The Gut Microbiome in Psychosis From Mice to Men: A Systematic Review of Preclinical and Clinical Studies

Effects of Limosilactobacillus reuteri strains PTA-126787 and PTA-126788 on intestinal barrier integrity and immune homeostasis in an alcohol-induced leaky gut model

Intestinal barrier is a first line of defense that prevents entry of various harmful substances from the lumen into the systemic environment. Impaired barrier function with consequent translocation of harmful substances into systemic circulation ("leaky gut") is a central theme in many gastrointestinal, autoimmune, mental, and metabolic diseases. Probiotics have emerged as a promising strategy to maintain intestinal integrity and address "leaky gut". Using in silico, in vitro and avian in vivo analyses, we previously showed that two novel L. reuteri strains, PTA-126787 (L. reuteri 3630) and PTA-126788 (L. reuteri 3632), isolated from broiler chickens possess favorable safety profiles. Consistent with a recent study, here we show that L. reuteri 3630 and 3632 are phylogenetically similar to human L. reuteri strains. Daily administration of high doses of L. reuteri 3630 and 3632 to Sprague Dawley rats for 28 days was found to be safe with no adverse effects. More importantly, administration of L. reuteri 3630 and 3632 significantly reduced markers associated with alcohol-induced leaky gut, by downregulating inflammatory cytokines and upregulating anti-inflammatory cytokines in an alcohol model of leaky gut in mice. While L. reuteri 3630 cells and supernatant showed no activation, L. reuteri 3632 cells but not supernatant showed activation of AhR, a key transcription factor that regulates gut and immune homeostasis. L. reuteri 3630 is creamish white in morphology typical of Lactobacillus species and L. reuteri 3632 displays a unique orange pigmentation, which was stable even after passaging for 480 generations. We identified a rare polyketide biosynthetic gene cluster in L. reuteri 3632 that likely encodes for the orange-pigmented secondary metabolite. Similar to L. reuteri 3632 cells, the purified orange metabolite activated AhR. All together, these data provide evidence on the phylogenetic relatedness, safety, efficacy, and one of the likely mechanisms of action of L. reuteri 3630 and 3632 for potential probiotic applications to address "leaky gut" and associated pathologies in humans.

The Underlying Neurobiological Mechanisms of Psychosis: Focus on Neurotransmission Dysregulation, Neuroinflammation, Oxidative Stress, and Mitochondrial Dysfunction

Psychosis, defined as a set of symptoms that results in a distorted sense of reality, is observed in several psychiatric disorders in addition to schizophrenia. This paper reviews the literature relevant to the underlying neurobiology of psychosis. The dopamine hypothesis has been a major influence in the study of the neurochemistry of psychosis and in development of antipsychotic drugs. However, it became clear early on that other factors must be involved in the dysfunction involved in psychosis. In the current review, it is reported how several of these factors, namely dysregulation of neurotransmitters [dopamine, serotonin, glutamate, and γ-aminobutyric acid (GABA)], neuroinflammation, glia (microglia, astrocytes, and oligodendrocytes), the hypothalamic-pituitary-adrenal axis, the gut microbiome, oxidative stress, and mitochondrial dysfunction contribute to psychosis and interact with one another. Research on psychosis has increased knowledge of the complexity of psychotic disorders. Potential new pharmacotherapies, including combinations of drugs (with pre- and probiotics in some cases) affecting several of the factors mentioned above, have been suggested. Similarly, several putative biomarkers, particularly those related to the immune system, have been proposed. Future research on both pharmacotherapy and biomarkers will require better-designed studies conducted on an all stages of psychotic disorders and must consider confounders such as sex differences and comorbidity.

Comparison analysis of microbial agent and different compost material on microbial community and nitrogen transformation genes dynamic changes during pig manure compost

This study aimed to assess the impact of microbial agent and different compost material, on physicochemical parameters dynamic change, nitrogen-transfer gene/bacterial community interaction network during the pig manure composting. Incorporating a microbial agent into rice straw-mushroom compost reduced the NH3 and total ammonia emissions by 25.52 % and 14.41 %, respectively. Notably, rice straw-mushroom with a microbial agent reduced the total ammonia emissions by 37.67 %. NH4+-N and pH emerged as primary factors of phylum-level and genus-level microorganisms. Microbial agent increased the expression of narG, nirK, and nosZ genes. Rice straw-mushroom elevated the content of amoA, nirK, nirS, and nosZ genes. Alcanivorax, Luteimonas, Pusillimonas, Lactobacillus, Aequorivita, Clostridium, Moheibacter and Truepera were identified as eight core microbial genera during the nitrogen conversion process. This study provides a strategy for reducing ammonia emissions and analyzes the potential mechanisms underlying compost processes.

