Intestinal permeability, gut-bacterial dysbiosis, and behavioral markers of alcohol-dependence severity

The interplay between gut microbiome, epigenetics, and substance use disorders: from molecular to clinical perspectives

Substance use disorders (SUDs) involve a complex series of central and peripheral pathologies, leading to impairments in cognitive, behavioral, and physiological processes. Emerging evidence indicates a more significant role for the microbiome-gut-brain axis (MGBA) in SUDs than previously recognized. The MGBA is interconnected with various body systems by producing numerous metabolites, most importantly short-chain fatty acids (SCFAs), cytokines, and neurotransmitters. These mediators influence the human body's epigenome and transcriptome. While numerous epigenetic alterations in different brain regions have been reported in SUD models, the intricate relationship between SUDs and the MGBA suggests that the gut microbiome may partially contribute to the underlying mechanisms of SUDs. Promising results have been observed with gut microbiome-directed interventions in patients with SUDs, including prebiotics, probiotics, antibiotics, and fecal microbiota transplantation. Nonetheless, the long-term epigenetic effects of these interventions remain unexplored. Moreover, various confounding factors and study limitations have hindered the identification of molecular mechanisms and clinical applications of gut microbiome interventions in SUDs. In the present review, we will (i) provide a comprehensive discussion on how the gut microbiome influences SUDs, with an emphasis on epigenetic alterations; (ii) discuss the current evidence on the bidirectional relationship of gut microbiome and SUDs, highlighting potential targets for intervention; and (iii) review recent advances in gut microbiome-directed therapies, along with their limitations and future directions.

Role of Intestinal Microbiome in Potentiating Inflammation and Predicting Outcomes in Alcohol-Associated Cirrhosis

In patients with alcohol-associated cirrhosis, the intestinal microbiome composition is disturbed with a loss of beneficial functions and an increase in pathobionts. These changes are associated with disease severity and decompensation, due in part to the exacerbation of liver inflammation by an altered microbiome. Microbes or their antigens may translocate to the liver to potentiate the activation of immune cells and thereby contribute to inflammatory injury. Moreover, microbes may aggravate liver disease through the production of toxins or metabolites, via the effects on bile acids or the intestinal immune system.

Utilizing blood inflammatory markers in alcohol studies: Considerations and recommendations for study design, sample collection, and data analysis

A large body of evidence suggests that heavy alcohol use is associated with dysregulated immune function, and that immune dysfunction in turn contributes to the pathophysiology of alcohol use disorder (AUD). As such, alcohol researchers have increasingly begun to include measurements of immune function-primarily peripheral circulating cytokines-in human studies, with the goal of testing associations with clinically-relevant behavioral measures. To date, findings and implications from these studies have been inconsistent and difficult to interpret, likely due to methodological challenges related to study design and implementation. In particular, the existing literature has demonstrated sample processing concerns, differences in assay methods, limited selection of analytes, and sample selection biases, all of which may contribute to inconsistent results. We briefly review the field, discuss these and other challenges, and propose guidance for designing studies on inflammation among heavy-drinking human participants. We note that conducting such studies requires appreciable consideration and planning, and ideally should involve an interdisciplinary team of experts, including immunologists, physiologists, and technical experts in bioassays, alongside experts in the field of interest (e.g., AUD). We highlight the importance of considering participant selection, analyte selection, sample collection, sample handling and storage, and assay methods, and suggest that the field move towards standardization of procedures and reporting. We propose that undertaking these changes in study design and implementation should produce consilience in findings and aid in our overall understanding of the complex relationship between alcohol exposure and immune function.

Xenon gas as a potential treatment for opioid use disorder, alcohol use disorder, and related disorders

Xenon gas is considered to be a safe anesthetic and imaging agent. Research on its other potentially beneficial effects suggests that xenon may have broad efficacy for treating health disorders. A number of reviews on xenon applications have been published, but none have focused on substance use disorders. Accordingly, we review xenon effects and targets relevant to the treatment of substance use disorders, with a focus on opioid use disorder and alcohol use disorder. We report that xenon inhaled at subsedative concentrations inhibits conditioned memory reconsolidation and opioid withdrawal symptoms. We review work by others reporting on the antidepressant, anxiolytic, and analgesic properties of xenon, which could diminish negative affective states and pain. We discuss research supporting the possibility that xenon could prevent analgesic- or stress-induced opioid tolerance and, by so doing could reduce the risk of developing opioid use disorder. The rapid kinetics, favorable safety and side effect profiles, and multitargeting capability of xenon suggest that it could be used as an ambulatory on-demand treatment to rapidly attenuate maladaptive memory, physical and affective withdrawal symptoms, and pain drivers of substance use disorders when they occur. Xenon may also have human immunodeficiency virus and oncology applications because its effects relevant to substance use disorders could be exploited to target human immunodeficiency virus reservoirs, human immunodeficiency virus protein-induced abnormalities, and cancers. Although xenon is expensive, low concentrations exert beneficial effects, and gas separation, recovery, and recycling advancements will lower xenon costs, increasing the economic feasibility of its therapeutic use. More research is needed to better understand the remarkable repertoire of effects of xenon and its potential therapeutic applications.

Microbial Approaches to Treat and Prevent Hepatic Encephalopathy

This review articulates the significance of the gut-liver-brain axis in understanding hepatic encephalopathy (HE), emphasizing the role of gut microbiota in influencing liver and brain health. Key treatments like lactulose, rifaximin, probiotics, and fecal microbiota transplantation are examined for their ability to modulate the gut microbiome, thereby mitigating HE symptoms through reduced neurotoxin production and enhanced gut barrier integrity. The synopsis highlights both established and emerging microbial therapies, presenting them as crucial to the management and future strategies of HE. This comprehensive overview explores current therapeutic approaches alongside promising future interventions, suggesting that personalized microbiome-focused treatments may revolutionize HE management.

Alcohol-Induced Changes in Brain Microstructure: Uncovering Novel Pathophysiological Mechanisms of AUD Using Translational DTI in Humans and Rodents

Alcohol use disorder (AUD) induces significant structural alterations in both gray and white matter, contributing to cognitive and functional impairments. This chapter presents a translational neuroimaging approach using diffusion-weighted MRI in humans and rodents to uncover novel pathophysiological mechanisms underlying AUD. Our studies demonstrate that increased mean diffusivity (MD) in gray matter reflects microglial reactivity and reduced extracellular space tortuosity, leading to enhanced volume neurotransmission. In white matter, fractional anisotropy (FA) reductions indicate progressive deterioration of key tracts, particularly the fimbria/fornix, linked to impaired cognitive flexibility. Importantly, longitudinal analyses reveal that white matter degeneration continues during early abstinence, suggesting that neuroinflammation and demyelination persist beyond alcohol cessation. Finally, we discuss how neuromodulatory interventions, such as transcranial magnetic stimulation (TMS), may promote recovery by enhancing myelin plasticity. These findings provide crucial insights into AUD's neurobiological underpinnings and highlight potential therapeutic targets for improving treatment outcomes.

Thomasclavelia ramosa and alcohol-related hepatocellular carcinoma: a microbial culturomics study

BACKGROUND

Gut microbiota alteration is implicated in the pathogenesis of alcoholic liver disease (ALD) and associated hepatocellular carcinoma (HCC). No study has characterized the dysbiosis associated with ALD by microbial culturomics, which certifies viability and allows pathobiont strain candidates to be characterized.

METHODS

A case-control study (n = 59) was conducted on patients with ALD without HCC (ALD-NoHCC, n = 16), ALD with HCC (ALD-HCC, n = 19) and controls (n = 24) groups. 16 S rRNA amplicon sequencing and microbial culturomics were used as complementary methods for gut microbiome profiling.

RESULTS

Compared to the control group, Thomasclavelia ramosa and Gemmiger formicilis were significantly increased in the ALD-HCC group and Mediterraneibacter gnavus was significantly increased in the ALD-NoHCC group using 16 S rRNA sequencing. By microbial culturomics, T. ramosa was detected in all ALD samples (100%), and the most enriched since cultivated in only a small proportion of controls (20%, p < 0.001).

CONCLUSIONS

T. ramosa, identified by culturomics and 16 rRNA sequencing, may be associated with ALD and ALD-HCC. These results highlight the potential role of T. ramosa in liver cancer, in line with its genotoxic properties and its tumor growth-promoting effect in gnotobiotic mice recently reported.

