The microbiota-gut-brain axis in gastrointestinal disorders: stressed bugs, stressed brain or both?

Effects of weaning and inactivated Lactobacillus helveticus supplementation on dairy calf behavioral and physiological indicators of affective state

The objectives of this study were to determine if weaning would induce behavioral and physiological indicators of a negative affective state, and if supplementation of inactivated Lactobacillus helveticus (ILH) to dairy calves would reduce those indicators of negative affect during weaning. Male Holstein calves (n = 23) were enrolled in the study on d 1 of life. The calves were housed in individual pens in 1 of 4 rooms for the 42 d study. Calves began a stepdown weaning from 9 L/d of milk replacer (MR), at 150 g of MR powder/L, on d 35 and received 6 L/d on d 35 - 36, 3 L/d on d 37 - 38, and 0.4 L/d on d 39 - 42. The MR was divided between 3 meals/d until the last 0.4 L/d phase which was divided between 2 meals/d. Calves had ad libitum water access throughout the study and calf starter from d 28 onwards. Within room, calves were assigned to 1 of 2 treatments: 1) control (CON; n = 11) and 2) 5 g of ILH/d split over and mixed into the 0800 h and 2000 h milk feedings from d 3-42 (ILH; n = 12). Lying behavior was recorded using HOBO data loggers from d 21-41. On d 33, 37 and 41, infrared eye images were taken to determine maximum eye temperature (MET), saliva samples were collected to determine cortisol concentration, and play assessments were conducted to quantify play behavior. On d 34, 38, and 42, blood samples were collected to determine blood serotonin concentration, whereas on d 38 and 39, calves were tested with a cognitive task. A subset of calves (n = 5/treatment) were euthanized to collect gut and brain tissue samples for serotonin concentration on d 43. Weaning resulted in fewer (d 37-41, tendency: d 36), but longer (d 38-41, tendency: d 37), lying bouts and reduced play (d 41), although no changes in lying time, MET, saliva cortisol, nor blood serotonin were detected with initiation of weaning. Supplementation of ILH was associated with lower lying time throughout the study, and reduced play duration and higher salivary cortisol and MET during weaning. No differences in lying bouts, play count, blood and tissue (colon, ileum, prefrontal cortex and brain stem) serotonin concentration, and time to complete the cognitive task were detected between the treatments. Overall, weaning induced behavioral changes indicative of negative affective state, and some behavioral differences were observed with ILH supplementation both before and during weaning, with some physiological changes observed during weaning.

Stress and the gut-brain axis: an inflammatory perspective

The gut-brain axis (GBA) plays a dominant role in maintaining homeostasis as well as contributes to mental health maintenance. The pathways that underpin the axis expand from macroscopic interactions with the nervous system, to the molecular signals that include microbial metabolites, tight junction protein expression, or cytokines released during inflammation. The dysfunctional GBA has been repeatedly linked to the occurrence of anxiety- and depressive-like behaviors development. The importance of the inflammatory aspects of the altered GBA has recently been highlighted in the literature. Here we summarize current reports on GBA signaling which involves the immune response within the intestinal and blood-brain barrier (BBB). We also emphasize the effect of stress response on altering barriers' permeability, and the therapeutic potential of microbiota restoration by probiotic administration or microbiota transplantation, based on the latest animal studies. Most research performed on various stress models showed an association between anxiety- and depressive-like behaviors, dysbiosis of gut microbiota, and disruption of intestinal permeability with simultaneous changes in BBB integrity. It could be postulated that under stress conditions impaired communication across BBB may therefore represent a significant mechanism allowing the gut microbiota to affect brain functions.

Supplementation with stigma maydis polysaccharide attenuates autism-like behaviors and improves gut function in valproic acid-induced autism model male rats

Stigma maydis polysaccharide (SMPS) has regulatory effect on the intestinal microflora and promotes gastrointestinal peristalsis. Children with autism spectrum disorder (ASD) often experience gastrointestinal problems and dysbiosis in their gut microbiota. Our previous study revealed that SMPS interventions had an impact on the gut microbiota of valproic acid (VPA)-induced autism model rats. However, the effects of SMPS on the behavior and gut function of autism model rats remain poorly understood. Therefore, we gave different doses of SMPS intervention in the early stage of autism model rats to observe their developmental conditions and behavior performances. Through histological evaluation and real-time polymerase chain reaction (PCR), integrity of the intestinal structure and the expression of tight junction-related gene Zo-1 and Occludin were detected. The results indicated that SMPS intervention improved the physical development, learning and memory impairment, and social performance of autism model rats. Meanwhile, SMPS promoted intestinal peristalsis and restored the integrity of the intestinal structure, reduced the number of inflammatory cells, and increased the expression of the Zo-1 and Occludin genes. Furthermore, the expression levels of neurotransmitters (substance P, enkephalin, vasoactive intestinal peptide, and 5-hydroxytryptamine) in the hippocampal tissues were altered after SMPS treatment. In conclusion, SMPS could ameliorate ASD-like phenotypes and gut problems in autism model rats. Collectively, these results provide new evidence for the relationship between the gut-brain axis and ASD and suggest a novel therapeutic target for ASD treatment.

The hidden threat: Environmental toxins and their effects on gut microbiota

The human gut microbiota (GM), which consists of a complex and diverse ecosystem of bacteria, plays a vital role in overall wellness. However, the delicate balance of this intricate system is being compromised by the widespread presence of environmental toxins. The intricate connection between contaminants in the environment and human well-being has garnered significant attention in recent times. Although many environmental pollutants and their toxicity have been identified and studied in laboratory settings and animal models, there is insufficient data concerning their relevance to human physiology. Consequently, research on the toxicity of environmental toxins in GM has gained prominence in recent years. Various factors, such as air pollution, chemicals, heavy metals, and pesticides, have a detrimental impact on the composition and functioning of the GM. This comprehensive review aims to comprehend the toxic effects of numerous environmental pollutants, including antibiotics, endocrine-disrupting chemicals, heavy metals, and pesticides, on GM by examining recent research findings. The current analysis concludes that different types of environmental toxins can lead to GM dysbiosis and have various potential adverse effects on the well-being of animals. We investigate the alterations to the GM composition induced by contaminants and their impact on overall well-being, providing a fresh perspective on research related to pollutant exposure.

Migraine is associated with the development of adult patients with inflammatory bowel disease: a nationwide, population-based study

It has been reported that migraine is more common in patients with inflammatory bowel disease (IBD) than in general. However, the impact of migraine on the development of IBD has not yet been elucidated. The aim of this study was to determine the association between migraine and the development of IBD. This nationwide population-based cohort study was conducted using the Korean National Health Insurance Service (NHIS) database. A total of 10,628,070 people aged 20 years or older who had undergone a national health examination conducted by the NHIS in 2009 were followed up until 2017. The study population was divided into two groups according to the presence or absence of migraine. We analyzed the incidence of newly developed IBD, Crohn's disease (CD), or ulcerative colitis (UC) during the follow-up period. The incidence of IBD was significantly higher in patients with migraine (adjusted hazard ratio [aHR] with 95% confidence interval [95%CI] of 1.31 [1.173-1.468], p < 0.001), CD (aHR with 95%CI of 1.58 [1.237-2.013], p < 0.001) and UC (aHR with 95%CI of 1.26 [1.106-1.424], p < 0.001) than in those without migraine. After 5 years of follow-up, those with migraine showed curves implying cumulative incidences of IBD with a steep increase, especially for CD. In subgroup analysis, migraine was associated with the risk of UC in males (aHR, 1.431 vs. 1.117; interaction p = 0.042). Migraine is significantly associated with the development of IBD. Patients with migraine should be monitored carefully for the development of IBD.

Probiotics Show Promise as a Novel Natural Treatment for Neurological Disorders

Probiotics are beneficial microorganisms shown to improve human health when consumed regularly and in sufficient quantities. Numerous health benefits can be attained by possessing important metabolites with nutritional and medicinal qualities. It has been shown through scientific research that these living microbial consortiums can influence a variety of mental health outcomes, including but not limited to anxiety, depression, cognitive processes, stress responses, and behavioral patterns. Selected strains of bacteria and yeasts control how the central nervous system (CNS) communicates with the gut-brain axis (GBA) through neuronal, humoral, and metabolic pathways to ease mood. Psychobiotics are substances that can affect the digestive system as well as mood and anxiety. There is scant evidence to validate the beneficial effects of psychiatric drugs in treating neurological diseases or disorders. The therapeutic method of research into psychobiotics opens exciting prospects for the future of the field of development. This review compiles the current evidence available in the scientific literature on the use of probiotics to influence neurological disorders.

