Psychobiotics: a novel class of psychotropic

Towards a psychobiotic therapy for depression: Bifidobacterium breve CCFM1025 reverses chronic stress-induced depressive symptoms and gut microbial abnormalities in mice

BACKGROUND

Accumulating evidence points to an association between gut microbial abnormalities and depression disorder. The microbiota-gut-brain axis is an emerging target for treating depression using nutritional strategies, considering the numerous limitations of current pharmacological approaches. Here we studied the effect and probable mechanisms of psychobiotic treatment on depression.

METHODS

Chronically stressed C57BL/6J male mice were administered viable Bifidobacterium breve CCFM1025 for 5 weeks prior to behavioral testing. Brain neurological alterations, serum corticosterone, cytokines levels, fecal microbial composition, and short-chain fatty acid (SCFA) content were measured. In addition, the effect of SCFA on 5-hydroxytryptophan (5-HTP) biosynthesis was investigated in an in vitro model of enterochromaffin cells (RIN14B).

RESULTS

CCFM1025 treatment significantly reduced depression- and anxiety-like behaviors. The hyperactive hypothalamic-pituitary-adrenal response, as well as inflammation, were also alleviated, possibly via regulating the expression of glucocorticoid receptors (Nr3c1). Moreover, CCFM1025 also down-regulated the pCREB-c-Fos pathway but increased the expression of brain-derived neurotrophic factor (BDNF). Meanwhile, chronic stress-induced gut microbial abnormalities were restored, accompanied by increased SCFA and 5-HTP levels. The intestinal 5-HTP biosynthesis positively correlated with fecal SCFA and Bifidobacterium breve levels.

CONCLUSIONS

In summary, Bifidobacterium breve CCFM1025 showed considerable antidepressant-like and microbiota-regulating effects, which opens avenues for novel therapeutic strategies towards treating depression.

The Prospects for the Therapeutic Implications of Genetically Engineered Probiotics

The interest in the therapeutic use of probiotic microorganisms has been increased during the last decade although the doubts have ascended about the probiotics mainly because their beneficial effects are not fully understood, and, in many cases, their usefulness has not been validated in clinical trials. Consequently, the notion got a considerable interest in those strains having proven probiotic potential to be engineered for improvement in their beneficial features. The process of genetic engineering can also be used for probiotic strains for the reversion of antimicrobial resistance and other modifications for their safer and effective human applications. The lactic acid bacilli are predominantly opposite as they already have gained attention owing to their health-promoting benefits and their safety for human consumption; therefore, their use, especially as a delivery agent of vaccines and drugs, is gaining attention. The tailoring of probiotic strains will not only improve the data regarding the probiotic potential of these strains but also clinch the doubts concerning these probiotics. This article focuses on the approaches of bioengineered probiotics and discusses the potential prospects for their therapeutic applications including immunomodulation, cognitive health, and anticancer therapeutics.

Computational profiling of the gut-brain axis: microflora dysbiosis insights to neurological disorders

Almost 2500 years after Hippocrates' observations on health and its direct association to the gastrointestinal tract, a paradigm shift has recently occurred, making the gut and its symbionts (bacteria, fungi, archaea and viruses) a point of convergence for studies. It is nowadays well established that the gut microflora's compositional diversity regulates via its genes (the microbiome) the host's health and provides preliminary insights into disease progression and regulation. The microbiome's involvement is evident in immunological and physiological studies that link changes in its biodiversity to its contributions to the host's phenotype but also in neurological investigations, substantiating the aptly named gut-brain axis. The definitive mechanisms of this last bidirectional interaction will be our main focus because it presents researchers with a new conundrum. In this review, we prospect current literature for computational analysis methodologies that accommodate the need for better understanding of the microbiome-gut-brain interactions and neurological disorder onset and progression, through cross-disciplinary systems biology applications. We will present bioinformatics tools used in exploring these synergies that help build and interpret microbial 16S ribosomal RNA data sets, produced by shotgun and high-throughput sequencing of healthy and neurological disorder samples stored in biological databases. These approaches provide alternative means for researchers to form hypotheses to their inquests faster, cheaper and swith precision. The goal of these studies relies on the integration of combined metagenomics and metabolomics assessments. An accurate characterization of the microbiome and its functionality can support new diagnostic, prognostic and therapeutic strategies for neurological disorders, customized for each individual host.

Dysregulation of synaptic pruning as a possible link between intestinal microbiota dysbiosis and neuropsychiatric disorders

The prenatal and early postnatal stages represent a critical time window for human brain development. Interestingly, this window partly overlaps with the maturation of the intestinal flora (microbiota) that play a critical role in the bidirectional communication between the central and the enteric nervous systems (microbiota-gut-brain axis). The microbial composition has important influences on general health and the development of several organ systems, such as the gastrointestinal tract, the immune system, and also the brain. Clinical studies have shown that microbiota alterations are associated with a wide range of neuropsychiatric disorders including autism spectrum disorder, attention deficit hyperactivity disorder, schizophrenia, and bipolar disorder. In this review, we dissect the link between these neuropsychiatric disorders and the intestinal microbiota by focusing on their effect on synaptic pruning, a vital process in the maturation and establishing efficient functioning of the brain. We discuss in detail how synaptic pruning is dysregulated differently in the aforementioned neuropsychiatric disorders and how it can be influenced by dysbiosis and/or changes in the intestinal microbiota composition. We also review that the improvement in the intestinal microbiota composition by a change in diet, probiotics, prebiotics, or fecal microbiota transplantation may play a role in improving neuropsychiatric functioning, which can be at least partly explained via the optimization of synaptic pruning and neuronal connections. Altogether, the demonstration of the microbiota's influence on brain function via microglial-induced synaptic pruning addresses the possibility that the manipulation of microbiota-immune crosstalk represents a promising strategy for treating neuropsychiatric disorders.

The bacterial neurometabolic signature of the gut microbiota of young children with autism spectrum disorders

Introduction. The human gut microbiota is currently seen as an important factor that can promote autism spectrum disorder (ASD) development in children.

Aim. This study aimed to detect differences in the taxonomic composition and content of bacterial genes encoding key enzymes involved in the metabolism of neuroactive biomarker compounds in the metagenomes of gut microbiota of children with ASD and neurotypical children.

Methodology. A whole metagenome sequencing approach was used to obtain metagenomic data on faecal specimens of 36 children with ASD and 21 healthy neurotypical children of 3–5 years old. Taxonomic analysis was conducted using MetaPhlAn2. The developed bioinformatics algorithm and created catalogue of the orthologues were applied to identify bacterial genes of neuroactive compounds in the metagenomes. For the identification of metagenomic signatures of children with ASD, Wilcoxon's test and adjustment for multiple comparisons were used.

Results. Statistically significant differences with decreases in average abundance in the microbiota of ASD children were found for the genera Barnesiella and Parabacteroides and species Alistipes putredinis , B. caccae , Bacteroides intestinihominis, Eubacterium rectale , Parabacteroides distasonis and Ruminococcus lactaris . Average relative abundances of the detected genes and neurometabolic signature approach did not reveal many significant differences in the metagenomes of the groups that were compared. We noted decreases in the abundance of genes linked to production of GABA, melatonine and butyric acid in the ASD metagenomes.

Conclusion. For the first time, the neurometabolic signature of the gut microbiota of young children with ASD is presented. The data can help to provide a comparative assessment of the transcriptional and metabolomic activity of the identified genes.

