The joint power of sex and stress to modulate brain-gut-microbiota axis and intestinal barrier homeostasis: implications for irritable bowel syndrome

Polygonatum sibiricum polysaccharide regulation of gut microbiota: A viable approach to alleviate cognitive impairment

Polygonatum sibiricum has anti-inflammatory effects and is one of the well-known functional foods. Polygonatum sibiricum polysaccharide (PSP), as a traditional medicinal and food homologous substance, can regulate the balance of intestinal flora and short chain fatty acid levels, reduce intestinal permeability and serum endotoxin levels, and inhibit the activation of astrocytes and microglia. It can significantly alleviate neurological diseases and improve cognitive impairment. Current evidence suggests that bidirectional communication between the central nervous system and the gastrointestinal tract may affect the human nervous system, cognition, and behavior through the gut-brain axis. This article provides a systematic review, detailing the biological activity of PSP, and explores the pathogenesis of gut microbiota signaling in cognitive impairment, providing a promising strategy for improving cognitive impairment.

Amelioration of Serum Aβ Levels and Cognitive Impairment in APPPS1 Transgenic Mice Following Symbiotic Administration

Alzheimer's disease (AD) is a neurodegenerative process responsible for almost 70% of all cases of dementia. The clinical signs consist in progressive and irreversible loss of memory, cognitive, and behavioral functions. The main histopathological hallmark is the accumulation of amyloid-ß (Aß) peptide fibrils in the brain. To date, the origin of Aß has not been determined. Recent studies have shown that the gut microbiota produces Aß, and dysbiotic states have been identified in AD patients and animal models of AD. Starting from the hypothesis that maintaining or restoring the microbiota's eubiosis is essential to control Aß's production and deposition in the brain, we used a mixture of probiotics and prebiotics (symbiotic) to treat APPPS1 male and female mice, an animal model of AD, from 2 to 8 months of age and evaluated their cognitive performances, mucus secretion, Aβ serum concentration, and microbiota composition. The results showed that the treatment was able to prevent the memory deficits, the reduced mucus secretion, the increased Aβ blood levels, and the imbalance in the gut microbiota found in APPPS1 mice. The present study demonstrates that the gut-brain axis plays a critical role in the genesis of cognitive impairment, and that modulation of the gut microbiota can ameliorate AD's symptomatology.

Gender-specific insights into the irritable bowel syndrome pathophysiology. Focus on gut dysbiosis and permeability

Irritable bowel syndrome (IBS) is the most common functional gastrointestinal disorder involving the brain-gut interaction. IBS is characterized by persistent abdominal pain and changes in bowel habits. IBS exerts significant impacts on quality of life and imposes huge economic costs. Global epidemiological data reveal variations in IBS prevalence, both globally and between genders, necessitating comprehensive studies to uncover potential societal and cultural influences. While the exact pathophysiology of IBS remains incompletely understood, the mechanism involves a dysregulation of the brain-gut axis, leading to disturbed intestinal motility, local inflammation, altered intestinal permeability, visceral sensitivity, and gut microbiota composition. We reviewed several gender-related pathophysiological aspects of IBS pathophysiology, by focusing on gut dysbiosis and intestinal permeability. This perspective paves the way to personalized and multidimensional clinical management of individuals with IBS.

Profiling of Metabolites in a Fermented Soy Dietary Supplement Reinforces its Role in the Management of Intestinal Inflammation

SCOPE

Gastro-AD (GAD) is a soy flour derived product that undergoes an industrial fermentation with Lactobacillus delbrueckii R0187 and has demonstrated clinical effects in gastroesophageal reflux and peptic ulcer symptom resolution. The aim of this study is to describe and link GAD's metabolomic profile to plausible mechanisms that manifest and explain the documented clinical outcomes.

METHODS AND RESULTS

1H NMR spectroscopy with multivariate statistical analysis is used to characterize the prefermented soy flour and GAD products. The acquired spectra are screened using various resources and the molecular assignments are confirmed using total correlation spectroscopy (TOCSY). Peaks corresponding to different metabolites are integrated and compared between the two products for relative changes. HPLC and GC are used to quantify some specific molecules. NMR analyses demonstrate significant changes in the composition of various assigned bioactive moieties. HPLC and GC analysis demonstrate deglycation of isoflavones after fermentation, resulting in estrogenically active secondary metabolites that have been previously shown to help to reduce inflammation.

CONCLUSION

The identification of bioactive molecules, such as genistein and SCFAs, capable of modulating anti-inflammatory signaling cascades in the stomach's gastric and neuroendocrine tissues can explain the reported biological effects in GAD and is supported by in vivo data.

Carrageenan oligosaccharide alleviates intestinal damage via gut microflora through activating IMD/relish pathway in female Drosophila melanogaster

Recent evidence suggests the anti-inflammatory effect of carrageenan oligosaccharides (COS). The effects of COS on intestinal injury induced by 0.6% sodium dodecyl sulfate (SDS) and the molecular mechanisms involved were investigated in this study. 0.625, 1.25, and 2.5 mg/mL COS in diet had no toxic effect in flies, and they could all prolong SDS-treated female flies' survival rate. 1.25 mg/mL COS prevented the development of inflammation by improving the intestinal barrier integrity and maintaining the intestinal morphology stability, inhibited the proliferation of intestine stem cells (ISCs), and the production of lysosomes induced by SDS, accompanied by a decrease in the expression of autophagy-related genes. Moreover, COS decreased the active oxygen species (ROS) content in gut and increased the antioxidant activity in SDS-induced female flies, while COS still played a role in increasing survival rate and decreasing intestinal leakage in CncC-RNAi flies. The improvement of anti-inflammation capacity may be associated with the regulation of intestinal microflora with COS supplementation for Drosophila melanogaster. COS changed the gut microbiota composition, and COS had no effect on germ-free (GF) flies. It is highlighted that COS could not work in Relish-RNAi flies, indicating relish is required for COS to perform beneficial effects. These results provide insights into the study of gut microbiota interacting with COS to modulate intestinal inflammation in specific hosts.

Chronic Stress Exposure Alters the Gut Barrier: Sex-Specific Effects on Microbiota and Jejunum Tight Junctions

Background

Major depressive disorder (MDD) is the leading cause of disability worldwide. Of individuals with MDD, 30% to 50% are unresponsive to common antidepressants, highlighting untapped causal biological mechanisms. Dysfunction in the microbiota-gut-brain axis has been implicated in MDD pathogenesis. Exposure to chronic stress disrupts blood-brain barrier integrity; still, little is known about intestinal barrier function in these conditions, particularly for the small intestine, where absorption of most foods and drugs takes place.

Methods

We investigated how chronic social or variable stress, two mouse models of depression, impact the jejunum intestinal barrier in males and females. Mice were subjected to stress paradigms followed by analysis of gene expression profiles of intestinal barrier-related targets, fecal microbial composition, and blood-based markers.

Results

Altered microbial populations and changes in gene expression of jejunum tight junctions were observed depending on the type and duration of stress, with sex-specific effects. We used machine learning to characterize in detail morphological tight junction properties, identifying a cluster of ruffled junctions in stressed animals. Junctional ruffling is associated with inflammation, so we evaluated whether lipopolysaccharide injection recapitulates stress-induced changes in the jejunum and observed profound sex differences. Finally, lipopolysaccharide-binding protein, a marker of gut barrier leakiness, was associated with stress vulnerability in mice, and translational value was confirmed on blood samples from women with MDD.

Conclusions

Our results provide evidence that chronic stress disrupts intestinal barrier homeostasis in conjunction with the manifestation of depressive-like behaviors in a sex-specific manner in mice and, possibly, in human depression.

Assesment of functional gastrointestinal diseases in obese children

Functional gastrointestinal disorders (FGID) are disorders of gut-brain interactions characterized by chronic recurrent gastrointestinal symptoms and are reported to be more common in obese individuals. The aim of the study was to evaluate FGID in obese children. A total of 405 children (6-18 years) were enrolled in this cross sectional study. The children were divided into two groups according to body mass index (BMI) as < 85th percentile and > 95th percentile. Diagnosis of FGID was based on ROME VI criteria. Demographic and clinical characteristics of the patients were evaluated. FGID and subgroups were determined. The mean age of the children was 12.73 ± 3.17 years; 52% (n = 211) of them was female and 47.9% (n = 194) was male. A total of 50.6% patients had BMI > 95th percentile, and 55.1% of those patients had FGID. The subgroups of FGID, functional abdominal pain disorders and functional defecation disorders were significantly more common in obese children than non-obese group (P < 0.01). Additionally, constipation-predominant irritable bowel syndrome (IBS), diarrhea-predominant IBS, functional diarrhea, and abdominal distention were significantly more common in obese children than non-obese children (P < 0.01).