Lactobacillus fermentum LF31 Supplementation Reversed Atrophy Fibers in a Model of Myopathy Through the Modulation of IL-6, TNF-α, and Hsp60 Levels Enhancing Muscle Regeneration

Background/Objectives: Recent studies have highlighted the role of the gut-muscle axis, suggesting that modulation of the gut microbiota may indirectly benefit skeletal muscle. This study aimed to evaluate the effects of Lactobacillus fermentum (L. fermentum) supplementation in a model of muscle atrophy induced by chronic ethanol (EtOH) intake, focusing on inflammatory and antioxidant mechanisms. Methods: Sixty 12-month-old female Balb/c mice were divided randomly into three groups (n = 20/group): (1) Ethanol (EtOH) group, receiving ethanol daily for 8 and 12 weeks to induce systemic oxidative stress and inflammation; (2) Ethanol + Probiotic (EtOH + P) group, receiving both ethanol and L. fermentum supplementation for the same durations; and (3) Control (Ctrl) group, receiving only water. Muscle samples were analyzed for the fiber morphology, inflammatory markers, oxidative stress indicators, and satellite cell (SC) activity. All data were tested for normality using the Shapiro-Wilk test before applying a parametric analysis. A statistical analysis was performed using one-way ANOVA followed by a Bonferroni post-hoc test. The level of significance was set at p < 0.05. Results: EtOH exposure caused significant atrophy in all muscle fiber types (type I, IIa, and IIb), with the most pronounced effects on oxidative fibers. L. fermentum supplementation significantly reversed atrophy in type I and IIa fibers, accompanied by a significant reduction in IL-6, TNF-α, and Hsp60 expression levels, indicating the protective effect of L. fermentum against oxidative stress and inflammation. Moreover, the probiotic treatment increased MyoD expression in SCs, suggesting enhanced regenerative activity, without histological evidence of fibrosis. Conclusions: These findings suggest that L. fermentum supplementation could counteract EtOH-induced skeletal muscle damage by reducing inflammation and oxidative stress and promoting muscle repair, indicating its potential as an adjuvant, in the therapeutic strategy of models of muscle degeneration.

Associations of alcohol with the human gut microbiome and prospective health outcomes in the FINRISK 2002 cohort

BACKGROUND AND AIMS

Alcohol remains a global risk factor for non-communicable diseases with the gut microbiome emerging as a novel elucidator. We investigated how gut microbiome associates with alcohol on population level, if there is mediation reflected in health outcomes, and how functional potential is related.

METHODS

Our sample consisted of 4575 shallow-shotgun sequenced fecal samples from the FINRISK 2002 cohort (25-74yrs., 52.5% women). Alcohol (g 100% alcohol/week) use was self-reported. Diversity and differential species abundances were analyzed using multiple linear regression. Compositional differences were analyzed using PERMANOVA, and prospective associations with Cox-regression. Connections between alcohol, microbiome, inflammatory markers, and outcomes were assessed using serial mediation. Functional associations were assessed using KEGG-orthologies and multiple linear regression.

RESULTS

High-risk alcohol consumers had significantly lower bacterial diversity when compared to low-risk consumers (mean±SD:4.04±0.41 vs. 4.11±0.43, p = 9.56 × 10- 4). Alcohol also associated with significant shifts in overall composition (PERMANOVA; p ≤ 1.00 × 10- 4) and differential abundances of 344 species (ANCOM-BC2; q ≤ 0.05). These shifts were characterized by an increase in relative abundances of Gram-negative bacteria, the top genera of which were Bacteroides and Prevotella, and a decrease in putatively beneficial species in genera such as Lactobacillus, Bifidobacterium, and Akkermansia. Prospective associations with all-cause mortality (HR:1.12 [1.02-1.23]), and liver disease (HR:1.53 [1.22-1.92]) were observed. The association between alcohol and liver disease had a mediating link via a proinflammatory beta-diversity principal coordinate (OR:1.04 [1.001-1.10]). Functional associations were observed with 1643 KO-groups (q < 0.05, npositive=431, nnegative=1212). Antioxidative and gut integrity maintaining functions were diminished and lipopolysaccharide synthesis enriched.

CONCLUSIONS

Alcohol use is associated with community-level shifts in composition towards enriched Gram-negative bacteria, and diminished levels of putatively beneficial bacteria. Alcohol use associates with a proinflammatory gut microbiome profile that mediates alcohol's effect on incident liver disease risk, possibly via increased proliferation of endotoxins through the gut epithelial lining.

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.

Lactobacillus rhamnosus GG Combined with Metformin Alleviates Alcohol-Induced Liver Inflammation in Mice by Maintaining the Intestinal Barrier and Regulating Treg/Th1 Cells

Disturbances of the intestinal barrier enabling bacterial translocation exacerbate alcoholic liver disease (ALD). Lactobacillus rhamnosus GG (LGG) has been shown to exert beneficial effects in gut dysbiosis and chronic liver disease. The current study assessed the combined effects of LGG and metformin, which play roles in anti-inflammatory and immunoregulatory processes, in alcohol-induced liver disease mice. A diet comprising 5% alcohol for 4 weeks was employed to develop an alcohol-induced liver injury model. Mice were orally administered LGG, metformin, or their combination on alternate days. Tight junction (TJ) proteins, gut microbiome composition, inflammatory cytokines, Jun N-terminal kinase (JNK), and p38 signals were assessed. When compared with treatment with LGG or metformin alone, combined LGG and metformin treatment substantially lowered the symptoms of inflammation, steatosis, and elevated liver enzymes caused by alcohol administration. Combination treatment significantly improved intestinal microecology, evidenced by the recovery of intestinal flora, TJ proteins, and intestinal villi. Combination treatment reduced hepatic inflammation by blocking p38 and JNK phosphorylation. The combination of LGG and metformin corrected immune-response dysregulation and improved ALD by enhancing the intestinal microbiome, restoring mucosal barrier integrity, modulating immune function, and decreasing liver injury. These results provide information for the development of intestinal microbiota-based preventive and therapeutic agents against ALD.

Effect of inulin supplementation on fecal and blood metabolome in alcohol use disorder patients: A randomised, controlled dietary intervention

BACKGROUND AND AIMS

Alcohol Use Disorder (AUD) is a psychiatric disorder characterized notably by gut microbial dysbiosis and insufficient dietary fiber (DF) intake. This study aims to investigate the effect of DF placebo-controlled intervention in patients suffering from AUD during a three-week period of alcohol withdrawal, in order to discover microbial-derived metabolites that could be involved in metabolic and behavioral status.

METHODS

A randomized, double-blind, placebo-controlled study was performed with 50 AUD patients supplemented with inulin (prebiotic DF) or maltodextrin (placebo) during 17 days. Fecal microbiota composition, plasma and fecal metabolomics (liquid chromatography coupled to mass spectrometry), blood markers of inflammation and hepatic alterations, and psychological assessment (questionnaires) were analyzed before and after the intervention.

RESULTS

Fecal metabolomics revealed 14 metabolites significantly modified by inulin versus placebo treatment (increased N8-acetylspermidine and decreased indole-3-butyric acid, 5-amino valeric acid betaine (5-AVAB) and bile acids). Thirteen plasma metabolites differentiated both treatments (higher levels of long-chain fatty acids, medium-chain acylcarnitines and sphingomyelin species, and reduced 3-methylhistidine by inulin versus placebo). Fecal Lachnoclostridium correlated with 6 of the identified fecal metabolites, whereas plasma lipidic moieties positively correlated with fecal Ruminococcus torques group and Flavonifractor. Interestingly, parameters reflecting liver alterations inversely correlated with sphingomyelin (SM 36:2).

CONCLUSIONS

Three weeks of inulin supplementation during alcohol withdrawal leads to specific and different changes in the plasma and fecal metabolome of AUD patients, some of these gut microbiota-related metabolites being correlated with liver function.

TRIAL REGISTRATION

NCT03803709, https://clinicaltrials.gov/ct2/show/NCT03803709.

Structural and functional alteration of the gut microbiomes in ICU staff: a cross-sectional analysis

BACKGROUND

16S rRNA sequencing has revealed structural alterations in the gut microbiomes of medical workers, particularly those working in intensive care unit (ICU). This study aims to further compare the taxonomic and functional characteristics of gut microbiomes between ICU staff and non-medical individuals using metagenomic sequencing.

METHODS

A prospective cross-sectional cohort study was conducted, fecal samples from 39 individuals in each group-ICU staff and non-medical subjects were analyzed using metagenomic sequencing. PERMANOVA (using the adonis function) was employed to analyze the genus-level profiles and assess the impact of individual parameters on the gut microbiome. Multiple databases were utilized to annotate and compare the functional differences in gut microbiomes between the two groups.

RESULTS

We observed that ICU staff exhibited a significant decrease in gut microbiome diversity, characterized by a marked decline in Actinobacteria and a substantial increase in Bacteroides and Bacteroidaceae. CAZy annotation revealed a notable increase in carbohydrate-active enzymes within the ICU staff cohort. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis further indicated an elevated risk of endocrine and metabolic disorders, along with enhanced glycan biosynthesis and metabolism. Additionally, KEGG pathway enrichment analysis highlighted significant enrichment in cancer-related pathways. Analysis using the Virulence Factor Database (VFDB) showed a higher abundance of virulence factors associated with immune modulation, invasion, and antimicrobial activity/competitive advantage among ICU staff. Notably, no discernible difference in the presence of antibiotic resistance genes within the gut microbiomes was observed between the two groups. Importantly, all aforementioned differences demonstrated clear gender disparities.

