Gut microbiota in autism and mood disorders

The Gut-Eye Axis: Lessons Learned from Murine Models

A healthy gut microbiota is essential in maintaining the human body in a homeostatic state by its functions in digestion and immune tolerance. Under states of aberrant microbial composition or function (dysbiosis), the gut microbiota induces systemic inflammation that can lead to the onset of many diseases. In this review, we describe some evidence, largely from rodent studies, that supports the possible role of a dysbiotic gut microbiota in the onset and exacerbation of ocular diseases, primarily diabetic retinopathy, age-related macular degeneration, choroidal neovascularization, and uveitis. Furthermore, we examine several potential therapeutic measures that show promise in restoring the gut microbiota to a eubiotic state, preventing the aforementioned disease pathologies.

From obesity through gut microbiota to cardiovascular diseases: a dangerous journey

The co-existence of humans and gut microbiota started millions of years ago. Until now, a balance gradually developed between gut bacteria and their hosts. It is now recognized that gut microbiota are key to form adequate immune and metabolic functions and, more in general, for the maintenance of good health. Gut microbiota are established before birth under the influence of maternal nutrition and metabolic status, which can impact the future metabolic risk of the offspring in terms of obesity, diabetes, and cardiometabolic disorders during the lifespan. Obesity and diabetes are prone to disrupt the gut microbiota and alter the gut barrier permeability, leading to metabolic endotoxaemia with its detrimental consequences on health. Specific bacterial sequences are now viewed as peculiar signatures of the metabolic syndrome across life stages in each individual, and are linked to pathogenesis of cardiovascular diseases (CVDs) via metabolic products (metabolites) and immune modulation. These mechanisms have been linked, in association with abnormalities in microbial richness and diversity, to an increased risk of developing arterial hypertension, systemic inflammation, nonalcoholic fatty liver disease, coronary artery disease, chronic kidney disease, and heart failure. Emerging strategies for the manipulation of intestinal microbiota represent a promising therapeutic option for the prevention and treatment of CVD especially in individuals prone to CV events.

Effects of octylphenol exposure on the lipid metabolism and microbiome of the intestinal tract of Rana chensinensis tadpole by RNAseq and 16s amplicon sequencing

Octylphenol (OP) is a widely distributed endocrine disrupting chemical (EDC), and can be commonly found in various and diverse environmental media. Previous studies have reported that OP exposure could cause many adverse effects on aquatic animals. However, knowledge concerning the impact of OP on lipid metabolism in amphibians was still limited. In our study, Rana chensinensis tadpoles were exposed to different OP concentrations (0, 10^-8, 10^-7 and 10^-6 mol/L) from the Gosner stage (Gs) 25-38. The RNA-seq analysis of tadpole intestines was explored by RNA-seq, and six differentially expressed genes (DEGs) related to the fat digestion and absorption were validated by RT-qPCR. Moreover, we used 16s amplicon sequencing to evaluate effects of OP on intestinal microbiome in tadpoles, further determining the variations of lipid metabolism. Our results revealed that OP exposure influenced gene expression levels related to fat digestion and absorption and led to alteration of structure and composition of intestinal microbiome. At the phylum level, the Firmicutes/Bacteroidetes ratio was gradually decreased in OP exposure groups, which disrupted lipid metabolism. According to the results of intestinal microbial functional prediction, OP exposure interfered with metabolic function and increased risk of disease. These data provide us with powerful resources to assess the effects of OP on lipid metabolism by integrating RNAseq and 16s amplicon sequencing analysis of intestinal tract and intestinal microbiome.

Porphyromonas: A neglected potential key genus in human microbiomes

Anaerobes form a large part of microbial communities, and have begun to be specifically studied in both healthy and pathologic contexts. Porphyromonas is one of the top ten anaerobic taxa in the microbiome (anaerobiome) in healthy subjects. However, to date, most studies focused on the deleterious role of P. gingivalis, the most widely described species. Interestingly, targeted metagenomics reveals Porphyromonas other than gingivalis (POTG), highlighting other species such as P. catoniae or P. pasteri as potential biomarkers in disease progression or pathogen colonization susceptibility. From the sparse data, it appears that the Porphyromonas genus may also be a relevant target of investigation in several pulmonary diseases. Moreover, deciphering cutaneous, gastric and oral microbiomes hint that Porphyromonas may be a genus of interest in non-pulmonary diseases. This review aims to summarize the major data on POTG and to report their impact on the various human microbiomes in different clinical states.

Bridging the Gap Between Physical Health and Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a highly complex and heterogeneous developmental disorder that affects how individuals communicate with other people and relate to the world around them. Research and clinical focus on the behavioural and cognitive manifestations of ASD, whilst important, have obscured the recognition that ASD is also commonly associated with a range of physical and mental health conditions. Many physical conditions appear with greater frequency in individuals with ASD compared to non-ASD populations. These can contribute to a worsening of social communication and behaviour, lower quality of life, higher morbidity and premature mortality. We highlight some of the key physical comorbidities affecting the immune and the gastrointestinal systems, metabolism and brain function in ASD. We discuss how healthcare professionals working with individuals with ASD and parents/carers have a duty to recognise their needs in order to improve their overall health and wellbeing, deliver equality in their healthcare experiences and reduce the likelihood of morbidity and early mortality associated with the condition.

The Promising Role of Probiotics in Managing the Altered Gut in Autism Spectrum Disorders

Gastrointestinal symptoms (GIS) have been reported repeatedly in people with autism spectrum disorder (ASD) and studies have reported interesting correlations between severity of behavioral and gastrointestinal symptoms. Growing evidence indicates that the gut microbiota in ASD is altered with various shifts described at different taxonomic levels, pointing to the importance of considering the gut-brain axis in treatment of these disorders. Probiotics are live beneficial bacteria that are ingested as food or customized pills. These beneficial bacteria, when added in sufficient amounts, can correct the dysbiosis. Because probiotics have shown success in treating irritable bowel syndrome (IBS), it is plausible to investigate whether they can induce alleviation of behavioral symptoms as well. Probiotics show, in some clinical studies, their potential benefits (1) in improving gastrointestinal dysfunction, (2) in correcting dysbiosis, (3) in consequently reducing the severity of ASD symptoms. This review compiles data from selected studies that investigate these benefits and the mechanisms that mediate these effects, which include the production of metabolites, hormones, and neurotransmitters and the regulation of pro-inflammatory and regulatory cytokines. Future research based on more randomized, controlled studies with a larger population size and standardized use of strains, concentration of probiotics, duration of treatments, and methods of DNA extraction is still needed in this area, which may lead to more robust results.

Comparative analysis of microbial community structure between healthy and Aeromonas veronii-infected Yangtze finless porpoise

Background

The gut microbiota is a complex ecosystem, which is essential for the metabolism, health and immunity of host. Many diseases have been shown to be closely related to the alteration of intestinal flora. Aeromonas veronii as a conditioned pathogen can cause disease in Yangtze finless porpoise through intestinal infections. However, it is not clear whether the disease caused by Aeromonas veronii is related to changes of intestinal flora. In the current study, the diversity and composition of gut microbiota in the healthy and Aeromonas veronii-infected Yangtze finless porpoise were evaluated by high-throughput sequencing to further investigate the potential association between intestinal flora alteration and pathogen invasion.

Results

A total of 127,3276 high-quality sequences were achieved and 2465 operational taxonomic units (OTUs) were in common among all samples. The results of alpha diversity showed that there was no obvious difference in richness and diversity between healthy and Aeromonas veronii-infected Yangtze finless porpoise. Firmicutes, Bacteroidetes and Proteobacteria were the most dominant phyla in all samples. In addition, the healthy Yangtze finless porpoise exhibited higher abundance of Firmicutes and Fusobacteria than Aeromonas veronii-infected Yangtze finless porpoise, while, the level of Proteobacteria was decreased. At the genus level, Paeniclostridium and Paraclostridium were the predominant bacteria genera in the CK (healthy Yangtze finless porpoise) group. In the DIS (Aeromonas veronii-infected Yangtze finless porpoise) group, Lactobacillus and unidentified_Enterobacteriaceae were the dominant bacteria genera and the proportion of Paeniclostridium, Paraclostridium, Terrisporobacter, Cetobacterium, Candidatus Arthromitus, Terrabacter and Dechloromonas were reduced.