Dysregulation of Microbiota in Patients With First-Episode Psychosis Is Associated With Symptom Severity and Treatment Response

BACKGROUND

The gut microbiome has been implicated in the pathogenesis of mental disorders where the gut-brain axis acts as a bidirectional communication network.

METHODS

Herein, we investigated the compositional and functional differences of gut microbiome between patients with first-episode psychosis (FEP) (n = 26) and healthy control participants (n = 22) using whole-genome shotgun sequencing. In addition, we assessed the oral microbiome in patients with FEP (n = 13) and listed their taxonomic diversity.

RESULTS

Our findings suggest that there is a dysbiosis of gut microbiota in patients with FEP. Relative abundance of Bifidobacterium adolescentis, Prevotella copri, and Turicibacter sanguinis was markedly increased (linear discriminant analysis scores [log10] > 1, and Mann-Whitney U test; false discovery rate-adjusted p values < .05) in the FEP group compared with the healthy control participants. Pathway analysis indicated that several metabolic pathways, particularly deoxyribonucleotide biosynthesis, branched-chain amino acid biosynthesis, tricarboxylic acid cycle, and fatty acid elongation and biosynthesis, were dysregulated in the FEP group compared with the healthy control group. In addition, this preliminary study was able to identify specific gut microbes (at baseline) that were predictive of weight gain in the FEP group at a 1-year follow-up. Bacteroides dorei, Bifidobacterium adolescentis, Turicibacter sanguinis, Roseburia spp., and Ruminococcus lactaris were positively associated (eXtreme gradient boosting, XGBoost regression model, Shapley additive explanations, R2 = 0.82) with weight gain.

CONCLUSIONS

Our findings may suggest the involvement of gut microbiota in the pathogenesis of psychosis. The benefit of modulation of the gut microbiome in the treatment of psychotic disorders should be explored further.

Intricate role of intestinal microbe and metabolite in schizophrenia

BACKGROUND

The brain-gut axis has gained increasing attention due to its contribution to the etiology of various central nervous system disorders. This study aims to elucidate the hypothesis that schizophrenia is associated with disturbances in intestinal microflora and imbalance in intestinal metabolites. By exploring the intricate relationship between the gut and the brain, with the goal of offering fresh perspectives and valuable insights into the potential contribution of intestinal microbial and metabolites dysbiosis to the etiology of schizophrenia.

METHODS

In this study, we used a 16S ribosomal RNA (16S rRNA) gene sequence-based approach and an untargeted liquid chromatography-mass spectrometry-based metabolic profiling approach to measure the gut microbiome and microbial metabolites from 44 healthy controls, 41 acute patients, and 39 remission patients, to evaluate whether microbial dysbiosis and microbial metabolite biomarkers were linked with the severity of schizophrenic symptoms.

RESULTS

Here, we identified 20 dominant disturbances in the gut microbial composition of patients compared with healthy controls, with 3 orders, 4 families, 9 genera, and 4 species. Several unique bacterial taxa associated with schizophrenia severity. Compared with healthy controls, 145 unusual microflora metabolites were detected in the acute and remission groups, which were mainly involved in environmental information processing, metabolism, organismal systems, and human diseases in the Kyoto encyclopedia of genes and genomes pathway. The Sankey diagram showed that 4 abnormal intestinal and 4 anomalous intestinal microbial metabolites were associated with psychiatric clinical symptoms.

CONCLUSIONS

These findings suggest a possible interactive influence of the gut microbiota and their metabolites on the pathophysiology of schizophrenia.