CONCLUSIONS

Our findings indicated that ICU staff exhibited a reduction in gut microbiome diversity which was associated with an increase in virulence factors and carbohydrate-active enzymes, as well as with a heightened susceptibility to endocrine and metabolic diseases and cancers.

Baseline gut microbiome and metabolites are correlated with changes in alcohol consumption in participants in a randomized Zonisamide clinical trial

Development and severity of alcohol use disorder (AUD) has been linked to variations in gut microbiota and their associated metabolites in both animal and human studies. However, the involvement of the gut microbiome in alcohol consumption of individuals with AUD undergoing treatment remains unclear. To address this, stool samples (n = 32) were collected at screening (baseline) and trial completion from a double-blind, placebo-controlled trial of zonisamide in individuals with AUD. Alcohol consumption was measured both at baseline and endpoint of 16-week trial period. Fecal microbiome was analyzed via 16 S rRNA sequencing and metabolome via untargeted LC-MS. Both sex (p = 0.003) and psychotropic medication usage (p = 0.025) are associated with baseline microbiome composition. The relative abundance of 11 genera at baseline was correlated with percent drinking reduction (p.adj < 0.1). Overall microbiome community structure at baseline differed between high and low reducers of alcohol drinking (67-100% and 0-33% drinking reduction, respectively; p = 0.034). A positive relationship between baseline fecal GABA levels and percent drinking reduction (R = 0.43, p.adj < 0.07) was identified by microbiome function prediction and confirmed by ELISA and metabolomics. Metabolomics analysis also found 3-hydroxykynurenine, a neurotoxic intermediate metabolite of tryptophan, was negatively correlated with drinking reduction (p.adj = 0.047), and was over-represented in low reducers. These findings highlight importance of baseline microbiome and amino acid metabolites in drinking reduction in AUD participants undergoing zonisamide treatment. It may hold significant value as a predictive tool in clinical settings to better personalize intervention and improve reduction in alcohol consumption in future.

Yi Mai Granule Improves High-Fat Diet-Induced Nonalcoholic Fatty Liver Disease in Mice by Regulating Gut Microbiota and Metabolites

Yi Mai granule (YMG) is a traditional Chinese medicine (TCM) herbal decoction consisting of two TCM formulas: Gua-Lou-Ban-Xia decoction and Si-Jun-Zi decoction. YMG has shown clinical benefit in the treatment of nonalcoholic fatty liver disease (NAFLD), which may be due to its regulatory effects on lipid metabolism. Previous studies have highlighted the importance of the gut microbiota and its metabolites in the use of TCM. However, the effect of YMG on the gut microbiota in the treatment of NAFLD remains unclear. In this study, we established an NAFLD model in ApoE-/- mice and treated them with YMG. High-performance liquid chromatography was adopted to identify the chemical components of YMG. By mapping the candidate targets using network pharmacology, we found that the targets of the main components of YMG were significantly enriched in NAFLD-related pathways. Moreover, 16S rRNA gene sequencing revealed that YMG affected the constitution and metabolism of the gut microbiota in NAFLD model mice, including lipid and carbohydrate metabolism. Similarly, metabolites related to lipid and carbohydrate metabolism in mouse serum were significantly altered by YMG. The correlation heat map and network analyses showed that the gut microbiota and metabolites affected by YMG were closely related to the blood lipid content. Collectively, YMG may exert therapeutic effects by affecting the metabolism of gut microbiota, thus regulating lipid and carbohydrate metabolism. These findings offer novel insight into the pharmacological mechanism of YMG in the treatment of NAFLD and provide theoretical bases for its clinical applications.

Gut Microbiome Alterations, Mental Health, and Alcohol Consumption: Investigating the Gut-Brain Axis in Firefighters

Firefighters across the world face higher risks of occupational hazards, such as exposure to chemicals, extreme heat, traumatic stressors, and intense physical demands, which can increase their vulnerability to a range of psychological and physiological difficulties. These challenges include the risk of developing chronic stress, depression, and post-traumatic stress disorder (PTSD), potentially leading to detrimental negative coping patterns such as alcohol abuse. The consequent health implications impact both short-term and long-term health and well-being. This study aimed to explore the relationship between mental health status, alcohol consumption patterns, and gut microbiome alterations in firefighters from two different regions-America and Korea. By investigating these relationships, we hope to gain insights into how repeated exposure to severe stressors impacts gut health. Healthy male firefighters (ages 21-50) and controls (matched sex, geography, and age) were recruited via flyers and snowball sampling in the United States and South Korea, resulting in 203 participants (102 firefighters and 101 controls). Firefighters reported significantly higher PTSD symptoms and depression and drank 2.3 times more alcohol than the control group. American firefighters reported more drinking than Koreans. There was a significant correlation between higher alcohol consumption and the likelihood of witnessing deaths by suicide. However, there were no correlations between alcohol consumption and PTSD symptom severity. There were associations between alcohol consumption patterns and aspects of the gut microbiome. This study highlights the mental health challenges faced by firefighters, including elevated rates of PTSD, depression, and alcohol consumption, with specific microbial imbalances linked to PTSD and alcohol use, emphasizing the role of the gut-brain axis.

Role of duodenal mucosal resurfacing in controlling diabetes in rats

BACKGROUND

The duodenum plays a significant role in metabolic regulation, and thickened mucous membranes are associated with insulin resistance. Duodenal mucosal resurfacing (DMR), a new-style endoscopic procedure using hydrothermal energy to ablate this thickened layer, shows promise for enhancing glucose and lipid metabolism in type 2 diabetes (T2D) patients. However, the mechanisms driving these improvements remain largely unexplored.

AIM

To investigate the mechanisms by which DMR improves metabolic disorders using a rat model.

METHODS

Rats with T2D underwent a revised DMR procedure via a gastric incision using a specialized catheter to abrade the duodenal mucosa. The duodenum was evaluated using histology, immunofluorescence, and western blotting. Serum assays measured glucose, lipid profiles, lipopolysaccharide, and intestinal hormones, while the gut microbiota and metabolomics profiles were analyzed through 16S rRNA gene sequencing and ultra performance liquid chromatography-mass spectrum/mass spectrum, severally.

RESULTS

DMR significantly improved glucose and lipid metabolic disorders in T2D rats. It increased the serum levels of cholecystokinin, gastric inhibitory peptide, and glucagon-like peptide 1, and reduced the length and depth of duodenal villi and crypts. DMR also enhanced the intestinal barrier integrity and reduced lipopolysaccharide translocation. Additionally, DMR modified the gut microbiome and metabolome, particularly affecting the Blautia genus. Correlation analysis revealed significant links between the gut microbiota, metabolites, and T2D phenotypes.

CONCLUSION

This study illustrates that DMR addresses metabolic dysfunctions in T2D through multifaceted mechanisms, highlighting the potential role of the Blautia genus on T2D pathogenesis and DMR's therapeutic impact.

The causal relationships between iron status and sarcopenia in Europeans: a bidirectional two-sample Mendelian randomization study

BACKGROUND

Previous studies have indicated potential associations between metals, lifestyle factors, and sarcopenia. However, the specific causal relationships between iron status, lifestyle factors, and sarcopenia remain unclear. Therefore, we conducted a bidirectional two-sample Mendelian Randomization (MR) approach to investigate these relationships.

METHODS

The exposure variables included iron status, living alone, coffee intake, alcohol taken with meals, and moderate physical activity, while the outcome variable was sarcopenia, assessed by grip strength in both hands and usual walking pace. We employed the Weighted Median (WM), the Inverse Variance-Weighted (IVW), and other MR methods to explore these problems for analysis. Simultaneously, we conducted a bidirectional MR analysis to assess whether sarcopenia has a reverse causal relationship with internal iron status.

RESULTS

In our present research, we found serum iron (P = 0.033), ferritin (P = 0.001), transferrin saturation (P = 0.029) and coffee intake (P = 0.002) revealed a negative trend for sarcopenia, living alone (P = 0.022) and alcohol taken with meal (P = 0.006) showed a opposite trend for sarcopenia. Whereas sarcopenia showed negative trend for ferritin (P = 0.041) and transferrin saturation (P = 0.043), showed the opposite trend for transferrin (P = 0.021).

CONCLUSION

Our study suggested that higher serum iron levels might reduce the risk of sarcopenia. Moreover, living alone and alcohol consumption might increase the sarcopenia risk, while coffee intake and moderate physical activity could reduce the sarcopenia risk.

