Similar Fecal Microbiota Signatures in Patients With Diarrhea-Predominant Irritable Bowel Syndrome and Patients With Depression

Shared and distinct aberrations in frontal-striatal system functional patterns among patients with irritable bowel syndrome and major depressive disorder

BACKGROUND

Considering the high comorbidity, shared risk factors, and genetic pathways between irritable bowel syndrome (IBS) and major depressive disorder (MDD), we hypothesized that there would be both shared and disorder-specific alterations in brain function.

METHODS

A total of 39 IBS patients, 39 MDD patients, and 40 healthy controls (HCs) were enrolled and matched for sex, age, and educational level. All subjects underwent resting-state functional MRI. The clinical variables of anxiety, depression, gastrointestinal symptoms and alexithymia were recorded. The 12 subregions of the striatum were employed as seeds to assess their functional connectivity (FC) with every voxel throughout the whole brain.

RESULTS

Compared to HC, IBS and MDD patients exhibited aberrant frontal-striatal circuitry. We observed a common decrease in FC between the dorsal striatum and regions of the hippocampus, sensorimotor cortex, and prefrontal cortex (PFC) in both IBS and MDD patients. Patients with IBS exhibited disorder-specific decreases in FC within the striatum, along with reduced connectivity between the ventral striatum and sensorimotor cortex. In contrast, MDD patients showed disorder-specific hyperconnectivity in the medial PFC-limbic system. Receiver operating characteristic curve analysis showed that frontal-striatal FC values could serve as transdiagnostic markers of IBS and MDD. Within the IBS group, striatal connectivity was not only negatively associated with weekly abdominal pain days but also negatively correlated with the levels of anxiety and alexithymia.

CONCLUSIONS

This exploratory analysis indicated that patients with IBS and MDD exhibited both shared and disorder-specific frontal-striatal circuit impairments, potentially explaining both comorbidity and distinct phenotypes.

New perspectives on microbiome-dependent gut-brain pathways for the treatment of depression with gastrointestinal symptoms: from bench to bedside

Patients with depression are more likely to have chronic gastrointestinal (GI) symptoms than the general population, but such symptoms are considered only somatic symptoms of depression and lack special attention. There is a chronic lack of appropriate diagnosis and effective treatment for patients with depression accompanied by GI symptoms, and studying the association between depression and GI disorders (GIDs) is extremely important for clinical management. There is growing evidence that depression is closely related to the microbiota present in the GI tract, and the microbiota-gut-brain axis (MGBA) is creating a new perspective on the association between depression and GIDs. Identifying and treating GIDs would provide a key opportunity to prevent episodes of depression and may also improve the outcome of refractory depression. Current studies on depression and the microbially related gut-brain axis (GBA) lack a focus on GI function. In this review, we combine preclinical and clinical evidence to summarize the roles of the microbially regulated GBA in emotions and GI function, and summarize potential therapeutic strategies to provide a reference for the study of the pathomechanism and treatment of depression in combination with GI symptoms.

A New Strategy for Dietary Nutrition to Improve Intestinal Homeostasis in Diarrheal Irritable Bowel Syndrome: A Perspective on Intestinal Flora and Intestinal Epithelial Interaction

BACKGROUND AND OBJECTIVES

Although a reasonable diet is essential for promoting human health, precise nutritional regulation presents a challenge for different physiological conditions. Irritable Bowel Syndrome (IBS) is characterized by recurrent abdominal pain and abnormal bowel habits, and diarrheal IBS (IBS-D) is the most common, seriously affecting patients' quality of life. Therefore, the implementation of precise nutritional interventions for IBS-D has become an urgent challenge in the fields of nutrition and food science. IBS-D intestinal homeostatic imbalance involves intestinal flora disorganization and impaired intestinal epithelial barrier function. A familiar interaction is evident between intestinal flora and intestinal epithelial cells (IECs), which together maintain intestinal homeostasis and health. Dietary patterns, such as the Mediterranean diet, have been shown to regulate gut flora, which in turn improves the body's health by influencing the immune system, the hormonal system, and other metabolic pathways.

METHODS

This review summarized the relationship between intestinal flora, IECs, and IBS-D. It analyzed the mechanism behind IBS-D intestinal homeostatic imbalance by examining the interactions between intestinal flora and IECs, and proposed a precise dietary nutrient intervention strategy.

RESULTS AND CONCLUSION

This increases the understanding of the IBS-D-targeted regulation pathways and provides guidance for designing related nutritional intervention strategies.

Cutting-Edge iPSC-Based Approaches in Studying Host-Microbe Interactions in Neuropsychiatric Disorders

Gut microbiota (GM), together with its metabolites (such as SCFA, tryptophan, dopamine, GABA, etc.), plays an important role in the functioning of the central nervous system. Various neurological and psychiatric disorders are associated with changes in the composition of GM and their metabolites, which puts them in the foreground as a potential adjuvant therapy. However, the molecular mechanisms behind this relationship are not clear enough. Therefore, before considering beneficial microbes and/or their metabolites as potential therapeutics for brain disorders, the mechanisms underlying microbiota-host interactions must be identified and characterized in detail. In this review, we summarize the current knowledge of GM alterations observed in prevalent neurological and psychiatric disorders, multiple sclerosis, major depressive disorder, Alzheimer's disease, and autism spectrum disorders, together with experimental evidence of their potential to improve patients' quality of life. We further discuss the main obstacles in the study of GM-host interactions and describe the state-of-the-art solution and trends in this field, namely "culturomics" which enables the culture and identification of novel bacteria that inhabit the human gut, and models of the gut and blood-brain barrier as well as the gut-brain axis based on induced pluripotent stem cells (iPSCs) and iPSC derivatives, thus pursuing a personalized medicine agenda for neuropsychiatric disorders.

Association between bowel movement disorders and depressive symptoms: a cross-sectional study

Objectives

This study aimed to explore the association between bowel movement disorders and depression in adults.

Method

A cross-sectional study was conducted using data from the National Health and Nutritional Examination Survey (NHANES), 2005-2010. Depression, constipation, diarrhea, and fecal incontinence were self-reported via questionnaires. Weighted logistic regression and subgroup analyses were performed to explore the association between bowel movement disorders and the risk of depression. Restricted cubic spline (RCS) was also conducted to investigate the association between bowel movements disorder and depression.

Results

A total of 13,820 participants were collected. Compared to the participants with normal bowel movements, the full-adjusted depression model ORs for constipation and diarrhea were 2.28 (95%CI,1.78-2.92), 1.75 (95%CI,1.31-2.31), respectively. Any kind of bowel leakage were associated with depression. The RCS showed the possible nonlinear association between bowel movement frequency/stool shape and depression.

Conclusions

Constipation, diarrhea, and bowel leakage are associated with an increased risk of depression.

Microbiota-Short Chain Fatty Acid Relationships Underlie Clinical Heterogeneity and Identify Key Microbial Targets in Irritable Bowel Syndrome (IBS)

Background

Identifying microbial targets in irritable bowel syndrome (IBS) and other disorders of gut-brain interaction (DGBI) is challenging due to the dynamic nature of microbiota-metabolite-host interactions. SCFA are key microbial metabolites that modulate intestinal homeostasis and may influence IBS pathophysiology. We aimed to assess microbial features associated with short chain fatty acids (SCFA) and determine if features varied across IBS subtypes and endophenotypes. Among 96 participants who were screened, 71 completed the study. We conducted in-depth investigations of stool microbial metagenomes, stool SCFA, and measurable IBS traits (stool bile acids, colonic transit, stool form) in 41 patients with IBS (IBS with constipation [IBS-C] IBS with diarrhea [IBS-D]) and 17 healthy controls. We used partial canonical correspondence analyses (pCCA), conditioned on transit, to quantify microbe-SCFA associations across clinical groups. To explore relationships between microbially-derived SCFA and IBS traits, we compared gut microbiome-encoded potential for substrate utilization across groups and within a subset of participants selected by their stool characteristics as well as stool microbiomes of patients with and without clinical bile acid malabsorption.

Results

Overall stool microbiome composition and individual taxa abundances differed between clinical groups. Microbes-SCFA associations differed across groups and revealed key taxa including Dorea sp. CAG:317 and Bifidobacterium pseudocatenulatum in IBS-D and Akkermansia muciniphila and Prevotella copri in IBS-C that that may drive subtype-specific microbially-mediated mechanisms. Strongest microbe-SCFA associations were observed in IBS-D and several SCFA-producing species surprisingly demonstrated inverse correlations with SCFA. Fewer bacterial taxa were associated with acetate to butyrate ratios in IBS compared to health. In participants selected by stool form, we demonstrated differential abundances of microbial genes/pathways for SCFA metabolism and degradation of carbohydrates and mucin across groups. SCFA-producing taxa were reduced in IBS-D patients with BAM.

