The Brain-Gut-Microbiota Interplay in Depression: a key to design innovative therapeutic approaches

Characterization of Gut Microbiome Composition in Depression and Completed Suicide

Growing evidence supports a bidirectional relationship between the gut microbiome and mental health. This study investigated the association between gut microbiota, depression, and suicidal behavior by analyzing fecal samples from 35 individuals with varying depression levels and 36 completed suicide cases. Standardized psychometric assessments were used for depression evaluation. Analysis revealed significant taxonomic differences between groups, with increased abundance of Firmicutes, Clostridia, Lachnospiraceae, Blautia, and Dorea in suicide cases, which also positively correlated with depression severity. Metabolic pathway analysis demonstrated a notable dichotomy: suicide cases showed elevated pathways related to infection processes, inflammation, and antibiotic resistance, while the control group exhibited higher energy metabolism and vitamin synthesis pathways. The findings establish specific microbiome profiles associated with both depression symptoms and suicidal behavior, suggesting that gut dysbiosis may influence mental health through altered energy metabolism and inflammatory processes, potentially offering new perspectives for diagnostic and therapeutic approaches.

The effects of a semen cuscutae flavonoids-based antidepressant treatment on microbiome and metabolome in mice

Background

Depression is a prevalent psychiatric disorder and one of the leading causes of disability worldwide. Previous studies have shown that Semen Cuscutae flavonoids (SCFs) exert antidepressant effects by modulating the microbiota-neuroinflammation axis and ameliorating hippocampal metabolic disturbances. However, the impact of SCFs on gut microbiota and related metabolomics remains largely undefined. Given that the gut microbiota has been proven to play a significant role in the etiology of depression and serves as a promising target for its treatment in humans, this study aims to elucidate the antidepressant effects of SCFs and to investigate how they modulate microbial and metabolic pathways to alleviate depressive symptoms.

Materials and methods

Chronic unpredictable mild stress (CUMS)-induced mice were used as a depression model. The normal mice and CUMS-induced mice were treated with either vehicle or with SCFs. A range of standardized behavioral assays and physiological indicators were employed to evaluate the antidepressant effects of SCFs. Upon the confirmation of the effectiveness of the SCFs treatment, the composition, richness, and diversity of the fecal microbiota were assessed using 16S rRNA gene sequencing. Additionally, fecal metabolic profiling was analyzed using UHPLC-MS/MS-based metabolomics. Multivariate data analysis was subsequently performed to identify differential metabolites and characterize alterations in fecal metabolites. Furthermore, a correlation analysis between differential metabolites and key microbiota was conducted.

Results

SCFs significantly ameliorated depressive behaviors and the dysregulated diversity of fecal microbiota induced by CUMS. SCFs enhanced the gut microbiota structure in the CUMS group by increasing the Firmicutes/Bacteroidota ratio, significantly elevating the abundance of Firmicutes, Lactobacillus, Limosilactobacillus, and Actinobacteria while reducing the abundance of Bacteroidota and Bacteroides in CUMS-treated mice. Fecal metabolomics analyses revealed that SCFs could modulate metabolic pathways, including aldosterone synthesis and secretion, arachidonic acid metabolism, and primary bile acid biosynthesis.

Conclusions

Mice with depression induced by CUMS exhibited disturbances in both their gut microbiota and fecal metabolism. However, SCFs restored the balance of the microbial community and corrected metabolic disturbances in feces, exerting antidepressant effects through a multifaceted mechanism.

Multi-omics analysis reveals mechanisms of FMT in Enhancing antidepressant effects of SSRIs

OBJECTIVE

This study explores the behavioral and molecular biological impacts of Fecal Microbiota Transplantation (FMT) on depressive mice unresponsive to treatment with Selective Serotonin Reuptake Inhibitors (SSRIs).

METHODS

Healthy male C57BL/6 mice were used to establish a depression model through chronic restraint stress, treated with fluoxetine, and categorized into Response and Non-response groups. An FMT treatment was added to the Non-response group. Behavioral tests were conducted to assess symptoms of depression. The gut microbiome, plasma metabolites, and hippocampal tissue gene expression and function changes were analyzed using 16S rRNA gene sequencing, LC-MS, and RNA sequencing.

RESULTS

FMT significantly improved the depressive symptoms in SSRIs-resistant mice. There was a partial restoration in the diversity and structure of the gut microbiota in the FMT group. Compared to the Non-response group, significant changes were noted in the metabolomic profiles of the FMT group, identifying various differential metabolites. Functional annotations indicated that these metabolites are involved in multiple metabolic pathways. In the Non-response group, certain gene expression levels were significantly restored. GO and KEGG enrichment analyses revealed that these differential genes mainly involve cytokine activity, receptor signaling regulation, and NOD-like receptor signaling pathways. Joint analysis suggested that FMT may exert its effects through an increase in the abundance of g__Paraprevotella, leading to decreased baicalin content and increased Tal2 expression.

CONCLUSION

FMT has potential in improving depressive symptoms unresponsive to SSRIs treatment. Its mechanism may be related to the modulation of the gut microbiota and its metabolites, subsequently affecting gene expression.

