Associations of gut microbiota alterations with clinical, metabolic, and immune-inflammatory characteristics of chronic schizophrenia

Archaea methanogens are associated with cognitive performance through the shaping of gut microbiota, butyrate and histidine metabolism

The relationship between bacteria, cognitive function and obesity is well established, yet the role of archaeal species remains underexplored. We used shotgun metagenomics and neuropsychological tests to identify microbial species associated with cognition in a discovery cohort (IRONMET, n = 125). Interestingly, methanogen archaeas exhibited the strongest positive associations with cognition, particularly Methanobrevibacter smithii (M. smithii). Stratifying individuals by median-centered log ratios (CLR) of M. smithii (low and high M. smithii groups: LMs and HMs) revealed that HMs exhibited better cognition and distinct gut bacterial profiles (PERMANOVA p = 0.001), characterized by increased levels of Verrucomicrobia, Synergistetes and Lentisphaerae species and reduced levels of Bacteroidetes and Proteobacteria. Several of these species were linked to the cognitive test scores. These findings were replicated in a large-scale validation cohort (Aging Imageomics, n = 942). Functional analyses revealed an enrichment of energy, butyrate, and bile acid metabolism in HMs in both cohorts. Global plasma metabolomics by CIL LC-MS in IRONMET identified an enrichment of methylhistidine, phenylacetate, alpha-linolenic and linoleic acid, and secondary bile acid metabolism associated with increased levels of 3-methylhistidine, phenylacetylgluamine, adrenic acid, and isolithocholic acid in the HMs group. Phenylacetate and linoleic acid metabolism also emerged in the Aging Imageomics cohort performing untargeted HPLC-ESI-MS/MS metabolic profiling, while a targeted bile acid profiling identified again isolithocholic acid as one of the most significant bile acid increased in the HMs. 3-Methylhistidine levels were also associated with intense physical activity in a second validation cohort (IRONMET-CGM, n = 116). Finally, FMT from HMs donors improved cognitive flexibility, reduced weight, and altered SCFAs, histidine-, linoleic acid- and phenylalanine-related metabolites in the dorsal striatum of recipient mice. M. smithii seems to interact with the bacterial ecosystem affecting butyrate, histidine, phenylalanine, and linoleic acid metabolism with a positive impact on cognition, constituting a promising therapeutic target to enhance cognitive performance, especially in subjects with obesity.

Fecal microbiota transplantation from patients into animals to establish human microbiota-associated animal models: a scoping review

BACKGROUND

Fecal microbiota transplantation (FMT) from humans with specific medical conditions to animal models can demonstrate causality by inducing or exacerbating pathophenotypes, linking the gut microbiota to health outcomes.

METHODS

We conducted a scoping review searching MEDLINE, EMBASE, Scopus, and Web of Science through July 2024 to identify human noninfectious diseases studied using FMT in animal models, investigate FMT methodologies, and assess the feasibility of systematic reviews on the role of the microbiota in specific diseases.

RESULTS

From 605 reports of 489 studies, we found that inflammatory bowel diseases, irritable bowel syndrome, obesity, colorectal cancer, and depression were the most commonly studied, with cancer research focusing on immunotherapy non-responsiveness. In a random sample of studies, gastrointestinal outcomes were most frequently reported, with remarkably high rates (> 80%) of successful induction of disease-specific alterations for intestinal barrier function, gastrointestinal inflammation, circulating immune parameters, and fecal metabolites. Most studies used C57BL/6 mice and oral gavage administration, with recipients being either germ-free or antibiotic-pretreated. We created tables linking conditions with publications to facilitate future systematic reviews.

CONCLUSIONS

Although human-to-animal FMT studies cover diverse conditions, methodological heterogeneity and inconsistent reporting hinder comparability. Standardized protocols and guidelines are needed. For several conditions, sufficient literature exists to assess the role of the gut microbiota in human health through systematic reviews.

Appraising the Effects of Gut Microbiota on Insomnia Risk Through Genetic Causal Analysis

BackgroundInsomnia is a common neurological disorder that exhibits connections with the gut microbiota; however, the exact causal relationship remains unclear. MethodsWe conducted a Mendelian randomization (MR) study to systematically evaluate the causal effects of genus-level gut microbiota on insomnia risk in individuals of European ancestry. Summary-level datasets on gut microbiota were sourced from the genome-wide association study (GWAS) of MiBioGen, while datasets on insomnia were obtained from the GWAS of Neale Lab and FinnGen. The primary analytical approach used was the inverse-variance weighted (IVW) method, supplemented by MR-Egger, maximum likelihood, MR-robust adjusted profile score, and weighted median. Sensitivity analyses were conducted to ensure robustness. ResultsThe microbial taxa Enterorhabdus, Family XIII AD3011 group, Paraprevotella, and Lachnospiraceae UCG004 were associated with an increased risk of insomnia, whereas Coprococcus1, Coprobacter, Desulfovibrio, Flavonifractor, Olsenella, Odoribacter, and Oscillibacter were linked to a decreased risk. Regarding the insomnia phenotype characterized by trouble falling asleep, the microbial taxon Eisenbergiella was correlated with an increased risk, while Haemophilus and the Eubacterium brachy group were associated with a reduced risk. Furthermore, for the insomnia phenotype characterized by waking too early, the microbial taxa Family XIII UCG001, Lachnospiraceae FCS020 group, and Olsenella were linked to an increased risk, whereas the Eubacterium brachy group and Victivallis were associated with a lower risk. The results remained robust across all sensitivity analyses. ConclusionOur MR study identified multiple genus-level gut microbial taxa that may exhibit potential causal effects on insomnia from a genetic perspective. These findings provide evidence supporting the theory of the microbiota-gut-brain axis and offer new insights into potential prevention and therapeutic targets for insomnia.