Conclusion

Keystone taxa responsible for SCFA production differ according to IBS subtype and traits and the IBS microbiome is characterized by reduced functional redundancy. Differences in microbial substrate preferences are also linked to bowel functions. Focusing on taxa that drive SCFA profiles and stool form may be a rational strategy for identifying relevant microbial targets in IBS and other DGBI.

Fecal Microbiota Characteristics in Constipation-Predominant and Mixed-Type Irritable Bowel Syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is a common condition that affects the lifestyle of patients. It is associated with significant changes in the composition of the gut microbiome, but the underlying microbial mechanisms remain to be fully understood. We study the fecal microbiome of patients with constipation-predominant IBS (IBS-C) and mixed-type IBS (IBS-M).

METHODS

We sequenced the V3 region of the 16S rRNA on the Ion Torrent PGM sequencing platform to study the microbiome.

RESULTS

In the patients with IBS-C and IBS-M, an increase in alpha diversity was found, compared to the healthy group, and differences in beta diversity were also noted. At the phylum level, both IBS subtypes showed an increase in the Firmicutes/Bacteroidetes ratio, as well as an increase in the abundance of Actinobacteria and Verrucomicrobiota. Changes in some types of bacteria were characteristic of only one of the IBS subtypes, while no statistically significant differences in the composition of the microbiome were detected between IBS-C and IBS-M.

CONCLUSIONS

This study was the first to demonstrate the association of Turicibacter sanguinis, Mitsuokella jalaludinii, Erysipelotrichaceae UCG-003, Senegalimassilia anaerobia, Corynebacterium jeikeium, Bacteroides faecichinchillae, Leuconostoc carnosum, and Parabacteroides merdae with IBS subtypes.

A meta-analysis of randomized controlled trials evaluating the effectiveness of fecal microbiota transplantation for patients with irritable bowel syndrome

OBJECTIVE

Multiple randomized controlled trials (RCTs) have investigated the efficacy of fecal microbiota transplantation (FMT) for irritable bowel syndrome (IBS), but have yielded inconsistent results. We updated the short-term and long-term efficacy of FMT in treating IBS, and performed a first-of-its-kind exploration of the relationship between gut microbiota and emotions.

METHODS

We conducted a comprehensive search of PubMed, Embase, Web of Science, and the Cochrane Library using various search strategies to identify all eligible studies. The inclusion criteria for data extraction were randomized controlled trials (RCTs) that investigated the efficacy of fecal microbiota transplantation (FMT) compared to placebo in adult patients (≥ 18 years old) with irritable bowel syndrome (IBS). A meta-analysis was then performed to assess the summary relative risk (RR) and corresponding 95% confidence intervals (CIs).

RESULTS

Out of 3,065 potentially relevant records, a total of 10 randomized controlled trials (RCTs) involving 573 subjects met the eligibility criteria for inclusion in the meta-analysis. The meta-analyses revealed no significant differences in short-term (12 weeks) (RR 0.20, 95% CI -0.04 to 0.44), long-term (52 weeks) global improvement (RR 1.38, 95% CI 0.87 to 2.21), besides short-term (12 weeks) (SMD - 48.16, 95% CI -102.13 to 5.81, I2 = 90%) and long-term (24 weeks) (SMD 2.16, 95% CI -60.52 to 64.83, I2 = 68%) IBS-SSS. There was statistically significant difference in short-term improvement of IBS-QoL (SMD 10.11, 95% CI 0.71 to 19.51, I2 = 82%), although there was a high risk of bias. In terms of long-term improvement (24 weeks and 54 weeks), there were no significant differences between the FMT and placebo groups (SMD 7.56, 95% CI 1.60 to 13.52, I2 = 0%; SMD 6.62, 95% CI -0.85 to 14.08, I2 = 0%). Sensitivity analysis indicated that there were visible significant effects observed when the criteria were based on Rome IV criteria (RR 16.48, 95% CI 7.22 to 37.62) and Gastroscopy (RR 3.25, 95%CI 2.37 to 4.47), Colonoscopy (RR 1.42, 95% CI 0.98 to 2.05). when using mixed stool FMT based on data from two RCTs, no significant difference was observed (RR 0.94, 95% CI 0.66 to -1.34). The remission of depression exhibited no significant difference between the FMT and placebo groups at the 12-week mark (SMD - 0.26, 95% CI -3.09 to 2.58), and at 24 weeks (SMD - 2.26, 95% CI -12.96 to 8.45). Furthermore, major adverse events associated with FMT were transient and self-limiting.

DISCUSSION

Based on the available randomized controlled trials (RCTs), the current evidence does not support the efficacy of FMT in improving global IBS symptoms in the long term. The differential results observed in subgroup analyses raise questions about the accurate identification of suitable populations for FMT. Further investigation is needed to better understand the reasons behind these inconsistent findings and to determine the true potential of FMT as a treatment for IBS.

The Microbiome in Child and Adolescent Psychiatry

Recent research has increasingly emphasized the function of the microbiome in human health. The gut microbiome is essential for digesting food and seems to play a vital role in mental health as well. This review briefly overviews the gut microbiome and its interplay with the central nervous system. We then summarize some of the latest findings on the possible role of the microbiome in psychiatric disorders in children and adolescents. In particular, we focus on autism spectrum disorder, attention-deficit/hyperactivity disorder, anorexia nervosa, bipolar disorder, and major depressive disorder. Although the role of microbiota in mental development and health still needs to be researched intensively, it has become increasingly apparent that the impact of microbiota must be considered to better understand psychiatric disorders.

Treating chronic stress and chronic pain by manipulating gut microbiota with diet: can we kill two birds with one stone?

Background: Chronic stress and chronic pain are closely linked by the capacity to exacerbate each other, sharing common roots in the brain and in the gut. The strict intersection between these two neurological diseases makes important to have a therapeutic strategy aimed at preventing both to maintain mental health in patients. Diet is an modifiable lifestyle factor associated with gut-brain axis diseases and there is growing interest in its use as adjuvant to main therapies. Several evidence attest the impact of specific diets or nutrients on chronic stress-related disorders and pain with a good degree of certainty. A daily adequate intake of foods containing micronutrients such as amino acids, minerals and vitamins, as well as the reduction in the consumption of processed food products can have a positive impact on microbiota and gut health. Many nutrients are endowed of prebiotic, anti-inflammatory, immunomodulatory and neuroprotective potential which make them useful tools helping the management of chronic stress and pain in patients. Dietary regimes, as intermittent fasting or caloric restriction, are promising, although further studies are needed to optimize protocols according to patient's medical history, age and sex. Moreover, by supporting gut microbiota health with diet is possible to attenuate comorbidities such as obesity, gastrointestinal dysfunction and mood disorders, thus reducing healthcare costs related to chronic stress or pain.Objective: This review summarize the most recent evidence on the microbiota-mediated beneficial effects of macro- and micronutrients, dietary-related factors, specific nutritional regimens and dietary intervention on these pathological conditions.

Interplay Between Drug-Induced Liver Injury and Gut Microbiota: A Comprehensive Overview

Drug-induced liver injury is a prevalent severe adverse event in clinical settings, leading to increased medical burdens for patients and presenting challenges for the development and commercialization of novel pharmaceuticals. Research has revealed a close association between gut microbiota and drug-induced liver injury in recent years. However, there has yet to be a consensus on the specific mechanism by which gut microbiota is involved in drug-induced liver injury. Gut microbiota may contribute to drug-induced liver injury by increasing intestinal permeability, disrupting intestinal metabolite homeostasis, and promoting inflammation and oxidative stress. Alterations in gut microbiota were found in drug-induced liver injury caused by antibiotics, psychotropic drugs, acetaminophen, antituberculosis drugs, and antithyroid drugs. Specific gut microbiota and their abundance are associated closely with the severity of drug-induced liver injury. Therefore, gut microbiota is expected to be a new target for the treatment of drug-induced liver injury. This review focuses on the association of gut microbiota with common hepatotoxic drugs and the potential mechanisms by which gut microbiota may contribute to the pathogenesis of drug-induced liver injury, providing a more comprehensive reference for the interaction between drug-induced liver injury and gut microbiota.

Microbial and metabolomic profiles of type 1 diabetes with depression: A case-control study

BACKGROUND

Depression is the most common psychological disorder in patients with type 1 diabetes (T1D). However, the characteristics of microbiota and metabolites in these patients remain unclear. This study aimed to investigate microbial and metabolomic profiles and identify novel biomarkers for T1D with depression.