Microbiota-gut-brain axis and its affect inflammatory bowel disease: Pathophysiological concepts and insights for clinicians

Despite the bi-directional interaction between gut microbiota and the brain not being fully understood, there is increasing evidence arising from animal and human studies that show how this intricate relationship may facilitate inflammatory bowel disease (IBD) pathogenesis, with consequent important implications on the possibility to improve the clinical outcomes of the diseases themselves, by acting on the different components of this system, mainly by modifying the microbiota. With the emergence of precision medicine, strategies in which patients with IBD might be categorized other than for standard gut symptom complexes could offer the opportunity to tailor therapies to individual patients. The aim of this narrative review is to elaborate on the concept of the gut-brain-microbiota axis and its clinical significance regarding IBD on the basis of recent scientific literature, and finally to focus on pharmacological therapies that could allow us to favorably modify the function of this complex system.

Scaffold hopping of agomelatine leads to enhanced antidepressant effects by modulation of gut microbiota and host immune responses

The mechanisms underlying the pathophysiology of depression remain elusive, and the development of novel, effective antidepressant drugs remains necessary. A dihydroquinoline analog of agomelatine (AGO), N-(2-(7-methoxy-3,4-dihydroisoquinolin-1-yl)ethyl)acetamide hydrochloride (NMDEA), was synthesized by employing a scaffold-hopping strategy in our previous study. In this study, NMDEA was demonstrated to attenuate depression-related behaviors in mice models of chronic unpredictable mild stress (CUMS), using a sucrose preference test, a forced swimming test, and a tail suspension test. However, the antidepressant mechanism of NMDEA appears to differ from that for AGO. Based on the analysis of fecal microbiota from mice, stress can alter the richness of the gut bacterial community, increasing the expression of immune-modulating microbiota, such as Clostridia, and decreasing the expression of probiotic bacteria, such as Lactobacillus. Treatment with NMDEA was able to recover the richness and to regulate the dysbiosis among bacterial species. Several studies have demonstrated that the gut microbiota population can induce inflammatory processes. To explore the effects of NMDEA on the suppression of pro-inflammatory factors, we used Western blotting to analyze the levels of interleukin 1 beta (IL-1β), interleukin 6 (IL-6), p65, and inducible nitric oxide synthase (iNOS). NMDEA suppressed the activation of IL-1β and IL-6, in the hippocampus, and IL-1β, IL-6, p65, and iNOS, in lipopolysaccharide (LPS)-induced BV-2 cells. These results suggested that NMDEA may affect the microbiota-inflammasome-brain axis, regulating relevant neuro-inflammatory markers and gut microbiota. Our data also suggested that using small molecules to modify the gut microbiota population or alter inflammasome signaling may represent a new therapeutic opportunity for the mitigation of depression.

Effects of prebiotics on affect and cognition in human intervention studies

Studies conducted in rodents have highlighted that neurobiological processes underlying cognition and affect are modulated by the gut microbiota. Certain dietary fibers are able to modulate the composition of gut microbiota and are thus considered prebiotics. A review of the impact of the available prebiotic intervention studies in humans on cognition and affect, addressing the potential mediating role of the microbiota, was conducted. PubMed, Scopus, and PsycINFO were selected as sources. Fourteen articles were eligible for narrative synthesis. Data extraction and quality assessment were performed with characteristics established a priori. Some chronic prebiotic interventions (>28 d) improved affect and verbal episodic memory compared with a placebo. Acute prebiotic interventions (<24 h) were more efficient in improving cognitive variables (eg, verbal episodic memory). Future research should measure microbiota using adequate methodologies and recruit patients with dysbiosis, inflammation, or psychopathology. More research is needed to unravel the conditions required to obtain effects on affect and cognition.

Modulation of the intestinal microbiota and the metabolites produced by the administration of ice cream and a dietary supplement containing the same probiotics

The aim of the present work was to compare the capacity to modulate the intestinal microbiota and the production of metabolites after 14 d administration of a commercial dietary supplement and a manufactured ice cream, both containing the same quantity of inulin and the same viable counts of Lactobacillus acidophilus LA-5 and Bifidobacterium animalis BB-12, using the Simulator of the Human Intestinal Microbial Ecosystem (SHIME®) model. Samples of the colonic contents were evaluated microbiologically by real-time quantitative PCR (qRT-PCR) and next-generation sequencing and chemically by the production of SCFA (acetate, propionate and butyrate) and ammonium ions ($\text{NH}_4^ + $). Statistical analyses were carried out for all the variables using the two-way ANOVA followed by the Tukey multiple comparisons test (P < 0·05) for metabolite production, qRT-PCR and the bioinformatics analysis for microbiota diversity. Dietary supplement and ice cream were able to deliver the probiotic L. acidophilus and B. animalis to the simulated colon and modulate the microbiota, increasing beneficial micro-organisms such as Bifidobacterium spp., Bacteroides spp. and Faecalibacterium spp. for dietary supplement administration, and Lactobacillus spp. for ice cream supplementation. However, the ice cream matrix was probably more favourable for the maintenance of the metabolic activity of the probiotics in the SHIME® model, due to the larger amounts of acetate, propionate, butyrate and ammonium ions obtained after 14 d of supplementation. In conclusion, both ways of probiotic supplementation could be efficient, each with its own particularities.

Impact of chemotherapy on the association between fear of cancer recurrence and the gut microbiota in breast cancer survivors

BACKGROUND

Dysfunctional processing of fear memory may be involved in the pathophysiology of fear of cancer recurrence (FCR), which is cited as the major unmet psychological need of cancer survivors. Emerging evidence has shown that the microbiota-gut-brain (MGB) axis affects depressive and anxiety disorders, and chemotherapy-associated psychological distress. We therefore hypothesized that the gut microbiota is associated with FCR in cancer survivors.

METHODS

This cross-sectional study enrolled women diagnosed with invasive breast cancer who were not currently undergoing chemotherapy. Fecal samples were obtained to assess the gut microbiota. FCR grade was assessed using the Concerns About Recurrence Scale (CARS).

RESULTS

Mean age of the participants (n = 126) was 58 years; 47% had stage I disease. Multiple regression analysis with adjustment for possible confounders showed that the relative abundance of the Bacteroides genus (beta = 0.180, p = 0.03) was significantly and directly associated with FCR. In the 57 participants with a history of chemotherapy, higher FCR was associated with lower microbial diversity (p = 0.04), lower relative abundance of Firmicutes (p = 0.03) and higher relative abundance of Bacteroidetes (p = 0.04) at the phylum level, and higher relative abundance of Bacteroides (p < 0.01) and lower relative abundance of Lachnospiraceae.g (p = 0.03) and Ruminococcus (p = 0.02) at the genus level.

CONCLUSION

Our findings provide the first evidence of an association between the gut microbiota and FCR and suggest that chemotherapy-induced changes in gut microbiota can influence FCR. Further studies should examine the effects of the gut microbiota on FCR using a prospective design.

Commentary: Microbial panaceas: does development have the answer? - reflections on Cowan, Dinan, & Cryan (2020)

Is the microbiome a promising adjunct, a potential panacea, or a distraction from feasible treatments for neurodevelopmental disorders? Taking a developmental approach may get us closer to understanding the data and give us pause in trying to translate this nascent field to the clinic right now.