Conclusions

In conclusion, our results showed that Aeromonas veronii infection can alter the gut microbiota of the Yangtze finless porpoise by affecting the number of harmful bacteria and beneficial bacteria.

A metabolomics approach to investigate urine levels of neurotransmitters and related metabolites in autistic children

Since recently metabolic abnormalities in autistic children have been associated with ASD disturbs, the aim of this study is to determine the neurotransmitter levels in urine samples of autistic children and to analyse the altered metabolic pathway involved in their production. Thus, ASD-specific urinary metabolomic patterns were explored in 40 ASD children and 40 matched controls using untargeted metabolomics through UHPLC-mass spectrometry (Q-exactive analyser), and by using XCMS Metlin software for data interpretation. Through this new advanced technique, a more considerable number of urinary altered metabolites were recorded in autistic children, than in the previous investigations, which allowed us to collect metabolites involved in neurotransmitter production. In these subjects, a high amount of dopamine was revealed and an increased amount of homovanillic acid, to the detriment of noradrenaline and adrenaline production, as well as MHPG and vanillylmandelic acid, which were found lower. This indicates that the accumulation of dopamine is not due to its greater production, but its lesser biotransformation into noradrenaline, due to the blockage of the dopamine β-hydroxylase enzyme by 4-cresol and vitamin C, both found in high quantities in autistic subjects. Finally, a decreased amount of the active form of vitamin B6, pyridoxal phosphate (P5P), implicated in biotransformation of glutamate into γ-aminobutyric acid (GABA), was also detected, justifying the lower levels of latter. All of these alterations are correlated with a peculiar intestinal microbiome in autistic subjects, supporting the idea of a microbiota-gut-brain axis, then altered levels of neurotransmitters and altered neuronal transmission exist.

Gut Microbiota: A Pivotal Hub for Polyphenols as Antidepressants

Polyphenols, present in a broad range of plants, have been thought to be responsible for many beneficial health effects, such as an antidepressant. Despite that polyphenols can be absorbed in the small intestine directly, most of them have low bioavailability and reach the large intestine without any modifications due to their complex structures. The interaction between microbial communities and polyphenols in the intestine is important for the latter to exert antidepressant effects. Gut microbiota can improve the bioavailability of polyphenols; in turn, polyphenols can maintain the intestinal barrier as well as the community of the gut microbiota in normal status. Furthermore, gut microbita catabolize polyphenols to more active, better-absorbed metabolites, further ameliorating depression through the microbial-gut-brain (MGB) axis. Based on this evidence, the review illustrates the potential role of gut microbiota in the processes of polyphenols or their metabolites acting as antidepressants and further envisions the gut microbiota as therapeutic targets for depression.

Anesthesia and surgery induce cognitive dysfunction in elderly male mice: the role of gut microbiota

It is well known that the incidence of postoperative cognitive dysfunction (POCD) is high in elderly patients. The pathogenesis and therapeutic mechanisms of POCD, however, have not yet been completely elucidated. The effects of gut microbiota, particularly in terms of regulating brain function, have gradually attracted increasing attention. In this study, we investigated the potential role of gut microbiota in POCD in aged male mice and attempted to determine whether alterations in gut microbiota would be helpful in the diagnosis of POCD. POCD and non-POCD mice were classified by hierarchical cluster analysis of behavioral results. Additionally, α- and β-diversity of gut microbiota showed a differential profile between the groups. In total, 24 gut bacteria were significantly altered in POCD mice compared with those in non-POCD mice, in which 13 gut bacteria were significantly correlated with escape latency in the Morris water maze test (MWMT). Remarkably, receiver operating characteristic curves revealed that the Dehalobacteriaceae family and Dehalobacterium genus are potentially important bacteria for the diagnosis of POCD. These findings indicate that alterations in the composition of gut microbiota are probably involved in the pathogenesis of POCD in aged mice. Novel therapeutic strategies regulating specific gut bacteria may be helpful for the prevention and treatment of POCD.

Gut Microbial Profiles in Nereis succinea and Their Contribution to the Degradation of Organic Pollutants

Gut microbiota of wildlife are usually exposed to and involved in degrading environmental pollutants, yet their biodegrading capacity remains largely unexplored. Here, we analyzed gut microbial profiles of a marine benthic polychaete, Nereis succinea, and elaborated the capacity of gut microbiota in degrading various organic pollutants, including polycyclic aromatic hydrocarbons, pesticides, phenols, and synthetic musks. High-throughput sequencing analysis revealed that the structures of microbial communities, including bacteria, fungi, and archaea, varied along the gut, manifesting distinct structural features in the fore-, mid-, and hindgut regions. Community-level physiological profiles and the capacity of gut microbiota in degrading the pollutants showed profound gut region and oxygen dependent features. In general, anaerobes were more active in degrading the pollutants, and those in the midgut presented the maximum degrading potential. Degradation capability of the gut microbiota was further quantitatively validated in an in vitro culture system using chlorpyrifos and malathion as representative compounds. Our results demonstrated a potential impact of gut microbiota in wildlife on the fate of organic pollutants in the ecosystem, which calls for further research on the influences of gut microbiota on biotransformation and bioaccumulation of xenobiotics in organisms.

Targeting the microbiota in pharmacology of psychiatric disorders

There is increasing interest in the role of the gut microbiota in health and disease. In particular, gut microbiota influences the Central Nervous System (CNS) development and homeostasis through neural pathways or routes involving the immune and circulatory systems. The CNS, in turn, shapes the intestinal flora through endocrine or stress-mediated responses. These overall bidirectional interactions, known as gut microbiota-brain axis, profoundly affect some brain functions, such as neurogenesis and the production of neurotransmitters, up to influence behavioral aspects of healthy subjects. Consequently, a dysfunction within this axis, as observed in case of dysbiosis, can have an impact on the behavior of a given individual (e.g. anxiety and depression) or on the development of pathologies affecting the CNS, such as autism spectrum disorders and neurodegenerative diseases (e.g. Alzheimer's disease and Parkinson's disease). It should be considered that the whole microbiota has a significant role not only on aspects concerning human physiology, such as harvesting of nutrients and energy from the ingested food or production of a wide range of bioactive compounds, but also has positive effects on the gastrointestinal barrier function and actively contributes to the pharmacokinetics of several compounds including neuropsychiatric drugs. Indeed, the microbiota is able to affect drug absorption and metabolism up to have an impact on drug activity and/or toxicity. On the other hand, drugs are able to shape the human gut microbiota itself, where these changes may contribute to their pharmacologic profile. Therefore, the emerging picture on the complex drug-microbiota bidirectional interplay will have considerable implications in the future not only in terms of clinical practice but also, upstream, on drug development.

An approach to gut microbiota profile in children with autism spectrum disorder

In recent years, there has been an increase in studies on the implications of gut microbiota (GM) on the behaviour of children with autism spectrum disorders (ASD) due to a dysbiosis in GM that can trigger onset, development or progression of ASD through the microbiota-gut-brain axis. The aim of this study is to carry out a systematic review of articles from the last 6 years that analyse GM in children with ASD compared to GM in control groups. Children with ASD showed a higher abundance of Roseburia and Candida genera, and lower abundance of Dialister, Bilophila, Veillonella, Streptococcus, Coprococcus and Prevotella genera. Those differences can be attributed to factors such as different nationalities, nature of control groups, place where the sample was taken, gastrointestinal (GI) problems or bacterial detection methods. It is still too early to define a specific GM profile of children with ASD, and future studies should focus on homogenizing the characteristics of samples and control groups. Furthermore, new multicentre studies should also focus on the impact of GM on GI physiology, neurophysiology and behaviour of children with ASD, and on performing psychometric analyses of the correlation between the severity of ASD behavioural symptoms and GM profiles.

The Application of Metabolomics to Probiotic and Prebiotic Interventions in Human Clinical Studies

There is an ever-increasing appreciation for our gut microbiota that plays a crucial role in the maintenance of health, as well as the development of disease. Probiotics are live bacteria that are consumed to increase the population of beneficial bacteria and prebiotics are dietary substrates intended to promote the propagation of beneficial bacteria. In order to optimize the use of probiotics and prebiotics, a more complete biochemical understanding of the impact that these treatments have on the community and functioning of the gut microbiota is required. Nucleic acid sequencing methods can provide highly detailed information on the composition of the microbial communities but provide less information on the actual function. As bacteria impart much of their influence on the host through the production of metabolites, there is much to be learned by the application of metabolomics. The focus of this review is on the use of metabolomics in the study of probiotic and prebiotic treatments in the context of human clinical trials. Assessment of the current state of this research will help guide the design of future studies to further elucidate the biochemical mechanism by which probiotics and prebiotics function and pave the way toward more personalized applications.