The Role of Mitochondrial Dysfunction-Mediated Changes in Immune Cytokine Expression in the Pathophysiology and Treatment of Major Depressive Disorder

Recent studies have demonstrated an association between major depressive disorder (MDD) and both mitochondrial dysfunction and alterations in pro-inflammatory cytokine expression, suggesting that such changes may be key drivers of MDD pathogenesis. Mechanistically, changes in mitochondrial function are related to endoplasmic reticulum stress, reactive oxygen species production, oxidative phosphorylation, apoptosis, and disrupted calcium ion homeostasis, all of which trigger the activation of signaling cascades that affect the expression of pro-inflammatory cytokines, including tumor necrosis factor alpha, interleukin 1, interleukin 6, and interferons. Certain factors present in the gut microbiota ecosystem can influence communication between microorganisms and the brain through the neuroendocrine, immune, and autonomic nervous systems, thereby altering mitochondrial function and cytokine production. This review article explores the means through which mitochondria regulate immune cytokine expression and the role of mitochondrial dysfunction in the pathogenesis and treatment of MDD to provide new perspectives for the diagnosis of this disease and the development of novel therapeutic interventions with greater efficacy and improved safety profiles.

Gut microbiota and their metabolites in the immune response of rheumatoid arthritis: Therapeutic potential and future directions

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by persistent joint inflammation, damage, and loss of function. In recent years, the role of gut microbiota and its metabolites in immune regulation has attracted increasing attention. The gut microbiota influences the host immune system's homeostasis through various mechanisms, regulating the differentiation, function, and immune tolerance of immune cells. Dysbiosis of the gut microbiota in RA patients is closely associated with abnormal activation of immune cells and excessive secretion of inflammatory cytokines. Metabolites produced by the gut microbiota, such as short-chain fatty acids (SCFAs), tryptophan metabolites, bile acids, and amino acid metabolites, play a critical role in immune responses, regulating the functions of immune cells like T cells, B cells, and macrophages, and inhibiting the release of pro-inflammatory cytokines. Restoring the balance of the gut microbiota and optimizing the production of metabolic products may become a new strategy for RA treatment. This review discusses the role of gut microbiota and its metabolites in the immune response of RA, exploring how they influence the immunopathological process of RA through the regulation of immune cells and key immune factors. It also provides a theoretical basis for future therapeutic strategies based on gut microbiota modulation.

Adenosine regulates depressive behavior in mice with chronic social defeat stress through gut microbiota

Major depressive disorder (MDD) is recognized as the most prevalent affective disorder worldwide. Metagenomic studies increasingly support a critical role for dysbiosis of gut microbiota in the development of depression. Previous studies have demonstrated that adenosine alleviates gut dysbiosis, suggesting that elevating adenosine levels could be a novel intervention for MDD; however, the mechanisms underlying this effect remain unclear. This study utilized 16S rRNA gene sequencing, fecal microbiota transplantation (FMT) and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) to test the hypothesis that increased adenosine alleviates depressive behaviors in male mice subjected to chronic social defeat stress (CSDS) through alterations to gut microbiota. The data showed that depression-susceptible (SUS) mice exhibited gut dysbiosis, and FMT from SUS mice increased depression-like behaviors in healthy recipients. In SUS mice, adenosine supplementation ameliorated both depression-like behaviors and abnormalities in gut microbiota, and co-administration of probiotics and adenosine not only mitigated depression-like behaviors but also enhanced gut barrier integrity. By including 83 depressed adolescents and 67 healthy controls, this study found that the level of short-chain fatty acids (SCFAs) in the depression group was reduced, this finding parallels reductions seen in SUS mice and in recipient mice after FMT from SUS donors. Conversely, supplementation with either adenosine or probiotics led increased SCFAs concentrations in the serum of SUS mice. These findings suggest that adenosine may alleviate depression-like behaviors in CSDS mice by modulating the gut microbiota. This effect is likely associated with increased serum SCFAs, metabolites produced by the gut microbiota, following adenosine supplementation. This article is part of the Special Issue on "Personality Disorders".

Association of probiotics, prebiotics, synbiotics or yogurt supplement with prevalence and all-cause mortality of depression: NHANES 2005-2016

BACKGROUND

A growing body of studies revealed that enteric dysbacteriosis could result in depression via the "gut-microbiota-brain axis" (GMBA). Whether probiotics, prebiotics, and synbiotics supplements could lessen the risk of depression is a topic attracting attention. This research was conducted to evaluate the relationship between probiotics, prebiotics, synbiotics, or yogurt supplements and depression with large cross-sectional data.

METHODS

All data in our research was sourced from the National Health and Nutrition Examination Survey (NHANES) (2005-2016). Probiotics, prebiotics, synbiotics, and yogurt supplements were identified using Food Frequency Questionnaire (FFQ) and Dietary Supplement Use 30-Day (DSQ). We employed the Patient Health Questionnaire (PHQ-9) for evaluating depression. Logistic regression and the Kaplan-Meier curve were performed to examine the correlation between the supplements and depression, as well as mortality.

RESULTS

A total of 17,745 adult participants were selected. The participants who supplemented probiotics, prebiotics, synbiotics, or yogurt products in the last 30 days showed a significantly lower depression rate compared with those who didn't. Specifically, the supplements could alleviate depressive symptoms including sad, anhedonia, sleep problems, fatigue, appetite changes, and psychomotor changes. This association was more prominent in specific populations such as the population aged 40-60 years, male, whites. The supplements also show more significant effects on increasing survival rates in patients with mild depression.

LIMITATION

Cross-sectional analysis reveals correlative but not causative association.

CONCLUSION

Based on the analysis of NHANES data, our research highlights the positive effect the supplements have on preventing depression, relieving depressive symptoms and increasing survival rates. This effect varied across populations.