METHODS

A case-control study was conducted in a total of 37 T1D patients with depression (TD+), 35 T1D patients without depression (TD-), and 29 healthy controls (HCs). 16S rRNA gene sequencing and liquid chromatography-mass spectrometry (LC-MS) metabolomics analysis were conducted to investigate the characteristics of microbiota and metabolites. The association between altered microbiota and metabolites was explored by Spearman's rank correlation and visualized by a heatmap. The microbial signatures to discriminate TD+ from TD- were identified by a random forest (RF) classifying model.

RESULTS

In microbiota, 15 genera enriched in TD- and 2 genera enriched in TD+, and in metabolites, 14 differential metabolites (11 upregulated and 3 downregulated) in TD+ versus TD- were identified. Additionally, 5 genera (including Phascolarctobacterium, Butyricimonas, and Alistipes from altered microbiota) demonstrated good diagnostic power (area under the curve [AUC] = 0.73; 95% CI, 0.58-0.87). In the correlation analysis, Butyricimonas was negatively correlated with glutaric acid (r = -0.28, p = 0.015) and malondialdehyde (r = -0.30, p = 0.012). Both Phascolarctobacterium (r = 0.27, p = 0.022) and Alistipes (r = 0.31, p = 0.009) were positively correlated with allopregnanolone.

CONCLUSIONS

T1D patients with depression were characterized by unique profiles of gut microbiota and serum metabolites. Phascolarctobacterium, Butyricimonas, and Alistipes could predict the risk of T1D with depression. These findings provide further evidence that the microbiota-gut-brain axis is involved in T1D with depression.

Gut microbiota: A potential player in psychiatric symptoms during COVID-19

OBJECTIVES

This study aims to explore the potential interconnections among gut microbiota, COVID-19 infection, depression and anxiety disorder. Additionally, it tries to assess potential therapeutic interventions that may improve the dysbiosis of gut microbiota.

METHODS

To achieve these objectives, we reviewed existing literature, encompassing studies and critical reviews that intersect the domains of gut microbiota, COVID-19, depression and anxiety disorders.

RESULTS

The findings highlight a notable correlation between the dysbiosis of gut microbiota and psychiatric symptoms in the context of COVID-19. Specifically, there is a marked reduction in the populations of bacteria that generate anti-inflammatory short-chain fatty acids (SCFAs), alongside a rise in the prevalence of gut bacterial clusters linked to inflammatory processes. Furthermore, several potential treatment strategies were summarised for improving the dysbiosis.

CONCLUSIONS

Gut microbiota plays a significant role in psychiatric symptoms during COVID-19, which has significant implications for the study and prevention of psychiatric symptoms in major epidemic diseases.

Social isolation induces intestinal barrier disorder and imbalances gut microbiota in mice

Social isolation, a known stressor, can have detrimental effects on both physical and mental health. Recent scientific attention has been drawn to the gut-brain axis, a bidirectional communication system between the central nervous system and gut microbiota, suggesting that gut microbes may influence brain function. This study aimed to explore the impact of social isolation on the intestinal barrier and gut microbiota. 40 male BALB/c mice were either individually housed or kept in groups for 8 and 15 weeks. Socially isolated mice exhibited increased anxiety-like behavior, with significant differences between the 8-week and 15-week isolation groups (P < 0.05). After 8 weeks of isolation, there was a reduction in tight junction protein expression in the intestinal mechanical barrier. Furthermore, after 15 weeks of isolation, both tight junction protein and mucin expression, key components of the intestinal chemical barrier, decreased. This was accompanied by a substantial increase in inflammatory cytokines (IL-6 mRNA, IL-10, and TNF-α) in colon tissue in the 15-week isolated group (P < 0.05). Additionally, Illumina MiSequencing revealed significant alterations in the gut microbiota of socially isolated mice, including reduced Firmicutes and Bacteroides compared to the control group. Lactobacillus levels also decreased in the socially isolated mice.

Microbial composition, functionality, and stress resilience or susceptibility: unraveling sex-specific patterns

BACKGROUND

Following exposure to traumatic stress, women are twice as likely as men to develop mood disorders. Yet, individual responses to such stress vary, with some people developing stress-induced psychopathologies while others exhibit resilience. The factors influencing sex-related disparities in affective disorders as well as variations in resilience remain unclear; however, emerging evidence suggests differences in the gut microbiota play a role. In this study, using the single prolonged stress (SPS) model of post-traumatic stress disorder, we investigated pre- and post-existing differences in microbial composition, functionality, and metabolites that affect stress susceptibility or resilience in each sex.

METHODS

Male and female Sprague-Dawley rats were randomly assigned to control or SPS groups. Two weeks following SPS, the animals were exposed to a battery of behavioral tests and decapitated a day later. Based on their anxiety index, they were further categorized as SPS-resilient (SPS-R) or SPS-susceptible (SPS-S). On the day of dissection, cecum, and selected brain tissues were isolated. Stool samples were collected before and after SPS, whereas urine samples were taken before and 30 min into the SPS.

RESULTS

Before SPS exposure, the sympathoadrenal axis exhibited alterations within male subgroups only. Expression of tight junction protein claudin-5 was lower in brain of SPS-S males, but higher in SPS-R females following SPS. Across the study, alpha diversity remained consistently lower in males compared to females. Beta diversity revealed distinct separations between male and female susceptible groups before SPS, with this separation becoming evident in the resilient groups following SPS. At the genus level, Lactobacillus, Lachnospiraceae_Incertae_Sedis, and Barnesiella exhibited sex-specific alterations, displaying opposing abundances in each sex. Additionally, sex-specific changes were observed in microbial predictive functionality and targeted functional modules both before and after SPS. Alterations in the microbial short-chain fatty acids (SCFAs), were also observed, with major and minor SCFAs being lower in SPS-susceptible males whereas branched-chain SCFAs being higher in SPS-susceptible females.

CONCLUSION

This study highlights distinct pre- and post-trauma differences in microbial composition, functionality, and metabolites, associated with stress resilience in male and female rats. The findings underscore the importance of developing sex-specific therapeutic strategies to effectively address stress-related disorders. Highlights SPS model induces divergent anxiety and social behavioral responses to traumatic stress in both male and female rodents. SPS-resilient females displayed less anxiety-like behavior and initiated more interactions towards a juvenile rat than SPS-resilient males. Sex-specific pre-existing and SPS-induced differences in the gut microbial composition and predictive functionality were observed in susceptible and resilient rats. SPS-resilient males displayed elevated cecal acetate levels, whereas SPS-susceptible females exhibited heightened branched-chain SCFAs.

Gut microbiota-derived short-chain fatty acids and depression: deep insight into biological mechanisms and potential applications

The gut microbiota is a complex and dynamic ecosystem known as the 'second brain'. Composing the microbiota-gut-brain axis, the gut microbiota and its metabolites regulate the central nervous system through neural, endocrine and immune pathways to ensure the normal functioning of the organism, tuning individuals' health and disease status. Short-chain fatty acids (SCFAs), the main bioactive metabolites of the gut microbiota, are involved in several neuropsychiatric disorders, including depression. SCFAs have essential effects on each component of the microbiota-gut-brain axis in depression. In the present review, the roles of major SCFAs (acetate, propionate and butyrate) in the pathophysiology of depression are summarised with respect to chronic cerebral hypoperfusion, neuroinflammation, host epigenome and neuroendocrine alterations. Concluding remarks on the biological mechanisms related to gut microbiota will hopefully address the clinical value of microbiota-related treatments for depression.

Pick fecal microbiota transplantation to enhance therapy for major depressive disorder

In recent years, fecal microbiota transplantation (FMT) has emerged as a promising therapy for major depressive disorder (MDD). The goal of the operation is to restore a healthy gut microbiota by introducing feces from a healthy donor into the recipient's digestive system. The brain-gut axis is thought to have a significant role in regulating mood, behavior, and cognition, which supports the use of FMT in the treatment of MDD. Numerous studies have shown a correlation between abnormalities of the gut microbiota and MDD, whereas FMT has demonstrated the potential to restore microbial equilibrium. While FMT has shown encouraging results, it is crucial to highlight the potential hazards and limits inherent to this therapeutic approach. Stool donor-to-recipient disease transfer is a concern of FMT. Furthermore, it still needs to be determined what effect FMT has on the gut microbiota and the brain in the long run. This literature review provides an overview of the possible efficacy of FMT as a therapeutic modality for MDD. There is hope for patients who have not reacted well to typical antidepressant therapy since FMT may become an invaluable tool in the treatment of MDD as researchers continue to examine the relationship between gut microbiota and MDD.

Exploring the human gut microbiota targets in relation to the use of contemporary antidepressants

BACKGROUND

Antidepressants, specifically selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs), are commonly prescribed for depression treatment. Animal studies have shown that antidepressants can influence gut microbiota composition and specific bacterial taxa. We aimed to investigate the association between antidepressant use and human gut microbiota composition and functional pathway.