Treatment with the traditional Chinese medicine BuYang HuanWu Tang induces alterations that normalize the microbiome in ASD patients

Autism spectrum disorders (ASDs) are prevalent neurobiological conditions with complicated causes worldwide. Increasing researcher awareness of ASD and accumulated evidence suggest that the development of ASD may be strongly linked to the dysbiosis of the gut microbiota. In addition, most of the current studies have compared autistic children and neurotypical children or have compared ASD patients before and after antibiotic treatment. Treatment of autism with traditional Chinese medicine (TCM) has increasingly been promoted, but the relationship between its efficacy and intestinal flora has rarely been reported. Under the premise that treatment with the TCM BuYang HuanWu Tang is effective, we conducted a comparative bioinformatics analysis to identify the overall changes in gut microbiota in relation to ASD by comparing the intestinal flora before and after treatment with TCM and contrasting the intestinal flora with that of healthy controls. At the phylum level, Proteobacteria showed a significant increase in children with ASD, which may be a signature of dysbiosis in the gut microbiota. At the genus level, Blautia, Coprococcus 1, the Lachnospiraceae family, and the Ruminococcaceae family were found at the lowest levels of relative abundance in children with ASD, whereas the abundances of Escherichia-Shigella, Klebsiella, and Flavonifractor were significantly increased compared with those in the healthy control group. In sum, this study characterized the alterations of the intestinal microbiome in children with ASD and its normalization after TCM treatment (TCMT), which may provide novel insights into the diagnosis and therapy of ASD.

Impact of Clostridium Bacteria in Children with Autism Spectrum Disorder and Their Anthropometric Measurements

Current research has shown that gut microbiota may play a fundamental role in neurological activity, behavior, mood, cognition, and possibly for the onset as well as the severity of autism spectrum disorder (ASD). Previous studies emphasized the possible correlation between Clostridium spp., gut colonization, and possible development or exacerbating of ASD in affected children. The aim of the present study was to investigate how Clostridia gut colonization can have an impact on the neurological outcome and anthropometric values in ASD children. The present study included 60 children (30 ASD and 30 neurotypical controls) of both sexes aged from 2 to 8 years. Children with ASD were diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5), Autism Diagnostic Interview-Revised (ADI-R), as well as the Childhood Autism Rating Scale (CARS). Quantitative real-time polymerase chain reaction (real-time PCR) was used to determine Clostridium presence in the stools of the enrolled subjects. The number of Clostridium spp. (Clostridium paraputri, Clostridium bolteae, and Clostridium perfringens) found in the stools of ASD children was greater than neurotypical children. Children with ASD had two types of Clostridium (Clostridium diffiicile and Clostridium clostridiioforme) not found in neurotypical children, whereas neurotypical children yielded only one species (Clostridium tertium) not found in the ASD children. The present study emphasizes the potential correlation between gut colonization of Clostridia and the probability of developing or exacerbating ASD among Egyptian children. If Clostridium bacteria play a potential role in the etiology of ASD, this may open the possibility for effective treatment of these patients.

Epigenetic programming-The important first 1000 days

The perinatal period is a time of fast physiological change, including epigenetic programming. Adverse events may lead to epigenetic changes, with implications for health and disease. Our review covers the basics of clinical epigenetics and explores the latest research, including the role of epigenetic processes in complex disease phenotypes, such as neurodevelopmental, neurodegenerative and immunological disorders. Some studies suggest that epigenetic alterations are linked to early life environmental stressors, including mode of delivery, famine, psychosocial stress, severe institutional deprivation and childhood abuse. CONCLUSION: Epigenetic modifications due to perinatal environmental exposures can lead to lifelong, but potentially reversible, phenotypic alterations and disease.

Host and body site-specific adaptation of Lactobacillus crispatus genomes

Lactobacillus crispatus is a common inhabitant of both healthy poultry gut and human vaginal tract, and the absence of this species has been associated with a higher risk of developing infectious diseases. In this study, we analyzed 105 L. crispatus genomes isolated from a variety of ecological niches, including the human vaginal tract, human gut, chicken gut and turkey gut, to shed light on the genetic and functional features that drive evolution and adaptation of this important species. We performed in silico analyses to identify the pan and core genomes of L. crispatus, and to reveal the genomic differences and similarities associated with their origins of isolation. Our results demonstrated that, although a significant portion of the genomic content is conserved, human and poultry L. crispatus isolates evolved to encompass different genomic features (e.g. carbohydrate usage, CRISPR-Cas immune systems, prophage occurrence) in order to thrive in different environmental niches. We also observed that chicken and turkey L. crispatus isolates can be differentiated based on their genomic information, suggesting significant differences may exist between these two poultry gut niches. These results provide insights into host and niche-specific adaptation patterns in species of human and animal importance.

Neuroinflammation in Murine Cirrhosis Is Dependent on the Gut Microbiome and Is Attenuated by Fecal Transplant

Cirrhosis and hepatic encephalopathy (HE) is associated with an altered gut-liver-brain axis. Fecal microbial transplant (FMT) after antibiotics improves outcomes in HE, but the impact on brain function is unclear. The aim of this study is to determine the effect of colonization using human donors in germ-free (GF) mice on the gut-liver-brain axis. GF and conventional mice were made cirrhotic using carbon tetrachloride and compared with controls in GF and conventional state. Additional GF mice were colonized with stool from controls (Ctrl-Hum) and patients with cirrhosis (Cirr-Hum). Stools from patients with HE cirrhosis after antibiotics were pooled (pre-FMT). Stools from the same patients 15 days after FMT from a healthy donor were also pooled (post-FMT). Sterile supernatants were created from pre-FMT and post-FMT samples. GF mice were colonized using stools/sterile supernatants. For all mice, frontal cortex, liver, and small/large intestines were collected. Cortical inflammation, synaptic plasticity and gamma-aminobutyric acid (GABA) signaling, and liver inflammation and intestinal 16s ribosomal RNA microbiota sequencing were performed. Conventional cirrhotic mice had higher degrees of neuroinflammation, microglial/glial activation, GABA signaling, and intestinal dysbiosis compared with other groups. Cirr-Hum mice had greater neuroinflammation, microglial/glial activation, and GABA signaling and lower synaptic plasticity compared with Ctrl-Hum mice. This was associated with greater dysbiosis but no change in liver histology. Pre-FMT material colonization was associated with neuroinflammation and microglial activation and dysbiosis, which was reduced significantly with post-FMT samples. Sterile pre-FMT and post-FMT supernatants did not affect brain parameters. Liver inflammation was unaffected. Conclusion: Fecal microbial colonization from patients with cirrhosis results in higher degrees of neuroinflammation and activation of GABAergic and neuronal activation in mice regardless of cirrhosis compared with those from healthy humans. Reduction in neuroinflammation by using samples from post-FMT patients to colonize GF mice shows a direct effect of fecal microbiota independent of active liver inflammation or injury.

Organ-level protein networks as a reference for the host effects of the microbiome

Connections between the microbiome and health are rapidly emerging in a wide range of diseases. However, a detailed mechanistic understanding of how different microbial communities are influencing their hosts is often lacking. One method researchers have used to understand these effects are germ-free (GF) mouse models. Differences found within the organ systems of these model organisms may highlight generalizable mechanisms that microbiome dysbioses have throughout the host. Here, we applied multiplexed, quantitative proteomics on the brains, spleens, hearts, small intestines, and colons of conventionally raised and GF mice, identifying associations to colonization state in over 7000 proteins. Highly ranked associations were constructed into protein–protein interaction networks and visualized onto an interactive 3D mouse model for user-guided exploration. These results act as a resource for microbiome researchers hoping to identify host effects of microbiome colonization on a given organ of interest. Our results include validation of previously reported effects in xenobiotic metabolism, the innate immune system, and glutamate-associated proteins while simultaneously providing organism-wide context. We highlight organism-wide differences in mitochondrial proteins including consistent increases in NNT, a mitochondrial protein with essential roles in influencing levels of NADH and NADPH, in all analyzed organs of conventional mice. Our networks also reveal new associations for further exploration, including protease responses in the spleen, high-density lipoproteins in the heart, and glutamatergic signaling in the brain. In total, our study provides a resource for microbiome researchers through detailed tables and visualization of the protein-level effects of microbial colonization on several organ systems.