CONCLUSION

 FGID in obese children was found to be increased significantly. Assessment of functional gastrointestinal symptoms in obese children will prevent unnecessary examinations.

WHAT IS KNOWN

• Functional gastrointestinal disorders are reported to be more common in obese individuals.

WHAT IS NEW

• Functional abdominal pain disorders and functional defecation disorders were significantly more common in obese children than non-obese group. • Constipation-predominant irritable bowel syndrome (IBS), diarrhea-predominant IBS, functional diarrhea, and abdominal distention were significantly more common in obese children than non-obese children.

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.

The Effect of Sex-Specific Differences on IL-10-/- Mouse Colitis Phenotype and Microbiota

Sexual dimorphism is an important factor in understanding various diseases, including inflammatory bowel disease (IBD). While females typically exhibit stronger immune responses, the role of sex in IBD remains unclear. This study aimed to explore the sex-dependent differences and inflammatory susceptibility in the most extensively used IBD mouse model as they developed colitis. We monitored IL10-deficient mice (IL-10-/-) up to 17 weeks of age and characterized their colonic and fecal inflammatory phenotype, as well as their microbiota changes. Here, we originally identified IL-10-/- female mice as more prone to developing intestinal inflammation, with an increase in fecal miR-21, and dysbiosis with more detrimental characteristics compared to males. Our findings provide valuable insights into the sex-based differences in the pathophysiology of colitis and emphasize the importance of considering sex in experimental designs. Moreover, this study paves the way for future investigations aiming at addressing sex-related differences for the development of adequate disease models and therapeutic strategies, ideally enabling personalized medicine.

The metabolic syndrome and its components as prognostic factors in colorectal cancer: A meta-analysis and systematic review

BACKGROUND AND AIM

Metabolic syndrome (MetS) increases the risk of colorectal cancer (CRC), and the impact of MetS on CRC prognosis remains controversial after the diagnosis of CRC has been established. This study aimed to explore the impact of the individual components and synergies of MetS on the prognosis of patients with CRC.

METHODS

We searched articles published before August 3, 2022, in four databases, including PubMed, Embase, Cochrane Library, and ScienceDirect. The random-effects model inverse variance method was used to estimate the summarized effect size.

RESULTS

Patients with CRC with MetS were 1.342 times more likely to experience all-cause mortality than those without MetS, and the 95% confidence interval (CI) of hazard ratio (HR) was 1.107-1.627 (P = 0.003). CRC-specific mortality in patients with CRC with MetS was 2.122 times higher than in those without MetS, and the 95% CI of HR was 1.080-4.173 (P = 0.029). CRC-specific mortality exhibited an increasing trend of risk with increased metabolic risk factors. The HR of CRC-specific mortality for one, two, and three metabolic risk factors was 1.206 (95% CI, 1.034-1.407; P = 0.017), 1.881 (95% CI, 1.253-2.824; P = 0.002), and 2.327 (95% CI, 1.262-4.291; P = 0.007), respectively.

CONCLUSIONS

Metabolic syndrome increased all-cause and CRC-specific mortality in patients with CRC. As a single component of MetS, diabetes mellitus increased overall mortality in patients with CRC, while obesity increased CRC-specific mortality in patients with CRC, with a significant difference from non-MetS. Moreover, the risk of CRC-specific mortality increased with increasing number of metabolic risk factors.

The Stressed Gut: Region-specific Immune and Neuroplasticity Changes in Response to Chronic Psychosocial Stress

Background/Aims

Chronic psychological stress affects gastrointestinal physiology which may underpin alterations in the immune response and epithelial transport, both functions are partly regulated by enteric nervous system. However, its effects on enteric neuroplasticity are still unclear. This study aims to investigate the effects of chronic unpredictable psychological stress on intestinal motility and prominent markers of enteric function.

Methods

Adult male C57BL/6J mice were exposed to 19 day of unpredictable stress protocol schedule of social defeat and overcrowding. We investigated the effects on plasma corticosterone, food intake, and body weight. In vivo gastrointestinal motility was assessed by fecal pellet output and by whole-gastrointestinal transit (using the carmine red method). Tissue monoamine level, neural and glial markers, neurotrophic factors, monoamine signaling, and Toll-like receptor expression in the proximal and distal colon, and terminal ileum were also assessed.

Results

Following chronic unpredictable psychological stress, stressed mice showed increased food intake and body weight gain (P < 0.001), and reduced corticosterone levels (P < 0.05) compared to control mice. Stressed mice had reduced stool output without differences in water content, and showed a delayed gastrointestinal transit compared to control mice (P < 0.05). Stressed mice exhibited decreased mRNA expression of tyrosine hydroxylase (Th), brain-derived neurotrophic factor (Bdnf) and glial cell-derived neurotrophic factor (Gdnf), as well as Toll-like receptor 2 (Tlr2) compared to control (P < 0.05), only proximal colon. These molecular changes in proximal colon were associated with higher levels of monoamines in tissue.

Conclusion

Unpredictable psychological chronic stress induces region-specific impairment in monoamine levels and neuroplasticity markers that may relate to delayed intestinal transit.

Prenatal stress induces changes in PAR2- and M3-dependent regulation of colon primitive cells

Prenatal stress is associated with a high risk of developing adult intestinal pathologies, such as irritable bowel syndrome, chronic inflammation, and cancer. Although epithelial stem cells and progenitors have been implicated in intestinal pathophysiology, how prenatal stress could impact their functions is still unknown. We have investigated the proliferative and differentiation capacities of primitive cells using epithelial crypts isolated from colons of adult male and female mice whose mothers have been stressed during late gestation. Our results show that stem cell/progenitor proliferation and differentiation in vitro are negatively impacted by prenatal stress in male progeny. This is promoted by a reinforcement of the negative proliferative/differentiation control by the protease-activated receptor 2 (PAR2) and the muscarinic receptor 3 (M3), two G protein-coupled receptors present in the crypt. Conversely, prenatal stress does not change in vitro proliferation of colon primitive cells in female progeny. Importantly, this maintenance is associated with a functional switch in the M3 negative control of colonoid growth, becoming proliferative after prenatal stress. In addition, the proliferative role of PAR2 specific to females is maintained under prenatal stress, even though PAR2-targeted stress signals Dusp6 and activated GSK3β are increased, reaching the levels of males. An epithelial serine protease could play a critical role in the activation of the survival kinase GSK3β in colonoids from prenatally stressed female progeny. Altogether, our results show that following prenatal stress, colon primitive cells cope with stress through sexually dimorphic mechanisms that could pave the way to dysregulated crypt regeneration and intestinal pathologies.NEW & NOTEWORTHY Primitive cells isolated from mouse colon following prenatal stress and exposed to additional stress conditions such as in vitro culture, present sexually dimorphic mechanisms based on PAR2- and M3-dependent regulation of proliferation and differentiation. Whereas prenatal stress reinforces the physiological negative control exerted by PAR2 and M3 in crypts from males, in females, it induces a switch in M3- and PAR2-dependent regulation leading to a resistant and proliferative phenotype of progenitor.

Mapping trends and hotspot regarding gastrointestinal microbiome and neuroscience: A bibliometric analysis of global research (2002-2022)

BACKGROUND

Scholars have long understood that gastrointestinal microorganisms are intimately related to human disorders. The literature on research involving the gut microbiome and neuroscience is emerging. This study exposed the connections between gut microbiota and neuroscience methodically and intuitively using bibliometrics and visualization. This study's objectives were to summarize the knowledge structure and identify emerging trends and potential hotspots in this field.

MATERIALS AND METHODS

On October 18, 2022, a literature search was conducted utilizing the Web of Science Core Collection (WoSCC) database for studies on gut microbiota and neuroscience studies from 2002 to 2022 (August 20, 2022). VOSviewer and CiteSpace V software was used to conduct the bibliometrics and visualization analysis.

