthy lifestyle have shown the capability to promote the function of the gut-brain, microbiota-gut-brain axis, and brain. It will be possible to harness the gut microbiota to improve brain and mental health and prevent and treat related diseases in the future.

Impact of prematurity and nutrition on the developing gut microbiome and preterm infant growth

BACKGROUND

Identification of factors that influence the neonatal gut microbiome is urgently needed to guide clinical practices that support growth of healthy preterm infants. Here, we examined the influence of nutrition and common practices on the gut microbiota and growth in a cohort of preterm infants.

RESULTS

With weekly gut microbiota samples spanning postmenstrual age (PMA) 24 to 46 weeks, we developed two models to test associations between the microbiota, nutrition and growth: a categorical model with three successive microbiota phases (P1, P2, and P3) and a model with two periods (early and late PMA) defined by microbiota composition and PMA, respectively. The more significant associations with phase led us to use a phase-based framework for the majority of our analyses. Phase transitions were characterized by rapid shifts in the microbiota, with transition out of P1 occurring nearly simultaneously with the change from meconium to normal stool. The rate of phase progression was positively associated with gestational age at birth, and delayed transition to a P3 microbiota was associated with growth failure. We found distinct bacterial metabolic functions in P1-3 and significant associations between nutrition, microbiota phase, and infant growth.

CONCLUSION

The phase-dependent impact of nutrition on infant growth along with phase-specific metabolic functions suggests a pioneering potential for improving growth outcomes by tailoring nutrient intake to microbiota phase.

The First Microbial Colonizers of the Human Gut: Composition, Activities, and Health Implications of the Infant Gut Microbiota

The human gut microbiota is engaged in multiple interactions affecting host health during the host's entire life span. Microbes colonize the neonatal gut immediately following birth. The establishment and interactive development of this early gut microbiota are believed to be (at least partially) driven and modulated by specific compounds present in human milk. It has been shown that certain genomes of infant gut commensals, in particular those of bifidobacterial species, are genetically adapted to utilize specific glycans of this human secretory fluid, thus representing a very intriguing example of host-microbe coevolution, where both partners are believed to benefit. In recent years, various metagenomic studies have tried to dissect the composition and functionality of the infant gut microbiome and to explore the distribution across the different ecological niches of the infant gut biogeography of the corresponding microbial consortia, including those corresponding to bacteria and viruses, in healthy and ill subjects. Such analyses have linked certain features of the microbiota/microbiome, such as reduced diversity or aberrant composition, to intestinal illnesses in infants or disease states that are manifested at later stages of life, including asthma, inflammatory bowel disease, and metabolic disorders. Thus, a growing number of studies have reported on how the early human gut microbiota composition/development may affect risk factors related to adult health conditions. This concept has fueled the development of strategies to shape the infant microbiota composition based on various functional food products. In this review, we describe the infant microbiota, the mechanisms that drive its establishment and composition, and how microbial consortia may be molded by natural or artificial interventions. Finally, we discuss the relevance of key microbial players of the infant gut microbiota, in particular bifidobacteria, with respect to their role in health and disease.

Foodomics as part of the host-microbiota-exposome interplay

The functional complexity of human gut microbiota and its relationship with host physiology and environmental modulating factors, offers the opportunity to investigate (i) the host and microbiota role in organism-environment relationship; (ii) the individual functional diversity and response to environmental stimuli (exposome); (iii) the host genome and microbiota metagenomes' modifications by diet-mediated epigenomic controls (nutriepigenomics); and (iv) the genotype-phenotype "trajectories" under physiological and disease constraints. Systems biology-based approaches aim at integrating biological data at cellular, tissue and organ organization levels, using computational modeling to interpret diseases' physiopathological mechanisms (i.e., onset and progression). Proteomics improves the existing gene models by profiling molecular phenotypes at protein abundance level, by analyzing post-translational modifications and protein-protein interactions and providing specific pathway information, hence contributing to functional molecular networks. Transcriptomics and metabolomics may determine host ad microbiota changes induced by food ingredients at molecular level, complementing functional genomics and proteomics data. Since foodomics is an -omic wide methodology may feed back all integrative data to foster the omics-based systems medicine field. Hence, coupled to ecological genomics of gut microbial communities, foodomics may highlight health benefits from nutrients, dissecting diet-induced gut microbiota eubiosis mechanisms and significantly contributing to understand and prevent complex disease phenotypes.