A rich component of Fructus Aurantii, meranzin hydrate, exerts antidepressant effects via suppressing caspase4 to regulate glial cell and neuronal functions in the hippocampus

Fructus Aurantii, a Chinese herbal medicine, has been indicated to have antidepressant effects in our previous study. However, the main component and specific mechanisms of the antidepressant effects of Fructus Aurantii still need to be further revealed. This study aimed to explore the main antidepressant component of Fructus Aurantii and the underlying mechanisms of its antidepressant effects in the hippocampus. The results showed that the component of meranzin hydrate (MH) was enrichment in Fructus Aurantii. MH could alleviate depressive phenotypes in LPS-induced mice after a single administration 1 day later. High genetic and proteinic levels of caspase4 in the hippocampus in LPS-induced mice were reversed by MH after a single administration 1 day later. Moreover, MH was capable of relieving inflammatory factors (TNF-a and IL-1β) and LPS in the serum in LPS-induced mice. Subsequently, activation of hippocampal caspase4 blocked MH's antidepressant effects and its effects on suppression of microglia and improvement of astrocyte in the hippocampus. Furthermore, MH could increase long-term potential (LTP) in the hippocampal dentate gyrus (DG) and activation of hippocampal caspase4 blocked MH's enhancement on neuronal activities and synaptic plasticity in the hippocampal DG. To sum up, the antidepressant effects of a rich component MH in Fructus Aurantii suppressed the activation of caspase4 by maintaining glial cells function to promote neuronal activities and synaptic plasticity in the hippocampus.

Unraveling the Role of the Blood-Brain Barrier in the Pathophysiology of Depression: Recent Advances and Future Perspectives

Depression is a highly prevalent psychological disorder characterized by persistent dysphoria, psychomotor retardation, insomnia, anhedonia, suicidal ideation, and a remarkable decrease in overall well-being. Despite the prevalence of accessible antidepressant therapies, many individuals do not achieve substantial improvement. Understanding the multifactorial pathophysiology and the heterogeneous nature of the disorder could lead the way toward better outcomes. Recent findings have elucidated the substantial impact of compromised blood-brain barrier (BBB) integrity on the manifestation of depression. BBB functions as an indispensable defense mechanism, tightly overseeing the transport of molecules from the periphery to preserve the integrity of the brain parenchyma. The dysfunction of the BBB has been implicated in a multitude of neurological disorders, and its disruption and consequent brain alterations could potentially serve as important factors in the pathogenesis and progression of depression. In this review, we extensively examine the pathophysiological relevance of the BBB and delve into the specific modifications of its components that underlie the complexities of depression. A particular focus has been placed on examining the effects of peripheral inflammation on the BBB in depression and elucidating the intricate interactions between the gut, BBB, and brain. Furthermore, this review encompasses significant updates on the assessment of BBB integrity and permeability, providing a comprehensive overview of the topic. Finally, we outline the therapeutic relevance and strategies based on BBB in depression, including COVID-19-associated BBB disruption and neuropsychiatric implications. Understanding the comprehensive pathogenic cascade of depression is crucial for shaping the trajectory of future research endeavors.

Electroconvulsive Therapy Changes Immunological Markers in Patients With Major Depressive Disorder: A Scoping Review

ABSTRACT

Major depressive disorder (MDD) is a highly prevalent and disabling condition. As such, understanding the causes of and treatment options for MDD is critical. Electroconvulsive therapy (ECT) remains the gold standard depression treatment, but the molecular mechanisms that underlie its effects are still largely unknown. One such explanation hinges on the immuno-inflammatory correlates of ECT treatment, given mounting evidence supporting the inflammatory hypothesis of depression. This review aims to provide an overview of the suggested immunomodulatory effects of ECT and the predictive value of immune biomarkers in relation to treatment outcomes and side effects. We conducted a preregistered, systematic literature search utilizing MEDLINE (PubMed), Embase (Elsevier), and PsycINFO (EBSCO) databases. We employed keywords related to MDD, ECT, gut microbiome, and the immune system. We only included human subjects research published between 1985 and January 13, 2021. Twenty-six unique studies were included in our analyses. Findings indicate a proinflammatory profile associated with MDD, with immune biomarkers exhibiting acute and chronic changes following ECT. Consistently, lower baseline interleukin 6 levels and higher C-reactive protein levels are correlated with a greater reduction in depressive symptoms following ECT. Furthermore, included studies emphasize the predictive value of peripheral immune changes, specifically interleukin 6 and tumor necrosis factor α, on cognitive outcomes following ECT. Given these results, further exploration of the potential roles of immunomodulatory effects on ECT treatment outcomes, as well as adverse cognitive side effects, is indicated.

Exploring the Potential of Probiotics and Prebiotics in Major Depression: From Molecular Function to Clinical Therapy

Major depressive disorder (MDD) represents a complex and challenging mental health condition with multifaceted etiology. Recent research exploring the gut-brain axis has shed light on the potential influence of gut microbiota on mental health, offering novel avenues for therapeutic intervention. This paper reviews current evidence on the role of prebiotics and probiotics in the context of MDD treatment. Clinical studies assessing the effects of prebiotic and probiotic interventions have demonstrated promising results, showcasing improvements in depression symptoms and metabolic parameters in certain populations. Notably, prebiotics and probiotics have shown the capacity to modulate inflammatory markers, cortisol levels, and neurotransmitter pathways linked to MDD. However, existing research presents varied outcomes, underscoring the need for further investigation into specific microbial strains, dosage optimization, and long-term effects. Future research should aim at refining personalized interventions, elucidating mechanisms of action, and establishing standardized protocols to integrate these interventions into clinical practice. While prebiotics and probiotics offer potential adjunctive therapies for MDD, continued interdisciplinary efforts are vital to harnessing their full therapeutic potential and reshaping the landscape of depression treatment paradigms.