Disruption of the microbiota-gut-brain axis is a defining characteristic of the α-Gal A (-/0) mouse model of Fabry disease

Fabry disease (FD) is an X-linked metabolic disease caused by a deficiency in α-galactosidase A (α-Gal A) activity. This causes accumulation of glycosphingolipids, especially globotriaosylceramide (Gb3), in different cells and organs. Neuropathic pain and gastrointestinal (GI) symptoms, such as abdominal pain, nausea, diarrhea, constipation, and early satiety, are the most frequent symptoms reported by FD patients and severely affect their quality of life. It is generally accepted that Gb3 and lyso-Gb3 are involved in the symptoms; nevertheless, the origin of these symptoms is complex and multifactorial, and the exact mechanisms of pathogenesis are still poorly understood. Here, we used a murine model of FD, the male α-Gal A (-/0) mouse, to characterize functionality, behavior, and microbiota in an attempt to elucidate the microbiota-gut-brain axis at three different ages. We provided evidence of a diarrhea-like phenotype and visceral hypersensitivity in our FD model together with reduced locomotor activity and anxiety-like behavior. We also showed for the first time that symptomology was associated with early compositional and functional dysbiosis of the gut microbiota, paralleled by alterations in fecal short-chain fatty acid levels, which partly persisted with advancing age. Interestingly, most of the dysbiotic features suggested a disruption of gut homeostasis, possibly contributing to accelerated intestinal transit, visceral hypersensitivity, and impaired communication along the gut-brain axis.

Development programming: Stress during gestation alters offspring development in sheep

Inappropriate management practices of domestic animals during pregnancy can be potential stressors, resulting in complex behavioural, physiological and neurological consequences in the developing offspring. Some of these consequences can last into adulthood or propagate to subsequent generations. We systematically summarized the results of different experimental patterns using artificially increased maternal glucocorticoid levels or prenatal maternal physiological stress paradigms, mediators between prenatal maternal stress (PMS) and programming effects in the offspring and the effects of PMS on offspring phenotypes in sheep. PMS can impair birthweight, regulate the development of the hypothalamic-pituitary-adrenal axis, modify behavioural patterns and cognitive abilities and alter gene expression and brain morphology in offspring. Further research should focus on the effects of programming on gene expression, immune function, gut microbiome, sex-specific effects and maternal behaviour of offspring, especially comparative studies of gestational periods when PMS is applied, continual studies of programming effects on offspring and treatment strategies that effectively reverse the detrimental programming effects of prenatal stress.

Implication of microbiota gut-brain axis in the manifestation of obsessive-compulsive disorder: Preclinical and clinical evidence

Recent research has highlighted the key role of gut microbiota in the development of psychiatric disorders. The adverse impact of stress, anxiety, and depression has been well documented on the commensal gut microflora. Thus, therapeutic benefits of gut microbiota-based interventions may not be avoided in central nervous system (CNS) disorders. In this review, we outline the current state of knowledge of gut microbiota with respect to obsessive-compulsive disorder (OCD). We discuss how OCD-generated changes corresponding to the key neurotransmitters, hypothalamic-pituitary-adrenal axis, and immunological and inflammatory pathways are connected with the modifications of the microbiota-gut-brain axis. Notably, administration of few probiotics such as Lactobacillus rhamnosus (ATCC 53103), Lactobacillus helveticus R0052, Bifidobacterium longum R0175, Saccharomyces boulardii, and Lactobacillus casei Shirota imparted positive effects in the management of OCD symptoms. Taken together, we suggest that the gut microbiota-directed therapeutics may open new treatment approaches for the management of OCD.

Lactic Acid Bacteria and Aging: Unraveling the Interplay for Healthy Longevity

Lactic Acid Bacteria (LAB) are beneficial microorganisms widely utilized in food fermentation processes and as probiotic supplements. They offer multifarious health benefits, including enhancing digestion, strengthening immune mechanisms, and mitigating inflammation. Recent studies suggest that LAB might be instrumental in the anti-aging domain, modulating key molecular pathways involved in the aging continuum, such as IL-13, TNF-α, mTOR, IFN-γ, TGF-β, AMPK, and GABA. The TLR family, particularly TLR2, appears pivotal during the primary cellular interactions with bacteria and their byproducts. Concurrently, the Sirtuin family, predominantly Sirtuin-1, plays diverse roles upon cellular stimuli by bacterial components. The potential anti-aging benefits postulated include restoring gut balance, enhancing antioxidant potential, and fortifying cognitive and mental faculties. However, the current body of evidence is still embryonic and calls for expansive human trials and deeper mechanistic analyses. The safety and optimal consumption metrics for LAB also warrant rigorous evaluation. Future research trajectories should identify specific LAB strains with potent anti-aging properties and unravel the underlying biological pathways. Given the promising implications, LAB strains stand as potential dietary contenders to foster healthy aging and enrich the quality of life among the elderly population.

Psychological, behavioural and biological factors associated with gastrointestinal symptoms in autistic adults and adults with autistic traits

LAY ABSTRACT

Little is known about factors related to the increased risk for gastrointestinal symptoms in adults with an autism spectrum disorder (ASD), while the negative impact of gastrointestinal symptoms is evident. Especially, the relationship between gastrointestinal symptoms and psychological, behavioural, and biological risk factors in adults with ASD (traits) is unclear. Autistic peer support workers and autism-advocates also emphasised the importance of identifying risk factors, because of the high prevalence of gastrointestinal problems in people with ASD. Therefore, our study investigated which psychological, behavioural, and biological factors are associated with gastrointestinal symptoms in adults with ASD or with autistic traits. We analysed data from 31,185 adults in the Dutch Lifelines Study. Questionnaires were used to evaluate the presence of an autism spectrum disorder diagnosis, autistic traits, gastrointestinal symptoms, psychological and behavioural factors. Biological factors were examined with body measurements. We found that not only adults with ASD but also adults with higher levels of autistic traits were at increased risk for gastrointestinal symptoms. Adults with ASD who experienced psychological problems (psychiatric problems, worse perceived health, chronic stress) had a higher risk for gastrointestinal symptoms than adults with ASD without these psychological problems. Moreover, adults with higher levels of autistic traits were less physically active, which was also associated with gastrointestinal symptoms. In conclusion, our study highlights the relevance of identifying psychological problems and evaluating physical activity when trying to help adults with ASD or autistic traits and gastrointestinal symptoms. This suggests that healthcare professionals should be more aware of behavioural and psychological risk factors when evaluating gastrointestinal symptoms in adults with ASD (traits).

Sleep loss impairs intestinal stem cell function and gut homeostasis through the modulation of the GABA signalling pathway in Drosophila

Sleep is essential for maintaining health. Indeed, sleep loss is closely associated with multiple health problems, including gastrointestinal disorders. However, it is not yet clear whether sleep loss affects the function of intestinal stem cells (ISCs). Mechanical sleep deprivation and sss mutant flies were used to generate the sleep loss model. qRT-PCR was used to measure the relative mRNA expression. Gene knock-in flies were used to observe protein localization and expression patterns. Immunofluorescence staining was used to determine the intestinal phenotype. The shift in gut microbiota was observed using 16S rRNA sequencing and analysis. Sleep loss caused by mechanical sleep deprivation and sss mutants disturbs ISC proliferation and intestinal epithelial repair through the brain-gut axis. In addition, disruption of SSS causes gut microbiota dysbiosis in Drosophila. As regards the mechanism, gut microbiota and the GABA signalling pathway both partially played a role in the sss regulation of ISC proliferation and gut function. The research shows that sleep loss disturbed ISC proliferation, gut microbiota, and gut function. Therefore, our results offer a stem cell perspective on brain-gut communication, with details on the effect of the environment on ISCs.

The gut microbiota-brain axis in neurological disorder

The gut microbiota (GM) plays an important role in the physiology and pathology of the host. Microbiota communicate with different organs of the organism by synthesizing hormones and regulating body activity. The interaction of the central nervous system (CNS) and gut signaling pathways includes chemical, neural immune and endocrine routes. Alteration or dysbiosis in the gut microbiota leads to different gastrointestinal tract disorders that ultimately impact host physiology because of the abnormal microbial metabolites that stimulate and trigger different physiologic reactions in the host body. Intestinal dysbiosis leads to a change in the bidirectional relationship between the CNS and GM, which is linked to the pathogenesis of neurodevelopmental and neurological disorders. Increasing preclinical and clinical studies/evidence indicate that gut microbes are a possible susceptibility factor for the progression of neurological disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS) and autism spectrum disorder (ASD). In this review, we discuss the crucial connection between the gut microbiota and the central nervous system, the signaling pathways of multiple biological systems and the contribution of gut microbiota-related neurological disorders.

