Allogenic Fecal Microbiota Transplantation in Patients With Nonalcoholic Fatty Liver Disease Improves Abnormal Small Intestinal Permeability: A Randomized Control Trial

Washed microbiota transplantation improves symptoms and intestinal barrier function in patients with functional bowel disorders: a propensity-score matching analysis

BACKGROUND

Alterations in the intestinal microbiota may play a role in the pathogenesis of functional bowel disorders (FBDs). Probiotics are widely used to improve intestinal dysbacteriosis in FBDs. In the context of FBDs, washed microbiota transplantation (WMT) appear to be a promising therapeutic option. We aimed to compare probiotics with WMT by using a propensity-score matching analysis (PSMA).

METHODS

We conducted a retrospective investigation of 103 patients with FBDs, including irritable bowel syndrome (IBS), functional constipation (FC), functional diarrhea (FDr), functional abdominal bloating (FAB). Patients were divided into the WMT group or probiotics group (taking probiotics capsules). Data on the following parameters were matched for PSMA: age; sex; disease course; body mass index; anxiety; insomnia; tobacco smoking; alcohol consumption; and levels of D-lactate, diamine oxidase, and lipopolysaccharide. Intestinal barrier function (IBF) and symptoms were evaluated both before and after treatment initiation. Prognostic factors were assessed by Cox proportional hazards regression analysis.

RESULTS

PSMA identified in 34 matched pairs (11 IBS, 12 FC, 7 FDr, and 4 FAB in the probiotics group and 14 IBS, 13 FC, 5 FDr, and 2 FAB in the WMT group. Improvement of FBD symptoms was greater with WMT than probiotics (P = 0.002). The WMT group had significantly fewer patients with intestinal barrier damage than the probiotics group (38.2% vs. 67.6%, P = 0.041). This improvement of FBD with WMT was further reflected as a reduction in D-lactate levels (P = 0.031). Increased D-lactate levels which were identified as a prognostic factor for FBDs (HR = 0.248, 95%CI 0.093-0.666, P = 0.006) in multivariate Cox regression analysis.

CONCLUSION

WMT could improve symptoms and IBF in patients with FBDs. Increased D-lactate levels in patients with FBDs may predict a favorable response to WMT treatment.

Impact of gut microbiota on nonalcoholic fatty liver disease: insights from a leave-one-out cross-validation study

Introduction

Enteric dysbacteriosis is strongly associated with nonalcoholic fatty liver disease (NAFLD). However, the underlying causal relationship remains unknown. Thus, the present study aimed to investigate the relationship between gut microbiota and NAFLD using Mendelian randomization (MR) and analyze the target genes potentially regulated by specific microbiota.

Methods

Bidirectional two-sample MR analysis was performed using inverse variance weighted (IVW) supplemented by MR-Egger, weighted median, simple mode, and weighted mode methods. Data were pooled from gut microbiota and NAFLD association studies. The least absolute shrinkage, selection operator regression, and the Support Vector Machine algorithm were used to identify genes regulated by these intestinal flora in NAFLD. The liver expression of these genes was verified in methionine choline-deficient (MCD) diet-fed mice.

Results

IVW results confirmed a causal relationship between eight specific gut microbes and NAFLD. Notably, the order Actinomycetales, NB1n, the family Actinomycetaceae, Oxalobacteraceae and the genus Ruminococcaceae UCG005 were positively correlated, whereas Lactobacillaceae, the Christensenellaceae R7 group, and Intestinibacter were negatively correlated with NAFLD onset. In NAFLD, these eight bacteria regulated four genes: colony-stimulating factor 2 receptor β, fucosyltransferase 2, 17-beta-hydroxysteroid dehydrogenase 14, and microtubule affinity regulatory kinase 3 (MAPK3). All genes, except MARK3, were differentially expressed in the liver tissues of MCD diet-fed mice.

Discussion

The abundance of eight gut microbiota species and NAFLD progression displayed a causal relationship based on the expression of the four target genes. Our findings contributed to the advancement of intestinal microecology-based diagnostic technologies and targeted therapies for NAFLD.

The gut-liver axis in hepatobiliary diseases

Recent advances in the analysis of intestinal bacteria have led to reports of variations in intestinal bacterial levels among hepatobiliary diseases. The mechanisms behind the changes in intestinal bacteria in various hepatobiliary diseases include the abnormal composition of intestinal bacteria, weakening of the intestinal barrier, and bacterial translocation outside the intestinal tract, along with their metabolites, but many aspects remain unresolved. Further research employing clinical studies and animal models is expected to clarify the direct relationship between intestinal bacteria and hepatobiliary diseases and to validate the utility of intestinal bacteria as a diagnostic biomarker and potential therapeutic target. This review summarizes the involvement of the microbiota in the pathogenesis of hepatobiliary diseases via the gut-liver axis.

Human gut microbiome: Therapeutic opportunities for metabolic syndrome-Hype or hope?

Shifts in gut microbiome composition and metabolic disorders are associated with one another. Clinical studies and experimental data suggest a causal relationship, making the gut microbiome an attractive therapeutic goal. Diet, intake of probiotics or prebiotics and faecal microbiome transplantation (FMT) are methods to alter a person's microbiome composition. Although FMT may allow establishing a proof of concept to use microbiome modulation to treat metabolic disorders, studies show mixed results regarding the effects on metabolic parameters as well as on the composition of the microbiome. This review summarizes the current knowledge on diet, probiotics, prebiotics and FMT to treat metabolic diseases, focusing on studies that also report alterations in microbiome composition. Furthermore, clinical trial results on the effects of common drugs used to treat metabolic diseases are synopsized to highlight the bidirectional relationship between the microbiome and metabolic diseases. In conclusion, there is clear evidence that microbiome modulation has the potential to influence metabolic diseases; however, it is not possible to distinguish which intervention is the most successful. In addition, a clear commitment from all stakeholders is necessary to move forward in the direction of developing targeted interventions for microbiome modulation.

Altered gut microbiome associated with metabolic-associated fatty liver disease in Chinese children

BACKGROUND & AIM

Limited studies have investigated the association between gut microbiota and metabolic dysfunction-associated fatty liver disease (MAFLD) in children and adolescents. We aimed to identify differences in gut microbiota composition and diversity between children with MAFLD and healthy counterparts.

METHODS

Data were collected from a nested case-control study (October to December, 2021) of the "Huantai Childhood Cardiovascular Health Cohort Study" in Huantai County, Zibo City, China. The study included 52 children aged 5-11 years with new-onset MAFLD and 52 healthy children matched by age and sex. Stool samples were collected and analyzed using 16S rRNA gene sequencing. Shannon index and Chao index were used to assess the α diversity of gut microbiota and Principal coordinates analysis (PCoA) was performed to evaluate β diversity between the two groups. The differences in the relative abundance of gut microbiota between MAFLD group and control group were compared by the Wilcoxon rank-sum test after false discovery rate (FDR) correction. Additionally, the gut-microbial metabolic pathways were identified using the phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt).

RESULTS

We found that children with MAFLD had significant different gut microbiota composition and reduced α diversity compared with the control group. PCoA showed that the two groups can be significantly distinguished based on the unweighted unifrac distance algorithm. Gut microbiota at the phylum level such as Verrucomicrobia and Desulfobacterial, genus level such as Blautia, Lachnospiraceae_NK4A136_group, Coprococcus, Erysipelotrichaceae_UCG-003, UCG-002 and Akkermansia, and species level such as Bifidobacterium_longum abundances were significantly decreased in children with MAFLD compared with that in children without MAFLD. Notably, the abundance of these bacteria were found to be associated with HDL-C, SBP, DBP, WC, BMI, etc. In addition, our analysis of gut-microbial metabolic pathways identified differences in carbohydrate transport and metabolism, as well as amino acid transport and metabolism between the two groups.