Searching for Intrinsic Causality between Colonic Dysbiosis and Non-Ischemic Cardiomyopathy: A Mendelian Randomization-Based Analysis

Objective: Little is known about gut microbiota (GM) and cardiomyopathy. Their causal relationship was explored using two-sample Mendelian randomization (TSMR) performed by R software. Methods: The single nucleotide polymorphisms (SNPs) were further screened based on the genome-wide association studies (GWAS) of gut microbiota and cardiomyopathy obtained from an open database. TSMR was performed using an MR-Egger regression, simple estimator based on mode, weighted median method, inverse variance weighted (IVW), weighted estimator and CML-MA-BIC to explore the causal association. And the sensitivity analysis was carried out using an MR-Egger regression and the leave-one-out sensitivity test. Results: As for 211 GM taxa, IVW results confirmed that the class Actinobacteria (OR = 0.81, p = 0.021) and genus Coprobacter (OR = 0.85, p = 0.033) were protective factors for cardiomyopathy. The phylum Firmicutes (OR = 0.87, p < 0.01), family Acidaminococcaceae (OR = 0.89, p < 0.01), genus Desulfovibrio (OR = 0.92, p = 0.030) and genus Prevotella9 (OR = 0.93, p = 0.029) were protective factors for ischemic cardiomyopathy. The family Rhodospirillaceae (OR = 1.06, p = 0.036) and genus Turicibacter (OR = 1.09, p = 0.019) were risk factors for ischemic cardiomyopathy. The genus Olsenella (OR = 0.91, p = 0.032) was a protective factor for non-ischemic cardiomyopathy. The order Rhodospirillales (OR = 1.14, p = 0.024), family Rikenellaceae (OR = 1.21, p = 0.012) and genus Gordonibacter (OR = 1.12, p = 0.019) were risk factors for non-ischemic cardiomyopathy. The robustness of MR results was reflected in the heterogeneity (p > 0.05) and pleiotropy (p > 0.05) analyses. Conclusions: A potential causal relationship of cardiomyopathy with some GM taxa has been confirmed in the current study.

Gut and oral microbiome modulate molecular and clinical markers of schizophrenia-related symptoms: A transdiagnostic, multilevel pilot study

Although increasing evidence links microbial dysbiosis with the risk for psychiatric symptoms through the microbiome-gut-brain axis (MGBA), the specific mechanisms remain poorly characterized. In a diagnostically heterogeneous group of treated psychiatric cases and nonpsychiatric controls, we characterized the gut and oral microbiome, plasma cytokines, and hippocampal inflammatory processes via proton magnetic resonance spectroscopic imaging (1H-MRSI). Using a transdiagnostic approach, these data were examined in association with schizophrenia-related symptoms measured by the Positive and Negative Syndrome Scale (PANSS). Psychiatric cases had significantly greater heterogeneity of gut alpha diversity and an enrichment of pathogenic taxa, like Veillonella and Prevotella, in the oral microbiome, which was an accurate classifier of phenotype. Cases exhibited significantly greater positive, negative, and general PANSS scores that uniquely correlated with bacterial taxa. Strong, positive correlations of bacterial taxa were also found with cytokines and hippocampal gliosis, dysmyelination, and excitatory neurotransmission. This pilot study supports the hypothesis that the MGBA influences psychiatric symptomatology in a transdiagnostic manner. The relative importance of the oral microbiome in peripheral and hippocampal inflammatory pathways was highlighted, suggesting opportunities for probiotics and oral health to diagnose and treat psychiatric conditions.

Gut Microbiome Composition and Its Association with Sleep in Major Psychiatric Disorders

INTRODUCTION

Sleep disturbances are highly prevalent across most major psychiatric disorders. Alterations in the hypothalamic-pituitary-adrenal axis, neuroimmune mechanisms, and circadian rhythm disturbances partially explain this connection. The gut microbiome is also suspected to play a role in sleep regulation, and recent studies suggest that certain probiotics, prebiotics, synbiotics, and fecal microbiome transplantation can improve sleep quality.

METHODS

We aimed to assess the relationship between gut-microbiota composition, psychiatric disorders, and sleep quality in this cross-sectional, cross-disorder study. We recruited 103 participants, 63 patients with psychiatric disorders (major depressive disorder [n = 31], bipolar disorder [n = 13], psychotic disorder [n = 19]) along with 40 healthy controls. Sleep quality was assessed with the Pittsburgh Sleep Quality Index (PSQI). The fecal microbiome was analyzed using 16S rRNA sequencing, and groups were compared based on alpha and beta diversity metrics, as well as differentially abundant species and genera.