Gut microbiome and liver diseases

Symbiotic microbiota plays a crucial role in the education, development, and maintenance of the host immune system, significantly contributing to overall health. Through the gut-liver axis, the gut microbiota and liver have a bidirectional relationship that is becoming increasingly evident as more research highlights the translocation of the gut microbiota and its metabolites. The focus of this narrative review is to examine and discuss the importance of the gut-liver axis and the enterohepatic barrier in maintaining overall health. Additionally, we emphasize the crucial role of the gut microbiome in liver diseases and explore potential therapeutic strategies for liver diseases by manipulating the microbiota.

Gut Microbiome-Liver-Brain axis in Alcohol Use Disorder. The role of gut dysbiosis and stress in alcohol-related cognitive impairment progression: possible therapeutic approaches

The Gut Microbiome-Liver-Brain Axis is a relatively novel construct with promising potential to enhance our understanding of Alcohol Use Disorder (AUD), and its therapeutic approaches. Significant alterations in the gut microbiome occur in AUD even before any other systemic signs or symptoms manifest. Prolonged and inappropriate alcohol consumption, by affecting the gut microbiota and gut mucosa permeability, is thought to contribute to the development of behavioral and cognitive impairments, leading to Alcohol-Related Liver Disorders and potentially progressing into alcoholic cirrhosis, which is often associated with severe cognitive impairment related to neurodegeneration, such as hepatic encephalopathy and alcoholic dementia. The critical role of the gut microbiota is further supported by the efficacy of FDA-approved treatments for hepatic encephalopathy in alcoholic cirrhosis (i.e., lactulose and rifaximin). To stimulate new research, we hypothesize that interactions between a maladaptive stress response and a constitutional predisposition to neurodegeneration underlie the progression of AUD to conditions of Alcohol-Related Clinical Concerns with severe cognitive impairment, which represent a significant and costly burden to society. Early identification of AUD individuals at risk for developing these conditions could help to prioritize integrated therapeutic interventions targeting different substrates of the Gut Microbiome-Liver-Brain axis. Specifically, addiction medications, microbiome modulators, stress-reducing interventions, and, possibly soon, novel agents that reduce hepatic steatosis/fibrosis will be discussed in the context of digitally supported integrated therapeutic approaches. The explicit goal of this AUD treatment performed on the early stage of the disorder would be to reduce the transition from AUD to those conditions of Alcohol-Related Common Clinical Concerns associated with severe cognitive impairment, a strategy recommended for most neurological neurodegenerative disorders.

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.

Dynamic human gut microbiome and immune shifts during an immersive psychosocial intervention program

BACKGROUND

Although depression is a leading cause of disability worldwide, the pathophysiological mechanisms underlying this disorder-particularly those involving the gut microbiome-are poorly understood.

METHOD

To investigate, we conducted a community-based observational study to explore complex associations between changes in the gut microbiome, cytokine levels, and depression symptoms in 51 participants (Mage = 49.56, SD = 13.31) receiving an immersive psychosocial intervention. A total of 142 multi-omics samples were collected from participants before, during, and three months after the nine-day inquiry-based stress reduction program.

RESULTS

Results revealed that depression was associated with both an increased presence of putatively pathogenic bacteria and reduced microbial beta-diversity. Following the intervention, we observed reductions in neuroinflammatory cytokines and improvements in several mental health indicators. Interestingly, participants with a Prevotella-dominant microbiome showed milder symptoms when depressed, along with a more resilient microbiome and more favorable inflammatory cytokine profile, including reduced levels of CXCL-1.

CONCLUSIONS

These findings reveal a potentially protective link between the Prevotella-dominant microbiome and depression, as evidenced by a reduced pro-inflammatory environment and fewer depressive symptoms. These insights, coupled with observed improvements in neuroinflammatory markers and mental health from the intervention, may highlight potential avenues for microbiome-targeted therapies for managing depression.

Candida albicans Colonization Modulates Murine Ethanol Consumption and Behavioral Responses Through Elevation of Serum Prostaglandin E2 and Impact on the Striatal Dopamine System

Candida albicans is a commensal yeast that is a common component of the gastrointestinal (GI) microbiome of humans. C. albicans has been shown to bloom in the GI tract of individuals with alcohol use disorder (AUD) and can promote and increase the severity of alcoholic liver disease (ALD). However, the effects of C. albicans blooms on the host in the context of AUD or AUD-related phenotypes, such as ethanol preference, have been unstudied. In this work, we report a reduction in ethanol consumption and preference in mice colonized with C. albicans. C. albicans-colonized mice exhibited elevated levels of serum PGE2 and reduced ethanol preference was reversed by injection with antagonists of PGE2 receptors. Further, injection of mice with a PGE2 derivative decreased their ethanol preference. These results show that PGE2 acting on its receptors EP1 and EP2 drives reduced ethanol preference in C. albicans-colonized mice. We also showed altered transcription of dopamine receptors in the dorsal striatum of C. albicans-colonized mice and more rapid acquisition of ethanol conditioned taste aversion, suggesting alterations to reinforcement or aversion learning. Finally, C. albicans-colonized mice were more susceptible to ethanol-induced motor coordination impairment showing significant alterations to the behavioral effects of ethanol. This study identifies a member of the fungal microbiome that alters ethanol preference and demonstrates a role for PGE2 signaling in these phenotypes.

Nutritional and Psychological Support as a Multidisciplinary Coordinated Approach in the Management of Chronic Liver Disease: A Scoping Review

OBJECTIVES

This review emphasizes a novel, multidisciplinary, coordinated approach in the management of chronic liver diseases (CLDs).

BACKGROUND

Chronic liver diseases represent a significant global health burden, marked by a notable shift in the prevalence patterns from virus-related to metabolic and alcohol-related entities. Malnutrition, frailty, and sarcopenia exert a substantial impact on patients with cirrhosis, affecting 75%-90% of cases and escalating as the disease progresses. The European Association for the Study of the Liver recommends a comprehensive approach to nutritional care, emphasizing the need for detailed assessments in patients with cirrhosis, using diverse tools such as computed tomography scans, bioelectrical impedance analysis, and evaluations of muscle function. Considering the prevalence of nutritional and psychological disorders in the CLD population, the treatment of these patients should be founded indispensably on a multidisciplinary approach.

METHODS

A systematic search was conducted of the PubMed, MEDLINE, and SCOPUS databases to identify trials investigating the health effects of nutritional and psychological assessments in patients with CLD.

RESULTS

In dealing with the treatment of patients with CLD, an exploration of the psychological domain emerges as crucial, because psychological distress, especially depression, exerts a tangible influence on patient outcomes. Thus, the engagement of psychologists and/or psychotherapists, who might use techniques such as cognitive behavioral therapy, could enhance patients' comprehension of nutritional implications in their treatment and make them more aware of their illness.

CONCLUSION

The review emphasizes the relevance of both nutritional and psychological assessments in patients with CLD that could improve patient education on the pivotal role of nutrition in disease management. Randomized controlled trials evaluating the combined impact of nutritional and psychological support are recommended to further investigate this complex clinical landscape.

Effects of dietary live microbes intake on a newly proposed classification system for steatotic liver disease

Steatotic liver disease (SLD) is a common chronic liver disease without effective therapeutic options. Some studies suggest potential health benefits of dietary live microbes. This study aims to investigate the association between dietary live microbes intake and metabolic dysfunction-associated steatotic liver disease (MASLD) / metabolic alcohol-related liver disease (MetALD) / alcoholic liver disease (ALD) in adults. Data from the National Health and Nutrition Examination Survey 1999-2018 were analyzed. MASLD was defined according to the latest Delphi Consensus standard. Participants were grouped based on estimated dietary live microbe intake: low (< 104 CFU/g), moderate (104-107 CFU/g), and high (> 107 CFU/g). Multivariable logistic regression analysis was employed to assess the impact of dietary live microbes on MASLD/MetALD/ALD, along with further investigations into non-dietary probiotic/prebiotic relationships. Participants had a weighted mean age of 47.05 years (SE, 0.24) and 50.59% were female. MASLD proportions differ among low (21.76%), moderate (22.24%), and high (18.96%) microbe groups. Similarly, for MetALD, proportions are 7.75%, 6.95%, and 6.44%, and for ALD, 5.42%, 3.59%, and 2.97% in respective groups. The high dietary live microbe intake group was associated with a 16% lower risk of MASLD compared to those in the low intake group (trend test, P = 0.02), while the risk of ALD was reduced by 25% in the moderate intake group. A lack of association was identified between non-dietary prebiotic/probiotic and MASLD/MetALD/ALD. Our study suggests that a relatively high intake of live microbes diets in adults is associated with a lower risk of SLD.

Identification of distinct stool metabolites in women with endometriosis for non-invasive diagnosis and potential for microbiota-based therapies

BACKGROUND

Endometriosis, a poorly studied gynecological condition, is characterized by the presence of ectopic endometrial lesions resulting in pelvic pain, inflammation, and infertility. These associated symptoms contribute to a significant burden, often exacerbated by delayed diagnosis. Current diagnostic methods involve invasive procedures, and existing treatments provide no cure.