Integrated colon microbiome and metabolomics to elucidate the antidepressant mechanisms of the Radix Bupleuri-Radix Paeoniae Alba herb pair

Radix Bupleuri-Radix Paeoniae Alba herb pair (RB-RPA) is the fundamental medication combination of many classic antidepressant prescriptions, and RB-RPA's antidepressant effect is well established. For an extended period, the involvement of intestinal flora in the progression of depression has been widely acknowledged. However, it remains unclear whether RB-RPA could modulate intestinal microbiota disturbances and metabolic abnormalities induced by depression. The research explores the antidepressant mechanism of RB-RPA in chronic unpredictable mild stress (CUMS) rats in terms of intestinal flora and metabolites. We identified critical gut microbial species and metabolites associated with the antidepressant effects of RB-RPA using 16 S rRNA sequencing and Liquid Chromatography-Mass Spectrometry (LC-MS) metabolomics. And then, correlation analysis between critical microbiota and differential metabolites was conducted. The results demonstrate that RB-RPA significantly ameliorated depressive-like behavior in CUMS rats. RB-RPA improved intestinal flora disorders in depressed rats mainly by increasing the abundance of Lactobacillus (especially L. johnsonii), and ameliorated tryptophan synthesis and metabolism disorders in depressed rats and restored the levels of tryptophan and tryptophan microbial metabolites, such as indoleacrylic acid and 4-indoleacetaldehyde. Notably, correlation analysis showed that Lactobacillus had a significant positive correlation with tryptophan, indoleacrylic acid, and 4-indoleacetaldehyde. In conclusion, RB-RPA can improve the disorder of intestinal flora by increasing the abundance of Lactobacillus and improve the metabolic disorder of depressed rats by regulating tryptophan metabolism, thus exerting antidepressant effects.

New therapeutic avenues in multiple sclerosis: Is there a place for gut microbiota-based treatments?

The bidirectional interaction between the gut and the central nervous system (CNS), the so-called gut microbiota-brain axis, is reported to influence brain functions, thus having a potential impact on the development or the progression of several neurodegenerative disorders. Within this context, it has been documented that multiple sclerosis (MS), an autoimmune inflammatory, demyelinating, and neurodegenerative disease of the CNS, is associated with gastrointestinal symptoms, including constipation, dysphagia, and faecal incontinence. Moreover, some evidence suggests the existence of an altered gut microbiota (GM) composition in MS patients with respect to healthy individuals, as well as the potential influence of GM dysbiosis on typical MS features, including increased intestinal permeability, disruption of blood-brain barrier integrity, chronic inflammation, and altered T cells differentiation. Starting from these assumptions, the possible involvement of GM alteration in MS pathogenesis seems likely, and its restoration could represent a supplemental beneficial strategy against this disabling disease. In this regard, the present review will explore possible preventive approaches (including several dietary interventions, the administration of probiotics, prebiotics, synbiotics, and postbiotics, and the use of faecal microbiota transplantation) to be pursued as prophylaxis or in combination with pharmacological treatments with the aim of re-establishing a proper GM, thus helping to prevent the development of this disease or to manage it by alleviating symptoms or slowing down its progression.

CMFHMDA: a prediction framework for human disease-microbe associations based on cross-domain matrix factorization

Predicting associations between microbes and diseases opens up new avenues for developing diagnostic, preventive, and therapeutic strategies. Given that laboratory-based biological tests to verify these associations are often time-consuming and expensive, there is a critical need for innovative computational frameworks to predict new microbe-disease associations. In this work, we introduce a novel prediction algorithm called Predicting Human Disease-Microbe Associations using Cross-Domain Matrix Factorization (CMFHMDA). Initially, we calculate the composite similarity of diseases and the Gaussian interaction profile similarity of microbes. We then apply the Weighted K Nearest Known Neighbors (WKNKN) algorithm to refine the microbe-disease association matrix. Our CMFHMDA model is subsequently developed by integrating the network data of both microbes and diseases to predict potential associations. The key innovations of this method include using the WKNKN algorithm to preprocess missing values in the association matrix and incorporating cross-domain information from microbes and diseases into the CMFHMDA model. To validate CMFHMDA, we employed three different cross-validation techniques to evaluate the model's accuracy. The results indicate that the CMFHMDA model achieved Area Under the Receiver Operating Characteristic Curve scores of 0.9172, 0.8551, and 0.9351$\pm $0.0052 in global Leave-One-Out Cross-Validation (LOOCV), local LOOCV, and five-fold CV, respectively. Furthermore, many predicted associations have been confirmed by published experimental studies, establishing CMFHMDA as an effective tool for predicting potential disease-associated microbes.