RESULTS

A transdiagnostic decrease in alpha diversity and differences in beta diversity indices were observed in psychiatric patients, compared to controls. Correlation analysis of diversity metrics and PSQI score showed no significance in the patient and control groups. However, three species, Ellagibacter isourolithinifaciens, Senegalimassilia faecalis, and uncultured Blautia sp., and two genera, Senegalimassilia and uncultured Muribaculaceae genus, were differentially abundant in psychiatric patients with good sleep quality (PSQI >8), compared to poor-sleep quality patients (PSQI ≤8).

CONCLUSION

In conclusion, this study raises important questions about the interconnection of the gut microbiome and sleep disturbances.

Emerging epigenetic dynamics in gut-microglia brain axis: experimental and clinical implications for accelerated brain aging in schizophrenia

Brain aging, which involves a progressive loss of neuronal functions, has been reported to be premature in probands affected by schizophrenia (SCZ). Evidence shows that SCZ and accelerated aging are linked to changes in epigenetic clocks. Recent cross-sectional magnetic resonance imaging analyses have uncovered reduced brain reserves and connectivity in patients with SCZ compared to typically aging individuals. These data may indicate early abnormalities of neuronal function following cyto-architectural alterations in SCZ. The current mechanistic knowledge on brain aging, epigenetic changes, and their neuropsychiatric disease association remains incomplete. With this review, we explore and summarize evidence that the dynamics of gut-resident bacteria can modulate molecular brain function and contribute to age-related neurodegenerative disorders. It is known that environmental factors such as mode of birth, dietary habits, stress, pollution, and infections can modulate the microbiota system to regulate intrinsic neuronal activity and brain reserves through the vagus nerve and enteric nervous system. Microbiota-derived molecules can trigger continuous activation of the microglial sensome, groups of receptors and proteins that permit microglia to remodel the brain neurochemistry based on complex environmental activities. This remodeling causes aberrant brain plasticity as early as fetal developmental stages, and after the onset of first-episode psychosis. In the central nervous system, microglia, the resident immune surveillance cells, are involved in neurogenesis, phagocytosis of synapses and neurological dysfunction. Here, we review recent emerging experimental and clinical evidence regarding the gut-brain microglia axis involvement in SCZ pathology and etiology, the hypothesis of brain reserve and accelerated aging induced by dietary habits, stress, pollution, infections, and other factors. We also include in our review the possibilities and consequences of gut dysbiosis activities on microglial function and dysfunction, together with the effects of antipsychotics on the gut microbiome: therapeutic and adverse effects, role of fecal microbiota transplant and psychobiotics on microglial sensomes, brain reserves and SCZ-derived accelerated aging. We end the review with suggestions that may be applicable to the clinical setting. For example, we propose that psychobiotics might contribute to antipsychotic-induced therapeutic benefits or adverse effects, as well as reduce the aging process through the gut-brain microglia axis. Overall, we hope that this review will help increase the understanding of SCZ pathogenesis as related to chronobiology and the gut microbiome, as well as reveal new concepts that will serve as novel treatment targets for SCZ.

The Effect of Probiotic Supplementation on the Gut-Brain Axis in Psychiatric Patients

The pathophysiology of several psychiatric diseases may entail disturbances in the hypothalamic-pituitary-adrenal (HPA) axis and metabolic pathways. Variations in how these effects present themselves may be connected to individual variances in clinical symptoms and treatment responses, such as the observation that a significant fraction of participants do not respond to current antipsychotic drugs. A bidirectional signaling pathway between the central nervous system and the gastrointestinal tract is known as the microbiota-gut-brain axis. The large and small intestines contain more than 100 trillion microbial cells, contributing to the intestinal ecosystem's incredible complexity. Interactions between the microbiota and intestinal epithelium can alter brain physiology and affect mood and behavior. There has recently been a focus on how these relationships impact mental health. According to evidence, intestinal microbiota may play a role in neurological and mental illnesses. Intestinal metabolites of microbial origin, such as short-chain fatty acids, tryptophan metabolites, and bacterial components that might stimulate the host's immune system, are mentioned in this review. We aim to shed some on the growing role of gut microbiota in inducing/manipulating several psychiatric disorders, which may pave the way for novel microbiota-based therapies.