CONCLUSION

Significant differences in gut microbiota composition are observed between children with and without MAFLD, which indicate that gut microbiota may be a potential contributor to the development of MAFLD in childhood.

Washed microbiota transplantation promotes homing of group 3 innate lymphoid cells to the liver via the CXCL16/CXCR6 axis: a potential treatment for metabolic-associated fatty liver disease

Despite the observed decrease in liver fat associated with metabolic-associated fatty liver disease (MAFLD) in mice following fecal microbiota transplantation, the clinical effects and underlying mechanisms of washed microbiota transplantation (WMT), a refined method of fecal microbiota transplantation, for the treatment of MAFLD remain unclear. In this study, both patients and mice with MAFLD exhibit an altered gut microbiota composition. WMT increases the levels of beneficial bacteria, decreases the abundance of pathogenic bacteria, and reduces hepatic steatosis in MAFLD-affected patients and mice. Downregulation of the liver-homing chemokine receptor CXCR6 on ILC3s results in an atypical distribution of ILC3s in patients and mice with MAFLD, characterized by a significant reduction in ILC3s in the liver and an increase in ILC3s outside the liver. Moreover, disease severity is negatively correlated with the proportion of hepatic ILC3s. These hepatic ILC3s demonstrate a mitigating effect on hepatic steatosis through the release of IL-22. Mechanistically, WMT upregulates CXCR6 expression on ILC3s, thereby facilitating their migration to the liver of MAFLD mice via the CXCL16/CXCR6 axis, ultimately contributing to the amelioration of MAFLD. Overall, these findings highlight that WMT and targeting of liver-homing ILC3s could be promising strategies for the treatment of MAFLD.

Nutritional Interventions, Probiotics, Synbiotics and Fecal Microbiota Transplantation in Steatotic Liver Disease : Pediatric Fatty Liver and Probiotics

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a major health problem worldwide, and the strongest determinant of liver disease in children. The possible influence of high-fat/low-fiber dietary patterns with microbiota (e.g., increased Firmicutes/Bacteroidetes ratio), and ultimately with MASLD occurrence and progression has been elucidated by several association studies. The possible mechanisms through which microbes exert their detrimental effects on MASLD include gut vascular barrier damage, a shift towards non-tolerogenic immunologic environment, and the detrimental metabolic changes, including a relative reduction of propionate and butyrate in favor of acetate, endogenous ethanol production, and impairment of the unconjugated bile acid-driven FXR-mediated gut-liver axis. The impact of nutritional and probiotic interventions in children with MASLD is described.

Gut microbiota and metabolite interface-mediated hepatic inflammation

Immunologic and metabolic signals regulated by gut microbiota and relevant metabolites mediate bidirectional interaction between the gut and liver. Gut microbiota dysbiosis, due to diet, lifestyle, bile acids, and genetic and environmental factors, can advance the progression of chronic liver disease. Commensal gut bacteria have both pro- and anti-inflammatory effects depending on their species and relative abundance in the intestine. Components and metabolites derived from gut microbiota-diet interaction can regulate hepatic innate and adaptive immune cells, as well as liver parenchymal cells, significantly impacting liver inflammation. In this mini review, recent findings of specific bacterial species and metabolites with functions in regulating liver inflammation are first reviewed. In addition, socioeconomic and environmental factors, hormones, and genetics that shape the profile of gut microbiota and microbial metabolites and components with the function of priming or dampening liver inflammation are discussed. Finally, current clinical trials evaluating the factors that manipulate gut microbiota to treat liver inflammation and chronic liver disease are reviewed. Overall, the discussion of microbial and metabolic mediators contributing to liver inflammation will help direct our future studies on liver disease.

Gut microbes in metabolic disturbances. Promising role for therapeutic manipulations?

The prevalence of overweight, obesity, type 2 diabetes, metabolic syndrome and steatotic liver disease is rapidly increasing worldwide with a huge economic burden in terms of morbidity and mortality. Several genetic and environmental factors are involved in the onset and development of metabolic disorders and related complications. A critical role also exists for the gut microbiota, a complex polymicrobial ecology at the interface of the internal and external environment. The gut microbiota contributes to food digestion and transformation, caloric intake, and immune response of the host, keeping the homeostatic control in health. Mechanisms of disease include enhanced energy extraction from the non-digestible dietary carbohydrates, increased gut permeability and translocation of bacterial metabolites which activate a chronic low-grade systemic inflammation and insulin resistance, as precursors of tangible metabolic disorders involving glucose and lipid homeostasis. The ultimate causative role of gut microbiota in this respect remains to be elucidated, as well as the therapeutic value of manipulating the gut microbiota by diet, pre- and pro- synbiotics, or fecal microbial transplantation.

Nonalcoholic Fatty Liver Disease and the Intestinal Microbiome: An Inseparable Link

Nonalcoholic fatty liver disease (NAFLD) particularly affects patients with type 2 diabetes and obesity. The incidence of NAFLD has increased significantly over the last decades and is now pandemically across the globe. It is a complex systemic disease comprising hepatic lipid accumulation, inflammation, lipotoxicity, gut dysbiosis, and insulin resistance as main features and with the potential to progress to cirrhosis and hepatocellular carcinoma (HCC). In numerous animal and human studies the gut microbiota plays a key role in the pathogenesis of NAFLD, NAFLD-cirrhosis and NAFLD-associated HCC. Lipotoxicity is the driver of inflammation, insulin resistance, and liver injury. Likewise, western diet, obesity, and metabolic disorders may alter the gut microbiota, which activates innate and adaptive immune responses and fuels hereby hepatic and systemic inflammation. Indigestible carbohydrates are fermented by the gut microbiota to produce important metabolites, such as short-chain fatty acids and succinate. Numerous animal and human studies suggested a pivotal role of these metabolites in the progression of NAFLD and its comorbidities. Though, modification of the gut microbiota and/or the metabolites could even be beneficial in patients with NAFLD, NAFLD-cirrhosis, and NAFLD-associated HCC. In this review we collect the evidence that exogenous and endogenous hits drive liver injury in NAFLD and propel liver fibrosis and the progressing to advanced disease stages. NAFLD can be seen as the product of a complex interplay between gut microbiota, the immune response and metabolism. Thus, the challenge will be to understand its pathogenesis and to develop new therapeutic strategies.

Getting off tract: contributions of intraorgan microbiota to cancer in extraintestinal organs

The gastrointestinal ecosystem has received the most attention when examining the contributions of the human microbiome to health and disease. This concentration of effort is logical due to the overwhelming abundance of microbes in the gut coupled with the relative ease of sampling compared with other organs. However, the intestines are intimately connected to multiple extraintestinal organs, providing an opportunity for homeostatic microbial colonisation and pathogenesis in organs traditionally thought to be sterile or only transiently harbouring microbiota. These habitats are challenging to sample, and their low microbial biomass among large amounts of host tissue can make study challenging. Nevertheless, recent findings have shown that many extraintestinal organs that are intimately linked to the gut harbour stable microbiomes, which are colonised from the gut in selective manners and have highlighted not just the influence of the bacteriome but that of the mycobiome and virome on oncogenesis and health.