Mechanism and implications of pro-nature physical activity in antagonizing psychological stress: the key role of microbial-gut-brain axis

Appropriate physical activities and a biodiversity-rich environment are conducive to the relief of psychological stress, and pro-nature physical activities are a combination of the two, which has good application potential in antagonizing psychological stress, but the intervention mechanism is still unclear. The microbiota-gut-brain axis is cyclically associated with psychological stress, and psychological stress can affect the microbiota through the gut-brain pathway, and conversely, the microbiota can also affect the psychological stress-induced symptoms. It is suggested that the microbe-gut-brain axis may provide a new perspective and target for the treatment of psychological stress-related diseases. Pro-nature physical activity can improve the number of Firmicutes, short-chain fatty acids, Akkermansia bacteria, and the gut-brain barrier and further affect the HPA axis, BDNF, and serotonin pathways of gut-brain two-way communication, thereby maintaining the body's homeostasis and reducing antagonistic psychological stress. According to the comprehensive influence of physical activities on the microbiota-gut-brain axis, a "green + exercise prescription hypothesis" in line with the holistic medical concept is revealed, which is expected to be effective in the prevention, alleviation, and treatment of irritable bowel syndrome and neurodegenerative diseases. It provides new means for treating psychological stress-related diseases such as mental disorders and mood disorders. In addition, it enlightens the construction of green infrastructure that is conducive to the diversified contact of microorganisms in outdoor physical activities venues and induces healthy interaction between the human body and the microbial population in the natural ecology. However, the current research is still in its early stages, and the intervention effect and mechanism of pro-nature physical activities need further demonstration in the future.

Impact of auricular percutaneous electrical nerve field stimulation on gut microbiome in adolescents with irritable bowel syndrome: A pilot study

OBJECTIVES

Percutaneous electrical nerve field stimulation (PENFS) has documented efficacy for irritable bowel syndrome (IBS) via plausible vagal neuromodulation effects. The vagus nerve may affect gut microbiome composition via brain-gut-microbiome signaling. We aimed to investigate gut microbiome alterations by PENFS therapy in adolescent IBS patients.

METHODS

A prospective study of females with IBS aged 11-18 years receiving PENFS therapy for 4 weeks with pre- and post-intervention stool sampling was conducted. Outcome surveys completed pre-therapy, weekly, and post-therapy included IBS-Severity Scoring System (IBS-SSS), Visceral Sensitivity Index (VSI), Functional Disability Inventory (FDI), and the global symptom response scale (SRS). Bacterial DNA was extracted from stool samples followed by 16S rRNA amplification and sequencing. QIIME 2 (version 2022.2) was used for analyses of α and β diversity and differential abundance by group.

RESULTS

Twenty females aged 15.6 ± 1.62 years were included. IBS-SSS, VSI, and FDI scores decreased significantly after PENFS therapy (P < 0.0001, P = 0.0003, P = 0.0004, respectively). No intra- or interindividual microbiome changes were noted pre- versus post-therapy or between responders and non-responders. When response was defined by 50-point IBS-SSS score reduction, α diversity was higher in responders compared with non-responders at week 4 (P = 0.033). There was higher abundance of Blautia in excellent responders versus non-responders.

CONCLUSIONS

There were no substantial microbial diversity alterations with PENFS. Subjects with excellent therapeutic response showed an enrichment of relative abundance of Blautia, which may indicate that patients with specific microbial signature have a more favorable response to PENFS.

Estradiol-mediated protection against high-fat diet induced anxiety and obesity is associated with changes in the gut microbiota in female mice

Decreased estrogens during menopause are associated with increased risk of anxiety, depression, type 2 diabetes and obesity. Similarly, depleting estrogens in rodents by ovariectomy, combined with a high-fat diet (HFD), increases anxiety and adiposity. How estrogens and diet interact to affect anxiety and metabolism is poorly understood. Mounting evidence indicates that gut microbiota influence anxiety and metabolism. Here, we investigated the effects of estradiol (E) and HFD on anxiety, metabolism, and their correlation with changes in gut microbiota in female mice. Adult C57BL/6J mice were ovariectomized, implanted with E or vehicle-containing capsules and fed a standard diet or HFD. Anxiety-like behavior was assessed and neuronal activation was measured by c-fos immunoreactivity throughout the brain using iDISCO. HFD increased anxiety-like behavior, while E reduced this HFD-dependent anxiogenic effect. Interestingly, E decreased neuronal activation in brain regions involved in anxiety and metabolism. E treatment also altered gut microbes, a subset of which were associated with anxiety-like behavior. These findings provide insight into gut microbiota-based therapies for anxiety and metabolic disorders associated with declining estrogens in menopausal women.

Short-Chain Fatty Acids in the Microbiota-Gut-Brain Axis: Role in Neurodegenerative Disorders and Viral Infections

The gut-brain axis (GBA) is the umbrella term to include all bidirectional communication between the brain and gastrointestinal (GI) tract in the mammalian body. Evidence from over two centuries describes a significant role of GI microbiome in health and disease states of the host organism. Short-chain fatty acids (SCFAs), mainly acetate, butyrate, and propionate that are the physiological forms of acetic acid, butyric acid, and propionic acid respectively, are GI bacteria derived metabolites. SCFAs have been reported to influence cellular function in multiple neurodegenerative diseases (NDDs). In addition, the inflammation modulating properties of SCFAs make them suitable therapeutic candidates in neuroinflammatory conditions. This review provides a historical background of the GBA and current knowledge of the GI microbiome and role of individual SCFAs in central nervous system (CNS) disorders. Recently, a few reports have also identified the effects of GI metabolites in the case of viral infections. Among these viruses, the flaviviridae family is associated with neuroinflammation and deterioration of CNS functions. In this context, we additionally introduce SCFA based mechanisms in different viral pathogenesis to understand the former's potential as agents against flaviviral disease.

Stress and Kynurenine-Inflammation Pathway in Major Depressive Disorder

Major depressive disorder (MDD) is one of the most prevalent disorders and causes severe damage to people's quality of life. Lifelong stress is one of the major villains in triggering MDD. Studies have shown that both stress and MDD, especially the more severe conditions of the disorder, are associated with inflammation and neuroinflammation and the relationship to an imbalance in tryptophan metabolism towards the kynurenine pathway (KP) through the enzymes indoleamine-2,3-dioxygenase (IDO), which is mainly stimulated by pro-inflammatory cytokines and tryptophan-2,3-dioxygenase (TDO) which is activated primarily by glucocorticoids. Considering that several pathophysiological mechanisms of MDD underlie or interact with biological processes from KP metabolites, this chapter addresses and discusses the function of these mechanisms. Activities triggered by stress and the hypothalamic-pituitary-adrenal (HPA) axis and immune and inflammatory processes, in addition to epigenetic phenomena and the gut-brain axis (GBA), are addressed. Finally, studies on the function and mechanisms of physical exercise in the KP metabolism and MDD are pointed out and discussed.

Hypnotherapy and IBS: Implicit, long-term stress memory in the ENS?

The association between irritable bowel syndrome (IBS) and psychiatric and mood disorders may be more fundamental than was previously believed. Prenatal, perinatal, postnatal, and early-age conditions can have a key role in the development of IBS. Subthreshold mental disorders (SMDs) could also be a significant source of countless diverse diseases and may be a cause of IBS development. We hypothesize that stress-induced implicit memories may persist throughout life by epigenetic processes in the enteric nervous system (ENS). These stress-induced implicit memories may play an essential role in the emergence and maintenance of IBS. In recent decades, numerous studies have proven that hypnosis can improve the primary symptoms of IBS and also reduce noncolonic symptoms such as anxiety and depression and improve quality of life and cognitive function. These significant beneficial effects of hypnosis on IBS may be because hypnosis allows access to unconscious brain processes.

Cognitive, Emotional, Behavioral and Physiological Evaluation of the Relationship Between Brain and Gut Microbiota

The aim of this study is to examine the effect of gut microbiota on brain functions, mood and psychiatric disorders such as depression, anxiety and behavioral addictions, neurotransmitter levels, cognitive processes such as self-control, decision making and delayed gratification. In this context, the relevant literature was reviewed and the findings were evaluated. The relationships of the bidirectional communication between the brain-gut axis with cognitive, emotional, behavioral and physiological processes were explained with a diagram. As a result, although more research is needed on this subject, it has been observed that the brain-gut axis is bidirectionally established through neural, stress, endocrine and immune systems. In this bidirectional communication process, there are interactions in the context of cognitive, emotional, behavioral and other physiological factors. These factors both individually enter into bidirectional relationships with the brain and gut microbiota and are affected by the bidirectional communication between the brain and gut.