The gut microbiota is associated with psychiatric symptom severity and treatment outcome among individuals with serious mental illness

BACKGROUND

Emerging evidence implicates the gut microbiota in central nervous system functioning via its effects on inflammation, the hypothalamic-pituitary axis, and/or neurotransmission. Our understanding of the cellular underpinnings of the brain-gut relationship is based almost exclusively on animal models with some small-scale human studies. This study examined the relationship between the gut microbiota and psychiatric symptom severity and treatment response among inpatients with serious mental illness.

METHOD

We collected data from adult inpatients (N = 111). Measures of diagnoses, suicide severity, trauma, depression, and anxiety were collected shortly after admission, while self-collected fecal swabs were collected early in the course of hospitalization and processed using 16S rRNA gene sequencing and whole genome shotgun sequencing methods.

RESULTS

Results indicate that depression and anxiety severity shortly after admission were negatively associated with bacterial richness and alpha diversity. Additional analyses revealed a number of bacterial taxa associated with depression and anxiety severity. Gut microbiota richness and alpha diversity early in the course of hospitalization was a significant predictor of depression remission at discharge.

CONCLUSIONS

This study is among the first to demonstrate a gut microbiota relationship with symptom severity among psychiatric inpatients as well as a relationship to remission of depression post-treatment. These findings are consistent with animal models and limited human studies as well as with the broader literature implicating inflammation in the pathophysiology of depression. These findings offer the foundation for further studies of novel therapeutic approaches to the treatment, prevention of, or recurrence of serious mental illness.

Gut microbiome composition and diversity are related to human personality traits

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Investigation of gut microbiome composition and diversity with respect to human personality.

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Analyses targeted bacterial genera linked to behaviour in animal and human psychiatric studies.

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Bacterial genera were modelled (using negative binomial regression) with respect to personality.

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Genera linked to autism are also related to social behaviour in the general population.

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Sociability is associated with higher diversity, and anxiety and stress with reduced diversity.

The gut microbiome has a measurable impact on the brain, influencing stress, anxiety, depressive symptoms and social behaviour. This microbiome–gut–brain axis may be mediated by various mechanisms including neural, immune and endocrine signalling. To date, the majority of research has been conducted in animal models, while the limited number of human studies has focused on psychiatric conditions. Here the composition and diversity of the gut microbiome is investigated with respect to human personality. Using regression models to control for possible confounding factors, the abundances of specific bacterial genera are shown to be significantly predicted by personality traits. Diversity analyses of the gut microbiome reveal that people with larger social networks tend to have a more diverse microbiome, suggesting that social interactions may shape the microbial community of the human gut. In contrast, anxiety and stress are linked to reduced diversity and an altered microbiome composition. Together, these results add a new dimension to our understanding of personality and reveal that the microbiome–gut–brain axis may also be relevant to behavioural variation in the general population as well as to cases of psychiatric disorders.

Probiotic Properties and Neuroprotective Effects of Lactobacillus buchneri KU200793 Isolated from Korean Fermented Foods

The purpose of this study was to evaluate the probiotic characteristics and neuroprotective effects of bacteria isolated from Korean fermented foods. Three bacterial strains (Lactobacillus fermentum KU200060, Lactobacillus delbrueckii KU200171, and Lactobacillus buchneri KU200793) showed potential probiotic properties, such as high tolerance against artificial gastric juice and bile salts, sensitivity to antibiotics, nonproduction of carcinogenic enzymes, and high adhesion to intestinal cells. Heat-killed L. fermentum KU200060 and L. buchneri KU200793 showed higher antioxidant activity than heat-killed L. delbrueckii KU200171. The conditioned medium (CM) was used to evaluate the reaction between HT-29 cells and each heat-killed strain. All CMs protected SH-SY5Y cells from 1-methyl-4-phenylpyridinium (MPP⁺)-induced toxicity. The expression of brain-derived neurotropic factor (BDNF) mRNA in HT-29 cells treated with CM containing heat-killed L. buchneri KU200793 was the highest. The CM significantly reduced the Bax/Bcl-2 ratio and increased BDNF mRNA expression in SH-SY5Y cells treated with MPP⁺. These results indicate that L. buchneri KU200793 can be used as a prophylactic functional food, having probiotic potential and neuroprotective effects.

Finding intestinal fortitude: Integrating the microbiome into a holistic view of depression mechanisms, treatment, and resilience

Depression affects at least 322 million people globally, or approximately 4.4% of the world's population. While the earnestness of researchers and clinicians to understand and treat depression is not waning, the number of individuals suffering from depression continues to increase over and above the rate of global population growth. There is a sincere need for a paradigm shift. Research in the past decade is beginning to take a more holistic approach to understanding depression etiology and treatment, integrating multiple body systems into whole-body conceptualizations of this mental health affliction. Evidence supports the hypothesis that the gut microbiome, or the collective trillions of microbes inhabiting the gastrointestinal tract, is an important factor determining both the risk of development of depression and persistence of depressive symptoms. This review discusses recent advances in both rodent and human research that explore bidirectional communication between the gut microbiome and the immune, endocrine, and central nervous systems implicated in the etiology and pathophysiology of depression. Through interactions with circulating inflammatory markers and hormones, afferent and efferent neural systems, and other, more niche, pathways, the gut microbiome can affect behavior to facilitate the development of depression, exacerbate current symptoms, or contribute to treatment and resilience. While the challenge of depression may be the direst mental health crisis of our age, new discoveries in the gut microbiome, when integrated into a holistic perspective, hold great promise for the future of positive mental health.

Effect of probiotic administration on gut microbiota and depressive behaviors in mice

BACKGROUND

The gut microbiota is closely associated with the bidirectional gut-brain axis that modulates neuropsychological functions of the central nervous system, thereby affecting mental disorders such as depression. Although it is known that probiotics affect brain functions, the impact of probiotics on the regulation of the prevalence and composition of gut microbiota, leading to anti-depressive effects has not been well understood.

METHODS

Mice were randomly divided into four different groups (n = 10 for each group) as follows: Group G1 (normal group) as control and group G2 (stress group) were given sterile saline via oral route daily for 8 weeks without and with stress condition, respectively. Under the stress condition, group G3 (fluoxetine group) was administered with fluoxetine hydrochloride and group G4 (probiotic group) was orally given multi-strains of probiotics daily for 8 weeks. After treatment, all mice underwent behavioral testing. Furthermore, fecal samples were collected from randomly selected 5 mice of each group on day 60 and taxonomical analysis of intestinal microbial distribution was performed.

RESULTS

Mice subjected to restraint stress showed depressive-like behaviors along with high corticosterone levels in serum. However, probiotic administration alleviated depressive-like behaviors and decreased corticosterone level. Moreover, fecal microbiota was distinctly altered in probiotic-treated mice of the stress group. The relative abundance of phylum and genus levels was significantly decreased in the stress group, but probiotic administration restored the composition of microbes restored.

CONCLUSION

Ingested probiotics alter the composition of gut microbiota, likely improving the symptoms of depression. Graphical abstract Probiotic administration alters gut microbiota and reduces depressive-like behaviors.