Gut liver brain axis in diseases: the implications for therapeutic interventions

Gut-liver-brain axis is a three-way highway of information interaction system among the gastrointestinal tract, liver, and nervous systems. In the past few decades, breakthrough progress has been made in the gut liver brain axis, mainly through understanding its formation mechanism and increasing treatment strategies. In this review, we discuss various complex networks including barrier permeability, gut hormones, gut microbial metabolites, vagus nerve, neurotransmitters, immunity, brain toxic metabolites, β-amyloid (Aβ) metabolism, and epigenetic regulation in the gut-liver-brain axis. Some therapies containing antibiotics, probiotics, prebiotics, synbiotics, fecal microbiota transplantation (FMT), polyphenols, low FODMAP diet and nanotechnology application regulate the gut liver brain axis. Besides, some special treatments targeting gut-liver axis include farnesoid X receptor (FXR) agonists, takeda G protein-coupled receptor 5 (TGR5) agonists, glucagon-like peptide-1 (GLP-1) receptor antagonists and fibroblast growth factor 19 (FGF19) analogs. Targeting gut-brain axis embraces cognitive behavioral therapy (CBT), antidepressants and tryptophan metabolism-related therapies. Targeting liver-brain axis contains epigenetic regulation and Aβ metabolism-related therapies. In the future, a better understanding of gut-liver-brain axis interactions will promote the development of novel preventative strategies and the discovery of precise therapeutic targets in multiple diseases.

Successful weight regain attenuation by autologous fecal microbiota transplantation is associated with non-core gut microbiota changes during weight loss; randomized controlled trial

We previously reported that autologous-fecal-microbiota-transplantation (aFMT), following 6 m of lifestyle intervention, attenuated subsequent weight regain and insulin rebound for participants consuming a high-polyphenol green-Mediterranean diet. Here, we explored whether specific changes in the core (abundant) vs. non-core (low-abundance) gut microbiome taxa fractions during the weight-loss phase (0-6 m) were differentially associated with weight maintenance following aFMT. Eighty-two abdominally obese/dyslipidemic participants (age = 52 years; 6 m weightloss = -8.3 kg) who provided fecal samples (0 m, 6 m) were included. Frozen 6 m's fecal samples were processed into 1 g, opaque and odorless aFMT capsules. Participants were randomly assigned to receive 100 capsules containing their own fecal microbiota or placebo over 8 m-14 m in ten administrations (adherence rate > 90%). Gut microbiome composition was evaluated using shotgun metagenomic sequencing. Non-core taxa were defined as ≤ 66% prevalence across participants. Overall, 450 species were analyzed. At baseline, 13.3% were classified as core, and Firmicutes presented the highest core proportion by phylum. During 6 m weight-loss phase, abundance of non-core species changed more than core species (P < .0001). Subject-specific changes in core and non-core taxa fractions were strongly correlated (Jaccard Index; r = 0.54; P < .001). Following aFMT treatment, only participants with a low 6 m change in core taxa, and a high change in non-core taxa, avoided 8-14 m weight regain (aFMT = -0.58 ± 2.4 kg, corresponding placebo group = 3.18 ± 3.5 kg; P = .02). In a linear regression model, low core/high non-core 6 m change was the only combination that was significantly associated with attenuated 8-14 m weight regain (P = .038; P = .002 for taxa patterns/treatment intervention interaction). High change in non-core, low-abundance taxa during weight-loss might mediate aFMT treatment success for weight loss maintenance.ClinicalTrials.gov: NCT03020186.

The role of faecal microbiota transplantation in chronic noncommunicable disorders

The gut microbiome plays a key role in influencing several pathways and functions involved in human health, including metabolism, protection against infection, and immune regulation. Perturbation of the gut microbiome is recognised as a pathogenic factor in several gastrointestinal and extraintestinal disorders, and is increasingly considered as a therapeutic target in these conditions. Faecal microbiota transplantation (FMT) is the transfer of the microbiota from healthy screened stool donors into the gut of affected patients, and is a well-established and highly effective treatment for recurrent Clostridioides difficile infection. Despite the mechanisms of efficacy of FMT not being fully understood, it has been investigated in several chronic noncommunicable disorders, with variable results. This review aims to give an overview of mechanisms of efficacy of FMT in chronic noncommunicable disorders, and to paint the current landscape of its investigation in these medical conditions, including inflammatory bowel disease (IBD), chronic liver disorders, and also extraintestinal autoimmune conditions.

Non-alcoholic fatty liver disease and gut microbial dysbiosis- underlying mechanisms and gut microbiota mediated treatment strategies

Non-alcoholic fatty liver disease (NAFLD) is by far the most prevalent form of liver disease worldwide. It's also the leading cause of liver-related hospitalizations and deaths. Furthermore, there is a link between obesity and NAFLD risk. A projected 25% of the world's population grieves from NAFLD, making it the most common chronic liver disorder. Several factors, such as obesity, oxidative stress, and insulin resistance, typically accompany NAFLD. Weight loss, lipid-lowering agents, thiazolidinediones, and metformin help prominently control NAFLD. Interestingly, pre-clinical studies demonstrate gut microbiota's potential causal role in NAFLD. Increased intestinal permeability and unhindered transport of microbial metabolites into the liver are the major disruptions due to gut microbiome dysbiosis, contributing to the development of NAFLD by dysregulating the gut-liver axis. Hence, altering the pathogenic bacterial population using probiotics, prebiotics, synbiotics, and fecal microbiota transplantation (FMT) could benefit patients with NAFLD. Therefore, it is crucial to acknowledge the importance of microbiota-mediated therapeutic approaches for NAFLD and comprehend the underlying mechanisms that establish a connection between NAFLD and gut microbiota. This review provides a comprehensive overview of the affiliation between dysbiosis of gut microbiota and the progress of NAFLD, as well as the potential benefits of prebiotic, probiotic, synbiotic supplementation, and FMT in obese individuals with NAFLD.

The Next Generation Fecal Microbiota Transplantation: To Transplant Bacteria or Virome

Fecal microbiota transplantation (FMT) has emerged as a promising therapeutic approach for dysbiosis-related diseases. However, the clinical practice of crude fecal transplants presents limitations in terms of acceptability and reproductivity. Consequently, two alternative solutions to FMT are developed: transplanting bacteria communities or virome. Advanced methods for transplanting bacteria mainly include washed microbiota transplantation and bacteria spores treatment. Transplanting the virome is also explored, with the development of fecal virome transplantation, which involves filtering the virome from feces. These approaches provide more palatable options for patients and healthcare providers while minimizing research heterogeneity. In general, the evolution of the next generation of FMT in global trends is fecal microbiota components transplantation which mainly focuses on transplanting bacteria or virome.

Gut microbiota, immunity, and bile acid metabolism: decoding metabolic disease interactions

In recent decades, the global prevalence of metabolic syndrome has surged, posing a significant public health challenge. Metabolic disorders, encompassing diabetes, obesity, nonalcoholic fatty liver disease, and polycystic ovarian syndrome, have been linked to alterations in the gut microbiota. Nonetheless, the connection between gut microbiota and host metabolic diseases warrants further investigation. In this review, we delve into the associations between various metabolic disorders and the gut microbiota, focusing on immune responses and bile acid (BA) metabolism. Notably, T helper cells, innate lymphoid cells, macrophages, and dendritic cells have been shown to modulate host metabolism through interactions with intestinal microorganisms and the release of cytokines. Furthermore, secondary BA metabolites, derived from the microbiota, are involved in the pathogenesis of metabolic diseases via the farnesoid X receptor and Takeda G protein-coupled receptor 5. By covering both aspects of this immune system-microorganism axis, we present a comprehensive overview of the roles played by the gut microbiota, microbiota-derived BA metabolites, and immune responses in metabolic diseases, as well as the interplay between these systems.

Small Intestinal Permeability and Metabolomic Profiles in Feces and Plasma Associate With Clinical Response in Patients With Active Psoriatic Arthritis Participating in a Fecal Microbiota Transplantation Trial: Exploratory Findings From the FLORA Trial

OBJECTIVE

We investigated intestinal permeability and fecal, plasma, and urine metabolomic profiles in methotrexate-treated active psoriatic arthritis (PsA) and how this related to clinical response following one sham or fecal microbiota transplantation (FMT).