Microbiota alterations associated with vascular diseases: postbiotics as a next-generation magic bullet for gut-vascular axis

The intestinal microbiota represents a key element in maintaining the homeostasis and health conditions of the host. Vascular pathologies and other risk factors such as aging have been recently associated with dysbiosis. The qualitative and quantitative alteration of the intestinal microbiota hinders correct metabolic homeostasis, causing structural and functional changes of the intestinal wall itself. Impairment of the intestinal microbiota, combined with the reduction of the barrier function, worsen the pathological scenarios of peripheral tissues over time, including the vascular one. Several experimental evidence, collected in this review, describes in detail the changes of the intestinal microbiota in dysbiosis associated with vascular alterations, such as atherosclerosis, hypertension, and endothelial dysfunction, the resulting metabolic disorders and how these can impact on vascular health. In this context, the gut-vascular axis is considered, for the first time, as a merged unit involved in the development and progression of vascular pathologies and as a promising target. Current approaches for the management of dysbiosis such as probiotics, prebiotics and dietary modifications act mainly on the intestinal district. Postbiotics, described as preparation of inanimate microorganisms and/or their components that confers health benefits on the host, represent an innovative strategy for a dual management of intestinal dysbiosis and vascular pathologies. In this context, this review has the further purpose of defining the positive effects of the supplementation of bacterial strains metabolites (short‑chain fatty acids, exopolysaccharides, lipoteichoic acids, gallic acid, and protocatechuic acid) restoring intestinal homeostasis and acting directly on the vascular district through the gut-vascular axis.

The Influence of Cecal Microbiota Transplantation on Chicken Injurious Behavior: Perspective in Human Neuropsychiatric Research

Numerous studies have evidenced that neuropsychiatric disorders (mental illness and emotional disturbances) with aggression (or violence) pose a significant challenge to public health and contribute to a substantial economic burden worldwide. Especially, social disorganization (or social inequality) associated with childhood adversity has long-lasting effects on mental health, increasing the risk of developing neuropsychiatric disorders. Intestinal bacteria, functionally as an endocrine organ and a second brain, release various immunomodulators and bioactive compounds directly or indirectly regulating a host's physiological and behavioral homeostasis. Under various social challenges, stress-induced dysbiosis increases gut permeability causes serial reactions: releasing neurotoxic compounds, leading to neuroinflammation and neuronal injury, and eventually neuropsychiatric disorders associated with aggressive, violent, or impulsive behavior in humans and various animals via a complex bidirectional communication of the microbiota-gut-brain (MGB) axis. The dysregulation of the MGB axis has also been recognized as one of the reasons for the prevalence of social stress-induced injurious behaviors (feather pecking, aggression, and cannibalistic pecking) in chickens. However, existing knowledge of preventing and treating these disorders in both humans and chickens is not well understood. In previous studies, we developed a non-mammal model in an abnormal behavioral investigation by rationalizing the effects of gut microbiota on injurious behaviors in chickens. Based on our earlier success, the perspective article outlines the possibility of reducing stress-induced injurious behaviors in chickens through modifying gut microbiota via cecal microbiota transplantation, with the potential for providing a biotherapeutic rationale for preventing injurious behaviors among individuals with mental disorders via restoring gut microbiota diversity and function.

Effects of Dietary Fiber, Phenolic Compounds, and Fatty Acids on Mental Health: Possible Interactions with Genetic and Epigenetic Aspects

Scientific evidence shows that dietary patterns are a key environmental determinant of mental health. Dietary constituents can modify epigenetic patterns and thus the gene expression of relevant genetic variants in various mental health conditions. In the present work, we describe some nutrigenomic effects of dietary fiber, phenolic compounds (plant secondary metabolites), and fatty acids on mental health outcomes, with emphasis on their possible interactions with genetic and epigenetic aspects. Prebiotics, through their effects on the gut microbiota, have been associated with modulation in the neuroendocrine response to stress and the facilitation of the processing of positive emotions. Some of the genetic and epigenetic mechanisms include the serotonin neurotransmitter system (TPH1 gene) and the brain-derived neurotrophic factor (inhibition of histone deacetylases). The consumption of phenolic compounds exerts a positive role in neurocognitive domains. The evidence showing the involvement of genetic and epigenetic factors comes mainly from animal models, highlighting the role of epigenetic mechanisms through miRNAs and methyltransferases as well as the effect on the expression of apoptotic-related genes. Long-chain n-3 fatty acids (EPA and DHA) have been mainly related to psychotic and mood disorders, but the genetic and epigenetic evidence is scarce. Studies on the genetic and epigenetic basis of these interactions need to be promoted to move towards a precision and personalized approach to medicine.

A novel probiotic formula, BLLL, ameliorates chronic stress-induced depression-like behaviors in mice by reducing neuroinflammation and increasing neurotrophic factors

Introduction: Probiotics have been recognized for their various biological activities, including antioxidant and anti-inflammatory properties. This study investigates the therapeutic effect of a novel probiotic formula, BLLL, consisting of Bifidobacterium breve, Lactobacillus plantarum, Lactobacillus paracasei, and Lactobacillus helveticus, on chronic stress-induced depression-like behaviors in mice. Methods: The BLLL formula or phosphate-buffered saline (PBS) was given orally at a dose of 2, 4, or 8 × 1010 CFU/kg once daily for 10 days in mice treated with chronic unpredictable stress (CUS) treated or vehicle. Depression-like behaviors were assessed using the sucrose preference test (SPT), the forced swimming test (FST), and the tail suspension test (TST). The mRNA and/or protein expression of interleukin-1β (IL-1β), IL-6, tumor necrosis factor-α (TNF-α), IL-4, IL-10, and chitinase-3-like protein 3 (CHI3L1, also known as Ym-1), as well as the concentration of nitrite, malondialdehyde (MDA), glutathione (GSH), and brain-derived neurotrophic factor (BDNF) in the hippocampus and medial prefrontal cortex were examined. Results: The BLLL formula treatment at a dose of 8 × 1010 CFU/kg, but not at a dose of 2 or 4 × 1010 CFU/kg, improved CUS-induced depression-like behaviors in mice, as shown by the decrease in immobility time in the TST and FST and the increase in sucrose intake in the SPT. Further analysis revealed that BLLL treatment suppressed the CUS-induced increase in IL-1β, IL-6, and TNF-α mRNA and protein levels, as well as the CUS-induced decrease in IL-4, IL-10, and Ym-1 mRNA and/or protein levels in the hippocampus and medial prefrontal cortex. In addition, treatment with the BLLL formula countered the CUS-induced increase in nitrite and MDA levels and the CUS-induced decrease in GSH content and BDNF concentration in the hippocampus and medial prefrontal cortex. Conclusion: These results demonstrate that the novel probiotic formula BLLL ameliorates chronic stress-induced depression-like behavior in mice by suppressing neuroinflammation and oxido-nitrosative stress in the brain.

