Gut microbiota regulates chronic ethanol exposure-induced depressive-like behavior through hippocampal NLRP3-mediated neuroinflammation

Arisaema cum Bile Mitigate Febrile Seizure in Rats via Inhibition of Neuroinflammation, Regulation of FXR and GABA Signaling Pathway

Background

Arisaema cum bile (known as DanNan Xing in Chinese, DNX) is a traditional herbal medicine commonly used to treat febrile seizure (FS), but the underlying mechanism remains unclear.

Objective

To evaluate the therapeutic effect of DNX on hot water bath-induced FS rat model and further explore the potential mechanism.

Methods

The chemical constituents of DNX were determined via liquid chromatography-mass spectrometry (LC-MS). FS rat model was established using a hot water bath (45 ± 2 °C), and DNX (2.8 and 0.7 g/kg, i.g) were administered for two weeks. Based on behavior test (duration and latency), pathological changes in the hippocampal tissue, and the levels of inflammatory cytokines the therapeutic effect of DNX for FS was evaluated. Subsequently, the network pharmacology, 16S rRNA and non-targeted metabolomics analysis were combined analysis to explore the potential signaling pathway. Furthermore, the signaling pathway was verified using the RT-qPCR and immunohistochemistry assay.

Results

The DNX treatment showed effective therapy on hot water bath induced FS, as indicated by a shortened seizure duration time, prolonged seizure latency, reduced hippocampal neuron damage and neuroinflammatory factor levels (TNF-α, IL-1β, IL-6, and HMGB1). Neurotransmitters (GABA, Glu) are also significantly regulated. Moreover, the relative abundance of Lactobacillus and Lachnospiraceae was notably increased (p < 0.01), while that of Tenericutes decreased, compared to gut microbiota of FS rat. A total of 20 fecal differential metabolites were regarded as the potential biomarkers including GABA, CDCA, and UDCA for anti-FS of DNX, and combined network pharmacy the metabolic pathways of primary bile acids (BAs) biosynthesis and alanine, aspartate and glutamate metabolism were involved.

Conclusion

DNX possesses a therapeutic effect on FS through inhibiting neuroinflammation and regulation of FXR and GABA signaling pathway.

Microbiota in Alcohol-Associated Organ Damage

Alcohol-associated organ damage is a major cause of morbidity and mortality worldwide, with the liver being the primarily affected organ. Emerging evidence highlights the gut microbiota as a key driver in alcohol-associated liver disease. Changes in the microbiota composition, microbial translocation, and a dysregulated immune response culminate in inflammation and tissue injury. Persistent liver injury eventually promotes disease progression from steatohepatitis to fibrosis and cirrhosis. In this review, we provide an overview of microbiota alterations observed in patients with chronic alcohol consumption and explore the mechanisms by which microbiota contributes to alcohol-associated damage across various organ systems. Emphasis is placed on changes in the gut microbiota and its role in alcohol-associated liver disease, the disease condition with the most robust evidence linking microbiota-related changes to organ injury. Additionally, we highlight key areas where further research is needed to address unresolved questions. Finally, we discuss emerging therapeutic strategies targeting the microbiota to treat alcohol use disorders and prevent alcohol-associated liver diseases.

A Bibliometric Analysis of Neuroinflammation in Depression from 2004 to 2023: Global Research Hotspots and Prospects

Background: Neuroinflammation lays a prominent impact in the pathophysiology of depression, and numerous studies have been conducted in recent decades. Bibliometric analysis is of important for understanding the hot spots and research trends in a certain subject field. However, no systematic bibliometric study exists in this field to date. The purpose of the study focused on the trends and hotspots in neuroinflammation of depression and provided future researchers with guidance and sights. Methods: Publications (2004-2023) were obtained from the WoSCC, and analyzed by HistCite, VOSviewer, CiteSpace, and Bibliometrix. The impact of publications was assessed by TGCS. Results: We analyzed 1,496 articles published in 409 journals and authored by 46,533 researchers across 72 countries and regions. The most prolific countries were China, the USA, and Brazil, and the most cited countries were the USA, followed with China and the UK, while the most prolific and cited institution was University Toronto (records=34, TGCS=2,137). Brain Behavior and Immunity is the leading journal that regularly published research in this field (records=93, TGCS=6,247). NLRP3 inflammasome, microglia, TNF-α, and brain-derived neurotrophic factor (BDNF) were the basis of neuroinflammation in depression. C-reactive protein, an important marker of inflammation, has been discussed for the longest time in this disease. In recent five years, two most frontier potential areas in studying depression were gut microbiota dysbiosis and BDNF. Conclusions: There remains a strong research basis for neuroinflammation in depression from this bibliometric analysis. Microglial activation, gut microbiota, cytokine signaling, and oxidative stress were research hotspots in recent years. In the future, chronic stress, hippocampal structure, and gut microbiota will continue to be studied in the field of neuroinflammation in depression. This study may benefit scientists in identifying potential directions for future study and providing clinicians with new ideas for treatment.

Trehalose Acts as a Mediator: Imbalance in Brain Proteostasis Induced by Polystyrene Nanoplastics via Gut Microbiota Dysbiosis during Early Life

As an emerging contaminant, nanoplastics have evolved into a global ecological issue. Studies have shown that nanoplastics induce neurotoxicity across species, however, the causal mechanism remains unknown. This study aimed to explore the mechanism underlying the neurotoxicity caused by polystyrene nanoplastics (PS-NPs) via microbiota-gut-brain axis in immature mice, which serve as a model of infants and young children who are at higher exposure risk to NPs. The results indicated that while only a minority of PS-NPs reached the brain after exposure, they still had significant neurotoxic effects, as reflected by abnormalities in behavior, biochemical marker levels and histopathology. Proteomics and quantification analyses revealed that a proteostasis imbalance mediated by lysosomal and proteasome dysfunction in the brain is the key reason for the induced neurotoxicity. Further, we confirmed the indirect role of gut microbiota in the neurotoxicity induced by PS-NPs through 16S rDNA analyses and fecal microbiota transplantation. Crucial bacterial species such as Eubacterium coprostanoligenes potentially act as indicators for gut dysbiosis after PS-NPs exposure. Notably, we first estimated the indirect effect of gut microbiota on neurotoxicity attributed to PS-NPs in immature mice as 39.20% by high-dimensional mediation analysis. Trehalose was identified as a mediator connecting the gut microbiota and the brain, and the crucial role of trehalose supplementation was highlighted in remodeling the brain proteostasis to alleviate the neurotoxicity in immature mice. These findings are expected to contribute to a deeper understanding of the risk assessment and health protection of the nervous system from exposure to PS-NPs early in life.

MiR-129-5p alleviates depression and anxiety by increasing astrocyte ATP production partly through targeting deubiquitinase Mysm1

Major depressive disorder (MDD) is a major global mental concern that severely affects quality of life, yet current pharmacological treatments remain limited in their effectiveness. Long-term chronic stress has been shown to increase the incidence of depression and anxiety. Micro RNAs (miRNAs) have been revealed to participate in the pathological process of depression and represent promising therapeutic targets. In this study, we found that microRNA-129-5p (miR-129-5p) was significantly decreased in the brains of depressive mice. Overexpression of miR-129-5p in the hippocampus effectively alleviated depressive-like behaviors and reduced the activation of microglial cells and astrocytes. In addition, ATP levels in depressive mice were significantly increased following miR-129-5p overexpression. The antidepressant effects of miR-129-5p were reversed when ATP function was blocked with the non-specific P2 receptor antagonist suramin. In vitro experiments revealed that miR-129-5p overexpression enhanced ATP production in astrocytes. Furthermore, using a dual-luciferase reporter assay, we found that miR-129-5p directly targeted Mysm1. When overexpressed in astrocytes, miR-129-5p significantly suppressed Mysm1 expression, promoted phosphorylation of p53 and AMPK, and enhanced the expression of PGC1α, factors previously associated with ATP production. Our findings highlight the crucial role of miR-129-5p in regulating depression, suggesting that miR-129-5p overexpression may serve as an effective strategy for antidepressant treatment.

Gut microbiota-derived trimethylamine N-oxide involved in methamphetamine-induced depression-like behaviors of male mice

Methamphetamine (METH)-provoked psychiatric symptoms are a major health concern, with depression being a prevalent symptom among METH abusers. Recently, gut microbiota-derived metabolites have been involved in various psychosis pathogenesis, but their roles in METH-induced depression remain unclear. This study investigates the implication of gut microbiota-derived metabolite trimethylamine N-oxide (TMAO) in METH-induced depressive-like behaviors (DLBs). We examined the circulating TMAO levels post-METH exposure besides exploring the impacts of TMAO on METH-triggered DLBs. Then, potential causes of TMAO alterations were explored, along with its effects on hippocampal neuronal damage and neuroinflammation. The findings showcased that METH-treated mice displayed DLBs accompanied by increased serum TMAO levels. Similarly, introducing TMAO to the drinking water elevated serum TMAO levels and induced DLBs. Although METH exposure did not notably alter the abundance of the gut microbiota, antibiotic (ABX) therapy suppressed the increased serum TMAO levels and the onset of DLBs. Additionally, choline and L-carnitine levels were elevated following METH exposure, which may be a potential mechanism for TMAO metabolic dysregulation. Elevated TMAO levels resulted in an elevation in Nissl-positive dead cells, the number of microglia, TNF-α, and IL-1β levels, along with TLR-4, NF-κB, and MyD88 expression in the hippocampal CA3 region. Inhibition of TMAO synthesis mitigated METH-provoked neuronal damage and neuroinflammation.