RESULTS

From 2002 to 2022 (August 20, 2022), 2,275 publications in the WoSCC database satisfied the criteria. The annual volume of publications has rapidly emerged in recent years (2016-2022). The most productive nation (n = 732, 32.18%) and the hub of inter-country cooperation (links: 38) were the United States. University College Cork had the most research papers published in this area, followed by McMaster University and Harvard Medical School. Cryan JF, Dinan TG, and Clarke G were key researchers with considerable academic influence. The journals with the most publications are "Neurogastroenterology and Motility" and "Brain Behavior and Immunity." The most cited article and co-cited reference was Cryan JF's 2012 article on the impact of gut microbiota on the brain and behavior. The current research hotspot includes gastrointestinal microbiome, inflammation, gut-brain axis, Parkinson's disease (PD), and Alzheimer's disease (AD). The research focus would be on the "gastrointestinal microbiome, inflammation: a link between obesity, insulin resistance, and cognition" and "the role of two important theories of the gut-brain axis and microbial-gut-brain axis in diseases." Burst detection analysis showed that schizophrenia, pathology, and psychiatric disorder may continue to be the research frontiers.

CONCLUSION

Research on "gastrointestinal microbiome, inflammation: a link between obesity, insulin resistance, and cognition" and "the role of two important theories of the gut-brain axis and microbial-gut-brain axis in diseases" will continue to be the hotspot. Schizophrenia and psychiatric disorder will be the key research diseases in the field of gut microbiota and neuroscience, and pathology is the key research content, which is worthy of scholars' attention.

Shedding light on biological sex differences and microbiota-gut-brain axis: a comprehensive review of its roles in neuropsychiatric disorders

Women and men are suggested to have differences in vulnerability to neuropsychiatric disorders, including major depressive disorder (MDD), generalized anxiety disorder (GAD), schizophrenia, eating disorders, including anorexia nervosa, and bulimia nervosa, neurodevelopmental disorders, such as autism spectrum disorder (ASD), and neurodegenerative disorders including Alzheimer’s disease, Parkinson’s disease. Genetic factors and sex hormones are apparently the main mediators of these differences. Recent evidence uncovers that reciprocal interactions between sex-related features (e.g., sex hormones and sex differences in the brain) and gut microbiota could play a role in the development of neuropsychiatric disorders via influencing the gut–brain axis. It is increasingly evident that sex–microbiota–brain interactions take part in the occurrence of neurologic and psychiatric disorders. Accordingly, integrating the existing evidence might help to enlighten the fundamental roles of these interactions in the pathogenesis of neuropsychiatric disorders. In addition, an increased understanding of the biological sex differences on the microbiota–brain may lead to advances in the treatment of neuropsychiatric disorders and increase the potential for precision medicine. This review discusses the effects of sex differences on the brain and gut microbiota and the putative underlying mechanisms of action. Additionally, we discuss the consequences of interactions between sex differences and gut microbiota on the emergence of particular neuropsychiatric disorders.

The human microbiome is a unique set of organisms affecting health via the gut–brain axis.

Neuropsychiatric disorders, eating disorders, neurodevelopmental disorders, and neurodegenerative disorders are regulated by the microbiota–gut–brain axis in a sex-specific manner.

Understanding the role of the microbiota–gut–brain axis and its sex differences in various diseases can lead to better therapeutic methods.

Effect of β-Estradiol on Mono- and Mixed-Species Biofilms of Human Commensal Bacteria Lactobacillus paracasei AK508 and Micrococcus luteus C01 on Different Model Surfaces

The impact of steroid hormones, and particularly estradiol, on human microbiota could be recognized as a substantial part of human-microbiota interactions. However, an area that remains poorly investigated is that of the skin and vaginal microbial communities and biofilms, which contain non-pathogenic bacteria of phyla Firmicutes and Actinobacteria, especially probiotic bacteria of the genus Lactobacillus and the widespread, safe skin genus, Micrococcus. Experiments with Lactobacillus paracasei AK508 and Micrococcus luteus C01 biofilms on PTFE cubes showed dose-dependent effects of estradiol at concentrations of 0.22 nM and 22 nM. The hormone mostly inhibits L. paracasei growth and stimulates M. luteus. The presented studies of colony-forming unit (CFU) amountsand cell aggregation in biofilms on glass fiber filters showed the same general tendencies. Estradiol generally increased the aggregation of cells in monospecies communities and potentially changed the synthesis of antibacterial metabolites in L. paracasei. The balance between two bacteria in mixed-species biofilms depended on the initial adhesion stage, and when this stage was reduced, micrococci were more resistant to the antagonistic action of L. paracasei. Moreover, in mixed-species biofilms, the effect of estradiol on lactobacilli altered from inhibition to stimulation, potentially due to the presence of M. luteus. At the same time, ethanol as a solvent for estradiol at the concentration 0.6% acted mostly as an antagonist of the hormone and had an opposite effect on bacteria; nevertheless, the overlapping of ethanol and estradiol effects was shown to be minimal. The data obtained prove the complexity of microbial interactions and the regulatory effect of estradiol on commensal bacteria biofilms.

Effects of Cognitive Training and Social Support on Cancer-Related Fatigue and Quality of Life in Colorectal Cancer Survivors: A Systematic Review and Meta-Analysis

Background:

Few studies have evaluated the effects of cognitive training and social support on cancer-related fatigue and quality of life. We performed a meta-analysis of randomized controlled trials to examine the efficacy of cognitive training and social support in colorectal cancer patients and survivors.

Methods:

The PubMed, Ovid, EMBASE, Cochrane Central Register of Controlled Trials, and China National Knowledge Infrastructure databases were searched from database establishment until August 2021 to identify suitable studies according to relevant key words, taking cancer-related fatigue and quality of life as the outcomes. The Jadad scale was used to evaluate the methodological quality of the studies. Stata 15.1 software was used for statistical analyses, and sensitivity analyses were performed.

Results:

Eleven studies (6 published in English and 5 published in Chinese) involving 980 patients and survivors were included in the meta-analysis. All studies had Jadad scores ≥3. Statistically significant effects of cognitive training and social support were detected for cancer-related fatigue within 14 weeks (SMD = −1.13, P < .001) and after 14 weeks (SMD = −0.56, P < .001), overall quality of life within 14 weeks (SMD = 0.73, P < .001) and after 14 weeks (SMD = 0.54, P = .003). However, no statistically significant effects of the combination intervention were detected on long-term QOL (SMD = 0.50, P = .435).

Conclusions:

Distinct cognitive interventions and a combination of cognitive and social support interventions can help to alleviate long-term and short-term CRF and short-term QOL. Further studies are needed to examine the mechanisms of cognitive training and social support for cancer-related fatigue and overall quality of life in patients and survivors with colorectal cancer.

Prevalence and Influencing Factors of Irritable Bowel Syndrome in Medical Staff: A Meta-Analysis

BACKGROUND

Irritable bowel syndrome (IBS) is a common functional digestive tract disease worldwide, with a high prevalence among medical staff. The purpose of this study is to systematically evaluate the prevalence and influencing factors of IBS in medical staff.

METHODS

We searched English online databases, including PubMed, The Cochrane Library, Web of Science, Embase, and EBSCOhost. The retrieval time was from database establishment to May of 2021. We screened the literature according to inclusion and exclusion criteria, extracted the relevant information, and evaluated the research quality. A meta-analysis was performed using the Stata 16.0 and Review Manager 5.4.1 software.

RESULTS

A total of 11 English studies from seven countries were included in this study, including 3,360 medical staff. The results of the meta-analysis showed an overall prevalence of IBS among medical staff of 16% [95%CI (0.15 ~ 0.17)] and that shift work (OR 2.27)), poor sleep quality (OR 4.27), and female gender (OR 2.29) are the major influencing factors of medical staff suffering from IBS.

CONCLUSIONS

The prevalence of irritable bowel syndrome among medical staff is relatively high, and hospitals can start by looking for targeted interventions from the highly related factors of IBS among medical staff such as shift work patterns, females, and poor sleep quality.