METHODS

Microbiome-metabolome signatures in stool samples from individuals with and without endometriosis were determined using unbiased metabolomics and 16S bacteria sequencing. Functional studies for selected microbiota-derived metabolites were conducted in vitro using patient-derived cells and in vivo by employing murine and human xenograft pre-clinical disease models.

FINDINGS

We discovered a unique bacteria-derived metabolite signature intricately linked to endometriosis. The altered fecal metabolite profile exhibits a strong correlation with that observed in inflammatory bowel disease (IBD), revealing intriguing connections between these two conditions. Notably, we validated 4-hydroxyindole, a gut-bacteria-derived metabolite that is lower in stool samples of endometriosis. Extensive in vivo studies found that 4-hydroxyindole suppressed the initiation and progression of endometriosis-associated inflammation and hyperalgesia in heterologous mouse and in pre-clinical models of the disease.

CONCLUSIONS

Our findings are the first to provide a distinct stool metabolite signature in women with endometriosis, which could serve as stool-based non-invasive diagnostics. Further, the gut-microbiota-derived 4-hydroxyindole poses as a therapeutic candidate for ameliorating endometriosis.

FUNDING

This work was funded by the NIH/NICHD grants (R01HD102680, R01HD104813) and a Research Scholar Grant from the American Cancer Society to R.K.

Cirrhosis and Faecal microbiota Transplantation (ChiFT) protocol: a Danish multicentre, randomised, placebo-controlled trial in patients with decompensated liver cirrhosis

INTRODUCTION

Liver cirrhosis is a progressive disease with high mortality. Gut microbiota derangement, increased gut permeability, bacterial translocation and chronic inflammation all drive disease progression. This trial aims to investigate whether faecal microbiota transplantation (FMT) may improve the disease course in patients with acute decompensation of liver cirrhosis.

METHODS AND ANALYSIS

In this Danish, multicentre, randomised, double-blinded, placebo-controlled trial, 220 patients with acute decompensation of liver cirrhosis and a Child-Pugh score≤12 will be randomised (1:1) to oral, encapsulated FMT or placebo in addition to standard of care. Before the intervention, the patients will be examined and biological samples obtained, and this is repeated at 1 and 4 weeks and 3, 6 and 12 months after the intervention. The primary outcome is the time from randomisation to new decompensation or death. Secondary endpoints include mortality, number of decompensation events during follow-up and changes in disease severity and liver function.

ETHICS AND DISSEMINATION

The Central Denmark Region Research Ethics Committee approved the trial protocol (no. 1-10-72-302-20). The results will be published in an international peer-reviewed journal, and all patients will receive a summary of the results.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov study identifier NCT04932577.

Sex disparity in the association between alcohol consumption and sarcopenia: a population-based study

BACKGROUND

Previous studies have shown inconsistent findings regarding the association of alcohol consumption with sarcopenia. Therefore, this study comprehensively investigated the association of alcohol consumption with sarcopenia in a nationally representative sample of US adults.

METHODS

This population-based study included adults aged 18 years and older from the National Health and Nutrition Examination Survey (NHANES) III. Alcohol exposure was defined as daily alcohol intake, alcohol drinking history, number of drinking days per week, and frequency of binge drinking days per month. Weighted logistic regressions were used to determine associations.

RESULTS

Four cohorts were selected from the NHANES III: cohort 1 (n = 7,592), cohort 2 (n = 12,060), cohort 3 (n = 7,608), and cohort 4 (n = 7,649), corresponding to alcohol exposure categories of daily alcohol intake, drinking history, number of drinking days per week, and frequency of binge drinking days per month. In the full model, the risk of sarcopenia was significantly associated with mild (odds ratio [OR]: 1.65; 95% confidence interval [CI]: 1.08-2.51), moderate (OR: 2.04; 95% CI: 1.12-3.71), and heavy drinkers (OR: 2.42; 95% CI: 1.17-4.97) compared to nondrinkers. There was an association between the development of sarcopenia and current drinkers (OR: 1.69; 95% CI: 1.12-2.56) but not former drinkers (OR: 1.21; 95% CI: 0.88-1.66). Compared to nondrinkers, an increased risk of developing sarcopenia was observed in participants who consumed alcohol 2 days (OR: 2.36; 95% CI: 1.40-3.99) or > 2 days (OR: 1.84; 95% CI: 1.10-3.07) per week, and those who engaged in binge drinking for ≤1 day per month (OR: 1.68; 95% CI: 1.09-2.60) or > 1 day per month (OR: 2.10; 95% CI: 1.10-4.01). Sensitivity analyses based on different definitions of sarcopenia yielded similar results. Stratified analyses revealed that these associations were present in females but not males.

CONCLUSION

Alcohol intake was associated with an increased risk of sarcopenia in all individuals, with this association being primarily observed in females rather than males.

Gut microbiota interacting with vitamin D but not anandamide might contribute to the pathogenesis of preeclampsia: a preliminary study

Introduction

Preeclampsia (PE) is a pregnancy-specific multisystem disorder and a leading cause of maternal and perinatal mortality globally. Despite numerous studies highlighting the potential roles of gut microbiota, anandamide (AEA), and Vitamin D (VitD) in PE, none have established them as reliable biomarkers for predicting disease onset. Moreover, their interactions in late-stage pregnancy women remain poorly understood.

Methods

Thirty-four preeclamptic patients (called PE group) and thirty-nine matched healthy late-pregnant women (called LP group) were involved in this case-control study. Fecal samples, which were used to acquire the diversity and composition of gut microbiota, were analyzed by 16S rRNA gene sequencing. Plasma AEA concentrations and serum VitD levels were determined by high-performance liquid chromatography-mass spectrometry (HPLC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), respectively.

Results

In this study, β diversity but not α diversity significantly differed between the LP and PE groups. Compared with the LP group, the relative abundances of Prevotella, Erysipelotrichaceae_UCG-003, and Dorea were increased dramatically in the PE group, whereas the relative abundances of Subdoligranulum, Parabacteroides, Bacteroides were significantly decreased in the PE group. Furthermore, women with PE had a substantially lower plasma level of AEA and a marked decrease in serum VitD compared to normal late-pregnant women. Lastly, although the serum level of AEA was not significantly correlated with VitD or any of the top 6 marker genera, VitD was significantly negatively correlated with the relative abundance of Dorea, a novel finding in this context.

Discussion

The gut microbiota profile of the PE group was significantly different from that of the LP group. Although no significant correlations were identified between the plasma AEA levels and serum VitD levels or any of the top 6 identified marker genera, a significant negative correlation was observed between VitD and Dorea, indicating VitD and gut microbiota have the potential to be combined targets for early diagnosis and management of PE.

The microbiota-gut-brain axis: a potential target in the small-molecule compounds and gene therapeutic strategies for Parkinson's disease

BACKGROUNDS

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by motor symptoms and non-motor symptoms. It has been found that intestinal issues usually precede motor symptoms. Microorganisms in the gastrointestinal tract can affect central nervous system through the microbiota-gut-brain axis. Accumulating evidence has shown that disturbances in the microbiota-gut-brain axis are linked with PD. Thus, this pathway appears to be a promising therapeutic target for treatment of PD.

OBJECTIVES

In this review, we mainly described gut dysbiosis in PD and their underlying mechanisms for mediating neuroinflammation and peripheral immune response in PD pathology and futher discussed the potential small-molecule compounds and genic therapeutic strategies targeting the microbiota-gut-brain axis and their applications in PD.

CONCLUSIONS

Studies have found that some small molecule compounds and alterations of inflammation-related genes can improve the motor and non-motor symptoms of PD by improving the microbiota-gut-brain axis, which may provide potentially beneficial drugs and molecular targets for the therapies of PD.

A narrative review about cognitive impairment in Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD): Another matter to face through a holistic approach

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic hepatic disorder worldwide in both adults and children. It is well established that MASLD represents the hepatic manifestation of the metabolic syndrome whose definition includes the presence of obesity, type 2 diabetes (T2D), dyslipidemia, hypertension and hypercoagulability. All these conditions contribute to a chronic inflammatory status which may impact on blood brain barrier (BBB) integrity leading to an impaired function of central nervous system (CNS).

AIM OF REVIEW

Since the mechanisms underlying the brain-liver-gut axis derangement are still inconclusive, the present narrative review aims to make a roundup of the most recent studies regarding the cognitive decline in MASLD also highlighting possible therapeutic strategies to reach a holistic advantage for the patients.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Due to its ever-growing prevalence, the MASLD-related mental dysfunction represents an enormous socio-economic burden since it largely impacts on the quality of life of patients as well as on their working productivity. Indeed, cognitive decline in MASLD translates in low concentration and processing speed, reduced memory, sleepiness but also anxiety and depression. Chronic systemic inflammation, hyperammonemia, genetic background and intestinal dysbiosis possibly contribute to the cognitive decline in MASLD patients. However, its diagnosis is still underestimated since the leading mechanisms are multi-faceted and unexplained and do not exist standardized diagnostic tools or cognitive test strategies. In this scenario, nutritional and lifestyle interventions as well as intestinal microbiota manipulation (probiotics, fecal transplantation) may represent new approaches to counteract mental impairment in these subjects. In sum, to face the "mental aspect" of this multifactorial disease which is almost unexplored, cognitive tools should be introduced in the management of MASLD patients.