Moderating role of live microbe between chronic inflammatory airway disease and depressive symptoms

Purpose

Our study aims to investigate the impact of dietary live microbe on the relationship between chronic inflammatory airway diseases (CIAD) and depressive symptoms.

Methods

We selected data from the NHANES database from 2007 to 2020. First, we explored the relationship between CIAD and depressive symptoms using logistic regression analysis. And subgroup analyses were conducted to demonstrate the relationship and whether there was an interaction effect between the two in each subgroup. Then, we further analyzed the effect of live microbe on depressive symptoms in CIAD patients. And subgroup analyses were conducted to assess whether the effect of dietary viable microbial levels on depressive symptoms held true in each subgroup and whether there was an interaction effect.

Results

A study included 23,072 participants, of whom 5,111 were diagnosed with CIAD, and 5,110 had live microbial information available. Multivariate logistic regression analysis revealed that, compared to those without CIAD, individuals with CIAD had an increased risk of depressive symptoms. Subgroup analysis indicated that, except for educational level and smoking status, all other subgroups demonstrated that CIAD increased the risk of depressive symptoms. Additionally, within the CIAD population, a higher level of live microbe was associated with a reduced risk of depressive symptoms. It is implied that live microbe can negatively modulate the relationship between CIAD and depressive symptoms. Subgroup analysis further showed no significant interaction effects across subgroups (p > 0.05).

Conclusion

Chronic inflammatory airway diseases can increase the risk of developing depressive symptoms. Dietary live microbe negatively modulate the relationship between CIAD and depressive symptoms. High levels of dietary live microbe significantly reduced the risk of depressive symptoms in patients with CIAD.

Therapeutic potential of faecal microbiota transplantation for alcohol use disorder, a narrative synthesis

BACKGROUND

Faecal microbiota transplantation is proposed as an alternative therapy to treat alcohol use disorder and has completed a Phase 1 clinical trial, with a Phase 2 clinical trial underway. Alcohol, a modifiable risk factor for noncommunicable diseases, resulted in approximately 3 million global deaths (5 %) in 2016 according to the World Health Organization.

AIMS

A narrative synthesis examines the effects of alcohol and faecal microbiota transplantation on gut microbiota and how gut microbiota impacts the gut-brain axis, leading to certain behavioural symptoms of alcohol use disorder. These behavioural symptoms are alcohol craving and relapse in humans; and preference for alcohol, anxiety and depression in rodents.

SEARCH METHODS AND RESULTS

Electronic databases PubMed, Embase, and Scopus were searched in January 2024 using the terms: faecal microbiota trans* AND alcohol AND microbio*. Ten studies out of 964 met the inclusion criteria of published primary studies with faecal microbiota transplantation as an intervention to study the gut-brain axis in alcohol use disorder.

RESULTS

The gut microbiota is altered in alcohol use disorder, which can be modified with faecal microbiota transplantation. Behavioural symptoms such as alcohol craving and relapse are associated with inflammation due to a loss of intestinal barrier function. Beneficial microbiota produce short-chain fatty acids that maintain intestinal barrier function and reduce inflammation. Studies also reported anxiety and depression-like behaviours, in addition to a preference for alcohol in alcohol-naïve rodents after faecal microbiota transplantation from patients with alcohol use disorder.

CONCLUSIONS

Faecal microbiota transplantation may moderate the behavioural symptoms of alcohol use disorder by altering gut microbiota, affecting intestinal permeability and inflammation, however, specific gut microbiota composition and long-term treatment outcomes require further clinical studies.

Improved effect of antibiotic treatments on the hippocampal spatial memory dysfunction of mice induced by high fluoride exposure: Insight from assembly processes and co-occurrence networks of gut microbial community

High fluoride exposure was widely demonstrated to be related with brain memory impairment. Since the absorption of F- enters the body mainly through the gastrointestinal tract, studying the effects of excessive intake of fluoride on brain memory function in various gut microbiome states might have profound implications for the prevention of fluorosis because growing evidence revealed the significance of the "microbiota-gut-brain" axis (MGBA). In the present study, we aimed to illustrate the potential mechanism of gut microbiota on high fluoride exposure-induced hippocampal lesions and spatial memory dysfunction in mice by the various intestinal microecological environments, which were constructed by antibiotic treatment. Mice fed with normal (CG1 and Exp1 groups) or sodium-fluoride (CG2 and Exp2 groups; 24 mg/kg sodium fluoride per mouse) by gavage administration with or without antibiotic treatments, a combination of metronidazole (1 g/L) and ciprofloxacin (0.2 g/L) in drinking water. Mice gavaged with excessive sodium fluoride alone exhibited reduced weight gain, hippocampal tissue damages, spatial memory levels dysfunction, impaired intestinal permeability, decreased inflammatory cytokines expression and antioxidant capability in the hippocampal and ileal tissues. In contrast, antibiotic intervention significantly reversed these high fluoride exposure-induced hippocampal and ileal changes.16S rRNA high throughput sequencing found that ileal microbiota were dominated by abundant taxa, which is conducive to constructing microbial interaction networks and module communities, and identifying keystone species targeted by high fluoride exposure compared with colonic microbiome. In addition, the microbial community composition and assembly mechanism of ileal microbiome under the effects of antibiotics were suitable for revealing the characteristics of high fluoride environment. In the later analysis, Lactobacillus, Staphylococcus, Muribaculaceae and Robinsoniella were considered as the keystone species targeted by high fluoride-exposed mice based on the analysis of network node properties and niche overlap of ileal microbes. Spearman rank correlation demonstrated that these keystone species had significant effects on hippocampal memory levels and intestinal health, as well as microbial communities functions. Compared to previous researches, this study further revealed intestinal microbial coummunity mediated the underlying mechanism through antibiotic treatment against high fluoride-induce hippocampal spatial memory impairment.

The kinase RIPK3 promotes neuronal survival by suppressing excitatory neurotransmission during central nervous system viral infection

While recent work has identified roles for immune mediators in regulating neural activity, how innate immune signaling within neurons influences neurotransmission remains poorly understood. Emerging evidence suggests that the modulation of neurotransmission may serve important roles in host protection during infection of the central nervous system. Here, we showed that receptor-interacting protein kinase-3 (RIPK3) preserved neuronal survival during flavivirus infection through the suppression of excitatory neurotransmission. These effects occurred independently of the traditional functions of RIPK3 in promoting necroptosis and inflammatory transcription. Instead, RIPK3 promoted phosphorylation of the neuronal regulatory kinase calcium/calmodulin-dependent protein kinase II (CaMKII), which in turn activated the transcription factor cyclic AMP response element-binding protein (CREB) to drive a neuroprotective transcriptional program and suppress deleterious glutamatergic signaling. These findings identify an unexpected function for a canonical cell death protein in promoting neuronal survival during viral infection through the modulation of neuronal activity, highlighting mechanisms of neuroimmune crosstalk.

Role of Lactobacillus plantarum-Derived Extracellular Vesicles in Regulating Alcohol Consumption

Alcohol Use Disorder (AUD), characterized by repeated alcohol consumption and withdrawal symptoms, poses a significant public health issue. Alcohol-induced impairment of the intestinal barrier results in alterations in intestinal permeability and the composition of the intestinal microbiota. Such alterations lead to a reduced relative abundance of intestinal lactic acid bacteria. However, the role of gut microbiota in alcohol consumption is not yet fully understood. In this study, we explore the mechanism by which gut microbiota regulates alcohol consumption, specifically using extracellular vesicles derived from Lactobacillus plantarum (L-EVs). L-EVs were administered to Sprague-Dawley rats either through intraperitoneal injection or microinjection into the ventral tegmental area (VTA), resulting in a significant reduction in alcohol consumption 72 hours after withdrawal. The observed reduction was akin to the effect of an intra-VTA microinjection of Brain-Derived Neurotrophic Factor (BDNF). Intriguingly, the microinjection of K252a (a Trk B antagonist) into the VTA blocked the reducing effect of L-EVs on alcohol consumption. The intraperitoneal injection of L-EVs restored the diminished BDNF expression in the VTA of alcohol-dependent rats. Furthermore, L-EVs rescued the low BDNF expression in alcohol-incubated PC12 cells. In conclusion, our study demonstrates that L-EVs attenuated alcohol consumption by enhancing BDNF expression in alcohol-dependent rats, thus suggesting the significant therapeutic potential of L-EVs in preventing excessive alcohol consumption.

Drinking pattern and sex modulate the impact of ethanol consumption on the mouse gut microbiome

Gut microbiota impacts host homeostasis and diseases. Chronic plus binge ethanol consumption has been linked to increased injuries than chronic or binge ethanol intake alone. We hypothesized that distinct shapes in gut microbiota composition are induced by chronic, binge, and the association of these treatments, thereby affecting host functions and contributing to sex-based differences in alcohol use disorders. Male and female C57BL/6J mice were submitted to chronic, binge, or chronic plus binge ethanol feeding. DNA was extracted from fecal microbiota, followed by analysis of the V3-V4 region of the 16S rRNA gene and sequencing on an Illumina platform. Gut microbiome analysis was performed using QIIME v2022.2.0. Functional profiling of the gut microbiome was performed using PICRUSt2. Ethanol differentially affected the gut microbiota of female and male mice. Decreased α diversity was observed in male and female mice from the chronic plus binge and chronic groups, respectively. The genera Faecalibaculum, Lachnospiraceae, and Alistipes were identified as major potential biomarkers for gut dysbiosis induced by ethanol consumption. In addition, ethanol-induced gut dysbiosis altered several metabolic pathways. Ethanol consumption modifies the mouse gut microbiome in a drinking pattern- and sex-dependent manner, potentially leading to different susceptibility to ethanol-related diseases. Chronic plus binge ethanol intake induces a more pronounced gut dysbiosis in male mice. Conversely, chronic ethanol is linked to a greater degree of gut dysbiosis in female mice. The changed gut microbiome may be potentially targeted to prevent, mitigate, or treat alcohol use disorders.NEW & NOTEWORTHY Ethanol alters the mouse gut microbiome in a drinking pattern- and sex-dependent manner. Chronic plus binge ethanol intake induces a more severe gut dysbiosis in male mice, whereas chronic ethanol consumption appears to be a more potent inductor of gut dysbiosis in female mice. Ethanol-induced gut dysbiosis alters several pathways linked to metabolism, genetic and environmental information processing, cellular processes, organism systems, and neurological human diseases.