Gastrointestinal (non-systemic) antibiotic rifaximin differentially affects chronic stress-induced changes in colon microbiome and gut permeability without effect on behavior

Chronic stress is often accompanied by gastrointestinal symptoms, which might be due to stress-induced shift of gut microbiome to pathogenic bacteria. It has been hypothesized that stress alters gut permeability and results in mild endotoxemia which exaggerates HPA activity and contributes to anxiety and depression. To reveal the relationship between microbiome composition, stress-induced gastrointestinal functions and behavior, we treated chronically stressed mice with non-absorbable antibiotic, rifaximin. The "two hits" stress paradigm was used, where newborn mice were separated from their mothers for 3 h daily as early life adversity (maternal separation, MS) and exposed to 4 weeks chronic variable stress (CVS) as adults. 16S rRNA based analysis of gut microbiome revealed increases of Bacteroidetes and Proteobacteria and more specifically, Clostridium species in chronically stressed animals. In mice exposed to MS + CVS, we found extenuation of colonic mucosa, increased bacterial translocation to mesenteric lymph node, elevation of plasma LPS levels and infiltration of F4/80 positive macrophages into the colon lamina propria. Chronically stressed mice displayed behavioral signs of anxiety-like behavior and neophobia. Rifaximin treatment decreased Clostridium concentration, gut permeability and LPS plasma concentration and increased colonic expression of tight junction proteins (TJP1, TJP2) and occludin. However, these beneficial effects of rifaximin in chronically stressed mice was not accompanied by positive changes in behavior. Our results suggest that non-absorbable antibiotic treatment alleviates stress-induced local pathologies, however, does not affect stress-induced behavior.

Microbiota and Alcohol Use Disorder: Are Psychobiotics a Novel Therapeutic Strategy?

In recent years, there has been an exciting focus of research attempting to understand neuropsychiatric disorders from a holistic perspective in order to determine the role of gut microbiota in the aetiology and pathogenesis of such disorders. Thus, the possible therapeutic benefits of targeting gut microbiota are being explored for conditions such as stress, depression or schizophrenia. Growing evidence indicates that there is bidirectional communication between gut microbiota and the brain that has an effect on normal CNS functioning and behavioural responses. Alcohol abuse damages the gastrointestinal tract, alters gut microbiota and induces neuroinflammation and cognitive decline. The relationship between alcohol abuse and hypothalamic-pituitary-adrenal axis activation, inflammation and immune regulation has been well documented. In this review, we explore the connection between microbiota, brain function and behaviour, as well as the mechanisms through which alcohol induces microbiota dysbiosis and intestinal barrier dysfunction. Finally, we propose the study of psychobiotics as a novel pharmaceutical strategy to treat alcohol use disorders.

The role of human and microbial metabolites of triptophane in severe diseases and critical ill (review)

The growing interest in metabolite circulating in the blood is associated with the accumulation of factual material on the involvement of low-molecular compounds in the development of a number of serious diseases. This review reveals the effect of a whole class of chemical compounds― tryptophan metabolites― on various pathological processes. The following keywords were used to find papers published in the PubMed database for the last 10 years: names of natural indole compounds, methods for their detection, nosology of diseases and critical ill patients. The data is presented in sections, which provide data on the study of tryptophan metabolites in a variety of groups of diseases, such as cancer, cardiovascular disease, kidney disease, bowel, mental disorders, atherosclerosis, etc. Particular attention is paid to the role of indole compounds that enter the systemic circulation as a result of microbial biotransformation of tryptophan, serotonin and other indole metabolites, which can be attributed to the "common metabolites" of humans and microbiota. The most interesting clinical studies are summarized in summary tables and figures. A number of indole metabolites are considered as potential biomarkers. The authors of the review substantiate the metabolomic approach to the study of a number of oncological, septic, mental and other intractable diseases, which opens up new possibilities of influence on the pathological process by targeted regulation in the metabolome/microbiome system.

Dysbiosis in Parkinson's disease might be triggered by certain antibiotics

Parkinson's disease (PD) is a neurodegenerative amyloid disorder with debilitating motor symptoms due to the loss of dopamine-synthesizing, basal ganglia-projecting neurons in the substantia nigra. An interesting feature of the disease is that most of PD patients have gastrointestinal problems and bacterial dysbiosis, years before the full expression of motor symptoms. We hypothesized that antibiotic consumption might be a contributing factor of gut microbiome dysbiosis in PD, favoring curli-producing Enterobacteria. Curli is a bacterial α-synuclein (αSyn) which is deposited first in the enteric nervous system and amyloid deposits are propagated in a prion like manner to the central nervous system. In addition, antibiotics result in a low-grade systemic inflammation, which also contributes to damage of neurons in enteric- and central nervous system. To support our hypothesis, by comparing PD prevalence change with antibiotic consumption data in EU countries, we found significant positive correlation between use narrow spectrum penicillin + penicillinase resistant penicillin and increased prevalence of the disease.

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.

Stress and the gut microbiota-brain axis

Stress is a nonspecific response of the body to any demand imposed upon it, disrupting the body homoeostasis and manifested with symptoms such as anxiety, depression or even headache. These responses are quite frequent in the present competitive world. The aim of this review is to explore the effect of stress on gut microbiota. First, we summarize evidence of where the microbiota composition has changed as a response to a stressful situation, and thereby the effect of the stress response. Likewise, we review different interventions that can modulate microbiota and could modulate the stress according to the underlying mechanisms whereby the gut-brain axis influences stress. Finally, we review both preclinical and clinical studies that provide evidence of the effect of gut modulation on stress. In conclusion, the influence of stress on gut microbiota and gut microbiota on stress modulation is clear for different stressors, but although the preclinical evidence is so extensive, the clinical evidence is more limited. A better understanding of the mechanism underlying stress modulation through the microbiota may open new avenues for the design of therapeutics that could boost the pursued clinical benefits. These new designs should not only focus on stress but also on stress-related disorders such as anxiety and depression, in both healthy individuals and different populations.

A Pilot Randomized Control Trial With the Probiotic Strain Lactobacillus rhamnosus GG (LGG) in ADHD: Children and Adolescents Report Better Health-Related Quality of Life

Objectives: This double-blind pilot randomized placebo-controlled trial examined the possible effect of the probiotic strain Lactobacillus rhamnosus GG ATCC53103 (LGG) on symptoms of attention-deficit/hyperactivity disorder (ADHD), health-related quality of life (QoL), and serum levels of cytokines in children and adolescents with ADHD. Methods: This trial evaluated 32 drug-naive children and adolescents aged between four and 17 years with a diagnosis of ADHD. The study subjects were randomly assigned to either the group that received LGG or the group that received the placebo. Assessments, comprising the ADHD Parent-Report Rating Scale-IV: Home Version; the Child Self-Report and Parent Proxy-Report of the Pediatric Quality of Life Inventory ^TM (PedsQL ^TM ) 4.0 Generic Core Scale; the Parent Form (CBCL/6-18) and the Teacher Report Form (TRF) of the Child Behavior Checklist (CBCL) for ages 6-18 of the Achenbach System of Empirically Based Assessment (ASEBA); and the serum cytokines; were compared between the groups at the baseline and after 3 months. Results: Thirty-five participants were randomized, with 32 completing the study (91.4% retention). There was a significant improvement in the PedsQL Child Self-Report Total Score after 3 months of treatment in the probiotic (p = 0.021, d = 0.53), whereas there was no significant improvement in the placebo group (p = 0.563, d = 0.04). The results of psychometric parameters assessed by parents and teachers were not so straightforward. There were statistically significant differences in the levels of serum cytokines between the groups after the 3-month treatment period: IL-6 in both the probiotic (p = 0.004, d = 0.73) and the placebo groups (p = 0.035, d = 0.94); IL-10 (p = 0.035, d = 0.6); IL-12 p70 (p = 0.025, d = 0.89); and TNF-α (p = 0.046, d = 0.64) in the probiotic group only. Conclusions: Children and adolescents with ADHD who received LGG supplementation reported better health-related QoL compared to their peers who received the placebo. This suggests that LGG supplementation could be beneficial. But results with psychometric tests conducted by parents and teachers as well as differences in the levels of inflammatory cytokines were ambiguous. Based on these results, we propose some study modifications: a longer observation period (6-12 months); inclusion of more children's self-report assessments; recruitment of non-drug naive patients and the possible omission of serum cytokines measurements. Clinical Trial Registration: Medical Ethics Committee (UKC-MB-KME-19-06/16).