BIOLOGICAL SIGNIFICANCE

Besides transcriptomics and proteomics there is a growing interest in applying metabolic profiling to food science for the development of functional foods. Indeed, one of the biggest challenges of modern nutrition is to propose a healthy diet to populations worldwide, intrinsically respecting the high inter-individual variability, driven by complex host/nutrients/microbiota/environment interactions. Therefore, metabolic profiling can assist at various levels for the development of functional foods, starting from screening for food composition to identification of new biomarkers to trace food intake. This current approach can support diet intervention strategies, epidemiological studies, and controlling of metabolic disorders worldwide spreading, hence ensuring healthy aging. With high-throughput molecular technologies driving foodomics, studying bidirectional interactions of host-microbial co-metabolism, innate immune development, dysfunctional nutrient absorption and processing, complex signaling pathways involved in nutritional metabolism, is now likely. In all cases, as microbiome pipeline efforts continue, it is possible that enhanced standardized protocols can be developed, which may lead to new testable biological and clinical hypotheses. This Review provides a comprehensive update on the current state-of-the-art of the integrated -omics route in food, microbiota and host co-metabolism studies, which may revolutionize the design of new dietary intervention strategies.

Developmental Programming, a Pathway to Disease

Accumulating evidence suggests that insults occurring during the perinatal period alter the developmental trajectory of the fetus/offspring leading to long-term detrimental outcomes that often culminate in adult pathologies. These perinatal insults include maternal/fetal disease states, nutritional deficits/excess, stress, lifestyle choices, exposure to environmental chemicals, and medical interventions. In addition to reviewing the various insults that contribute to developmental programming and the benefits of animal models in addressing underlying mechanisms, this review focuses on the commonalities in disease outcomes stemming from various insults, the convergence of mechanistic pathways via which various insults can lead to common outcomes, and identifies the knowledge gaps in the field and future directions.

Obesity Reduces Cognitive and Motor Functions across the Lifespan

Due to a sedentary lifestyle, more and more people are becoming obese nowadays. In addition to health-related problems, obesity can also impair cognition and motor performance. Previous results have shown that obesity mainly affects cognition and motor behaviors through altering brain functions and musculoskeletal system, respectively. Many factors, such as insulin/leptin dysregulation and inflammation, mediate the effect of obesity and cognition and motor behaviors. Substantial evidence has suggested exercise to be an effective way to improve obesity and related cognitive and motor dysfunctions. This paper aims to discuss the association of obesity with cognition and motor behaviors and its underlying mechanisms. Following this, mechanisms of exercise to improve obesity-related dysfunctions are described. Finally, implications and future research direction are raised.

The Endocannabinoid System and Its Role in Regulating the Intrinsic Neural Circuitry of the Gastrointestinal Tract

Endocannabinoids are important neuromodulators in the central nervous system. They regulate central transmission through pre- and postsynaptic actions on neurons and indirectly through effects on glial cells. Cannabinoids (CBs) also regulate neurotransmission in the enteric nervous system (ENS) of the gastrointestinal (GI) tract. The ENS consists of intrinsic primary afferent neurons, interneurons, and motor neurons arranged in two ganglionated plexuses which control all the functions of the gut. Increasing evidence suggests that endocannabinoids are potent neuromodulators in the ENS. In this review, we will highlight key observations on the localization of CB receptors and molecules involved in the synthesis and degradation of endocannabinoids in the ENS. We will discuss endocannabinoid signaling mechanisms, endocannabinoid tone and concepts of CB receptor metaplasticity in the ENS. We will also touch on some examples of enteric neural signaling in relation neuromuscular, secretomotor, and enteroendocrine transmission in the ENS. Finally, we will briefly discuss some key future directions.