The Role of Vasoactive Intestinal Peptide and Mast Cells in the Regulatory Effect of Lactobacillus casei ATCC 393 on Intestinal Mucosal Immune Barrier

Vasoactive intestinal peptide (VIP) plays an important role in the neuro-endocrine-immune system. Mast cells (MCs) are important immune effector cells. This study was conducted to investigate the protective effect of L. casei ATCC 393 on Enterotoxigenic Escherichia coli (ETEC) K88-induced intestinal mucosal immune barrier injury and its association with VIP/MC signaling by in vitro experiments in cultures of porcine mucosal mast cells (PMMCs) and in vivo experiments using VIP receptor antagonist (aVIP) drug. The results showed that compared with the ETEC K88 and lipopolysaccharides (LPS)-induced model groups, VIP pretreatment significantly inhibited the activation of MCs and the release of β-hexosaminidase (β-hex), histamine and tryptase. Pretreatment with aVIP abolished the protective effect of L. casei ATCC 393 on ETEC K88-induced intestinal mucosal immune barrier dysfunction in C57BL/6 mice. Also, with the blocking of VIP signal transduction, the ETEC K88 infection increased serum inflammatory cytokines, and the numbers of degranulated MCs in ileum, which were decreased by administration of L. casei ATCC 393. In addition, VIP mediated the regulatory effect of L. casei ATCC 393 on intestinal microbiota in mice. These findings suggested that VIP may mediate the protective effect of L.casei ATCC 393 on intestinal mucosal immune barrier dysfunction via MCs.

Physiological mechanisms of unexplained (functional) gastrointestinal disorders

Functional gastrointestinal disorders (FGIDs) encompass a range of complex conditions with similar clinical characteristics and no overt pathology. Recent recognition of sub-clinical pathologies in FGIDs, in conjunction with physiological and biochemical abnormalities including increased intestinal permeability, microbial profile alterations, differences in metabolites and extra-intestinal manifestations of disease, call into question the designation of these conditions as 'functional'. This is despite significant heterogeneity in both symptom profile and specifics of reported physiological abnormalities hampering efforts to determine defined mechanisms that drive onset and chronicity of symptoms. Instead, the literature demonstrates these conditions are disorders of homeostatic imbalance, with disruptions in both host and microbial function and metabolism. This imbalance is also associated with extraintestinal abnormalities including psychological comorbidities and fatigue that may be a consequence of gastrointestinal disruption. Given the exploitation of such abnormalities will be crucial for improved therapeutic selection, an enhanced understanding of the relationship between alterations in function of the gastrointestinal tract and the response of the immune system is of interest in identifying mechanisms that drive FGID onset and chronicity. Considerations for future research should include the role of sex hormones in regulating physiological functions and treatment responses in patients, as well as the importance of high-level phenotyping of clinical, immune, microbial and physiological parameters in study cohorts. There is opportunity to examine the functional contribution of the microbiota and associated metabolites as a source of mechanistic insight and targets for therapeutic modulation.

Dietary Fibre Intervention for Gut Microbiota, Sleep, and Mental Health in Adults with Irritable Bowel Syndrome: A Scoping Review

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder affecting 4-5% of the global population. This disorder is associated with gut microbiota, diet, sleep, and mental health. This scoping review therefore aims to map existing research that has administrated fibre-related dietary intervention to IBS individuals and reported outcomes on at least two of the three following themes: gut microbiota, sleep, and mental health. Five digital databases were searched to identify and select papers as per the inclusion and exclusion criteria. Five articles were included in the assessment, where none reported on all three themes or the combination of gut microbiota and sleep. Two studies identified alterations in gut microbiota and mental health with fibre supplementation. The other three studies reported on mental health and sleep outcomes using subjective questionnaires. IBS-related research lacks system biology-type studies targeting gut microbiota, sleep, and mental health in patients undergoing diet intervention. Further IBS research is required to explore how human gut microbiota functions (such as short-chain fatty acids) in sleep and mental health, following the implementation of dietary pattern alteration or component supplementation. Additionally, the application of objective sleep assessments is required in order to detect sleep change with more accuracy and less bias.

The Microbiota-Gut-Brain Axis and Alzheimer Disease. From Dysbiosis to Neurodegeneration: Focus on the Central Nervous System Glial Cells

The microbiota-gut system can be thought of as a single unit that interacts with the brain via the "two-way" microbiota-gut-brain axis. Through this axis, a constant interplay mediated by the several products originating from the microbiota guarantees the physiological development and shaping of the gut and the brain. In the present review will be described the modalities through which the microbiota and gut control each other, and the main microbiota products conditioning both local and brain homeostasis. Much evidence has accumulated over the past decade in favor of a significant association between dysbiosis, neuroinflammation and neurodegeneration. Presently, the pathogenetic mechanisms triggered by molecules produced by the altered microbiota, also responsible for the onset and evolution of Alzheimer disease, will be described. Our attention will be focused on the role of astrocytes and microglia. Numerous studies have progressively demonstrated how these glial cells are important to ensure an adequate environment for neuronal activity in healthy conditions. Furthermore, it is becoming evident how both cell types can mediate the onset of neuroinflammation and lead to neurodegeneration when subjected to pathological stimuli. Based on this information, the role of the major microbiota products in shifting the activation profiles of astrocytes and microglia from a healthy to a diseased state will be discussed, focusing on Alzheimer disease pathogenesis.

Obesity Exacerbates Irritable Bowel Syndrome-Related Sleep and Psychiatric Disorders in Women With Polycystic Ovary Syndrome

BACKGROUND/OBJECTIVES

Polycystic ovary syndrome (PCOS) and irritable bowel syndrome (IBS) share similar clinical and psychosocial features. We aimed to investigate the clinical characteristics of IBS in women with PCOS, and its relationship with obesity, metabolic and hormonal profiles, as well as sleep and psychiatric disorders.

SUBJECTS/METHODS

This is a cross-sectional case-control study of 431 untreated women with PCOS and 259 healthy volunteers. All participants were assessed with a comprehensive clinical evaluation and two questionnaires: the Athens Insomnia Scale (AIS) and the Brief Symptom Rating Scale (BSRS-5). IBS was diagnosed using the Rome III criteria. Obesity was defined as a BMI ≥30 kg/m². Anthropometric measurements, metabolic, hormonal profiles, and psychosocial morbidities were compared.

RESULTS

Women with PCOS were more likely to have IBS (10.7% vs 5.8%, p=0.029) and obesity (29% vs 4%, p<0.001) than healthy volunteers. Mixed-type IBS (IBS-M) was the most common subtype (74%) among patients with PCOS and IBS. There was a higher prevalence of psychiatric morbidities (total BSRS-5 score ≥10) in women with PCOS than in healthy women (11.4% vs 3.5%, p<0.001). Women with PCOS and IBS were more likely to have sleep difficulties (67.4% vs 30.9%, p<0.001) and psychiatric morbidities (21.7% vs 10.1%, p=0.019) than those without IBS. Anthropometrics, metabolic and hormonal profiles were similar between PCOS women with and without IBS. Among women with PCOS, those with both IBS and obesity had the highest risk of developing sleep difficulties (odds ratio: 5.91; 95% confidence interval: 1.77-19.77) and psychiatric distress (odds ratio: 4.39; 95% confidence interval: 1.26-15.29) than those without.

CONCLUSION

Women with PCOS have increased IBS, obesity, sleep and psychiatric disturbances. The presence of IBS in PCOS women is associated with sleep and psychiatric disorders. The coexistence of obesity and IBS exacerbates sleep difficulties and psychiatric distress. Screening and management of IBS and obesity might be warranted to improve sleep and psychiatric disturbances in women with PCOS.

Histone H3K9 methylation regulates chronic stress and IL-6-induced colon epithelial permeability and visceral pain

BACKGROUND

Chronic stress is associated with activation of the HPA axis, elevation in pro-inflammatory cytokines, decrease in intestinal epithelial cell tight junction (TJ) proteins, and enhanced visceral pain. It is unknown whether epigenetic regulatory pathways play a role in chronic stress-induced intestinal barrier dysfunction and visceral hyperalgesia.

METHODS

Young adult male rats were subjected to water avoidance stress ± H3K9 methylation inhibitors or siRNAs. Visceral pain response was assessed. Differentiated Caco-2/BBE cells and human colonoids were treated with cortisol or IL-6 ± antagonists. Expression of TJ, IL-6, and H3K9 methylation status at gene promoters was measured. Transepithelial electrical resistance and FITC-dextran permeability were evaluated.

KEY RESULTS

Chronic stress induced IL-6 up-regulation prior to a decrease in TJ proteins in the rat colon. The IL-6 level inversely correlated with occludin expression. Treatment with IL-6 decreased occludin and induced visceral hyperalgesia. Chronic stress and IL-6 increased H3K9 methylation and decreased transcriptional GR binding to the occludin gene promoter, leading to down-regulation of protein expression and increase in paracellular permeability. Intrarectal administration of a H3K9 methylation antagonist prevented chronic stress-induced visceral hyperalgesia in the rat. In a human colonoid model, cortisol decreased occludin expression, which was prevented by the GR antagonist RU486, and IL-6 increased H3K9 methylation and decreased TJ protein levels, which were prevented by inhibitors of H3K9 methylation.