Neuroinflammation, Gut-Brain Axis and Depression

Psychiatric diseases are the manifestations that result from the individual's genetic structure, physiology, immunology and ways of coping with environmental stressors. The current psychiatric diagnostic systems do not include any systematic characterization in regard to neurobiological processes that reveal the clinical picture in individuals who got psychiatric diagnosis. It is obvious that further research in different areas is needed to understand the psychopathology. The problems in the functions of immune system and the correlation of neuroinflammatory processes with psychiatric disorders have been one of the main research topics of psychiatry in recent years and have contributed to our understanding of psychopathology. Recent advances in the fields of immunology and genetics as well as rapidly increasing knowledge on the effects of immunological processes on brain functions have drawn attention to the correlations between psychiatric disorders and immune system dysfunctions. There are still unfilled gaps in the biology, pathophysiology, and treatment of major depressive disorder, which is quite prevalent among the psychiatric disorders, can lead to significant disability, and frequently has a recurrent course. It appears that low-grade chronic neuroinflammation plays a key role in forming a basis for the interaction between psychological stress, impaired gut microbiota and major depressive disorder. In this review, the role of neuroinflammation in the etiopathogenesis of depression and the mechanism of action of the gut-brain axis that leads to this are discussed in the light of current studies.

Gut microbiome structure and adrenocortical activity in dogs with aggressive and phobic behavioral disorders

Accompanying human beings since the Paleolithic period, dogs has been recently regarded as a reliable model for the study of the gut microbiome connections with health and disease. In order to provide some glimpses on the connections between the gut microbiome layout and host behavior, we profiled the phylogenetic composition and structure of the canine gut microbiome of dogs with aggressive (n = 11), phobic (n = 13) and normal behavior (n = 18). Hormones' determination was made through Radio Immuno-Assay (RIA), and next generation sequencing of the V3-V4 gene region of the bacterial 16S rRNA was employed to determine gut microbiome composition. Our results did not evidence any significant differences of hormonal levels between the three groups. According to our findings, aggressive behavioral disorder was found to be characterized by a peculiar gut microbiome structure, with high biodiversity and enrichment in generally subdominant bacterial genera (i.e. Catenibacterium and Megamonas). On the other hand, phobic dogs were enriched in Lactobacillus, a bacterial genus with known probiotic and psychobiotic properties. Although further studies are needed to validate our findings, our work supports the intriguing opportunity that different behavioral phenotypes in dogs may be associated with peculiar gut microbiome layouts, suggesting possible connections between the gut microbiome and the central nervous system and indicating the possible adoption of probiotic interventions aimed at restoring a balanced host-symbiont interplay for mitigating behavioral disorders.

Bibliometric and Visual Analysis of Research on the Links Between the Gut Microbiota and Depression From 1999 to 2019

Background: There is a crucial link between the gut microbiota and the host central nervous system, and the communication between them occurs via a bidirectional pathway termed the "microbiota-gut-brain axis." The gut microbiome in the modern environment has markedly changed in response to environmental factors. These changes may affect a broad range of host psychiatric disorders, such as depression, by interacting with the host through metabolic, immune, neural, and endocrine pathways. Nevertheless, the general aspects of the links between the gut microbiota and depression have not been systematically investigated through bibliometric analysis. Aim: This study aimed to analyze the current status and developing trends in gut microbiota research in the depression field through bibliometric and visual analysis. Methods: A total of 1,962 publications published between 1999 and 2019 were retrieved from the Web of Science Core Collection. CiteSpace (5.6 R5) was used to perform collaboration network analysis, co-citation analysis, co-occurrence analysis, and citation burst detection. Results: The number of publications has been rapidly growing since 2010. The collaboration network analysis revealed that the USA, University College Cork, and John F. Cryan were the most influential country, institute, and scholar, respectively. The most productive and co-cited journals were Brain Behavior and Immunity and Proceedings of the National Academy of Sciences of the United States of America, respectively. The co-citation analysis of references revealed that the most recent research focus was in the largest theme cluster, "cytokines," thus reflecting the important research foundation in this field. The co-occurrence analysis of keywords revealed that "fecal microbiota" and "microbiome" have become the top two research hotspots since 2013. The citation burst detection for keywords identified several keywords, including "Parkinson's disease," "microbiota-gut-brain axis," "microbiome," "dysbiosis," "bipolar disorder," "impact," "C reactive protein," and "immune system," as new research frontiers, which have currently ongoing bursts. Conclusions: These results provide an instructive perspective on the current research and future directions in the study of the links between the gut microbiota and depression, which may help researchers choose suitable cooperators or journals, and promote their research illustrating the underlying molecular mechanisms of depression, including its etiology, prevention, and treatment.

The Role of Brain Derived Neurotrophic Factor in HIV-Associated Neurocognitive Disorder: From the Bench-Top to the Bedside

Human immunodeficiency virus (HIV)-associated neurocognitive disorder (HAND) remains prevalent in the anti-retroviral (ART) era. While there is a complex interplay of many factors in the neuropathogenesis of HAND, decreased neurotrophic synthesis has been shown to contribute to synaptic degeneration which is a hallmark of HAND neuropathology. Brain derived neurotrophic factor (BDNF) is the most abundant and synaptic-promoting neurotrophic factor in the brain and plays a critical role in both learning and memory. Reduced BDNF levels can worsen neurocognitive impairment in HIV-positive individuals across several domains. In this paper, we review the evidence from pre-clinical and clinical studies showing the neuroprotective roles of BDNF against viral proteins, effect on co-morbid mental health disorders, altered human microbiome and ART in HAND management. Potential applications of BDNF modulation in pharmacotherapeutic, cognitive and behavioral interventions in HAND are also discussed. Finally, research gaps and future research direction are identified with the aim of helping researchers to direct efforts to make these BDNF driven interventions improve the quality of life of patients living with HAND.

Psychobiotics as treatment for anxiety, depression, and related symptoms: a systematic review

Objective: Altering the gut microflora may produce health benefits in individuals suffering from mood disorders. The purpose of this review was to evaluate the efficacy of probiotics, prebiotics, or synbiotics as a potential treatment for symptoms of depression, anxiety, and stress (as psychobiotics).Methods: Google Scholar, PubMed, PsychINFO, and Web of Science were utilized to identify and evaluate studies through October 31, 2019. Studies were included if subjects were evaluated for altered mood or stress levels at start of the study and consumed probiotics, prebiotics, and/or synbiotics for intervention.Results: Search results yielded 142 articles, while only 12 studies met all inclusion criteria. Nine of the 12 studies identified evaluated the efficacy of various probiotic strains, while only two evaluated synbiotics and one evaluated prebiotics. Six out of 12 studies found probiotics to reduce depression, while two studies found probiotics to reduce anxiety.Discussion: Translational research in this field is limited and further investigation of the efficacy of psychobiotics in mood disorders is warranted.