Role of Peripheral NLRP3 Inflammasome in Cognitive Impairments: Insights of Non-central Factors

Cognitive impairments are common clinical manifestation of Alzheimer's disease, vascular dementia, type 2 diabetes mellitus, and autoimmune diseases. Emerging evidence has suggested a strong correlation between peripheral chronic inflammation and cognitive impairments. For example, nearly 40% of individuals with inflammatory bowel disease also suffer from cognitive impairments. In this condition, NLRP3 inflammasome (NLRP3-I) generating pro-inflammatory cytokines like IL-1β serves as a significant effector, and its persistence exerts adverse effects to both periphery and the brain. Moreover, investigations on serum biomarkers of mild cognitive impairments have shown NLRP3-I components' upregulation, suggesting the involvement of peripheral inflammasome pathway in this disorder. Here, we systematically reviewed the current knowledge of NLRP3-I in inflammatory disease to uncover its potential role in bridging peripheral chronic inflammation and cognitive impairments. This review summarizes the molecular features and ignition process of NLRP3-I in inflammatory response. Meanwhile, various effects of NLRP3-I involved in peripheral inflammation-associated disease are also reviewed, especially its chronic disturbances to brain homeostasis and cognitive function through routes including gut-brain, liver-brain, and kidney-brain axes. In addition, current promising compounds and their targets relative to NLRP3-I are discussed in the context of cognitive impairments. Through the detailed investigation, this review highlights the critical role of peripheral NLRP3-I in the pathogenesis of cognitive disorders, and offers novel perspectives for developing effective therapeutic interventions for diseases associated with cognitive impairments. The present review outlines the current knowledge on the ignition of NLRP3-I in inflammatory disease and more importantly, emphasizes the role of peripheral NLRP3-I as a causal pathway in the development of cognitive disorders. Although major efforts to restrain cognitive decline are mainly focused on the central nervous system, it has become clear that disturbances from peripheral immune are closely associated with the dysfunctional brain. Therefore, attenuation of these inflammatory changes through inhibiting the NLRP3-I pathway in early inflammatory disease may reduce future risk of cognitive impairments, and in the meantime, considerations on such pathogenesis for combined drug therapy will be required in the clinical evaluation of cognitive disorders.

Unraveling the Complex Interplay Between Neuroinflammation and Depression: A Comprehensive Review

The relationship between neuroinflammation and depression is a complex area of research that has garnered significant attention in recent years. Neuroinflammation, characterized by the activation of glial cells and the release of pro-inflammatory cytokines, has been implicated in the pathophysiology of depression. The relationship between neuroinflammation and depression is bidirectional; not only can inflammation contribute to the onset of depressive symptoms, but depression itself can also exacerbate inflammatory responses, creating a vicious cycle that complicates treatment and recovery. The present comprehensive review aimed to explore the current findings on the interplay between neuroinflammation and depression, as well as the mechanisms, risk factors, and therapeutic implications. The mechanisms by which neuroinflammation induces depressive-like behaviors are diverse. Neuroinflammation can increase pro-inflammatory cytokines, activate the hypothalamus-pituitary-adrenal (HPA) axis, and impair serotonin synthesis, all of which contribute to depressive symptoms. Furthermore, the activation of microglia has been linked to the release of inflammatory mediators that can disrupt neuronal function and contribute to mood disorders. Stress-induced neuroinflammatory responses can lead to the release of pro-inflammatory cytokines that not only affect brain function but also influence behavior and mood. Understanding these mechanisms is crucial for developing targeted therapies that can mitigate the effects of neuroinflammation on mood disorders.

Increased expression of ER stress, inflammasome activation, and mitochondrial biogenesis-related genes in peripheral blood mononuclear cells in major depressive disorder

A subset of major depressive disorder (MDD) is characterized by immune system dysfunction, but the intracellular origin of these immune changes remains unclear. Here we tested the hypothesis that abnormalities in endoplasmic reticulum (ER) stress, inflammasome activity and mitochondrial biogenesis contribute to the development of systemic inflammation in MDD. RT-qPCR was used to measure mRNA expression of key organellar genes from peripheral blood mononuclear cells (PBMCs) isolated from 186 MDD and 67 healthy control (HC) subjects. The comparative CT (2-ΔΔCT) method was applied to quantify mRNA expression using GAPDH as the reference gene. After controlling for age, sex, BMI, and medication status using linear regression models, expression of the inflammasome (NLRC4 and NLRP3) and the ER stress (XBP1u, XBP1s, and ATF4) genes was found to be significantly increased in the MDD versus the HC group. Sensitivity analyses excluding covariates yielded similar results. After excluding outliers, expression of the inflammasome genes was no longer statistically significant but expression of the ER stress genes (XBP1u, XBP1s, and ATF4) remained significant and the mitochondrial biogenesis gene, MFN2, was significantly increased in the MDD group. NLRC4 and MFN2 were positively correlated with serum C-reactive protein concentrations, while ASC trended significant. The altered expression of inflammasome activation, ER stress, and mitochondrial biogenesis pathway components suggest that dysfunction of these organelles may play a role in the pathogenesis of MDD.

The liver-brain axis under the influence of chronic Opisthorchis felineus infection combined with prolonged alcoholization in mice

Our purpose was to model a combination of a prolonged consumption of ethanol with Opisthorchis felineus infection in mice. Four groups of C57BL/6 mice were compiled: OF, mice infected with O. felineus for 6 months; Eth, mice consuming 20 % ethanol; Eth+OF, mice subjected to both adverse factors; and CON, control mice not exposed to these factors. In the experimental mice, especially in Eth+OF, each treatment caused well-pronounced periductal and cholangiofibrosis, proliferation of bile ducts, and enlargement of areas of inflammatory infiltration in the liver parenchyma. Simultaneously with liver disintegration, the infectious factor caused - in the frontal cerebral cortex - the growth of pericellular edema (OF mice), which was attenuated by the administration of ethanol (Eth+OF mice). Changes in the levels of some proteins (Iba1, IL-1β, IL-6, and TNF) and in mRNA expression of genes Aif1, Il1b, Il6, and Tnf were found in the hippocampus and especially in the frontal cortex, implying region-specific neuroinflammation. Behavioral testing of mice showed that ethanol consumption influenced the behavior of Eth and Eth+OF mice in the forced swimming test and their startle reflex. In the open field test, more pronounced changes were observed in OF mice. In mice of all three experimental groups, especially in OF mice, a disturbance in the sense of smell was detected (fresh peppermint leaves). The results may reflect an abnormality of regulatory mechanisms of the central nervous system as a consequence of systemic inflammation under the combined action of prolonged alcohol consumption and helminth infection.

CUMS induces depressive-like behaviors and cognition impairment by activating the ERS-NLRP3 signaling pathway in mice

BACKGROUND AND OBJECTIVE

Endoplasmic reticulum stress (ERS), as a primary defense mechanism against stress, is closely related to mental disorders, but its pathogenesis is still unclear. This research seeks to explore the influence of ERS-nucleotide-bound oligomerized domain-like receptor protein 3 (NLRP3) signaling on mice's depressive-like behaviors and cognitive impairment.

DESIGN AND METHOD

We carried out a study on 32 male C57BL/6J mice to investigate how chronic unpredictable mild stress (CUMS) can give rise to depressive-like behaviors and cognitive dysfunction, randomly dividing them into control, model, inhibitor, and agonist groups. We utilized ELISA to quantify dopamine (DA) and 5-hydroxytryptamine (5-HT) levels. Using Nissl and hematoxylin and eosin (H&E) staining, we assessed the number and morphology of hippocampal neurons and cells. Western blot and immunofluorescence staining detected the changes in ERS and inflammation-related pathways in the hippocampus.

RESULTS

CUMS could induce ERS and activate NLRP3 inflammasome, causing neuronal damage and histopathological changes, eventually leading to depressive-like behaviors and cognitive impairment in mice. The abnormal activation of NLRP3 inflammasome could be restored by ERS blocker 4-phenyl butyric acid (PBA), thus reducing neuronal damage, and ameliorating depressive-like behaviors and cognitive disorder in mice.

CONCLUSION

Our study demonstrates a previously unknown link between ERS and NLRP3 inflammasome in CUMS mice. The ERS-NLRP3 signaling pathway may be activated by CUMS, potentially resulting in mice exhibiting depressive-like behaviors and cognitive dysfunction. Theoretical foundations for elucidating the pathogenesis of depression, as well as its prevention and treatment, will be established through the results.

Gut microbiota: a novel target for exercise-mediated regulation of NLRP3 inflammasome activation

The NOD-like receptor family pyrin domain-containing 3 (NLRP3) is a key pattern recognition receptor in the innate immune system. Its overactivation leads to the production of pro-inflammatory cytokines, such as IL-1β and IL-18, which contribute to the development and progression of various diseases. In recent years, evidence has shown that gut microbiota plays an important role in regulating the activation of NLRP3 inflammasome. Variations in the function and composition of gut microbiota can directly or indirectly influence NLRP3 inflammasome activation by influencing bacterial components and gut microbiota metabolites. Additionally, exercise has been shown to effectively reduce NLRP3 inflammasome overactivation while promoting beneficial changes in gut microbiota. This suggests that gut microbiota may play a key role in mediating the effects of exercise on NLRP3 inflammasome regulation. This review explores the impact of exercise on gut microbiota and NLRP3 inflammasome activation, and examines the mechanisms through which gut microbiota mediates the anti-inflammatory effects of exercise, providing new avenues for research.