The Role of Nondigestible Oligosaccharides in Alleviating Human Chronic Diseases by Regulating the Gut Microbiota: A Review

The gut has been a focus of chronic disease research. The gut microbiota produces metabolites that act as signaling molecules and substrates, closely influencing host health. Nondigestible oligosaccharides (NDOs), as a common dietary fiber, play an important role in regulating the structure and function of the gut microbiota. Their mechanism of action is mainly attributed to providing a carbon source as specific probiotics, producing related metabolites, and regulating the gut microbial community. However, due to the selective utilization of oligosaccharides, some factors, such as the type and structure of oligosaccharides, have different impacts on the composition of microbial populations and the production of metabolites in the colon ecosystem. This review systematically describes the key factors influencing the selective utilization of oligosaccharides by microorganisms and elaborates how oligosaccharides affect the host's immune system, inflammation levels, and energy metabolism by regulating microbial diversity and metabolic function, which in turn affects the onset and progress of chronic diseases, especially diabetes, obesity, depression, intestinal inflammatory diseases, and constipation. In this review, we re-examine the interaction mechanisms between the gut microbiota and its associated metabolites and diseases, and we explore new strategies for promoting human health and combating chronic diseases through dietary interventions.

Current landscape of fecal microbiota transplantation in treating depression

Depression, projected to be the predominant contributor to the global disease burden, is a complex condition with diverse symptoms including mood disturbances and cognitive impairments. Traditional treatments such as medication and psychotherapy often fall short, prompting the pursuit of alternative interventions. Recent research has highlighted the significant role of gut microbiota in mental health, influencing emotional and neural regulation. Fecal microbiota transplantation (FMT), the infusion of fecal matter from a healthy donor into the gut of a patient, emerges as a promising strategy to ameliorate depressive symptoms by restoring gut microbial balance. The microbial-gut-brain (MGB) axis represents a critical pathway through which to potentially rectify dysbiosis and modulate neuropsychiatric outcomes. Preclinical studies reveal that FMT can enhance neurochemicals and reduce inflammatory markers, thereby alleviating depressive behaviors. Moreover, FMT has shown promise in clinical settings, improving gastrointestinal symptoms and overall quality of life in patients with depression. The review highlights the role of the gut-brain axis in depression and the need for further research to validate the long-term safety and efficacy of FMT, identify specific therapeutic microbial strains, and develop targeted microbial modulation strategies. Advancing our understanding of FMT could revolutionize depression treatment, shifting the paradigm toward microbiome-targeting therapies.

Gut microbiota and inflammatory factor characteristics in major depressive disorder patients with anorexia

BACKGROUND

This study aimed to explore the gut microbiota and inflammatory factor characteristics in major depressive disorder (MDD) patients with anorexia and to analyze the correlation between gut microbiota and inflammatory factors, anorexia, and HAMD scores.

METHODS

46 MDD patients and 46 healthy controls (HC) were included in the study. The 46 MDD patients were divided into two groups according to whether they had anorexia:20 MDD without anorexia (MDA0 group) and 26 MDD with anorexia (MDA1 group). We used the Hamilton Depression Scale-24 (HAMD-24) to evaluate the depression status of all participants and 16 S ribosomal RNA (16 S rRNA)sequencing to evaluate the composition of the gut microbiota. Inflammatory factors in peripheral blood such as C-reactive protein (CRP) were detected using enzyme-linked immunosorbent assay (ELISA). Spearman's correlation analysis was used to evaluate the correlation between gut microbiota and inflammatory factors, HAMD scores, and anorexia.

RESULTS

1). CRP was significantly higher in the MDA0, MDA1, than HC. 2). An analysis of α-diversity shows: the Simpson and Pielou indices of the HC group are higher than the MDA1 group (P < 0.05). 3). The β-diversity analysis shows differences in the composition of microbial communities between the MDA0, MDA1, and HC group. 4). A correlation analysis showed that Blautia positively correlated with anorexia, HAMD scores, and CRP level, whereas Faecalibacterium, Bacteroides, Roseburia, and Parabacteroides negatively correlated with anorexia, HAMD scores, and CRP level. 5). The receiver operating characteristic (ROC) curve was drawn using the differential bacterial genera between MDD patients with or without anorexia as biomarkers to identify whether MDD patients were accompanied with anorexia, and its area under curve (AUC) was 0.85. The ROC curve was drawn using the differential bacterial genera between MDD patients with anorexia and healthy controls as biomarkers to diagnose MDD patients with anorexia, with its AUC was 0.97.

CONCLUSION

This study suggested that MDD patients with anorexia had a distinct gut microbiota compared to healthy individuals, with higher level of CRP. Blautia was more abundant in MDD patients with anorexia and positively correlated with CRP, HAMD scores, and anorexia. The gut microbiota might have influenced MDD and anorexia through the inflammatory factor CRP.