METHODS

We collected information on antidepressant use, demographic, food patterns, and clinical characteristics through questionnaires and medical records. The gut microbiota profiles of 271 depressive patients were carried out through 16S rRNA gene sequencing. Patients were categorized based on different types of antidepressant use groups for gut microbiota comparisons. MaAsLin2 was performed to evaluate microbiota composition across groups. PICRUSt2 was used to predict microbiota functional pathways.

RESULTS

Patients taking SSRIs or SNRIs had a lower microbiota diversity. We found seven taxa abundances (Turicibacter, Barnesiella, Lachnospiraceae_ND3007_group, Romboutia, Akkermansia, Dialister, Romboutia and Fusicatenibacter) differed in patients with various types of antidepressants compared with those without antidepressant treatments (p < 0.05). Turicibacter inversely correlated with depression severity in SSRIs or SNRI users (r = -0.43, p < 0.05). Top identified pathways were related to compound fermentation and biosynthesis in microbiota function.

CONCLUSION

Antidepressant usage, especially SSRIs and SNRIs, associates with changes in gut microbiota composition and specific taxa. Given our study's preliminary cross-sectional nature, further research is warranted to comprehend the relationship between antidepressant use, treatment response, and gut microbiota, aiming to enhance therapeutic interventions in the future.

Probiotics and Fecal Microbiota Transplantation in Major Depression: Doxa or Episteme?

In the human body, eukaryotic somatic cells and prokaryotic microorganisms live together. In this state, the body can be viewed as a "superorganism." Symbiotic life with commensal microorganisms can be observed in almost every part of the body. Intestinal microbiota plays an important role in health and disease, and in shaping and regulating neuronal functions from the intrauterine period to the end of life. Microbiota-based treatment opportunities are becoming more evident in both understanding the etiopathogenesis and treatment of neuropsychiatric disorders, especially depression. Antidepressant drugs, which are the first choice in the treatment of depression, also have antimicrobial and immunomodulatory mechanisms of action. From these perspectives, direct probiotics and fecal microbiota transplantation are treatment options to modulate microbiota composition. There are few preclinical and clinical studies on the effectiveness and safety of these applications in depression. The information obtained from these studies may still be at a doxa level. However, the probability that this information will become episteme in the future seems to be increasing.

Cognitive function in patients with irritable bowel syndrome: impairment is common and only weakly correlated with depression/anxiety and severity of gastrointestinal symptoms

OBJECTIVE

To investigate cognitive function in patients with irritable bowel syndrome (IBS) and its relation to anxiety/depression and severity of gastrointestinal (GI) symptoms.

METHODS

Patients with IBS (n = 65) and healthy controls (HCs, n = 37) performed the ten subtests of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Age-normed index scores of five cognitive domains (Immediate memory, Visuospatial function, Language function, Attention, Recall) and a total (Fullscale) score were derived from the performance. Emotional function was assessed using the Hospital Anxiety and Depression Scale (HADS), and the IBS Symptom Scoring System (IBS-SSS) was used to define the severity of GI symptoms.

RESULTS

Patients with IBS reported significantly higher scores than the HC group on symptom measures of anxiety and depression, and significantly lower scores on the Immediate memory, Recall, and Fullscale RBANS indexes. Approximately 30% of the IBS patients obtained index scores at least one standard deviation below the population mean, and more than 50% scored above the screening threshold for an anxiety disorder. The severity of GI symptoms was significantly correlated with the severity level of anxiety symptoms (p=.006), but neither the severity level of emotional nor GI symptoms was significantly correlated with the RBANS index scores in the IBS group.

CONCLUSION

Cognitive and emotional function were more severely affected in patients with IBS than in HCs. The weak correlation between the two functional areas suggests that both should be assessed as part of a clinical examination of patients with IBS.

Gut microbiota composition in depressive disorder: a systematic review, meta-analysis, and meta-regression

Studies investigating gut microbiota composition in depressive disorder have yielded mixed results. The aim of our study was to compare gut microbiome between people with depressive disorder and healthy controls. We did a meta-analysis and meta-regression of studies by searching PubMed, Web of Science, Embase, Scopus, Ovid, Cochrane Library, ProQuest, and PsycINFO for articles published from database inception to March 07, 2022. Search strategies were then re-run on 12 March 2023 for an update. We undertook meta-analyses whenever values of alpha diversity and Firmicutes, Bacteroidetes (relative abundance) were available in two or more studies. A random-effects model with restricted maximum-likelihood estimator was used to synthesize the effect size (assessed by standardized mean difference [SMD]) across studies. We identified 44 studies representing 2091 patients and 2792 controls. Our study found that there were no significant differences in patients with depressive disorder on alpha diversity indices, Firmicutes and Bacteroidetes compared with healthy controls. In subgroup analyses with regional variations(east/west) as a predictor, patients who were in the West had a lower Chao1 level (SMD -0.42[-0.74 to -0.10]). Subgroup meta-analysis showed Firmicutes level was decreased in patients with depressive disorder who were medication-free (SMD -1.54[-2.36 to -0.72]), but Bacteroidetes level was increased (SMD -0.90[0.07 to 1.72]). In the meta-regression analysis, six variables cannot explain the 100% heterogeneity of the studies assessing by Chao1, Shannon index, Firmicutes, and Bacteroidetes. Depleted levels of Butyricicoccus, Coprococcus, Faecalibacterium, Fusicatenibacter, Romboutsia, and enriched levels of Eggerthella, Enterococcus, Flavonifractor, Holdemania, Streptococcus were consistently shared in depressive disorder. This systematic review and meta-analysis found that psychotropic medication and dietary habit may influence microbiota. There is reliable evidence for differences in the phylogenetic relationship in depressive disorder compared with controls, however, method of measurement and method of patient classification (symptom vs diagnosis based) may affect findings. Depressive disorder is characterized by an increase of pro-inflammatory bacteria, while anti-inflammatory butyrate-producing genera are depleted.

Microbiota-derived butyrate dampens linaclotide stimulation of the guanylate cyclase C pathway in patient-derived colonoids

BACKGROUND & AIMS

Disorders of gut-brain interaction (DGBI) are complex conditions that result in decreased quality of life and a significant cost burden. Linaclotide, a guanylin cyclase C (GCC) receptor agonist, is approved as a DGBI treatment. However, its efficacy has been limited and variable across DGBI patients. Microbiota and metabolomic alterations are noted in DGBI patients, provoking the hypothesis that the microbiota may impact the GCC response to current therapeutics.

METHODS

Human-derived intestinal organoids were grown from pediatric DGBI, non-IBD colon biopsies (colonoids). Colonoids were treated with 250 nM linaclotide and assayed for cGMP to develop a model of GCC activity. Butyrate was administered to human colonoids overnight at a concentration of 1 mM. Colonoid lysates were analyzed for cGMP levels by ELISA. For the swelling assay, colonoids were photographed pre- and post-treatment and volume was measured using ImageJ. Principal coordinate analyses (PCoA) were performed on the Bray-Curtis dissimilarity and Jaccard distance to assess differences in the community composition of short-chain fatty acid (SCFA) producing microbial species in the intestinal microbiota from pediatric patients with IBS and healthy control samples.

KEY RESULTS

Linaclotide treatment induced a significant increase in [cGMP] and swelling of patient-derived colonoids, demonstrating a human in vitro model of linaclotide-induced GCC activation. Shotgun sequencing analysis of pediatric IBS patients and healthy controls showed differences in the composition of commensal SCFA-producing bacteria. Butyrate exposure significantly dampened linaclotide-induced cGMP levels and swelling in patient-derived colonoids.

CONCLUSIONS & INFERENCES

Patient-derived colonoids demonstrate that microbiota-derived butyrate can dampen human colonic responses to linaclotide. This study supports incorporation of microbiota and metabolomic assessment to improve precision medicine for DGBI patients.