1,3-butanediol administration as an alternative strategy to calorie restriction for neuroprotection - Insights into modulation of stress response in hippocampus of healthy rats

Ketogenic diet has a wide range of beneficial effects but presents practical limitations due to its low compliance, hence dietary supplements have been developed to induce ketosis without nutrient deprivation. The alcohol 1,3-butanediol (BD) is a promising molecule for its ability to induce ketosis, but its effects on brain have been investigated so far only in disease models, but never in physiological conditions. To support BD use to preserve brain health, the analysis of its activity is mandatory. Therefore, we investigated, in healthy rats, the effect of a fourteen-days BD-administration on the hippocampus, an area particularly vulnerable to oxidative and inflammatory damage. Since BD treatment has been reported to reduce energy intake, results were compared with those obtained from rats undergoing a restricted dietary regimen, isoenergetic with BD group (pair fed, PF). Reduced pro-inflammatory signaling pathways and glial activation were revealed in hippocampus of BD treated rats in comparison to control (C) and PF groups. ROS content and the extent of protein oxidative damage were lower in BD and PF groups than in C. Interestingly, higher amounts of nuclear factor erythroid 2-related factor 2 (Nrf2), decreased level of lipid hydroperoxides, lower susceptibility to oxidative insult, higher amounts of superoxide dismutase-2, glutathione reductase and glutathione peroxidase (GPx), and increased GPx activity were observed in BD animals. BD administration, but not dietary restriction, attenuated endoplasmic reticulum stress, reduced autophagic response activation, and was associated with an increase of both the neurotrophin BDNF and pre-synaptic proteins synaptophysin and synaptotagmin. Our results highlight that BD plays a neuroprotective role in healthy conditions, thus emerging as an effective strategy to support brain function without the need of implementing ketogenic nutritional interventions.

Ethanol modulates astrocyte activation and neuroinflammation via miR-339/NLRP6 inflammasome signaling

Alcohol is the most abused substance among adolescents and has a profound impact on health, society, and the economy. Alcohol intoxication is linked to neuroinflammation and neuronal damage, which result in behavioral alterations such as motor dysfunction, neuronal injury, cognitive deficits, and inflammation. Alcohol-induced neuroinflammation is associated with the activation of central nervous system cells, including astrocytes, and the release of proinflammatory cytokines. In this study, we investigated the role of the NLRP6 inflammasome signaling pathway in inducing cellular activation and neuroinflammation in human primary astrocytes exposed to ethanol. Our results demonstrated that ethanol upregulates the expression of NLRP6 inflammasome signaling mediators, including NLRP6, caspase 1, and proinflammatory cytokines IL-1β and IL-18, in human primary astrocytes. Gene silencing studies using NLRP6 siRNA further validate ethanol-mediated activation of NLRP6, cleavage of caspase 1, IL-1β, and IL-18 in human primary astrocytes. miR array analysis of ethanol-exposed human primary astrocytes reveals decreased levels of miR-339, accompanied by an upregulation of NLRP6 inflammasome signaling and astrocyte activation. Through bioinformatics analyses, Argonaute immunoprecipitation assays, and miR-339 overexpression experiments, we identify NLRP6 as a novel 3'-UTR target of miR-339. Overall, our findings confirmed the involvement of miR-339 in NLRP6 inflammasome signaling and its association with cellular activation and neuroinflammation in human primary astrocytes exposed to ethanol and provide novel insights highlighting a previously unrecognized mechanism in alcohol-induced neuroinflammation.

Association between window ventilation frequency and depressive symptoms among older Chinese adults

OBJECTIVES

Indoor air pollution exposure is harmful to people's physical and mental health, especially in the elderly population. Depressive symptoms are the most common mental health issue among elderly individuals. However, evidence linking the frequency of indoor natural ventilation to depressive symptoms in the elderly population is limited.

METHODS

This study included 7887 individuals 65 years and older from 2017 to 2018 the China Longitudinal Healthy Longevity Survey (CLHLS). The frequency of indoor window ventilation was measured as the self-reported times of ventilation of indoor window per week in each season, and the four seasons' scores were added up to calculate the annual ventilation frequency. Depressive symptoms were measured by the 10-item Center for Epidemiologic Studies Short Depression Scale (CESD). Using three models adjusted for demographic, socio-economic, health status, and environmental factors successively, the correlation between indoor window ventilation frequency and depressive symptoms was verified through logistic regression.

RESULTS

Among the 7887 elderly people included in this study, 1952 (24.7 %) had depressive symptoms. In the fully adjusted model, compared with the lower indoor annual ventilation frequency group, high indoor annual ventilation frequency group was significantly associated with a 33 % (OR: 0.67, 95%CI: 0.51-0.88) lower probability of depressive symptoms. Subgroup analysis and sensitivity analysis yielded similar results.

CONCLUSIONS

High frequency of window ventilation is significantly associated with the lower risk of depressive symptoms in Chinese individuals aged 65 and older. This result provides strong evidence for health intervention and policy formulation.

Gut microbiota dysbiosis induced by alcohol exposure in pubertal and adult mice

Alcohol intake causes many diseases including neuropsychiatric symptoms, nutritional deficiency, progressive pancreatitis, liver cirrhosis, and ischemic heart disease. The gut microbiota changes significantly after alcohol exposure. Alcohol consumption tends to increase in underage and young people, but the feature of the gut microbiota in puberty remains largely unexplored. In this study, we conducted alcohol-exposed pubertal and adult mice model to investigate the intestinal damage and gut microbiota change. Interestingly, the responses of pubertal mice and adult mice after alcohol exposure were different. We found that alcohol dehydrogenase decreased and aldehyde dehydrogenase increased in the liver of pubertal mice, thus reducing the accumulation of toxic acetaldehyde. Furthermore, alcohol exposure caused less intestinal injury in pubertal mice. Through the analysis of metagenome assembly genome, we obtained many unrecognized bacterial genomes. Limosillactobacillus reuteri (cluster_56) and Lactobacillus intestinalis (cluster_57) were assembled from the samples of pubertal mice, which were involved in the production of indole acetic acid and the transformation of bile acids in response to alcohol exposure. This study provided a new insight to investigate the gut microbiota change and explained the difference of the gut microbiota after alcohol exposure between pubertal mice and adult mice.

IMPORTANCE

This study elucidates the significant impact of alcohol exposure on the gut microbiota and metabolic pathways in mice, highlighting the differential responses between adolescent and adult stages. Alcohol exposure was found to damage the intestinal barrier, alter the microbial composition by decreasing beneficial bacteria like Lactobacillus, and increase harmful bacteria such as Alistipes. The study also discovered unique microbial changes and resilience in pubertal mice. Species-level metagenomic analysis revealed specific microbial taxa and metabolic functions affected by alcohol. Metagenome-assembled genomes (MAGs) found many species that could not be annotated by conventional methods including many members of Lachnospiraceae, greatly expanding our understanding of the gut microbiota composition. These findings underscore the need for further research on alcohol's effects on various organs and the implications of microbial metabolites on disease progression.

Is anxiety and depression transmissible? Depressed mother rats transmit anxiety- and depression-like phenotypes to cohabited rat pups through gut microbiota assimilation

OBJECTIVE

This study is to investigate the role of gut microbiota transmission in the development of anxiety/depression in offspring exposed to maternal depression.

METHOD

Offspring rats were cohabitated with their depressed mother or father rats (which exposed to chronic unpredictable mild stress (CUMS)) for 2, 4, and 6 months, the anxiety- and depression-like behaviors, and interaction/caring activities between mother/father and their pups were detected. The gut microbiota composition and its relationship with behaviors were analyzed. Fecal microbiota transplantation (FMT) was performed to establish the gut microbiota of depressed/normal mother rats in the offspring rats to further confirm the role of "depressive gut microbiota" transmission in mediating the anxiety/depression in the pups.

RESULTS

Anxiety and depression phenotypes can be transmitted from depressed mother rats to their cohabited offspring. Frequent interactions and gut microbiota assimilation were observed between rat mothers and their pups. Remodeling of the gut microbiota in pups by FMT could induce or attenuate anxiety- and depression-like phenotypes depending on the origin of the fecal microbiota. By comparison, the pups cohabiting with depressed father rats exhibited milder anxiety and depression.

CONCLUSIONS

These data together support that depressed mothers can transmit anxiety/depression to their pups through gut microbiota assimilation, which is related to frequent interactions. Our study reinforces the significance of mental health of mothers in preventing the occurrence of childhood anxiety and depression, and pointing out the possibility of remodeling intestinal microbiota as an effective therapeutic approach for treating anxiety/depression in children.