The Mobilizable Plasmid P3 of Salmonella enterica Serovar Typhimurium SL1344 Depends on the P2 Plasmid for Conjugative Transfer into a Broad Range of Bacteria In Vitro and In Vivo

The global rise of drug-resistant bacteria is of great concern. Conjugative transfer of antibiotic resistance plasmids contributes to the emerging resistance crisis. Despite substantial progress in understanding the molecular basis of conjugation in vitro, the in vivo dynamics of intra- and interspecies conjugative plasmid transfer are much less understood. In this study, we focused on the streptomycin resistance-encoding mobilizable plasmid pRSF1010^SL1344 (P3) of Salmonella enterica serovar Typhimurium strain SL1344. We show that P3 is mobilized by interacting with the conjugation machinery of the conjugative plasmid pCol1B9^SL1344 (P2) of SL1344. Thereby, P3 can be transferred into a broad range of relevant environmental and clinical bacterial isolates in vitro and in vivo. Our data suggest that S. Typhimurium persisters in host tissues can serve as P3 reservoirs and foster transfer of both P2 and P3 once they reseed the gut lumen. This adds to our understanding of resistance plasmid transfer in ecologically relevant niches, including the mammalian gut. IMPORTANCE S. Typhimurium is a globally abundant bacterial species that rapidly occupies new niches and survives unstable environmental conditions. As an enteric pathogen, S. Typhimurium interacts with a broad range of bacterial species residing in the mammalian gut. High abundance of bacteria in the gut lumen facilitates conjugation and spread of plasmid-carried antibiotic resistance genes. By studying the transfer dynamics of the P3 plasmid in vitro and in vivo, we illustrate the impact of S. Typhimurium-mediated antibiotic resistance spread via conjugation to relevant environmental and clinical bacterial isolates. Plasmids are among the most critical vehicles driving antibiotic resistance spread. Further understanding of the dynamics and drivers of antibiotic resistance transfer is needed to develop effective solutions for slowing down the emerging threat of multidrug-resistant bacterial pathogens.

Functional Gastrointestinal Disorders with Psychiatric Symptoms: Involvement of the Microbiome-Gut-Brain Axis in the Pathophysiology and Case Management

Functional Gastrointestinal Disorders have been an important cause of poor life quality in affected populations. The unclear etiology and pathophysiological mechanism alter the clinical evolution of the patient. Although a strong connection with psychological stress has been observed, it was not until recently that the gut-brain axis involvement has been revealed. Furthermore, the current literature not only promotes the gut-brain axis modulation as a therapeutical target for functional digestive disorders but also states that the gut microbiome has a main role in this bi-directional mechanism. Psychiatric symptoms are currently recognized as an equally important aspect of the clinical manifestation and modulation of both the digestive and central nervous systems and could be the best approach in restoring the balance. As such, this article proposes a detailed description of the physiology of the microbiome-gut-brain axis, the pathophysiology of the functional gastrointestinal disorders with psychiatric symptoms and current perspectives for therapeutical management, as revealed by the latest studies in the scientific literature.

Role of brain-gut-muscle axis in human health and energy homeostasis

The interrelationship between brain, gut and skeletal muscle plays a key role in energy homeostasis of the body, and is becoming a hot topic of research. Intestinal microbial metabolites, such as short-chain fatty acids (SCFAs), bile acids (BAs) and tryptophan metabolites, communicate with the central nervous system (CNS) by binding to their receptors. In fact, there is a cross-talk between the CNS and the gut. The CNS, under the stimulation of pressure, will also affect the stability of the intestinal system, including the local intestinal transport, secretion and permeability of the intestinal system. After the gastrointestinal tract collects information about food absorption, it sends signals to the central system through vagus nerve and other channels to stimulate the secretion of brain-gut peptide and produce feeding behavior, which is also an important part of maintaining energy homeostasis. Skeletal muscle has receptors for SCFAs and BAs. Therefore, intestinal microbiota can participate in skeletal muscle energy metabolism and muscle fiber conversion through their metabolites. Skeletal muscles can also communicate with the gut system during exercise. Under the stimulation of exercise, myokines secreted by skeletal muscle causes the secretion of intestinal hormones, and these hormones can act on the central system and affect food intake. The idea of the brain-gut-muscle axis is gradually being confirmed, and at present it is important for regulating energy homeostasis, which also seems to be relevant to human health. This article focuses on the interaction of intestinal microbiota, central nervous, skeletal muscle energy metabolism, and feeding behavior regulation, which will provide new insight into the diagnostic and treatment strategies for obesity, diabetes, and other metabolic diseases.

The effects of microbiota on reproductive health: A review

Reproductive issues are becoming an increasing global problem. There is increasing interest in the relationship between microbiota and reproductive health. Stable microbiota communities exist in the gut, reproductive tract, uterus, testes, and semen. Various effects (e.g., epigenetic modifications, nervous system, metabolism) of dysbiosis in the microbiota can impair gamete quality; interfere with zygote formation, embryo implantation, and embryo development; and increase disease susceptibility, thus adversely impacting reproductive capacity and pregnancy. The maintenance of a healthy microbiota can protect the host from pathogens, increase reproductive potential, and reduce the rates of adverse pregnancy outcomes. In conclusion, this review discusses microbiota in the male and female reproductive systems of multiple animal species. It explores the effects and mechanisms of microbiota on reproduction, factors that influence microbiota composition, and applications of microbiota in reproductive disorder treatment and detection. The findings support novel approaches for managing reproductive diseases through microbiota improvement and monitoring. In addition, it will stimulate further systematic explorations of microbiota-mediated effects on reproduction.

Sex-Dependent Effects of Inhaled Nicotine on the Gut Microbiome

INTRODUCTION

The impact of nicotine, the addictive component of both traditional cigarettes and e-cigarettes, on many physiological processes remains poorly understood. To date, there have been few investigations into the impact of nicotine on the gut microbiome, and these studies utilized oral administration rather than inhalation. This study aimed to establish if inhaled nicotine alters the gut microbiome and the effect of sex as a biological variable.

METHODS

Female (n = 8 air; n = 10 nicotine) and male (n = 10 air; n = 10 nicotine) C57BL6/J mice were exposed to air (control) or nicotine vapor (12 hour/day) for 13 weeks. A fecal sample was collected from each mouse at the time of sacrifice, and the gut microbiome was analyzed by 16S rRNA gene sequencing. QIIME2, PICRUSt, and STAMP were used to detect gut bacterial differences and functional metabolic pathways.

RESULTS

Sex-specific differences were observed in both alpha and beta diversities in the absence of nicotine. While nicotine alters microbial community structure in both male and female mice as revealed by the beta diversity metric, nicotine significantly reduced alpha diversity only in female mice. A total of 42 bacterial taxa from phylum to species were found to be significantly different among the treatment groups. Finally, analysis for functional genes revealed significant differences in twelve metabolic pathways in female mice and ten in male mice exposed to nicotine compared to air controls.

CONCLUSIONS

Nicotine inhalation alters the gut microbiome and reduces bacterial diversity in a sex-specific manner, which may contribute to the overall adverse health impact of nicotine.

IMPLICATIONS

The gut microbiota plays a fundamental role in the well-being of the host, and traditional cigarette smoking has been shown to affect the gut microbiome. The effects of nicotine alone, however, remain largely uncharacterized. Our study demonstrates that nicotine inhalation alters the gut microbiome in a sex-specific manner, which may contribute to the adverse health consequences of inhaled nicotine. This study points to the importance of more detailed investigations into the influence of inhaled nicotine on the gut microbiota.

Exploring the association between microbiota and behaviour in suckling piglets

It is increasingly recognised that the microbes residing in the gastrointestinal tract can influence brain physiology and behaviour, via the microbiota-gut-brain axis. Here, we made a first explorative evaluation at the association between the gut microbiota and behaviour in suckling piglets. 16S microbiota profiling information was obtained from two independent replicate experiments at 2 and 4 weeks of age. Piglets underwent a backtest to assess their personality or coping style at 2 weeks of age, and were subjected to a combined open field and novel object test at 3.5 weeks of age, recording anxiety-related and exploratory behaviour. The number of squeals vocalised during the open field test was associated with microbial groups such as Coprococcus 3 and CAG-873, whereas in the novel object test, explorative behaviour was significantly associated with microbial genera like Atopobium and Prevotella. Overall, this study explores the microbiota-behavioural relation by employing multivariate analysis and exemplifies the importance of individualised analyses when evaluating such relationships.