CONCLUSIONS & INFERENCES

Our findings support a novel role for methylation of the repressive histone H3K9 to regulate chronic stress, pro-inflammatory cytokine-mediated reduction in colon TJ protein levels, and increase in paracellular permeability and visceral hyperalgesia.

Efficacy of probiotics on stress in healthy volunteers: A systematic review and meta-analysis based on randomized controlled trials

BACKGROUND

Probiotics seems to play a beneficial role in stressed populations; thus, a systematic review and meta-analysis to assess the effects of probiotics on stress in healthy subjects were conducted.

METHODS

Randomized controlled trials on the effects of probiotics on stress in healthy subjects were retrieved from five databases. The effects of probiotics on subjective stress level, stress-related subthreshold anxiety/depression level, cortisol level, and adverse reactions were analyzed. Separate subgroup analyses were conducted on single-strain probiotics versus multi-strain probiotics, and short-term administration versus long-term administration.

RESULTS

Seven studies were included, involving a total of 1,146 subjects. All the studies were rated as low or moderate risk of bias. Our research found that probiotic administration can generally reduce the subjective stress level of healthy volunteers and may improve their stress-related subthreshold anxiety/depression level, but no significant effect was observed in the subgroup analysis. The effect of probiotics on cortisol level was not significant. Adverse reactions were reported in only one of seven studies, but left undescribed.

CONCLUSION

Current evidence suggests that probiotics can reduce subjective stress level in healthy volunteers and may alleviate stress-related subthreshold anxiety/depression level, without significant effect on cortisol level, and there is not enough support to draw conclusions about adverse effects; thus, more reliable evidence from clinical trials is needed.

Gut permeability is affected by sex and increased in children with irritable bowel syndrome but not in functional abdominal pain

BACKGROUND

Gut permeability is increased in some children and adults with irritable bowel syndrome (IBS). We investigated whether this also is true for children with functional abdominal pain (FAP). We also determined whether sex affected permeability results.

METHODS

Sucrose, lactulose, mannitol, and sucralose were ingested after an overnight fast in well-phenotyped children with IBS (n = 95), FAP (n = 25), and healthy controls (HC) (n = 60). Urine was collected for 24 hours. Percent sucrose recovery was calculated based on the 0- to 3-hour collection; lactulose/mannitol ratio both on the 0- to 3-hour and 0- to 24-hour collections; and percent sucralose recovery on the 0- to 24-hours collection.

KEY RESULTS

Age was similar among the groups (P = .26). The lactulose/mannitol ratio was increased in IBS compared with HC at 0-3 and 0-24 hours (P = .023, P = .05, respectively). Percent sucralose recovery was greater in FAP than in HC (P = .045). No differences were noted among the groups in percent sucrose recovery. Taking sex into account, percent sucrose recovery was greater in girls with IBS vs HC girls (P = .008). The lactulose/mannitol ratio was greater in boys with IBS compared with HC boys at both time points (both P = .02). Percent sucralose recovery was greater in boys with IBS than in FAP or HC (both P < .001).

CONCLUSIONS AND INFERENCES

Sex is a critically important factor when measuring gut permeability. Boys with IBS have increased lactulose/mannitol ratios and percent sucralose recovery. Girls with IBS have increased percent recovery of sucrose. Children with FAP do not demonstrate abnormal gut 0permeability even taking sex into account.

The Relationship Between the Serotonin Metabolism, Gut-Microbiota and the Gut-Brain Axis

BACKGROUND

Serotonin (5-HT) has a pleiotropic function in gastrointestinal, neurological/psychiatric and liver diseases. The aim of this review was to elucidate whether the gut-microbiota played a critical role in regulating peripheral serotonin levels.

METHODS

We searched for relevant studies published in English using the PubMed database from 1993 to the present.

RESULTS

Several studies suggested that alterations in the gut-microbiota may contribute to a modulation of serotonin signalling. The first indication regarded the changes in the composition of the commensal bacteria and the intestinal transit time caused by antibiotic treatment. The second indication regarded the changes in serotonin levels correlated to specific bacteria. The third indication regarded the fact that decreased serotonin transporter expression was associated with a shift in gut-microbiota from homeostasis to inflammatory type microbiota. Serotonin plays a key role in the regulation of visceral pain, secretion, and initiation of the peristaltic reflex; however, its altered levels are also detected in many different psychiatric disorders. Symptoms of some gastrointestinal functional disorders may be due to deregulation in central nervous system activity, dysregulation at the peripheral level (intestine), or a combination of both (brain-gut axis) by means of neuro-endocrine-immune stimuli. Moreover, several studies have demonstrated the profibrogenic role of 5-HT in the liver, showing that it works synergistically with platelet-derived growth factor in stimulating hepatic stellate cell proliferation.

CONCLUSION

Although the specific interaction mechanisms are still unclear, some studies have suggested that there is a correlation between the gut-microbiota, some gastrointestinal and liver diseases and the serotonin metabolism.

Increased Gut Permeability in First-degree Relatives of Children with Irritable Bowel Syndrome or Functional Abdominal Pain

BACKGROUND & AIMS

Increased gut permeability might contribute to the pathogenesis of irritable bowel syndrome or functional abdominal pain (IBS or FAP). We investigated whether siblings and parents of children with IBS or FAP have increased gut permeability.

METHODS

We performed permeability tests (using sucrose, lactulose, mannitol, and sucralose) on 29 siblings and 43 parents of children with IBS or FAP, and 43 children (controls) and 42 parents of controls, from primary and secondary care. Permeability studies were repeated in 7 siblings and 37 parents of children with IBS or FAP and 23 controls and 36 parents of controls following ingestion of 400 mg of ibuprofen. Percent recovery of sucrose was calculated based on analyses of urine collected overnight; the lactulose/mannitol ratio and percent recovery of sucralose were based on analyses of urine samples collected over a 24-hour period.

RESULTS

When we controlled for age, sex, and family membership, siblings of children with IBS or FAP had increased small bowel permeability (urinary lactulose/mannitol ratio) vs controls (P = .004). There was no difference in gastroduodenal (percent sucrose recovery) or colonic (percent sucralose recovery) permeability between groups. Similarly, parents of children with IBS or FAP also had increased small bowel permeability, compared with parents of controls (P = .015), with no differences in gastric or colonic permeability. After administration of ibuprofen, gastroduodenal and small bowel permeability tended to be greater in IBS or FAP siblings (P = .08) and gastroduodenal permeability tended to be greater in IBS or FAP parents (P = .086).

CONCLUSIONS

Siblings and parents of children with IBS or FAP have increased baseline small intestinal permeability compared with control children and their parents. These results indicate that there are familial influences on gastrointestinal permeability in patients with IBS or FAP.

Psychotherapeutic Interventions in Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a frequent functional gastrointestinal disorder. The patients complain about various symptoms like change in bowel habits, constipation or diarrhea, abdominal pain, and meteorism leading to a great reduction in quality of life. The pathophysiology is complex and best explained using the biopsychosocial model encompassing biological, psychological as well as (psycho)social factors. In line with the multitude of underlying factors, the treatment is comprised of a multitude of components. Often, patients start with lifestyle changes and dietary advice followed by medical treatment. However, also psychotherapy is an important treatment option for patients with IBS and should not be restricted to those with psychiatric comorbidities. Several evidence-based psychotherapeutic treatment options exist such as psychoeducation, self-help, cognitive behavioral therapy, psychodynamic psychotherapy, hypnotherapy, mindfulness-based therapy, and relaxation therapy which will be discussed in the present review.

New insights into irritable bowel syndrome: from pathophysiology to treatment

Irritable bowel syndrome (IBS) is the most common reason to visit a gastroenterologist. IBS was believed to be a functional disease, but many possible pathophysiologic mechanisms can now explain the symptoms. IBS patients are classified into subtypes according to their predominant bowel habit, based on the Rome IV criteria. These include diarrhea-predominant and constipation-predominant IBS, as well as the mixed type, a combination of the two. Usually, IBS treatment is based on the predominant symptoms, with many options for each subtype. A new promising treatment option, fecal microbiota transplantation, seems to have beneficial effects on IBS. However, treating the pathophysiological causative agent responsible for the symptoms is an emerging approach. Therefore, before the appropriate therapeutic option is chosen for treating IBS, a clinical evaluation of its pathophysiology should be performed.