Dysregulation of the Gut Microbiota Contributes to Sevoflurane-Induced Cognitive Dysfunction in Aged Mice by Activating the NLRP3 Inflammasome

Postoperative cognitive dysfunction (POCD), a common complication in elderly patients after surgery, seriously affects patients' quality of life. Long-term or repeated inhalation of sevoflurane can cause neuroinflammation, which is a risk factor for POCD. However, the underlying mechanism needs to be further explored. Recent research had revealed a correlation between neurological disorders and changes in the gut microbiota. Dysfunction of the gut microbiota is involved in the occurrence and development of central nervous system diseases. Here, we found that cognitive dysfunction in aged mice induced by sevoflurane exposure (3%, 2 hours daily, for 3 days) was related to gut microbiota dysbiosis, while probiotics improved cognitive function by alleviating dysbiosis. Sevoflurane caused a significant decrease in the abundance of Akkermansia (P<0.05), while probiotics restored the abundance of Akkermansia. Compared to those in the control group, sevoflurane significantly increased the expression of NLRP3 inflammasome-associated proteins in the gut and brain in the sevoflurane-exposed group, thus causing neuroinflammation and synaptic damage, which probiotics can mitigate (con vs. sev, P < 0.01; p+sev vs. sev, P < 0.05). In conclusion, for the first time, our study revealed that dysbiosis of the gut microbiota caused by sevoflurane anesthesia contributes to the NLRP3 inflammasome-mediated neuroinflammation and cognitive dysfunction from the perspective of the gut-brain axis. Perhaps postoperative cognitive impairment in elderly patients can be alleviated or even prevented by regulating the gut microbiota. This study provides new insights and methods for the prevention and treatment of cognitive impairment induced by sevoflurane.

Vinegar-processed Schisandra Chinensis enhanced therapeutic effects on colitis-induced depression through tryptophan metabolism

BACKGROUND

Ulcerative colitis (UC) is an inflammatory bowel disease characterized by its incurable nature and undefined etiology, which is often accompanied by a high prevalence of comorbid depression. The gut-brain axis has emerged as a promising treatment target in recent years.

PURPOSE

This study aimed to investigate how vinegar-processed Schisandra Chinensis (VSC) enhances therapeutic effects on depressive behavior in chronic UC mice.

METHODS

A chronic UC model was induced in mice using dextran sulfate sodium. The therapeutic effects of both raw and vinegar-processed Schisandra Chinensis on UC and associated depressive symptoms were assessed. Colonic mucosal damage was evaluated using hematoxylin and eosin (H&E) and Alcian blue staining. The integrity of the blood-brain barrier (BBB) and synaptic structures was visualized via transmission electron microscopy (TEM). Enzyme-linked immunosorbent assay (ELISA) was employed to quantify inflammatory cytokine levels in the colon, serum, and brain, while western blotting was performed for protein expression analysis. Additionally, metagenomic analysis was conducted to investigate gut microbiota composition. Nissl staining and immunofluorescence were used to assess hippocampal neuronal damage, and behavioral assessments including the morris water maze, open field test, forced swimming test and tail suspension test, were implemented to evaluate depressive states. Serum metabolites were analyzed using UPLC-MS/MS.

RESULTS

Both raw and vinegar-processed Schisandra Chinensis significantly upregulated aryl hydrocarbon receptor (AhR), inhibited NF-κB p-p65 activation, and reduced levels of pro-inflammatory cytokine. These treatments also enhanced the expression of tight junction proteins, restored colonic mucosal and BBB integrity, alleviated damage to hippocampal neurons, and improved synaptic structure. Behavioral assessments indicated that VSC was particularly effective in ameliorating depressive-like behaviors in chronic UC mice. In the gut, both treatments reshaped the gut microbial composition, restoring the relative abundance of Duncaniella, Candidatus_Amulumruptor, Alistipes, Parabacteroides, Lachnospiraceae_bacterium, uncultured_Bacteroides_sp., Candidatus_Amulumruptor_caecigallinarius, with VSC showing more pronounced effects. Serum metabolomics revealed an increase in tryptophan levels and a decrease in kynurenine and xanthurenic acid levels with VSC, indicating that tryptophan metabolism shifted from the kynurenine pathway to the 5-HT or indole pathway. However, this phenomenon did not occur with Schisandra Chinensis (SC).

CONCLUSION

This study demonstrated that the disruption of tryptophan metabolic balance served as a biological mechanism underlying the occurrence of depressive behaviors induced by UC. The application of SC following vinegar processing enhanced its regulatory effects on gut microbiota and tryptophan metabolism. This findings provided a new insight for the clinical management of gut-brain comorbidities.

Limosilactobacillus-related 3-OMDP as a potential therapeutic target for depression

OBJECTIVE

Gut microbiota was closely involved in the pathogenesis of depression, but the underlying molecular mechanisms in depression remained unclear. This study was conducted to investigate the relationship between neurotransmitters/inflammatory factors and gut microbiota in depressed mice.

MATERIALS AND METHODS

A chronic social defeat stress (CSDS) depression model was established. Gut microbial composition was detected in faeces, neurotransmitters were detected in faeces, colon, blood and hippocampus, and inflammatory factors were detected in hippocampus. After a key neurotransmitter was identified, intervention experiment was conducted to explore whether it could improve depressive-like behaviours.

RESULTS

Six differential genera in faeces, 14 differential neurotransmitters in gut-brain axis, and two differential inflammatory factors (interleukin-1 beta (IL-1β) and interleukin-6 (IL-6)) in hippocampus were identified in depressed mice. There were significant correlations among differential genera, differential neurotransmitters and IL-1β/IL-6. Among these differential neurotransmitters, 3-O-Methyldopa (3-OMDP) was found to be consistently decreased in faeces, colon, blood and hippocampus, and 3-OMDP was significantly correlated to Limosilactobacillus and IL-1β. After receiving 3-OMDP, the depressive-like behaviours in depressed mice were improved and the increased IL-1β/IL-6 levels were reversed.

CONCLUSIONS

These results indicated that gut microbiota might affect host's inflammation levels in brain through regulating neurotransmitters, eventually leading to the onset of depression. 'Limosilactobacillus-3-OMDP-IL-1β/IL-6' might be a potential pathway in the crosstalk of gut and brain, and 3-OMDP held the promise as a therapeutic target for depression.

Probiotics alleviate chronic ethanol exposure-induced anxiety-like behavior and hippocampal neuroinflammation in male mice through gut microbiota-derived extracellular vesicles

BACKGROUND

Probiotics can colonize both the human and animal bodies and consist of active microorganisms that are beneficial to health. The use of probiotics has been shown to alleviate certain neurological diseases and disturbances in gut microbiota resulting from chronic ethanol exposure. Research indicates that probiotics can influence the nervous system via the microbial-gut-brain axis, wherein extracellular vesicles secreted by the gut microbiota play a significant role in this process.

RESULTS

In this study, we first established a 30-day ethanol exposure and probiotic gavage mouse model, both of which influenced behavior and the composition of gut microbiota. We then extracted gut microbiota-derived extracellular vesicles from the feces of these model mice and injected them into new mice via the tail vein to assess the role of each set of extracellular vesicles. The results indicated that the extracellular vesicles derived from the intestinal microbiota in the ethanol group induced anxiety-like behavior and hippocampal neuroinflammation in the recipient mice. In contrast, the extracellular vesicles secreted by the gut microbiota from the probiotic group mitigated the anxiety-like behavior and neuroinflammation induced by ethanol-influenced extracellular vesicles.

CONCLUSIONS

Our study demonstrates that extracellular vesicles secreted by the gut microbiota can influence the nervous system via the microbial-gut-brain axis. Furthermore, we found that the extracellular vesicles secreted by the gut microbiota from the probiotic group exert a beneficial therapeutic effect on anxiety and hippocampal neuroinflammation.

AdipoRon exerts an antidepressant effect by inhibiting NLRP3 inflammasome activation in microglia via promoting mitophagy

Depression is a serious mental disorder that threatens patients' physical and mental health worldwide. The activation of the NLR family pyrin domain-containing 3 (NLRP3) inflammasome is essential for microglia-mediated neuroinflammation and neuronal damage in depression. Numerous pathophysiological factors, such as mitochondrial dysfunction and impaired mitophagy, have an essential role in activating the NLRP3 inflammasome. AdipoRon is a potent adiponectin receptor agonist; however, its antidepressant effects have not been thoroughly investigated. In this study, we found that AdipoRon ameliorated depression-like behavior and neuronal damage induced by chronic unpredictable mild stress (CUMS). Further research demonstrated that AdipoRon inhibited the activation of the NLRP3 inflammasome and protected hippocampal neurons from microglial cytotoxicity by promoting mitophagy, increasing the clearance of damaged mitochondria, and reducing mtROS accumulation. Importantly, inhibition of mitophagy attenuated the antidepressant and neuroprotective effects of AdipoRon. Overall, these findings indicate that AdipoRon alleviates depression by inhibiting NLRP3 inflammasome activation in microglia via improving mitophagy.

Dazhu Hongjingtian injection attenuated alcohol-induced depressive symptoms by inhibiting hippocampus oxidative stress and inflammation through Nrf2/HO-1/NLRP3 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Alcoholic depression, a disorder of the central nervous system, is characterized by alcohol abuse, which causes blood-brain barrier disruption and oxidative damage in the brain. The rhizome of Rhodiola crenulate, from which Dazhu Hongjingtian Injection (DZHJTI) is derived, has been traditionally employed in ethnopharmacology to treat neurological disorders due to its neuroprotective, anti-inflammatory, and antioxidant properties. However, the exact mechanism by which DZHJTI alleviates alcoholic depression remains unclear.

AIM OF THE STUDY

This study aimed to investigate the antidepressant effects of DZHJTI and its underlying mechanisms in a mouse model of alcohol-induced depression.

MATERIALS AND METHODS

A model of alcoholic depression was established using C57BL/6J mice, and the effects of DZHJTI on depression-like behaviors induced by alcohol exposure were assessed through behavioral experiments. Histopathological examination was conducted to observe nerve cell damage and microglial activation in the hippocampal region. Oxidative stress indices in the hippocampus, inflammatory factors, and serum levels of dopamine (DA) and 5-hydroxytryptamine (5-HT) were measured using ELISA. Expression of proteins related to the Nrf2/HO-1/NLRP3 signaling pathway was determined by Western blot analysis.