Association between microbiome and the development of adverse posttraumatic neuropsychiatric sequelae after traumatic stress exposure

Patients exposed to trauma often experience high rates of adverse post-traumatic neuropsychiatric sequelae (APNS). The biological mechanisms promoting APNS are currently unknown, but the microbiota-gut-brain axis offers an avenue to understanding mechanisms as well as possibilities for intervention. Microbiome composition after trauma exposure has been poorly examined regarding neuropsychiatric outcomes. We aimed to determine whether the gut microbiomes of trauma-exposed emergency department patients who develop APNS have dysfunctional gut microbiome profiles and discover potential associated mechanisms. We performed metagenomic analysis on stool samples (n = 51) from a subset of adults enrolled in the Advancing Understanding of RecOvery afteR traumA (AURORA) study. Two-, eight- and twelve-week post-trauma outcomes for post-traumatic stress disorder (PTSD) (PTSD checklist for DSM-5), normalized depression scores (PROMIS Depression Short Form 8b) and somatic symptom counts were collected. Generalized linear models were created for each outcome using microbial abundances and relevant demographics. Mixed-effect random forest machine learning models were used to identify associations between APNS outcomes and microbial features and encoded metabolic pathways from stool metagenomics. Microbial species, including Flavonifractor plautii, Ruminococcus gnavus and, Bifidobacterium species, which are prevalent commensal gut microbes, were found to be important in predicting worse APNS outcomes from microbial abundance data. Notably, through APNS outcome modeling using microbial metabolic pathways, worse APNS outcomes were highly predicted by decreased L-arginine related pathway genes and increased citrulline and ornithine pathways. Common commensal microbial species are enriched in individuals who develop APNS. More notably, we identified a biological mechanism through which the gut microbiome reduces global arginine bioavailability, a metabolic change that has also been demonstrated in the plasma of patients with PTSD.

Identification of intestinal and fecal microbial biomarkers using a porcine social stress model

Understanding the relationships between social stress and the gastrointestinal microbiota, and how they influence host health and performance is expected to have many scientific and commercial implementations in different species, including identification and improvement of challenges to animal welfare and health. In particular, the study of the stress impact on the gastrointestinal microbiota of pigs may be of interest as a model for human health. A porcine stress model based on repeated regrouping and reduced space allowance during the last 4 weeks of the finishing period was developed to identify stress-induced changes in the gut microbiome composition. The application of the porcine stress model resulted in a significant increase in salivary cortisol concentration over the course of the trial and decreased growth performance and appetite. The applied social stress resulted in 32 bacteria being either enriched (13) or depleted (19) in the intestine and feces. Fecal samples showed a greater number of microbial genera influenced by stress than caecum or colon samples. Our trial revealed that the opportunistic pathogens Treponema and Clostridium were enriched in colonic and fecal samples from stressed pigs. Additionally, genera such as Streptococcus, Parabacteroides, Desulfovibrio, Terrisporobacter, Marvinbryantia, and Romboutsia were found to be enriched in response to social stress. In contrast, the genera Prevotella, Faecalibacterium, Butyricicoccus, Dialister, Alloprevotella, Megasphaera, and Mitsuokella were depleted. These depleted bacteria are of great interest because they synthesize metabolites [e.g., short-chain fatty acids (SCFA), in particular, butyrate] showing beneficial health benefits due to inhibitory effects on pathogenic bacteria in different animal species. Of particular interest are Dialister and Faecalibacterium, as their depletion was identified in a human study to be associated with inferior quality of life and depression. We also revealed that some pigs were more susceptible to pathogens as indicated by large enrichments of opportunistic pathogens of Clostridium, Treponema, Streptococcus and Campylobacter. Generally, our results provide further evidence for the microbiota-gut-brain axis as indicated by an increase in cortisol concentration due to social stress regulated by the hypothalamic-pituitary-adrenal axis, and a change in microbiota composition, particularly of bacteria known to be associated with pathogenicity and mental health diseases.

Distinct Effects of Non-absorbed Agents Rifaximin and Berberine on the Microbiota-Gut-Brain Axis in Dysbiosis-induced Visceral Hypersensitivity in Rats

Background/Aims

Irritable bowel syndrome (IBS) is accepted as a disorder of gut-brain interactions. Berberine and rifaximin are non-absorbed antibiotics and have been confirmed effective for IBS treatment, but there is still lack of direct comparison of their effects. This study aims to compare the effect of the 2 drugs on the alteration of gut-brain axis caused by gut microbiota from IBS patients.

Methods

Germ-free rats received fecal microbiota transplantation from screened IBS patients and healthy controls. After 14 days' colonization, rats were administrated orally with berberine, rifaximin or vehicle respectively for the next 14 days. The visceral sensitivity was evaluated, fecal microbiota profiled and microbial short chain fatty acids were determined. Immunofluorescence staining and morphological analysis were performed to evaluate microglial activation.

Results

Visceral hypersensitivity induced by IBS-fecal microbiota transplantation was relieved by berberine and rifaximin, and berberine increased sucrose preference rate. Microbial α-diversity were reduced by both drugs. Compared with rifaximin, berberine significantly changed microbial structure and enriched Lachnoclostridium. Furthermore, berberine but not rifaximin significantly increased fecal concentrations of acetate and propionate acids. Berberine restored the morphological alterations of microglia induced by dysbiosis, which may be associated with its effect on the expression of microbial gene pathways involved in peptidoglycan biosynthesis. Rifaximin affected neither the numbers of activated microglial cells nor the microglial morphological alterations.

Conclusions

Berberine enriched Lachnoclostridium, reduced the expression of peptidoglycan biosynthesis genes and increased acetate and propionate. The absence of these actions of rifaximin may explain the different effects of the drugs on microbiota-gut-brain axis.

"Sentinel or accomplice": gut microbiota and microglia crosstalk in disorders of gut-brain interaction

Abnormal brain-gut interaction is considered the core pathological mechanism behind the disorders of gut-brain interaction (DGBI), in which the intestinal microbiota plays an important role. Microglia are the "sentinels" of the central nervous system (CNS), which participate in tissue damage caused by traumatic brain injury, resist central infection and participate in neurogenesis, and are involved in the occurrence of various neurological diseases. With in-depth research on DGBI, we could find an interaction between the intestinal microbiota and microglia and that they are jointly involved in the occurrence of DGBI, especially in individuals with comorbidities of mental disorders, such as irritable bowel syndrome (IBS). This bidirectional regulation of microbiota and microglia provides a new direction for the treatment of DGBI. In this review, we focus on the role and underlying mechanism of the interaction between gut microbiota and microglia in DGBI, especially IBS, and the corresponding clinical application prospects and highlight its potential to treat DGBI in individuals with psychiatric comorbidities.

Reproducible microbiome composition signatures of anxiety and depressive symptoms

The gut microbiome is a significant contributor to mental health, with growing evidence linking its composition to anxiety and depressive disorders. Gut microbiome composition is associated with signs of anxiety and depression both in clinically diagnosed mood disorders and subclinically in the general population and may be influenced by dietary fibre intake and the presence of chronic pain. We provide an update of current evidence on the role of gut microbiome composition in depressive and anxiety disorders or symptoms by reviewing available studies. Analysing data from three independent cohorts (osteoarthritis 1 (OA1); n = 46, osteoarthritis 2 (OA2); n = 58, and healthy controls (CON); n = 67), we identified microbial composition signatures of anxiety and depressive symptoms at genus level and cross-validated our findings performing meta-analyses of our results with results from previously published studies. The genera Bifidobacterium (fixed-effect beta (95% CI) = -0.22 (-0.34, -0.10), p = 3.90e-04) and Lachnospiraceae NK4A136 group (fixed-effect beta (95% CI) = -0.09 (-0.13, -0.05), p = 2.53e-06) were found to be the best predictors of anxiety and depressive symptoms, respectively, across our three cohorts and published literature taking into account demographic and lifestyle covariates, such as fibre intake. The association with anxiety was robust in accounting for heterogeneity between cohorts and supports previous observations of the potential prophylactic effect of Bifidobacterium against anxiety symptoms.

The Role of the Adrenal-Gut-Brain Axis on Comorbid Depressive Disorder Development in Diabetes

Diabetic patients are more affected by depression than non-diabetics, and this is related to greater treatment resistance and associated with poorer outcomes. This increase in the prevalence of depression in diabetics is also related to hyperglycemia and hypercortisolism. In diabetics, the hyperactivity of the HPA axis occurs in parallel to gut dysbiosis, weakness of the intestinal permeability barrier, and high bacterial-product translocation into the bloodstream. Diabetes also induces an increase in the permeability of the blood-brain barrier (BBB) and Toll-like receptor 4 (TLR4) expression in the hippocampus. Furthermore, lipopolysaccharide (LPS)-induced depression behaviors and neuroinflammation are exacerbated in diabetic mice. In this context, we propose here that hypercortisolism, in association with gut dysbiosis, leads to an exacerbation of hippocampal neuroinflammation, glutamatergic transmission, and neuronal apoptosis, leading to the development and aggravation of depression and to resistance to treatment of this mood disorder in diabetic patients.