METHODS

This exploratory study is based on the FLORA trial cohort, in which 31 patients with moderate-to-high peripheral PsA disease activity, despite at least 3 months of methotrexate-treatment, were included in a 26-week, double-blind, 1:1 randomized, sham-controlled trial. Participants were randomly allocated to receive either one healthy donor FMT (n = 15) or sham (n = 16) via gastroscopy. The primary trial end point was the proportion of treatment failures through 26 weeks. We performed a lactulose-to-mannitol ratio (LMR) test at baseline (n = 31) and at week 26 (n = 26) to assess small intestinal permeability. Metabolomic profiles in fecal, plasma, and urine samples collected at baseline, weeks 4, 12, and 26 were measured using 1 H Nuclear Magnetic Resonance.

RESULTS

Trial failures (n = 7) had significantly higher LMR compared with responders (n = 19) at week 26 (0.027 [0.017-0.33]) vs. 0.012 [0-0.064], P = 0.013), indicating increased intestinal permeability. Multivariate analysis revealed a significant model for responders (n = 19) versus failures (n = 12) at all time points based on their fecal (P < 0.0001) and plasma (P = 0.005) metabolomic profiles, whereas urine metabolomic profiles did not differ between groups (P = 1). Fecal N-acetyl glycoprotein GlycA correlated with Health Assessment Questionnaire Disability Index (coefficient = 0.50; P = 0.03) and fecal propionate correlated with American College of Rheumatology 20 response at week 26 (coefficient = 27, P = 0.02).

CONCLUSION

Intestinal permeability and fecal and plasma metabolomic profiles of patients with PsA were associated with the primary clinical trial end point, failure versus responder.

Deciphering the role of gut metabolites in non-alcoholic fatty liver disease

Perturbations in microbial abundance or diversity in the intestinal lumen leads to intestinal inflammation and disruption of intestinal membrane which eventually facilitates the translocation of microbial metabolites or whole microbes to the liver and other organs through portal vein. This process of translocation finally leads to multitude of health disorders. In this review, we are going to focus on the mechanisms by which gut metabolites like SCFAs, tryptophan (Trp) metabolites, bile acids (BAs), ethanol, and choline can either cause the development/progression of non-alcoholic fatty liver disease (NAFLD) or serves as a therapeutic treatment for the disease. Alterations in some metabolites like SCFAs, Trp metabolites, etc., can serve as biomarker molecules whereas presence of specific metabolites like ethanol definitely leads to disease progression. Thus, proper understanding of these mechanisms will subsequently help in designing of microbiome-based therapeutic approaches. Furthermore, we have also focussed on the role of dysbiosis on the mucosal immune system. In addition, we would also compile up the microbiome-based clinical trials which are currently undergoing for the treatment of NAFLD and non-alcoholic steatohepatitis (NASH). It has been observed that the use of microbiome-based approaches like prebiotics, probiotics, symbiotics, etc., can act as a beneficial treatment option but more research needs to be done to know how to manipulate the composition of gut microbes.

Exploring the diversity of blood microbiome during liver diseases: Unveiling Novel diagnostic and therapeutic Avenues

Liver diseases are a group of major metabolic and immune or inflammation related diseases caused due to various reasons including infection, abnormalities in immune system, genetic defects, and lifestyle habits. However, the cause-effect relationship is not completely understood in liver disease. The role of microbiome, particularly, the role of gut and oral microbiome in liver diseases has been extensively studied in recent years. More interestingly, the presence of blood microbiome and tissue microbiome has been identified in many liver diseases. The translocation of microbes from the gut into the portal circulation has been attributed to be the major reason for the presence of blood microbial components and its clinical implications in liver disorders. Besides microbial translocation, Pathogen associated Molecular Patterns (PAMPs) derived from gut microbiota might also translocate. The presence of blood microbiome in liver disease has been reviewed earlier. However, the role of blood microbiome as a biomarker and therapeutic target in liver diseases has not been analysed earlier. In this review, we confabulate the origin and physiology of blood microbiome and blood microbial components in relation to the progression and pathogenesis of liver disease. In conclusion, we discuss the translational perspectives targeting the blood microbial components in the diagnosis and therapy of liver disease.

Therapeutic modulation of the liver immune microenvironment

Inflammation is a hallmark of progressive liver diseases such as chronic viral or immune-mediated hepatitis, alcohol-associated liver disease, and NAFLD. Preclinical and clinical studies have provided robust evidence that cytokines and related cellular stress sensors in innate and adaptive immunity orchestrate hepatic disease processes. Unresolved inflammation and liver injury result in hepatic scarring, fibrosis, and cirrhosis, which may culminate in HCC. Liver diseases are accompanied by gut dysbiosis and a bloom of pathobionts, fueling hepatic inflammation. Anti-inflammatory strategies are extensively used to treat human immune-mediated conditions beyond the liver, while evidence for immunomodulatory therapies and cell therapy-based strategies in liver diseases is only emerging. The development and establishment of novel immunomodulatory therapies for chronic liver diseases has been dampened by several clinical challenges, such as invasive monitoring of therapeutic efficacy with liver biopsy in clinical trials and risk of DILI in several studies. Such aspects prevented advancements of novel medical therapies for chronic inflammatory liver diseases. New concepts modulating the liver immune environment are studied and eagerly awaited to improve the management of chronic liver diseases in the future.

The gut-liver axis and gut microbiota in health and liver disease

The trillions of microorganisms in the human intestine are important regulators of health, and disruptions in the gut microbial communities can cause disease. The gut, liver and immune system have a symbiotic relationship with these microorganisms. Environmental factors, such as high-fat diets and alcohol consumption, can disrupt and alter microbial communities. This dysbiosis can lead to dysfunction of the intestinal barrier, translocation of microbial components to the liver and development or progression of liver disease. Changes in metabolites produced by gut microorganisms can also contribute to liver disease. In this Review, we discuss the importance of the gut microbiota in maintenance of health and the alterations in microbial mediators that contribute to liver disease. We present strategies for modulation of the intestinal microbiota and/or their metabolites as potential treatments for liver disease.

Fecal microbiota transplantation improves hepatic fibro-inflammation via regulating oxidative stress in experimental NASH

Nonalcoholic steatohepatitis (NASH) is associated with imbalance of gut microbiome, indicating participation of gut environment in hepatic health status. Therefore, modulating gut environment via fecal microbiota transplantation (FMT) is a promising therapeutic procedure for NASH patients. However, the effect and mechanism of the FMT remains largely unknown. Here, we investigated the gut-liver axis to understand the FMT-mediated hepatic improvement in NASH. Feces from specific pathogen free mice were infused allogeneically into gastrointestinal tract of mice fed with high fat, high cholesterol and fructose (HFHCF), resulting in suppressing hepatic pathogenic events, featured by decreasing inflammatory and fibrotic mediators. The FMT elevated NF-E2-related factor 2 (NRF2), a key transcription factor that regulates antioxidant enzymes, in livers. The HFHCF-induced NASH increased intestinal permeability with abundant Facklamia and Aerococcus, an imbalanced gut environment that was significantly improved by the FMT, characterized with restoration of intestinal barrier function and an enrichment of Clostridium. Notably, the gut environment created by FMT was inferred to produce metabolites from the aromatic biogenic amine degradation pathway, specifically 4-hydroxyphenylacetic acid (4-HPA), which is known to ameliorate liver injury. We suggest that gut-derived molecules, related to hepatic improvement such as 4-HPA are the potential therapeutic agents for preventing and treating NASH.