RESULTS

DZHJTI attenuated depression-like behaviors, neuronal cell damage, oxidative stress levels, inflammatory responses, and microglial activation. It also restored levels of brain-derived neurotrophic factor, brain myelin basic protein, DA, and 5-HT in mice with chronic alcohol exposure. After DZHJTI treatment, the expressions of Nuclear Respiratory Factor 2 (Nrf2) and Heme Oxygenase-1 (HO-1) increased in the hippocampus, whereas the levels of NOD-like receptor thermal protein domain-associated protein 3 (NLRP3), apoptosis-associated speck-like protein containing CARD, cleaved caspase-1, interleukin (IL)-1β, and IL-18 decreased.

CONCLUSIONS

DZHJTI ameliorates alcohol-induced depressive symptoms in mice through its antioxidant and anti-inflammatory effects, involving mechanisms associated with the Nrf2/HO-1/NLRP3 signaling pathway. This study highlights the potential of DZHJTI as a therapeutic option for alcohol-related depression and suggests the scope for future research to further elucidate its mechanisms and broader clinical applications.

Gut microbiota modulates depressive-like behaviors induced by chronic ethanol exposure through short-chain fatty acids

BACKGROUND

Chronic ethanol exposure (CEE) is recognized as an important risk factor for depression, and the gut-brain axis has emerged as a key mechanism underlying chronic ethanol exposure-induced anxiety and depression-like behaviors. Short-chain fatty acids (SCFAs), which are the key metabolites generated by gut microbiota from insoluble dietary fiber, exert protective roles on the central nervous system, including the reduction of neuroinflammation. However, the link between gut microbial disturbances caused by chronic ethanol exposure, production of SCFAs, and anxiety and depression-like behaviors remains unclear.

METHODS

Initially, a 90-day chronic ethanol exposure model was established, followed by fecal microbiota transplantation model, which was supplemented with SCFAs via gavage. Anxiety and depression-like behaviors were determined by open field test, forced swim test, and elevated plus-maze. Serum and intestinal SCFAs levels were quantified using GC-MS. Changes in related indicators, including the intestinal barrier, intestinal inflammation, neuroinflammation, neurotrophy, and nerve damage, were detected using Western blotting, immunofluorescence, and Nissl staining.

RESULTS

Chronic ethanol exposure disrupted with gut microbial homeostasis, reduced the production of SCFAs, and led to anxiety and depression-like behaviors. Recipient mice transplanted with fecal microbiota that had been affected by chronic ethanol exposure exhibited impaired intestinal structure and function, low levels of SCFAs, intestinal inflammation, activation of neuroinflammation, a compromised blood-brain barrier, neurotrophic defects, alterations in the GABA system, anxiety and depression-like behaviors. Notably, the negative effects observed in these recipient mice were significantly alleviated through the supplementation of SCFAs.

CONCLUSION

SCFAs not only mitigate damage to intestinal structure and function but also alleviate various lesions in the central nervous system, such as neuroinflammation, and reduce anxiety and depression-like behaviors, which were triggered by transplantation with fecal microbiota that had been affected by chronic ethanol exposure, adding more support that SCFAs serve as a bridge between the gut and the brain.

Mesenchymal stem cells improve depressive disorder via inhibiting the inflammatory polarization of microglia

Depressive disorder (DD) ranks among the most prevalent, burdensome, and costly psychiatric conditions globally. It manifests through a range of emotional, cognitive, somatic, and behavioral symptoms. Mesenchymal Stem Cells (MSCs) have garnered significant attention due to their therapeutic potential via immunomodulation in neurological disorders. Our research indicates that MSCs treatment demonstrates a notable effect on a Chronic Unpredictable Mild Stress (CUMS)-induced DD model in mice, surpassing even Fluoxetine in its antidepressant efficacy. MSCs mitigate DD by inhibiting central nervous system inflammation and facilitating the conversion of microglial cells into an Arg1high anti-inflammatory state. The MSCs-derived TGF-β1 is crucial for this Arg1high microglial cell transformation in DD treatment.

Lactobacillus rhamnosus GG attenuates depression-like behaviour and cognitive deficits in chronic ethanol exposure mice by down-regulating systemic inflammatory factors

Ethanol can directly or indirectly lead to cognitive and mental disorders. The long-term intake of alcohol can directly affect the distribution of gut microbiota. Lactobacillus rhamnosus GG (LGG) is a natural bacterium isolated from healthy human intestines that has the function of preventing cytokine-induced cell apoptosis and protecting cell barriers. However, the regulatory effect of LGG on cognitive and mental disorders caused by chronic ethanol exposure (CEE) is still unclear. In this study, we established a CEE mouse model through free alcohol consumption and added LGG or antibiotics in the later stages of the model. Sequencing analysis of the 16S rRNA gene showed that CEE resulted in a decrease in the abundance and diversity of mouse gut microbial communities accompanied by alterations in the relative abundance of multiple enterobacterial genera. The use of LGG and antibiotics alleviated the depression-like behaviour and cognitive impairment of CEE-induced mice, reduced expression of inflammatory factors such as interleukin (IL)-6, IL-1β and tumour necrosis factor (TNF)-α in the ileum, serum and brain and increased the expression of synaptophysin (SYN), postsynaptic density protein-95 (PSD-95) and brain-derived neurotrophic factor (BDNF) in the hippocampus. Together, LGG can alleviate depression-like behaviour caused by CEE in mice while also improving cognitive and memory functions through reducing peripheral and nervous system inflammation factors and balancing gut microbiota.

Immunological mechanisms in steatotic liver diseases: An overview and clinical perspectives

Steatotic liver diseases (SLD) are the principal worldwide cause of cirrhosis and end-stage liver cancer, affecting nearly a quarter of the global population. SLD includes metabolic dysfunction-associated alcoholic liver disease (MetALD) and metabolic dysfunction-associated steatotic liver disease (MASLD), resulting in asymptomatic liver steatosis, fibrosis, cirrhosis and associated complications. The immune processes include gut dysbiosis, adiposeliver organ crosstalk, hepatocyte death and immune cell-mediated inflammatory processes. Notably, various immune cells such as B cells, plasma cells, dendritic cells, conventional CD4+ and CD8+ T cells, innate-like T cells, platelets, neutrophils and macrophages play vital roles in the development of MetALD and MASLD. Immunological modulations targeting hepatocyte death, inflammatory reactions and gut microbiome include N-acetylcysteine, selonsertib, F-652, prednisone, pentoxifylline, anakinra, JKB-121, HA35, obeticholic acid, probiotics, prebiotics, antibiotics and fecal microbiota transplantation. Understanding the immunological mechanisms underlying SLD is crucial for advancing clinical therapeutic strategies.

Gut microbiota-NLRP3 inflammasome crosstalk in metabolic dysfunction-associated steatotic liver disease

Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease associated with metabolic dysfunction, ranging from hepatic steatosis with or without mild inflammation to nonalcoholic steatohepatitis, which can rapidly progress to liver fibrosis and even liver cancer. In 2023, after several rounds of Delphi surveys, a new consensus recommended renaming NAFLD as metabolic dysfunction-associated steatotic liver disease (MASLD). Ninety-nine percent of NAFLD patients meet the new MASLD criteria related to metabolic cardiovascular risk factors under the "multiple parallel hits" of lipotoxicity, insulin resistance (IR), a proinflammatory diet, and an intestinal microbiota disorder, and previous research on NAFLD remains valid. The NLRP3 inflammasome, a well-known member of the pattern recognition receptor (PRR) family, can be activated by danger signals transmitted by pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs), as well as cytokines involved in immune and inflammatory responses. The activation of the NLRP3 inflammasome pathway by MASLD triggers the production of the inflammatory cytokines IL-1β and IL-18. In MASLD, while changes in the composition and metabolites of the intestinal microbiota occur, the disrupted intestinal microbiota can also generate the inflammatory cytokines IL-1β and IL-18 by damaging the intestinal barrier, negatively regulating the liver on the gut-liver axis, and further aggravating MASLD. Therefore, modulating the gut-microbiota-liver axis through the NLRP3 inflammasome may emerge as a novel therapeutic approach for MASLD patients. In this article, we review the evidence regarding the functions of the NLRP3 inflammasome and the intestinal microbiota in MASLD, as well as their interactions in this disease.

Balancing the mind: Toward a complete picture of the interplay between gut microbiota, inflammation and major depressive disorder

The intricate interplay existing between gut microbiota and homeostasis extends to the realm of the brain, where emerging research underscores the significant impact of the microbiota on mood regulation and overall neurological well-being and vice-versa, with inflammation playing a pivotal role in mediating these complex interactions. This comprehensive review explores the complex interplay between inflammation, alterations in gut microbiota, and their impact on major depressive disorder (MDD). It provides a cohesive framework for the puzzle pieces of this triad, emphasizing recent advancements in understanding the gut microbiota and inflammatory states' contribution to the depressive features. Two directions of communication between the gut and the brain in depression are discussed, with inflammation serving as a potential modulator. Therapeutic implications were discussed as well, drawing insights from interventional studies on the effects of probiotics on gut bacterial composition and depressive symptoms. Ultimately, this review will attempt to provide a complete and valuable framework for future research and therapeutic interventions in MDD.