Administration of Lactobacillus helveticus NS8 improves behavioral, cognitive, and biochemical aberrations caused by chronic restraint stress

Increasing numbers of studies have suggested that the gut microbiota is involved in the pathophysiology of stress-related disorders. Chronic stress can cause behavioral, cognitive, biochemical, and gut microbiota aberrations. Gut bacteria can communicate with the host through the microbiota-gut-brain axis (which mainly includes the immune, neuroendocrine, and neural pathways) to influence brain and behavior. It is hypothesized that administration of probiotics can improve chronic-stress-induced depression. In order to examine this hypothesis, the chronic restraint stress depression model was established in this study. Adult specific pathogen free (SPF) Sprague-Dawley rats were subjected to 21 days of restraint stress followed by behavioral testing (including the sucrose preference test (SPT), elevated-plus maze test, open-field test (OFT), object recognition test (ORT), and object placement test (OPT)) and biochemical analysis. Supplemental Lactobacillus helveticus NS8 was provided every day during stress until the end of experiment, and selective serotonin reuptake inhibitor (SSRI) citalopram (CIT) served as a positive control. Results showed that L. helveticus NS8 improved chronic restraint stress-induced behavioral (anxiety and depression) and cognitive dysfunction, showing an effect similar to and better than that of CIT. L. helveticus NS8 also resulted in lower plasma corticosterone (CORT) and adrenocorticotropic hormone (ACTH) levels, higher plasma interleukin-10 (IL-10) levels, restored hippocampal serotonin (5-HT) and norepinephrine (NE) levels, and more hippocampal brain-derived neurotrophic factor (BDNF) mRNA expression than in chronic stress rats. Taken together, these results indicate an anti-depressant effect of L. helveticus NS8 in rats subjected to chronic restraint stress depression and that this effect could be due to the microbiota-gut-brain axis. They also suggest the therapeutic potential of L. helveticus NS8 in stress-related and possibly other kinds of depression.

Alterations in the Vaginal Microbiome by Maternal Stress Are Associated With Metabolic Reprogramming of the Offspring Gut and Brain

The neonate is exposed to the maternal vaginal microbiota during parturition, providing the primary source for normal gut colonization, host immune maturation, and metabolism. These early interactions between the host and microbiota occur during a critical window of neurodevelopment, suggesting early life as an important period of cross talk between the developing gut and brain. Because perturbations in the prenatal environment such as maternal stress increase neurodevelopmental disease risk, disruptions to the vaginal ecosystem could be a contributing factor in significant and long-term consequences for the offspring. Therefore, to examine the hypothesis that changes in the vaginal microbiome are associated with effects on the offspring gut microbiota and on the developing brain, we used genomic, proteomic and metabolomic technologies to examine outcomes in our mouse model of early prenatal stress. Multivariate modeling identified broad proteomic changes to the maternal vaginal environment that influence offspring microbiota composition and metabolic processes essential for normal neurodevelopment. Maternal stress altered proteins related to vaginal immunity and abundance of Lactobacillus, the prominent taxa in the maternal vagina. Loss of maternal vaginal Lactobacillus resulted in decreased transmission of this bacterium to offspring. Further, altered microbiota composition in the neonate gut corresponded with changes in metabolite profiles involved in energy balance, and with region- and sex-specific disruptions of amino acid profiles in the developing brain. Taken together, these results identify the vaginal microbiota as a novel factor by which maternal stress may contribute to reprogramming of the developing brain that may predispose individuals to neurodevelopmental disorders.

Dietary fiber is positively associated with cognitive control among prepubertal children

BACKGROUND

Converging evidence now indicates that aerobic fitness and adiposity are key correlates of childhood cognitive function and brain health. However, the evidence relating dietary intake to executive function/cognitive control remains limited.

OBJECTIVE

The current study assessed cross-sectional associations between performance on an attentional inhibition task and dietary fatty acids (FAs), fiber, and overall diet quality among children aged 7-9 y (n = 65).

METHODS

Attentional inhibition was assessed by using a modified flanker task. Three-day food records were used to conduct nutrient-level analyses and to calculate diet quality (Healthy Eating Index-2005) scores.