Just a gut feeling: Faecal microbiota transplant for treatment of depression - A mini-review

BACKGROUND

The microbiota-gut-brain axis (MGBA) allows bidirectional crosstalk between the brain and gut microbiota (GM) and is believed to contribute to regulating mood/cognition/behaviour/metabolism/health and homeostasis. Manipulation of GM through faecal microbiota transplant (FMT) is a new, exciting and promising treatment for major depressive disorder (MDD).

AIMS

This mini-review examines current research into GM and FMT as a therapy for depression.

METHODS

Original research articles published in Medline/Cochrane Library/PubMed/EMBASE/PsycINFO databases/National Institute of Health website Clinicaltrials.gov/controlled-trials.com were searched. Full articles included in reference lists were evaluated. We summarise current data on GM and depression and discuss communication through the MGBA and the interaction of antidepressants and GM through this. We review compositions of dysbiosis in depressed cohorts, focusing on future directions in the treatment of MDD.

RESULTS

Studies have demonstrated significant gut dysbiosis in depressed patients compared to healthy cohorts, with overgrowth of pro-inflammatory microbiota, reduction in anti-inflammatory species and reduced overall stability and taxonomic richness. FMT allows the introduction of healthy microbiota into the gastrointestinal tract, facilitating the restoration of eubiosis.

CONCLUSION

The GM plays an integral role in human health and disease through its communication with the rest of the body via the MGBA. FMT may provide a means to transfer the healthy phenotype into the recipient and this concept in humans is attracting enormous attention as a prospective treatment for psychopathologies, such as MDD, in the future. It may be possible to manipulate the GM in a number of ways, but further research is needed to determine the exact likelihood and profiles involved in the development and amelioration of MDD in humans, as well as the long-term effects and potential risks of this procedure.

Gut microbiota and type 2 diabetes mellitus: a focus on the gut-brain axis

Type 2 diabetes mellitus (T2DM) has become one of the most serious public healthcare challenges, contributing to increased mortality and disability. In the past decades, significant progress has been made in understanding the pathogenesis of T2DM. Mounting evidence suggested that gut microbiota (GM) plays a significant role in the development of T2DM. Communication between the GM and the brain is a complex bidirectional connection, known as the "gut-brain axis," via the nervous, neuroendocrine, and immune systems. Gut-brain axis has an essential impact on various physiological processes, including glucose metabolism, food intake, gut motility, etc. In this review, we provide an outline of the gut-brain axis. We also highlight how the dysbiosis of the gut-brain axis affects glucose homeostasis and even results in T2DM.

BDNF/CREB signaling pathway contribution in depression pathogenesis: A survey on the non-pharmacological therapeutic opportunities for gut microbiota dysbiosis

Emerging evidence supports the gut microbiota and the brain communication in general health. This axis may affect behavior through modulating neurotransmission, and thereby involve in the pathogenesis and/or progression of different neuropsychiatric disorders such as depression. Brain-derived neurotrophic factor and cAMP response element-binding protein known as CREB/BDNF pathway plays have critical functions in the pathogenesis of depression as the same of mechanisms related to antidepressants. However, the putative causal significance of the CREB/BDNF signaling cascade in the gut-brain axis in depression remains unknown. Also interventions such as probiotics supplementation and exercise can influence microbiome also improve bidirectional communication of gut and brain. In this review we aim to explain the BDNF/CREB signaling pathway and gut microbiota dysfunction and then evaluate the potential role of probiotics, prebiotics, and exercise as a therapeutic target in the gut microbiota dysfunction induced depression. The current narrative review will specifically focus on the impact of exercise and diet on the intestinal microbiota component, as well as the effect that these therapies may have on the microbiota to alleviate depressive symptoms. Finally, we look at how BDNF/CREB signaling pathway may exert distinct effects on depression and gut microbiota dysfunction.

A meta-analysis of the changes in the Gut microbiota in patients with intractable epilepsy compared to healthy controls

OBJECTIVE

To explore gut microbiota changes in intractable epilepsy patients compared to healthy control individuals through meta-analysis.

METHODS

PubMed, Web of Science, CNKI, Wanfang, medRxiv, bioRxiv, ilae.org, clinical trial databases, and papers from the International Epilepsy Congress (IEC) were searched, and the literature on the correlation between intractable epilepsy and the gut microbiota reported from database establishment to June 2023 was included. Literature meeting the inclusion criteria was screened, and meta-analysis of the included literature was performed using RevMan5.4 software.

RESULTS

Ten case-control studies were included in the meta-analysis. There were 183 patients with intractable epilepsy and 283 healthy control subjects. The analysis results indicated that Bacteroidetes (MD = -0.64, 95 %-CI = -1.21 to -0.06) and Ruminococcaceae (MD = -1.44, 95 % CI = -1.96 to -0.92) were less abundant in the patients with intractable epilepsy than in the normal population. Proteobacteria (MD = 0.53, 95 % CI = 0.02 to 1.05) and Verrucomicrobia (MD = 0.26, 95 % CI = 0.06 to 0.45) were more abundant in the patients with intractable epilepsy than in the normal population.

CONCLUSION

This meta-analysis indicated that the abundances of Bacteroidetes and Ruminococcaceae were reduced while those of Proteobacteria and Verrucomicrobia were significantly increased in patients with intractable epilepsy. The above changes in these four taxa of the gut microbiota may have been induced by intractable epilepsy, which may increase the risk of seizures. Their roles in the pathogenesis of intractable epilepsy need to be further explored, and related factors that influence microbiota changes should be considered in future studies.