Psychobiotics Regulate the Anxiety Symptoms in Carriers of Allele A of IL-1β Gene: A Randomized, Placebo-Controlled Clinical Trial

Background

Probiotic oral intake, via modulation of the microbiota-gut-brain axis, can impact brain activity, mood, and behavior; therefore, it may be beneficial against psychological distress and anxiety disorders. Inflammatory cytokines can influence the onset and progression of several neurodegenerative mood disorders, and the IL-1β rs16944 SNP is related to high cytokine levels and potentially affects mood disorders. The aim of this study was to examine the combined effect of IL-1β polymorphism and probiotic administration in mood disorder phenotypes in the Italian population.

Methods

150 subjects were randomized into two different groups, probiotic oral suspension group (POSG) and placebo control group (PCG), and received the relative treatment for 12 weeks. Psychological profile assessment by Hamilton Anxiety Rating Scale (HAM-A), Body Uneasiness Test (BUT), and Symptom Checklist 90-Revised (SCL90R) was administered to all volunteers. Genotyping was performed on DNA extracted from salivary samples.

Results

After 12 weeks of intervention, a significant reduction of HAM-A total score was detected in the POSG (p < 0.01), compared to the PCG. Furthermore, IL-1β carriers have moderate risk to develop anxiety (OR = 5.90), and in POSG IL-1β carriers, we observed a reduction of HAM-A score (p = 0.02).

Conclusions

Consumption of probiotics mitigates anxiety symptoms, especially in healthy adults with the minor A allele of rs16944 as a risk factor. Our results encourage the use of probiotics in anxiety disorders and suggest genetic association studies for psychobiotic-personalized therapy.

Plasma trimethylamine N-oxide, a gut microbe-generated phosphatidylcholine metabolite, is associated with autism spectrum disorders

OBJECTIVE

The compositions of the gut microbiota and its metabolites were altered in individuals with Autism Spectrum Disorder (ASD). The aim of this study was to assess whether plasma levels of gut-derived metabolite trimethylamine N-oxide (TMAO) were associated with ASD and the degree of symptom severity.

METHODS

From September 2017 to January 2019, a total of three hundred and twenty-eight Chinese children (164 with ASD and 164 their age-sex matched control subjects) aged 3-8 years were included. TMAO levels in plasma were determined using high-performance liquid chromatography tandem mass spectrometry (LC/MS/MS). Logistic regression analysis was used to examine the TMAO-ASD association.

RESULTS

In the study, the median age of the ASD group was 5 years (interquartile range [IQR], 4-6 years) and 129 (78.7%) were boys. The median plasma levels of TMAO in children with ASD and typically-developing (TD) children at admission were 4.2 (IQR, 3.0-5.6) μmol/l and 3.0 (2.0-4.4) μmol/l, respectively (P < 0.001). For each 1 μmol/l increase of plasma TMAO, the unadjusted and adjusted risk of ASD would be increased by 54% (with the odds ratios [OR] of 1.54; 95% confidence intervals [CI]: 1.32-1.78; P < 0.001) and 27% (1.27 [1.10-1.45], P < 0.001), respectively. Symptom severity was classified as mild-to-moderate (CARS < 37) for 66 children with ASD (40.2%). In these children, the plasma levels of TMAO were lower than in the 98 children with ASD (59.8%) whose symptoms were classified as severe (CARS > 36) (3.5[2.5-4.9] μmol/l vs. 4.5(3.7-6.0) μmol/l; P < 0.001). For each 1 μmol/l increase of plasma TMAO, the unadjusted and adjusted risk of severe autism would be increased by 61% (with the OR of 1.61 [95% CI 1.28-2.01], P < 0.001) and 31% (1.31 [1.08-1.49], P < 0.001), respectively.

CONCLUSIONS

Elevated plasma levels of TMAO were associated with ASD and symptom severity.

Vitamin D and Depression in Women: A Mini-review

Affective-related disorders, including depression, are constantly rising, complicating people's personal lifestyle increasing disqualification and hospital care. Because of the high intensity of urbanization, our lifestyle and food have altered dramatically in the last twenty years. These food modifications have been associated with scores of depression and other affective-related disorders in urbanized countries with high economic levels. Nutrients imbalance is considered as one of the critical causes enabling the pathophysiological mechanisms for the development of psychiatric disorders. The application of additional nutritional interventions for treatment of mood deteriorations can be beneficial for both the prophylaxis and therapy of affective-related disorders. This paper will review recent research on the relation of Vitamin D levels and the epidemiology of depression in women. In this paper, we will provide an overview of the results of a variety of different studies taking into account research which both suggests and refutes an association. Based on these findings we will propose important directions for future research in relation to this topic.

Novel aspects of enteric serotonergic signaling in health and brain-gut disease

Gastrointestinal (GI) comorbidities are common in individuals with mood and behavioral dysfunction. Similarly, patients with GI problems more commonly suffer from co-morbid psychiatric diagnoses. Although the central and enteric nervous systems (CNS and ENS, respectively) have largely been studied separately, there is emerging interest in factors that may contribute to disease states involving both systems. There is strong evidence to suggest that serotonin may be an important contributor to these brain-gut conditions. Serotonin has long been recognized for its critical functions in CNS development and function. The majority of the body's serotonin, however, is produced in the GI tract, where it plays key roles in ENS development and function. Further understanding of the specific impact that enteric serotonin has on brain-gut disease may lay the foundation for the creation of novel therapeutic targets. This review summarizes the current data focusing on the important roles that serotonin plays in ENS development and motility, with a focus on novel aspects of serotonergic signaling in medical conditions in which CNS and ENS co-morbidities are common, including autism spectrum disorders and depression.

Microbiota and gut-brain axis dysfunction in autism spectrum disorder: Evidence for functional gastrointestinal disorders

INTRODUCTION

The high frequency of functional gastrointestinal disorders (FGIDs) in autism spectrum disorders (ASD) has drawn attention to the composition of gut microbiota as a possible factor in ASD pathogenesis. However, characterization of a distinctive ASD microbial pattern is still unclear.

OBJECTIVE

To conduct a narrative review on ASD microbial profile and diversity changes relative to NT children and FGID comorbidity and ASD pathogenesis.

METHODOLOGY

First, we searched the PubMed database in peer-reviewed journals for evidence regarding the current epidemiological evidence on FGID comorbidity. For the identification of a microbial profile in ASD children, only original studies examining gut bacterial and fungal abundances and diversity in ASD children and adolescents were included. Lastly, research on the role of microbial dysbiosis as an interface between genetic and environmental risk factors in the pathogenesis of neuropsychiatric disorders, and specifically ASD, was examined.

RESULTS

Prevalence and risk of FGIDs is significantly higher in ASD children and correlates with the severity of ASD. Bacterial and fungal diversity differ between ASD and NT children, indicating a difference in taxonomic abundance profiles, which have been reported at all bacterial phylogenetic levels. However, studies analyzing gut microbiota have a heterogeneous methodology and several limitations that could account for the variety of findings for each taxon. Also, covariate analysis reveals influence of demographics, diet, disease severity, GI comorbidity and allergies. Integration of these findings with changes in metabolome and genetic risk factors allowed for a better understanding of microbiota involvement in ASD pathogenesis for future research.