Gut microbiome characteristics in individuals across different stages of schizophrenia spectrum disorders: A systematic review and meta-analysis

Schizophrenia (SCZ) is a complex neuropsychiatric disorder with unclear pathogenesis, limiting advances in early diagnosis and targeted interventions. Increasing evidence suggests that the gut microbiome contributed to SCZ pathophysiology, yet comprehensive characterization across illness stages remains lacking. This meta-analysis aimed to characterize gut microbial alterations across the SCZ spectrum disorder, including individuals at ultra-high risk for psychosis, first-episode psychosis (FEP) and chronic SCZ patients. A systematic search of 10 databases identified 91 case-control studies. Gut microbial outcome measures included relative abundance, alpha and beta diversity. Review Manager and R were used to analyze the data. The results showed that patients with SCZ exhibited significantly reduced alpha diversity, particularly in Shannon, Chao1, Observe and Evenness indices, compared to healthy controls. Beta diversity also differed significantly, with 88.5 % of studies reporting distinct microbial profiles across SCZ stages. Quantitative analysis revealed significantly increased relative abundance of Bacteroides and a decrease abundance of Bifidobacterium and Lactobacilli in FEP patients compared to healthy controls. Qualitative analysis further showed increasing abundance in Lactobacillus, Prevotella and Collinsella, but decreasing abundance in Faecalibacterium, Butyricicoccus, and Blautia in SCZ. Bifidobacterium exhibited stage-specific changes, decreasing in first-episode psychosis but increasing in chronic stages, while Bacteroides followed an opposite trajectory. Notably, Lactobacillus demonstrated an early upward tractor in high-risk individuals, persisting to chronic stages. This meta-analysis identified dynamic and consistent alterations in the gut microbial across the SCZ spectrum. These findings implicated the potentials of gut microbes as early indicators for identification and intervention of SCZ.

Targeting Neuroinflammation in Schizophrenia: A comprehensive review of mechanisms and pharmacological interventions

Schizophrenia is a complex psychiatric disorder traditionally linked to neurotransmitter imbalances, but growing evidence implicates neuroinflammation as a key factor in its pathogenesis. Core pathological features include aberrant microglial activation, elevated proinflammatory cytokines (e.g., IL-6, TNF-α), blood-brain barrier disruption, and oxidative stress, all contributing to neuronal dysfunction. Genetic, epigenetic, and neurodevelopmental abnormalities further intensify the link between neuroinflammation and clinical symptoms, including cognitive deficits and positive/negative symptoms. Therapeutically, anti-inflammatory strategies show promise: Non-steroidal anti-inflammatory drugs inhibit the cyclooxygenase pathway; minocycline modulates microglial activity; cytokine inhibitors regulate immune responses; and antioxidants and mitochondrial agents (e.g., N-acetylcysteine, omega-3 fatty acids) reduce oxidative damage. Emerging approaches such as cannabidiol and nanodelivery systems also demonstrate anti-inflammatory and neuroprotective potential. However, long-term safety, dosage optimization, and individual variability remain to be fully validated. Future research should integrate single-cell genomics, neuroimaging, and biomarker stratification to elucidate neuroinflammatory mechanisms and enable precise combination therapies. Combining immunomodulatory and neurotransmitter-based strategies may overcome the limitations of traditional antipsychotics and improve clinical outcomes.

Crocin drives intestinal microbiota variation in a rat model of Alzheimer's disease by reducing DKK3 expression

BACKGROUND

Alzheimer's disease (AD) is a common neurodegenerative disease. Targeting DKK3-mediated intestinal microbiota (IM) variation is a promising strategy to treat AD. Crocin can alter IM distribution and inhibit DKK3 expression. We aimed to explore whether Crocin alleviates AD by regulating DKK3-mediated IM variation.

METHODS

AD animal models were established by injecting Aβ1-42 into the brains of rats. Subsequently, AD rats were overexpressed with DKK3 and treated with Crocin. Morris water maze and passive avoidance tests were performed to assess the learning and memory abilities of the rats. The effect of Crocin on brain Aβ1-42 and p-tau levels, serum proinflammatory cytokine (TNF-α, IL-1β and IL-6) levels were analyzed. Then, hippocampal pathological damage of the rats was evaluated. Furthermore, DKK3, NeuN, Bax, BCL-2 expressions and GSK-3β phosphorylation were measured by immunohistochemistry and Western blot. Moreover, rat feces were collected for 16S rRNA sequencing.

RESULTS

Crocin improved learning and memory abilities of AD rats. Additionally, Crocin inhibited brain Aβ1-42 and p-tau levels, and serum proinflammatory cytokine levels for AD rats. It was also observed that Crocin attenuated hippocampal pathological damage, inhibited DKK3, Bax expressions and GSK-3β phosphorylation, but increased NeuN, BCL-2 expressions for AD rats. Notably, Crocin increased the α and β diversity of the IM in AD rats. However, DKK3 overexpression reversed these situations. Additionally, Crocin treatment led to an increase in Prevotellaceae_NK3B31_group, alongside reductions in Lachnospiraceae UCG-001 and Family_XIII_AD3011_group.

CONCLUSION

Crocin alleviated AD by regulating DKK3-mediated IM variation, suggesting that DKK3-mediated IM variation was a potential therapeutic target for AD.

Is There a Link Between Type 2 Diabetes Mellitus and Negative Symptoms in Schizophrenia? A Scoping Review

BACKGROUND/OBJECTIVES

Type 2 diabetes mellitus (T2DM) and impaired glucose metabolism are more prevalent among patients with schizophrenia than in the general population. The incidence of T2DM is associated with lifestyle factors that are often influenced by the negative symptoms of schizophrenia; comorbid T2DM may contribute to the reduced life expectancy observed in patients with schizophrenia. The existing literature reveals a scarcity of data regarding the potential causal relationship between T2DM and negative symptoms.

METHODS

A scoping review was conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) criteria, utilizing the PubMed database to identify clinical studies investigating the association between T2DM and the negative (but not cognitive) symptom domain of schizophrenia. Subsequently, the reference lists of these identified publications were searched.

RESULTS

Seventeen publications were included. There is evidence supporting the association between impaired glucose tolerance and increased negative symptoms in patients with first-episode psychosis, and several studies indicate that poorer glucose metabolic status correlates with more severe negative symptoms. Patients with T2DM and chronic schizophrenia, however, had milder negative symptom scores compared to those without diabetes, although this association was less pronounced than in early disease stages.