RESULTS

Bivariate correlations revealed that socioeconomic status and sex were not related to task performance or diet measures. However, age, intelligence quotient (IQ), pubertal staging, maximal oxygen uptake (V̇O2max), and percentage of fat mass (%fat mass) correlated with task accuracy. Hierarchical regression models were used to determine the relation between diet variables and task accuracy and reaction time across both congruent and incongruent trials of the flanker task. After adjustment of confounding variables (age, IQ, pubertal staging, V̇O2max, and %fat mass), congruent accuracy was positively associated with insoluble fiber (β = 0.26, P = 0.03) and total dietary fiber (β = 0.23, P = 0.05). Incongruent response accuracy was positively associated with insoluble fiber (β = 0.35, P < 0.01), pectins (β = 0.25, P = 0.04), and total dietary fiber (β = 0.32, P < 0.01). Higher diet quality was related to lower accuracy interference (β = -0.26, P = 0.03), whereas higher total FA intake was related to greater accuracy interference (β = 0.24, P = 0.04). No statistically significant associations were observed between diet variables and reaction time measures.

CONCLUSION

These results demonstrate that children's diet quality, specifically dietary fiber, is an important correlate of performance on a cognitive task requiring variable amounts of cognitive control.

The human neonatal gut microbiome: a brief review

The field of genomics has expanded into subspecialties such as metagenomics over the course of the last decade and a half. The development of massively parallel sequencing capabilities has allowed for increasingly detailed study of the genome of the human microbiome, the microbial super organ that resides symbiotically within the mucosal tissues and integumentary system of the human host. The gut microbiome, and particularly the study of its origins in neonates, has become subtopics of great interest within the field of genomics. This brief review seeks to summarize recent literature regarding the origins and establishment of the neonatal gut microbiome, beginning in utero, and how it is affected by neonatal nutritional status (breastfed versus formula fed) and gestational age (term versus preterm). We also explore the role of dysbiosis, a perturbation within the fragile ecosystem of the microbiome, and its role in the origin of select pathologic states, specifically, obesity and necrotizing enterocolitis (NEC) in preterm infants. We discuss the evidence supporting enteral pre- and pro-biotic supplementation of commensal organisms such as Bifidobacterium and Lactobacillus in the neonatal period, and their role in the prevention and amelioration of NEC in premature infants. Finally, we review directions to consider for further research to promote human health within this field.

The human gut microbiota: a dynamic interplay with the host from birth to senescence settled during childhood

The microbiota "organ" is the central bioreactor of the gastrointestinal tract, populated by a total of 10(14) bacteria and characterized by a genomic content (microbiome), which represents more than 100 times the human genome. The microbiota plays an important role in child health by acting as a barrier against pathogens and their invasion with a highly dynamic modality, exerting metabolic multistep functions and stimulating the development of the host immune system, through well-organized programming, which influences all of the growth and aging processes. The advent of "omics" technologies (genomics, proteomics, metabolomics), characterized by complex technological platforms and advanced analytical and computational procedures, has opened new avenues to the knowledge of the gut microbiota ecosystem, clarifying some aspects on the establishment of microbial communities that constitute it, their modulation and active interaction with external stimuli as well as food, within the host genetic variability. With a huge interdisciplinary effort and an interface work between basic, translational, and clinical research, microbiologists, specialists in "-omics" disciplines, and clinicians are now clarifying the role of the microbiota in the programming process of several gut-related diseases, from the physiological symbiosis to the microbial dysbiosis stage, through an integrated systems biology approach.

Modulation of gut microbiota in the management of metabolic disorders: the prospects and challenges

The gut microbiota plays a number of important roles including digestion, metabolism, extraction of nutrients, synthesis of vitamins, prevention against pathogen colonization, and modulation of the immune system. Alterations or changes in composition and biodiversity of the gut microbiota have been associated with many gastrointestinal tract (GIT) disorders such as inflammatory bowel disease and colon cancer. Recent evidence suggests that altered composition and diversity of gut microbiota may play a role in the increased prevalence of metabolic diseases. This review article has two main objectives. First, it underscores approaches (such as probiotics, prebiotics, antimicrobial agents, bariatric surgery, and weight loss strategies) and their prospects in modulating the gut microbiota in the management of metabolic diseases. Second, it highlights some of the current challenges and discusses areas of future research as it relates to the gut microbiota and metabolic diseases. The prospect of modulating the gut microbiota seems promising. However, considering that research investigating the role of gut microbiota in metabolic diseases is still in its infancy, more rigorous and well-designed in vitro, animal and clinical studies are needed.