Maternal Supplementation with N-Acetylcysteine Modulates the Microbiota-Gut-Brain Axis in Offspring of the Poly I:C Rat Model of Schizophrenia

The microbiota-gut-brain axis is a complex interconnected system altered in schizophrenia. The antioxidant N-acetylcysteine (NAC) has been proposed as an adjunctive therapy to antipsychotics in clinical trials, but its role in the microbiota-gut-brain axis has not been sufficiently explored. We aimed to describe the effect of NAC administration during pregnancy on the gut-brain axis in the offspring from the maternal immune stimulation (MIS) animal model of schizophrenia. Pregnant Wistar rats were treated with PolyI:C/Saline. Six groups of animals were studied according to the study factors: phenotype (Saline, MIS) and treatment (no NAC, NAC 7 days, NAC 21 days). Offspring were subjected to the novel object recognition test and were scanned using MRI. Caecum contents were used for metagenomics 16S rRNA sequencing. NAC treatment prevented hippocampal volume reduction and long-term memory deficits in MIS-offspring. In addition, MIS-animals showed lower bacterial richness, which was prevented by NAC. Moreover, NAC7/NAC21 treatments resulted in a reduction of proinflammatory taxons in MIS-animals and an increase in taxa known to produce anti-inflammatory metabolites. Early approaches, like this one, with anti-inflammatory/anti-oxidative compounds, especially in neurodevelopmental disorders with an inflammatory/oxidative basis, may be useful in modulating bacterial microbiota, hippocampal size, as well as hippocampal-based memory impairments.

Multi-Species Probiotic Strain Mixture Enhances Intestinal Barrier Function by Regulating Inflammation and Tight Junctions in Lipopolysaccharides Stimulated Caco-2 Cells

Although leaky gut syndrome is not recognized as an official diagnosis for human diseases, it is now believed that dysfunction of the cell barrier causes increased permeability of intestinal epithelial cells leading to this condition. Probiotics have been widely used to improve gut health, and studies have investigated the relevance of protecting the intestinal barrier by taking probiotic strains in vitro and in vivo. However, most studies have restricted the use of single or several probiotic strains and do not consider commercially available probiotic products composed of multi-species. In this study, we provide experimental evidence that a multi-species probiotic mixture composed of eight different strains and a heat-treated probiotic strain is effective in preventing leaky gut conditions. We employed an in vitro co-culture model system utilizing two different differentiated cell lines to mimic human intestinal tissue. The integrity of epithelial barrier function was protected by the preserving the occludin protein level and activating the AMPK signaling pathway, associated with tight junctions (TJs), through treatment with the probiotic strain mixture in Caco-2 cells. Moreover, we confirmed that application of the multi-species probiotic mixture reduced the expression of proinflammatory cytokine genes by inhibiting NFκB signaling pathway when artificial inflammation was induced in an in vitro co-culture model system. Finally, we proved that the epithelial permeability measured by trans-epithelial electrical resistance (TEER) was significantly decreased in the probiotic mixture treated cells, indicating that the integrity of the epithelial barrier function was not compromised. The multi-species probiotic strain mixture exhibited the protective effect on the integrity of intestinal barrier function via enhancing TJ complexes and reducing inflammatory responses in the human intestinal cells.

The Role of Gut Microbiota in Various Neurological and Psychiatric Disorders-An Evidence Mapping Based on Quantified Evidence

Methods

We searched PubMed, Cochrane Library, and Epistemonikos to identify systematic reviews and meta-analysis (SRs). We searched for neurological diseases and psychiatric disorders, including Alzheimer's disease (AD), attention deficit hyperactivity disorder (ADHD), amyotrophic lateral sclerosis (ALS), autism spectrum disorder (ASD), anorexia nervosa (AN), bipolar disorder (BD), eating disorder (ED), generalized anxiety disorder (GAD), major depressive disorder (MDD), multiple sclerosis (MS), obsessive compulsive disorder (OCD), Parkinson's disease (PD), posttraumatic stress disorder (PTSD), spinal cord injury (SCI), schizophrenia, and stroke. We used A Measurement Tool to Assess Systematic Reviews (AMSTAR-2) to evaluate the quality of included SRs. We also created an evidence map showing the role of gut microbiota in neurological diseases and the certainty of the evidence.