Prenatal Stress and Ethanol Exposure: Microbiota-Induced Immune Dysregulation and Psychiatric Risks

Changes in maternal gut microbiota due to stress and/or ethanol exposure can have lasting effects on offspring's health, particularly regarding immunity, inflammation response, and susceptibility to psychiatric disorders. The literature search for this review was conducted using PubMed and Scopus, employing keywords and phrases related to maternal stress, ethanol exposure, gut microbiota, microbiome, gut-brain axis, diet, dysbiosis, progesterone, placenta, prenatal development, immunity, inflammation, and depression to identify relevant studies in both preclinical and human research. Only a limited number of reviews were included to support the arguments. The search encompassed studies from the 1990s to the present. This review begins by exploring the role of microbiota in modulating host health and disease. It then examines how disturbances in maternal microbiota can affect the offspring's immune system. The analysis continues by investigating the interplay between stress and dysbiosis, focusing on how prenatal maternal stress influences both maternal and offspring microbiota and its implications for susceptibility to depression. The review also considers the impact of ethanol consumption on gut dysbiosis, with an emphasis on the effects of prenatal ethanol exposure on both maternal and offspring microbiota. Finally, it is suggested that maternal gut microbiota dysbiosis may be significantly exacerbated by the combined effects of stress and ethanol exposure, leading to immune system dysfunction and chronic inflammation, which could increase the risk of depression in the offspring. These interactions underscore the potential for novel mental health interventions that address the gut-brain axis, especially in relation to maternal and offspring health.

Empagliflozin alleviates neuroinflammation by inhibiting astrocyte activation in the brain and regulating gut microbiota of high-fat diet mice

A high-fat diet can modify the composition of gut microbiota, resulting in dysbiosis. Changes in gut microbiota composition can lead to increased permeability of the gut barrier, allowing bacterial products like lipopolysaccharides (LPS) to enter circulation. This process can initiate systemic inflammation and contribute to neuroinflammation. Empagliflozin (EF), an SGLT2 inhibitor-type hypoglycemic drug, has been reported to treat neuroinflammation. However, there is a lack of evidence showing that EF regulates the gut microbiota axis to control neuroinflammation in HFD models. In this study, we explored whether EF could improve neuroinflammation caused by an HFD via regulation of the gut microbiota and the mechanism underlying this phenomenon. Our data revealed that EF alleviates pathological brain injury, reduces the reactive proliferation of astrocytes, and increases the expression of synaptophysin. In addition, the levels of inflammatory factors in hippocampal tissue were significantly decreased after EF intervention. Subsequently, the results of 16S rRNA gene sequencing showed that EF could change the microbial community structure of mice, indicating that the abundance of Lactococcus, Ligilactobacillus and other microbial populations decreased dramatically. Therefore, EF alleviates neuroinflammation by inhibiting gut microbiota-mediated astrocyte activation in the brains of high-fat diet-fed mice. Our study focused on the gut-brain axis, and broader research on neuroinflammation can provide a more holistic understanding of the mechanisms driving neurodegenerative diseases and inform the development of effective strategies to mitigate their impact on brain health. The results provide strong evidence supporting the larger clinical application of EF.

The gut microbiota-brain axis in neurological disorders

Previous studies have shown a bidirectional communication between human gut microbiota and the brain, known as the microbiota-gut-brain axis (MGBA). The MGBA influences the host's nervous system development, emotional regulation, and cognitive function through neurotransmitters, immune modulation, and metabolic pathways. Factors like diet, lifestyle, genetics, and environment shape the gut microbiota composition together. Most research have explored how gut microbiota regulates host physiology and its potential in preventing and treating neurological disorders. However, the individual heterogeneity of gut microbiota, strains playing a dominant role in neurological diseases, and the interactions of these microbial metabolites with the central/peripheral nervous systems still need exploration. This review summarizes the potential role of gut microbiota in driving neurodevelopmental disorders (autism spectrum disorder and attention deficit/hyperactivity disorder), neurodegenerative diseases (Alzheimer's and Parkinson's disease), and mood disorders (anxiety and depression) in recent years and discusses the current clinical and preclinical gut microbe-based interventions, including dietary intervention, probiotics, prebiotics, and fecal microbiota transplantation. It also puts forward the current insufficient research on gut microbiota in neurological disorders and provides a framework for further research on neurological disorders.

Gut microbiota dysbiosis contributes to depression-like behaviors via hippocampal NLRP3-mediated neuroinflammation in a postpartum depression mouse model

Postpartum depression (PPD) is a severe mental disorder that affects approximately 10---20% of women after childbirth. The precise mechanism underlying PPD pathogenesis remains elusive, thus limiting the development of therapeutics. Gut microbiota dysbiosis is considered to contribute to major depressive disorder. However, the associations between gut microbiota and PPD remain unanswered. Here, we established a mouse PPD model by sudden ovarian steroid withdrawal after hormone-simulated pseudopregnancy-human (HSP-H) in ovariectomy (OVX) mouse. Ovarian hormone withdrawal induced depression-like and anxiety-like behaviors and an altered gut microbiota composition. Fecal microbiota transplantation (FMT) from PPD mice to antibiotic cocktail-treated mice induced depression-like and anxiety-like behaviors and neuropathological changes in the hippocampus of the recipient mice. FMT from healthy mice to PPD mice attenuated the depression-like and anxiety-like behaviors as well as the inflammation mediated by the NOD-like receptor protein (NLRP)-3/caspase-1 signaling pathway both in the gut and the hippocampus, increased fecal short-chain fatty acids (SCFAs) levels and alleviated gut dysbiosis with increased SCFA-producing bacteria and reduced Akkermansia in the PPD mice. Also, downregulation of NLRP3 in the hippocampus mitigated depression-like behaviors in PPD mice and overexpression of NLRP3 in the hippocampal dentate gyrus induced depression-like behaviors in naïve female mice. Intriguingly, FMT from healthy mice failed to alleviate depression-like behaviors in PPD mice with NLRP3 overexpression in the hippocampus. Our results highlighted the NLRP3 inflammasome as a key component within the microbiota-gut-brain axis, suggesting that targeting the gut microbiota may be a therapeutic strategy for PPD.

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 Alleviates Intestinal Injury Induced by Extended Exposure to Light via Inhibiting the Activation of NLRP3 Inflammasome in Broiler Chickens

Light pollution is a potential risk for intestinal health in humans and animals. The gut microbiota is associated with the development of intestinal inflammation induced by extended exposure to light, but the underlying mechanism is not yet clear. The results of this study showed that extended exposure to light (18L:6D) damaged intestinal morphology, downregulated the expression of tight junction proteins, and upregulated the expression of the NLRP3 inflammasome and the concentration of pro-inflammatory cytokines. In addition, extended exposure to light significantly decreased the abundance of Lactobacillus, Butyricicoccus, and Sellimonas and increased the abundance of Bifidobacterium, unclassified Oscillospirales, Family_XIII_UCG-001, norank_f__norank_o__Clostridia_vadinBB60_group, and Defluviitaleaceae_UCG-01. Spearman correlation analysis indicated that gut microbiota dysbiosis positively correlated with the activation of the NLRP3 inflammasome. The above results indicated that extended exposure to light induced intestinal injury by NLRP3 inflammasome activation and gut microbiota dysbiosis. Antibiotic depletion intestinal microbiota treatment and cecal microbiota transplantation (CMT) from the 12L:12D group to 18L:6D group indicated that the gut microbiota alleviated intestinal inflammatory injury induced by extended exposure to light via inhibiting the activation of the NLRP3 inflammasome. In conclusion, our findings indicated that the gut microbiota can alleviate intestinal inflammation induced by extended exposure to light via inhibiting the activation of the NLRP3 inflammasome.

cGAS/STING signaling pathway-mediated microglial activation in the PFC underlies chronic ethanol exposure-induced anxiety-like behaviors in mice

Chronic ethanol consumption is a prevalent condition in contemporary society and exacerbates anxiety symptoms in healthy individuals. The activation of microglia, leading to neuroinflammatory responses, may serve as a significant precipitating factor; however, the precise molecular mechanisms underlying this phenomenon remain elusive. In this study, we initially confirmed that chronic ethanol exposure (CEE) induces anxiety-like behaviors in mice through open field test and elevated plus maze test. The cGAS/STING signaling pathway has been confirmed to exhibits a significant association with inflammatory signaling responses in both peripheral and central systems. Western blot analysis confirmed alterations in the cGAS/STING signaling pathway during CEE, including the upregulation of p-TBK1 and p-IRF3 proteins. Moreover, we observed microglial activation in the prefrontal cortex (PFC) of CEE mice, characterized by significant alterations in branching morphology and an increase in cell body size. Additionally, we observed that administration of CEE resulted in mitochondrial dysfunction within the PFC of mice, accompanied by a significant elevation in cytosolic mitochondrial DNA (mtDNA) levels. Furthermore, our findings revealed that the inhibition of STING by H-151 effectively alleviated anxiety-like behavior and suppressed microglial activation induced by CEE. Our study unveiled a significant association between anxiety-like behavior, microglial activation, inflammation, and mitochondria dysfunction during CEE.