The microbiota-gut-brain axis: neurobehavioral correlates, health and sociality

Recent data suggest that the human body is not such a neatly self-sufficient island after all. It is more like a super-complex ecosystem containing trillions of bacteria and other microorganisms that inhabit all our surfaces; skin, mouth, sexual organs, and specially intestines. It has recently become evident that such microbiota, specifically within the gut, can greatly influence many physiological parameters, including cognitive functions, such as learning, memory and decision making processes. Human microbiota is a diverse and dynamic ecosystem, which has evolved in a mutualistic relationship with its host. Ontogenetically, it is vertically inoculated from the mother during birth, established during the first year of life and during lifespan, horizontally transferred among relatives, mates or close community members. This micro-ecosystem serves the host by protecting it against pathogens, metabolizing complex lipids and polysaccharides that otherwise would be inaccessible nutrients, neutralizing drugs and carcinogens, modulating intestinal motility, and making visceral perception possible. It is now evident that the bidirectional signaling between the gastrointestinal tract and the brain, mainly through the vagus nerve, the so called “microbiota–gut–vagus–brain axis,” is vital for maintaining homeostasis and it may be also involved in the etiology of several metabolic and mental dysfunctions/disorders. Here we review evidence on the ability of the gut microbiota to communicate with the brain and thus modulate behavior, and also elaborate on the ethological and cultural strategies of human and non-human primates to select, transfer and eliminate microorganisms for selecting the commensal profile.

Gut microbiota, probiotics, and human health

The review is devoted to the problems of microbiota and the ways of it correction employing beneficial life bacteria- probiotics. It covers the issues related to the functioning of human microbiota and its importance for the health, individual variability of microbial content, functioning of the probiotics in the human organism and the history of probiotic studies with particular focus on the microbiological investigations in the USSR. The article discusses the safety issues related to probiotics and the problems with probiotic therapy, trying to explain the reasons for the side effects caused by probiotics. The necessity of personified selection of the probiotic strain or individual microbial therapy autoprobiotics is also discussed.

The role of gut microbiota in the gut-brain axis: current challenges and perspectives

Brain and the gastrointestinal (GI) tract are intimately connected to form a bidirectional neurohumoral communication system. The communication between gut and brain, knows as the gut-brain axis, is so well established that the functional status of gut is always related to the condition of brain. The researches on the gut-brain axis were traditionally focused on the psychological status affecting the function of the GI tract. However, recent evidences showed that gut microbiota communicates with the brain via the gut-brain axis to modulate brain development and behavioral phenotypes. These recent findings on the new role of gut microbiota in the gut-brain axis implicate that gut microbiota could associate with brain functions as well as neurological diseases via the gut-brain axis. To elucidate the role of gut microbiota in the gut-brain axis, precise identification of the composition of microbes constituting gut microbiota is an essential step. However, identification of microbes constituting gut microbiota has been the main technological challenge currently due to massive amount of intestinal microbes and the difficulties in culture of gut microbes. Current methods for identification of microbes constituting gut microbiota are dependent on omics analysis methods by using advanced high tech equipment. Here, we review the association of gut microbiota with the gut-brain axis, including the pros and cons of the current high throughput methods for identification of microbes constituting gut microbiota to elucidate the role of gut microbiota in the gut-brain axis.

Mind-altering microorganisms: the impact of the gut microbiota on brain and behaviour

Recent years have witnessed the rise of the gut microbiota as a major topic of research interest in biology. Studies are revealing how variations and changes in the composition of the gut microbiota influence normal physiology and contribute to diseases ranging from inflammation to obesity. Accumulating data now indicate that the gut microbiota also communicates with the CNS--possibly through neural, endocrine and immune pathways--and thereby influences brain function and behaviour. Studies in germ-free animals and in animals exposed to pathogenic bacterial infections, probiotic bacteria or antibiotic drugs suggest a role for the gut microbiota in the regulation of anxiety, mood, cognition and pain. Thus, the emerging concept of a microbiota-gut-brain axis suggests that modulation of the gut microbiota may be a tractable strategy for developing novel therapeutics for complex CNS disorders.