Gut mycobiome and neuropsychiatric disorders: insights and therapeutic potential

Background

The human gut mycobiome, a minor but integral component of the gut microbiome, has emerged as a significant player in host homeostasis and disease development. While bacteria have traditionally been the focus of gut microbiome studies, recent evidence suggests that fungal communities (mycobiota) may also play a crucial role in modulating health, particularly in neuropsychiatric disorders.

Objective

This review aims to provide a comprehensive overview of current knowledge on the relationship between the gut mycobiome and neuropsychiatric disorders, exploring the potential of targeting fungal communities as a novel therapeutic strategy.

Methods

We summarized recent findings from metagenomic analyses that characterize the diversity and composition of gut mycobiota and discuss how these communities interact with the host and other microorganisms via the gut-brain axis. Key methodologies for studying mycobiota, such as high-throughout sequencing and bioinformatics approaches, were also reviewed to highlight advances in the field.

Results

Emerging research links gut mycobiota dysbiosis to conditions such as schizophrenia, Alzheimer's disease, autism spectrum disorders, bipolar disorder, and depression. Studies indicate that specific fungal populations, such as Candida and Saccharomyces, may influence neuroinflammation, gut permeability and immune responses, thereby affecting mental health outcomes.

Conclusion

Understanding the gut mycobiome's role in neuropsychiatric disorders opens new avenues for therapeutic interventions, including antifungal treatments, probiotics, and dietary modifications. Future research should integrate multi-omics approaches to unravel the complex interkingdom interactions within the gut ecosystem, paving the way for personalized medicine in mental health care.

Developing a translational research framework for MDD: combining biomolecular mechanisms with a spiraling risk factor model

Objective

The global incidence and burden of Major Depressive Disorder (MDD) are increasing annually, with current antidepressant treatments proving ineffective for 30-40% of patients. Biomolecular mechanisms within the microbiota-gut-brain axis (MGBA) may significantly contribute to MDD, potentially paving the way for novel treatment approaches. However, integrating the MGBA with the psychological and environmental aspects of MDD remains challenging. This manuscript aims to: 1) investigate the underlying biomolecular mechanisms of MDD using a modeling approach, and 2) integrate this knowledge into a comprehensive 'spiraling risk factor model' to develop a biopsychosocial translational research framework for the prevention and treatment of MDD.

Methods

For the first aim, a systematic review (PROSPERO registration) was conducted using PubMed, Embase, and Scopus to query literature published between 2016-2020, with select additional sources. A narrative review was performed for the second aim.

Results

In addition to genetics and neurobiology, research consistently indicates that hyperactivation of the HPA axis and a pro-inflammatory state are interrelated components of the MGBA and likely underlying mechanisms of MDD. Dysregulation of the MGBA, along with imbalances in mental and physical conditions, lifestyle factors, and pre-existing treatments, can trigger a downward spiral of stress and anxiety, potentially leading to MDD.

Conclusions

MDD is not solely a brain disorder but a heterogeneous condition involving biomolecular, psychological, and environmental risk factors. Future interdisciplinary research can utilize the integrated biopsychosocial insights from this manuscript to develop more effective lifestyle-focused multimodal treatment interventions, enhance diagnosis, and stimulate early-stage prevention of MDD.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42020215412.

Alcohol Use Disorder and the Gut-Brain Axis: A Narrative Review of the Role of Gut Microbiota and Implications for Treatment

Alcohol use disorder (AUD) affects millions of people worldwide and can lead to deleterious physical and social consequences. Recent research has highlighted not only the effect of alcohol on the gut microbiome, but also the role of the gut microbiome and the gut-brain axis in the development and maintenance of alcohol use disorder. This review provides an overview of the reciprocal relationship between alcohol consumption and the gut microbiome, including the effects of alcohol on gut microbial composition, changes in gut microbial metabolites in response to alcohol consumption, and how gut microbial metabolites may modulate alcohol use behavior. We also discuss the gut-mediated mechanisms of neuroinflammation that contribute to and result from AUD, including disruption of the intestinal barrier, toll-like receptor signaling, and the activation of glial cells and immune cells. Finally, we review the current evidence on gut microbial-directed therapies for AUD and discuss the implications of this research for our understanding of the pathophysiology of AUD and future research directions.

Characterization of Gut Microbiota in Rats and Rhesus Monkeys After Methamphetamine Self-administration

Methamphetamine (MA) is one of the most abused drugs globally, but the mechanism of its addiction remains unclear. Several animal studies have shown that the gut microbiota (GM) influences addictive behaviors, but the pattern of GM changes during addiction in animals of different species remains unclear. The aim of this study was to explore the association between dynamic changes in GM and MA self-administration acquisition among two classical mammals, rhesus monkeys (Macaca mulatta) and rats, MA self-administration models. Male Sprague-Dawley rats and male rhesus monkeys were subjected to classical MA self-administration training, and fecal samples were collected before and after MA self-administration training, respectively. 16S rRNA sequencing was used for GM analyses. We found that GM changes were more pronounced in rats than in rhesus monkeys, as evidenced by more GM taxa producing significant differences before and after MA self-administration training in rats than in monkeys. We also found that the expression of the genus Clostridia_vadinBB60_group significantly decreased after MA self-administration training in both rats and rhesus monkeys. Lactobacillus changes were significantly negatively correlated with total MA uptake in rats (Pearson R =  - 0.666, p = 0.035; Spearman R =  - 0.721, p = 0.023), whereas its change was also highly negatively correlated with total MA uptake in rhesus monkeys (Pearson R =  - 0.882, p = 0.118; Spearman R =  - 1.000, p = 0.083), although this was not significant. These findings suggest that MA causes significant alterations in GM in both rhesus monkeys and rats and that the genus Lactobacillus might be a common therapeutic target for MA uptake prevention across the species.

The gut microbiota-produced vitamin B6 mitigates alcohol-associated liver disease by attenuating hepatic oxidative stress damage

BACKGROUND

Alcohol-associated liver disease (ALD) is a major clinical issue characterized by progressive stages, including hepatic steatosis, liver fibrosis, cirrhosis, and HCC. Patients with long-term chronic alcoholism often present with gut microbiota dysbiosis and reduced plasma levels of vitamin B6. This study aimed to verify that gut microbiota disruption in ALD significantly contributes to reduced in vivo production of vitamin B6 and to investigate the role of this reduction in the pathogenesis of ALD.

METHODS

The ALD was investigated utilizing the Gao-binge mouse model. Fecal microbial composition was analyzed in pair-fed mice and ALD mice to identify alcohol-induced functional changes in the microbiota. Additionally, liver protein expression profiles and liver and plasma metabolomic profiles were characterized to elucidate the role of vitamin B6 in ALD pathogenesis through integrated proteomic and metabolomic analyses. The findings were further validated using animal models and clinical patient samples.

RESULTS

Alcohol consumption disrupted the gut microbiota in the mice, impairing the vitamin B6 synthesis by intestinal microorganisms. Vitamin B6 deficiency aggravated the disorder of amino acid metabolism in the liver and inhibited ornithine aminotransferase expression, thereby worsening oxidative stress damage. In patients with ALD, significant disturbances of gut microbiota were observed, along with decreased intestinal vitamin B6 levels, which were negatively correlated with serum biochemical markers.

CONCLUSIONS

The imbalance of gut microbiota in ALD mice reduces vitamin B6 synthesis, which affects amino acid metabolism and glutathione synthesis in the liver, thereby exacerbating ALD. These findings suggest that vitamin B6 may play a critical protective role in ALD progression by regulating amino acid metabolism.

Neuroglia in substance use disorders

Substance use disorders (SUD) remain a major public health concern in which individuals are unable to control their use of substances despite significant harm and negative consequences. Drugs of abuse dysregulate major brain and behavioral functions. Glial cells, primarily microglia and astrocytes, play a crucial role in these drug-induced molecular and behavioral changes. This review explores preclinical and clinical studies of how neuroglia and their associated neuroinflammatory responses contribute to SUD and reward-related properties. We evaluate preclinical and clinical evidence for targeting neuroglia as therapeutic interventions. In addition, we evaluate the literature on the gut microbiome and its role in SUD. Clinical treatments are most effective for reducing drug cravings, and some have yielded promising results in other measures of drug use. N-Acetylcysteine, through modulation of cysteine-glutamate antiporter of glial cells, shows encouraging results across a variety of drug classes. Neuroglia and gut microbiome interactions are important factors to consider with regard to SUD and could lead to novel therapeutic avenues. Age- and sex-dependent properties of neuroglia, gut microbiome, and drug use behaviors are important areas in need of further investigation.