Gut microbiota and neurological effects of glyphosate

There are currently various concerns regarding certain environmental toxins and the possible impact they can have on developmental diseases. Glyphosate (Gly) is the most utilised herbicide in agriculture, although its widespread use is generating controversy in the scientific world because of its probable carcinogenic effect on human cells. Gly performs as an inhibitor of 5-enolpyruvylshikimate-3-phospate synthase (EPSP synthase), not only in plants, but also in bacteria. An inhibiting effect on EPSP synthase from intestinal microbiota has been reported, affecting mainly beneficial bacteria. To the contrary, Clostridium spp. and Salmonella strains are shown to be resistant to Gly. Consequently, researchers have suggested that Gly can cause dysbiosis, a phenomenon which is characterised by an imbalance between beneficial and pathogenic microorganisms. The overgrowth of bacteria such as clostridia generates high levels of noxious metabolites in the brain, which can contribute to the development of neurological deviations. This work reviews the impact of Gly-induced intestinal dysbiosis on the central nervous system, focusing on emotional, neurological and neurodegenerative disorders. A wide variety of factors were investigated in relation to brain-related changes, including highlighting genetic abnormalities, pregnancy-associated problems, diet, infections, vaccines and heavy metals. However, more studies are required to determine the implication of the most internationally used herbicide, Gly, in behavioural disorders.

Dietary Recombinant Phycoerythrin Modulates the Gut Microbiota of H22 Tumor-Bearing Mice

Normal intestinal flora is widely involved in many functions of the host: nutritional metabolism; maintenance of intestinal microecological balance; regulation of intestinal endocrine function and nerve signal transduction; promotion of intestinal immune system development and maturation; inhibition of pathogenic bacteria growth and colonization, reduction of its invasion to intestinal mucosa, and so on. In recent years, more and more studies have shown that intestinal flora is closely related to the occurrence, development, and treatment of various tumors. It is indicated that recombinant phycoerythrin (RPE) has significant anti-tumor and immunomodulatory effects. However, little is known about the mechanism of the effect of oral (or intragastric) administration of RPE on gut microbiota in tumor-bearing animals. In this study, using high-throughput 16S rDNA sequencing, we examined the response of gut microbiota in H22-bearing mice to dietary RPE supplementation. The results showed that the abundance of beneficial bacteria in the mice intestinal flora decreased and that of the detrimental flora increased after inoculation with tumor cells (H22); following treatment with dietary RPE, the abundance of beneficial bacteria in the intestinal flora significantly increased and that of detrimental bacteria decreased. In this study, for the first time, it was demonstrated that dietary RPE could modulate the gut microbiota of the H22 bearing mice by increasing the abundance of beneficial bacteria and decreasing that of detrimental bacteria among intestinal bacteria, providing evidence for the mechanism by which bioactive proteins affect intestinal nutrition and disease resistance in animals.

The potential mechanism of postoperative cognitive dysfunction in older people

Postoperative cognitive dysfunction (POCD) is a common disorder following surgery, which seriously threatens the quality of patients' life, especially the older people. Accumulating attention has been paid to POCD worldwide in pace with the popularization of anesthesia/surgery. The development of medical humanities and rehabilitation medicine sets higher demands on accurate diagnosis and safe treatment system of POCD. Although the research on POCD is in full swing, underlying pathogenesis is still inconclusive due to these conflicting results and controversial evidence. Generally, POCD is closely related to neuropsychiatric diseases such as dementia, depression and Alzheimer's disease in molecular pathways. Researchers have come up with various hypotheses to reveal the mechanisms of POCD, including neuroinflammation, oxidative stress, autophagy disorder, impaired synaptic function, lacking neurotrophic support, etc. Recent work focused on molecular mechanism of POCD in older people has been thoroughly reviewed and summed up here, concerning the changes of peripheral circulation, pathological pathways of central nervous system (CNS), the microbiota-gut-brain axis and the related brain regions. Accordingly, this article provides a better perspective to understand the development situation of POCD in older people, which is conductive to uncover the pathological mechanism and exploit reasonable treatment strategy of POCD.

Plant- and Nutraceutical-based Approach for the Management of Diabetes and its Neurological Complications: A Narrative Review

Diabetes is an important metabolic disease affecting many organs and systems in the body. The nervous system is one of the body systems affected by diabetes and neuropathic complications are troublesome in diabetic patients with many consequences. As diabetes has deleterious influences almost on bodily systems, an integrative approach seems to be necessary accepting the body as a whole and integrating body systems with lifestyle and living environment. Like some traditional health systems such as Ayurveda, integrative approach includes additional modalities to overcome both diabetes and diabetic complications. In general, these modalities consist of nutraceuticals and plant products. Prebiotics and probiotics are two types of nutraceuticals having active ingredients, such as antioxidants, nutrient factors, microorganisms, etc. Many plants are indicated for the cure of diabetes. All of these may be employed in the prevention and in the non-pharmacological management of mildto- moderate diabetes. Severe diabetes should require appropriate drug selection. Being complementary, prebiotics, probiotics, plants and exercise may be additive for the drug therapy of diabetes. Similarly, there are complementary approaches to prevent and cure neurological and/or behavioral manifestations of diabetes, which may be included in therapy and prevention plans. A scheme is given for the prevention and therapy of comorbid depression, which is one of the most common behavioral complications of diabetes. Within this scheme, the main criterion for the selection of modalities is the severity of diseases, so that personalized management may be developed for diabetic patients using prebiotics and probiotics in their diets, plants and drugs avoiding possible interactions.

Chronic Unpredictable Mild Stress in Rats Induces Colonic Inflammation

Chronic psychological stress is associated with an increased risk for relapse of inflammatory bowel diseases (IBD) and impedes the treatment of this condition. However, the impact of stress on the risk of IBD onset remains unclear. The goal of the present study was to examine whether chronic unpredictable mild stress (CUMS) could initiate or aggravate the onset of colon inflammation in rats which, in turn, would be capable of triggering bowel disease. We found that CUMS exposure increased infiltration of CD-45 positive cells and MPO activity, as well as augmented the expression of the inflammatory cytokines, IFN-γ and IL-6 within the colon of these rats. In addition, CUMS treatment changed the composition and diversity of gut microbiota and enhanced intestinal epithelial permeability, indicating the presence of a defect in the intestinal barrier. This CUMS-induced disruption of mucosal barrier integrity was associated with a reduction in expression of the tight junction protein, occludin 1, and an inhibition in mucosal layer functioning via reductions in goblet cells. Results from bacterial cultures revealed an increased presence of bacterial invasion after CUMS treatment as compared with that observed in controls. Thus, our data indicate that CUMS treatment induces alterations of the fecal microbiome and intestinal barrier defects, which facilitates bacterial invasion into colonic mucosa and further exacerbates inflammatory reactions within the colon. Accordingly, chronic stress may predispose patients to gastrointestinal infection and increase the risk of inflammation-related gut diseases.

The Role of Gut Microbiota in Gastrointestinal Symptoms of Children with ASD

Background and objectives: Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impaired communication, social interaction disorder, and repetitive behavior. Dysbiotic gut microbiota (GM) could be a contributing factor to the appearance of ASD, as gastrointestinal (GI) symptoms are comorbidities frequently reported in ASD. As there is a lack of reviews about the role played by GM in the GI symptoms of ASD, this work aimed to carry out a systematic review of current studies comparing the GM of children with ASD and GI symptoms with those of healthy controls in the last six years. Materials and Methods: The systematic review was performed following the PRISMA guidelines. The databases chosen were Web of Science, Scopus, PubMed, and PsycINFO, and the keywords were (gut* OR intestine* OR bowel* OR gastrointestinal*) AND (microbiota* OR microflora* OR bacteria* OR microbiome* OR flora* OR bacterial* OR bacteria* OR microorganism* OR feces* OR stool*) AND (autistic* OR autism* OR ASD*). Results: A total of 16 articles were included. Ten articles performed correlations analysis between GI symptoms and ASD. Among those 10 articles, 7 found differences between the GI symptoms present in children with ASD and healthy controls. The most common GI symptom was constipation. Among the seven articles that found differences, three performed correlations analysis between GI symptoms and gut microbe abundance. Candida, Prevotella, Streptococcus, and Veillonella showed higher and lower abundance, respectively, in children with ASD and GI symptoms in more than one article. Bacteroidetes, Firmicutes, Actinomyces, Dorea, Lactobacillus, Faecalibacterium prausnitzii, and Bacteroidetes/Firmicutes ratios showed abundance discrepancies. Conclusions: It is still too early to draw a conclusion about the gut microbes involved in GI symptoms of ASD. Future research should consider the relationship between ASD behavior, GM, and GI symptoms in a multidisciplinary way and homogenize sample characteristics.