Gut microbiome and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has become the most prevalent chronic liver disease globally and imposed a heavy economic burden on society and individuals. To date, the pathological process of NAFLD is not yet fully elucidated. Compelling evidences have demonstrated the pivotal role of gut microbiota in the pathogenesis of NAFLD, and gut dysbiosis has been commonly observed in patients with NAFLD. Gut dysbiosis impairs gut permeability, allowing the translocation of bacterial products such as lipopolysaccharides (LPS), short-chain fatty acids (SCFAs), and ethanol to the liver via portal blood flow. This review aimed to shed light on the underlying mechanisms by which gut microbiota influences the development and progression of NAFLD. In addition, the potential application of gut microbiome as a non-invasive diagnostic tool and a novel therapeutical target was reviewed.

The Intestinal Microbiota in the Development of Chronic Liver Disease: Current Status

Chronic liver disease (CLD) is a significant global health burden, leading to millions of deaths annually. The gut-liver axis plays a pivotal role in this context, allowing the transport of gut-derived products directly to the liver, as well as biological compounds from the liver to the intestine. The gut microbiota plays a significant role in maintaining the health of the digestive system. A change in gut microbiome composition as seen in dysbiosis is associated with immune dysregulation, altered energy and gut hormone regulation, and increased intestinal permeability, contributing to inflammatory mechanisms and damage to the liver, irrespective of the underlying etiology of CLD. The aim of this review is to present the current knowledge about the composition of the intestinal microbiome in healthy individuals and those with CLD, including the factors that affect this composition, the impact of the altered microbiome on the liver, and the mechanisms by which it occurs. Furthermore, this review analyzes the effects of gut microbiome modulation on the course of CLD, by using pharmacotherapy, nutrition, fecal microbiota transplantation, supplements, and probiotics. This review opens avenues for the translation of knowledge about gut-liver interplay into clinical practice as an additional tool to fight CLD and its complications.

New Insights into the Pathogenesis of Metabolic-Associated Fatty Liver Disease (MAFLD): Gut-Liver-Heart Crosstalk

Metabolism-associated fatty liver disease (MAFLD) is a multifaceted disease that involves complex interactions between various organs, including the gut and heart. It is defined by hepatic lipid accumulation and is related to metabolic dysfunction, obesity, and diabetes. Understanding the intricate interplay of the gut-liver-heart crosstalk is crucial for unraveling the complexities of MAFLD and developing effective treatment and prevention strategies. The gut-liver crosstalk participates in the regulation of the metabolic and inflammatory processes through host-microbiome interactions. Gut microbiota have been associated with the development and progression of MAFLD, and its dysbiosis contributes to insulin resistance, inflammation, and oxidative stress. Metabolites derived from the gut microbiota enter the systemic circulation and influence both the liver and heart, resulting in the gut-liver-heart axis playing an important role in MAFLD. Furthermore, growing evidence suggests that insulin resistance, endothelial dysfunction, and systemic inflammation in MAFLD may contribute to an increased risk of cardiovascular disease (CVD). Additionally, the dysregulation of lipid metabolism in MAFLD may also lead to cardiac dysfunction and heart failure. Overall, the crosstalk between the liver and heart involves a complex interplay of molecular pathways that contribute to the development of CVD in patients with MAFLD. This review emphasizes the current understanding of the gut-liver-heart crosstalk as a foundation for optimizing patient outcomes with MAFLD.

The Intestinal Microbiome and the Metabolic Syndrome-How Its Manipulation May Affect Metabolic-Associated Fatty Liver Disease (MAFLD)

Metabolic-associated fatty liver disease (MAFLD) is now the predominant liver disease worldwide consequent to the epidemic of obesity. The intestinal microbiome (IM), consisting of the bacteria, fungi, archaea, and viruses residing in the gastrointestinal tract, plays an important role in human metabolism and preserving the epithelial barrier function. Disturbances in the IM have been shown to influence the development and progression of MAFLD and play a role in the development of metabolic syndrome (MS). The main treatment for MAFLD involves lifestyle changes, which also influence the IM. Manipulation of the IM by fecal microbial transplantation (FMT) has been approved for the treatment of recurrent Closteroides difficile infection. This may be administered by endoscopic administration from the lower or upper GI tract. Other methods of administration include nasogastric tube, enema, and oral capsules of stool from healthy donors. In this narrative review, we elaborate on the role of the IM in developing MS and MAFLD and on the current experience with IM modulation by FMT on MAFLD.

The role of gut microbiome and fecal microbiota transplantation in liver cancer and related complications: mechanisms and therapeutic potentials

Liver cancer is the sixth commonest cancer and the third leading cause of cancer mortality worldwide. Accumulating evidence suggests a pivotal role of the gut microbiome in the progression of chronic liver disease and the subsequent development of liver cancer. Additionally, gut microbiome has been shown to contribute to the hosts’ antitumor responses following immunotherapy and chemotherapy for liver cancers, highlighting the therapeutic potential of gut microbiome modulation in enhancing treatment efficacy and reducing drug resistance. Fecal microbiota transplantation (FMT), a novel therapeutic modality to deliver a healthy donor's stool by endoscopy or capsule, has demonstrated potential in managing liver diseases and cancers by restoring and modulating the recipient’s gut microbiome composition. However, existing data on the clinical application of FMT in liver cancers are still limited. This review summarizes the underlying roles and mechanisms of gut microbiome in liver cancer and discusses the therapeutic potential of FMT in liver cancer treatment and the management of its related complications (e.g., hepatic encephalopathy).

Follicle-stimulating hormone is negatively associated with nonalcoholic fatty liver disease in a Chinese elderly population: a retrospective observational study

BACKGROUND

Several studies have explored the connection between follicle-stimulating hormone (FSH) and nonalcoholic fatty liver disease (NAFLD). However, the impact of FSH elevation on NAFLD remains a topic of debate. Hence, this investigation aimed to evaluate the potential correlation between FSH levels and NAFLD in the aging population.

METHODS

This was a retrospective observational cross-sectional study between July 2017 and August 2018 in our hospital. We used data obtained from 455 patients over 60 years old. Anthropometrics and laboratory tests were performed for each patient. NAFLD was diagnosed by sonographic features and the fatty liver index (LFI).

RESULTS

Of the 455 patients, 200 (43.96%) had NAFLD on their ultrasound and 169 (37.14%) had NAFLD according to the LFI. An intraclass correlation coefficient of the two methods was 80.4% (P < 0.001). People with NAFLD on their ultrasound showed lower FSH levels (52.68 vs. 61.39 IU/L) and more unfavorable metabolic profiles. FSH was negatively correlated with age, alanine aminotransferase, estradiol, testosterone, systolic blood pressure, waist, body mass index, fasting blood glucose, postload plasma glucose and positive associated with total cholesterol, high-density lipoprotein-cholesterol and low-density lipoprotein-cholesterol by Spearman correlation analysis (all P < 0.05). By controlling for all confounding factors, the odds ratios (OR) of FSH for NAFLD were determined in elderly individuals, both men and women, aged 60-70 years and over 70 years. These ORs were found to be 0.937, 0.982, 0.983, and 0.973, respectively, with corresponding 95% confidence intervals (CI) of 0.892-0.984 (P = 0.009), 0.971-0.993 (P = 0.002), 0.967-0.999 (P = 0.033), and 0.958-0.989 (P = 0.001). In addition, our findings demonstrated no significant correlation between FSH and advanced fibrosis when adjusting for potential covariates. The OR for advanced fibrosis was 0.979 (95% CI, 0.938-1.022, P = 0.339). Additionally, ROC curve analysis showed an optimal cut-off value of 66.91 for women and 15.25 for men for NAFLD diagnosis.