The potential of dandelion in the fight against gastrointestinal diseases: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Dandelion (Taraxacum officinale Weber ex F. H. Wigg.), as a garden weed grown globally, has long been consumed as a therapeutic herb. Its folkloric uses include treatments of digestive disorders (dyspepsia, anorexia, stomach disorders, gastritis and enteritis) and associate complex ailments involving uterine, liver and lung disorders.

AIM OF THE STUDY

The present study aims to critically assess the current state of research and summarize the potential roles of dandelion and its constituents in gastrointestinal (GI) -protective actions. A focus is placed on the reported bioactive components, pharmacological activities and modes of action (including molecular mechanisms and interactions among bioactive substances) of dandelion products/preparations and derived active constituents related to GI protection.

MATERIALS AND METHODS

The available information published prior to August 2021 was reviewed via SciFinder, Web of Science, Google Scholar, PubMed, Elsevier, Wiley On-line Library, and The Plant List. The search was based on the ethnomedical remedies, pharmacological activities, bioactive compounds of dandelion for GI protection, as well as the interactions of the components in dandelion with the gut microbiota or biological regulators, and with other ingested bioactive compounds. The key search words were "Taraxacum" and "dandelion".

RESULTS

T. coreanum Nakai, T. mongolicum and T. officinale are the most commonly used species for folkloric uses, with the whole plant, leaves and root of dandelion being used more frequently. GI-protective substances of dandelion include taraxasterol, taraxerol, caffeic acid, chicoric acid, chlorogenic acid, luteolin and its glucosides, polysaccharides, inulin, and β-sitosterol. Dandelion products and derived constituents exhibit pharmacological effects against GI disorders, mainly including dyspepsia, gastroesophageal reflux disease, gastritis, small intestinal ulcer, ulcerative colitis, liver diseases, gallstones, acute pancreatitis, and GI malignancy. The underlying molecular mechanisms may include immuno-inflammatory mechanisms, apoptosis mechanism, autophagy mechanism, and cholinergic mechanism, although interactions of dandelion's constituents with GI health-related biological entities (e.g., GI microbiota and associated biological modulators) or other ingested bioactive compounds shouldn't be ignored.

CONCLUSION

The review reveals some in vivo and in vitro studies on the potential of dandelion derived products as complementary and alternative medicines/therapeutics against GI disorders. The whole herb may alleviate some symptoms related GI immuno-inflammatory basing on the abundant anti-inflammatory and anti-oxide active substances. Dandelion root could be a nontoxic and effective anticancer alternative, owing to its abundant terpenoids and polysaccharides. However, research related to GI protective dandelion-derived products remains limited. Besides the need of identifying bioactive compounds/complexes in various dandelion species, more clinical studies are also required on the metabolism, bioavailability and safety of these substances to support their applications in food, medicine and pharmaceuticals.

Alterations of the gut microbiota in borderline personality disorder

OBJECTIVE

A growing body of research has shown that people with a wide range of psychiatric disorders, including depression, present with alterations of the gut microbiota, although it is unclear if differences may be caused by the action of psychotropic medication. No data exist for patients with borderline personality disorder (BPD), a psychiatric condition that is frequently comorbidly associated with depression.

METHODS

Twenty-four unmedicated patients and twenty-one age- and sex-matched healthy controls were recruited. Stool samples were frozen at -80 °C within ten minutes after defecation. The V4 region of bacterial 16S ribosomal RNA (rRNA) gene was sequenced on an Illumina platform. Operational taxonomic units (OTUs) were used for further analysis of community structure, alpha- and beta-diversity.

RESULTS

There was no significant difference in alpha- and beta-diversity between patients and controls. However, the Bacteroidetes/Firmicutes-ratio was higher in patients, approaching significance (p = 0.06, r = 0.23). Four species were significantly less abundant in BPD patients, namely Pseudoflavonifractor phocaensis (p = 0.003, r = 0.41), Eubacterium coprostanoligenes (p = 0.01, r = 0.34), Anaerotaenia torta (p = 0.01, r = 0.35), and (statistically somewhat weaker) Parabacteroides chongii (p = 0.046, r = 0.26), which correlated with various psychometric scores.

CONCLUSION

Differences in the taxonomic composition may indicate a potential dysbiosis among SCFA-producing bacteria in BPD. Future research is warranted to replicate these findings in independent and larger samples. If confirmed, the results suggest that microbiota-targeted therapies may be a useful adjunct strategy for BPD.

How Metabolomics Provides Novel Insights on Celiac Disease and Gluten-Free Diet: A Narrative Review

Celiac disease (CD) is an inflammatory autoimmune disorder triggered by the ingestion of gluten from wheat and other cereals. Nowadays, its positive diagnosis is based on invasive approaches such as the histological examination of intestinal biopsies and positive serology screening of antibodies. After proven diagnosis, the only admissible treatment for CD individuals is strict life-long adherence to gluten-free diet (GFD), although it is not a conclusive therapy. Acting by different mechanisms and with different etiologies, both CD and GFD have a great impact on gut microbiota that result in a different taxa composition. Altered production of specific metabolites reflects these microbiota changes. In this light, the currently available literature reports some suggestions about the possible use of specific metabolites, detected by meta-omics analyses, as potential biomarkers for a CD non-invasive diagnosis. To highlight insights about metabolomics application in CD study, we conducted a narrative dissertation of selected original articles published in the last decade. By applying a systematic search, it clearly emerged how the metabolomic signature appears to be contradictory, as well as poorly investigated.

Ginsenoside Rg1 mitigates morphine dependence via regulation of gut microbiota, tryptophan metabolism, and serotonergic system function

BACKGROUND

Morphine dependence, a devastating neuropsychiatric condition, may be closely associated with gut microbiota dysbiosis. Ginsenoside Rg1 (Rg1), an active ingredient extracted from the roots of Panax ginseng C.A. Meyer, has potential health-promoting effects on the nervous system. However, its role in substance use disorders remains unclear. Here, we explored the potential modulatory roles of Rg1 in protection against morphine dependence.

METHODS

Conditioned place preference (CPP) was used for establishing a murine model of morphine dependence. 16S rRNA gene sequencing and metabolomics were performed for microbial and metabolite analysis. Molecular analysis was tested for evaluating the host serum and brain responses.

RESULTS

Rg1 prevented morphine-induced CPP in mice. The 16S rRNA gene-based microbiota analysis demonstrated that Rg1 ameliorated morphine-induced gut microbiota dysbiosis, specifically for Bacteroidetes. Moreover, Rg1 also inhibited gut microbiota-derived tryptophan metabolism and reduced the serotonin, 5-hydroxytryptamine receptor 1B (5-HTR1B), and 5-hydroxytryptamine receptor 2 A (5-HTR2A) levels. However, the Rg1-induced amelioration of CPP was not observed in mice when their gut microbiome was depleted by non-absorbable antibiotics. Subsequently, gavage with Bacteroides vulgatus increased the abundance of Bacteroidetes. B. vulgatus supplementation synergistically enhanced Rg1-alleviated morphine-induced CPP in mice with microbiome knockdown. Co-treatment with B. vulgatus and Rg1 produced suppressive effects against morphine dependency by inhibiting tryptophan metabolism and reducing the serotonin and 5-HTR1B/5-HTR2A levels.

CONCLUSIONS

The gut microbiota-tryptophan metabolism-serotonin plays an important role in gut-brain signaling in morphine disorders, which may represent a novel approach for drug dependence treatment via manipulation of the gut microbial composition and tryptophan metabolite.

Bacteria and Bellicosity: Photoperiodic Shifts in Gut Microbiota Drive Seasonal Aggressive Behavior in Male Siberian Hamsters

The existence of a microbiome-gut-brain axis has been established wherein gut microbiota significantly impacts host behavior and physiology, with increasing evidence suggesting a role for the gut microbiota in maintaining host homeostasis. Communication between the gut microbiota and the host is bidirectional, and shifts in the composition of the gut microbiota are dependent on both internal and external cues (host-derived signals, such as stress and immunity, and endocrine and environmental signals, such as photoperiod). Although there is host-driven seasonal variation in the composition of the microbiota, the mechanisms linking photoperiod, gut microbiota, and host behavior have not been characterized. The results of the present study suggest that seasonal changes in the gut microbiota drive seasonal changes in aggression. Implanting short-day Siberian hamsters (Phodopus sungorus) with fecal microbiota from long-day hamsters resulted in a reversal of seasonal aggression, whereby short-day hamsters displayed aggression levels typical of long-day hamsters. In addition, there are correlations between aggressive behavior and several bacterial taxa. These results implicate the gut microbiota as part of the photoperiodic mechanism regulating seasonal host behavior and contribute toward a more comprehensive understanding of the relationships between the microbiota, host, and environment.