Probiotics of Diverse Origin and Their Therapeutic Applications: A Review

The increased awareness about the harmful effects of excessive use of antibiotics has created an interest in probiotics due to its beneficial effects on gut microbiota. These advantages of probiotics have attracted researchers to find out effects on human metabolism and their role in the treatment of diverse types of diseases or disorders. Additionally, they are clinically used as biocontrol agents in the treatment of mental disorders, anticancer agents and in decreasing the threat of necrotizing enterocolitis in premature infants. In this review, we have focused on various kinds of probiotics and various nondairy substrates for their production. We have also included the importance of probiotics in the treatment of metabolic disorders, type II diabetes and infectious diseases. Furthermore, this review emphasizes applications of probiotics originated from different organisms. Their future health perspectives are discussed to gain insight into their applications.KEY TEACHING POINTSThe global market of probiotics is enormously rising day by day due to its highly beneficial effect on human microbiota.Additionally, these are used as biocontrol agents; mental disorders prevent cancer and decrease the threat of necrotizing enterocolitis (NEC) in premature infants.This review focuses on various kinds of sources of probiotics and various non-dairy substrates for the production of probiotics.The importance of probiotics in the treatment of metabolic disorders, type II diabetes control, cancer and treatment of infectious diseases are also described.It emphasizes diversified probiotics and their applications in various human health aspects and future perspectives.

Strain specific stress-modulating effects of candidate probiotics: A systematic screening in a mouse model of chronic restraint stress

BACKGROUND

Changes in the gut microbiota have been implicated in mood and cognition. In rodents, supplementation with certain bacteria have been shown to alleviate adverse effects of stress on gut microbiota composition and behaviour, but little is known of how the performance of different strains compare to each other. We took a systematic approach to test the efficacy of twelve candidate probiotic strains from ten species/sub-species of Bifidobacterium and Lactobacillus on behaviours and neuroendocrine responses of chronically stressed mice.

METHODS

The strains were tested in four screening experiments with non-stressed and chronically stressed vehicle groups. The three most efficacious strains were re-tested to validate the results. Mice were administered a daily oral gavage containing either 1 × 10⁹ colony forming units (CFU) of selected candidate probiotic or saline solution for one week prior to and for three weeks during daily chronic restraint stress. Behavioural tests including the elevated plus maze, open field, novel object recognition, and forced swim test were applied during week five. Corticosterone and adrenocorticotropic hormone (ACTH) were analysed to measure the neuroendocrine response to stress. Plasma and tissue samples were collected for biomarker analyses.

RESULTS

Of the twelve candidate probiotics, Lactobacillus paracasei Lpc-37, Lactobacillus plantarum LP12407, Lactobacillus plantarum LP12418 and Lactobacillus plantarum LP12151 prevented stress-associated anxiety and depression-related behaviours from developing compared with chronically stressed vehicle mice. In addition, Lpc-37 improved cognition.

CONCLUSION

This systematic screening indicates species- and strain-dependent effects on behavioural outcomes related to stress and further suggests that strains differ from each other in their effects on potential mechanistic outcomes.

The Behavioral Biology of Teams: Multidisciplinary Contributions to Social Dynamics in Isolated, Confined, and Extreme Environments

Teams in isolated, confined, and extreme (ICE) environments face many risks to behavioral health, social dynamics, and team performance. Complex long-duration ICE operational settings such as spaceflight and military deployments are largely closed systems with tightly coupled components, often operating as autonomous microsocieties within isolated ecosystems. As such, all components of the system are presumed to interact and can positively or negatively influence team dynamics through direct or indirect pathways. However, modern team science frameworks rarely consider inputs to the team system from outside the social and behavioral sciences and rarely incorporate biological factors despite the brain and associated neurobiological systems as the nexus of input from the environment and necessary substrate for emergent team dynamics and performance. Here, we provide a high-level overview of several key neurobiological systems relevant to social dynamics. We then describe several key components of ICE systems that can interact with and on neurobiological systems as individual-level inputs influencing social dynamics over the team life cycle-specifically food and nutrition, exercise and physical activity, sleep/wake/work rhythms, and habitat design and layout. Finally, we identify opportunities and strategic considerations for multidisciplinary research and development. Our overarching goal is to encourage multidisciplinary expansion of team science through (1) prospective horizontal integration of variables outside the current bounds of team science as significant inputs to closed ICE team systems and (2) bidirectional vertical integration of biology as the necessary inputs and mediators of individual and team behavioral health and performance. Prospective efforts to account for the behavioral biology of teams in ICE settings through an integrated organizational neuroscience approach will enable the field of team science to better understand and support teams who work, live, serve, and explore in extreme environments.

Psychobiotics

Psychobiotics are live bacteria that directly and indirectly produce positive effects on neuronal functions by colonizing into the intestinal flora. Preliminary studies, although in limited numbers, have found that these bacteria have anxiolytic and antidepressant activities. No research has yet been published on the antipsychotic efficacy of psychobiotics. However, these preliminary studies have opened up new horizons and raised the idea that a new class is emerging in psychopharmacology. About 70 years have passed since the discovery of chlorpromazine, and while the synaptic transmission is understood in almost all details, there seems to be a paradigm shift in psychopharmacology. In recent years, the perspective has shifted from synapse to intestinal microbiota. In this respect, germ-free and conventional animal experiments and few human studies were examined in a comprehensive manner. In this article, after a brief look at the history of contemporary psychopharmacology, the mechanisms of the gut-brain relationship and the evidence of metabolic, systemic, and neuropsychiatric activities of psychobiotics were discussed in detail. In conclusion, psychobiotics seem to have the potential for treatment of neuropsychiatric disorders in the future. However, there are many questions and we do not know the answers yet. We anticipate that the answer to these questions will be given in the near future.

The Potential Influence of the Bacterial Microbiome on the Development and Progression of ADHD

The latest research cumulates staggering information about the correlation between the microbiota-gut-brain axis and neurodevelopmental disorders. This review aims to shed light on the potential influence of the microbiome on the development of the most prevalent neurodevelopmental disease, attention-deficit-hyperactive disorder (ADHD). As the etiology and pathophysiology of ADHD are still unclear, finding viable biomarkers and effective treatment still represent a challenge. Therefore, we focused on factors that have been associated with a higher risk of developing ADHD, while simultaneously influencing the microbial composition. We reviewed the effect of a differing microbial makeup on neurotransmitter concentrations important in the pathophysiology of ADHD. Additionally, we deduced factors that correlate with a high prevalence of ADHD, while simultaneously affecting the gut microbiome, such as emergency c-sections, and premature birth as the former leads to a decrease of the gut microbial diversity and the latter causes neuroprotective Lactobacillus levels to be reduced. Also, we assessed nutritional influences, such as breastfeeding, ingestion of short-chain fatty acids (SCFAs) and polyunsaturated fatty acids (PUFAs) on the host′s microbiome and development of ADHD. Finally, we discussed the potential significance of Bifidobacterium as a biomarker for ADHD, the importance of preventing premature birth as prophylaxis and nutrition as a prospective therapeutic measurement against ADHD.