Gut Dysbiosis in Irritable Bowel Syndrome: A Narrative Review on Correlation with Disease Subtypes and Novel Therapeutic Implications

Irritable bowel syndrome (IBS) is a prevalent functional gastrointestinal disorder characterized by chronic abdominal pain and altered bowel habits. It can be subclassified in different subtypes according to the main clinical manifestation: constipation, diarrhea, mixed, and unclassified. Over the past decade, the role of gut microbiota in IBS has garnered significant attention in the scientific community. Emerging research spotlights the intricate involvement of microbiota dysbiosis in IBS pathogenesis. Studies have demonstrated reduced microbial diversity and stability and specific microbial alterations for each disease subgroup. Microbiota-targeted treatments, such as antibiotics, probiotics, prebiotics, synbiotics, fecal microbiota transplantation, and even diet, offer exciting prospects for managing IBS. However, definitive conclusions are hindered by the heterogeneity of these studies. Further research should focus on elucidating the mechanisms, developing microbiome-based diagnostics, and enabling personalized therapies tailored to an individual's microbiome profile. This review takes a deep dive into the microscopic world inhabiting our guts, and its implications for IBS. Our aim is to elucidate the complex interplay between gut microbiota and each IBS subtype, exploring novel microbiota-targeted treatments and providing a comprehensive overview of the current state of knowledge.

The Role of Bovine Kappa-Casein Glycomacropeptide in Modulating the Microbiome and Inflammatory Responses of Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder marked by chronic abdominal pain, bloating, and irregular bowel habits. Effective treatments are still actively sought. Kappa-casein glycomacropeptide (GMP), a milk-derived peptide, holds promise because it can modulate the gut microbiome, immune responses, gut motility, and barrier functions, as well as binding toxins. These properties align with the recognized pathophysiological aspects of IBS, including gut microbiota imbalances, immune system dysregulation, and altered gut barrier functions. This review delves into GMP's role in regulating the gut microbiome, accentuating its influence on bacterial populations and its potential to promote beneficial bacteria while inhibiting pathogenic varieties. It further investigates the gut microbial shifts observed in IBS patients and contemplates GMP's potential for restoring microbial equilibrium and overall gut health. The anti-inflammatory attributes of GMP, especially its impact on vital inflammatory markers and capacity to temper the low-grade inflammation present in IBS are also discussed. In addition, this review delves into current research on GMP's effects on gut motility and barrier integrity and examines the changes in gut motility and barrier function observed in IBS sufferers. The overarching goal is to assess the potential clinical utility of GMP in IBS management.

The Association between Gut Microbiota and Depression in the Japanese Population

Depression is a leading cause of disease worldwide. The association between gut microbiota and depression has barely been investigated in the Japanese population. We analyzed Iwaki health check-up data collected from 2017 to 2019 and constructed generalized linear mixed models. The independent variable was the relative abundance of each of the 37 gut microbiota genera that were reported to be associated with depression. The dependent variable was the presence of depression assessed by the Center for Epidemiologic Studies Depression Scale. Potential confounders, including grip strength, gender, height, weight, smoking, and drinking habits, were adjusted in the regression models. Nine genera's regression coefficients (Alistipes, Blautia, Coprococcus, Dorea, Faecalibacterium, Holdemania, Lactobacillus, Mitsuokella, and Oscillibacter) showed statistical significance after multiple comparisons adjustment. Among these nine gut bacteria genera, Alistipes, Blautia, Coprococcus, Dorea, Faecalibacterium, and Oscillibacter were reported to be associated with butyrate production in the intestine. Our results indicate that gut microbiotas may influence the depression condition of the host via the butyrate-producing process.

The butyrate-producing and spore-forming bacterial genus Coprococcus as a potential biomarker for neurological disorders

The host-intestinal microbiome interaction has gained much scientific attention in the past two decades, boosted by advances in DNA sequencing and cultivation techniques. An accumulating amount of evidence shows that gut microbes play crucial roles in gut homeostasis, immune system education, and are associated with quality-of-life indicators. Beneficial health factors are associated with the digestion of dietary fibres in the colon and the subsequent production of short-chain fatty acids, including acetate, propionate, and butyrate. Coprococcus is a butyrate-producing genus in the phylum Firmicutes, and its abundance is inversely correlated with several neuropsychological and neurodegenerative disorders. Case-control studies provide strong evidence of decreased abundance of Coprococcus spp. in depressed individuals. The species Coprococcus eutactus has the unique capacity to use two separate pathways for butyrate synthesis and has been found to be depleted in children with delayed language development and adults with Parkinson's disease. The combined literature on Coprococcus and the gut microbiota-brain axis points towards enhanced butyrate production and reduced colonisation of pathogenic clades as factors explaining its association with health effects. The genus Coprococcus is a promising candidate for a mental health biomarker and an interesting lead for novel dietary-based preventive therapies for specific neurological disorders.

Investigating the antidepressant effect of Ziyan green tea on chronic unpredictable mild stress mice through fecal metabolomics

Introduction

Some studies have shown the effectiveness of tea in reducing depression. Gut flora dysfunction is strongly associated with depression. The mechanism by which Ziyan green tea ameliorates depression is not clear.

Methods

In this study, we examined the impact of Ziyan green tea on mice exhibiting symptoms similar to depression. We specifically focused on the role of intestinal flora and its metabolites. We first established a chronic unpredictable mild stress (CUMS) mouse model to induce depressive symptoms and conducted behavioural tests, biochemical tests, and pathological tissue analysis. We also investigated gut microbiota changes by 16S rRNA sequencing and measured faecal metabolites in mice using UHPLC-MS/MS.

Results

The results showed that Ziyan green tea intervention improved depression-like behaviour, neurobiochemical factors, and reduced levels of pro-inflammatory factors in CUMS mice. Spearman's correlation analysis showed that different microbial communities (Corynebacterium, Faecalibaculum, Enterorhabdus, Desulfovibrio) correlation with differential metabolites (Cholic acid, Deoxycholic acid, etc.) and depression-related biochemical indicators (5-HT, DA, BDNF, IL-6, and TNF-α).

Discussion

In conclusion, our findings suggest that both low and high-dose interventions of Ziyan green tea have positive preventive effects on CUMS mice without dose dependence, partly because they mainly affect intestinal Purine Metabolism, Bile Acid Biosynthesis and Cysteine Metabolism in CUMS mice, thus stimulating brain 5-HT, DA and BDNF, and decreasing the inflammatory factors IL-6, TNF-α, activate the composition of intestinal flora, improve the intestinal flora environment and thus promote the production of intestinal metabolites, which can be used for depression treatment. It is suggested that Ziyan green tea may achieve an antidepressant effect through the gut-microbiota-brain axis.

Effect of prebiotics, probiotics, synbiotics on depression: results from a meta-analysis

Accumulating studies have shown the effects of gut microbiota management tools in improving depression. We conducted a meta-analysis to evaluate the effects of prebiotics, probiotics, and synbiotics on patients with depression. We searched six databases up to July 2022. In total, 13 randomized controlled trials (RCTs) with 786 participants were included. The overall results demonstrated that patients who received prebiotics, probiotics or synbiotics had significantly improved symptoms of depression compared with those in the placebo group. However, subgroup analysis only confirmed the significant antidepressant effects of agents that contained probiotics. In addition, patients with mild or moderate depression could both benefit from the treatment. Studies with a lower proportion of females reported stronger effects for alleviating depressive symptoms. In conclusion, agents that manipulate gut microbiota might improve mild-to-moderate depression. It is necessary to further investigate the benefits of prebiotic, probiotic and synbiotic treatments relative to antidepressants and follow up with individuals over a longer time before these therapies are implemented in clinical practice.

Gender Influences Gut Microbiota among Patients with Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal disease that affects approximately 11% of the general population. The gut microbiota, among other known factors, plays a substantial role in its pathogenesis. The study aimed to characterize the gut microbiota differences between patients with IBS and unaffected individuals, taking into account the gender aspect of the patients and the types of IBS determined on the basis of the Rome IV Criteria, the IBS-C, IBS-D, IBS-M, and IBS-U. In total, 121 patients with IBS and 70 unaffected individuals participated in the study; the derived stool samples were subjected to 16S rRNA amplicon sequencing. The gut microbiota of patients with IBS was found to be more diverse in comparison to unaffected individuals, and the differences were observed primarily among Clostridiales, Mogibacteriaceae, Synergistaceae, Coriobacteriaceae, Blautia spp., and Shuttleworthia spp., depending on the study subgroup and patient gender. There was higher differentiation of females' gut microbiota compared to males, regardless of the disease status. No correlation between the composition of the gut microbiota and the type of IBS was found. Patients with IBS were characterized by more diverse gut microbiota compared to unaffected individuals. The gender criterion should be considered in the characterization of the gut microbiota. The type of IBS did not determine the identified differences in gut microbiota.