CONCLUSIONS

There is insufficient confirmatory evidence regarding the potential causality of T2DM on the negative symptoms of schizophrenia. Further, preferably prospective studies are needed to explore the complex and potentially causal relationship between T2DM and negative symptoms of schizophrenia. If T2DM were found to have a causal relationship with negative symptoms or to exacerbate pre-existing symptoms, it could lead to significant changes in therapeutic approaches for schizophrenia.

Immune cells mediated the causal relationship between the gut microbiota and anxiety disorders: A Mendelian randomization study

BACKGROUND

Studies have demonstrated that the gut microbiome-immune system-brain axis plays an important role in neurological disorders. Furthermore, recent studies have shown that the gut microbiota influences the occurrence and progression of anxiety disorders, with potential involvement of immune cells. We aimed to investigate the causal impact of gut microbiota on anxiety disorders and identify potential immune cell mediators.

METHODS

We made use of the summary statistics of 196 gut microbiota (MiBioGen consortium), 731 immune cells, and anxiety disorders (Medical Research Council Integrative Epidemiology Unit consortium), from the extensive genome-wide association studies to date. To determine the causal links between gut microbiota and anxiety disorders, we employed bidirectional Mendelian randomization (MR) analyses, and further employed 2-step MR to confirm potential mediating roles of immune cells. Moreover, we conducted rigorous sensitivity analyses to assess the heterogeneity, robustness, and horizontal pleiotropy of our findings.

RESULTS

Bi-directional MR analysis revealed that 11 gut microbiota species can affect anxiety disorders, while the reversed causal relationship was not existed. Mediation analysis revealed that three immune cells mediated the causal relationships between two gut microbiota species and anxiety disorders. Specifically, "CD39+ resting Treg %resting Treg", "CD39+ resting Treg % CD4 Treg", and "BAFF-R on IgD+ CD38- naive B cell" mediated the effects of class Melainabacteria on anxiety disorders, with mediating impacts of 0.000075, 0.000096, and 0.000263, representing 5.98 %, 7.67 %, and 21.01 % of the total effects, respectively. Additionally, "BAFF-R on IgD+ CD38- naive B cell" also mediated the effects of order Gastranaerophilales on anxiety disorders, with a mediating impact of 0.000266, accounting for 19.06 % of the total effects.

LIMITATIONS

The bacterial analysis was limited to genus level, overlooking species or strains. We used a lenient p-value threshold of p < 1.0 × 10-5 for instrumental variables, instead of the typical p < 5 × 10-8. Lastly, the GWAS focused on European participants, potentially limiting the generalizability of our findings to other ethnicities.

CONCLUSION

The risk of anxiety disorders has been linked causally to gut microbiota, with three distinct immunophenotypes acting as potential mediators in this relationship. The role of gut microbiota in modulating immune cells, thereby influencing anxiety disorders, may offer new therapeutic strategies and management approaches.

Causal estimation of the relationship between reproductive performance and the fecal bacteriome in cattle

BACKGROUND

The gut bacteriome influences host metabolic and physiological functions. However, its relationship with reproductive performance remains unclear. In this study, we evaluated the relationship between the gut bacteriome and reproductive performance in beef cattle, such as Japanese black heifers. Artificial insemination (AI) was performed after 300 days of age, and the number of AI required for pregnancy (AI number) was evaluated. The relationship of the fecal bacteriome at 150 and 300 days of age and reproductive performance was visualized using statistical structural equation modelling between traits based on four types of machine-learning algorithms (linear discriminant analysis, association analysis, random forest, and XGBoost).

RESULTS

The heifers were classified into superior (1.04 ± 0.04 cycles, n = 26) and inferior groups (3.87 ± 0.27 cycles, n = 23) according to the median frequency of AI. The fecal bacteria of the two groups were examined and compared using differential analysis, which demonstrated that the genera Rikenellaceae RC9 gut group and Christensenellaceae R-7 group were increased in the superior group. Subsequently, correlation analysis evaluated the interrelationships between bacteriomes, which demonstrated that the patterns exhibited distinct characteristics. Therefore, four machine-learning algorithms were employed to identify the distinctive factors between the two groups. The directed acyclic graphs carried out by DirectLiNGAM based on these extracted factors inferred that the family Erysipelotrichaceae and the genera Clostridium sensu stricto 1 and Family XIII AD3011 group at 150 days of age were strongly associated with an increase in AI number. Furthermore, a pathway involved in creatinine degradation (PWY-4722) at 150 days of age was related to an increase in AI number. However, bacteriomes and/or pathways at 300 days of age were not necessarily related to AI number.

CONCLUSIONS

In this study, a causal inference methodology was applied to investigate AI-dependent gut bacterial communities in pregnant cattle. These findings suggest that AI numbers, which are crucial for beef cattle production management, could be inferred from the fecal bacterial patterns nearly six months before the AI, rather than immediately before. This study provides a novel perspective of the gut environment and its role in reproductive performance.

Dysbiosis is associated with the behavioral phenotype observed in the triple-hit Wisket rat model of schizophrenia

Comorbidities between gastrointestinal diseases and psychiatric disorders have been widely reported, with the gut-brain axis implicated as a potential biological basis. Thus, dysbiosis may play an important role in the etiology of schizophrenia, which is barely detected. Triple-hit Wisket model rats exhibit various schizophrenia-like behavioral phenotypes. The present study aimed to compare the diversity and abundance of gut microbiota in Wisket model and control rats; furthermore, to correlate the microbial taxonomic profiles to indices of behavioral change. Tail-flick and Ambitus tests were used to assess acute heat pain sensitivity, and record exploration and locomotor activity along with motivation in young adult, control and Wisket model rats. Fecal microbiota composition was profiled by deep sequencing of bacterial 16S rRNA, and it was correlated to behavioral phenotype. Wisket rats exhibited significantly decreased pain sensitivity, lower locomotor activity and exploration, and impaired motivation compared with controls. No significant differences were observed in bacterial alpha diversity between the groups; however, clear differences in community structure were observed. Wisket rats showed decreases in several genera of Firmicutes and Saccharimonas, and increases in Bacteriodetes and Helicobacter phyla compared with controls. Correlation analysis revealed significant associations between the microbiota profile and the behavioral phenotype. This is the first demonstration that fecal microbiota composition is markedly altered in a triple-hit schizophrenia rat model, suggesting the contribution of the microbiota-gut-brain axis in the development of the schizophrenia-like behavioral phenotype. Thus targeting the gut microbiota may be a novel approach to treat such impairments.