Are there sex differences in visceral sensitivity in young healthy men and women?

BACKGROUND

Visceral hypersensitivity plays a key role in the pathophysiology of chronic visceral pain like irritable bowel syndrome (IBS), which is significantly more prevalent in women. Possible sex differences in visceral sensitivity remain poorly studied. We assessed sex differences in visceral sensitivity and their association with subclinical symptoms, trait anxiety, and chronic stress in a large sample of healthy men and women.

METHODS

In 280 young healthy volunteers (50% female), visceral sensory and pain thresholds were determined using rectal balloon distensions. Gastrointestinal (GI) symptoms, chronic stress, and trait anxiety as IBS-related risk factors were assessed with questionnaires. Men and women were compared regarding visceral sensitivity and multiple regression analyses were conducted to evaluate the predictive value of sex and risk factors for visceral sensitivity. Subgroups with high, intermediate, and low sensitivity were compared regarding psychological and biological characteristics.

KEY RESULTS

Men and women did not differ in sensory or pain thresholds or in IBS-related risk factors. In multiple regression analyses, no predictor of visceral sensitivity could be identified. While sensitivity subgroups differed in sensory and pain thresholds, the proportions of men and women were comparable, and groups did not differ in IBS-related risk factors.

CONCLUSIONS AND INFERENCES

Despite the large sample size, we found no evidence supporting sex differences in visceral sensitivity. At least in healthy young volunteers, our findings suggest that sex, GI symptoms, anxiety, or chronic stress do not contribute to altered visceral sensitivity.

Pharmacological restoration of gut barrier function in stressed neonates partially reverses long-term alterations associated with maternal separation

RATIONALE

Intestinal permeability plays an important role in gut-brain axis communication. Recent studies indicate that intestinal permeability increases in neonate pups during maternal separation (MS).

OBJECTIVES

The present study aims to determine whether pharmacological inhibition of myosin light chain kinase (MLCK), which regulates tight junction contraction and controls intestinal permeability, in stressed neonates, protects against the long-term effects of MS.

METHODS

Male Wistar rats were exposed to MS (3 h per day from post-natal day (PND)2 to PND14) or left undisturbed and received daily intraperitoneal injection of a MLCK inhibitor (ML-7, 5 mg/kg) or vehicle during the same period. At adulthood, emotional behaviors, corticosterone response to stress, and gut microbiota composition were analyzed.

RESULTS

ML-7 restored gut barrier function in MS rats specifically during the neonatal period. Remarkably, ML-7 prevented MS-induced sexual reward-seeking impairment and reversed the alteration of corticosterone response to stress at adulthood. The effects of ML-7 were accompanied by the normalization of the abundance of members of Lachnospiraceae, Clostridiales, Desulfovibrio, Bacteroidales, Enterorhabdus, and Bifidobacterium in the feces of MS rats at adulthood.

CONCLUSIONS

Altogether, our work suggests that improvement of intestinal barrier defects during development may alleviate some of the long-term effects of early-life stress and provides new insight on brain-gut axis communication in a context of stress.

Association Between Obesity/Overweight and Functional Gastrointestinal Disorders in Children

OBJECTIVE

Although emerging data indicate that obese/overweight children are more likely to develop functional gastrointestinal disorders (FGIDs) than normal-weight peers, contrasting results have been reported. The present observational, case-control study aimed at estimating the prevalence of FGIDs in obese/overweight children compared to normal-weight peers.

METHODS

Consecutive obese and overweight children aged 4 to 18 years attending the obesity outpatient clinic were enrolled as study cases. Normal-weight children were enrolled as comparison group. All the enrolled patients received a thorough health examination from both a pediatric endocrinologist and gastroenterologist. Moreover, they were asked to fill out the Rome III questionnaire for the diagnosis of FGIDs. Data were analyzed to compare the prevalence of FGIDs between cases and controls.

RESULTS

Throughout the study period we enrolled 103 cases and 115 controls. No significant age and sex differences were found between the 2 groups. FGIDs were significantly more prevalent in obese/overweight compared to normal-weight children (47.57% vs 17.39%; P < 0.0001). Increased prevalence was observed for functional constipation (18.44% vs 7.82%; P = 0.025), functional dyspepsia (23.33% vs 6.95%; P = 0.001), and irritable bowel syndrome (10.67% vs 2.60%; P = 0.024), whereas no difference was observed for functional abdominal pain (1.94% vs 2.60%; P = 1.00).

CONCLUSIONS

Our data suggest that there is a link between excess body fat and FGIDs in children. This finding may offer a model of patients in which the effects of food and nutritional substances, the gut microbial environment, and psychosocial factors are fitting well with the emerging biopsychosocial conceptual model for FGIDs.

The microgenderome revealed: sex differences in bidirectional interactions between the microbiota, hormones, immunity and disease susceptibility

Sex differences in immunity are well described in the literature and thought to be mainly driven by sex hormones and sex-linked immune response genes. The gastrointestinal tract (GIT) is one of the largest immune organs in the body and contains multiple immune cells in the GIT-associated lymphoid tissue, Peyer's patches and elsewhere, which together have profound effects on local and systemic inflammation. The GIT is colonised with microbial communities composed of bacteria, fungi and viruses, collectively known as the GIT microbiota. The GIT microbiota drives multiple interactions locally with immune cells that regulate the homeostatic environment and systemically in diverse tissues. It is becoming evident that the microbiota differs between the sexes, both in animal models and in humans, and these sex differences often lead to sex-dependent changes in local GIT inflammation, systemic immunity and susceptibility to a range of inflammatory diseases. The sexually dimorphic microbiome has been termed the 'microgenderome'. Herein, we review the evidence for the microgenderome and contemplate the role it plays in driving sex differences in immunity and disease susceptibility. We further consider the impact that biological sex might play in the response to treatments aimed at manipulating the GIT microbiota, such as prebiotics, live biotherapeutics, (probiotics, synbiotics and bacteriotherapies) and faecal microbial transplant. These alternative therapies hold potential in the treatment of both psychological (e.g., anxiety, depression) and physiological (e.g., irritable bowel disease) disorders differentially affecting males and females.

Enriched environment on the intestinal mucosal barrier and brain-gut axis in rats with colorectal cancer

An enriched environment (EE) is an animal housing technique in which animals are given increased amounts of space, physical activity, and social interaction. Currently, researchers studying EE focus mainly on its effects within the context of neurological diseases. However, little is known about how EE affects the intestinal mucosal barrier. This study assessed the effects of EE on the intestinal mucosal barrier in rats with colorectal cancer. A rat model of 1,2-dimethylhydrazine (DMH)-induced colorectal cancer was used. The rats were housed in eight conditions for eight weeks: EE, large cages containing eight rats with stimulating objects; enlarged space and socially enriched conditions (ES), large cages containing eight rats; enlarged space and cognition enriched conditions (EC), large cages containing one rat with stimulating objects; enlarged space enriched conditions (E), large cages containing one rat; cognition and socially enriched conditions (CS), four to five rats housed in standard cages containing stimulating objects; cognition enriched conditions (C), rats housed individually in small-size cages containing stimulating objects; socially enriched conditions (S), standard cages containing four rats; and normal conditions (blank group, B). We determined the weight of each rat, measured the intestinal mucosa and plasma levels of tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), interleukin 10 (IL-10), ghrelin, corticotropin-releasing factor (CRF), occludin, bacterial translocation (BT), and secretory immunoglobulin A (SIgA), and assessed the morphology of the intestinal mucosa. On the whole, the combination of cognitive stimulus and social support was better than the combination of three factors in maintenance of the intestinal mucosal immune barrier and brain–gut peptide. The combination of all three factors and combination of cognitive training and social support were more effective than any single factor. Future studies are needed to study the effects of an EE on body weight, brain–gut peptide, and the intestinal mucosa biological barrier.

Impact statement

An enriched environment (EE) is an animal housing technique where animals are given increased amounts of space, physical activity, and social interaction. Presently, researchers studying EEs focus mainly on their effects within the context of neurological diseases. However, little is known about how EEs affect the intestinal mucosal barrier. This study assessed the effects of an EE on the intestinal mucosal barrier in rats with colorectal cancer.