CONCLUSIONS

There was an inverse relationship observed between levels of FSH in the blood serum and NAFLD in the elderly population. These findings suggest that reduced FSH levels might serve as a potential risk factor or biomarker for NAFLD in the elderly.

Fresh Washed Microbiota Transplantation Alters Gut Microbiota Metabolites to Ameliorate Sleeping Disorder Symptom of Autistic Children

Accumulating studies have raised concerns about gut dysbiosis associating autism spectrum disorder (ASD) and its related symptoms. However, the effect of gut microbiota modification on the Chinese ASD population and its underlying mechanism were still elusive. Herein, we enrolled 24 ASD children to perform the first course of fresh washed microbiota transplantation (WMT), 18 patients decided to participate the second course, 13 of which stayed to participate the third course, and there were 8 patients at the fourth course. Then we evaluated the effects of fresh WMT on these patients and their related symptoms. Our results found that the sleeping disorder symptom was positively interrelated to ASD, fresh WMT significantly alleviated ASD and its sleeping disorder and constipation symptoms. In addition, WMT stably and continuously downregulated Bacteroides/Flavonifractor/Parasutterella while upregulated Prevotella_9 to decrease toxic metabolic production and improve detoxification by regulating glycolysis/myo-inositol/D-glucuronide/D-glucarate degradation, L-1,2-propanediol degradation, fatty acid β-oxidation. Thus, our results suggested that fresh WMT moderated gut microbiome to improve the behavioral and sleeping disorder symptoms of ASD via decrease toxic metabolic production and improve detoxification. Which thus provides a promising gut ecological strategy for ASD children and its related symptoms treatments.

Immunological mechanisms of inflammatory diseases caused by gut microbiota dysbiosis: A review

The gut microbiota is indispensable for maintaining host health by enhancing the host's digestive capacity, safeguarding the intestinal epithelial barrier, and preventing pathogen invasion. Additionally, the gut microbiota exhibits a bidirectional interaction with the host immune system and promotes the immune system of the host to mature. Dysbiosis of the gut microbiota, primarily caused by factors such as host genetic susceptibility, age, BMI, diet, and drug abuse, is a significant contributor to inflammatory diseases. However, the mechanisms underlying inflammatory diseases resulting from gut microbiota dysbiosis lack systematic categorization. In this study, we summarize the normal physiological functions of symbiotic microbiota in a healthy state and demonstrate that when dysbiosis occurs due to various external factors, the normal physiological functions of the gut microbiota are lost, leading to pathological damage to the intestinal lining, metabolic disorders, and intestinal barrier damage. This, in turn, triggers immune system disorders and eventually causes inflammatory diseases in various systems. These discoveries provide fresh perspectives on how to diagnose and treat inflammatory diseases. However, the unrecognized variables that might affect the link between inflammatory illnesses and gut microbiota, need further studies and extensive basic and clinical research will still be required to investigate this relationship in the future.

Manipulation of the intestinal microbiome-a slow journey to primetime

The gut microbiota has important functions in the regulation of normal body functions. Alterations of the microbiota are being increasingly linked to various disease states. The microbiome has been manipulated via the administration of stool from animals or humans, for more than 1000 years. Currently, fecal microbiota transplantation can be performed via endoscopic administration of fecal matter to the duodenum or colon or via capsules of lyophilized stools. More recently fecal microbial transplantation has been shown to be very effective for recurrent Clostridoides difficile infection (CDI). In addition there is some evidence of efficacy in the metabolic syndrome and its hepatic manifestation, metabolic associated fatty liver disease (MAFLD), irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). We review the current literature regarding the microbiome and the pathogenesis and treatment of CDI, MAFLD, IBS and IBD.

Assessing the impact of pregnancy and birth factors on the maternal and infant microbiota

Background: The microbiota acquired at birth is known to play an intimate role in later life health and disease and has been shown to be affected by the mode of birth. There has been recent interest in microbiota correction by maternal vaginal seeding in Cesarean section-born infants; however, the safety of this practice has been debated. The aim of this study was to assess how other factors, such as timing of sampling, maternal obesity, vaginal Group B Streptococcus colonization (GBS), and antibiotic exposure, affect the maternal and infant microbiota. Methods: Maternal vaginal and saliva samples were collected at three time periods: 35-37 weeks gestation (prenatal), within 24-36 hours after birth (birth), and at ~6 weeks postpartum. Infant saliva and stool samples were collected at ~6 weeks postpartum. 16S rRNA amplicon sequencing was utilized to assess the taxonomic and inferred functional compositions of the bacterial communities from both mothers and infants. Results: Samples from 36 mothers and 32 infants were obtained. Gestational age, breastfeeding, mode of birth, and gravidity were associated with taxonomic alterations in the infant samples, while obesity, antibiotic use, and GBS status were not. Maternal samples were predominantly affected by time, whereby significant alterations including increased microbial diversity were seen at birth and persisted to 6 weeks postpartum. Conclusion: This study provides information on the relationship between health and delivery factors and changes in vaginal and infant microbiota. These results may better direct clinicians and mothers in optimizing the infant microbiota towards health during infancy and later life.

Pharmacotherapies of NAFLD: updated opportunities based on metabolic intervention

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease that is becoming increasingly prevalent, and it ranges from simple steatosis to cirrhosis. However, there is still a lack of pharmacotherapeutic strategies approved by the Food and Drug Administration, which results in a higher risk of death related to carcinoma and cardiovascular complications. Of note, it is well established that the pathogenesis of NAFLD is tightly associated with whole metabolic dysfunction. Thus, targeting interconnected metabolic conditions could present promising benefits to NAFLD, according to a number of clinical studies. Here, we summarize the metabolic characteristics of the development of NAFLD, including glucose metabolism, lipid metabolism and intestinal metabolism, and provide insight into pharmacological targets. In addition, we present updates on the progresses in the development of pharmacotherapeutic strategies based on metabolic intervention globally, which could lead to new opportunities for NAFLD drug development.

Interaction between mucus layer and gut microbiota in non-alcoholic fatty liver disease: Soil and seeds

ABSTRACT

The intestinal mucus layer is a barrier that separates intestinal contents and epithelial cells, as well as acts as the "mucus layer-soil" for intestinal flora adhesion and colonization. Its structural and functional integrity is crucial to human health. Intestinal mucus is regulated by factors such as diet, living habits, hormones, neurotransmitters, cytokines, and intestinal flora. The mucus layer's thickness, viscosity, porosity, growth rate, and glycosylation status affect the structure of the gut flora colonized on it. The interaction between "mucus layer-soil" and "gut bacteria-seed" is an important factor leading to the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Probiotics, prebiotics, fecal microbiota transplantation (FMT), and wash microbial transplantation are efficient methods for managing NAFLD, but their long-term efficacy is poor. FMT is focused on achieving the goal of treating diseases by enhancing the "gut bacteria-seed". However, a lack of effective repair and management of the "mucus layer-soil" may be a reason why "seeds" cannot be well colonized and grow in the host gut, as the thinning and destruction of the "mucus layer-soil" is an early symptom of NAFLD. This review summarizes the existing correlation between intestinal mucus and gut microbiota, as well as the pathogenesis of NAFLD, and proposes a new perspective that "mucus layer-soil" restoration combined with "gut bacteria-seed" FMT may be one of the most effective future strategies for enhancing the long-term efficacy of NAFLD treatment.