Gut microbiota dysbiosis in a cohort of patients with psoriasis

BACKGROUND

There is increasing evidence of the key role that the gut microbiota plays in inflammatory diseases.

OBJECTIVES

To identify differences in the faecal microbial composition of patients with psoriasis compared with healthy individuals in order to unravel the microbiota profiling in this autoimmune disease.

METHODS

16S rRNA gene sequencing and bioinformatic analyses were performed with the total DNA extracted from the faecal microbiota of 19 patients with psoriasis and 20 healthy individuals from the same geographic location.

RESULTS

Gut microbiota composition of patients with psoriasis displayed a lower diversity and different relative abundance of certain bacterial taxa compared with healthy individuals.

CONCLUSIONS

The gut microbiota profile of patients with psoriasis displayed a clear dysbiosis that can be targeted for microbiome-based therapeutic approaches. What's already known about this topic? Psoriasis is a chronic inflammatory immune-mediated skin disease, the aetiology of which remains unclear. The human microbiota is a complex microbial community that inhabits our body and has been related with the maintenance of a healthy status. Several studies have focused on the skin microbiome and its connection with psoriasis although less attention has been focused on the potential role of the gut microbiota in psoriatic disease. What does this study add? This study unravels the gut microbiome dysbiosis present in a cohort of patients with psoriasis, compared with a healthy control group from the same geographical location. This study shows a lower bacterial diversity and different relative abundance of certain bacterial taxa in patients with psoriasis. We gain knowledge and insight into the microbiome alterations in psoriatic disease, opening new avenues for therapeutic approaches to reshape the human microbiome towards a healthy status.

Human gut microbiome changes during a 10 week Randomised Control Trial for micronutrient supplementation in children with attention deficit hyperactivity disorder

It has been widely hypothesized that both diet and the microbiome play a role in the regulation of attention-deficit/hyperactivity disorder (ADHD) behaviour. However, there has been very limited scientific investigation into the potential biological connection. We performed a 10-week pilot study investigating the effects of a broad spectrum micronutrient administration on faecal microbiome content, using 16S rRNA gene sequencing. The study consisted of 17 children (seven in the placebo and ten in the treatment group) between the ages of seven and 12 years, who were diagnosed with ADHD. We found that micronutrient treatment did not drive large-scale changes in composition or structure of the microbiome. However, observed OTUs significantly increased in the treatment group, and showed no mean change in the placebo group. The differential abundance and relative frequency of Actinobacteria significantly decreased post- micronutrient treatment, and this was largely attributed to species from the genus Bifidobacterium. This was compensated by an increase in the relative frequency of species from the genus Collinsella. Further research is required to establish the role that Bifidobacterium contribute towards neuropsychiatric disorders; however, these findings suggest that micronutrient administration could be used as a safe, therapeutic method to modulate Bifidobacterium abundance, which could have potential implications for modulating and regulating ADHD behaviour. Our pilot study provides an initial observation into this area of research, and highlights an interesting avenue for further investigation in a larger cohort. Furthermore, these novel results provide a basis for future research on the biological connection between ADHD, diet and the microbiome.

Maternal separation in rodents: a journey from gut to brain and nutritional perspectives

The developmental period constitutes a critical window of sensitivity to stress. Indeed, early-life adversity increases the risk to develop psychiatric diseases, but also gastrointestinal disorders such as the irritable bowel syndrome at adulthood. In the past decade, there has been huge interest in the gut-brain axis, especially as regards stress-related emotional behaviours. Animal models of early-life adversity, in particular, maternal separation (MS) in rodents, demonstrate lasting deleterious effects on both the gut and the brain. Here, we review the effects of MS on both systems with a focus on stress-related behaviours. In addition, we discuss more recent findings showing the impact of gut-directed interventions, including nutrition with pre- and probiotics, illustrating the role played by gut microbiota in mediating the long-term effects of MS. Overall, preclinical studies suggest that nutritional approaches with pro- and prebiotics may constitute safe and efficient strategies to attenuate the effects of early-life stress on the gut-brain axis. Further research is required to understand the complex mechanisms underlying gut-brain interaction dysfunctions after early-life stress as well as to determine the beneficial impact of gut-directed strategies in a context of early-life adversity in human subjects.

Mixed Spices at Culinary Doses Have Prebiotic Effects in Healthy Adults: A Pilot Study

Spices were used as food preservatives prior to the advent of refrigeration, suggesting the possibility of effects on microbiota. Previous studies have shown prebiotic activities in animals and in vitro, but there has not been a demonstration of prebiotic or postbiotic effects at culinary doses in humans. In this randomized placebo-controlled study, we determined in twenty-nine healthy adults the effects on the gut microbiota of the consumption daily of capsules containing 5 g of mixed spices at culinary doses by comparison to a matched control group consuming a maltodextrin placebo capsule. The 16S ribosomal RNA sequencing data were used for microbial characterization. Spice consumption resulted in a significant reduction in Firmicutes abundance (p < 0.033) and a trend of enrichment in Bacteroidetes (p < 0.097) compared to placebo group. Twenty-six operational taxonomic units (OTUs) were different between the spice and placebo groups after intervention. Furthermore, there was a significant negative correlation between fecal short-chain fatty acid propionate concentration and Firmicutes abundance in spice intervention group (p < 0.04). The production of individual fecal short-chain fatty acid was not significantly changed by spice consumption in this study. Mixed spices consumption significantly modified gut microbiota, suggesting a prebiotic effect of spice consumption at culinary doses.

Impaired butyrate absorption in the proximal colon, low serum butyrate and diminished central effects of butyrate on blood pressure in spontaneously hypertensive rats

AIM

Butyrate is a major gut microbiota-derived metabolite. Reduced butyrate-producing bacteria has been reported in the spontaneously hypertensive rat (SHR), a model of hypertension characterized by dysfunctional autonomic nervous system and gut dysbiosis. Here, we demonstrate a potential mechanism for butyrate in blood pressure regulation.

METHODS

High-performance liquid chromatography and liquid chromatography-mass spectrometry were performed to measure butyrate levels in feces and serum. Ussing chamber determined butyrate transport in colon ex vivo. Real-time PCR and immunohistochemistry evaluated expression of butyrate transporter, Slc5a8, in the colon. Mean arterial blood pressure was measured in catheterized anesthetized rats before and after a single butyrate intracerebroventricular injection. Activity of cardioregulatory brain regions was determined by functional magnetic resonance imaging to derive neural effects of butyrate.

RESULTS

In the SHR, we demonstrated elevated butyrate levels in cecal content, but diminished butyrate levels in circulation, possibly due to reduced expression of Slc5a8 transporter in the colon. In addition, we observed lower expression levels of butyrate-sensing receptors in the hypothalamus of SHR, likely leading to the reduced effects of centrally administered butyrate on blood pressure in the SHR. Functional magnetic resonance imaging revealed reduced activation of cardioregulatory brain regions following central administration of butyrate in the SHR compared to control.

CONCLUSION

We demonstrated a reduced availability of serum butyrate in the SHR, possibly due to diminished colonic absorption. Reduced expression of butyrate-sensing receptors in the SHR hypothalamus may explain the reduced central responsiveness to butyrate, indicating microbial butyrate may play a role in blood pressure regulation.

The effect of adjunctive nutraceuticals in bipolar disorder: A systematic review of randomized placebo-controlled trials

BACKGROUND

Nutraceuticals are a group of compounds of growing interest for mental health professionals. Given the implication of certain nutrients in the onset of bipolar disorder, it has been hypothesized that nutraceuticals might be effective in improving symptoms of the condition (i.e. mania or depression). Our systematic review aimed to evaluate the effectiveness of adjunctive nutraceuticals compared to placebo.

METHODS

We searched the following databases from inception to February 2019: Web of Science, CINAHL, Embase, and PsycINFO. We included only original randomized controlled trials written in English, testing the efficacy of nutraceuticals in add-on to standard care, compared to placebo, in patients with bipolar disorder.

RESULTS

After identifying 6584 potentially relevant publications, we finally included 25 studies, among which six used fatty acids, seven micronutrients, seven amino acids. One study tested probiotics, while in four trials a combination of different types of nutraceuticals was used. Even if some compounds have shown promising results (i.e. fatty acids and N-acetyl cysteine for depression, amino acid drinks and folic acid for mania), the majority of nutraceuticals did not cause significant improvements in comparison to placebo.