Results

In total, 42 studies were included in this evidence mapping. Most findings were obtained from observational studies. According to the AMSTAR-2 assessment, 21 SRs scored "critically low" in terms of methodological quality, 16 SR scored "low," and 5 SR scored "moderate." A total of 15 diseases have been investigated for the potential association between gut microbiome alpha diversity and disease, with the Shannon index and Simpson index being the most widely studied. A total of 12 diseases were investigated for potential link between beta diversity and disease. At the phylum level, Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria, and Verrucomicrobia were more researched. At the genus level, Prevotella, Coprococcus, Parabacteroides, Phascolarctobacterium, Escherichia Shigella, Alistipes, Sutteralla, Veillonella, Odoribacter, Faecalibacterium, Bacteroides, Bifidobacterium, Dialister, and Blautia were more researched. Some diseases have been found to have specific flora changes, and some diseases have been found to have common intestinal microbiological changes.

Conclusion

We found varied levels of evidence for the associations between gut microbiota and neurological diseases; some gut microbiota increased the risk of neurological diseases, whereas others showed evidence of benefit that gut microbiota might be promising therapeutic targets for such diseases.

Modeling methods for busulfan-induced oligospermia and asthenozoospermia in mice: a systematic review and meta-analysis

OBJECTIVE

Modeling methods for busulfan-induced oligoasthenozoospermia are controversial. We aimed to systematically review the modeling method of busulfan-induced oligospermia and asthenozoospermia, and analyze changes in various evaluation indicators at different busulfan doses over time.

METHODS

We searched the Cochrane Library, PubMed databases, Web of Science, the Chinese National Knowledge Infrastructure, and the Chinese Biomedical Literature Service System until April 9, 2022. Animal experiments of busulfan-induced spermatogenesis dysfunction were included and screened. The model mortality and parameters of the evaluation indicators were subjected to meta-analysis.

RESULTS

Twenty-nine animal studies were included (control/model: 669/1829). The mortality of mice increased with busulfan dose. Significant spermatogenesis impairment occurred within 5 weeks, regardless of busulfan dose (10-40 mg/kg). Testicular weight (weighted mean difference [WMD]: - 0.04, 95% CI: - 0.05, - 0.03), testicular index (WMD: - 2.10, 95% CI: - 2.43, - 1.76), and Johnsen score (WMD: - 4.67, 95% CI: - 5.99, - 3.35) were significantly decreased. The pooled sperm counts of the model group were reduced by 32.8 × 106/ml (WMD: - 32.8, 95% CI: - 44.34, - 21.28), and sperm motility decreased by 37% (WMD: - 0.37, 95% CI: - 0.47, - 0.27). Sperm counts decreased slightly (WMD: - 3.03, 95% CI: - 3.42, - 2.64) in an intratesticular injection of low-dose busulfan (4 - 6 mg/kg), and the model almost returned to normal after one seminiferous cycle.

CONCLUSION

The model using low-dose busulfan (10 - 20 mg/kg) returned to normal after 10 - 15 weeks. However, in some spermatogenesis cycles, testicular weight reduction and testicular spermatogenic function damage were not proportional to busulfan dose. Sperm counts and motility results in different studies had significant heterogeneity. Standard protocols for sperm assessment in animal models were needed to reduce heterogeneity between studies.

Gut Microbiome: A Brief Review on Its Role in Schizophrenia and First Episode of Psychosis

There is a growing body of evidence highlighting the role of gut microbiota as a biological basis of psychiatric disorders. The existing literature suggest that cognitive and emotional activities can be influenced by microbes through the microbiota–gut–brain axis and implies an association between alterations in the gut microbiome and several psychiatric conditions, such as autism, depression, bipolar disorder and psychosis. The aim of this review is to summarise recent findings and provide concise updates on the latest progress of the role of gut microbiota in the development and maintenance of psychiatric symptoms in schizophrenia and the first episode of psychosis. Despite the lack of consistent findings in regard to specific microbiome changes related to psychosis, the emerging literature reports significant differences in the gut microbiome of schizophrenic subjects compared to healthy controls and increasingly outlines the significance of an altered microbiome composition in the pathogenesis, development, symptom severity and prognosis of psychosis. Further human studies are, however, required, which should focus on identifying the drivers of microbiota changes in psychosis and establish the direction of causality between psychosis and microbiome alterations.