Gut Microbiota as Emerging Players in the Development of Alcohol-Related Liver Disease

The global incidence and mortality rates of alcohol-related liver disease are on the rise, reflecting a growing health concern worldwide. Alcohol-related liver disease develops due to a complex interplay of multiple reasons, including oxidative stress generated during the metabolism of ethanol, immune response activated by immunogenic substances, and subsequent inflammatory processes. Recent research highlights the gut microbiota's significant role in the progression of alcohol-related liver disease. In patients with alcohol-related liver disease, the relative abundance of pathogenic bacteria, including Enterococcus faecalis, increases and is positively correlated with the level of severity exhibited by alcohol-related liver disease. Supplement probiotics like Lactobacillus, as well as Bifidobacterium, have been found to alleviate alcohol-related liver disease. The gut microbiota is speculated to trigger specific signaling pathways, influence metabolite profiles, and modulate immune responses in the gut and liver. This research aimed to investigate the role of gut microorganisms in the onset and advancement of alcohol-related liver disease, as well as to uncover the underlying mechanisms by which the gut microbiota may contribute to its development. This review outlines current treatments for reversing gut dysbiosis, including probiotics, fecal microbiota transplantation, and targeted phage therapy. Particularly, targeted therapy will be a vital aspect of future alcohol-related liver disease treatment. It is to be hoped that this article will prove beneficial for the treatment of alcohol-related liver disease.

Alcohol-induced gut microbial reorganization and associated overproduction of phenylacetylglutamine promotes cardiovascular disease

The mechanism(s) underlying gut microbial metabolite (GMM) contribution towards alcohol-mediated cardiovascular disease (CVD) is unknown. Herein we observe elevation in circulating phenylacetylglutamine (PAGln), a known CVD-associated GMM, in individuals living with alcohol use disorder. In a male murine binge-on-chronic alcohol model, we confirm gut microbial reorganization, elevation in PAGln levels, and the presence of cardiovascular pathophysiology. Fecal microbiota transplantation from pair-/alcohol-fed mice into naïve male mice demonstrates the transmissibility of PAGln production and the CVD phenotype. Independent of alcohol exposure, pharmacological-mediated increases in PAGln elicits direct cardiac and vascular dysfunction. PAGln induced hypercontractility and altered calcium cycling in isolated cardiomyocytes providing evidence of improper relaxation which corresponds to elevated filling pressures observed in vivo. Furthermore, PAGln directly induces vascular endothelial cell activation through induction of oxidative stress leading to endothelial cell dysfunction. We thus reveal that the alcohol-induced microbial reorganization and resultant GMM elevation, specifically PAGln, directly contributes to CVD.

Structural characterization of the polysaccharides from Atractylodes chinensis (DC.) Koidz. and the protective effection against alcohol-induced intestinal injury in rats

A neutral polysaccharide, AP, with a weight-average molecular weight of 60.61 kDa, consisting mainly of arabinose and galactose, was isolated from the rhizomes of Atractylodes chinensis (DC.) Koidz. Methylation analyses and nuclear magnetic resonance spectroscopy indicated that the probable repeat unit of AP was →3,6)-α-D-Galp-(1→ residues and constituted the main chain, with a side chain of →5)-α-L-Araf-(1→ and terminal α-L-Araf attached to C-6 of the main chain. The protective activity and potential mechanisms of action of AP on the intestinal tract were investigated. AP improved intestinal oxidative stress injury and inflammatory responses by promoting the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 signaling pathway and inhibiting the toll-like receptor 4/myeloid differentiation primary response protein 88/nuclear factor-kappa B signaling pathway, but also repaired colonic mucosal injury and reduced intestinal leakage of endotoxins by promoting expression of the tight-junction proteins zonula occludens-1 and occludin. AP improved ecological dysregulation of the intestinal microbiota and promoted the growth of the potentially beneficial bacteria Lactobacillus_taiwanensis, Limosilactobacillus_reuteri and Akkermansia_muciniphila. AP promoted intestinal health by increasing the production of potentially beneficial metabolites such as short-chain fatty acids, Indole-3-propionic acid, and N-Eicosapentaenoyl tryptophan through metabolism (amino acids, lipids, carbohydrates). These results suggest that AP is a promising prebiotic in attenuating alcohol-induced intestinal damage.

Alcohol-associated liver disease-Global epidemiology

Alcohol-associated liver disease (ALD), as highlighted in this narrative review, is a major public health concern, increasingly impacting global disease burden and premature mortality. In 2019, ALD accounted for the loss of 11 million life-years worldwide. The rising number of deaths and disability-adjusted life-years attributed to ALD, particularly pronounced in the United States, are alarming. Projections suggest that the economic impact of ALD, as seen in the United States, could potentially double by 2040. ALD is increasingly prevalent among younger adults (20-45 y) and has become the leading cause of liver transplantation in both United States and Europe. During the COVID-19 pandemic, the existing trend was further amplified as high-risk drinking patterns coincided with a rise in hospital admissions for alcohol-associated hepatitis and increased ALD-related mortality. The prevalence of ALD is estimated at 3.5% in the general population, 26.0% among hazardous drinkers, and 55.1% among those with alcohol use disorders. Alarmingly, 5-year mortality rates for patients with ALD exceed 50%, with even higher rates in more advanced disease stages. Methodological challenges, such as underreporting, diagnostic difficulties, and variability in registry data quality, complicate the accurate assessment of the impact of ALD. Additionally, the contribution of alcohol to the progression of other liver diseases is often under acknowledged in health care registries, leading to a significant underestimation of its broader implications for liver health. Addressing the growing ALD concern requires robust public health initiatives, heightened awareness, refined diagnostic techniques, and comprehensive epidemiological studies. These measures are vital to tackle the increasing prevalence of ALD and mitigate its extensive impact on individuals and health care systems.

Alcohol-associated liver disease: Emerging therapeutic strategies

The large and growing burden of alcohol-associated liver disease-and the considerable burden of morbidity and mortality associated with it-has been a drive toward ongoing research into novel strategies for its treatment, with a particular focus upon alcohol-associated hepatitis (AH). Management of alcohol-use disorder forms the central pillar of alcohol-associated liver disease care, with evidence-based psychological and pharmacological approaches being well established, and certain models demonstrating improved clinical outcomes when hepatology and addiction services are co-located. Corticosteroids have previously been used somewhat indiscriminately in patients with severe AH, but effective tools now exist to assess early response (and limit futile ongoing exposure). Techniques to predict risk of corticosteroid-related infection are also available, although current clinical strategies to mitigate this risk are limited. A variety of novel therapeutic approaches to AH are at different phases of trials and evidence gathering, with some of the most promising signals related to cytokine manipulation, epigenetic modulation, and targeting of the gut microbiota (ie, by means of fecal microbiota transplant). While remaining an ongoing source of debate, early liver transplant in severe AH has grown in interest and acceptability over the past decade as evidence supporting its efficacy builds, in the process challenging paradigms about mandatory pretransplant sobriety periods. However, uncertainty remains regarding the optimal selection criteria, and whether liver transplant has a role for only a highly limited proportion of patients with AH or more widespread application. This review aims to provide an overview of this fast-moving field.

Biotics as novel therapeutics in targeting signs of skin ageing via the gut-skin axis

Skin ageing is a phenomenon resulting from the aggregative changes to skin structure and function and is clinically manifested by physical features such as wrinkles, hyperpigmentation, elastosis, telangiectasia, and deterioration of skin barrier integrity. One of the main drivers of skin ageing, UV radiation, negatively influences the homeostasis of cells and tissues comprising the skin by triggering production of immune-mediated reactive oxygen species (ROS) and pro-inflammatory cytokines, as well as a various hormones and neuropeptides. Interestingly, an established link between the gut and the skin coined the 'gut-skin axis' has been demonstrated, with dysbiosis and gut barrier dysfunction frequently observed in certain inflammatory skin conditions and more recently, implicated in skin ageing. Therapeutic use of 'biotics' including prebiotics, probiotics, postbiotics, and synbiotics, which modulate the gut microbiota and production of microbially associated metabolites, influence the activity of the gut mucosal and immune systems and are showing promise as key candidates in addressing signs of skin ageing. In this review we aim to focus on the structure and function of the gut-skin axis and showcase the recent in-vitro and clinical evidence demonstrating the beneficial effects of select biotics in targeting signs of skin ageing and discuss the proposed mechanisms mediated via the gut-skin axis underpinning these effects.