The gut microbiota-immune-brain axis: Therapeutic implications

The microbiota-gut-brain axis has major implications for human health including gastrointestinal physiology, brain function, and behavior. The immune system represents a key pathway of communication along this axis with the microbiome implicated in neuroinflammation in health and disease. In this review, we discuss the mechanisms as to how the gut microbiota interacts with the brain, focusing on innate and adaptive immunity that are often disrupted in gut-brain axis disorders. We also consider the implications of these observations and how they can be advanced by interdisciplinary research. Leveraging an increased understanding of how these interactions regulate immunity has the potential to usher in a new era of precision neuropsychiatric clinical interventions for psychiatric, neurodevelopmental, and neurological disorders.

Elucidating the critical role of gut microbiota in the pathogenesis of bacterial pneumonia: insights from a Mendelian randomization analysis mediated by immune cell

BACKGROUND

The gut microbiota (GM) is recognized as a critical factor in sustaining overall health and regulating the immune system. However, the precise function of GM in the pathogenesis of bacterial pneumonia (BP), as well as the potential involvement of immune cells in these mechanisms, remains inadequately understood. Given that BP represents a substantial public health issue, elucidating the protective role of the gut microbiota against this condition is of considerable significance.

METHODS

We employed a bidirectional two-sample univariate Mendelian randomization (UVMR) approach to investigate the potential causal relationship between GM and BP. Furthermore, we integrated UVMR with multivariate Mendelian randomization (MVMR) analysis to assess the mediating role of immune cells in the pathway linking GM to BP risk. We additionally performed a reverse analysis to exclude GM that could exhibit a reverse causal relationship with BP.

RESULTS

Mendelian randomization (MR) analysis identified 18 GM significantly associated with BP, with 8 of these bacterial taxa linked to a reduced risk and 10 associated with an increased risk. Additionally, 50 immune cell traits exhibited suggestive associations with BP, with 27 immune cells potentially conferring protection and 23 immune cells potentially augmenting risk. Importantly, mediation MR analysis revealed that the protective effect of Clostridia on BP was predominantly mediated by the proportion of HLA DR + Natural Killer cells within CD3- lymphocytes (HLA DR + Natural Killer %CD3- lymphocytes) (Total effect IVW: OR = 0.724, 95% CI [0.552, 0.950], P = 0.020). The evaluation of the mediation effect revealed an effect size of -0.025 (95% CI [-0.061, -0.000]), with a mediation effect ratio of 7.143%.

CONCLUSION

The study identified specific components of the GM that confer a protective effect against BP. It revealed that the subsets of HLA DR + Natural Killer %CD3- lymphocytes are modulated by Clostridia, thereby enhancing the host's immune defense against BP.

Investigating the gut microbiome in schizophrenia cases versus controls: South Africa's version

Schizophrenia (SCZ) is a chronic and severe mental disorder with a complex molecular aetiology. Emerging evidence indicates a potential association between the gut microbiome and the development of SCZ. Considering the under-representation of African populations in SCZ research, this study aimed to explore the association between the gut microbiome and SCZ within a South African cohort. Gut microbial DNA was obtained from 89 participants (n = 41 SCZ cases; n = 48 controls) and underwent 16S rRNA (V4) sequencing. Data preparation and taxa classification were performed with the DADA2 pipeline in R studio followed by diversity analysis using QIIME2. Analysis of Compositions of Microbiomes with Bias Correction (ANCOM-BC) was utilised to identify differentially abundant taxa. No statistically significant differences were observed between SCZ patients and controls in terms of alpha-diversity (Shannon q = 0.09; Simpson q = 0.174) or beta-diversity (p = 0.547). Five taxa, namely Prevotella (p = 0.037), Faecalibacterium (p = 0.032), Phascolarctobacterium (p = 0.002), Dialister (p = 0.043), and SMB53 (p = 0.012), were differentially abundant in cases compared to controls, but this observation did not survive correction for multiple testing. This exploratory study suggests a potential association between the relative abundance of Prevotella, Faecalibacterium, Phascolarctobacterium, Dialister, and SMB53 with SCZ case-control status. Given the lack of significance after correcting for multiple testing, these results should be interpreted with caution. Mechanistic studies in larger samples are warranted to confirm these findings and better understand the association between the gut microbiome and SCZ.

Polysorbate 80 and carboxymethylcellulose: A different impact on epithelial integrity when interacting with the microbiome

The consumption of dietary emulsifiers, including polysorbate 80 (P80) and sodium carboxymethylcellulose (CMC), has raised safety concerns due to its interaction with the intestinal microbiome. This study demonstrated that increasing concentrations of P80 and CMC added to a dynamic four-stage gut microbiota model (BFBL gut simulator) altered the microbiome composition and impacted epithelial integrity in a dose-dependent manner. 16S rDNA amplicon-based metagenomics analysis revealed that these emulsifiers increased microbial groups with proinflammatory capacities while decreasing microbial taxa known to enhance barrier function. Increasing doses of P80 significantly decreased Bacteroides dorei and Akkermansia, taxa associated with anti-inflammatory potential, while increasing doses of CMC were linked to a higher abundance of Ruminococcus torques and Hungatella, which negatively impact barrier function. Both emulsifiers displayed a different impact on epithelial integrity when interacting with the microbiome. On one hand, supernatants from the BFBL simulator fed with P80 disrupted epithelial integrity to a lesser extent than the additive alone. On the other hand, both the microbiota and the supernatants from the BFBL simulator fed with CMC diminished the epithelial integrity, though the additive itself did not. These findings highlight the need to incorporate the gut microbiome in the risk assessment of these additives.