Supplementation with SCFAs Re-Establishes Microbiota Composition and Attenuates Hyperalgesia and Pain in a Mouse Model of NTG-Induced Migraine

Migraine is a common brain-disorder that affects 15% of the population. Converging evidence shows that migraine is associated with gastrointestinal disorders. However, the mechanisms underlying the interaction between the gut and brain in patients with migraine are not clear. In this study, we evaluated the role of the short-chain fatty acids (SCFAs) as sodium propionate (SP) and sodium butyrate (SB) on microbiota profile and intestinal permeability in a mouse model of migraine induced by nitroglycerine (NTG). The mice were orally administered SB and SP at the dose of 10, 30 and 100 mg/kg, 5 min after NTG intraperitoneal injections. Behavioral tests were used to evaluate migraine-like pain. Histological and molecular analyses were performed on the intestine. The composition of the intestinal microbiota was extracted from frozen fecal samples and sequenced with an Illumina MiSeq System. Our results demonstrated that the SP and SB treatments attenuated hyperalgesia and pain following NTG injection. Moreover, SP and SB reduced histological damage in the intestine and restored intestinal permeability and the intestinal microbiota profile. These results provide corroborating evidence that SB and SP exert a protective effect on central sensitization induced by NTG through a modulation of intestinal microbiota, suggesting the potential application of SCFAs as novel supportive therapies for intestinal disfunction associated with migraine.

Stressful events induce long-term gut microbiota dysbiosis and associated post-traumatic stress symptoms in healthcare workers fighting against COVID-19

OBJECTIVE

The microbiota-gut-brain axis is a key pathway perturbed by prolonged stressors to produce brain and behavioral disorders. Frontline healthcare workers (FHWs) fighting against COVID-19 typically experience stressful event sequences and manifest some mental symptoms; however, the role of gut microbiota in such stress-induced mental problems remains unclear. We investigated the association between the psychological stress of FHW and gut microbiota.

METHODS

We used full-length 16S rRNA gene sequencing to characterize the longitudinal changes in gut microbiota and investigated the impact of microbial changes on FHWs' mental status.

RESULTS

Stressful events induced significant depression, anxiety, and stress in FHWs and disrupted the gut microbiome; gut dysbiosis persisted for at least half a year. Different microbes followed discrete trajectories during the half-year of follow-up. Microbes associated with mental health were mainly Faecalibacterium spp. and [Eubacterium] eligens group spp. with anti-inflammatory effects. Of note, the prediction model indicated that low abundance of [Eubacterium] hallii group uncultured bacterium and high abundance of Bacteroides eggerthii at Day 0 (immediately after the two-month frontline work) were significant determinants of the reappearance of post-traumatic stress symptoms in FHWs.

LIMITATIONS

The lack of metabolomic evidence and animal experiments result in the unclear mechanism of gut dysbiosis-related stress symptoms.

CONCLUSION

The stressful event sequences of fighting against COVID-19 induce characteristic longitudinal changes in gut microbiota, which underlies dynamic mental state changes.

Magnesium Orotate and the Microbiome–Gut–Brain Axis Modulation: New Approaches in Psychological Comorbidities of Gastrointestinal Functional Disorders

Magnesium orotate has been cited in the medical literature for the past three years as a possible adjuvant in some pediatric and adult gastroenterological disorders associated with dysbiosis. Studies also focus on the possibility of adding magnesium orotate in psychiatric disorders’ treatment, such as major depression and anxiety. The most relevant element in these studies is the efficiency of magnesium orotate therapy in cases with both gastroenterological and psychiatric symptoms. This article proposes a literature review, focused on the studies published in the last three years, targeting magnesium orotate treatment and probiotic supplementation in patients with both digestive and psychiatric symptoms. Moreover, this review will compare the efficiency of magnesium orotate and probiotics within both the pediatric and adult communities, focusing on the possibility of gut–brain axis modulation and its involvement in the clinical evolution of these patients.

Effects of Probiotic Bacteria on Central Neuronal Activation in Experimental Colitis

BACKGROUND

Brain-gut axis dysregulation is observed in inflammatory bowel disease. However, the effect of altered gut flora on neuro- immunomodulation and its role in the pathogenesis of inflammatory bowel disease are unknown. The aims of this study are to determine (i) whether colitis modifies the expression of c-fos, a marker of general neuronal activation in the brain and (ii) whether this activation could be modulated by probiotic bacteria.

METHODS

In this study, 28 Sprague-Dawley rats were divided into 4 groups: colitis-probiotic group, non-colitis-fed-control group receiv- ing probiotic Lactobacillus delbrueckii subsp. Bulgaricus B3 strain for 7 days, colitis group, and sham group receiving only sodium chlo- ride. Colitis was induced by intracolonic administration of trinitrobenzene sulfonic acid-ethanol. The expression of c-fos was detected by immunohistochemistry in the brain tissue. Cytokines and inflammatory mediators were analyzed in the plasma. Histological scores and oxidative status were analyzed in the colon samples.

RESULTS

The inflammatory response was accompanied by increased levels of cytokines, lipid peroxidation activities, c-fos expression in the medial nucleus of the amygdala, and decreased levels of antioxidant enzymes in the colitis (P < .001). Probiotic treatment reversed those effects. Also, histopathologic scores were significantly lower in the probiotic-treated groups compared to the colitis group (P = .035). In contrast, the expression of c-fos was significantly increased in the paraventricular nucleus of hypothalamus in the probiotic- treated rats (P < .001).

CONCLUSION

Colitis and intestinal inflammation are associated with the activation of neurons in the limbic system creating stress-like effects in the brain. Probiotics diversely modulate limbic response and hypothalamic axis activity in addition to protective effects in inflammation.

The Therapeutic Role of Exercise and Probiotics in Stressful Brain Conditions

Oxidative stress has been recognized as a contributing factor in aging and in the progression of multiple neurological disorders such as Parkinson’s disease, Alzheimer’s dementia, ischemic stroke, and head and spinal cord injury. The increased production of reactive oxygen species (ROS) has been associated with mitochondrial dysfunction, altered metal homeostasis, and compromised brain antioxidant defence. All these changes have been reported to directly affect synaptic activity and neurotransmission in neurons, leading to cognitive dysfunction. In this context two non-invasive strategies could be employed in an attempt to improve the aforementioned stressful brain status. In this regard, it has been shown that exercise could increase the resistance against oxidative stress, thus providing enhanced neuroprotection. Indeed, there is evidence suggesting that regular physical exercise diminishes BBB permeability as it reinforces antioxidative capacity, reduces oxidative stress, and has anti-inflammatory effects. However, the differential effects of different types of exercise (aerobic exhausted exercise, anaerobic exercise, or the combination of both types) and the duration of physical activity will be also addressed in this review as likely determinants of therapeutic efficacy. The second proposed strategy is related to the use of probiotics, which can also reduce some biomarkers of oxidative stress and inflammatory cytokines, although their underlying mechanisms of action remain unclear. Moreover, various probiotics produce neuroactive molecules that directly or indirectly impact signalling in the brain. In this review, we will discuss how physical activity can be incorporated as a component of therapeutic strategies in oxidative stress-based neurological disorders along with the augmentation of probiotics intake.

Cross-lagged analyses between gastrointestinal symptoms, psychological distress, and disability in emerging adults

The gut-brain connection refers to communication between the brain and gastrointestinal (GI) system. Disorders of gut-brain interaction (DGBI) are characterized by GI symptoms that accompany distress and disability. Epidemiological research has suggested DGBI rates in emerging adults are increasing. This study investigated the relationship between GI health, distress, and disability in emerging adults across time. Emerging adults were recruited. A repeated-measure design with a 1-month time lag was used to collect data via an online survey (N = 861) across five academic semesters (Spring 2019 to Summer 2020). Measurement equivalence across time was established and a cross-lagged panel model (CLPM) was specified. Distress at Time 1 predicted GI symptoms at Time 2 (β = .206, SE = .084, p < .05). GI symptoms at Time 1 predicted disability at Time 2 (β = .117, SE = .039, p < .01). Higher disability at Time 1 predicted distress at Time 2 (β = .092, SE = .027, p < .01). The cross-lagged design offers stronger causal inferences than cross-sectional studies used to study the effects of GI symptoms. Findings provide initial evidence of a directional pathway between brain and gut rather than a bidirectional network. Findings highlight the importance of psychogastroenterology.