LIMITATIONS

We could not perform a meta-analysis due to the high heterogeneity of trials, which were also affected by some methodological caveats.

CONCLUSIONS

Evidence regarding the efficacy of adjunctive nutraceuticals in bipolar disorder is inconsistent. Nevertheless, they appear generally free from relevant side effects. Well-designed trials are needed to further explore the potential role of nutraceuticals in different mood episodes.

Medical Complications of Binge Eating Disorder

Binge eating disorder (BED) is the most common eating disorder and is accompanied by multiple medical comorbidities, many of which are associated with obesity-related diseases. However, the BED itself is likely to confer additional risk factors. BED presents with medical symptoms in virtually every body system and can have devastating consequences on both quality and length of life. This review covers the major comorbidities of BED and highlights areas of ongoing research in this disorder.

The Possible Role of the Microbiota-Gut-Brain-Axis in Autism Spectrum Disorder

New research points to a possible link between autism spectrum disorder (ASD) and the gut microbiota as many autistic children have co-occurring gastrointestinal problems. This review focuses on specific alterations of gut microbiota mostly observed in autistic patients. Particularly, the mechanisms through which such alterations may trigger the production of the bacterial metabolites, or leaky gut in autistic people are described. Various altered metabolite levels were observed in the blood and urine of autistic children, many of which were of bacterial origin such as short chain fatty acids (SCFAs), indoles and lipopolysaccharides (LPS). A less integrative gut-blood-barrier is abundant in autistic individuals. This explains the leakage of bacterial metabolites into the patients, triggering new body responses or an altered metabolism. Some other co-occurring symptoms such as mitochondrial dysfunction, oxidative stress in cells, altered tight junctions in the blood-brain barrier and structural changes in the cortex, hippocampus, amygdala and cerebellum were also detected. Moreover, this paper suggests that ASD is associated with an unbalanced gut microbiota (dysbiosis). Although the cause-effect relationship between ASD and gut microbiota is not yet well established, the consumption of specific probiotics may represent a side-effect free tool to re-establish gut homeostasis and promote gut health. The diagnostic and therapeutic value of bacterial-derived compounds as new possible biomarkers, associated with perturbation in the phenylalanine metabolism, as well as potential therapeutic strategies will be discussed.

Relation Between Infant Microbiota and Autism?: Results from a National Cohort Sibling Design Study

BACKGROUND

Hypotheses concerning adverse effects of changes in microbiota have received much recent attention, but unobserved confounding makes them difficult to test. We investigated whether surrogate markers for potential adverse microbiota change in infancy affected autism risk, addressing unobserved confounding using a sibling study design.

METHODS

This is a population-based, prospective cohort study including all singleton live births in Denmark from 1997 to 2010. The exposure variables were cesarean delivery and antibiotic use in the first 2 years of life. The outcome was a subsequent autism diagnosis. We used the between- and within-sibling model and compared it with sibling-stratified Cox models and simpler standard Cox models that ignored sibship.

RESULTS

Of our study population including 671,606 children, who were followed for up to 15 years (7,341,133 person-years), 72% received antibiotics, 17.5% were delivered by cesarean, and 1.2% (8,267) developed autism. The standard Cox models predicted that both cesarean (compared with vaginal) delivery and antibiotics increased the risk of autism. In the sibling-stratified Cox model, only broader spectrum antibiotics were associated with increased risk of autism: hazard ratio (HR) = 1.16 (95% confidence interval = 1.01, 1.36). The between-within model estimated no exposure effects: intrapartum cesarean HR = 1.06 (0.89, 1.26); prelabor cesarean HR = 0.97 (0.83, 1.15); exclusively penicillin HR = 1.05 (0.93, 1.18); and broader spectrum antibiotics HR = 1.05 (0.95, 1.16).

CONCLUSIONS

The between-within model rendered more precise estimates than sibling-stratified Cox models, and we believe that it also provided more valid estimates. Results from these preferred models do not support a causal relation between antibiotic treatment during infancy, cesarean delivery, and autism. See video abstract at, http://links.lww.com/EDE/B432.

Comparison of the Intestinal Microbial Community in Ducks Reared Differently through High-Throughput Sequencing

Birds are an important source of fecal contamination in environment. Many of diseases are spread through water contamination caused by poultry droppings. A study was conducted to compare the intestinal microbial structure of Shaoxing ducks with and without water. Thirty 1-day-old Shaoxing ducks (Qingke No. 3) were randomly divided into two groups; one group had free access to water (CC), while the other one was restricted from water (CT). After 8 months of breeding, caecal samples of 10 birds from each group were obtained on ice for high-throughput sequencing. A total of 1507978 valid sequences were examined and clustered into 1815 operational taxonomic units (OTUs). At phylum level, Firmicutes (41.37%), Bacteroidetes (33.26%), Proteobacteria (13.67%), and Actinobacteria (8.26%) were found to dominate the microbial community in CC birds, while Firmicutes (53.62%), Bacteroidetes (33.06%), and Actinobacteria (11.13%) were uncovered to be the prime phyla in CT ducks. At genus level, Bacteroides (25.02%), Escherichia-Shigella (11.02%), Peptococcus (7.73%) and Parabacteroides (5.86%) were revealed to be the mainly genera in the CC group ducks, while Bacteroides (18.11%), Erysipelatoclostridium (10.94%), Ruminococcaceae_unclassified (10.43%), Lachnospiraceae_unclassified (5.26%), Coriobacteriales_unclassified (5.89%), and Faecalibacterium (4.2%) were detected to staple the microbial flora in the CT birds. One phylum and 13 genera were found to have the significant difference between the two bird groups (p<0.05). At phylum level, Proteobacteria in CT ducks were found to be obviously lower than ducks in CC birds (p<0.05). At genus level, Escherichia-Shigella (p<0.05) and Peptococcus (p<0.05) were found to be notably lower in CT birds, while Erysipelatoclostridium (p<0.05), Ruminococcaceae_unclassified (p<0.01), Coriobacteriales_unclassified (p<0.05), Faecalibacterium (p<0.01), Atopobiaceae_unclassified (p<0.01), Alistipes (p<0.05), Eggerthellaceae_unclassified (p<0.05), Prevotella_7 (<0.05), Rikenellaceae_RC9_gut_group (p<0.05), Prevotellaceae_uncultured (p<0.05), and Shuttleworthia (p<0.05) were observed to be prominently higher in CT ducks. In conclusion, the present study revealed the effects of keeping ducks away from swimming with obvious changes in the microbial community. Though higher microbial richness was found in the ducks without swimming, more pathogenic genera including Eggerthella, Erysipelatoclostridium, Alistipes, Prevotella_7, and Shuttleworthia; zoonotic genera including Eggerthella and Shuttleworthia; inflammatory genus Alistipes; anti-inflammatory Faecalibacterium genus; and tumor genus Rikenellaceae were examined in these ducks. The CT ducks also showed significant changes at genera level regarding the metabolism (Peptococcus, Ruminococcaceae, and Coriobacteriales).

Chronic alcohol exposure induced gut microbiota dysbiosis and its correlations with neuropsychic behaviors and brain BDNF/Gabra1 changes in mice

Alcohol addiction can cause brain dysfunction and many other diseases. Recently, increasing evidences have suggested that gut microbiota plays a vital role in regulating alcohol addiction. However, the exact mechanism has not yet been elucidated. Here, our study focused on the intestinal bacteria alternations and their correlations with alcohol-induced neuropsychic behaviors. When consuming alcohol over 3-week period, animals gradually displayed anxiety/depression-like behaviors. Moreover, 16S rRNA sequencing showed significant intestinal microflora dysbiosis and distinct community composition. Actinobacteria and Cyanobacteria were both increased at the phylum level. At the genus level, Adlercreutzia spp., Allobaculum spp., and Turicibacter spp. were increased whereas Helicobacter spp. was decreased. We also found that the distances in inner zone measured by open field test and 4% (v/v) alcohol preference percentages were significantly correlated with Adlercreutzia spp. The possible mechanisms were explored and we found the expression of brain-derived neurotrophic factor (BDNF) and α1 subunit of γ-aminobutyric acid A receptor (Gabra1) were both decreased in prefrontal cortex (PFC). Especially, further correlation analyses demonstrated that decreased Adlercreutzia spp. was positively correlated with alcohol preference and negatively correlated with anxiety-like behavior and BDNF/Gabra1 changes in PFC. Similar relationships were observed between Allobaculum spp. and alcohol preference and BDNF changes. Helicobacter spp. and Turicibacter spp. were also correlated with PFC BDNF and hippocampus Gabra1 level. Taken together, our study showed that gut microbiota dysbiosis during chronic alcohol exposure was closely correlated with alcohol-induced neuropsychic behaviors and BDNF/Gabra1 expression, which provides a new perspective for understanding underlying mechanisms in alcohol addiction. © 2018 BioFactors, 45(2):187-199, 2019.