Positive effects of a Clostridium butyricum-based compound probiotic on growth performance, immune responses, intestinal morphology, hypothalamic neurotransmitters, and colonic microbiota in weaned piglets

Weaning stress in piglets can lead to poor health outcomes and reduced production. We investigated the effects of probiotics, one potential antibiotic alternative, on the growth performance, serum biochemical parameters, intestinal morphology, mucosal immunity, hypothalamic neurotransmitters, and colonic microflora in weaned piglets. Thirty-six weaned piglets were fed a basal diet, a diet supplemented with colistin sulphate antibiotic, or a diet supplemented with probiotics including Clostridium butyricum, Bacillus subtilis, and B. licheniformis. Probiotics significantly increased the feed : gain ratio, improved the average day gain from day 1 to day 28, and decreased the diarrhoea index. Probiotics also lowered the serum concentrations of AST, ALT, and ALP on day 14 and lowered the serum concentration of ALT on day 28 compared with the control. Probiotic supplementation caused fewer ileal apoptotic cells. The serum and ileal concentrations of TNF-α and IL-1β on day 28 were significantly lowered, and the serum concentrations of IL-6 were significantly lowered on days 14 and 28. Probiotic-fed piglets exhibited higher contents of hypothalamic serotonin and dopamine as well as serum γ-aminobutyric acid along with higher colonic concentrations of butyrate and valerate on day 28. High-throughput sequencing showed 972 core operational taxonomic units among all groups, of which 48 were unique to the probiotic-treated group. The relative abundance of genus Bacillus and species Bacillus velezensis was enriched in probiotic piglets; the phylogenetic investigation of communities by the reconstruction of unobserved states indicated that amino acid metabolism, DNA repair, replication and recombination proteins, and secretion systems were enriched with probiotics. In conclusion, the Clostridium butyricum-based probiotics improved growth performance, enhanced intestinal morphology, changed hypothalamic neurotransmitters and modulated colonic microflora in weaned piglets.

Metabolic Profiling of Human Plasma and Urine, Targeting Tryptophan, Tyrosine and Branched Chain Amino Acid Pathways

Tryptophan and tyrosine metabolism has a major effect on human health, and disorders have been associated with the development of several pathologies. Recently, gut microbial metabolism was found to be important for maintaining correct physiology. Here, we describe the development and validation of a UHPLC-ESI-MS/MS method for targeted quantification of 39 metabolites related to tryptophan and tyrosine metabolism, branched chain amino acids and gut-derived metabolites in human plasma and urine. Extraction from plasma was optimised using 96-well plates, shown to be effective in removing phospholipids. Urine was filtered and diluted ten-fold. Metabolites were separated with reverse phase chromatography and detected using triple quadrupole MS. Linear ranges (from ppb to ppm) and correlation coefficients (r² > 0.990) were established for both matrices independently and the method was shown to be linear for all tested metabolites. At medium spiked concentration, recovery was over 80% in both matrices, while analytical precision was excellent (CV < 15%). Matrix effects were minimal and retention time stability was excellent. The applicability of the methods was tested on biological samples, and metabolite concentrations were found to be in agreement with available data. The method allows the analysis of up to 96 samples per day and was demonstrated to be stable for up to three weeks from acquisition.

Probiotics for Gastrointestinal Symptoms and Quality of Life in Autism: A Placebo-Controlled Pilot Trial

Objective: A randomized pilot trial of gastrointestinal (GI) symptoms targeting probiotic for quality of life in autism spectrum disorder (ASD). Methods: Thirteen children, 3-12 years of age with ASD, anxiety, and GI symptoms, were randomized into a probiotic crossover trial of 8 weeks each on VISBIOME and placebo separated by a 3-week washout. VISBIOME contains eight probiotic species, mostly Lactobacillus and Bifidobacterium. Primary outcome was the Pediatric Quality of Life Inventory (PedsQL) GI module. Secondary outcomes included gut microbiota analysis, the Parent-Rated Anxiety Scale for ASD (PRAS-ASD), and parent-selected target symptoms. A mixed analysis model was applied. Results: Thirteen children were randomized, with 10 completing the study (77% retention): 6 in probiotic/placebo sequence, 4 in placebo/probiotic sequence. Adherence to study treatment was 96%. There were no serious adverse events (AEs), and more nonserious AEs occurred with placebo than with probiotic, including those attributable to treatment. Only 6 of the 10 guessed the correct treatment at the end of week 8. Over the 19-week trial, each outcome improved from baseline and PedsQL correlated significantly with abundance of Lactobacillus without discernable changes to microbiota composition/diversity. Although probiotic showed more improvement than placebo, PedsQL and PRAS-ASD were not statistically significant, as expected at this sample size. PedsQL effect size was d = 0.49 by the general model and d = 0.79 by simple comparison of week 8 changes. A parent-selected target symptom showed significant improvement in GI complaints on probiotic compared with placebo (p = 0.02, d = 0.79). Probiotic effects carried over through the 3-week washout. Conclusion: The VISBIOME formulation was safe and suggested a health benefit in children with ASD and GI symptoms who retained Lactobacillus. The moderate effect size compared with placebo warrants a larger trial using a parallel-group design.

Posttraumatic stress disorder is associated with altered gut microbiota that modulates cognitive performance in veterans with cirrhosis

Posttraumatic stress disorder (PTSD) is associated with cirrhosis in veterans, and therapeutic results are suboptimal. An altered gut-liver-brain axis exists in cirrhosis due to hepatic encephalopathy (HE), but the added impact of PTSD is unclear. The aim of this study was to define linkages between gut microbiota and cognition in cirrhosis with/without PTSD. Cirrhotic veterans (with/without prior HE) underwent cognitive testing [PHES, inhibitory control test (ICT), and block design test (BDT)], serum lipopolysaccharide-binding protein (LBP) and stool collection for 16S rRNA microbiota composition, and predicted function analysis (PiCRUST). PTSD was diagnosed using DSM-V criteria. Correlation networks between microbiota and cognition were created. Patients with/without PTSD and with/without HE were compared. Ninety-three combat-exposed male veterans [ (58 yr, MELD 11, 34% HE, 31% combat-PTSD (42 no-HE/PTSD, 19 PTSD-only, 22 HE-only, 10 PTSD+HE)] were included. PTSD patients had similar demographics, alcohol history, MELD, but worse ICT/BDT, and higher antidepressant use and LBP levels. Microbial diversity was lower in PTSD (2.1 ± 0.5 vs. 2.5 ± 0.5, P = 0.03) but unaffected by alcohol/antidepressant use. PTSD (P = 0.02) and MELD (P < 0.001) predicted diversity on regression. PTSD patients showed higher pathobionts (Enterococcus and Escherichia/Shigella) and lower autochthonous genera belonging to Lachnospiraceaeae and Ruminococcaceae regardless of HE. Enterococcus was correlated with poor cognition, while the opposite was true for autochthonous taxa regardless of PTSD/HE. Escherichia/Shigella was only linked with poor cognition in PTSD patients. Gut-brain axis-associated microbiota functionality was altered in PTSD. In male cirrhotic veterans, combat-related PTSD is associated with cognitive impairment, lower microbial diversity, higher pathobionts, and lower autochthonous taxa composition and altered gut-brain axis functionality compared with non-PTSD combat-exposed patients. Cognition was differentially linked to gut microbiota, which could represent a new therapeutic target.NEW & NOTEWORTHY Posttraumatic stress disorder (PTSD) in veterans with cirrhosis was associated with poor cognitive performance. This was associated with lower gut microbial diversity in PTSD with higher pathobionts belonging to Enterococcus and Escherichia/Shigella and lower beneficial taxa belonging to Lachnospiraceaeae and Ruminococcaceae, with functional alterations despite accounting for prior hepatic encephalopathy, psychoactive drug use, or model for end-stage liver disease score. Given the suboptimal response to current therapies for PTSD, targeting the gut microbiota could benefit the altered gut-brain axis in these patients.