Chronic stress and captivity alter the cloacal microbiome of a wild songbird

There are complex interactions between an organism's microbiome and its response to stressors, often referred to as the “gut-brain axis;” however, the ecological relevance of this axis in wild animals remains poorly understood. Here, we used a chronic mild stress protocol to induce stress in wild-caught house sparrows (Passer domesticus), and compared microbial communities among stressed animals, those recovering from stress, captive controls (unstressed), and a group not brought into captivity. We assessed changes in microbial communities and abundance of shed microbes by culturing cloacal samples on multiple media to select for aerobic and anaerobic bacteria and fungi. We complemented this with cultivation-independent 16S and ITS rRNA gene amplification and sequencing, pairing these results with host physiological and immune metrics, including body mass change, relative spleen mass, and plasma corticosterone concentrations. We found significant effects of stress and captivity on the house sparrow microbiomes, with stress leading to an increased relative abundance of endotoxin-producing bacteria— a possible mechanism for the hyperinflammatory response observed in captive avians. While we found evidence that the microbiome community partially recovers after stress cessation, animals may lose key taxa, and the abundance of endotoxin-producing bacteria persists. Our results suggest an overall link between chronic stress, host immune system, and the microbiome, with the loss of potentially beneficial taxa (e.g., lactic acid bacteria), and an increase in endotoxin-producing bacteria due to stress and captivity. Ultimately, consideration of the host's microbiome may be useful when evaluating the impact of stressors on individual and population health.

Microbiota and Pain: Save Your Gut Feeling

Recently, a growing body of evidence has emerged regarding the interplay between microbiota and the nervous system. This relationship has been associated with several pathological conditions and also with the onset and regulation of pain. Dysregulation of the axis leads to a huge variety of diseases such as visceral hypersensitivity, stress-induced hyperalgesia, allodynia, inflammatory pain and functional disorders. In pain management, probiotics have shown promising results. This narrative review describes the peripheral and central mechanisms underlying pain processing and regulation, highlighting the role of the gut-brain axis in the modulation of pain. We summarized the main findings in regard to the stress impact on microbiota’s composition and its influence on pain perception. We also focused on the relationship between gut microbiota and both visceral and inflammatory pain and we provided a summary of the main evidence regarding the mechanistic effects and probiotics use.

No guts about it: captivity, but not neophobia phenotype, influences the cloacal microbiome of house sparrows (Passer domesticus)

Behavioral traits such as anxiety and depression have been linked to diversity of the gut microbiome in humans, domesticated animals, and lab-bred model species, but the extent to which this link exists in wild animals, and thus its ecological relevance, is poorly understood. We examined the relationship between a behavioral trait (neophobia) and the cloacal microbiome in wild house sparrows (Passer domesticus,n = 22) to determine whether gut microbial diversity is related to personality in a wild animal. We swabbed the cloaca immediately upon capture, assessed neophobia phenotypes in the lab, and then swabbed the cloaca again after several weeks in captivity to additionally test whether the microbiome of different personality types is affected disparately by captivity, and characterized gut microbiomes using 16S rRNA gene amplicon sequencing. We did not detect differences in cloacal alpha or beta microbial diversity between neophobic and non-neophobic house sparrows, and diversity for both phenotypes was negatively impacted by captivity. Although our results suggest that the adult cloacal microbiome and neophobia are not strongly linked in wild sparrows, we did detect specific OTUs that appeared more frequently and at higher abundances in neophobic sparrows, suggesting that links between the gut microbiome and behavior may occur at the level of specific taxa. Further investigations of personality and the gut microbiome are needed in more wild species to reveal how the microbiome-gut-brain axis and behavior interact in an ecological context.

Cerebral Metabolic Analysis of Patients With Colorectal Cancer and Chronic Enteritis: Inquiry Into Gut-Brain Crosstalk

Gut-brain crosstalk has been demonstrated previously. However, brain metabolic patterns of colorectal cancer and chronic enteritis remain unclear. A better understanding of gut-brain crosstalk from a radiological perspective is necessary. We conducted a retrospective study in which we acquired ¹⁸F-fluorodeoxyglucose positron emission tomography in 45 colorectal cancer cases, 45 age- and sex-matched chronic enteritis patients, and 45 age- and sex-matched healthy controls. We calculated a scaled sub-profile pattern based on principal component analysis and metabolic connectivity to explore the brain metabolic model and analyzed correlations between various brain regions and cancer to identify potential neuroimaging markers for non-pharmaceutical therapies. We found a characteristic cerebral metabolic pattern in colorectal cancer patients, which mainly involved visceral sensation and both affective and cognitive psychological processes. The metabolic patterns of patients with colorectal cancer and chronic enteritis were similar but not identical. The metabolic connectivity of the postcentral gyrus and paracentral lobule was found to be significantly different between the controls and patients with colorectal cancer (p < 0.05, false discovery rate correction). The maximal standard uptake value of the cancer focus in colorectal cancer patients was negatively correlated with the dorsolateral superior frontal gyrus (p < 0.05). Patients with colorectal cancer may show abnormal glucose cerebral metabolism characterized by “point-line-surface.” This preliminary study revealed the cerebral metabolic characteristics and neurobiological mechanisms of colorectal cancer and chronic enteritis (ChiCTR2000041020; registered December 16, 2020).

The gut microbiome as a target for adjuvant therapy in insomnia disorder

Insomnia is a type of sleep disorder which has negative impacts on the quality of life, mood, cognitive function and health of humans. The etiology of insomnia may be related to many factors such as genetics, biochemistry, neuroendocrine, immune, and psychosocial factors. However, the detailed pathological aspects of insomnia remain unclear. Recent investigation of the microbiome-gut-brain axis enhances our understanding of the role of the gut microbiota in brain-related diseases. Gut microbiome has been shown to be associated with insomnia. However, the available data in this field remain limited and the relevant scientific work has only recently begun. This review aims to summarize the recent literature as an aid to better understanding how the alteration of gut microbiota composition contributes to insomnia while evaluating and prospecting the therapeutic effect of modulating gut microbiota in the treatment of insomnia based on previous publications.

Temporal Relationships Between Abdominal Pain, Psychological Distress and Coping in Patients With IBS - A Time Series Approach

OBJECTIVE

Irritable bowel syndrome (IBS) is a chronic disease leading to abdominal pain that is often related to psychological distress. The aim of the study was to investigate the temporal relationships between abdominal pain and psychological variables in patients with IBS.

METHODS

This longitudinal diary study included eight patients from a waiting group, recruited in the frame of a pilot intervention study. During their waiting time of 3 months the patients answered questions daily regarding somatic and psychological variables using an online diary. All patients were considered and analyzed as single cases. The temporal dynamics between the time series of psycho-somatic variables were analyzed using a vector autoregressive (VAR) modeling approach.

RESULTS

For all patients, positive same-day correlations between somatic and psychological time series were observed. The highest same-day correlations were found between somatic symptoms and pain-related discomfort (r = 0.40 to r = 0.94). Altogether, n = 26 significant lagged relationships were identified; n = 17 (65%) indicated that somatic values were predictive of psychological complaints on the following days. N = 9 (35%) lagged relationships indicated an opposite relationship in that psychological complaints were predictive of somatic symptoms. Three patients showed a significant positive same-day correlation between abdominal pain and use of a positive coping strategy. However, significant lagged relationships in two patients showed that for these patients the use of positive thinking as a coping strategy was unhelpful in reducing pain on the following days.

CONCLUSIONS

In patients with IBS abdominal symptoms appear to be closely related to psychological symptoms. For some patients, somatic complaints predict psychological complaints, in other patients the directionality is opposite. The impact of coping strategies on somatic symptoms varies among patients, therefore their role for a possible reduction of pain should be further explored. The results suggest the need of characterizing patientsindividually for effective health interventions. Individual time series analyses provide helpful tools for finding reasonable person-level moderators.

The rising dominance of microbiology: what to expect in the next 15 years?

What microbiology beholds after a decade and a half in the future requires a vision based on the facts and ongoing trends in research and technological advancements. While the latter, assisted by microbial dark matter, presents a greater potential of creating an upsurge in in-situ and ex-situ rapid microbial detection techniques, this anticipated change will also set forth a revolution in microbial cultivation and diversity analyses. The availability of a microbial genetic toolbox at the expanse will help complement the current understanding of the microbiome and assist in real-time monitoring of the dynamics for detecting the health status of the host with utmost precision. Alongside, in light of the emerging infectious diseases, antimicrobial resistance (AMR) and social demands for safer and better health care alternatives, microbiology laboratories are prospected to drift in terms of the volume and nature of research and outcomes. With today's microbiological lens, one can predict with certainty that in the years to come, microbes will play a significant role in therapeutic treatment and the designing of novel diagnostic techniques. Another area where the scope of microbial application seems to be promising is the use of novel probiotics as a method to offer health benefits whilst promoting metabolic outputs specific for microbiome replenishment. Nonetheless, the evolution of extraterrestrial microbes or the adaptation of earth microbes as extraterrestrial residents are also yet another prominent microbial event one may witness in the upcoming years. But like the two sides of the coin, there is also an urgent need to dampen the bloom of urbanization, overpopulation and global trade and adopting sustainable approaches to control the recurrence of epidemics and pandemics.