The Impact of Nutrition, Physical Activity, Beneficial Microbes, and Fecal Microbiota Transplant for Improving Health

The recognition that microbes are integral to human life has led to studies on how to manipulate them in favor of health outcomes. To date, there has been no conjoint recommendation for the intake of dietary compounds that can complement the ingested organisms in terms of promoting an improved health outcome. The aim of this review is to discuss how beneficial microbes in the form of probiotics, fermented foods, and donor feces are being used to manage health. In addition, we explore the rationale for selecting beneficial microbial strains and aligning diets to accommodate their propagation in the gut. A pilot clinical trial design is presented to examine the effects of probiotics and exercise in patients with phenylketonuria (PKU); it is the most common inborn error of amino acid metabolism, and it is a complication that requires lifelong dietary intervention. The example design is provided to illustrate the importance of using omics technology to see if the intervention elevates neuroactive biogenic amines in the plasma; increases the abundance of Eubacterium rectale, Coprococcus eutactus, Akkermansia muciniphila, or Butyricicoccus; and increases Escherichia/Shigella in the gut, all as markers of improved health. By emphasizing the combined importance of diet, microbial supplements, and the gut microbiome, we hope that future studies will better align these components, not only to improve outcomes, but also to enhance our understanding of the mechanisms.

Future indications and clinical management for fecal microbiota transplantation (FMT) in immuno-oncology

The gut microbiota has rapidly emerged as one of the "hallmarks of cancers" and a key contributor to cancer immunotherapy. Metagenomics profiling has established the link between microbiota compositions and immune checkpoint inhibitors response and toxicity, while murine experiments demonstrating the synergistic benefits of microbiota modification with immune checkpoint inhibitors (ICIs) pave a clear path for translation. Fecal microbiota transplantation (FMT) is one of the most effective treatments for patients with Clostridioides difficile, but its utility in other disease contexts has been limited. Nonetheless, promising data from the first trials combining FMT with ICIs have provided strong clinical rationale to pursue this strategy as a novel therapeutic avenue. In addition to the safety considerations surrounding new and emerging pathogens potentially transmissible by FMT, several other challenges must be overcome in order to validate the use of FMT as a therapeutic option in oncology. In this review, we will explore how the lessons learned from FMT in other specialties will help shape the design and development of FMT in the immuno-oncology arena.

Research Priorities for Precision Medicine in NAFLD

NAFLD is a multisystem condition and the leading cause of chronic liver disease globally. There are no approved NAFLD-specific dugs. To advance in the prevention and treatment of NAFLD, there is a clear need to better understand the pathophysiology and genetic and environmental risk factors, identify subphenotypes, and develop personalized and precision medicine. In this review, we discuss the main NAFLD research priorities, with a particular focus on socioeconomic factors, interindividual variations, limitations of current NAFLD clinical trials, multidisciplinary models of care, and novel approaches in the management of patients with NAFLD.

Intestinal Barrier Function in the Pathogenesis of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide. The mechanisms involved in NAFLD onset are complicated and multifactorial. Recent literature has indicated that altered intestinal barrier function is related to the occurrence and progression of liver disease. The intestinal barrier is important for absorbing nutrients and electrolytes and for defending against toxins and antigens in the enteric environment. Major mechanisms by which the intestinal barrier influences the development of NAFLD involve the altered epithelial layer, decreased intracellular junction integrity, and increased intestinal barrier permeability. Increased intestinal permeability leads to luminal dysbiosis and allows the translocation of pathogenic bacteria and metabolites into the liver, inducing inflammation, immune response, and hepatocyte injury in NAFLD. Although research has been directed to NAFLD in recent decades, the pathophysiological changes in NAFLD initiation and progression are still not completely understood, and the therapeutic targets remain limited. A deeper understanding on the correlation between NAFLD pathogenesis and intestinal barrier regulation must be attained. Therefore, in this review, the components of the intestinal barrier and their respective functions and disruptions during the progression of NAFLD are discussed.

Gut-liver axis: barriers and functional circuits

The gut and the liver are characterized by mutual interactions between both organs, the microbiome, diet and other environmental factors. The sum of these interactions is conceptualized as the gut-liver axis. In this Review we discuss the gut-liver axis, concentrating on the barriers formed by the enterohepatic tissues to restrict gut-derived microorganisms, microbial stimuli and dietary constituents. In addition, we discuss the establishment of barriers in the gut and liver during development and their cooperative function in the adult host. We detail the interplay between microbial and dietary metabolites, the intestinal epithelium, vascular endothelium, the immune system and the various host soluble factors, and how this interplay establishes a homeostatic balance in the healthy gut and liver. Finally, we highlight how this balance is disrupted in diseases of the gut and liver, outline the existing therapeutics and describe the cutting-edge discoveries that could lead to the development of novel treatment approaches.

The Role of Probiotics and Their Metabolites in the Treatment of Depression

Depression is a common and complex mental and emotional disorder that causes disability, morbidity, and quite often mortality around the world. Depression is closely related to several physical and metabolic conditions causing metabolic depression. Studies have indicated that there is a relationship between the intestinal microbiota and the brain, known as the gut–brain axis. While this microbiota–gut–brain connection is disturbed, dysfunctions of the brain, immune system, endocrine system, and gastrointestinal tract occur. Numerous studies show that intestinal dysbiosis characterized by abnormal microbiota and dysfunction of the microbiota–gut–brain axis could be a direct cause of mental and emotional disorders. Traditional treatment of depression includes psychotherapy and pharmacotherapy, and it mainly targets the brain. However, restoration of the intestinal microbiota and functions of the gut–brain axis via using probiotics, their metabolites, prebiotics, and healthy diet may alleviate depressive symptoms. Administration of probiotics labeled as psychobiotics and their metabolites as metabiotics, especially as an adjuvant to antidepressants, improves mental disorders. It is a new approach to the prevention, management, and treatment of mental and emotional illnesses, particularly major depressive disorder and metabolic depression. For the effectiveness of antidepressant therapy, psychobiotics should be administered at a dose higher than 1 billion CFU/day for at least 8 weeks.

Geniposide plus chlorogenic acid reverses non-alcoholic steatohepatitis via regulation of gut microbiota and bile acid signaling in a mouse model in vivo

Background: Geniposide and chlorogenic acid are the major active ingredients in Yinchenhao Decoction and are widely used as herbal medicines in Asia. This study further assessed their effects on improvement of non-alcoholic steatohepatitis (NASH) in a mouse model and explored the underlying molecular events in vivo.

Methods: Male C57BL/6 and farnesoid X receptor knockout (FXR−/−) mice were used to establish the NASH model and were treated with or without geniposide, chlorogenic acid, obeticholic acid (OCA), and antibiotics for assessment of the serum and tissue levels of various biochemical parameters, bile acid, DNA sequencing of bacterial 16S amplicon, protein expression, and histology.

Results: The data showed that the combination of geniposide and chlorogenic acid (GC) reduced the levels of blood and liver lipids, serum alanine aminotransferase (ALT), serum aspartate aminotransferase (AST), and the liver tissue index in NASH mice. In addition, GC treatment improved the intestinal microbial disorders in the NASH mice as well as the intestinal and serum bile acid metabolism. At the gene level, GC induced FXR signaling, i.e., increased the expression of FXR, small heterodimer partner (SHP), and bile salt export pump (BSEP) in liver tissues and fibroblast growth factor 15 (FGF15) expression in the ileal tissues of NASH mice. However, antibiotics (ampicillin, neomycin, vancomycin, and tinidazole) in drinking water (ADW) reversed the effect of GC on NASH and altered the gut microbiota in NASH mice in vivo. Furthermore, GC treatment failed to improve NASH in the FXR−/− mouse NASH model in vivo, indicating that the effectiveness of GC treatment might be through FXR signaling activation.

Conclusion: GC was able to alleviate NASH by improving the gut microbiome and activating FXR signaling; its effect was better than each individual agent alone.