Blood metabolomic profiling reveals new targets in the management of psychological symptoms associated with severe alcohol use disorder

Background

Alcohol use disorder (AUD) is a global health problem with limited therapeutic options. The biochemical mechanisms that lead to this disorder are not yet fully understood, and in this respect, metabolomics represents a promising approach to decipher metabolic events related to AUD. The plasma metabolome contains a plethora of bioactive molecules that reflects the functional changes in host metabolism but also the impact of the gut microbiome and nutritional habits.

Methods

In this study, we investigated the impact of severe AUD (sAUD), and of a 3-week period of alcohol abstinence, on the blood metabolome (non-targeted LC-MS metabolomics analysis) in 96 sAUD patients hospitalized for alcohol withdrawal.

Results

We found that the plasma levels of different lipids ((lyso)phosphatidylcholines, long-chain fatty acids), short-chain fatty acids (i.e. 3-hydroxyvaleric acid) and bile acids were altered in sAUD patients. In addition, several microbial metabolites, including indole-3-propionic acid, p-cresol sulfate, hippuric acid, pyrocatechol sulfate, and metabolites belonging to xanthine class (paraxanthine, theobromine and theophylline) were sensitive to alcohol exposure and alcohol withdrawal. 3-Hydroxyvaleric acid, caffeine metabolites (theobromine, paraxanthine, and theophylline) and microbial metabolites (hippuric acid and pyrocatechol sulfate) were correlated with anxiety, depression and alcohol craving. Metabolomics analysis in postmortem samples of frontal cortex and cerebrospinal fluid of those consuming a high level of alcohol revealed that those metabolites can be found also in brain tissue.

Conclusions

Our data allow the identification of neuroactive metabolites, from interactions between food components and microbiota, which may represent new targets arising in the management of neuropsychiatric diseases such as sAUD.

Funding

Gut2Behave project was initiated from ERA-NET NEURON network (Joint Transnational Call 2019) and was financed by Academy of Finland, French National Research Agency (ANR-19-NEUR-0003-03) and the Fonds de la Recherche Scientifique (FRS-FNRS; PINT-MULTI R.8013.19, Belgium). Metabolomics analysis of the TSDS samples was supported by grant from the Finnish Foundation for Alcohol Studies.

Gut microbiota as a biomarker and modulator of anti-tumor immunotherapy outcomes

Although immune-checkpoint inhibitors (ICIs) have significantly improved cancer treatment, their effectiveness is limited by primary or acquired resistance in many patients. The gut microbiota, through its production of metabolites and regulation of immune cell functions, plays a vital role in maintaining immune balance and influencing the response to cancer immunotherapies. This review highlights evidence linking specific gut microbial characteristics to increased therapeutic efficacy in a variety of cancers, such as gastrointestinal cancers, melanoma, lung cancer, urinary system cancers, and reproductive system cancers, suggesting the gut microbiota's potential as a predictive biomarker for ICI responsiveness. It also explores the possibility of enhancing ICI effectiveness through fecal microbiota transplantation, probiotics, prebiotics, synbiotics, postbiotics, and dietary modifications. Moreover, the review underscores the need for extensive randomized controlled trials to confirm the gut microbiota's predictive value and to establish guidelines for microbiota-targeted interventions in immunotherapy. In summary, the article suggests that a balanced gut microbiota is key to maximizing immunotherapy benefits and calls for further research to optimize microbiota modulation strategies for cancer treatment. It advocates for a deeper comprehension of the complex interactions between gut microbiota, host immunity, and cancer therapy, aiming for more personalized and effective treatment options.

Intragastric administration of short chain fatty acids greatly reduces voluntary ethanol intake in rats

Alcohol use disorder (AUD) represents a public health crisis with few FDA-approved medications for its treatment. Growing evidence supports the key role of the bidirectional communication between the gut microbiota and the central nervous system (CNS) during the initiation and progression of alcohol use disorder. Among the different protective molecules that could mediate this communication, short chain fatty acids (SCFAs) have emerged as attractive candidates, since these gut microbiota-derived molecules have multi-target effects that could normalize several of the functional and structural parameters altered by chronic alcohol abuse. The present study, conducted in male alcohol-preferring UChB rats, shows that the initiation of voluntary ethanol intake was inhibited in 85% by the intragastric administration of a combination of SCFAs (acetate, propionate and butyrate) given before ethanol exposure, while SCFAs administration after two months of ethanol intake induced a 90% reduction in its consumption. These SCFAs therapeutic effects were associated with (1) a significant reduction of ethanol-induced intestinal inflammation and damage; (2) reduction of plasma lipopolysaccharide levels and hepatic inflammation; (3) reduction of ethanol-induced astrocyte and microglia activation; and (4) attenuation of the ethanol-induced gene expression changes within the nucleus accumbens. Finally, we determined that among the different SCFAs evaluated, butyrate was the most potent, reducing chronic ethanol intake in a dose-response manner. These findings support a key role of SCFAs, and especially butyrate, in regulating AUD, providing a simple, inexpensive, and safe approach as a preventive and intervention-based strategy to address this devastating disease.

Minibioreactor arrays to model microbiome response to alcohol and tryptophan in the context of alcohol-associated liver disease

The intestinal microbiota (IM) plays a role in the severity of alcohol-associated liver disease. Modifying severe alcohol-associated hepatitis (AH) dysbiosis improves liver injury through tryptophan (Trp) metabolites and the aryl hydrocarbon receptor (AhR). However, Trp's effect on the IM in alcohol use disorder (AUD) patients remains unclear. Here, we used an in vitro microbiota modeling system named Minibioreactor arrays (MBRAs). Feces from AUD patients with or without AH were treated with low, normal, or high Trp concentrations, with subsequent treatment with alcohol. Microbiota composition and AhR activity were studied. We showed that microbial communities from donors were maintained in MBRAs. High and low Trp increased the abundance of pathogen Escherichia Shigella. In the absence of alcohol, Trp changed more bacteria in AUD IM compared to AH IM. Normal Trp increased the AhR activity. Overall, maintaining normal Trp levels may prevent dysbiosis in AUD or AH, pending in vivo confirmation.

Ketamine induced gut microbiota dysbiosis and barrier and hippocampal dysfunction in rats

The microbiota-gut-brain axis (MGBA) plays a pivotal role in drug addiction. However, the pathophysiological mechanism of MGBA in ketamine addiction remains elusive. The present study investigated the ketamine-induced gut microbiota disorders, intestinal barrier dysfunction, and the alterations in brain function, using a conditioned place preference (CPP) model of ketamine addiction in rats. Compared with the control group, ketamine induced decreased amplitude of low-frequency fluctuation (ALFF) values in the hippocampus, and pyknotic nuclei and concentrated cytoplasm in hippocampal neurons, as well as alterations in gut microbiota composition, shortened ileum villi, and thinner colonic mucosa. We also found that the abundance of gut microbiota exhibited correlations with CPP score, hippocampal ALFF value, length of ileum villi, and thickness of colonic mucosa. Our findings provide evidence for abnormal alterations in the MGBA of ketamine-addicted rats, which improves our understating of the mechanism of ketamine addiction and the potential for developing new therapeutic strategies.

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.

Blackcurrants shape gut microbiota profile and reduce risk of postmenopausal osteoporosis via the gut-bone axis: Evidence from a pilot randomized controlled trial

This study aimed to investigate the effects of blackcurrant (BC) on gut microbiota abundance and composition, inflammatory and immune responses, and their relationship with bone mass changes. The effects of BC on bone mineral density (BMD), gut microbiota, and blood inflammatory and immune biomarkers were evaluated using DXA, stool and fasting blood collected from a pilot three-arm, randomized, double-blind, placebo-controlled clinical trial. Fifty-one peri- and early postmenopausal women aged 45-60 years were randomly assigned into one of three treatment groups for 6 months: control, low BC (392 mg/day) and high BC (784 mg/day); and 40 women completed the trial. BC supplementation for 6 months effectively mitigated the loss of whole-body BMD (P<.05). Six-month changes (%) in peripheral IL-1β (P=.056) and RANKL (P=.052) for the high BC group were marginally significantly lower than the control group. Six-month changes in whole-body BMD were inversely correlated with changes in RANKL (P<.01). In proteome analysis, four plasma proteins showed increased expression in the high BC group: IGFBP4, tetranectin, fetuin-B, and vitamin K-dependent protein S. BC dose-dependently increased the relative abundance of Ruminococcus 2 (P<.05), one of six bacteria correlated with BMD changes in the high BC group (P<.05), suggesting it might be the key bacteria that drove bone protective effects. Daily BC consumption for 6 months mitigated bone loss in this population potentially through modulating the gut microbiota composition and suppressing osteoclastogenic cytokines. Larger-scale clinical trials on the potential benefits of BC and connection of Ruminococcus 2 with BMD maintenance in postmenopausal women are warranted. Trial Registration: NCT04431960, https://classic.clinicaltrials.gov/ct2/show/NCT04431960.