Sex Differences in Fish Oil and Olanzapine Effects on Gut Microbiota in Diet-Induced Obese Mice

Children are prescribed second-generation antipsychotic (SGA) medications, such as olanzapine (OLZ) for FDA-approved and "off-label" indications. The long-term impact of early-life SGA medication exposure is unclear. Olanzapine and other SGA medications are known to cause excessive weight gain in young and adult patients, suggesting the possibility of long-term complications associated with the use of these drugs, such as obesity, diabetes, and heart disease. Further, the weight gain effects of OLZ have previously been shown to depend on the presence of gut bacteria and treatment with OLZ, which shifts gut bacteria toward an "obesogenic" profile. The purpose of the current study was to evaluate changes in gut bacteria in adult mice following early life treatment with OLZ and being fed either a high-fat diet or a high-fat diet supplemented with fish oil, which has previously been shown to counteract gut dysbiosis, weight gain, and inflammation produced by a high-fat diet. Female and male C57Bl/6J mice were fed a high fat diet without (HF) or with the supplementation of fish oil (HF-FO) and treated with OLZ from postnatal day (PND) 37-65 resulting in four groups of mice: mice fed a HF diet and treated with OLZ (HF-OLZ), mice fed a HF diet and treated with vehicle (HF), mice fed a HF-FO diet and treated with OLZ (HF-FO-OLZ), and mice fed a HF-FO diet and treated with vehicle (HF-FO). Following euthanasia at approximately 164 days of age, we determined changes in gut bacteria populations and serum LPS binding protein, an established marker of gut inflammation and dysbiosis. Our results showed that male HF-FO and HF-FO-OLZ mice had lower body weights, at sacrifice, compared to the HF group, with a comparable body weight across groups in female mice. HF-FO and HF-FO-OLZ male groups also exhibited lower serum LPS binding protein levels compared to the HF group, with no differences across groups in female mice. Gut microbiota profiles were also different among the four groups; the Bacteroidetes-to-Firmicutes (B/F) ratio had the lowest value of 0.51 in the HF group compared to 0.6 in HF-OLZ, 0.9 in HF-FO, and 1.1 in HF-FO-OLZ, with no differences in female mice. In conclusion, FO reduced dietary obesity and its associated inflammation and increased the B/F ratio in male mice but did not benefit the female mice. Although the weight lowering effects of OLZ were unexpected, FO effects persisted in the presence of olanzapine, demonstrating its potential protective effects in male subjects using antipsychotic drugs.

Stress and the Role of the Gut-Brain Axis in the Pathogenesis of Schizophrenia: A Literature Review

Schizophrenia is a severe neuropsychiatric disorder, and its etiology remains largely unknown. Environmental factors have been reported to play roles in the pathogenesis of schizophrenia, and one of the major environmental factors identified for this disorder is psychosocial stress. Several studies have suggested that stressful life events, as well as the chronic social stress associated with city life, may lead to the development of schizophrenia. The other factor is the gut–brain axis. The composition of the gut microbiome and alterations thereof may affect the brain and may lead to schizophrenia. The main interest of this review article is in overviewing the major recent findings on the effects of stress and the gut–brain axis, as well as their possible bidirectional effects, in the pathogenesis of schizophrenia.

Cerebrospinal Fluid Inflammatory Cytokine Levels in Patients With Major Psychiatric Disorders: A Multiplex Immunoassay Study

Aim: Accumulating evidence suggests that neural inflammation plays an important role in psychiatric disorders. We aimed to identify inflammatory cytokines involved in the pathophysiology of such disorders by quantifying them in cerebrospinal fluid (CSF) samples from a large sample of patients with major psychiatric disorders and healthy controls.

Methods: The subjects included 94 patients with schizophrenia, 68 with bipolar disorder, 104 with major depressive disorder, and 118 healthy controls, matched for age, sex, and ethnicity (Japanese). Lumbar puncture was performed to collect these CSF samples. A multiplex immunoassay was then performed to measure CSF cytokine levels using magnetic on-bead antibody conjugation for 19 inflammatory cytokines.

Results: CSF interferon-β level was significantly higher in total psychiatric patients than in healthy controls (corrected p = 0.000029). In diagnostic group comparisons, CSF interferon-β level was significantly higher in patients with schizophrenia, or bipolar disorder (corrected p = 0.000047 or 0.0034) than in healthy controls.

Conclusion: We present novel evidence that CSF IFN-β level showed prominent statistical differences between psychiatric groups and healthy controls. This suggests IFN-β as the most important player among the 19 cytokines tested here in the inflammation-related pathophysiology of major psychiatric disorders.