Should we consider microbiota-based interventions as a novel therapeutic strategy for schizophrenia? A systematic review and meta-analysis

Schizophrenia is a chronic psychiatric disorder characterized by a variety of symptoms broadly categorized into positive, negative, and cognitive domains. Its etiology is multifactorial, involving a complex interplay of genetic, neurobiological, and environmental factors, and its neurobiology is associated with abnormalities in different neurotransmitter systems. Due to this multifactorial etiology and neurobiology, leading to a wide heterogeneity of symptoms and clinical presentations, current antipsychotic treatments face challenges, underscoring the need for novel therapeutic approaches. Recent studies have revealed differences in the gut microbiome of individuals with schizophrenia compared to healthy controls, establishing an intricate link between this disorder and gastrointestinal health, and suggesting that microbiota-targeted interventions could help alleviate clinical symptoms. Therefore, this meta-analysis investigates whether gut microbiota manipulation can ameliorate psychotic outcomes in patients with schizophrenia receiving pharmacological treatment. Nine studies (n = 417 participants) were selected from 81 records, comprising seven randomized controlled trials and two open-label studies, all with a low risk of bias, included in this systematic review and meta-analysis. The overall combined effect size indicated significant symptom improvement following microbiota treatment (Hedges' g = 0.48, 95% CI = 0.09 to 0.88, p = 0.004, I2 = 62.35%). However, according to Hedges' g criteria, the effect size was small (approaching moderate), and study heterogeneity was moderate based on I2 criteria. This review also discusses clinical and preclinical studies to elucidate the neural, immune, and metabolic pathways by which microbiota manipulation, particularly with Lactobacillus and Bifidobacterium genera, may exert beneficial effects on schizophrenia symptoms via the gut-brain axis. Finally, we address the main confounding factors identified in our systematic review, highlight key limitations, and offer recommendations to guide future high-quality trials with larger participant cohorts to explore microbiome-based therapies as a primary or adjunctive treatment for schizophrenia.

Human-fecal microbiota transplantation in relation to gut microbiome signatures in animal models for schizophrenia: A scoping review

More recently, attention has turned to the putative role of gut microbiome (GMB) in pathogenesis, symptomatology, treatment response and/or resistance in schizophrenia (SCZ). It is foreseeable that fecal microbiota transplantation (FMT) from SCZ patients (SCZ-FMT) to germ-free mice could represent a suitable experimental framework for a better understanding of the relationship between GMB and SCZ. Thus, we set out to identify literature (i) characterizing the GMB in animal models of SCZ, and (ii) employing SCZ-FMT into rodents to model SCZ in relation to behavioral and molecular phenotypes. Five studies examining animal models of SCZ suggest distinct GMB composition compared to respective control groups, which was correlated with SCZ-like behavioral phenotypes. Four additional studies investigated SCZ-FMT into rodents in relation to behavioral phenotypes, including spontaneous hyperlocomotion, social deficits, exaggerated startle response, and cognitive impairments, resembling those observed in SCZ patients. Mice receiving SCZ-FMT showed altered neurochemical and metabolic pathways in the brain. Animal models of SCZ have shown altered GMB composition, whereas reported behavioral and neurochemical alterations following FMT from patients into rodents suggest early face and construct validity for SCZ-FMT animal models. However, the predictive validity of these models remains to be validated.

Gut Microbiome variation in patients with early-stage mild-to-moderate intracerebral hemorrhage: A pilot study exploring therapeutic targets

BACKGROUND

The significant morbidity and mortality rates of acute intracerebral hemorrhage (ICH) are well-known around the world. The link between gut microbiota and different types of strokes is becoming more studied. The goal of this study was to look at the relationships between intestinal flora and early-stage mild-to-moderate ICH (emICH), and to provide a new perspective for adjunctive treatment of emICH.

METHODS

Fecal samples from 100 participants with emICH (n=50) and healthy individuals (n=50) in this study were collected as well as analyzed utilizing 16S rRNA gene amplicon sequencing in order to characterize the gut microbial community.

RESULTS

Distinct microbial communities are present within each group, with emICH patients exhibiting a diminished diversity and uniformity in their microbial profiles. A notable shift in the gut microbiota composition of emICH patients has been observed, characterized by an upsurge in pro-inflammatory microbes belonging to the Euryarchaeota phylum and a concurrent decline in beneficial Bacteroidetes species. Concurrently, significant associations and patterns among operational taxonomic units (OTUs) were identified in emICH patients. A panel of biomarkers (WAL_1855D, Methanobrevibacter, Streptococcus, Bacteroides, Coprococcus, Lachnospira) has been effectively utilized to distinguish emICH patients from healthy individuals, with an area under the curve (AUC) of 0.845. Additionally, an analysis using the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway annotation uncovered several perturbed pathways in emICH patients, predominantly those related to metabolic processes and the inflammatory response. Moreover, predictive profiling of the microbiome's phenotypic traits suggests that emICH patients are likely to harbor a higher prevalence of Gram-negative bacteria and potential opportunistic pathogens compared to healthy controls.

CONCLUSIONS

The gut microbiota ecosystem of emICH patients is disrupted, characterized primarily by an increase in pro-inflammatory microbiota, elevated inflammatory signaling pathways, and metabolic dysregulation. Furthermore, microbiota modulation may be seen as a novel approach for the adjunctive treatment of emICH.

Comparative Analysis of Fecal Microbiota Between Adolescents with Early-Onset Psychosis and Adults with Schizophrenia

Studies of the composition of the gut microbiome have consistently shown that psychiatric disorders such as schizophrenia are associated with gut dysbiosis. However, research focusing on adolescents with early-onset psychosis remains limited. This study aimed to characterize the microbial communities and their potential metabolic functions in these populations. We identified that genera Desulfovibrionaceae_Incertae_Sedis, Paraprevotella, and several genera from the Oscillospiraceae family were significantly more abundant in patients with schizophrenia compared to non-psychotic individuals, while Dorea showed decreased levels in schizophrenia patients. Furthermore, patients with early-onset psychosis demonstrated a significant reduction in Staphylococcus abundance. Additionally, we observed an increase in Prevotellaceae Leyella and Prevotellaceae Incertae Sedis in patients receiving atypical antipsychotic treatment, along with a rise in the genus Weissella among those treated with sertraline. Conversely, patients on valproate treatment exhibited decreased levels of Desulfovibrionaceae Incertae Sedis, while showing increased levels of Kandleria and Howardella. Functional prediction analysis using PICRUSt2 revealed significant differences in the expression of key enzymes associated with fatty acid metabolism. Gene orthology analysis identified 10 differentially expressed genes in the early-onset psychosis and schizophrenia groups. Our findings underscore the importance of considering dietary factors, pharmacological treatments, and microbial composition in understanding the gut-brain axis in psychiatric disorders.