Clinical health issues, reproductive hormones, and metabolic hormones associated with gut microbiome structure in African and Asian elephants

Background

The gut microbiome is important to immune health, metabolism, and hormone regulation. Understanding host–microbiome relationships in captive animals may lead to mediating long term health issues common in captive animals. For instance, zoo managed African elephants (Loxodonta africana) and Asian elephants (Elephas maximus) experience low reproductive rates, high body condition, and gastrointestinal (GI) issues. We leveraged an extensive collection of fecal samples and health records from the Elephant Welfare Study conducted across North American zoos in 2012 to examine the link between gut microbiota and clinical health issues, reproductive hormones, and metabolic hormones in captive elephants. We quantified gut microbiomes of 69 African and 48 Asian elephants from across 50 zoos using Illumina sequencing of the 16S rRNA bacterial gene.

Results

Elephant species differed in microbiome structure, with African elephants having lower bacterial richness and dissimilar bacterial composition from Asian elephants. In both species, bacterial composition was strongly influenced by zoo facility. Bacterial richness was lower in African elephants with recent GI issues, and richness was positively correlated with metabolic hormone total triiodothyronine (total T3) in Asian elephants. We found species-specific associations between gut microbiome composition and hormones: Asian elephant gut microbiome composition was linked to total T3 and free thyroxine (free T4), while fecal glucocorticoid metabolites (FGM) were linked to African elephant gut microbiome composition. We identified many relationships between bacterial relative abundances and hormone concentrations, including Prevotella spp., Treponema spp., and Akkermansia spp.

Conclusions

We present a comprehensive assessment of relationships between the gut microbiome, host species, environment, clinical health issues, and the endocrine system in captive elephants. Our results highlight the combined significance of host species-specific regulation and environmental effects on the gut microbiome between two elephant species and across 50 zoo facilities. We provide evidence of clinical health issues, reproductive hormones, and metabolic hormones associated with the gut microbiome structure of captive elephants. Our findings establish the groundwork for future studies to investigate bacterial function or develop tools (e.g., prebiotics, probiotics, dietary manipulations) suitable for conservation and zoo management.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42523-021-00146-9.

Brain morphometry and diminished physical growth in Bangladeshi children growing up in extreme poverty: A longitudinal study

Diminished physical growth is a common marker of malnutrition and it affects approximately 200 million children worldwide. Despite its importance and prevalence, it is not clear whether diminished growth relates to brain development and general cognitive ability. Further, diminished growth is more common in areas of extreme poverty, raising the possibility that it may mediate previously shown links between socioeconomic status (SES) and brain structure. To address these gaps, 79 children growing up in an extremely poor, urban area of Bangladesh underwent MRI at age six years. Structural brain images were submitted to Mindboggle software, a Docker-compliant and high-reproducibility tool for tissue segmentation and regional estimations of volume, surface area, cortical thickness, sulcal depth, and mean curvature. Diminished growth predicted brain morphometry and mediated the link between SES and brain morphometry most consistently for subcortical and white matter subcortical volumes. Meanwhile, brain volume in left pallidum and right ventral diencephalon mediated the relationship between diminished growth and full-scale IQ. These findings offer malnutrition as one possible pathway through which SES affects brain development and general cognitive ability in areas of extreme poverty.

Pediococcus acidilactici CCFM6432 mitigates chronic stress-induced anxiety and gut microbial abnormalities

The discovery of psychobiotics has improved the therapeutic choices available for clinical mental disorders and shows promise for regulating mental health in people by combining the properties of food and medicine. A Pediococcus acidilactici strain CCFM6432 was previously isolated and its mood-regulating effect was investigated in this study. Viable bacteria were given to chronically stressed mice for five weeks, and then the behavioral, neurobiological, and gut microbial changes were determined. CCFM6432 significantly reduced stress-induced anxiety-like behaviors, mitigated hypothalamic-pituitary-adrenal (HPA) axis hyperactivity, and reversed the abnormal expression of hippocampal phosphorylated CREB and the c-Fos protein. In particular, CCFM6432 improved the gut microbial composition by inhibiting the over-proliferated pathogenic bacteria (e.g., Escherichia-shigella) and promoting beneficial bacteria growth (e.g., Bifidobacterium). Lactic acid, rather than bacteriocin, was further confirmed as the key compound that determined the antimicrobial activity of CCFM6432. Collectively, these results first proved the psychobiotic potential of the Pediococcus acidilactici strain. Ingestion of CCFM6432, or fermented food containing it, may facilitate mental health management in daily life, especially during the COVID-19 pandemic.

The Microbiota-Gut-Brain Axis During Heat Stress in Chickens: A Review

Heat stress is a global issue for the poultry industries with substantial annual economic losses and threats to bird health and welfare. When chickens are exposed to high ambient temperatures, like other species they undergo multiple physiological alterations, including behavioral changes, such as cessation of feeding, initiation of a stress signaling cascade, and intestinal immune, and inflammatory responses. The brain and gut are connected and participate in bidirectional communication via the nervous and humoral systems, this network collectively known as the gut-brain axis. Moreover, heat stress not only induces hyperthermia and oxidative stress at the gut epithelium, leading to impaired permeability and then susceptibility to infection and inflammation, but also alters the composition and abundance of the microbiome. The gut microflora, primarily via bacterially derived metabolites and hormones and neurotransmitters, also communicate via similar pathways to regulate host metabolic homeostasis, health, and behavior. Thus, it stands to reason that reshaping the composition of the gut microbiota will impact intestinal health and modulate host brain circuits via multiple reinforcing and complementary mechanisms. In this review, we describe the structure and function of the microbiota-gut-brain axis, with an emphasis on physiological changes that occur in heat-stressed poultry.

A Microbiome-Driven Approach to Combating Depression During the COVID-19 Pandemic

The significant stressors brought about and exacerbated by COVID-19 are associated with startling surges in mental health illnesses, specifically those related to depressive disorders. Given the huge impact of depression on society, and an incomplete understanding of impactful therapeutics, we have examined the current literature surrounding the microbiome and gut-brain axis to advance a potential complementary approach to address depression and depressive disorders that have increased during the COVID-19 pandemic. While we understand that the impact of the human gut microbiome on emotional health is a newly emerging field and more research needs to be conducted, the current evidence is extremely promising and suggests at least part of the answer to understanding depression in more depth may lie within the microbiome. As a result of these findings, we propose that a microbiome-based holistic approach, which involves carefully annotating the microbiome and potential modification through diet, probiotics, and lifestyle changes, may address depression. This paper's primary purpose is to shed light on the link between the gut microbiome and depression, including the gut-brain axis and propose a holistic approach to microbiome modification, with the ultimate goal of assisting individuals to manage their battle with depression through diet, probiotics, and lifestyle changes, in addition to offering a semblance of hope during these challenging times.

Pain and psyche in a patient with irritable bowel syndrome: chicken or egg? A time series case report

BACKGROUND

Irritable bowel syndrome (IBS) appears to have a bidirectional interaction with both depressive and anxiety-related complaints. However, it remains unclear how exactly the psychological complaints, at the individual level, are related to somatic symptoms on a daily basis. This single case study investigates how somatic and psychological variables are temporally related in a patient with irritable bowel syndrome.

CASE REPORT

The patient was a woman in her mid-twenties with an IBS diagnosis. She reported frequent soft bowel movements (5-6 times per day), as well as flatulence and abdominal pain. She resembled a typical IBS patient; however, a marked feature of the patient was her high motivation for psychosomatic treatment as well as her willingness to try new strategies regarding the management of her symptoms. As an innovative approach this single case study used a longitudinal, observational, time series design. The patient answered questions regarding somatic and psychological variables daily over a period of twelve weeks with an online diary. The diary data was analysed using an autoregressive (VAR) modeling approach. Time series analyses showed that in most variables, strong same-day correlations between somatic (abdominal pain, daily impairment) and psychological time series (including coping strategies) were present. The day-lagged relationships indicated that higher values in abdominal pain on one day were predictive of higher values in the psychological variables on the following day (e.g. nervousness, tension, catastrophizing, hopelessness). The use of positive thinking as a coping strategy was helpful in reducing the pain on the following days.

CONCLUSION

In the presented case we found a high correlation between variables, with somatic symptoms temporally preceding psychological variables. In addition, for this patient, the use of positive thoughts as a coping strategy was helpful in reducing pain.