Quercetin Inhibits Neuronal Pyroptosis and Ferroptosis by Modulating Microglial M1/M2 Polarization in Atherosclerosis

Atherosclerosis (AS) with iron and lipid overload and systemic inflammation is a risk factor for Alzheimer's disease. M1 macrophage/microglia participate in neuronal pyroptosis and recently have been reported to be the ferroptosis-resistant phenotype. Quercetin plays a prominent role in preventing and treating neuroinflammation, but the protective mechanism against neurodegeneration caused by iron deposition is poorly understood. ApoE-/- mice were fed a high-fat diet with or without quercetin treatment. The Morris water maze and novel object recognition tests were conducted to assess spatial learning and memory, and nonspatial recognition memory, respectively. Prussian blue and immunofluorescence staining were performed to assess the iron levels in the whole brain and in microglia, microglia polarization, and the degree of microglia/neuron ferroptosis. In vitro, we further explored the molecular biological alterations associated with microglial polarization, neuronal pyroptosis, and ferroptosis via Western blot, flow cytometry, CCK8, LDH, propidium iodide, and coculture system. We found that quercetin improved brain lesions and spatial learning and memory in AS mice. Iron deposition in the whole brain or microglia was reversed by the quercetin treatment. In the AS group, the colocalization of iNOS with Iba1 was increased, which was reversed by quercetin. However, the colocalization of iNOS with PTGS2/TfR was not increased in the AS group, suggesting a character resisting ferroptosis. Quercetin induced the expression of Arg-1 and decreased the colocalizations of Arg-1 with PTGS2/TfR. In vitro, ox-LDL combined with ferric ammonium citrate treatment (OF) significantly shifted the microglial M1/M2 phenotype balance and increased the levels of free iron, ROS, and lipid peroxides, which was reversed by quercetin. M1 phenotype induced by OF caused neuronal pyroptosis and was promoted to ferroptosis by L-NIL treatment, which contributed to neuronal ferroptosis as well. However, quercetin induced the M1 to M2 phenotype and inhibited M2 macrophages/microglia and neuron pyroptosis or ferroptosis. In summary, quercetin alleviated neuroinflammation by inducing the M1 to M2 phenotype to inhibit neuronal pyroptosis and protected neurons from ferroptosis, which may provide a new idea for neuroinflammation prevention and treatment.

Screening for depression and anxiety in lung cancer patients: A real-world study using GAD-7 and HADS

BACKGROUND

The psychological well-being of lung cancer patients is critical in-patient care but frequently overlooked.

METHODS

This study, employing a cross-sectional, questionnaire-based design, aimed to elucidate the prevalence of depressive and anxiety symptoms among lung cancer patients and identify associated risk factors. Participants' demographic, medical history, disease stage, and pathology were systematically collected. Psychological assessment was conducted using the general anxiety disorder-7 (GAD-7), patient health questionnaire-9 (PHQ-9), and hospital anxiety and depression scale (HADS). Statistical analyses were performed using SPSS software (version 25.0).

RESULTS

Out of 294 distributed questionnaires, 247 lung cancer patients were included in the final analysis, with an average completion time of 9.08 min. Notably, 32.4% exhibited depressive symptoms, while 30% displayed signs of anxiety. A significant correlation was found between both depressive and anxiety symptoms and a history of tobacco and alcohol consumption. Specifically, increased nicotine dependence and greater cumulative tobacco use were linked to higher rates of depressive symptoms, whereas cumulative alcohol consumption was associated with increased risks of anxiety symptoms.

CONCLUSION

The study affirms the feasibility of GAD-7, PHQ-9, and HADS as screening tools for depressive and anxiety symptoms in lung cancer patients. It further highlights tobacco and alcohol consumption as significant risk factors for poor psychological health in this population.

RIPK3 promotes neuronal survival by suppressing excitatory neurotransmission during CNS viral infection

While recent work has identified roles for immune mediators in the regulation of neural activity, the capacity for cell intrinsic innate immune signaling within neurons to influence neurotransmission remains poorly understood. However, the existing evidence linking immune signaling with neuronal function suggests that modulation of neurotransmission may serve previously undefined roles in host protection during infection of the central nervous system. Here, we identify a specialized function for RIPK3, a kinase traditionally associated with necroptotic cell death, in preserving neuronal survival during neurotropic flavivirus infection through the suppression of excitatory neurotransmission. We show that RIPK3 coordinates transcriptomic changes in neurons that suppress neuronal glutamate signaling, thereby desensitizing neurons to excitotoxic cell death. These effects occur independently of the traditional functions of RIPK3 in promoting necroptosis and inflammatory transcription. Instead, RIPK3 promotes phosphorylation of the key neuronal regulatory kinase CaMKII, which in turn activates the transcription factor CREB to drive a neuroprotective transcriptional program and suppress deleterious glutamatergic signaling. These findings identify an unexpected function for a canonical cell death protein in promoting neuronal survival during viral infection through the modulation of neuronal activity, highlighting new mechanisms of neuroimmune crosstalk.

Modulation of gut microbiota with probiotics as a strategy to counteract endogenous and exogenous neurotoxicity

The existing data demonstrate that probiotic supplementation affords protective effects against neurotoxicity of exogenous (e.g., metals, ethanol, propionic acid, aflatoxin B1, organic pollutants) and endogenous (e.g., LPS, glucose, Aβ, phospho-tau, α-synuclein) agents. Although the protective mechanisms of probiotic treatments differ between various neurotoxic agents, several key mechanisms at both the intestinal and brain levels seem inherent to all of them. Specifically, probiotic-induced improvement in gut microbiota diversity and taxonomic characteristics results in modulation of gut-derived metabolite production with increased secretion of SFCA. Moreover, modulation of gut microbiota results in inhibition of intestinal absorption of neurotoxic agents and their deposition in brain. Probiotics also maintain gut wall integrity and inhibit intestinal inflammation, thus reducing systemic levels of LPS. Centrally, probiotics ameliorate neurotoxin-induced neuroinflammation by decreasing LPS-induced TLR4/MyD88/NF-κB signaling and prevention of microglia activation. Neuroprotective mechanisms of probiotics also include inhibition of apoptosis and oxidative stress, at least partially by up-regulation of SIRT1 signaling. Moreover, probiotics reduce inhibitory effect of neurotoxic agents on BDNF expression, on neurogenesis, and on synaptic function. They can also reverse altered neurotransmitter metabolism and exert an antiamyloidogenic effect. The latter may be due to up-regulation of ADAM10 activity and down-regulation of presenilin 1 expression. Therefore, in view of the multiple mechanisms invoked for the neuroprotective effect of probiotics, as well as their high tolerance and safety, the use of probiotics should be considered as a therapeutic strategy for ameliorating adverse brain effects of various endogenous and exogenous agents.

The Landscape of Gut Microbiota and Its Metabolites: A Key to Understanding the Pathophysiology of Pattern in Chinese Medicine

Liver Stagnation and Spleen Deficiency (LSSD) is a Chinese Medicine (CM) pattern commonly observed in gastrointestinal (GI) diseases, yet its biological nature remains unknown. This limits the global use of CM medications for treating GI diseases. Recent studies emphasize the role of gut microbiota and their metabolites in the pathogenesis and treatment of LSSD-associated GI diseases. There is increasing evidence supporting that an altered gut microbiome in LSSD patients or animals contributes to GI and extra-intestinal symptoms and affects the effectiveness of CM therapies. The gut microbiota is considered to be an essential component of the biological basis of LSSD. This study aims to provide an overview of existing research findings and gaps for the pathophysiological study of LSSD from the gut microbiota perspective in order to understand the relationship between the CM pattern and disease progression and to optimize CM-based diagnosis, prevention, and therapy.

Akkermansia muciniphila Improves Depressive-Like Symptoms by Modulating the Level of 5-HT Neurotransmitters in the Gut and Brain of Mice

Accumulating evidence has suggested that the gut microbiome plays an important role in depression. Akkermansia muciniphila (AKK), a next-generation probiotic, shows a beneficial effect on immune and metabolic homeostasis. The relative abundance of AKK was found negatively correlated with depressive symptoms in both clinical and pre-clinical studies. To evaluate the potential antidepressant effect of AKK and explore the possible mechanism, we used chronic alcohol exposure and chronic unpredictable mild stress (CUMS) to induce depressive-like behaviors in mice. We found that oral AKK administration significantly reduced the immobility time in the force swimming test (FST) and tail suspension test (TST) in the mice with chronic alcohol exposure and the CUMS mice. The sucrose preference in the mice receiving AKK was significantly increased in the sucrose preference test (SPT). More importantly, AKK implantation significantly increased the level of 5-HT in the gut and PFC of both the alcohol exposure mice and the CUMS mice. Furthermore, AKK had inhibited the expression of SERT in the gut but not in the brain for both NIAAA and the CUMS model mice. Interestingly, the expression of cFos in enteric nerves in the gut significantly decreased after AKK administration. In conclusion, our study demonstrated the antidepressant effect of AKK in mice exposed to alcohol exposure and CUMS, with the potential mechanism that AKK implantation might lead to an increased level of 5-HT and inhibited SERT expression in the gut, and might alter the gut-to-brain signal through suppression of enteric nerves activation.

Increased expression of ER stress, inflammasome activation, and mitochondrial biogenesis-related genes in peripheral blood mononuclear cells in major depressive disorder

A subset of major depressive disorder (MDD) is characterized by immune system dysfunction, but the intracellular origin of these immune changes remains unclear. Here we tested the hypothesis that abnormalities in the endoplasmic reticulum (ER) stress, inflammasome activity and mitochondrial biogenesis contribute to the development of systemic inflammation in MDD. RT-qPCR was used to measure mRNA expression of key organellar genes from peripheral blood mononuclear cells (PBMCs) isolated from 186 MDD and 67 healthy control (HC) subjects. The comparative CT (2-ΔΔCT) method was applied to quantify mRNA expression using GAPDH as the reference gene. After controlling for age, sex, BMI, and medication status using linear regression models, expression of the inflammasome (NLRC4 and NLRP3) and the ER stress (XBP1u, XBP1s, and ATF4) genes was found to be significantly increased in the MDD versus the HC group. After excluding outliers, expression of the inflammasome genes was no longer statistically significant but expression of the ER stress genes (XBP1u, XBP1s, and ATF4) and the mitochondrial biogenesis gene, MFN2, was significantly increased in the MDD group. ASC and MFN2 were positively correlated with serum C-reactive protein concentrations. The altered expression of inflammasome activation, ER stress, and mitochondrial biogenesis pathway components suggest that dysfunction of these organelles may play a role in the pathogenesis of MDD.

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.