The role of the brain-gut-microbiota axis in psychology: The importance of considering gut microbiota in the development, perpetuation, and treatment of psychological disorders

INTRODUCTION

The prevalence of psychological disorders remains stable despite steady increases in pharmacological treatments suggesting the need for auxiliary treatment options. Consideration of the brain-gut-microbiota axis (BGMA) has made inroads into reconceptualizing psychological illness from a more holistic perspective. While our understanding of the precise role of gut microbiota (GM) in psychological illness is in its infancy, it represents an attractive target for novel interventions.

METHOD

An extensive review of relevant literature was undertaken.

RESULTS

Gut microbiota are proposed to directly and indirectly influence mood, cognition, and behavior which are key components of mental health. This paper outlines how GM may be implicated in psychological disorders from etiology through to treatment and prevention using the Four P model of case formulation.

CONCLUSION

Moving forward, integration of GM into the conceptualization and treatment of psychological illness will require the discipline of psychology to undergo a significant paradigm shift. While the importance of the GM in psychological well-being must be respected, it is not proposed to be a panacea, but instead, an additional arm to a multidisciplinary approach to treatment and prevention.

The Gut Microbiome and Mental Health: What Should We Tell Our Patients?: Le microbiote Intestinal et la Santé Mentale : que Devrions-Nous dire à nos Patients?

The gut microbiome as a potential therapeutic target for mental illness is a hot topic in psychiatry. Trillions of bacteria reside in the human gut and have been shown to play a crucial role in gut-brain communication through an influence on neural, immune, and endocrine pathways. Patients with various psychiatric disorders including depression, bipolar disorder, schizophrenia, and autism spectrum disorder have been shown to have significant differences in the composition of their gut microbiome. Enhancing beneficial bacteria in the gut, for example, through the use of probiotics, prebiotics, or dietary change, has the potential to improve mood and reduce anxiety in both healthy people and patient groups. Much attention is being given to this subject in the general media, and patients are becoming increasingly interested in the potential to treat mental illness with microbiome-based therapies. It is imperative that those working with people with mental illness are aware of the rationale and current evidence base for such treatment strategies. In this review, we provide an overview of the gut microbiome, what it is, and what it does in relation to gut-brain communication and psychological function. We describe the fundamental principles and basic techniques used in microbiome-gut-brain axis research in an accessible way for a clinician audience. We summarize the current evidence in relation to microbiome-based strategies for various psychiatric disorders and provide some practical advice that can be given to patients seeking to try a probiotic for mental health benefit.

Neuroactive compounds in foods: Occurrence, mechanism and potential health effects

Neuroactive compounds are synthesized by certain plants and microorganisms by undertaking different tasks, especially as a stress response. Most common neuroactive compounds in foods are gamma-aminobutyric acid (GABA), serotonin, melatonin, kynurenine, kynurenic acid, dopamine, norepinephrine, histamine, tryptamine, tyramine and β-phenylethylamine. Fermented foods contain some of these compounds, which can affect human health and mood. Moreover, food processing such as roasting and malting alter amount and profile of neuroactive compounds in foods. In addition to plant-origin and microbially-formed neuroactive compounds in foods, these substances are also formed by gut microbiota, which is the most attractive subject to assess the interaction between gut microbiota and mental health. The discovery of microbiota-gut-brain axis calls for the investigation of the effects of diet on the formation of neuroactive compounds in the gut. Furthermore, probiotics and prebiotics are indispensable elements for the understanding of the food-mood relationship. The focus of this comprehensive review is to investigate the neuroactive compounds found naturally in foods or formed during fermentation. Their formation pathways in humans, plants and microorganisms, potential health effects, effects of diet on the formation of microbial metabolites including neuroactive compounds in the gut are discussed throughout this review. Furthermore, the importance of gut-brain axis, probiotics and prebiotics are discussed.

Degree of lipid saturation affects depressive-like behaviour and gut microbiota in mice

This study explored the effects of the degree of lipid saturation on depressive behaviour and gut microbiota in mice. Thirty-two mice were divided into normal (N), Prozac (NP), lard (L) and fish oil (F) groups. After a 12-week dietary intervention, the open field test (OFT) and the forced swim test (FST) were conducted before sacrifice. The mice in the L group exhibited anxiety-like behaviours in the OFT and depressive-like behaviours in the FST. A significant difference was observed in β-diversity indices between the L group and the F group. The abundance of Allobaculum and Bifidobacterium was significantly higher in the F group than in the L and N groups. The prefrontal cortex fatty acid composition was altered in various lipid-treated groups and was highly correlated with depressive-like behaviours. In conclusion, the degree of lipid saturation affects depressive-like behaviour, gut microbiota composition, and the prefrontal cortex fatty acid profile in mice.

The Microbiota-Gut-Brain Axis

The importance of the gut-brain axis in maintaining homeostasis has long been appreciated. However, the past 15 yr have seen the emergence of the microbiota (the trillions of microorganisms within and on our bodies) as one of the key regulators of gut-brain function and has led to the appreciation of the importance of a distinct microbiota-gut-brain axis. This axis is gaining ever more traction in fields investigating the biological and physiological basis of psychiatric, neurodevelopmental, age-related, and neurodegenerative disorders. The microbiota and the brain communicate with each other via various routes including the immune system, tryptophan metabolism, the vagus nerve and the enteric nervous system, involving microbial metabolites such as short-chain fatty acids, branched chain amino acids, and peptidoglycans. Many factors can influence microbiota composition in early life, including infection, mode of birth delivery, use of antibiotic medications, the nature of nutritional provision, environmental stressors, and host genetics. At the other extreme of life, microbial diversity diminishes with aging. Stress, in particular, can significantly impact the microbiota-gut-brain axis at all stages of life. Much recent work has implicated the gut microbiota in many conditions including autism, anxiety, obesity, schizophrenia, Parkinson’s disease, and Alzheimer’s disease. Animal models have been paramount in linking the regulation of fundamental neural processes, such as neurogenesis and myelination, to microbiome activation of microglia. Moreover, translational human studies are ongoing and will greatly enhance the field. Future studies will focus on understanding the mechanisms underlying the microbiota-gut-brain axis and attempt to elucidate microbial-based intervention and therapeutic strategies for neuropsychiatric disorders.

Monocyte mobilisation, microbiota & mental illness

The gastrointestinal microbiome has emerged as a key player in regulating brain and behaviour. This has led to the strategy of targeting the gut microbiota to ameliorate disorders of the central nervous system. Understanding the underlying signalling pathways in which the microbiota impacts these disorders is crucial for the development of future therapeutics for improving CNS functionality. One of the major pathways through which the microbiota influences the brain is the immune system, where there is an increasing appreciation for the role of monocyte trafficking in regulating brain homeostasis. In this review, we will shed light on the role of monocyte trafficking as a relay of microbiota signals in conditions where the central nervous system is in disorder, such as stress, peripheral inflammation, ageing, traumatic brain injury, stroke, multiple sclerosis, Alzheimer's disease and Parkinson's disease. We also cover how the gastrointestinal microbiota is implicated in these mental illnesses. In addition, we aim to discuss how the monocyte system can be modulated by the gut microbiota to mitigate disorders of the central nervous system, which will lead to novel microbiota-targeted strategies.