Fibromyalgia and Irritable Bowel Syndrome Interaction: A Possible Role for Gut Microbiota and Gut-Brain Axis

Fibromyalgia (FM) is a serious chronic pain syndrome, characterised by muscle and joint stiffness, insomnia, fatigue, mood disorders, cognitive dysfunction, anxiety, depression and intestinal irritability. Irritable Bowel Syndrome (IBS) shares many of these symptoms, and FM and IBS frequently co-exist, which suggests a common aetiology for the two diseases. The exact physiopathological mechanisms underlying both FM and IBS onset are unknown. Researchers have investigated many possible causes, including alterations in gut microbiota, which contain billions of microorganisms in the human digestive tract. The gut-brain axis has been proven to be the link between the gut microbiota and the central nervous system, which can then control the gut microbiota composition. In this review, we will discuss the similarities between FM and IBS. Particularly, we will focus our attention on symptomatology overlap between FM and IBS as well as the similarities in microbiota composition between FM and IBS patients. We will also briefly discuss the potential therapeutic approaches based on microbiota manipulations that are successfully used in IBS and could be employed also in FM patients to relieve pain, ameliorate the rehabilitation outcome, psychological distress and intestinal symptoms.

Paeonia lactiflora Pall. Polysaccharide alleviates depression in CUMS mice by inhibiting the NLRP3/ASC/Caspase-1 signaling pathway and affecting the composition of their intestinal flora

ETHNOPHARMACOLOGICAL RELEVANCE

Paeonia lactiflora Pall. (PL) has been commonly used to de-stressing the liver and relieve depression in traditional Chinese medicine for over a thousand years. Recently, it has been widely used in studies on anti-depressant, anti-inflammatory and regulation of intestinal flora. However, the polysaccharide component has received less attention than the saponin component of PL.

AIM OF THE STUDY

This study aimed to elucidate the effects of Paeonia lactiflora polysaccharide (PLP) on depressive behavior in mice in a chronic unpredictable mild stress (CUMS) model and its possible action mechanisms.

MATERIALS AND METHODS

A model of chronic depression induced by the CUMS approach. Behavioral experiments were used to assess the success of the CUMS model and the therapeutic impact of PLP. Then the extent of damage to the colonic mucosa was assessed by H&E staining; the extent of neuronal damage was assessed by Nissler staining. Inflammatory factor expression was assessed at different sites in the mouse by enzyme-linked immunoassay (Elisa). The alterations of fecal microflora were detected by 16S rRNA gene sequencing. In the colonic tissues, NLRP3, ASC and Caspase-1 mRNA and protein levels detected by quantitative real-time PCR (qRT-PCR) and Western blot(WB).

RUSULTS

PLP can improve depressive behavior in CUMS mice, and colonic mucosal and neuronal damage. Elisa assay showed that PLP could reduce interleukin-1β (IL-1β), interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α) levels, and increase 5-Hydroxytryptamine(5-HT) levels in CUMS mice. 16S sequencing analysis showed that PLP could regulate the intestinal flora of CUMS mice and increase their species richness. In addition, PLP significantly inhibited NLRP3/ASC/Caspase-1 signalling pathways activation in the colonic tissues of CUMS mice.

CONCLUSIONS

PLP modulates depression-related intestinal ecological dysregulation, increases species richness, and inhibits inflammatory factors levels and NLRP3 inflammasome activation to reduce colonic mucosal and neurons damage, thereby improving depression-like behavior and neurotransmitter release in CUMS mice.

Assessing the relationship between gut microbiota and irritable bowel syndrome: a two-sample Mendelian randomization analysis

BACKGROUND

Growing evidence has suggested that gut microbiota is closely related to the risk of irritable bowel syndrome (IBS), but whether there is a causal effect remains unknown. We adopted a Mendelian randomization (MR) approach to evaluate the potential causal relationships between gut microbiota and the risk of IBS.

METHODS

Genetic instrumental variables for gut microbiota were identified from a genome-wide association study (GWAS) of 18,340 participants. Summary statistics of IBS were drawn from a GWAS including 53,400 cases and 433,201 controls. We used the inverse-variance weighted (IVW) method as the primary analysis. To test the robustness of our results, we further performed the weighted-median method, MR-Egger regression, and MR pleiotropy residual sum and outlier test. Finally, reverse MR analysis was performed to evaluate the possibility of reverse causation.

RESULTS

We identified suggestive associations between three bacterial traits and the risk of IBS (odds ratio (OR): 1.08; 95% confidence interval (CI): 1.02, 1.15; p = 0.011 for phylum Actinobacteria; OR: 0.95; 95% CI: 0.91, 1.00; p = 0.030 for genus Eisenbergiella and OR: 1.10; 95% CI: 1.03, 1.18; p = 0.005 for genus Flavonifractor). The results of sensitivity analyses for these bacterial traits were consistent. We did not find statistically significant associations between IBS and these three bacterial traits in the reverse MR analysis.

CONCLUSIONS

Our systematic analyses provide evidence to support a potential causal relationship between several gut microbiota taxa and the risk of IBS. More studies are required to show how the gut microbiota affects the development of IBS.

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.

Gut microbiota and irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder that poses a significant health concern. Although its etiology remains unknown, there is growing evidence that gut dysbiosis is involved in the development and exacerbation of IBS. Previous studies have reported altered microbial diversity, abundance, and composition in IBS patients when compared to controls. However, whether dysbiosis or aberrant changes in the intestinal microbiota can be used as a hallmark of IBS remains inconclusive. We reviewed the literatures on changes in and roles of intestinal microbiota in relation to IBS and discussed various gut microbiota manipulation strategies. Gut microbiota may affect IBS development by regulating the mucosal immune system, brain-gut-microbiome interaction, and intestinal barrier function. The advent of high-throughput multi-omics provides important insights into the pathogenesis of IBS and promotes the development of individualized treatment for IBS. Despite advances in currently available microbiota-directed therapies, large-scale, well-organized, and long-term randomized controlled trials are highly warranted to assess their clinical effects. Overall, gut microbiota alterations play a critical role in the pathophysiology of IBS, and modulation of microbiota has a significant therapeutic potential that requires to be further verified.

Behavioral phenotype, intestinal microbiome, and brain neuronal activity of male serotonin transporter knockout mice

The serotonin transporter (5-HTT) plays a critical role in the regulation of serotonin neurotransmission. Mice genetically deficient in 5-HTT expression have been used to study the physiological functions of 5-HTT in the brain and have been proposed as a potential animal model for neuropsychiatric and neurodevelopmental disorders. Recent studies have provided evidence for a link between the gut-brain axis and mood disorders. However, the effects of 5-HTT deficiency on gut microbiota, brain function, and behavior remain to be fully characterized. Here we investigated the effects of 5-HTT deficiency on different types of behavior, the gut microbiome, and brain c-Fos expression as a marker of neuronal activation in response to the forced swim test for assessing depression-related behavior in male 5-HTT knockout mice. Behavioral analysis using a battery of 16 different tests showed that 5-HTT-/- mice exhibited markedly reduced locomotor activity, decreased pain sensitivity, reduced motor function, increased anxiety-like and depression-related behavior, altered social behavior in novel and familiar environments, normal working memory, enhanced spatial reference memory, and impaired fear memory compared to 5-HTT+/+ mice. 5-HTT+/- mice showed slightly reduced locomotor activity and impaired social behavior compared to 5-HTT+/+ mice. Analysis of 16S rRNA gene amplicons showed that 5-HTT-/- mice had altered gut microbiota abundances, such as a decrease in Allobaculum, Bifidobacterium, Clostridium sensu stricto, and Turicibacter, compared to 5-HTT+/+ mice. This study also showed that after exposure to the forced swim test, the number of c-Fos-positive cells was higher in the paraventricular thalamus and lateral hypothalamus and was lower in the prefrontal cortical regions, nucleus accumbens shell, dorsolateral septal nucleus, hippocampal regions, and ventromedial hypothalamus in 5-HTT-/- mice than in 5-HTT+/+ mice. These phenotypes of 5-HTT-/- mice partially recapitulate clinical observations in humans with major depressive disorder. The present findings indicate that 5-HTT-deficient mice serve as a good and valid animal model to study anxiety and depression with altered gut microbial composition and abnormal neuronal activity in the brain, highlighting the importance of 5-HTT in brain function and the mechanisms underlying the regulation of anxiety and depression.

A Systematic Review on the Association between Obesity and Mood Disorders and the Role of Gut Microbiota

Obesity is a complex health condition that increases the susceptibility to developing cardiovascular diseases, diabetes, and numerous other metabolic health issues. The effect of obesity is not just limited to the conditions mentioned above; it is also seen to have a profound impact on the patient’s mental state, leading to the onset of various mental disorders, particularly mood disorders. Therefore, it is necessary to understand the mechanism underlying the crosstalk between obesity and mental disorders. The gut microbiota is vital in regulating and maintaining host physiology, including metabolism and neuronal circuits. Because of this newly developed understanding of gut microbiota role, here we evaluated the published diverse information to summarize the achievement in the field. In this review, we gave an overview of the association between obesity, mental disorders, and the role of gut microbiota there. Further new guidelines and experimental tools are necessary to understand the microbial contribution to regulate a balanced healthy life.