Understanding the Biological Relationship between Migraine and Depression

Migraine is a highly prevalent neurological disorder. Among the risk factors identified, psychiatric comorbidities, such as depression, seem to play an important role in its onset and clinical course. Patients with migraine are 2.5 times more likely to develop a depressive disorder; this risk becomes even higher in patients suffering from chronic migraine or migraine with aura. This relationship is bidirectional, since depression also predicts an earlier/worse onset of migraine, increasing the risk of migraine chronicity and, consequently, requiring a higher healthcare expenditure compared to migraine alone. All these data suggest that migraine and depression may share overlapping biological mechanisms. Herein, this review explores this topic in further detail: firstly, by introducing the common epidemiological and risk factors for this comorbidity; secondly, by focusing on providing the cumulative evidence of common biological aspects, with a particular emphasis on the serotoninergic system, neuropeptides such as calcitonin-gene-related peptide (CGRP), pituitary adenylate cyclase-activating polypeptide (PACAP), substance P, neuropeptide Y and orexins, sexual hormones, and the immune system; lastly, by remarking on the future challenges required to elucidate the etiopathological mechanisms of migraine and depression and providing updated information regarding new key targets for the pharmacological treatment of these clinical entities.

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.

Gastrointestinal barrier function, immunity, and neurocognition: The role of human milk oligosaccharide (hMO) supplementation in infant formula

Breastmilk is seen as the gold standard for infant nutrition as it provides nutrients and compounds that stimulate gut barrier, immune, and brain development to the infant. However, there are many instances where it is not possible for an infant to be fed with breastmilk, especially for the full 6 months recommended by the World Health Organization. In such instances, infant formula is seen as the next best approach. However, infant formulas do not contain human milk oligosaccharides (hMOs), which are uniquely present in human milk as the third most abundant solid component. hMOs have been linked to many health benefits, such as the development of the gut microbiome, the immune system, the intestinal barrier, and a healthy brain. This paper reviews the effects of specific hMOs applied in infant formula on the intestinal barrier, including the not-often-recognized intestinal alkaline phosphatase system that prevents inflammation. Additionally, impact on immunity and the current proof for effects in neurocognitive function and the corresponding mechanisms are discussed. Recent studies suggest that hMOs can alter gut microbiota, modulate intestinal immune barrier function, and promote neurocognitive function. The hMOs 2'-fucosyllactose and lacto-N-neotetraose have been found to have positive effects on the development of infants and have been deemed safe for use in formula. However, their use has been limited due to their cost and complexity of synthesis. Thus, although many benefits have been described, complex hMOs and combinations of hMOs with other oligosaccharides are the best approach to stimulate gut barrier, immune, and brain development and for the prevention of disease.

JAK-STAT signaling in inflammation and stress-related diseases: implications for therapeutic interventions

The Janus kinase-signal transducer and transcription activator pathway (JAK-STAT) serves as a cornerstone in cellular signaling, regulating physiological and pathological processes such as inflammation and stress. Dysregulation in this pathway can lead to severe immunodeficiencies and malignancies, and its role extends to neurotransduction and pro-inflammatory signaling mechanisms. Although JAK inhibitors (Jakinibs) have successfully treated immunological and inflammatory disorders, their application has generally been limited to diseases with similar pathogenic features. Despite the modest expression of JAK-STAT in the CNS, it is crucial for functions in the cortex, hippocampus, and cerebellum, making it relevant in conditions like Parkinson's disease and other neuroinflammatory disorders. Furthermore, the influence of the pathway on serotonin receptors and phospholipase C has implications for stress and mood disorders. This review expands the understanding of JAK-STAT, moving beyond traditional immunological contexts to explore its role in stress-related disorders and CNS function. Recent findings, such as the effectiveness of Jakinibs in chronic conditions such as rheumatoid arthritis, expand their therapeutic applicability. Advances in isoform-specific inhibitors, including filgotinib and upadacitinib, promise greater specificity with fewer off-target effects. Combination therapies, involving Jakinibs and monoclonal antibodies, aiming to enhance therapeutic specificity and efficacy also give great hope. Overall, this review bridges the gap between basic science and clinical application, elucidating the complex influence of the JAK-STAT pathway on human health and guiding future interventions.

Vagus nerve-dependent effects of fluoxetine on anxiety- and depression-like behaviors in mice

The vagus nerve is a major pathway in the body that is responsible for regulating the activity of the parasympathetic nervous system, which plays an important role in mood disorders including anxiety and depression. Fluoxetine, also known as Prozac, is widely used to treat depression. Nevertheless, there are few studies on the vagus nerve-mediated action of fluoxetine. In this study, we aimed to investigate the vagus nerve-dependent actions of fluoxetine in mice with restraint stress-induced or antibiotics-induced anxiety- and depression-like behaviors. Compared to sham operation, vagotomy alone did not exhibit significant effects on behavioral changes and serotonin-related biomarkers in mice not exposed to stress, antibiotics, or fluoxetine. Oral administration of fluoxetine significantly alleviated anxiety- and depression-like behaviors. However, celiac vagotomy significantly attenuated the anti-depressive effects of fluoxetine. The vagotomy also inhibited the effect of fluoxetine to attenuate restraint stress- or cefaclor-induced reduction in serotonin levels and Htr1a mRNA expression in the hippocampus. These findings suggest that the vagus nerve may regulate the efficacy of fluoxetine for depression.