Current, emerging, and potential therapies for non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) has been identified as the most common chronic liver disease worldwide, with a growing incidence. NAFLD is considered the hepatic manifestation of a metabolic syndrome that emerges from multiple factors (e.g., oxidative stress, metabolic disorders, endoplasmic reticulum stress, cell death, and inflammation). Non-alcoholic steatohepatitis (NASH), an advanced form of NAFLD, has been reported to be a leading cause of cirrhosis and hepatic carcinoma, and it is progressing rapidly. Since there is no approved pharmacotherapy for NASH, a considerable number of therapeutic targets have emerged with the deepening of the research on NASH pathogenesis. In this study, the therapeutic potential and properties of regulating metabolism, the gut microbiome, antioxidant, microRNA, inhibiting apoptosis, targeting ferroptosis, and stem cell-based therapy in NASH are reviewed and evaluated. Since the single-drug treatment of NASH is affected by individual heterogeneous responses and side effects, it is imperative to precisely carry out targeted therapy with low toxicity. Lastly, targeted therapeutic agent delivery based on exosomes is proposed in this study, such that drugs with different mechanisms can be incorporated to generate high-efficiency and low-toxicity individualized medicine.

Faecal Microbiota Transplantation, Paving the Way to Treat Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is currently the most prevalent cause of chronic liver disease (CLD). Currently, the only therapeutic recommendation available is a lifestyle change. However, adherence to this approach is often difficult to guarantee. Alteration of the microbiota and an increase in intestinal permeability seem to be key in the development and progression of NAFLD. Therefore, the manipulation of microbiota seems to provide a promising therapeutic strategy. One way to do so is through faecal microbiota transplantation (FMT). Here, we summarize the key aspects of FMT, detail its current indications and highlight the most recent advances in NAFLD.

Microbiome-liver crosstalk: A multihit therapeutic target for liver disease

Liver disease has become a leading cause of death, particularly in the West, where it is attributed to more than two million deaths annually. The correlation between gut microbiota and liver disease is still not fully understood. However, it is well known that gut dysbiosis accompanied by a leaky gut causes an increase in lipopolysaccharides in circulation, which in turn evoke massive hepatic inflammation promoting liver cirrhosis. Microbial dysbiosis also leads to poor bile acid metabolism and low short-chain fatty acids, all of which exacerbate the inflammatory response of liver cells. Gut microbial homeostasis is maintained through intricate processes that ensure that commensal microbes adapt to the low oxygen potential of the gut and that they rapidly occupy all the intestinal niches, thus outcompeting any potential pathogens for available nutrients. The crosstalk between the gut microbiota and its metabolites also guarantee an intact gut barrier. These processes that protect against destabilization of gut microbes by potential entry of pathogenic bacteria are collectively called colonization resistance and are equally essential for liver health. In this review, we shall investigate how the mechanisms of colonization resistance influence the liver in health and disease and the microbial-liver crosstalk potential as therapeutic target areas.

Translational characterization of the temporal dynamics of metabolic dysfunctions in liver, adipose tissue and the gut during diet-induced NASH development in Ldlr-/-.Leiden mice

Background

NAFLD progression, from steatosis to inflammation and fibrosis, results from an interplay of intra- and extrahepatic mechanisms. Disease drivers likely include signals from white adipose tissue (WAT) and gut. However, the temporal dynamics of disease development remain poorly understood.

Methods

High-fat-diet (HFD)-fed Ldlr-/-.Leiden mice were compared to chow-fed controls. At t = 0, 8, 16, 28 and 38w mice were euthanized, and liver, WAT depots and gut were analyzed biochemically, histologically and by lipidomics and transcriptomics together with circulating factors to investigate the sequence of pathogenic events and organ cross-talk during NAFLD development.

Results

HFD-induced obesity was associated with an increase in visceral fat, plasma lipids and hyperinsulinemia at t = 8w, along with increased liver steatosis and circulating liver damage biomarkers. In parallel, upstream regulator analysis predicted that lipid catabolism regulators were deactivated and lipid synthesis regulators were activated. Subsequently, hepatocyte hypertrophy, oxidative stress and hepatic inflammation developed. Hepatic collagen accumulated from t = 16 w and became pronounced at t = 28-38 w. Epididymal WAT was maximally hypertrophic from t = 8 w, which coincided with inflammation development. Mesenteric and subcutaneous WAT hypertrophy developed slower and did not appear to reach a maximum, with minimal inflammation. In gut, HFD significantly increased permeability, induced a shift in microbiota composition from t = 8 w and changed circulating gut-derived metabolites.

Conclusion

HFD-fed Ldlr-/-.Leiden mice develop obesity, dyslipidemia and insulin resistance, essentially as observed in obese NAFLD patients, underlining their translational value. We demonstrate that marked epididymal-WAT inflammation, and gut permeability and dysbiosis precede the development of NAFLD stressing the importance of a multiple-organ approach in the prevention and treatment of NAFLD.

Microbiota-Liver Diseases Interactions

Gut microbiota regulates essential processes of host metabolism and physiology: synthesis of vitamins, digestion of foods non-digestible by the host (such as fibers), and-most important-protects the digestive tract from pathogens. In this study, we focus on the CRISPR/Cas9 technology, which is extensively used to correct multiple diseases, including liver diseases. Then, we discuss the non-alcoholic fatty liver disease (NAFLD), affecting more than 25% of the global population; colorectal cancer (CRC) is second in mortality. We give space to rarely discussed topics, such as pathobionts and multiple mutations. Pathobionts help to understand the origin and complexity of the microbiota. Since several types of cancers have as target the gut, it is vital extending the research of multiple mutations to the type of cancers affecting the gut-liver axis.

Dendrobium officinale alleviates high-fat diet-induced nonalcoholic steatohepatitis by modulating gut microbiota

Introduction

The gut microbiota plays an important role in the development of nonalcoholic steatohepatitis (NASH). This study investigated the preventive effect of Dendrobium officinale (DO), including whether its effect was related to the gut microbiota, intestinal permeability and liver inflammation.

Methods

A NASH model was established in rats using a high-fat diet (HFD) and gavage with different doses of DO or Atorvastatin Calcium (AT) for 10 weeks. Body weight and body mass index along with liver appearance, weight, index, pathology, and biochemistry were measured to assess the preventive effects of DO on NASH rats. Changes in the gut microbiota were analyzed by 16S rRNA sequencing, and intestinal permeability and liver inflammation were determined to explore the mechanism by which DO treatment prevented NASH.

Results

Pathological and biochemical indexes showed that DO was able to protect rats against HFD-induced hepatic steatosis and inflammation. Results of 16S rRNA sequencing showed that Proteobacteria, Romboutsia, Turicibacter, Lachnoclostridium, Blautia, Ruminococcus_torques_group, Sutterella, Escherichia-Shigella, Prevotella, Alistipes, and Lactobacillus_acidophilus differed significantly at the phylum, genus, and species levels. DO treatment modulated the diversity, richness, and evenness of gut microbiota, downregulated the abundance of the Gram-negative bacteria Proteobacteria, Sutterella, and Escherichia-Shigella, and reduced gut-derived lipopolysaccharide (LPS) levels. DO also restored expression of the tight junction proteins, zona occludens-1 (ZO-1), claudin-1, and occludin in the intestine and ameliorated the increased intestinal permeability caused by HFD, gut microbiota such as Turicibacter, Ruminococcus, Escherichia-Shigella, and Sutterella, and LPS. Lower intestinal permeability reduced LPS delivery to the liver, thus inhibiting TLR4 expression and nuclear factor-kappaB (NF-κB) nuclear translocation, improving liver inflammation.

Discussion

These results suggest that DO may alleviate NASH by regulating the gut microbiota, intestinal permeability, and liver inflammation.