Traumatic Brain Injury in Mice Induces Acute Bacterial Dysbiosis Within the Fecal Microbiome

The secondary injury cascade that is activated following traumatic brain injury (TBI) induces responses from multiple physiological systems, including the immune system. These responses are not limited to the area of brain injury; they can also alter peripheral organs such as the intestinal tract. Gut microbiota play a role in the regulation of immune cell populations and microglia activation, and microbiome dysbiosis is implicated in immune dysregulation and behavioral abnormalities. However, changes to the gut microbiome induced after acute TBI remains largely unexplored. In this study, we have investigated the impact of TBI on bacterial dysbiosis. To test the hypothesis that TBI results in changes in microbiome composition, we performed controlled cortical impact (CCI) or sham injury in male 9-weeks old C57BL/6J mice. Fresh stool pellets were collected at baseline and at 24 h post-CCI. 16S rRNA based microbiome analysis was performed to identify differential abundance in bacteria at the genus and species level. In all baseline vs. 24 h post-CCI samples, we evaluated species-level differential abundances via clustered and annotated operational taxonomic units (OTU). At a high-level view, we observed significant changes in two genera after TBI, Marvinbryantia, and Clostridiales. At the species-level, we found significant decreases in three species (Lactobacillus gasseri, Ruminococcus flavefaciens, and Eubacterium ventriosum), and significant increases in two additional species (Eubacterium sulci, and Marvinbryantia formatexigens). These results pinpoint critical changes in the genus-level and species-level microbiome composition in injured mice compared to baseline; highlighting a previously unreported acute dysbiosis in the microbiome after TBI.

Gluten and Functional Abdominal Pain Disorders in Children

In children, functional gastrointestinal disorders (FGIDs) are common at all ages. Consumption of certain foods, particularly gluten, is frequently associated with the development and persistence of FGIDs and functional abdominal pain disorders (FAPDs) in adults and children. However, this association is not well defined. Even without a diagnosis of celiac disease (CD), some people avoid gluten or wheat in their diet since it has been shown to trigger mostly gastrointestinal symptoms in certain individuals, especially in children. The incidence of conditions such as non-celiac gluten sensitivity (NCGS) is increasing, particularly in children. On the other hand, CD is a chronic, autoimmune small intestinal enteropathy with symptoms that can sometimes be mimicked by FAPD. It is still unclear if pediatric patients with irritable bowel syndrome (IBS) are more likely to have CD. Abdominal, pain-associated FGID in children with CD does not seem to improve on a gluten-free diet. The threshold for gluten tolerance in patients with NCGS is unknown and varies among subjects. Thus, it is challenging to clearly distinguish between gluten exclusion and improvement of symptoms related solely to functional disorders.

Sex-Gender Differences in Irritable Bowel Syndrome

Because of the sex-gender differences that are shown in a diversity of physiological and psychological factors, it can be speculated that the clinical presentation of symptoms as well as treatment strategies in women and men with irritable bowel syndrome (IBS) may differ. Studies have revealed that IBS is more common in women than men. As for the IBS subtype, IBS with constipation is significantly more prevalent among women than men. Sex hormones and gender differences may play important roles in the pathophysiology of IBS. However, its pathophysiologic mechanisms still remain largely unknown, and therapeutic implications are limited. Moreover, women IBS patients have been reported to feel more fatigue, depression, anxiety, and lower quality of life than men IBS patients. Furthermore, there has been evidence of differences in the appropriate treatment efficacy to IBS in men and women, although relatively few men are enrolled in most relevant clinical trials. A more sex-gender-oriented approach in the medical care setting could improve understanding of heterogeneous patients suffering from IBS. An individualized and multicomponent approach including sex and gender issues might help improve the treatment of IBS.

[Psychosomatic research in 2018: Lost illusions, renewed hopes]

A critical analysis of the basic hypotheses of psychosomatic research and the sometimes hasty assertions drawn from the previous works makes it possible to better discern the data confirmed by the most recent works or the most rigorous meta-analyses and to highlight the emerging tracks. If the hypothesis of behavioral patterns specifically related to the risk of certain pathologies seems abandoned, the predictive value of depression in the cardiovascular field, more than in that of oncology, becomes clearer. Negative affect and impaired emotional awareness emerge as two complementary factors of somatic vulnerability. Several vulnerability factors seem all the more effective as they affect individuals of lower socio-economic status. Social exclusion feeling and its links with the inflammatory response appear to be a possible common denominator, both for depression and for many somatic conditions. A series of studies on the cerebral regulation of emotions and stress, as well as on bidirectional brain-bowel relations and on the mediating role of the gut microbiota, complements the available epidemiological data. The same is true for certain advances in behavioral neuro-economics, which inform the decision-making processes of patients facing preventive health choices. Lastly, it appears that a significant part of the excess mortality associated with the existence of severe mental disorders is not due to factors inherent to the patients themselves, but to disparities in the quality of the care provided to them.

Evidence for a Coupled Oscillator Model of Endocrine Ultradian Rhythms

Whereas long-period temporal structures in endocrine dynamics have been well studied, endocrine rhythms on the scale of hours are relatively unexplored. The study of these ultradian rhythms (URs) has remained nascent, in part, because a theoretical framework unifying ultradian patterns across systems has not been established. The present overview proposes a conceptual coupled oscillator network model of URs in which oscillating hormonal outputs, or nodes, are connected by edges representing the strength of node-node coupling. We propose that variable-strength coupling exists both within and across classic hormonal axes. Because coupled oscillators synchronize, such a model implies that changes across hormonal systems could be inferred by surveying accessible nodes in the network. This implication would at once simplify the study of URs and open new avenues of exploration into conditions affecting coupling. In support of this proposed framework, we review mammalian evidence for (1) URs of the gut-brain axis and the hypothalamo-pituitary-thyroid, -adrenal, and -gonadal axes, (2) UR coupling within and across these axes; and (3) the relation of these URs to body temperature. URs across these systems exhibit behavior broadly consistent with a coupled oscillator network, maintaining both consistent URs and coupling within and across axes. This model may aid the exploration of mammalian physiology at high temporal resolution and improve the understanding of endocrine system dynamics within individuals.

The potential role of thyrotropin-releasing hormone in colonic dysmotility induced by water avoidance stress in rats

OBJECTIVE

This study sought to investigate the effect and underlying mechanism of thyrotrophin releasing hormone (TRH) on colonic contractile disorders induced by chronic water avoidance stress (WAS).

METHODS

Male SD rats were exposed to daily 1-h WAS or sham WAS for 10 consecutive days. The presence of TRH in the serum and colonic mucosa were determined using enzyme immunoassay kits. Immunohistochemistry and western blotting were performed to detect the expression of TRH receptor 1 (TRH-R1). The contractions of proximal colonic smooth muscle were studied in an organ bath system. The whole-cell patch-clamp technique was used to record the currents of both L-type calcium currents (I_Ca,L) and large conductance Ca²⁺-activated K⁺ (BK_Ca) channels in colonic smooth muscle cells (SMCs) isolated from adult rats.

RESULTS

Enzyme immunoassay revealed that TRH was present in both serum and colonic mucosa and that this expression increased in the WAS group. Immunohistochemistry revealed that the TRH-R1 level increased in colons devoid of mucosa and submucosa from the stressed rats as compared with the control group. TRH increased the spontaneous contractions of the longitudinal muscle and circular muscle strips in a dose-dependent manner in vitro. The effect was also confirmed in an vivo experiment, where an intraperitoneal injection of TRH in rats significantly increased fecal pellet output during a 24-h period as compared with the control group. Furthermore, intraperitoneal injection of a non-specific TRH receptor antagonist, chlordiazepoxide and a TRH-R1 antibody, partially decreased the fecal pellets of WAS rats during the 10-day stress period. Furthermore, TRH increased the peak current of L-type channels in colonic smooth muscle cells (SMCs) at a membrane potential of 0 mV, while the current of large conductance Ca²⁺-activated K⁺ (BK_Ca) channels was not changed following the addition of TRH.

CONCLUSION

TRH may be involved in the dysmotility induced by chronic stress and may have some potential clinical therapeutic use in regulating gut motility.