Causal effect of air pollution on the risk of brain health and potential mediation by gut microbiota

OBJECTIVE

Epidemiologic investigations have examined the correlation between air pollution and neurologic disorders and neuroanatomic structures. Increasing evidence underscores the profound influence of the gut microbiota on brain health. However, the existing evidence is equivocal, and a causal link remains uncertain. This study aimed: to determine if there is a causal connection between four key air pollutants, and 42 neurologic diseases, and 1325 distinct brain structures; and to explore the potential role of the gut microbiota in mediating these associations.

METHODS

Univariable Mendelian randomization (UVMR) and multivariable Mendelian randomization (MVMR) models were deployed to estimate the causal impact of air pollutants (including particulate matter [PM] with aerodynamic diameters <2.5 μm [PM2.5], and <10 μm [PM10]; PM2.5 absorbance; and nitrogen oxides [NOx]) on brain health through various Mendelian randomization methodologies. Lastly, the mediating role of the gut microbiome in the connections between the identified pollutants and neurologic diseases and brain structures was systematically examined.

RESULTS

The potential causal associations of PM2.5, PM2.5 absorbance, PM10, and exposure to NOx, with the risks of intracerebral hemorrhage, hippocampal perivascular spaces, large artery strokes, generalized epilepsy with tonic-clonic seizures, Alzheimer's disease, multiple sclerosis, anorexia nervosa, post-traumatic stress disorder (PTSD), and 420 brain structures, were investigated by UVMR analysis. Following adjustment for air pollutants by MVMR analysis, the genetic correlations between PM10 exposure and PTSD and multiple sclerosis remained significant and robust. Importantly, we observed that phylum Lentisphaerae may mediate the association between PM10 and multiple sclerosis. Additionally, PM2.5 absorbance with a greater risk of reduced thickness in the left anterior transverse temporal gyrus of Heschl and a decreased area in the right sulcus intermedius primus of Jensen, mediated by genus Senegalimassilia and genus Lachnospiraceae UCG010, respectively. Finally, we provided evidence that Clostridium innocuum and genus Ruminococcus2 may partly mediate the causal effect of NOx on altered thickness in the left transverse temporal cortex and area in the right sulcus intermedius primus of Jensen, respectively.

CONCLUSION

This study established a genetic connection between air pollution and brain health, implicating the gut microbiota as a potential mediator in the relationship between air pollution, neurologic disorders, and altered brain structures.

Integrated Microbiome and Metabolome Analysis Reveals Hypothalamic-Comorbidities Related Signatures in Craniopharyngioma

Craniopharyngioma (CP) is an intracranial tumor with high mortality and morbidity. Though biologically benign, CP will damage the hypothalamus, inducing comorbidities such as obesity, metabolic syndrome, and cognitive impairments. The roles of gut microbiome and serum metabolome in CP-associated hypothalamic comorbidities are aimed to be explored. Patients with CP are characterized by increased Shannon diversity, Eubacterium, Clostridium, and Roseburia, alongside decreased Alistipes and Bacteroides. CP-enriched taxa are positively correlated with dyslipidemia and cognitive decline, while CP-depleted taxa are negatively associated with fatty liver. Subsequent serum metabolomics identified notably up-regulated purine metabolism, and integrative analysis indicated an association between altered microbiota and elevated hypoxanthine. Phenotypic study and multi-omics analysis in the Rax-CreERT2::BrafV600E/+::PtenFlox/+ mouse model validated potential involvement of increased Clostridium and dysregulated purine metabolism in hypothalamic comorbidities. To further consolidate this, intervention experiments are performed and it is found that hypoxanthine co-variated with the severity of hypothalamic comorbidities and abundance of Clostridium, and induced dysregulated purine metabolism along with redox imbalance in target organs (liver and brain cortex). Overall, the study demonstrated the potential of increased Clostridium and up-regulated purine metabolism as signatures of CP-associated hypothalamic-comorbidities, and unveiled that elevated Clostridium, dysregulated purine metabolism, and redox imbalance may mediate the development and progression of CP-associated hypothalamic-comorbidities.

Unveiling the gut microbiota blueprint of schizophrenia: a multilevel omics approach

Background

Schizophrenia is a persistent incurable mental disorder and is characterized by the manifestation of negative emotions and behaviors with anxiety and depression, fear and insecurity, self-harm and social withdrawal. The intricate molecular mechanisms underlying this phenomenon remain largely elusive. Accumulating evidence points towards the gut microbiota exerting an influence on brain function via the gut-brain axis, potentially contributing to the development of schizophrenia. Therefore, the objective of this study is to delineate the gut microbial composition and metabolic profile of fecal samples from individuals with schizophrenia.

Methods

Liquid chromatography-mass spectrometry (LC-MS) and 16S ribosomal RNA (16S rRNA) gene sequencing were employed to analyze fecal metabolites and gut microbiota profiles in a cohort of 29 patients diagnosed with schizophrenia and 30 normal controls. The microbial composition of fecal samples was determined through the 16S rRNA gene sequencing, and microbial α-diversity and β-diversity indices were calculated. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were performed to analyze the distribution of samples. The metabolites and gut microbiota exhibiting differential expression were identified through the application of biological variance criteria. Co-occurrence analysis of bacteria and metabolites was conducted using the spearman's rank correlation coefficient and visualized in a circular layout with the Cytoscape software.

Results

The findings of the study indicated a lack of substantial evidence supporting significant disparities in α-diversity and β-diversity between individuals with schizophrenia and normal controls. In terms of metabolomics, a discernible pattern in sample distribution between the two groups was observed. Our analysis has revealed 30 bacterial species and 45 fecal metabolites that exhibited notable differences in abundance between individuals diagnosed with schizophrenia and normal controls. These alterations in multilevel omics have led to the development of a co-expression network associated with schizophrenia. The perturbed microbial genes and fecal metabolites consistently demonstrated associations with amino acid and lipid metabolism, which play essential roles in regulating the central nervous system.