Irritable Bowel Syndrome and the Gut Microbiome: A Comprehensive Review

Irritable Bowel Syndrome (IBS) is a functional disorder of the gastrointestinal tract characterized by abdominal pain and altered bowel habits. It has a prevalence of 10 to 25% in the United States and has a high disease burden, as evidenced by reduced quality of life, decreased work productivity and increased healthcare utilization and costs. IBS has been associated with several intra-intestinal and extra-intestinal conditions, including psychiatric comorbidities. Although the pathophysiology of IBS has not been fully elucidated, it involves dysregulation of communication between the brain and gut (brain–gut axis) which is associated with alterations in intestinal motility, gut permeability, visceral hypersensitivity and gut microbiota composition. The purpose of this article is to review the role the gut microbiota plays in the pathophysiology of IBS, understand factors that affect the gut microbiome and explore the microbiome as a target of treatment.

The Microbiota-Gut-Brain Axis: Psychoneuroimmunological Insights

There is growing interest in the role that the intestinal microbiota and the related autoimmune processes may have in the genesis and presentation of some psychiatric diseases. An alteration in the communication of the microbiota-gut-brain axis, which constitutes a communicative model between the central nervous system (CNS) and the gastro-enteric tract, has been identified as one of the possible causes of some psychiatric diseases. The purpose of this narrative review is to describe evidence supporting a role of the gut microbiota in psychiatric diseases and the impact of diet on microbiota and mental health. Change in the composition of the gut microbiota could determine an increase in the permeability of the intestinal barrier, leading to a cytokine storm. This could trigger a systemic inflammatory activation and immune response: this series of events could have repercussions on the release of some neurotransmitters, altering the activity of the hypothalamic-pituitary-adrenal axis, and reducing the presence of trophic brain factors. Although gut microbiota and psychiatric disorders seem to be connected, more effort is needed to understand the potential causative mechanisms underlying the interactions between these systems.

Relationship between Dietary Polyphenols and Gut Microbiota: New Clues to Improve Cognitive Disorders, Mood Disorders and Circadian Rhythms

Cognitive, mood and sleep disorders are common and intractable disorders of the central nervous system, causing great inconvenience to the lives of those affected. The gut-brain axis plays a vital role in studying neurological disorders such as neurodegenerative diseases by acting as a channel for a bidirectional information exchange between the gut microbiota and the nervous system. Dietary polyphenols have received widespread attention because of their excellent biological activity and their wide range of sources, structural diversity and low toxicity. Dietary intervention through the increased intake of dietary polyphenols is an emerging strategy for improving circadian rhythms and treating metabolic disorders. Dietary polyphenols have been shown to play an essential role in regulating intestinal flora, mainly by maintaining the balance of the intestinal flora and enhancing host immunity, thereby suppressing neurodegenerative pathologies. This paper reviewed the bidirectional interactions between the gut microbiota and the brain and their effects on the central nervous system, focusing on dietary polyphenols that regulate circadian rhythms and maintain the health of the central nervous system through the gut-brain axis.

Altered Gut Microbic Flora and Haemorrhoids: Could They Have a Possible Relationship?

To date, the exact pathophysiology of haemorrhoids is poorly understood. The different philosophies on haemorrhoids aetiology may lead to different approaches of treatment. A pathogenic theory involving a correlation between altered anal canal microflora, local inflammation, and muscular dyssynergia is proposed through an extensive review of the literature. Since the middle of the twentieth century, three main theories exist: (1) the varicose vein theory, (2) the vascular hyperplasia theory, and (3) the concept of a sliding anal lining. These phenomena determine changes in the connective tissue (linked to inflammation), including loss of organization, muscular hypertrophy, fragmentation of the anal subepithelial muscle and the elastin component, and vascular changes, including abnormal venous dilatation and vascular thrombosis. Recent studies have reported a possible involvement of gut microbiota in gut motility alteration. Furthermore, dysbiosis seems to represent the leading cause of bowel mucosa inflammation in any intestinal district. The alteration of the gut microbioma in the anorectal district could be responsible for haemorrhoids and other anorectal disorders. A deeper knowledge of the gut microbiota in anorectal disorders lays the basis for unveiling the roles of these various gut microbiota components in anorectal disorder pathogenesis and being conductive to instructing future therapeutics. The therapeutic strategy of antibiotics, prebiotics, probiotics, and fecal microbiota transplantation will benefit the effective application of precision microbiome manipulation in anorectal disorders.

Differences in gut microbiota associated with stress resilience and susceptibility to single prolonged stress in female rodents

Exposure to traumatic stress is a major risk factor for the development of neuropsychiatric disorders in a subpopulation of individuals, whereas others remain resilient. The determinants of resilience and susceptibility remain unclear. Here, we aimed to characterize the microbial, immunological, and molecular differences between stress-susceptible and stress-resilient female rats before and after exposure to a traumatic experience. Animals were randomly divided into unstressed controls (n = 10) and experimental groups (n = 16) exposed to Single Prolonged Stress (SPS), an animal model of PTSD. Fourteen days later, all rats underwent a battery of behavioral tests and were sacrificed the following day to collect different organs. Stool samples were collected before and after SPS. Behavioral analyses revealed divergent responses to SPS. The SPS treated animals were further subdivided into SPS-resilient (SPS-R) and SPS-susceptible (SPS-S) subgroups. Comparative analysis of fecal 16S sequencing before and after SPS exposure indicated significant differences in the gut microbial composition, functionality, and metabolites of the SPS-R and SPS-S subgroups. In line with the observed distinct behavioral phenotypes, the SPS-S subgroup displayed higher blood-brain barrier permeability and neuroinflammation relative to the SPS-R and/or controls. These results indicate, for the first time, pre-existing and trauma-induced differences in the gut microbial composition and functionality of female rats that relate to their ability to cope with traumatic stress. Further characterization of these factors will be crucial for understanding susceptibility and fostering resilience, especially in females, who are more likely than males to develop mood disorders.

Phytotherapy of mood disorders in the light of microbiota-gut-brain axis

BACKGROUND

Clinical research in natural product-based psychopharmacology has revealed a variety of promising herbal medicines that may provide benefit in the treatment of mild mood disorders, however failed to unambiguously indicate pharmacologically active constituents. The emerging role of the microbiota-gut-brain axis opens new possibilities in the search for effective methods of treatment and prevention of mood disorders.

PURPOSE

Considering the clinically proven effectiveness juxtaposed with inconsistencies regarding the indication of active principles for many medicinal plants applied in the treatment of anxiety and depression, the aim of the review is to look at their therapeutic properties from the perspective of the microbiota-gut-brain axis.

METHOD

A literature-based survey was performed using Scopus, Pubmed, and Google Scholar databases. The current state of knowledge regarding Hypericum perforatum, Valeriana officinalis, Piper methysticum, Passiflora incarnata, Humulus lupulus, Melissa officinalis, Lavandula officinalis, and Rhodiola rosea in terms of their antimicrobial activity, bioavailability, clinical effectiveness in depression/anxiety and gut microbiota - natural products interaction was summarized and analyzed.

RESULTS

Recent studies have provided direct and indirect evidence that herbal extracts and isolated compounds are potent modulators of gut microbiota structure. Additionally, some of the formed postbiotic metabolites exert positive effects and ameliorate depression-related behaviors in animal models of mood disorders. The review underlines the gap in research on natural products - gut microbiota interaction in the context of mood disorders.

CONCLUSION

Modification of microbiota-gut-brain axis by natural products is a plausible explanation of their therapeutic properties. Future studies evaluating the effectiveness of herbal medicine and isolated compounds in treating mild mood disorders should consider the bidirectional interplay between phytoconstituents and the gut microbiota community.

Food as Medicine: How to Influence the Microbiome and Improve Symptoms in Patients with Irritable Bowel Syndrome

PURPOSE OF REVIEW

This review highlights effects of dietary interventions on the gut microbiome and gastrointestinal symptoms in those with irritable bowel syndrome (IBS).

RECENT FINDINGS

It is hypothesized that gut dysbiosis factors into the pathophysiology of IBS. Various diets that influence the microbiome and intestinal physiology may have therapeutic properties. At present, data suggests that implementation of personalized dietary interventions have a mixed, but overall positive effect on the gut microbiome and IBS symptoms. The effect of dietary modification on the gut microbiome and GI symptoms in patients with IBS is a topic that has garnered interest due to the increasing prevalence of IBS and heightened awareness of the importance of gut health. The composition of the gut microbiome may be modulated by promoting fiber intake and implementation of exclusionary diets and dietary supplements; however, additional studies are needed to provide evidence-based guidelines in this patient population.