Emerging trends and research foci in gastrointestinal microbiome

Background

Gastrointestinal microbiome has drawn an increasing amount of attention over the past decades. There is emerging evidence that the gut flora plays a major role in the pathogenesis of certain diseases. We aimed to analyze the evolution of gastrointestinal microbiome research and evaluate publications qualitatively and quantitatively.

Methods

We obtained a record of 2891 manuscripts published between 1998 and 2018 from the Web of Science Core Collection (WoSCC) of Thomson Reuters; this record was obtained on June 23, 2018. The WoSCC is the most frequently used source of scientific information. We used the term “Gastrointestinal Microbiomes” and all of its hyponyms to retrieve the record, and restricted the subjects to gastroenterology and hepatology. We then derived a clustered network from 70,169 references that were cited by the 2891 manuscripts, and identified 676 top co-cited articles. Next, we used the bibliometric method, CiteSpace V, and VOSviewer 1.6.8 to identify top authors, journals, institutions, countries, keywords, co-cited articles, and trends.

Results

We identified that the number of publications on gastrointestinal microbiome is increasing over time. 112 journals published articles on gastrointestinal microbiome. The United States of America was the leading country for publications, and the leading institution was the University of North Carolina. Co-cited reference analysis revealed the top landmark articles in the field. Gut microbiota, inflammatory bowel disease (IBD), probiotics, irritable bowel disease, and obesity are some of the high frequency keywords in co-occurrence cluster analysis and co-cited reference cluster analysis; indicating gut microbiota and related digestive diseases remain the hotspots in gut microbiome research. Burst detection analysis of top keywords showed that bile acid, obesity, and Akkermansia muciniphila were the new research foci.

Conclusions

This study revealed that our understanding of the link between gastrointestinal microbiome and associated diseases has evolved dramatically over time. The emerging new therapeutic targets in gut microbiota would be the foci of future research.

Effect of Metformin on Short-Term High-Fat Diet-Induced Weight Gain and Anxiety-Like Behavior and the Gut Microbiota

The pathogenic factors of the complex epidemic disorder-obesity, have expanded from genetic background, endocrine factors, abnormal feeding behaviors, and direct neural control of adipose tissue physiology. As a chronic metabolic disease, it is important to find new potential therapeutic targets and locate a sensitive time window for intervention. In this study, we focus on the early stage of a high-fat diet mouse model: a short-term 3-week treatment. Our results showed that this short-term 3-week HFD can already induce significant body weight gain, increased adipocyte size and surprisingly, anxiety-like behavior of the animals. Then we tried the early intervention with metformin, already reported for its effects in long-term HFD induced obesity. For a short-term 3-week co-treatment, metformin alleviated the HFD-induced increase in body weight, the increase in adipocyte size and furthermore, the anxiety-like behavior. Differences were noted among the normal diet (ND), HFD, and HFD with metformin co-treatment groups in gut microbiota, including its composition and diversity. The possible involvement of gut microbiota cannot be ruled out. Intense phospho-AMPK staining was found in the metformin treatment group in the habenular nuclei, hippocampus and basal ganglia of the brain compared with the HFD group, implying that the anxiolytic effect of metformin could be due to the direct activation of the AMPK pathway in the anxiety-related brain nuclei.

Gut microbiota composition in patients with newly diagnosed bipolar disorder and their unaffected first-degree relatives

OBJECTIVE

An aberrant gut microbiota may be associated with a broad spectrum of diseases including mental illness. The gut microbiota is scarcely studied in bipolar disorder (BD). We examined the gut microbiota composition in patients with newly diagnosed BD, their unaffected first-degree relatives and healthy individuals.

METHODS

Stool samples were collected from 113 patients with BD, 39 unaffected first-degree relatives and 77 healthy individuals and the microbiota was profiled using 16S rRNA gene amplicon sequencing.

RESULTS

The gut microbiota community membership of patients with BD differed from that of healthy individuals (R² = 1.0%, P = 0.008), whereas the community membership of unaffected first-degree relatives did not. Flavonifractor was present in 61% of patients with BD, 42% of their unaffected relatives and 39% of healthy individuals. Presence of Flavonifractor was associated with an odds ratio of 2.9 (95%CI: 1.6-5.2, P = 5.8 × 10^-4, Q = 0.036) for having BD. When excluding smokers, presence of Flavonifractor was associated with an odds ratio of 2.3 (95%CI: 1.1-5.3, P = 0.019) for having BD. However, when considering the subsample of non-smokers only, BD and presence of Flavonifractor were no longer associated when adjusted for all possible tests at genus level (Q = 0.6). Presence of Flavonifractor in patients with BD was associated with smoking and female sex, but not with age, waist circumference, exercise level, high-sensitive C-reactive protein, current affective state, subtype of BD, illness duration or psychotropic medication, respectively.

CONCLUSION

Flavonifractor, a bacterial genus that may induce oxidative stress and inflammation in its host, was associated with BD. Higher prevalence of smoking among patients with BD contributed to our findings, and it cannot be excluded that findings are influenced by residual confounding.

The valproic acid rat model of autism presents with gut bacterial dysbiosis similar to that in human autism

Background

Gut microbiota has the capacity to impact the regular function of the brain, which can in turn affect the composition of microbiota. Autism spectrum disorder (ASD) patients suffer from gastrointestinal problems and experience changes in gut microbiota; however, it is not yet clear whether the change in the microbiota associated with ASD is a cause or a consequence of the disease.

Methods

We have investigated the species richness and microbial composition in a valproic acid (VPA)-induced rat model autism. Fecal samples from the rectum were collected at necropsy, microbial total DNA was extracted, 16 rRNA genes sequenced using Illumina, and the global microbial co-occurrence network was constructed using a random matrix theory-based pipeline. Collected rat microbiome data were compared to available data derived from cases of autism.

Results

We found that VPA administration during pregnancy reduced fecal microbial richness, changed the gut microbial composition, and altered the metabolite potential of the fecal microbial community in a pattern similar to that seen in patients with ASD. However, the global network property and network composition as well as microbial co-occurrence patterns were largely preserved in the offspring of rats exposed to prenatal administration of VPA.

Conclusions

Our data on the microbiota of the VPA rat model of autism indicate that this model, in addition to behaviorally and anatomically mimicking the autistic brain as previously shown, also mimics the microbiome features of autism, making it one of the best-suited rodent models for the study of autism and ASD.

A systematic review of gut-immune-brain mechanisms in Autism Spectrum Disorder

Despite decades of research, the etiological origins of Autism Spectrum Disorder (ASD) remain elusive. Recently, the mechanisms of ASD have encompassed emerging theories involving the gastrointestinal, immune, and nervous systems. While each of these perspectives presents its own set of supporting evidence, the field requires an integration of these modular concepts and an overarching view of how these subsystems intersect. In this systematic review, we have synthesized relevant evidences from the existing literature, evaluating them in an interdependent manner and in doing so, outlining their possible connections. Specifically, we first discussed gastrointestinal and immuno-inflammation pathways in-depth, exploring the relationships between microbial composition, bacterial metabolites, gut mucosa, and immune system constituents. Accounting for temporal differences in the mechanisms involved in neurodevelopment, prenatal and postnatal phases were further elucidated, where the former focused on maternal immune activation (MIA) and fetal development, while the latter addressed the role of immune dysregulation in contributing to atypical neurodevelopment. As autism remains, foremost, a neurodevelopmental disorder, this review presents an integration of disparate modules into a "Gut-Immune-Brain" paradigm. Existing gaps in the literature have been highlighted, and possible avenues for future research with an integrated physiological perspective underlying ASD have also been suggested.