Conclusion

Our results offered profound insights into the impact of imbalanced gut microbiota and metabolism on brain function in individuals with schizophrenia.

Dissecting the causal links between gut microbiome, immune traits and polyp using genetic evidence

Background

Previous research has demonstrated an association between gut microbiota and immune status with the development of several diseases. However, whether these factors contribute to polyps remains unclear. This study aims to use Mendelian randomization (MR) to investigate the causal relationship between gut microbiota and 4 types of polyps (nasal, gallbladder, colon, and gastric polyps), as well as to analyze the mediating role of immune traits.

Methods

This study utilized large-scale GWAS meta-analyses of gut microbiota (MiBioGen Consortium), 731 immune traits, and 4 types of polyps (one from the FinnGen Consortium and three from the NBDC Human Database). Univariate MR with the inverse variance weighted (IVW) estimation method was employed as the primary analytical approach. A two-step MR analysis was performed to identify potential mediating immune traits. Additionally, multivariable MR approach based on Bayesian model averaging (MR-BMA) was employed to further prioritize gut microbiota and immune traits associated with polyp development.

Results

Based on IVW method in univariate MR analysis, we identified 39 gut microbial taxa and 135 immune traits significantly causally associated with at least one type of polyp. For nasal polyps, 13 microbial taxa and 61 immune traits were causally associated. After false discovery rate (FDR) correction, CD3 on Central Memory CD8+ T cells and CD3 on CD4 regulatory T cells remained significant. MR-BMA identified 4 gut microbial taxa and 4 immune traits as high priority. For gallbladder polyps, 9 microbial taxa and 30 immune traits were causally associated. MR-BMA identified 8 microbial taxa and 6 immune traits as higher importance. For colon polyps, 6 microbial taxa and 21 immune traits were causally associated. MR-BMA identified 4 microbial taxa and 3 immune traits as higher importance. For gastric polyps, 12 microbial taxa and 33 immune traits were causally associated. Actinobacteria remained significant after FDR correction, and MR-BMA identified 7 gut microbial taxa and 6 immune traits as high priority. We identified 16 causal pathways with mediator directions consistent with the direction of gut microbiome-polyp association. Of these, 6 pathways were associated with the mechanism of nasal polyps, 1 with gallbladder polyps, 2 with colon polyps, and 7 with gastric polyps.

Conclusions

Our findings shed light on the causal relationships between gut microbiota, immune traits, and polyp development, underscoring the crucial roles of gut microbiota and immune status in polypogenesis. Furthermore, these findings suggest potential applications in polyp prevention, early screening, and the development of effective strategies to reduce polyp risk.

Causal associations between gut microbiota, circulating inflammatory proteins, and epilepsy: a multivariable Mendelian randomization study

Background

Previous studies have suggested that gut microbiota (GM) may be involved in the pathogenesis of epilepsy through the microbiota-gut-brain axis (MGBA). However, the causal relationship between GM and different epilepsy subtypes and whether circulating inflammatory proteins act as mediators to participate in epileptogenesis through the MGBA remain unclear. Therefore, it is necessary to identify specific GM associated with epilepsy and its subtypes and explore their underlying inflammatory mechanisms for risk prediction, personalized treatment, and prognostic monitoring of epilepsy.

Methods

We hypothesized the existence of a pathway GM-inflammatory proteins-epilepsy. We found genetic variants strongly associated with GM, circulating inflammatory proteins, epilepsy and its subtypes, including generalized and partial seizures, from large-scale genome-wide association studies (GWAS) summary data and used Multivariate Mendelian Randomization to explore the causal relationship between the three and whether circulating inflammatory proteins play a mediating role in the pathway from GM to epilepsy, with inverse variance weighted (IVW) method as the primary statistical method, supplemented by four methods: MR-Egger, weighted median estimator (WME), Weighted mode and Simple mode.

Results

16 positive and three negative causal associations were found between the genetic liability of GM and epilepsy and its subtypes. There were nine positive and nine negative causal associations between inflammatory proteins and epilepsy and its subtypes. Furthermore, we found that C-X-C motif chemokine 11 (CXCL11) levels mediated the causal association between Genus Family XIII AD3011 group and epilepsy.

Conclusion

Our study highlights the possible causal role of specific GM and specific inflammatory proteins in the development of epilepsy and suggests that circulating inflammatory proteins may mediate epileptogenesis through the MGBA.

Gut microbiome and schizophrenia: insights from two-sample Mendelian randomization

Growing evidence suggests a potential link between the gut microbiome and schizophrenia. However, it is unclear whether the gut microbiome is causally associated with schizophrenia. We performed two-sample bidirectional Mendelian randomization to detect bidirectional causal relationships between gut microbiome and schizophrenia. Summary genome-wide association study (GWAS) datasets of the gut microbiome from the MiBioGen consortium (n = 18,340) and schizophrenia (n = 130,644) were utilized in our study. Then a cohort of sensitive analyses was followed to validate the robustness of MR results. We identified nine taxa that exerted positive causal effects on schizophrenia (OR: 1.08-1.16) and six taxa that conferred negative causal effects on schizophrenia (OR: 0.88-0.94). On the other hand, the reverse MR analysis showed that schizophrenia may increase the abundance of nine taxa (OR: 1.03-1.08) and reduce the abundance of two taxa (OR: 0.94). Our study unveiled mutual causal relationships between gut microbiome and schizophrenia. The findings may provide evidence for the treatment potential of gut microbiomes in schizophrenia.