Exosomes derived from high-glucose-stimulated Schwann cells promote development of diabetic peripheral neuropathy

Schwann cells actively interact with axons of dorsal root ganglia (DRG) neurons. Exosomes mediate intercellular communication by transferring their biomaterials, including microRNAs (miRs) into recipient cells. We hypothesized that exosomes derived from Schwann cells stimulated by high glucose (HG) exosomes accelerate development of diabetic peripheral neuropathy and that exosomal cargo miRs contribute to this process. We found that HG exosomes contained high levels of miR-28, -31a, and -130a compared to exosomes derived from non-HG-stimulated Schwann cells. In vitro, treatment of distal axons with HG exosomes resulted in reduction of axonal growth, which was associated with elevation of miR-28, -31a, and -130a and reduction of their target proteins of DNA methyltransferase-3α, NUMB (an endocytic adaptor protein), synaptosome associated protein 25, and growth-associated protein-43 in axons. In vivo, administration of HG exosomes to sciatic nerves of diabetic db/db mice at 7 wk of age promoted occurrence of peripheral neuropathy characterized by impairment of nerve conduction velocity and induction of mechanic and thermal hypoesthesia, which was associated with substantial decreases in intraepidermal nerve fibers. Our findings demonstrate a functional role of exosomes derived from HG-stimulated Schwann cells in mediating development of diabetic peripheral neuropathy.-Jia, L., Chopp, M., Wang, L., Lu, X., Szalad, A., Zhang, Z. G. Exosomes derived from high-glucose-stimulated Schwann cells promote development of diabetic peripheral neuropathy.

Sex differences in NSAID-induced perturbation of human intestinal barrier function and microbiota

Intestinal barrier function and microbiota are integrally related and play critical roles in maintenance of host physiology. Sex is a key biologic variable for several disorders. Our aim was to determine sex-based differences in response to perturbation and subsequent recovery of intestinal barrier function and microbiota in healthy humans. Twenty-three volunteers underwent duodenal biopsies, mucosal impedance, and in vivo permeability measurement. Permeability testing was repeated after administration of indomethacin, then 4 to 6 wk after its discontinuation. Duodenal and fecal microbiota composition was determined using 16S rRNA amplicon sequencing. Healthy women had lower intestinal permeability and higher duodenal and fecal microbial diversity than healthy men. Intestinal permeability increases after indomethacin administration in both sexes. However, only women demonstrated decreased fecal microbial diversity, including an increase in Prevotella abundance, after indomethacin administration. Duodenal microbiota composition did not show sex-specific changes. The increase in permeability and microbiota changes normalized after discontinuation of indomethacin. In summary, women have lower intestinal permeability and higher microbial diversity. Intestinal permeability is sensitive to perturbation but recovers to baseline. Gut microbiota in women is sensitive to perturbation but appears to be more stable in men. Sex-based differences in intestinal barrier function and microbiome should be considered in future studies.-Edogawa, S., Peters, S. A., Jenkins, G. D., Gurunathan, S. V., Sundt, W. J., Johnson, S., Lennon, R. J., Dyer, R. B., Camilleri, M., Kashyap, P. C., Farrugia, G., Chen, J., Singh, R. J., Grover, M. Sex differences in NSAID-induced perturbation of human intestinal barrier function and microbiota.

Mechanisms of Stress-induced Visceral Pain

Evidence suggests that long-term stress facilitates visceral pain through sensitization of pain pathways and promotes chronic visceral pain disorders such as the irritable bowel syndrome (IBS). This review will describe the importance of stress in exacerbating IBS-induced abdominal pain. Additionally, we will briefly review our understanding of the activation of the hypothalamic-pituitary-adrenal axis by both chronic adult stress and following early life stress in the pathogenesis of IBS. The review will focus on the glucocorticoid receptor and corticotropin-releasing hormone-mediated mechanisms in the amygdala involved in stress-induced visceral hypersensitivity. One potential mechanism underlying persistent effects of stress on visceral sensitivity could be epigenetic modulation of gene expression. While there are relatively few studies examining epigenetically mediated mechanisms involved in stress-induced visceral nociception, alterations in DNA methylation and histone acetylation patterns within the brain, have been linked to alterations in nociceptive signaling via increased expression of pro-nociceptive neurotransmitters. This review will discuss the latest studies investigating the long-term effects of stress on visceral sensitivity. Additionally, we will critically review the importance of experimental models of adult stress and early life stress in enhancing our understanding of the basic molecular mechanisms of nociceptive processing.

The Role of Bacteria, Probiotics and Diet in Irritable Bowel Syndrome

Irritable bowel syndrome is a highly prevalent gastrointestinal disorder that threatens the quality of life of millions and poses a substantial financial burden on healthcare systems around the world. Intense research into the human microbiome has led to fascinating discoveries which directly and indirectly implicate the diversity and function of this occult organ in irritable bowel syndrome (IBS) pathophysiology. The benefit of manipulating the gastrointestinal microbiota with diet and probiotics to improve symptoms has been demonstrated in a wealth of both animal and human studies. The positive and negative mechanistic roles bacteria play in IBS will be explored and practical probiotic and dietary choices offered.

Subthreshold Psychiatric Psychopathology in Functional Gastrointestinal Disorders: Can It Be the Bridge between Gastroenterology and Psychiatry?

Background and Aims

Functional gastrointestinal disorders (FGDs) are multifactorial disorders of the gut-brain interaction. This study investigated the prevalence of Axis I and spectrum disorders in patients with FGD and established the link between FGDs and psychopathological dimensions.

Methods

A total of 135 consecutive patients with FGD were enrolled. The symptoms' severity was evaluated using questionnaires, while the psychiatric evaluation by clinical interviews established the presence/absence of mental (Diagnostic and Statistical Manual-4th edition, Axis I Diagnosis) or spectrum disorders.

Results

Of the 135 patients, 42 (32.3%) had functional dyspepsia, 52 (40.0%) had irritable bowel syndrome, 21 (16.2%) had functional bloating, and 20 (15.4%) had functional constipation. At least one psychiatric disorder was present in 46.9% of the patients, while a suprathreshold panic spectrum was present in 26.2%. Functional constipation was associated with depressive disorders (p < 0.05), while functional dyspepsia was related to the current major depressive episode (p < 0.05). Obsessive-compulsive spectrum was correlated with the presence of functional constipation and irritable bowel syndrome (p < 0.05).

Conclusion

The high prevalence of subthreshold psychiatric symptomatology in patients with FGD, which is likely to influence the expression of gastrointestinal symptoms, suggested the usefulness of psychological evaluation in patients with FGDs.

The effect of age on the intestinal mucus thickness, microbiota composition and immunity in relation to sex in mice

A mucus layer covers and protects the intestinal epithelial cells from direct contact with microbes. This mucus layer not only prevents inflammation but also plays an essential role in microbiota colonization, indicating the complex interplay between mucus composition-microbiota and intestinal health. However, it is unknown whether the mucus layer is influenced by age or sex and whether this contributes to reported differences in intestinal diseases in males and females or with ageing. Therefore, in this study we investigated the effect of age on mucus thickness, intestinal microbiota composition and immune composition in relation to sex. The ageing induced shrinkage of the colonic mucus layer was associated with bacterial penetration and direct contact of bacteria with the epithelium in both sexes. Additionally, several genes involved in the biosynthesis of mucus were downregulated in old mice, especially in males, and this was accompanied by a decrease in abundances of various Lactobacillus species and unclassified Clostridiales type IV and XIV and increase in abundance of the potential pathobiont Bacteroides vulgatus. The changes in mucus and microbiota in old mice were associated with enhanced activation of the immune system as illustrated by a higher percentage of effector T cells in old mice. Our data contribute to a better understanding of the interplay between mucus-microbiota-and immune responses and ultimately may lead to more tailored design of strategies to modulate mucus production in targeted groups.

Diets link metabolic syndrome and colorectal cancer development (Review)

Diets have been believed to be an important factor in the development of metabolic syndrome and colorectal cancer (CRC). In recent years, many studies have shown an intimate relationship between mucosal immunity, metabolism and diets, which has led to a greater understanding of the pathophysiology of metabolic syndrome and CRC development. Although the precise effects of diets on oncogenesis have not been compl-etely elucidated, microbiota changes and inflammation are believed to be important factors that influence the development of CRC. Moreover, increased release of pro-inflammatory cytokines and alteration of adipokine levels have been observed in patients with colorectal adenoma and/or CRC, and these all have been considered as the important mechanisms that link diets to the development of metabolic syndrome and CRC. Importantly, a high-fat, low-fiber diet is associated with dysbiosis, and as the gut signature becomes more important in metabolic syndrome and CRC, an increased understanding of diets on bacterial activity in the pathogenesis of metabolic syndrome and CRC will lead to new preventive and therapeutic strategies.