The Preventive Effect of Low-Molecular Weight Oyster Peptides on Lipopolysaccharide-Induced Acute Colitis in Mice by Modulating Intestinal Microbiota Communities

Colitis causes inflammation, diarrhoea, fever, and other serious illnesses, posing a serious threat to human health and safety. Current medications for the treatment of colitis have serious side effects. Therefore, the new strategy of creating a defence barrier for immune function by adding anti-inflammatory foods to the daily diet is worth advocating for. Low-molecular weight oyster peptides (LOPs) are a natural food with anti-inflammatory activity extracted from oysters, so intervention with LOPs is likely to be an effective preventive solution. The aim of this study was to investigate the preventive effect of LOPs on lipopolysaccharide (LPS)-induced acute colitis inflammation in mice and its underlying mechanism. The results showed that LOPs not only inhibited the colonic histopathy in mice induced by LPS-induced inflammation but also reduced the inflammatory response in the blood. In addition, LOPs significantly increased the number of beneficial bacteria (Alistipes, Mucispirillum, and Oscillospira), decreased the number of harmful bacteria (Coprobacillus, Acinetobater) in the intestinal microbiota, and further affected the absorption and utilisation of short-chain fatty acids (SCFAs) in the intestinal tract. In conclusion, dietary supplementation with LOPs is a promising health-promoting dietary supplement and nutraceutical for the prevention of acute colitis by reducing the inflammatory response and modulating the intestinal microbial communities.

Causal effects of gut microbiota on chalazion: a two-sample Mendelian randomization study

Purpose

To investigate the causal relationship between gut microbiota (GM) and chalazion through Mendelian randomization (MR) analysis.

Methods

GM-related genome-wide association studies (GWAS) were obtained from the International Consortium MiBioGen. Genetic data for chalazion were sourced from the MRC Integrative Epidemiology Unit (IEU) Open GWAS database. Five MR methods, including inverse variance weighted (IVW), were employed to estimate causal relationships. Cochran's Q test was used to detect heterogeneity, the MR-Egger intercept test and MR-PRESSO regression were utilized to detect horizontal pleiotropy, and the leave-one-out method was employed to validate data stability.

Results

We identified 1,509 single nucleotide polymorphisms (SNPs) across 119 genera as instrumental variables (IVs) (p < 1 × 10-5). According to the inverse variance weighted (IVW) estimate, the Family XIII AD3011 group (OR = 1.0018, 95% CI 1.0002-1.0035, p = 0.030) and Catenibacterium (OR = 1.0013, 95% CI 1.0002-1.0025, p = 0.022) were potentially associated with increased risk of chalazion. Conversely, Veillonella (OR = 0.9986, 95% CI 0.9974-0.9999, p = 0.036) appeared to provide protection against chalazion. There was no evidence of heterogeneity or pleiotropy.

Conclusion

This study uncovered the causal relationship between GM and chalazion, pinpointing Catenibacterium and Family XIII AD3011 group as potential risk contributors, while highlighting Veillonella as a protective factor. In-depth investigation into the potential mechanisms of specific bacteria in chalazion was essential for providing novel therapeutic and preventive strategies in the future.

Irisin alleviated the reproductive endocrinal disorders of PCOS mice accompanied by changes in gut microbiota and metabolomic characteristics

Introduction

Folliculogenesis and oligo/anovulation are common pathophysiological characteristics in polycystic ovary syndrome (PCOS) patients, and it is also accompanied by gut microbiota dysbiosis. It is known that physical activity has beneficial effects on improving metabolism and promoting ovulation and menstrual cycle disorder in PCOS patients, and it can also modulate the gastrointestinal microbiota in human beings. However, the mechanism remains vague. Irisin, a novel myokine, plays a positive role in the mediating effects of physical activity.

Methods

Mice were randomly divided into the control group, PCOS group and PCOS+irisin group. PCOS model was induced by dehydroepiandrosterone (DHEA) and high-fat diet (HFD). The PCOS+irisin group was given irisin 400μg/kg intraperitoneal injection every other day for 21 days. The serum sex hormones were measured by radioimmunoassay. Hematoxylin and Eosin (H&E) Staining and immunohistochemistry (IHC) were conducted on ovarian tissue. The feces microbiota and metabolomic characteristics were collected by 16S rRNA gene sequencing and liquid chromatography-mass spectrometry (LC-MS).

Results

In this study, we demonstrated that irisin supplementation alleviated reproductive endocrine disorders of PCOS mice, including estrous cycle disturbance, ovarian polycystic degeneration, and hyperandrogenemia. Irisin also improved the PCOS follicles dysplasia and ovulation disorders, while it had no significant effect on the quality of oocytes. Moreover, irisin could mitigate the decreased bacteria of Odoribacter and the increased bacteria of Eisenbergiella and Dubosiella in PCOS mice model. Moreover, irisin could alleviate the increased fecal metabolites: Methallenestril and PS (22:5(4Z,7Z,10Z,13Z,16Z)/ LTE4).

Conclusion

These results suggest that irisin may alleviate the status of PCOS mice model by modulating androgen-induced gut microbiota dysbiosis and fecal metabolites. Hence, our study provided evidence that irisin may be considered as a promising strategy for the treatment of PCOS.

The Bidirectional Relationship between Weight Gain and Cognitive Function in First-Episode Schizophrenia: A Longitudinal Study in China

Patients with schizophrenia often encounter notable weight gain during their illness, heightening the risk of metabolic diseases. While previous studies have noted a correlation between obesity and cognitive impairment in schizophrenia, many were cross-sectional, posing challenges in establishing a causal relationship between weight gain and cognitive function. The aim of this longitudinal study is to examine the relationship between weight gain and cognitive function in patients with first-episode schizophrenia (FES) during the initial 6-month antipsychotic treatments. Employing linear and logistic regression analyses, the study involved 337 participants. Significantly, baseline scores in processing speed (OR = 0.834, p = 0.007), working memory and attention (OR = 0.889, p = 0.043), and executive function (OR = 0.862, p = 0.006) were associated with clinically relevant weight gain (CRW, defined as an increase in body weight > 7%) at the 6-month endpoint. On the other hand, CRW correlated with improvements in the Brief Visuospatial Memory Test (p = 0.037). These findings suggest that patients with lower baseline cognitive performance undergo more substantial weight gain. Conversely, weight gain was correlated with cognitive improvements, particularly in the domain of visual learning and memory. This suggested a potential bidirectional relationship between weight gain and cognitive function in first-episode schizophrenia patients.